HMGB1 and ventilator-associated pneumonia: Thus, the aim of this study was to determine the effects of GTS-21 on (1) hyperoxia-reduced host defense to clear PA infection in a mouse model of VAP, (2) hyperoxia-induced suppression of macrophage phagocytosis, and (3) the accumulation of extracellular HMGB1 in the airways of animals subjected to prolonged exposure to hyperoxia and PA lung infection.