Synthetic glycoprotein mimics inhibit L-selectin-mediated rolling and promote L-selectin shedding

L-selectin is a leukocyte cell-surface protein that facilitates the rolling of leukocytes along the endothelium, a process that leads to leukocyte migration to a site of infection. Preventing L-selectin-mediated rolling minimizes leukocyte adhesion and extravasation; therefore, compounds that inhibit rolling may act as anti-inflammatory agents. To investigate the potential role of multivalent ligands as rolling inhibitors, compounds termed neoglycopolymers were synthesized that possess key structural features of physiological L-selectin ligands. Sulfated neoglycopolymers substituted with sialyl Lewis x derivatives (3',6-disulfo Lewis x or 6-sulfo sialyl Lewis x) or a sulfatide analog (3,6-disulfo galactose) inhibited L-selectin-mediated rolling of lymphoid cells. Functional analysis of the inhibitory ligands indicates that they also induce proteolytic release of L-selectin. Thus, their inhibitory potency may arise from their ability to induce shedding. Our data indicate that screening for compounds that promote L-selectin release can identify ligands that inhibit rolling.