Selectin-Targeting Peptide-Glycosaminoglycan Conjugates Modulate Neutrophil-Endothelial Interactions.

INTRODUCTION: The glycocalyx is a layer of glycoproteins, proteoglycans and glycosaminoglycans that coats the luminal surface of most blood vessels. It effectively regulates adhesive interactions between leukocytes in flowing blood and the endothelium, where during inflammation, binding to E- and P-selectins and intercellular adhesion molecule-1 (ICAM-1) promotes cell tethering and arrest under shear flow. METHODS: In this study, we examine the targeting of E-selectin by an engineered peptide moiety bound to a dermatan sulfate backbone. We further investigate this conjugate, denoted as EC-SEAL, by observing its binding to inflamed endothelium, and quantifying its ability to modulate neutrophil-endothelium interactions. RESULTS: Binding data reveal that EC-SEAL recognizes domains on E-selectin, and to a lesser degree on P- and L-selectin, and ICAM-1. Further, EC-SEAL increases neutrophil rolling velocity, and decreases neutrophil arrest and migration on inflamed human microvascular endothelial cells under physiologically relevant flow conditions. CONCLUSIONS: We conclude that simple targeting strategies can mimic glycocalyx function under inflammatory conditions, effectively reducing neutrophil recruitment.

Development of a Glycosaminoglycan Derived, Selectin Targeting Anti-Adhesive Coating to Treat Endothelial Cell Dysfunction.

Endothelial cell (EC) dysfunction is associated with many disease states including deep vein thrombosis (DVT), chronic kidney disease, sepsis and diabetes. Loss of the glycocalyx, a thin glycosaminoglycan (GAG)-rich layer on the EC surface, is a key feature of endothelial dysfunction and increases exposure of EC adhesion molecules such as selectins, which are involved in platelet binding to ECs. Once bound, platelets cause thrombus formation and an increased inflammatory response. We have developed a GAG derived, selectin targeting anti-adhesive coating (termed EC-SEAL) consisting of a dermatan sulfate backbone and multiple selectin-binding peptides designed to bind to inflamed endothelium and prevent platelet binding to create a more quiescent endothelial state. Multiple EC-SEAL variants were evaluated and the lead variant was found to preferentially bind to selectin-expressing ECs and smooth muscle cells (SMCs) and inhibit platelet binding and activation in a dose-dependent manner. In an in vivo model of DVT, treatment with the lead variant resulted in reduced thrombus formation. These results indicate that EC-SEAL has promise as a potential therapeutic in the treatment of endothelial dysfunction.