ROLE OF MUCIN, MANNOSE, AND BETA-1 INTEGRIN RECEPTORS IN ESCHERICHIA-COLI TRANSLOCATION ACROSS CACO-2 CELL MONOLAYERS

Our previous work suggests that Caco-2 cells play an active role in ba cterial translocation (BT). Since bacterial enterocyte interactions ma y be receptor-mediated, the current study was performed to investigate the role of beta 1 integrin and mannose receptors as well as the gene ral protective effect of the mucous layer in this process. Caco-2 cell s grown to confluence on semipermeable membranes contained in the uppe r compartment of a two compartment system were utilized. BT was assess ed by quantitating the number of Escherichia coli crossing the monolay ers after challenge with 10(8) E. ColiC25. Pretreatment of the Caco-2 cells with the beta 1 integrin receptor competitive inhibitors fibrone ctin or RGD did not inhibit BT; while pretreatment of Caco-2 cells wit h the LFA-1 (lectin) receptor competitive inhibitor mannose (12 mg/ml) or purified mucin (8 mg/ml) decreased BT compared to control membrane s (p < .001). Transepithelial resistance was similar among all the gro ups indicating maintenence of tight junction integrity. These studies suggest that E. coli BT in the Caco-2 system can be reduced by mannose and that intestinal mucin contributes to the barrier function of the monolayer.