A “leaky gut” might increase the severity of food allergies, according to new research conducted in mice and published in The Journal of Immunology. The researchers found that changes to the gut microbiome in mice were linked to increased intestinal permeability (leaky gut), and an increase in food allergy severity.
Intestinal permeability describes how the intestines are meant to move water and nutrients from our food into our bloodstream. Increased permeability, sometimes called “leaky gut”, describes a condition in which damage to the gut lining allows partially digested food, toxins, and/or germs to pass into the bloodstream.
The gut microbiome—the trillions of bacteria living in your gut—directly regulates this barrier, meaning microbiome imbalances can be a primary driver of gut leakage.
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In this study, the researchers used two groups of mice that were known to have differences in their gut microbiomes. When a food allergy was induced in the mice, one group developed mild allergic reactions (less diarrhea), while the other had more severe reactions. The mice that had more severe diarrhea were also known to have increased intestinal permeability, or “leaky gut”.
Immune cells
In mice with more severe food allergies, the researchers also observed an increase in immune cells that cause allergic reactions, Th2 cells, and a decrease in food-allergy-specific immune cells that turn off immune responses, Treg cells. Th2 cells are the immune cells that cause anaphylaxis in people with food allergies.
Interestingly, when the researchers housed the mice from the two groups together, they found that mice with milder food allergies developed more severe symptoms. Further tests uncovered that the gut microbiome of the mice with milder allergic reactions shifted to be more like that of the group with severe reactions. They also reported increased intestinal permeability and a change in the balance of immune cells involved in the food allergy response, suggesting that “leaky gut” and the gut microbiome are linked to how the immune system responds to a food allergy.
Gut microbes
“Essentially, we saw that food-allergy-specific immune cells were impacted by gut microbes, which affected the food allergy itself,” said Dr. Alexa Weingarden, Assistant Professor in Gastroenterology, Hepatology and Nutrition at the University of Minnesota School of Medicine, and lead author of the study.
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“Understanding how these food-allergy-specific immune cells change in response to different conditions, like the microbes in the gut, can lead to new targets for food allergy treatment,” continued Dr. Weingarden.
“There’s still a lot we don’t know, but these findings open up new avenues for exploring interactions between gut health, immune cells, and allergies. Some questions we hope to answer include, which bacteria are really responsible for the difference in allergic reactions and how does increased gut permeability impact food-allergy-specific immune cells,” said Dr. Weingarden.
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