Platelet CD36 mediates interactions with endothelial cell–derived microparticles and contributes to thrombosis in mice

Abstract

CD36 is a scavenger receptor that binds multiple ligands, including phosphatidyl serine (PS). Although CD36 -mice do not have a bleeding diathesis, we show here that they do have significantly prolonged thrombotic occlusion times in response to FeCl 3 -induced vascular injury. Because cell-derived microparticles (MPs) are generated in response to vascular injury and circulate in patients with prothrombotic diseases, we hypothesized that PS exposed on their surfaces could be an endogenous CD36 ligand that transmits an activating signal to platelets. We found that MPs prepared from human ECs, monocytes, or platelets or isolated from blood of normal subjects bound to platelets. Binding was not observed with platelets from CD36 -donors and was inhibited by an anti-CD36 antibody or by blockade of exposed PS by annexin V or anti-PS IgM. Preincubation of platelets with MPs led to CD36-dependent augmentation of platelet activation in response to low doses of ADP, as assessed by measuring α 2b β 3 activation, P-selectin expression, and aggregation. Immunofluorescence confocal microscopy of murine carotid thrombi from CD36 -mice showed a significant decrement in endothelial antigen accumulation, which suggests that CD36 plays a role in MP recruitment into thrombi. These results provide what we believe to be a novel role for CD36 in thrombosis.

Oxidized Low-Density Lipoprotein-Dependent Platelet-Derived Microvesicles Trigger Procoagulant Effects and Amplify Oxidative Stress

“…We used an inhibitory antibody to block platelet CD36 and annexin V to mask surface PS exposed on PMVs and found the activation function of PMVs to depend on CD36 and PS to some extent. Our results and those of others indicate that PS on the surface of PMVs binds to platelet CD36 and triggers platelet activation signals (11,19).…”

“…Then PMV pellets were washed twice (to avoid contamination of oxLDL) and resuspended in Modified Tyrode buffer and stored at -80°C. Freezing had no adverse effect on microvesicles (11). The protein content was measured by the Bradford Protein Assay Kit (Beyotime, Jiangsu, China).…”

“…Thus, PMVs may be important sources of platelet activation by oxidative stress, which initiates the coagulation process in atherothrombosis. CD36, a class B scavenger receptor, promotes platelet activation (10,11). It is expressed in platelets, monocytes and several other cells and mediates many pathophysiological processes by binding with various oxidized phospholipids, apoptotic cells and certain pathogens.…”

Redistribution and Hemostatic Action of Recombinant Activated Factor VII Associated with Platelets

“…Interestingly, our data demonstrate that the scavenger receptor GPIV, known to be involved in the uptake of molecules or even microvesicles, has a role in the binding of rFVIIa to platelet membrane. 49,50 Overall, our investigations also suggest that, although the binding of rFVIIa to the platelet membrane is contributed through different components of the platelet membrane, there is certainly a metabolic basis in the internalization process. The use of cytochalasin B resulted in a partial inhibition (25%), in accord with the results observed with a combination of wortmannin and tyrphostin-47 (60% inhibition), the most effective strategy tested.…”

Monocyte tissue factor–dependent activation of coagulation in hypercholesterolemic mice and monkeys is inhibited by simvastatin

“…A recent study demonstrated that activation of platelets with a specific oxidized choline glycerophospholipid (oxPC CD36 ) is mediated by CD36 (16). Moreover, hypercholesterolemic mice exhibit a shortened time to occlusion in a carotid artery thrombosis model compared with healthy mice (16)(17)(18)(19). At present, the mechanism underlying the systemic activation of coagulation associated with hypercholesterolemia has not been defined.…”