In September 2022, the largest study to date on the gut microbiome, i.e. the bacteria that make up the gut microbiota, their genes and metabolites, in people affected by multiple sclerosis (MS) was published in the prestigious scientific journal Cell (2022 Sep 15;185(19):3467-3486). This study was conducted by the International Consortium for the Study of the Microbiome in MS (iMSMS.org/) under the direction of Dr. Sergio Baranzini, University of California, San Francisco.
This study examined the gut microbiome of 576 people with MS and healthy matched controls living together. The MS affected individuals came from 7 centers in the United States, Argentina, United Kingdom and Spain. Microbial diversity in stool samples from individuals with both relapsing-remitting and progressive MS and its relationship with age, gender, ethnicity, MS treatments and diet was analyzed and assessed using standardized questionnaires. Compared to healthy cohabiting controls, the authors found an over-representation of five bacterial species, including Akkermansia muciniphila, Ruthenibacterium lactatiformans, Hungatella hathewayi and Eisenbergiella tayi, and a decrease in Faecalibacterium prausnitzii and Blautia species. In addition, they observed alterations in certain bacterial metabolic pathways, such as an increase in phytate degradation and a reduction in carbohydrate metabolism that produces pyruvate. In addition, they observed interaction networks between certain bacteria that were different in untreated MS patients compared to healthy controls. The authors conclude that associations exist between microbiome composition and MS risk, disease course and progression, and that MS treatments influence them.
This work is a very important contribution to the study of the gut microbiota in multiple sclerosis as it confirms and extends the findings of several investigators from previous studies and demonstrates that the gut microbiome represents an important environmental risk factor for MS, which can be influenced. Furthermore, this study provides a framework for further research on this topic.