title: Impairment of Macrophage Cholesterol Efflux by Cholesterol Hydroperoxide Trafficking: Implications for Atherogenesis Under Oxidative Stress.
abstract: OBJECTIVE
  Oxidative stress associated with cardiovascular disease can produce various oxidized lipids, including cholesterol oxides, such as 7-hydroperoxide (7-OOH), 7-hydroxide (7-OH), and 7-ketone (7=O). Unlike 7=O and 7-OH, 7-OOH is redox active, giving rise to the others via potentially toxic-free radical reactions. We tested the novel hypothesis that under oxidative stress conditions, steroidogenic acute regulatory (StAR) family proteins not only deliver cholesterol to/into mitochondria of vascular macrophages, but also 7-OOH, which induces peroxidative damage that impairs early stage reverse cholesterol transport.
  
  
  RESULTS
  Stimulation of human monocyte-derived THP-1 macrophages with dibutyryl-cAMP resulted in substantial upregulation of StarD1 and ATP-binding cassette (ABC) transporter, ABCA1. Small interfering RNA-induced StarD1 knockdown before stimulation had no effect on StarD4, but reduced ABCA1 upregulation, linking the latter to StarD1 functionality. Mitochondria in stimulated StarD1-knockdown cells internalized 7-OOH slower than nonstimulated controls and underwent less 7-OOH-induced lipid peroxidation and membrane depolarization, as probed with C11-BODIPY (4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-inda-cene-3-undecanoic acid) and JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolylcarbocyanine iodide), respectively. Major functional consequences of 7-OOH exposure were (1) loss of mitochondrial CYP27A1 activity, (2) reduced 27-hydroxycholesterol (27-OH) output, and (3) downregulation of cholesterol-exporting ABCA1 and ABCG1. Consistently, 7-OOH-challenged macrophages exported less cholesterol to apoA-I or high-density lipoprotein than did nonchallenged controls. StarD1-mediated 7-OOH transport was also found to be highly cytotoxic, whereas 7=O and 7-OH were minimally toxic.
  
  
  CONCLUSIONS
  This study describes a previously unrecognized mechanism by which macrophage cholesterol efflux can be incapacitated under oxidative stress-linked disorders, such as chronic obesity and hypertension. Our findings provide new insights into the role of macrophage redox damage/dysfunction in atherogenesis.
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.). agirotti@mcw.edu witekkor@mcw.edu.
authors: Witold
authors: W
authors: Korytowski
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.).
authors: Katarzyna
authors: K
authors: Wawak
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.).
authors: Pawel
authors: P
authors: Pabisz
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.).
authors: Jared C
authors: JC
authors: Schmitt
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.).
authors: Alexandra C
authors: AC
authors: Chadwick
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.).
authors: Daisy
authors: D
authors: Sahoo
authors: From the Department of Biochemistry (A.W.G., W.K., D.S., A.C.C., J.C.S.) and Department of Medicine (D.S.), Medical College of Wisconsin, Milwaukee; and Department of Biophysics, Jagiellonian University, Krakow, Poland (W.K., K.W., P.P.). agirotti@mcw.edu witekkor@mcw.edu.
authors: Albert W
authors: AW
authors: Girotti
mesh_terms: D050197:Atherosclerosis / Q000378:metabolism*; D001692:Biological Transport; D002478:Cells, Cultured; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000378:metabolism; D003563:Cyclic CMP / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D015227:Lipid Peroxidation / Q000502:physiology*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D021381:Protein Transport; D012680:Sensitivity and Specificity
chemical_list: D003563:Cyclic CMP; C053441:dibutyryl cyclic-3',5'-cytidine monophosphate; C002843:cholesterol hydroperoxide; D002784:Cholesterol
keywords: StAR protein; atherosclerosis; cholesterol; cholesterol hydroperoxide; oxidative stress