Pilot study takes a first step towards understanding how bacteria in the gut influence childhood MS
The bacteria living in our gut – our gut’s microbiome – and our immune system are inextricably linked: the microbiome can influence the immune system, while the immune system keeps the microbiome in check. Growing evidence suggests that, in some cases, shifts in the composition or number of bacteria in the gut can drive a fundamental change in immune cell behaviour, leading to inflammation and, for some individuals, MS.
Children are thought to be uniquely vulnerable, as the microbiome plays a core role in the proper development of the child’s immune system. To explore the possible relationship between gut bacteria and pediatric MS, Dr. Helen Tremlett (University of British Columbia) conducted a small, exploratory pilot study. This early work would lead to a partnership with the Canadian Pediatric Demyelinating Disease Network and the United States Network of Pediatric MS Centers, a much larger collaborative effort funded by the MS Scientific Research Foundation to unravel the interplay between microbiome and childhood MS. Dr. Tremlett’s pilot study that formed the foundation for the subsequent collaborative project was published in the Journal of the Neurological Sciences.
Stool samples were collected from 17 children and adolescents with pediatric MS. All participants were considered to be in the early stages of the disorder – less than 2 years since onset of symptoms.
Bacterial DNA was extracted and analyzed from participant stool samples, giving the research team a snapshot of the gut microbiome. Following sample collection, participants were monitored for an average of 20 months for signs of relapse. By comparing the bacterial population in participants who relapsed compared those who did not, the researchers could establish a link between certain bacteria and the risk of relapse.
The team linked the absence of one particular species of gut microbe – Fusobacteria – to an increased risk of relapse. Over the course of the study, participants lacking Fusobacteria were 3.2 times more likely to suffer an earlier relapse than individuals who tested positive for the bacteria.
This pilot project was an important first step in establishing a relationship between the absence of specific bacteria and the risk of relapse in pediatric MS. The research team noted how the presence of the Fusobacteria group of gut microbes has been linked to both positive and negative health outcomes – in the latter case with colorectal cancer, a disease that occurs less frequently in people with MS. The researchers suggested additional analyses would be warranted to identify the precise species of Fusobacteria associated with the reduced risk of relapse and uncover the molecular mechanisms at play.
Dr. Tremlett’s findings also tie into a larger narrative, one where abnormal changes in the gut microbiome act not only as potential triggers and drivers for pediatric MS, but for all individuals who are at a higher risk of developing MS. Dr. Tremlett’s work, along with scientific collaborators from the Canadian Pediatric Demyelinating Disease Network and the US Network of Pediatric MS Centers, will continue to answer questions fundamental to our understanding of how gut bacteria alter immune cell behaviour and possibly initiate or worsen MS symptoms.
Tremlett H et al. (2016) Gut microbiota composition and relapse risk in pediatric MS: A pilot study. Journal of the Neurological Sciences. 363: 153-157.