Peptides inhibit selectin-mediated cell adhesion in vitro, and neutrophil influx into inflammatory sites in vivo

The selectins are cell adhesion molecules whose carbohydrate-binding domain (C-type lectin) is thought to be involved in leukocyte adhesion to activated vascular endothelium in the inflammatory process. A series of peptides, based on a conserved region (48YYWIGIRK55-NH2) of the lectin domain of E-, L- and P-selectins, were analysed for their ability to block selectin-mediated cell adhesion in vitro, and neutrophil infiltration into sites of inflammation in vivo. The peptides inhibited the adhesion of myeloid cells to recombinant forms of E- and P-selectin. The adhesion of myeloid cells to human endothelial cells, stimulated to express E-selectin, was also inhibited by the peptides. Finally, the peptides blocked the adhesion of lymphocytes, expressing L-selectin, to high endothelial venules in lymph nodes which contain the ligand for L-selectin. A clear structure-activity relationship was established when peptides of different amino acid chain lengths were tested in these assays. Peptides lacking tyrosine residues (e.g. WIGIR-NH2) at their amino terminus were poor inhibitors of selectin-mediated cell adhesion in vitro. The peptides that were found to be inhibitors of cell adhesion in vitro were also found to inhibit (up to 70%) neutrophil infiltration into sites of inflammation in a thioglycollate-induced peritonitis mouse model system. They also significantly reduced (> 50%) the migration of neutrophils into cytokine-treated skin. These results strongly suggest that compounds based on these tyrosine-containing, selectin-derived peptides could be used as anti-inflammatory therapeutic agents.