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To assess the role of gut microbiota as a risk factor of MS, researchers correlated the presence of specific bacteria with 7T MRI metrics. Detrimental bacteria, notably Alistipes onderdonkii, had a positive association with cerebral leptomeningeal enhancement (LME), a feature of MS. Butyrate-producing bacteria was found to be negatively associated with LME. These findings provide further evidence of an association between microbes and MS pathogenesis.

Gut microbiota have a role in MS pathogenesis and may also influence MRI findings. Federico Montini, MD, from the Brigham and Women’s Hospital, in Boston and his group set out to investigate if gut microbiota is associated with 7T MRI metrics (notably cerebral LME and cortical lesions [CL]) in MS. Dr. Montini explained that they included 28 patients with MS with a median age of 53 years. Participants underwent 7T MRI scans and their stools were collected within 6 months after the scan.

The results showed that gut microbiota was associated with LME foci count, CL count and volume, and T2-lesion volume. “It was very interesting to see that several butyrate-producing bacteria, such as Roseburia, Agathobacter, and Blautia, had a beneficial effect on LME (i.e. less LME foci), whereas Alistipes onderdonkii and Ruminococcus had a detrimental effect.” The volumetric data analysis revealed that gut microbiota is associated with volumes of the thalamus, caudate, globus pallidus, putamen, and deep grey matter; Butyrococcus and Prevotella had a beneficial effect (i.e. less atrophy), while for example Collinsella intestinales had a detrimental effect.

Stool MUC2 levels were reduced in MS. MUC2 is a major structural component of the protective mucus layer in the colon and small intestine. Stool MUC2 levels were negatively associated with LME foci count and negatively associated with mucus-degrading bacteria abundance.

Dr. Montini concluded that these findings may indicate that disruption of the mucus layer facilitates a (too) narrow bacterial-immune system interaction, favoring LME development.

Medical writing support was provided by Michiel Tent

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