Reactive Oxygen Species Regulate Osteopontin Expression in a Murine Model of Post-Ischemic Neo-vascularization

• Type of Material: Article
• Authors: Alicia N. Lyle, Emory University; Giji Joseph, Emory University; Aaron E. Fan, Emory University; Daiana Weiss, Emory University; Natalia Landazuri, Emory University; W Robert Taylor, Emory University
• Language: English
• Date: 2012-06
• Publisher: American Heart Association
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 American Heart Association, Inc.
• Final Published Version (URL): http://dx.doi.org/10.1161%2FATVBAHA.112.248922
• Title of Journal or Parent Work: Arteriosclerosis, Thrombosis, and Vascular Biology
• ISSN: 1079-5642
• Volume: 32
• Issue: 6
• Start Page: 1383
• End Page: 1391
• Grant/Funding Information: This work was supported by NIH PO1 HL095070, NIH RO1 HL09058, NIH RO1HL062820 and a post-doctoral grant to Alicia N. Lyle from the American Heart Association.
• Keywords: Ischemia; Angiogenesis; Reactive Oxygen Species; Osteopontin; Collateral Circulation
• Research Categories: Engineering, Biomedical

Abstract

Objective Previous findings from our laboratory demonstrated that neo-vascularization was impaired in osteopontin (OPN) knockout animals. However, the mechanisms responsible for regulation of OPN expression in the setting of ischemia remain undefined. Therefore, we sought to determine if OPN is upregulated in response to ischemia and hypothesized that H2O2 is a critical component of the signaling mechanism by which OPN expression is upregulated in response to ischemia in vivo. Methods and Results To determine if ischemic injury upregulates OPN, we used a murine model of hind limb ischemia. Femoral artery ligation in C57Bl/6 mice significantly increased OPN expression and H2O2 production. Infusion of C57Bl/6 mice with PEG-catalase (10,000 U/kg/day) or the use of transgenic mice with smooth muscle cell specific catalase overexpression blunted ischemia-induced OPN, suggesting ischemia-induced OPN expression is H2O2-dependent. Decreased H2O2-mediated OPN blunted reperfusion and collateral formation in vivo. In contrast, the overexpression of OPN using lentivirus restored neovascularization. Conclusions Scavenging H2O2 blocks ischemia-induced OPN expression, providing evidence that ischemia-induced OPN expression is H2O2-dependent. Decreased OPN expression impaired neo-vascularization, whereas overexpression of OPN increased angiogenesis, supporting our hypothesis that OPN is a critical mediator of post-ischemic neo-vascularization and a potential novel therapeutic target for inducing new vessel growth.