Expression levels of T cell-related immune factors and their correlation with thyroid function in Graves' disease with varied serum iodine status: insights into immunopathogenesis.

Objective: Measurement of Serum Iodine Concentration (SIC) in Newly Diagnosed Adult Graves' Disease (GD) Patients with Hyperthyroidism and Healthy Controls: Investigating Cytokine Expression Profiles and Their Correlations with Thyroid Function Across Diverse Iodine Nutritional Status. Method: Patients newly diagnosed with GD hyperthyroidism from September 2024 to February 2025 at our institution were enrolled. Serum samples were collected for SIC measurement using arsenic-cerium catalytic spectrophotometry. Serum cytokine levels of 12 Th cell-related cytokines were quantified via LEGENDplex™ Human Th Cytokine Panel, and thyroid function was assessed by electrochemical immunoassay. Participants were stratified into three groups based on WHO iodine status criteria: iodine deficiency (<45 μg/L), adequate iodine (45-90 μg/L), and iodine excess (>90 μg/L). Pearson/Spearman correlation analyses were performed to evaluate associations between cytokine profiles and thyroid function parameters across subgroups. Results: Based on the inclusion and exclusion criteria, a total of 75 subjects were enrolled in this study. The SIC was 148.62 ± 17.63 μg/L (GD I group), 72.33 ± 12.08 μg/L (GD II group), and 75.24 ± 7.94 μg/L (NC group), respectively, with statistically significant differences among the three groups (P<0.001). In GD patients, SIC showed a positive correlation with TRAb levels (r = 0.136, P<0.001). Serum concentrations of IL-6, IL-4, IL-5, IL-13, IL-2, IFN-γ, TNF-α, IL-17A, and IL-22 in GD patients were significantly higher than those in the NC group, with the GD I group demonstrating notably elevated IL-6 levels compared to the GD II group (P<0.05). Correlation analysis revealed positive associations between IL-6 and SIC, TRAb, and IL-17A (r = 0.114, 0.105, 0.214; P < 0.05), while no correlations were observed with FT3, FT4, TSH, TPOAb, or TgAb levels (P > 0.05). Similarly, IL-17A exhibited positive correlations with SIC and IL-6 (r = 0.130, 0.214; P < 0.05), but showed no significant associations with FT3, FT4, TSH, TPOAb, or TgAb concentrations (P > 0.05). Conclusions: 1. Serum cytokine levels (including IL-6, IL-9, IL-17A, IL-17F, and IL-22) exhibited significant differences between healthy subjects and patients with newly diagnosed hyperthyroid Graves' disease (GD) under varying serum iodine concentration (SIC). 2. In newly diagnosed hyperthyroid GD patients, serum IL-6 demonstrated positive correlations with SIC, TRAb, and IL-17A (all P < 0.05), while IL-17A showed positive correlations with SIC and IL-6 (P < 0.05). 3. In GD patients with elevated SIC, cytokines IL-17A and IL-6 may contribute to pathogenic processes in hyperthyroid GD.