Fecal let-7b and miR-21 directly modulate the intestinal microbiota, driving chronic inflammation

Area of Science:

• Gastroenterology
• Microbiology
• Molecular Biology

Background:

• Inflammatory bowel diseases (IBD) have complex causes, with the role of fecal microRNAs (miRNAs) in gut inflammation and microbiota interaction not fully understood.
• Fecal miRNAs are implicated in chronic inflammation, but their specific contribution to IBD pathogenesis requires further investigation.

Purpose of the Study:

• To investigate the role of fecal let-7b and miR-21 in IBD pathogenesis.
• To determine how these miRNAs influence the gut microbiota and host-immune response.
• To evaluate the therapeutic potential of inhibiting let-7b and miR-21 in colitis models.

Main Methods:

• Analysis of fecal let-7b and miR-21 levels in IBD patients and IL-10-/- mice.
• In vitro microbiota modeling to assess miRNA effects on microbial composition and function.
• In vivo studies in mice to evaluate the impact of luminal miRNA increase and inhibition on intestinal inflammation, barrier function, and host-microbiota interactions.

Main Results:

• Elevated fecal let-7b and miR-21 correlated with inflammation and specific bacteria in IBD patients and mice.
• let-7b and miR-21 directly altered microbiota composition, increasing its proinflammatory potential.
• Luminal let-7b increased pro-inflammatory cytokines, while miR-21 impaired gut barrier function and induced dysbiosis.
• In vivo inhibition of let-7b and miR-21 improved gut barrier function, promoted healthier host-microbiota interactions, and protected against colitis.

Conclusions:

• Fecal miRNAs, specifically let-7b and miR-21, play a functional role in host-microbiota communication.
• These miRNAs contribute to intestinal inflammation and dysbiosis in IBD.
• Targeting fecal miRNAs with anti-miRNAs presents a promising therapeutic strategy for IBD and related conditions.