Aspirin inhibits surface glycoprotein IIb/IIIa, P-selectin, CD63, and CD107a receptor expression on human platelets

Abstract

Platelet inhibition after aspirin therapy reduces the risk for the development of acute coronary syndromes. However, the mechanism by which aspirin affect platelets other than by prostaglandin blockade is unclear. We sought to determine the in vitro effects of aspirin on the surface expression of nine platelet receptors using whole blood flow cytometry. Blood from 24 healthy volunteers was incubated for 30 min with 1.8 and 7.2 mg/l phosphate-buffered saline-diluted acetylsalicylic acid in the presence or absence of apyrase. Platelet serotonin release, and the surface expression of platelet receptors with or without apyrase were determined using the following monoclonal antibodies: anit-CD41 [glycoprotein (GP)IIb/IIIa], CD42b (GPIb), CD62p (P-selectin), CD51/CD61 (vitronectin receptor), CD31 [platelet/endothelial cellular adhesion molecule-1 (PECAM-1)], CD107a [lysosomal associated membrane protein (LAMP)-1], CD107b (LAMP-2), CD63 (LIMP or LAMP-3), and CD151 (PETA-3). Samples were then immediately fixed with 2% paraformaldehyde, and run on the flow cytometer within 48 h. Aspirin does not affect serotonin release from human platelets. Dose-dependent inhibition of GPIIb/IIIa, P-selectin, CD63, and CD107a receptor expression was observed in the aspirin-treated whole-blood samples. Apyrase potentiates the effects of aspirin, and independently inhibits PECAM-1. In addition to the known effect of irreversibly inhibiting platelet cyclooxygenase-1, thereby blocking thromboxane A(2) synthesis, it appears that aspirin exhibits direct effects on selective major platelet receptors.

Thrombin-induced lysosomal exocytosis in human platelets is dependent on secondary activation by ADP and regulated by endothelial-derived substances

“…This is in accordance with experiments performed by Vorland and Holmsen who found no effect on lysosomal secretion when using the specific TXA2 inhibitor SQ 29.548 in thrombin-stimulated platelets [27] and Chronos et al who compared the exposure of CD63 and P-selectin in healthy subjects before and after ingestion of ASA [31]. McKenzie et al reported that the spontaneous expression of LAMP-1, LIMP and P-selectin was reduced in platelets treated with ASA in vitro [32]. In contrast, we did not observe any effect of ASA on spontaneous lysosomal or α-granule exocytosis.…”

Elevated procoagulant microparticles expressing endothelial and platelet markers in essential thrombocythemia

“…This could be because most ET patients were on anti-thrombotic drugs at the time of blood sampling, which may have affected markers of platelet activation; aspirin inhibits the expression of CD62P and CD63 on platelets. 29 Remarkably, half of the ET patients showed a large increase in CD62E-positive microparticles. These CD62E-positive microparticles were not normal endothelial microparticles since they co-expressed CD41, a platelet marker, a finding that we did not observe in other conditions characterized by endothelial perturbation, including diabetes mellitus 20 and renal failure (data not shown).…”

Expression of EMMPRIN (CD147) on circulating platelets in vivo

“…The lack of difference in expression between CAD patients and controls in our study is likely to be due to relatively low levels of activation in all patient groups, and may be explained by the use of agents such as aspirin (approximately 80% of subjects were receiving an antiplatelet agent), and very effective suppression of ex vivo activation using whole blood flow cytometry and CTAD anticoagulant. Clopidogrel and aspirin have been shown to affect the expression of both CD62P and PAC-1 [25][26][27][28].…”