- An international team led by researchers at Brigham and Women’s Hospital in Boston describes a pathway by which substances in the diet and bacteria in the gut can act to suppress inflammation in the brain of mice with MS-like disease, and also show evidence that this pathway exists in people with MS.
- The team plans to investigate further to determine if the findings can be translated into new treatment approaches for people with MS.
- Senior author Francisco Quintana, PhD, was funded in this work by the National MS Society, the international Progressive MS Alliance and other funders.
- The team (Veit Rothhammer, MD, Dr. Quintana and colleagues at Brigham and Women’s Hospital and other institutions worldwide) has published results in Nature Medicine (published early online, May 9, 2016).
MS involves immune-system attacks against the brain and spinal cord. The gut, including the small and large intestine, is the largest immune organ in mammals, including people. Each of us has millions of “commensal” bacteria living within our guts. Most of these bacteria are harmless as long as they remain in the inner wall of the intestine. They play a critical role in our normal physiology, and accumulating research suggests that they are critical in the establishment and maintenance of immune balance by the molecules they release.
Investigators first analyzed the genes involved in instructing astrocytes, cells that help to support the brain’s structure, especially during MS-like disease in mouse models. The findings indicate that immune messenger proteins known as interferons provide signals to astrocytes and that these signals limit immune system activity in the brain during disease. They found, in particular, that these signals are mediated through a molecule known as the aryl hydrocarbon receptor (AHR).
Previous research has indicated that AHR is activated by commensal bacteria or substances in the diet. With this in mind, the team administered supplements related to tryptophan – an amino acid found in most protein-based foods – to mice after inducing MS-like disease. Then gut bacteria stimulated AHR activity, which then modulated interferon signals to astrocytes. Inflammation in the brain was reduced, along with disease activity.
Senior author Francisco Quintana, PhD, was funded in this work by the National MS Society, the international Progressive MS Alliance and other funders. According to Dr. Quintana, “What we eat influences the ability of bacteria in our gut to produce small molecules, some of which are capable of traveling all the way to the brain. This opens up an area that’s largely been unknown until now: how the gut controls brain inflammation.”
The authors also tested AHR levels in blood samples from people with MS and controls without MS, and found this molecule to be decreased in people with MS.
The team (Veit Rothhammer, MD, Francisco Quintana, PhD, and colleagues at Brigham and Women’s Hospital and other institutions worldwide) has published results in Nature Medicine
(published early online, May 9, 2016
The team plans to investigate further to determine if the findings can be translated into new treatment approaches for people with MS. The National MS Society continues to fund research in this area, most recently The MS Microbiome Consortium
, a comprehensive analysis of gut bacteria in people with MS to determine factors that may drive progression and develop probiotic strategies for stopping progression.
Read more about research on diet and MS