tbuckley/cabot-search huggingface dataset:
Abstract We143: MED12 Dysregulation Disrupts Transcriptional Programs Leading to Dilated Cardiomyopathy
Authors: Dominic Kolonay, Kedryn Baskin, Kathlyene Stone
Journal: Circulation Research (2024)

The Mediator complex serves as a bridge to link transcriptional machinery and transcription factors (TFs) to control transcription, but detailed molecular mechanisms of transcriptional regulation by Mediator are not well-understood. Mediator is comprised of the head, middle, and tail submodules that make up the core Mediator, and the transiently associating kinase submodule. The CDK8 kinase submodule acts to regulate Mediator-RNA Polymerase II interaction. MED12 is an essential Mediator component within the kinase submodule and is required for CDK8 kinase activity. In aging models, dysregulated levels of Med12 mRNA are detected in both atria and ventricles by qRT-PCR. MED12 protein levels are also increased in human heart failure biopsies and in the mouse heart after transverse aortic constriction (TAC)-induced heart failure[KB1] . To test the hypothesis that increased levels of MED12 contribute to development of heart failure we generated cardiac-specific Med12 transgenic mice (cTg) by driving increased MED12 expression in cardiomyocytes using the αMHC promoter. Med12 overexpression leads to a progressive decrease in fractional shortening by serial echocardiography. Decreased cardiac function was accompanied by increased cardiac chamber size and dilation, without cardiac fibrosis. RNA sequencing of cardiomyocytes from cTg and control mice revealed that increased levels of MED12 leads to early changes in gene expression programs. Using ingenuity pathway analysis we identified MED12-regulated gene programs including those involved in calcium cycling. MED12 is a transcriptional regulator but does not directly bind DNA. To determine how MED12 regulates gene expression we screened for TFs that interact with MED12. We performed immunoprecipitation of MED12 and by mass spectrometry and determined that MED12 interacts with the TFs MEF2, CREB, and SRF. In follow-up experiments we demonstrated that MED12 interacts with the transcription factor (TF) MEF2 to regulate calcium handling genes. Current studies are focused on determining how MED12 binding coordinates gene expression through multiple TFs in cardiomyocytes. Collectively, our data demonstrate that increased MED12 expression leads to the development of heart failure, in part by dysregulation of gene expression. Therefore, precise regulation of MED12 levels is important to maintain normal cardiac function. [KB1]What about aging?
Abstract We036: Recapitulating Cardiac Microenvironment: Elucidating the Role of ECM Components and Architecture on Cardiac Differentiation
Authors: Kiran Ali, Jessica Gluck
Journal: Circulation Research (2024)

The discovery of iPSCs was revolutionary for regenerative medicine, especially as a source to replace a cell population with limited regeneration capability, like cardiomyocytes (CMs). However, the exact mechanism(s) governing how the microenvironment influences cardiac differentiation at a cellular scale is still widely unclear. To bridge this gap, we created an in vitro fibrous model from a decellularized porcine cardiac extracellular matrix. The aim is to assess the impact of the microenvironment, specifically the effects of protein composition and micro-architecture, on the cardiac differentiation of iPSCs. To study the role of protein composition, atrial and ventricular regions of the porcine heart are manually identified and separated as their protein composition is observed to be different. To test this, the material was subjected to proteomics analysis with LS-Mass Spectrometry where about 1000 proteins were identified in the ventricular region and only 300 proteins in atria. The decellularized tissue was tested for complete removal of nuclei by staining and further validated with DNA quantification. The dECM was blended with synthetic polymer (polycaprolactone) for electrospinning. The average collected fiber diameter was 14.8 ± 3.9 μm. The fibrous scaffolds were seeded with iPSCs and differentiated towards cardiac lineage. dECM samples show comparable signs of biocompatibility as laminin-521 coated TCPS, forming clusters throughout the differentiation process indicating that the scaffolds encourage cardiac differentiation. Further analysis is being conducted to compare the cellular expressions of differentiation markers including mesoderm formation, cardiac specification, and cardiomyocyte structural and functional markers. The effects of the ECM composition will be checked with myosin light and heavy chain expressions, as their expressions vary in the atrial and ventricular regions of the heart.
Abstract Mo082: Polygenic Assessment for Atrial Fibrillation Liability Predicts Ventricular Arrhythmia Risk
Authors: Megan Puckelwartz, Daniel Acciani, Tanner Monroe, Lorenzo pesce, Samuel Kearns, Lisa Dellefave-Castillo, Gregory Webster, Elizabeth McNally
Journal: Circulation Research (2024)

Background: The risks for atrial and ventricular arrhythmias are increased with cardiomyopathy. Currently, left ventricular dysfunction is the major determinate of implantable cardioverter-defibrillator (ICD) placement despite left ventricular ejection fraction only having an odds ratio of 2.9 for subjects with an LVEF &lt;35% with sensitivity and specificity that suggests many patients are inappropriately receiving or not receiving a device. Additional testable variables would aid in arrhythmia risk stratification. There is growing evidence that atrial dysfunction is both a cause and consequence of ventricular disease. Atrial fibrillation (AFib) is the most common atrial arrhythmia and is highly heritable suggesting a strong genetic basis, and AFib occurs at increased frequency with cardiomyopathies. Genome-wide association studies (GWAS) identify &gt;100 loci that contribute to AFib, and signals from GWAS can be used to develop polygenic risk scores (PRS). Subjects in the top 3% of one AFib PRS were found to have ~2 fold greater risk for AFib (OR 1.7-4.6). Hypothesis: The genetic pathways represented in an AFib PRS account for a portion of arrhythmia risk associated with cardiomyopathy and can be exploited to predict ventricular arrhythmia risk. Approach: As part of an AHA Arrhythmia and Sudden Death Strategically Funded Research Network, we assembled a cohort with varying risk for sudden cardiac death ranging from low-risk individuals with non-ischemic cardiomyopathy without arrhythmia to higher risk individuals who underwent ICD placement for aborted sudden death and sudden death. Whole genome sequencing was completed 1043 individuals across the arrhythmia risk spectrum. Results: We examined an AFib PRS to define ventricular outcomes in the cohort. Of the 440 participants with disease, 81% had cardiomyopathy, 8% channelopathy and 7% idiopathic arrest. We found the AFib PRS stratified subjects without significant ventricular arrhythmia risk from subjects with known ventricular arrhythmia (p=0.03), indicating that the AFib PRS includes components that are important markers of ventricular dysfunction. Conclusions: The AFib PRS is a useful tool to stratify ventricular arrhythmia risk.
Abstract We009: Cardiac Fibroblast Autophagy Is Required for Neonatal Heart Regeneration
Authors: Jie Feng, Yandong Li, Yu Nie
Journal: Circulation Research (2024)

Introduction: During heart regeneration, a switch between the synthesis, secretion and degradation of extracellular matrix (ECM) is essential, which relies on highly coordinated biosynthetic and catabolic processes. Although many biosynthetic signaling have been identified, catabolic processes in heart regeneration is still largely unexplored. Hypothesis: Autophagy is a key catabolic process necessary for depredating unwanted cellular components, dysfunctional organelles or aggregated proteins, and providing the needed substances for newly synthesizing ECM. We assessed the hypothesis that autophagy was involved in heart regeneration through regulating ECM remodeling. Methods: Apical resection (AR) and myocardial infarction (MI) models in neonatal mice were used. Three mouse stains, GFP-LC3 tg/+ , Atg7 fl/fl and Col1a2-2A-CreER mice were induced . Transmission electron microscopy was applied to observe autophagic vesicles. Immunostaining was used to detect autophagy activation and cardiomyocyte proliferation. Cardiac fibrosis was evaluated by Masson staining. Liquid chromatography-mass spectrometry was utilized for ECM components analysis. Results: We performed AR injury on postnatal day 1 (P1) mice, and observed an obvious increase in the number and size of autophagic vesicles in the injured heart tissue at 1 day post-resection using transmission electron microscopy (TEM). Co-localization analysis of GFP-LC3 with cardiomyocyte marker α-actinin and fibroblast (FB) marker PDGFRα revealed that autophagy was predominantly activated in cardiac FBs following AR. Cardiac FB-specific Atg7 conditional knockout ( Atg7- cKO) resulted in impaired heart regeneration after AR or MI injury in neonatal mice, accompanied by reduced cardiomyocyte proliferation. Cardiac ECM (cECM) derived from Atg7 -cKO mice hindered cardiomyocyte proliferation compared to Atg7 fl/fl mice, indicating that cardiac FB autophagy regulated cardiomyocyte proliferation by modulating the ECM profile. Through liquid chromatography-mass spectrometry analysis, we revealed that cardiac FB-specific Atg7 deficiency induced the downregulation of ECM components associated with regeneration, cell cycle, and muscle cell proliferation. Conclusion: In conclusion, our research highlights that cardiac FB autophagy plays a crucial role in neonatal heart regeneration by controlling the ECM remodeling. These findings suggest that targeting autophagy could be a promising therapeutic approach for individuals with ischemic heart disease.
Abstract We112: Volumetric imaging to recapitulate cardiac injury and arrhythmias
Authors: Yichen Ding, Alireza Saberigarakani, Xinyuan Zhang, Milad Almasian, Jie Yuan
Journal: Circulation Research (2024)

Advanced understanding of cardiac structure and function is crucial for uncovering the underlying mechanism of injury and arrhythmias. To explore cues to structural and functional abnormalities in extensively established animal models, we have developed optical imaging and computational methods tailored to investigate intact hearts of zebrafish and rodents at cellular resolution. Our cardiac light-field microscopy allows us to capture instantaneous dynamics such as calcium transients, irregular contraction, and blood flow at 200 volumes per second in zebrafish larvae 1 . To improve the spatial resolution and enable the study of rodent models, we have customized two light-sheet imaging systems. One system is empowered by the retrospective synchronization and machine learning for the study of contractile function and focal myocardial mechanics from end-systole to end-diastole 2 , while the other integrates tissue clearing and axially scanning approaches for the exploration of ventricular trabeculation and myocardial compaction 3 . These methods aim to overcome the trade-off in spatial resolution, imaging speed, field of view across the atria and ventricles with minimal photo-damage and maximal penetration depth, enabling long-term investigation of cardiac development and regenerative processes. To further interpret the large volume of datasets, we have customized a successive subspace learning and virtual reality-based platform for interactive image analysis 4 . Collectively, our multi-scale strategy has opened up new landscapes for exploring the cardiac micro-structure and contractile function, both in health and disease. References 1. Saberigarakani A, et al. Light-field microscopy to study cardiac arrhythmias in zebrafish larvae. In: Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXXI. 2024. p. 48–55. 2. Zhang X, et al. 4D Light-sheet imaging and interactive analysis of cardiac contractility in zebrafish larvae. APL Bioeng . 2023;7:26112. 3. Almasian M, et al. 3D isotropic light-sheet imaging to reveal the structure of neonatal mouse hearts. In: Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXXI. 2024. p. PC128480F. 4. Yuan J, et al. Extended reality for biomedicine. Nat Rev Methods Prim . 2023;3:14.
Abstract We138: Single-nucleus and bulk multiomic analyses reveal the dynamics of individual cardiac cell types after myocardial infarction and the underlying gene regulatory networks
Authors: Yuxia Li, Leshan Wang, Qianglin Liu, Xujia Zhang, Peidong Gao, Jiangwen Sun, Xing Fu
Journal: Circulation Research (2024)

Cardiovascular diseases are the leading causes of death in the world, among which myocardial infarction (MI) is the most fatal form. Following MI, the death of cardiomyocytes induces cardiac remodeling, which is mainly mediated by cardiac fibroblasts but also involves other cardiac cell types. A deeper understanding of the dynamics of individual cell types among different stages after myocardial infarction may help identify novel therapeutic strategies. Here, through single-nucleus multiomic (snRNAseq and snATACseq) analysis of uninjured mouse hearts and mouse hearts at different time points (2 h, 1 d, 3 d, 7 d, and 4 w) after MI, we identified multiple cardiac cell types, including cardiomyocyte, fibroblast, epicardial cell, endothelial cell, mural cell, and immune cell, and their dynamic gene expression and chromatin accessibility after MI. Features specific to the acute and chronic responses of different cell types to MI were identified. Cell type-specific single-nucleus gene regulatory networks (snGRNs) constructed through integrated analysis of snRNAseq and snATACseq data revealed transcription factors possibly responsible for the gene expression changes in individual cell types. The cardiac fibroblast GRN was further enriched using bulk RNAseq and ATACseq data collected at more time points (uninjured, and 2 h, 12 h, 1 d, 3 d, 7 d, 2 w, and 4 w after MI) and non-coding RNA transcriptomics. Promoter and enhancer activities and chromatin interactions in cardiac fibroblasts were further verified by CUT&amp;Tag targeting corresponding histone markers and Hi-C, respectively. The refined cardiac fibroblast GRN identified multiple key transcription factors that likely govern cardiac fibroblast activation and differentiation after MI.
Abstract We001: Doxorubicin-Induced hiPSC Hormetic Model
Authors: Jahanvi Patel, Hazel Gonzalez Vargas, Iris Lopez Perez, Tania Toussaint, Rosy Joshi-Mukherjee
Journal: Circulation Research (2024)

Doxorubicin (Dox), an anticancer anthracycline drug, is an important tool to understand how cells develop resistance to anthracyclines. Hormesis is a biological phenomenon where low doses of drugs can have beneficial effects on cell proliferation and differentiation. hiPSCs are becoming the model of choice for Dox studies yet the low dose hormetic effect of Dox on hiPSC proliferation and differentiation is not well understood. We assess the hypothesis that low-dose Dox preconditioning of hiPSCs enhances pluripotency gene expression while maintaining pluripotency state. To determine the low-dose effect (50 nM), we treated the JHU001 hiPSC line with Dox (hiPSC-D50) for two hours and a vehicle control without Dox (hiPSC-D0). Both hiPSC-D50 and hiPSC-D0 were maintained in E8 flex medium culture until reaching 70% confluency and were passaged five times and frozen for experimental studies. hiPSC-D50 and -D0 were thawed at passage 5 and cultured on coverslips for pluripotent gene expression (Oct-4, Nanog, and SSEA-4) analysis by immunocytochemistry. The cells were imaged using epifluorescence Nikon Eclipse Ti2 microscopy and the images were analyzed using NIS-Elements BR software. Phase-contrast microscopy shows significant cell death in hiPSC-D50 24 hours post-treatment compared to hiPSC-D0. However, 72 hours post-Dox-treatment, several colonies with pluripotent morphology were observed in hiPSC-D50 that were similar to hiPSC-D0. While some differentiated cell morphologies were observed in hiPSC-D50, these were significantly reduced after five passages. Immunofluorescent staining of Oct-4 and Nanog showed nuclear localization whereas SSEA-4 was localized on the cell surface, in both hiPSC-D0 and hiPSC-D50 cells at passage five. However, immunocytochemistry analysis of pluripotent markers revealed significantly higher expression of Oct-4, Nanog and SSEA-4 in hiPSC-D50 when compared to hiPSC-D0 (1.3-fold,1.9-fold and 2.9-fold increase with p-values: 0.00057, 0.018, and 0.0000026, respectively; n= 5) suggesting a more robust pluripotent state and self-renewal capacity. Interestingly, higher SSEA-4 expression might also be associated with resistance to Dox. Our data suggest that low-dose Dox preconditioning enhances pluripotency state. This Dox-induced hormesis model of hiPSCs is a unique platform to help understand how Dox upregulate pluripotency markers and the potential link between SSEA-4 and drug resistance.
Abstract We127: Infective Endocarditis in COVID-19 - An Unusual Suspect
Authors: Sean Masi, Darshine Venugopal, Stefanie Delvecchio
Journal: Circulation Research (2024)

Introduction: The COVID-19 pandemic globally overwhelmed healthcare systems and the complications associated with this illness have contributed to poor outcomes. The hypercoagulable state associated with COVID-19 is well recognized in the literature. Thromboembolic complications such as left ventricular thrombus (LVT), deep venous thrombosis (DVT) and pulmonary embolism (PE) have been increasingly reported. Dhakal et al. published an association between COVID-19 and cardiovascular disease, including possible complication by infective endocarditis (IE) which was confirmed by Amir et al. reporting the first case. Since then, there have been few reported cases. We present a case of COVID-19 in a patient who developed LVT, complicated by non-valvular IE by an underreported organism, Granulicatella adiacens. Case Presentation: A 55-year-old male with history of dental caries, provoked DVT/PE, NSTEMI x2 and STEMI in-stent restenosis requiring thrombectomy presented to the hospital with a 2-day history of shortness of breath, fatigue, cough, change in mentation and right-sided weakness. He tested positive for COVID-19 by NAAT. CXR revealed cardiomegaly and multiple bilateral infiltrates. CT head demonstrated acute ischemic stroke of the left occipital, parietal and posterior temporal lobes, also confirmed on MRI. CTA neck showed 30% stenosis of left ICA. Blood cultures x2 resulted positive for G. adiacens. Echocardiogram was obtained, demonstrating reduced EF of 35% and the presence of a large, 2.7 x 2.2cm mobile thrombus in the apical-septal region of the left ventricle, not visualized on previous echocardiogram 6 months earlier. Methods: Data was collected from direct patient care and electronic medical records. Discussion: G. adiacens is a fastidious gram-positive coccus, part of the nutritionally variant streptococci (NVS) species, and part of the normal oral and gastrointestinal flora. It is also found in dental plaques and endodontic abscesses. NVS account for less than 5% of cases of bacteremia and IE. G. adiacens account for even fewer cases. Two separate meta-analyses conducted by Quintero-Martinez et al. and George et al. failed to reveal any cases of IE attributable to G. adiacens in the setting of COVID-19 infection. In conclusion, we believe that the hypercoagulable state of COVID-19 infection led to endocardial damage and development of LVT, thereby creating a nidus for microorganism adherence from underlying dental carries resulting in thromboembolic stroke.
Abstract We126: Myocarditis Following mRNA Vaccination for COVID-19 is Mediated by CXCL10 and IFN-γ
Authors: Xu Cao, Masataka Nishiga, Amit Manhas, Arianne Caudal, Gema Mondejar-Parreno, Shane Zhao, James Jahng, Mingqiang Wang, Pj Utz, Kari Nadeau, Joseph Wu
Journal: Circulation Research (2024)

Introduction: mRNA vaccines have shown remarkable efficacy against symptomatic COVID-19, reshaping the pandemic's trajectory. Despite a robust safety profile, ongoing monitoring is crucial due to the rare but concerning myocarditis cases, predominantly affecting males under 30. Symptoms appear around 2.6 days post-vaccination, with chest pain, shortness of breath, and palpitations. Elevated cTnI and ST-segment changes are common, along with late gadolinium enhancement in cardiac MRI. Understanding these rare adverse effects is essential for the expanding scope of mRNA technology, spanning infectious disease vaccines and anti-cancer immunotherapies. Hypothesis: Myocarditis linked to COVID-19 mRNA vaccines involves cytokine production from myeloid cells, leading to impaired cardiac function. Methodology: a, Reanalysis of proteomics data of healthy and myocarditis individuals following COVID-19 vaccination; b, Macrophages (N = 7 lines) were exposed to BNT162b2 or mRNA-1273, and analyzed by cytokine array and RNA-seq; c, Cardiomyocytes (N = 4 lines) were treated with CXCL10 (1 and 10 ng/mL) and IFN-γ (0.5 and 5 ng/mL), with or without genistein (10 μM), followed by functional assessment, transcriptomic and proteomic profiling; d, Mice (6 per group) were administered with CXCL10 and IFN-γ, with or without genistein pretreatment (7 days). Myeloid cell infiltration in the heart, serum cTnI levels, RNA-seq, and immunoproteasome activity were analyzed. Results: Examination of post-vaccination plasma revealed a notable rise in CXCL10 and IFN-γ levels in patients. Similarly, macrophages exposed to mRNA vaccines displayed heightened production of these cytokines. When cardiomyocytes were exposed to these cytokines, they exhibited compromised contractility, increased arrhythmogenicity, and gene expression patterns reminiscent of myocarditis. Genistein, an anti-inflammatory phytoestrogen, demonstrated significant alleviation of these effects, preventing cytokine-induced proteasomal activation and preserving contractile function. Mouse model of cytokine-induced myocarditis showed that genistein substantially reduced cardiac injury markers and immune cell infiltration. Conclusion: These findings highlight CXCL10 and IFN-γ as pivotal contributors to myocarditis following mRNA vaccination and suggest genistein as a potential therapeutic intervention to mitigate associated cardiovascular risks.