Retinal ischemia-reperfusion injury attenuated by blocking of adhesion molecules of vascular endothelium

To evaluate quantitatively the effects of blocking of adhesion molecules (P-selectin or intercellular adhesion molecule-1 [ICAM-1]) on leukocyte dynamics in the retinal microcirculation in vivo during ischemia-reperfusion injury and the therapeutic efficacy of the blocking of adhesion molecules on retinal ischemia-reperfusion injury.

Retinal ischemia was induced for 60 minutes in anesthetized pigmented rats by temporary ligation of the optic nerve. P-selectin or ICAM-1 monoclonal antibody (mAb) was administered at 5 minutes before reperfusion. At 4, 12, and 24 hours after onset of reperfusion, leukocyte behavior in the retinal microcirculation was evaluated in vivo with acridine orange digital fluorography. After 7 or 14 days of reperfusion, retinal damage was evaluated histologically.

P-selectin mAb significantly inhibited leukocyte rolling along the major retinal veins after reperfusion. Subsequently, the number of accumulated leukocytes decreased in the P-selectin-inhibited rats. ICAM-1 mAb also inhibited leukocyte accumulation during the reperfusion period in a more substantial manner than P-selectin mAb. Histologic examination demonstrated the protective effect of the blocking of P-selectin or ICAM-1. In accordance with a reduction in leukocyte accumulation, the protective effect of mAb on retinal ischemia-reperfusion injury was more substantial in ICAM-1-inhibited rats.

The present study demonstrates the inhibitory effect of P-selectin and ICAM-1 mAb on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.