Background and aim: The roles of host glycosylation in interactions with EPEC and EHEC O157:H7 are largely unclear; this study examined whether O-glycans are involved in EPEC and EHEC O157:H7 adherence to HT-29 cells.
Methods: Bacterial adherence to the cultured cells was determined using the direct co-staining of adherent bacteria and host cells, the adherent bacteria plating, and/or the direct fluorescent observation of the adherent GFP-labeled bacteria.
Results: A comparison of the adherence of EPEC and EHEC O157:H7 to HT-29-Gal and HT-29 cells indicated that the differentiation of HT-29 cells led to a reduction in the adherence of EPEC and EHEC O157:H7. EPEC and EHEC O157:H7 adhesion decreased after the abrogation of O-glycan biosynthesis mediated by benzyl-α-GalNAc treatment. Core 2 O-glycan-deficient HT-29 cells induced by C2GnT2 knockdown had a significant reduction in EPEC and EHEC O157:H7 adhesion in C2GnT2-sh2/HT-29 cells compared with HT-29 and shRNA-Ctr/HT-29 cells. MUC2 expression in benzyl-α-GalNAc-treated HT-29 cells was significantly reduced but unchanged in C2GnT2-deficient HT-29 cells. EPEC or EHEC O157:H7 infection in C2GnT2-deficient HT-29 cells deteriorated the epithelial barrier function. The occludin expression in the shRNA-Ctr/HT-29 and C2GnT2-sh2/HT-29 cells after infection with EPEC or EHEC O157:H7 was pyknic and discontinuous at the cell surface compared with its continuous distribution of control cells. These data indicate that EPEC and EHEC O157:H7 adherence to HT-29 cells is related to mucin-type core 2 O-glycan.
Conclusions: This study provides the concepts toward the design of carbohydrate-dependent inhibition of EPEC and EHEC O157:H7 adhesion to human intestinal epithelial cells.