NADPH oxidase plays a central role in blood-brain barrier damage in experimental stroke.
OBJECTIVE
Cerebral ischemia/reperfusion is associated with reactive oxygen species (ROS) generation, and NADPH oxidases are important sources of ROS. We hypothesized that NADPH oxidases mediate blood-brain barrier (BBB) disruption and contribute to tissue damage in ischemia/reperfusion.


METHODS
Ischemia was induced by filament occlusion of the middle cerebral artery in mice for 2 hours followed by reperfusion. BBB permeability was measured by Evans blue extravasation. Monolayer permeability was determined from transendothelial electrical resistance of cultured porcine brain capillary endothelial cells.


RESULTS
BBB permeability was increased in the ischemic hemisphere 1 hour after reperfusion. In NADPH oxidase-knockout (gp91phox(-/-)) mice, middle cerebral artery occlusion-induced BBB disruption and lesion volume were largely attenuated compared with those in wild-type mice. Inhibition of NADPH oxidase by apocynin prevented BBB damage. In porcine brain capillary endothelial cells, hypoxia/reoxygenation induced translocation of the NADPH oxidase activator Rac-1 to the membrane. In vivo inhibition of Rac-1 by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin or Clostridium difficile lethal toxin B also prevented the ischemia/reperfusion-induced BBB disruption. Stimulation of porcine brain capillary endothelial cells with H(2)O(2) increased permeability, an effect attenuated by inhibition of phosphatidyl inositol 3-kinase or c-Jun N-terminal kinase but not blockade of extracellular signal-regulated kinase-1/2 or p38 mitogen-activated protein kinase. Inhibition of Rho kinase completely prevented the ROS-induced increase in permeability and the ROS-induced polymerization of the actin cytoskeleton.


CONCLUSIONS
Activation of Rac and subsequently of the gp91phox containing NADPH oxidase promotes cerebral ROS formation, which then leads to Rho kinase-mediated endothelial cell contraction and disruption of the BBB. Inhibition of NADPH oxidase is a promising approach to reduce brain injury after stroke.
Kahles
Timo
T
Institut für Kardiovaskuläre Physiologie, Fachbereich Medizin der J.W. Goethe Universität, Theodor-Stern-Kai 7, D-60596 Frankfurt am Main, Germany.
Luedike
Peter
P
Endres
Matthias
M
Galla
Hans-Joachim
HJ
Steinmetz
Helmuth
H
Busse
Rudi
R
Neumann-Haefelin
Tobias
T
Brandes
Ralf P
RP
D000818:Animals; D001812:Blood-Brain Barrier / Q000201:enzymology* / Q000503:physiopathology; D001929:Brain Edema / Q000201:enzymology / Q000209:etiology / Q000503:physiopathology; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020244:Infarction, Middle Cerebral Artery / Q000201:enzymology / Q000503:physiopathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D000074624:NADPH Oxidase 1; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000201:enzymology* / Q000503:physiopathology; D020521:Stroke / Q000201:enzymology* / Q000503:physiopathology; D034421:Sus scrofa; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D054460:rho-Associated Kinases; D020830:rac1 GTP-Binding Protein