Hypoxia-induced HMGB1 release in macrophages and its mechanism

Objective To investigate the extracellular release of high mobility group box 1(HMGB1) in macrophages induced by hypoxia and its possible mechanism.Methods The changes of HMGB1 mRNA expression,HMGB1 concentration in the culture medium and the intracellular distribution of HMGB1 were investigated after RAW264.7 macrophages were subjected to hypoxia(1% O2) with different hours.Inhibitory effect of N-acetylcysteine was observed on HMGB1 release.The HMGB1 concentration and the level of HMGB1 mRNA expression were determined by ELISA and real-time fluorescent quantitative PCR,respectively.Results The level of HMGB1 mRNA expression increased after RAW264.7 macrophages were subjected to hypoxia culture for 6 h(P0.05).The HMGB1 concentration in the culture medium significantly increased and nuclear HMGB1 was translocated to the cytoplasm after hypoxia culture for 12 h(P0.01).N-acetylcysteine partly inhibited extracellular release of HMGB1 in hypoxia-cultured RAW264.7 macrophages in a dose-dependent manner.Conclusion Hypoxia induces macrophages to release HMGB1,which may be involved with intracellular production of reactive oxygen species.