Clinical relevance of estimating circulating interleukin-17 and interleukin-23 during methylprednisolone therapy in Graves' orbitopathy: A preliminary study

Purpose: Graves' orbitopathy (GO) is an important problem in endocrinology. Currently used methods of assessing the degree of activity of the autoimmune process are not satisfactory. Therefore, there is a need to establish indicators of greater utility. Patients and methods: The study included 35 patients: 15 with GO, 10 with Graves' disease (GD) without GO and 10 controls. Patients with GO received methylprednisolone (MP) for 12 weeks. Concentrations of thyrotropin receptor antibodies (TSHRab), interleukin 17 (IL-17) and 23 (IL-23) were obtained before administering the first dose of MP, after 6 and 12 weeks of therapy, and 3 months after treatment cessation. Patients were classified as responders (n 1/4 11) if a reduction of >2 points in the Clinical Activity Score (CAS) was observed. Results: A significant decrease in exophthalmos, muscles' thickness and CAS value was demonstrated after MP treatment in responders group. Significantly higher concentrations were found in baseline IL-23 between the GD and GO groups compared to controls. No statistically significant differences in serum concentrations of IL-17 and IL-23 were observed during treatment with MP and 3 months after treatment cessation. A statistically significant reduction in TSHRab concentration was demonstrated 3 months after treatment cessation compared to baseline values in responders group. Conclusions: Low baseline IL-17 concentration, in addition to high TSHRab titre, serves as marker of disease activity. Although, we expect that low IL-23 concentration, in addition to high TSHRab titre, could be used as predictors of disease activity and a prognostic factor of response to immunosuppressive therapy in GO.