Genetic signatures of myeloid cells with somatic mutations in men with chronic heart failure – interaction between loss of Y chromosome and clonal hematopoiesis

Introduction: Clonal hematopoiesis of indeterminate potential (CHIP) has been associated with worse prognosis in heart failure. Mosaic loss of the Y chromosome (LOY), the most common somatic mutation in blood cells of men also increases with age and was experimentally shown to lead to diffuse cardiac fibrosis in mice. However, the prognostic significance of LOY as well as its potential interaction with CHIP and the mechanisms responsible in patients with chronic heart failure are unknown.

Methods: We investigated the prevalence and prognostic significance of the extent of LOY and the two most common CHIP-driver mutations DNMT3A and TET2 in 781 male patients with chronic heart failure. To assess the effects of LOY in human leukocytes of patients with heart failure, we performed single-cell RNA-sequencing (scRNA-seq) of immune cells from 10 male patients with and without DNMT3A mutations.

Results: Both, LOY and DNMT3A/TET2 CHIP driver mutations increased with age. LOY was an independent predictor of death during 3-years of follow-up. The co-occurrence of harboring LOY and DNMT3A/TET2 mutations significantly contributed to the observed increased mortality observed in carriers of DNMT3A/TET2 mutations. The detrimental effect of LOY on prognosis was confirmed in a validation cohort of patients with ischemic heart disease. scRNA-seq of circulating leukocytes of patients with heart failure was performed. Here, gene ontology (GO) terms derived from upregulated genes in LOY monocytes were associated with macrophage-mediated tissue damage and cardiac fibrosis. Expression levels of genes mediating profibrotic signaling and tissue damage such as S100A8, TLR2, CLEC4D were elevated and TGF-b inhibiting genes SMAD7, TGIF2 were downregulated in LOY monocytes. To gain insights into the detrimental effect of the combination of both, the presence of CHIP mutations and LOY ≥ 17%, on prognosis in patients with heart failure, a paired analysis of LOY and Y cells in patients with and without DNMT3A mutations was performed. Specifically upregulated GO-Terms in LOY cells derived from patients simultaneously harboring DNMT3A mutations were related to maladaptive inflammation and fibrosis. In contrast, we did not find gene ontology terms related to increased inflammation in LOY cells of patients without CHIP mutations. On a single gene level, proinflammatory genes such as the alarmins S100A8 and HMGB2 were significantly upregulated in LOY cells of patients simultaneously harboring DNMT3A CHIP-driver mutations. Moreover, IFNGR and CD84, which enhances IFN-y secretion as well as the interferon-inducible E3 ubiquitin ligase TRIM56, which modulates cGAS-STING were specifically upregulated in LOY cells of patients with DNMT3A mutations. In addition, PLBD1, which generates lipid mediators of inflammation and CLCN7, a major activator of cellular lysosomal activity were significantly upregulated only in LOY cells of patients with DNMT3A mutations.

Conclusion: The co-occurrence of LOY contributes increased mortality observed in patients with chronic heart failure carrying DNMT3A/TET2 CHIP driver mutations. scRNA-seq analyses of circulating monocytes lacking Y chromosome encoded genes exhibit profibrotic genetic signatures. LOY monocytes of patients simultaneously harboring DNMT3A CHIP-driver mutations display genetic expression features of augmented generic paracrine and cell-intrinsic inflammation pathways in addition to profibrotic activation.