Glycyrrhizin protects against porcine endotoxemia through modulation of systemic inflammatory response

INTRODUCTION: Glycyrrhizin (GL) was recently found to suppress high-mobility group box 1 (HMGB1)-induced injury by binding directly to it. However, the effect of GL on HMGB1 expression in endotoxemia as well as its underlying molecular mechanism remained unclear. METHODS: Twenty-one pigs were divided into four groups: sham group (n = 3), control group (n = 6), ethyl pyruvate group (n = 6) and glycyrrhizin group (n = 6). Pigs were anesthetized, mechanically ventilated, monitored and given a continuous intravenous infusion of lipopolysaccharide (LPS). Twelve hours after the start of the LPS infusion, ethyl pyruvate (30 mg/kg/hr) or glycyrrhizin (1 mg/kg/hr) was administered for 12 hours. Systemic and pulmonary hemodynamics, oxygen exchange, and metabolic status were measured. The concentrations of cytokines in serum and the corresponding gene and protein expressions in tissue samples from liver, lungs, kidneys, small intestine and lymph nodes were measured. RESULTS: GL maintained the stability of systemic hemodynamics and improved pulmonary oxygen exchange and metabolic status. GL also attenuated organ injury and decreased the serum levels of HMGB1 and other pro-inflammatory cytokines by inhibiting their gene and protein expression. CONCLUSIONS: GL improved systemic hemodynamics and protected vital organs against porcine endotoxemia through modulation of the systemic inflammatory response. By reducing the serum level and gene expression of HMGB1 and other pro-inflammatory cytokines, GL may become a potential agent for the treatment of sepsis.