title: Tweaking the cholesterol efflux capacity of reconstituted HDL.
abstract: Mechanisms to increase plasma high-density lipoprotein (HDL) or to promote egress of cholesterol from cholesterol-loaded cells (e.g., foam cells from atherosclerotic lesions) remain an important target to regress heart disease. Reconstituted HDL (rHDL) serves as a valuable vehicle to promote cellular cholesterol efflux in vitro and in vivo. rHDL were prepared with wild type apolipoprotein (apo) A-I and the rare variant, apoA-I Milano (M), and each apolipoprotein was reconstituted with phosphatidylcholine (PC) or sphingomyelin (SM). The four distinct rHDL generated were incubated with CHO cells, J774 macrophages, and BHK cells in cellular cholesterol efflux assays. In each cell type, apoA-I(M) SM-rHDL promoted the greatest cholesterol efflux. In BHK cells, the cholesterol efflux capacities of all four distinct rHDL were greatly enhanced by increased expression of ABCG1. Efflux to PC-containing rHDL was stimulated by transfection of a nonfunctional ABCA1 mutant (W590S), suggesting that binding to ABCA1 represents a competing interaction. This interpretation was confirmed by binding experiments. The data show that cholesterol efflux activity is dependent upon the apoA-I protein employed, as well as the phospholipid constituent of the rHDL. Future studies designed to optimize the efflux capacity of therapeutic rHDL may improve the value of this emerging intervention strategy.
authors.affiliation: Cardiovascular Research Laboratories, Department of Medicine, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC H3A 1A1, Canada.
authors.forename: Cheng-I J
authors.initials: CI
authors.lastname: Ma
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Beckstead
authors.forename: Airlia
authors.initials: A
authors.lastname: Thompson
authors.forename: Anouar
authors.initials: A
authors.lastname: Hafiane
authors.forename: Rui Hao Leo
authors.initials: RH
authors.lastname: Wang
authors.forename: Robert O
authors.initials: RO
authors.lastname: Ryan
authors.forename: Robert S
authors.initials: RS
authors.lastname: Kiss
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016632:Apolipoprotein A-I / Q000235:genetics / Q000378:metabolism; D016466:CHO Cells; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D008075:Lipoproteins, HDL / Q000378:metabolism*; D014162:Transfection
chemical_list: D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D016632:Apolipoprotein A-I; D008075:Lipoproteins, HDL; D002784:Cholesterol