IL22 and fatty liver disease: Administration of recombinant IL-22 fusion protein or induction of IL-22 signaling by therapeutic agents was proven to relieve hepatic steatosis and reverse various metabolic symptoms by downregulating expression of genes related to lipogenesis and triglyceride synthesis, alleviating lipotoxic substrate-induced oxidative/ER stresses, and maintaining intestinal barrier integrity in db/db- or HFD-fed obese mice [26,27].