Nucleophosmin 1 Promotes Mucosal Immunity by Supporting Mitochondrial Oxidative Phosphorylation and ILC3 Activity

NPM1 is commonly mutated in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Concurrent inflammatory bowel diseases (IBD) and MDS have been reported frequently, indicating a close relationship between IBD and MDS. Here, we examined the role of NPM1 in IBD and colitis-associated colorectal cancer (CAC). NPM1 was reduced in IBD patients. Npm1+/- mice were more susceptible to acute colitis and experimentally induced CAC than littermate controls. Npm1 deficiency impaired the function of IL-22-producing group 3 innate lymphoid cells (ILC3s). Mice lacking Npm1 in ILC3s exhibited decreased IL-22 production and accelerated development of colitis. NPM1 was important for mitochondrial biogenesis and metabolism by oxidative phosphorylation in ILC3s. Further experiments revealed that NPM1 cooperates with p65 to promote TFAM transcription in ILC3s. Overexpression of Npm1 in mice enhanced ILC3 function and reduced severity of DSS-induced colitis. Thus, our findings suggest the protective function of NPM1 in ILC3s against IBD by regulating mitochondrial metabolism through p65-TFAM axis. Overall design: To uncover mechanisms by which NPM1 regulates ILC3 expansion and function, we performed RNA sequencing (smart-seq2) of Live+Lin-CD45lowCD90high LPLs from colon of WT and Npm1+/- mice with colitis induced by DSS treatment.