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

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).