Complementarity and redundancy of IL-22-producing innate lymphoid cells

Homeostasis of the gut microbiota is pivotal to the survival of the host. Intestinal T cells and Innate Lymphoid cells (ILCs) control the composition of the microbiota and respond to its perturbations. Interleukin 22 (IL-22) plays a pivotal role in the immune control of gut commensal and pathogenic bacteria and is secreted by a heterogeneous population of intestinal T cells, NCR- ILC3 and NCR+ILC3. Expression of NCR by ILC3 is believed to define an irreversible effector ILC3 end-state fate in which these cells are key to control of bacterial infection via their production of IL-22. Here we identify the core transcriptional signature that drives the differentiation of NCR- ILC3 into NCR+ ILC3 and reveal that NCR+ILC3 exhibit more plasticity than originally thought, as NCR+ ILC3 can revert to NCR- ILC3. Contrary to the prevailing understanding of NCR+ ILC3 genesis and function, in vivo analyses of mice conditionally deleted of the key ILC3 genes Stat3, Il22, Tbet and Mcl1 demonstrated that NCR+ ILC3 were not essential for the control of colonic infections in the presence of T cells. However, NCR+ ILC3 were mandatory for homeostasis of the caecum. Our data identify that the interplay of intestinal T cells and ILC3 results in robust complementary fail-safe mechanisms that ensure gut homeostasis. Overall design: Transcriptional profiling of wild-type and T-bet knockout innate lymphoid cells (ILC3) using RNA sequencing

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Rankin LC, Girard-Madoux MJ, Seillet C, Mielke LA, Kerdiles Y, Fenis A, Wieduwild E, Putoczki T, Mondot S, Lantz O, Demon D, Papenfuss AT, Smyth GK, Lamkanfi M, Carotta S, Renauld JC, Shi W, Carpentier S, Soos T, Arendt C, Ugolini S, Huntington ND, Belz GT, Vivier E