Abstract:

Objective To analyze the role of IL-21 in IL-17 upregulation of patients with Graves disease (GD). Methods Thirty patients with GD were enrolled as GD group; 17 patients with euthyroid GD after treatment, as eGD group; and 18 healthy subjects, as control group. Electrochemical luminescence detection was used to determine levels of thyroid function indexes (FT3, FT4, and uTSH) and autoantibodies (TgAb, TPOAb, and TRAb). The peripheral blood mononuclear cells (PBMCs) were cultured in the presence or absence of IL-21 in vitro. The level of IL-17 protein was measured by enzyme-linked immunosorbent assay (ELISA), and expressions of IL-17 and RORγt mRNA were examined by semi-quantitative RT-PCR. Results Compared to control and eGD groups, there were significantly differences in the levels of thyroid function indexes in GD group (P<0.05), whereas there was no difference between control group and eGD group (P>0.05). Before IL-12 stimulation, compared to control group, expressions of IL-17 and RORγt mRNA and level of IL-17 protein were significantly higher in GD and eGD groups (P<0.05); but there were no significant differences between GD group and eGD group (P>0.05). After IL-12 stimulation, expressions of IL-17 and RORγt mRNA and IL-17 protein levels markedly increased in all three groups, which were significantly higher in GD and eGD groups compared to control group (P<0.05). There were no differences of the values between GD group and eGD group (P>0.05). Conclusion The results indicated that IL-21 involved in the pathogenesis of GD through IL-17 upregulation, which might be not dependent on thyroid function but be related to autoimmunity.

Key words: IL-21, IL-17, Graves disease, immunity