DNMT3A clonal hematopoiesis-driver mutations induce cardiac fibrosis by paracrine activation of fibroblasts.

Hematopoietic mutations in epigenetic regulators like DNA methyltransferase 3 alpha (DNMT3A), play a pivotal role in driving clonal hematopoiesis of indeterminate potential (CHIP), and are associated with unfavorable outcomes in patients suffering from heart failure (HF). However, the precise interactions between CHIP-mutated cells and other cardiac cell types remain unknown. Here, we identify fibroblasts as potential partners in interactions with CHIP-mutated monocytes. We used combined transcriptomic data derived from peripheral blood mononuclear cells of HF patients, both with and without CHIP, and cardiac tissue. We demonstrate that inactivation of DNMT3A in macrophages intensifies interactions with cardiac fibroblasts and increases cardiac fibrosis. DNMT3A inactivation amplifies the release of heparin-binding epidermal growth factor-like growth factor, thereby facilitating activation of cardiac fibroblasts. These findings identify a potential pathway of DNMT3A CHIP-driver mutations to the initiation and progression of HF and may also provide a compelling basis for the development of innovative anti-fibrotic strategies.

Single-cell technologies to decipher cardiovascular diseases.

Cardiovascular disease remains the leading cause of death worldwide. A deeper understanding of the multicellular composition and molecular processes may help to identify novel therapeutic strategies. Single-cell technologies such as single-cell or single-nuclei RNA sequencing provide expression profiles of individual cells and allow for dissection of heterogeneity in tissue during health and disease. This review will summarize (i) how these novel technologies have become critical for delineating mechanistic drivers of cardiovascular disease, particularly, in humans and (ii) how they might serve as diagnostic tools for risk stratification or individualized therapy. The review will further discuss technical pitfalls and provide an overview of publicly available human and mouse data sets that can be used as a resource for research.

Post-myocardial infarction heart failure dysregulates the bone vascular niche.

The regulation of bone vasculature by chronic diseases, such as heart failure is unknown. Here, we describe the effects of myocardial infarction and post-infarction heart failure on the bone vascular cell composition. We demonstrate an age-independent loss of type H endothelium in heart failure after myocardial infarction in both mice and humans. Using single-cell RNA sequencing, we delineate the transcriptional heterogeneity of human bone marrow endothelium, showing increased expression of inflammatory genes, including IL1B and MYC, in ischemic heart failure. Endothelial-specific overexpression of MYC was sufficient to induce type H bone endothelial cells, whereas inhibition of NLRP3-dependent IL-1ß production partially prevented the post-myocardial infarction loss of type H vasculature in mice. These results provide a rationale for using anti-inflammatory therapies to prevent or reverse the deterioration of bone vascular function in ischemic heart disease.

Clonal Hematopoiesis-Driver DNMT3A Mutations Alter Immune Cells in Heart Failure.

RATIONALE: Clonal hematopoiesis driven by mutations of DNMT3A (DNA methyltransferase 3a) is associated with increased incidence of cardiovascular disease and poor prognosis of patients with chronic heart failure (HF) and aortic stenosis. Although experimental studies suggest that DNMT3A clonal hematopoiesis-driver mutations may enhance inflammation, specific signatures of inflammatory cells in humans are missing. OBJECTIVE: To define subsets of immune cells mediating inflammation in humans using single-cell RNA sequencing. METHODS AND RESULTS: Transcriptomic profiles of peripheral blood mononuclear cells were analyzed in n=6 patients with HF harboring DNMT3A clonal hematopoiesis-driver mutations and n=4 patients with HF and no DNMT3A mutations by single-cell RNA sequencing. Monocytes of patients with HF carrying DNMT3A mutations demonstrated a significantly increased expression of inflammatory genes compared with monocytes derived from patients with HF without DNMT3A mutations. Among the specific upregulated genes were the prototypic inflammatory IL (interleukin) IL1B (interleukin 1B), IL6, IL8, the inflammasome NLRP3, and the macrophage inflammatory proteins CCL3 and CCL4 as well as resistin, which augments monocyte-endothelial adhesion. Silencing of DNMT3A in monocytes induced a paracrine proinflammatory activation and increased adhesion to endothelial cells. Furthermore, the classical monocyte subset of DNMT3A mutation carriers showed increased expression of T-cell stimulating immunoglobulin superfamily members CD300LB, CD83, SIGLEC12, as well as the CD2 ligand and cell adhesion molecule CD58, all of which may be involved in monocyte-T-cell interactions. DNMT3A mutation carriers were further characterized by increased expression of the T-cell alpha receptor constant chain and changes in T helper cell 1, T helper cell 2, T helper cell 17, CD8+ effector, CD4+ memory, and regulatory T-cell-specific signatures. CONCLUSIONS: This study demonstrates that circulating monocytes and T cells of patients with HF harboring clonal hematopoiesis-driver mutations in DNMT3A exhibit a highly inflamed transcriptome, which may contribute to the aggravation of chronic HF.

Association of Clonal Hematopoiesis of Indeterminate Potential With Inflammatory Gene Expression in Patients With Severe Degenerative Aortic Valve Stenosis or Chronic Postischemic Heart Failure.

Importance: Cytokine release syndrome is a complication of coronavirus disease 2019. Clinically, advanced age and cardiovascular comorbidities are the most important risk factors. Objective: To determine whether clonal hematopoiesis of indeterminate potential (CHIP), an age-associated condition with excess cardiovascular risk defined as the presence of an expanded, mutated somatic blood cell clone in persons without other hematological abnormalities, may be associated with an inflammatory gene expression sensitizing monocytes to aggravated immune responses. Design, Setting, and Participants: This hypothesis-generating diagnostic study examined a cohort of patients with severe degenerative aortic valve stenosis or chronic postinfarction heart failure, as well as age-matched healthy control participants. Single-cell RNA sequencing and analyses of circulating peripheral monocytes was done between 2017 and 2019 to assess the transcriptome of circulating monocytes. Exposures: Severe degenerative aortic valve stenosis or chronic postinfarction heart failure. Main Outcomes and Measures: CHIP-driver sequence variations in monocytes with a proinflammatory signature of genes involved in cytokine release syndrome. Results: The study included 8 patients with severe degenerative aortic valve stenosis, 6 with chronic postinfarction heart failure, and 3 healthy control participants. Their mean age was 75.7 (range, 54-89) years, and 6 were women. Mean CHIP-driver gene variant allele frequency was 4.2% (range, 2.5%-6.9%) for DNMT3A and 14.3% (range, 2.6%-37.4%) for TET2. Participants with DNMT3A or TET2 CHIP-driver sequence variations displayed increased expression of interleukin 1ß (no CHIP-driver sequence variations, 1.6217 normalized Unique Molecular Identifiers [nUMI]; DNMT3A, 5.3956 nUMI; P < .001; TET2, 10.8216 nUMI; P < .001), the interleukin 6 receptor (no CHIP-driver sequence variations, 0.5386 nUMI; DNMT3A, 0.9162 nUMI; P < .001;TET2, 0.5738 nUMI; P < .001), as well as the NLRP3 inflammasome complex (no CHIP-driver sequence variations, 0.4797 nUMI; DNMT3A, 0.9961 nUMI; P < .001; TET2, 1.2189 nUMI; P < .001), plus upregulation of CD163 (no CHIP-driver sequence variations, 0.5239 nUMI; DNMT3A, 1.4722 nUMI; P < .001; TET2, 1.0684 nUMI; P < .001), a cellular receptor capable of mediating infection, macrophage activation syndrome, and other genes involved in cytokine response syndrome. Gene ontology term analyses of regulated genes revealed that the most significantly upregulated genes encode for leukocyte-activation and interleukin-signaling pathways in monocytes of individuals with DNMT3A (myeloid leukocyte activation: log[Q value], -50.1986; log P value, -54.5177; regulation of cytokine production: log[Q value], -21.0264; log P value, -24.1993; signaling by interleukins: log[Q value], -18.0710: log P value, -21.1597) or TET2 CHIP-driver sequence variations (immune response: log[Q value], -36.3673; log P value, -40.6864; regulation of cytokine production: log[Q value], -13.1733; log P value, -16.3463; signaling by interleukins: log[Q value], -12.6547: log P value, -15.7977). Conclusions and Relevance: Monocytes of individuals who carry CHIP-driver sequence variations and have cardiovascular disease appear to be primed for excessive inflammatory responses. Further studies are warranted to address potential adverse outcomes of coronavirus disease 2019 in patients with CHIP-driver sequence variations.

Efficiency and Target Derepression of Anti-miR-92a: Results of a First in Human Study.

MicroRNA (miRNA) inhibition is a promising therapeutic strategy in several disease indications. MRG-110 is a locked nucleic acid-based antisense oligonucleotide that targets miR-92a-3p and experimentally was shown to have documented therapeutic effects on cardiovascular disease and wound healing. To gain first insights into the activity of anti-miR-92a in humans, we investigated miR-92a-3p expression in several blood compartments and assessed the effect of MRG-110 on target derepression. Healthy adults were randomly assigned (5:2) to receive a single intravenous dose of MRG-110 or placebo in one of seven sequential ascending intravenous dose cohorts ranging from 0.01 to 1.5 mg/kg body weight. MiR-92a-3p whole blood levels were time and dose dependently decreased with half-maximal inhibition of 0.27 and 0.31 mg/kg at 24 and 72 h after dosing, respectively. In the high-dose groups, >95% inhibition was detected at 24-72 h postinfusion and significant inhibition was observed for 2 weeks. Similar inhibitory effects were detected in isolated CD31+ cells, and miR-92a-3p expression was also inhibited in extracellular vesicles in the high-dose group. Target derepression was measured in whole blood and showed that ITGA5 and CD93 were increased at a dose of 1.5 mg/kg. Single-cell RNA sequencing of peripheral blood cells revealed a cell type-specific derepression of miR-92a targets. Together this study demonstrates that systemic infusion of anti-miR-92a efficiently inhibits miR-92a in the peripheral blood compartment and derepresses miR-92a targets in humans.