FGF21 and obesity due to melanocortin 4 receptor deficiency: Recently, treatment with FGF21 slowed the progression of obesity by downregulating ALT, AST and IL-6.34 There are recent reports that FGF21 attenuated CIA development, decreased inflammatory cytokine production and diminished the Th17-IL-17 axis via the STAT3 pathway.18, 35 We observed that metformin reduced the levels of inflammatory mediators, such as IKBKE, which is a therapeutic target for obesity-associated inflammation36 and a means to increase FGF21 production in the liver and BAT.