Allergic diseases affect hundreds of millions of children worldwide and continue to increase in prevalence. These rising rates have coincided with social and environmental changes that have had an intergenerational impact on the microbes and their collective genes that make up our microbiota.
You may be familiar with the term atopic march which refers to the typical progression of allergic diseases that often begin early in life. These include atopic dermatitis (eczema), food allergy, allergic rhinitis (hay fever) and asthma.
New research links these allergic diseases to the gut microbiome and identifies a bacterial signature associated with their development. The study “Delayed gut microbiota maturation in the first year of life is a hallmark of pediatric allergic disease” was recently published in the journal Nature Communications.
Established during infancy, a child’s microbiota expands and fluctuates until it reaches a more stable community. Many risk factors for allergic diseases, including mode of delivery, diet, urban living, and antibiotic exposure, also influence early microbiota membership and structure.
While this maturation process usually coincides with the development of healthy immune tolerance, allergic sensitization can emerge in some children during the same period as the microbiota is being established.
In the study, the first to examine all four allergies associated with the atopic march at once, researchers evaluated 1,115 children at age five after analyzing their stool collected during study visits at ages three months and one year.
Roughly half the children (523) showed no evidence of allergy at any time, while the others (592) were diagnosed with one or more allergic disorders by a specialist.
They found that delayed infant microbiota maturation was shared across each five-year allergic diagnosis compared to those with no history of allergic sensitization and that this delay in microbiota maturation preceded the diagnosis of allergic disease. The bacterial signature is a hallmark of dysbiosis — an imbalanced gut microbiota — that likely resulted in a compromised intestinal lining and an elevated inflammatory response within the gut.
Said Courtney Hoskinson, a PhD candidate at UBC and first author on the paper:
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. We found a common breakdown in these mechanisms in babies prior to the development of allergies.
Said Dr Stuart Turvey, professor of pediatrics at UBC and co-senior author of the study:
There are a lot of potential insights from this robust analysis. 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.
Research can now turn to leverage the findings to help find treatments that correct an imbalanced gut microbiota and could potentially prevent allergies from developing.
Said Dr Turvey:
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.
