Cerebral microvascular responses to hypercholesterolemia: roles of NADPH oxidase and P-selectin.
Although hypercholesterolemia is widely accepted as a major risk factor for coronary artery and peripheral vascular diseases, its role in the pathogenesis of stroke is controversial. The objectives of this study were to determine how hypercholesterolemia affects the cerebral microcirculation under resting conditions and after ischemia-reperfusion (I/R). Platelet- and leukocyte-endothelial cell interactions and oxidant production (using the oxidant-sensitive fluorochrome dihydrorhodamine-123) were monitored by intravital videomicroscopy in the cerebral microvasculature of mice placed on either a normal (ND) or cholesterol-enriched diet (HCD). Platelets labeled with carboxyfluorescein diacetate succinimidyl ester (CFDASE) and leukocytes labeled with rhodamine 6G were seen to roll and firmly adhere, with a corresponding increase in oxidant production, in venules of mice on HCD, but not ND. Immunoneutralization of P-selectin attenuated the platelet- and leukocyte-endothelial cell interactions and the enhanced oxidant production associated with HCD. A GPIIb/IIIa blocking antibody did not alter the blood cell-vessel wall interactions to HCD. Mice deficient in the NADPH oxidase subunit gp91(phox) exhibited significantly blunted platelet and leukocyte recruitment responses to HCD. Focal I/R also elicited inflammatory and prothrombogenic responses in cerebral venules and these were exaggerated in mice on HCD. These results implicate an oxidant-dependent, P-selectin-mediated mechanism in the blood cell-vessel wall interactions induced by hypercholesterolemia in the brain and demonstrate that the deleterious effects of I/R on the brain are exacerbated by this cardiovascular risk factor.
Ishikawa
Mami
M
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, La 71130-3932, USA.
Stokes
Karen Y
KY
Zhang
John H
JH
Nanda
Anil
A
Granger
D Neil
DN
D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002545:Brain Ischemia / Q000378:metabolism*; D002448:Cell Adhesion; D002560:Cerebrovascular Circulation; D002634:Chemotaxis, Leukocyte / Q000502:physiology; D002791:Cholesterol, Dietary / Q000633:toxicity; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005456:Fluorescent Dyes / Q000032:analysis; D006937:Hypercholesterolemia / Q000378:metabolism*; D007962:Leukocytes / Q000502:physiology*; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation; D008856:Microscopy, Fluorescence; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D019007:P-Selectin / Q000235:genetics / Q000502:physiology*; D010973:Platelet Adhesiveness; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000502:physiology; D015427:Reperfusion Injury / Q000378:metabolism*; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology; D019851:Thrombophilia / Q000209:etiology / Q000378:metabolism; D014657:Vasculitis / Q000209:etiology / Q000378:metabolism; D014699:Venules / Q000473:pathology
D002791:Cholesterol, Dietary; D005456:Fluorescent Dyes; D008562:Membrane Glycoproteins; D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases