title: Human atheromatous plaques stimulate thrombus formation by activating platelet glycoprotein VI.
abstract: Lipid-rich atherosclerotic plaques are vulnerable, and their rupture can cause the formation of a platelet- and fibrin-rich thrombus leading to myocardial infarction and ischemic stroke. Although the role of plaque-based tissue factor as stimulator of blood coagulation has been recognized, it is not known whether plaques can cause thrombus formation through direct activation of platelets. We isolated lipid-rich atheromatous plaques from 60 patients with carotid stenosis and identified morphologically diverse collagen type I- and type III-positive structures in the plaques that directly stimulated adhesion, dense granule secretion, and aggregation of platelets in buffer, plasma, and blood. This material also elicited platelet-monocyte aggregation and platelet-dependent blood coagulation. Plaques exposed to flowing blood at arterial wall shear rate induced platelets to adhere to and spread on the collagenous structures, triggering subsequent thrombus formation. Plaque-induced platelet thrombus formation was observed in fully anticoagulated blood (i.e., in the absence of tissue factor-mediated coagulation). Mice platelets lacking glycoprotein VI (GPVI) were unable to adhere to atheromatous plaque or form thrombi. Human platelet thrombus formation onto plaques in flowing blood was completely blocked by GPVI inhibition with the antibody 10B12 but not affected by integrin alpha2beta1 inhibition with 6F1 mAb. Moreover, the initial platelet response, shape change, induced by plaque was blocked by GPVI inhibition but not with alpha2beta1 antagonists (6F1 mAb or GFOGER-GPP peptide). Pretreatment of plaques with collagenase or anti-collagen type I and anti-collagen type III antibodies abolished plaque-induced platelet activation. Our results indicate that morphologically diverse collagen type I- and collagen type III-containing structures in lipid-rich atherosclerotic plaques stimulate thrombus formation by activating platelet GPVI. This platelet collagen receptor, essential for plaque-induced thrombus formation, presents a promising new anti-thrombotic target for the prevention of ischemic cardiovascular diseases.
authors.affiliation: Institute for Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Penz
authors.forename: Armin J
authors.initials: AJ
authors.lastname: Reininger
authors.forename: Richard
authors.initials: R
authors.lastname: Brandl
authors.forename: Pankaj
authors.initials: P
authors.lastname: Goyal
authors.forename: Tamer
authors.initials: T
authors.lastname: Rabie
authors.forename: Isabell
authors.initials: I
authors.lastname: Bernlochner
authors.forename: Enno
authors.initials: E
authors.lastname: Rother
authors.forename: Christine
authors.initials: C
authors.lastname: Goetz
authors.forename: Bernd
authors.initials: B
authors.lastname: Engelmann
authors.forename: Peter A
authors.initials: PA
authors.lastname: Smethurst
authors.forename: Willem H
authors.initials: WH
authors.lastname: Ouwehand
authors.forename: Richard
authors.initials: R
authors.lastname: Farndale
authors.forename: Bernhard
authors.initials: B
authors.lastname: Nieswandt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Siess
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000150:complications* / Q000473:pathology; D001777:Blood Coagulation; D001792:Blood Platelets / Q000502:physiology; D016893:Carotid Stenosis / Q000097:blood; D024042:Collagen Type I / Q000032:analysis; D024061:Collagen Type III / Q000032:analysis; D006801:Humans; D038982:Integrin alpha2beta1 / Q000502:physiology; D008055:Lipids / Q000032:analysis; D051379:Mice; D008856:Microscopy, Fluorescence; D009000:Monocytes / Q000502:physiology; D015539:Platelet Activation; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D013927:Thrombosis / Q000209:etiology*
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D038982:Integrin alpha2beta1; D008055:Lipids; D010980:Platelet Membrane Glycoproteins; C098341:platelet membrane glycoprotein VI