According to the Mayo Clinic, 6 to 8 percent of children under age 3 and 3 percent of adults have some type of food allergy. Allergy-causing foods can trigger symptoms ranging from mild to severe to even life-threatening. Researchers at the University of Chicago Medicine (UCM) recently made a breakthrough that offers hope for people with food allergies–the discovery of a common gut bacteria found to protect against food allergens in mice.
The cause of food allergies remains unknown, but one prevalent theory is that diet, modern hygiene and use of antibiotics and antimicrobials may disturb the natural bacterial composition in the body. The UCM researchers decided to test this theory.
Two groups of mice–one germ-free group raised in a sterile environment, and one group that was given antibiotics as newborns–were exposed to peanut allergens. In both groups, the researchers observed significantly higher levels of antibodies against peanut allergens than in mice with normal gut bacteria. The researchers also discovered that reintroducing Clostridia bacteria back into the mice reversed their food allergen sensitivity.
“We’ve identified a bacterial population that protects against food allergen sensitization,” says Cathryn Nagler, PhD, Bunning Food Allergy Professor at the University of Chicago and senior author of the study. “The first step in getting sensitized to a food allergen is for it to get into your blood and be presented to your immune system. The presence of these bacteria regulates that process.”
Genetic study and analysis showed that Clostridia boosts production of a molecule that decreases permeability of the intestinal lining called interleukin-22 (IL-22). Mice that were given antibiotics were given IL-22 or colonized with Clostridia, then exposed to peanut allergens. Both groups showed reduced allergen levels. When given antibodies that neutralize the IL-22, the mice showed increased allergen levels. This was an indicator that Clostridia-induced IL-22 protects the bloodstream from allergens.
These findings may not mean freedom from food allergies for everyone who has to deal with them, according to Nagler, because the various factors that contribute to food allergies is still not clearly understood. Nagler still believes, however, that the discovery of Clostridia will pave the way for the development of probiotic therapies to prevent and treat food allergies.
“It’s exciting because we know what the bacteria are; we have a way to intervene,” she says. “There are of course no guarantees, but this is absolutely testable as a therapeutic against a disease for which there’s nothing. As a mom, I can imagine how frightening it must be to worry every time your child takes a bite of food.”
By Ramie A Tritt, MD, President, Atlanta ENT
