Augmenter of Liver Regeneration Protects Against Acetaminophen-Induced Acute Liver Injury in Mice by Promoting Autophagy

Abstract

Most cases of acute liver failure are caused by acetaminophen (APAP) overdose. Oxidative stress is a key factor in APAP toxicity. Although augmenter of liver regeneration (ALR) has both antioxidative and antiapoptotic effects, its therapeutic potential in APAP hepatotoxicity remains unknown. The current study assessed the protective effects and associated mechanisms of ALR against APAP-induced acute liver injury in female BALB/c mice. We found that serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, intrahepatic hemorrhage and necrosis were increased at 3, 6, 12, 24, 48, and 72h after 600mg/kg APAP i.p. injection. During the early stages (before 12h) of acute liver injury, ALR levels increased significantly, followed by a decrease to control level at 24h after APAP administration. ALR treatment increased autophagosomes, promoted the conversion of LC3 I to LC3 II, and the degradation of p62. ALR attenuated APAP-stimulated increases in ALT, AST, myeloperoxidase (MPO), malondialdehyde (MDA), and reactive oxidative species (ROS) levels; intrahepatic hemorrhage; and necrosis as well as superoxide dismutase (SOD) and Glutathione (GSH) depletion. We found that APAP caused release of the mitochondrial intermembrane proteins apoptosis-inducing factor (AIF) and cytochrome c and that ALR inhibited this change. Meanwhile, ALR decreased expression of cleaved-caspase 3 and apoptotic cells. Subsequently, we investigated the significance of autophagy in APAP-induced acute liver injury by treatment with 3-methyladenine (3-MA), which were classical pharmaceuticals for suppressing autophagy. ALR directly induced autophagy flux; and the inhibition of autophagy reversed the beneficial effects of ALR on hepatotoxicity. Our findings suggest that ALR protects against APAP hepatotoxicity by activating the autophagy pathway.