tbuckley/cabot-search huggingface dataset:
Abstract Tu080: Unique Physiology of Fibroblast and Immune Cells in the Right Ventricle
Authors: Madeline Burghaze, Zianne Olverson, Trent Sandstrom, Matthew Gorr
Journal: Circulation Research (2024)

Introduction: Failure of the right ventricle (RV) is a main component of the morbidity and mortality of pulmonary hypertension (PH). There exists no specific treatment for RV dysfunction and failure and the only cure for many patients (especially in the case of pulmonary arterial hypertension) remains transplantation. This is partially due to the critical lack of understanding of RV biology; therapeutic strategies that are beneficial for LV failure have worse outcomes when applied to those with RV failure. RV dysfunction is characterized by exaggerated fibrosis and divergent contractile and hypertrophic responses to several drugs when compared to LV dysfunction. Thus, the RV may contain distinct cellular physiology compared to the LV that has high significance for the treatment of PH. Methods: Tissue digests from the RV and LV of Sprague Dawley rats were collected. We utilized digests to collect RNA for RNA-seq, and prepared cells for flow cytometry and fibroblast isolations. Fibroblasts were cultured for proliferation assays and cell signaling studies. Results: We found that the RV and LV have significant differences in expression of immune-related and fibrotic genes. The RV of control rats had an average of four-fold higher density of immune cells, namely macrophages/monocytes, compared to the LV (P&lt;0.05 via paired t-test). Fibroblasts from the RV of control rats, which had a higher proliferation rate and an alteration of metabolic genes than those from the LV (P&lt;0.05 via two-way ANOVA), also had a higher fold-change increase in periostin and CTGF expression upon treatment with TGFβ. Conclusions: The results demonstrate that in comparison to the LV, the RV is made up of a unique population of cells and has a unique capacity for fibrotic response that is reflected in its molecular makeup, which may contribute to its distinct response to PH. Future experiments will focus on determining the molecular mechanisms driving these differences. This knowledge is expected to yield new therapeutic approaches for RV dysfunction and failure occurring with PH, which currently have no specific treatment.
Abstract Tu070: Impact of Hypertrophic Cardiomyopathy in Hospitalizations with Aortic Stenosis : A National Inpatient Sample survey
Authors: Rohit Sekandlapuram, Dhairya Nanavaty, Hima Varsha Voruganti, Bhavyakumar Vachhani, Jayalekshmi Jayakumar, Pradeep Kumar Devarakonda, Sohrab Singh, Nishant Patel, Sujana Sanka, Rishav Sinha, Cesar Ayala-Rodriguez, Priya Hotwani, Sukrut Nanavaty
Journal: Circulation Research (2024)

Background: The management of patients with combined aortic stenosis (AS) and hypertrophic cardiomyopathy (HCM) is tricky. HCM causes a dynamic obstruction, while AS causes a fixed obstruction, both causing a hindrance to left ventricular output. We aim to study the outcomes of hospitalizations with co-prevalent HCM and AS. Methods: We queried the National Inpatient Sample 2018-2020 for adult hospitalizations with AS. This sample was stratified based on the prevalence of HCM. Mortality, arrhythmia prevalence, and acute cardiac complications were compared in aortic stenosis hospitalizations with and without AS. A multivariate regression analysis was performed to study the impact of HCM on mortality, arrhythmias, and other complications in patients with AS. Results: In hospitalizations with aortic stenosis (n=2483854), a total of 11820 had underlying HCM (0.47%). The mean age was 76 years and 64% were females. Hospitalizations with AS and HCM as compared to those without HCM had a higher prevalence of arrhythmias including first degree AV block, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular fibrillation (Table 1). The occurence of cardiogenic shock was also higher in this subgroup. The difference in mortality, acute coronary syndrome, acute heart failure and cardiac arrest was not statistically significant in AS hospitalizations with and without HCM (Table 1). Multivariate regression analysis revealed a higher odds of arrhythmias (OR-1.44; C.I: 1.36-1.62; P&lt;0.001) and cardiogenic shock (OR-1.58; C.I: 1.22-2.06; P&lt;0.001) with HCM in AS hospitalizations. Conclusion: Prior studies have demonstrated worse outcomes in AS patients with pre-existing HCM, especially post TAVI. Our study concludes that HCM was associated with a higher odds of arrhythmias and cardiogenic shock in AS hospitalizations.
Abstract Tu124: The Transcriptional Regulator FOG2S Represses GATA4-ERRα-PGC1α Complex to Decrease Mitochondrial Metabolism
Authors: Sharavana Gurunathan, Tomoya Sakamoto, Donna Conlon, Daniel Kelly, Marie Guerraty
Journal: Circulation Research (2024)

Background: Cardiac transcription factors (CTFs) and coregulators drive the developmental transition from immature to mature cardiomyocytes (CMs). The nuclear receptor estrogen-related receptor (ERR), with coregulator PGC-1α and CTF GATA4, has been shown to serve as a critical role in CM maturation. Friend of GATA 2 (FOG2), a transcriptional coregulator, is crucial for normal cardiac development and exists in 2 isoforms: FOG2 and FOG2S, a shortened isoform lacking the N-terminal repressor domain and more prevalent in developing heart. Little is known about the role of FOG2S. We sought to investigate the mechanisms whereby FOG2S serves as a transcriptional regulator and assess its potential interaction with maturation CTFs. Methods: FOG2S was overexpressed in 8-week-old male C57/BL6 mice and human iPSC-derived cardiomyocytes (iPSC-CMs) using cardiac-specific AAV (cTNT.AAV9). Hearts were processed for RNA-seq and electron microscopy. iPSC-CMs were also treated with 0.1 mM DMOG for 16 h to induce hypoxia, essential for metabolic flexibility, and assessed with Seahorse Bioanalyzer. Hearts and iPSC-CMs were also analyzed for oxidative phosphorylation genes by qRTPCR. Co-transfection studies using a 3XERR-RE upstream of a minimal promoter driving luciferase reporter was performed in HEK293 cells with 3xFLAG-ERRα, PGC-1α-Myc/His-, GATA4-HA-, FOG2-FLAG- and/or FOG2S-FLAG-tagged plasmids. Results: FOG2S mice showed 678 differentially expressed genes (p&lt;0.001, 424 genes up and 254 genes down). Gene set enrichment analysis identified oxidative phosphorylation as the top hallmark pathway, driven by decreased Nduf’s and Cox’s and increased Bnip3, a mitophagy gene. FOG2S hearts had smaller and rounder mitochondria with less cristae. In vitro , DMOG-treated FOG2S iPSC-CMs exhibited decreased basal and maximal respiration and reduction in mitochondrial network. There was a significant 40-80% decrease in mitochondrial gene expression, MFN1, COX10, TIMM21, TOMM22, NDUFA11, NDUFAB1. GSEA for transcription factor targets identified ERRα as the top hit. Luciferase reporter assay for 3XERR-RE activity showed FOG2S inhibited ERRα-PGC1α-GATA4 mediated activation in a dose-dependent manner. Inhibition was also mediated through GATA4 and independent of PGC1α. Conclusion: FOG2S overexpression suppresses oxidative phosphorylation and mitochondrial metabolism by inhibiting GATA4 in the context of ERRα-PGC1α-GATA4 complex. These results suggest that FOG2S modulates CM metabolic maturation.
Abstract Tu086: Repairing nuclear envelope ruptures to ameliorate Lamin-related cardiomyopathy
Authors: Atsuki En, Hanumakumar Bogireddi, Briana Thomas, Alexis Stutzman, Sachie Ikegami, Brigitte Laforest, Omar Almakki, Peter Pytel, Ivan Moskowitz, Kohta Ikegami
Journal: Circulation Research (2024)

Heterozygous loss-of-function mutations in LMNA , encoding nuclear lamina protein Lamin A/C, cause severe adult-onset dilated cardiomyopathy. A prevailing hypothesis posits that LMNA insufficiency causes nuclear envelope structural defects that ultimately cause the disease. However, the mechanisms linking defective nuclear envelopes to cardiomyopathy remain undefined. To determine specific nuclear envelope defects and their consequences, we deleted Lmna in cardiomyocytes in adult mice ( Lmna CKO ). Strikingly, a modest (50%) reduction of Lamin A/C caused widespread localized ruptures of the nuclear envelope in cardiomyocytes (En et al. bioRxiv 2023). The nuclear envelope ruptures did not cause immediate cell death, but accompanied a strong inflammatory response in the heart, prior to fatal cardiomyopathy. We hypothesized that DNA leaked from ruptured nuclei might elicit the cGAS-STING cytosolic DNA sensing pathway of innate immunity. Contrary to this hypothesis, we did not observe cGAS-STING activation in Lmna CKO cardiomyocytes. This lack of cGAS-STING activation was likely due to the near absence of cGAS protein in adult cardiomyocytes. To investigate the mechanism underlying cardiac inflammation in Lmna CKO mice, we conducted time-course single-nucleus RNA-seq. This analysis nominated cardiac fibroblasts as the central mediator of the inflammatory response, receiving ECM-mediated signaling from Lmna CKO cardiomyocytes and recruiting immune cells to the mutant hearts. Finally, we found evidence suggesting that nuclear envelope repair activity counteracts nuclear envelope ruptures in Lmna CKO mice. We found that the envelope ruptured sites co-localized with the ESCRT-III membrane remodeling complex, previously implicated in nuclear envelope repair. We further found that overexpression of DNA-binding protein BANF1 promoted ESCRT-III recruitment to the ruptured sites. We are currently investigating whether facilitated nuclear envelope repair ameliorates cardiomyopathy in Lmna CKO mice. If it does, nuclear envelope repair may be a potential therapeutic strategy for LMNA -related dilated cardiomyopathy.
Abstract Tu072: O-GlcNAcylation underlies the activation of sodium-glucose cotransporter 1 in diabetic hearts
Authors: Vivek Pandey, Sathya Velmurugan, Miao Liu, Sanda Despa
Journal: Circulation Research (2024)

Rationale: Type-2 diabetes (T2D) greatly increases the risk for developing heart failure. Recent evidence indicates that the cardiac expression and function of the sodium-glucose cotransporter 1 (SGLT1) is elevated in disease states, including T2D, leading to structural and functional remodeling of the heart. The mechanisms underlying SGLT1 activation in the diabetic heart are currently unknown. Objective: To investigate if SGLT1 undergoes the O-linked attachment of β- N -acetylglucosamine (O-GlcNAcylation), a post-translational modification that is exacerbated in T2D, and its effect on SGLT1 activity in diabetic hearts. Methods/Results: SGLT1 co-immunoprecipitates with O-GlcNAc in heart homogenates and HL-1 cardiomyocyte lysates. Enhancing global protein O-GlcNAcylation in HL-1 cells via si-RNA-mediated silencing of O-GlcNAcase (OGA), the enzyme that removes O-GlcNAc from proteins, resulted in increased amounts of O-GlcNAc that precipitate with SGLT1. SGLT1 function, measured as the SGLT1-mediated Na + influx, was significantly increased in HL-1 cells with silenced OGA. These data suggest that SGLT1 undergoes O-GlcNAcylation and this modification results in SGLT1 activation. Using rats that express human amylin in the pancreatic β-cells (HIP rats) as a model of late-onset T2D and their wild-type littermates as controls, we found that a larger fraction of SGLT1 co-immunoprecipitates with O-GlcNAc in hearts from T2D rats compared to controls. The SGLT1-mediated Na + influx was larger in myocytes from T2D vs . control rats. Increasing total O-GlcNAcylation with Thiamet-G in control myocytes resulted in larger Na + influx. In reverse experiments, inhibition of O-GlcNAcylation with 6-diazo-5-oxo-L-norleucine crystalline reduced SGLT1-mediated Na + uptake in myocytes from T2D rats. Inhibition of O-GlcNAcylation in T2D myocytes reduced Ca 2+ spark frequency and this effect was significantly less pronounced with SGLT1 blocked. These results suggest that O-GlcNAcylation affects myocyte Na + regulation by activating SGLT1, which contributes to myocyte Na + overload and its downstream effects on sarcoplasmic reticulum Ca 2+ leak in T2D. Conclusion: Exacerbated O-GlcNAcylation underlies SGLT1 activation in diabetic hearts. Preventing O-GlcNAcylation may limit myocyte Na + overload and the frequency of pro-arrhythmogenic Ca 2+ sparks in myocytes from T2D rats.
Abstract Mo100: Predictive Accuracy of Rightward Extrapolation of the Left Ventricular End-Diastolic Pressure-Volume Relationship in Healthy Swine
Authors: Filip Konecny, Ryan Mackey, Emily Hudson, Luke Graser, Brian Weil
Journal: Circulation Research (2024)

Objective: Myocardial stiffness is a primary determinant of left ventricular (LV) diastolic function and can be quantitatively described by the end-diastolic pressure-volume relationship (EDPVR). The EDPVR is traditionally derived by measuring LV end-diastolic pressure (EDP) and volume (EDV) during transient reductions in venous return (preload). However, the accuracy of this approach in predicting changes in LVEDP in response to a rise in LVEDV via rightward extrapolation has not been directly studied. Accordingly, we sought to assess the predictive accuracy of preload reduction-derived EDPVRs in estimating LV diastolic stiffness (ΔLVEDP/ΔLVEDV) in healthy swine. Methods: LVEDP and LVEDV were measured in swine (n=6) at rest and during transient inferior vena cava (IVC) occlusion (reduced preload), transient aortic occlusion (increased afterload), and intravenous phenylephrine (PE; 0.5 mg/kg/hr; increased afterload and preload). Pressure-volume data collected during IVC occlusion were used to generate the EDPVR, the accuracy of which was determined via comparison to measurements of ΔLVEDP/ΔLVEDV during aortic occlusion and PE. Results: The LV diastolic stiffness coefficient was greater when derived via aortic occlusion vs. IVC occlusion (0.057±0.013 vs. 0.022±0.004; p=0.03). As a result, IVC occlusion-derived EDPVRs underestimated the rise in LVEDP during aortic occlusion (7.6±2.2 vs. 13.5±2.1 mmHg; p=0.08). Similarly, ΔLVEDP/ΔLVEDV in response to aortic occlusion (0.96±0.28 mmHg/mL) tended to be higher than that predicted from the IVC occlusion-derived EDPVR (0.44±0.09 mmHg/mL; p=0.12). Compared with aortic occlusion, PE elicited a greater rise in LVEDV (31.5±5.4 vs.18.6±4.2 mL; p=0.08) and LVEDP (20.8±1.3 vs. 13.5±2.1 mmHg; p=0.01) but ΔLVEDP/ΔLVEDV was comparable between each condition (0.78±0.16 mmHg/mL vs. 0.96±0.28 mmHg/mL; p=0.60). However, ΔLVEDP/ΔLVEDV derived from PE tended to be higher than that from IVC occlusion (0.78±0.16 mmHg/mL vs. 0.44±0.09 mmHg/mL; p=0.10). Conclusions: Rightward extrapolation of the EDPVR derived via IVC occlusion underestimates the rise in LVEDP when LVEDV is increased in the normal heart. This was observed with increased afterload as well as when afterload and preload were simultaneously increased via PE. These findings reinforce the importance of assessing the hemodynamic response to increased LV loading directly, rather than extrapolating from EDPVRs created via transient preload reduction.
Abstract Tu004: Global distribution of cardiac exosomes after myocardial infarction
Authors: Xinjie Wang, Xiao Du, Zhishi chen, Wei Yu, Zhongjing Wang, Yanping Chen, Daniel Chang, Isla Mata, Garrett Jensen, Jiang Chang, Weijia Luo
Journal: Circulation Research (2024)

Background: Exosomes’ beneficial effects on the injured hearts show promising results. Understanding the biodistribution and kinetics of cardiac exosomes during myocardial infarction (MI) is crucial for exploring the underlying mechanisms. Aim: We aimed to elucidate dynamic biodistributions of cardiomyocyte-released exosomes in MI hearts at post-MI day 3 and day 14, representing the acute and remodeling stages, respectively. We employed the cardiac exosome reporter mice expressing CD63NanoLuc to track the endogenous cardiac exosomes. Method: The NanoLuc reporter mice underwent MI surgery (n=3-12/group). Reporter expression was induced by tamoxifen injection. To assess post-MI cardiac exosome distribution via circulation, fourteen organs, and plasma exosomes were harvested for luciferase activity quantification at each time point. Bioluminescence analysis was conducted in isolated cardiac fibroblasts, endothelial cells, and leukocytes to profile exosome-mediated paracrine signaling. Result: Plasma exosome luciferase activities were consistent across groups. A decline in bioluminescent levels was observed in all organs at both time points, with significant differences in the pancreas, thyroid, kidney, lung, and thymus (p&lt;0.05). Day 3 post-MI showed increased heart endothelial cell bioluminescence in risk and remote areas (p=0.0007), whereas day 14 showed decreased bioluminescence in cardiac fibroblasts in both areas (p=0.0029 and p=0.0086). Endothelial cells and leukocytes exhibited a ten-fold higher exosome uptake than cardiac fibroblasts. Conclusion: There was a significant decrease in exosome uptake by major organs from the injured heart. Cardiac endothelial cells and fibroblasts demonstrated dynamic exosome uptake changes, with endothelial cells and leukocytes showing notably higher uptake compared to fibroblasts.
Abstract Or108: The role of SARM1 in regulation of immune response in heart failure with preserved ejection fraction
Authors: Azadeh Nasuhidehnavi, Keaton Minor, Christine Light, Chi Fung Lee
Journal: Circulation Research (2024)

Heart failure with preserved ejection fraction (HFpEF) is an unmet medical need. Recent studies have shown that HFpEF is associated with immune dysregulation and decline in nicotinamide adenine dinucleotide (NAD + ) levels. However, the molecular mechanisms linking these factors in HFpEF are not completely understood. Sterile alpha and TIR motif-containing 1 (SARM1) is a NAD + consuming enzyme that may regulate immune response and NAD + metabolism. Here, we investigated the role of SARM1 in HFpEF pathophysiology. We utilized a two-hit diet model to induce HFpEF in mice (HFpEF diet: high-fat diet and L-NAME). Wild-type (WT) mice on HFpEF diet showed progressive decline in diastolic function (e.g. decreased E’/A’, increased relaxation time, IVRT) at 5- and 15-week, associated with unchanged systolic function and increased cardiac hypertrophy. Despite decline in NAD + levels as previously reported in HFpEF hearts, qPCR analysis showed no significant differences in the expression of enzymes involved in NAD + biosynthesis including the salvage, Preiss-Handler and de novo pathways. We employed RNA-sequencing to identify cardiac gene signatures that are associated with HFpEF. Gene ontology analysis showed activation of various immune pathways in HFpEF hearts. Using flow cytometry analysis, we observed around 66% increase in total leukocytes (CD45+) number, along with infiltration of both T cells (CD3+ CD4+/CD8+) and myeloid cell populations (CD11b+) in HFpEF hearts. To understand the role of SARM1 in HFpEF pathogenesis, we subjected global SARM1 knock out (KO) mice to HFpEF diet. SARM1 KO hearts had improved diastolic function and reduced hypertrophy after 15-week HFpEF diet. RNA-sequencing of SARM1 KO-HFpEF hearts showed downregulations of transcripts in immune activation pathways, compared to WT-HFpEF hearts. In summary, our findings suggest that SARM1 may regulate immune activation pathways and promote HFpEF pathogenesis. We plan to determine the intricate relationships between immune dysregulation, metabolic stress, and cardiac dysfunction in HFpEF pathogenesis. The future direction may identify potential avenues for targeted therapeutic interventions aimed at modulating immune responses for HFpEF.
Abstract Tu007: The Impact of Shear-Thinning Hydrogel Delivery on Extracellular Vesicle Cardiac Retention
Authors: Touba Tarvirdizadeh, Mohamed Alaa Mohamed, Stelios Andreadis, Jennifer Lang
Journal: Circulation Research (2024)

Background: Extracellular vesicles (EVs) are essential mediators of intercellular communication. EVs secreted by cardiosphere-derived cells (CDC-EVs) hold promise as vectors in the context of cardiac repair and remodeling through modulation of cardiomyocyte apoptosis and the immune response following injury. Cardiac retention of CDC-EVs is a critical factor influencing their therapeutic efficacy as first-pass uptake and washout from the myocardium remains a variable. We hypothesized that loading CDC-EVs in a shear-thinning, hybrid hydrogel would provide sustained myocardial delivery and reduced EV extraction by the lungs. Methods: The hydrogel system was constructed via a two-step approach utilizing Michael-addition reaction and host-guest complexation. This system incorporates four components: (1) an adamantane-functionalized multi-arm polyethylene glycol, (2) monosubstituted β-cyclodextrin-maleimide, (3) a thiolated hyaluronic acid, and (4) a heparin molecule containing thiol moieties. Following LAD ligation, intramyocardial injections of DiR-labeled EVs or hydrogel-encapsulated DiR-labeled EVs were performed on mice. Animals were euthanized after 24 hours and organs harvested. Whole organ biofluorescence was performed using IVIS Spectrum imaging. Results: Hydrogel-encapsulated EVs exhibited enhanced cardiac retention 24 hours post-MI when compared with EVs without hydrogel (17 ± 4.4 vs. 3.4 ± 0.9, mean radiant efficiency as a % of dose ± SEM, p&lt;0.01 using unpaired two-tailed t-test). Mice treated with hydrogel encapsulated EVs showed reduced EV retention in the lungs compared to controls treated with EVs alone (5.7 ± 0.9 vs. 10.6 ± 1.4, mean radiant efficiency as a % of dose ± SEM, p&lt;0.05 using unpaired two-tailed t-test). Conclusion: Usage of shear-thinning hydrogel as an EV delivery vehicle enhances EV retention in the heart and decreases off-target uptake of EVs following acute MI. This finding suggests that hydrogel delivery may be a promising strategy to improve the therapeutic efficacy of CDC-EVs for cardiac repair.
Abstract Tu133: Cardiac Adaptations and Mitochondrial Protection Through Long Noncoding RNAs Regulation in Mice on a Ketogenic Diet
Authors: Talan Tran, Natalia Noto, Ariana Hernandez, Victoria Pulido-Correa, Chana Vogel, Zachary Lawrence, Shalet James, Iliana Uribe, Robert Speth, Lisa Robison, Narasimman Gurusamy
Journal: Circulation Research (2024)

Background: Heart failure, characterized by a metabolic imbalance, leads to impaired mitochondrial ATP production. Ketone bodies not only serve as an alternate energy source but also mitigate heart failure by reducing cardiac remodeling and inflammation. The role of long noncoding RNAs (lncRNAs) in cardiac remodeling and mitochondrial metabolism is increasingly appreciated, and this study examines the effect of ketogenic diet on cardiac lncRNA regulation and mitochondrial protection. Methods and Results: In a six-month study, 10-week-old male and female C57BL/6J mice were assigned to either a control diet (10% fat, 20% protein, 70% carbohydrate) or a ketogenic diet (Keto; 80% fat, 15% protein, 5% carbohydrate). Data were analyzed using unpaired two-tailed t-tests (GraphPad Prism) and reported as mean ± SE. The keto diet significantly increased blood ketone bodies (n=36/group), indicating ketosis, and led to weight gain as well as a significant decrease in heart mass relative to body weight, suggesting cardiac metabolic adaptation (Fig 1A-B) . The cardiac expression analysis of lncRNAs Anril, Caren, Carmn, Gm15441, Malat1, Miat, and Oip5-as1 via qPCR (n=13/group) revealed significant upregulation of Anril and Malat1 in the Keto hearts ( Fig 1C-D ), indicating their potential regulatory roles under ketogenic conditions. Sex-specific differences were not observed in the lncRNA expressions. Key proteins involved in mitochondrial biogenesis, protection, and metabolic adaptation, including Nrf2 and PGC1α, were significantly increased at both mRNA and protein levels (n=6-10) in the hearts of mice on keto diet ( Fig 1E-H ). Conclusion: A six-month ketogenic diet in mice promotes cardiometabolic adaptations characterized by a reduction in relative heart mass and activation of key proteins involved in mitochondrial biogenesis and protection possibly through lncRNAs Anril and Malat1. These findings shed light on novel molecular targets and the potential of ketogenic diet/ketone bodies in treating heart failure.