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 3

EGF-EcN–mediated actions in EGFR signaling in DSS-induced colitis.

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EGF-EcN–mediated actions in EGFR signaling in DSS-induced colitis. (A–C)...
(A–C) 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) Insulted colons were analyzed by IHC using the phosphorylated EGFR (p-EGFR) antibody with hematoxylin counterstaining. A microscopy image at original magnification of ×200 is shown at left. The relative density of p-EGFR was measured by using the HistoQuest tissue analysis software (each histogram of events with increasing diaminobenzidine (DAB) levels, described in the Methods section in detail). A quantitative comparison is shown in the right graphs. Scale bar: 100 μm. Results are shown as a box-and-whisker plot (min to max), and different letters represent a significant difference between groups (P < 0.05 using 1-way ANOVA with the Newman-Keuls post hoc test). (B) Each group of mouse colon lysates was subjected to Western blot analysis. The blots are representative of 3 independent experiments. (C) Eight-week-old female C57BL/6 mice were infected with 1 × 109 EcN or EGF-EcN via oral gavage twice at 3-day intervals, and mouse gut was isolated on the third day after the second inoculation. LARD-tagged EGF secreted from the EGF-EcN and activated EGFR were detected in the colonic mucosa. The white arrows indicate EGFR-Tyr1068 (green) in the mucosa, and the numbers in the upper left represent the relative levels of LARD-EGF or p-EGFR. Relative levels of p-EGFR in mucosa were compared in the box-and-whisker plot (min to max) (right), and the asterisks represent a significant difference between 2 groups (***P < 0.001 using 2-tailed, unpaired Student’s t test).