IL22 and obesity due to melanocortin 4 receptor deficiency: IL-22 also preserves the endocrine functions and the gut mucosal barrier, alleviates epithelial injury, and restores gut integrity, thus preventing LPS-induced systemic endotoxemia and adipose inflammation during obesity, regulating lipid metabolism in the liver and adipose tissue, and ameliorating hepatic steatosis via STAT3 activation [44].