Study author Cathryn Nagler.
A common class of gut bacteria has the potential to prevent and even treat food allergies, according to a groundbreaking study published in August in the Proceedings of the National Academy of Sciences.
Using lab mice, a team of scientists from multiple institutions discovered that bacteria from the class Clostridia appeared to prevent the development of peanut allergy. Various bacteria are normally present in the digestive system as part of “the microbiome” – the trillions of micro-organisms that live inside mammals and help the body function properly.
“Clostridia protected mice from becoming sensitized,” Cathryn Nagler, study author and professor at the University of Chicago, told Allergic Living. “Using it therapeutically is the next step.”
The study is generating considerable excitement in the allergy research community and widespread media attention.
To conduct it, the research team altered the natural microbiome development of the mice by either giving them antibiotics early in life or (in another group) by raising them in sterile, microbe-free conditions. Afterward, all mice were sensitized to peanut. Both groups had more markers of peanut allergy when compared to mice with “normal” gut bacteria that underwent the same peanut sensitization process.
The researchers then determined that bacteria from the class Clostridia were responsible for the differences in sensitization. Mice lacking these bacteria had higher levels of peanut protein in their blood, which the researchers note was also tied to the level of sensitization. By introducing Clostridia to either group of mice before peanut sensitization, the peanut sensitization was prevented.
This protective effect was not observed when the mice were given other microbiota, including another common group of gut bacteria known as Bacteroides, highlighting the importance of Clostridia.
Nagler says there appears to be a barrier-protective effect: the bacteria’s presence caused a chain reaction beginning with Clostridia interacting with immune molecules in the intestine, and resulting in far less uptake of peanut protein into the bloodstream. The reduced ability of the molecules to pass through the intestinal barrier into the bloodstream is believed to be behind the observed protective effect.
(Although the problematic bacterium C. difficile is part of the Clostridia class, it is from a separate subgroup and is unrelated to the bacteria used in this study).
The next step is to start assessing how the findings could translate to humans – with the ultimate goal of one day producing a therapy, possibly a probiotic pill containing Clostridia.
“We hope it can be developed as both preventative medicine and treatment,” says Nagler. “We still have a lot to learn and are a long way from clinical trials, but we will keep working hard.”