Platelet adhesion via glycoprotein IIb integrin is critical for atheroprogression and focal cerebral ischemia: an in vivo study in mice lacking glycoprotein IIb.
BACKGROUND
The platelet glycoprotein (GP) IIb/IIIa integrin binds to fibrinogen and thereby mediates platelet aggregation. Here, we addressed the role of GP IIb for platelet adhesion and determined the relevance of platelet GP IIb for the processes of atherosclerosis and cerebral ischemia-reperfusion (I/R) injury.


RESULTS
GP IIb(-/-) mice were generated and bred with ApoE(-/-) animals to create GP IIb(-/-)ApoE(-/-) mice. Platelet adhesion to the mechanically injured or atherosclerotic vessel wall was monitored by in vivo video fluorescence microscopy. In the presence of GP IIb, vascular injury and early atherosclerosis induced platelet adhesion in the carotid artery (CA). In contrast, platelet adhesion was significantly reduced in the absence of GP IIb integrin (P<0.05). To address the contribution of platelet GP IIb to atheroprogression, we determined atherosclerotic lesion formation in the CA and aortic arch (AA) of GP IIb(+/+)ApoE(-/-) or GP IIb(-/-)ApoE(-/-) mice. Interestingly, the absence of GP IIb attenuated lesion formation in CA and AA, indicating that platelets, via GP IIb, contribute substantially to atherosclerosis. Next, we assessed the implication of GP IIb for cerebral I/R injury. We observed that after occlusion of the middle cerebral artery, the cerebral infarct size was drastically reduced in mice lacking GP IIb compared with wild-types.


CONCLUSIONS
These findings show for the first time in vivo that GP IIb not only mediates platelet aggregation but also triggers platelet adhesion to exposed extracellular matrices and dysfunctional endothelial cells. In a process strictly involving GP IIb, platelets, which are among the first blood cells to arrive at the scene of endothelial dysfunction, contribute essentially to atherosclerosis and cerebral I/R injury.
Massberg
Steffen
S
Deutsches Herzzentrum and 1. Medizinische Klinik, Technische Universität München, Lazarettstrasse 36, D-80636 Munich, Germany. massberg@dhm.mhn.de
Schürzinger
Katrin
K
Lorenz
Michael
M
Konrad
Ildiko
I
Schulz
Christian
C
Plesnila
Nikolaus
N
Kennerknecht
Elisabeth
E
Rudelius
Martina
M
Sauer
Susanne
S
Braun
Siegmund
S
Kremmer
Elisabeth
E
Emambokus
Nikla R
NR
Frampton
Jon
J
Gawaz
Meinrad
M
D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism; D002545:Brain Ischemia / Q000097:blood* / Q000235:genetics; D002450:Cell Communication / Q000502:physiology; D002544:Cerebral Infarction / Q000097:blood / Q000235:genetics; D018450:Disease Progression; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D002537:Intracranial Arteriosclerosis / Q000097:blood* / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D010973:Platelet Adhesiveness / Q000502:physiology*; D010974:Platelet Aggregation / Q000502:physiology; D040201:Platelet Membrane Glycoprotein IIb / Q000235:genetics* / Q000378:metabolism*; D020521:Stroke / Q000097:blood / Q000235:genetics
D001057:Apolipoproteins E; D040201:Platelet Membrane Glycoprotein IIb