The effect of methylprednisolone pulse treatment on cytokine network in Graves ophthalmopathy

The etiology of Graves ophthalmopathy (GO), representing the most common extrathyroidal manifestation of Graves disease, is multifactorial. Among multiple genetic, environmental, and endogenous factors, cytokines play a critical role in its etiopathogenesis. We studied an effect of glucocorticoid therapy on the serum IL-6, IL-4, and IL-13 levels in 18 GO patients. All the patients presented euthyroid GO with over 4 points according to the CAS classification (range 4-6; mean 4.94). The patients were treated with methylprednisolone (1 g every second day for three times) followed by 6 months oral prednisone (60 mg/day, with gradual reduction). The clinical examination (Clinical Activity Score and the GO severity by modified NOSPECS classification) and measurement of anti-TPO, anti-TG, anti-TSHR (TRAK), IL-6, IL-4, as well as IL-13 serum levels were performed before, after 2 weeks, and after 6 months of the glucocorticoid therapy. Significant serum IL-6 increases (p < 0.001) and moderate serum IL-4 and IL-13 increases (p < 0.05) were found in GO patients compared with healthy controls. After 2 weeks of the therapy, the serum IL-6 levels decreased in majority of the patients, however after 6-month observation, lower serum IL-6 levels were only in 8 patients who seemed to respond clinically to the therapy (mean value of the Clinical Activity Score decreased from 4.5 before the therapy initiation to 1.25 after 6 months of the glucocorticoid therapy). No changes in IL-4 and IL-13 serum levels during the therapy were observed. Statistical analysis revealed a good correlation between serum IL-6 level and the Clinical Activity Score (p < 0.01). Based on the obtained data, we conclude that IL-6 plays an important role in GO. It seems that IL-6 may serve as a useful factor in the inflammatory events of GO.