title: Lipid-free apolipoprotein A-I and discoidal reconstituted high-density lipoproteins differentially inhibit glucose-induced oxidative stress in human macrophages.
abstract: OBJECTIVE
  The goal of this study was to investigate the mechanisms by which apolipoprotein (apo) A-I, in the lipid-free form or as a constituent of discoidal reconstituted high-density lipoproteins ([A-I]rHDL), inhibits high-glucose-induced redox signaling in human monocyte-derived macrophages (HMDM).
  
  
  RESULTS
  HMDM were incubated under normal (5.8 mmol/L) or high-glucose (25 mmol/L) conditions with native high-density lipoproteins (HDL) lipid-free apoA-I from normal subjects and from subjects with type 2 diabetes (T2D) or (A-I)rHDL. Superoxide (O2-) production was measured using dihydroethidium fluorescence. NADPH oxidase activity was assessed using lucigenin-derived chemiluminescence and a cyotochrome c assay. p47phox translocation to the plasma membrane, Nox2, superoxide dismutase 1 (SOD1), and SOD2 mRNA and protein levels were determined by real-time polymerase chain reaction and Western blotting. Native HDL induced a time-dependent inhibition of O2- generation in HMDM incubated with 25 mmol/L glucose. Lipid-free apoA-I and (A-I)rHDL increased SOD1 and SOD2 levels and attenuated 25 mmol/L glucose-mediated increases in cellular O2-, NADPH oxidase activity, p47 translocation, and Nox2 expression. Lipid-free apoA-I mediated its effects on Nox2, SOD1, and SOD2 via ABCA1. (A-I)rHDL-mediated effects were via ABCG1 and scavenger receptor BI. Lipid-free apoA-I from subjects with T2D inhibited reactive oxygen species generation less efficiently than normal apoA-I.
  
  
  CONCLUSIONS
  Native HDL, lipid-free apoA-I and (A-I)rHDL inhibit high-glucose-induced redox signaling in HMDM. The antioxidant properties of apoA-I are attenuated in T2D.
authors.affiliation: Lipid Research Group, The Heart Research Institute, 7 Eliza Street, Sydney, New South Wales 2042, Australia. tabetf@hri.org.au
authors.forename: Fatiha
authors.initials: F
authors.lastname: Tabet
authors.forename: Gilles
authors.initials: G
authors.lastname: Lambert
authors.forename: Luisa F
authors.initials: LF
authors.lastname: Cuesta Torres
authors.forename: Liming
authors.initials: L
authors.lastname: Hou
authors.forename: Irene
authors.initials: I
authors.lastname: Sotirchos
authors.forename: Rhian M
authors.initials: RM
authors.lastname: Touyz
authors.forename: Alicia J
authors.initials: AJ
authors.lastname: Jenkins
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Barter
authors.forename: Kerry-Anne
authors.initials: KA
authors.lastname: Rye
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D016632:Apolipoprotein A-I / Q000378:metabolism*; D015153:Blotting, Western; D016022:Case-Control Studies; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D021381:Protein Transport; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051122:Scavenger Receptors, Class B / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D000099156:Superoxide Dismutase 2
chemical_list: D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D016632:Apolipoprotein A-I; D004791:Enzyme Inhibitors; D005947:Glucose; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008562:Membrane Glycoproteins; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D012333:RNA, Messenger; D051122:Scavenger Receptors, Class B; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D013481:Superoxides; D000099156:Superoxide Dismutase 2; C577836:ABCA1 protein, human; C419353:ABCG1 protein, human; C505693:APOA1 protein, human; C495124:SCARB1 protein, human; C000606290:SOD1 protein, human; C034366:discoidal lipoproteins; C056558:CYBB protein, human; C060505:neutrophil cytosolic factor 1