DISTINCT PATHOGENESIS OF CLONAL HEMATOPOIESIS REVEALED BY SINGLE-CELL MULTI-OMICS SEQUENCING

Despite the significant impact of clonal hematopoiesis (CH) on leukemogenesis, the pathogenesis of CH is still not fully understood. Utilizing a novel single-cell sequencing platform that allows for simultaneous detection of mutations and gene expression, we examined the gene expression profiles of hematopoietic stem and progenitor cells (HSPCs) harboring CH-related mutations from CH(+) cases, which was compared with that of wild-type (WT) cells from both CH(+) and CH(−) cases. Age-related changes in the bone marrow (BM) environment were also assessed using CH(−) cases. In 12 patients with CH, genes associated with cell proliferation were upregulated in mutant cells. Significantly, mutant cells showed decreased expression of genes related to inflammatory responses, which were enhanced in BM cells from aged CH(−) cases, indicating the potential contribution of aged BM environment to the positive selection of mutant cells. Unexpectedly, WT cells from 3 TET2-CH(+) cases demonstrated significant upregulation of genes related to interferon response and cell proliferation, compared with those from age-matched CH(−) cases, suggesting the altered BM environments. Notably, when competitively transplanted with Tet2-knockout (KO) cells, WT HSPCs displayed enhanced expression of genes associated with cell proliferation and interferon signalling, compared with those transplanted with WT cells, implying non-cell autonomous effects of mutant cells. These results suggest that mutant cells in CH(+) BM may exert non-cell autonomous effects on WT cells. Alongside aged BM environments, these effects may contribute to the positive selection of CH clones, playing a pivotal role in the pathogenesis of CH.