Figure 5

Immunofluorescence staining to localize tight and adherens junction proteins after Caco-2 cells were incubated with IIL ESPs treated with various inhibitor mixtures. IIL ESPs pre-incubated with different mixtures of 4 inhibitors were added to Caco-2 cell monolayers and incubated at 37 °C for 2 h. The cells were examined under a fluorescence microscope, and the cell nuclei were stained blue with DAPI. When the IIL ESPs were pre-treated with the 4-inhibitor mixtures (PMSF + E-64 + 1,10-Phe + pepstatin), the degradation of occludin, claudin-1 and E-cad by the IIL ESPs was completely blocked, while claudin-2 expression was restored. Scale bars: 50 μm.