Paeoniflorin protects against liver ischemia/reperfusion injury in mice via inhibiting HMGB1-TLR4 signaling pathway

Hepatic ischemia/reperfusion (I/R) injury is a major cause of high morbidity and mortality after liver resection, transplantation, and hemorrhagic shock. Paeoniflorin (PF), the main substance of glucosides in Radix Paeoniae Alba, has been widely used to treat various hepatic inflammatory diseases including I/R injury. However, the underlying mechanisms of PF on hepatic I/R injury remain further investigated. In this study, the liver I/R model was performed by clamping the portal vein and hepatic artery with an atraumatic clamp for 90 min followed by 6 hr reperfusion. PF (100 mg/kg) was given three times a day by gavage before I/R. The blood and hepatic samples were collected to evaluate liver injury and molecular indexes. The results showed that PF pretreatment significantly inhibited I/R-induced serum ALT and AST activities (40.3% and 53.8% those of I/R group, respectively), hepatic pathological damages and hepatic apoptosis (P < 0.01), and infiltration of neutrophils into liver. In addition, PF suppressed the production of pro-inflammatory cytokines (P < 0.01), decreased the expression of high mobility group box-1 (HMGB1), and down-regulated toll-like receptors 4 (TLR4) and phosphorylated ERK1/2, JNK1/2, p38, and NF-kappa B signal molecules expression in the I/R-operated mice. These findings indicated that PF played a protective role in liver I/R injury, and this protection was associated with inhibition of I/R-activated HMGB1-TLR4 signaling pathway to attenuate hepatic inflammation responses.