tbuckley/cabot-search huggingface dataset:
Abstract Tu111: Effect Of Grandmaternal Diabetes and High Fat Diet on Cardiometabolic Dysfunction in the Second Generation (F2) Newborns
Authors: Prathapan Ayyappan, Tricia Larsen, Abigail Klein, Ty Gandy, Michelle Baack
Journal: Circulation Research (2024)

Infants exposed to diabetic pregnancy are at higher risk of cardiomyopathy at birth and early onset cardiovascular disease (CVD) as adults. We have previously used a rat model to demonstrate that a combination of high fat diet (HFD) and late gestational diabetes causes impaired cardiac function in first generation (F1) newborn and adult offspring via mitochondrial dysfunction and metabolic stress. The objective of this study was to determine whether grandmaternal HFD and diabetes can cause inheritable CVD in second generation offspring (F2), even if the first generation is cross fostered during lactation and fed a standard control diet throughout life. Myocardial function in the F2 newborns was assessed using echocardiography and mitochondrial function in the isolated neonatal cardiomyocytes (NRCM) was assessed using extracellular flux analyses. Exposed F2 newborns had a higher birthweight (p=0.03) and blood glucose (p&lt;0.0001) compared to control newborns and F1 generation parents (p=0.0002 and p&lt;0.0001). Of significant interest, exposed F2 newborns had higher heart rates (p&lt;0.0001), heart:body weight ratios (p&lt;0.0001) and systolic dysfunction which was evident from lower ejection fraction (p&lt;0.0001) and fractional shortening (p&lt;0.0001) compared to control F2 newborns. While control and combination exposed NRCM had similar basal respiration, exposed F2 NRCM had a higher proton leak (p=0.0004) which indicates damage to the inner mitochondrial membrane and/or electron transport chain complex. There was also shift to higher glycolysis at baseline (p=0.005), but blunted glucose-induced glycolytic rate (p=0.04) in F2 newborns compared to controls. Overall results suggest that maternal HFD and diabetes causes multigenerational programming of cardiometabolic dysfunction in F2 offspring despite the F1 parent having normal diet, weight, and euglycemia during the pregnancy.
Abstract Mo103: Aberrant Trans- and De- Nitrosylation Underpins Nitrosative Stress in Cardiometabolic HFpEF
Authors: Zhen Li, Natalie Gehred, Tatiana Gromova, Kyle LaPenna, Thomas Sharp, Jingshu Chen, Smitha Shambhu, Xiaoman YU, Traci Goodchild, Martin Borch Jensen, Thomas Vondriska, David Lefer
Journal: Circulation Research (2024)

Background: Heart failure with preserved ejection fraction (HFpEF) is among the leading causes of cardiovascular mortality and morbidity. Recent reports suggest excessive myocardial protein S-nitrosylation (-SNO), a hallmark of nitrosative stress, contributes to HFpEF pathophysiology. However, the role of transnitrosylases, enzymes that induce protein-SNO, or denitrosylases, enzymes that eliminate protein-SNO, have not been investigated in the context of HFpEF. Research Questions and Goals: We sought to investigate the regulation of protein nitrosylation dynamics in a rat model of cardiometabolic HFpEF. Methods: Echocardiographic assessment, invasive hemodynamic measurements, and exercise testing were conducted in WKY or ZSF1 obese (Ob) rats to evaluate HFpEF severity. Nitric oxide (NO) bioavailability and protein-SNO levels were determined in the heart tissue. Endothelial-dependent vascular reactivity was assayed to further evaluate NO signaling. In parallel, single-cell (sc) RNA sequencing was performed to determine the transcriptional changes in trans- and denitrosylases, as well as NO synthases. Results: We observed progressive deterioration in LV diastolic function (significantly elevated E/e’ and LV end-diastolic pressure) and exercise performance in ZSF1 Ob when compared to WKY controls. Notably, ZSF1 Ob rats exhibited an age-dependent elevation in protein-SNO levels, despite significant reduction in NO bioavailability and signaling. Targeted sc transcriptomic analysis revealed significantly elevated expression of transnitrosylases such as hemoglobin subunit α and β in cardiomyocytes, endothelial cells, and cardiac fibroblasts from ZSF1 Ob hearts. In contrast, significantly reduced expression of denitrosylases such as thioredoxin 2 was found in the ZSF1 Ob cardiomyocytes. No change was observed in expression of NO synthases (nNOS, iNOS, eNOS). Conclusion: Herein, we demonstrate a profound disconnect between insufficient NO bioavailability and nitrosative stress in ZSF1 Ob rat model of HFpEF. Our data suggests the pathological accumulation of nitroso - proteins, may be attributed in part to the derangement of transnitrosylases and denitrosylases expression. Restoration of physiological protein nitrosylation dynamics may represent a novel therapeutic approach for HFpEF, and warrants further investigation.
Abstract Tu136: HIF-1α a novel therapeutic target to reduce Cardiac Ischemia Reperfusion Injury during AMI
Authors: Lija Swain, Lara Reyelt, Xiaoying Qiao, Shreyas Bhave, Kay Everett, Elena Mahmoudi, Navin Kapur
Journal: Circulation Research (2024)

Acute myocardial infarction (AMI) is a major cause of mortality worldwide. In preclinical models of AMI, using a trans-valvular pump (TVP) to reduce left ventricular (LV) workload for 30 minutes before reperfusion reduces infarct size by 50%. The mechanisms underlying the cardioprotective effect of LV unloading remain poorly understood. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive transcription factor that activates cardioprotective signaling pathways, improves cell survival and mitochondrial function during myocardial ischemia. We hypothesized that LV unloading limits myocardial injury by activating hypoxia inducible factor 1-a (HIF-1α). To explore the effect of LV unloading on HIF-1α stabilization during ischemia, we performed left anterior descending artery (LAD) occlusion for a total of 120 minutes in adult swine in the presence and absence of LV unloading and further 180 minutes of reperfusion was performed following 120 minutes of LAD occlusion. Trans-valvular unloading activation significantly decreased infarct size both during ischemia (IS/AAR: 4.78±4 % vs 1.5±3%) and post reperfusion when compared ischemia alone and IR alone groups (36.04±8.39 % vs 16.02±3.52 %, p&lt;0.0001) respectively. Interestingly, HIF-1α stabilization is significantly reduced with LV unloading during ischemia and significantly increased post reperfusion in the infarct zone of the swine model of AMI. To test whether HIF1a is necessary for cardioprotection with LV unloading, adult swine were treated with intracoronary delivery of the HIF-1α inhibitor (2-methoxyestradiol; 2ME) before reperfusion. Compared to TVP activation for 30 minutes before reperfusion, addition of 2ME abolished the cardioprotective effect of TVP resulting in increased infarct size (16.03% vs 35.86% p&lt;0.03) and decreased HIF-1a stabilization. Stabilizing HIF-1α post-reperfusion by using a well know HIF-1a stabilizing agent Roxadustat, immediately before reperfusion significantly decreased infarct size in both with and without TVP groups compared to IRI alone. Treatment with Roxadustat also preserved mitochondrial function and increased RISK signaling. We report the novel finding that stabilizing HIF-1a activity before reperfusion plays a critical role in reducing Infarct size in preclinical model of AMI.
Abstract Tu117: Unraveling the Role of Mitochondrial Ribosomal Protein L7/L12 (MRPL12) in Diabetic Cardiomyopathy
Authors: Amit Rai, Shridhar Sanghvi, Suriya Muthukumaran Natrajseenivasan, Dhananjie Chandrasekera, Ashlesha Kadam, Ioannis Kyriazis, Sreejit Gopalkrishna, Dhanendra Tomar, Devasena Ponnalagu, Mahmood Khan, Harpreet Singh, Prabhakara Nagareddy, David Goukassian, Rajesh Katare, Venkata Garikipati
Journal: Circulation Research (2024)

Diabetic cardiomyopathy (DMCM) is a major cause of death in diabetic patients. Emerging evidence shows that mitochondrial dysfunction contributes to heart failure in diabetes. However, the molecular mechanisms of mitochondrial dysfunction mediating heart failure in diabetes are still poorly understood. The current study aimed to investigate the role of mitochondrial ribosomal protein L7/L12 (MRPL12) in human and mouse models of type II diabetes (db/db mice, and high-fat diet fed (HFD) mice) with or without induction of myocardial infarction (MI). Mitochondrial respiration was measured by using sea horse and mitochondrial membrane potential was measured by using confocal microscopy. Data was analyzed by using the mean of the groups was compared using a student t-test (for 2 groups) and ANOVA. We found increased MRPL12 levels in diabetic patients with ischemic heart disease compared to non-diabetic patients. Further we found elevated MRPL12 levels in the LV tissue of HFD fed mice with MI compared to low-fat diet-fed mice with MI. With the overexpression of MRPL12 under hyperglycemic conditions, the level of oxidative phosphorylation (OXPHOS) was found downregulated, but cellular ATP and human cardiomyocyte cell death remained unchanged, However, there was notable impairment in mitochondrial membrane potential (MMP) in hyperglycemia condition, along with changes in basal respiration oxygen consumption rate (OCR) and maximal respiratory capacity OCR. Overall, our results suggest MRPL12 may have a compensatory role in the diabetic hearts with ischemic heart disease. Therefore, our finding proposes new insights into the role of MRPL12 in the pathophysiology of MI in diabetes.
Abstract Tu138: Tandem Mass Tagging (TMT)-based Identification of Proteome Signatures for Ischemia-Reperfusion Injury in Swine
Authors: Sini Sunny, Jiacheng Sun, Sayed Aniqa, Gregory Walcott, Jianyi Zhang, Rajasekaran Namakkal-Soorappan
Journal: Circulation Research (2024)

Background: The composition of proteins in blood plasma mirrors the physical changes occurring in the course of disease pathogenesis. Currently available clinical markers are insufficient to predict the actual damage and the redox changes in response to ischemia. Hence, we identified novel redox markers for ischemia/reperfusion (I/R) in swine using TMT-proteomics. Methodology: We employed TMT-10plex isobaric labeling-based quantitative proteomics to track the plasma proteome in Sus Scorfa pigs subjected to surgical I/R at different time points. Plasma samples were collected before ischemia, at 1-hr after ischemia (baseline), and 4-hr, 24-hrs, and 7 days following reperfusion. Results: An average of 4853 spectra and a total of 457 proteins were identified, ensuring a 1% false discovery rate for peptides and proteins with at least two distinct peptides. Pre-ischemia plasma samples served as the control group in all the analyses. TMT analysis revealed temporal changes in the plasma proteome with a prominent shift at 4 hours after I/R insult. To investigate the significantly changed proteins (&gt;1.5 fold), a temporal analysis was carried out. Notably, endopin-1, a serpin protein family member, and fibronectin B were detectable in the plasma following 4 hours of ischemia-reperfusion, indicating the release of these proteins in the circulation during the ischemia-reperfusion. A positive correlation was observed between the redox proteins (i.e., catalase and glutathione peroxidase) with the serpin proteins in the plasma. Biochemical analysis of circulating glutathione, a small-molecular antioxidant, revealed a reductive redox after 60 minutes of Ischemia (hypoxic condition) but this was shifted to an oxidative milieu at 4hrs following reperfusion (hyperoxia) in the adult pigs subjected to I/R insult. Interestingly, we noticed a significant increase in GSH levels and a decrease in catalase levels at 24 hours following I/R, suggesting a compensatory biochemical response in association with repair after I/R insult/injury in the heart. These results correlated with the increased circulating LDH levels indicating the rate of tissue damage following I/R. Conclusion: The present study reveals the presence of a previously unexplored Serpin protein member, endopin-1, during I/R. Understanding the kinetics of endopin-1 expression along with the shift in redox state can help unravel its role in the progression and resolution phases of I/R injury.
Abstract Tu075: Cardiac macrophages expressing CD206 and IL-4Ra are required for adverse LV remodeling in HF
Authors: Qiongxin Wang, Ameen Ismahil, Gregg Rokosh, Tariq Hamid, Guihua Zhou, Yujie Zhu, Sumanth Prabhu
Journal: Circulation Research (2024)

Cardiac macrophages significantly expand in chronic heart failure (HF). We tested the hypothesis that CD206 + macrophages expressing interleukin (IL)-4Ra in the failing heart are key drivers of left ventricular (LV) remodeling and ischemic cardiomyopathy. Cardiac macrophages were profiled using flow cytometry in adult male C57BL/6 (WT) mice following non-reperfused myocardial infarction (MI) to induce HF or sham operation. CD206 + macrophages progressively expanded in post-MI hearts during the progression of LV remodeling and comprised ~85% of macrophages at 8 w. These macrophages were exclusively proliferative and predominantly C-C motif chemokine receptor (CCR2) – and major histocompatibility complex (MHC)II hi in failing hearts, with the majority (92%) of CD206 + CCR2 – macrophages expressing LYVE-1, an embryonically-derived resident macrophage marker. Nearly half of cardiac CD206 + macrophages expressed IL-4Ra; the abundance of CD206 + IL-4Ra + directly correlated with LV dysfunction and fibrosis. Intramyocardial adoptive transfer of IL-4-polarized bone marrow derived CD206 + macrophages induced progressive LV dilation, dysfunction and fibrosis over 4 w in naïve recipient mice. To evaluate the role of CD206 + IL-4Ra + macrophages in LV remodeling, we used male and female LysM CreERT2 ;IL-4Ra F/F mice that allow for inducible myeloid-specific IL-4Ra gene deletion. Administration of tamoxifen from at 4 to 10 w post-MI (in established HF), effectively deleted IL-4Ra in cardiac macrophages and significantly reduced CD206 + macrophage abundance and proliferation in the remodeling heart. Myeloid-specific IL-4Ra deletion further prevented LV remodeling progression, improved fibrosis and neovascularization, and alleviated LV systolic dysfunction, while suppressing expansion of cardiac immune cells and blood Ly6C high monocytosis. We conclude that an expanded and proliferative population of CD206 + IL-4Ra + macrophages primarily derived from resident macrophages are key mediators of pathological LV remodeling and fibrosis. Inhibition of CD206 + macrophage IL-4Ra signaling may be a fruitful therapeutic approach to alleviate disease progression in HF.
Abstract Tu082: Novel Structural and Biochemical Effects of Nexilin Associated Hypertrophic Cardiomyopathy
Authors: Harshil Chittora
Journal: Circulation Research (2024)

Hypertrophic cardiomyopathy is primarily a genetic disease that results in abnormal cardiac muscle phenotypes characterized by ventricular hypertrophy, fibrosis, and contractile dysfunction. Both sarcomere structural and signaling genes are associated with HCM. Among various genes, one of the implicated genes for HCM is Nexilin (NEXN). Nexilin is an F-actin binding protein widely expressed in muscle cells and localized at sarcomere and T-tubules. It is known to have a surprising role in insulin signaling. The role of Nexilin mutations is poorly studied. We hypothesized that Nexilin missense variants in genetically engineered human pluripotent stem cells (hPSCs) perturb essential cardiac metabolic signaling pathways leading to HCM. In our Indian HCM cohort, we identified seven Nexilin mutations through exome sequencing and categorized them as pathogenic per ACMG/AMP classification. A representative novel mutant in Nexilin p.Q131T was introduced in hPSC with the CRISPR-Cas9 knock-in method and was differentiated into cardiomyocytes, recapitulating patient-specific heterozygous mutation. Our data shows that Nexilin p.Q131T causes an increase in cell size and activation of fetal gene transcriptional programs in hPSC-derived cardiomyocytes. Global transcriptomics was performed to understand transcriptional changes and investigate further. We observe the significant activation of insulin-related signaling pathways, including AKT/MTOR and MAPK, confirmed by immunoblotting. Akt-mTOR and MAPK cascades are well-known to be regulated by IRS-1 signaling. Our studies show hyperactivation of these cascades, suggesting IRS-1 involvement in the pathogenesis. Nexilin and IRS-1 interaction were probed and found to be perturbed, hence causing higher activation of IRS-1 and its downstream targets. In addition, Nexilin wild type and mutant protein structure-functional analysis were performed with purified proteins. Using cryo-EM structural analysis, we identified unique F-actin binding sites for Nexilin for the first time, and the mutant p.Q131T showed decreased binding affinity to F-actin. We report Nexilin's high-resolution cryo-EM structure and a novel metabolic signaling mechanism where mutations in Nexilin cause dysregulation of IRS-1 signaling in the gene-edited cardiomyocytes, leading to HCM pathogenesis.
Abstract Tu074: A Potential Link Between Stress Kinase JNK2 and AKAP-1 in Catecholamine-Induced Acute Heart Failure
Authors: Aaryan Kohli, Jiajie Yan, Yuanyuan Cao, Dan Bare, Xun Ai
Journal: Circulation Research (2024)

Takotsuba Syndrome (TTS) is a type of emotional/physical stress-induced heart failure (HF). Stress-elevated catecholamines activate adrenergic signaling. Cardiac A-Kinase Anchoring Protein-1 (AKAP1) is known to regulate the adrenergic signaling via protein complex formation and phosphorylation. We recently discovered that activation of the stress response kinase JNK2 is critical in HF onset. Whether AKAP1 is involved with stress-activated JNK2 and HF onset remains completely unknown. Isoproterenol (Iso; synthetic catecholamine) effects on JNK2 activation were assessed in left ventricles (LV) from Iso-treated wildtype (WT) mice (67 mg/kg i.p., 2 days) and in heterologous HEK-RyR2 cells (inducible cardiac ryanodine receptor-2; myocyte mimic; 5 mM Iso, 24 h). A JNK2 effect on cardiac function was reflected by cardiac output (CO) using echocardiography in cardiac-specific MKK7D (inducible overexpression of active MKK7D; a JNK upstream activator) and MKK7D-JNK2KD (50% JNK2 knockdown in MKK7D) mice. The AKAP1-JNK2 link was assessed using immunoprecipitation (IP) and immunoblotting in tGFP -JNK2 and/or FLAG -AKAP1 transfected HEK293 cells. Iso-WT LV had increased JNK phosphorylation (JNK-p, activated) and reduced SERCA2 (a hallmark of HF) vs controls. Likely, MKK7-induction in MKK7D LV increased JNK2 and JNK-p (vs WT-littermates; p&lt;0.05, n=5,4), which led to reduced CO by 68% (n=5,6, p&lt;0.01) and downregulated SERCA2 by 79% (p&lt;0.01, n=4,8), also evidenced by preserved CO and SERCA2 in MKK7D-JNK2KD mice (50% ablated JNK2; n=9). Moreover, Iso treatment in HEK-RyR2 cells activated JNK2, but not JNK1, compared to sham controls. Intriguingly, we found that JNK2 was associated with AKAP1, given the co-IP of tGFP -JNK2 with anti- FLAG antibody pulldown of FLAG -AKAP1 co-transfected HEK293 cells (n=3). Further, overexpressed FLAG -AKAP1 increased the phosphorylation of co-transfected tGFP -JNK2 as well as endogenous JNK (p&lt;0.01 &amp; p&lt;0.001, n=3,3), while the notable JNK downstream target c-Jun also showed increased phosphorylation (c-Jun-p; p&lt;0.05, n=3,3), supporting a previously unrecognized role for AKAP1 in JNK2 activation. In total, our findings suggest that stress activates JNK2 via an adrenergic-AKAP1 activation pathway to drive HF/TTS onset.
Abstract Tu112: The Outer Mitochondrial Membrane Protein Mtch2 Regulates Cardiac Metabolic Homeostasis and Body Mass
Authors: Marisa Stachowski, Tanner Monroe, Michele Hadhazy, Ewa Bomba-Warczak, Jeffrey Savas, Megan Puckelwartz, Elizabeth McNally
Journal: Circulation Research (2024)

Introduction: MTCH2 is an outer mitochondrial membrane protein insertase and variants in MTCH2 associate with human heart failure and obesity. Hypothesis: Lower levels of MTCH2 predispose the heart to stress. Methods and Results: Cardiomyocyte-specific Mtch2 KO ( cMtch2 KO) mice were generated and develop systolic dysfunction accompanied by increased fibrosis and elevation of heart failure markers ( n =6). Prior to the development of cardiac dysfunction male cMtch2 KO mice maintain a leaner body mass compared to controls, consistent with the idea that cardiac MTCH2 drives whole body energy utilization. We hypothesize the increased energetic demand of maintaining cardiac function in younger animals shifts energy expenditure and results in lower fat mass. We found that young, pre-cardiomyopathic cMtch2 KO mice were sensitized to stress. When young cMtch2 KO mice were challenged to an acute dosing regimen of isoproterenol, compared to controls, hearts from cMtch2 KO mice failed to respond with physiological hypertrophy and animals could not maintain body mass ( n =7). We assessed mitochondrial function in cMtch2 KO mice. Isolated cMtch2 KO cardiomyocytes loaded with Mitotracker green and TMRE had reduced mitochondrial membrane potential compared to control ( n =20 cells/mouse, 3 mice/group). In the presence of glucose, oxygen consumption rates were reduced in cMtch2 KO heart tissue ( n =6), and targeted metabolomics of cMtch2 KO ventricle exhibited an accumulation of palmitate ( n =4), indicating cMtch2 KO hearts do not efficiently utilize glucose and fatty acids. To identify changes in the mitochondrial proteome we performed mass spectrometry on isolated mitochondria from control and cMtch2 KO mice ( n =4). Overall, proteins associated with fatty acid beta oxidation and pyruvate metabolism were reduced in abundance in cMtch2 KO hearts compared to control. Additionally, three potential insertase target proteins were reduced, confirming a critical role for MTCH2 in mitochondrial health. Conclusion: MTCH2 is vital for maintaining normal mitochondrial function. Reduction of MTCH2 sensitizes the heart to stress, resulting in impaired mitochondrial, sarcomere, and global heart function with effects on body composition.