IL-17A Promotes RANTES Expression, But Not IL-16, in Orbital Fibroblasts Via CD40-CD40L Combination in Thyroid-Associated Ophthalmopathy

PURPOSE. This present study aims to investigate the phenotype of IL-17A-producing T cells in thyroid-associated ophthalmopathy (TAO) and the role of IL-17A on RANTES and IL-16 expression in orbital fibroblasts (OFs) from TAO patients. METHODS. Blood samples were obtained from TAO patients and healthy controls and were subjected to ELISA and flow cytometry analysis. Primary human OFs cultured from surgical wastes were stimulated with IL-17A in the presence or absence of CD40L and were examined by qRT-PCR, ELISA, Western blotting, and apoptosis assays. RESULTS. We reported upregulated IL-17A, IFN-gamma, RANTES, and IL-16 serum levels and increased frequency of IL-17A-and IFN-gamma-producing T cells in peripheral blood mononuclear cells from patients with TAO compared with healthy controls. In addition, TAO orbital tissues were rich in T lymphocytes, expressing more IL-17A, IFN-gamma, RANTES, and IL-16. Moreover, IL-17A could enhance the expression of RANTES, but not IL-16, in cultured primary OFs in cooperation with CD40L. We further validated that MAPK signaling was largely responsible for RANTES production in IL-17A-treated OFs. Finally, we demonstrated that IL-17A could not promote apparent apoptosis in OFs from TAO patients and healthy controls. CONCLUSIONS. Our results indicate the potent effect of IL-17A-induced RANTES expression on OFs and elaborate a possible mechanism in understanding Th17 cells in the pathology of TAO and its potential as a target to immunotherapy of TAO and other autoimmune disorders.