CD36 Mediated Reactive Oxygen Species Formation Contributes to Thrombosis.

We previously showed that mice in which the CD36 gene was deleted had significantly prolonged time to form an occlusive thrombus in response to FeCl₃-induced vascular injury than wild type (WT) mice. In other studies we and others have shown that CD36 promotes reactive oxygen species (ROS) formation in murine models of cerebral and cardiac ischemia. In this study, we examined the formation and roles of ROS in FeCl₃-induced carotid artery injury and thrombosis using CD36 null and WT mice. Hydroethidine, a fluorescent superoxide indicator, was injected via the jugular vein and then carotid artery injury was induced in the contralateral artery by direct topical application of FeCl₃ at concentrations of 7.5% or 12.5%. Fluorescence images were monitored with intravital microscopy. FeCl₃ dose dependently induced significant accumulation of ROS in the vessel wall; however, the degree was significantly less in CD36 null mice than in WT mice exposed to the lower dose of FeCl₃. Direct injection of Edavarone (1 mg/Kg body weight), a free radical scavenger, significantly elongated the time to thrombosis in WT mice. Thrombosis time was also increased in the CD36 null mice, but not to the same extent as WT. We also found fewer endothelial cell-derived microparticles (CD105 positive) in plasma of CD36 null mice 3 minutes after injury with the low dose of FeCl₃. Immunoblots of lysates prepared from carotid arteries with thrombi or from untreated normal carotid arteries showed that levels of peroxiredoxin 2 (Prx 2), an antioxidant enzyme known to detoxify ROS, were lower in the thrombi formed from CD36 null mice, but higher in the normal vessel wall, suggesting that an anti-oxidative system may exist in the vessel wall of CD36 null mice. We conclude that CD36 plays a role in ROS formation during thrombosis and may also sensitize the vessel to injury induced by FeCl_3. High Prx 2 expression in the vessel wall in CD36 null mice may contribute to the anti-oxidative effect observed in these mice.