Objective:

To investigate oral microbial profiles and salivary metabolite levels in patients with relapsing–remitting multiple sclerosis (RRMS) compared to healthy controls.

Approach:

• Study Design: Cross-sectional case–control study involving 50 adults with RRMS and 50 age-matched healthy controls.
• Microbial Analysis: Shotgun metagenomic sequencing of oral swabs to evaluate microbial diversity and composition.
• Metabolomic Profiling: Untargeted salivary metabolomic profiling using liquid chromatography–mass spectrometry.
• Statistical Analysis: Alpha and beta diversity measures, random forest model for classification accuracy, and correlation networks linking microbial species to metabolites.

Key Findings:

• Distinct oral microbial profiles in RRMS patients with reduced salivary hypotaurine.
• Lower microbial diversity and significant differences in community composition between RRMS patients and controls.
• Reduction in common Gram-positive species and increase in Gram-negative bacteria in RRMS patients.
• Metabolomic analysis revealed reduced levels of five salivary metabolites and elevated levels of nine metabolites in RRMS patients.
• Random forest model showed moderate accuracy in distinguishing RRMS from controls (67% for controls, 89% for RRMS patients).
• A total of 102 microbial species varied in abundance, including 96 bacterial, 5 viral, and 1 fungal species.

Interpretation:

Limitations:

• Lack of dental or periodontal assessments limits evaluation of gum disease as a confounder.
• Single-center design may restrict generalizability.
• Cross-sectional nature prevents establishing causality.
• Modest sample size limits detection of smaller subgroup differences.

Conclusion:

Sources:

• npj biofilms and microbioms