Relapsing-Remitting Multiple Sclerosis Is Associated With a Dysbiotic Oral Microbiome.

Area of Science:

• Microbiology
• Immunology
• Neurology

Background:

• Multiple sclerosis (MS) is a chronic autoimmune disease impacting the central nervous system.
• The gut microbiome's role in MS is known, but the oral microbiome's association is less understood, especially in North American populations.

Purpose of the Study:

• To investigate oral bacterial composition, functional pathways, and immune profiles in relapsing-remitting MS (RRMS) patients compared to healthy controls (HC).
• To explore the relationship between oral microbiota and salivary cytokines in RRMS.

Main Methods:

• Saliva samples from 60 RRMS patients and 44 HC were analyzed using 16S rRNA sequencing for bacterial composition.
• Functional pathways were inferred using PICRUSt2, and salivary cytokines were quantified via multiplex immunoassays.
• LEfSe and random forest models identified key taxa, with Spearman analysis assessing microbiota-cytokine correlations.

Main Results:

• RRMS patients displayed distinct oral microbial communities with an increased Bacteroidota to Firmicutes ratio.
• Enriched taxa in RRMS included Campylobacter, Lachnoanaerobaculum, and Porphyromonas; lipopolysaccharide biosynthesis pathways were also elevated.
• Elevated pro-inflammatory cytokines (IFN-γ, IL-6) correlated with the altered microbiome in RRMS patients.

Conclusions:

• This study reveals oral microbiome-host interactions in North American RRMS patients, highlighting microbial dysbiosis, functional pathway alterations, and immune dysregulation.
• The oral microbiome presents potential as a biomarker for MS-associated immune alterations.