Specific microbial ratio in the gut microbiome is associated with multiple sclerosis

Area of Science:

• Microbiome research
• Neuroimmunology
• Gut-brain axis

Background:

• Gut microbiota dysbiosis is implicated in multiple sclerosis (MS) pathogenesis.
• The precise role of specific gut bacteria in MS remains unclear.

Purpose of the Study:

• To investigate the gut microbiome composition in people with MS (PwMS) compared to healthy controls (HC).
• To identify specific bacterial species and ratios associated with MS.
• To explore the functional impact of identified bacteria on gut inflammation and MS-like pathology in a mouse model.

Main Methods:

• Shotgun metagenomic sequencing of stool microbiomes from PwMS and HC.
• Administration of *Blautia wexlerae* (BW) to mice to assess gut inflammatory markers and microbiota changes.
• Induction of experimental autoimmune encephalomyelitis (EAE) in mice to model MS and evaluate the impact of BW and microbial ratios on disease severity.

Main Results:

• Distinct gut microbiome profiles were observed between PwMS and HC, with *Blautia* species identified as drivers in PwMS.
• Administration of *Blautia wexlerae* increased gut inflammatory markers and pro-inflammatory cytokine induction capacity in mice.
• A lower *Bifidobacterium* to *Akkermansia* ratio, specifically *Bifidobacterium adolescentis* to *Akkermansia muciniphila* (BA:AM), was associated with MS and correlated with increased EAE severity in mice.

Conclusions:

• The *Bifidobacterium adolescentis* to *Akkermansia muciniphila* (BA:AM) ratio serves as a potential gut microbial biomarker for MS.
• This ratio may aid in the diagnosis and prognosis of MS.
• Findings suggest potential for microbiome-based therapeutic strategies for MS.