Impact of monocyte colony-stimulating factor upon β-very low density lipoprotein (β-VLDL) cholesterol metabolism in tetradecanoyl phorbol acetate-derived THP-1 cells

Abstract

The effect of monocyte colony stimulating factor (M-CSF) on the β-very low density lipoprotein (β-VLDL) metabolism in THP-1 cells (human leukemia cell line) was studied. THP-1 cells treated with M-CSF decreased Latex Bead phagocytosis, but the cells incubated with 12-tetradecanoyl-phorbol-13-acetate (TPA) enhanced phagocytosis 2.5-fold. Binding activity of 125I-M-CSF to THP-1 cells was higher than that in THP-1 cells elicited with TPA. THP-1 cells incubated with M-CSF before TPA treatment were designated MT macrophages, and those incubated with M-CSF after TPA treatment were called TM macrophages. When these cells were incubated with β-VLDL, the cholesterol ester content in MT macrophages was less than in TM macrophages. The uptake of [ 3H]cholesterol oleate-β-VLDL in MT macrophages was the same as in TM macrophages. The released radioactivity from [ 3H]cholesterol oleate-β-VLDL loaded MT macrophages was higher than that from TM macrophages. Acid cholesterol esterase activity and ACAT activity were the same in both types of macrophages. Neutral cholesterol esterase activity was higher in MT than in TM macrophages. These results suggested that β-VLDL-induced cholesterol ester deposition in THP-1 cells-derived macrophages was suppressed by M-CSF, when M-CSF acted at the stage of monocytes (THP-1 cells), and that the reduction of cholesterol ester might be due to enhanced release of cholesterol from the cells with high neutral cholesterol esterase activity.