Background
A person’s gut is home to trillions of bacteria collectively known as the gut microbiome. These tiny microbes are essential partners in good health: they assist in the digestion of certain foods, can produce a variety of nutrients, interact with and help train one’s immune system, and aggressively defend the gut from invading pathogens.
Disruption to the gut’s natural bacterial balance is linked to a number of different disorders, including multiple sclerosis. The signs and symptoms of MS occur when a person’s own immune system attacks myelin in the brain and spinal cord, and emerging evidence is showing that gut bacteria interact with this same immune system on a daily basis. Some gut bacteria can release chemicals that activate immune cells known to play a damaging role in MS, while others produce chemicals that suppress MS-like symptoms in mice. It is easy to see why insights into this possible MS link could prove vital.
To date, our understanding of the microbiome/MS relationship comes predominantly from animal studies, and new studies are translating these observations into humans. A study published in the journal Scientific Reports by Dr. Ashutosh Mangalam and his team from the Mayo Clinic and the University of Iowa set out to explore the differences in the gut microbiome between individuals living with MS and the rest of the population.
Method
Dr. Mangalam and his research team compared the gut microbiome of 31 participants with relapsing remitting MS to 36 age- and gender-matched healthy participants.
All participants provided stool samples for analysis. Samples were analyzed using a highly specialized gene sequencing technique to identify the various bacteria present. This allowed the researchers to develop unique microbiome profiles for each participant. The profiles were used to compare gut bacteria among individuals with MS and healthy participants, as well as between participants with MS that were either symptom-free at the time or had had a relapse within a month of sample collection.
Results
Participants with relapsing remitting MS had a distinct bacterial profile relative to non-MS participants – some types of bacteria were found in much greater numbers in the MS group, while other bacteria were more numerous in non-MS participants.
Within the MS group, the gut microbiome profile differed depending on how active a participants’ disease was at the time of sample collection. Participants with an active form of the disorder had much less diversity in their gut bacteria relative to participants with less active disease.
Comment
The researchers concluded that an imbalance in the gut’s microflora may be one of the missing environmental factors that affects the development and course of MS in those with a genetic predisposition. This area of research is still very much in its infancy, and the authors acknowledge that more work is needed to expand their study to a larger participant group over longer periods of time, and to determine whether a difference in the gut microbiome is a contributor, or consequence, of the disease.
In their discussion, the authors note that lower numbers of certain bacteria in their MS participant group (examples include Prevotella, Parabacteroides, Adlercreutzia, and Erysipelotrichaceae) could predispose an individual to developing MS. These four particular organisms release anti-inflammatory chemicals as part of their metabolic process. Normally, these chemicals help to calm the immune system. The lack of these bacteria could be partly responsible for the abnormal immune response that is a part of MS.
Researchers are beginning to understand and appreciate the role of the gut microbiome in maintaining good health. Insights into the gut microbiome can potentially have a two-fold benefit: 1) building knowledge around environmental factors that determine MS risk, and; 2) informing therapeutic approaches that can shape the composition of the gut microbiome to tone down harmful inflammation. The MS Society-affiliated MS Scientific Research Foundation is funding a collaborative team grant, led by Dr. Helen Tremlett, to explore the relationship between the gut microbiome and MS in children and adolescents to shed more light on this important question; read the MS Update here.
Source
Chen J. et al. (2016) Multiple sclerosis patients have a distinct gut microbiota compared to healthy controls. Scientific Reports. DOI: 10.1038/srep28484.