tbuckley/cabot-search huggingface dataset:
Abstract We050: Elevated Cell-Free RNA in Maternal Circulation during Single Ventricle Heart Defect Pregnancies Dysregulate Human Cardiomyocyte Proliferation
Authors: Matthew Alonzo, zhaohui xu, Shiqiao Ye, Cankun Wang, Megan McNutt, Yang Yu, Qin Ma, Karen Texter, Vidu Garg, Mingtao Zhao
Journal: Circulation Research (2024)

Congenital single-ventricle heart defects (SVHDs) are life-threatening conditions in newborns, where one of the heart's ventricular chambers is severely underdeveloped. While medical advancements have improved survival rates, many SVHD patients still suffer lifelong cardiac complications and comorbidities. Clinical diagnosis of fetal SVHD occurs at around 20 weeks of gestation through echocardiogram. In this study, we aimed to identify novel maternal blood biomarkers that could signal SVHD development in fetuses. The study's premise is based on the limited regenerative capacity of adult human cardiomyocytes, like those in pregnant mothers, compared to the extensive proliferation seen in fetal cardiomyocytes that form the functional heart. We hypothesized small signaling molecules secreted by proliferating fetal cardiomyocytes enter the maternal circulatory system and could indicate abnormal ventricular growth in SVHD-affected fetuses. Both clinical and in vitro approaches were employed to identify potential cell-free miRNAs released by the developing fetal heart into maternal circulation. Blood plasma samples from pregnant women carrying healthy and SVHD-affected fetuses were screened for differentially expressed cell-free miRNAs and were compared with those from the supernatants of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) grown from healthy and SVHD donors. This comparative approach led to the identification of an miRNA panel (miR-487b, miR-433, mi-134, and miR-889) that were elevated in pregnant women carrying SVHD-affected fetuses and in proliferating iPSC-CMs from SVHD patients compared to healthy controls (p.adj&lt;0.05). From this panel, forced-expression of miR-487b and mir-134 modulated the proliferation profiles of human cardiomyocytes in vitro . Results from this study establish these circulating cell-free miRNAs in maternal blood as potential non-invasive biomarkers for predicting abnormal fetal cardiac development leading to SVHDs. These findings could potentially revolutionize SVHD screening as an alternative diagnostic tool to echocardiogram.
Abstract Mo074: Overexpression of IPP2 Impairs Intracellular Calcium Handling, Leading to Arrhythmogenic Events
Authors: Gwang Hyeon Eom, Somy Yoon
Journal: Circulation Research (2024)

Cardiac arrhythmias, which are disruptions in the heart's electrical activities, critically affect the ventricular conduction system, impairing efficient blood circulation. These disturbances result in irregular heartbeats, contributing to patient mortality or causing harm to distant organs via embolic events. Given the severe implications, a profound understanding of the molecular mechanisms driving arrhythmia is crucial for devising specific treatments. This study unveils a pioneering link between the overexpression of IPP2 (Protein Phosphatase 1 Regulatory Inhibitor Subunit 2), driven by the Myh6 promoter (termed TgIPP2), and the onset of age-dependent cardiac arrhythmias. The electrical abnormalities observed in TgIPP2 overexpressing mice include a spectrum of dysfunctions such as axis deviations, elongated QRS and PR intervals, absence of P waves, AV dissociation, ventricular tachyarrhythmia, and heightened T waves. Investigating the pathophysiology behind these electrical anomalies, we subjected young adult mice to catecholamine challenges at low doses and conducted surface electrocardiogram (EKG) monitoring. TgIPP2 mice demonstrated a notable increase in arrhythmogenic episode frequency and duration following 0.2 mg/kg isoproterenol injection compared to their control counterparts. Through a protein phosphorylation analysis, we identified a key regulator of the ryanodine receptor, which modulates calcium release from the sarcoplasmic reticulum, correlating with the extended PR intervals and the delayed peaking of T waves. Therapeutic trials employing RyR blockers, specifically dantrolene, successfully normalized the erratic cardiac rhythms in aged TgIPP2 mice. However, beta blockers or L-type calcium channel blockers induced sudden cardiac death in this model. The study reveals that IPP2-induced aberrant phosphorylation disrupts calcium homeostasis, leading to arrhythmias. In conclusion, our research marks a significant advancement in understanding arrhythmogenic mechanisms, demonstrating that IPP2 overexpression directly triggers arrhythmia, particularly affecting the atrioventricular (AV) node, atria, and ventricles. The discovery that aberrant phosphorylation, especially of the RyR regulator, plays a pivotal role in initiating cardiac arrhythmias opens new pathways for targeted anti-arrhythmic therapies.
Abstract Or118: Transcription Factor Gene Therapy for Treatment of Junctional Bradycardia in a Porcine Model of Complete Atrioventricular Block Following His Bundle Ablation
Authors: Rafael Ramirez, Samuel Bergman, Jamal Masri, Alexander Weltz, Naman Kumar, Caridad de la Uz, Aravindan Kolandaivelu, Andreas Barth, Bernadette Barcelon, Jinqi Fan, Hee Cheol Cho
Journal: Circulation Research (2024)

Background: Pacemaker implantation is standard treatment for patients with complete atrioventricular (AV) block. However, contraindications for device implantations create a need for alternative non-hardware cardiac pacing solutions. We developed a porcine model of complete heart block with junctional bradycardia to test a novel transcription factor-based gene therapy consisting of Tbx18, Shox2 and Tbx3 (TST). Somatic reprogramming of ventricular cardiomyocytes by TST induces pacemaker-like activity and provides biological pacing in vitro . Methods: Eight domestic swine (Yorkshire/Landrace) received catheter ablation of the AV node/His Bundle resulting in complete AV block, confirmed by dissociation of P and R waves on ECG. An implanted device pacemaker (VVI mode) maintained cardiac output during occurrences of junctional bradycardia below 50 bpm. Telemetric 3-lead ECG was recorded continuously. Subjects received TST gene therapy or control gene (GFP) via catheter-based intramuscular injection into the high right ventricular septum. Pacemaker usage and ECG were continuously monitored for 8 weeks. Results: Following AV node ablation, junctional escape rhythm decelerated into junctional bradycardia. After 3 weeks of AV block, 49.9 ± 13.1% of heartbeats were initiated by the device pacemaker. Upon reaching pacemaker dependence of 95% in an average of 27.9 ± 5.5 days, subjects received TST gene therapy or control injection. In subjects receiving TST therapy, daily pacemaker reliance decreased to 50% dependency in an average of 14.7 ± 2.3 days, while in GFP controls, daily pacemaker dependency at 50 bpm remained unchanged at &gt;98% throughout follow-up. In TST-treated subjects, reductions in pacemaker dependence were associated with increases in ventricular rates exceeding 70 bpm. Efficacy of gene therapy waned after about one month; an improvement of &gt;10% pacemaker dependency over two consecutive days was still observed on average 29.0 ± 4.1 days after TST injection. Conclusion: In a porcine model of complete AV block, ventricular junctional escape rhythm decelerated into bradycardia in less than one month. Subsequent gene therapy by TST injection into the high ventricular septum alleviated pacemaker dependency and enhanced heart rate for 29.0 ± 4.1 days. Somatic reprogramming of cardiomyocytes by TST gene delivery may provide a biological pacemaker alternative to hardware device implantation for therapeutic cardiac pacing.
Abstract We078: Endothelial-specific PHD2 Modulates Cardiac Inflammation, Hypertrophy, and Dysfunction in an Age-dependent Manner
Authors: Xiaochen He, Rui Xu, Umesh Bhattarai, Lihong Pan, Dongzhi Wang, Ziru Niu, Heng Zeng, Jian-Xiong Chen, Yingjie Chen
Journal: Circulation Research (2024)

Background: Prolyl hydroxylase domain proteins (PHD) are oxygen-sensing molecules that degrade hypoxia-inducible factor-α. Deletion of endothelial-specific PHD2 (PHD2ECKO) shows different degrees of pulmonary arterial hypertension and cardiac hypertrophy. Whether EC-specific PHD2 deletion plays a role in regulating cardiac inflammation and dysfunction is still unclear. We investigated the effect of endothelial-specific PHD2 deficiency on cardiac inflammation and dysfunction in mice. Methods: Briefly, PHD2ECKO mice were obtained by crossing PHD2-floxed mice with VE-Cadherin-Cre transgenic mice. The effect of PHD2ECKO on cardiac structure and function was determined in male young (6 months old) and old (12-16 months old) mice. Results: While PHD2ECKO caused significant left ventricular (LV) hypertrophy in mice at 6 months, PHD2ECKO had no significant impact on LV fibrosis and dysfunction in these mice. However, PHD2ECKO caused significant LV leukocyte infiltration, fibrosis, cardiomyocyte hypertrophy, and LV dysfunction in mice over 12 months. Most interestingly, we found that PHD2ECKO caused a significant increase of cardiac CD4 + T cells and CD8 + T cells, activation, and their proinflammatory cytokine productions in mice at the age of 12 months. Moreover, we found that PHD2ECKO resulted in a significant upregulation of several adhesion molecules important for CD4 + and CD8 + T cell homing, retention, and proliferation. However, the cytokine production by other immune cell subsets was largely unaffected. Conclusions: Our findings demonstrated that endothelial-PHD2 exerts an important role in proliferation, activation, and proinflammatory cytokine production by CD4 and CD8 T cells, and the aging-dependent LV hypertrophy and dysfunction.
Abstract We096: Gene therapy of MAOA fine-tunes nuclear cAMP nanodomain and improves cardiac hypertrophy in mice
Authors: Wenjing Xiang, Xingsheng Sun, Chunyu Su, Yang Xiang, Ying Wang
Journal: Circulation Research (2024)

Cardiac hypertrophy, a precursor to heart failure, represents a leading cause of global mortality and morbidity. Current therapeutic strategies focused on reducing the heart's workload, demonstrate limited efficacy. Nuclear-localized cAMP emerges as a promising therapeutic target, intervening in hypertrophic gene transcription and exhibiting overactivation in hypertrophic cardiomyocytes. Despite its potential, the spatiotemporal regulation and molecular targets of nuclear-localized cAMP (NLS-cAMP) remain elusive. Employing super-resolution imaging, we identified a pool of β1 adrenergic receptors (β1AR) at the nuclear envelope that transduces NLS-cAMP-PKA signaling in cardiomyocytes. Utilizing a nuclear-localized FRET biosensor, our investigations revealed that the deletion or inhibition of monoamine oxidase A (MAOA) amplifies the norepinephrine-induced NLS-β1AR activation signal. Conversely, overexpressing MAOA prevents NLS-B1AR activation, underscoring the critical role of MAOA in regulating the NLS-cAMP nanodomain. Single-cell transcriptome analysis unveiled a decline in MAOA expression in a mouse cardiac hypertrophy model. Cardiac-specific deletion of MAOA in mice led to simultaneous hypertrophy and eventual heart failure. Mechanistically, MAOA deletion increased PKA-dependent phosphorylation of HDAC1, H3K27 acetylation, and chromatin accessibility of hypertrophic genes, including Nppa and Nppb. To validate therapeutic potential, we intraventricularly injected adeno-associated virus (AAV) 9 vectors expressing mcherry or mcherry-MAOA under the control of the cTNT promoter into mice. Inducing cardiac hypertrophy through Angiotensin II infusion five weeks later, mice preinjected with AAV-MAOA exhibited attenuated cardiac hypertrophy and improved cardiac function. Our findings suggest that MAOA gene therapy holds promise for treating hypertrophy by specifically targeting the NLS-cAMP nanodomain, opening new avenues for targeted interventions in cardiac hypertrophy and heart failure.
Abstract Or114: Inhibiting IL-1 Signaling to Cardiac Fibroblasts Protects Against Acute Viral Myocarditis
Authors: David Elias, Wonyoung Jo, Monica Talor, Daniela Cihakova
Journal: Circulation Research (2024)

Background: Understanding what factors perpetuate cardiac inflammation in patients with unremitting inflammatory dilated cardiomyopathy (iDCM) is critical for developing curative therapies. We have previously demonstrated that inflammatory fibroblasts (IFs), a subset of cardiac fibroblasts (CFs) that promote inflammation, depend on IL-17A signaling to drive iDCM progression in experimental autoimmune myocarditis. Here, we demonstrate that IL-1 signaling more potently activates IFs than IL-17A. IL-1 signaling has been implicated in the pathogenesis of viral myocarditis, the most common etiology of myocarditis, though the mechanism is unclear. Hypothesis: We hypothesize that IL-1 signaling to CFs induces their differentiation into IFs, which drive pathogenic inflammation during viral myocarditis. Methods: Primary murine CF cultures were used to characterize IF activation by various cytokines. Next, we both performed qPCR on sorted CFs and used a CCL2-mCherry reporter mouse line to phenotype IF activation during Coxsackievirus B3 (CVB3) myocarditis. Finally, in-vivo fibroblast-specific IL-1 signaling was genetically ablated using PDGFRα cre IL1r1 fl/fl mice. We infected PDGFRα cre and PDGFRα cre IL1r1 fl/fl mice with CVB3 and assessed myocarditis severity during the peak of inflammation using histological scoring and flow cytometry. Results: Innate, Th1, Th2, and Th17 related cytokines such as IL-1β, IFNγ, IL-13, and IL-17A induced unique IF gene expression signatures. IL-1β most potently activated IFs with a pro-myeloid cytokine inflammatory profile. During CVB3 myocarditis, IF activation peaked on day 3 post infection and was sustained until day 10. Ablating IL-1 signaling to CFs reduced the magnitude of cardiac inflammation by 45% ± 14% (p=0.002) during the peak of CVB3 myocarditis with a reduction in monocyte, CD4+ T cells, CD8+ T cells, and NK cell recruitment. Gene expression analysis of sorted CFs from mutant and control mice revealed reduced expression of pro-myeloid chemokines such as CXCL1 and CCL2 on day 3 of CVB3 myocarditis. Conclusions: Cardiac fibroblasts exhibit remarkable plasticity allowing them to respond to a changing micro-environment. Blocking IL-1 signaling to IFs during CVB3 myocarditis inhibited production of pro-inflammatory chemokines resulting in attenuation of myocardial inflammation. Therefore, early IF activity acts as a rheostat to modulate the magnitude of cardiac inflammation during myocarditis.
Abstract We098: Target-Specific Novel Therapeutic Approach for Prevention of Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia
Authors: Shreya Bavishi, Stryder Meadows
Journal: Circulation Research (2024)

Background: Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic vascular disease with no cure. HHT is characterized by abnormalities in blood vessels that occur in mucocutaneous tissues (telangiectasias) and deep tissues (arteriovenous malformations, AVMs). The tangled, enlarged, fragile, and aberrant vasculature in HHT patients is prone to chronic bleeding or hemorrhage and may cause serious complications, especially in the brain. Problem Statement: While diagnosed AVMs can be surgically treated, there are no FDA-approved drugs to prevent or manage them. Developing targeted therapeutics to manage AVMs has been incredibly challenging as the mechanism of AVM formation is not clearly understood. Rationale: Dysregulation of pro-angiogenic signaling pathways is considered to play a major role in AVM development. For instance, VEGFA-VEGFR2, ANG2–TIE2 and MAP Kinase 1/2 signaling have been implicated individually in HHT pathogenesis. While MAPK 1/2 signaling is difficult to target because of its universal presence, its upstream activators VEGFA and ANG2 are lucrative targets for their relative specificity primarily affecting vasculature (Figure 1). Innovation: We use a novel approach to target VEGFA and ANG2 simultaneously using IgG CrossMab bispecific inhibitor, allowing superior efficacy by inhibiting dual specific targets to prevent genetic vasculature abnormalities. Approach: We use vascular latex casting and molecular quantification techniques to assess the benefits of inhibiting abnormal pro-angiogenic signaling in HHT mice models. Our preliminary data shows improved vasculature development with small doses of MAPK 1/2 inhibitor, but early mortality due to its damaging side effects. Preliminarily, the combined effect of the bispecific inhibitor in smaller doses improves the vasculature defects in the mutant brain more robustly than the individual inhibitors alone, while not negatively affecting the wild-type model (Figure 2). We further expect this dual inhibition to normalize the transcriptomic signature of mutants to mimic the wild-type setting. Societal Impact: The expected beneficial effects of the bispecific inhibitor will provide a pre-clinical assessment of the cerebrovascular AVM management strategies for 1.4 million HHT patients. It will further the mechanistic understanding of AVM development and prevention in HHT, the 2 nd most common bleeding disorder.
Abstract We087: The mitochondrial citrate carrier SLC25A1 is a regulator of metabolic reprogramming and morphogenesis in the developing heart
Authors: Chiemela Ohanele, Jessica Peoples, Anja Karlstaedt, Joshua Geiger, Nasab Ghazal, Milton Brown, Michael Davis, George Porter, Jennifer Kwong
Journal: Circulation Research (2024)

Background: Congenital heart defects (CHDs) are the most common type of birth defect, yet the etiology of most CHDs are unknown. A major genetic risk factor for CHD is 22q11.2 deletion syndrome (22q11.2DS), a multisystem chromosomal microdeletion disorder where ~75% of patients present with CHD. SLC25A1 is a gene found within the 22q11.2DS microdeletion region that encodes for the mitochondrial citrate carrier, an inner membrane transporter that regulates intracellular citrate compartmentalization. Through this role, SLC25A1 is thought to contribute to cytosolic acetyl-CoA availability, and processes like protein acetylation and the epigenetic regulation of gene expression. We have previously found that SLC25A1 is a central gene contributing to the neurodevelopmental presentation of 22q11.2DS and importantly, neuronal mitochondrial function. Because the heart, like the brain, is highly reliant on energy derived from mitochondria, and the developing heart must undergo metabolic maturation whereby metabolism is reprogrammed from primary reliance on glycolysis towards mitochondrial oxidative metabolism, we hypothesized that SLC25A1 plays a key role in the metabolic maturation that is required for proper cardiac development. Objective: Here, we studied the role of Slc25a1 in the developing heart to examine the link between mitochondria and cardiac morphogenesis. Methods and Results: By studying mice with the systemic knockout of SLC25A1, we discovered that Slc25a1 null embryos displayed impaired growth, cardiac malformations, mitochondrial ultrastructural defects and impaired mitochondrial oxygen consumption. Transcriptomics analyses of metabolism-related genes revealed that Slc25a1 deletion causes widespread alterations in metabolic gene expression. Further, metabolic modelling predicted that loss of SLC25A1 downregulates oxidative phosphorylation, while increasing reliance on glucose. Finally, we found that loss of SLC25A1 decreases cardiac H3K9 acetylation levels at promoter regions of dysregulated metabolic genes. Mechanistically, SLC25A1 may regulating mitochondrial function and metabolism through epigenetic control of gene expression to promote metabolic remodeling in the developing heart. Conclusions: Our work suggests that SLC25A1 as an an important mitochondrial regulator of gene expression in the developing heart. Importantly, it positions SLC25A1 as a novel mitochondrial regulator of ventricular morphogenesis as well as cardiac metabolic maturation.
Abstract Mo044: Minimally Invasive Delivery of Mesenchymal Stem Cell-derived Exosomes Improves Heart Repair in Pigs
Authors: Yuan Li, Panagiotis Tasoudis, Ke Huang, Ke Cheng
Journal: Circulation Research (2024)

Myocardial infarction (MI) is one of the primary manifestations of cardiovascular events. Human mesenchymal stem cell-derived exosomes (hMSC-Exo) were shown to promote cardiac repair after MI. To harness the therapeutic effect, prolong the therapeutic window, and achieve minimally invasive delivery, hMSC-Exo was embedded in hyaluronic acid (HA) hydrogel. The intrapericardial cavity (iPC) is a natural “pocket” surrounding the myocardium. Clinically, iPC procedures were used to treat heart diseases, which could make iPC injection a viable route for drug delivery. In addition, porcine models were highly relevant for pre-clinical studies due to their physiological and anatomical similarities to human patients. Therefore, we hypothesized that minimally invasive delivery of MSC-Exo in HA gel via iPC injection in a porcine MI model could improve pig cardiac function and cardiomyocyte (CM) proliferation. Here, a pig MI model was created using percutaneous coronary balloon catheter occlusion with C-arm fluoroscopy. Yorkshire pigs underwent video-assisted thoracoscopic surgery for iPC injection of MSC-Exo. Cardiac function studies were conducted using echocardiography (echo) to measure left ventricle ejection fraction (LVEF) and left ventricle fractional shortening (LVFS). Histology and immunohistochemistry (IHC) analyses were performed to investigate CM proliferation. Single nucleus RNA-sequencing (snRNA-sq) analysis was performed to identify key gene features and phenotype changes that may be affected by the MSC-Exo treatment. As a result, the iPC injection of MSC-Exo improved cardiac function, enhanced cardiomyocyte proliferation, and induced phenotype alteration in the pig MI model. Echo depicted significantly enhanced LVEF and LVFS on Day 28 in the MSC-Exo group. Histology showed reduced fibrotic percentage and improved infarct wall thickness. IHC analysis showed a significant increase in CM proliferation. SnRNA-seq gene and pathway enrichment elucidated upregulated CM gene features involved in cell proliferation and ECM interaction. In conclusion, these results demonstrated significant improvements in pig cardiac function and CM proliferation. Interestingly, immature cardiomyocytes of a different phenotype emerged in the MSC-Exo group. These findings provide an unprecedented dataset to facilitate the clinical translation of minimally invasive cardiac repair therapeutics.