Multiple sclerosis patients exhibit oral dysbiosis with decreased early colonizers and lower hypotaurine level

Although gut microbiome dysbiosis is implicated in the pathobiology of multiple sclerosis (MS), the role of the oral microbiome (OM), the second largest microbiome, remains poorly understood. Additionally, while the salivary metabolome has been linked to other neurodegenerative diseases; its role in people with Relapsing-Remitting MS (pwRRMS), the most prevalent form of MS, is unknown. Combining shotgun metagenomics with untargeted metabolomics, we identified a reduced abundance of several early colonizing species including Streptococcus and Actinomyces in pwRRMS and an enrichment of bacteria with pathogenic potential including Fusobacterium nucleatum, Porphyromonas gingivalis, and several Prevotella species. pwRRMS had an altered metabolite profile including a decreased hypotaurine compared to healthy controls. Thus we report altered oral microbiome and metabolome in pwRRMS which might contribute to MS pathobiology. These findings offer potential microbiome-metabolome based diagnostic biomarkers for MS and pave the way for novel therapeutic interventions to improve disease management and patient outcomes.