In vivo ligand specificity of E-selectin binding to multivalent sialyl Lewisx N-linked oligosaccharides

The in vivo specificity for E-selectin binding to a panel of N-linked oligosaccharides containing a clustered array of one to four sialyl Lewisx (SLex; NeuAcalpha2-3Gal[Fucalpha1-3]beta1-4GlcNAc) determinants was studied in mice. Following intraperitoneal dosing with lipopolysaccharide, radioiodinated tyrosinamide N-linked oligosaccharides were dosed i.v. and analyzed for their pharmacokinetics and biodistribution. Specific targeting was determined from the degree of SLex oligosaccharide targeting relative to a sialyl oligosaccharide control. Oligosaccharides targeted the kidney with the greatest selectivity after a 4-h induction period following lipopolysaccharide dosing. Unique pharmacokinetic profiles were identified for SLex biantennary and triantennary oligosaccharides but not for monovalent and tetraantennary SLex oligosaccharides or sialyl oligosaccharide controls. Biodistribution studies established that both SLex biantennary and triantennary oligosaccharides distributed to the kidney with 2-3-fold selectivity over sialyl oligosaccharide controls, whereas monovalent and tetraantennary SLex oligosaccharides failed to mediate specific kidney targeting. Simultaneous dosing of SLex biantennary or triantennary oligosaccharide with a mouse anti-E-selectin monoclonal antibody blocked kidney targeting, whereas co-administration with anti-P-selectin monoclonal antibody did not significantly block kidney targeting. The results suggest that SLex biantennary and triantennary are N-linked oligosaccharide ligands for E-selectin and implicate E-selectin as a bivalent receptor in the murine kidney endothelium.