Inflammatory cytokines up-regulate FAT/CD36 expression in renal cells loaded by fatty acids

AIM: To investigate the effects of inflammatory cytokines on the expression of fatty acid transporter (FAT/CD36) in renal cells loaded by fatty acids. METHODS: Human mesangial cells (HMCs) and renal tubular epithelial HK-2 cells were treated with palmitate at concentrations of 0 mmol/L, 0.02 mmol/L, 0.04 mmol/L, 0.08 mmol/L, 0.16 mmol/L and 0.32 mmol/L for 24 h. The expression of FAT/CD36 at mRNA and protein levels was detected by real-time PCR and Western blotting,respectively. The renal cells were treated with palmitate at concentration of 0.04 mmol/L combined with TNF-α (25 μg/L) or IL-6 (20 μg/L) for 24 h. The effect of inflammatory cytokines on the mRNA and protein levels of FAT/CD36 in the renal cells was also investigated. Oil red O staining was used to determine the intracellular lipid droplet formation. The intracellular triglyceride (TG) and free fatty acid (FFA) were measured by enzymic assay and ELISA, respectively. RESULTS: Palmitate loading dose-dependently increased the expression of FAT/CD36 at mRNA and protein levels in both HMCs and HK-2 cells. The inflammatory cytokines further increased the expression of FAT/CD36 at mRNA and protein levels in both cells loaded by palmitate. Oil red O staining, TG detection and FFA assay showed that the inflammatory cytokines increased intracellular lipid levels in both HMCs and HK-2 cells. CONCLUSION: Inflammatory cytokines up-regulate the expression of FAT/CD36 in renal cells loaded by fatty acids and exacerbate the intracellular lipid accumulation.