Liver X Receptor Activation Induces the Uptake of Cholesteryl Esters From High Density Lipoproteins in Primary Human Macrophages

Objective— Liver X receptors (LXRs) are oxysterol-activated nuclear receptors regulating reverse cholesterol transport, in part by modulating cholesterol efflux from macrophages to apoAI and HDL via the ABCA1 and ABCG1/ABCG4 pathways. Moreover, LXR activation increases intracellular cholesterol trafficking via the induction of NPC1 and NPC2 expression. However, implication of LXRs in the selective uptake of cholesteryl esters from lipoproteins in human macrophages has never been reported. Methods and Results— Our results show that (1) selective CE uptake from HDL3 is highly efficient in human monocyte-derived macrophages; (2) surprisingly, HDL3-CE uptake is strongly increased by LXR activation despite antiatherogenic effects of LXRs; (3) HDL3-CE uptake increase is not linked to SR-BI expression modulation but it is dependent of proteoglycan interactions; (4) HDL3-CE uptake increase is associated with increased expression and secretion of apoE and LPL, two proteins interacting with proteoglycans; (5) HDL3-...