title: Human immunodeficiency virus impairs reverse cholesterol transport from macrophages.
abstract: Several steps of HIV-1 replication critically depend on cholesterol. HIV infection is associated with profound changes in lipid and lipoprotein metabolism and an increased risk of coronary artery disease. Whereas numerous studies have investigated the role of anti-HIV drugs in lipodystrophy and dyslipidemia, the effects of HIV infection on cellular cholesterol metabolism remain uncharacterized. Here, we demonstrate that HIV-1 impairs ATP-binding cassette transporter A1 (ABCA1)-dependent cholesterol efflux from human macrophages, a condition previously shown to be highly atherogenic. In HIV-1-infected cells, this effect was mediated by Nef. Transfection of murine macrophages with Nef impaired cholesterol efflux from these cells. At least two mechanisms were found to be responsible for this phenomenon: first, HIV infection and transfection with Nef induced post-transcriptional down-regulation of ABCA1; and second, Nef caused redistribution of ABCA1 to the plasma membrane and inhibited internalization of apolipoprotein A-I. Binding of Nef to ABCA1 was required for down-regulation and redistribution of ABCA1. HIV-infected and Nef-transfected macrophages accumulated substantial amounts of lipids, thus resembling foam cells. The contribution of HIV-infected macrophages to the pathogenesis of atherosclerosis was supported by the presence of HIV-positive foam cells in atherosclerotic plaques of HIV-infected patients. Stimulation of cholesterol efflux from macrophages significantly reduced infectivity of the virions produced by these cells, and this effect correlated with a decreased amount of virion-associated cholesterol, suggesting that impairment of cholesterol efflux is essential to ensure proper cholesterol content in nascent HIV particles. These results reveal a previously unrecognized dysregulation of intracellular lipid metabolism in HIV-infected macrophages and identify Nef and ABCA1 as the key players responsible for this effect. Our findings have implications for pathogenesis of both HIV disease and atherosclerosis, because they reveal the role of cholesterol efflux impairment in HIV infectivity and suggest a possible mechanism by which HIV infection of macrophages may contribute to increased risk of atherosclerosis in HIV-infected patients.
authors.affiliation: The George Washington University, Washington, District of Columbia, USA.
authors.forename: Zahedi
authors.initials: Z
authors.lastname: Mujawar
authors.forename: Honor
authors.initials: H
authors.lastname: Rose
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Morrow
authors.forename: Tatiana
authors.initials: T
authors.lastname: Pushkarsky
authors.forename: Larisa
authors.initials: L
authors.lastname: Dubrovsky
authors.forename: Nigora
authors.initials: N
authors.lastname: Mukhamedova
authors.forename: Ying
authors.initials: Y
authors.lastname: Fu
authors.forename: Anthony
authors.initials: A
authors.lastname: Dart
authors.forename: Jan M
authors.initials: JM
authors.lastname: Orenstein
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Bobryshev
authors.forename: Michael
authors.initials: M
authors.lastname: Bukrinsky
authors.forename: Dmitri
authors.initials: D
authors.lastname: Sviridov
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism*; D015536:Down-Regulation; D005487:Foam Cells / Q000378:metabolism; D015693:Gene Products, nef / Q000378:metabolism; D006678:HIV / Q000378:metabolism / Q000472:pathogenicity*; D015658:HIV Infections / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: C577836:ABCA1 protein, human; D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D015693:Gene Products, nef; D054311:nef Gene Products, Human Immunodeficiency Virus; D002784:Cholesterol