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References Nature Communications 2019. volume 10, Article number: 1528 Adv Exp Med Biol. 2019:1111:1-17. doi10.1007/5584_2018_185. Nature Immunology volume 20, pages559–570 (2019) Biochem J. 2001 Dec 15; 360(Pt 3): 513–530. PNAS 1993. 90: 10952-10956 --- Send in a voice message: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/message Support this podcast: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/support
References J Zhejiang Univ Sci B. 2022 Jul 15; 23(7): 607–612 Biomaterials. 2020 Apr; 238: 119836. Int J Nanomedicine. 2023;18:5265-5287 Child Ballad 100. 1775. Pentangle. 1972.Willie O' Winsbury https://youtu.be/nwqP_yoszCE?si=C0NH51euOOTlPYn9 --- Send in a voice message: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/message Support this podcast: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/support
References FASEB 2017. Volume 31, Issue2 Pages 663-673 Guerra,DJ. Graduate Biochemistry Lectures Albioni , Thomaseo. 1708. Sonate da chiesa ("op. 4") (for violin and basso continuo), https://youtu.be/IMmjjcfG2c4?si=C4VG-rPWL_Fv7-Xe --- Send in a voice message: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/message Support this podcast: https://podcasters.spotify.com/pod/show/dr-daniel-j-guerra/support
Dr Glenn McConell chats with Dr Carlos Henríquez-Olguín from The University of Copenhagen, Denmark. Carlos is an up and coming rising star exercise metabolism researcher. He discusses the challenges of doing mechanistic exercise research in Chile and how he ended up moving to the University of Copenhagen. Language challenges etc. He has been doing really ground breaking research on reactive oxygen species (ROS) and contraction/exercise and already won awards for his research. Twitter: @MuscleBiology.0:00. Introduction/reason invited Carlos onto Inside exercise4:00. Challenges doing mechanistic exercise research in Chile etc9:37. Cell culture and mouse ROS experiments in Chile12:11. How got into reactive oxygen species research14:25. Muscle dystrophy, contraction and ROS16:09. Chronic versus acute increases in ROS16:49. How/why moved to the University of Copenhagen19:20. No success with initial research at the University of Copenhagen20:30. Made his own luck21:39. The need for patience from supervisor if facing challenges23:40. Language challenges when coming from Chile26:30. Giving better visibility to early career researchers31:04. Prizes he has won in both exercise and ROS34:08. Challenges publishing when from less scientifically recognized countries36:22. What are reactive oxygen species?37:50. Theory of ROS and aging38:30. ROS, antioxidants, oxidative stress, ROS signaling40:05. Muscle antioxidants, exercise and disease42:19. Where in muscle are ROS coming from during contraction?45:02. NOX2, RAC1, glucose uptake with contraction47:21. What's activating ROS production during contraction?48:11. Nitric oxide vs ROS vs both?50:15. Acute versus chronic increases in ROS53:16. Best exercise for increasing your antioxidant defenses?57:50. High ROS production from mitochondria in some diseases59:30. Can exercise improve these diseases by producing ROS?1:00:41. Compartmentalization of ROS production in muscle1:02:03. Should supplement with antioxidants?1:07:23. Increased mortality in people taking high levels of supplements1:06:32. Antioxidant supplements improve those with chronically high ROS?1:09:20. Mitochondria ROS and mitochondria specific antioxidants1:14:37. Exercise and antioxidant gene expression1:16:50. Mitochondria have antioxidant enzymes1:17:50. Carlos's methods to study ROS with contraction/insulin resistance1:23:20. Takeaway messages1:27:39. ROS and glucose uptake during exercise1:29:43. Outro (9 seconds) Inside Exercise brings to you the who's who of research in exercise metabolism, exercise physiology and exercise's effects on health. With scientific rigor, these researchers discuss popular exercise topics while providing practical strategies for all.The interviewer, Emeritus Professor Glenn McConell, has an international research profile following 30 years of Exercise Metabolism research experience while at The University of Melbourne, Ball State University, Monash University, the University of Copenhagen and Victoria University.He has published over 120 peer reviewed journal articles and recently edited an Exercise Metabolism eBook written by world experts on 17 different topics (https://link.springer.com/book/10.1007/978-3-030-94305-9).Connect with Inside Exercise and Glenn McConell at:Twitter: @Inside_exercise and @GlennMcConell1Instagram: insideexerciseFacebook: Glenn McConellLinkedIn: Glenn McConell https://www.linkedin.com/in/glenn-mcconell-83475460ResearchGate: Glenn McConellEmail: glenn.mcconell@gmail.comSubscribe to Inside exercise:Spotify: shorturl.at/tyGHLApple Podcasts: shorturl.at/oFQRUYouTube: https://www.youtube.com/@insideexerciseAnchor: https://anchor.fm/insideexerciseGoogle Podcasts: shorturl.at/bfhHIAnchor: https://anchor.fm/insideexercisePodcast Addict: https://podcastaddict.com/podcast/4025218Not medical advice
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 Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1β Mediated Inflammation. Article highlights: Pi, et al. Metabolomic Signatures in PAH Carnevale, et al. Thrombosis TLR4-Mediated in SARS-CoV-2 Infection Cai, et al. Macrophage ADAR1 in AAA Koide, et al. sEVs Accelerate Vascular Calcification in CKD 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 symptoms or adverse effect they are seeing and if these symptoms are associated with something else. So there is data that if patients having CVD risk factor, they are more prone to develop ponatinib induced cardiac events. But it needs more polish like you asked the just previous question, diabetes versus maybe blood pressure means hypertension, atherosclerosis, or thrombosis. So it has not been delineated further but in a one big bucket if patients are having CVD risk factor before they are more prone and more likely to develop the cardiac events. Cindy St. Hilaire: So after you established that these two murine models could pretty robustly recapitulate the human phenotype, what did you do next? How did you come upon the S100A8/A9-NLRP3-IL-1β signaling circuit? How did you get to that? Hind Lal: So in basic science work, whenever we do mouse is called until we get there is cardiac dysfunction, it's called phenotype, right? So mouse had a cardiac phenotype. So next step is, "Why? What is leading to that phenotype?" That's what we call mechanism. So there the best idea to fit the mechanism is using one of the unbiased approaches like you do unbiased proteomics, unbiased RNC analysis, something like this that will analyze the entire transcript like RNC and say, "Okay, these pathway are," then you can do further analysis that will indicate these pathway are different, are altered. So in this case we used RNC analysis and it came out that this yes A8 and yes A9, 100A8 and nine, they were the most upregulated in this whole set. And thereafter we were very lucky. So we started this study at Vanderbilt, where my lab was and thereafter we very lucky to move here and found Sultan who had a lot of experience with this inflammation and immune system and then Sultan may add something on this so he'll be the better person to say something on this. Tousif Sultan: So after our RNC analysis, so we got this S100A8 and nine as top hit with the ponatinib treatment. So then we validated this finding with our flow cytometric, qRT PCR aand then we started which pathway is going to release cytokine and all that. So we found that is NLRP3 inflammasome. Cindy St. Hilaire: Yeah and well and I guess maybe step back, what is S100A8/A9? What are those? Tousif Sultan: Yeah, S10A8/A9 is a calcium binding protein. So that's also called alarmin and they basically binds with the pathogen associated pattern and other TLR2 like receptors and then start inflammatory pathway to release cytokine and all that and it's stable in heterodimer form. So S100A8 heterodimer with A9 and then bind with TLR and a start in this inflammatory pathway. Cindy St. Hilaire: And what type of cell is that happening in? Is that happening in the immune cells only or is it also in the cardiomyocyte, or...? Tousif Sultan: Yeah, we have included all this data. So from where this alarmin is coming with ponatinib treatment, so literature also suggested that neutrophils and monocytes, those cells are the potential to release the alarmin. So here we also found these two type of cells, neutrophils and monocytes. They release huge alarmin with the treatment of ponatinib. Cindy St. Hilaire: And so really taking this really neat mechanism to the next level, you then tried attenuating it by using broad anti-inflammatory steroid dexamethasone but also by targeting these specific components, the NLRP and the S100A specific inhibitors and they worked well. It worked really nicely. Does your data show that any of these therapies work better than the other and then are these viable options to use in humans? Hind Lal: Yeah, we have some data in the paper. Are very broad which help a lot in COVID patients, far very acute infections. So in this case, situation is very different cause most of CML patients will going to take ponatinib for lifelong, there is no remission, right? So in those case, its certainly not a very attractive option. We have shown data in the paper that dexamethasone help with the heart but lead to some metabolic changes. So we have compared those with the NLRP3 inhibitors, those metabolic alterations, dexa versus the NLRP3 inhibitors, CY-09. And we demonstrated that targeting is specifically with paquinimod, our NLRP3 inhibitor CY-09, feel better. It can still rescue the cardiac phenotype without having those adverse effect on metabolic parameters. Cindy St. Hilaire: That's wonderful. Do you think though that because you have to take ponatinib for life, that long-term NLRP inhibition would also cause problems or...? Hind Lal: So because not every patient who taking ponatinib would develop the cardiac phenotype, right? Which is like a 10%, 12%, patient developing cardiac dysfunction. So I think someone like I strongly believe paquinimod, which is inhibitor of S100A9, will be really good option or at least we have enough data that make us nail for at least a small clinical trial. And we quickly moving on that. At UAB we have our clinical cardio-oncology program and we are already in touch with the director for the clinical cardio-oncology program. So what we trying to do in that small trial is if one of the standard therapy for heart like beta blocker or ARBs inhibitor, is there any preference like one work better than the other in the standard care? So first we doing that project, then we obviously looking forward if one small clinical trial can be done with paquinimod. I strongly believe it should be helpful. Cindy St. Hilaire: That is wonderful. And so do you think... There's other chemotherapeutic agents or probably even other non-cancer drugs that cause cardiotoxicity, do you think this mechanism, this pathway, this S100A-NLRP-IL-1β axis is operative in all cardiotoxicities or do you think it's going to be very specific to the ponatinib? Hind Lal: So it's certainly not all, but it'll be certainly more than ponatinib. So in our lab we are using another kinase inhibitor, which is osimertinib and it's not published yet, but now we know that it's also cardiotoxic because it's taking metabolic root or energetics disruption but not this pro-inflammatory part, but we're doing another project which is strep pneumonia induced cardiac dysfunction, which is called pneumonia. So strep pneumoniae, which leads to the pneumonia ,and lot patient die because of the failing heart we see here in the hospitals and we see these pathways operational over there and we gearing up to do clinical trial on that aspect as well, but it's not generalized like all kind of heart will have the same mechanism. Cindy St. Hilaire: It's wonderful to see you're already taking those next steps towards really kind of bringing this to a translational/clinical study. So what was the most challenging aspect of this study? Tousif Sultan: The challenging aspect, ponatinib is a kinase inhibitor and that was surprising for us how it's activating immune cells. Generally kinase inhibitors, inhibits all the cells like that. So that was challenging. So we repeated it many times did in vitro experiment to confirm that. So we just added, just treated in vitro immune cells with the ponatinib and confirmed it. So that was little challenging. Cindy St. Hilaire: So what's next? You mentioned you're going to try some clinical trials, early stage clinical trials. What's next mechanistically, what do you want to go after? Hind Lal: So what we are doing next and we are very, very eagerly trying to do that. So what it was done, we used the cardiac comorbidity models, but as you know, anybody who will take ponatinib will have cancer, right? So we strongly believe that we miss one factor. There was no cancer on these. So that is very logical next step. What that will allow us to do, what rescue experiment we'll have done in this paper. So we saw, "Okay, this rescue the cardiac phenotype, which is taken care of now," but very same time, we not able to demonstrate that this is happening without hurting the cancer efficacy. So if we have the dual comorbid mouse, which have CML a real thing and we have cardiac thing, then that will allow us to demonstrate, "Okay, we got something that can take care of the cardiac problem without hurting the efficacy on the cancer." And it will be best if you also help little bit to more potentiate the cancer efficacy. Cindy St. Hilaire: Yes. Excellent. Well, congratulations on a beautiful study, really exciting findings. Dr Lal and Dr Sultan, thank you so much for taking the time to talk with me today. Tousif Sultan: Thank you so much. Hind Lal: Well thank you, Cynthia. We really appreciate your time. Thank you for having us. Cindy St. Hilaire: Yeah, it was great. Cindy St. Hilaire: That's it for our highlights from the February 3rd and February 17th issues of Circulation Research. Thank you so much for listening. Please check out the Circulation Research Facebook page and follow us on Twitter and Instagram with the handle @CircRes and #DiscoverCircRes. Thank you to our guests, Dr Hind Lal and Dr Tousif Sultan. This podcast is produced by Ishara Ratnayake, edited by Melissa Stoner and supported by the editorial team at Circulation Research. Some of the copy text for the highlighted articles was provided by Ruth Williams. I'm your host, Dr Cynthia St. Hilaire, and this is Discover CircRes, you're on-the-go source for most exciting discoveries in basic cardiovascular research. This program is copyright of the American Heart Association 2023. And the opinions expressed by the speakers in this podcast are their own and not necessarily those of the editors or of the American Heart Association. For more information, please visit ahajournals.org.
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.02.15.528710v1?rss=1 Authors: Ruiz-Uribe, N. E., Bracko, O., Swallow, M., Omurzakov, A., Dash, S., Uchida, H., Xiang, D., Haft-Javaherian, M., Falkenhain, K., Lamont, M. E., Ali, M., Njiru, B. N., Chang, H.-Y., Tan, A. Y., Xiang, J. Z., Iadecola, C., Park, L., Sanchez, T., Nishimura, N., Schaffer, C. B. Abstract: INTRODUCTIONIn this study, we explore the role of oxidative stress produced by NOX2-containing NADPH oxidase as a molecular mechanism causing capillary stalling and cerebral blood flow deficits in the APP/PS1 mouse model of AD. METHODSWe inhibited NOX2 in APP/PS1 mice by administering a 10 mg/kg dose of the peptide inhibitor gp91-ds-tat i.p., for two weeks. We used in vivo two-photon imaging to measure capillary stalling, penetrating arteriole flow, and vascular inflammation. We also characterized short-term memory function and gene expression changes in cerebral microvessels. RESULTSWe found that after NOX2 inhibition capillary stalling, as well as parenchymal and vascular inflammation, were significantly reduced. In addition, we found a significant increase in penetrating arteriole flow, followed by an improvement in short-term memory, and downregulation of inflammatory gene expression pathways. DISCUSSIONOxidative stress is a major mechanism leading to microvascular dysfunction in AD, and represents an important therapeutic target. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC
Tis the time of year when mischief is managed and chaos is controlled! It's NCAA Championship season accompanied by the priming of the professional season. Some times and marks are indicators and some are just numbers on a line. Which of the two do the tiles think are interesting? Which of the marks do the tiles think are irrelevant??? Tune in to see Would you rather with Sir Lucious and which of the scenarios does he say NOx2 for... Safe travels to those heading to Eugene and to everyone else, enjoy the time and activities in front of you! Want to have an exploratory conversation about YOUR track equipment needs? Connect with us: Host Mike Cunningham on Twitter: @mikecunningham Email: sales@gillathletics.com Phone: 800-637-3090 Twitter: @GillAthletics Instagram: @GillAthletics1918 Facebook: facebook.com/gillathletics LinkedIn: linkedin.com/company/gillathletics/
In this week's episode we'll discuss an undescribed role for NOX2 in maintaining lung homeostasis through suppression of alveolar macrophage activation. We'll also cover results of a phase 3 randomized trial that compares the safety and efficacy of hydroxyurea and peginterferon alfa-2a in patients with high-risk polycythemia vera and essential thrombocythemia (or PV and ET, respectively). Finally, we'll go more in depth on the emerging treatment landscape for PV, and the limits of current clinical trial endpoints.
This week’s episode includes author Finnian Mc Causland and Associate Editor Justin Ezekowitz as they discuss angiotensin-neprilysin inhibition and renal outcomes in heart failure with preserved ejection fraction. TRANSCRIPT BELOW Dr Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to The Journal and its editors. I'm Dr Carolyn Lam, Associate Editor from the National Heart Center and Duke National University of Singapore. Dr Greg Hundley: And I'm Greg Hundley Associate Editor, director of the Pauley Heart Center at VCU Health in Richmond, Virginia. Dr Carolyn Lam: Greg, we're going to be talking about RNEs and renal outcomes in HFpEF. Oh, you got to hold me back this is going to be such an interesting discussion. But maybe let's grab our coffees. Are you ready to talk about some of the papers in today's issue? Dr Greg Hundley: You bet. Dr Carolyn Lam: Well the first paper I have really represents a novel gene therapy approach to atrial fibrillation. So doctors led by Dr Arora from Northwestern University Feinberg School of Medicine and colleagues used a novel gene therapy approach in a canine rapid atrial pacing model of atrial fibrillation to demonstrate that NADPH oxidase-2 or NOX2 generated oxidative injury by causing upregulation of a constitutively active form of acetylcholine-dependent potassium current, or IKH is an important mechanism underlying electrical remodeling in the fibrillating atrium. Dr Greg Hundley: Wow, Carolyn, very interesting. Tell us a little bit more about this gene therapy approach. Dr Carolyn Lam: They performed targeted expression of anti-NOX2 short hairpin RNA in the intact atria of the dogs, and then subjected those animals to rapid atrial pacing for a period of several weeks to months. The novel atrial gene therapy approach prevented the development of electrical remodeling and sustained atrial fibrillation thus demonstrating for the first time a clearer causative role for NOX2 generated oxidative injury in the creation, as well as the maintenance of electrical remodeling in atrial fibrillation. Furthermore, they demonstrate that a likely cellular and molecular mechanism by which oxidative injury created a vulnerable substrate for atrial fibrillation, the results of this study yield therefore valuable mechanistic insights into the pathogenesis of atrial fibrillation and have important therapeutic implications for this clinical management. Dr Greg Hundley: Very nice, Carolyn. We need more therapies for AFib. Boy, that's so informative. Well, the next paper that I have sort of merges the world of electrophysiology with the world of imaging and it comes to us from Dr Michela Casella from Centro Cardiologico Monzino. Among 162 consecutive patients, this study evaluated the combined utility of electroanatomic voltage mapping coupled with cardiovascular magnetic resonance imaging to guide endomyocardial biopsies. Dr Carolyn Lam: Oh, so interesting. A combined noninvasive and invasive electrical guide to perform cardiac biopsies, wow. So what did they find Greg? Dr Greg Hundley: So they found that the sensitivity of pooled electroanatomic voltage mapping and cardiovascular magnetic resonance was as high as 95%. EVM and CMR together conferred an endomyocardial biopsy positive predictive value of 89%. Endomyocardial biopsy analysis allowed to reach a new diagnosis different from the suspected diagnosis in 39% of patients, complication rates were low, mostly vascular access related, with no patients requiring urgent management. Most impressive for this manuscript are the illustrative figures that are provided. It's really a great article for those performing biopsies, doing imaging, or the EP procedures that guide the biopsy process. Dr Carolyn Lam: Really nice, Greg, thanks. Now for the last paper, have you ever thought about atherosclerosis as an autoimmune disease? Dr Greg Hundley: Well, I wonder, we're learning so much about our immune systems these days, perhaps. Dr Carolyn Lam: Indeed, throughout the inflammatory response that accompanies atherosclerosis auto-reactive CD4 positive T helper cells do accumulate in the atherosclerotic plaque. Apolipoprotein B-100 or Apo B is the core protein of LDL really serves as the auto antigen that drives the generation of pathogenic T helper one cells with pro inflammatory cytokine secretion. Yet there may also exist Apo B specific CD4 positive T cells with an athero protective regulatory T cell phenotype in healthy individuals. And that relationship between the protective Apo B reactive T regulatory cells and the pathogenic T helper one cells really has remained unknown until today's paper. And this is from Dr Ley from the La Jolla Institute for Immunology and colleagues is really the first report to characterize CD4 positive T cells recognizing Apo B in the mouse with a combination of a novel MHC II tetramer and single cell transcriptomics immuno receptor sequencing and functional evaluation, and their results demonstrated an unexpected mixed phenotype of Apo B reactive auto-immune T cells in atherosclerosis and suggest an initially protective auto immune response against Apo B with a progressive derangement in clinical disease. These findings really identify Apo B auto-reactive T regulatory cells as a novel cellular target in atherosclerosis. Dr Greg Hundley: Very nice Carolyn, boy that was a beautiful summary. I've got in the mail bag just a couple of things to talk about before you get to the discussion of some research letters. There's an ECG challenge from Dr Gunaseelan involving a young patient with chest pain. And then Theresa Wang has a very nice case series involving pulmonary hypertension, entitled Pressures at an All Time High. Dr Carolyn Lam: There's also an On My Mind piece by Dr Perman on overcoming fears to save lives. So COVID-19 and the threat to bystanders CPR in out-of-hospital cardiac arrest. There's a research letter by Dr Myhre on cardiovascular hospitalizations, influenza activity, and COVID-19 measures, another by Dr Gurbel on the first inhuman experience with inhaled acetylsalicylic acid for immediate platelet inhibition, the comparison with chewed and swallowed acetylsalicylic acid. A final research letter by Dr Zurek rounds us up regarding neuregulin one inducing cardiac hypertrophy and impaired cardiac performance in post myocardial infarction rats, very surprising because we thought this was protected. So there you have it for this issue, Greg, shall we go on to our future discussion? Dr Greg Hundley: Absolutely. Dr Carolyn Lam: In patients with heart failure, chronic kidney disease is really common and associated with a higher risk of renal events than in patients without chronic kidney disease. In fact, these renal events are really increasing in prominence in the heart failure literature. And so I'm really welcoming the discussion of today's feature paper, which looks at the renal effects of angiotensin neprilysin inhibition in patients with heart failure with preserved ejection fraction in the PARAGON trial. I'm so pleased to have with us the first and corresponding author of this paper, Dr Finnian Mc Causland from Brigham and Women's hospital, as well as our associate editor Dr Justin Ezekowitz from University of Alberta. Finnian, congratulations on this beautiful paper. Could you please tell us a little bit about the overview? What motivated it, what you found? Dr Finnian Mc Causland: It's long been a passion of mine to look at this interaction or intersection between cardiology and renal events. And if the truth be told, I had a moment in my life where I thought about being a cardiologist but I was swayed in other directions during my training in Ireland. Well, I've always been very much interested in this intersection, like I said, and so I've had the opportunity to work very closely with Scott Solomon and others at the Brigham who lead many of the heart failure trials that you are all aware of much more than I have been. And this particular subset of patients with heart failure with preserved ejection fraction is a very unique population that were studied in the PARAGON-HF trial. And we thought it was a unique opportunity to look at some of the pre-specified secondary end points, which were the renal outcomes in terms of trying to figure out what the effect of this was compared to valsartan therapy in this patient population. So I think looking at this intersection between heart failure and preserved ejection fraction and the deterioration of kidney function was the primary driver to look at this in the PARAGON heart failure trial, and to really look at the comparison between sacubitril-valsartan with valsartan in this patient population. Dr Carolyn Lam: Indeed, thanks so much Finnian, and here's a confession too. I really liked nephrology during my training. (laughs) I thought it was really cool and with all the interventions, and so I really admire the many things you think about, especially in these patients, who've got multisystem disease, but okay. Moving on with PARAGON, I know that the secondary outcomes were reported and it was really a striking effect on the renal events. And so glad that you're shedding more light in it. Could you tell us what this paper added? Dr Finnian Mc Causland: Yeah, so here we really got into I suppose the depths of the renal composite outcome and just to remind everybody that was a composite of a 50% or greater decline in eGFR, the development of end stage renal disease, or death from renal causes, so this was the composite outcome that was examined. We really evaluated this in a lot more detailed breaking our composite down into its individual components, as well as looking at it in totality. And I think the big take away point was that we found there was an almost 50% reduction in this primary renal composite outcome for patients on sacubitril-valsartan compared with valsartan. Dr Carolyn Lam: And what about the components and the sort of further analyses? Dr Finnian Mc Causland: Yeah, so getting into the, I suppose the details in a little bit more granularity, the major driver of those events will be 50% or greater decline in eGFR. And that's where the majority of these events really came from over the follow-up of PARAGON. And so this was assessed that various study business throughout the course of the few years that the patients followed up with PARAGON. And I think if we look at this slope and this was clarified in terms of the overall slope analyses of the eGFR. And we thought this relatively early separation in favor of sacubitril-valsartan so that there was less decline in eGFR over time compared with valsartan. So I think this was a supportive finding from the slope analysis that really got to this 50% threshold and that many people have examined in greater detail than they had the cardiovascular literature. So it takes a fair degree of kidney function decline to really reach that threshold of 50%. And so I think this was a very repulsed finding supported by the slope analyses. Dr Carolyn Lam: Yeah, and to the audience that's listening, you have to grab hold of figure three of this paper, and that shows the eGFR slopes, which is something that's I think really important in current heart failure literature, the concept of the eGFR decline. So really nice work. Congratulations again, Finnian. Justin, could you put these findings in context for us? Dr Justin Ezekowitz: Finnian once again, congratulations on getting this analysis. Pretty complex area to try to analyze and analyze properly, given that there's an expansive renal literature out there about looking at eGFR and how you look at it. So I think there's a couple of questions that come to mind when we think about the PARAGON trial overall. When we think about the protection of the kidneys over three, four, five years, my sense was from your analysis and perhaps you could expand on it is there seems to be very few events in those people with pretty preserved eGFR, but a greater number of events in those less than 60 mils per minute, and I'm wondering if you think that there's more of a unique place for medications such as sacubitril-valsartan and that cohort and if so is it really, that's where all the action is, but there's no real difference? Or do you think there's an interaction there that we should explore? Dr Finnian Mc Causland: Thinking back to the entry criteria for PARAGON-HF, one had to have an eGFR more than 30 mils per minute at baseline. And you had to go through this kind of complex running period where you didn't have elevations of creatinine or potassium that went inside the pre-specified ranges. So after you took that element of what many people would consider hemodynamic changes, acute hemodynamic changes out of it, you were left with participants who entered the double blind randomized period. And there, I think that's where again, we started to kind of see most of the end points in terms of follow-up, which again were mostly the eGFR decline. If you go to table two of the paper, you'll see the composite, the components of the renal composite broken out into those with eGFRs of less than 60 or 60 or greater at baseline. And even in both groups, I think you'll find that again they were both driven by the 50% decline, but you only really saw the end stage renal disease events or very few deaths from renal causes in those with eGFR of less than 60 mils per minute of baseline. And I think really what that speaks to is that these are the patients with quote unquote, chronic kidney disease at baseline are the ones who have that detrimenting kidney function to begin with. And so we're more likely to progress as we know than those with more preserved kidney function. And so if you followed patients both for really good kidney function over time, it's going to take a long time before they get that really severe decline due to the compensating mechanisms that the kidney has to preserve eGFR in the face of decline. So I think once you get into the more advanced disease, you really start to see the deterioration where there's very little renal functional reserve to cope with any additional damage or hemodynamic changes. So to me, it wasn't particularly surprising that that's where the action was. To answer your second point of should we be focusing therapy here? If you look at the median eGFR in the PARAGON heart failure study was around 63 mils per minute. So about half of these patients I suppose could be classified as having impaired kidney function. If you look at it by CKD criteria it's eGFR of less than 60. And so I think there's a huge opportunity there to really think about this population in terms of trying to look for interventional studies and potentially protect patients as we've seen with this molecule, and but also with others such as SGLT-2 inhibitors, what I'm really intrigued about is if this was persistent at eGFRs below 30, because of course, one of the most devastating icons for patients with kidney disease that we deal with is the development of end stage renal disease and those who go on to hemodialysis. So if there was some mechanism to prevent those even higher risk patients from progressing, I think that would be a huge opportunity for further research in this area. Dr Justin Ezekowitz: Thanks for that very complete and thorough answer Finnian, and that actually maybe leads to putting this in context for the majority of people who will read Circulation and the audience will most likely be cardiovascular specialists and understand a lot of what you said, but could you put this in context with other studies that really are nearby to this trial, such as CREDENCE where the eGFR slope might be slightly different, or even the UK HARP-III trial where the same molecule was used, but in a different population, I wonder if you could give us some context for these findings. Dr Finnian Mc Causland: Sure, yeah. I mean, I think the UK HARP-III trial maybe is the first one to discuss since this was a comparison of sacubitril-valsartan versus irbesartan. This was a study performed in the United Kingdom and they recruited patients with chronic kidney disease, a small proportion of those patients had heart failure, but this was not any of the pre-specified entry criteria for this study. And their primary outcome was the change in measured glomerular filtration rate after 12 months. And really they found that there was no significant difference at the 12 month mark between sacubitril-valsartan versus irbesartan. And so we were asked a similar question when we presented this study in abstract form at the American Society of Nephrology meeting in Washington last year. And I think a lot of the differences potentially relate to the difference in entry criteria for the patients. But also one might argue that 12 months of follow-up may not have been enough to see these differences in eGFR slope, which tend to occur, I suppose, rather later in the course of progressive kidney disease and heart failure. And so that may be part of the reason that we didn't see the differences with UK HARP-III. In terms of CREDENCE, obviously it's a different molecule. And if you look at our main eGFR decline over time in PARAGON-HF, it was around 0.7 mils per minute, per 1.7, three meters squared per year. And so this compares with the about 1.5 mils per minute in CREDENCE, remember CREDENCE recruited patients with chronic kidney disease. PARAGON-HF recruited patients with heart failure and preserved ejection fraction. So differences in terms of the inclusion criteria right off the bat. I think other big differences where the CREDENCE compared, and it kind of flows in versus placebo, there was an active comparator in PARAGON-HF in terms of it was sacubitril-valsartan versus valsartan. So we saw differences in eGFR slope, despite an active comparator, I think was also quite telling and that there appears to be some additional renal benefit in the additional sacubitril versus blast inhibition alone. And so I think the mechanisms is a whole other area, right? For research, I don't think we're entirely clear of the underlying mechanisms of this potential renal benefit, but I think we're pretty excited in the kidney community. Where now we have several molecules that may have potential to slow kidney functional decline, SGLT-2 inhibitors being one class potentially sacubitril-valsartan in another, and the top line results from their number are just out as well. And so there's ongoing trials that are looking at kidney function outcomes there. So we're getting pretty excited and we're not quite as jealous of the cardiology community as we used to be. Dr Carolyn Lam: I couldn't think of a better way to summarize those findings and to put it into context of other very hopeful medications for the cardio renal outcomes. Thank you so much Finnian for joining us today and for publishing such a great paper with us at Circulation. And thank you, Justin, for your perspectives. Dr Justin Ezekowitz: Thanks Carolyn, and Finnian congrats to your team as well. This has been a terrific paper to be able to handle and read and look at figure three, and it tells a lot of the story of what you saw. Dr Finnian Mc Causland: Thank you very much again for the opportunity and a big shout out to everybody that worked in PARAGON-HF and especially to the support from Scott Solomon and John McMurray for getting me involved. It's a pleasure to be part of this. Dr Carolyn Lam: Thank you so much from Greg and I for joining us today, tune in again, next week. Dr Greg Hundley: This program is copyright of the American Heart Association 2020.
Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.12.248492v1?rss=1 Authors: Malkov, A., Popova, I., Ivanov, A., Jang, S.-S., Yoon, S. Y., Osipov, A., Huang, Y., Zilberter, Y., Zilberter, M. Abstract: A paramount driver of sporadic Alzheimer's disease (AD) is the synergy of oxidative stress and glucose hypometabolism in the brain. Oxidative stress damages cellular macromolecules such as DNA, lipids and proteins, whereas glucose hypometabolism impairs cellular energy supply and antioxidant defence; Together, these cellular and functional alterations may be primary triggers of AD. However, the exact molecular basis of AD-associated glucose hypometabolism has remained unknown, hampering the search for effective interventions. Here, we identify NADPH oxidase 2 (NOX2) activation by beta-amyloid peptide (A{beta}1-42) as the main molecular source of oxidative stress driving brain glucose hypometabolism and network hyperactivity. Using a combination of electrophysiology with dynamic recordings of autofluorescence and metabolic biosensors, we show that in hippocampal brain slices, A{beta}1-42 application reduced network activity-driven glucose consumption and glycolysis by half, while NOX2 antagonism prevented this effect. In vivo, intracerebroventricular injection of A{beta}1-42 exerted a profound inhibitory effect on brain glucose consumption, resulting in long-lasting network hyperactivity and changes in animal behavioral profile. Critically, the novel bioavailable NOX2 antagonist GSK2795039 prevented all of the observed A{beta}-related detrimental effects. These data suggest that targeting NOX2-induced oxidative stress is a promising approach to both the prevention and treatment of AD. Copy rights belong to original authors. Visit the link for more info
This month on Episode 12 of the Discover CircRes podcast, host Cindy St. Hilaire highlights three featured articles from the May 8 issue of Circulation Research and gives listeners an inside scoop of the cutting edge ideas in the May 22nd Compendium on Obesity. This episode also features an in-depth conversation with Dr Eduardo Marbán concerning COVID-19 and its effects on the heart. Article highlights: Roberts et al. LYN Regulates Monocyte Heterogeneity and Lifespan Lu, et al. Acute Hyperglycemia Activates CaMKII-ROS Pathway Yan, et al. Epicardium and Atrial Cardiomyopathy Transcript Dr 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. Today, I'm going to share with you articles selected from the May 8th issue of Circulation Research as well as give you a hint at the cutting-edge ideas in the May 22nd Compendium on Obesity. We'll also have discussion with Dr Eduardo Marbán from the Smidt Heart Institute at Cedar Sinai Medical Center about his Review on COVID-19 and its effects on heart. So, first the highlights. The first article I'm sharing with you is titled Deep Phenotyping by Mass Cytometry and Single Cell RNA Sequencing reveals LYN Regulated Signaling Profiles Underlying Monocyte Subset Heterogeneity and Lifespan. The first authors are Morgan Roberts and Maunish Barvalia and the corresponding author is Kenneth Harder and they're from the University of British Columbia. Monocytes can be separated into two main groups, conventional monocytes which enter tissues from the bloodstream and differentiate into macrophages, and patrolling monocytes, which developed from conventional monocytes but tend to remain in the blood vessel walls where they can scavenge cells and tissue debris. It's thought that patrolling monocytes help to prevent a range of diseases like atherosclerosis by helping to clean up the vessel walls. Studies in mice harboring genetic mutations in a gene called Nr4a1 cause mice to have less than normal numbers of patrolling monocytes. In these mice, the development of atherosclerosis is exacerbated. In addition to Nr4a1, this group has now identified another factor regulating the survival of patrolling monocytes, the tyrosine kinase LYN, L-Y-N. Genetic deficiency of LYN caused the upregulation of Nr4a1 and other genes involved in patrolling monocytes development and survival. This in turn led to the accumulation of patrolling monocytes in the blood, also in the bone marrow, spleen, and the aorta. Loss of LYN was also protective against atherosclerosis in mouse models of this disease. These results not only provide novel insights into patrolling monocyte biology, but also suggest that targeting LYN could offer novel treatments for diseases like atherosclerosis, where boosting the patrolling monocyte numbers could be beneficial. The second article I want to highlight is titled Hyperglycemia Acutely Increases Cytosolic Reactive Oxygen Species via O-linked GlcNAcylation and CaMKII Activation in Mouse Ventricular Myocytes. The first author is Shan Lu and the corresponding author is Don Bers, and they're from the University of California, Davis. Diabetes affects more than 400 million people worldwide and puts these individuals at a higher risk for developing heart failure. When heart failure does occur, the outcomes for these patients with diabetes are likely to be far worse than for individuals without the diabetic condition. Both heart failure and diabetes have been associated with excessive production of reactive oxygen species and also with increased activation of a protein kinase in the cells of the heart called CaMKII. Both ROS and CaMKII are induced by hypoglycemia, where there is an increased amount of extracellular glucose levels in the blood. This study shows that reactive oxygen species in CaMKII are causally linked. When CaMKII was inhibited or genetically deleted in mouse cardiomyocytes, high extracellular glucose levels were unable to induce reactive oxygen species production, which is what would normally occur. The team also discovered that O-GlcNAcylation post-translational modification of CaMKII is induced by the extracellular glucose and this modification is necessary for the enzyme's reactive oxygen species- boosting effects. Lastly, they found that the enzyme NADPH oxidase 2 or NOX2 was the source of this CaMKII induced reactive oxygen species. This work uncovers the molecular pathway linking hyperglycemia, cardiomyocyte-damaging reactive oxygen species production, and it helps explain why heart failure pathology is exacerbated in diabetic patients. The next article I want to share with you is Reactivation of the Epicardium at the Origin of Myocardial Fibro-Fatty Infiltration During the Atrial Cardiomyopathy. The first author is Nadine Suffee and the corresponding author is Stéphane Hatem and they're from Inserm in Montpellier, France. Fatty tissue surrounding the heart is linked to an increased risk for atrial fibrillation, which is the most common form of arrhythmia. It seems that a combination of fat cells, which are called adipocytes and the fibroblast localized within the heart's epicardium, builds up and expand into the subepicardial layers, and this is a feature that is called fibro-fatty infiltration. These fibro-fatty infiltrations cause disturbances to the electrical rhythms that regulate the heart beating. Although generally quiescent in the adult heart, epicardial cells possess the ability to proliferate and have been shown that they harbor the ability to differentiate into adipocytes and fibroblast. This team hypothesized that the epicardial cells were the source of the damaging fibro-fatty infiltrations. Sure enough, when they looked at human heart sections, they found that within the epicardial layer, there were cells that were expressing fibroblast and adipocyte progenitor cell markers. In culture, these epicardial cells with fibroblast progenitor markers could be differentiated into fibroblasts by treatment with angiotensin II and cells with the adipocyte progenitor markers could be differentiated into adipocytes by treatment with atrial natriuretic peptide. The team also showed that these epicardial fibro-fatty infiltrations occurred in a mouse model of atrial cardiomyopathy. Together this work highlights the pathogenesis of epicardial fibro-fatty infiltrations and suggest a novel model in which to study its progression to AFib. The last thing I want to share with you before we switch to our interview with Dr Marbán is that the May 22nd issue of Circulation Research is our Obesity Compendium. Obesity is a major threat to cardiovascular health worldwide. While early studies focused on body mass index as a generalized measure of obesity and focused on the BMIs relation to cardiovascular disease, studies within the last decade have now tried to more fully understand adipose tissue physiology and the overall impact of obesity on cardiovascular disease. The articles in this compendium are obesity phenotypes, diabetes and cardiovascular diseases, basic mechanisms of diabetic heart disease, leukocyte heterogeneity and adipose tissue including obesity, an eclectic cast of cellular actors orchestrates innate immune responses and the mechanisms driving obesity and the metabolic perturbation, metabolic inflammation and insulin resistance in obesity, genetic insights into the relationship between Type 2 diabetes and coronary heart disease, metabolomics and proteomics in Type 2 diabetes, metabolic and molecular imaging in diabetic cardiomyopathy and treatment of obesity and mitigating metabolic risk. This compendium reflects the collective work of leading investigators in the space of diabetes, cardiometabolic disease, and cardiovascular disease with the ultimate goal of providing a summary of selected aspects of obesity and metabolic physiology central to cardiovascular disease development. So, I have with me here today, Dr Eduardo Marbán, the founder of the Smidt Heart Institute at Cedars-Sinai Medical Center in Los Angeles, California. He's a leading physician scientist in the fields of electrophysiology, cardiac progenitor cells, and next generation cell-free therapeutics. Dr Marbán, thank you very much for taking the time out of your busy schedule to speak with us today about your article COVID-19 and the Heart, which is now freely available on the Circulation Research webpage. Dr Eduardo Marbán: It's my pleasure to talk to you Cynthia. Dr Cindy St. Hilaire: First off, how are you and how are things at your hospital center in LA? Dr Eduardo Marbán: We seem to have dodged the bullet here in the sense that we were pretty progressive in terms of quarantine and stay at home orders. Given that, we seem to have peaked at a level that is very manageable in terms of our surge capacity. So, we feel for those who are worse off, but at least knock on wood here, we seem to be surviving so far. Dr Cindy St. Hilaire: Yeah, that's similar to how we are in Pittsburgh. We shut down about the same time that Philadelphia, who was already surging was shutting down. So, we are feeling safe but still prepared. So, I was extremely excited to read this article because as we know, cardiac injury is happening in between 20% to 30% of the COVID-19 patients and cardiac injury is also the cause of about 40% of the COVID-19 related deaths. So, my first question is, what are the types of cardiac injuries or events that you're seeing in these COVID-19 patients and are there any particular characteristics that the subpopulation of patients shares that's different from non-cardiac injury COVID patients? Dr Eduardo Marbán: What seems to be extremely common in COVID-19 patients is elevations of circulating biomarkers, things like troponin I, troponin T, BNP as an indicator of heart failure, but what's much less certain is whether these biomarker elevations have any clinical significance. At the level of isolated case reports, there's fulminant myocarditis, ventricular tachycardia, arrhythmias, occasional acute coronary syndromes, but there seems to be a disconnect between the almost ubiquitous nature of the circulating biomarker elevations and the relative rarity of clinical events. Dr Cindy St. Hilaire: So, do these patients, do a majority of them have a history of cardiovascular disease or is this all new developments? Do we know? Dr Eduardo Marbán: Underlying cardiovascular disease, diabetes, hypertension, and recently obesity and, of course age, have all been implicated as general risk factors for being critically ill with COVID, but there's no specific indication epidemiologically yet that those with underlying cardiovascular disease have a particular predilection to manifesting worse heart symptoms or signs during COVID-19. It makes sense that that would be the case, but so far, the epidemiology is somewhat more general. Dr Cindy St. Hilaire: When you were first writing this article, I'm sure between then and now we even have more epidemiological data points that are constantly changing. Dr Eduardo Marbán: Since the article was published online on April 7th, I've given four updated versions of the webinar to various audiences. Every time we do so, the slides need to change subtly. It's a very rapidly evolving field. Dr Cindy St. Hilaire: Yeah, that's amazing. In the first SARS outbreak, which was in 2002-2003, scientists discovered that this type of Coronavirus enters the cell by binding to angiotensin converting enzyme II as a receptor. So, ACE2 as it's called. It's not a receptor in the canonical sense of the word, but it's a cell surface enzyme and it's involved in the renin angiotensin aldosterone system, which regulates a handful of cardiovascular homeostatic processes and is quite frankly, rather complicated. So, I don't want to talk specifically about that, but I'm wondering if you could tell us a little bit about what ACE2 is, what cells it's found on, and what that might mean for the implications of this virus and its effects on the cardiovascular system? Dr Eduardo Marbán: Well as you correctly stated, ACE2 is central to cardiac physiology in the sense that it creates the bioactive form of angiotensin. In so doing, its regulation is central to that of blood pressure, human dynamics. What is less appreciated and to me was a bit of a revelation is the fact that it's expressed fairly richly on the surface of epithelial cells of the lung and the SARS-CoV virus family seems to have co-opted the presence of that in order to create a handy sort of hook to get into the cells in the first place. Whether there are broader ranging implications of ACE2 other than the particular mode of entry into the cell for a viral infection is a topic of great speculation at this point. Dr Cindy St. Hilaire: Yeah. In some of my preparation for this and also just my curiosity regarding this virus and the vascular system, when you look at things like the human protein atlas, you can see that ACE2 is highly expressed, not only on the lung epithelial like you say, but they're also expressed on cardiovascular cells in nearly all of the tissue. I'm thinking of cells like the smooth muscle cell and the endothelial cell. Is the virus binding to ACE2 positive cells part of the reason for the cardiac events or these cardiac events secondary to systemic toxicity? So, I guess the real question is, do we know anything about the direct versus the indirect effects of the virus on the heart? Dr Eduardo Marbán: No question in vitro that SARS-CoV can infect cardiac myocytes and most surely almost any other cell that expresses these two on its surface. In vivo, how frequently that happens as opposed to triggering secondary cardiac damage due to the systemic inflammation is uncertain, but I can tell you from the various case reports that have actually analyzed human tissue either at autopsy or an endomyocardial biopsy in cases of fulminant myocarditis, the frequency of direct viral infection seen either by culturing viral particles or more frequently by electron microscopy and visualization of inclusion bodies within cells points to perhaps a third of the cases being due to direct infection and two thirds of the cases likely being due to some bystander effect of systemic inflammation. Dr Cindy St. Hilaire: Interesting. So, are the phenotypes different between those patients where it seems to be direct versus indirect? Does the myocarditis appear similar or the cytokine profiles, anything like that? Dr Eduardo Marbán: There are too few patients to make really good conclusions about whether or not the phenotypes differ greatly when there's direct versus indirect cardiac involvement, but certainly from the literature as it exists now, there's no reason to believe that we could outsmart the clinical picture. They all look pretty much the same from the bedside. Dr Cindy St. Hilaire: So from the first SARS outbreak, do we know anything about the long-term effects of this type of viral infection on the cardiovascular system or on the heart specifically? Dr Eduardo Marbán: Yeah. COVID-19 of course the follow-up is limited to a few months since the first cases probably didn't emerge until late October early November and weren't really recognized as such until late '19 early 2020, but for SARS from the 2002-2003 epidemic, some of the long lasting sequelae are unanticipated and include hypertension, hyperlipidemia, pulmonary fibrosis, avascular necrosis. So, it seems that even when a patient is out of the woods, perhaps they're not really out of the woods in terms of long-term sequelae. We need to be watchful for long-term sequelae in COVID-19 survivors. They're going to be many more of them than there were from the SARS epidemic. Dr Cindy St. Hilaire: So, one of the things that's come out recently, which I've been really mulling about because my background is vascular biology and specifically smooth muscle cells and endothelial cells, but one of the findings is about the later stage or more sick patients. These are patients who are going on ventilators and about 50% of them going on the ventilators are dying and/or just not responding to ventilator therapy as doctors expect. So, just to give a little background about ventilators, they're normally used when a patient's blood oxygen level drops too low. So, normal levels are between 95% and 100%. However, patients with pneumonia or acute respiratory symptoms are put on ventilators sometimes when their oxygen drops below 90%, but some of the COVID-19 patients are exhibiting blood oxygen levels at 70% or sometimes even lower, but they don't have outward signs of distress and they can still hold conversations. So, I'm wondering if you can give me any insight into possibly what's going on there with the lens of vascular remodeling, what might be happening to the vasculature in the lung that is unique to this ventilator response and COVID response? Dr Eduardo Marbán: The observation you described is common that sometimes a patient will be profoundly hypoxemic but chatting away or surfing the internet as if nothing were happening. We're not used to seeing this in other cases of ARDS or viral sepsis where the patient usually is in extremis by the time the blood oxygen levels get that low. It begs the question as to whether perhaps there's something about the cerebral circulation, and this is complete and rampant speculation. Whether there's something about the cerebral circulation that makes it somewhat resistant to the effects of systemic hypoxia, perhaps there's a compensatory vasodilation that occurs that compensates for the otherwise deadly systemic hypoxemia. It would be quite interesting to monitor oxygen tensions within the cerebral parenchyma to test that, but all I can say with any certainty right now is that the clinical observation is robust. We see this not infrequently in patients who in the sort of clinical jargon have no right to look that good. Dr Cindy St. Hilaire: Yeah. Yeah. It's like your numbers, you really have those numbers? Yeah. There's just so many questions. It's really unprecedented. So, I guess we've been talking a lot about the disease itself and the symptoms and the pathogenesis, but I want to switch to ask about potential therapies. There's been several therapies that have been suggested by a variety of people and there's, I don't even know how many clinical trials. I looked a week ago and there's really a great response of pharmaceutical companies and university hospital systems trying what they can with the tools they have. So, things like antivirals, HIV protease inhibitors, inhibitory antibodies, and even antimalarial drugs have been suggested that they could possibly work. So, I'm wondering if you could give us some insight from a cardiovascular standpoint, what are the potential implications or potential adverse side effects of using these different therapies off label and what might that mean for the heart in addition to treating the viral infection? Dr Eduardo Marbán: You're correct in the explosion of clinical trials in this area or at least, clinical interventions. At our IRB, as of today, there are 56 active COVID protocols. Imagine nobody even cared about COVID until mid-February, right? Dr Cindy St. Hilaire: That's just at Cedars-Sinai. Dr Eduardo Marbán: Yeah. Now, we have 56 active protocols. So, not all of those are interventional. Some of them are epidemiological or biomarker studies, but still there's an incredible plethora. You're right, the approaches of targeted anything from the viral infection to the viremia to the downstream consequences of viral infection including the hyper inflammation and cytokine storm. The rationale for anti-malarials is actually fairly thin and resides on in vitro observations that actually were just from February that SARS-CoV-2 infection in vitro is somewhat retarded by exposure to hydroxychloroquine. This didn't come out of the blue. There had been an extensive literature and quite controversial literature, I should say, that anti-malarials might be useful in influenza and other infections. In a very general sense, there was a lot of hype created by early in vitro studies, which turned out to be neutral or in some cases even harmful clinically, but this has led to an almost universal adoption of hydroxychloroquine in patients with COVID-19 coupled sometimes with the antibacterial agent azithromycin for which the rationale is even thinner. There's no reason to believe that an antibacterial per se would help in a viral infection, but azithromycin is said to have antioxidant properties, which may or may not potentiate the effects of hydroxychloroquine, but for sure what they do together is prolong repolarization of the heart and lead to a clinical syndrome known as prolonged QT, which is a known substrate for toxic arrhythmias like polymorphic ventricular tachycardia. So, in prescribing some of these agents, one needs to weigh the uncertain benefits against the very certain risk that they entail. Dr Cindy St. Hilaire: Yeah. I think that's a really important point. I think one of the scary things that has the potential of happening during this crisis is too quick of a jump to conclusions. While there is a need for as rapid a response as possible, we still need to make sure that we're taking in all the scientific information we have and that that science is good and strong. I think one of the things that you mentioned in the Review is the lack of power in some of those initial anti-malarial studies. I think it's really important thing I want to emphasize that it's an emergency, but we still need to make proper good scientific decisions. Dr Eduardo Marbán: Well, one of the problems is that hydroxychloroquine and other agents in some cases, remdesivir and you know, you choose, have gotten so popular and hyped that there's almost no possibility of being an ethical clinical trial because the patients want to be on them. So, it may be easier in some settings than in others, but it's certainly not going to be a trivial thing to sort out the true risk benefit ratio of these drugs in this illness. Dr Cindy St. Hilaire: So right now, doctors and scientists, we're all in crisis mode, but once things settled down, we could really start to sit down and think about more mechanistic questions that might be able to be tested that will really help us flush out our understanding of COVID-19 disease pathogenesis and its effects on the cardiovascular system. So, what do you see after this initial crisis is under control, what do you see as the immediate next questions that basic scientists and translational scientists need to address that can help the next time that this comes again? Dr Eduardo Marbán: First of all, it's quite clear that we've all become consumed by COVID-19 and SARS-CoV-2. We can't think of anything else often. It's really hard to even focus on work from the laboratory that doesn't have to do with SARS-CoV-2 and COVID. It's so ubiquitous in public perception and the way we're living our lives that it just makes it incredibly difficult to think about anything else. I think there's going to be a correction in which we're going to get frankly tired of SARS-CoV-2 and COVID and want to think about other things, but among the lasting questions and the ones that will have greater biological merit above and beyond how to deal with this particular virus and this particular pandemic are the following. What is the role of ACE2 in human biology? Clearly here, there's an experiment of nature in which this surface enzyme has been co-opted for viral entry and a tremendous amount of speculation surrounds the question of whether high ACE2 values are protective and detrimental and ACE inhibitors and angiotensin receptor blockers might be detrimental or beneficial. All of these fundamental mechanisms need to be sorted out and now there's motivation to do so because of the epidemic. Some of this work is easier than others and those institutions that happen to have a BSL-3 level facility for being able to directly study the effects of the virus on various tissues should do so with alacrity because it's a limited resource right now where the number of questions really far exceed the ability to answer them just physically. Another question which I think is going to be motivated by our experience with COVID-19 is that of the mechanisms of cytokine storm and hyper thrombotic states. These are things that characterize the critically ill patient with COVID-19. Dr Cindy St. Hilaire: Can you just explain what is a cytokine storm? What does that exactly mean? Dr Eduardo Marbán: So, patients who are critically ill with COVID-19 manifest a late stage of the illness, which is often fatal, in which circulating levels of various inflammatory biomarkers, interleukin 6, C-reactive protein, ferritin being among them, but basically anything that goes up in an inflammatory state. And some of these appeared not to just be markers of inflammation. Something like C-reactive protein is probably just a biomarker of inflammation, but interleukin 6 for example, is a highly bioactive cytokine that itself probably causes tremendous tissue injury and there's some enthusiasm for the use of anti IL6 antibodies and anti IL6 receptor antibodies to treat the critically ill with some anecdotal dramatic success I should say. So perhaps the cytokine storm isn't just a marker of those who are critically ill, perhaps it's causative. If that presumption is real, then it makes good sense to target the cytokine storm, but from a scientific point of view, what causes it in the first place? How does a viral infection lead to massive production of cytokines and inflammatory biomarkers and how can that be mitigated? One of the ways of dealing with that is by understanding precisely how it happens in the first place and there's not that much literature on it. There's a recent study which I found quite provocative that glucose metabolism and the whole process known as O-GlcNAcylation might actually be a trigger in the production of cytokines during viral infections like COVID-19, but I think understanding how it happens will lead to much more targeted therapeutics and perhaps enable us to eventually divorce the infection from the overreaction. Really what's happening is friendly fire. The body's immune system is turning against itself in a sort of vain effort to control the virus. Sometimes the viremia is actually almost gone by the time that these inflammatory biomarkers increase, and the cytokine storm surges. Dr Cindy St. Hilaire: So, it's almost like the inflammatory response reaches some point beyond which it doesn't need virus anymore. It is just full force feeding forward and causing more damage by itself. Dr Eduardo Marbán: Yeah, exactly. It's almost as if there's an eroding cliff and even though the river may be back down to normal levels, the cliff is still unstable and the whole hillside could come crashing down. Dr Cindy St. Hilaire: Are there long terms effects of that? I wonder how long that would last after the infection or is it only during a viral titer in the system? Dr Eduardo Marbán: Well, you raised yet another interesting question to the extent that patients who have survived SARS- CoV-2 infection develop long-term sequelae, what's the mechanism of those long-term sequelae? Why should patients who are previously well develop hyperlipidemia and hypertension after the infection, if in fact they do, so are any of these related to micro thrombotic events? It's quite conceivable. Dr Cindy St. Hilaire: Great. Well, thank you so very much for taking the time to speak with me today. I don't think I found a ton of answers. I found a lot more questions, but hopefully as this develops and we get it under control, maybe we can talk again and talk about some of those new mechanistic findings and potential therapies. Dr Eduardo Marbán: Absolutely. You're welcome, and I hope you and all the listeners stay safe during this pandemic. Dr Cindy St. Hilaire: You too, and your clinical team. That's it for highlights from the May 10th and May 22nd Obesity Compendium issues of Circulation Research. Thank you so much for listening. Please check out the Circulation Research Facebook page and follow us on Twitter and Instagram with the handle @CircRes and #DscoverCircRes. Thank you to our guest, Dr Eduardo Marbán. This podcast is produced by Rebecca McTavish, edited by Melissa Stoner, and supported by the editorial team of Circulation Research. Some of the copy text for highlighted articles is provided by Ruth Williams. I'm your host, Dr Cindy St. Hilaire, and this is Discover CircRes, your on-the-go source for the most up-to-date and exciting discoveries in basic cardiovascular research.
Dr Paul Wang: Welcome to the monthly podcast, On the Beat, for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue. In our first paper, Leroy Joseph and associates examined whether an increase in dietary saturated fat could lead to abnormalities of calcium homeostasis and heart rhythm, by an NADPH oxidase 2, NOX2-dependent mechanism. In mice on high fat diets, they found that saturated fat activates NOX, whereas polyunsaturated fat does not. The high saturated fat diet increased repolarization heterogeneity in ventricular tachycardia, VT inducibility in perfused hearts. Pharmacologic inhibition or genetic deletion of NOX2 prevented arrhythmogenic abnormalities in vivo during high saturated fat diet and resulted in less inducible VT. On the other hand, high saturated fat diet activates calcium calmodulin dependent protein kinase in the heart, which contributes to abnormal calcium handling, promoting arrhythmia. This work suggests that a molecular mechanism links cardiac metabolism to arrhythmia and it suggest that NOX2 inhibitors could be a novel therapy for heart rhythm abnormalities caused by cardiac lipid overload. In our next paper, Misha Regouski and associates examined whether the relationship between endurance exercise and atrial fibrillation, or AF, is dependent on atrial myopathy. They examined six cardiac specific TGFβ1 transgenic and six wild type goats. Pacemakers were implanted in all animals for continuous arrhythmia monitoring and AF inducibility. AF inducibility was evaluated using five separate ten second bursts of atrial pacing. At baseline sustained AF greater than 30 seconds was induced with 10 seconds of atrial pacing in 4 out of 6 transgenic goats, compared to zero out of six wild type controls, P less than 0.05. No spontaneous AF was observed at baseline, three months of progressive endurance exercise up to 90 minutes at 4.5 miles per hour was performed. The authors observed that between two to three months of exercise, three out of six transgenic animals developed self-terminating spontaneous atrial fibrillation compared to zero out of six wild type animals, (P less than 0.05). There was an increase in AF inducibility in both transgenic and wild type animals during the first two months of exercise with partial normalization at three months. These changes in AF susceptibility were associated with a decrease in circulating micro RNA 21 and micro RNA 29 during the first two months of exercise, with partial normalization three months in both transgenic and wild type animals. The authors concluded that endurance exercise appears to increase inducible AF secondary to altered expression of key profibrotic biomarkers that is independent of the presence of an atrial myopathy. In our next paper, Seokhun Yang and associates examined whether there is an association between lifetime exposure to endogenous sex hormone, and incident atrial fibrillation, or AF, in subsequent ischemic stroke. They studied nearly five million natural postmenopausal women aged 40 years or greater without prior history of AF and with breast cancer. The primary end point was incident AF and the secondary end point was subsequent ischemic stroke once AF is developed. During the mean follow up of 6.3 years, shorter total reproductive years (
Dr. Carolyn Lam: Welcome to Circulation on the Run, your weekly podcast summary and backstage pass to the journal and its editors. I'm Dr. Carolyn Lam, associate editor from the National Heart Center, and Duke National University of Singapore. Our featured paper this week confirms the clinical utility of a polygenic risk score of common variants of cardiovascular disease. More soon after this week's summary of articles. The first original article describes distinct cell-specific roles for NADPH oxidase, or Nox2, in blood pressure regulation. This paper from first author, Dr. Sag, corresponding author, Dr. Shah, colleagues from King's College London British Heart Foundation Center of Excellence in the United Kingdom. The authors used novel gene modified mouse models to show that Nox2 in myeloid cells modulates basal blood pressure whereas endothelial cell Nox2 is involved in angiotensin II-dependent hypertension. The finding that Nox2 in different cell types has distinct effects on blood pressure, suggest that different diseases conditions may alter blood pressure through effects on Nox2 in different cell types. For example, it is conceivable that the effects on myeloid cells on basal blood pressure may be enhanced in inflammatory settings, whereas endothelial cell Nox2 activation may be more relevant to renin-angiotensin system-dependent hypertension. The current results are therefore relevant to the design of novel therapeutic approaches for hypertension by targeting NADPH oxidases. The next paper provides a new, more accurate atherosclerotic cardiovascular disease risk prediction tool in familial hypercholesterolemia that may increase the efficiency of care and use of newer lipid lowering therapies. Co-corresponding authors, Dr. Mata and Pérez de Isla, from Hospital Clinicals San Carlos in Madrid, Spain, use data from SAFEHEART, a multicenter, nationwide, long-term prospective cohort study of 2,404 adult patients with molecularly-defined familial hypercholesterolemia and who have followed up for a mean of 5.5 years. They developed a robust risk prediction equation for incident atherosclerotic cardiovascular disease based on the following independent predictors; age, male gender, history of previous atherosclerotic cardiovascular disease, high blood pressure, increased body mass index, active smoking, LDL cholesterol and LPA levels. The new SAFEHEART risk equation performed better with a Harrell C index of 0.81 compared to 0.78 for the modified Framingham's risk equation and 0.8 for the ACC/AHA Pooled Cohort risk Equations. The authors therefore concluded that the risk of incident atherosclerotic cardiovascular disease may be estimated in familiar hypercholesterolemia patients, using simple clinical predictors, and that these findings may improve re-stratification and could be utilized to guide therapy in patients with familiar hypercholesterolemia. The next study tells us that late gadolinium enhancement cardiovascular magnetic residents identifies patients with dilated cardiomyopathy but without severe left ventricular systolic dysfunction, who are still at high risk of sudden cardiac death. In this study, by first author Dr. Halliday, corresponding author Dr. Pennell, from Royal Brompton Hospital in London, United Kingdom, the authors prospectively investigated the association between mid-wall late gadolinium enhancement and the primary composite outcome of sudden cardiac death or aborted sudden cardiac death, among 399 consecutive referrals with dilated cardiomyopathy and a left ventricular ejection fraction above 40% seen at their center between 2000 and 2011. These patients were followed for a median of 4.6 years. 17.8% of patients with late gadolinium enhancement reached the pre-specified end point, compared to only 2.3% without late gadolinium enhancement. Furthermore, following adjustment, late gadolinium enhancement predicted the composite end point, with a hazards ratio of 9.3. Thus, patients with dilated cardiomyopathy and mid-wall late gadolinium enhancement, and mild or moderate reductions of left ventricular ejection fraction should still be recognized as having a high risk of sudden cardiac death. This is important because these patients are not currently offered ICDs for the primary prevention of sudden cardiac death, based on current guidelines. Due to the low competing risk of death from non-sudden causes, it is possible that these patients will benefit from ICD implantation, but randomized trials are now required. These issues are discussed in an accompanying editorial from Dr. Markman of Johns Hopkins University, and Dr. Nazarian, Hospital of University of Pennsylvania. The next study enhances our understanding of the role of immunity in hypertension. Now, the innate antigen-presenting cells and adaptive immune T-cells have long been implicated in the development of hypertension, however, the T-lymphocytes subsets involved in the pathophysiology of hypertension remain unclear. A small subset of innate-like T-cells expressing the gamma-delta T-cell receptor, rather than the more commonly expressed alpha-beta T-cell receptor, could play a role, and these were the focus in today's paper by first author Dr. Caillon, corresponding author Dr. Schiffrin, and colleagues from Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Canada. In experimental models, the authors showed than angiotensin-2 infusion increased gamma-delta T-cell numbers and activation in the spleen of wall tite mice, as well as in increased the systolic blood pressure, and decreased mesentric artery endothelial function in wild type mice, but not in mice devoid of gamma-delta T-cells, or in mice depleted of gamma-delta T-cells by depleting antibody injections. Furthermore, angiotensin-2 induced T-cell activation in the spleen and peri-vascular adipose tissue was blunted in null mice. In humans, there was an association between systolic blood pressure and gamma-delta T-cells. In summary, this is the first in-vivo demonstration that gamma-delta T-cells, a subpopulation of T-cells, play a fundamental role in the development of hypertension and vascular damage. These results will help design novel treatments to limit the progression of hypertension and vascular damage. The final paper describes a novel multi-modality strategy for cardiovascular risk assessment. Dr. de Lemos and colleagues from UT Southwestern Medical Center in Dallas, Texas, hypothesized that a strategy combining promising biomarkers across multiple different testing modalities would improve global and atherosclerotic cardiovascular disease risk assessments among individuals without known cardiovascular disease. These modalities included: left ventricular hypertrophy by electrocardiogram, coronary artery calcium, N-terminal pro B-type natriuretic peptide, high sensitivity cardiac troponin-T, and high sensitivity C-reactive protein. Using data from 6,621 individuals of the multi-ethnic study of atherosclerosis, or MESA, as well as 2,202 individuals from the Dallas heart study, the authors evaluated the association of test results with the global composite cardiovascular disease outcome, and that would include cardiovascular death, myocardial infarction, stroke, coronary or periphery revascularization, incident heart failure or atrial fibrillation, as well as atherosclerotic cardiovascular disease outcomes, which included fatal or non-fatal myocardial infarction or stroke. Over more than 10 years of follow-up, the authors found that each test result was independently associated with the global composite cardiovascular disease events in MESA. When the 5 tests were added to a base model, the C statistic improved, that was significant integrated discrimination improvement, and net reclassification improvement, and the model was well-calibrated. Using a simple integer score counting the number of abnormal tests, they showed that global cardiovascular disease risk increased with increasing score in a graded fashion. These findings were replicated in the Dallas heart study, and were similar for the atherosclerotic cardiovascular disease outcome. This study therefore supports the potential value of a multi-modality testing strategy in selected individuals, in whom additional risk stratification is desired, beyond measurement of traditional atherosclerosis risk factors. The authors do highlight that additional studies are needed to validate the present findings, determine the optimal approach to implementation, and address direct and indirect cost implications of the additional testing. Well, that wraps it up for your summaries. Now for our feature discussion. Our feature paper today tells us that a polygenic risk score identifies a group of individuals with a higher burden of atherosclerosis, and greater relative benefit from statin therapy in the primary prevention setting. But perhaps even more significant, is that it addresses the fact that even relatively small effect sizes of common snips gathered together in a genetic risk score may have clinical utility in the prediction of cardiovascular disease, and to discuss this I'm so pleased to have the first author, Dr. Pradeep Natarajan from Massachusetts General Hospital, and Dr. Anand Rohatgi, associate editor from UT Southwestern. Welcome, gentlemen. Dr. Pradeep Natarajan: Thank you very much, Carolyn. Dr. Anand Rohatgi: Thank you, Carolyn. Dr. Carolyn Lam: Pradeep, could you start by telling us what you did? This was a tour de force, please. Dr. Pradeep Natarajan: Yeah, thanks so much for the invitation and the enthusiasm. So, briefly, large-scale, genome-wide association studies have discovered genetic risk variants in the population that individually associate with coronary disease risk. Many others have shown that an aggregate of these genetic risk variants predisposes to an increased risk for coronary disease by about 60%. But we sought to, with this study, understand how primary preventive statins could influence that risk, and whether these insights could be helpful in refining statin eligibility. So, among the individual variants that had been associated with coronary disease, we developed a risk score. This encapsulated 57 individual genetic variants. This risk score is independent of traditional cardiovascular risk factors, and identified individuals with a greater burden of sub-clinical atherosclerosis, defined as coronary artery calcium and carotid plaque, and two observational cohorts in individuals with a greater absolute and relative benefit from statin therapy from a subgroup analysis within the WOSCOPS clinical trial. What we were surprised by is that the conventional wisdom, that all previously described subgroups within statin trials had the same relative benefit, and statins per unit of alveol cholesterol lowering. So, about 20 to 25% lowering of risk per 40mg per deciliter of alveol cholesterol. So we clinically identify individuals who just start out at high absolute risk, assume that the relative benefit will be the same across everyone, and optimize the number needed to treat simply by just finding individuals at high risk. But, here we didn't see the expected 20 to 25% lowering in the high genetic risk group, we saw actually a 44% relative risk reduction for the same lowering of alveol cholesterol. And we have now observed that across three different clinical trials, and these individuals are at high baseline risk, so this translates into an even more optimized number needed to treat, and really the opportunity to identify individuals earlier with an age independent biomarker. Dr. Carolyn Lam: That's really cool, in fact, the number needed to treat in the high-risk score group was impressively low at 13. Dr. Pradeep Natarajan: That's correct. Now, overall in the WOSCOPS trial, if you look at all individuals, it's about 38, so it is a high risk primary preventive group of men with, you know, substantial hyperlipidemia, but if you look at at least a relative difference between the two, going from 38 to 13, that's about a three-fold improvement of the number needed to treat. Dr. Carolyn Lam: You know, what you said about it not correlating with exactly what you expected with the drop in LDL and so on, does that mean that this genetic risk score, that a lot of the snips are probably associated with LDL levels, but that a lot of them may be giving more information beyond LDL? Is that what it means? Dr. Pradeep Natarajan: Yeah, you know, it's interesting. Most of the genetic variants that are associated with coronary disease actually do not seem to clearly influence traditional cardiovascular risk factors. The latest best estimate of that is about 39% of them associate with traditional cardiovascular risk factors, and then a subset with LDL cholesterol. So the aggregate score actually does not associate with traditional risk factors, and including with LDL cholesterol. Dr. Carolyn Lam: Wow, and Anand, I'm sure we had so many discussions with the editors about the paper. Could you share some thoughts? Dr. Anand Rohatgi: Yes, Carolyn. Circulation as a journal represents the best in cardiovascular science, and we're always interested in the highest-level articles related to atherosclerotic cardiovascular disease. So, when we received this manuscript from Pradeep and Sekar's group, really leaders in the field, we were really excited, and as we went through the review process we got even more excited because it, as you said, Carolyn, it really was a tour de force, it was a high-quality article and it combined multiple things, and that's what we're really interested in seeing at Circulation, is combining several aspects, in this case genetics, sub-clinical atherosclerotic imaging, and also treatment effect. And, you know, it's interesting because several recent manuscripts looking at genetic risk scores, they were associated with coronary disease but it wasn't clear that they were improving what we call risk prediction performance indices, at least enough to meet the bar of incorporating them into guideline-type recommendations. So I think the field wasn't sure how to move forwards with this type of information, but now I think this study really demonstrates that this type of risk score, this genetic risk score, really can inform treatment decisions in a big way. And so we were really excited to talk about that and then see it move forward. Dr. Carolyn Lam: So a question for both of you now. Can these data be extrapolated to other cohorts of patients? I mean, WOSCOPS was predominantly white, and all were males, right? So, Pradeep, would you like to take that first? Dr. Pradeep Natarajan: That's an excellent observation, and I think ... A clear limitation in the field, but an outstanding question that I think can be addressed going forwards. So, the main challenge is that the epidemiological cohorts that were used for genetic analysis largely have been of European ancestry, and we know that genetic background and a variety of non-genetic factors influence cardiovascular disease risk, so in genetic analysis of European individuals the influencers of coronary disease risk may not influence cardiovascular disease the same in non-European ethnicities. And, you know, we've done some work of this specifically in African-Americans, and there are some differences. You know, African-Americans are largely mixed of both African and European ancestry, some of that seems to also influence how you interpret the cardiovascular genetic risk score. Ideally you would have a risk score that is not influenced by the genetic background, and so the next step going forward are one to look to see how well this risk score predicts in non-European ancestry, because, obviously, not as much statin clinical trial information in non-European cohorts, but I think looking at the treatment effect in non-Europeans will be important. And then, you know, the third step is we and others are participating in several now large ongoing efforts to really define what the genetic influences are in non-European ancestries, and I think that will be a very important next step that's really critical before the clinical implementation. Dr. Carolyn Lam: Yeah, talking to you from Asia, that's music to my ears, obviously. Anand, did you have any questions for Pradeep or anything else to add about the paper? Dr. Anand Rohatgi: Yeah, I wanted to add one or two comments. One thing that this study demonstrates is that the genetic risk scores, whether they relate to traditional risk factors or lipids, that doesn't necessarily translate to what it might mean in terms of treatment benefit, and so I think that concept is generalizable and now it needs to be tested in other ethnicities, other types of subgroups, but I think you can disentangle a relationship with risk factors and lipids to its treatment effect and this study really nicely shows that. And I think just to take a step back, we know statins work in intermediate-risk patients, maybe even low-risk patients with the most recent studies, but at a public policy level, and just as a cognition, we really want to narrow the focus, it's something called precision medicine that the American Heart Association is promoting as a concept, and I think that this study really demonstrates that here we have now another tool that can reduce this number needed to treat, make this choice for statins more precise, maximizing the benefits and limiting cost. So, I think that concept is very generalizable, it needs to be tested now in multiple populations, like Pradeep said, and I guess one of the questions I had had for the authors is: how do we incorporate this finding that they saw with sub-clinical atherosclerosis, which we thought was very fascinating among the editors at Circulation, that now they're also linking with sub-clinical atherosclerosis, is that something that the investigators think needs to be pursued further? Would that be something that would be used clinically as well? Dr. Pradeep Natarajan: I think there are lots of opportunities for this going forward, you know, in prior work we've done the genetic architecture for clinical coronary disease is actually very similar to sub-clinical coronary disease, and there are many influences for sub-clinical coronary disease, and clinical coronary-disease, that are both genetic and environmental, and the aggregate effect from the polygenic risk on sub-clinical atherosclerosis suggests that it's obviously not absolute and there are other factors that influence sub-clinical atherosclerosis. Dr. Carolyn Lam: Well, listeners, you heard it right here. Thank you for joining us this week, tell all your friends about it, and don't forget to tune in again next week.
Commentary by Dr. Valentin Fuster
Drugs that reduce microtubule density or prevent the production of reactive oxygen species in skeletal muscle might slow the progression of Duchenne muscular dystrophy.
Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.
Fakultät für Chemie und Pharmazie - Digitale Hochschulschriften der LMU - Teil 03/06
Increased levels of reactive oxygen species (ROS) contribute to vascular diseases like pulmonary hypertension and atherosclerosis. Although a NOX2-containing NADPH oxidase similar to the neutrophil one has been described to be active in endothelial cells, the contribution of newly discovered NOX homologues (NOX1-NOX5) was still unclear. Therefore, the overall aim of this study was to better characterize the expression, regulation and function of NOX homologues in different endothelial cell models. First, we could demonstrate the presence of NOX1, NOX2, NOX4, NOX5 including NOX5S as well as p22phox mRNA and protein levels in Ea.Hy926 or HMEC-1 cells. Furthermore, NOX5 protein was also present in endothelial and smooth muscle cells in the vascular wall of spleen and lung tissue. We found that NOX2, NOX4 and NOX5 were present in an intracellular perinuclear compartment, whereby NOX2 and NOX4 could be localized simultaneously in one cell. NOX2, NOX4, NOX5 were able to interact with p22phox and overexpression of NOX2, NOX4 and NOX5 increased ROS generation, although NOX5-dependent ROS generation did not require the presence of p22phox. NOX2, NOX4 and NOX5 also increased endothelial proliferation while depletion of NOX2, NOX4 and NOX5 decreased ROS generation, proliferation and tube forming ability indicating angiogenic activity under basal conditions. NOX2- and NOX4-induced proliferation was mediated by p38 MAP kinase. Although NOX1 expression as well as the expression of its regulatory subunits NOXO1 and NOXA1 was detectable in endothelial cells, depletion of NOX1 did not significantly affect basal ROS generation or proliferation of endothelial cells. Second, we could demonstrate the upregulation of NOX2, NOX5 and NOX5S after thrombin stimulation in endothelial cells and the modulation of p22phox expression in an ATF4- and XBP1-dependent manner under ER-stress conditions. Cellular stress either by thrombin or UPR also induced ROS generation of endothelial cells. In addition, thrombin induced proliferation and enhanced the tube forming ability of endothelial cells. Thrombin-induced ROS generation, proliferation and tube forming ability were diminished by silencing NOX2 or NOX5, whereas UPR induced ROS generation was inhibited by silencing p22phox as well as by silencing ATF4 or XBP1. In summary, this work provides evidence that in endothelial cells, NOX2, NOX4 and NOX5, but not NOX1, contribute to basal ROS generation, proliferation and angiogenesis and that the NOX proteins NOX2 and NOX5 as well as p22phox play an important role in the response to thrombin and ER-stress providing new insights in endothelial function and redox signaling.
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