Increased level of high mobility group box 1 in the serum and skin in patients with generalized pustular psoriasis

High‐mobility group box 1 (HMGB‐1) is a highly abundant pro‐inflammatory protein associated with the pathogenesis of inflammatory and autoimmune diseases. HMGB‐1 expression level increases in patients with psoriasis vulgaris (PV). However, HMGB‐1 expression in patients with generalized pustular psoriasis (GPP) is unknown. In this study, we investigated HMGB‐1 expression in GPP. HMGB‐1 expression levels were examined in the skin and serum of patients with GPP, PV, atopic dermatitis (AD) and healthy controls (HC) using enzyme‐linked immunosorbent assay and immunohistochemistry. The elevation in HMGB‐1 expression was significantly higher in GPP patients than in PV, AD and HC patients. In addition, patients with GPP had elevated serum HMGB‐1 levels compared with those with AD and HC. Furthermore, serum HMGB‐1 levels were significantly decreased after systemic treatment. In the correlation analysis, a significant positive correlation was detected between serum HMGB‐1 levels and the Japanese severity score for GPP. HMGB‐1 may be involved in the pathogenesis of GPP and can be useful to evaluate disease severity and the effectiveness of GPP treatment.