tbuckley/cabot-search huggingface dataset:
Abstract Tu043: Gut Microbial Metabolite Phenylacetylglutamine Leads to Cardiomyocyte Hypercontractility and Vascular Endothelial Cell Activation
Authors: Zhen Li, Aline Zaparte, Xiaoming Fu, Xinmin Li, David Wong, aaron gibson, Kiersten Gorse, Zeneng Wong, Stanley Hazen, David Lefer, Pearl Quijada, Cat Makarewich, Thomas Sharp
Journal: Circulation Research (2024)

Background: Numerous gut microbial metabolites including phenylacetylglutamine (PAGln) are associated with increased cardiovascular disease risk and mortality. However, little is known about the cellular-specific perturbations by which PAGln may drive cardiovascular dysfunction. Aims: To understand if elevated PAGln leads to cardiovascular dysfunction and what direct cardiac- and vascular-specific pathophysiology is occurring. Methods: Herein, we subject C57Bl/6N male mice to pharmacological increases in circulating PAGln (50mg/kg) or vehicle twice daily for 20 days. We performed echocardiography, invasive hemodynamics, and vascular reactivity assays. We also performed ex vivo cardiomyocyte cell physiology experiments in the presence or absence of PAGln. Moreover, to understand vascular effects we subjected endothelial cells to PAGln and looked at expression of proinflammatory and cell adhesion molecules. Results: We first performed LC-MS/MS analysis demonstrating significant elevation in PAGln levels in multiple tissues compared to vehicle. There was no significant alteration in cardiac structure and function through echocardiographic analysis. Invasive hemodynamic assessment of systemic blood pressure showed no change, however left ventricular filling pressures were significantly elevated in PAGln group. Aortic rings subjected to varying concentrations of acetylcholine in the PAGln-treated animals were significantly impaired compared to vehicle controls. Given the elevated filling pressures and aberrant vascular endothelial relaxation we measured nitrite levels. Nitrite was significantly reduced in the plasma, cardiac, and liver tissue in PAGln group. Cardiomyocyte fractional shortening was significantly increased compared to baseline and equivalent to b-adrenergic agonism. PAGln hypercontractility was not inhibited with adrenergic antagonism. Vascular endothelial cells which were exposed to PAGln had an increase in expression of proinflammatory and cell adhesion molecules versus vehicle. Conclusion: Our data demonstrates that PAGln drives cardiovascular dysfunction through cardiomyocyte hypercontractility and inducing vascular coronary endothelial cell activation in vitro .
Abstract Tu131: Counteracting Cardiac Ischemia and Reperfusion Injury: the role of Sialidase Neu3
Authors: Marco Piccoli, Simona Coviello, Rossana Borella, Ivana Lavota, Federica Cirillo, Andrea Ghiroldi, Carlo Pappone, Luigi Anastasia
Journal: Circulation Research (2024)

Coronary reperfusion procedures are crucial for restoring blood flow to the heart tissue after an acute myocardial infarction. However, they also lead to ischemia and reperfusion injury (IRI), which exacerbate the damage and promote heart failure. Despite the urgent need for cardioprotective strategies against IRI, none have been clinically implemented, emphasizing the need for a comprehensive understanding of the pathophysiology of IRI. Our research team found that sialidase Neu3, an enzyme responsible for the removal of sialic acid from glycosphingolipids, is modulated during IRI in vivo. Constitutive overexpression of Neu3 in rat cardiomyoblasts was shown to attenuate IRI through activation of the reperfusion injury salvage kinase (RISK) and HIF-1α signaling pathways. To further investigate the role of Neu3 in promoting cardioprotection, in this study we developed an inducible Neu3 overexpression model in human cardiac cells and mice. Inducible upregulation of Neu3 significantly improved cell resistance and reduced oxidative stress in AC16 cells exposed to IRI in vitro. These effects were attributed to Neu3-mediated maintenance of mitochondrial membrane potential, which was impaired in control cells. When looking at the upregulated genes exclusively in cells overexpressing the sialidase Neu3, RNAseq analysis revealed the predominant activation of MAP kinases typical of the RISK pathway. We also generated, for the first time, αMHC-Cre/LSL-Neu3 mice overexpressing Neu3 in an inducible and cardiomyocyte-specific manner. These mice showed no significant differences in cardiac morphology and functionality compared to wild-type animals. However, the Neu3-overexpressing mice exhibited a significant reduction in infarct size and improved cardiac functionality after surgical induction of IRI. These results suggest that Neu3 is a promising target for improving cardioprotection and attenuating the incidence and severity of myocardial infarction.
Abstract Or105: Constitutive Deletion of the Obscurin Ig58/59 Domains Induces Structural and Electrophysiological Remodeling in Atria
Authors: Annie Brong, Alyssa Grogan, Humberto Cavalcante Joca, Liron Boyman, Aaron Kaplan, Christopher Ward, Maura Greiser, Aikaterini Kontrogianni-Konstantopoulos
Journal: Circulation Research (2024)

Introduction: Obscurin is a giant cytoskeletal protein that supports muscle development, tethers intracellular compartments and regulates contraction. In the ObscnΔIg58/59 mouse model, expressing obscurin lacking Immunoglobulin (Ig) domains 58 and 59, aging males exhibit irregular heart rhythm with prominent atrial fibrillation, atrial enlargement, and progressive remodeling of the ventricles. A mechanistic basis for the emergence of arrhythmia early on could not be identified in ObscnΔIg58/59 ventricles, suggesting that the atria are preferentially impacted by deletion of the obscurin Ig58/59 module prior to the ventricles. Hypothesis: We hypothesize that Ig58/59 deletion elicits unique structural, electrical, and functional consequences in the atria preceding ventricular maladaptation. Aims: I. Examine the structural organization of ObscnΔIg58/59 atria II. Assess Ca 2+ handling in isolated atrial cardiomyocytes and determine molecular alterations. Methods: Electron microscopy and super resolution microscopy were utilized to visualize sarcomeric ultrastructure and the transverse-axial tubule (TAT) network, respectively. Ca 2+ handling activity and synchrony were also resolved, while Phos-Tag gels were used to quantify T-cap phospho-species. Results: ObscnΔIg58/59 atria exhibited misalignment of Z-disks. Spontaneous and stimulated Ca 2+ cycling behavior were [AB1] differentially disrupted in atrial cardiomyocytes in 6- and 12-month ObscnΔIg58/59 males. Relatedly, atrial cells showed an age-dependent deterioration in TAT architecture. Finally, as a function of aging, ObscnΔIg58/59 atria displayed alterations in the expression and phosphorylation of T-cap, a Z-disk protein implicated in the integration of t-tubules with the sarcomeric cytoskeleton. Conclusions: The structural and electrical alterations that arise in ObscnΔIg58/59 atria precede ventricular dysfunction and coincide with the emergence of atrial fibrillation. Collectively, our work indicates that the atria are principally affected by Ig58/59 elimination, instigating arrhythmias and morphological alterations with age. The ObscnΔIg58/59 mouse model has thus emerged as a proxy for atrial cardiomyopathy.
Abstract Or104: Targeting Tropomyosin Overlap Flexibility via Small Molecule Intervention in a Murine Dilated Cardiomyopathy Model
Authors: Catherine Vasquez, Melissa Lynn, Jil Tardiff
Journal: Circulation Research (2024)

Familial dilated cardiomyopathy (DCM) is a genetic heart disorder characterized by enlargement of one or both ventricles, rendering the heart unable to pump blood efficiently. Mutations in cardiac thin filament (CTF) proteins have been associated with characterized clinical manifestations of DCM. Genetic segregation identified a mutation in α-Tropomyosin (Tm) at residue 230 (D230N-Tm) in two unrelated, multigenerational families linked to severe, early onset DCM. To meaningfully link genotype to phenotype our group sought to investigate the effects of D230N-Tm on the biophysical structure of Tm filament. We showed that D230N-Tm caused a compaction of the cardiac Troponin T (cTnT)–Tm overlap region accompanied by a decreased in flexibility of the Tm filament. Given the altered biophysical structure we investigated whether we could target this decrease in flexibility via small molecule intervention and improve function. Computational modeling and biophysical experiments identified small molecule 4-Hydroxy Duloxetine β-D-Glucuronide (Z06) shown to improve compaction of the cTnT-Tm overlap and restore flexibility of the Tm filament. We hypothesized that the decrease in flexibility of Tm impairs its ability to shift through its different conformational states, leading to impaired crossbridge formation. To investigate whether Z06 improves myofilament function, we performed an NADH-coupled ATPase assay using isolated myofibrils from our D230N-Tm transgenic mice and compared them to Non-Transgenic (NTg) littermates. ATPase activity was measured at saturating calcium (100uM) in the presence (250uM) and absence (0uM) of Z06. In the absence of Z06, D230N-Tm exhibited a decrease in ATPase activity (1.793±0.203 umol/min) compared to NTg littermates (5.420±0.562 umol/min), a common trend in DCM models. In the presence of 250uM Z06, D230N-Tm ATPase rates improve to levels comparable to NTg mice (4.816±0.544 umol/min). Moving forward, we will perform calcium titrations, allowing us to investigate if Z06 can restore cooperativity of myofilament activation. Additionally, we will test if the restorative effects of Z06 are present at the myocellular level, and if so, we will optimize delivery to test in vivo effects of Z06 in our D230N-Tm mouse model.
Abstract Tu068: Calmodulin Kinase II is a Mutation-Specific Driver of Disease in Hypertrophic Cardiomyopathy
Authors: Garrett Hauck, Catherine Vasquez, Melissa Lynn, Matthew Klass, Paul Langlais, Shanna Hamilton, Jil Tardiff
Journal: Circulation Research (2024)

In the heart, Ca/Calmodulin Kinase IIδ (CaMKIIδ) functions to maintain electromechanical and calcium homeostasis. Post-translational modifications (PTMs) of CaMKIIδ render its activity autonomous of Ca/CaM. In hypertrophic cardiomyopathy (HCM), increased levels of autonomous CaMKIIδ are linked to disease progression. We have shown that the pathogenic role of CaMKIIδ in HCM is mutation-specific: autonomous CaMKIIδ is elevated in cardiac troponin T (cTnT)-R92W mice, but not in cTnT-R92L mice. These results pose a clinically relevant and critical question: what is the trigger for CaMKIIδ dysregulation in HCM, such that it is only found with certain mutations? We hypothesize that CaMKIIδ dysregulation results from distinct modifications in thin filament (TF) biophysical properties altered by point mutations. cTnT-R92W TFs display faster calcium dissociation kinetics compared to wild type TFs, whereas cTnT-R92L TFs have slower dissociation kinetics, thus we propose accelerated calcium dissociation kinetics as a mutation-specific trigger of CaMKIIδ dysregulation. To test this, we will use mass spectrometry following CaMKIIδ immunoprecipitation to assess the levels of phosphorylation at Thr-287 and oxidation at Met-281/282 in mice expressing the R94H, I79N, or R92W mutations in cTnT, which exhibit differing calcium dissociation kinetics. Preliminary data shows that CaMKIIδ PTMs can be readily detected. We will also use the CaMKIIδ biosensor CaMKAR in cardiomyocytes isolated from these mice to evaluate CaMKIIδ activity. We have shown that genetic inhibition of CaMKIIδ in cTnT-R92W mice improves diastolic function and atrial remodeling. We also aim to test the efficacy of the small molecule CaMKIIδ inhibitor ruxolitinib (rux) in cTnT-R92W mice. Two-week treatment of these mice with rux improves systolic and diastolic function, and has no effect in nontransgenic controls, implicating small molecule inhibition of CaMKIIδ as a potential therapeutic option in HCM. To continue these studies, we will explore changes in calcium handling in the three mouse models to further establish potential mechanistic pathways for CaMKIIδ dysregulation in HCM and will extend rux treatment to longer timepoints to further evaluate its efficacy as an HCM therapeutic.
Abstract Tu059: Single-Nucleus Transcriptomics Demonstrates Endothelial Cell Expansion in Failing Human Right Ventricles
Authors: Ivan Kuznetsov, Kristina Li, Bridget Simonson, Mark Chaffin, Yasmine Guedira, Kenneth Bedi, Kenneth Margulies, Patrick Ellinor, Zoltan Arany, Jonathan Edwards
Journal: Circulation Research (2024)

Background: Right ventricular failure (RVF) is most commonly observed as a sequela of left ventricular failure (LVF)—for which it more than doubles the risk of mortality. Moreover, isolated RVF is the most common cause of death in pulmonary hypertension and is a leading cause of major adverse events in systemic right ventricle congenital heart diseases. Therapies which effectively treat LVF show poor efficacy for RVF. For example, beta blockade, a cornerstone of LVF therapy, has no efficacy in RVF. Therefore, there is a need for broader exploratory research to identify pathways which are dysregulated in RVF and which could serve as targets for future therapies. Methods/Results: To this end, we performed single-nucleus RNA sequencing (N=11) on RV myocardium from nonfailing or dilated cardiomyopathy (DCM) hearts subgrouped by preserved systolic and diastolic RV function (pRV) or RVF. After cell-type assignment and differential expression analysis, we find a progressive upregulation of pro-angiogenic signaling in vascular endothelial cells (ECs) from nonfailing to pRV and RVF. There is a concomitant expansion of the EC pool from nonfailing to pRV and RVF (EC percentage 5%, 9%,15% for NF, pRV, and RVF; p &lt; 0.05 for one-way ANOVA). We find increased HIF-mediated and VEGF-mediated signaling in these ECs, which may be mediating this expansion. Surprisingly, there is also increased expression of genes regulated by type 1 interferon signaling, which is thought to be anti-angiogenic. Discussion: In summary, we have conducted a single-nuclei transcriptomic study of human RVF and found evidence for increased angiogenic signaling and EC expansion. These findings are significant, as the balance of pro-angiogenic and anti-angiogenic factors in RVF is still unclear, with studies in animal models showing conflicting results in terms of changes in macro/microvasculature in RVF. Here, we provide evidence that in human RVF the balance tends to lead toward a pro-angiogenic phenotype, even in dysfunctional RVs. Orthogonal studies to validate the causal nature of these observed changes in pathogenesis of RVF are currently ongoing.
Abstract Tu054: Deficiency or targeting inhibition of histone lysine demethylase KDM5B <i>in vivo</i> for potential therapeutic effects on both HFrEF and HFpEF
Authors: Wen Zhao, Hui Qiao, Ziwei Wang, Meifei Wang, Haopeng Wang, Wenlong Wang, Qiqi Wang, Shixuan Tan, Lemin Jiao, Jiale Xu, Yalan Li, Erhe Gao, Ziqiao Yuan, Hong-Min Liu, jianzeng Dong, Bin Yu
Journal: Circulation Research (2024)

Heart failures with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF) have been recognized as the leading cause of morbidity and mortality worldwide. Histone lysine demethylase KDM5B, an important anti-tumor drug target, has been involved in several cardiovascular diseases. However, its role in heart failure remains largely unknown. In the current study, we found that the expression of KDM5B were significantly enhanced and KDM5B’s downstream substrate: the methylation level of H3K4me3 was decreased in the mouse hearts of both trans-aortic constriction (TAC)-induced HFrEF and high fat diet (HFD) with Nω-nitro-L-arginine methyl ester (L-NAME) (two-hit)-induced HFpEF. By generating a tamoxifen-induced cardiomyocyte- (CM-KO) and a myofibroblast- (MF-KO) specific KDM5B Cre-loxP conditional knockout mice, specifically, we further found that either KDM5B CM-KO or MF-KO mouse significantly ameliorated pathological ventricular remodeling, fibrosis and rescued the cardiac dysfunction phenotypes induced by TAC or the two-hit models, specifically. Furthermore, pretreatment of a KDM5B specific inhibitor TK-129, which was previously identified by our group, also significantly attenuated myocardial hypertrophy, fibrosis and improved cardiac dysfunction in the two mouse heart failure models. Our findings demonstrated, for the first time, that genetic deficiency of KDM5B in either cardiomyocytes or myofibroblasts in vivo or pharmacological inhibition of KDM5B display a similar therapeutic effect in the pathological cardiac remodeling and heart failure in both pressure overload-induced HFrEF and HFpEF mouse models, suggesting that KDM5B is a potential therapeutic target for these two different HFs.
Abstract Mo118: Myofilament proteolysis may underlie contractile remodeling in atrial fibrillation
Authors: Hannah Cizauskas, Hope Burnham, Azaria Panni, Alexandra Pena, Alejandro Alvarez-Arce, Therese Davis, Kelly Araujo, Christine Delligatti, Seby Edassery, Jonathan Kirk, Rishi Arora, David Barefield
Journal: Circulation Research (2024)

Atrial fibrillation (AFib) is the most common cardiac rhythm disturbance. Treatment of AFib involves restoration of the atrial electrical rhythm. Following rhythm restoration, a period of depressed mechanical function, including decreased blood flow velocity and reduced atrial contractility, known as atrial stunning, occurs. This suggests that defects in contractility occur in AFib and are revealed upon restoration of rhythm. To assess contractile function, we used a canine atrial tachypacing model of induced AFib. Mass spectrometry analysis showed dysregulation of contractile proteins in samples from AFib compared to sinus rhythm atria. In atrial cardiomyocytes that were useable for skinned single cardiomyocyte force-calcium studies, we found reduced force of contraction. There were no significant differences in myosin heavy chain isoform expression. Resting tension is decreased in the AFib samples correlating with reduced full-length titin in the sarcomere. We measured degradation of other myofilament proteins including cMyBP-C, actinin, MHC, and cTnI, showing significant degradation in the AFib samples compared to sinus rhythm atria. Many of the protein degradation products appeared as discrete cleavage products that are generated by calpain proteolysis. We assessed calpain activity and found it to be significantly increased. Skinned cardiomyocytes from AFib atria showed increased calcium sensitivity that was consistent with increased cTnI degradation and decreased TnI phosphorylation. These results provide an understanding of the contractile remodeling that occurs in AFib.
Abstract Tu022: Gut-derived bacterial metabolites promote cardiac inflammation, leading to heart failure in murine model of DSS-induced colitis
Authors: Prabhat Ranjan, Roshan Dutta, Karen Colin, Ram Prasad, Craig Maynard, Suresh Verma
Journal: Circulation Research (2024)

Background: Inflammatory Bowel Disease (IBD) affects millions of people all over the world. This has been known to contribute to several other comorbidities. Recently, impaired gut-barrier permeability has been known to contribute to cardiovascular diseases in IBD patients. However, the precise mechanisms remain unclear. In this study, we propose that bacterial metabolites, like peptidoglycan, may play a role in promoting cardiac inflammation and ultimately leading to heart failure in mice following colitis. Methods: We induced colitis in C57 black mice with DSS (dextran sodium sulfate) treatment. Further, we collected fecal sample for 16s rRNA analysis to evaluate microbial flora. Additionally, heart and intestine tissues were collected to determine inflammatory genes expression (qPCR), immune cell infiltration (FACS), and intestinal permeability (WB and immunohistochemistry). Blood was collected to quantify the circulating peptidoglycan (PGN) level. The effect of PGN on NFkB inflammatory pathways was evaluated in macrophages. Results: Echo-data showed cardiac dysfunction in DSS mice. Masson’s trichrome staining showed deteriorated intestinal villi, while western blot data indicated decreased Occludin and increased PV-1 level, suggesting a leaky gut in DSS treated mice. Comparative analysis of 16s rRNA sequencing data showed significantly altered Firmicutes/Bacteroidetes ratio in DSS treated mice as compared to control mice. Moreover, plasma PGN level was significantly increased 3 weeks following DSS treatment. Real-time gene expression data of pro-inflammatory cytokines (TNFα) and fibrosis associated genes (col1α1, fibronectin) were increased in DSS mice heart. Increased CD68 expression in the immunostaining data of DSS mice heart suggests the recruitment of inflammatory macrophages. At the molecular level, CDK9 expression was significantly increased in macrophage following PGN treatment, which ultimately leads to an increase in NFkB signaling. Finally, CDK9 inhibition attenuated PGN-induced NFkB signaling. Conclusion: Together, our study suggests that colitis-induced gut leakage leads to CDK9-mediated NFκB upregulation, contributing to cardiac inflammation. Ongoing research will shed light on the underlying molecular mechanisms of cardiovascular dysfunction.
Abstract Tu025: Exploring Metabolomic Profiles in Vitamin D Deficient and Obese Individuals: Relevance to Arterial Stiffness
Authors: Adel Elmoselhi, Amal Bouzid, Mohamed Seif Allah, zeinab ibrahim, Ruqaiyyah Siddiqui, Naveed Ahmed Khan, Hamza M. Al-Hroub, Mohammad Harb, Nelson Da Cruz Soares, Rifat A Hamoudi
Journal: Circulation Research (2024)

Introduction: Cardiovascular diseases (CVDs) continue to pose a significant global health challenge, with vitamin D deficiency and obesity emerging as prominent risk factors. Arterial stiffness is recognized as a pivotal predictor and an independent risk element for CVDs. This study explores the metabolomic profiling of blood samples obtained from individuals afflicted with early arterial stiffness due to vitamin D deficiency and obesity, compared with a control group. Methods: The study comprised nine participants with vitamin D deficiency (vitamin D level of 20 ng/ml or lower), and obese participants (BMI of 30 or higher), along with eleven control participants (with vitamin D levels above 20 ng/ml and normal BMI). Pulse Wave Velocity (PWV) measurements were conducted using the SphygmoCor device. Whole blood was collected from each participant in EDTA tubes, followed by centrifugation at 4200 RPM for 10 minutes to obtain plasma samples, which were then stored in a -80°C freezer. Metabolomic analysis was carried out using Liquid Chromatography coupled with tandem mass spectrometry (LC-MS/MS). A two-tailed p-value &lt; 0.05 was considered statistically significant for all analyses. Results: The average PWV value relative to the participant's age was 19.4 ± 4.7 m/s in the group with both vitamin D deficiency and obesity, compared to 14.7 ± 2.1 m/s in the control group (p &lt; 0.05), indicating increased arterial stiffness. Furthermore, eleven metabolites exhibited statistically significant differences in patients with vitamin D deficiency and obesity. Of these, eight metabolites demonstrated increased expression levels, including Nutriacholic acid, N-Acetylputrescine, Succinylacetone, Adenosine monophosphate, Elaidic acid, Niacinamide, DUMP, and 2-Pyrrolidinone, while three metabolites exhibited decreased expression: PC (18:1(9Z)/18:1(9Z)), Trimethylamine, and Imidazole. Additionally, top enrichment analysis revealed metabolic pathways predicted to be altered in the context of dysfunctional enzymes, encompassing processes such as nicotinamide acid uptake, fatty-acyl-CoA synthase (n-C18:0CoA), and extracellular NADP nucleosidase, among others. Conclusion: The metabolomic alterations identified in our study offer insights into potential biomarkers for evaluating arterial stiffness and present novel targets for therapeutic interventions in vitamin D deficient and obese individuals.