Project description:Microvascular dysfunction is an important determinant in HFpEF but the role of mural cells herein is still poorly investigated. We aimed to examine the transcriptomic signature of endothelial cells and mural cells of the micro- and macrovascular niche in healthy vs. HFpEF cell RNAsequencing.
Project description:Effective treatments for heart failure with preserved ejection fraction (HFpEF) are limited. Empagliflozin, a sodium-glucosecotransporter-2 (SGLT2) inhibitor, provides cardiovascular benefits for patients with HFpEF. SGLT2 expression is virtually absent in cardiomyocytes, hence the exact protective mechanism of empagliflozin is unclear. We aimed to study the effect of in vivo empagliflozin treatment on excitation–contraction coupling (ECC), electrophysiology, and gene transcription in a translational two-hit HFpEF mouse model that combines the obese-diabetic leptin receptor-deficient db/db mice with chronic aldosterone infusion (db/db + Aldo). We performed morphometry, echocardiography, cardiomyocyte electrophysiology, intracellular Ca imaging, and whole-heart RNA-sequencing in empagliflozin-treated db/db + Aldo and vehicle control mice. In db/db + Aldo mice, empagliflozin (in vivo, 4weeks) reduced the elevated plasma blood glucose (13 ± 5 mmol/L versus 23 ± 8 mmol/L) and BNP levels, prevented pulmonary congestion, and ameliorated diastolic dysfunction. However, empagliflozin did not reduce cardiac hypertrophy and obesity. In healthy control mice, empagliflozin had no functional effect. Chronic in vivo empagliflozin treatment in db/db + Aldo also normalized the changes in cardiomyocyte electrophysiology and Ca handling properties measured in the absence of empagliflozin in the perfusion solution during cell experiments, indicating a true phenotypic rescue. Differentially expressed gene clusters were identified characteristic of the db/db genotype, aldosterone, and empagliflozin treatments. Interestingly, empagliflozin did not just reverse the HFpEF-altered gene expression but shifted it further away from control to a new expression profile. We conclude that chronic in vivo empagliflozin treatment restores cardiomyocyte electrophysiological and ECC properties, ameliorates diastolic function in cardiometabolic HFpEF, and induces complex gene expression changes.
Project description:Heart failure (HF) with preserved ejection fraction (HFpEF) comprises heterogenous clinical phenotypes and presence of various co-morbidities. Recent two-hit translational animal models, including the hypertensive, nitrosative-stressed mice fed with high-fat diet and L-NAME (HFD+L-NAME) and the obese-diabetic leptin receptor-deficient db/db mice with excess aldosterone (db/db+Aldo), may phenocopy select subgroups of HFpEF. We systematically compared mechanisms of excitation-contraction coupling (ECC), electrophysiology, and gene transcription in these key preclinical HFpEF models and between sexes to advance translation. We performed morphometry, echocardiography, cellular electrophysiology, intracellular Ca2+ imaging, and RNA-sequencing. The multiorgan HFpEF phenotype showed key differences between the 2 models, db/db+Aldo mice were markedly obese, had severe hyperglycaemia and hepatomegaly, whereas male HFD+L-NAME mice had more pronounced cardiac hypertrophy. Diastolic dysfunction was more severe in db/db+Aldo mice and worse in females therein, whereas female sex was protective in HFD+L-NAME. Marked proarrhythmic action potential (AP) changes (AP prolongation, increased short-term variability and alternans threshold) occurred in db/db+Aldo (in both sexes), these AP changes were less severe in male HFD+L-NAME and absent in female HFD+L-NAME. In line with these, differential ionic current and Ca2+ handling changes occurred between these two HFpEF models and between sexes in each model. RNA-sequencing revealed highly distinctive gene expression profiles between HFpEF models. We conclude that marked differences exist in cardiomyocyte ECC, electrophysiology, and gene expression between HFD+L-NAME and db/db+Aldo mice and between sexes. This indicates that a combination of translational HFpEF models that mimic select HFpEF sub-phenogroups are needed to better understand HFpEF mechanisms for therapeutic drug development.
Project description:db/db mouse kidney given liraglutide or insulin compared to db/db vehicle and healthy vehicle, 12 weeks dosing, all included db/db mice over 16 mM blood glucose level.
Project description:Given that celastrol?s leptin-sensitizing effect requires both high levels of circulating leptin and intact leptin receptor signaling, we analyzed the effect of celastrol on hypothalamic gene expression profile of db/db mice, which have high circulating levels of leptin, but lack intact leptin receptor signaling. This analysis will be serving as negative control for DIO mice analysis.
Project description:This program addresses the molecular basis of beta-cell failure associated with the development of type 2 diabetes in the db/db mice. Specifically, which genes are differentially expressed in pancreatic islets of the db/db mice compared to the control db/+ mice?
Project description:This program addresses the molecular basis of beta-cell failure associated with the development of type 2 diabetes in the db/db mice. Specifically, which genes are differentially expressed in pancreatic islets of the db/db mice compared to the control db/+ mice? The db/db mice islets profiling data was analyzed by identifying genes that were up- and down-regulated at selected p value and fold change in the islets of db/db mice compared to the corresponding db/+ controls.
Project description:A control group of male C57BL/6J mice were fed a 60% fat diet (Research Diets D12492i) for 8 weeks, resulting in “ad libitum obesity” (ALO). Leptin receptor-deficient B6.BKS(D)-Leprdb/J (“db/db”) male mice were fed a low-fat chow diet (PicoLab Rodent Diet 20; Purina Mills Inc). Once the average body weights of the two groups were equivalent, all mice were fasted for 24 hours, after which they were sacrificed and perigonadal adipose tissue (PGAT) was dissected out. PGAT was cultured ex vivo for 6 hours, after which conditioned media was collected and submitted for proteomic profiling. At the time of sacrifice, ALO mice were 17 weeks old and db/db mice were 10 weeks old. “HFD” is also used to refer to the ALO condition while “DB” is used to refer to the “db/db” condition.