Clinical relevance of estimating circulating interleukin-17 and interleukin-23 during methylprednisolone therapy in...

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.

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 ​= ​11) if a reduction of ≥2 points in the Clinical Activity Score (CAS) was observed.

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.

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.