Interleukin-1 contributes to clonal expansion and progression of bone marrow fibrosis in JAK2V617F-induced myeloproliferative neoplasm

The somatic JAK2V617F mutation is found in a majority of patients with myeloproliferative neoplasms (MPN). Chronic inflammation is often associated with MPN, but the role of inflammation in the pathogenesis of MPN remains elusive. Expression of interleukin-1 (IL-1), a key regulator of inflammation, is found elevated in MPN. Here, we show that increased IL-1ß enhances myeloid cell expansion and promotes the development of bone marrow (BM) fibrosis in heterozygous Jak2V617F mouse model of MPN. Genetic deletion of IL-1 receptor 1 (IL-1R1) preferentially inhibited the expansion of Jak2 mutant hematopoietic stem/progenitor cells. Furthermore, IL-1R1 deletion or blockade with anti-IL-1R1 antibody significantly reduced leukocytosis and splenomegaly, and markedly inhibited BM fibrosis in homozygous Jak2V617F mutant mice. Collectively, our results suggest that IL-1 signaling plays an important role in progression to BM fibrosis in MPN, and targeting of IL-1R1 could be a useful strategy for the treatment of myelofibrosis. Overall design: RNA-sequencing on sorted LSK and LK cells from heterozygous Jak2V617F knock-in mice treated with vehicle (PBS) and IL-1ß. RNA-seq analysis on bone marrow (BM) mesenchymal stromal cells (MSC) stimulated with vehicle (PBS) and IL-1ß.