Serum retinol-binding protein 4 in patients with nonalcoholic fatty liver disease: does it have a significant impact on pathogenesis?

Abstract

Objectives: Conflicting data have been reported in the literature about the role of retinol-binding protein 4 (RBP4) in insulin sensitivity, type 2 diabetes, and obesity in humans. It is of interest whether serum RBP4 is associated with various features of nonalcoholic fatty liver disease (NAFLD).

Methods: Serum RBP4, adiponectin, leptin, and resistin were measured by enzyme-linked immunosorbent assay in 76 nondiabetic NAFLD patients, 55 of whom had elevated alanine aminotransferase (ALT). Thirty-four of 55 underwent a liver biopsy. Fasting insulin, liver and lipid panels were analyzed and ultrasound score, body mass index, and homeostasis model assessment for insulin resistance were recorded for each patient. Twenty-four healthy individuals served as controls.

Results: Serum RBP4 levels were not different between the steatosis group and controls as well as between the groups with high and normal ALT. Serum adiponectin was significantly lower and resistin was higher (P<0.001) in steatosis group compared with controls. RBP4 and resistin were negatively correlated, whereas leptin and resistin were correlated positively in patients with high ALT. At multivariate analysis, homeostasis model assessment for insulin resistance [odds ratio (OR): 10.71; 95% confidence interval (95% CI): 1.40-81.74], leptin (OR: 22.14; 95% CI: 2.40-204.12), resistin (OR: 6.29; 95% CI: 0.94-41.91), ALT (OR: 1.205; 95% CI: 1.05-1.39), and aspartate aminotransferase (OR: 0.846; 95% CI: 0.72-0.99) were independent variables associated with steatosis. Serum leptin, adiponectin, resistin, gamma-glutamyl transferase, and cholesterol were associated with histological activity by multivariate linear regression.

Conclusion: Serum RBP4 is not a predictive factor in NAFLD irrespective of ALT. Low adiponectin, elevated resistin, and leptin were significantly associated with necroinflammation.