The multiple sclerosis gut microbiome and disease activity: A systematic review

Area of Science:

• Microbiome research
• Neurology
• Immunology

Background:

• The gut microbiome's role in multiple sclerosis (MS) is a growing area of research, but its specific associations with disease activity remain unclear.
• Understanding these links is crucial for developing targeted microbiome-based therapies for MS.
• This systematic review investigates the relationship between gut microbial composition and MS disease activity, course, and progression.

Approach:

• A comprehensive literature search was conducted across major databases (MEDLINE, EMBASE, Web of Science, Google Scholar) from January 2011 to February 2024.
• Included studies were observational or interventional, excluding case reports, and focused on MS disease activity, course, and disability progression (e.g., relapses, MRI findings, EDSS scores).
• Study quality was assessed using the Newcastle-Ottawa Scale to ensure reliability of findings.

Key Points:

• Out of 23 studies (1760 MS patients), most found no association between overall gut microbial diversity and MS outcomes.
• Specific bacterial taxa showed significant associations: higher Actinobacteria, Bacteroidota, and Roseburia inulinivorans linked to better MS outcomes (lower EDSS).
• Conversely, increased Streptococcus, Clostridium nexile, Clostridium scindens, and Collinsella aerofaciens were associated with worse outcomes (higher MRI lesion volumes).

Conclusions:

• Gut microbial diversity is not consistently linked to multiple sclerosis outcomes.
• Specific bacterial taxa, including short-chain fatty acid producers like Bacteroidota, show associations with MS disease severity and progression.
• The predominance of cross-sectional studies highlights the need for longitudinal research to establish causality.