Magnesium isoglycyrrhizinate ameliorates lipopolysaccharide-induced liver injury by upregulating autophagy and inhibiting inflammation via IL-22 expression

Liver disease has become a major cause of premature mortality worldwide. It is well known that dysregulated inflammation response plays a crucial role in most liver diseases. As a Chinese medicinal herb, Magnesium isoglycyrrhizinate (MgIG) has been proven to have good hepatoprotective activity and has been used in clinic to treat liver disease. However, the mechanisms by which MgIG regulates LPS-induced liver injury and inflammation in vivo remain elusive. In our study, MgIG pretreatment mitigated LPS-induced liver damage by suppressing apoptosis and inflammation via regulating macrophage/neutrophil infiltration. MgIG ameliorated the effects of LPS on pro-oxidant enzymes (NOX1/2/4) and anti-oxidant enzymes (SOD1/2). Interestingly, we found that the level of the hepatoprotective cytokine interleukin (IL)–22 was significantly upregulated in MgIG-treated liver tissues, which might be a potential mechanism of MgIG against liver injury. Moreover, we found that MgIG treatment not only inhibited TLR4/MyD88/NF-κB signaling pathway, but also activated autophagy. Furthermore, IL-22 treatment activated autophagy and inhibited TLR4/NF-κB signaling pathway in vitro, suggesting that IL-22-activated autophagy and -inhibited inflammation also participated in the protective effects of MgIG. Altogether, our results uncovered the potential mechanisms of the hepatoprotective effects of MgIG, which provided critical evidence to support the use of MgIG to prevent and treat liver diseases.