Significant differences in gut bacteria revealed in people with MS

Published: 29 September 2022

A new study has found that the gut bacteria of people with multiple sclerosis (MS) is altered compared with healthy people. This has been noted in previous studies, but this is the first piece of research to compare the gut bacteria of people with MS to that of people living within the same household.

A person’s gut bacteria is influenced by environmental factors like their diet and where they live. People sharing a household have more comparable environments, so researchers looked at people that lived together.

The research, by the International Multiple Sclerosis Microbiome Study (iMSMS), looked at 576 pairs of people, in which one person had MS, and the other was someone they lived with without MS. Of the MS patients, 76% had relapsing remitting MS, 24% had progressive MS and two-thirds of the people with MS were taking a disease modifying therapy.

Stool samples were collected to analyse gut bacteria. In line with other studies, the area people lived in caused the biggest difference in microbiome. Age, sex and other factors were associated with differences too, but these differences were accounted for.

Researchers found 16 different species of bacteria that were present in the guts of people with MS in significantly higher amounts than in the control group. Many of these are known to have properties that could theoretically contribute to MS. They also found there were seven species that were present at significantly lower levels than in the control group.

One bacteria species that was found to be decreased in MS patients was Faecalibacterium prausnitzii which has anti-inflammatory properties. Analysing the metabolic pathways showed that there were disease-relevant changes to this lack of bacteria, namely a reduction in a molecule that F. prausnitzii helps make called pyruvate.

“We found a depletion of potentially beneficial bacteria in untreated MS patients compared with healthy controls, which in turn disturbed key metabolic pathways that might be expected to worsen MS inflammation,” the researcher said.

In progressive MS patients, the species Clostridium, Butyrivibrio and Ruminococcus were associated with less disease severity, and the presence of the bacteria group Prevotella was linked with greater disease severity.

In people with RRMS, the species Collinsella aerofaciens was linked to more severe disease, whereas the group of bacteria Bacteroides were linked to less severe disease.

Medication was also thought to affect gut microbiome. Some bacterial species from the group Akkermansia were altered compared with the control group in patients not receiving treatment, but were found not to be altered in those on disease-modifying therapies.