Nononcogenic restoration of the intestinal barrier by E. coli–delivered human EGF
Mira Yu, Juil Kim, Jung Hoon Ahn, Yuseok Moon
Mira Yu, Juil Kim, Jung Hoon Ahn, Yuseok Moon
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Research Article Microbiology

Nononcogenic restoration of the intestinal barrier by E. coli–delivered human EGF

Abstract

Although mucoactive proteins, such as epidermal growth factor (EGF), could improve clinical outcomes of intestinal ulcerative diseases, their gastrointestinal application is limited because of their proteolytic digestion or concerns about tumor promotion. In the present study, ATP-binding cassette (ABC) transporter–linked secretion of human EGF from probiotic Escherichia coli (EGF-EcN) was created to promote beneficial actions of the EGF receptor, which is notably attenuated in patients with intestinal ulcerative injuries. Preventive and postinjury treatment with EGF-EcN alleviated intestinal ulcers and other readouts of disease severity in murine intestinal ulcer models. EGF-EcN administration promoted the restitutive recovery of damaged epithelial layers, particularly via upward expansion of highly proliferating progenitor cells from the lower crypts. Along with the epithelial barrier benefit, EGF-EcN improved goblet cell–associated mucosal integrity, which controls the access of luminal microbiota to the underlying host tissues. Despite concern about the oncogenic action of EGF, EGF-EcN did not aggravate colitis-associated colon cancer; instead, it alleviated protumorigenic activities and improved barrier integrity in the lesions. All findings indicate that probiotic bacteria–based precision delivery of human EGF is a promising mucosal intervention against gastrointestinal ulcers and malignant distress through crypt-derived barrier restoration.

Authors

Mira Yu, Juil Kim, Jung Hoon Ahn, Yuseok Moon

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Figure 6

Effects of EGF-EcN on gut epithelial and mucosal barrier integrity in colonic ulcer.

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Effects of EGF-EcN on gut epithelial and mucosal barrier integrity in co...
Six-week-old female mice were pretreated twice with vehicle, EcN, or EGF-EcN over 7 days (n = 12–15). The mice were then exposed to 3% DSS for 5 days to induce colitis. (A) Gut epithelia were stained with DAPI (blue) and phalloidin-TRITC (red) to stain nucleic acid and F-actin (original magnification, ×400; inset magnification, x8000). Scale bar: 100 μm. White arrows indicate the spread of apical F-actin into the basement membrane. TRITC, tetramethylrhodamine. (B) Colons were isolated for mucin analysis. Secreted and intracellular mucins were stained with Alcian blue (blue colored, original magnification, ×400. Scale bar: 100 μm). Each histogram represents events with increasing Alcian blue levels. A quantitative comparison is shown in the lower graph. (C) Gram staining to determine the accessibility of the total gut bacteria to the epithelial barrier (original magnification, ×400. Scale bar: 100 μm). The asterisks represent significant differences between 2 groups (each lower graph in A, B, and C) (**P < 0.01; ***P < 0.001 using 2-tailed, unpaired Student’s t test). (D) Intestinal permeability was evaluated at 3 hours after oral administration with FITC-conjugated dextran (150 mg/kg body weight). Results are shown as the box-and-whisker plot (min to max), and different letters represent significant differences between groups (P < 0.05 using 1-way ANOVA with the Newman-Keuls post hoc test). The box plots depict the minimum and maximum values (whiskers), the upper and lower quartiles, and the median. The length of the box represents the interquartile range.