DOCK8 regulates protective immunity by controlling the function and survival of ROR?t+ ILCs

Retinoic-acid receptor-related orphan receptor-?t-positive (ROR?t+) innate lymphoid cells (ILCs) produce interleukin (IL)-22 and IL-17, which are critical for protective immunity against enteric pathogens. The molecular mechanism underlying the development and survival of ROR?t+ ILCs is not thoroughly understood. Here we show that Dedicator of cytokinesis 8 (DOCK8), a scaffolding protein involved in cytoskeletal rearrangement and cell migration, is essential for the protective immunity against Citrobacter rodentium. A comparative RNA sequencing-based analysis reveals an impaired induction of antimicrobial peptides in the colon of DOCK8-deficient mice, which correlates with high susceptibility to infection and a very low number of IL-22-producing ROR?t+ ILCs in their GI tract. Furthermore, DOCK8-deficient ROR?t+ ILCs are less responsive to IL-7 mediated signaling, more prone to apoptosis and produce less IL-22 due to a defect in IL-23-mediated STAT3 phosphorylation. Our studies reveal an unsuspected role of DOCK8 for the function, generation and survival of ROR?t+ ILCs. Overall design: Control and DOCK8 KO mice were infected with 2X109 CFU of Citrobacter rodentium and day 8 post infection mice were sacrificed and their colons were harvested (n=5) . Total RNA was purified from the infected colons with RNeasy mini kit (Qiagen). RNA sequencing was performed (pooled RNA sample from five mice in each group) at Genomic Core Facility Southwestern Medical Center, University of Texas.

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Singh AK, Eken A, Fry M, Bettelli E, Oukka M