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Derepression of Gene Expression Underlies HDAC Inhibitor-Mediated Reversal of Diastolic Dysfunction [RNA-seq]

ABSTRACT: Background: Diastolic dysfunction is characterized by increased ventricular stiffness, which impairs relaxation. Histone deacetylase (HDAC) inhibitors have been shown to reverse diastolic dysfunction in preclinical models. Objectives: We addressed the mechanisms by which HDAC inhibitors improve relaxation of the heart. Methods: Diastolic dysfunction was induced in mice through unilateral nephrectomy (UNX) and implantation of a deoxycorticosterone acetate (DOCA) pellet. After four weeks, when diastolic dysfunction was established, a subset of mice received ITF2357, an FDA-approved HDAC inhibitor, for four additional weeks. At study endpoint, single-cell RNA sequencing (scRNA-seq) was performed on cardiac non-myocytes. Flow cytometry further characterized cardiac non-myocyte populations. For mechanistic experiments, cardiac fibroblasts (CFs) from failing human hearts were treated with ITF2357 and subjected to bulk RNA-seq and assay for transposase-accessible chromatin with sequencing (ATAC-seq). Results: Diastolic dysfunction induced transcriptionally distinct subpopulations of CFs, myeloid cells, and endothelial cells, with gene repression being more strongly associated with cardiac dysfunction than gene induction. ITF2357 reversed this repression in correlation with improvements in diastolic function. HDAC inhibition prevented the emergence of profibrotic and proinflammatory fibroblasts and macrophages in the heart. In human CFs, ITF2357-induced chromatin opening was coupled to gene derepression and reduced profibrotic state. A strong signature of gene repression was also noted in cardiac non-myocytes in human heart failure (HF).

ORGANISM(S): Homo sapiens

PROVIDER: GSE346301 | GEO | 2026/09/07

REPOSITORIES: GEO

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Project description:Background: Diastolic dysfunction (DD) is associated with the development of heart failure and contributes to the pathogenesis of other cardiac maladies, including atrial fibrillation. Inhibition of histone deacetylases (HDACs) has been shown to prevent DD by enhancing myofibril relaxation. We addressed the therapeutic potential of HDAC inhibition in a model of established DD with preserved ejection fraction. Methods: Four weeks after uninephrectomy and implantation with deoxycorticosterone acetate pellets, when DD was clearly evident, 1 cohort of mice was administered the clinical-stage HDAC inhibitor ITF2357/Givinostat. Echocardiography, blood pressure measurements, and end point invasive hemodynamic analyses were performed. Myofibril mechanics and intact cardiomyocyte relaxation were assessed ex vivo. Cardiac fibrosis was evaluated by picrosirius red staining and second harmonic generation microscopy of left ventricle (LV) sections, RNA sequencing of LV mRNA, mass spectrometry-based evaluation of decellularized LV biopsies, and atomic force microscopy determination of LV stiffness. Mechanistic studies were performed with primary rat and human cardiac fibroblasts. Results: HDAC inhibition normalized DD without lowering blood pressure in this model of systemic hypertension. In contrast to previous models, myofibril relaxation was unimpaired in uninephrectomy/deoxycorticosterone acetate mice. Furthermore, cardiac fibrosis was not evident in any mouse cohort on the basis of picrosirius red staining or second harmonic generation microscopy. However, mass spectrometry revealed induction in the expression of >100 extracellular matrix proteins in LVs of uninephrectomy/deoxycorticosterone acetate mice, which correlated with profound tissue stiffening based on atomic force microscopy. ITF2357/Givinostat treatment blocked extracellular matrix expansion and LV stiffening. The HDAC inhibitor was subsequently shown to suppress cardiac fibroblast activation, at least in part, by blunting recruitment of the profibrotic chromatin reader protein BRD4 (bromodomain-containing protein 4) to key gene regulatory elements. Conclusions: These findings demonstrate the potential of HDAC inhibition as a therapeutic intervention to reverse existing DD and establish blockade of extracellular matrix remodeling as a second mechanism by which HDAC inhibitors improve ventricular filling. Our data reveal the existence of pathophysiologically relevant covert or hidden cardiac fibrosis that is below the limit of detection of histochemical stains such as picrosirius red, highlighting the need to evaluate fibrosis of the heart using diverse methodologies.

Project description:Background: Organ fibrosis due to excessive production of extracellular matrix (ECM) by resident fibroblasts is estimated to contribute to >45% of deaths in the Western world, including those due to cardiovascular diseases such as heart failure (HF). Here, we screened for small molecule inhibitors with a common ability to suppress activation of fibroblasts across organ systems. Methods: High content imaging of cultured cardiac, pulmonary and renal fibroblasts was employed to identify non-toxic compounds that blocked induction of markers of activation in response to the profibrotic stimulus, TGF-β. SW033291, which inhibits the eicosanoid-degrading enzyme, 15-hydroxyprostaglandin dehydrogenase (15-PGDH), was chosen for follow-up studies with cultured adult rat ventricular fibroblasts (ARVFs) and human cardiac fibroblasts (CFs), and for evaluation in mouse models of cardiac fibrosis and diastolic dysfunction. Additional mechanistic studies were performed with CFs treated with exogenous eicosanoids. Results: Nine compounds, including SW033291, shared a common ability to suppress TGF-β-mediated activation of cardiac, pulmonary and renal fibroblasts. SW033291 dose-dependently inhibited TGF-β-induced expression of activation markers (e.g. α-smooth muscle actin and periostin) in ARVFs and normal human CFs, and reduced contractile capacity of the cells. Remarkably, the 15-PGDH inhibitor also reversed constitutive activation of fibroblasts obtained from explanted hearts from patients with HF. SW033291 blocked cardiac fibrosis induced by angiotensin II (Ang II) infusion and ameliorated diastolic dysfunction in an alternative model of systemic hypertension driven by combined uninephrectomy (UNX) and deoxycorticosterone acetate (DOCA) administration. Mechanistically, SW033291-mediated stimulation of ERK1/2 mitogen-activated protein kinase signaling was required for SW033291 to block CF activation. Of the 12 exogenous eicosanoids that were tested, only 12-hydroxyeicosatetraenoic acid (12[S]-HETE), which signals through the G protein-coupled receptor (GPCR), GPR31, recapitulated the suppressive effects of SW033291 on CF activation. Conclusions: Inhibition of degradation of eicosanoids, arachidonic acid-derived fatty acids that signal through GPCRs, is a potential therapeutic strategy for suppression of pathological organ fibrosis. In the heart, we propose that 15-PGDH inhibition triggers CF-derived autocrine/paracrine signaling by eicosanoids, including 12(S)-HETE, to stimulate ERK1/2 and block conversion of fibroblasts into activated cells that secrete excessive amounts of ECM and contribute of HF pathogenesis.

Project description:Propionate is a common three-carbon intermediate produced from the breakdown of propiogenic substrates, such as branched-chain amino acids and odd-numbered fatty acids, and by gut bacteria. Propionate can chemically modify proteins, and if this involves histones, it may underpin a disease-relevant link between short-chain acyls and gene expression in the heart. Here, we sought to characterize how propionate-dependent modifications to histones affect cardiac gene expression and contractile function in a mouse model producing elevated levels of propionate/propionyl-CoA. An adult mouse model of propionic acidaemia (PA) was used to investigate how propionate affects histones and gene expression in the heart, an organ strongly affected in PA patients. Mass spectrometry confirmed elevated plasma propionate in 8-week PA mice, reaching levels detected in PA patient serum. Metabolomic analyses confirmed a metabolic signature of PA, but male mice had enhanced propionate processing towards -alanine. Female PA hearts had expanded end-diastolic and end-systolic volumes, and weaker systolic contractions, without major electrocardiographic changes. Ca2+ signals were deranged in female PA mice (raised diastolic Ca2+), consistent with contractile dysfunction. Differentially-expressed genes (DEGs) included Pde9a and Mme, previously linked to cardiac dysfunction. These DEGs also responded to 48-h culture of wild-type myocytes with propionate as well as butyrate, an HDAC inhibitor, suggesting a role for increased histone acetylation alongside propionylation in inducing these genes. Indeed, histone acetylation (H3K27ac) and propionylation were elevated genome-wide in the PA heart and at the promoters of Pde9a and Mme. These propionate-associated epigenetic responses were more pronounced in female PA mice. The greater prominence of epigenetic, transcriptional, and functional responses in female PA mice, despite a mostly sex-indiscriminate overall metabolic milieu, argues that histone acylation plays a defining role in the cardiac phenotype. We conclude that perturbed propionate metabolism in vivo alters histone acylation and gene expression, which impacts cardiac contractile function.

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Derepression of Gene Expression Underlies HDAC Inhibitor-Mediated Reversal of Diastolic Dysfunction [RNA-seq]

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