Microscopic Colitis Patients Possess a Perturbed and Inflammatory Gut Microbiota

Area of Science:

• Gastroenterology
• Microbiology
• Immunology

Background:

• Microscopic colitis (MC) is an inflammatory colon disease causing chronic diarrhea.
• The exact cause of MC is unknown, but gut microbiome alterations are suspected.
• The relationship between fecal microbiota and MC remains underexplored.

Purpose of the Study:

• To investigate differences in fecal microbiota composition and function between MC patients and healthy controls.
• To assess the inflammatory potential of MC-associated microbiota using an in vitro colonocyte model.

Main Methods:

• 16S rRNA V4 amplicon sequencing of stool microbiota from 15 MC patients and 21 healthy controls (HC).
• Microbiota functions were predicted using Piphillin.
• Inflammatory potential was assessed via an in vitro HT29 colonocyte cell assay.

Main Results:

• MC fecal microbiota showed significantly lower diversity and distinct composition compared to HC.
• MC microbiota were depleted of Clostridiales and enriched for Prevotella.
• In vitro assays indicated MC microbiota products altered colonocyte gene expression, including reduced IL-1B and occludin, and increased GPR119 and CCL20.

Conclusions:

• MC gut microbiota are characterized by reduced diversity, Prevotella enrichment, and distinct functional pathways.
• MC microbiota induce unique responses in epithelial cells, suggesting a role in mucosal dysfunction.
• Microbiota perturbation is implicated in the pathogenesis of microscopic colitis.