Adhesive Interaction Between P-Selectin and Sialyl Lewis^xPlays an Important Role in Recurrent Coronary Arterial Thrombosis in Dogs

Abstract

Abstract-Cell adhesion molecules may play an important role in the disease process of acute coronary syndromes. We have shown a neutralizing anti-P-selectin monoclonal antibody and a sialyl Lewis x -containing oligosaccharide (SLe x -OS), an analogue of selectin ligand on leukocytes, reduce cyclic flow variations (CFVs) in a canine model of recurrent coronary arterial thrombosis, suggesting the important interaction between P-selectin and SLe x for the pathophysiology of these syndromes. However, the functional role of these adhesion molecules in the thrombotic process remains unclear. Therefore, we investigated effects of SLe x -OS on CFVs, platelet P-selectin expression, and morphology of the stenotic site in the same model. Anesthetized open-chest dogs (nϭ34) were randomly divided into 4 groups after developing CFVs. Dogs intravenously received saline or graded doses of SLe x -OS (5, 20, or 40 mg/kg bolus) infusion followed by a continuous infusion (5 mg ⅐ kg Ϫ1 ⅐ h Ϫ1 ) for 60 minutes. By flow cytometric analysis, P-selectin expression on platelets after CFVs was significantly upregulated during CFVs. Immunohistochemical analysis revealed the incorporation of platelets with upregulated P-selectin within thrombi at the stenotic site. Microscopic observations revealed the presence of numerous platelets adhered to leukocytes at the stenotic site on the damaged endothelium. SLe x -OS significantly reduced CFVs, inhibited the P-selectin expression on platelets, and prevented the adherence of platelets and leukocytes. These findings further support the notion that the adhesive interaction between P-selectin on platelets and SLe x on leukocytes plays an important role in platelet-mediated thrombus formation in this model.

Intraplatelet Tetrahydrobiopterin Plays an Important Role in Regulating Canine Coronary Arterial Thrombosis by Modulating Intraplatelet Nitric Oxide and Superoxide Generation

“…This finding is consistent with the results of our recent study. 18 Taken together, decreased intraplatelet BH 4 during thrombus formation might enhance platelet aggregation and adhesiveness, resulting in augmented thrombus formation.…”

“…18 Intraplatelet BH 4 How to examine intraplatelet BH 4 levels was described previously. 19 In brief, the washed platelet suspension was homogenized with HClO 4 , which immediately deproteinizes platelets, and then sonicated twice for 5 seconds with a tip sonicator and centrifuged at 12 000g for 2 minutes.…”

Absence of P-Selectin, but Not Intercellular Adhesion Molecule-1, Attenuates Neointimal Growth After Arterial Injury in Apolipoprotein E–Deficient Mice

“…22 In a canine model of acute coronary arterial thrombosis, inhibition of P-selectin-dependent adhesive interactions by the tetrasaccharide sialyl Lewis x or analogues has been shown to inhibit platelet aggregation associated with mural thrombi after endothelial injury. 25,26 ICAM-1 binding to its integrin receptors on leukocytes containing the CD18 ␤-chain subunit (Mac-1 or lymphocyte function-associated antigen-1) mediates firm adhesion and Figure 3. A, Quantitative histomorphometry of plaque area in injured carotid arteries 4 weeks after denudation and 5 weeks on Western diet.…”

Role for Sulfatides in Platelet Aggregation

“…P-selectin inhibition accelerated thrombolysis in a primate model of arterial thrombosis, 25 reduced the extent of venous thrombosis in another primate model, 26 and reduced recurrent coronary arterial thrombosis in dogs. 27 Although attributed to the inhibition of platelet-leukocyte interactions, a significant component of the observed beneficial effects of P-selectin blockade may instead be due to the reversal of platelet aggregation.…”