The pathological role of visceral fat accumulation in steatosis, inflammation, and progression of nonalcoholic fatty liver disease.

BACKGROUND

Our previous studies have indicated a close association between visceral fat accumulation and hepatic steatosis in nonalcoholic fatty liver disease (NAFLD). This study investigated whether visceral fat accumulation was related to the pathogenesis and disease progression of nonalcoholic steatohepatitis (NASH)/NAFLD.

METHODS

First, a total of 550 subjects who underwent a health checkup and measurement of visceral fat accumulation, done with a bioelectrical impedance analyzer (X-SCAN; Owa Medical, Fukuoka, Japan), were included. The relationship between visceral fat accumulation and biochemical parameters was examined. Second, a total of 74 patients with NASH/NAFLD who underwent liver biopsy were reviewed. Visceral fat accumulation was determined by abdominal computed tomography. The association between visceral fat accumulation and the histopathological grade/stage determined by the NAFLD activity score and Brunt's classification was evaluated.

RESULTS

There was a significant relationship between visceral fat accumulation and glucose, triglyceride, and alanine aminotransferase (ALT; r = 0.423, P < 0.01). In stepwise regression analysis, visceral fat area (VFA), serum triglyceride level, and serum low-density lipoprotein (LDL)-cholesterol level were selected as predictor variables for serum ALT level, in a continuous manner (serum ALT level = -1.359 + 0.143 × VFA + 0.046 × triglyceride + 0.059 × LDL, R(2) = 0.217, P < 0.001). In patients with NASH, there was no correlation between histological grade and the visceral fat volume. Visceral fat accumulation in patients with stage 3/4 advanced NASH was greater than that in patients with stage 1/2 early NASH (P < 0.05).

CONCLUSIONS

These results suggest that visceral fat accumulation plays a role in steatosis and fibrosis in the pathogenesis and prognosis of NAFLD.