Inhibition of lectin adherence to tissue culture cells by prebiotic carbohydrates

Prebiotic carbohydrates, in addition to their ability to influence the colonic microbiota, are also able to inhibit attachment of pathogenic bacteria to epithelial cells. This effect is mediated via their structural similarity to the carbohydrate ligands, located on the mucosal cell surface to which bacterial lectins attach. However, the mechanism for this inhibition is not well understood. The goal of this research was to measure the effect of two prebiotic carbohydrates, galactooli-gosaccharide and polydextrose, on the binding kinetics of plant lectins, having known ligand specificity, to tissue culture cells. To measure adherence, competetion experiments were conducted with HEp-2 cells exposed to nine fluorescent-labeled lectins and either the cognate ligand or a prebiotic. Fluorescence microscopy and image analysis were used to quantify adherence. Lectins that were able to bind to target cells were significantly inhibited in the presence of the cognate ligands. When prebiotics were added, inhibittion of lectin binding was observed, depending on the structural similarity between the prebiotic and the cognate ligands. In general, PDX did not inhibit lectin attachment, whereas GOS significantly inhibited most lectins. This research suggests that receptor sites located on the surface of epithelial HEp-2 cells are structurally similar to GOS.