Intestinal CD103(+)CD11b(-) dendritic cells restrain colitis via IFN-γ-induced anti-inflammatory response in epithelial cells.

A crosstalk between commensals, gut immune cells, and colonic epithelia is required for a proper function of intestinal mucosal barrier. Here we investigated the importance of two distinct intestinal dendritic cell (DC) subsets in controlling intestinal inflammation. We show that Clec9A-diphtheria toxin receptor (DTR) mice after depletion of CD103(+)CD11b(-) DCs developed severe, low-dose dextran sodium sulfate (DSS)-induced colitis, whereas the lack of CD103(+)CD11b(+) DCs in Clec4a4-DTR mice did not exacerbate intestinal inflammation. The CD103(+)CD11b(-) DC subset has gained a functional specialization that able them to repress inflammation via several epithelial interferon-γ (IFN-γ)-induced proteins. Among others, we identified that epithelial IDO1 and interleukin-18-binding protein (IL-18bp) were strongly modulated by CD103(+)CD11b(-) DCs. Through its preferential property to express IL-12 and IL-15, this particular DC subset can induce lymphocytes in colonic lamina propria and in epithelia to secrete IFN-γ that then can trigger a reversible early anti-inflammatory response in intestinal epithelial cells.