Pamela J. Beck

Inhibition of L-selectin-mediated Leukocyte Rolling by Synthetic Glycoprotein Mimics*

Synthetic carbohydrate and glycoprotein mimics displaying sulfated saccharide residues have been assayed for their L-selectin inhibitory properties under static and flow conditions. Polymers displaying the L-selectin recognition epitopes 3′,6-disulfo Lewis x(Glc) (3-O-SO3-Galβ1α4(Fucα1α3)-6-O-SO3-Glcβ-OR) and 3′,6′-disulfo Lewis x(Glc) (3,6-di-O-SO3-Galβ1α4(Fucα1α3)Glcβ-OR) both inhibit L-selectin binding to heparin under static, cell-free binding conditions with similar efficacies. Under conditions of shear flow, however, only the polymer displaying 3′,6-disulfo Lewis x(Glc) inhibits the rolling of L-selectin-transfected cells on the glycoprotein ligand GlyCAM-1. Although it has been shown to more effective than sialyl Lewis x at blocking the L-selectin–GlyCAM-1 interaction in static binding studies, the corresponding monomer had no effect in the dynamic assay. These data indicate that multivalent ligands are far more effective inhibitors of L-selectin-mediated rolling than their monovalent counterparts and that the inhibitory activities are dependent on the specific sulfation pattern of the recognition epitope. Importantly, our results indicate the L-selectin specificity for one ligand over another found in static, cell-free binding assays is not necessarily retained under the conditions of shear flow. The results suggest that monovalent or polyvalent carbohydrate or glycoprotein mimetics that inhibit selectin binding in static assays may not block the more physiologically relevant process of selectin-mediated rolling.

Neoglycopolymer inhibitors of the selectins

Abstract The selectin class of proteins plays an important role in the inflammatory response. These proteins, which bind saccharide ligands, facilitate the recruitment of leukocytes to the inflamed endothelium. The ring-opening metathesis polymerization (ROMP) has been used to generate synthetic multidentate ligands, which display multiple copies of sulfated saccharide residues. By altering the structure of the appended saccharide residues, multivalent ligands that selectively target one member of the selectin family, P-selectin, were created. The biological activities of materials prepared from the same monomer unit varied, depending on the method of polymer preparation. This result suggests that polymers containing more repeat elements exhibit higher selectin inhibitory activities.