A link indeed appears to exist between multiple sclerosis (MS) and unusual changes in the bacterial composition of the gut, according to researchers at Brigham and Women’s Hospital (BWH).
In their study, “Alterations of the human gut microbiome in multiple sclerosis,” published in the journal Nature Communications, the researchers revealed that MS patients experience modifications in their gut microbiome toward an environment rich in bacteria involved in inflammation and autoimmunity. The findings may help in developing therapies that target the gut’s bacteria.
“Our findings raise the possibility that by affecting the gut microbiome, one could come up with treatments for MS — treatments that affect the microbiome, and, in turn, the immune response,” said Howard L. Weiner, MD, director of the Partners MS Center and co-director of the Ann Romney Center for Neurologic Disease at BWH, in a press release. “There are a number of ways that the microbiome could play a role in MS and this opens up a whole new world of looking at the disease in a way that it’s never been looked at before.”
The gut microbiome is important in that can influence both local and systemic immune responses. Not surprisingly, it has been implicated in several immunologic disorders, including inflammatory bowel disease, type 1 diabetes, and rheumatoid arthritis as well as MS.
A number of studies in mice have shown that altering the gut microbiome can induce autoimmunity in the central nervous system, as well as increase the severity of the disease in MS models. In patients with MS, changes in the gut composition have also been found, but how they relate to treatment or changes in immunity has not been addressed.
Researchers examined stool samples from 60 MS patients included in the Comprehensive Longitudinal Investigation in Multiple Sclerosis study at BWH, and compared them with samples from 48 healthy controls. Differences in microbial composition were analyzed through gene sequencing.
Results revealed that MS patients had higher levels of specific bacterial species, such as Akkermansia and Methanobrevibacter, and lower levels of other species, such as Butyricimona. Some of these bacteria have already been shown to be involved in inflammatory and autoimmunity processes, and consistently, the team found that the activity of some genes known to play a role in the immune system was also altered.
The researchers then examined the effect of disease-modifying drugs on the gut composition of previously untreated patients. Their results showed that the drugs were able to normalize these patients’ gut microbiome.
“This work provides a window into how the gut can affect the immune system, which can then affect the brain,” said Dr. Weiner, a professor of Neurology at Harvard Medical School. “Characterizing the gut microbiome in those with MS may provide new opportunities to diagnose MS and point us toward new interventions to help prevent disease development in those who are at risk.”