Editor's Note: While onsite at the Joint 2014 Americas Committee for Treatment and Research in Multiple Sclerosis/European Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS/ECTRIMS) conference in Boston, Massachusetts, Medscape spoke with Sushrut Jangi, MD, of Brigham and Women's Hospital, about the possible link between our gastrointestinal microbiome and multiple sclerosis (MS).
Medscape: Your study looked at the potential relationship between gastrointestinal flora and MS. What were the objectives of your study?
Dr Jangi: In many autoimmune diseases there has been a lot of recent interest in trying to determine how what we eat, how the kind of bacteria that live in our gut, might influence the immune system. Eighty percent of the immune system is in the gut and is probably shaped by what grows in the gut. For example, in rheumatoid arthritis and inflammatory bowel disease, we've seen that the gut microbiome probably makes a difference and alters the expression of those diseases.
We've also seen that when the gut flora in mice are changed, it affects whether they acquire the MS-like disease experimental autoimmune encephalomyelitis (EAE). EAE is similar to MS in that when you give certain immunogenic compounds to mice, they develop a disease that looks very similar to MS. They get demyelination and disrupted nerve conduction, leading to deficits similar to those seen in MS. This model has allowed us to investigate how the pathogenesis of MS works.
So, given the work in mice with EAE and the fact that there was no study looking at this relationship in humans, we wanted to determine what the constituents of the gut microbiome are in MS patients compared with non-MS patients. We studied 105 patients and recently expanded our cohort to 250.
Medscape: And was there a difference?
Dr Jangi: The preliminary data show that there are at least a couple of different genera of bacteria that are different in the gut of MS patients compared with healthy controls. We found that a bug called Methanobrevibacteriaceae is enriched in the gut of MS patients and seems to have immunoproliferative properties that drive inflammation. We also found that the population of Butyricimonas bacteria is low in MS patients compared with healthy controls. This is an interesting result because these bacteria produce butyrate, which is thought to be immunosuppressive, but we do need to repeat this study in a larger cohort.
So it seems that our work initially supports the idea that the gut in MS patients contains bugs that drive inflammation and are low in the types of bacteria that control inflammation. This is consistent with work in rheumatoid arthritis and inflammatory bowel disease.
Medscape: Would you go so far as to say that gut flora might actually cause MS?
Dr Jangi: It's very hard to say that at this point, but there is a correlation there. I'd like to think that it's related to the cause, because that would suggest that we might be able to control the disease either by changing diet or prescribing antibiotics or probiotics, or even by doing something more dramatic like fecal transplantation.
This also mirrors the idea that MS is a disease of the western world. If you go to countries like India and parts of Asia, where diets are far more vegetarian, you don't really see MS. However, when these people come to the United States and adopt a more westernized diet, the incidence of the disease goes up. I think this is an exciting premise but it's still too early to say anything about the causality.
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Cite this: Multiple Sclerosis and the Microbiome: What's the Connection? - Medscape - Oct 01, 2014.