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Interleukin‐23 and T helper 17‐type responses in intestinal inflammation: from cytokines to T‐cell plasticity
Author(s) -
Morrison Peter J.,
Ballantyne Sarah J.,
Kullberg Marika C.
Publication year - 2011
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2011.03454.x
Subject(s) - immunology , biology , foxp3 , t helper cell , innate lymphoid cell , immune system , inflammatory bowel disease , inflammation , t cell , interleukin 23 , interleukin 17 , population , interleukin , acquired immune system , cytokine , disease , medicine , pathology , environmental health
Summary Interleukin‐23 (IL‐23) plays an essential role in driving intestinal pathology in experimental models of both T‐cell‐dependent and innate colitis. Furthermore, genome‐wide association studies have identified several single‐nucleotide polymorphisms in the IL‐23 receptor (IL‐23R) gene that are associated with either susceptibility or resistance to inflammatory bowel disease in humans. Although initially found to support the expansion and maintenance of CD4 + T helper 17 (Th17) cells, IL‐23 is now recognized as having multiple effects on the immune response, including restraining Foxp3 + regulatory T‐cell activity and inducing the expression of Th17‐type cytokines from non‐T‐cell sources. Here we focus on Th17 cells and their associated cytokines IL‐17A, IL‐17F, IL‐21 and IL‐22. We review studies performed in mouse models of colitis where these effector cytokines have been shown to have either a pathogenic or a tissue‐protective function. We also discuss the heterogeneity found within the Th17 population and the phenomenon of plasticity of Th17 cells, in particular the ability of these lymphocytes to extinguish IL‐17 expression and turn on interferon‐γ production to become Th1‐like ‘ex‐Th17’ cells. Interleukin‐23 has been identified as a key driver in this process, and this may be an additional mechanism by which IL‐23 promotes pathology in the intestinal tract. These ‘ex‐Th17’ cells may contribute to disease pathogenesis through their secretion of pro‐inflammatory mediators.