Objective To investigate the protective effect of NDUFA13 protein against acute liver injury and liver fibrosis in mice and explore the possible mechanisms.Methods BALB/C mice(7 to 8 weeks old)were divided into normal group,CCl4 group,CCl4+AAV-NC group and CCl4+AAV-NDU13 group(n=18).Mouse models of liver fibrosis were established by intraperitoneal injection of CCl4 twice a week for 3,5 or 7 weeks,and the recombinant virus AAV8-TBG-NC or AAV8-TBG-NDUFA13 was injected via the tail vein 7-10 days prior to CCl4 injection.After the treatments,pathological changes in the liver of the mice were observed using HE and Masson staining.Hepatic expression levels of NDUFA13 and α-SMA were detected with Western blotting,and the coexpression of NDUFA13 and NLRP3,TNF-α and IL-1β,and α-SMA and collagen Ⅲ was analyzed with immunofluorescence assay.Results HE and Masson staining showed deranged liver architecture,necrotic hepatocytes and obvious inflammatory infiltration and collagen fiber deposition in mice with CCl4 injection(P<0.001).NDUFA13 expression markedly decreased in CCl4-treated mice(P<0.001),while a significant reduction in inflammatory aggregation and fibrosis was observed in mice with AAV-mediated NDUFA13 overexpression(P<0.001).In CCl4+AAV-NDU13 group,immunofluorescence assay revealed markedly weakened activation of NLRP3 inflammasomes(P<0.001),significantly decreased TNF-α and IL-1β secretion(P<0.001),and inhibited hepatic stellate cell activation(P<0.05)and collagen formation in the liver(P<0.001).Conclusion Mitochondrial NDUFA13 overexpression in hepatocytes protects against CCl4-induced liver fibrosis in mice by inhibiting activation of NLRP3 signaling.