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IL-10 produced by macrophages regulates epithelial integrity in the small intestine

Morhardt, TL;Hayashi, A;Ochi, T;Quirs, M;Kitamoto, S;Nagao-Kitamoto, H;Kuffa, P;Atarashi, K;Honda, K;Kao, JY;Nusrat, A;Kamada, N;

Macrophages (Ms) are known to be major producers of the anti-inflammatory cytokine interleukin-10 (IL-10) in the intestine, thus playing an important role in maintaining gastrointestinal homeostasis. Ms that reside in the small intestine (SI) have been previously shown to be regulated by dietary antigens, while colonic Ms are regulated by the microbiota. However, the role which resident Ms play in SI homeostasis has not yet been fully elucidated. Here, we show that SI Ms regulate the integrity of the epithelial barrier via secretion of IL-10. We used an animal model of non-steroidal anti-inflammatory drug (NSAID)-induced SI epithelial injury to show that IL-10 is mainly produced by MHCII+ CD64+ Ly6Clow Ms early in injury and that it is involved in the restoration of the epithelial barrier. We found that a lack of IL-10, particularly its secretion by Ms, compromised the recovery of SI epithelial barrier. IL-10 production by MHCII+ CD64+ Ly6Clow Ms in the SI is not regulated by the gut microbiota, hence depletion of the microbiota did not influence epithelial regeneration in the SI. Collectively, these results highlight the critical role IL-10-producing Ms play in recovery from intestinal epithelial injury induced by NSAID.