Osteopontin (OPN) is expressed in atherosclerotic lesions, particularly in diabetic patients. To determine the role of OPN in atherogenesis, ApoE–/–OPN+/+, ApoE–/–OPN+/–, and ApoE–/–OPN–/– mice were infused with Ang II, inducing vascular OPN expression and accelerating atherosclerosis. Compared with ApoE–/–OPN+/+ mice, ApoE–/–OPN+/– and ApoE–/–OPN–/– mice developed less Ang II–accelerated atherosclerosis. ApoE–/– mice transplanted with bone marrow derived from ApoE–/–OPN–/– mice had less Ang II–induced atherosclerosis compared with animals receiving ApoE–/–OPN+/+ cells. Aortae from Ang II–infused ApoE–/–OPN–/– mice expressed less CD68, C-C-chemokine receptor 2, and VCAM-1. In response to intraperitoneal thioglycollate, recruitment of leukocytes in OPN–/– mice was impaired, and OPN–/– leukocytes exhibited decreased basal and MCP-1–directed migration. Furthermore, macrophage viability in atherosclerotic lesions from Ang II–infused ApoE–/–OPN–/– mice was decreased. Finally, Ang II–induced abdominal aortic aneurysm formation in ApoE–/–OPN–/– mice was reduced and associated with decreased MMP-2 and MMP-9 activity. These data suggest an important role for leukocyte-derived OPN in mediating Ang II–accelerated atherosclerosis and aneurysm formation.
Dennis Bruemmer, Alan R. Collins, Grace Noh, Wei Wang, Mary Territo, Sarah Arias-Magallona, Michael C. Fishbein, Florian Blaschke, Ulrich Kintscher, Kristof Graf, Ronald E. Law, Willa A. Hsueh