Childhood Allergies May Originate from Gut Bacteria

A new study identifies specific gut microbiome features and early life influences that are associated with children developing four of the most common allergies. Researchers say their findings, published in Nature Communications, could lead to new methods of predicting and preventing childhood allergies.

According to the study’s co-author, Stuart Turvey, MBBS, DPhil, FRCPC, professor in the department of pediatrics at the University of British Columbia (UBC) and an investigator at British Columbia Children’s Hospital Research Institute, in Vancouver, Canada, hospitals are seeing an increase in children and families seeking emergency care due to allergies. For this study, Turvey and his colleagues sought to better understand why these allergies develop and determine whether they have a common origin linked to the infant gut microbiota composition.

"Hundreds of millions of children worldwide suffer from allergies, including one in three children in Canada, and it's important to understand why this is happening and how it can be prevented,” said Turvey, who conducted the investigation in his lab, Turvey Lab.

For the investigation, researchers analyzed clinical assessments from 1,115 children tracked from birth to age five. Around half of the children had no history of allergies, while the other half were diagnosed with one or more allergic disorders by an expert physician. Researchers focused on the four most common allergies: eczema, asthma, food allergy, and/or hay fever.

"These are technically different diagnoses, each with their own list of symptoms, so most researchers tend to study them individually," said Charisse Petersen, PhD, co-senior author on the paper and postdoctoral fellow in the Turvey lab. "But when you look at what is going wrong at a cellular level, they actually have a lot in common."

Researchers evaluated the children’s microbiomes from stool samples collected at clinical visits at three months and one year of age. The stool samples revealed a bacterial signature associated with children developing any of the four allergies by age five. According to the study, the bacterial signature found is a hallmark of dysbiosis, which is likely to lead to a compromised intestinal lining as well as an elevated inflammatory response within the gut.

"Typically, our bodies tolerate the millions of bacteria living in our guts because they do so many good things for our health. Some of the ways we tolerate them are by keeping a strong barrier between them and our immune cells and by limiting inflammatory signals that would call those immune cells into action," said Courtney Hoskinson, a PhD candidate at UBC and first author on the paper. "We found a common breakdown in these mechanisms in babies prior to the development of allergies."

According to Turvey, the data also suggested that factors such as antibiotic usage in the first year of life are more likely to result in later allergic disorders, while breastfeeding for the first six months appeared protective. In the future, Turvey hopes to leverage these findings to inform treatments for correcting an imbalanced microbiota.

"Developing therapies that change these interactions during infancy may, therefore prevent the development of all sorts of allergic diseases in childhood, which often last a lifetime," said Turvey.