Identifying Efficient Clostridium difficile Toxin A Binders with a Multivalent Neo-Glycoprotein Glycan Library

Area of Science:

• Microbiology and Immunology
• Carbohydrate Chemistry
• Gastroenterology

Background:

• Clostridium difficile infections (CDI) present significant gastrointestinal health risks, necessitating novel therapeutic strategies beyond antibiotics.
• Bacterial enterotoxins, Toxin A (TcdA) and Toxin B (TcdB), initiate CDI by binding to intestinal epithelial cell surface glycans.
• Current therapeutic approaches lack effective methods for toxin scavenging, highlighting a critical unmet need.

Purpose of the Study:

• To develop and identify an effective multivalent glycan ligand capable of scavenging Clostridium difficile toxins.
• To investigate the potential of a neo-glycoprotein-based glycan library for therapeutic applications against CDI.

Main Methods:

• Construction of a neo-glycoprotein-based glycan library featuring 40 different glycan epitopes derived from N-acetyllactosamine precursors.
• Screening of the library to identify high-affinity glycan ligands for TcdA receptor domain and holotoxin.
• De novo synthesis and multivalent presentation of the lead glycan epitope (Lewis y-Lewis x) coupled to a Bovine Serum Albumin (BSA) scaffold.

Main Results:

• Nine glycan structures demonstrated strong binding to the TcdA receptor domain.
• The Lewis y-Lewis x epitope exhibited superior binding affinity for both the TcdA receptor domain and the holotoxin.
• The synthesized multivalent neo-glycoprotein effectively scavenged TcdA in vitro and protected HT29 cells from toxin-induced damage.

Conclusions:

• Multivalent presentation of glycans is a viable strategy for developing novel therapeutics against Clostridium difficile.
• The identified Lewis y-Lewis x-based neo-glycoprotein shows significant potential for in vitro toxin neutralization and therapeutic intervention in CDI.
• This approach offers a promising antibiotic-sparing alternative for managing Clostridium difficile infections.