Elevated IL-4 and IFN-γ Levels in Muscle Tissue of Patients with Dermatomyositis.

Background/aim: To investigate the contribution of muscle tissue-derived cytokines in dermatomyositis (DM).

Materials And Methods: Muscle homogenates were prepared from deltoid muscle biopsy specimens of 10 patients with DM and eight controls with no pathological signs of myopathy. Interleukin (IL)-4, interferon (IFN)-γ and IL-17 levels were evaluated by enzyme-linked immunosorbent assay (ELISA) and immunoblotting analysis. Muscle strength grades were recorded.

Results: Patients with DM showed significantly elevated muscle tissue IL-4 and IFN-γ levels, whereas IL-17 levels were comparable between patients with DM and controls. Immunoblotting studies confirmed ELISA results. In DM muscle specimens, IL-4 and IFN-γ levels were positively correlated, while no correlation was observed between IL-17 and the other two cytokines. Moreover, IL-4 and IFN-γ levels were significantly negative correlated with muscle strength grades for the deltoid muscle.

Conclusion: Our results confirm the involvement of T helper (Th) 1-type and Th2-type immunity in DM pathogenesis. Muscle tissue appears to contribute to muscle weakness in DM by producing inflammatory cytokines.