title: Platelet-erythrocyte interactions enhance alpha(IIb)beta(3) integrin receptor activation and P-selectin expression during platelet recruitment: down-regulation by aspirin ex vivo.
abstract: Activated platelets release biologically active compounds, which then recruit additional platelets into an evolving thrombus. We studied activation of alpha(IIb)beta(3) and exposure of P-selectin on platelets recruited by releasates obtained from collagen-treated platelets and evaluated modifications in prothrombotic effects of releasates induced by platelet-erythrocyte interactions and aspirin treatment. Releasates from collagen-stimulated platelets induced alpha(IIb)beta(3) activation and P-selectin exposure (monitored by flow cytometry using fluorescein isothiocyanate-PAC-1 and phycoerythrin-CD62 antibodies). These responses were markedly amplified by releasates from combined platelet-erythrocyte suspensions. This finding demonstrates a novel mechanism(s) by which erythrocytes intensify platelet aggregability and mediate increased platelet recruitment. Because P-selectin and alpha(IIb)beta(3) are potential sites for platelet-leukocyte interactions, erythrocytes may also modulate leukocyte recruitment. Following aspirin ingestion both the recruiting capacity of platelet releasates and erythrocyte-induced amplification of platelet recruitment were down-regulated. These events represent an additional antithrombotic property of aspirin. We also examined the possibility that arachidonic acid, or eicosanoids derived therefrom, can induce a prothrombotic activity of erythrocytes. The TXA(2)-analog U46 619 and free arachidonate, but not PGI(2) or 12-HETE, induced increases in cytosolic Ca(++) and promoted phosphatidylserine (PS) exposure on a subpopulation of erythrocytes. PS exposure and increases in erythrocyte [Ca(++)](i) are associated with enhanced procoagulant activity, increased endothelial adhesion, and reduced erythrocyte deformability. Our findings, therefore, suggest that TXA(2) and arachidonic acid, derived from activated platelets, induce a prothrombotic phenotype on erythrocytes in proximity. We conclude that by these mechanisms, erythrocytes can actively contribute to platelet-driven thrombogenesis and microvascular occlusion.
authors: Research Center and Department of Clinical Pathology, University Hospital La Fe, Valencia, Spain.
authors: Juana
authors: J
authors: Vallés
authors: M Teresa
authors: MT
authors: Santos
authors: Justo
authors: J
authors: Aznar
authors: Marcial
authors: M
authors: Martínez
authors: Antonio
authors: A
authors: Moscardó
authors: Marta
authors: M
authors: Piñón
authors: M Johan
authors: MJ
authors: Broekman
authors: Aaron J
authors: AJ
authors: Marcus
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000097:blood; D003600:Cytosol / Q000378:metabolism; D004912:Erythrocytes / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D015759:Ionomycin / Q000494:pharmacology; D019007:P-Selectin / Q000235:genetics*; D015539:Platelet Activation / Q000187:drug effects; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D014662:Vasoconstrictor Agents; D016718:Arachidonic Acid; D015759:Ionomycin; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001241:Aspirin; D002118:Calcium