Anti-TIF1γ antibody and the expression of TIF1γ in idiopathic inflammatory myopathies

Objective Anti-transcriptional intermediary factor 1 (TIF1) antibody is associated with idiopathic inflammatory myopathies (IIMs). The aim of this study was to investigate the expression of TIF1s in IIMs. Method TIF1 alpha, beta or gamma expression in the skin and muscle of patients and controls was studied by immunohistochemistry. Serum myositis-specific autoantibodies were detected by immunoblot. Results TIF1 alpha was expressed in the skin of most dermatomyositis (DM) patients but not in the controls (80% vs 0%, P < 0.001). TIF1 beta was expressed in all tissues of patients and controls. TIF1 gamma was expressed in the muscle of DM patients compared to controls (42.1% vs 0%, P = 0.039) and associated with tubuloreticular bodies (P = 0.003). Anti-TIF1 gamma was related with TIF1 gamma expression in the muscle (P = 0.042). Conclusion TIF1 alpha expression in the skin and TIF1 gamma in the muscle of DM was increased compared to controls. TIF1 gamma expression in the muscle of IIMs was related to anti-TIF1 gamma antibody.