[The influence of corticosteroids on IL-6/IL-6R system in patients with Graves' ophthalmopathy]

Abstract

IL-6 and its soluble receptor (IL-6R) appeared as reliable markers of inflammation activity in autoimmune diseases. The aim of the study was an estimation of serum IL-6 and sIL-R in patients with Graves' disease with ophthalmopathy during treatment with corticosteroids to assess their potential as a guideline of immunosuppressive therapy. We detected serum HIL-6 and IL-6R in three groups of subjects: 18 patients with clinical symptoms of ophthalmopathy (Clinical Activity Score > or = 3, anamnesis of GO > or = 1 yr), 16 patients with Graves' disease without ophthalmopathy (Gd) and 14 healthy volunteers. Corticosteroid therapy consisted of intravenous infusions of methylprednisolone (MP) and subsequent treatment with oral prednisone (P). The serum samples were collected 24 hours before MP, 24 hours after MP, 14 days of treatment with prednisone and after the end of the corticosteroid therapy. The levels of soluble IL-6 and IL-6R in the serum were determined by the ELISA method (Quantikine kit, R&D Systems, Minneapolis). The statistical significance was estimated by the Mann-Whitney U-test. IL-6 concentration was significantly increased in patients with GO in comparison to the controls (12.4 +/- 3.7 vs 11.8 +/- 3.2; p < 0.05). After MP treatment in corticosteroid-responsive patients (improvement in CAS < or = 1) serum concentration of sIL-6R decreased significantly in comparison to pretreatment values (32.8 +/- 4.2 vs 28.6 +/- 4.9; p < 0.05). We found a positive correlation between IL-6 concentration and degree of proptosis.

Conclusions: 1. IL-6/IL-6R system plays an important role in the pathogenesis of GO. 2. IL-6R is a potent prognostic factor for efficacy of the immunotherapy but further investigations are needed.