Impact of Fibroblast Growth Factors 19 and 21 in Bariatric Metabolism

Background: Bariatric surgery is a popular and effective therapeutic intervention for obesity, which is an abnormal health condition that is prevalent worldwide. Metabolic improvements that precede weight loss after bariatric surgery may be mediated, in part, through the fibroblast growth factor (FGF) 15/19 and FGF21 signaling pathways. Both FGF15/19 and FGF21 are hormone-like members of the FGF family and exert their metabolic effects in an endocrine manner. Enhanced bile acid recycling after bariatric surgery leads to increased circulating levels of FGF15/19 in the distal small intestine. Synthesis of FGF21 is upregulated predominately in the fasting state through peroxisome proliferator-activated receptor pathways and to a lesser extent by FGF15/19. Key Messages: The biological functions of FGF15/19 and FGF21 are diverse and complicated. The tissue targeted effects of FGF15/19 and FGF21 of importance after bariatric surgery include the regulation of hepatic bile acid biosynthesis and ketogenesis as well as thermogenesis in adipose tissue, respectively. Furthermore, FGF15/19 and FGF21 function to regulate carbohydrate and lipid metabolism.

Conclusion: The long-term effects of bariatric surgery on weight loss are undisputable. However, the mechanism for improvements in glucose and lipid homeostasis observed shortly after bariatric surgery is less understood. This review article attempts to describe the known metabolic effects of FGF15/19 and FGF21 that may potentiate these improvements after bariatric surgery.