HMGB1 and dermatomyositis: HMGB1 levels in serum of PM and DM patients were higher than that of healthy controls and higher in patients with Interstitial lung disease. Patients with high levels of HMGB1 had lower overall survival and disease-free survival. HMGB1/RAGE axis was involved in the amyloid deposition in muscle tissue of IBM patients. HMGB 1 could promote inflammation muscle fatigue and induce expression of MHC1 molecules in the early stage of the disease but promote the protection and regeneration of muscle tissue in the late stage of the disease.