Interleukin-10 acts directly on CD45RB lo but not CD45RB hi cells to control colitis upon transfer into Rag1-deficient recipients.
The role of direct IL-10 signaling in different T cell subsets is not well understood. To address this, we generated transgenic mice expressing a dominant-negative IL-10 receptor specifically in T cells (CD4dnIL-10Rα). We found that Foxp3-depleted CD45RB lo (regulatory T cell [T reg cell]–depleted CD45RB lo) but not CD45RB hi CD4 + T cells are controlled directly by IL-10 upon transfer into Rag1 knockout (KO) mice. Furthermore, the colitis induced by transfer of T reg cell–depleted CD45RB lo CD4 + T cells into Rag1 KO mice was characterized by reduced Th1 and increased Th17 cytokine messenger RNA levels in the colon as compared with the colitis induced by transfer of CD45RB hi T cells. In contrast to the CD45RB hi transfer colitis model, in which IL-22 is protective, we found that T cell–derived IL-22 was pathogenic upon transfer of T reg cell–depleted CD45RB lo T cells into Rag1 KO mice. Our results highlight characteristic differences between colitis induced by naive (CD45RB hi) and memory/effector (T reg cell–depleted CD45RB lo) cells and different ways that IL-22 impacts inflammatory bowel disease.