A receptor decoy inhibits the enterotoxic effects of Clostridium difficile toxin a in rat ileum

Background & Aims: Clostridium difficile toxin A causes secretion and intestinal inflammation in rodents by binding to a specific trisaccharide Gal alpha(1-3)Gal beta(1-4) GlcNAc on enterocyte receptors. The purpose of this study was to explore the ability of Synsorb 90 (Synsorb Biotech Inc., Calgary, Alberta, Canada), an inert support carrying this trisaccharide, to bind toxin A in vitro and to inhibit its enterotoxic effects in vivo. Methods: Binding of [H-3]toxin A to Synsorb 90, Synsorb 83 (beta-mannose attached), and Chromosorb P (inert support with no sugar attached) (Synsorb Biotech Inc.) was measured. The inhibitory effects of these compounds on toxin A-mediated fluid secretion, mannitol permeability, and histological damage were measured in ileal loops in vivo. Results: Toxin A showed specific binding to Synsorb 90, bearing the specific trisaccharide that binds toxin A, but not to Synsorb 83 or to Chromosorb P. Pretreatment of rats with Synsorb 90 by gavage (200 mg/kg body wt), but not Synsorb 83 or Chromosorb P at the same doses, dramatically reduced toxin A-associated fluid secretion and permeability. Conclusions: An immobilized toxin A receptor sequesters toxin A in the intestinal lumen and inhibits its effects on ileal mucosa. These results suggest a potential use for this agent in treating patients with C. difficile colitis.