IL-33 controls IL-22-dependent antibacterial defense by modulating the microbiota [bulk RNA-seq]
IL-22 plays a critical role in defending against mucosal infections, but how IL-22 production is regulated is incompletely understood. Here, we show that mice lacking IL-33 or its receptor ST2 (IL-1RL1) were more resistant to Streptococcus pneumoniae lung infection than wild-type animals, and that single nucleotide polymorphisms in IL33 and IL1RL1 were associated with pneumococcal pneumonia in humans. The effect of IL-33 on S. pneumoniae infection was mediated by negative regulation of IL-22 production by innate lymphoid cells (ILCs), but independent of ILC2s as well as IL-4 and IL-13 signaling. Moreover, IL-33´s influence on antibacterial defense was dependent on the housing conditions of the mice, and mediated by IL-33´s modulatory effect on the intestinal microbiota. Collectively, we reveal that IL-33 controls IL-22-dependent antibacterial defense by modulating the microbiota. Our study thus provides insight into the bidirectional crosstalk between the innate immune system and the microbiota and how it shapes susceptibility to bacterial infection. Overall design: Infection with S.pneumoniae, single cell digestion of lungs, sort for CD127+ ST2+ CD90+ ILC2s, bulkseq of 7 samples