Bacteroides vesicles promote functional alterations in the gut microbiota composition

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Inflammatory bowel diseases (IBD) involve chronic intestinal inflammation and gut dysbiosis.
• Bacteroides fragilis outer membrane vesicles (OMVs), containing polysaccharide A (PSA), may modulate inflammation and microbiota.
• PSA alone has shown efficacy in preventing chemically induced colitis.

Purpose of the Study:

• To investigate the therapeutic potential of B. fragilis OMVs in a murine model of chronic DSS-induced colitis.
• To assess the impact of OMV treatment on intestinal inflammation, microbiota composition, and fecal volatile compounds.

Main Methods:

• Induction of chronic colitis in mice using sodium dextran sulfate (DSS).
• Treatment of colitis model with B. fragilis OMVs.
• Monitoring disease activity index (DAI) and histological examination (HE) for therapeutic efficacy.
• Analysis of gut microbiota composition via 16S rRNA gene sequencing.
• Evaluation of fecal volatile compounds using HS-GC/MS for functional microbiota assessment.

Main Results:

• OMV treatment led to significant intestinal repair, indicated by improved DAI and HE scores.
• Metabolomic analysis revealed altered fecal volatile compound profiles, with reduced phenol and pentanoic acid in OMV-treated groups.
• 16S rRNA sequencing and metabolomics indicated that OMV treatment shifted microbiota composition towards a healthier state.
• Correlation analysis showed distinct associations between specific metabolites and bacterial taxa in control versus OMV-treated groups.

Conclusions:

• B. fragilis OMVs exhibit potent anti-inflammatory effects and promote intestinal healing in experimental colitis.
• OMVs contribute to the recovery of gut microbiota structure and function.
• These findings highlight the therapeutic promise of B. fragilis OMVs for managing inflammatory bowel diseases.