[Metformin inhibits THP-1 macrophage-derived foam cell formation induced by lipopolysaccharide]

To investigate the impact of metformin (Met) on THP-1 macrophage-derived foam cell formation induced by lipopolysaccharide (LPS) and observe the changes of lipid droplets (LDs) and LDs-associated proteins.

THP-1 cells were induced to differentiate into macrophages by 100 ng/mL phorbol 12-myristate 13-acetate (PMA) for 48 hours, and then the macrophages were further induced to generate foam cells by 50 μg/mL oxidized low-density lipoprotein (ox-LDL) and 1 μg/mL LPS. During this process, these foam cells were treated with 0, 100, 200 μmol/L Met. Under the fluorescence microscope, the effect of Met on foam cell formation was evaluated by Oil red O staining and the number and morphology of LDs were observed by BODIPY493/503 staining. Intracellular triglyceride (TG) were extracted and measured by TG quantitative kits. The expressions of adipose differentiation-related protein (ADRP) and tail-interacting protein of 47 kDa (TIP47) were detected by Western blotting.

Compared with the untreated group, the LDs in foam cells were reduced significantly and the size became smaller after treated with 100 or 200 μmol/L Met. What's more, the quantitative data showed that the intracellular TG content decreased markedly in a dose-dependent manner, and the TG content decreased about 25% in foam cells treated with 200 μmol/L Met. Western blotting showed that Met reduced the expression of ADRP, but not TIP47 in the THP-1 macrophage-derived foam cells.

Met could inhibit THP-1-derived foam cell formation induced by LPS, reduce intracellular lipid accumulation, and down-regulate the expression of ADRP.