Exposure to endotoxins prevented mice from developing asthma, which researchers said is similar to what happens when children are exposed to them. Photo by Andrey Orletsky/Shutterstock
WASHINGTON, Sept. 4 (UPI) -- Bacteria in farm dust was found in a recent study to trigger an inflammatory response in mice that protected them from developing asthma.
Researchers said the study lends credence to longtime concerns in the medical community about the anti-germ compulsion to over-cleanliness that has eliminated exposure to microorganisms in the environment, which help teach children's immune system to protect their bodies.
"At this point, we have revealed an actual link between farm dust and protection against asthma and allergies," Bart Lambrecht, a professor of pulmonary medicine at Ghent University, told The Guardian. "We did this by exposing mice to farm dust extract from Germany and Switzerland. These tests revealed that the mice were fully protected against house dust mite allergy, the most common cause for allergies in humans."
Researchers at Ghent, as well as Flanders Institute for Biotechnology in Belgium, tested the effects of microbes from the farms by injecting them into the noses of mice every other day for two weeks. They found the exposure to the microbes, called endotoxins, protected the mice from later developing asthma.
In mice exposed to the endotoxins, epithelial cells in the lungs made fewer proinflammatory molecules, called cytokines, when the mice encountered dust mites. The mice also had fewer dendritic cells in their lungs, which respond to cytokines.
An enzyme in the epithelial cells called A20 also resulted in dampening the inflammatory responses -- something that did not happen in mice that lacked the gene to produce A20.
When examining human bronchial samples from healthy people, researchers found exposure to endotoxins had the same effect as it did in the mice. Researchers also found that, among 500 farm children regularly exposed to endotoxins, those genetically predisposed for lower A20 activity were more likely to develop asthma.
The researchers posit their study reinforces something called the hygiene hypothesis, which suggests the longtime purging of childhood, and adult, exposure to germs and dirt is making people more susceptible to allergies and sickness.
While they are hopeful the new discovery will lead to treatments to prevent allergies, the researchers endorse ideas that get children outside and closer to endotoxins and germs for their protective benefits.
"In Holland and in Germany, there's a lot of farms who are now organizing daycare centers," Lambrecht told The Verge. "It's a crazy idea, but it's happening as we speak in Western Europe; this study shows that we shouldn't be afraid to do that -- to send our kids to farms for daycare."
The study is published in the journal Science.