GSE201292
Group 3 innate lymphoid cell pyroptosis represents a host defense mechanism against Salmonella infection
Group 3 innate lymphoid cells (ILC3s) produce interleukin (IL)-22 and, together with other cells in the gut, orchestrate to mount productive host immunity against bacterial infection. However, the role of ILC3s in Salmonella enterica serovar Typhimurium (S. Typhimurium) infection, which causes foodborne enteritis in humans, remains elusive. Here, we show that S. Typhimurium exploit ILC3-produced IL-22 to promote its infection. Specifically, S. Typhimurium secrete flagellin through activation of the TLR5-Myd88-IL-23 signaling pathway in antigen presenting cells (APCs) to selectively enhance IL-22 production by ILC3s, but not T cells. Deletion of ILC3s but not T cells in mice led to better control of S. Typhimurium infection. We also show that S. Typhimurium can invade ILC3s directly and cause caspase-1-mediated ILC3 pyroptosis independently of flagellin. Genetic ablation of Casp1 in mice leads to increased ILC3 survival and IL-22 production, and enhanced S. Typhimurium infection. Collectively, our data suggest a key host defense mechanism against S. Typhimurium infection via induction of ILC3 death to limit intracellular bacteria and reduce IL-22 production. Overall design: RNA-seq (3 replicates) analysis of ILC3 isolated from large intestine of S. Typhimurium infected (SL1344) mice vs uninfected (control) mice.