Scavenger Receptor A and CD36 Are Implicated in Mediating Platelet Activation Induced by Oxidized Low- Density Lipoproteins

Abstract

See ATVB 2007;2476–2483. CD36, previously known as GPIIIb or GPIV, is an 88-kDa membrane glycoprotein that was isolated from blood platelets soon after being identified on monocytes by monoclonal antibody OKM5. Cloning the CD36 gene showed this cell adhesion molecule to be a member of the scavenger receptor class B family. Moreover, it was observed that CD36 has the capacity to bind oxidized low-density lipoproteins (oxLDL) but not acetylated lipoproteins. Scavenger receptor class A (SRA),1 also expressed on platelets and monocytes/macrophages, is a trimer of 77 kDa, that binds to acetylated and oxidized lipoproteins. SRA is closely associated to macrophage CD36 in initiating atherosclerotic lesions, in some studies but not all.2,3,4 Very little was known, up to now, on the role played by oxLDL in activating platelets via CD36 and SRA and promoting a prothrombotic phenotype. The study, in this issue of Arteriosclerosis, Thrombosis, and Vascular Biology , by Suzanne Korporaal and coworkers,5 shows very elegantly that oxLDL, in tandem with CD36 and SRA, is activating platelets and potentially increasing the risk of thrombosis. This investigation brings some exciting data on a novel platelet-activating pathway triggered by partially oxidized (30% to 60%) LDL and mediated by the combined activity of CD36 and …