Core 2 mucin-type O-glycan inhibits EPEC or EHEC O157:H7 invasion into HT-29 epithelial cells

Background: How host cell glycosylation affects EPEC or EHEC O157:H7 invasion is unclear. This study investigated whether and how O-glycans were involved in EPEC or EHEC O157:H7 invasion into HT-29 cells. Results: Lectin histochemical staining confirmed stronger staining with PNA, which labeled Gal beta 1, 3 GalNAc (core 1 structure) in HT-29-Gal-OBN and C2GnT2-sh2/HT-29 cells, compared with control cells. EPEC or EHEC O157:H7 invasion into HT-29 and its derived cells was based on the intracellular presence of GFP-labeled bacteria. The differentiation of HT-29 cells led to a reduction in EPEC internalization compared with HT-29 cells (p < 0.01). EPEC or EHEC O157:H7 invasion into HT-29-OBN and HT-29-Gal-OBN cells increased compared with HT-29 and HT-29-Gal cells (p < 0.05 and p < 0.01). Core 2 O-glycan-deficient HT-29 cells underwent a significant increase in EPEC (p < 0.01) or EHEC O157:H7 (p < 0.05) invasion compared with control cells. Methods: Bacterial invasion into cultured cells was determined by a gentamicin protection assay and a GFP-labeled bacteria invasion assay. O-glycans biosynthesis was inhibited by benzyl-alpha-GalNAc, and core 2 O-glycan-deficient HT-29 cells were induced by C2GnT2 interference. Conclusion: These data indicated that EPEC or EHEC O157: H7 invasion into HT-29 cells was related to their O-glycosylation status. This study provided the first evidence of carbohydrate-dependent EPEC or EHEC O157:H7 invasion into host cells.