HMGB1 and dermatomyositis: With regards to IIM, extra-nuclear HMGB1 expression has been demonstrated in the muscle of mice with experimental autoimmune myositis (Wang and Qin, 2016) and in muscle from IBM (Muth et al., 2015), PM, and DM (Ulfgren et al., 2004; Grundtman et al., 2010) patients.