Inhibitory effects of antithrombin III on interactions between blood cells and endothelial cells during retinal ischemia-reperfusion injury.
OBJECTIVE
Infiltrating leukocytes have long been widely thought to be key mediators of ischemia-reperfusion injury. Recently, however, evidence suggests that platelets accumulating in postischemic tissues also contribute to ischemia-reperfusion injury because of their inflammatory properties and promotion of formation of thrombi. This study was designed to evaluate quantitatively the inhibitory effects of antithrombin (AT)-III on the interactions between blood cells and retinal endothelial cells in vivo after transient retinal ischemia.


METHODS
Transient retinal ischemia was induced for 60 minutes in male Long-Evans rats by ligation of the optic nerve. AT III (250 U/kg) was administered intravenously just after induction of ischemia. Leukocyte and platelet behavior in the retina was evaluated in vivo with a scanning laser ophthalmoscope. Expression of P-selectin and intracellular adhesion molecule (ICAM)-1 in the postischemic retina was investigated by reverse transcription-polymerase chain reaction and immunohistochemistry. After 14 days of reperfusion, ischemia-induced retinal damage was evaluated histologically.


RESULTS
Administration of AT III significantly inhibited leukocyte rolling along the major retinal veins and subsequent accumulation of leukocytes in the postischemic retina. Furthermore, the maximum number of rolling and adherent platelets was reduced by 76% (P < 0.01) and 48% (P < 0.01), respectively, at 12 hours after reperfusion. Immunohistochemical studies also revealed the suppressive effect of AT III on expression of P-selectin and ICAM-1. Finally, histologic examination demonstrated the protective effects of AT III against retinal damage after transient retinal ischemia.


CONCLUSIONS
This study demonstrates the inhibitory effects of AT III on leukocyte and platelet recruitment to the postischemic retina, which may account for the neuroprotective properties of this alpha-2 globulin against retinal ischemia-reperfusion injury.
Nishijima
Kazuaki
K
Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.
Kiryu
Junichi
J
Tsujikawa
Akitaka
A
Honjo
Megumi
M
Nonaka
Atsushi
A
Yamashiro
Kenji
K
Kamizuru
Hiroshi
H
Ieki
Yoshiaki
Y
Tanihara
Hidenobu
H
Honda
Yoshihito
Y
Ogura
Yuichiro
Y
D000165:Acridine Orange; D000818:Animals; D000990:Antithrombin III / Q000494:pharmacology*; D001792:Blood Platelets / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005452:Fluoresceins; D007275:Injections, Intravenous; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D007958:Leukocyte Count; D007962:Leukocytes / Q000378:metabolism*; D008297:Male; D019007:P-Selectin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D015427:Reperfusion Injury / Q000378:metabolism* / Q000517:prevention & control; D012169:Retinal Vein / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*
D005452:Fluoresceins; D019007:P-Selectin; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; D018799:Intercellular Adhesion Molecule-1; C024098:6-carboxyfluorescein; D000990:Antithrombin III; D000165:Acridine Orange