Th22 cells in autoimmunity: a review of current knowledge

Abstract

Newly identified T helper cell 22 (Th22) is a subset of CD4(+) T cells with specific properties apart from other known CD4(+) T cell subsets. Th22 is obviously discrete from Th17 and Th1 subsets by production of interleukin (IL)-22 but not IL-17 or IFN-gamma, and also with distinguished expression of aryl hydrocarbon receptor (AHR) as the key transcription factor. This T helper subset, by producing pro-inflammatory cytokines such as IL-22 and tumor necrosis factor-alpha (TNF-alpha), is implicated in the pathogenesis of inflammatory and autoimmune disorder. This review discusses the role of Th22 and its cytokine IL-22 in the immunopathogenesis of autoimmune disease including acute coronary syndrome, psoriasis, atopic dermatitis, rheumatoid arthritis, systemic lupus erythematosus, Behcet's disease, type 1 and 2 diabetes and immune thrombocytopenia.