U of G Study First to Build
Pigs’ Allergy Resistance
Goal is to eventually develop a preventive treatment for human food allergies that could be administered to newborns
BY DEIRDRE HEALEY
Exposing newborns to bacteria could reduce their chances of developing food allergies later in life, say U of G researchers.
In a first-ever study involving pigs, University professor emeritus Bruce Wilkie, Pathobiology, and colleagues were able to build resistance to experimental food allergy by exposing the animals to bacteria when they were just days old.
The goal of the research is to eventually develop a preventive treatment for human food allergies that could be administered to newborns, says Wilkie.
In North America, four per cent of adults and six per cent of children have food allergies.
“Allergies are increasing at an epidemic rate that cannot be due to genetic change,” he says. “It’s probably because today’s newborns and young children are no longer exposed to the bacterial, fungal and viral infectious diseases needed for the development of a balanced immune system. Some environmental exposure is necessary to allow us to have an immune system that works.”
The research is based on the theory that the sanitized environments created by modern health-care and hygiene practices have caused humans to become more susceptible to allergies.
It’s argued that exposure to infectious disease or microbial products at a young age is crucial to triggering a healthy immune response and suppressing the development of an allergic immune response.
To determine whether exposure to bacteria influenced the newborn pigs’ immune response to allergens, Wilkie and researchers Prithy Rupa, Julie Schmied, Melissa Cirinna, Korinne Hamilton and Serene Lai had to first develop a way to make pigs allergic to human foods. Using injections of ovomucoid, a major allergen of eggs, they were able to induce an allergic reaction to egg whites — the second most common food allergy among young children (the first is milk).
For the study, the researchers injected piglets with dead Escherichia coli bacteria during the first week of their life. When they were two and three weeks old, the animals were then injected with the purified ovomucoid, the protein that induced hypersensitivity reactions to egg whites.
Once the pigs were just over a month old, they were fed egg whites and monitored to see if they became allergic. Within an hour, a majority of the piglets that were not exposed to the E. coli began to show signs of an allergic reaction similar to a human food allergy, including skin rash, vomiting and diarrhea.
“The pigs exposed to E. coli had significantly fewer signs of allergy,” says Wilkie.
This research is the first to show that exposure to bacteria reduces the likelihood of allergies in pigs. These results may better reflect a human response compared with previous research conducted with mice, because pigs are biologically more similar to humans, he says.
Pigs are also outbred, so their genetic makeup varies even within litters and can mimic the diversity in allergy susceptibility and response to treatments that occurs in the human population, he adds.
The next step is to investigate for similar anti-allergic effects with probiotic bacteria that can be ingested rather than injected.
“Parents aren’t going to want to have babies receive injections when they’re newborns,” says Wilkie. “If we can develop a way the bacteria can be ingested and have the same effect, we will be closer to creating an anti- allergic treatment for humans and animals."
This research appears in a special issue of the journal Veterinary Immunology and Immunopathology.