title: A novel cell-permeable antioxidant peptide, SS31, attenuates ischemic brain injury by down-regulating CD36.
abstract: Oxidative stress is implicated in the pathogenesis of ischemia/reperfusion injury. Recently, we demonstrated that activation of CD36, a class B scavenger receptor, mediates free radical production and tissue injury in cerebral ischemia (1). Oxidized low density lipoproteins (oxLDL) are among the ligands that bind to CD36 and are elevated in acute cerebral infarction. SS31 is a cell-permeable antioxidant peptide that reduces intracellular free radicals and inhibits LDL oxidation/lipid peroxidation (2). The current study was designed to investigate whether treatment with SS31 normalizes ischemia-induced redox changes and attenuates CD36-mediated tissue injury. C57BL/6 mice were subjected to transient middle cerebral artery occlusion (MCAO). Redox status and infarct volume were measured in animals treated with either saline or SS31. Oxidative stress induced by ischemia/reperfusion profoundly depleted glutathione (GSH) concentrations in the ipsilateral cortex and striatum. Treating mice with SS31 immediately after reperfusion significantly attenuated ischemia-induced GSH depletion in the cortex and reduced infarct size. By contrast, the protective effect of SS31 was absent in CD36 knock-out mice, indicating that SS31 is acting through inhibition of CD36. Treating C57BL/6 mice with SS31 reduced CD36 expression in postischemic brain and mouse peritoneal macrophages (MPM). Further in vitro studies revealed that SS31 attenuated oxLDL-induced CD36 expression and foam cell formation in MPM. These in vivo and in vitro studies indicate that the down-regulation of CD36 by novel class antioxidant peptides may be a useful strategy to treat ischemic stroke victims.
authors.affiliation: Burke Medical Research Institute, White Plains, New York 10605; Neurology/Neuroscience and Weill Medical College of Cornell University, New York, New York 10021. Electronic address: suc2002@med.cornell.edu.
authors.forename: Sunghee
authors.initials: S
authors.lastname: Cho
authors.affiliation: Pharmacology, Weill Medical College of Cornell University, New York, New York 10021.
authors.forename: Hazel H
authors.initials: HH
authors.lastname: Szeto
authors.affiliation: Burke Medical Research Institute, White Plains, New York 10605.
authors.forename: Eunhee
authors.initials: E
authors.lastname: Kim
authors.affiliation: Burke Medical Research Institute, White Plains, New York 10605.
authors.forename: Hyunjoo
authors.initials: H
authors.lastname: Kim
authors.affiliation: Burke Medical Research Institute, White Plains, New York 10605.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Tolhurst
authors.affiliation: Burke Medical Research Institute, White Plains, New York 10605.
authors.forename: John T
authors.initials: JT
authors.lastname: Pinto
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001930:Brain Injuries / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D018955:CD36 Antigens / Q000096:biosynthesis*; D015536:Down-Regulation / Q000187:drug effects*; D005487:Foam Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D009841:Oligonucleotides / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D015427:Reperfusion Injury / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology
chemical_list: D000975:Antioxidants; D018955:CD36 Antigens; D008077:Lipoproteins, LDL; D009841:Oligonucleotides; C099252:oxidized low density lipoprotein