IL17A and obesity due to melanocortin 4 receptor deficiency: At the metabolic level, obesity is associated with elevated serum levels of free fatty acids, which sensitize human dendritic cells to amplify Th1/Th17 immune responses [51]; imiquimod-induced psoriasiform skin inflammation in obese mice is more severe than in lean mice, and is also associated with higher serum levels of IL-17, IL-22 and IL-23 [51].