Selectin/glycoconjugate binding assays for the identification and optimization of selectin antagonists

Area of Science:

• Biochemistry
• Immunology
• Glycobiology

Background:

• Selectins are crucial cell adhesion molecules involved in inflammatory responses.
• Developing selective inhibitors for selectins is a key therapeutic strategy.
• Existing assays for selectin antagonists can be limited in scope and efficiency.

Purpose of the Study:

• To develop and validate novel ELISA-type assays for P- and L-selectin binding.
• To utilize a synthetic glycoconjugate, sialyl Lewis A (sLe(a))-polymer, as a ligand for selectin analysis.
• To assess the utility of these assays in screening and characterizing selectin antagonists.

Main Methods:

• Enzyme-linked immunosorbent assay (ELISA) format utilizing recombinant P- and L-selectins.
• A biotinylated sialyl Lewis A (sLe(a))-polymer as a synthetic ligand.
• Precomplexation of the ligand with streptavidin-peroxidase for detection via peroxidase activity.
• Inhibition studies using specific antibodies and known selectin-binding compounds (heparin, fucoidan, sialyl Lewis X).

Main Results:

• The sLe(a)-polymer demonstrated cation-dependent binding to both P- and L-selectins.
• Binding was inhibited by specific anti-selectin antibodies and reference inhibitors.
• Sialyl Lewis X (sLe(x)) showed selective inhibition of L-selectin binding.
• The assays exhibited low variability and were rapid to perform.
• The P-selectin assay successfully identified and optimized carbohydrate-based antagonists.
• Comparative analysis with E-selectin assays revealed fine selectivity of antagonists.

Conclusions:

• Developed ELISA assays using sLe(a)-polymer are effective for analyzing P- and L-selectin binding.
• These assays are suitable for the primary screening and characterization of selectin antagonists.
• The methodology allows for the identification of novel carbohydrate-based inhibitors with potential therapeutic applications.