A protective role for human IL-10-expressing CD4+ T cells in colitis (121.11)

Abstract

Abstract Little is known about the relationship between cell- or tissue-specific IL-10 expression and disease susceptibility in humans. Here, we utilized the previously described hIL10BAC transgenic model to examine the role of human IL-10 (hIL-10) in maintaining intestinal homeostasis. Genomically-controlled hIL-10 expression rescued Il10−/− mice from Helicobacter-induced colitis and was associated with control of pro-inflammatory cytokine expression and TH17 cell accumulation in gut tissues. Resistance to colitis was associated with an accumulation of hIL-10-expressing CD4+Foxp3+ T regulatory cells specifically within the lamina propria but not other secondary lymphoid tissues. Co-transfer of CD4+CD45RBlo cells from Il10-/-/hIL10BAC mice rescued Rag1-/- mice from colitis further suggesting that CD4+ T cells represent a protective source of hIL-10 in the colon. In concordance with an enhanced capacity to express IL-10, CD4+CD44+ T cells isolated from the lamina propria exhibited lower levels of the repressive histone mark H3K27Me3 and higher levels of the permissive histone mark AcH3 in both the human and mouse IL10 locus compared to the spleen. These results provide experimental evidence verifying the importance of T cell-derived human IL-10 expression in controlling inflammation within the colonic mucosa. We also provide molecular evidence suggesting the tissue microenvironment influences IL-10 expression patterns and chromatin structure in the human (and mouse) IL10 locus.