Gut microbiota modulate inflammation and cortical damage

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 were 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. Dr Federico Montini (Brigham and Women's Hospital, MA, USA) and colleagues set out to investigate whether gut microbiota are associated with 7T MRI metrics (notably cerebral LME and cortical lesions [CL]) in MS [1]. Enrolled were 28 participants 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 researchers extracted stool DNA and performed 16S RNA-sequencing. LME and CLs were quantified by 2 blinded experts. The data science platform QIIME 2 (pronounced chime 2) and the statistical package Microbiome Multivariable Association with Linear Models (MaAsLin2) were deployed to detect associations.

The results showed that gut microbiota were 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,” said Dr Montini. The volumetric data analysis revealed that gut microbiota are 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 also reduced. 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 with mucus-degrading bacteria abundance.

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

1. Montini F, et al. Gut microbiota are associated with cortical lesions and leptomeningeal enhancement on 7T MRI. Abstract O008, ECTRIMS 2024, 18–20 September, Copenhagen, Denmark.

 

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Posted on 18 November 202418 November 2024