Effects of inflammatory cytokines on intracellular lipids accumulation and intracellular cholesterol efflux in THP-1 macrophages.

THP-1 macrophages were incubated in serum-free medium at 37°C for 24 h. The medium was then replaced by fresh serum-free medium containing (I) blank control, (II) 40 ng/ml IL-6, (III) 50 ng/ml TNF-α, (IV) 25 µg/ml LDL, (V) 25 µg/ml LDL plus 40 ng/ml IL-6, or (VI) 25 µg/ml LDL plus 50 ng/ml TNF-α, followed by incubation at 37°C for 24 h. (A) The cells stained with oil red O for the examination of lipid inclusions. The results are representative of those observed in six separate experiments (×400). (B) Semi-quantitative analysis of oil red O positive staining was performed by the Image-J software. Data are means ± SD from 6 separate fields. (C) Intracellular total cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE). Values are means ± SD of duplicate wells from 6 experiments. (D) Intracellular apoA-I-mediated cholesterol efflux. Data are means ± SD of duplicate wells from 6 experiments. *, P