Millions of people around the world are affected by allergies, which can lead to life-threatening complications. The prevalence of allergies is also thought to be increasing. A growing body of evidence has linked the development of allergies to disruptions in the gut microbiome, the community of microbes in our gastrointestinal tract. Research has noted that childhood allergies have also been increasing in the context of social and environmental changes that are altering huamn gut microbes.
A new study has evaluated the development of four different allergic diseases that can begin to arise in children: asthma, eczema, food allergies, and hay fever. This work identified gut microbiome characteristics that are linked to an increased risk of these conditions in children. The study suggested that these allergies may be arising due to a common mechanism, rooted in the gut microbiome. The findings have been reported in Nature Communications.
This work may help scientists develop tools to predict which children are most likely to develop allergies, and potentially prevent them.
"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 co-senior study author Dr. Stuart Turvey, professor at University of British Columbia (UBC) and an investigator at BC Children's Hospital Research Institute.
Since these four allergic conditions are different and cause different symptoms, they tend to be investigated in isolation. "But when you look at what is going wrong at a cellular level, they actually have a lot in common," noted co-senior study author Dr. Charisse Petersen, a postdoctoral fellow in the Turvey lab.
In this work, the investigators assessed the health data of 1,115 children who were followed from birth to age five. Just under half of these study participants, or 523 kids, did not have any allergy diagnosis through the course of the study; just over half, or 592 kids, had been diagnosed with one or more allergic disorders by a physician. With stool samples collected when the children were three months and one year old, the researchers also ascertained the compositions of their gut microbiomes.
This work showed that kids who received a diagnosis of one of the four allergic conditions by age five also carried a certain gut bacterial signature, which indicated dysbiosis, or imbalances in the gut microbiome. The researchers suggested that dysbiosis is causing leakage in the gut lining, which leads to inflammation.
There are many influences on the gut microbiome, including where people live, what they eat and whether or not they've taken antibiotics. This study indicated that antibiotic exposure in the first year of life increases the risk of the allergic disorders the research focused on, while breastfeeding helps protect against them.
"This was universal to all the allergic disorders we studied," said Turvey.
While more research will be needed, these results could help scientists develop tests that can show who might get an allergy, or how to prevent them.
Sources: University of British Columbia, Nature Communications
