title: Oxidized LDL activates blood platelets through CD36/NOX2-mediated inhibition of the cGMP/protein kinase G signaling cascade.
abstract: Oxidized low-density lipoprotein (oxLDL) promotes unregulated platelet activation in dyslipidemic disorders. Although oxLDL stimulates activatory signaling, it is unclear how these events drive accelerated thrombosis. Here, we describe a mechanism for oxLDL-mediated platelet hyperactivity that requires generation of reactive oxygen species (ROS). Under arterial flow, oxLDL triggered sustained generation of platelet intracellular ROS, which was blocked by CD36 inhibitors, mimicked by CD36-specific oxidized phospholipids, and ablated in CD36(-/-) murine platelets. oxLDL-induced ROS generation was blocked by the reduced NAD phosphate oxidase 2 (NOX2) inhibitor, gp91ds-tat, and absent in NOX2(-/-) mice. The synthesis of ROS by oxLDL/CD36 required Src-family kinases and protein kinase C (PKC)-dependent phosphorylation and activation of NOX2. In functional assays, oxLDL abolished guanosine 3',5'-cyclic monophosphate (cGMP)-mediated signaling and inhibited platelet aggregation and arrest under flow. This was prevented by either pharmacologic inhibition of NOX2 in human platelets or genetic ablation of NOX2 in murine platelets. Platelets from hyperlipidemic mice were also found to have a diminished sensitivity to cGMP when tested ex vivo, a phenotype that was corrected by infusion of gp91ds-tat into the mice. This study demonstrates that oxLDL and hyperlipidemia stimulate the generation of NOX2-derived ROS through a CD36-PKC pathway and may promote platelet hyperactivity through modulation of cGMP signaling.
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Simbarashe
authors.initials: S
authors.lastname: Magwenzi
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Casey
authors.initials: C
authors.lastname: Woodward
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Katie S
authors.initials: KS
authors.lastname: Wraith
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Ahmed
authors.initials: A
authors.lastname: Aburima
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Zaher
authors.initials: Z
authors.lastname: Raslan
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Huw
authors.initials: H
authors.lastname: Jones
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Catriona
authors.initials: C
authors.lastname: McNeil
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, LIGHT Laboratories, University of Leeds, Leeds, United Kingdom; and.
authors.forename: Stephen
authors.initials: S
authors.lastname: Wheatcroft
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, LIGHT Laboratories, University of Leeds, Leeds, United Kingdom; and.
authors.forename: Nadira
authors.initials: N
authors.lastname: Yuldasheva
authors.affiliation: School of Dentistry, University of Alberta, Edmonton, AB, Canada.
authors.forename: Maria
authors.initials: M
authors.lastname: Febbriao
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, LIGHT Laboratories, University of Leeds, Leeds, United Kingdom; and.
authors.forename: Mark
authors.initials: M
authors.lastname: Kearney
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull-York Medical School, Thrombosis Research Laboratory (013/014), University of Hull, Hull, United Kingdom;
authors.forename: Khalid M
authors.initials: KM
authors.lastname: Naseem
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D018955:CD36 Antigens / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D006801:Humans; D006949:Hyperlipidemias / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D010766:Phosphorylation; D015539:Platelet Activation; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018955:CD36 Antigens; D008077:Lipoproteins, LDL; D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; C099252:oxidized low density lipoprotein; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP