SYSTEMIC INVOLVEMENT OF HIGH-MOBILITY GROUP BOX 1 PROTEIN AND THERAPEUTIC EFFECT OF ANTI-HIGH-MOBILITY GROUP BOX 1 PROTEIN ANTIBODY IN A RAT MODEL OF CRUSH INJURY

Patients with crush injury often present systemic inflammatory response syndrome and fall into multiple organ failure. The mechanism by which the local tissue damage induces distant organ failure is still unclear. We focused on high-mobility group box 1 protein (HMGB1) as one of the damage-associated molecular pattern molecules that cause systemic inflammation in crush injury. We investigated involvement of HMGB1 and the effects of treatment with anti-HMGB1 antibody in a rat model of crush injury. Both hindlimbs of rats were compressed for 6 h and then released. In the crush injury group, the level of serum HMGB1 peaked at 3 h after releasing compression, followed by the increasing in the serum levels of interleukin 6 and tumor necrosis factor alpha. Hematoxylin-eosin staining showed substantial damage in the lung 24 h after the crush injury, with upregulation of the expression of receptor for advanced glycation end products, as revealed by immunohistochemical analysis. Intravenous administration of anti-HMGB1 antibody improved survival (n = 20 each group) and significantly suppressed serum levels of HMGB1, interleukin 6, and tumor necrosis factor ! compared with the untreated crush injury group (n = 6-9 each group). Histological findings of lung damage were ameliorated, and the expression of receptor for advanced glycation end products was hampered by the treatment. These results indicate that HMGB1 is released in response to damage immediately after crush injury and acts as a proinflammatory mediator. Administration of anti-HMGB1 antibody reduced inflammatory reactions and improved survival by blocking extracellular HMGB1. Thus, HMGB1 appears to be a therapeutic target, and anti-HMGB1 antibody may become a promising novel therapy against crush injury to prevent the progression to multiple organ failure.