Genetic Mouse Models with Intestinal-Specific Tight Junction Deletion Resemble an Ulcerative Colitis Phenotype

Area of Science:

• Gastroenterology
• Molecular Biology
• Inflammatory Bowel Disease Research

Background:

• Ulcerative colitis (UC) is characterized by low mucus phosphatidylcholine (PC).
• Tight junction (TJ) dysfunction may impair PC transport, contributing to UC pathogenesis.
• Investigating TJ integrity is crucial for understanding UC development.

Purpose of the Study:

• To create and analyze mutant mice with intestinal TJ deletion.
• To determine if TJ disruption leads to an ulcerative colitis (UC) phenotype.
• To explore the role of PC in UC pathogenesis.

Main Methods:

• Generated mutant mice with tamoxifen-induced deletion of kindlin 1 and 2.
• Utilized electron and light microscopy to assess TJ morphology and crypts.
• Measured mucus PC content, hydrophobicity, and microbiota penetration.
• Administered oral PC supplementation to evaluate therapeutic effects.
• Compared findings to colonic biopsies from human UC patients.

Main Results:

• Mutant mice exhibited defective TJ morphology, reduced mucus PC (>50%), and decreased hydrophobicity (>50%).
• Microbiota penetrated the submucosa, leading to inflammation and colitis features within 3 days.
• Oral PC supplementation effectively suppressed inflammation in mutant mice.
• Human UC biopsies showed similar TJ defects and impaired PC secretion.

Conclusions:

• Intestinal deletion of kindlin 1 and 2 causes TJ defects, impairing PC secretion and inducing UC-like inflammation.
• These findings establish a genetic mouse model for studying UC.
• PC supplementation shows therapeutic potential for managing UC.