Project description:BACKGROUND: Clinical management of heart failure with preserved ejection fraction (HFpEF) is hindered by a lack of disease-modifying therapies capable of altering its distinct pathophysiology. Despite the widespread implementation of a 2-hit model of cardiometabolic HFpEF to inform precision therapy, which utilizes HFD+L-NAME (ad libitum high-fat diet and 0.5% N[ω]-nitro-L-arginine methyl ester), we observe that C57BL6/J mice exhibit less cardiac diastolic dysfunction in response to HFD+L-NAME. METHODS: Genetic strain-specific single-nucleus transcriptomic analysis identified disease-relevant genes that enrich oxidative metabolic pathways within cardiomyocytes. Because C57BL/6J mice are known to harbor a loss-of-function mutation affecting the inner mitochondrial membrane protein Nnt (nicotinamide nucleotide transhydrogenase), we established an isogenic model of Nnt loss-of-function to determine whether intact NNT is necessary for the pathological cardiac manifestations of HFD+L-NAME. Twelve-week-old mice cross-bred to isolate wild-type (Nnt+/+) or loss-of-function (Nnt−/−) Nnt in the C57BL/6N background were challenged with HFD+L-NAME for 9 weeks (N=6–10). RESULTS: Nnt+/+ mice exhibited impaired ventricular diastolic relaxation and pathological remodeling, as assessed via noninvasive echocardiographic quantification of early diastolic pulse-wave velocity (E) to mitral annular velocity (e′) ratio (E/e′) (42.8 versus 21.5, P=1.2×10−10), E/A (early-to-late mitral inflow velocity ratio) (2.3 versus 1.4, P=4.1×10−2), diastolic stiffness (0.09 versus 0.04 mm Hg/μL, P=5.1×10−3), and myocardial fibrosis (P=2.3×10−2). Liquid chromatography and mass spectroscopy exposed a 40.0% reduction in NAD+ (P=8.4×10−3) and a 38.8% reduction in the ratio of reduced-to-oxidized glutathione (GSH: GSSG, P=2.6×10−2) among Nnt+/+ mice after HFD+L-NAME feeding. Using single-nucleus ligand-receptor analysis, we implicate Fgf1 (fibroblast growth factor 1) as a putative NNT-dependent mediator of cardiomyocyte-to-fibroblast signaling in myocardial fibrosis. CONCLUSIONS: Together, these findings underscore the pivotal role of mitochondrial dysfunction in HFpEF pathogenesis, implicating both NNT and Fgf1 as novel therapeutic targets.
Project description:Clinical management of heart failure with preserved ejection fraction (HFpEF) is hindered by a lack of disease-modifying therapies capable of altering its distinct pathophysiology. Despite the widespread implementation of a “two-hit” model of cardiometabolic HFpEF to inform precision therapy, which utilizes ad libitum high-fat and 0.5% N(ω)-nitro-L-arginine methyl ester (HFD+L-NAME) diet, we observe that C57BL6/J mice exhibit less cardiac diastolic dysfunction in response to HFD+L-NAME. Genetic strain-specific single-nucleus transcriptomic analysis identified disease-relevant genes that enrich oxidative metabolic pathways within cardiomyocytes. Because C57BL/6J mice are known to harbor a loss-of-function mutation affecting the inner mitochondrial membrane protein nicotinamide nucleotide transhydrogenase (Nnt), we used an isogenic model of Nnt loss-of-function to determine whether intact NNT is necessary for the pathological cardiac manifestations of HFD+L-NAME. Twelve-week-old mice cross-bred to isolate wild-type (Nnt+/+) or loss-of-function (Nnt-/-) Nnt in the C57BL/6N background, were challenged with HFD+L-NAME for 9 weeks (n = 6-10). Nnt+/+ mice exhibited impaired ventricular diastolic relaxation and pathological remodeling, as assessed via E/e’ (42.8 vs. 21.5, P = 1.2e-10), E/A (2.3 vs 1.4, P = 4.1e-2), diastolic stiffness (0.09 vs 0.04 mmHg/μL, P = 5.1e-3), and myocardial fibrosis (P = 2.3e-2). Liquid chromatography and mass spectroscopy exposed a 40.0% reduction in NAD+ (P = 8.4e-3) and a 38.8% reduction in GSH:GSSG (P = 2.6e-2) among Nnt+/+ mice after HFD+L-NAME feeding. Using single-nucleus ligand-receptor analysis, we implicate fibroblast growth factor 1 (Fgf1) as a putative NNT-dependent mediator of cardiomyocyte-to-fibroblast signaling of myocardial fibrosis. Together, these findings underscore the pivotal role of mitochondrial dysfunction in HFpEF pathogenesis and position both NNT and Fgf1 as novel therapeutic targets.
Project description:Heart failure with preserved ejection fraction (HFpEF) remains a major public health burden with increasing prevalence but only few effective therapies. Endothelial dysfunction and inflammation are identified as pathophysiological drivers of HFpEF disease progression. MicroRNAs are increasingly recognized as key regulators of these pathological processes, while antimiR-based therapies have been emerged as promising therapeutics in mice and humans. Therefore, we tested whether targeting miR-92a-3p inhibition is a promising therapeutic intervention to target HFpEF in vivo. By injection of locked nucleic acid (LNA)-based antimiR (LNA-92a) weekly, we demonstrate that inhibition of miR-92a-3p attenuates the development of diastolic dysfunction and left atrial dilation following experimental induction of HFpEF in mice. Indeed, LNA-92a depleted miR-92a-3p expression in the myocardium and peripheral blood, and derepressed predicted target genes in a cell type-specific manner. Furthermore, cell-type specific efficacy of LNA-92a treatment was assessed by single-nuclear RNA sequencing of HFpEF hearts either treated with LNA-92a or LNA-Control. Endothelial cells of LNA-92a treated mice showed normalized vascular gene expression and reduced gene signatures associated with endothelial-mesenchymal transition. Conclusion: This study demonstrates that LNA-based antimiR-92a is an effective therapeutic strategy to target diastolic dysfunction and left atrial dilation in HFpEF.
Project description:Microvascular dysfunction has been proposed to drive heart failure with preserved ejection fraction (HFpEF), but the initiating molecular and cellular events are largely unknown. Our objective was to determine when microvascular alterations in HFpEF begin, how they contribute to disease progression, and how pericyte dysfunction plays a role herein. We aimed to assess microvascular dysfunction with respect to the development of cardiac dysfunction, in the Zucker fatty and spontaneously hypertensive (ZSF1) obese rat model of HFpEF at three time points: 6, 14, and 21 weeks of age. We found that pericyte loss was the earliest and strongest microvascular change, occurring before prominent echocardiographic signs of diastolic dysfunction were present. Pericytes were shown to be less proliferative and had a disrupted morphology at 14 weeks in the obese ZSF1 animals, who also exhibited an increased capillary luminal diameter and disrupted endothelial junctions. Pericytes exposed to oxidative stress in vitro showed downregulation of cell cycle associated pathways, and induced a pro-inflammatory state in endothelial cells upon co-culture. We propose pericytes are important for maintaining endothelial cell function, where loss of pericytes enhances the reactivity of endothelial cells to inflammatory signals and promotes microvascular dysfunction, thereby accelerating the development of HFpEF.
Project description:As part of genetic studies of heart failure in mice, we observed that heart mitochondrial DNA levels and function tend to be reduced in females as compared to males. We also observed that expression of genes encoding mitochondrial proteins were higher in males than females in human cohorts. Heart failure with preserved ejection fraction (HFpEF) exhibits a sex bias, being more common in women than men, and we hypothesized that mitochondrial sex differences might underlie this bias. We tested this in a panel of genetically diverse inbred strains of mice, termed the Hybrid Mouse Diversity Panel (HMDP). Indeed, we found that mitochondrial gene expression was highly correlated with diastolic function, a key trait in HFpEF. Consistent with this, studies of a “two-hit” mouse model of HFpEF confirmed that mitochondrial function differed between sexes and was strongly associated with a number of HFpEF traits. By integrating data from human heart failure and the mouse HMDP cohort, we identified the mitochondrial protein Acsl6 as a genetic determinant of diastolic function. We validated its role in HFpEF using adenoviral over-expression in the heart. We conclude that sex differences in mitochondrial function underlie, in part, the sex bias in diastolic function.
Project description:Disrupted cardiomyocyte energy metabolism underlies HFpEF. We found that cardiac succinate and GPR91 were reduced in HFpEF. In WT mice, succinate supplementation restored metabolism, improved diastolic function, and alleviated hypertrophy and fibrosis, whereas these benefits were abolished in global and cardiomyocyte-specific Gpr91 knockouts. Transcriptomics and mechanistic studies revealed that succinate–GPR91 signaling activated AMPK via Gq, enhanced NAD⁺ production, and promoted glucose–lipid metabolic reprogramming. Thus, the succinate–GPR91 axis is essential for cardiometabolic regulation and represents a promising therapeutic target in HFpEF.
Project description:Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome in patients with a left ventricular ejection fraction (LVEF) ≥50% and evidence of diastolic dysfunction (abnormal LV filling and elevated filling pressures) causing symptoms including decreased exercise tolerance and dyspnea. Characterization of clinical phenogroups within HFpEF patients using the standards from TOPCAT (Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist Trial) identified one of three that predominantly demonstrates cardiometabolic and inflammatory phenotypes (cardiometabolic HFpEF). (1) This patient population accounts for the largest healthcare burden and has the highest mortality of all three phenogroups. While the primary goal of iron infusion is to enhance HF outcomes, it's crucial to acknowledge the potential for unintended acute myocardial injury following IV iron infusion. This realization prompted us to investigate if a single clinically relevant dose of IV iron could induce ferroptosis in the myocardium. We identified that a single clinically relevant dose of IV iron acutely induced changes consistent with myocardial ferroptosis. This discovery highlights the urgency of determining if repeated doses of IV iron induce repetitive bouts of ferroptosis and if this adversely affects cardiac function. Further studies should evaluate if the co-administration of ferroptosis inhibitors with IV iron mitigates potential harm while providing the benefits of iron supplementation in cardiometabolic HFpEF.
Project description:HFpEF accounts for ∼50% of HF cases. The ZSF1-obese rat model recapitulates clinical features of HFpEF including hypertension, obesity, metabolic syndrome, exercise intolerance, and diastolic dysfunction. Here, we used a systems biology approach to define the metabolic and transcriptional signatures to gain mechanistic insight into pathways contributing to HFpEF development. The integrated omics approach applied here provides a framework to uncover novel genes, metabolites, and pathways underlying HFpEF, with an emphasis on mitochondrial energy metabolism as a potential interventional target.
Project description:Heart failure with preserved ejection fraction (HFpEF) is a highly prevalent and intractable form of cardiac decompensation commonly associated with diastolic dysfunction. Here, we show that diastolic dysfunction in patients with HFpEF is associated with a cardiac deficit in nicotinamide adenine dinucleotide (NAD+). Elevating NAD+ by oral supplementation of its precursor, nicotinamide, improved diastolic dysfunction induced by aging (in 2-year-old C57BL/6J mice), hypertension (in Dahl salt-sensitive rats) or cardiometabolic syndrome (in ZSF1 obese rats). Mechanistically, this effect was mediated partly through alleviated systemic comorbidities and enhanced myocardial bioenergetics, as evidenced by cardiac trasncriptome and metabolome analyses. Simultaneously, nicotinamide directly improved cardiomyocyte passive stiffness and calcium-dependent active relaxation through increased deacetylation of titin and the sarcoplasmic reticulum calcium ATPase 2a, respectively. In a long-term human cohort study, high dietary intake of naturally occurring NAD+ precursors was associated with lower blood pressure and reduced risk of cardiac mortality. Collectively, these results suggest NAD+ precursors, and especially nicotinamide, as potential therapeutic agents to treat diastolic dysfunction and HFpEF in humans.