Differential expression of GPR15 on T cells during ulcerative colitis

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Abstract

G protein–coupled receptor 15 (GPR15) was recently highlighted as a colon-homing receptor for murine and human CD4⁺ T cells. The aim of this study was to explore the functional phenotype of human GPR15⁺CD4⁺ T cells, focusing on Tregs and effector T cells (Teffs), and to determine whether GPR15 is the driver for the migration of T cells to the colon during ulcerative colitis (UC). In the peripheral blood, GPR15 was expressed on Tregs and Teffs; both GPR15⁺ T cell subsets produced less IFN-γ and IL-4 but more IL-17 after stimulation and showed a higher migration activity compared with GPR15^–CD4⁺ T cells. In UC patients, GPR15 expression was increased on Tregs in the peripheral blood but not on Teffs. Interestingly, the expression of GPR15 was significantly enhanced on colonic T cells of UC patients in noninflamed biopsies but not in inflamed biopsies. The differential expression of GPR15 in UC patients was accompanied by a significant reduction of bacterial immunoregulatory metabolites in the feces. In conclusion, GPR15 expression on CD4⁺ T cells is altered in UC patients, which may have implications for the development of therapeutic approaches to target T cell trafficking to the colon.

Authors

Alexandra Adamczyk, Daniel Gageik, Annika Frede, Eva Pastille, Wiebke Hansen, Andreas Rueffer, Jan Buer, Jürgen Büning, Jost Langhorst, Astrid M. Westendorf