FIGURE 4.

Lactobacillus bulgaricus, Bifidobacterium, and Streptococcus thermophilus prevents E. coli K1-induced disruption of intestinal integrity. HT-29 cells were cultured on the upper chamber of the Transwell insert and pre-treated with or without LBS before E. coli K1 infection. Cells treated with PBS or LBS alone were served as controls. After infection, HRP was added to the upper chamber of Transwell for 1 h. Bacteria and HRP translocated from the upper chamber to the lower chamber were quantified as described in section “Materials and Methods.” (A) The OD₄₅₀ value of HRP. (B) The number of E. coli K1 CFU, which penetrated across the HT-29 monolayer. Results are represented as mean ± SD. ^∗P < 0.05, ^∗∗∗P < 0.001. (C) HT-29 cells were treated as described in Figure 1, proteins of each group were isolated for western blotting. The expressions of ZO-1 and occludin was determined, β-Actin band was used as an indicator of protein loading.