Numerous studies have indicated that IL-22 administration activates hepatic STAT3 signaling and ameliorates several liver diseases, including autoimmune hepatitis, viral hepatitis, drug-induced liver injury, alcoholic fatty liver and steatohepatitis (Dumoutier et al., 2009; Ki et al., 2010; Wolk et al., 2010). This evidence concerns the gene STAT3 and animal viral hepatitis.