Lipidomic Profiling Reveals the Effect of Egg Components on Nonalcoholic Steatosis in HepG2 Cells and Its Involved Mechanisms

Non-alcoholic fatty liver disease (NAFLD) is a major cause of cardiovascular disease. The relationship between egg consumption and NAFLD is still controversial for its high cholesterol content. In this study, the effects of different egg components (egg white (EW), egg yolk (EY), and whole egg (WE)) on NAFLD are examined using oleic acid (OA)-induced HepG2 cells with UPLC-ESI-MS/MS approach. The results show EY could affect the lipid profile effectively by increasing phosphocholine (PC), phosphatidylglycerol (PG), and carnitine (CAR). Orthogonal projections to latent structures-discriminate analysis (OPLS-DA) combine with S-plot analysis select 10, 82, and 20 potential biomarkers in EW, EY, and WE group, respectively. Up-regulated TG, DG, and down-regulated lysophosphatidylcholines (lysoPC), lysophosphatidylethanolamine (lysoPE) biomarkers are found in EY group, while down-regulated TG and FFA are found in EW and WE group. Glycerolipid and choline metabolism are the most involved pathways affected by EY and WE. In addition, the mechanism is associated with the expression of Pla2g15, Pnpla6-1, Gad1, and involved lipogenic genes ABC1 and PPAR alpha. This study suggests that WE treatment can ameliorate OA-induced hepatic steatosis by inhibiting TG accumulation, while EY seems slightly accelerate hepatic steatosis. Furthermore, the effects are closely associated with its effects on glycerolipid metabolism. Practical applications: Nonalcoholic fatty liver disease (NAFLD) is a worldwide disease, while the associations between egg consumption and NAFLD are still poorly understood. This study investigates the effects of egg components on NAFLD in oleic acid (OA)-induced HepG2 cells based on a targeted lipidomics approach. The results indicate that WE (whole egg) treatment could ameliorate OA-induced hepatic steatosis by inhibiting TG and FFA accumulation, which is closely associated with glycerolipid metabolism. The results provide knowledge and understanding of the effects of egg on NAFLD and involved mechanism, and further provided nutritional guidelines for egg consumption.