Molecular determinants of the prothrombogenic and inflammatory phenotype assumed by the postischemic cerebral microcirculation.
OBJECTIVE
Circulating blood cells have been implicated in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury and stroke. The objective of this study was to define the magnitude and molecular determinants of the platelet- and leukocyte-endothelial cell adhesive interactions induced by I/R in the mouse brain.


METHODS
Bilateral common carotid artery occlusion was induced for 1 hour in C57BL/6 mice, followed by either 40 minutes or 4 hours of reperfusion. Fluorescent platelets were administered intravenously, and the frontal brain surface was observed with intravital fluorescence microscopy. Leukocyte-endothelial cell adhesion was monitored with the use of rhodamine-6G.


RESULTS
Ischemia followed by 40 minutes of reperfusion resulted in the rolling (125.1+/-23.6/mm2) and firm adhesion (109.5+/-25.8/mm2) of leukocytes but not platelets in venules. However, with 4 hours of reperfusion, rolling (138.8+/-24.6/mm2) and firm adhesion (153.7+/-22.3/mm2) of platelets were detected, and this was accompanied by a more intense recruitment of rolling (374.5+/-54.6/mm2) and adherent (445.2+/-57.1/mm2) leukocytes. In mice deficient in either P-selectin (P-selectin-/-) or intercellular adhesion molecule-1 (ICAM-1) (ICAM-1-/-), the I/R-induced platelet-endothelial cell (by 80% and 60%, respectively) and leukocyte-endothelial cell (by 84% and 78%, respectively) interactions were significantly blunted compared with those of wild-type mice.


CONCLUSIONS
These findings indicate that I/R promotes the adhesion of both platelets and leukocytes in cerebral venules, with the accumulation of adherent leukocytes preceding the recruitment of platelets. Both P-selectin and ICAM-1 contribute to the inflammatory and prothrombogenic state induced by cerebral I/R.
Ishikawa
Mami
M
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, 1501 Kings Hwy, Shreveport, LA 71130-3932, USA.
Cooper
Dianne
D
Russell
Janice
J
Salter
James W
JW
Zhang
John H
JH
Nanda
Anil
A
Granger
D Neil
DN
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism / Q000473:pathology; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D002448:Cell Adhesion; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D005456:Fluorescent Dyes; D007249:Inflammation / Q000209:etiology*; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D020767:Intracranial Thrombosis / Q000209:etiology*; D002546:Ischemic Attack, Transient / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D007962:Leukocytes / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008833:Microcirculation / Q000503:physiopathology*; D019007:P-Selectin / Q000235:genetics; D010973:Platelet Adhesiveness; D015424:Reperfusion; D014654:Vascular Patency; D014699:Venules / Q000473:pathology / Q000503:physiopathology
D005456:Fluorescent Dyes; D019007:P-Selectin; D018799:Intercellular Adhesion Molecule-1