Open Collections

Chan, Jocelyn Joy

University of British Columbia

Background: MUC2 is the primary mucin comprising the intestinal mucus layer that separates noxious luminal stimuli, such as bacteria, from the underlying intestinal epithelium. Muc2-deficient mice (Muc2⁻⧸⁻) display a severely compromised intestinal mucus barrier and develop spontaneous colitis as they age. Defects in the colonic mucus barrier are often observed in patients with ulcerative colitis (UC). Studies have explored whether fecal microbiota transplantation (FMT) is therapeutic in UC. While FMT is highly effective in treating recurrent C. difficile infections with cure rates over 90%, its efficacy in UC shows promising but more variable outcomes, with approximately 36% of patients achieving remission. Here, we utilized Muc2⁻⧸⁻ mice to model FMT for UC, testing its efficacy and exploring underlying mechanisms. Method: Prior to FMT, mice deficient in Muc2 (Muc2⁻⧸⁻) and heterozygous for Muc2 (Muc2⁺⧸⁻) were pretreated with an antifungal drug (amphotericin B) and given broad-spectrum antibiotics (vancomycin, ampicillin, neomycin, metronidazole) for a week in their drinking water. Following a 24-hour antibiotic washout period, lyophilized FMT from pooled C57BL/6 mice stool or a lyophilized sucrose control was administered ad libitum for three consecutive days. Mice were euthanized at several key timepoints to examine both acute and long-term effects: Day 3 of administering FMT, 2 weeks post-FMT, and 20 weeks post-FMT. Results: Without FMT, antibiotic-treated Muc2⁻⧸⁻ mice developed spontaneous colitis, experienced bacterial translocation, and required humane euthanasia at early timepoints. Lyophilized FMT engrafted in Muc2⁻⧸⁻ mice, restoring microbial diversity and enhancing intestinal barrier function. FMT reduced intestinal permeability, prevented bacterial penetration of colonic crypts, mitigated colitic pathology, and stimulated changes in the intestinal epithelium characterized by elevated transcription and production of trefoil factor 3 (TFF3) and mucins, including mucin 5AC (MUC5AC). Conclusion: FMT delayed the onset of spontaneous colitis in Muc2⁻⧸⁻ mice and increased their survival rates following antibiotic treatment. The protective effects were evident in terms of colonic pathology as early as the third day of treatment. FMT-treated Muc2⁻⧸⁻ mice exhibited improved mucosal epithelial integrity, characterized by reduced intestinal permeability and absence of bacterial translocation, and elevated gene expression of goblet cell-secreted factors such as TFF3, MUC3, and MUC5AC.

Text

2024-07-17

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88659

Experimental Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/