PECAM-1/IgG attenuates peroxynitrite-mediated extremity reperfusion injury

Objective: Neutrophil transendothelial migration, a key feature of skeletal muscle ischemia and reperfusion (I/R) injury, is mediated by the platelet endothelial cell adhesion molecule-1 (PECAM-1). Peroxynitrite anion, a toxi c product of neutrophil superoxide anion and nitric oxide, contributes to o xidative skeletal muscle injury and can be quantified by measurement of pro tein tyrosine nitration after I/R. This study hypothesizes that administrat ion of the PECAM-1/IgG antibody chimera will inhibit peroxynitrite-mediated injury after I/R. Methods: The study was composed of five groups: an I/R group (n = 4), a sha m treatment group anesthetic control (n = 3), a treatment group receiving t he PECAM-1/immunoglobulin G (IgG) antibody chimera with I/R (n = 9), a trea tment group receiving human IgG with I/R as an antibody control (n = 6), an d a treatment group receiving normal saline solution with I/R as a vehicle control (n = 5). The right hind limb in mate New Zealand white rabbits was rendered ischemic by occluding the iliac and femoral arteries for 3 hours, followed by 2 hours of reperfusion (I/R). Sham-treated rabbits underwent ar terial dissection without arterial occlusion. PECAM-1/IgG-treated rabbits a nd IgG-treated rabbits received an infusion of 1 mg/kg in normal saline sol ution 20 mL via an ear vein catheter during the last 5 minutes of ischemia and the first 15 minutes of reperfusion. Saline solution-treated rabbits si milarly received normal saline solution 20 mL. The anterior tibialis muscle was harvested after reperfusion. Immunohistochemical staining for nitrotyr osine was performed with monoclonal antinitrotyrosine antibodies and fluore scently labeled secondary antibodies. Computed morphometric study was perfo rmed to calculate relative fluorescence scores for each histologic section. Averaged fluorescence scores were analyzed by one-way analysis of variance with Bonferroni post hoc comparison. Results: The averaged fluorescence scores (mean +/- SEM) for the sham-treat ed (2.88 +/- 0.78) and PECAM-1/IgG-treated (6.16 +/- 0.43) groups demonstra ted a significant reduction in quantitative fluorescence compared with the IgG- (15.17 +/- 2.01) and saline solution-treated (17.46 +/- 3.71) control groups, and the I/R-treated (18.52 +/- 3.00) group, (P < .05). Conclusions: These results suggest that PECAM-1/IgG diminishes peroxynitrit e-mediated oxidative skeletal muscle injury by inhibiting neutrophil transe ndothelial migration and may therefore prove a useful therapeutic agent in the treatment of reperfusion injury.