Glycyrrhizin improves inflammation and apoptosis via suppressing HMGB1 and PI3K/mTOR pathway in lipopolysaccharide-induced acute liver injury

C.-H. Shen, Z.-Y. Ma, J.-H. Li, R.-D. Li, Y.-F. Tao, Q.-B. Zhang, Z.-X. Wang

Department of General Surgery, Affiliated Huashan Hospital of Fudan University, Shanghai, China. wangzhengxin@huashan.org.cn

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• Pharmacology

OBJECTIVE: Acute liver injury (ALI) is mainly characterized by the symptom of metabolic disorders, homeostasis unbalance, and loss of liver function. There are no effective treatment methods at present stage except the liver transplantation. Effective treatment for early ALI is of great significance for the treatment of liver injury thereof. Glycyrrhizin (GL) is a promising inhibitor of the high-mobility group box-1 gene (HMGB1) which is expressed much higher in an inflammatory injury. However, it is not clear whether GL improves ALI via the inhibition of HMGB1. The present study is to probe the function and mechanism of glycyrrhizin on acute liver injury.

MATERIALS AND METHODS: The expression of HMGB1 and inflammation in liver macrophages were analyzed. Lipopolysaccharide (LPS) was used in stimulating the macrophages to activate inflammatory response and recombined human HMGB1 was used to resist the function of GL to explore whether GL acted via the target of HMGB1. Then, LPS injection was utilized to induce ALI in mice, and then we evaluated GL treatment in ALI model.

RESULTS: The results showed that the expressions of HMGB1 and inflammatory factors were markedly increased in LPS-activated liver macrophages. GL inhibited the progress of macrophages inflammation by restraining HMGB1, and the administration of GL could reverse the effects of LPS-induced ALI in mice. Moreover, PI3K/mTOR pathway was significantly suppressed by GL application.

CONCLUSIONS: These results suggest that GL prevents inflammation in liver macrophages via inhibition of HMGB1. GL restrains inflammation and cell apoptosis by inhibiting HMGB1 via PI3K/mTOR signaling pathway in ALI. GL may become a novel drug for the therapy of ALI in the future.

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