Th22 Cells Lodge in Immunopathogenesis of Rheumatic Diseases

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 with distinguished gene expression and function. Th22 cells are characterized by production of a distinct profile of effector cytokines, including interleukin (IL)-22, IL-13, and tumor necrosis factor-α (TNF-α). The levels of Th22 and related cytokine IL-22 are increased in various autoimmune diseases and positively associated with some rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus, behcet''s disease, ankylosing spondylitis and psoriatic arthritis. In summary, IL-22 and Th22 cells play a significant and complicated role in inflammatory and autoimmune rheumatic diseases, therefore, targeting IL-22 or Th22 have unique and attractive advantages due to the fact that Th22 subset is recently identified and its associated research is extremely limited. This review discusses the role of Th22 and its cytokine IL-22 in the immunopathogenesis of rheumatic disease.