Di-n-butyl phthalate promotes lipid accumulation via the miR200c-5p-ABCA1 pathway in THP-1 macrophages

Di-n-butyl phthalate (DBP) is ubiquitously in the environment and has been detected in almost all of human bodies. Few data could be found about the effects of DBP on cardiovascular system, though its reproductive toxicities have been studied extensively. This study aimed to explore the effects of DBP on lipid metabolism, a key step during the formation of atherosclerosis, since DBP was recently reported to be associated with atherosclerosis. THP-1 macrophages were employed and exposed to various levels of DBP (10−8, 10−7, 10−6, 10−5 and 10−4 mol/L) or DMSO as control. Lipid accumulation was determined by detection of cellular total cholesterol, free cholesterol, cholesterol ester and content of lipid drops. Expressions of mRNA/miRNAs and proteins were measured by qRT-PCR and western blotting, respectively. Bioinformatic analysis and dual luciferase reporter assay were used to analyze the combination between miR200c-5p and ATP-binding cassette transporter A1 (ABCA1). Cholesterol efflux assay was executed to study the inhibitory effects of DBP on cholesterol efflux capability. Results revealed that DBP at 10−7 mol/L prompted THP-1 macrophages lipid accumulation by inhibiting cholesterol efflux via suppressing ABCA1 expression. In addition, a non-linear inverted U-shaped relationship between DBP and lipid accumulation could be observed. Moreover, miR200c-5p could directly targets to ABCA1 3′UTR and modulate ABCA1 expression. Besides, downregulation of ABCA1 expression and reduction of lipid efflux induced by DBP were due to the miR200c-5p upregulation. Collectively, these data suggested that DBP at levels relative to human exposure could increase lipid accumulation in THP-1 macrophages by decreasing cholesterol efflux through miR200c-5p-ABCA1, then potentiate the formation of atherosclerosis.