Figure 7. Involvement of EGFR signaling in recombinant bacteria–mediated protection.

Eight-week-old female C57BL/6 mice (n = 8–15) were treated twice with 3% DSS after oral gavages with 1 × 10⁹ EcN or EGF-EcN. Mice were then injected (intraperitoneally) with EGFR inhibitor (1 mg AG1478/mouse, Selleckchem) twice at 2-day intervals before and after the last day of DSS exposure. (A) Schematic outline of EGFR inhibition in the EcN or EGF-EcN treatment and DSS-induced colitis model. (B) Expression of p-EGFR in mucosa (green with the white arrow) was quantified (left box-and-whisker plot, min to max, based on fluorescence microscopy observations, shown at right) (*P < 0.05; **P < 0.01; ***P < 0.001; ns using 2-tailed, unpaired Student’s t test). (C) Representative hematoxylin and eosin (H&E) staining of the intestinal lesions as demonstrated by microscopy (original magnification, ×200). Scale bar: 100 μm. (D) Colons were isolated for analysis of goblet cells and mucin production and were stained with Alcian blue (original magnification, ×400. Scale bar: 100 μm). Each histogram represents events at an increasing Alcian blue level. A quantitative comparison is shown in the right graph (*P < 0.05; **P < 0.01; ***P < 0.001; ns using 2-tailed, unpaired Student’s t test). (E) Gram staining (original magnification, ×400. Scale bar: 100 μm). The asterisks represent significant differences between 2 groups (the right graph) (**P < 0.01; ***P < 0.001 using 2-tailed, unpaired Student’s t test).