A new study has found that four major childhood allergies share a common feature: an imbalance of gut bacteria during infancy. It’s hoped that the findings will inform treatments that correct the gut microbiome in children, potentially preventing lifelong allergic diseases.
Millions of people worldwide are affected by allergies. And, like so many health conditions recently, they’ve been linked to gut health and the gut microbiome. Given that the microbiome and an infant’s immune system mature in parallel, a new study has investigated the connection between the two.
Researchers from the University of British Columbia and the BC Children’s Hospital, Canada, looked at the role that gut bacteria and early-life influences played in developing four major childhood allergies: eczema, asthma, food allergy and hay fever.
“We’re seeing more and more children and families seeking help at the emergency department due to allergies,” said Stuart Turvey, corresponding author of the study. “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.”
Although the four allergy types have their own symptoms, the researchers wanted to see whether they had a common origin that was linked to the composition of bacteria in the gut.
“These are technically different diagnoses, each with their own list of symptoms, so most researchers tend to study them individually,” said Charisse Petersen, one of the study’s co-authors. “But when you look at what is going wrong at a cellular level, they actually have a lot in common.”
The researchers tracked 1,115 children from birth to age five. Of the children, 523 children were defined as “healthy” (that is, no evidence or history of allergies), and 592 had been diagnosed by an expert physician at the five-year scheduled visit with one or more allergic disorders (e.g., atopic dermatitis, asthma, allergic rhinitis, and food allergy). The children’s microbiomes were analyzed from stool samples collected at three months and one year of age.
The stool samples revealed a common bacterial ‘signature’ associated with the children who’d developed any of the four allergies by age five, indicating an imbalanced gut microbiota or dysbiosis that likely resulted in a compromised intestinal lining and elevated inflammatory response in the gut.
“Typically, our bodies tolerate the millions of bacteria living in our guts because they do so many good things for our health,” said Courtney Hoskinson, the study’s lead author. “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. We found a common breakdown in these mechanisms in babies prior to the development of allergies.”
The researchers also examined whether factors such as antibiotic use or breastfeeding impacted the microbiota in the children and affected whether they developed allergies.
“There are a lot of potential insights from this robust analysis,” Turvey said. “From these data, we can see 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 is protective. This was universal to all the allergic disorders we studied.”
It’s hoped that the study’s findings will inform treatments to correct gut dysbiosis, potentially preventing allergies from developing.
“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.
The study was published in the journal Nature Communications.
Source: University of British Columbia