Malvidin protects against lipopolysaccharide-induced acute liver injury in mice via regulating Nrf2 and NLRP3 pathways and suppressing apoptosis and autophagy

Sepsis-related acute liver injury (ALI) is a fatal disease associated with many complications. Recent studies indicate that malvidin, an active flavonoid, has multiple bioactivities including anti-oxidant and anti-inflammation. However, the protective roles of malvidin against LPS-induced ALI are unknown. The purpose of this research is to explore whether malvidin has biological activities on LPS-induced ALI in mice and the underlying mechanisms. Male C57 mice were injected intraperitoneally with malvidin for five days and the mice were euthanized 6 h after LPS (10 mg/kg body weight) intraperitoneal injection. Multiple methods of H&E staining, biochemical kits, qRT-PCR assay, western blotting analysis, TUNEL and transmission electron microscope (TEM) were used. Results showed that decreased ALT, AST levels and alleviated histopathological damage of liver tissue were observed in malvidin pretreatment group in mice. Then, malvidin prevented LPS-induced reduction of antioxidant enzyme activities such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) via up-regulating nuclear factor E2-related factor2 (Nrf2) pathway. In addition, in malvidin pretreatment groups, mRNA levels of pro-inflammatory cytokines (TNF-α，IL-1β, IL-6) and protein levels of NOD-like receptor protein 3 (NLRP3) inflammasome in the liver were significantly down-regulated. We also found that the malvidin could reduce the expression of apoptosis key protein and TUNEL-labeled apoptotic hepatocytes. Furthermore, malvidin inhibited the protein expression of ATG5, p62 and the ratio of LC3-II/LC3-I. In conclusion, our study firstly suggests that malvidin is a potentially protective agent against LPS-induced ALI through up-regulating Nrf2 signaling pathway, suppressing NLRP3 inflammasome and inhibiting apoptosis and autophagy.