Changes to bugs in the gut could prevent food allergies

Allergic reactions to food have dramatically increased over the past 10 to 20 years. Dan Peled/AAP

Changing the bacteria in the gut could treat and prevent life-threatening allergies, according to research published in the Proceedings of the National Academy of Sciences (PNAS) journal today.

“These findings are a game changer for understanding how allergies develop,” said Dr Simon Keely, senior lecturer in immunology and microbiology at the University of Newcastle. “The number of hospital admissions due to reactions to food have increased dramatically over the past 10 to 20 years.”

The study authors examined how changes in the trillions of bacteria that normally populate the gastrointestinal tract influence allergic responses to food. They started by inducing peanut sensitivity in mice by giving them antibiotics soon after birth.

Antibiotics disturb the harmony between the bacteria and immune system of the gut, creating an allergic sensitisation to peanuts. They prime the immune system to mistakenly recognise peanuts as a threat.

The researchers then introduced a peanut solution directly into the mice’s gastrointestinal tract through a feeding tube. When the rodents were exposed to this solution, they became sensitive to peanuts.

A group of bacteria called Clostridia was then introduced into the gut of the mice and the researchers found it got rid of the peanut sensitivity. They believe the findings will inform the development of similar approaches for allergy prevention in humans.

Although the research was done in mice, Professor Katie Allen, paediatric gastroenterologist and allergist at Murdoch Childrens Research Institute, said the results were profound for allergy research because they showed proof of concept of the importance of gut bacteria and their interactions with the developing immune system.

Dr Keely said the study demonstrated previously unrecognised pathways by which the immune system interacts with the bacteria in the gut.

“When you disrupt that interaction, you become more susceptible to developing allergy,” he said.

The study underlines how bacteria in the gut and the immune system are intrinsically linked, he said, adding “they regulate each other. If you disturb one, you disturb the other.”

But both Allen and Keely highlighted some of the limitations of the research.

“We can’t say that gut bacteria that are shown to be protective for mice will also be protective for humans but it is an interesting concept nonetheless,” said Professor Allen.

Dr Keely said humans have a much more diverse diet than mice and tended to be exposed to a very broad environment of bacteria, unlike mice, which tend to live in relatively clean cages.

The good news is that this research suggests the potential for modifying gut bacteria in humans as a way of prevention of allergic disease – in particular food sensitisation, Professor Allen added.

Professor Allen said researchers have been looking at many ways of preventing allergy including kick starting the immune system in newborn babies, studying migration changes on human allergies and studies in probiotics.

This current study provides further supportive evidence for the role of gut bacteria in allergy development, she said. The most important thing to take away from it is that there may be group of bugs that will be helpful in protecting against allergic sensitization and therefore also food allergy.