Unbalanced helper T cell function in Behcet's disease

Abstract

Behcet's disease (BD) is a multisystem inflammatory disease that is characterized by re-current attacks of uveitis, oral apthous ulcers, genital ulcers, and erythema nodosum. The eti-ology and pathogenesis of BD are largely unknown. We have presented evidence that sup-ports a role of excessive Th1 cell activity in BD. Recently, it has been suggested that Th17 cells are associated with several autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease, all of which are considered to be Th1 diseases. Therefore, it is interesting to study the role of Th17-related cytokines and Th17-associated signaling molecules in BD. Major Th17-related cytokines were not detected in peripheral blood mononuclear cells (PBMCs) and in skin lesions of BD patients. Expression of TGF-beta receptor and Smad2 mRNA was significantly higher in BD patients compared with the levels in normal controls. Interleukin (IL)-23 receptor, ROR-C, and Foxp3 are key transcription fac-tors expressed by Th17 cells and regulatory T cells, respectively, and their expression was de-creased in BD. These findings suggest that T cell function may be unbalanced in BD.