2010 Volume 74 Issue 8 Pages 1518-1523
Heparin cofactor II (HCII), a serine protease inhibitor (serpin), inactivates thrombin action in the subendothelial layer of the vascular wall. Because a congenitally HCII-deficient patient has been shown to have multiple atherosclerotic lesions, it is hypothesized that HCII plays a pivotal role in the development of vascular remodeling, including atherosclerosis. To clarify this issue, 3 clinical studies concerning plasma HCII activity and atherosclerosis were carried out, and results demonstrated that a higher incidence of in-stent restenosis after percutaneous coronary intervention, maximum carotid arterial plaque thickness, and prevalence of peripheral arterial disease occurred in subjects with low plasma HCII activity. Furthermore, HCII-deficient mice were generated by a gene targeting method to determine the mechanism of the vascular protective action of HCII. Because HCII-/- mice were embryonically lethal, we used HCII+/- mice and found that they manifested augmentation of intimal hyperplasia and increased thrombosis after cuff or wire injury to the femoral arteries. HCII+/- mice with vascular injury showed augmentation of inflammatory cytokines and chemokines and oxidative stress. These abnormal phenotypes of vascular remodeling observed in HCII+/- mice were almost restored by human HCII protein supplementation. HCII protects against vascular remodeling, including atherosclerosis, in both humans and mice, and plasma HCII activity might be a predictive biomarker and novel therapeutic target for the prevention of cardiovascular diseases. (Circ J 2010; 74: 1518 - 1523)