Baicalin promotes liver regeneration after acetaminophen-induced liver injury by inducing NLRP3 inflammasome activation

Liver regeneration has become a new hotspot in the study of drug-induced liver injury (DILI). Baicalin has already been reported to alleviate acetaminophen (APAP)-induced acute liver injury in our previous study. This study aims to observe whether baicalin also promotes liver regeneration after APAP-induced liver injury and to elucidate its engaged mechanism. Baicalin alleviated APAP-induced hepatic parenchymal cells injury and enhanced the number of mitotic and proliferating cell nuclear antigen (PCNA)-positive hepatocytes in APAP-intoxicated mice. Baicalin increased hepatic PCNA and cyclinD1 expression in APAP-intoxicated mice. Baicalin induced the activation of NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome, leading to the increased hepatic expression of interleukin-18 (IL-18) and IL-1β in APAP-intoxicated mice. The results in vitro demonstrated that IL-18 promoted the proliferation of human normal liver L-02 cells. Moreover, the baicalin-provided promotion on liver regeneration in APAP-intoxicated mice was diminished after the application of NLRP3 inhibitor MCC950 and the recombinant mouse IL-18 binding protein (rmIL-18BP). Baicalin induced the cytosolic accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2), and increased the interaction between Nrf2 with Nlrp3, ASC and pro-caspase-1 in livers from APAP-intoxicated mice. Furthermore, the baicalin-provided NLRP3 inflammasome activation and promotion on liver regeneration after APAP-induced liver injury in wild-type mice were diminished in Nrf2 knockout mice. In conclusion, baicalin promoted liver regeneration after APAP-induced acute liver injury in mice via inducing Nrf2 accumulation in cytoplasm that led to NLRP3 inflammasome activation, and then caused the increased expression of IL-18, which induced hepatocytes proliferation.