ID: 192: Role of AhR in IL-22 production by four types of immune cells, including CD4-CD8- TCRß T cells, present in psoriasis-like skin after topical imiquimod
IL-22 has a detrimental role in skin inflammatory processes, particularly in the imiquimod-induced psoriasis model. As transcription factor AhR controls IL-22 production by several cell types, we analyzed its role in IL-22 production by immune cells in the inflamed skin. We used a model in which imiquimod is applied on the ears. Our results indicate that IL-22 is still expressed in the skin of imiquimod-treated AhR−/− mice but in lesser amounts than in wild-type mice. We then studied the role of AhR on each of the three cell populations known to produce IL-22 in the skin: γ δ T cells, Th17 cells and ILC3. We studied also a new IL-22 producing cell type that we identified in this setting: CD4-/CD8- TCR β + T cells. In the imiquimod-treated ears, AhR was required for IL-22 production by Th17 but not by the three other cell types. For the latter but not for Th17 cells, AhR had a role in their recruitment into the inflamed skin or in their local proliferation, as their numbers were reduced in AhR−/− vs wild-type imiquimod-treated ears.