A "leaky gut" may increase the severity of food allergies, according to research conducted in mice and published in The Journal of Immunology, as reported on Jul. 31. The study found that alterations in the gut microbiome were associated with increased intestinal permeability and heightened food allergy reactions.
Intestinal permeability refers to how the intestines transfer water and nutrients from food into the bloodstream. Increased permeability, or "leaky gut," occurs when damage to the gut lining allows partially digested food, toxins, or germs to enter the bloodstream. The trillions of bacteria living in the gut—known as the microbiome—directly regulate this barrier, so imbalances can contribute to increased leakage.
Researchers studied two groups of mice with different gut microbiomes. When a food allergy was induced, one group developed mild allergic reactions while the other experienced more severe symptoms such as diarrhea. The group with more severe reactions also had greater intestinal permeability.
The researchers observed that mice with more severe allergies had an increase in Th2 immune cells—which cause allergic reactions—and a decrease in Treg cells that normally turn off immune responses specific to food allergies. Th2 cells are known for causing anaphylaxis during allergic responses.
When both groups were housed together, mice with previously milder symptoms began developing more severe reactions after their microbiomes shifted toward those of their counterparts. These changes included increased intestinal permeability and altered balances of immune cells involved in allergy response.
"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," said Dr. Weingarden. He added, "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."
