Discover CircRes

Monthly summary & in-depth analysis of the research published in the Circulation Research journal

April 2024 Discover CircRes 04/18/2024

March 2024 Discover CircRes 03/21/2024

February 2024 Discover CircRes 02/15/2024

January 2024 Discover CircRes 01/18/2024

December 2023 Discover CircRes 12/21/2023

November 2023 Discover CircRes 11/16/2023

October 2023 Discover CircRes 10/19/2023

September 2023 Discover CircRes 09/21/2023

August 2023 Discover CircRes 08/17/2023

July 2023 Discover CircRes 07/20/2023

June 2023 Discover CircRes 06/15/2023

May 2023 Discover CircRes 05/18/2023

May 2023 Discover CircRes This month on Episode 48 of Discover CircRes, host Cynthia St. Hilaire highlights three original research articles featured in the April 28th issue of Circulation Research. This Episode also includes a discussion between Dr Mina Chung, Dr DeLisa Fairweather and Dr Milka Koupenova, who all contributed to manuscripts to the May 12th Compendium on Covid-19 and the Cardiovascular System. Article highlights: Heijman, et al. Chen, et al. Enzan, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh. Today, I'm going to be highlighting articles from our April 28th and May 12th issues of Circulation Research. I'm also going to have a chat with Dr Mina Chung, Dr DeLisa Fairweather and Dr Milka Koupenova, who all contributed to articles in the May 12th COVID Compendium. But before we have that interview, let's first talk about some highlights. The first article I want to present is titled Enhanced Calcium-Dependent SK-Channel Gating and Membrane Trafficking in Human Atrial Fibrillation. This article is coming from the University of Essen by Heijman and Zhou, et al. Atrial fibrillation is one of the most common forms of heart arrhythmia in humans and is characterized by irregular, often rapid heartbeats that can cause palpitations, dizziness and extreme fatigue. Atrial fibrillation can increase a person's risk of heart failure, and though treatments exist such as beta blockers, blood thinners and antiarrhythmia medications, they can have limited efficacy and side effects. A new family of drugs in development are those blocking small-conductance calcium-activated potassium channels called SK channels, which exhibit increased activity in animal models of AF and suppression of which attenuates the arrhythmia. In humans however, the relationship between SK channels and atrial fibrillation is less clear, at least in terms of SK channel mRNA levels. Because mRNA might not reflect actual channel activity, this group looked at just that and they found indeed that channel activity was increased in cardiomyocytes from atrial fibrillation patients compared to those from controls even though the mRNA and protein levels themselves were similar. The altered currents were instead due to changes in SK channel trafficking and membrane targeting. By confirming that SK channels play a role in human atrial fibrillation, this work supports the pursuit of SK channel inhibitors as possible new atrial fibrillation treatments. The next article I want to present is titled IL-37 Attenuates Platelet Activation and Thrombosis Through IL-1R8 Pathway. This article comes from Fudan University by Chen and Hong, et al. Thrombus formation followed by the rupture of a coronary plaque is a major pathophysiological step in the development of a myocardial infarction. Understanding the endogenous antithrombotic factors at play could provide insights and opportunities for developing treatments. With this in mind, Chen and Hong, et al. investigated the role of interleukin-1 receptor 8, or IL-1R8, which suppresses platelet aggregation in mice, and of IL-37, a newly discovered human interleukin that forms a complex with IL-1R8 and is found at increased levels in the blood of patients with myocardial infarction. Indeed, the amount of IL-37 in myocardial infarction patients negatively correlates with platelet aggregation. They also show that treatment of human platelets in vitro with IL-37 suppresses the cell's aggregation and does so in a concentration-dependent manner. Moreover, injection of the protein into the veins of mice inhibits thrombus development and better preserves heart function even after myocardial infarction. Such effects were not seen in mice lacking IL-1R8. This suggests IL-37's antithrombotic action depends on its interaction with the receptor. Together, the results suggest IL-37 could be developed as a antithrombotic agent for use in MI patients or indeed perhaps other thrombotic conditions. The last article I want to present before our interview is titled ZBP1 Protects Against Mitochondrial DNA-Induced Myocardial Inflammation in Failing Hearts. This article is coming from Kyushu University and is by Enzan, et al. Myocardial inflammation is a key factor in the pathological progression of heart failure and occurs when damaged mitochondria within the stricken cardiomyocyte release their DNA, triggering an innate inflammatory reaction. In a variety of cells, DNA sensors such as Z-DNA-binding protein 1 or ZBP1 are responsible for such mitochondrial DNA-induced inflammation. In theory then, it's conceivable that therapeutic suppression of ZBP1 might reduce myocardial inflammation in heart failure and preserve function. But as Enzan and colleagues have now discovered to their surprise, mice lacking ZBP1 exhibited worse, not better heart inflammation and more failure after induced myocardial infarction. Indeed, the test animals' hearts had increased infiltration of immune cells, production of inflammatory cytokines and fibrosis together with decreased function compared with the hearts of mice with normal ZBP1 levels. Experiments in rodent cardiomyocytes further confirmed that loss of ZBP1 exacerbated mitochondrial DNA-induced inflammatory cytokine production while overexpression of ZBP1 had the opposite effect. While the reason behind ZBP1's opposing roles in different cells is not yet clear, the finding suggests that boosting ZBP1 activity in the heart might be a strategy for mitigating heart inflammation after infarction. Cindy St. Hilaire: The May 12th issue of Circulation Research is our COVID compendium, which consists of a series of 10 reviews on all angles of COVID-19 as it relates to cardiovascular health and disease. Today, three of the authors of the articles in this series are here with me. Dr Mina Chung is a professor of medicine at the Cleveland Clinic. She and Dr Tamanna Singh and their colleagues wrote the article, A Post Pandemic Enigma: The Cardiovascular Impact of Post-Acute Sequelae of SARS-CoV-2. Dr DeLisa Fairweather, professor of medicine, immunology and clinical and translational science at the Mayo Clinic, and she and her colleagues penned the article, COVID-19 Myocarditis and Pericarditis. Dr Milka Koupenova is an assistant professor of medicine at the UMass Chan School of Medical and she led the group writing the article, Platelets and SARS-CoV-2 During COVID-19: Immunity, Thrombosis, and Beyond. Thank you all for joining me today. DeLisa Fairweather: Thank you so much for having us. Mina Chung: Thank you. Milka Koupenova: Thank you for having us, Cindy. Cindy St. Hilaire: In addition to these three articles, we have another seven that are on all different aspects of COVID. Dr Messinger's group wrote the article, Interaction of COVID-19 With Common Cardiovascular Disorders. Emily Tsai covered cell-specific mechanisms in the heart of COVID-19 patients. Mark Chappell and colleagues wrote about the renin-angiotensin system and sex differences in COVID-19. Michael Bristow covered vaccination-associated myocarditis and myocardial injury. Jow Loacalzo and colleagues covered repurposing drugs for the treatment of COVID-19 and its cardiovascular manifestations. Dr Stephen Holby covered multimodality cardiac imaging in COVID, and Arun Sharma covered microfluidic organ chips in stem cell models in the fight against COVID-19. Cindy St. Hilaire As of today, worldwide, there have been over six hundred million individuals infected with the virus and more than six and a half million have died from COVID-19. In the US, we are about a sixth of all of those deaths. Obviously now we're in 2023, the numbers of individuals getting infected and dying are much, much lower. As my husband read to me this morning, one doctor in Boston was quoted saying, "People are still getting wicked sick." In 75% of deaths, people have had underlying conditions and cardiovascular disease is found in about 60% of all those deaths. In the introduction to the compendium, you mentioned that the remarkable COVID-19 rapid response initiative released by the AHA, which again is the parent organization of Circ Research and this podcast, if I were to guess when that rapid response initiative started, I would've guessed well into the pandemic, but it was actually March 26th, 2020. I know in Pittsburgh, our labs have barely shut down. So how soon after we knew of SARS-CoV-2 and COVID, how soon after that did we know that there were cardiovascular complications? Mina Chung: I think we saw cardiovascular complications happening pretty early. We saw troponin increases very early. It was really amazing what AHA did in terms of this rapid response grant mechanism. You mentioned that the RFA was announced, first of all, putting it together by March 26th when we were just shutting down in March was pretty incredible to get even the RFA out. Then the grants were supposed to be submitted by April 6th and there were 750 grants that were put together and submitted. They were all reviewed within 10 days from 150 volunteer reviewers. The notices were distributed April 23rd, less than a month out. Cindy St. Hilaire: Amazing. Mina Chung: So this is an amazing, you're right, paradigm for grant requests and submissions and reviews. DeLisa Fairweather: For myocarditis, reports of that occurred almost immediately coming out of China, so it was incredibly rapid. Cindy St. Hilaire: Yeah, and that was a perfect lead up to my next question. Was myocarditis, I guess, the first link or the first clue that this was not just going to be a respiratory infection? DeLisa Fairweather: I think myocarditis appearing very early, especially it has a history both of being induced by viruses, but being strongly an autoimmune disease, the combination of both of those, I think, started to hint that something different was going to happen, although a lot of people probably didn't realize the significance of that right away. Cindy St. Hilaire: What other disease states, I guess I'm thinking viruses, but anything, what causes myocarditis and pericarditis normally and how unique is it that we are seeing this as a sequelae of COVID? DeLisa Fairweather: I think it's not surprising that we find it. Viruses around the world are the primary cause of myocarditis, although in South America, it's the parasite Trypanosoma cruzi. Really, many viruses that also we think target mitochondria, including SARS-CoV-2, have an important role in driving myocarditis. Also, we know that SARS-CoV-1 and MERS also reported myocarditis in those previous infections. We knew about it beforehand that they could cause myocarditis. Cindy St. Hilaire: Is it presenting differently in a COVID patient than say those South American patients with the... I forget the name of the organism you said, but does it come quickly or get worse quickly or is it all once you get it, it's the same progression? DeLisa Fairweather: Yeah. That's a good question. Basically, what we find is that no matter what the viral infection is, that myocarditis really appears for signs and symptoms and how we treat it identically and we see that with COVID-19. So that really isn't any different. Cindy St. Hilaire: Another huge observation that we noticed in COVID-19 patients, which was the increased risk of thrombic outcomes in the patients. Dr Koupenova, Milka, you are a world expert in platelets and viruses and so you and your team were leading the writing of that article. My guess is knowing what you know about platelets and viruses, this wasn't so surprising to you, but could you at least tell us the state of the field in terms of what we knew about viruses and platelets before COVID, before Feb 2020? Milka Koupenova: Before Feb 2020, we actually knew that influenza gets inside in platelets. It leads to not directly prothrombotic events, but it would lead to release of complement 3 from them. That complement 3 would actually increase the immunothrombosis by pushing neutrophils to release their DNA, forming aggregates. In cases when you have compromised endothelium and people with underlying conditions, you would expect certain thrombotic outcomes. That, we actually published 2019 and then 2020 hit. The difference between influenza and SARS-CoV-2, they're different viruses. They carry their genome in a different RNA strand. I remember thinking perhaps viruses are getting inside in platelets, but perhaps they do not. So we went through surprising discoveries that it seemed like it is another RNA virus. It also got into platelets. It was a bit hard to tweak things surrounding BSL-3 to tell you if the response was the same. It is still not very clear how much SARS or rather what receptor, particularly when it gets inside would induce an immune response. There are some literature showing the MDA5, but not for sure, may be responsible. But what we found is that once it gets in platelets, it just induces this profound activation of programmed cell death pathways and release of extracellular vesicles and all these prothrombotic, procoagulant form of content that can induce damage around, because platelets are everywhere. So that how it started in 2019 and surprisingly progressed to 2021 or 2020 without the plan of really studying this virus. Cindy St. Hilaire: How similar and how different is what you observe in platelets infected, obviously in the lab, so I know it's not exactly the same, but how similar and how different is it between the flu? Do you know all the differences yet? Milka Koupenova: No offense here, they don't get infected. Cindy St. Hilaire: Okay. Milka Koupenova: Done the proper research. The virus does not impact platelets, but induces the response. Cindy St. Hilaire: Okay. Milka Koupenova: That goes back to sensing mechanism. Thank goodness platelets don't get infected because we would be in a particularly bad situation, but they remove the infectious virus from the plasma from what we can see with function. Cindy St. Hilaire: Got it. So they're helping the cleanup process and in that cleaning up is where the virus within them activates. That is a really complicated mechanism. Milka Koupenova: Oh, they're sensing it in some form to alert the environment. It's hard to say how similar and how different they are unless you study them hint by hint next to each other. All I can tell is that particularly with SARS-C, you definitely see a lot more various kinds of extracellular vesicles coming out of them that you don't see the same way or rather through the same proportion with influenza. But what that means in how platelet activates the immune system with one versus the other, and that goes back to the prothrombotic mechanisms. That is exactly what needs to be studied and that was the call for this COVID compendium is to point out how much we have done as a team. As scientists who put heads together, as Mina said, superfast response, it's an amazing going back and looking at what happened to think of what we achieved. There is so much more, so much more that we do not understand how one contributes to all of these profound responses in the organs themselves, such as myocarditis. We see it's important and that will be the problem that we're dealing from here on trying to figure it out and then long COVID, right? Cindy St. Hilaire: Yeah. Related to what you just said about the mechanism, this cleanup by the platelets or the act of cleaning up helps trigger their activation, is that partly why the antiplatelet and anticoagulant therapies failed in patients? Can you speculate on that? I know the jury's still out and there's a lot of work to be done, but is that part of why those therapies weren't beneficial? Milka Koupenova: The answer to that in my personally biased opinion is yes. Clearly, the antiplatelet therapies couldn't really control the classical activation of a platelet. So what I think we need to do from here on is to look at things that we don't understand that non-classically contribute to the thrombotic response downstream. If we manage to control the immune response in some way or the inflammation of the infection or how a platelet responds to a virus, then perhaps we can ameliorate a little bit of the downstream prothrombotic effect. So it's a lot more for us to trickle down and to understand in my personal opinion. DeLisa Fairweather: There is one thing that was really remarkable to me in hearing your experience, Milka, is that I had developed an autoimmune viral model of myocarditis in mice during my postdoc. So I've been studying that for the last 20 years. What is unique about that model is rather than using an adjuvant, we use a mild viral infection so it doesn't take very much virus at all going to the heart to induce it. I also, more recently, started studying extracellular vesicles really as a therapy, and in doing that, inadvertently found out that actually, the model that I'd created where we passage the virus through the heart to induce this autoimmune model, we were actually injecting extracellular vesicles into the mice and that's what was really driving the disease. This is really brought out. So from early days, I did my postdoc with Dr Noel Rose. If you've heard of him, he came up with the idea of autoimmune disease in the '50s. We had always, in that environment, really believed that viruses were triggering autoimmune disease and yet it took COVID before we could really prove that because no one could identify them. Here we have an example and I think the incidence rates with COVID were so high for myocarditis because for the first time, we had distinguished symptoms of patients going to the doctor right at the beginning of their infection having an actual test to examine the virus, knowing whether it's present or not, whether PCR or antibody test, and then being able to see when myocarditis happened. Cindy St. Hilaire: Yeah. I think one thing we can all appreciate now is just some of the basic biology we've learned on the backend of this. Actually, those last comments really led well to the article that your team led, Dr Chung, about what we call long COVID, which I guess I didn't realize has an actual name, post-acute sequelae of SARS-CoV-2 or PASC is the now more formal name for... /episode/index/show/circresearch/id/26870553

April 2023 Discover CircRes 04/20/2023

April 2023 Discover CircRes This month on Episode 47 of Discover CircRes, host Cynthia St. Hilaire highlights three original research articles featured in the March 31 issue of Circulation Research. We’ll also provide an overview of the Compendium on Increased Risk of Cardiovascular Complications in Chronic Kidney Disease published in the April 14 issue. Finally, this episode features an interview with Dr Elizabeth Tarling and Dr Bethan Clifford from UCLA regarding their study, RNF130 Regulates LDLR Availability and Plasma LDL Cholesterol Levels. Article highlights: Shi, et al. Chen, et al. Subramaniam, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to share three articles selected from our March 31st issue of Circulation Research and give you a quick summary of our April 14th Compendium. I'm also excited to speak with Dr Elizabeth Tarling and Dr Bethan Clifford from UCLA regarding their study, RNF130 Regulates LDLR Availability and Plasma LDL Cholesterol Levels. So first the highlights. The first article we're going to discuss is Discovery of Transacting Long Noncoding RNAs that Regulates Smooth Muscle Cell Phenotype. This article's coming from Stanford University and the laboratory of Dr Thomas Quertermous. Smooth muscle cells are the major cell type contributing to atherosclerotic plaques. And in plaque pathogenesis, the cells can undergo a phenotypic transition whereby a contractile smooth muscle cell can trans differentiate into other cell types found within the plaque, such as macrophage-like cells, osteoblast-like cells and fibroblast-like cells. These transitions are regulated by a network of genetic and epigenetic mechanisms, and these mechanisms govern the risk of disease. The involvement of long non-coding RNAs, or Lnc RNAs as they're called, has been increasingly identified in cardiovascular disease. However, smooth muscle cell Lnc RNAs have not been comprehensively characterized and the regulatory role in the smooth muscle cell state transition is not thoroughly understood. To address this gap, Shi and colleagues created a discovery pipeline and applied it to deeply strand-specific RNA sequencing from human coronary artery smooth muscle cells that were stressed with different disease related stimuli. Subsequently, the functional relevancy of a few novel Lnc RNAs was verified in vitro. From this pipeline, they identified over 4,500 known and over 13,000 unknown or previously unknown Lnc RNAs in human coronary artery smooth muscle cells. The genomic location of these long noncoding RNAs was enriched near coronary artery disease related transcription factor and genetic loci. They were also found to be gene regulators of smooth muscle cell identity. Two novel Lnc RNAs, ZEB-interacting suppressor or ZIPPOR and TNS1-antisense or TNS1-AS2, were identified by the screen, and this group discovered that the coronary artery disease gene, ZEB2, which is a transcription factor in the TGF beta signaling pathway, is a target for these Lnc RNAs. These data suggest a critical role for long noncoding RNAs in smooth muscle cell phenotypic transition and in human atherosclerotic disease. Cindy St. Hilaire: The second article I want to share is titled Destabilization of Atherosclerotic Plaque by Bilirubin Deficiency. This article is coming from the Heart Research Institute and the corresponding author is Roland Stocker. The rupture of atherosclerotic plaque contributes significantly to cardiovascular disease. Plasma concentrations of bilirubin, a byproduct of heme catabolism, is inversely associated with risk of cardiovascular disease, but the link between bilirubin and atherosclerosis is unknown. Chen et el addressed this gap by crossing a bilirubin knockout mice to a atherosclerosis prone APOe knockout mouse. Chen et el addressed this gap by crossing the bilirubin knockout mouse to the atherosclerosis-prone APOE knockout mouse, and used the tandem stenosis model of plaque instability to address this question. Compared with their litter mate controls, bilirubin-APOE double knockouts showed signs of increased systemic oxidative stress, endothelial dysfunction, as well as hyperlipidemia. And they had higher atherosclerotic plaque burden. Hemeatabolism was increased in unstable plaques compared with stable plaques in both of these groups as well as in human coronary arteries. In mice, the bilirubin deletion selectively destabilized unstable plaques and this was characterized by positive arterial remodeling and increased cap thinning, intra plaque hemorrhage, infiltration of neutrophils and MPO activity. Subsequent proteomics analysis confirmed bilirubin deletion enhanced extracellular matrix degradation, recruitment and activation of neutrophils and associated oxidative stress in the unstable plaque. Thus, bilirubin deficiency generates a pro atherogenic phenotype and selectively enhances neutrophil-mediated inflammation and destabilization of unstable plaques, thereby providing a link between bilirubin and cardiovascular disease risk. Cindy St. Hilaire: The third article I want to share is titled Integrated Proteomics Unveils Regulation of Cardiac Monocyte Hypertrophic Growth by a Nuclear Cyclic AMP Nano Domain under the Control of PDE3A. This study is coming from the University of Oxford in the lab of Manuela Zaccolo. Cyclic AMP is a critically important secondary messenger downstream from a myriad of signaling receptors on the cell surface. Signaling by cyclic AMP is organized in multiple distinct subcellular nano domains, regulated by cyclic AMP hydrolyzing phosphodiesterases or PDEs. The cardiac beta adrenergic signaling has served as the prototypical system to elucidate this very complex cyclic AMP compartmentalization. Although studies in cardiac monocytes have provided an understanding of the location and the properties of a handful of these subcellular domains, an overview of the cellular landscape of the cyclic AMP nano domains is missing. To understand the nanodynamics, Subramanian et al combined an integrated phospho proteomics approach that took advantage of the unique role that individual phosphodiesterases play in the control of local cyclic AMP. They combined this with network analysis to identify previously unrecognized cyclic AMP nano domains associated with beta adrenergic stimulation. They found that indeed this integrated phospho proteomics approach could successfully pinpoint the location of these signaling domains and it provided crucial cues to determine the function of previously unknown cyclic AMP nano domains. The group characterized one such cellular compartment in detail and they showed that the phosphodiesterase PDE3A2 isoform operates in a nuclear nano domain that involves SMAD4 and HDAC1. Inhibition of PDE3 resulted in an increased HDAC1 phosphorylation, which led to an inhibition of its deacetylase activity, and thus derepression of gene transcription and cardiac monocyte hypertrophic growth. These findings reveal a very unique mechanism that explains the negative long-term consequences observed in patients with heart failure treated with PDE3 inhibitors. Cindy St. Hilaire: The April 14th issue is our compendium on Increased Risk of Cardiovascular Complications in Chronic Kidney Disease. Dr Heidi Noels from the University of Aachen is our guest editor of the 11 articles in this issue. Chronic kidney disease is defined by kidney damage or a reduced kidney filtration function. Chronic kidney disease is a highly prevalent condition affecting over 13% of the population worldwide and its progressive nature has devastating effects on patient health. At the end stage of kidney disease, patients depend on dialysis or kidney transplantation for survival. However, less than 1% of CKD patients will reach this end stage of chronic kidney disease. Instead, most of them with moderate to advanced chronic kidney disease will prematurely die and most often they die from cardiovascular disease. And this highlights the extreme cardiovascular burden patients with CKD have. The titles of the articles in this compendium are the Cardio Kidney Patient Epidemiology, Clinical Characteristics, and Therapy by Nicholas Marx, the Innate Immunity System in Patients with Cardiovascular and Kidney Disease by Carmine Zoccali et al. NETs Induced Thrombosis Impacts on Cardiovascular and Chronic Kidney disease by Yvonne Doering et al. Accelerated Vascular Aging and Chronic Kidney Disease, The Potential for Novel Therapies by Peter Stenvinkel et al. Endothelial Cell Dysfunction and Increased Cardiovascular Risk in Patients with Chronic Kidney Disease by Heidi Noels et al. Cardiovascular Calcification Heterogeneity in Chronic Kidney Disease by Claudia Goettsch et al. Fibrosis in Pathobiology of Heart and Kidney From Deep RNA Sequencing to Novel Molecular Targets by Raphael Kramann et al. Cardiac Metabolism and Heart Failure and Implications for Uremic Cardiomyopathy by P. Christian Schulze et al. Hypertension as Cardiovascular Risk Factor in Chronic Kidney Disease by Michael Burnier et al. Role of the Microbiome in Gut, Heart, Kidney crosstalk by Griet Glorieux et al, and Use of Computation Ecosystems to Analyze the Kidney Heart Crosstalk by Joachim Jankowski et al. These reviews were written by leading investigators in the field, and the editors of Circulation Research hope that this comprehensive undertaking stimulates further research into the path flow of physiological kidney-heart crosstalk, and on comorbidities and intra organ crosstalk in general. Cindy St. Hilaire: So for our interview portion of the episode I have with me Dr Elizabeth Tarling and Dr Bethan Clifford. And Dr Tarling is an associate professor in the Department of Medicine in cardiology at UCLA, and Dr Clifford is a postdoctoral fellow with the Tarling lab. And today we're going to be discussing their manuscript that's titled, RNF130 Regulates LDLR Availability and Plasma LDL Cholesterol Levels. So thank you both so much for joining me today. Elizabeth Tarling: Thank you for having us. Bethan Clifford: Yeah, thanks for having us. This is exciting. Cindy St. Hilaire: I guess first, Liz, how did you get into this line of research? I guess, before we get into that, I should disclose. Liz, we are friends and we've worked together in the ATVB Women's Leadership Committee. So full disclosure here, that being said, the editorial board votes on these articles, so it's not just me picking my friends. But it is great to have you here. So how did you enter this field, I guess, briefly? Elizabeth Tarling: Yeah, well briefly, I mean my training right from doing my PhD in the United Kingdom in the University of Nottingham has always been on lipid metabolism, lipoprotein biology with an interest in liver and cardiovascular disease. So broadly we've always been interested in this area and this line of research. And my postdoctoral research was on atherosclerosis and lipoprotein metabolism. And this project came about through a number of different unique avenues, but really because we were looking for regulators of LDL biology and plasma LDL cholesterol, that's sort of where the interest of the lab lies. Cindy St. Hilaire: Excellent. And Bethan, you came to UCLA from the UK. Was this a topic you were kind of dabbling in before or was it all new for you? Bethan Clifford: It was actually all completely new for me. So yeah, I did my PhD at the same university as Liz and when I started looking for postdocs, I was honestly pretty adamant that I wanted to stay clear away from lipids and lipid strategy. And then it wasn't until I started interviewing and meeting people and I spoke to Liz and she really sort of convinced me of the excitement and that the interest and all the possibilities of working with lipids and well now I won't go back, to be honest. Cindy St. Hilaire: And now here you are. Well- Bethan Clifford: Exactly. Cindy St. Hilaire: ... congrats on a wonderful study. So LDLR, so low density lipoprotein receptor, it's a major determinant of plasmid LDL cholesterol levels. And hopefully most of us know and appreciate that that is really a major contributor and a major risk for the development of atherosclerosis and coronary artery disease. And I think one thing people may not really appreciate, which your study kind of introduces and talks about nicely, is the role of the liver, right? And the role of receptor mediated endocytosis in regulating plasma cholesterol levels. And so before we kind of chat about the nitty-gritty of your study, could you just give us a brief summary of these key parts between plasma LDL, the LDL receptor and where it goes in your body? Elizabeth Tarling: Yeah. So the liver expresses 70% to 80% of the body's LDL receptor. So it's the major determinant of plasma lipoprotein plasma LDL cholesterol levels. And through groundbreaking work by Mike Brown and Joe Goldstein at the University of Texas, they really define this receptor mediated endocytosis by the liver and the LDL receptor by looking at patients with familial hypercholesterolemia. So those patients have mutations in the LDL receptor and they either express one functional copy or no functional copies of the LDL receptor and they have very, very large changes in plasma LDL cholesterol. And they have severe increases in cardiovascular disease risk and occurrence and diseases associated with elevated levels of cholesterol within the blood and within different tissues. And so that's sort of how the liver really controls plasma LDL cholesterol is through this receptor mediated endocytosis of the lipoprotein particle. Cindy St. Hilaire: There's several drugs now that can help regulate our cholesterol levels. So there's statins which block that rate limiting step of cholesterol biosynthesis, but there's this new generation of therapies, the PCSK9 inhibitors. And can you just give us a summary or a quick rundown of what are those key differences really? What is the key mechanism of action that these therapies are going after and is there room for more improvement? Bethan Clifford: Yeah, sure. So I mean I think you've touched on something that's really key about the LDR receptor is that it's regulated at so many different levels. So we have medications available that target the production of cholesterol and then as you mentioned this newer generation of things like PCSK9 inhibitors that sort of try and target LDL at the point of clearance from the plasma. And in response to your question of is there room for more regulation, I would say that given the sort of continual rate of increased cholesterol in the general population and the huge risks associated with elevated cholesterol, there's always capacity for more to improve that and sort of generally improve the health of the population. And what we sort of found particularly exciting about RNF130 is that it's a distinct pathway from any of these regulatory mechanisms. So it doesn't regulate the level of transcription, it doesn't regulate PCSK9. Or in response to PCSK9, it's a completely independent pathway that could sort of improve or add to changes in cholesterol. Cindy St. Hilaire: So your study, it's focusing on the E3 ligase, RNF130. What is an E3 ligase, and why was this particular one of interest to you? How did you come across it? Elizabeth Tarling: is predTates Bethan joining the lab. This is, I think, again for the listeners and those people in training, I think it's really important to note this project has been going in the lab for a number of years and has really... Bethan was the one who came in and really took charge and helped us round it out. But it wasn't a quick find or a quick story. It had a lot of nuances to it. But we were interested in looking for new regulators of LDL cholesterol and actually through completely independent pathways we had found the RNF130 locus as being associated with LDL cholesterol in animals. And then it came out in a very specific genome-wide association study in the African American care study, the NHLBI care study. And so really what we started looking at, we didn't even know what it was. Elizabeth Tarling: So we asked ourselves, well what is this gene? What is this protein? And it's RNF, so that's ring finger containing protein 130 and ring stands for really interesting new gene. Somebody came up with the glorious name. But proteins that contain this ring domain are very characteristic and they are E3 ubiquitin ligases. And so they conjugate the addition of ubiquitin to a target protein and that signals for that protein to either be internalized and/or degraded through different decorative pathways within the cell. And so we didn't land on it because we were looking at E3 ligases, we really came at it from an LDL cholesterol perspective. And it was something that we hadn't worked on before and the study sort of blossomed from there. Cindy St. Hilaire: That's amazing and a beautiful, but also, I'm sure, heartbreaking story because these long projects are just... They're bears. So what does this RNF130 do to LDLR? What'd you guys find? Bethan Clifford: As Liz said, this is a long process, but one of the key factors of RNF130 is it's structurally characteristically looked like E3 ligase. So the first thing that Liz did and then I followed up with in the lab is to see is this E3 ligase ubiquitinating in vitro. And if it is going to ubiquitinate, what's it likely to regulate that might cause changes in plasma cholesterol that would explain these human genetic links that we saw published at the same time. And so because the LDL cholesterol is predominantly regulated by the LDL receptor and the levels of it at the surface of the parasites in the liver, the first question we wanted to see is does RNF130 interact in any way with that pathway? And I'm giving you... /episode/index/show/circresearch/id/26591421

March 2023 Discover CircRes 03/16/2023

March 2023 Discover CircRes This month on Episode 46 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the March 3 and March 17th issues of Circulation Research. This episode also features an interview with Dr Andrew Hughes and Dr Jessilyn Dunn about their review, Article highlights: Delgobo, et al. Sun, et al. Sun, et al Johnson, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to share four articles selected from the March 3rd and March 17th issues of CircRes. I'm also going to have a discussion with Dr Andrew Hughes and Dr Jessilyn Dunn about their review, Wearable Devices in Cardiovascular Medicine. And the Review is also featured in our March 3rd issue. Cindy St. Hilaire: First, the highlights. The first article I'm going to present is Myocardial Milieu Favors Local Differentiation of Regulatory T-Cells. The first author is Murilo Delgobo and the corresponding author is Gustavo Campos Ramos. After myocardial infarction, the release of autoantigens from the damaged heart cells activates local and infiltrating immune cells such as the T-cell. Studies in mice have shown that fragments of the muscle protein myosin can act as autoantigens, and these myosin fragments are the dominant driver of the T-cell response. But how do these myosin specific T-cells behave in the damaged heart to drive inflammation and repair is unknown. To find out, Delgobo and colleagues studied endogenous myosin specific T-cells, as well as those transferred into recipient mice. They found, whether exogenously supplied or endogenously created, the myosin specific T-cells that accumulated in the animals' infarcted hearts tended to adopt an immunosuppressive T-regulatory phenotype. Strikingly, even if the exogenous cells were differentiated into inflammatory TH-17 cells prior to transfer, a significant proportion of them were still reprogrammed into T-regs within the heart. Although cells pre-differentiated into an inflammatory TH-17 phenotype were less inclined to change after the transfer, the results nevertheless indicate that, by and large, the infarcted heart promotes T-cell reprogramming to quell inflammation and drive repair. Yet exactly how the heart does this is a question for future studies. Cindy St. Hilaire: The next article I'm going to present is titled Inhibition of FAP Promotes Cardiac Repair by Stabilizing BNP. The first authors of the study are Yuxi Sun and Mengqiu Ma, and the corresponding author is Rui Yue, and they are from Tongji University. After myocardial infarction, there needs to be a balance of recovery processes to protect the tissue. Fibrosis, for example, acts like an immediate bandaid to hold the damaged heart muscle together, but fibrosis can limit contractile function. Similarly, angiogenesis and sufficient revascularization is required to promote survival of cardiomyocytes within the ischemic tissue and protect heart function. To better understand the balance between fibrotic and angiogenic responses, Sun and colleagues examined the role of fibroblasts activated protein, or FAP, which is dramatically upregulated in damaged hearts, and brain natriuretic peptide, or BNP, which promotes angiogenesis in the heart. In this study, they found that genetic deletion or pharmacological inhibition of FAP in mice reduces cardiac fibrosis and improves angiogenesis and heart function after MI. Such benefits are not seen if BNP or its receptor, NRP-1, are lacking. The in vitro experiments revealed that FAP's protease activity degrades BNP, thus inhibiting the latter's angiogenic activity. Interestingly, while FAP is upregulated in the heart, its levels drop in the blood, showing that BNP inhibition is localized. Together, these results suggest that blocking FAP's activity in the heart after MI could be a possible strategy for protecting the muscle's function. Cindy St. Hilaire: The next article I want to present is Hypoxia Sensing of Beta-Adrenergic Receptor is Regulated by Endosomal PI-3 Kinase Gamma. The first author of this study is Yu Sun, and the corresponding author is Sathyamangla Naga Prasad. Hypoxia is the most proximate acute stress encountered by the heart during an ischemic event. Hypoxia triggers dysfunction of the beta-adrenergic receptors, beta-1AR and beta-2AR, which are critical regulators of cardiac function. Under normoxic conditions, activation of PI3K-gamma by beta-adrenergic receptors leads to feedback regulation of the receptor by hindering its dephosphorylation through inhibition of protein phosphatase 2A or PP2A. Although it is known that ischemia reduces beta-adrenergic receptor function, the impact of hypoxia on interfering with this PI3K feedback loop was unknown. Using in vitro and in vivo techniques, this group found that activation of PI3K-gamma underlies hypoxia sensing mechanisms in the heart. Exposing PI3K-gamma knockout mice to acute hypoxia resulted in preserved cardiac function and reduced beta-adrenergic receptor phosphorylation. And this was due to a normalized beta-2AR associated PP2A activity, thus uncovering a unique role for PI3K-gamma in hypoxia sensing and cardiac function. Similarly, challenging wild-type mice post hypoxia with dobutamine resulted in an impaired cardiac response that was normalized in the PI3K-gamma knockout mice. These data suggests that preserving beta-adrenergic resensitization by targeting the PI3K-gamma pathway would maintain beta-adrenergic signaling and cardiac function, thereby permitting the heart to meet the metabolic demands of the body following ischemia. Cindy St. Hilaire: The last article I want to highlight is Systemic Hypoxia Induces Cardiomyocyte Hypertrophy and Right Ventricle Specific Induction of Proliferation. First author of this study is Jaslyn Johnson, and the corresponding author is Steven Houser, and they're at Temple University. The cardiac hypoxia created by myocardial infarction leads to the death of the heart tissue, including the cardiomyocytes. While some procedures such as reperfusion therapy prevent some cardiomyocyte death, true repair of the infarcted heart requires that dead cells be replaced. There have been many studies that have attempted new approaches to repopulate the heart with new myocytes. However, these approaches have had only marginal success. A recent study suggested that systemic hypoxemia in adult male mice could induce cardiac monocytes to proliferate. Building on this observation, Johnson and colleagues wanted to identify the mechanisms that induced adult cardiomyocyte cell cycle reentry and wanted to determine whether this hypoxemia could also induce cardiomyocyte proliferation in female mice. Mice were kept in hypoxic conditions for two weeks, and using methods to trace cell proliferation in-vivo, the group found that hypoxia induced cardiac hypertrophy in both the left ventricle and the right ventricle in the myocytes of the left ventricle and of the right ventricle. However, the left ventricle monocytes lengthened while the RV monocytes widened and lengthened. Hypoxia induced an increase in the number of right ventricular cardiomyocytes, but did not affect left ventricular monocyte proliferation in male or in female mice. RNA sequencing showed upregulation of cell cycle genes which promote the G1 to S phase transition in hypoxic mice, as well as a downregulation of cullen genes, which are the scaffold proteins related to the ubiquitin ligase complexes. There was significant proliferation of non monocytes in mild cardiac fibrosis in the hypoxic mice that did not disrupt cardiac function. Male and female mice exhibited similar gene expression patterns following hypoxia. Thus, systemic hypoxia induced a global hypertrophic stress response that was associated with increased RV proliferation, while LV monocytes did not show increased proliferation. These results confirm previous reports that hypoxia can induce cardiomyocyte cell cycle activity in-vivo, and also show that this hypoxia induced proliferation also occurs in the female mice. Cindy St. Hilaire: With me today for our interview, I have Dr Andrew Hughes and Dr Jessilyn Dunn, and they're from Vanderbilt University Medical Center. And they're here to discuss the review article that they helped co-author called Wearable Devices in Cardiovascular Medicine. And just as a side note, the corresponding author, Evan Brittain, unfortunately just wasn't able to join us due to clinical service, but they're going to help dissect and discuss this Review with us. Thank you both so much for joining me today. Andy, can you just tell us a little bit about yourself? Andy Hughes: Yeah, thank you, Cindy. I'm Andy Hughes. I'm a third year medicine resident at Vanderbilt University who is currently on an NIH supported research year this year. And then will be applying to cardiology fellowships coming up in the upcoming cycle. Cindy St. Hilaire: Great, thank you. And Jessilyn, I said you are from Vanderbilt. I know you're from Duke. It was Evan and Andy at Vanderbilt. Jessilyn, tell us about yourself. Jessilyn Dunn: Thanks. I am an Assistant Professor at Duke. I have a joint appointment between biomedical engineering and biostatistics and bioinformatics. The work that my lab does is mainly centered on digital health technologies in developing what we call digital biomarkers, using data from often consumer wearables to try to detect early signs of health abnormalities and ultimately try to develop interventions. Cindy St. Hilaire: Thank you. We're talking about wearable devices today, and obviously the first thing I think most of us think about are the watch-like ones, the ones you wear on your wrists. But there's really a whole lot more out there. It's not just Apple Watches and Fitbits and the like. Can you just give us a quick summary of all these different types of devices and how they're classified? Jessilyn Dunn: Yeah, absolutely. We have a wide variety of different sensors that can be useful. A lot of times, we like to think about them in terms of the types of properties that they measure. So mechanical properties like movement, electrical properties like electrical activity of the heart. We have optical sensors. And so, a lot of the common consumer wearables that we think about contain these different types of sensors. A good example that we can think about is your consumer smartwatch, like an Apple Watch or a Fitbit or a Garmin device where it has something called an accelerometer that can measure movement. And oftentimes, that gets converted into step counts. And then it may also have an optical sensor that can be used to measure heart rate in a particular method called PPG, or photoplethysmography. And then some of the newer devices also have the ability to take an ECG, so you can actually measure electrical activity as well as the optical based PPG heart rate measurement. These are some of the simpler components that make up the more complex devices that we call wearables. Cindy St. Hilaire: And how accurate are the measurements? You did mention three of the companies, and I know there's probably even more, and there's also the clinical grade at-home ECG machines versus the one in the smartwatch. How accurate are the measurements between companies? And we also hear recent stories about somebody's Apple Watch calling 911 because they think they're dead, things like that. Obviously, there's proprietary information involved, but how accurate are these devices and how accurate are they between each other? Jessilyn Dunn: This is a really interesting question and we've done quite a bit of work in my lab on this very topic, all the way from what does it mean for something to be accurate? Because we might say, "Well, the more accurate, the better," but then we can start to think about, "Well, how accurate do we need something to be in order to make a clinical decision based off of that?" And if it costs significantly more to make a device super, super accurate, but we don't need it to be that accurate to make useful decisions, then it actually might not be serving people well to try to get it to that extreme level of accuracy. So there are a lot of trade-offs, and I think that's a tough thing to think about in the circumstances, is these trade-offs between the accuracy and, I don't know, the generalizability or being able to apply this to a lot of people. That being said, it also depends on the circumstances of use. When we think about something like step counts, for example, if you're off by a hundred step counts and you're just trying to get a general view of your step counts, it's not that much of a problem. But if we're talking about trying to detect an irregular heart rhythm, it can be very bad to either miss something that's abnormal or to call something abnormal that's not and have people worried. We've been working with the Digital Medicine Society to develop this framework that we call V3, which is verification, analytic validation and clinical validation. And these are the different levels of analysis or evaluation that you can do on these devices to determine how fit for purpose are they. Given the population we're trying to measure in and given what the goal of the measurement is, does the device do the job? And what's also interesting about this topic is that the FDA has been evolving how they think about these types of devices because there's, in the past, been this very clear distinction between wellness devices and medical devices. But the problem is that a lot of these devices blur that line. And so, I think we're going to see more changes in the way that the FDA is overseeing and potentially regulating things like this as well. Cindy St. Hilaire: These consumer-based devices have started early on as the step counters. When did they start to bridge into the medical sphere? When did that start to peak the interest of clinicians and researchers? Jessilyn Dunn: Yeah, sure. What's interesting is if we think back to accelerometers, these have been used prior to the existence of mobile phones. These really are mechanical sensors that could be used to count steps. And when we think about the smartwatch in the form that we most commonly think of today, probably looking back to about 2014 is when ... maybe between 2012, 2014 is when we saw these devices really hitting the market more ... Timing for when the devices that we know as our typical consumer smartwatch today was around 2012 to 2014. And those were things that were counting steps and then the next generation of that added in the PPG or photoplethysmography sensor. That's that green light when we look on the back of our watch that measures heart rate. And so, thinking back to the early days, probably Jawbone, there was a watch called Basis, the Intel Basis watch. Well, it was Basis and then got acquired by Intel. Fitbit was also an early joining the market, but that was really the timing. Cindy St. Hilaire: How good are these devices at actually changing behavior? We know we're really good at tracking our steps now and maybe monitoring our heartbeat or our oxygen levels. How good are they at changing behavior though? Do we know yet? Andy Hughes: Yeah, that's a great question and certainly a significant area of ongoing research right now with physical activity interventions. Things that we've seen right now is that simple interventions that use the wearable devices alone may not be as effective as multifaceted interventions. And what I mean by that is interventions that use the smartwatch but may be coupled with another component, whether that is health education or counseling or more complex interventions that use gamification or just in time adaptive interventions. And gamification really takes things to another level because that integrates components, competition or support or collaboration and really helps to build upon features of behaviors that we know have an increased likelihood of sustaining activity. With that being said, that is one of the challenges of physical activity interventions, is the sustainability of their improvements over the course of months to years. And something that we have seen is the effects do typically decrease over time, but there is work on how do we integrate all of these features to develop interventions that can help to sustain the results more effectively. So we have seen some improvement, but finding ways to sustain the effects of physical activity is certainly an area of ongoing research. Cindy St. Hilaire: I know it's funny that even as adults we love getting those gold stars or the circle completions. All of these devices, whether it's smartwatches like we're just talking about, or the other things for cardiac rehabilitation, they're generating a ton of data. What is happening with all this data? Who's actually analyzing it? How is it stored and what's that flow through from getting from the patient's body to the room where their physician is looking at it? Andy Hughes: And that is certainly a challenge right now that is limiting the widespread adoption of these devices into routine clinical care is, as Jessilyn mentioned. The wearables generate a vast amount of data, and right now, we need to identify and develop a way as clinicians to sort through all of the noise in order to be able to identify the information that is clinically meaningful and worthy of action without significantly increasing the workload. And a few of the barriers that will be necessary in order to reach that point is, one, finding ways to integrate the wearables' data into the electronic health record and also developing some machine learning algorithms or ways with which we can use the computational power of those technologies to be able to identify when there is meaningful data within all of the vast data that comes from wearables. So it's somewhere that certainly we need to get to for these devices to reach their full clinical potential, but we are limited right now by a few of those challenges. Jessilyn Dunn: I was just going to say, I will add on to what Andy was saying about this idea behind digital biomarkers because this fits really nicely with this idea that giving people this huge data deluge is not helpful, but if we had a single metric where we can say, "Here's the... /episode/index/show/circresearch/id/26239170

February 2023 Discover CircRes 02/16/2023

February 2023 Discover CircRes This month on Episode 45 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the February 3rd and February 17th issues of Circulation Research. This episode also features an interview with Dr Hind Lal and Dr Tousif Sultan from the University of Alabama at Birmingham about their study Article highlights: Pi, et al. Carnevale, et al. Cai, et al. Koide, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cynthia St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to be highlighting the articles from our February 3rd and 17th issues of Circulation Research. I'm also going to have a chat with Dr Hind Lal and Dr Tousif Sultan from the University of Alabama at Birmingham about their study, Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1β Mediated Inflammation. But before I get to the interviews, here are a few article highlights. Cindy St. Hilaire: The first article I want to highlight comes from the laboratory of Dr Peter Leary at the University of Washington, and the title is Metabolomic Signatures Associated With Pulmonary Arterial Hypertension Outcomes. Pulmonary Arterial Hypertension or PAH is a rare but life-threatening disease in which progressive thickening of the walls of the lung’s blood vessels causes increased blood pressure and that increased blood pressure ultimately damages the heart's right ventricle. Interestingly, progression to heart failure varies considerably among patients, but the reasons why there is variability are not well understood. To find out, this group turned their attention to patient metabolomes, which differ significantly from those of healthy people and thus may also change with severity. Blood samples from 117 PAH patients were analyzed for more than a thousand metabolites by mass spectrometry and the patient's progress was followed for the next three years. 22 patients died within a three-year period and 27 developed significant right ventricle dilation. Other measures of severity included pulmonary vascular resistance, exercise capacity and levels of BNP, which is a metric of heart health. Two metabolic pathways, those relating to polyamine and histidine metabolism, were found to be linked with all measures of severity suggesting a key role for them in disease pathology. While determining how these pathways influence disease as a subject for further study, the current findings may nevertheless lead to new prognostic indicators to inform patient care. Cindy St. Hilaire: The next article I want to discuss is coming from our February 3rd issue of Circulation Research and this is coming from the laboratory of Dr Francisco Violi at the University of Rome and the title is Toll-Like Receptor 4-Dependent Platelet-Related Thrombosis in SARS-CoV-2 Infection. Thrombosis can be a complication of COVID-19 and it is associated with poor outcomes, including death. However, the exact mechanism by which the virus activates platelets, which are the cells that drive thrombosis, is not clear. For one thing, platelets do not appear to express the receptor for SARS-CoV-2. They do however, express the TLR4 receptor and that's a receptor that mediates entry of other viruses as part of the immune response. And TLR4 is ramped up in COVID-19 patient platelets. This group now confirms that, indeed, SARS-CoV-2 interacts with TLR4, which in turn triggers thrombosis. The team analyzed platelets from 25 patients and 10 healthy controls and they found that the platelet activation and thrombic activity were both boosted in the patient samples and could not be blocked using a TLR4 inhibitor. Additionally, immunoprecipitation and immunofluorescent experiments further revealed colocalization between the virus protein and the TLR4 receptor on patient platelets. The team went on to show that the signaling pathway involved reactive oxygen species producing factors p47phox and Nox2, and that inhibition of phox 47, like that of the TLR4 receptor itsel,f could prevent platelet activation. As such, this study suggests that inhibiting either of these proteins may form the basis of an antithrombotic treatment for COVID-19. Cindy St. Hilaire: The third article I want to highlight is coming from the lab of Shi-You Chen at University of Missouri and the title of this article is ADAR1 Non-Editing Function in Macrophage Activation and Abdominal Aortic Aneurysm. Macrophage activation plays a critical role in abdominal aortic aneurysm development, or AAA development. Inflammation is a component of this pathology; however, the mechanisms controlling macrophage activation and vascular inflammation in AAA are largely unknown. The ADAR1 enzyme catalyzes the conversion of adenosine to inosine in RNA molecules and thus this conversion can serve as a rheostat to regulate RNA structure or the gene coding sequence of proteins. Several studies have explored the role of ADAR1 in inflammation, but its precise contribution is not fully understood, so the objective of this group was to study the role of ADAR1 in macrophage activation and AAA formation. Aortic transplantation was conducted to determine the importance of nonvascular ADAR1 in AAA development and dissection and angiotensin II infusion of ApoE knockout mice combined with a macrophage specific knockout of ADAR1 was used to study the role of ADAR1 macrophage specific contributions to AAA formation and dissection. Allograft transplantation of wild type abdominal aortas to ADAR1 haploinsufficient recipient mice significantly attenuated AAA formation. ADAR1 deficiency in hematopoietic stem cells also decreased the prevalence and the severity of AAA and it also inhibited macrophage infiltration into the aortic wall. ADAR1 deletion blocked the classic macrophage activation pathway. It diminished NF-κB signaling and it enhanced the expression of a number of anti-inflammatory microRNAs. Reconstitution of ADAR1 deficient but not wild type human monocytes to immunodeficient mice blocked the aneurysm formation in transplanted human arteries. Together these results suggest that macrophage ADAR1 promotes aneurysm formation in both mouse and human arteries through a novel mechanism of editing the microRNAs that target NF-κB signaling, which ultimately promotes vascular inflammation in AAA. Cindy St. Hilaire: The last article I want to highlight is also from our February 17th issue of Circulation Research and it is coming from the lab of Shintaro Mandai at Tokyo Medical and Dental University and the title of the article is Circulating Extracellular Vesicle Propagated MicroRNA signatures as a Vascular Calcification Factor in Chronic Kidney Disease. Chronic Kidney Disease or CKD accelerates vascular calcification in part by promoting the phenotypic switching of vascular smooth muscle cells to osteoblast like cells. This study investigated the role of circulating small extracellular vesicles or SUVs from the kidneys in promoting this osteogenic switch. CKD was induced in rats and in mice by an adenine induced tubular interstitial fibrosis and serum from these animals induced calcification in in vitro cultures of A-10 embryonic rat smooth muscle cells. Intraperitoneal administration of a compound that prevents SEV biosynthesis and release inhibited thoracic aortic calcification in CKD mice under a high phosphorus diet. In Chronic Kidney Disease, the microRNA transcriptome of SUVs revealed a depletion of four microRNAs and the expression of the microRNAs inversely correlated with kidney function in CKD patients. In vitro studies found that transected microRNA mimics prevented smooth muscle cell calcification in vitro. In silico analyses revealed that VEGF-A was a convergent target of all four microRNAs and leveraging this, the group used in vitro and in vivo models of calcification to show the inhibition of the VEGF-A, VEGFR-2 signaling pathway mitigated calcification. So in addition to identifying a new potential therapeutic target, these SUV propagated microRNAs are a potential biomarker that can be used for screening patients to determine the severity of CKD and possibly even vascular calcification. Cindy St. Hilaire: Today I have with me Dr Hind Lal who's an associate professor of medicine at the University of Alabama Birmingham and his post-doctoral fellow and the lead author of the study Dr Tousif Sultan. And their manuscript is titled Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1β Mediated Inflammation. And this article is in our February 3rd issue of Circulation Research. So thank you both so much for joining me today. Tousif Sultan: Thank you. Hind Lal: Thank you for taking time. Cindy St. Hilaire: So ponatinib, it's a tyrosine kinase inhibitor and from my understanding it's the only treatment option for a specific group of patients who have chronic myelogenous leukemia and they have to harbor a specific mutation. And while this drug helps to keep these patients alive essentially, it's extremely cardiotoxic. So cardiotoxicity is somewhat of a new field. So Dr Lal, I was wondering how did you get into this line of research? Hind Lal: So I was fortunate enough to be in the lab of Dr Tom Force and he was kind of father of this new area, now is very developed, it's called cardio-oncology. On those days there were basically everything started in cardio-oncology. So I just recall the first tyrosine kinase approved by FDA was in 2000 and that was... Imagine and our paper came in Nature Medicine 2005 and discovering there is... so to elaborate it a little bit, the cancer therapy broadly divided in two parts. One is called non-targeted therapy like chemotherapy, radiations, et cetera, and then there are cytotoxic drugs. So those cytotoxic drugs because they do not have any targeted name on it so they are, cardiotoxic are toxic to any organ was very obvious and understanding. When these targeted therapy came, which is mainly kinase inhibitor are monoclonal antibodies. So these are targeted to a specific pathway that is activated only in the cancer cells but not in any other cells in the body so they were proposed as like magic bullets that can take off the cancer without any cardiotoxity or minimal side effects. But even in the early phase like 2005 to 2010, these came out, these so-called targeted, they are not very targeted and they are not also the magic bullets and they have serious cardiotoxicity. Cindy St. Hilaire: And so what's the mechanism of action of ponatinib in the leukemia and how does that intersect with the cardiovascular system? Hind Lal: Yeah, so this is very good question I must say. So what we believe at this point because, so leukemia if you know is driven by the famous Philadelphia chromosome, which is a translicational gene, one part of human chromosome nine and one part of human chromosome 22 and they translocate make a new gene which is BCR-ABL gene. And because it was discovered in Philadelphia UPENN, is named that Philadelphia chromosome, which is very established mechanism, that's how CML is driven. But what we have discovered that the cardiotoxicity driven by totally, totally different from the ponatinib is one of the inflammatory So it's kind of goodening. So this question is so good. One kind of toxicity is called on-target, when toxicity is mediated by the same mechanism, what is the mechanism of the drug to cure the cancer? So in that case your absolute is minimal because if you manipulate that, the drug's ability to cure the cancer will be affected but if the toxicity and the efficacy is driven by two different mechanism, then as in case of ponatinib seems like it's NLRP3 and inflammasome related mechanism. So this can be managed by manipulating this pathway without hampering the drug efficacy on the cancer. Cindy St. Hilaire: So what exactly is cardiotoxicity and how does it present itself in these patients? Hind Lal: So these drugs like ponatinib, they call broader CVD effects. So it's not just cardiac, so they also in hypertensives and atherosclerosis and thrombosis, those kind of thing. But our lab is primarily focused on the heart. So that's why in this paper we have given impresses on the heart. So what we believe at this point that ponatinib lead to this proinflammatory pathway described in this paper, which is just 108A9-NLRP3-IL-1β and this inflammatory pathway lead to a cytokine storm very much like in the COVID-19 and these cytokine storms lead to excessive myocarditis and then finally cardiac dysfunction. Cindy St. Hilaire: Is the cytokine storm just local in the cardiac tissue or is it also systemic in the patients? Is cardiotoxicity localized only or is it a more systemic problem? Tousif Sultan: I would like to add in this paper we have included that we look this cytokine things and explain blood circulation, bone marrow. So the effect is everywhere, it's not local. So we didn't check other organs, maybe other organs also being affected with the ponatinib treatment. Cindy St. Hilaire: And what's the initial phenotype of a patient has when they start to get cardiotoxicity, what's kind of like a telltale symptom? Hind Lal: So good thing that in recent years cardio-oncology developed. So initially the patient that were going for cancer treatment, they were not monitored very closely. So they only end up in cardiology clinic when they are having some cardiac events already. So thanks to the lot of development and growth in the cardio-oncology field, now most patients who going for a long-term cancer treatment, they are closely monitored by cardiology clinics. Cindy St. Hilaire: Got it. So they can often catch it before a symptom or an event. That's wonderful. Hind Lal: Yeah, so there's a lot of development in monitoring. Cindy St. Hilaire: Wonderful. So you were really interested in figuring out why ponatinib induces cardiotoxicity and you mentioned that really up until now it's been very difficult to study and that's because of the limitation of available murine models. If you just inject a wild type mouse with ponatinib, nothing happens really. So what was your approach to finding relatively good murine models? How did you go about that? Hind Lal: So this is the top scientific question you can ask. So like science, the field is try and try again. So initially this is the first paper with the ponatinib toxicity using the real in vivo models. Any paper before this including ours studies published, they were done on the cellular model in hiPSC, that isolated cardiomyocytes. So you directly putting the ponatinib directly the isolated cells. So this is first case when we were trying to do in vivo, maybe other attempt in vivo but at least not published. So first we also treated the animals with ponatinib and that failed, we don't see any cardiotoxic effect. And then when we going back to the literature, the clinical data is very, very clear from pharmacovigilance that ponatinib is cardiotoxic in humans. So when we're not able to see any phenotype in mouse, we realize that we are not mimicking what's happening in the humans. So we certainly missing something. Now once again I quote this COVID-19, so many people get infected with COVID-19 but people are having preexisting conditions are on high risk to developing CVD. So there was some literature on that line. So we use this very, very same concept that if there is preexisting conditions, so likely who'd have developing future cardiac event will be more. So we use two model in this paper one atherosclerosis model which is APoE null mice mice, another is tag branding which is pressure overload model for the heart and as soon as we start using what we call comorbidity model like patient is having some preexisting conditions and we very clearly see the robust defect of ponatinib on cardiac dysfunction. Cindy St. Hilaire: Yeah, it's really, really well done and I really like that you use kind of two different models of this. Do you think it's also going to be operative in maybe like the diabetic mirroring models? Do you think if we expand to other comorbidities, you might also recapitulate the cardiotoxicity? Hind Lal: So you got all the best questions. Cindy St. Hilaire: Thank you. I try. Hind Lal: So because this is CML drug and lot of the risk factor for cardiovascular and cancer are common and even metabolic disease. So most of the time these patients are elderly patients and they're having metabolic conditions and most of the time they have blood pressure or something CVD risk factors. So I agree with you, it'll be very relevant to expand this to the diabetes or metabolic models, but these were the first study, we put all our focus to get this one out so news is there then we can expand the field adding additional models et cetera. But I agree with you that will be very logical next step to do. Cindy St. Hilaire: Yeah. And so I guess going back to what you know from the human study or the clinical trials or the human observations, are different populations of patients with CML more predisposed to cardio toxicity than others or is that not known yet? Hind Lal: So one other area called pharmacovigilance. So what pharmacovigilance does patient all over the world taking these drugs. So WHO have their own vigilance system and FDA have their own, so it's called BG-Base for the WHO and it's called the FAERS for the FDA. So one can go back in those data sets and see if X patient taking this Y drug and what kind of... /episode/index/show/circresearch/id/25951446

January 2023 Discover CircRes 01/19/2023

January 2023 Discover CircRes This month on Episode 44 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the January 6th and January 20th issue of Circulation Research. This episode also features an interview with Dr Timothy McKinsey and Dr Marcello Rubino about their study, Article highlights: Prasad, et al. Cui, et al. Li, et al. Luo, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's Journal Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh. And today I'm going to be highlighting articles from our January 6th and January 20th issues of Circulation Research. I'm also going to have a chat with Dr Timothy McKinsey and Dr Marcello Rubino about their study, Inhibition of Eicosanoid Degradation Mitigates Fibrosis of the Heart. But before the interview, I want to get to a few articles to highlight. Cindy St. Hilaire: The first article is titled, Maintenance of Enteral ACE2 Prevents Diabetic Retinopathy in Type 1 Diabetes. The first authors are Ram Prasad and Jason Floyd, and the corresponding author is Maria Grant, and they are from the University of Alabama. Type 1 Diabetes has a complex etiology and pathology that are not entirely understood. In addition to the destruction of insulin-producing cells, a recently discovered feature of the disease in both humans and in rodent models is that the levels of angiotensin converting enzyme 2 or ACE2 can be unusually low in certain tissues. ACE2 is a component of the renin angiotensin system controlling hemodynamics and interestingly, genetic deficiency of ACE2 in rodents exacerbates aspects of diabetes such as gut permeability, systemic inflammation and diabetic retinopathy, while boosting ACE2 has been shown to ameliorate diabetic retinopathy in mice. This study shows that ACE2 treatment also improves gut integrity and systemic inflammation as well as retinopathy. Six months after the onset of diabetes in a mouse model, oral doses of a bacteria engineered to express humanized ACE2 led to a reversal of the animal's gut barrier dysfunction and its retinopathy. Humans with diabetic retinopathy also displayed evidence of increased gut permeability in low levels of ACE2. This study suggests they may benefit from a similar probiotic treatment. Cindy St. Hilaire: The next article I want to highlight is titled, Epsin Nanotherapy Regulates Cholesterol Transport to Fortify Atheroma Regression. The first authors are Kui Cui, Xinlei Gao and Beibei Wang, and the corresponding authors are Hong Chen and Kaifu Chen and they're from Boston Children's Hospital. Epsins are a family of plasma membrane proteins that drive endocytosis. They're expressed at varying levels throughout the tissues of the body, and recent research shows that they are unusually abundant on macrophages within atherosclerotic lesions. In mice, macrophage specific Epsin loss results in a reduction in foam cell formation and atherosclerotic plaque development. This study now shows that this effect on foam cells is because Epsins normally promote the internalization of lipids into macrophages through their endosytic activity. But that's not all. The proteins also impede cholesterol efflux from macrophages to further exacerbate lipid retention. It turns out out Epsins regulate the endocytosis and the degradation of a cholesterol efflux factor called ABCG1. Importantly, these pro atrogenic activities of Epsins can be stopped. Using macrophage targeted nanoparticles carrying Epson specific silencing RNA, the team could suppress reduction of the protein in cultured macrophages and could reduce the size and number of plaques in atherosclerosis prone mice. Together these results suggest blocking Epsins via nanotherapy or other means could be a therapeutic approach to stopping or slowing atherosclerotic plaque progression. Cindy St. Hilaire: The third article I want to highlight is coming from our January 20th issue of Circ Res and is titled, Hydrogen Sulfide Modulates Endothelial-Mesenchymal Transition in Heart Failure. The first author is Zhen Li, and the corresponding author is David Lefer and they're from Cedars-Sinai. Hydrogen sulfide is a critical endogenous signaling molecule that exerts protective effects in the setting of heart failure. Cystathionine γ-lyase, or CSE, is one of the three hydrogen sulfide producing enzymes, and it's predominantly localized in the vascular endothelium. Genetic deletion of CSE, specifically in the endothelium, leads to reduced nitric oxide bioavailability, impaired vascular relaxation and impaired exercise capacity, while genetic over-expression of PSE in endothelial cells improves endothelial cell dysfunction, and attenuates myocardial infarction following myocardial ischemia-reperfusion injury. In this study, endothelial cell specific CSE knockout mice and endothelial cell specific CSE overexpressing transgenic mice were subjected to transverse aortic constriction to induce heart failure with reduced ejection fraction. And the goal was to investigate the contribution of the CSE hydrogen sulfide access in heart failure. Endothelial specific CSE knockout mice exhibited increased endothelial to mesenchymal transition and reduced nitric oxide bioavailability in the myocardium. And this was associated with increased cardiac fibrosis, impaired cardiac and vascular function, and it worsened the vascular performance of these animals. In contrast, genetic overexpression of CSE in endothelial cells led to increased myocardial nitric oxide, decreased EndoMT and decreased cardiac fibrosis. It also improved exercise capacity. These data demonstrate that endothelial CSE modulates endothelial mesenchymal transition and ameliorated the severity of pressure overload induced heart failure , in part through nitric oxide related mechanisms. This data further suggests that endothelium derived hydrogen sulfide is a potential therapeutic for the treatment of heart failure with reduced ejection fraction. Cindy St. Hilaire The last article I want to highlight is titled, Flavonifractor plautii Protects Against Elevated Arterial Stiffness. The first authors are Shiyun Luo and Yawen Zhao, and the corresponding author is Min Xia, and they are at Sun Yat-sen University. Dysbiosis of gut microbiota contributes to vascular dysfunction and gut microbial diversity has been reported to be inversely correlated with arterial stiffness. However, the causal role of gut microbiota in the progression of arterial stiffness and the specific species along with the molecular mechanisms underlying this change remain largely unknown. In this study, the microbial composition in metabolic capacities were compared in participants with elevated arterial stiffness and in normal controls free of medication. And these groups were age and sex match. Human fecal metagenomic sequencing identified a significant presence of Flavonifractor plautii or F. plautii in normal controls, which was absent in the subjects with elevated arterial stiffness. The microbiome of normal controls exhibited an enhanced capacity for glycolysis and polysaccharide degradation, whereas individuals with increased arterial stiffness exhibited increased biosynthesis of fatty acids and aromatic amino acids. Additionally, experiments in the angiotensin II induced and humanized mouse model show that replenishment with F. plautii or its main effector cis-aconitic acid or CCA improved elastic fiber network and reversed increased pulse wave velocity through the suppression of matrix metalloproteinase-2 and through the inhibition of monocyte chemoattractant protein-1. And this was seen in both the angiotensin II induced and humanized models of arterial stiffness. This study now identifies a novel link between F. plautii and arterial function and raises the possibility of sustaining vascular health by targeting the gut microbiota. Cindy St. Hilaire: Today with me I have Dr Tim McKinsey and Dr Marcello Rubino from the University of Colorado Anschutz Medical Campus, and we're here to talk about their paper Inhibition of Eicosanoid Degradati`on Mitigates Fibrosis of the Heart. And this article is in our January 6th issue of Circulation Research, so thank you both so much for joining me today. Timothy McKinsey: Thank you for inviting us. Marcello Rubino: Yeah, thank you for the opportunity. Cindy St. Hilaire: And so Dr McKinsey, you're a professor at the University of Colorado. How long have you been investigating cardiac fibrosis? Timothy McKinsey: Oh, a long time. Before I started the lab here in 2010, I was in industry working in biotech with Myogenic Gilead, and we were very interested in cardiac fibrosis all the way back then. Cindy St. Hilaire: Oh wow, so you actually made an industry to academia transfer. Timothy McKinsey: Yes. Cindy St. Hilaire: Good topic for another podcast. That is really great. Timothy McKinsey: Yeah, it's of interest to a lot of people, including trainees. Cindy St. Hilaire: Yeah, I bet. Dr Rubino, you were or are a postdoc in the McKinsey lab? Marcello Rubino: Yeah, I was a postdoc in Timothy McKinsey lab. I spent four years in Tim's lab. It was my first time studying cardio fibrosis, so it was a little bit difficult at the end, but I think I was right choosing Tim, so I'm really happy now. Cindy St. Hilaire: Nice and are you sticking with fibrosis or are you moving on? Marcello Rubino: Yeah, so now I'm back in Milan where I did my PhD student and postdoc. I am like an independent researcher, but it's still not a principal investigator, so I want to become one of the that, studying cardiac fibrosis. Yeah. And inflammation and epigenetics, so yeah, I'm going try to go to my way, thanks to Tim, I think that I find my own way. Cindy St. Hilaire: I'm sure you will. I mean, based on the great work in this study, right. Building upon that, I'm sure you'll be a success. Timothy McKinsey: No doubt about it. Cindy St. Hilaire: So your manuscript, this study, it's investigating whether eicosanoid availability can attenuate fibrosis in the heart. But before we kind of jump into this study, why is fibrosis in the heart a bad thing? Is it always detrimental? Is there some level of fibrosis that's necessary or even helpful? Timothy McKinsey: I mean, a certain level of extracellular matrix is deposited in your heart and that maintains the structure of the heart. Fibrosis can also be good after you have a myocardial infarction and a big piece of the muscle of your heart has died, it needs to be replaced with a fibrotic scar, essentially to prevent rupture of the ventricle. So fibrosis isn't always bad, but chronic fibrosis can be really deleterious to the heart and contribute to stiffening of the heart and cause diastolic dysfunction. It can create substrates for arrhythmias and sudden cardiac death. So we're really trying to block the maladaptive fibrosis that occurs in response to chronic stress. Cindy St. Hilaire: Yeah, yeah. And what about eicosanoids? What are they and what role do they play in cardiac fibrosis or what was known about their role in this process before your study? Timothy McKinsey: Eicosanoids are lipids, they're basically fatty acids, 20 carbon in length and a lot is known about them. It's a very complex system. There are many different eicosanoids, but they're produced from arachidonic acid through the action of cyclooxygenase enzymes like COX-2. And so you're probably familiar with the literature showing that non-steroidal anti-inflammatory drugs that target the COX enzymes can actually increase the risk of cardiac disease, so there was a lot known about what produces eicosanoids in the heart, but our study is really the first to address how they're degraded and how that controls cardiac fibrosis. Cindy St. Hilaire: What I thought you did really well in the introduction and what I guess I didn't really fully appreciate until I had read your study, was that your goal was to identify compounds that could attenuate fibrosis. And you spent some time emphasizing the differences between a targeted small molecule screen and a phenotype based screen. And I was wondering if you could just expand on this difference for the audience and maybe just explain why in your case you went with the latter. Timothy McKinsey: Well, we wanted to use an unbiased approach and some people call this a chemical biology approach where we took a targeted library, meaning we took compounds with known activities, meaning compounds that with known targets and we screened that library using a phenotypic assays that we developed in the lab. And the phenotypic assay is an unbiased assay, right? We're just screening for compounds that have the ability to block the activation of fibroblasts. And we monitor activation by looking at markers of fibroblast activation such as alpha smooth muscle Actin. And we can do this in a very quantitative and high throughput manner using this imaging system, high content imaging system that we have in the lab. It was an unbiased screen looking for inhibitors of fibroblasts activation across organ systems. We not only studied cardiac fibroblasts, but we also studied lung and renal fibroblasts looking for compounds with a common ability to block the activation state of each of those cell types. One of the things that I get asked frequently is how do we maintain the cardiac fibroblasts in a quiescent state? Because you may know this, but when fibroblasts are plated on cell culture plastic, which has a very high 10 cell strength, they tend to spontaneously activate, so we actually spent a couple of years working out the conditions to maintain the cells in quiescent state, and I think that will also be of great interest to the field. Cindy St. Hilaire: Probably even the smooth muscle cell biology field where I hang out and even valve interstitial cells that we study. All of those, I guess basic things related to cell culture, we have taken for granted that plastic is not physiological. Timothy McKinsey: Right. Cindy St. Hilaire: And so I think with this really nice phenotypic or chemical screen that you conducted, you first identified nine compounds, but what made you zero in on this one, SW033291? Timothy McKinsey: When we got the hits, we were intrigued by the SW compound SW033291 because there was only one paper describing its action and there was a paper published in Science showing that SW or inhibition of this enzyme 15-PGDH could enhance organ regeneration. Cindy St. Hilaire: Oh, okay. Timothy McKinsey: And there's a very interesting interplay between fibrosis and organ regeneration where fibrosis inhibits regeneration and if you can stimulate regenerative pathways, they can actually block fibrosis, so there's this back and forth. And so that's really the main reason we were interested in pursuing SW just because of the novelty and the potential. And also it was a compound that behaved beautifully in our cell culture models with beautiful dose-dependent inhibition of each of the fibroblast types. Cindy St. Hilaire: It's kind of like the cleanest thing to start with. Also, if there's nothing known, it's ripe for investigation, so that's great. You just said this SW compound acts on 15-PGDH, so what is the role of that protein in fibroblasts and what if any known effects are there on this protein's inhibition in other cell types or disease states? Marcello Rubino: In fibroblasts team, I would like to say that this was really the first article that was published. Maybe there was just one published in Pulmonary Fibrosis, but like last year, but I didn't really talk about 15-PGDH, so you need to consider that 15-PGDH is an inhibitor, an enzyme that degrades prostaglandin, so if you inhibit the inhibitor, the release increase production, a lot of prostaglandin. And so a lot of paper were talking about this effect, so they will see we are just using SW in order to increase Prostaglandin E2 level and that was why we had this like anti-inflammatory or whatever effect. I would like to say that until now, maybe this can be the first really paper talking about no more than not just prostaglandin but 15-PGDH. Its action total level, a global level at particularly on fibroblasts. To answer your question, I would like to say that this was also our question first and we checked by level other browser to try to find the answer to your question. We figured out that it was known that 15-PGDH was increasing a pathology condition in different organ, not just related by fibroblasts, not just related to cardiac disease, about the function with discover a function in macrophage that interested us because it can regulate maybe the polarization macrophage, so still involving the prostaglandin production inflammation, so that's why also we decide to take a look because it was still novel in fibrolbasts and we still know that it was doing something important and we were trying not to put the piece together and find something new in that we were lucky for this. Timothy McKinsey: 15-PGDH is actually expressed at very low levels in fibroblasts. It's much more highly expressed in macrophage, just as Marcello pointed out, so in the future we're very interested in knocking out or inhibiting 15-PGDH in different cell types to see how that contributes to inhibition of cardiac fibrosis. Cindy St. Hilaire: Really interesting. Related to that, you used a couple different animal models for fibrosis. They're all different or special in their own way. How well did these recapitulate what we observe in humans. Are there any limitations of benefits? Timothy McKinsey: They're always limitations to animal models. We started out with a very robust commonly used model of cardiac fibrosis, which relies on Angiotensin II infusion in mice. We like that model because it's robust and quick so we can get answers quickly. And then we transitioned into a model of diastolic dysfunction that we've been working with in a lab where we remove a kidney from a mouse and we implant something called DOCA, which is an aldosterone memetic. And so the animals develop hypertension that leads to a mild but significant diastolic dysfunction with preserved ejection fraction. And that's a model that we like a lot. It has something that we call hidden fibrosis, so if you just do standard histochemical... /episode/index/show/circresearch/id/25648197

December 2022 Discover CircRes 12/15/2022

December 2022 Discover CircRes This month on Episode 43 of Discover CircRes, guest host Nicole Purcell highlights two original research articles featured in the December 2 issue of Circulation Research. This episode also features an interview with Drs Aaron Phillips and Kevin O'Gallagher about their study, The Effect of a Neuronal Nitric Oxide Synthase Inhibitor on Neurovascular Regulation in Humans. Article highlights: Akerberg, et al. Lv, et al. Nicole Purcell: Hi and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I am your host, Dr Nicole Purcell, from the Huntington Medical Research Institutes in Pasadena, California, and today I will be highlighting two articles from our December 2 issue of Circulation Research. I'll also have a chat with Drs Aaron Phillips and Kevin O'Gallagher about their study, The Effect of a Neuronal Nitric Oxide Synthase Inhibitor on Neurovascular Regulation in Humans. Nicole Purcell: But before I get to the interview, here are a few article highlights. The first article we're going to highlight is RBPMS2 Is a Myocardial Enriched Splicing Regulator Required for Cardiac Function. This comes from Boston Children's Hospital with first author Dr Alexander Akerberg, and corresponding author Dr Jeffrey Burns. RNA splicing, along with transcription control and post-translational modifications, is a mechanism for fine tuning the expression of a gene for a particular purpose in a particular tissue. Factors that control splicing are thus often enriched in certain cell types. The factor, RBPMS2, for example, is enriched in the myocytes of amphibians, fish, birds and mammals. This conserve tissue specificity suggesting essential role of RBPMS2 in heart function. Akerberg and colleagues now confirm this is indeed the case. They generated zebra fish embryos and human cardiomyocytes lacking RBPMS2, and found the fish suffered early cardiac dysfunction by 48 hours post fertilization. The animal's hearts had reduced ejection fractions, compared with the hearts of controlled fish. At the cellular level, the RBPMS2 lacking fish cardiomyocytes displayed malformed sarcomere fibers and disrupted calcium handling, both of which were also seen in the RBPMS2 deficient human cardiomyocytes. Furthermore, RNA sequencing experiments revealed a conserve set of 29 genes in the RBPMS2-lacking fish and human cells that were incorrectly spliced. In revealing the essential cardiac role of RBPMS2 and its RNA targets, the work provides new molecular details for understanding vertebrate heart function and disease, say the team. Nicole Purcell: Our second article being highlighted is Blocking MG53 Serine 255 Phosphorylation Protects Diabetic Heart from Ischemic Injury. This comes from Peking University with first authors, Fengxiang L, Yingfan Wang and Dan Shan, as well as corresponding author Dr Rui-Ping Xiao. Midsegment 53, or MG53, is a recently discovered muscle-specific protein that is an essential component of the cell membrane repair machinery with cardioprotective effects. MG53 thus has therapeutic potential, but for patients whose heart disease is linked to type 2 diabetes, there's a problem. MG53 also tags certain cellular proteins for destruction, including the insulin receptor and the insulin signaling factor, IRS1. Loss of these factors could worsen insulin resistance. lev and colleagues therefore investigate whether MG53 could be tweaked to provide protection without the diabetes downside. Nicole Purcell: They discovered the phosphorylation of MG53 at serine 255 is required for its role in protein destruction, and that a mutant version of MG53, incapable of this phosphorylation, MG53 serine to 255 alanine mutant, could still promote cardiomyocyte survival, and protect the cells from membrane damaging insults. Importantly, when a diabetic mouse model was injected with MG53 serine 255 to alanine mutant, the protein better protected the animals against myocardial infarction than injection with the wild type MG53, recipients of which had poor insulin sensitivity. Based on these findings, the authors suggest MG53 serine 255 alanine mutant could be developed into a heart protective drug, for use in diabetic and non-diabetic patients alike. Nicole Purcell: Today, Dr Aaron Phillips and Dr Kevin O'Gallagher from University of Calgary are with me to discuss their study, the Effect of a Neuronal Nitric Oxide Synthase Inhibitor on Neurovascular Regulation in Humans in our December 2 issue of Circulation Research. Thank you for joining me today. Kevin O'Gallagher: Hello, my name's Dr Kevin O'Gallagher. I'm a British Heart Foundation clinician scientist and interventional cardiologist at Kings College London and Kings College Hospital NHS Foundation Trust. Aaron Phillips: Hello, my name's Dr Aaron Phillips. I'm an associate professor in physiology, pharmacology, cardiac sciences, biomedical engineering and clinical neurosciences at the University of Calgary in the Hotchkiss Brain Institute and Libin Cardiovascular Institute. I am also the director of the Restore Network, which is a large platform at the University of Calgary spanning all these groups, developing new tools and techniques for translational research into neurological conditions. Nicole Purcell: There are a lot of authors involved in this study. While all could not join us, I appreciate you taking the time to discuss your findings today. Your paper deals with looking at neurovascular control in humans. Two primary regulatory pathways are neurovascular coupling, or NVC, and dynamic cerebral autoregulation. Dr Phillips, can you explain what NVC to our audience, and what does dysregulation lead to? Aaron Phillips: Yeah, thanks Nicole and I'm happy to be here. Thank you for the invitation. NVC, or neurovascular coupling, we've been studying it for about 15 years. At its fundamental level, it's kind of this elegant interplay between neurons, which unfortunately have very limited capacity for substrate storage. The brain has very limited substrate storage capacity, and so neurons need to very rapidly match their metabolic activity to the blood flow that's being delivered to them, and that needs to happen locally, for areas of the brain that have greater metabolic needs as opposed to other areas. What happens, in terms of dysregulation or conditions that are associated with dysregulation, it's an interesting story because we still really need to understand the mechanisms fully, in order to suss out what clinical conditions should have dysfunction of this unit. We know that certain conditions, such as vascular cognitive impairment, even spinal cord injury, we've done some work in stroke patients, it seems to be dysfunctional in all of these conditions, but understanding exactly why it's dysfunctional, we're still establishing that. Nicole Purcell: Great. You were talking about how it's the connection or interplay between blood flow, so we're talking about altered blood pressure seems to play a key role in neurovascular coupling. So, for those listeners not familiar with this field, can you explain how nitric oxide synthase and its isoforms, how this relates to NVC? Aaron Phillips: Well, nitric oxide synthase is an enzyme that produces nitric oxide that's expressed primarily in neurons. Nitric oxide is a powerful vasodilator. It actually works on quite a rapid time course. So, we surmised, we suspected, and there were some preclinical work before our human study, that neuronal sources of nitric oxide, being that nitric oxide is a potent vasodilator, we thought that would be likely to be mediating a large part of the neurovascular coupling response. Nicole Purcell: Great. So, Dr O'Gallagher, based on that, what was your main objective or hypothesis of this study, and how is your study novel from those that have already just suggested, looked at NOS regulation for cerebral blood flow? Kevin O'Gallagher: Thanks very much for the invite to talk. I mean, we hypothesized that nNOS would have a role in regulating neurovascular coupling. I think the novelty of our study is that although people have been interested in NOS and its regulation of cerebral vascular and cardiovascular blood flow, it's only relatively recently that there has become an agent available that will specifically inhibit nNOS, and therefore give us an idea of what it is doing, rather than previous inhibitors which just inhibit all of the three NOS isoforms. It was really that the development of the agent was what allowed us to do this study. I think it was really through that, that makes this an interesting finding that nNOS does play a role in neurovascular coupling, and really pushes the field forward ever so slightly. Nicole Purcell: Great. So, as you pointed out, this is a specific nNOS inhibitor, which is known as SMTC. It's a synthetic L-Arginine analog, right? That's really what sets your study apart. Can you tell us a little bit the audience, whether that be you, Dr Phillips or Dr O'Gallagher, about what your study was and what did you find, and how did an ambition of using this SMTC to inhibit nNOS affect systemic hemodynamic changes and NVC? Aaron Phillips: Yeah, I think both of us can probably speak to this interchangeably and add in different elements of the experiment. This is kind of a summary of the study, I guess. In advance of this, adding on what Kevin had just said in terms of the novelty of the study and the importance, we had done a lot of work previous to this paper where we were one of the groups that helped establish neurovascular coupling as a measure that could be tested in humans. This involved kind of understanding metabolism of the eye, how that's coupled to the visual cortex, and how to measure blood flow on a high temporal resolution in the visual cortex in response to visual input. That's why we used very well standardized perturbations involving tracking an eye, tracking a dot on a screen at a known one rate and a known one amplitude of movement, while also measuring the hyperemic response in the posterior brain. Then we kind of went on and developed some new measures, developed some software that we're now proud is used in a few different labs around the world, that kind of automatically takes that input of repetitive eyes opening and closing and that hyperemic response, and it breaks it down into a single wave form. A single hyperemic response is superimposed of 10, 15, 20 cycles of those eyes open and eyes closed, and then when we superimpose all the wave forms together, we can generate different metrics from that hyperemic response that correspond to different elements. One of the ways where software can, I guess dice out the hyperemic response, is by timing. We can look at very specific unique time windows over that 30 seconds of eyes open, and we can also look at the slope of the response, as well as we recently did some dimensionality reduction techniques and looked at specific computed measures of that hyperemic response. We published that a few years ago. Those were some of the tools that enabled this study, along with a fantastically unique drug that really could isolate that neuron expression of NOS and the capacity of nNOS to mediate neurovascular coupling. Kevin O'Gallagher: Obviously, we're going to use a systemic infusion of SMTC, the study drug, and we've used that before and shown it to be safe. But because a systemic infusion of SMTC through peripheral and systemic nNOS inhibition does cause an increase in systemic vascular resistance, and therefore an increase in mean arterial pressure of around about 7 mm of mercury, in addition to a cline placebo control condition, we also felt the need to have a pressure control condition. For that, we used phenylephrine to match the rise in mean arterial pressure that we anticipated we'd see with SMTC. We ended up with 12 healthy volunteers who attended on three separate visits, and so we had a party randomized double blinded intervention study where we measured the neurovascular coupling metrics, both before and after an infusion of one of the three conditions on each particular visit. Aaron Phillips: I just wanted to add into that, we had found previously that mean arterial pressure does have an effect on the hyperemic response. This was actually classically found by 1960s by Harper and Glass in a dog study, but we've repeated that in humans and kind of found that the ability of the brain to kind of... It's reserve for further vasodilation is dependent on pressure. As you drop it, neurovascular coupling will go away, and as you increase it, neurovascular coupling will increase partially, so it's important to standardize the mean arterial pressure levels. I always liken it to your water pressure in your house. You can't turn on a faucet with a given pressure unless you have that in the system upstream. That was a really important aspect of the study. Nicole Purcell: That was quite unique for your study, too. Not a lot of people have control for pressure. Aaron Phillips: Correct. Kevin O'Gallagher: I think it reflects the challenges of these healthy volunteer studies where you're trying to look at one particular part of the cardiovascular system, because as a cardiologist, if we were doing a study like this, looking at cardiovascular regulation, we would put a catheter into the coronary arteries in patients who had come for angiograms, and we'd give a local infusion of SMTC, as we've done in studies before. But with healthy volunteers, and ethically it really demanded a systemic infusion, so it was a really nice workaround to have that pressure control condition. Nicole Purcell: So, can you tell us a little bit about what your findings were? Kevin O'Gallagher: I think testament to the study design and the rigorous methodology that we employed, we did find with the resting steady state hemodynamics that SMTC condition performed as we would expect, and as we've seen in prior studies where we've given a systemic dose in that compared to both placebo and pressure control conditions, SMTC decreased cardiac output, and it decreased stroke volume, and also increased systemic vascular resistance, so very much as expected the resting hemodynamic conditions. Aaron Phillips: Yeah, thanks. Just adding onto that, moving on into some of the cerebral vascular measures. So again, we were measuring posterior cerebral artery velocity, blood velocity and specific responsiveness that it has to a visual stimuli. Between conditions, we didn't see a change in resting posterior cerebral artery velocity, so that was consistent between the conditions. Where we saw most of our change actually was in this very early period, the first five seconds of what we're going to call the hyperemic response, or the first five seconds of the neurovascular coupling response. That's where we saw our primary effect. We didn't see an effect in almost any of the neurovascular coupling measures that we generated in the actual sustained period after that initial rise, so that's where we saw our key inhibition with nNOS inhibition. What permitted that was the phenylephrine control group, again, allowing us to really look at apples and apples, not apples and oranges. Nicole Purcell: Great. So that early transient change that you saw, that as you said, hyperemic response, what therapeutic implications does this have for the field? Kevin O'Gallagher: Well, certainly there are conditions in which nNOS dysfunction, nNOS may be implicated, we mentioned a couple in the paper, some neurodegenerative diseases. But also, I think the field is now open for any vascular mediated headache syndrome, such as migraine, to investigate the potential role of nNOS from that angle. Then we haven't touched on already, but as well as dysfunctional, so decreased nNOS activity, there's also some conditions in which there's dysregulation or abnormally increased nNOS function. Again, we've highlighted this kind of study methodology is a tool that could be used to investigate those types of conditions. Aaron Phillips: These are all terrific points, and I think there's a lot of conditions where neurovascular coupling is impaired, and it's worth exploring them and understanding the specific role where nNOS might be a part of it. I also think there's a lot of interesting basic science surrounding this, in terms of the mechanisms. What was really interesting in this study, which is still kind of wracking my brain, is why didn't more of the neurovascular coupling response go away? This is a highly selective inhibitor for what was potentially thought by some groups to be a large mediator, this response. It was a relatively small inhibitory effect, and isolated to a small part of the neurovascular coupling response, just that early phase. So, still lots of work to do to kind of dice out the other pathways. They're probably highly redundant. This is such a critical mechanism in the central nervous system. Getting at it and humans is going to be tricky, but we're excited about the future and exploring some of those other avenues on the mechanistic cascade. Nicole Purcell: Based on the fact that you just had 12 healthy individuals, what do you see as some of the limitations of your study going forward, thinking about what you did? Kevin O'Gallagher: I think you've just hit on a key limitation. It was a small number of volunteers. They were all healthy, so we can't extrapolate these findings to conditions such as hypertension, where we know from other studies that cardiovascular responses, nNOS responses are impaired Also, this was a noninvasive study. We looked at the blood flow through Doppler, but we don't really know the effect of SMTC on cerebral artery diameter or other markers like that, so I think those are important limitations to mention. Nicole Purcell: I know I didn't ask this, and I know it was mentioned in the paper, but for our audience, and it was a small sample size, but did you see any sex differences between your male and female cohort? Kevin O'Gallagher: No. We did analyze for that and there were no sex... /episode/index/show/circresearch/id/25341690

November 2022 Discover Circ Res 11/17/2022

November 2022 Discover Circ Res This month on Episode 42 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the October 28 and November 11th issues of Circulation Research. This episode also features an interview with Dr Miguel Lopez-Ramirez and undergraduate student Bliss Nelson from University of California San Diego about their study, Neuroinflammation Plays a Critical Role in Cerebral Cavernous Malformations. Article highlights: Jia, et al. Rammah, et al. Wang, et al. Katsuki, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today, I'm going to be highlighting articles from our October 28th and our November 11th issues of Circ Res. I'm also going to have a chat with Dr Miguel Lopez-Ramirez and undergraduate student Bliss Nelson, about their study, Neuroinflammation Plays a Critical Role in Cerebral Cavernous Malformations. But, before I get into the interviews, here are a few article highlights. Cindy St. Hilaire: The first article is from our October 28th issue, and the title is, PHB2 Maintains the Contractile Phenotype of Smooth Muscle Cells by Counteracting PKM Splicing. The corresponding author is Wei Kong, and the first authors are Yiting Jia and Chengfeng Mao, and they are all from Peking University. Insults to blood vessels, whether in the form of atherosclerosis, physical injury, or inflammation, can trigger vascular smooth muscle cells to transition from a contractile state to a proliferative and migratory one. Accompanying this conversion is a switch in the cells' metabolism from the mitochondria to glycolysis. But what controls this switch? To investigate, this group compared the transcriptomes of contractile and proliferative smooth muscle cells. Among the differentially expressed genes, more than 1800 were reciprocally up and down regulated. Of those, six were associated with glucose metabolism, including one called Prohibitin-2, or PHB2, which the team showed localized to the artery wall. In cultured smooth muscle cells, suppression of PHB2 reduced expression of several contractile genes. While in rat arteries, injury caused a decrease in production of PHB2 itself, and of contractile markers. Furthermore, expression of PHB2 in proliferative smooth muscle cells could revert these cells to a contractile phenotype. Further experiments revealed PHB2 controlled the splicing of the metabolic enzyme to up-regulate the phenotypic switch. Regardless of mechanism, the results suggest that boosting PHB2 might be a way to reduce adverse smooth muscle cell overgrowth and conditions such as atherosclerosis and restenosis. Cindy St. Hilaire: The second article I'm going to highlight is also from our October 28th issue, and the first authors are Mayassa Rammah and Magali Theveniau-Ruissy. And the corresponding authors are Francesca Rochais and Robert Kelly. And they are all from Marseille University. Abnormal development of the heart's outflow track, which ultimately forms the bases of the aorta and the pulmonary artery, accounts for more than 30% of all human congenital heart defects. To gain a better understanding of outflow tract development, and thus the origins of such defects, this group investigated the role of transcription factors thought to be involved in specifying the superior outflow tract, or SOFT, which gives rise to the subaortic myocardium, and the inferior outflow tract, which gives rise to the subpulmonary myocardium. Transcription factor S1 is over-expressed in superior outflow tract cells and the transcription factors, TBX1 and PPAR gamma, are expressed in inferior outflow tract cells. And now this group has shown that TBX1 drives PPAR gamma expression in the inferior outflow tract, while Hess-1 surpasses PPAR gamma expression in the superior outflow tract. Indeed, in mouse embryos lacking TBX1, PPAR gamma expression was absent in the outflow tract. While in mouse embryos lacking Hess-1, PPAR gamma expression was increased and PPAR gamma positive cells were more widespread in the outflow tract. The team also identified that signaling kinase DLK is an upstream activator of Hess-1 and a suppressor of PPAR gamma. In further detailing the molecular interplay regulating outflow tract patterning, the work will shed light on congenital heart disease etiologies, and inform potential interventions for future therapies. Cindy St. Hilaire: The third article I want to highlight is from our November 11th issue of Circulation Research, and the title is Histone Lactylation Boosts Reparative Gene Activation Post Myocardial Infarction. The first author is Jinjin Wang and the corresponding author is Maomao Zhang, and they're from Harbin Medical University. Lactylation of histones is a recently discovered epigenetic modification that regulates gene expression in a variety of biological processes. In inflammation, for example, a significant increase in histone lactylation is responsible for switching on reparative genes and macrophages when pro-inflammatory processes give way to pro-resolvin ones. The role of histone lactylation in inflammation resolution has been shown in a variety of pathologies, but has not been examined in myocardial infarction. Wang and colleagues have now done just that. They isolated monocytes from the bone marrow and the circulation of mice at various time points after induced myocardial infarctions, and examined the cells' gene expression patterns. Within a day of myocardial infarction, monocytes from both bone marrow and the blood had begun upregulating genes involved in inflammation resolution. And, concordant with this, histone lactylation was dramatically increased in the cells, specifically at genes involved in repair processes. The team went on to show that injection of sodium lactate into mice boosted monocyte histone lactylation and improved heart function after myocardial infarction, findings that suggest further studies of lactylation's pro-resolving benefits are warranted. Cindy St. Hilaire: The last article I want to highlight is titled, PCSK9 Promotes Macrophage Activation via LDL Receptor Independent Mechanisms. The first authors are Shunsuke Katsuki and Prabhash Kumar Jha, and the corresponding author is Masanori Aikawa, and they are from Brigham and Women's Hospital in Harvard. Statins are the go-to drug for lowering cholesterol in atherosclerosis patients. But the more recently approved PCSK9 inhibitors also lower cholesterol and can be used to augment or replace statins in patients where these drugs are insufficient. PCSK9 is an enzyme that circulates in the blood and destroys the LDL receptor, thereby impeding the removal of bad cholesterol. The enzyme also appears to promote inflammation, thus potentially contributing to atherosclerosis in two ways. This group now confirms that PCSK9 does indeed promote pro-inflammatory macrophage activation and lesion development, and does so independent of its actions on the LDL receptor. The team assessed PCSK9-induced lesions in animals with saphenous vein grafts, which are commonly used in bypass surgery but are prone to lesion regrowth. They found that LDL receptor lacking graft containing mice had greater graft macrophage accumulation and lesion development when PCSK9 activity was boosted than when it was not. The animal's macrophages also had higher levels of the pro-inflammatory factor expression. Together, this work shows that PCSK9 inhibitors provide a double punch against atherosclerosis and might be effective drugs for preventing the all too common failure of saphenous vein grafts. Cindy St. Hilaire: So, today with me I have Dr Miguel Lopez-Ramirez and undergraduate student Bliss Nelson from the University of California in San Diego, and we're going to talk about their study, Neuroinflammation Plays a Critical Role in Cerebral Cavernous Malformation Disease, and this article is in our November 11th issue of Circulation Research. Thank you both so much for joining me today. Before we talk about the science, want to just maybe tell me a little bit about yourselves? Bliss Nelson: My name is Bliss Nelson. I'm a member of Miguel Lopez-Ramirez's lab here at UC San Diego at the School of Medicine. I'm an undergraduate student here at UC San Diego. I'm actually a transfer student. I went to a community college here in California and I got involved in research after I transferred. Cindy St. Hilaire: What's your major? Bliss Nelson: I'm a cognitive science major. Cindy St. Hilaire: Excellent. You might be the first undergrad on the podcast, which is exciting. Bliss Nelson: Wow. What an honor. Thank so much. Cindy St. Hilaire: And Miguel, how about you? Miguel Lopez-Ramirez: Yes, thank you. Well, first thank you very much for the opportunity to present our work through this media. It's very exciting for us. My name is Miguel Alejandro Lopez-Ramirez, and I'm an assistant professor in the Department of Medicine and Pharmacology here at UCSD. Cindy St. Hilaire: Wonderful. I loved your paper, because, well, first, I don't think I've talked about cerebral cavernous malformations. So what are CCMs, and why are they so bad? Bliss Nelson: Cerebral cavernous malformations, or CCMs for short, are common neurovascular lesions caused by a loss of function mutation in one of three genes. These genes are KRIT1, or CCM1, CCM2 and PDCD10, or CCM3, and generally regarded as an endothelial cell autonomous disease found in the central nervous system, so the brain and the spinal cord. The relevance of CCMs is that it affects about one in every 200 children and adults, and this causes a lifelong risk of chronic and acute hemorrhaging. CCMs can be quiescent or dynamic lesions. If they are dynamic, they can enlarge, regress, or behave progressively, producing repetitive hemorrhaging and exacerbations of the disease. Other side effects of the disease could be chronic bleedings, focal neurological deficits, headaches, epileptic seizures and, in some cases, death. There's no pharmacological treatment for CCMs. There's only one type of option some patients may have, which would be to have surgery to cut out the lesions. But of course this depends on where the lesion or lesions are in the central nervous system, if that's even an option. So sometimes there's no option these patients have, there's no treatment, which is what propels our lab to towards finding a pharmacological treatment or uncovering some of the mechanisms behind that. Cindy St. Hilaire: Do people who have CCM know that they have them or sometimes it not detected? And when it is detected, what are the symptoms? Bliss Nelson: Sometimes patients who have them may not show any symptoms either ever in their lifetime or until a certain point, so really the only way to find out if you were to have them is if you went to go get a brain scan, if you went to go see a doctor, or if you started having symptoms. But also, one of the issues with CCMs is that they're very hard to diagnose, and in the medical community there's a lack of knowledge for CCMs, so sometimes you may not get directed to the right specialist in time, or even ever, and be diagnosed. Miguel Lopez-Ramirez: I will just add a little bit. It is fabulous, what you're doing. I think this is very, very good. But yes, that's why they're considered rare disease, because it's not obvious disease, so sometimes most of the patient, they go asymptomatic even when they have one lesions, but there's still no answers of why patients that are asymptomatics can become symptomatics. And there is a lot in neuro study, this study that we will start mentioning a little bit more in detail. We try to explain these transitions from silent or, quiescent, lesion, into a more active lesion that gives the disability to the patient. Some of the symptoms, it can start even with headaches, or, in some cases, they have more neurological deficits that could be like weakness in the arms or loss of vision. In many cases also problems with the speech or balance. So it depends where the lesion is present, in the brain or in the spinal cord, the symptoms that the patient will experience. And some of the most, I will say, severe symptoms is the hemorrhagic stroke and the vascular thrombosis and seizure that the patients can present. Those would be the most significant symptoms that the patient will experience. Cindy St. Hilaire: What have been some limitations in the study of CCMs? What have been limitations in trying to figure out what's going on here? Bliss Nelson: The limitations to the disease is that, well, one, the propensity for lesions, or the disease, to come about, isn't known, so a lot of the labs that work on it, just going down to the basic building blocks of what's even happening in the disease is a major problem, because until that's well established, it's really hard to go over to the pharmacological side of treating the disease or helping patients with the disease, without knowing what's going on at the molecular level. Cindy St. Hilaire: You just mentioned molecular level. Maybe let's take a step back. What's actually going on at the cellular level in CCMs? What are the major cell types that are not happy, that shift and become unhappy cells? Which are the key players? Bliss Nelson: That's a great question and a great part of this paper. So when we're talking about the neuroinflammation in the disease, our paper, we're reporting the interactions between the endothelium, the astrocytes, leukocytes, microglia and neutrophils, and we've actually coined this term as the CaLM interaction. Cindy St. Hilaire: Great name, by the way. Bliss Nelson: Thank you. All props to Miguel. And if you look at our paper, in figure seven we actually have a great graphic that's showing this interaction in play, showing the different components happening and the different cell types involved in the CaLM interaction that's happening within or around the CCM lesions. Cindy St. Hilaire: What does a astrocyte normally do? I think our podcast listening base is definitely well versed in probably endothelial and smooth muscle cell and pericyte, but not many of us, not going to lie, including me, really know what a astrocyte does. So what does that cell do and why do we care about its interaction with the endothelium? Miguel Lopez-Ramirez: Well, the astrocytes play a very important role. Actually, there are more astrocytes than any other cells in the central nervous system, so that can tell you how important they are. Obviously play a very important role maintaining the neurological synapses, maintaining also the hemostasis of the central nervous system by supporting not only the neurons during the neural communication, but also by supporting the blood vessels of the brain. All this is telling us that also another important role is the inflammation, or the response to damage. So in this case, what also this study proposed, is that new signature for these reactive astrocytes during cerebral malformation disease. So understanding better how the vasculature with malformations can activate the astrocytes, and how the astrocytes can contribute back to these developing of malformations. It will teach us a lot of how new therapeutic targets can be implemented for the disease. This is part of this work, and now we extend it to see how it can also contribute to the communication with immune cells as Bliss already mentioned. Cindy St. Hilaire: Is it a fair analogy to say that a astrocyte is more similar to a pericyte in the periphery? Is that accurate? Miguel Lopez-Ramirez: No, actually there are pericytes in the central nervous system as well. They have different roles. The pericyte is still a neuron cell that give the shape, plays a role in the contractility and maintains the integrity of the vessels, while the astrocyte is more like part of the immune system, but also part of the supporting of growth factors or maintaining if something leaks out of the vasculature to be able to capture that. Cindy St. Hilaire: You used a handful of really interesting mouse models to conduct this study. Can you tell us a little bit about, I guess, the base model for CCM and then some of the unique tools that you used to study the cells specifically? Bliss Nelson: Yeah, of course. I do a lot of the animal work in the lab. I'd love to tell you about the mouse model. So to this study we use the animal model with CCM3 mutation. We use this one because it is the most aggressive form of CCM and it really gives us a wide range of options to study the disease super intricately. We use tamoxifen-regulated Cre recombinase under the control of brain endothelial specific promoter, driving the silencing of the gene CCM3, which we call the PDCD10 betco animal, as you can see in our manuscript. To this, the animal without the Cre system, that does not develop any lesions, that we use as a control, we call the PDCD10 plox. And these animals are injected with the tamoxifen postnatally day one, and then for brain collection to investigate, wcollected at different stages. So we do P15, which we call the acute stage, P50, which we term the progressive stage, and then P80, which is the chronocytes stage. And after enough brain collections, we use them for histology, gene expression, RNA analysis, flow cytometry, and different imaging to help us further look into CCMs. Cindy St. Hilaire: How similar is a murine CCM to a human CCM? Is there really good overlap or are there some differences? Miguel Lopez-Ramirez: Yes. So, actually, that's a very good question, and that's part of the work that we are doing. This model definitely has advantages in which the lesions of the vascular formations are in an adult and juvenile animals, which represent an advantage for the field in which now we will be able to test pharmacological therapies in a more meaningful, way where we can test different doses, different, again, approaches. But definitely, I mean, I think... /episode/index/show/circresearch/id/25039365

October 2022 Discover Circ Res 10/20/2022

October 2022 Discover Circ Res This month on Episode 41 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the September 30 and October 14 issues of Circulation Research. This episode also features an interview with Dr Kory Lavine and Dr Chieh-Yu Lin from Washington University St. Louis, to discuss their study, Transcriptional and Immune Landscape of Cardiac Sarcoidosis. Article highlights: Tian, et al. Wleklinski, et al. Masson, et al. Li, et al. Cindy St. Hilaire: Hi, and welcome to Discover Circ Res, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cynthia St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to highlight articles from our September 30th and October 14th issues of Circulation Research. I'm also going to have a chat with Dr Kory Lavine and Dr Chieh-Yu Lin from Washington University St. Louis, and we're going to discuss their study Transcriptional and Immune Landscape of Cardiac Sarcoidosis. But before I get to the interview, I'm going to highlight a few articles. Cindy St. Hilaire: The first article I'm going to share is Extracellular Vesicles Regulate Sympathoexcitation by Nrf2 in Heart Failure. The first author of this study is Changhai Tian, and the corresponding author is Irving Zucker, and they are at University of Nebraska. After a myocardial infarction, increased oxidative stress in the heart can contribute to adverse cardiac remodeling, and ultimately, heart failure. Nrf2 is a master activator of antioxidant genes, suggesting a protective role, but studies in rats have shown its expression to be suppressed after MI, likely due to upregulation of Nrf2-targeting microRNAs. These microRNAs can also be packaged into vesicles and released from stressed heart cells. Now, this group has shown that rats and humans with chronic heart failure have an abundance of these microRNA-containing EVs in their blood. In the rats with chronic heart failure, these extracellular vesicles were found to be taken up by neurons of the rostral ventrolateral medulla, RVLM, wherein the microRNA suppressed Nrf2 expression. The RVLM is a brain region that controls the sympathetic nervous system, and in the presence of EVs, it is ramped up by sympathetic excitation. Because such elevated sympathetic activity can induce the fight or flight response, including increased heart rate and blood pressure, this would likely worsen heart failure progression. The team, however, found that inhibiting microRNAs in the extracellular vesicles prevented Nrf2 suppression in the RVLM and sympathetic activation, suggesting the pathway could be targeted therapeutically. Cindy St. Hilaire: The next article I want to highlight is titled, Impaired Dynamic Sarcoplasmic Reticulum Calcium Buffering in Autosomal Dominant CPVT2. The first author of this study is Matthew Wleklinski, and the corresponding author is Bjӧrn Knollmann, and they are at Vanderbilt University. Exercise or emotional stress can prompt the release of catecholamine hormones, which induce a fast heart rate, increased blood pressure, and other features of the fight or flight response. For people with catecholaminergic polymorphic ventricular tachycardia, or CPVT, physical activity or stress can cause potentially lethal arrhythmias. Mutations of calsequestrin-2, or CASQ2, which is a sarcoplasmic reticulum calcium-binding protein, is a major cause of CPVT, and can be recessive or dominant in nature. For many recessive mutations, disease occurs due to loss of CASQ2 protein. This group investigated a dominant lysine to arginine mutation in this protein, and found by contrast, protein levels remain normal. In mice carrying the mutation, not only was the level of CASQ2 comparable to that in control animals, but so, too, was the protein's subcellular localization. The mutation instead interfered with CASQ2's calcium binding or buffering capability within the sarcoplasmic reticulum. The result was that upon catecholamine injection or exercise, the unbound calcium released prematurely from the sarcoplasmic reticulum, triggering spontaneous cell contractions. In uncovering this novel molecular etiology of CPVT, the work provides a basis for studying the consequences of other dominant CASQ2 mutations. Cindy St. Hilaire: The next article I want to highlight is from our October 14th issue of Circulation Research, and the title of the article is ORAI1 Inhibitors as Potential Treatments for Pulmonary Arterial Hypertension. The first author is Bastien Masson, and the corresponding author is Fabrice Antigny, and they're from Inserm in France. In pulmonary arterial hypertension, the arteries of the lungs become progressively obstructed, making it harder for the heart to pump blood through them, ultimately leading to right ventricular hypertrophy and heart failure. A contributing factor in the molecular pathology of pulmonary arterial hypertension is abnormal calcium handling within the pulmonary artery smooth muscle cells. Indeed, excess calcium signaling causes these cells to proliferate, migrate, and become resistant to apoptotic death, thus leading to narrowing of the vessel. This group now identified the calcium channel ORAI1 as a major culprit behind this excess signaling. Samples of lung tissue from pulmonary arterial hypertension patients and a pulmonary arterial hypertension rat model had significantly upregulated expression of this channel compared with controls. And in patient pulmonary arterial smooth muscle cells, the high ORAI1 levels resulted in heightened calcium influx, heightened proliferation, heightened migration and reduced apoptosis. Inhibition of ORAI1 reversed these effects. Furthermore, in pulmonary hypertension model rats, ORAI1 inhibition reduced right ventricle systolic pressure and attenuated right ventricle hypertrophy when compared with untreated controls. This study indicates that ORAI1 inhibitors could be a new potential target for treating this incurable condition. Cindy St. Hilaire: The last article I want to share is titled Faecalibacterium Prausnitzii Attenuates CKD via Butyrate-Renal GPR43 Axis. The first author of this study is Hong-Bao Li, and the corresponding author is Tao Yang, and they are from the University of Toledo. Progressive renal inflammation and fibrosis accompanied by hypertension are hallmarks of chronic kidney disease, which is an incurable condition affecting a significant chunk of the world's population. Studies indicate that chronic kidney disease is linked to gut dysbiosis. Specifically, depletion of lactobacillus bifidobacterium and faecalibacterium, prompting investigations into the use of probiotics. While supplements including lactobacillus and bifidobacterium have shown little effectiveness in chronic kidney disease, supplementations with F. prausnitzii have not been investigated. Now, this group has shown in a mouse model of chronic kidney disease that oral administration of F. prausnitzii has beneficial effects on renal function, reducing renal fibrosis and inflammation. This bacterial supplementation also produced the short chain fatty acid butyrate, which was found to be at unusually low levels in the blood samples from the CKD model mice and from chronic kidney disease patients. Oral supplementation with this bacterium boosted butyrate levels in the mice, and in fact, oral administration of butyrate itself mimicked the effects of the bacteria. These findings suggest that supplementation with F. prausnitzii or, indeed, butyrate could be worth investigating as a treatment for chronic kidney disease. Cindy St. Hilaire: Today I have with me Dr Kory Lavine and Dr Chieh-Yu Lin from Washington University St. Louis, and we're going to talk about their paper, Transcriptional and Immune Landscape of Cardiac Sarcoidosis. This is in our September 30th issue of Circulation Research. Welcome, and thank you for taking the time to speak with me today. Chieh-Yu Lin: Thank you for inviting us. It's a great honor to be here today. Kory Lavine: Thank you. Cindy St. Hilaire: Really great paper, ton of data, and hopefully, we can pick some of it apart. But before we get into it, I actually want to just talk about sarcoidosis generally. I know it's a systemic inflammatory disease that has this kind of aggregation of immune cells as its culprit, and it can happen in a bunch of different organs. It's mostly in the lung, but it's also, like you're studying, in the heart. Can you just give us a little bit of background? What is sarcoidosis, and how common is cardiac sarcoidosis? Chieh-Yu Lin: Well, this is actually a great question, and I'll try to answer it. You actually capture one of the most important kind of features for sarcoidosis. It happens in all kind of organ system, mostly commonly in lung, in lymph nodes, but also in heart, spleen, even in brain, or even orbit, like eyes. It's really a truly multisystemic disease that has been characterized by this aggregate of macrophages, or myeloid cells, with scattered multinucleated giant cells, as the name implies, have multiple nuclear big, chunky, cells that form an aggregate. That's kind of like a pathognomonic feature for sarcoidosis, whether it's happening in lung, in the heart. When any organ system, a lot of studies has been done, but as of now, a very clear pathogenesis or mechanism has been, I would say, still pretty elusive, or still remain quite unclear, despite all the great effort has been made in this field. The other thing is that a lot of the studies actually focusing on pulmonary sarcoidosis for good reasons. Actually, that's one of the most common manifestations. For cardiac sarcoidosis, although it's only effect in probably, I would say depends on the data, 20% to 30% of the outpatient that with sarcoidosis, with or without lung involvement. It's actually carry a very significant clinical implications as of matter that the presentation of cardiac sarcoidosis can be devastating and sometimes actually fatal. Some of the study actually show that cardiac sarcoidosis actually higher, up to 80%, just because the first presentation's actually, unfortunately, sudden cardiac death. That's why Kory and I, we teamed up. I'm a cardiothoracic pathologist, so in my clinical practice I see specimens and samples from human body, from patient suffer from sarcoidosis, both in lung, lymph node, and heart. Kory is an outstanding heart failure, heart transplant cardiologist, see the other end, which is the patient care. This disease, specifically in heart, its presentation and its pathogens in heart, really attracts our attention. Cindy St. Hilaire: Do we know any or some of the potential causes? Why it would start, maybe in a different patient population, but also in the heart versus the lung? Do we know anything about that process? Kory Lavine: We know nothing about it. Sarcoid has no known etiology. There's been thoughts in the past that it may be driven by infection, the typical pathogens or autoimmune ideologies, but really, there's little data out there to support those possibilities. Right now, the field's wide open. The other challenge is we don't really have a good way to treat this disease, so a lot of the therapies available are things like steroids, which can have some effect on the disease but carry a lot of risk of complications. The other agents that we sometimes use to lower the doses of steroids, things like methotrexate and azathioprine, are only modestly effective. These are really the motivation for Chieh-Yu and myself to pursue this. We don't really know what causes the disease, and we don't really have very good treatments. We really wanted to take the first step, that's to study the real disease, and understand what are the pathologic cell types that are present within the granuloma, which is these aggregation of immune cells that Chieh-Yu was speaking about. Cindy St. Hilaire: What is actually happening at the beginning of this disease? These granulomas form, and then what is the pathological progression in the heart? What goes on there? Chieh-Yu Lin: This is actually another great question that I will say there's not much that has been discovered because, especially in human tissue, every time we have a sample, it's actually a kind of time point. We cannot do a longitudinal study. But in general speaking, very little is known about how it's initiated because it will need to accumulate to a certain disease burden for this to have a clinical symptom sign and be manifested, and then being clinically studied. We do know that in both heart and lung after treatment of progressions, it's usually in, a general speaking, going through a phase from a more proliferative means that it's creating more granulomas, more inflammatory cell aggregate, to a more fibrotic phase. Means that sometimes you actually see the granuloma start to disappear or dissipate, and then showing this kind of dense collagen and fibrosis. That has been commonly documented in both lung and heart sarcoidosis. The other things is that very difficult to study this disease that we do not have a great animal model, so we cannot use animal model to try to approximate or really study the disease pathogenesis. There are several animal models they try to use microbacteria or infectious agents, and these infectious agents can create morphologically similar granuloma, per se, but just like in human body. For instance, patients suffer from TB in their lung, biopsy will show this. But clinically, these are two very distinct disease entities, even though they look alike. Even in the heart, one of the conditions that we study in our paper is giant cell myocarditis, as the name implying having multinucleated giant cells granuloma. It looks really alike under microscopy for pathologists like me, but their clinical course in response to treatment is drastically different. This type of barriers and in the current limitations of our study tool makes, as Kory just said, this is really a wide open. We just know so little despite all the effort. Cindy St. Hilaire: Yeah. I'm guessing based on this granuloma information, to start with, the obvious question you went after is going after the immune cell populations that possibly contribute to sarcoidosis. To do this, because you have the human tissue, you went for single cell transcriptional profiling, which is a great use of the technology. But what biological sources did you use, and how did you go about choosing patient? Because the great thing about single cell is you can do just that, you can look at however many thousands of cells in one patient. But how do you make sure or check that that is broadly seen versus just a co-founding observation in that patient? Kory Lavine: We use explanted hearts and heart tissue from patients that underwent either heart transplantation or implementation of LVADs. It's a pretty big hunk of myocardium, and we're lucky to work with outstanding pathologists both at WashU, JU, as well as our collaborators at Duke. Between the two institutions, we're able to pull together a collection of tissues where we knew there were granulomas within that piece of tissue we analyzed. You bring up an important challenge. You need to make sure the disease and cause of the disease is present in the tissue that you're analyzing, otherwise you'll not come up with the data that really is informative. Chieh-Yu Lin: Kory beautifully answered the question, but I just wanted to add one little thing, and that's also why we use various different modalities. Some of them is more inside you, like the NanoString Technologies' spatial transcriptomic. You can visualize and confirm that we are studying the phenomenon that has been described for sarcoidosis, and then using multichannel immunofluorescence to validate our sequencing data, to complement such limitations of certain technology. Cindy St. Hilaire: Especially, I feel like with this diseased tissue that it's such a large tissue, there's so much information, it's really hard to dig in and figure out where the signal is. This was a wonderful paper for kind of highlighting, integrating all these new technologies with also just classical staining. Makes for great pictures as well. How does this cellular landscape of cardiac sarcoidosis compare to a normal heart? What'd you find? Chieh-Yu Lin: This is a great question. Compared to normal heart, we have been talking about this accumulation of macrophages with scattered multinucleated giant cells. For the similar landscape, first and foremost, you do not see those type of accumulations in brain microscopy or by myeloid markers in the heart. Although, indeed, in even normal heart tissue we have rest and macrophages. It just doesn't form such morphological alterations. But then we dive deep into it, and then we found that from a different cell type perspective, we realized that the granuloma is composed by several different type of inflammatory cells, with most of the T cells and NKT cells kind of adding periphery. The myeloid cells, including the multinucleated giant cells also, are kind of in the center of the granuloma of the sarcoidosis. Then, we further dive in and realize that there are at least six different subtype of myeloid cells that is contributing to the formation of this very eye-catching distinctive granular malformations, and to just never feel first off and foremost, of course, is those multinucleated giant cells that is really distinct, even on the line microscopy] routine change stand. And then we have a typical monocyte that's more like a precursor being recently recruited to the heart, and we finally sent the other four different type of myeloid cell that carry different markers, and then improving the resident macrophages. Especially for me as a pathologist, I'm using my eye and looking at stand every day, is actually these six type of cells, myeloid cells, actually form a very beautiful special kind of distribution with the connections or special arrangement with all different type, kind of like multinucleated giant cell in the middle, flanked by HLA-DR positive epithelioid macrophages, kind of scatter, and then with dendritic cells and a typical monocyte at the peripheral, and then resident macrophage kind of like in the mix of the seas of granuloma information. All these are distinct from normal heart tissues that does carry a certain amount of macrophages, but just don't form this orchestrated... /episode/index/show/circresearch/id/24726783

September 2022 Discover Circ Res 09/15/2022

September 2022 Discover Circ Res This month on Episode 40 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the September 2 and September 16 issues of the journal. This episode also features an interview with Dr Jun Yoshioka, and Dr Yoshinobu Nakayama, from the City University of New York, about their study, Interaction of ARRDC-4 with GLUT1 Mediates Metabolic Stress in the Ischemic Heart. Article highlights: Jin, et al. Mengozzi, et al. Hu, et al. Garcia-Gonzales, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh. And today I'm going to be highlighting some articles from September 2nd, and September 16th issues of CircRes. And I'm also going to have a conversation with Dr Jun Yoshioka, and Dr Yoshinobu Nakayama, from the City University of New York, about their study, Interaction of ARRDC-4 with GLUT1 Mediates Metabolic Stress in the Ischemic Heart. But, before I get to the interview, I'm going to highlight a few articles. The first article is from our September 2nd issue, and it's titled, Gut Dysbiosis Promotes Preeclampsia by Regulating Macrophages, and Trophoblasts. The first author is Jiajia Jin, and the corresponding author is Qunye Zhang from the Chinese National Health Commission. Preeclampsia is a late-stage pregnancy complication that can be fatal to the mother, and the baby. It's characterized by high blood pressure, and protein in the urine. The cause is unknown, but evidence suggests the involvement of inflammation, and impaired placental blood supply. Because gut dysbiosis can influence blood pressure, and inflammation has been observed in preeclamptic patients, Jin and colleagues examined this link more closely. They found that women with preeclampsia had altered gut microbiome. Specifically, a reduction in a species of bacteria that produced short-chain fatty acids, and lower short-chain fatty acid levels in their feces, in their serum, and in their placentas. And preeclamptic women had lower short-chain fatty acid levels in their feces, in their serum, and in their placentas compared with women without preeclampsia. They found that fecal transfers from the preeclampsia women to rats with a form of the condition exacerbated the animals' preeclampsia symptoms, while fecal transfers from control humans alleviated the symptoms. Furthermore, giving rats an oral dose of short-chain fatty acids or short-chain fatty acid producing bacteria decreased the animals' blood pressure, reduced placental inflammation, and improved placental function. This work suggests that short-chain fatty acids, and gut microbiomes could be a diagnostic marker for preeclampsia. And microbial manipulations may even alleviate the condition. The second article I want to share is also from our September 2nd issue, and it's titled, Targeting SIRT1 Rescues Age and Obesity-Induced Microvascular Dysfunction in Ex Vivo Human Vessels. And this study was led by Alessandro Mengozzi from University of Pisa. With age, the endothelial lining of blood vessels can lose its ability to control vasodilation, causing the vessel to narrow and reduce blood flow. This decline in endothelial function has been associated with age related decrease in the levels of the enzyme, SIRT1. And artificially elevating SIRT1 in old mice improves animals' endothelial function. Obesity, which accelerates endothelial dysfunction, is also linked to low SIRT1 levels. In light of these SIRT1 findings, Mengozzi, and colleagues examined whether increasing the enzyme's activity could improve the function of human blood vessels. The team collected subcutaneous microvessels from 27 young, and 28 old donors. And both age groups included obese, and non-obese individuals. SIRT1 levels in the tissue were, as expected, negatively correlated with age and obesity, and positively correlated with baseline endothelium dependent vasodilatory function. Importantly, incubating tissue samples from older, and obese individuals with a SIRT1 agonist, restored the vessel’s vasodilatory functions. This restoration involved a SIRT1 induced boost to mitochondrial function, suggesting that maintaining SIRT1 or its metabolic effect might be a strategy for preserving vascular health in aging, and in obesity. The third article I want to share is from our September 16th issue. And this one is titled, Differences in Metabolomic Profiles Between Black And White Women and Risk of Coronary Heart Disease. The first author is Jie Hu, and the corresponding author is Kathryn Rexrode, and they're from Brigham and Women's Hospital, and Harvard University. In the US, coronary heart disease, and coronary heart disease-related morbidity, and mortality is more prevalent among black women than white women. While racial differences in coronary heart disease risk factors, and socioeconomic status have been blamed, this group argues that these differences alone cannot fully explain the disparity. Metabolomic variation, independent of race, has been linked to coronary heart disease risk. Furthermore, because a person's metabolome is influenced by genetics, diet, lifestyle, environment and more, the authors say that it reflects accumulation of many cultural, and biological factors that may differ by race. This group posited that if racial metabolomic differences are found to exist, then they might partially account for differences in coronary heart disease risk. This study utilized plasma samples from nearly 2000 black women, and more than 4500 white women from several different cohorts. The team identified a racial difference metabolomic pattern, or RDMP, consisting of 52 metabolites that were significantly different between black, and white women. This RDMP was strongly linked to coronary heart disease risk, independent of race, and known coronary heart disease risk factors. Thus, in addition to socioeconomic factors, such as access to healthcare, this study shows that racial metabolomic differences may underlie the coronary heart disease risk disparity. The last article I want to share is also from our September 16th issue, and it is titled, ADAR1 Prevents Autoinflammatory Processes in The Heart Mediated by IRF7. The first author is Claudia Garcia-Gonzalez, and the corresponding author is Thomas Braun, and they are from Max Planck University. It's essential for a cell to distinguish their own RNA from the RNA of an invading virus to avoid triggering immune responses inappropriately. To that end, each cell makes modifications, and edits its own RNA to mark it as self. One type of edit made to certain RNAs is the conversion of adenosines to inosines. And this is carried out by adenosine deaminase acting on RNA1 or ADAR1 protein. Complete loss of this enzyme causes strong innate immune auto reactivity, and is lethal to mice before birth. Interestingly, the effects of ADAR1 loss in specific tissues is thought to vary. And the effect in heart cells in particular has not been examined. This study, which focused on the heart, discovered that mice lacking ADAR1 activity specifically in cardiomyocytes, exhibit autoinflammatory myocarditis that led to cardiomyopathy. However, the immune reaction was not as potent as in other cells lacking ADAR1. Cardiomyocytes did not exhibit the sort of upsurge in inflammatory cytokines, and apoptotic factors seen in other cells lacking ADAR1. And the animals themselves did not succumb to heart failure until 30 weeks of age. The author suggests that this milder reaction may ensure the heart resists apoptosis, and inflammatory damage because, unlike some other organs, it cannot readily replace cells. Cindy St. Hilaire: Today I have with me, Dr Jun Yoshioka, and Dr Yoshinobu Nakayama, and they're from City University of New York. And today we're going to talk about their paper, Interaction of ARRDC4 With GLUT1 Mediates Metabolic Stress in The Ischemic Heart. And this is in our September 2nd issue of Circulation Research. So, thank you both so much for joining me today. Jun Yoshioka: Thank you for having us. We are very excited to be here. Cindy St. Hilaire: It's a great publication, and also had some really great pictures in it. So, I'm really excited to discuss it. So, this paper really kind of focuses on ischemia, and the remodeling in the heart that happens after an ischemic event. And for anyone who's not familiar, ischemia is a condition where blood flow, and thus oxygen, is restricted to a particular part of the body. And in the heart, this restriction often occurs after myocardial infarctions, also called heart attacks. And so, cardiomyocytes, they require a lot of energy for contraction, and kind of their basic functions. And in response to this lack of oxygen, cardiomyocytes switch their energy production substrate. And so, I'm wondering if before we start talking about your paper, you can just talk about the metabolic switch that happens in a cardiac myocyte in the healthy state versus in the ischemic state. Jun Yoshioka: Sure. As you just said, that the heart never stops beating throughout the life. And it's one of the most energy demanding organs in the body. So, under normal conditions, cardiac ATP is mainly derived from fatty acid oxidation, and glucose metabolism contributes a little bit less in adult cardiomyocytes. However, under stress conditions such as ischemia, glucose uptake will become more critical when oxidative metabolism is interrupted by a lack of oxygen. That is because glycolysis is a primary anaerobic source of energy. We believe this metabolic adaptation is essential to preserve high energy phosphates and protect cardiomyocytes from lethal injuries. The concept of shifting the energy type of stress preference toward glucose, as you just said, has been actually long proposed as an effective therapy against MI. For example, GIK glucose insulin petition is classic. Now, let me explain how glucose uptake is regulated. Glucose uptake is facilitated by multiple isophones of glucose transporters in cardiomyocytes. Mainly group one and group four, and the minor, with a minor contribution of more recently characterized STLT1. In this study, we were particularly interested in group one because group one is a basal glucose transporter. Dr Ronglih Liao, and Dr Rong Tian's groups reported nearly two decades ago that the cardiac over-expression of group one prevents development of heart failure, and ischemic damage in mice. Since they are remarkable discoveries, the precise mechanism has not yet been investigated enough, at least to me. Especially how acute ischemic stress regulates group one function in cardiomyocytes. We felt that this mechanism is important because there is a potential to identify new strategies around group one, to reduce myocardiac ischemic damage. That is why we started this project hoping to review a new mechanism by which a protein family, called alpha-arrestins, controls cardiac metabolism under both normal, and diseased conditions. Cindy St. Hilaire: That is a perfect segue for my next question, actually, which is, you were focusing on this arrestin-fold protein, arrestin domain-containing protein four or ARRDC4. So, what is this family of proteins? What are arrestin-fold proteins? And before your study, what was known about a ARCCD4, and its relationship to metabolism, and I guess specifically cardiomyocyte metabolism? Jun Yoshioka: So, the arrestin mediated regulation of steroid signaling is actually common in cardiomyocytes. Especially beta, not the alpha, beta-arrestins have been well characterized as an adapter protein for beta-adrenergic receptors. Beta-arrestins combine to activate beta-adrenergic receptors on the plasma membrane, promote their endosomal recycling, and cause desensitization of beta-adrenergic signaling. Over the past decade, however, this family, the arrestin family, has been extended to include a new class of alpha-arrestins. But unlike beta-arrestins, the physiological functions of alpha-arrestins remain largely unclear based in mammalian cells. Humans, and mice have six members of alpha-arrestins including Txnip, thioredoxin interacting protein called Txnip, and five others named alpha domain-containing protein ARRDC1 2, 3, 4 and 5. Among them Txnip is the best studied alpha-arrestin. And Txnip is pretty much the only one shown to play a role in cardiac physiology. Txnip was initially thought to connect alternative stress and metabolism. However, it is now known that the Txnip serves as an adapter protein for the endocytosis of group one, and group four to mediate acute suppression of glucose influx to cells. In fact, our group has previously shown that the Txnip knockout mice have an enhanced glucose uptake into the peripheral tissues, as well as into the heart. Now, in this study, our leading player is ARRDC4. The arrestin-domains of ARRDC4 have 42% amino acid sequence similarities to Txnip. This means that the structurally speaking ARRDC4 is a brother to Txnip. So, usually the functions of arrestins are expected to be related to their conserved arrestin-domains. So, we were wondering whether two brothers, Txnip, and ARRDC4, may share the same ability to inhibit the glucose transport. That was a starting point where we initiated this project. Cindy St. Hilaire: That's great. And so, this link between ARRDC4, and the cardiac expression of gluten one and gluten four, I guess, mostly gluten one related to your paper, that really wasn't known. You went about this question kind of based on protein homology. Is that correct? Jun Yoshioka: That is right. Cindy St. Hilaire: And so, ARRDC4 can modulate glucose levels in the cell by binding, and if I understand it right, kind of helping that internalization process of glute one. Which makes sense. You know, when you have glucose come into the cell, you don't want too much. So, the kind of endogenous mechanism is to shut it off, and this ARRDC4 helps do that. But you also found that this adapter protein impacts cellular stress, and the cellular stress response. So, I was wondering if you could share a little bit more about that because I thought that was quite interesting. It's not just the metabolic impact of regulating glucose. There's also this cellular stress response. Jun Yoshioka: Right? So, Txnip is known to induce oxidative stress. But about the ARRDC4, we found that ARRDC4 actually does not induce oxidative stress. Instead, we found that it reproducibly causes ER, stress rather than oxidative stress. So, let Yoshinobu talk about the ER stress part. Yoshinobu, can you talk about how you found the ER stress story? Yoshinobu Nakayama: So, then let's talk about the, yeah, ER stress caused by ARRDC4. The ER stress caused by ARRDC4, year one was the biggest challenge in this study, because it's a little bit difficult to how we found a link of the glucose metabolism to the effect of the ARRDC4, only our stress. And at the other point of the project, we noticed that a ARRDC4 causes ER stress reproducibly, but we did not know how. So, both group one, and ARRDC4 are membrane proteins mainly localized near the plasma membrane. Then how does ARRDC4 regulate the biological process inside in the plasma radical? So, we then hypothesize that ARRDC4 induces intercellular glucose depravation by blocking cellular glucose uptake, and then interferes with protein glycosylation, thereby disturbing the ER apparatus. That makes sense because inhibition of group one trafficking by ARRDC4 was involved in the unfolded protein response in ischemic cardiomyocytes. Cindy St. Hilaire: So how difficult was that to figure out? How long did that take you? Yoshinobu Nakayama: How long? Yeah. Is this the question? Cindy St. Hilaire: It's always a hard question. ... /episode/index/show/circresearch/id/24377541

August 2022 Discover CircRes 08/18/2022

August 2022 Discover CircRes This month on Episode 39 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the August 5th and 19th issues of the journal. This episode also features an interview with Dr Annet Kirabo and Dr Ashley Pitzer from Vanderbilt University on their article, Dendritic Cell ENaC-Dependent Inflammasome Activation Contributes to Salt-Sensitive Hypertension. Article highlights: Jain, et al. Orlich et al: Xue et al: Wang et al: Cindy St. Hilaire: Hi, welcome to Discover CircRes, the podcast of the American Heart Association's journal Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to be highlighting articles from our August 5th and August 19th issues of Circulation Research. I'm also going to have a chat with Dr Annet Kirabo and Dr Ashley Pitzer from Vanderbilt University about their study, Dendritic Cell ENaC-Dependent Inflammasome Activation Contributes to Salt-Sensitive Hypertension. But before I get to the interview, I first want to share an article from our August 5th issue, and that article is titled, Unfolded Protein Response Differentially Modulates the Platelet Phenotype. The first author of this study is Kanika Jain and the corresponding author is John Hwa from Yale University. Self-stress can lead to protein misfolding, and the accumulation of misfolded proteins can lead to a reduction in protein translation and may alter gene transcription, a process collectively known as the unfolded protein response, or UPR. UPR is well documented in nucleated cells; however, it has not been studied in platelets, which are anuclear, but do have a rapid response to cellular stress. In this study, they investigated the UPR in anucleate platelets and explore its role, if any, in platelet physiology and function. They found that treating human and mouse platelets with various stressors caused aggregations of misfolded proteins and induction of UPR-specific factors. Oxidative stress, for example, induced the UPR kinase PERK, while an endoplasmic reticulum stressor induced the transcription of the UPR factor XBP1. The team went on to study the UPR in platelets from people with type II diabetes, which is a population in which platelet mediated thrombosis is a major complication. They showed that protein aggregation and upregulation of the XBP1 pathway in diabetic patient platelets correlated with disease severity. Furthermore, treating the diabetic patient platelets with a chemical chaperone that helps to correct protein misfolding reduced protein aggregations and prevented the cells prothrombotic activation. This work confirms that even without transcription, platelets display stress-induced UPR, and that targeting this response may be a way to reduce thrombotic risk in diabetic patients. Cindy St. Hilaire: The second article I want to share with you is from our August 5th issue and is titled, Mural Cell SRF Controls Pericyte Migration, Vessel Patterning and Blood Flow, and it was led by Michael Orlich from Uppsala University in Sweden. Blood vessels are lined with endothelial cells and surrounded by mural cells. Vascular smooth muscle cells are the mural cells in the case of veins and arteries, and pericytes are the mural cells in the case of capillaries. In the capillaries, pericytes maintain blood-brain and blood-retina barrier function and can mediate vascular tone, similar to smooth muscle cells. While these pericytes and smooth muscle cells are related, they have distinct roles and characteristics. To learn more about the similarities and the differences between pericytes and smooth muscle cells, this group examined how each would be affected by the absence of SRF in the other. SRF is a transcription factor, essential for nonvascular or visceral smooth muscle cell function. In visceral smooth muscle cells, SRF drives expression of smooth muscle actin and other smooth muscle genes. Using mice engineered to lack SRF in mural cells, they show that SRF drives smooth muscle gene expression in these pericytes and smooth muscle cells, and its loss from smooth muscle cells causes atrial venous malformations and diminishes vascular tone. In pericytes, loss of SRF impaired cell migration in angiogenic sprouting. In a mouse model of retinopathy, activation of SRF drove pathological growth of pericytes. This work not only highlights the various functions of SRF in mural cell biology, but it also suggests that it has a role in pathological capillary patterning. Cindy St. Hilaire: The third article I want to share is from our August 19th issue of Circulation Research and is titled, Gut Microbially Produced Indole-3-Propionic Acid Inhibits Atherosclerosis by Promoting Reverse Cholesterol Transport and its Deficiency Is Causally Related to Atherosclerotic Cardiovascular Disease. The first authors are Hongliang Xue and Xu Chen, and the corresponding author is Wenhua Ling from Sun Yat-Sen University in Guangzhou, China. Recent studies provide evidence that disorders in the gut microbiota and gut microbiome derived metabolites affect the development of atherosclerosis. However, which and how specific gut microbial metabolites contribute to the progression of atherosclerosis and the clinical relevance of these alterations remain unclear. Gut microbiome derived metabolites, such as short-chain fatty acids and trimethylamine N-oxide, or TMAO, have been found to correlate with atherosclerotic disease severity. This study has now found that serum levels of indole-3-propionic acid, or IPA, are lower in atherosclerosis patients than controls. The team performed unbiased metagenomic and metabolomic analyses on fecal and serum samples from 30 coronary artery disease patients and found that, compared with controls, patients with atherosclerosis had lower gut bacterial diversity, depletion of species that commonly produce IPA and lower levels of IPA in their blood. Examination of a second larger cohort of atherosclerosis patients confirmed this IPA disease correlation. The team also showed serum IPA was reduced in a mouse model of atherosclerosis, and that supplementing such mice with dietary IPA could slow disease progression. Analysis of the macrophages from these mice showed that IPA increased cholesterol efflux, and the team went on to elucidate the molecular steps involved. The results of this study not only unraveled the details of IPA's influence on atherosclerosis, but suggest boosting levels of this metabolite could slow atherosclerotic disease progression. Cindy St. Hilaire: The last article I want to share is also from our August 19th issue, and it's titled, Endothelial Loss of ETS1 Impairs Coronary Vascular Development and Leads to Ventricular Non-Compaction. The first author is Lu Wang and the corresponding author is Paul Grossfeld, and they are at UCSD. Congenital heart defects, or CHDs, are present in nearly 1% of the human population. In some cases, the heart defects result from a genetic error, which can give researchers clues to its etiology. Jacobson syndrome is a complex condition caused by deletions from one end of chromosome 11, and the occurrence of a congenital heart defect in this syndrome has been associated with the loss of the gene ETS1. ETS1 is an angiogenesis promoting transcription factor, but how ETS1 functions in heart development was not known. Wang and colleagues now show that both global or endothelial-specific loss of ETS1 in mice caused differences in embryonic heart development that ultimately led to a muscular wall defect known as ventricular non-compaction. The mice also had defective coronary vasculogenesis associated with decreased abundance of endothelial cells in the ventricular myocardium. RNA sequencing of ventricular tissue revealed that, compared with controls, mice lacking ETS1 had reduced expression of several important angiogenesis genes and upregulation of extracellular matrix factors, which together contributed to the muscular and vascular defects. Cindy St. Hilaire: Today I have with me, Dr Annet Kirabo and Dr Ashley Pitzer, both from Vanderbilt University, and we're going to talk about their paper, Dendritic Cell ENaC-Dependent Inflammasome Activation Contributes to Salt-Sensitive Hypertension. This article is in our August 5th issue of Circulation Research. Thank you both so much for joining me today. Annet Kirabo: Yeah, thank you so much for having us. Ashley Pitzer: Yeah, thank you for having us. Cindy St. Hilaire: Yeah, it's a great paper. I think we're all familiar with hypertension and this idea that too much salt is bad for our cardiovascular system. When I was a kid, my grandparents had those salt replacements on their kitchen table, Mrs. Dash and whatever. But, like you said in the start of your paper, the exact mechanism by which salt intake increases blood pressure and also increases cardiovascular risk, it's not really well understood, and you guys are focusing on the contribution of immune responses in this process or in this pathogenesis. Before we dig into the details of your paper, I was wondering if you could give us a little bit of background about what's known regarding the role of inflammation in this salt-sensitive hypertension pathogenesis. Annet Kirabo: Yeah. It's difficult to know where begin to from, but the role of inflammation in cardiovascular disease have been known for many, many decades. Right now, Dr David Harrison showed more than 10 years ago that T cells contribute to hypertension, but the mechanisms were not known. Back when I was a post doc in David Harrison's lab, we discovered a new mechanism, how immune cells are activated in inflammation and hypertension, whereby we found that there is increased oxidative stress in antigen-presenting cells. This leads to formation of oxidative products known as arachidonic acid or lipid products known as isolevuglandin, or IsoLGs. These IsoLGs are highly, highly reactive and they adapt to lysines on proteins. This is a covalent binding, which leads to permanent alteration of proteins, and so these proteins act as neoantigens that are presented as self-antigens to T cells, leading to an autoimmune-like state in hypertension. Annet Kirabo: We found that these antigen-presenting cells are activated and they start producing a lot of cytokines that paralyze T cells to IL-17 producing T cells that contribute to hypertension. And so, when I started my lab back in 2016, we discovered that excess dietary salt profoundly activates this pathway, and we found for the first time that these antigen-presenting cells, they express ENaC, the epithelial sodium channel, and sodium goes into these antigen-presenting cells and activates the NADPH oxidase, which is an enzyme which produces this reactive oxygen species, leading to this IsoLG formation, which I've talked about, and leading to inflammation. So, three years ago when Ashley joined my lab, she had extensively studied the inflammasome in her PhD program, and she suggested why don't we look at the role of the inflammasome in this pathway and how IsoLG may contribute to this. In her paper that we are discussing right now, she found that in a dependent manner, sodium enters the cell and activates this pathway, and the NLRP3 inflammasome is involved in this process. Cindy St. Hilaire: That's such a wonderful story that fits together so many pieces. One of the things you talk about, which I guess I didn't even appreciate myself is, there are certain individuals out there who are more salt-sensitive than others. Annet Kirabo: Yeah. Cindy St. Hilaire: What is that difference? Do we know the root cause of that? And then also, how many individuals are we talking about are salt-sensitive? Annet Kirabo: Salt-sensitive blood pressure, it is a variable trait and it's normally distributed in the population, but it happens more in some individuals than others. It happens even in 25% of people without any hypertension. These people go to that doctor, that doctor thinks they're normal, they don't have any hypertension, but these people can be at a risk of sudden heart attack or cardiovascular risk or even a stroke, simply because when they eat a salty meal, their blood pressure will go up. Cindy St. Hilaire: Yeah, that's one of my questions. How much salt are we talking about here? And not only how much in a meal, but a sustained amount? How bad is a miso soup a day? Annet Kirabo: Yes. The American Heart Association and the World Health Organization have recommendations. American Heart Association recommends one spoon per day. We have refused to adapt to this recommendation, but that is the recommendation that they have recommended per day to eat. But this is difficult because most of the salt, as you know, is already in our food through processing in our processed foods and we don't have any control over how much salt we have, and there's also a lot of adding of salt at a table. Cindy St. Hilaire: Ashley, your background was more the inflammasome. What were your thoughts entering into this project? Did you have much of a hypertension background? Ashley Pitzer: No. My graduate thesis focused mainly on endothelial dysfunction and cardiovascular disease, and so it was a pretty easy segue. But it was just with Annet, so excited about the project and showing me all the data and this robust IL-1 beta production that she was seeing after these immune cells being exposed to high salt, I, with my inflammasome background, was immediately like, this could be playing a role. And so it was, like I said, a pretty easy transition and, as is in the paper, we're doing human studies. All of my research back in grad school was very basic research, so it was very exciting to see how our research was being translated with people having this condition and potentially finding mechanisms where we can target this to help actual people. Cindy St. Hilaire: I think a lot of us who are not in the hypertension field, and maybe this was you before you joined Annet's lab, we really only kind of think of the kidneys and the blood vessels when we think about hypertension, but studies like this are changing that. And I think a lot of Annet's earlier work, as well as the work of others, have shown a role for this epithelial sodium channel as an important player in this salt-induced hypertension. New to me, it's not just found in the kidney, which I totally did not appreciate that. And it's this channel sensing the salt that can trigger this IL-1 beta production that does a whole bunch of other things. Cindy St. Hilaire: What are those other things? What are those cells that are affected and where is this happening? Obviously it's not just kidney cells, but is it only in the kidney or are these systemic cells? What do we think is happening? Ashley Pitzer: That's the question, is, where is this happening? There's been studies at Vanderbilt by Jens Titze and his lab showing, where are these immune cells sensing the salt? And so they've shown that sodium accumulates in the skin, a huge argument is for they're sensing the sodium in the kidney because that's where a lot of it is being processed. But these immune cells travel through the whole body, so they're seeing it where there are the highest amounts of sodium concentration, and so I would argue it's in the kidney. Annet Kirabo: Indeed, because we're now collaborating with Tina Kon, and we have recently published with her a paper in the International Journal of Science, where we have done sodium MRI and we find this accumulation of sodium in the kidney even much more than in the skin. And we know that the kidney is where sodium is highly concentrated. So the working hypothesis in the lab is that these immune cells can be activated wherever they are, in the lymph nodes or not, in other tissues, but they can travel to the kidney. We find that in high salt, if you feed high salt to the mouse, the endothelium in the kidney becomes dysfunctional and it expresses molecules, chemoattractants, that attract these immune cells in the kidney. We think that the high salt accumulation in the kidney can activate these, and then these immune cells are activated and they produce cytokines. Dr Steve Crowley showed that they can produce IL-1 beta, which induces activation of sodium channels that can be induced. We have also actually found that even IL-17 can be produced by these immune cells in the kidney and they can activate sodium channels in the kidney, leading retention of sodium and water and hypertension. Cindy St. Hilaire: Very cool. You used a lot of mice in this paper. Can you tell us, I just want to know a little bit about the models you chose to use, but also how similar is hypertension in mouse and humans? Obviously for atherosclerosis, we have to do lots of things to get them to form a plaque. Is hypertension similar in a mouse and do mice also show this salt-sensitive phenotype? Annet Kirabo: That is an extremely important point. If you read our paper, we use a slightly different approach. Most people do benchside to bed approach. We did the opposite. We did a bed to benchside approach. Cindy St. Hilaire: Always smart. Annet Kirabo: Yeah. We first started humans, and then with some references, we went to the mice, because I think when it comes to salt-sensitive blood pressure, mice are different from humans. In fact, if we look in the lab, we find that female mice are protected from salt-sensitive blood pressure, but we find that in the humans, it's the opposite. Females are more prone to salt-sensitive hypertension. Those are studies that we are doing right now. We haven't published. But we know that it can be different. The model we use most of the time in the lab, the C57 mice, are resistant to salt-sensitive hypertension. These C57 mice would rather die before they raise their blood pressure in response to salt. We can induce salt-sensitivity in these mice like in the paper that we are discussing. When we induce the endothelial dysfunction using L-NAME and we wash it out, then these mice, when you give them, subsequently, salt, suggests that they become salt-sensitive. But we also have a salt-sensitive mouse model that we use, the 129/SV mouse. So we use several models to kind of prove the same thing over and over again with the findings... /episode/index/show/circresearch/id/24074952

July 2022 Discover Circ Res 07/21/2022

July 2022 Discover Circ Res This month on Episode 38 of Discover CircRes, host Cynthia St. Hilaire highlights original research articles featured in the Jue 24th, July 8th and July 22nd issues of the journal. This episode also features an interview with the 2022 BCBS Outstanding Early Career Investigator Award finalists, Dr Hisayuki Hashimoto, Dr Matthew DeBerge and Dr Anja Karlstadt. Article highlights: Nguyen, et al. . Choi, et al. Kamtchum-Tatuene, et al. Li, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh. And today I'm going to be highlighting articles from our June 24th, July 8th and July 22nd issues of Circulation Research. I'm also going to have a chat with the finalists for the 2022 BCBS Outstanding Early Career Investigator Award, Dr Hisayuki Hashimoto, Dr Matthew DeBerge and Dr Anja Karlstadt. Cindy St. Hilaire: The first article I want to share is from our June 24th issue and is titled, miR-223 Exerts Translational Control of Proatherogenic Genes in Macrophages. The first authors are My-Anh Nguyen and Huy-Dung Hoang, and the corresponding author is Katey Rayner and they're from the University of Ottawa. A combination of cholesterol accumulation in the blood vessels and subsequent chronic inflammation that's derived from this accumulation drive the progression of atherosclerosis. Unfortunately, current standard medications tackle just one of these factors, the cholesterol. And this might explain why many patients on such drugs still have vascular plaques. In considering treatments that work on both aspects of the disease, meaning lipid accumulation and inflammation, this group investigated the micro RNA 223 or miR-223, which is a small regulatory RNA that has been shown to suppress expression of genes involved in both cholesterol uptake and inflammatory pathways in both liver and immune cells. Cindy St. Hilaire: The team showed that mouse macrophages deficient in miR-223, exhibited increased expression of pro-inflammatory cytokines and reduced cholesterol efflux compared with control cells. Overexpression of miR-223 had the opposite effects. Furthermore, atherosclerosis prone mice, whose hematopoietic cells lacked miR-223, had worse atherosclerosis with larger plaques and higher levels of pro-inflammatory cytokines than to control animals with normal levels of miR-223. These findings highlight miR-223's dual prompt, antiatherogenic action, which could be leveraged for future therapies. Cindy St. Hilaire: The second article I want to share is from our July 8th issue of Circulation Research and is titled, Piezo1-Regulated Mechanotransduction Controls Flow-Activated Lymph Expansion. The first author is Dongwon Choi and the corresponding author is Young-Kwon Hong, and they're from UCLA. As well as being super highways for immune cells, lymph vessels are drainage channels that help maintain fluid homeostasis in the tissues. This network of branching tubes grows as fluids begin to flow in the developing embryo. This fluid flow induces calcium influx into the lymphatic endothelial cells, which in turn promotes proliferation and migration of these cells, leading to the sprouting of lymph tubules. But how do LECs, the lymphatic endothelial cells, detect fluid flow in the first place? Piezo1 is a flow and mechanosensing protein known for its role in blood vessel development and certain mutations in Piezo1 cause abnormal lymphatic growth in humans. Cindy St. Hilaire: This script found that Piezo1 is expressed in the embryonic mouse LECs and that the suppression of Piezo1 inhibits both flow activated calcium entry via the channel ORAI1, as well as downstream target gene activation. Overexpression of Piezo1, by contrast, induced the target genes. The team went on to show that mice lacking either Piezo1 or ORAI1 had lymphatic sprouting defects and that pharmacological activation of Piezo1 in mice enhanced lymphogenesis and prevented edema after tail surgery. Together, the results confirmed Piezo1's role in flow dependent lymphatic growth and suggest it might be a target for treating lymphedema. Cindy St. Hilaire: The third article I want to share is also from our July 8th issue and is titled, Interleukin-6 Predicts Carotid Plaque Severity, Vulnerability and Progression. The first and corresponding author of this study is Joseph Kamtchum-Tatuene from University of Alberta. Excessive plasma cholesterol and systemic inflammation are contributing factors in atherosclerosis. While traditional remedies have been aimed at lowering patient's lipid levels, drugs that tackle inflammation are now under investigation, including those that suppress Interleukin-6, which is an inflammatory cytokine implicated in the disease. Focusing on carotid artery disease, this group conducted a prospective study to determine whether IL-6 levels correlated with disease severity. 4,334 individuals were enrolled in the cardiovascular health study cohort. They had their blood drawn and ultrasounds taken at the start of the study and five years later. This group found IL-6 was robustly correlated with and predicted plaque severity independent of other cardiovascular risk factors. This study also determined that an IL-6 blood plasma level of 2.0 picograms/mls, identified individuals with the highest likelihood of plaque, vulnerability and progression. This threshold value could be used to select patients who might benefit from novel IL-6 lowering medications. Cindy St. Hilaire: The last article I want to share is from our July 22nd issue of Circulation Research and is titled, Mitochondrial H2S Regulates BCAA Catabolism in Heart Failure. The first author is Zhen Li, and the corresponding author is David Lefer from Louisiana State University. Hydrogen sulfide, or H2S, is a compound that exerts mitochondrial specific actions that include the preservation of oxidative phosphorylation, mitochondrial biogenesis and ATP synthesis, as well as inhibiting cell death. 3-mercaptopyruvate sulfurtransferase, or 3-MST, is a mitochondrial H2S producing enzyme, whose functions in cardiovascular disease are not fully understood. Cindy St. Hilaire: This group investigated the global effects of 3-MST deficiency in the setting of pressure overload induced heart failure. They found that 3-MST was significantly reduced in the myocardium of patients with heart failure, compared with non failing controls. 3-MST knockout mice exhibited increased accumulation of branch chain amino acids in the myocardium, which was associated with reduced myocardial respiration and ATP synthesis, exacerbated cardiac and vascular dysfunction, and worsened exercise performance, following transverse aortic constriction. Restoring myocardial branched-chain amino acid catabolism, or administration of a potent H2S donor, ameliorated the detrimental effects of 3-MST deficiency and heart failure with reduced injection fraction. These data suggest that 3-MST derived mitochondrial H2S, may play a regulatory role in branch chain amino acid catabolism, and mediate critical cardiovascular protection in heart failure. Cindy St. Hilaire: Today, I'm really excited to have our guests, who are the finalists for the BCVS Outstanding Early Career Investigator Awards. Welcome everyone. Hisayuki Hashimoto: Thank you. Anja Karlstaedt: Hi. Hisayuki Hashimoto: Hi. Matthew DeBerge: Hello. Thank you. Cindy St. Hilaire: So the finalists who are with me today are Dr Hisayuki Hashimoto from Keio University School of Medicine in Tokyo, Japan, Dr Matthew Deberge from Northwestern University in Chicago and Dr Anja Karlstaedt from Cedar Sinai Medical Center in LA. Thank you again. Congratulations. And I'm really excited to talk about your science. Hisayuki Hashimoto: Thank you. Yes. Thanks, first of all for this opportunity to join this really exciting group and to talk about myself and ourselves. I am Hisayuki Hashimoto, I'm from Tokyo, Japan. I actually learned my English... I went to an American school in a country called Zaire in Africa and also Paris, France because my father was a diplomat and I learned English there. After coming back to Japan, I went to medical school. During my first year of rotation, I was really interested in cardiology, so I decided to take a specialized course for cardiology. Then I got interested in basic science, so I took a PhD course, and that's what brought me to this cardiology cardiovascular research field. Matthew DeBerge: So I'm currently a research assistant professor at Northwestern University. I'm actually from the Chicagoland area, so I'm really excited to welcome you all to my hometown for the BCVS meeting. Cindy St. Hilaire: Oh, that's right. And AHA is also there too this year. So you'll see a lot of everybody. Matthew DeBerge: I guess I get the home field advantage, so to speak. So, I grew up here, I did my undergrad here, and then went out in the east coast, Dartmouth College in New Hampshire for my PhD training. And actually, I was a viral immunologist by training, so I did T cells. When I was looking for a postdoctoral position, I was looking for a little bit of something different and came across Dr Edward Thorpe's lab at Northwestern university, where the interest and the focus is macrophages in tissue repair after MI. So, got into the macrophages in the heart and have really enjoyed the studies here and have arisen as a research assistant professor now within the Thorpe lab. Now we're looking to transition my own independent trajectory. Kind of now looking beyond just the heart and focusing how cardiovascular disease affects other organs, including the brain. That's kind of where I'm starting to go now. Next is looking at the cardiovascular crosstalk with brain and how this influences neuroinflammation. Anja Karlstaedt: I am like Hisayuki, I'm also a medical doctor. I did my medical training and my PhD in Berlin at the Charité University Medicine in Berlin, which is a medical faculty from Humboldt University and Freie University. II got really interested in mathematical modeling of complex biological systems. And so I started doing my PhD around cardiac metabolism and that was a purely core and computationally based PhD. And while I was doing this, I got really hooked into metabolism. I wanted to do my own experiments to further advance the model, but also to study more in crosstalk cardiac metabolism. I joined Dr Heinrich Taegteyer lab at the University of Texas in the Texas Medical Center, and stayed there for a couple of years. And while I was discovering some of the very first interactions between leukemia cells and the heart, I decided I cannot stop. I cannot go back just after a year. I need to continue this project and need to get funding. And so after an AHA fellowship and NIHK99, I am now here at Cedars Sinai, an assistant professor in cardiology and also with a cross appointment at the cancer center and basically living the dream of doing translational research and working in cardio-oncology. Cindy St. Hilaire: Great. So, Dr Hashimoto, the title of your submission is, Cardiac Reprogramming Inducer ZNF281 is Indispensable for Heart Development by Interacting with Key Cardiac Transcriptional Factors. This is obviously focused on reprogramming, but why do we care about cardiac reprogramming and what exactly did you find about this inducer ZNF281? Hisayuki Hashimoto: Thank you for the question. So, I mean, as I said, I'm a cardiologist and I was always interested in working heart regeneration. At first, I was working with pluripotent stem cells derived cardiomyocyte, but then I changed my field during my postdoc into directly programming by making cardiomyocyte-like cells from fiberblast. But after working in that field, I kind of found that it was a very interesting field that we do artificially make a cardiomyocyte-like cell. But when I dissected the enhanced landscape, epigenetic analysis showed that there are very strong commonalities between cardiac reprogramming and heart development. So I thought that, hey, maybe we can use this as a tool to discover new networks of heart development. And the strength is that cardiac reprogramming in vitro assay hardly opens in vivo assay, so it's really time consuming. But using dark programming, we can save a lot of time and money to study the cardiac transitional networks. And we found this DNF281 from an unbiased screen, out of 1000 human open reading frames. And we found that this gene was a very strong cardiac reprogramming inducer, but there was no study reporting about any functioning heart development. We decided to study this gene in heart development, and we found out that it is an essential gene in heart development and we were kind of able to discover a new network in heart development. Cindy St. Hilaire: And you actually used, I think it was three different CRE drivers? Was that correct to study? Hisayuki Hashimoto: Ah, yes. Yeah. Cindy St. Hilaire: How did you pick those different drivers and what, I guess, cell population or progenitor cell population did those drivers target? Hisayuki Hashimoto: So I decided to use a mesodermal Cre-driver, which is a Mesp1Cre and a cardiac precursor Cre-driver, which is the Nkx2-5 Cre and the cardiomyocyte Cre, which is the Myh6-Cre. So three differentiation stages during heart development, and we found out that actually, DNF281 is an essential factor during mesodermal to cardiac precursor differentiation state. We're still trying to dig into the molecular mechanism, but at that stage, if the DNF281 is not there, we are not able to make up the heart. Cindy St. Hilaire: That is so interesting. Did you look at any of the strains that survived anyway? Did you look at any phenotypes that might present in adulthood? Is there anything where the various strains might have survived, but then there's a kind of longer-term disease implicating phenotype that's observed. Hisayuki Hashimoto: Well, thank you for the question. Actually, the mesodermal Cre-driver knocking out the DNF281 in that stage is embryonic lethal, and it does make different congenital heart disease. And they cannot survive until after embryonic day 14.5. The later stage Nkx2-5 Cre and Myh6-Cre, interestingly, they do survive after birth. And then in adult stage, I did also look into the tissues, but the heart is functioning normally. I haven't stressed them, but they develop and they're alive after one year. It looks like there's really no like phenotype at like the homeostatic status. Cindy St. Hilaire: Interesting. So it's kind of like, once they get over that developmental hump, they're okay. Hisayuki Hashimoto: Exactly. That might also give us an answer. What kind of network is important for cardiac reprogramming? Cindy St. Hilaire: So what are you going to do next? Hisayuki Hashimoto: Thank you. I'm actually trying to dig into the transitional network of what kind of cardiac transitional network the ZNF281 is interacting with, so that maybe I can find a new answer to any etiology of congenital heart disease, because even from a single gene, different mutation, different variants arise different phenotypes in congenital heart disease. Maybe if I find a new interaction with any key cardiac transitional factors, maybe I could find a new etiology of congenital heart disease phenotype. Cindy St. Hilaire: That would be wonderful. Well, best of luck with that. Congratulations on an excellent study. Hisayuki Hashimoto: Thank you. Cindy St. Hilaire: Dr DeBerge, your study was titled, Unbiased Discovery of Allograft Inflammatory Factor-1 as a New and Critical Immuno Metabolic Regulatory Node During Cardiac Injury. Congrats on this very cool study. You were really kind of focused on macrophages in myocardial infarction. And macrophages, they're a Jeckel Hyde kind of cell, right? They're good. They're bad. They can be both, almost at the same time, sometimes it seems like. So why were you interested in macrophages particularly in myocardial infarction, and what did you discover about this allograft inflammatory factor-1, or AIF1 protein? Matthew DeBerge: Thank you. That's the great question. You really kind of alluded to why we're interested in macrophages in the heart after tissue repair. I mean, they really are the central mediators at both pro-inflammatory and anti-inflammatory responses after myocardial infarction. Decades of research before this have shown that inflammation has increased acutely after MI and has also increased in heart failure patients, which really has led to the development of clinical efforts to target inflammatory mediators after MI. Now, unfortunately, the results to target inflammation after MI, thus far, have been modest or disappointing, I guess, at worst, in the respect that broadly targeting macrophage function, again, hasn't achieved results. Again, because these cells have both pro and anti-inflammatory functions and targeting specific mediators has been somewhat effective, but really hasn't achieved the results we want to see. Matthew DeBerge: I think what we've learned is that the key, I guess, the targeting macrophage after MI, is really to target their specific function. And this led us to sort of pursue novel proteins that are mediating macrophage factor function after MI. To accomplish this, we similarly performed an unbiased screen collecting peri-infarct tissue from a patient that was undergoing heart transplantation for end stage heart failure and had suffered an MI years previously. And this led to the discovery of allograft inflammatory factor-1, or AIF1, specifically within cardiac macrophages compared to other cardiac cell clusters from our specimen. And following up with this with post-mortem specimens after acute MI to show that AIF1 was specifically increased in macrophages after MI and then subsequently then testing causality with both murine model of permanent inclusion MI, as well as in vitro studies using bone marrow drive macrophages to dig deeper mechanistically, we found that AIF1 was crucial in regulating inflammatory programing macrophages, which ultimately culminated in worse in cardiac repair after MI. Cindy St. Hilaire: That's really interesting. And I love how you start with the human and then figure out what the heck it's doing in the human. And one of the things you ended up doing in the mouse... /episode/index/show/circresearch/id/23792120

June 2022 Discover Circ Res 06/16/2022

June 2022 Discover Circ Res This month on Episode 37 of Discover CircRes, host Cynthia St. Hilaire highlights two original research articles featured in the May 27th issue of the journal and also provides an overview of the Compendium on Basic Models of Cardiovascular Disease featured in the June 10 issue of Circulation Research. This episode also features an interview between Dr Nikki Purcell, Circulation Research Social Media Editor and Associate Professor at Huntington Medical Research Institute and Dr Mark Feinberg, Dr Rulin Zhuang, and Dr Jingshu Chen from Brigham and Women's Hospital in Harvard Medical School to discuss their study, Perivascular Fibrosis Is Mediated by a KLF10-IL-9 Signaling Access in CD4+ T-Cells. Article highlights: Liang, et al. Jin, et al. Rosenzweig, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire from the. Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to be highlighting articles from our May 27th and June 10th issues of Circulation Research. Dr Nikki Purcell, an Associate Professor from the Huntington Medical Research Institute and my colleague on the CircRes Editorial Board, is going to interview Dr Mark Feinberg, Dr Rulin Zhuang and Dr Jingshu Chen from Brigham and Women's Hospital in Harvard Medical School and they're going to discuss their study, Perivascular Fibrosis Is Mediated by a KLF10-IL-9 Signaling Access in CD4+ T-Cells. Cindy St. Hilaire: The first article I'm going to highlight is titled Tenascin-X Mediates Flow Induced Suppression of EndMT and Atherosclerosis. The first author is Guozheng Liang and the corresponding author is Stefan Offermanns and they're from the Max Planck Institute. Atherosclerotic plaques in arteries arise when blood flow is reduced or turbulent. These are commonly regions where the vessels are curved or branched. Disturbed flow in these regions can prompt the local endothelial cells to undergo a process called e-to-mesenchymal transition or EndMT, which in turn contributes to atherosclerotic plaque formation. Exactly why turbulent, but not laminar flow prompts EndMT is not known. Using in vitro and in vivo experiments, this group discovered a critical EndMT suppressor protein expressed at high levels in endothelial cells exposed to lamina flow, but not exposed to turbulent flow. Mice that lack the protein, which is called Tenascin-X or TN-X, exhibited signs of EndMT and inflammation throughout their aorta and they were more prone to atherosclerosis. TN-X binds and blocks the function of the cytokine TGF beta, which is a potent driver of EndMT. Inhibiting the activity of TGF beta, whether with an anti TGF beta antibody or by deletion of its receptors, prevented the EndMT promoting effects of TN-X loss. Together, the results suggest that bolstering or mimicking the effects of TN-X may be a novel strategy for preventing atherosclerosis progression. Cindy St. Hilaire: The second article I want to share is titled, Genetic Lineage Tracing of Pericardial Cavity Macrophages in the Injured Heart. The first author is Hengwei Jin and the corresponding author is Bin Zhou and they're from the Chinese Academy of Science. If the heart suffers an infarction, monocytes and macrophages travel to the injury site via the bloodstream and locally from within the heart itself. A recent Immunity paper claims that macrophages in the surrounding pericardial cavity also can infiltrate the heart to aid in its repair. New work from Jin and colleagues, however, does not support these findings. The discrepancies seem in part to be related to the way that pericardial cavity macrophages were tracked. In the Immunity study, pericardial cavity macrophages were tracked by labeling with fluorescent beads or transplantation of trackable pericardial cavity macrophages into the recipient mice. Both of these strategies showed the cells entering the myocardium after infarction. Cindy St. Hilaire: However, in the Circ Research study, mice were engineered to have trackable endogenous pericardial cavity macrophages. Using these animals, the team found that while pericardial cavity macrophages did migrate to the surface of the heart, they did not significantly penetrate the tissue. Further discrepancies between the studies were apparent in loss of function experiments. Where the initial study found pericardial cavity macrophage loss led to increased myocardial fibrosis and left ventricle stiffness, the new study did not. Because myocardial infiltration of pericardial cavity macrophages represents a paradigm shift in heart injury research, the authors say its existence requires rigorous testing and for now at least, it remains debatable. Cindy St. Hilaire: The June 10th issue of Circ Research is our Compendium on Basic ModelsoOf Cardiovascular Diseases. The articles in this compendium are Illuminating the Mechanisms Underlying Sex Differences in Cardiovascular Disease by Carrie Weiss and Karen Rue, Animal Models to Study Cardiac Arrhythmias by Daniel Blackwell and Bjorn Knollmann, Animal Models of Exercise from Rodents to Pythons by Margaret Hastings, Anthony Rosenzweig and colleagues, Animal Models of Atherosclerosis Supportive Notes and Tricks of the Trade by Anton Gastera and Goran Hanson and colleagues, Heart Failure with Preserved Ejection Fraction, Heterogeneous Syndrome, Diverse Preclinical Models by Jason Roh and colleagues, Large and Small Animals of Heart Failure with Reduced Ejection Fraction by Patrick Pilz, Ronglih Liao and colleagues, CRISPR Modeling and Correction of Cardiovascular Disease by Ning Liu and Eric Olson, Animal Models of Cardiovascular Complications of Pregnancy by Zoltan Arany, Denise Hilfiker-Kleiner and S Ananth Karumanchi, Animal Models of Dysregulated Cardiac Metabolism by Heiko Bugger, Nicole Burn and Dale Abel, Biomedical Imaging and Experimental Models of Cardiovascular Disease by Marielle Scherrer-Crosbie and David Sosnovik, Zebrafish Models of Cardiac Disease from Fortuitous Mutants to Precision Medicine by Juan Gonzalez-Rosa and Cellular and Engineered Organoid Cardiovascular Models by Dilip Thomas and Joe Wu and colleagues. Nikki Purcell: Hi, I'm Dr Nicole Purcell, Associate Professor in the Cardiovascular Division at Huntington Medical Research Institute and today Dr Mark Feinberg, Dr Rulin Zhuang and Dr Jingshu Chen from Brigham and Women's Hospital in Harvard Medical School are with me to discuss their study, Perivascular Fibrosis Is Mediated by a KLF10-IL-9 Signaling Access in CD4 T-Cells in our May 27th issue of Circulation Research. Thank you for joining me today. Mark Feinberg: Thanks for having us. We're glad to be here. Rulin Zhuang: Thank you. Nikki Purcell: There were a lot of authors involved in this study, and while all could not join us today, I appreciate you taking the time to discuss your findings. So, your paper is dealing with vascular disease, often associated with elevated blood pressure or hypertension. A hallmark of advanced vascular diseases fibrosis is in the heart. When we talk about fibrosis, most investigators would think of interstitial fibrosis, but your paper focuses on perivascular. So Dr Feinberg, what is perivascular fibrosis and what led you to focus in hypertension? Mark Feinberg: Thanks, it's a great question. So perivascular fibrosis is characterized by an increased accumulation of connective tissue around blood vessels. There are many cell types that contribute to this process. Fibroblasts, obviously, that produce a lot of extracellular matrix and a wide range of collagens, but other cell types, muscle cells, which are sensitive to humoral factors, Ang-2, endothelial and other cytokines and growth factors, and more recently getting more attention, our immune cells, including infiltrated T-cells, which are important mediators of crosstalk between fibroblasts and extra matrix that actively modulate this fibrotic response. Clinically, perivascular fibrosis is a hallmark of several age related conditions that we see in our patients, hypertension, diabetes, chronic kidney disease, really all are involved with extensive extracellular remodeling. Many of our patients with elderly patients with hypertension have left ventricular hypertrophy, stiff heart and pure diastolic dysfunction, as well as arterial stiffness, which can contribute to a range of diseases from heart failure, MI, stroke and organ damage and including kidney disease. Mark Feinberg: So we actually started off wondering if there are any key transcription factors that may be involved in CD-4 T cell effector functions, given potential role of CD-4 T cells in this hypertensive response, and that perhaps may underlie the development of blood pressure and organ injury. With that idea, if you can understand a signaling pathway, perhaps it might impact the development of blood pressure, cardiovascular modeling, particularly with interstitial fibrosis and end organ injury. To be honest, we did not expect to find a factor that regulated perivascular fibrosis and end organ damage, but had no effect on blood pressure or interstitial fibrosis. This was a real surprise in the subject of the paper. Nikki Purcell: Like you said, the importance of T cells and perivascular fibrosis falling hypertension with Ang 2 infusion has recently been demonstrated, but you know, you guys were really focusing on what was the mechanism, trying to understand that. So, Dr Feinberg, can you elaborate on why you chose to focus on the CD-4+ T cells and hypertension in particular, how it came about the transcription factor, Kruppel like factor 10 or KLF 10? Mark Feinberg: Yeah. Great question. So we over accumulating studies many years now that CD-4 T cells play a particular important role, mediating hypertension, and a variety of preclinical models. For example, studies from David Harrison's or Steven Crowley's groups perform some classical experiments using immunocompromised mice. These are either RAG1 or SCID mice, which as, you know, have defective T or B cells. What's really interesting about those seminal papers was one that Ang2 mediated increase in blood pressure and the associated cardiac and kidney injury in these mice was severely blocked and two only when there was adoptive transfer of CD-4 T cells did that restore these deleterious effects in response to Ang2, indicating really for the first time that CD-4 T cells are key mediators of blood pressure and organ injury, and predominantly they focus on interstitial fibrosis and remodeling. However, the factors that mediate the CD-4 T cell effect on end organ damage or blood pressure really have been poorly defined over the years. Mark Feinberg: And so work from our group and others have identified over several years a transcription factor called KLF10 or Kruppel like factor 10 belongs to a family about 17 total Kruppel like factors. This one is expressed highly in CD-4 T cell subsets, both factors and T regulatory cells and work from our group and actually those are others have, have shown that KLF10 can regulate T cell factors. They're more hyperactivated and also the T regulatory subsets don't exhibit what we call immunosuppressive or anti-inflammatory properties. We've shown this now in the context of athero, we've developed CD-4 specific health and knockout mice, and when placed on a high fat diet, those mice developed obesity and insulin resistance. However, the role for KLF10 in CD-4 T cells and hypertension really was unknown and really came into this thinking that this was going to play a role in development of blood pressure and interstitial fibrosis. So it was, again, a real surprise for us. Nikki Purcell: I'm glad you mentioned that. Dr Zhuang, given the role of the CD-4T+ cells in controlling hypertension, you would've expected the blood pressure to be increased in your CDF4KLF10 knockout mice, but surprisingly, there was no difference. Can you tell us why you think this happened? Rulin Zhuang: Yeah, that's true. When we found severe cardiovascular fibrosis and vascular remodeling in TKO mice, after Ang2 infusion, the first potential explanation comes to us that there should be a difference in blood pressure, but we didn't find any difference in after 28 days and even 42 days after Ang2 treatment. So previous literatures did indicate that hypertension and is related cardiovascular injury could result from other forms of mediators, which is independent of blood pressure. Which suggests that blood pressure alone perhaps is not sufficient to predict end organ damage in hypertension. You know, it is because of the lack of difference in blood pressure that allow us to explore another molecule insights into perivascular fibrosis. Nikki Purcell: So Dr Chen, you found that the CD-4 positive KLF10 knockout mice had perivascular fibrosis in multiple organs, both the aorta, hearts and kidneys following Ang2 infusion. How did you identify that IL-9 was mediating these effects on perivascular fibrosis? Jingshu Chen: Actually after we found the phenotype in Ang2 treated TKO mice, we start to find some possible mediators involved in these multiple organ perivascular fibrosis. Firstly, we detect the expression of angiotensin to receptors in CD-4 positive T Cells, but no difference was observed between TKO and our Cre mice. KLF10 also have another name, which is TIEG1, TGFbeta Inducible Early Gene-1. So next we checked the TGFbeta signaling. But we didn't find any difference in the rational level of TGFbeta one to three between Cre and knockout mice in the CD-4+ T cells that made it. Also, we didn't find any impact of calcium in TGFbeta signaling in vivo supported by our different RNA seek dataset for some pathway analysis. We performed calcium flux profiling from our Ang2 treated TKO and Cre mice. Although we do find some cytokines, slightly changed TKO mice to treatment, IL-9 nine was the only one significantly increase dramatically in both male and female TKO miceIL-9 nine was reported in the regulation of the immune responses and played a pro fibrotic role in lung fibrosis and liver fibrosis. We'll assume that perhaps IL-9 contributes to perivascular fibrosis. We gave the recombinant IL-9, our control mice, which have a less perivascular fibrosis after Ang2 treatment. After we giving them recombinant IL-9, we do found more perivascular fibrosis, which is efficiently phenocopy what we observed in our transgenic mice. Also, our further study found that calcium could bind into IL-9 promoter and interact with HTAC-1 to inhibit IL-9 activation. That is where we make a conclusion that we consider that calcium deficient C4 positive release more IL-9 that introduce perivascular fibrosis. Mark Feinberg: I might add that, the discovery of this phenotype was almost missed. And I think it was interesting when Rulin described some of the initial H and E from the hearts of these mice and remember him saying there wasn't a lot of interstitial fibrosis, but there was lots of thickening outside the blood vessel wall. And what was interesting is that several of the aortas didn't show this, but it turned out those aortas Rulin had actually stripped for different reasons. And then when he repeated it without stripping and looking at all the organs, aorta, heart, kidney, you could tell easily who was the knockout, just blank, looking at the H and E slide. And he searched very hard for interstitial fibrosis. I actually had a colleague, Rick Mitchell who's a cardiac pathologist at the Brigham, review these slides in a blinded manner who, who verified that there was a lot of perivascular fibrosis in multiple organs, but no clear difference in interstitial fibrosis. That made us really excited about our new pathway to explore. Nikki Purcell: Nice. That leads you nice that you were talking about the strip because Dr Zhuang and Chen, you had through your RNA seek data found that calcium signaling were dominantly upregulated in those nonstripped aorta. That's the perivascular adventitia tissue wasn't removed in those, in the CD-4 + KLF10 knockout mice after Ang2 treatment. To further investigate calcium signal involved in the fibroblast and myophytes differentiation, you had gone and nicely isolated primary fibroblasts from these blood vessels. And that can be quite tricky. So can you tell us about what method was used to purify these fibroblasts for this study? Jingshu Chen: Yeah, it's actually very interesting progress for isolating those because when we search literatures, there's actually no well-established method to isolate from the aortas. We actually go from the aorta digestion to make sure we have a very good viability of the digestive cells. And then after that, Dr Zhuang and I kept discussing at lab, like why we just use the BES to isolate it's use the antibody, find the BES to isolate the fibroblasts. We tried a lot of methods and then finally we find optimize the protocol by use of magnetic BES these, but also to remove a lot of other cell types and to make sure we get the good purity of the fibroblasts. It's a very nice protocol and we actually published in the Atherosclerosis journal. It is already online. So I hope it can benefit the field. Anyone who can use it. Nikki Purcell: Yeah. It's these beautiful pictures that you've got from that isolation in the paper. You used both the cells as well as the tissue for several RNA Seq overlapping data sets in this manuscript. You used those stripped and non-stripped aortas from the KD-4 + KLF10 knockout Cre mice exposed to Ang2. But then as you talked about Dr Zhuang, you also use from a group of Ang2 to treated mice that received that anti IL-9 monoclonal antibody. What are some of the main findings that you found from these dataset that you'd like others to know? Jingshu Chen: Followed by the discussion, we are having the non-stripped and stripped aortas at very first, we sent off on the stripped aortas for sequencing, and we don't find a lot of genes are regulated actually only 200, 300 genes were regulated. It comes to the question actually, the perivascular fibrosis happened in adventitia. We sent out again for the nonstripped aorta, which has a perivascular fibrosis areas included. And luckily, we find like thousands of genes were regulated and a lot... /episode/index/show/circresearch/id/23437277

May 2022 Discover Circ Res 05/19/2022

May 2022 Discover Circ Res This month on Episode 36 of Discover CircRes, host Cynthia St. Hilaire highlights original research articles featured in the April 29 and May 13 issues of Circulation Research. This episode also features a conversation with Dr Patricia Nguyen and Jessica D'Addabbo from Stanford University about their study, Human Coronary Plaque T-cells are Clonal and Cross-React to Virus and Self. Article highlights: Zanoli, et al. Wang, et al. Harraz, et al. Zhao, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Dr Cyndy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh. And today, I'll be highlighting the articles from our April 29th and May 13th issues of Circulation Research. I also will speak with Dr Patricia Nguyen and Jessica D'Addabbo from Stanford University about their study, Human Coronary Plaque T-cells are Clonal and Cross-React to Virus and Self. Cindy St. Hilaire: The first article I want to share is titled Vascular Dysfunction of COVID 19 Is Partially Reverted in the Long-Term. The first author is Agostino Gaudio and the corresponding author is Luca Zanoli. And they're from the University of Catania. Cardiovascular complications, such as endothelial dysfunction, arterial stiffness, thrombosis and heart disease are common in COVID 19. But how quickly such issues resolve, once the acute phase of the illness has passed, remains unclear. To find out, this group examined aortic and brachial pulse wave velocity, and other measures of arterial stiffness in 90 people who, several months earlier, had been hospitalized with COVID 19. These measurements were compared with data from 180 controls, matched for age, sex, ethnicity and body mass index, whose arterial stiffness had been assessed prior to the pandemic. 41 of the COVID patients were also examined 27 weeks later to assess any changes in arterial stiffness over time. Together, the data showed arterial stiffness was higher in COVID patients than in controls. And though it improved over time, it tended to remain higher than normal for almost a year after COVID. Cindy St. Hilaire: This finding could suggest residual structural damage to the arterial walls or possibly, persistent low-grade inflammation in COVID patients. Either way, since arterial stiffness is a predictor of cardiovascular health, its potential longterm effects in COVID patients deserves further longitudinal studies. Cindy St. Hilaire: The second article I want to share is titled Gene Therapy with the N-Terminus of Junctophilin-2 Improves Heart Failure in Mice. The first author is Jinxi Wang and the corresponding author is Long-Sheng Song from the University of Iowa. Junctophilin-2 is a protein with a split personality. Normally, it forms part of the heart's excitation contraction coupling machinery. But when the heart is stressed, JP2 literally splits in two, and sends its N-terminal domain, JP2NT, to the nucleus, where it suppresses transcription of genes involved in fibrosis, hypertrophy, inflammation and other heart failure related processes. However, if this stress is severe or sustained, the protective action of JP2NT is insufficient to halt the progressive failure. This group asked. "What if this N-terminal domain could be ramped up using gene therapy to aid a failing mouse heart?" Cindy St. Hilaire: To answer this question, they injected adenoviral vectors encoding JP2NT into mice either before or soon after transaortic constriction, or TAC, tack, which is a method of experimentally inducing heart failure. They found, in both cases, that the injected animals fared better than the controls. Animals injected before TAC showed less severe cardiac remodeling than control mice, while those treated soon after TAC exhibited slower loss of heart function with reduced ventricle dilation and fibrosis. These data suggest that supplementing JP2NT, via gene therapy or other means, could be a promising strategy for treating heart failure. And this data provides a basis for future translational studies. Cindy St. Hilaire: The third article I want to share is titled Piezo1 Is a Mechanosensor Channel in Central Nervous System Capillaries. The first and corresponding author is Osama Harraz from the University of Vermont. Neurovascular coupling is the process whereby transient activation of neurons leads to an upsurge in local blood flow to accommodate the increased metabolic needs of the cell. It's known that agents released from active neurons trigger changes in local capillaries that prompt vasodilation, but how these hemodynamic changes are sensed and controlled is not entirely clear. This group suspected that the mechanosensory protein Piezo1, a calcium channel that regulates dilation and constriction of other blood vessels, may be involved. But whether Piezo1 is even found in the microcirculation of the CNS was unknown. This group shows that Piezo1 is present in cortical capillaries of the brain and the retina of the mouse, and that it responds to changes in blood pressure and flow. Cindy St. Hilaire: Ex vivo preparations of mouse retina showed that experimentally induced changes in hemodynamics caused calcium transients and related currents within capillary endothelial cells, and that these were dependent on the presence of Piezo1. While it is not entirely clear how Piezo1 influences cerebral blood flow, its pressure induced activation of CNS capillary endothelial cells suggest a critical role in neurovascular coupling. Cindy St. Hilaire: The last article I want to share is titled Small Extracellular Vesicles from Brown Adipose Tissue Mediate Exercise Cardioprotection. The first authors are Hang Zhao and Xiyao Chen. And the corresponding authors are Fuyang Zhang and Ling Tao from the Fourth Military Medical University. Regular aerobic exercise is good for the heart and it increases the body's proportion of brown adipose tissue relative to white adipose tissue. This link has led to the idea that brown fat, possibly via its endocrinal activity, might somehow contribute to exercise related cardioprotection. Zhao and colleagues now show that, indeed, brown fat produces extracellular vesicles that are key to preserving heart health. While mice subjected to four weeks of aerobic exercise were better protected against subsequent heart injury than their sedentary counterparts, blocking the production of EVs prior to exercise significantly impaired this protection. Furthermore, injection of brown fat derived EVs into the hearts of mice lessened the impact of subsequent cardiac injury. Cindy St. Hilaire: The team went on to identify micro RNAs within the vesicles responsible for this protection, showing that the micro RNAs suppressed an apoptosis pathway in cardiomyocytes. In identifying mechanisms and molecules involved in exercise related cardio protection, the work will inform the development of exercise mimicking treatments for people at risk of heart disease or who are intolerant to exercise. Cindy St. Hilaire: Lastly, I want to bring up that the April 29th issue of Circulation Research also contains a short Review Series on pulmonary hypertension, with articles on: The Latest in Animal Models of Pulmonary Hypertension and Right Ventricular Failure, by Olivier Boucherat; Harnessing Big Data to Advance Treatment and Understanding of Pulmonary Hypertension, by Christopher Rhodes and colleagues; New Mutations and Pathogenesis of Pulmonary Hypertension: Progress and Puzzles in Disease Pathogenesis, by Christophe Guignabert and colleagues; Group 3 Pulmonary Hypertension From Bench to Bedside, by Corey Ventetuolo and colleagues; and Novel Approaches to Imaging the Pulmonary Vasculature and Right Heart, by Sudarshan Rajagopal and colleagues; and Understanding the Pathobiology of Pulmonary Hypertension Due to Left Heart Disease, by Jessica Huston and colleagues. Cindy St. Hilaire: Today, Dr Patricia Nguyen and Jessica D'Addabbo, from Sanford University, are with me to discuss their study, Human Coronary Plaque T-cells are Clonal and Cross-React to Virus and Self. And this article is in our May 13th issue of Circulation Research. So, Trisha and Jessica, thank you so much for joining me today. Jessica D'Addabbo: Thank you for having us. Patricia Nguyen: Yes. Thank you for inviting us to your podcast. We're very excited to be here. Cindy St. Hilaire: Yeah. And I know there's lots of authors involved in this study, so unfortunately we can't have everyone join us, but I appreciate you all taking the time. Patricia Nguyen: This is like a humongous effort by many people in the group, including Roshni Roy Chowdhury, and Xianxi Huang, as well as Charles Chan and Mark Davis. So, we thank you. Cindy St. Hilaire: So atherosclerosis, it stems from lipid deposition in the vascular wall. And that lipid deposition causes a whole bunch of things to happen that lead to a chronic inflammatory state. And there's many cells that can be inflammatory. And this study, your study, is really focusing on the role of T-cells in the atherosclerotic plaque. So, before we get into the nitty gritty details of your study, can you share with us, what is it that a T-cell does normally and what is it doing in a plaque? Or rather, let me rephrase that as, what did we know a T-cell was doing in a plaque before your study? Patricia Nguyen: So, T-cells, as you know, are members of the adaptive immune system. They are the master regulators of the entire immune system, secreting cytokines and other proteins to attract immune cells to a diseased portion of the body, for example. T-cells have been characterized in plaque previously, mainly with immunohisto chemistry. And their characterization has also been recently performed using single cell technologies. Those studies have been restricted to mainly mirroring studies, studies in mice in their aortic walls, in addition to human carotid arteries. So, it is well known that T cells are found in plaque and a lot of attention has been given to the macrophage subset as the innate immune D. But let's not forget the T-cell because they're actually composed about... 50% in the plaque are T-cells. Patricia Nguyen: And we were particularly interested in the T-cell population because we have a strong collaboration with Dr Mark Davis, who's actually the pioneer of T-cell biology and was the first to describe the T-cell receptor alpha beta receptor in his lab in the 1970s. So, he has developed many techniques to interrogate T-cell biology. And our collaboration with him has allowed us and enabled us to perform many of these single cell technologies. In addition, his colleague, Dr Chen, also was pivotal in helping us with the interrogation and understanding of the T-cells in plaque. Cindy St. Hilaire: And I think one of the really neat strengths of your study is that you used human coronary artery plaques. So, could you walk us through? What was that like? I collect a lot of human tissue in my lab. I get a lot of aortic valves from the clinic. And it's a lot of logistics. And a lot of times, we're just fixing them, but you are not just fixing them. So, can you walk us through? What was that experimental process from the patient to the Petri dish? And also, could you tell us a little bit about your patient population that you sampled from? Jessica D'Addabbo: So, these were coronary arteries that we got from patients receiving a heart transplant. So, they were getting a heart transplant for various reasons, and we would receive their old heart, and someone would help us dissect out the coronary arteries from these. And then, we would process each of these coronary arteries separately. And this happened at whatever hour the hearts came out of the patient. Jessica D'Addabbo: So sometime, I was coming in at 3:00 AM with Dr Nguyen and we would be working on these hearts then, because we wanted the samples to be as fresh as possible. So, we would get the arteries. We would digest out the tissue. And then, we would have certain staining profiles that we wanted to look at so that we could put the cells on fax to be able to sort the cells, and then do all the downstream sequencing from there. Cindy St. Hilaire: So, in terms of, I don't know, the time when you get that phone call that a heart's coming in to actually getting those single cells that you can either send a fax or send a sequencing, how long did that take, on a good day? Let's talk only about good days. Jessica D'Addabbo: Yeah. A lot of factors went into that, sometimes depending on availability of things. But usually, we were ready with all of the materials in advance. So, I'd say it could be anywhere from six to 12 hours, it would take, to get everything sorted. Then, everything after that would happen. But that was just that critical period of making sure we got the cells fresh. Patricia Nguyen: So we have to credit the CT surgeons at Stanford for setting up the program or the structure, infrastructure, that enables us to obtain this precious tissue. That is Jack Boyd and Joseph Woo of CT surgery. So, they have enabled human research on hearts by making these tissues available. Because as you know, a transplant... They can say the transplant's happening at 12:00 AM, but it actually doesn't happen until 4:00 AM. And I think it's very difficult for a lab to make that happen all the time. And I think having their support in this paper was critical. And this has allowed us, enabled us, to interrogate kind of the spectrum of disease, especially focusing on T-cells, which are... They make a portion of the plaque, but the plaque itself has not like a million cells that are immune. A lot of them are not immune. So, enabling us to get the tissue in a timely fashion where they're not out of the body for more than 30 minutes enables us to interrogate these small populations of cells. Cindy St. Hilaire: That's actually the perfect segue to my next question, which is, how many cells in a plaque were you able to investigate with the single cell analysis? And what was the percentage again of the T-cells in those plaques or in... I guess you looked at different phases of plaque. So, what was that spectrum for the percentage of T-cells? Patricia Nguyen: So, for 10X, for example, you need a minimum of 10,000 captured cells. You could do less, but the utility of the 10X is maximized with 10,000. So, many times before the ability to multiplex these tissues, we were doing like capturing 5,000 for example. And the number of cells follows kind of the disease progression, in the sense that as a disease is more severe, you have more immune cells, in general. And it kind of decreases as it becomes more fibrotic and scarred, like calcified. So, it was a bit challenging to get very early just lipid-only cells. And a lot of those, we captured like 3000 or something like that. And efficiency is like 80% perhaps. So, you kind of capture… Cindy St. Hilaire: And also, how many excised hearts are going to have early athero? So, it's... Patricia Nguyen: Well, there are... nonischemics will have... Cindy St. Hilaire: Oh, okay. Okay. Patricia Nguyen: So, the range was nonischemic to ischemic. Cindy St. Hilaire: Oh great. Patricia Nguyen: So, about a portion... I would say one third of the total heart transplants were ischemic. And a lot of them were non ischemic. But as you know, the nonischemic can mix with ischemia. And so, they could have mild to moderate disease in the other arteries, for example, but not severe like 70%/90% obstruction. Cindy St. Hilaire: Wow. That's so great. That's amazing. Amazing sample size you have. So T-cell, it's kind of an umbrella term, right? There's many different types of T-cells. And when you start to get in the nitty gritty, they really do have distinct functions. So, what types of T-cells did you see and did you focus on in this study? Jessica D'Addabbo: So, the two main types of T-cells are CD4 positive T-cells and CD8 positive T-cells. And we looked at both of these T-cells from patients. We usually sorted multiple plates from each. And then, with 10X, we captured both. But our major finding was actually that the CD8 positive t-cell population was more clonally expanded than the CD4 population, which led us to believe that these cells were more important in the coronary artery disease progression and in the study that we were doing because for a cell to be clonally expanded, it means it was previously exposed to an antigen. And so, if we're finding these T-cells that are clonally expanded in our plaques, then we're hypothesizing that they were likely exposed to some sort of antigen, and then expanded, and then settled into the plaque. Cindy St. Hilaire: And when you're saying expansion, are you talking about them being exposed to the antigen in the plaque and expanding there? Or do you think they're being triggered in the periphery and then honing in as a more clonal population? Patricia Nguyen: So, that's a great question. And unfortunately, I don't have the answer to that. So basically- Jessica D'Addabbo: Next paper, next paper. Patricia Nguyen: Exactly. So, we... Interesting to expand on Jessica's answer. Predominantly what was found, as you said, was memory T-cells, so memory T-cells expressing specific markers, so memory versus naive. And these were effector T-cells. And memory meaning they were previously expanded by antigen engagement, and just happened to be in the plaque for whatever reason. We do not know why T-cells specifically are attracted to the plaque, but they are obviously there. And they're in a memory state, if you will. And some of them did display activation markers, which suggested that they clonally expanded to an antigen. What that antigen is, is the topic of another paper. But certainly, it is important to understand that these patients that we recruit, because they were transplant patients, they're not actively infected, right? That is a exclusionary criteria for transplants, right? Patricia Nguyen: So, that means these T-cells were there for unclear reasons. Why... /episode/index/show/circresearch/id/23136818

April 2022 Discover Circ Res 04/21/2022

April 2022 Discover Circ Res This month on Episode 35 of Discover CircRes, host Cynthia St. Hilaire highlights two original research articles featured in the April 1 issue of Circulation Research, as well as highlights from the Stroke and Neurocognitive Impairment Compendium in the April 15th issue. This episode also features a conversation with Dr Shubing Chen and Dr Yuling Han from Weill Cornell Medical College to discuss their study, SARS-CoV-2 Infection Induces Ferroptosis of Sinoatrial Node Pacemaker Cells. Article highlights: Pabel, et al. Pattarabanjird, et al. Iadecola, et al. Cindy St. Hilaire: Hi and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire, from the Vascular Medicine Institute at the University of Pittsburgh. And today I'm going to be highlighting articles from our April issues of Circulation Research. I'll also speak with Dr Shubing Chen and Dr Yuling Han from Weill Cornell Medical College, and they're with me to discuss their study, SARS-CoV-2 infection induces ferroptosis of Sinoatrial node pacemaker cells. Cindy St. Hilaire: The first article I want to share is titled, Effects of Atrial Fibrillation on the Human Ventricle. The first author is Steffen Pabel and the corresponding author is Samuel Sossalla and they're from Regensburg University. Atrial fibrillation, or AFib, is the most common form of heart arrhythmia. Patients with AFib may experience shortness of breath, dizziness and weakness. And they're also at risk for more life-threatening complications, such as clot-induced stroke and heart failure. Focusing on heart failure, this study investigated how disruptions to rhythm in the atria might lead to changes in the ventricular myocardium. The team studied ventricular muscle tissue from 24 patients with AFib and 31 without AFib. While the levels of fibrosis were equivalent in ventricular myocytes from both the AFib and the non AFib patients, other cellular features were distinct. For example, patients with AFib had reduced systolic calcium release, prolonged action potential duration and increased oxidative stress, compared with the non AFib patient controls. These differences were largely recapitulated in ventricular myocytes derived from human induced pluripotent stem cells that had been electrically stimulated to either mimic AFib or normal sinus rhythm. The results indicate that AFib affects the ventricles just as well as the atria and might therefore be best studied and treated with the whole heart in mind. Cindy St. Hilaire: The second article I want to share is titled B-1b Cells Possess Unique bHLH-Driven P62-Dependent Self-Renewal and Atheroprotection. The first author is Tanyaporn Pattarabanjird and the corresponding author is Colleen McNamara, from the University of Virginia. Atherosclerosis is a complex and dynamic chronic inflammatory condition. However, not all immune cells exacerbate this disease. Some immune cells are actively dampening the inflammation. B-1 cells are such cells that do this, and they produce IgM antibodies that bind cholesterol, preventing its uptake into macrophages and therefore limiting macrophage driven inflammatory responses. Increased number of B1 cells, therefore, might be atheroprotective. In mice, deletion of the transcription factor ID3 leads to a boost in B-1 cell IgM production. Cindy St. Hilaire: In this work the authors investigated the molecular mechanism underlying this effect and found that upon deletion of ID3 in mice B-1b cells, the level of P62 protein was increased. B-1b cell proliferation was found to be dependent on P62 and over expression of P62 in mouse B-1b cells increased cell numbers, raised plasma IgM levels and importantly, ameliorated diet-induced atherosclerosis in animals. The team went on to show that people with an ID3 mutation had an unusually high level of serum IgM and B-1b cell P62. This suggests that results from mice may hold true for humans, and if so, could inform the development of immunomodulatory treatments for atherosclerosis. Cindy St. Hilaire: So the April 15th issue of Circulation Research is our Stroke And Neurocognitive Impairment Compendium. The last Circulation Research Compendium on Stroke was published about five years ago. In this year Dr Costantino Iadecola, Dr Mark Fisher and Dr Ralph Sacco focused this update on advances made over the past five years, with a focus on topics that were not addressed in the previous compendium, that best reflect the leading edge of basic in clinical science related to cerebral vascular diseases. Seemant Chaturvedi, Brian Mac Grory and colleagues provide an overview of preventative strategies according to stroke mechanism, including stroke of unknown cause. And the challenges of stroke prevention with antithrombotic therapy and subjects with increased hemorrhage risk are also considered. Cindy St. Hilaire: Stéphanie Debette and Hugh Markus provide an account of the most recent developments in the genetics of cerebrovascular diseases. The gut microbiota is another factor that has recently been linked to stroke risk and Pedram Honarpisheh, Louise McCullough and colleagues provide a comprehensive overview of the microbiology and the microbiota, and the influence that stroke risk factors exert on its composition and homeostatic relationship with mucosal surfaces. Karin Hochrainer and Wei Yang provide a systematic review of the large amount of data and stroke proteomic from animal models and human patients. Matthias Endres and colleagues cover the dramatic effect that innate and adaptive immunity exert on stroke risk and on acute brain damage and post stroke sequelae, such as post-stroke cognitive impairment and depression. Cindy St. Hilaire: Manuela De Michele, Alexander Merkler and colleagues discuss the cerebral vascular diseases that have emerged as a frequent manifestation of the maladaptive immune response to severe SARS-CoV-2 infection. Jessica Magid-Bernstein and Lauren Sansing review the current concepts on epidemiology, risk factors in etiology, clinical features, as well as the medical and surgical interventions for cerebral hemorrhage. Yunyun Xiong and Marc Fisher cover the progress that has been achieved in the treatment of acute ischemic stroke and Natalie Rost and Martin Dichgans and colleagues address the long term impact of stroke on cognitive function, which is becoming a significant healthcare challenge in the world's aging population. Cindy St. Hilaire: So today I have Dr Shubing Chen and Yuling Han from Weill Cornell Medical College. And they're with me to discuss their study SARS-CoV-2 infection induces ferroptosis of Sinoatrial node pacemaker cells. And this article is in our April 1st issue of Circulation Research. So thank you both for joining me today. Shubing Chen: Thank you. It's really nice to join the program, and it's really a great honor. Cindy St. Hilaire: It's a really great article. I'm so excited to talk about. So there's a lot of research happening regarding SARS-CoV-2 virus and the patients who are infected and have COVID-19. And this paper is focusing on the impact of viral infection on the heart and specifically on the sinoatrial node, which is the primary cardiac pacemaker that keeps our hearts beating. So I was wondering if you could tell us what led you to focus on this particular aspect of COVID-19 symptoms, and also how early in the pandemic did you start this? Shubing Chen: Yeah, so we started working on SARS-CoV-2 through back to early 2020 when very unfortunately, New York City was a pandemic center and we had a lot of patients in the hospital unit, and also postdoc students working very hard in the lab. So that's the time we start working on SARS-CoV-2. And I was trained as a stem cell biologist. And what we're really interest is to set up a platform to basically understand which type of cells can be infected by SARS-CoV-2 and if they can, how they respond to SARS-CoV-2 infection. Not only for SARS-CoV-2, we sent it as like a viral infection platform, but SARS-CoV-2 is one of the virus we study now. And it's kind of very surprising. We have a pretty broad platform. We have a lung organoid, we have colon organoids, we have pancreas, we have cardiomyocytes, pacemaker cells. And as expected, we see lung can be infected like colon and because patient had GI tract, liver can be infected, but very surprisingly we see very high cardiomyocytes infection as well as pacemakers. So as we'll know that still big controversy in the field, whether we can detect SARS-CoV-2 like viral protein or viral RA in the heart, in particular, cardiomyocytes. But I think now everyone agree that the cardiomyocytes really can be very well infected actually. Because it's very difficult to get the pacemaker tissue and the sinoatrial tissue from the COVID patient. So we collaborate with Dr Ben Andora’s lab at NYU to get this hamster model. So we basically take SA tissue from hamster and then other colleagues basically did the section imaging, and we confirm that the hC4 polymerase cells can be infected by SARS-CoV-2. And at that time we start to learn a more clinical studies they report the COVID patient, they develop arrhythmia, or some other problem, not only with cardiomyocyte, as well as the conduction system. So at that time, that's the time that we say maybe we should do something on the pacemaker and focus on that. So that's how the project was developed. Cindy St. Hilaire: That is so interesting. And so I know humans infected, like you just said with SARS-CoV-2, they can develop arrhythmias. What's that timeframe? Is there a common timeframe that this happens? Does it normally happen very close to the infection or only in later stage? What's that window of when these arrhythmias are happening? Shubing Chen: At least based on the clinical study we show right now, actually the patient can develop acute arrhythmia. So it can be very soon after they developed symptom for COVID. Cindy St. Hilaire: Wow. That's amazing. So you mentioned this, your study utilized a hamster model, which you actually don't see a lot of. Most studies use a lot of rats or most studies I'm familiar with, especially in Circulation Research, they use more rats or more mouse models. So what advantages does that hamster model have and why were you interested in using it? Shubing Chen: Yeah, that's actually really specific for SARS-CoV-2. As SARS-CoV-2 mainly use ACE2 as a key entry factor to enter the cells. Of course, there's additional receptor, like neutrophils is one. Like all this enzyme involved, but human and mouse ACE2, they have very different structure. So the SARS-CoV-2 virus combine with human ACE2 very well but not mouse ACE2. So from the beginning, the rat and mouse was not used as a very good model to study SARS-CoV-2 infection. Of course there are other models, like knockin human ACE2 in the mouse and also like ACE2 transgenic mice. That's how different mouse model use. But hamster you don't need any modification, but they are very promising to SARS-CoV-2 infection. And so that's a reason we decide to use that as an animal model to basically run in parallel with our human stem cell model. Cindy St. Hilaire: We joke in my lab, mice are not little humans, but it's really true in a lot of cases, they're beautiful models in so many ways, but then when they don't work, they really don't work. Shubing Chen: Yeah. Before COVID every time when we try to talk about our human stem cell, derived cells, organoids as a disease model. People always ask, why do you want to work on human organoids? Right? It's that we have all these beautiful animal models like as you mentioned, mouse or rats, that's very broadly used. And we have to find different reasons. And now when we start working on SARS-CoV-2, which is very clear example, that mouse are not identical to human. Yeah. Cindy St. Hilaire: Yeah. That's great. I love finding additional models to use that are the best one for the question. So in order to investigate, I guess kind of the mechanism of how this was happening in the SAN cells, the sinoatrial node cells, you had to develop a new differentiation protocol that took the human embryonic stem cells, I think it was the H9 line you used, and essentially differentiate that cell line into a sinoatrial node-like cell. So I was wondering if you could tell us a little bit about A) how did you figure out that protocol and B) how does it work? Shubing Chen: So it's actually a long story to cell line. Cindy St. Hilaire: We can condense it. Let's get- Shubing Chen: At least based on the clinical study we show right now, actually the patient can. Let's condense it. But it's as you can imagine, we did not develop this cell line only for this particular project. Actually, we start working on this cell line back to maybe six, seven years ago. The first postdoc we have who basically knockin the mCherry, Myh6. Which basically label the atrial cardiomyocytes. And another postdoc, Zanir, he basically put a GFP in the SARS2 locus. So now we have this duel reporter line we can visualize the SA nodal cells. And we really spend a lot of time on that because we think that unfortunately in our hand, there is not really no good antibody for SARS2. We think it's very, very important that you can see these cells. So after developing these lines and because my lab run a lot of chemical screening, where we run Zanir, we run several chemical screening to develop the protocol. And Jialing Zhu, another postdoc in the lab, also pick up the project to further develop the protocol. And there is several years’ work. We do have this good protocol to make pretty efficiently to make the cells. And it's not only our work. I want to say that. For example, Dr Sean Wu from Stanford, they did this beautiful study on the single cell RNC mouse conduction system and Dr Gordon Keller and many other labs also basically published protocol in the field. We are very excited about this duel reporter line. I think they gave us a lot of new opportunity and we are very happy to share this line. Yeah. So if anyone in the field are interested in that, just contact us. Cindy St. Hilaire: Yeah. Anyone listening. That's great. So were you surprised to find the entry factors that SARS-CoV-2 uses to get into a cell, were you surprised to find them on these sinoatrial node cells? And I guess in the context of comparing these particular cells to other cells in the heart, are those entry factors higher in the sinoatrial node cells? Shubing Chen: So it can be either surprised or not surprised let's say this way. So because one, we see the cardiomyocytes that can be infected, we were kind of surprised. And then we find actually several type of cells in the heart can be infected, like endothelial cells. I will say that the ACE2 expression of like ACE2 aminophenol in pacemaker cell, it's not significantly higher than cardiomyocytes. So we are not really saying, or seeing that SA nodal cells are more permissive to SARS-CoV-2 infections compared to cardiomyocytes, even in the petri dish, but they can be infected. Cindy St. Hilaire: So you found SARS-CoV-2 infection in these sinoatrial nodal cells induces a process called ferroptosis. So Yuling, I was wondering if you could tell us what is ferroptosis and what is it doing in these pacemaker cells? Yuling Han: For the ferroptosis, they was surprised so far that its by the RA sequencing of the SARS-CoV-2 infection make our cells. And the first process is mainly caused by the- Shubing Chen: Error in iron. Yuling Han: Yes. So more intake of the iron error and induced the RA's pathway and caused the cell deaths. So by our RA sequencing, we found the key factor involved in ferroptosis pathway is the GPS score was checked after the SARS-CoV-2 infection. So we focused on the ferroptosis pathway and found other key factors or checked after the infection makes in the pacemaker cells. Cindy St. Hilaire: What is the ferroptosis doing that disrupts the SNA cells? Shubing Chen: Ferroptosis is a type of cell death mechanism. So eventually it will cause cell death. And we think something that is really surprising, but we think it's very interesting, is we only see ferroptosis in the SARS-CoV-2 infected general atrial cells. So SA cells, we actually, as Yuling mentioned, when we develop this platform, we see different type of cell can be affected. And we are very curious what happened. So we see that we run a sequence on each individual cells we can see infection and along, we can see cell death like apoptosis in cardiomyocytes. We see apoptosis and only in SA nodal cells, we actually see the ferroptosis pathway as we come up. Cindy St. Hilaire: Why do you think that is in that cell type versus in another? Do you have any ideas about why? Shubing Chen: No, we don't have any idea yet to be honest, but we are working on that. But at least I think that it gave us some clue that we really need to use different type of whole cells to study the whole cell response. Because traditionally when we study viral infection and when we see lung, we always... /episode/index/show/circresearch/id/22852094

March 2022 Discover CircRes 03/17/2022

March 2022 Discover CircRes This month on Episode 34 of Discover CircRes, host Cynthia St. Hilaire highlights four original research articles featured in the March 4 and March 18th issues of Circulation Research. This episode also features a conversation with Dr Mireille Ouimet and Sabrina Robichaud from the University of Ottawa Heart Institute to discuss their study, Autophagy is Differentially Regulated in Leukocyte and Non-Leukocyte Foam Cells During Atherosclerosis. Article highlights: Pauza, et al. Lim, et al. Hohl, et al. Liu, et al. Cindy St. Hilaire: Hi and welcome to Discover CircRes, the podcast of the American Heart Association's journal, Circulation Research. I'm your host, Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh, and today I'm going to be highlighting articles from our March issues of Circulation Research. I'm also going to speak with Dr Mireille Ouimet and Sabrina Robichaud from the University of Ottawa Heart Institute, and they're with me to discuss their study, Autophagy is Differentially Regulated in Leukocyte and Non-Leukocyte Foam Cells During Atherosclerosis. The first article I want to share is titled GLP1R Attenuates Sympathetic Response to High Glucose via Carotid Body Inhibition. The first author is Audrys Pauza, and the corresponding authors are Julian Paton and David Murphy at the University of Bristol. Cindy St. Hilaire: Hypertension and diabetes are risk factors for cardiovascular disease. And yet, for many patients with these two conditions, lowering blood pressure and blood sugar is insufficient for eliminating the risk. The carotid body is a cluster of sensory cells in the carotid artery, and it regulates sympathetic nerve activity. Because hypertension and diabetes are linked to increased sympathetic nerve activation, this group investigated the role of the carotid body in these disease states. They performed a transcriptome analysis of crowded body tissue, from rats with and without spontaneous hypertension. And they found among many differentially-expressed genes that the transcript encoding glucagon-like peptide-1 receptor or GLP1R, was considerably less abundant in hypertensive animals. Cindy St. Hilaire: This was of particular interest because the gut hormone GLP-1 promotes insulin secretion and tends to be suppressed in Type 2 diabetes. Moreover, GLP1R agonists are already used as diabetic treatments. This group showed that treating rat carotid body with GLP1R agonist suppresses sympathetic nerve activation and arterial blood pressure, suggesting that these drugs may provide benefits in more than one way. Perhaps the carotid body could be a novel target for lowering cardiovascular disease risk in metabolic syndrome. Cindy St. Hilaire: The second article I want to share is titled Inhibition of IL11 Signaling Reduces Aortic Pathology in Murine Marfan syndrome. The first author is Wei-Wen Lim, and the corresponding author is Stuart Cook and they're from the National Heart Center in Singapore. People with the genetic connective tissue disorder Marfan syndrome, are typically tall and thin with long limbs and are prone to skeletal, eye and cardiovascular problems, including a life-threatening weakening of the aorta. While Marfan syndrome patients commonly take blood pressure-lowering treatments to minimize risk of aortic aneurysm and dissection, there's currently no cure for Marfan syndrome or targeted therapy. Cindy St. Hilaire: The cytokine IL11 is strongly induced in vascular smooth muscle cells upon treatment with the growth factor TGF-beta, which is over activated in Marfan syndrome patients. And TGF-beta is also considered a key feature of the syndrome’s molecular pathology. This study found that IL11 is strongly upregulated in the aortas of Marfan syndrome model mouse, and that genetically eliminating IL11 in these animals protected them against aortic dilation, fibrosis, inflammation, elastin degradation and loss of smooth muscle cells. Treating Marfan syndrome mice with anti-IL11 neutralizing antibodies exhibited the same beneficial effects. These results suggest that perhaps inhibiting IL11’s activity could be a novel approach for protecting the aortas of Marfan syndrome patients. Cindy St. Hilaire: The next article I want to mention is titled Renal Denervation Prevents Atrial Arrhythmogenic Substrate Development in Chronic Kidney Disease. The first authors are, Mathias Hohl, Simina-Ramona Selejan and Jan Wintrich, and the corresponding authors also Mathias Hohl, and they're from Saarland University. People with chronic kidney disease have a two to three fold higher risk than the general population of developing atrial fibrillation, which is a common form of arrhythmia that can be life-threatening. Chronic kidney disease is associated with activation of the sympathetic nervous system, which can be damaging to the heart. Thus, this group examined myocardial tissues from atrial fibrillation patients with and without chronic kidney disease to see how they differ. They found that atrial fibrosis was more pronounced in patients with both conditions than in patients with atrial fibrillation alone, suggesting that chronic kidney disease perhaps exacerbates or even drives arterial remodeling. Cindy St. Hilaire: Sure enough, induction of chronic kidney disease in rats led to greater atrial fibrosis and incidence of atrial fibrillation than seen in the control animals. Renal denervation is a treatment in which the sympathetic nerves are ablated, and it's a medical procedure that's used for treating uncontrolled hypertension, and it has also been shown in animals to reduce atrial fibrillation. Performing renal denervation in the rats with chronic kidney disease reduced atrial fibrosis and atrial fibrillation susceptibility. This study not only shows that chronic kidney disease induces atrial fibrosis and in turn atrial fibrillation, but also suggests that renal denervation may be used in chronic kidney disease patients to break this pathological link and prevent potentially deadly arrhythmias. Cindy St. Hilaire: The last article I want to highlight is titled YAP Targets the TGFβ Pathway to Mediate High-Fat/High-Sucrose Diet-Induced Arterial Stiffness. First author is Yanan Liu and the corresponding author is Ding Ai from Tianjin Medical University. Metabolic syndrome is characterized as a collection of conditions that increase the risk of cardiovascular diseases, such as obesity, hypertension and diabetes. Among the tissue pathologies associated with metabolic syndrome is arterial stiffness, which itself is a predictor of cardiovascular disease incidence and mortality. To specifically investigate how arterial stiffness develops in metabolic syndrome, this group fed mice a high-fat, high-sugar diet, which is known to induce metabolic syndrome and concomitant arterial stiffness. Cindy St. Hilaire: After two weeks on the diet, the animals’ aorta has exhibited significant upregulation of TGF-beta signaling, which is a pathway known for its role in tissue fibrosis, and the aorta has also exhibited increased levels of yes-associated protein, or YAP, which has previously been implicated in vascular remodeling, collagen deposition and inflammation. YAP gain and loss of function experiments in transgenic mice revealed that while knockdown of protein in the animals’ smooth muscle cells attenuated arterial stiffness, increased expression exacerbated the condition. Cindy St. Hilaire: The team went on to show that YAP interacted with and prevented the activation of PPM-1 B, which is a phosphatase that normally inhibits TGF-beta signaling and thus fibrosis. Together the results suggest that targeting the YAP, PPM-1 B pathway, could be a strategy for reducing arterial stiffness and associated cardiovascular disease risk in metabolic syndrome. Cindy St. Hilaire: Today, Sabrina Robichaud and Dr Mireille Ouimet from University of Ottawa Heart Institute are with me to discuss their study Autophagy is Differentially Regulated in Leukocyte and Non-Leukocyte Foam Cells During Atherosclerosis, which is in our March 18 issue of Circulation Research. So thank you both for joining me today. Sabrina Robichaud: Thank you so much for having us. It's a pleasure. Mireille Ouimet: Thank you for having us. Cindy St. Hilaire: Yeah, and congrats on the study. So we know that LDL particles contain cholesterol and fats, and these are the initiating factors in atherosclerosis. And it's also really now appreciated that inflammation in the vessel wall is a secondary consequence to this lipid accumulation. Macrophages are an immune cell that, in the context of the plaque, gobble up this cholesterol to the point that they become laden with lipids and exhibit this foamy appearance, which we now call foam cells. And these foam cells can exhibit atheroprotective properties, one of them called reverse cholesterol transport, and that's really one of the focuses of your paper. So before we dig into what your paper is all about, could you give us a little bit of background about what reverse cholesterol transport is in the context of the atherosclerotic plaque? And maybe introduce how it links to this cellular recycling program, autophagy, which is also a big feature of your study. Mireille Ouimet: Yes, so the reverse cholesterol transport pathway is a pathway that's very highly anti-atherogenic. It's linked to HDL function and the HDL protective effects, in that HDL can serve as a cholesterol acceptor for any excess cholesterol from arterial cells or other cells of the body and return this excess cholesterol to the liver for excretion into the feces. There is also trans-intestinal cholesterol efflux that can help eliminate any excess bodily cholesterol. Mireille Ouimet: So reverse cholesterol transport is a way that we can eliminate excess cholesterol from foam cells in the vascular wall, and that's why we're really interested in the process. But the rate-limiting step of cholesterol efflux out of foam cells in plaques is actually, they have to be mobilized in the form of free cholesterol to be pumped out of the cells through the action of the ATP-binding cassette transporters. And so the rate-limiting step of the process is the hydrolysis of the cholesterol esters and the lipid droplets, because that's where the excess cholesterol is stored in foam cells. Mireille Ouimet: And so for years, people investigated the actions of cytosol like lipases in mobilizing free cholesterol from lipid droplets, although the identity of those lipases are not well-known and in macrophage themselves, but our recent work showed a role for autophagy in the catabolism of lipid droplets. And in fact, in macrophage foam cells, 50% of lipid droplet hydrolysis is attributable to autophagy while the other half is mediated by neutral lipases, which makes it really important to investigate the mechanisms of autophagy-mediated lipid droplet catabolism. Cindy St. Hilaire: That is so interesting. I guess I didn't realize it was that significant a component in that kind of rate-limiting step. That's so cool. So really, a lot of the cholesterol efflux studies, and maybe this is just limited to my knowledge of a lot of these cholesterol efflux studies, but to my knowledge, it's been really focused on the foam cell itself, the macrophage foam cell. However, there's been a lot of recent work that has now implicated vascular smooth muscle cells in this process. So could you share some of the research specific to smooth muscle cells and smooth muscle-derived foam cells that led you to want to investigate the contributions of smooth muscle cell-derived foam cells in cholesterol efflux? Mireille Ouimet: Yeah, so you're right in the sense that macrophages have always been the culprit foam cells in the atherosclerotic plaques but pioneering work from several groups, including Edward Fisher and Gordon Francis, they've shown that the smooth muscle cells can actually acquire a macrophage-like phenotype becoming lipid-loaded and foamy. And there's been work specifically looking at the ABC transporters, and their ability to efflux cholesterol from these vascular smooth muscle cell-derived foam cells, because as they trans-differentiate into macrophage-like cells, they acquire the expression of ABCA1, but this is to a lower extent, as compared to their macrophage counterparts. Mireille Ouimet: And the efflux is defective because there's an impairment in liposomal cholesterol processing of the lipoproteins that's really important to activate a like cell, and the expression of the ABC transporters, so vascular smooth muscle cell-derived foam cells are very poor effluxes. Sabrina Robichaud: There's very few studies that look at the vascular smooth muscle cell foam cells, and the very few that did look at it mostly focused on the ABCA1 transporters, and did show that they were poor effluxes. And as we all know, ABC1 is not the only cholesterol transporters that can transport cholesterol out of cells, there's also ABCG1 which is also one of our major findings in our paper. Cindy St. Hilaire: Can you tell us a little bit about the models you chose in the study and why you picked them? And also maybe a step back in terms of, what are the pros and cons of using mouse models in atherosclerotic studies? Sabrina Robichaud: So we chose to use the GFP-LC3 reporter mouse model because it allows us to track in lifestyle the movement of LC3, which is the main component of the autophagosome which is involved in pathology. So by using this reporter model, we could infer whether or not the cells had high autophagy or low autophagy. And to induce atherosclerosis in these mice, instead of backcrossing them to either an LDLR knockout or an ApoE knockout, we chose to do the adeno-associated virus that encode the gain of function PCSK9 instead to kind of minimize the time for breeding. It did have the effect that we needed in terms of raising plasma cholesterol to induce the atherosclerosis. So that was one of the models that we used in our paper. Mireille Ouimet: There's not very many good mouse models to study autophagy flux in vivo and GFP-LC3 is kind of the main one currently. We're working on developing some other tools to track lipophagy in vivo, but these things take time to put in place. So in the future, we hope to have some better tools to track lipophagy in real-time in vivo. Cindy St. Hilaire: How difficult is it to measure autophagy flux in vivo? I know there's certain part like LC3 or P62, a lot of people use a western blot and it's like, oh, it's high, it must be active, but it's a flux. So it's a little bit more... There's more subtleties to that, dynamic than that. So how difficult is it to really measure this flux in in vivo tissues? Mireille Ouimet: Yes, so now there are more recent mouse models that have been developed more recently to replace kind of the GFP-LC3 is the Rosella LC3. So it has both a red and a green tag, and so two LC3, so when autophagosomes are fused to lysosomes and are degraded, then there's preferential quenching of the GFP first, and then you have the red appearance that predominates so we know that then it's kind of like it a live flux measurements. Because we use the GFP-LC3 mouse, Sabrina treated her cells ex vivo. When we dissected out the aortic arches, digested the cells then we divided those into two components and added bafilomycin so that we can inhibit lysosome acidification to see the changes in the flux. And that's really to get the differences in untreated versus bafilomycin-treated. Mireille Ouimet: When we inhibit the lysosome, then we're sure that it is a functional flux or not. But it's kind of an indirect way of measuring it, and it reads very complex when we're talking about P62 and LC3 degradation with or without lysosome inhibition, but you really need that lysosomal inhibition, to show that if you block the degradation of the autophagosomes that fuse in with a lysosome, then you get an increase in the LC3 and the P62, and that's when you know that the flux is you intact. Mireille Ouimet: Because you could get an increase in LC3, that's just related to a defect in the breakdown of the autophagosome. But in our study, we've used phosphorylated ATG16L1, which is a now better marker of active autophagy. And I would recommend researchers to begin to use that rather than the combination of P62 and LC3 together with or without a lysosome inhibitors such as- Cindy St. Hilaire: Oh, interesting. So let's repeat that, phosphorylated ATG- Mireille Ouimet: 16L1, yes. So there's been an antibody that was developed by a colleague at the University of Ottawa, Dr Ryan Russell, and it's commercially available through cell signaling now, and it really has been a great tool to track active autophagy. Cindy St. Hilaire: That's great. I remember my lab was looking at that at one point, and I was trying to explain the flux as... I don't know if people are going to remember this, but there's this amazing, I Love Lucy skit, where her and Ethel are working on a chocolate factory conveyor belt, and it picks up speed. And because she can't get it all done quick, she starts stuffing them in her mouth. And it's like, if you just took a snapshot of that, you would not know whether it's going too fast, or not functioning properly. And so I equate the flux experiments to that. Which are probably aging myself a lot on so. Cindy St. Hilaire: All right, so sticking to kind of the autophagy angle, what were the differences you found in autophagy in early and late atherosclerotic plaques? Because I know you looked at those two time points, but also, importantly, between the macrophage foam cells and the smooth muscle cell-derived foam cells? Sabrina Robichaud: So surprisingly, there weren't that big of a difference between each time point when we were looking at the individual cell type by themselves. Surprisingly, we did find that the macrophages did have a functional autophagy flux, even at the later stages of atherosclerosis, which was kind of interesting in itself. But when we looked at the vascular smooth muscle cell foam cells, though, that was a whole other story, and we found that these were actually defective at a very early stage and stayed defective up until the very late stage of atherosclerosis. Cindy St.... /episode/index/show/circresearch/id/22458842

February 2022 Discover Circ Res 02/17/2022

February 2022 Discover Circ Res This month on Episode 33 of Discover CircRes, host Cynthia St. Hilaire highlights two original research articles featured in the February 4 issue of Circulation Research. In addition, she previews Circulation Research’s Compendium on Women and Cardiovascular Health, featured in the February 18th issue. This episode also features a conversation with Dr Alastair Poole and Dr Laura Corbin from the University of Bristol and Dr Stephen White from the Manchester Metropolitan University about their study, Epigenetic Regulation of F2RL3 Associates with Myocardial Infarction and Platelet Function. Article highlights: Samargandy, et al. Gilchrist, et al. Cindy St. Hilaire: Hi, and welcome to Discover CircRes, the podcast of the American Heart Association's Journal, Circulation Research. I'm your host, Dr Cindy St. Hilaire from the Vascular Medicine Institute at the University of Pittsburgh and today I'm going to be highlighting articles from our February issues of Circulation Research. I'm also going to speak with Dr Alastair Poole and Dr Laura Corbin from the University of Bristol and Dr Stephen White from the Manchester Metropolitan University about their study, Epigenetic Regulation of F2RL3 Associates with Myocardial Infarction and Platelet Function. Cindy St. Hilaire: The first article I want to share is titled Trajectories of Blood Pressure in Midlife Women: Does Menopause Matter? The first author is Saad Samargandy, and the corresponding author is Samar El Khoudary from the University of Pittsburgh. Blood pressure increases with age, but after midlife, the rate of increase for women generally exceeds that for men. This observation has led to debate over whether menopause might influence the blood pressure trajectory. Cindy St. Hilaire: To find out, this group examined data on over 3300 women of diverse ethnicity enrolled in the Study of Women's Health Across the Nation, or SWAN study. The women began the study between 42 and 52 years old, and they had 17 follow-up visits at roughly one-year intervals. At these visits, blood pressure, hormone levels, weight and other health parameters were measured. Cindy St. Hilaire: Analysis of the data revealed women fell largely into three blood pressure trajectory groups. Those with low blood pressure before menopause and accelerated blood pressure after menopause, those with a linear increase linked to age, and those with high blood pressure before and a slower ascent afterwards. White, Chinese and Japanese women were more likely to be in the low to accelerated group, as were those with early menopause, while Latino and Black women were more likely to have high blood pressure in general. Together, the results indicate that for many women, menopause itself does not accelerate age-related blood pressure increase, and that women of menopausal age should be advised of this risk and have their blood pressure monitored regularly. Cindy St. Hilaire: The second article I want to highlight is titled Research Goes Red: Early Experience With a Participant-Centric Registry. The first author is Susan Gilchrist and the corresponding author is Jennifer Hall from the American Heart Association. Cardiovascular disease is a leading cause of death for men and women alike, but there are particular factors such as pregnancy and menopause that may specifically influence the genesis, presentation and management of the condition in women. Cindy St. Hilaire: With that in mind, for the past two decades, the AHA's Go Red for Women campaign has been raising awareness of and driving research into women's cardiovascular health issues. The latest Go Red initiative, an online platform called Research Goes Red, was launched in 2019 with the aim of empowering women to contribute to health research by, among other things, taking part in health surveys. In the last two years, the platform has garnered 15,000 registered individuals between the ages of 30 and 60. It has deployed six targeted health surveys and prompted two AHA-funded research studies based on participant responses: one on perimenopausal weight gain, and one on the use of social media to engage young women in cardiovascular disease awareness. While Research Goes Red has successfully amassed middle aged participants, the authors say that future goals should include increasing the number and the diversity of the registrants and encouraging researchers to use the registry not just for data, but for identifying potential trial participants. Cindy St. Hilaire: I want to now mention the 15 articles that are featured in our Compendium on Women and Cardiovascular Disease that is featured in our February 18th issue of Circulation Research. And this also happens to correspond with February being the American Heart Month. So Susan Cheng and colleagues present A Scientific Imperative As Seen Through a Sharpened Lens: Sex, Gender and the Cardiovascular Condition. Genetic, molecular and cellular determinants of sex-specific cardiovascular traits is discussed by Teemu Niiranen and colleagues. Bonnie Ky et al. describe sex-specific cardiovascular risks of cancer and its therapies. Sex differences and similarities in valvular heart disease is presented by Francis Delling and colleagues. Cecile Lahiri and colleagues wrote about the cardiovascular implications of immune disorders in women. Joshua Smith and colleagues discuss sex differences in cardiac rehabilitation outcomes. Cindy St. Hilaire: Pregnancy and reproductive risk factors of cardiovascular disease in women is reviewed by Michael Honigberg and colleagues. The impact of sex and gender on stroke is presented by Kathryn Rexrode and colleagues. Ersilia DeFilippis and colleagues cover heart failure subtypes and cardiomyopathies in women. Demilade Adedinsewo and colleagues wrote about cardiovascular disease screening in women, leveraging artificial intelligence, and digital tools. Sexual dimorphism in cardiovascular biomarkers, clinical research implications, is discussed by Jennifer Ho and colleagues. Connie Hess et al. review sex differences in peripheral artery disease. Janet Wei and colleagues provide an update on coronary arterial function and disease in women with non-obstructive coronary arteries. Sex differences in myocardial and vascular aging is presented by Hongwei Ji and colleagues. And lastly, arrhythmias in female patients, incidence, presentation and management, is reviewed by Andrea Russo and colleagues. Cindy St. Hilaire: Today I have with me Drs Alastair Poole and Laura Corbin from the University of Bristol and Dr Stephen White from the Manchester Metropolitan University. And they're here with me to discuss their study, Epigenetic Regulation of F2RL3 Associates with Myocardial Infarction and Platelet Function. And this article is in our February 4th issue of Circ Res. Well, Drs Corbin, Poole and White, thank you so much for joining me today. Laura Corbin: Thank you very much. Stephen White: Thank you. Alastair Poole: Thanks. Cindy St. Hilaire: So this is a really neat study. It's bringing in a couple different fields. It's investigating what I'm calling a Venn diagram of these intersecting topics all related to cardiovascular disease: cigarette smoking, epigenetic modification and platelet activation. So can you maybe give us a little bit of background on the status of the field and how these three topics intersected at the start of your study? Laura Corbin: So yeah, our working hypothesis was based on existing literature and it was really to look at whether smoking-induced epigenetic DNA hypermethylation of F2RL3 could increase risk of myocardial infarction and whether the route to that could be through platelet function. So there's quite a lot of literature going back probably to around about 2015 that shown that there are changes to the methylome in response to smoking. And DNA methylation is a way of cells controlling gene expression, but without having to actually make changes in the DNA sequence itself. So this could be a really important way that we know that smoking increases the risk of a number of cardiovascular diseases, but we don't really know how that happens. And one way that that could happen is through changes to methylation. Cindy St. Hilaire: What is known about how cigarette smoke impacts the status of DNA methylation? How has that switched or changed? Maybe when someone is actively smoking, when someone quits, is it dynamic? What is known about that relationship? Laura Corbin: Okay. So yeah, going back to about 2015, there was a number of studies that looked at methylation across the whole genome. So in a hypothesis-free untargeted manner, developments and technology meant that we could look at many, many sites across the genome at the same time. And so studies were done to look at changes that were associated with smoking. And what was found was those changes, actually quite a lot of changes across the genome in a number of different genes, but not really anything much beyond that. So F2RL3 was one of the first sites to be identified as being associated, methylation at that site associated with smoking. And it was replicated in several studies. Laura Corbin: And it was also showing that there was a dose-response relationship. So the more a person smoked, the less methylated that site appeared to be. And then there's been some work done already, but we also did it in our paper to show that those methylation marks actually hang around for quite a long time once somebody quits smoking. But also that there's a lot of variation within an individual, so even if you smoke, it doesn't necessarily mean that you'll definitely have low methylation, there's still variation. So there's other factors that are involved in that. Cindy St. Hilaire: So you were looking at a specific population of patients, can you tell us a little bit about that group of patients you were looking at? And you mentioned the variability in the amount of smoke they were exposed to, do you know that information? And I guess one of the base questions I had is I'm in Pittsburgh, which back in the '80s and earlier was a steel mill town that had a lot of pollution. And so I'm wondering if you're able to clearly separate out a cigarette smoker from maybe someone who is a light cigarette smoker, but lives in a more polluted area? Laura Corbin: Okay. So there's two parts of the study that were looking at this in a human context, so in a whole person context. One of those was using data from the Copenhagen City Heart Study, and that's the one where we looked at the relationship between smoking and methylation and then between methylation and myocardial infarction. So that study is great because it's been tracking people over time and so we're able to use the samples that were collected before they had their cardiovascular event and look at methylation at that point. So we know that the event occurs after that point, which is important. And so we were able to verify in that population that we did see an association between smoking and methylation. We were able to show that it was a dose-dependent relationship. So if we look at something like in that dataset, we had things like the intensity of which people smoke, so pack years is one of the things that we looked at. And it did appear to correspond in an approximately linear fashion. Laura Corbin: So we don't really know, I don't think, at this point, what impact other environmental exposures would have on the methylome and how that would interact with the cigarette smoking. That's actually a really interesting point that we'll probably come onto later about whilst we were looking here at the smoking effect on this methylation site, in the second part of the work, we were able to show that even in non-smokers, there's variability in methylation at this site, and that can still have impacts on the biology downstream. So yeah, it's an interesting point. Stephen White: Just to maybe just jump in, there's very good amounts of literature now that show quite a good correlation between changes in air quality and cardiovascular events. So smogs, wildfires and so on, clearly correlate with an increase in cardiovascular events. But actually the opposite's also been observed in the more recent COVID lockdowns, where reduction in air pollution also mirrored a reduction in the number of cardiovascular events. So I think you raise a really interesting point about is it cigarette smoke alone or does air quality in general play an effect? And clearly it does play an effect, although we didn't correlate that within this current dataset. Cindy St. Hilaire: Your study looked at DNA methylation patterns at cytosine, phosphate, guanidine or CPG sites in the genome. Can you tell us a little bit more about what these islands are and how they change throughout maybe different cells in the body, but also maybe in the same cell, but throughout the course of life or the course of, in this case, cigarette exposure? Stephen White: So if we just want to focus in on our study, what we showed was that exposure to cigarette smoke changes endothelial cell methylation. It also changes megakaryocyte methylation patterns in the same way. And I think one of the surprising things was that only 48 hours of exposure to cigarette smoke significantly changes the methylation pattern of the F2RL3 locus. So it's quite a dynamic event, but it does show that these can be quite rapidly regulated. And Laura's really nice work shows that the methylation on cessation of smoking, that pattern does actually go down, but it's a 20-year process. So it looks like it can be rapidly induced, but may actually remain as a methylation mark for a considerable length of time. Stephen White: And I think one of the things we did in our study was actually to triangulate not only the observational data and the association data in patients, but actually start to look at a mechanism of how that might actually relate to changes in gene expression. So we showed that this particular CPG site is right next to a binding site for a transcription factor, and transcription factors are the cell’s way of regulating how much of a particular gene is expressed. And we show that changes in methylation changed the binding of this transcription factor and therefore change the amount of this particular gene that was made. Cindy St. Hilaire: Yeah. Actually, I want to start to talk about that locus you were interested in. So what was known about the F3RL2 locus? How big is it, but also what genes are there and what did you start to investigate with your in vitro modeling? Stephen White: So I think when we started, we had the observation that a change in methylation at the F2RL3 locus was associated with the risk of cardiovascular events. And then it was a detective expedition into the gene using various in silico analyses that identified the methylation site that we are interested in, or most interested in, is right next to a transcription factor binding site. Stephen White: So we then went on to show that binding of that transcription factor is sensitive to methylation, that if we would just excise that piece of DNA, we can show that that has the ability to regulate F2RL3 expression or the expression of a reporter gene. And then if you knocked out the transcription factor binding site, you lose that regulation. So it was a series of detective work and experimental steps that allowed us to put a mechanism behind the observation that changes in methylation might truly affect the level of gene expression of the F2RL3, otherwise known as PAR4 to platelet biologists. So get that in there. Alastair Poole: I first came across it when another member of our team actually mentioned it to me over a casual conversation actually a few years ago that F2RL3 gene was regulated in this way. To me as a platelet biologist, F2RL3 didn't mean a lot, but when I was told then it was the gene that encodes PAR4, it meant everything. And so platelet biologists, we talk about PAR4, which is of course the protein product of the F2RL3 gene. And PAR4 is one of several really key receptors on a platelet surface that responds to, in this case, to changes in thrombin generation, thrombin activity, which is of course the major effectively end product of the coagulation cascade. Alastair Poole: So it's what couples coagulation and platelet biology together, thrombin. And there are two major receptors on platelets that operate in response to changes in thrombin and that's PAR1 and PAR4. And they're both very important genes, but yeah, really interestingly, you have this rather selective effect on PAR4 and the paper actually shows it is indeed a selective effect on PAR4 as opposed to PAR1 in terms of epigenetic regulation of its responsiveness to PAR4 activation. Cindy St. Hilaire: So I want to tap back onto something that Laura had mentioned briefly, and that is talking about your platelet assays where you isolated platelets from a specific subset of the patients. And I believe it was figure three, and you looked at patients who in adolescence had exhibited differences in the methylation pattern at the site in the F3RL2 locus. What do we know about that innate or early-age change? And then I would love to hear more about this actual experiment, how you looked at the patients earlier versus current and what the thinking was behind that. Laura Corbin: So yeah, this part of the work was done in a birth cohort study called the Avon Longitudinal Study of Parents and Children, which is based at the University of Bristol. And this is a really great study, a great resource that we have, and in fact, it's open to all researchers so anyone could use it, where mothers were recruited during pregnancy, which was in around 1991 to 1992. And then those children that were born from those pregnancies have then been followed up ever since. Laura Corbin: So that was the data that we were able to use for this part of the... /episode/index/show/circresearch/id/22126595

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