Researchers from Brigham and Women’s Hospital (MA, USA) have suggested that neuroinflammation and neurodegeneration may be influenced by diet and gut flora composition. Their findings in mouse models of multiple sclerosis (MS) and patient samples indicate that gut bacteria may impact astrocyte activity and as a result affect disease progression.
Previous research has indicated a link between brain inflammation and the gut microbiome; however, the nature of the relationship between the two has remained largely unknown. To address this issue, the research team, led by Francisco Quintana (Brigham and Women’s Hospital) carried out a genome-wide transcriptional analysis on astrocytes from a mouse model of MS.
The study, published in Nature Medicine, suggests that there is a molecular pathway present in astrocytes that has a role in neuroinflammation. The researchers observed that molecules derived from dietary tryptophan act on this pathway and that a higher concentration of these molecules correlates with lower levels of brain inflammation, which is mediated by astrocytes. Furthermore, Quintana and the team observed decreased levels of the tryptophan-derived molecules in MS patient blood samples.
“For the first time, we’ve been able to identify that food has some sort of remote control over CNS inflammation,” commented 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.”
Quintana explained: “Deficits in the gut flora, deficits in the diet or deficits in the ability to uptake these products from the gut flora or transport them from the gut – any of these may lead to deficits that contribute to disease progression.”
Going forward, the team aims to investigate this pathway and the role that diet may play in neuroinflammation and the progression of MS. They hope that new insight into the pathway may pave the way for new therapeutic targets and identification of biomarkers for the disease.
Sources: Rothhammer V, Mascanfroni I, Bunse L et al. Type I interferons and microbial metabolites of tryptophan modulate astrocyte activity and central nervous system inflammation via the aryl hydrocarbon receptor. Nat. Med. doi:10.1038/nm.4106 (Epub ahead of print) (2016); BWH press release