EFFECT OF VITAMIN D ON LIPID METABOLISM BY MODULATING MACROPHAGE POLARIZATION IN HEPATOCYTES
Objective To investigate the effect of vitamin D(VD)on lipid metabolism by modulating fatty-acid induced macrophage M1-M2 polarization in hepatocytes.Methods Saturated fatty acid treated RAW264.7 macrophages were cultured in DMEM with 1,25(OH)2D3,and the conditioned medium(CM)were prepared.Then,AML12 hepatocytes were cultured in CM for 24 h.The M1/M2 polarization phenotype markers of macrophages were detected by RT-PCR.The mRNA and protein expressions of VDR and PPARγ of macrophages were detected by real-time PCR and Western blot,respectively.Lipid deposition in hepatocytes was examined by oil red O staining.The mRNA and protein expressions of lipometabolic enzymes of hepatocytes were detected by RT-PCR and Western blot,respectively.Results Compared to palmitic acid(PA)treated VD control group,the mRNA expressions of M1 phenotype markers,including iNOS2,TNFα and IL-6,and M2 phenotype marker IL-10,as well as the mRNA and protein expressions of VDR and PPARγ of macrophages in PA plus VD treated group were significantly decreased.Hepatocyte steatosis was obviously alleviated in the CM-PA plus VD treated group compared to the CM-PA plus VD control group.The mRNA and protein expressions of SREBP1C and FASN,as well as CPT1A of hepatocytes were significantly decreased in CM-PA plus VD treated group compared to the CM-PA plus VD control group.Conclusion VD supplementation improves lipid metabolism by reversing fatty-acid induced macrophage polarization through VDR/PPARγ pathway in hepatocytes.[ACTA NUTRIMENTA SINICA,2024,46(2):139-145]
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