Reverse genetics in humanized mice reveals CARD8-mediated pyroptosis causing pancytopenia in human DPP9 deficiency

Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine

Loss-of-function mutation in the human gene dipeptidyl peptidase 9 () causes Hatipoglu syndrome leading to severe inflammasomopathy. A key feature of the disease is pancytopenia, and patients require bone marrow transplantation, but the mechanism of cell loss is unclear, since-mutant mice have normal hematopoiesis, suggesting that a distinct mechanism of disease occurs in humans. Here, we present a model of human DPP9 deficiency leveraging reverse genetics in the MISTRG6 humanized mice. We found that CRISPR editing of human CD34hematopoietic stem and progenitor cells (HSPCs) led to very efficient and persistent gene deletion in vivo. Humandeletion recapitulated cytopenia in peripheral blood and in the bone marrow, and cell loss was cell intrinsic. However,deletion led to few transcriptional changes suggesting posttranscriptional regulation in human HSPCs. Mechanistically, DPP9 deficiency led to activation of the CARD8 inflammasome, resulting in HSPC pyroptosis, whereas NLRP1 was dispensable for cell death. Thus, our results reveal a unique human mechanism of disease and offer therapeutic insight for this inflammasomopathy. We develop a new way to model human genetic disease and discover why patients with DPP9 deficiency have loss of blood cells. toc