Resistin in idiopathic inflammatory myopathies

ABSTRACT: INTRODUCTION: To evaluate and compare the serum levels and local expression of resistin in patients with idiopathic inflammatory myopathies to controls, and to determine the relationship between resistin levels, inflammation and disease activity. METHODS: Serum resistin levels were determined in 42 patients with inflammatory myopathies and 27 healthy controls. The association between resistin levels, inflammation, global disease activity and muscle strength was examined. The expression of resistin in muscle tissues from patients with inflammatory myopathies and healthy controls was evaluated. Gene expression and protein release from resistin-stimulated muscle and mononuclear cells were assessed. RESULTS: In patients with inflammatory myopathies, the serum levels of resistin were significantly higher than those observed in controls (8.53+/-6.84 vs. 4.54+/-1.08 ng/ml, P<0.0001) and correlated with CRP levels (r=0.328, P=0.044) and global disease activity score MYOACT (r=0.382, P=0.026). Stronger association was observed between the levels of serum resistin and C-reactive protein (CRP) levels (r=0.717, P=0.037) as well as myositis disease activity assessment visual analogue scales (MYOACT; r=0.798, P=0.007), and there was a trend towards correlation between serum resistin and myoglobin levels (r=0.650, P=0.067) in anti-Jo-1 positive patients. Furthermore, in patients with DM, serum resistin levels significantly correlated with MYOACT (r=0.667, P=0.001), creatine kinase (r=0.739, P=0.001) and myoglobin levels (r=0.791, P=0.0003) and showed a trend towards correlation with CRP levels (r=0.447, P=0.067). Resistin expression in muscle tissue was significantly higher in patients with inflammatory myopathies compared to controls, and resistin induced the expression of interleukins (IL)-1beta and IL-6 and monocyte chemoattractant protein (MCP)-1 in mononuclear cells but not in myocytes. CONCLUSIONS: The results of this study indicate that higher levels of serum resistin are associated with inflammation, higher global disease activity index and muscle injury in patients with myositis-specific anti-Jo-1 antibody and patients with dermatomyositis. Furthermore, up-regulation of resistin in muscle tissue and resistin-induced synthesis of pro-inflammatory cytokines in mononuclear cells suggest a potential role for resistin in the pathogenesis of inflammatory myopathies