Serum retinol binding protein 4 and galectin-3 binding protein as novel markers for postmenopausal nonalcoholic fatty liver disease

Objective: To investigate the differential protein expression before and after menopause in women with nonalcoholic fatty liver disease (NAFLD) and to explore novel markers for menopausal NAFLD. Methods: Eight serum samples collected from pre-or post-menopausal women with NAFLD were analysed by iTRAQ 2D-LC-MS/MS. Two protein candidates were selected and verified by enzyme-linked immunosorbent assay (ELISA) in serum samples collected from a one hundred and fifty-three female population subsequently, including 51 in post-menopausal status with NAFLD, 41 in pre-menopausal with NAFLD, 19 healthy individuals in post-menopausal status and 42 healthy pre-menopausal women. Results: A total of one hundred and sixty-seven proteins exhibiting significant changes were characterized, among which sixty-five were up-regulated and one hundred and two were down-regulated. Of those altered proteins, the expression of serum retinol binding protein 4 (RBP4) and galectin-3 binding protein (LGALS3BP) was obviously increased in the post-menopausal patient group compared to the other. ELISA validations for the two proteins were consistent with the proteomic profiling. Conclusions: Serum RBP4 and LGAL3BP were up-regulated after menopause under NAFLD conditions, which suggested the two proteins may be potential markers as NAFLD in postmenopausal population.