Receptors involved in carbohydrate binding modulate intestinal epithelial- neutrophil interactions

Abstract

Neutrophil (polymorphonuclear neutrophil) migration across epithelial barriers is a common morphologic feature of many diseases. Previous studies show that PMN-epithelial interactions are dependent on the PMN β2-integrin CD11b/18; however, nothing is known about surface carbohydrates and PMN- epithelial interactions. Here we investigate the role of carbohydrates on PMN-epithelial interactions using PMN and cultured monolayers of the intestinal epithelial cell line T84. Addition of the carbohydrates mannose 6- phosphate (Man-6-P) and glucose 6-phosphate (Glu-6-P), but not fructose 1- phosphate (Fru-1-P) inhibited transmigration by ≥70%. Likewise, more complex carbohydrates, such as fucoidin and the Man-6-P-rich polysaccharide PPME selectively inhibited PMN transepithelial migration. These carbohydrates were found to be inhibitory in the apical-to-basolateral direction as well as the basolateral-to-apical direction, indicating a lack of polarity. This panel of related carbohydrates, however, was not effective in modulating short-term adhesion of PMN to epithelial monolayers, indicating that carbohydrate ligands may modulate different steps in the transmigration cascade. Finally, addition of functionally inhibitory monoclonal antibodies specific for the selectins (CD62E, CD62L, and CD62P) revealed no observable effect on PMN transmigration. These studies suggest that cell surface carbohydrates may play a role in inflammatory processes of the intestine.