Around the world, millions of individuals suffer from allergic diseases. Changes in the gut microbiome, or the bacteria and their genes within the gastrointestinal tract, have been linked to increased prevalence. The development of the baby’s immune system and gut microbiota take place concurrently; as a result, the microbiome’s conformation may influence whether the infant develops tolerant immune programming.
A new study by the University of British Columbia and BC Children’s Hospital suggests that several major childhood allergies may all stem from the community of bacteria living in our gut.
The study identifies gut microbiome features and early life influences linked with children developing four common allergies — eczema, asthma, food allergy, and/or hay fever. This is one of the first studies to look at four different pediatric allergies in children in school. Scientists were interested in whether these allergy disorders might share a common origin associated with the makeup of the infant gut microbiota, even though each has distinct symptoms.
Dr. Charisse Petersen, the co-senior author, said, “These are technically different diagnoses, each with their list of symptoms, so most researchers tend to study them individually. But they have much in common when you look at what is going wrong at a cellular level.”
Researchers looked at 1,115 children’s clinical evaluations who were followed from birth to age five for the study. A qualified physician identified one or more allergic disorders in more than half of the children (592), while about half of the children (523) had no history of allergies at any time. The researchers assessed the children’s microbiomes from stool samples taken during clinical visits at three months and one year of age.
The bacterial signature seen in the stool samples was linked to the children getting any of the four allergies by the time they turned five. The bacterial signature is a symptom of dysbiosis, or an unbalanced microbiota in the gut, which most likely leads to a damaged intestinal lining and an aggravated inflammatory response.
Courtney Hoskinson, a Ph.D. candidate at UBC and first author of the paper, said, “Typically, our bodies tolerate the millions of bacteria living in our guts because they do so many good things for our health. Some ways we tolerate them are by keeping a strong barrier between them and our immune cells and limiting inflammatory signals that would call those immune cells into action. We found a common breakdown in these mechanisms in babies before developing allergies.”
The nutrition, how we are born, where we live, and our exposure to antibiotics are just a few variables that might affect the microbiota in the infant’s stomach. For instance, although breastfeeding tends to replace and provide the essential food for bacteria in the infant’s intestines, antibiotics may wipe out sensitive bacteria. Scientists examined how these influences affected the balance of gut microbiota and the development of allergies.
Dr. Turvey said, “There are a lot of potential insights from this robust analysis. From these data, we can see that antibiotic usage in the first year of life is 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.”
The researchers will now use the findings to guide the development of therapies that address an unbalanced gut microbiota and may delay the onset of allergies. The findings could lead to methods of predicting whether a child will develop allergies and ways to prevent them from developing at all.