Defeating food allergies with gastrointestinal microbiota

Food allergies can be caused by the absence of certain intestinal bacteria. Current study results show that the replacement of these intestinal bacteria could make a decisive contribution to the treatment of allergies.

Immunization as an option through intestinal microbiota transplantation

Food allergies can be caused by the absence of certain intestinal bacteria. Current study results show that the replacement of these intestinal bacteria could make a decisive contribution to the treatment of allergies.

Researchers from the Boston Children's Hospital and Brigham & Women's Hospital (BWH) found that babies and children with food allergies lack certain intestinal bacteria. When the research team administered the missing bacteria to mice, the animals were protected from allergies by microbes.

The interactions between mouse cells and bacteria were recorded by the researchers. Conclusions on the relationship between intestinal bacteria and food allergies were already drawn in previous studies, but the current study analyzed the interactions at the cellular level for the first time.

Dr. Lynn Bry, a co-author of the study, says: "We have been able to identify cultivable bacteria of human origin that reverse the polarity of the immune system to develop tolerance to food allergies". The study thus shows a new way to treat food allergies with beneficial bacteria that trigger a change in the immune system.

In addition, this method could make it possible to treat all food allergies in one strategy, rather than targeting reach food allergy individually. Dr. Bry notes: "This means major changes for our methods for developing food allergies’ treatments."

Transplantation of stool samples into mice

The researchers began the study by collecting stool samples every few months from babies and children, 56 of whom had food allergies and 98 of whom were allergy-free. The results showed what previous studies have shown: the intestinal bacteria of the tested groups of children differed.

Since these results raised the question of what conclusions could be drawn for food allergies, the research team transplanted samples from the test groups into mice allergic to eggs. They found that the mice containing intestinal samples from allergy-free children were less allergic to eggs than the second test group.

The researchers then used computer technology to detect differences between the intestinal bacteria samples and were able to derive individual bacterial species from them.

After repeated testing of the bacteria on mice, the team developed two groups of microbes. These contained five to six intestinal bacteria of the genera Clostridiales or Bacteroidetes. The bacterial groups kept the mice immune to egg allergy. However, the use of other bacterial species did not provide protection against allergies.

Bacteria changed the T-cells

In the following step, the researchers discussed the processes behind these effects at the cellular level. They observed the immune reactions of humans and mice. They found that the beneficial intestinal bacteria targeted two immune pathways and released regulatory T-cells into the immune system. The bacteria altered the state of the T-cells in such a way that no strong immune reactions to the proteins from chicken eggs were induced.

However, the scientists point out that the results of their study are promising, but so far only apply to mice. However, some of the researchers are currently setting up a clinical trial for adults at Boston Children's Hospital. These will be used to test a fecal transplant for the treatment of peanut allergies.

In addition, some private companies are producing various bacterial composites for clinical trials. At the current pace, there is a possibility that new drugs will be available in about five years.

"It seems that the ability to see the detailed course of interaction between microbes and human cells opens up the possibility of a better therapeutic and diagnostic approach to disease," notes Dr. Bry. "As far as food allergies are concerned, we now have promising remedies that we will soon be able to use for patient care".

Microbiota therapy acts via a regulatory T cell MyD88/RORγt pathway to suppress food allergy. In: Nature Medicin (2019). 24. Juni 2019
Azza Abdel-Gadir, Emmanuel Stephen-Victor, Georg K. Gerber, Magali Noval Rivas, Sen Wang, Hani Harb, Leighanne Wang, Ning Li, Elena Crestani, Sara Spielman, William Secor, Heather Biehl, Nicholas Dibendetto, Xiaoxi Dong, Dale T. Umetsu, Lynn Bry, Rima Rachid & Talal A. Chatila