Illustration of brain and spine. Istock photo
International research team studying how diet can affect brain inflammation
An international team led by researchers at Brigham and Women’s Hospital in Boston is studying how substances in the diet and gut bacteria can affect brain inflammation and disease activity in mice with a disease similar to multiple sclerosis (MS).
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.
Senior author Francisco Quintana, PhD, received funding from the National MS Society, the international Progressive MS Alliance and others. The team published results online in Nature Medicine in May.
According to the study, accumulating research suggests that gut bacteria are critical in the establishment and maintenance of immune balance by the molecules they release.
The researchers found that the signals that help direct immune system activity in the brain are mediated by a molecule called the aryl hydrocarbon receptor (AHR). Previous research has indicated that AHR is activated by 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 the mice after inducing MS-like disease. Then, gut bacteria stimulated AHR activity, which then modulated the immune system signals. Inflammation in the brain was reduced, along with disease activity.
“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,” says Quintana in a press release. “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 the molecule to be decreased 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, especially probiotic strategies to stop