Effects of inflammatory cytokines on miR-33a-5P, SREBP2, ABCA1 and ABCG1 expression 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 blank control, 40 ng/ml IL-6, 50 ng/ml TNF-α, 25 µg/ml LDL, 25 µg/ml LDL plus 40 ng/ml IL-6, or 25 µg/ml LDL plus 50 ng/ml TNF-α, followed by incubation at 37°C for 24 h. (A) mRNA levels of miR-33a-5P, SREBP2, ABCA1 and ABCG1 in THP-1 macrophages. The mRNA levels were determined using the 2−ΔΔCt method for RT-PCR as described in the Materials and Methods section. U6 or β-actin served as a reference gene. Data are means ± SD from 6 experiments. (B) SREBP2, ABCA1 and ABCG1 protein levels examined by Western blotting assay. (C) Quantification of SREBP2, ABCA1 and ABCG1 protein levels. Histograms represent the densitometric values of SREBP2, ABCA1 and ABCG1 protein bands from four experiments, normalized to β-actin and expressed as a percentage of control. Data are means ± SD. *, P