Effects of inflammation on FAT/CD36 expressions in HepG2 cells loaded with fatty acids

Objective:To investigate the effects of inflammatory cytokines on expressions of fatty acid transporter/CD36(FAT/CD36) in HepG2 cells loaded with fatty acids.Methods:HepG2 cells were cultured and treated with palmitate at concentrations of 0.00,0.04,0.08,0.16,0.32 mmol/L for 24 h.Protein and mRNA expressions of FAT/CD36 were detected by Western blot and real-time PCR,respectively.Intracellular lipid droplet formation was determined by Oil red O staining.Then the HepG2 cells were cultured and treated with palmitate at concentration of 0.04 mmol/L combined with tumor necrosis factor-α(TNF-α)(25 ng/ml) or interleukin-6(IL6)(20 ng/ml) for 24 h.Effects of inflammatory cytokines on the protein and mRNA levels of FAT/CD36 in HepG2 cells were also investigated.Oil red O staining was used to determine the intracellular lipid droplet formation.Intracellular triglyceride(TG) and free fatty acid(FFA) were measured by enzymic assay and ELISA,respectively.Results:Palmitate loading dose-dependently increased the protein and mRNA expressions of FAT/CD36 and intracellular lipid levels(r=0.873,P=0.000;r=0.884,P=0.000).Inflammatory cytokines further increased the protein and mRNA expressions of FAT/CD36 in HepG2 cells loaded with palmitate(P=0.001,P= 0.000).Oil red O staining and intracellular TG and FFA quantitative detection all showed that inflammatory cytokines can promote lipid accumulation of HepG2 cells.Based on intracellular TG quantitative detection:palmitate + TNF-α group vs.control group,P= 0.009,P=0.037;palmitate + IL-6 group vs.control group and palmitate group,all P=0.000.Based on intracellular FFA quantitative detection:palmitate + TNF-α group vs.control group and palmitate group,P=0.001,P=0.002;palmitate + IL-6 group vs.control group and palmitate group,all P=0.000.Conclusions:Inflammatory cytokines up-regulate the expression of FAT/CD36 in HepG2 cells loaded with fatty acids and exacerbate the intracellular lipid accumulation.