{gamma}{delta} T Cells Coexpressing Gut Homing {alpha}4{beta}7 and {alpha}E Integrins Define a Novel Subset Promoting Intestinal Inflammation [MUCOSAL IMMUNOLOGY]

T lymphocytes, dominant T cell subsets in the intestine, mediate both regulatory and pathogenic roles, yet the mechanisms underlying such opposing effects remain unclear. In this study, we identified a unique T cell subset that coexpresses high levels of gut-homing integrins, CD103 and α4β7. They were exclusively found in the mesenteric lymph node after T cell–mediated colitis induction, and their appearance preceded the inflammation. Adoptive transfer of the CD103⁺α4β7^high subsets enhanced Th1/Th17 T cell generation and accumulation in the intestine, and the disease severity. The level of generation correlated with the disease severity. Moreover, these cells were also found to be elevated in a spontaneous mouse model of ileitis. Based on the procolitogenic function, we referred to this subset as "inflammatory" T cells. Targeting inflammatory T cells may open a novel strategy to treat inflammatory diseases where T cells play a pathogenic role including inflammatory bowel disease.

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