Fibroblast growth factor-21 and omentin-1 hepatic mRNA expression and serum levels in morbidly obese women with non-alcoholic fatty liver disease

: Fibroblast growth factor-21 (FGF21) and omentin-1 have been recognized as potent antidiabetic agents with potential hepatoprotective activity. The aim of this study was to evaluate hepatic FGF21 and omentin-1 mRNA expression as well as their serum levels as predictive markers of liver injury and insulin resistance in morbidly obese women with non-alcoholic fatty liver disease (NAFLD). This study included 56 severely obese women who underwent intraoperative wedge liver biopsy during the bariatric surgery. Hepatic FGF21 and omentin-1 mRNA were assessed by quantitative real-time PCR, while their serum concentrations were measured with commercially available enzyme-linked immunosorbent assays. The FGF21 serum level was significantly higher in patients with a greater extent of steatosis (grade 2 and 3) compared to those without or with mild steatosis (grade 0 and 1) (P = 0.049). Receiver Operating Characteristic analysis, however, showed poor discriminant power for the FGF21 serum levels in differentiating between more and less extensive steatosis with an AUC = 0.666. There was a tendency towards higher levels of hepatic FGF21 mRNA in patients with lobular inflammation and fibrosis and towards lower levels in the case of hepatocyte ballooning and steatosis. There was a positive mutual correlation between hepatic FGF21 and omentin-1 mRNA levels (r = 0.78; P < 0.001). Fibrosis stage was associated with serum glucose and homeostatic model assessment for insulin resistance (HOMA-IR) (P = 0.03 and P = 0.02, respectively). Serum omentin-1 was not associated with histopathological features. The hepatic omentin-1 mRNA levels showed a tendency to be lower in patients with advanced steatosis and hepatocyte ballooning. In conclusion, our study, which focused on hepatic FGF21 and omentin-1 mRNA expression, confirmed marked expression of both molecules in the liver of morbidly obese patients with NAFLD. More extensive steatosis was associated with evident changes in the serum FGF21 concentration in morbidly obese women with NAFLD, but the difference did not reach statistical significance. The vast amount of fat, both visceral and subcutaneous, in severely obese patients may be the additional source and influence the FGF21 and omentin-1 serum levels.