Podcasts about mhc ii

In May 2025, we attended IMMUNOLOGY2025™, the annual meeting of the American Association of Immunologists in Honolulu, where we recorded daily episodes highlighting key developments from the previous 24 hours. This is the fourth of five special episodes from the meeting. In this episode, Brenda and Jason discuss how macrophages contribute to lung tissue repair and influence hormone activity, as well as the mechanisms linking MHC-II abnormalities to autoimmune disease pathogenesis.

CardioNerds (Dr. Amit Goyal) join Dr. Anureet Malhotra, Dr. John Fritzlen, and Dr. Tarun Dalia from the University of Kansas School of Medicine for some of Kansas City's famous barbeque. They discuss a case of Hydroxychloroquine induced cardiomyopathy. Notes were drafted by Dr. Anureet Malhotra, Dr. John Fritzlen, and Dr. Tarun Dalia. Expert commentary was provided by Dr. Pradeep Mammen. The episode audio was edited by Dr. Akiva Rosenzveig. Drug-induced cardiomyopathy remains an important and under-recognized etiology of cardiomyopathy and heart failure. Hydroxychloroquine is a disease-modifying antirheumatic drug used for various rheumatological conditions, and its long-term use is well-known to have toxic effects on cardiac muscle cells. Multiple cardiac manifestations of these drugs have been identified, the most prominent being electrophysiological disturbances. In this episode, we discuss a biopsy-proven case of hydroxychloroquine-induced cardiotoxicity with detailed histopathological and imaging findings. We develop a roadmap for the diagnosis of hydroxychloroquine-induced cardiomyopathy and discuss the various differentials of drug-induced cardiomyopathy. We highlight the importance of clinical monitoring and early consideration of drug-induced toxicities as a culprit for heart failure. US Cardiology Review is now the official journal of CardioNerds! Submit your manuscript here. CardioNerds Case Reports PageCardioNerds Episode PageCardioNerds AcademyCardionerds Healy Honor Roll CardioNerds Journal ClubSubscribe to The Heartbeat Newsletter!Check out CardioNerds SWAG!Become a CardioNerds Patron! Case Media - Hydroxychloroquine induced cardiomyopathy Pearls - Hydroxychloroquine induced cardiomyopathy Continued decline in left ventricular systolic function despite appropriate guideline directed medical therapy should prompt a thorough evaluation for unrecognized etiologies and warrants an early referral to advanced heart failure specialists. Transthoracic echocardiogram is a valuable non-invasive screening tool for suspected pulmonary hypertension, but right heart catheterization is required for definitive diagnosis. Cardiac MRI can be used for better characterization of myocardial tissue and can aid in the evaluation of patients with non-ischemic cardiomyopathy. Hydroxychloroquine (HCQ) is a commonly used DMARD that remains an underrecognized etiology of cardiomyopathy and heart failure. In addition to ophthalmological screening, annual ECG, as well as echocardiography screening for patients on long-term HCQ therapy, should be considered in patients at risk for cardiovascular toxicity, including those with pre-existing cardiovascular disease, older age, female sex, longer duration of therapy, and renal impairment. Management of hydroxychloroquine-associated cardiomyopathy consists of discontinuing hydroxychloroquine and standard guideline-directed medical therapy for heart failure.  HCQ cardiomyopathy may persist despite medical therapy, and advanced therapy options may have to be considered in those with refractory heart failure. Show Notes - Hydroxychloroquine induced cardiomyopathy What are the various cardiotoxic effects of hydroxychloroquine (HCQ) and the mechanism of HCQ-mediated cardiomyopathy? One of the most frequently prescribed disease-modifying antirheumatic drugs (DMARDs), HCQ is an immunomodulatory and anti-inflammatory agent that remains an integral part of treatment for a myriad of rheumatological conditions. Its efficacy is linked to inhibiting lysosomal antigen processing, MHC-II antigen presentation, and TLR functions.8 The known cardiac manifestations of HCQ-induced toxicity include conduction abnormalities, ventricular hypertrophy, hypokinesia, and lastly, cardiomyopathy. Conduction Abnormalities - by binding to and inhibiting the human ether-à-go-go-related gene (hERG) voltage-gated potassium channel,

Klaus Früh visits the Incubator to discuss his career and his work on cytomegalovirus-vectored vaccines which are unique in their ability to persistently maintain an immune shield of effector memory T cells, including highly unconventional MHC-II and MHC-E restricted CD8+ T cells. Host: Vincent Racaniello, Rich Condit, and Brianne Barker Guest: Klaus Früh Subscribe (free): Apple Podcasts, Google Podcasts, RSS, email Become a patron of TWiV! Links for this episode MicrobeTV Discord Server MicrobeTV store at Cafepress Spike shirts at vaccinated.us (promo code Microbetv) Research assistant position in Rosenfeld Lab CBER/FDA (pdf) HCMV-based attenuated vaccine platform (Sci Rep) HLA-E-restricted, Gag-specific CD8+ T cells suppress HIV-1 infection (Sci Immunol) RhCMV/SIV vaccine shows long-term efficacy against SIV challenge (Sci Transl Med) Timestamps by Jolene. Thanks! Intro music is by Ronald Jenkees Send your virology questions and comments to twiv@microbe.tv

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.14.549028v1?rss=1 Authors: Wallings, R., Mark, J., Staley, H., Gillett, D., Neighbarger, N., hirst, w., Kordasiewicz, H., Tansey, M. G. Abstract: Genetic variation around the LRRK2 gene affects risk of both familial and sporadic Parkinson's disease (PD). LRRK2 levels have become an appealing target for potential PD-therapeutics with LRRK2 antisense oligonucleotides (ASOs) now in clinical trials. However, LRRK2 has been suggested to play a fundamental role in peripheral immunity, and it is currently unknown if targeting increased LRRK2 levels in peripheral immune cells will be beneficial or deleterious. Furthermore, the precise role of LRRK2 in immune cells is currently unknown, although it has been suggested that LRRK2-mediated lysosomal function may be crucial to immune responses. Here, it was observed that G2019S macrophages exhibited increased stimulation-dependent lysosomal tubule formation (LTF) and MHC-II trafficking from the perinuclear lysosome to the plasma membrane in an mTOR dependent manner with concomitant increases in pro-inflammatory cytokine release. Both ASO-mediated knock down of mutant Lrrk2 and LRRK2 kinase inhibition ameliorated this phenotype and decreased these immune responses in control cells. Given the critical role of antigen presentation, lysosomal function, and cytokine release in macrophages, it is likely LRRK2-targetting therapies may have therapeutic value with regards to mutant LRRK2 but deleterious effects on the peripheral immune system, such as altered pathogen control and infection resolution. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.12.14.520294v1?rss=1 Authors: Sulzer, D., Hobson, B., Stanley, A., De Los Santos, M., Culbertson, B., Mosharov, E., Sims, P. Abstract: Dysregulated inflammation within the central nervous system (CNS) contributes to neuropathology in infectious, autoimmune, and neurodegenerative disease. With the exception of microglia, major histocompatibility complex (MHC) proteins are virtually undetectable in the mature, healthy central nervous system (CNS). Neurons have generally been considered incapable of antigen presentation, and although interferon gamma (IFN-{gamma}) can elicit neuronal MHC class I (MHC-I) expression and antigen presentation in vitro, it remains unclear whether similar responses occur in vivo. Here we directly injected IFN-{gamma} into the ventral midbrain of mature mice and analyzed gene expression profiles of specific CNS cell types. We find that IFN-{gamma} induces cellular proliferation and expression of MHC-II and associated genes only in microglia. However, IFN-{gamma} upregulated MHC-I and associated mRNAs in ventral midbrain microglia, astrocytes, oligodendrocytes, and GABAergic, glutamatergic, and dopaminergic neurons. The core set of IFN-{gamma}-induced genes and their response kinetics were conserved across neurons and glia, with a lower amplitude of expression in neurons. A diverse repertoire of genes was upregulated in glia, particularly microglia, while no neuron-specific responses to IFN-{gamma} were observed. Using mutant mice to selectively delete the IFN-{gamma}-binding domain of IFNGR1 in dopaminergic neurons, we demonstrate that dopaminergic neurons respond directly to IFN-{gamma}. Our results suggest that most neurons are capable of responding directly to IFN-{gamma} and upregulating MHC-I and related genes in vivo, but their expression amplitude and repertoire is limited compared to oligodendrocytes, astrocytes, and microglia. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Al Singer joins immune to discuss mice that have their T cell immune system reversed, revealing the molecular basis for T cell lineage fate determination in the thymus. Hosts: Vincent Racaniello, Cynthia Leifer, Steph Langel, and Brianne Barker Guest: Al Singer Subscribe (free): Apple Podcasts, Google Podcasts. RSS, email Become a patron of Immune! Links for this episode T cell FlipFlop mice reveal lineage determination (Nat Immunol) Time stamps by Jolene. Thanks! Music by Steve Neal. Immune logo image by Blausen Medical Send your immunology questions and comments to immune@microbe.tv

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.

Dr Guerra continues his associative pathobiochemical dialectic concerning T lymphocytte differentaition and senescence The Th and Tc populations following uptake and processing of an antigen by an APC such as a dendritic cell is presented either to the CD8 population in the context of MHC-I or to the CD4 subpopulation in the context of MHC-II generates a cascading set of cellular lymphoproliferative and differentiative steps initiated under the inductive influence of cytokines that ultimately determine effector functions. Papers examined in this episode: Nat Med. 2017 Jun; 23(6): 775–781 Cancer Genet Cytogenet. 1999 Mar;109(2):108-13. BMC Cancer volume 20, Article number: 882 (2020) --- Support this podcast: https://anchor.fm/dr-daniel-j-guerra/support

Hør denne podcast med Katrine og kim, og bliv klogere på hvad Major Histocompatibility Complex er. Her bliver snakket om både HLA, MHC I og MHC II.

Crescentic glomerulonephritis is characterized by glomerular necrosis. Dying cells release intracellular proteins that act as danger-associated molecular patterns to activate the innate immune system. Previously, we have demonstrated that dying tubular cells release histones, which can kill endothelial cells and activate the toll-like receptor 2/4 (TLR2/4). This drives tubulointerstitial inflammation in septic or post-ischemic acute kidney injury (AKI). Furthermore, other groups have also reported that extracellular histones cause organ damage during acute lung injury, stroke, peritonitis and retinal dysfunction, and that blocking extracellular histones represents a beneficial approach during the disease progression. In this thesis, we investigated whether extracellular histones can elicit similar pathogenic effects during necrotizing glomerulonephritis. To do so, we used an animal model based on the necrotizing type of severe glomerulonephritis. Necrotic glomerulonephritis was induced in mice by a single intravenous injection of 100µl sheep anti-GBM antiserum. The impact of histone neutralization was studied by using an antibody isolated from the BWA-3 clone, which had the capacity to neutralize released extracellular histones in-vivo and in-vitro. After 7 days, mice were sacrificed and kidneys were collected for further data analysis. Proteinuria was assessed in spot urine samples. Anti-GBM treated mice showed increased proteinuria (albumin/creatinine ratio), plasma creatinine and BUN levels. This was associated with a reduced number of podocytes, increased crescentic glomeruli and the infiltration of neutrophils and macrophages into the kidney. Interestingly, neutralization of extracellular histones significantly reduced proteinuria leading to less podocyte damage. This was linked to an improved renal function defined by lower plasma creatinine and BUN levels, and with a decrease in neutrophil and macrophage infiltration and activation in kidney. Histone blockade also significantly reduced renal mRNA expression of TNF-α and fibrinogen in the glomerular capillaries, which was associated with less glomerulosclerosis, crescents and tubular atrophy. In-vitro studies demonstrated that extracellular histones and NETs-related histones kill glomerular endothelial cells, podocytes and parietal epithelial cells in a dose-dependent manner. Histone-neutralizing agents such as anti-histone IgG, activated protein C or heparin prevented this cytotoxic effect. Stimulation of BMDCs with histones upregulated the expression of the activation marker including MHC-II, CD48, CD80 and CD86 significantly as well as increased the production of TNF-α and IL-6. It has been previously reported by others including us that in biopsies from patients with ANCA-associated vasculitis showed an over-expression of the TLR2/4 receptor compared to the healthy glomeruli. Histone toxicity on glomeruli ex-vivo was also dependent on the TLR2/4 receptor axis given that the lack of TLR2/4 attenuated histone-induced renal thrombotic microangiopathy and glomerular necrosis in mice. Anti-GBM glomerulonephritis involved NET formation and vascular necrosis, while blocking NET formation via PAD inhibitor or pre-emptive anti-histone IgG injection significantly reduced all parameters of glomerulonephritis including vascular necrosis, podocyte loss, albuminuria, cytokine induction, recruitment and activation of glomerular leukocytes, and glomerular crescent formation. Finally, to evaluate histones as a therapeutic target, mice with established glomerulonephritis were treated with three different histone-neutralizing agents such as anti-histone IgG, recombinant activated protein C and/or heparin. Interestingly, all agents were equally effective in abrogating severe glomerulonephritis, while combination therapy had no additive effect. In summary, the results of this thesis indicate that NET-related histones released during glomerulonephritis elicit cytotoxic and immunostimulatory effects and that neutralizing extracellular histones, therefore, represents a potential therapeutic approach when applied during already established glomerulonephritis.

Die Marek’sche Erkrankung (MD) ist weltweit eines der bedeutendsten Probleme in der Geflügelindustrie und verantwortlich für erhebliche wirtschaftliche Schäden. Die MD wird durch ein lymphotropes und strikt zell-assoziiertes α-Herpesvirus (MDV) verursacht, das immunsuppressiv wirkt und regelmäßig T Zelltumore induziert. B- und T-Zellen sind die primären Zielzellen des MDV in vivo. In B-Zellen kommt es zu einer lytischen Infektion und zum massiven Untergang der infizierten Zellen. Dagegen wird eine latente Infektion primär in CD4+ αβTCR+ T-Zellen beobachtet, welche nach Reaktivierung des Virus auch transformieren und Lymphome bilden können. Bis heute basieren alle Untersuchungen zur MD Pathogenese entweder auf in vivo Versuchen oder aber auf Zellkultursystemen, die mit Fibroblasten oder Nierenzellen arbeiten. Ein in vitro Infektionssystem für B- und T-Zellen, den primären Zielzellen des Virus, konnte bis heute nicht etabliert werden. Ursächlich hierfür war das Fehlen geeigneter Zellkultursysteme für diese Zellen, die ex vivo nur eine sehr kurze Überlebenszeit und einen schnellen apoptotischen Zelltod zeigen. Fortschritte in der aviären Immunologie haben zur Charakterisierung zahlreicher Zytokinen und Wachstumsfaktoren geführt, die B- und T-Zellen in vitro aktivieren, zur Proliferation anregen und erhöhte Überlebensraten induzieren. Diese Zytokine wurden in der vorliegenden Arbeit genutzt, um neue Kultursysteme für Hühner-Lymphozyten zu etablieren, mit deren Hilfe in vitro MDV Infektionsmodelle für B- und T Zellen aufgebaut werden konnten. Die erfolgreiche Infektion der Zellen wurde mit Hilfe genetisch modifizierten MDV-Reporterviren (MDV RB-1B UL47GFP und RB-1B MeqGFP-UL47RFP) nachgewiesen. Die aus der Milz, dem Blut und der Bursa Fabricii isolierten B-Zellen wurden mit löslichem chCD40L stimuliert und mit MDV RB-1B UL47GFP infizierten Fibroblasten co-kultiviert. Zu verschiedenen Zeitpunkten nach der Infektion konnten infizierte B-Zellen durch die Expression von UL47GFP durchflusszytometrisch identifiziert werden. Die Infektion wurde zusätzlich durch die zytoplasmatische Färbung der MDV-Proteine ICP4 und gB bestätigt. Der Anteil infizierter Bursa-B-Lymphozyten stieg von 2,5% am ersten Tag nach der Infektion (p.i.) bis auf ca. 15% an Tag 4 p.i. Vergleichbare Werte wurden auch für B-Zellkulturen aus der Milz und dem Blut gefunden. Die durchflusszytometrische Charakterisierung der infizierten Zellpopulation erfolgte mit Hilfe zahlreicher Hühner-spezifischer monoklonaler Antikörper. Infizierte B-Zellen sind chBu1+ und zeigen einen distinkten Phänotyp sowie eine intermediäre Zellgröße. Für die weitere Charakterisierung wurden infizierte und nicht infizierte Bursa-B-Zellen durchflusszytometrisch sortiert (> 95% Reinheit) und Mikroarray basierten Genexpressionsanalysen unterzogen. Auch T-Zellen aus der Milz, dem Blut und dem Thymus konnten nach αVβ1-TCR (TCR-2) Stimulation auf dieselbe Weise mit RB-1B MeqGFP-UL47RFP infiziert werden. Der Hauptteil der infizierten T-Zellen zeigte einen CD4+ αVβ1-TCR+ Phänotyp, allerdings fanden sich auch einige infizierte CD8+ T-Zellen. Durch die alleinige Expression von MeqGFP oder die gleichzeitige Expression von UL47RFP und MeqGFP konnten die infizierten Thymozyten in eine latent und eine zytolytisch infizierte Population unterteilt werden. Während die zytolytisch infizierte Population primär aus B-Zellen und CD8+ T-Zellen bestand, waren die latent infizierten T-Zellen zum Großteil CD4+ T Zellen. Erstmals gelang es in dieser Arbeit die Übertragung des Virus von der B-Zelle auf die T Zellen durch Co-Kultivierung mit durchflusszytometrisch sortierten infizierten B Zellen direkt nachzuweisen. Darüber hinaus konnten aus Langzeitkulturen infizierter Thymozyten vier lymphoblastoide Zelllinien (JS1 –JS4) isoliert werden. Alle vier Linien zeigten ein homogenes, lymphoblastoides Erscheinungsbild und waren CD4+, αVβ1-TCR+, MHC I+ und MHC II+. Dieser Phänotyp entspricht exakt dem von in vivo transformierten T Zelllymphomen. Das in dieser Arbeit etablierte Infektionssystem ist das erste Kultursystem, mit dem eine reproduzierbare und effiziente MDV Infektion von Lymphozyten in vitro erreicht wird. Es spiegelt die verschiedenen Phasen des natürlichen Infektionszyklus wider. Damit eröffnet sich erstmals ein Weg, die Interaktion von B-Zellen und Virus, bzw. T-Zellen und Virus detailliert und zu definierten Zeitpunkten zu analysieren. Hervorzuheben ist, dass die hier beschriebenen Methoden nicht nur verbesserte Untersuchungsmöglichkeiten bieten, sondern auch dazu beitragen können, die Zahl der bisher notwendigen Tierversuche in der MDV-Forschung deutlich zu reduzieren.

Wed, 6 Nov 2013 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/18855/ https://edoc.ub.uni-muenchen.de/18855/1/Schulz_Anna.pdf Schulz, Anna ddc:610, ddc:600,

Objective: Trauma-hemorrhage results in depressed immune responses of antigen-presenting cells (APCs) and T-cells. Recent studies suggest a key role of depressed T-cell derived interferon (IFN)-g in this complex immune cell interaction. The aim of this study was to elucidate further the underlying mechanisms responsible for dysfunctional T-cells and their interaction with APCs following trauma-hemorrhage. Design: Adult C3H/HeN male mice were subjected to trauma-hemorrhage (3-cm midline laparotomy) followed by hemorrhage (blood pressure of 35�5mmHg for 90 min and resuscitation) or sham operation. At 24 h thereafter, spleens were harvested and T-cells (by Microbeads) and APCs (via adherence) were Isolated. Co-cultures of T-cells and APCs were established for 48 h and stimulated with concanavalin A and lipopolysaccharide. T-Cell specific cytokines known to affect APC function (i.e. interleukin(IL)-2, IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF)) were measured in culture supernatants by Multiplex assay. The expression of MHC class II as well as co-stimulatory surface molecules on T-cells and APCs was determined by flow cytometry. Results: The release of IL-4 and GM-CSF by T-cells was suppressed following trauma-hemorrhage, irrespective of whether sham or trauma-hemorrhage APCs were present. Antigen-presenting cells from animals subjected to trauma-hemorrhage did not affect T-cell derived cytokine release by sham T-cells. In contrast, T-cells from traumahemorrhage animals depressed MHC class II expression of CD11c(þ) cells, irrespective of whether APCs underwent sham or trauma-hemorrhage procedure. Surprisingly, co-stimulatory molecules on APCs (CD80, CD86) were not affected by trauma-hemorrhage. Conclusions: These results suggest that beside IFN-g other T-cell derived cytokines contribute to immunosuppression following trauma-hemorrhage causing diminished MHC II expression on APCs. Thus, T-cells appear to play an important role in this interaction at the time-point examined. Therapeutic approaches should aim at maintenance of T-cell function and their interaction with APCs to prevent extended immunosuppression following trauma-hemorrhage.

Analysis of MHC I and II presentation on Equid herpesvirus 1 infected cells Various Alphaherpesviruses are able to interfere with MHC class I presentation by reducing surface expression of these molecules. Equid herpesvirus 1 (EHV-1) infection also results in MHC I downregulation on the respective cells, but other than the involvement of the viral UL49.5-protein, this process is not yet very well understood (Rappocciolo et al., 2003; Ambagala et al., 2004; Koppers-Lalic et al., 2005). As the in vitro non essential EHV-1 proteins UL11p and UL43p were considered as further candidate proteins for playing a role in interfering with MHC I or II expression, the aim of this study was to elucidate this supposition. In a first step, the influence of EHV-1-infection on MHC I/II surface expression had to be investigated. At various time-points p.i., a considerable reduction of MHC class I-molecules on the surface of EHV-1-infected cultured equine cells could indeed be confirmed and was also observed after in vitro-infection of equine PBMC. Moreover, it could be clearly demonstrated for the first time that EHV-1-infection also results in a downregulation of MHC II expression on equine cell culture cells following interferon--induction. MHC II-expression on the surface of in vitro EHV-1-infected PBMC, however, was reduced slightly only. Previous results gave rise to the hypothesis that the EHV-1 proteins UL11p and /or UL43p might be involved in EHV-1-induced immunomodulation. In the course of this study, however, it could be demonstrated that neither a deletion of the UL11- nor of the UL43-gene had an impact on the downregulation of MHC I or II surface expression. No difference in MHC I presentation was detectable between cells infected with the recently isolated EHV-1 strains O834 (myeloencephalopathy, 1999) and E216 (abortion, 2006) but, surprisingly, MHC class I downregulation was even more pronounced than on cells infected with the EHV-1 strain RacL11 (abortion, 1958). The interferon- induced MHC II presentation, however, was affected similarly by all EHV-1 strains tested. Interestingly, during the course of this study, it became obvious that deleting the UL43-gene does not influence MHC I or II surface expression, but the distribution of viral cell surface glycoproteins in EHV-1-infected cells. Comparative studies with cells infected with RacL11, RacH, and the respective UL43-deleted viruses revealed that the absence of the UL43 gene-product resulted in quantitative changes concerning the expression of EHV-1 glycoproteins such as gC, gp2 and gD, as assessed by flow cytometry analysis. In addition, by confocal laser scanning microscopy, clear variations regarding the distribution of gB and gC were shown. Other glycoproteins, such as gM or membrane-associated proteins such as UL11p were not affected. These results give rise to the assumption that UL43p might in fact play a by far more important role in vivo than has yet been demonstrated in vitro.

Epstein-Barr virus (EBV) is associated with a number of human malignancies. EBV-positive post-transplant lymphoproliferative disease in solid organ and hematopoietic stem cell transplant recipients has been successfully treated by the adoptive transfer of polyclonal EBV-specific T cell lines containing CD4+ and CD8+ T cell components. Although patients receiving T cell preparations with a higher CD4+ T cell proportion show better clinical responses, the specificity of the infused CD4+ component has remained completely unknown. We generated LCL-stimulated T cell lines from 21 donors according to clinical protocols, and analyzed the antigen specificity of the CD4+ component in EBV-specific T cell preparations using a genetically engineered EBV mutant that is unable to enter the lytic cycle, and recombinantly expressed and purified EBV proteins. Surprisingly, CD4+ T cell lines from acutely and persistently EBV-infected donors consistently responded against EBV lytic cycle antigens and autoantigens, but barely against latent cycle antigens of EBV hitherto considered principal immunotherapeutic targets. Lytic cycle antigens were predominantly derived from structural proteins of the virus presented on MHC II via receptor-mediated uptake of released viral particles, but also included abundant infected cell proteins whose presentation involved intercellular protein transfer. Importantly, presentation of virion antigens was severely impaired by acyclovir treatment of stimulator cells, as currently performed in most clinical protocols. These results indicate that structural antigens of EBV are the immunodominant targets of CD4+ T cells in LCL-stimulated T cell preparations. These findings add to our understanding of the immune response against this human tumor-virus and have important implications for the improvement of immunotherapeutic strategies against EBV.