The transcriptional and epigenetic reprogramming mediated by chronic IL1β exposure drives self-renewal ability and myeloid priming in TET2 deficient stem and progenitor cells.

Clonal hematopoiesis (CH) increases the risk for the development of hematological malignancy and cardiovascular disease. IL1{beta} is elevated in patients with CH and its inhibition mitigates cardiovascular risk in murine models with Tet2 loss-of-function. How IL1{beta} alters population dynamics of hematopoietic cells upon Tet2 deletion (Tet2-KO) is not well understood. We demonstrated IL1{beta} expands Tet2-KO monocytes/macrophages, and long-term hematopoietic stem cells. IL1{beta} promoted myeloid bias over other lineages of Tet2-KO HSPCs coinciding with the failure to demethylate lineage-associated enhancer and transcription factor binding sites. IL1{beta} enhanced the self-renewal ability of Tet2-KO HSPCs by upregulating genes associated with self-renewal and by resisting the demethylation of binding sites of transcription factors promoting terminal differentiation. The IL1{beta}-mediated premalignant phenotype is suppressed by the IL1{beta} antagonist or deletion of the IL1 receptor-1, in vivo in aged mice. Our results demonstrate that targeting IL1 signaling could be an efficient early intervention strategy in preleukemic disorders. STATEMENT OF SIGNIFICANCEIL1{beta} promoted myeloid expansion and self-renewal capacity of TET2-null pre-leukemic cells. Lineage bias occurred early within progenitors towards pro-inflammatory macrophages. Genes specific to aging and with roles in promoting self-renewal capacity, and myeloid bias were upregulated. Hypermethylation occurred within lymphoid and erythroid lineage-specific regulatory elements. Targeting IL1R1 reduced aberrant myeloid bias and premalignant phenotype.