Copyright Rijana
Growing up with animals reduces the chance of allergies
Regular exposure to farm dust and bacterial particles triggers the production of a protein that protects against the development of allergies and asthma.
This explains why children who grow up on a farm are less likely to develop allergies. The same applies to children who grow up with pets.
A group of Dutch and Belgian researchers published about this in Science.
And so the common wisdom seems to be proven that an overly hygienic environment increases the risk of allergies and
asthma. Researchers from Erasmus MC in Rotterdam, Ghent University and the Flemish Institute for Biotechnology
drew this conclusion after exposing mice to farm dust containing a higher dosage of fungal and bacterial particles than is
normally present in the air.
Farm dust also contains many endotoxins. These are parts of the cell wall of a specific group of bacteria, the Gram-
negative bacteria. Endotoxins contribute to the pathogenic potential of those bacteria.
One group of mice was exposed daily for two weeks to these endotoxins from farm dust and a control group was not.
After two weeks, both groups were exposed to house dust mites, which often cause asthma in humans.
Not a single mouse in the endotoxin group developed an allergy. The mice in the control group did.
The researchers also discovered how this works. Exposure to endotoxins activates the protein A20 in the lung mucosa.
This triggers a response of the immune system that prevents allergic reactions.
As soon as this protein was deactivated in mice that had been exposed to endotoxins, they also developed allergies.
The researchers tested their findings in humans. For this, they used samples of lung tissue from healthy patients and asthma patients. After regular exposure to
endotoxins, there was much less of an inflammatory response in the cells of healthy people than in the cells of asthma patients. The cells of asthma patients
also contained much less of the A20 protein.
In a second control study, exposure to farm dust and allergic reactions were examined in 1,700 children in Bavaria.
The 480 children from a group who grow up on a farm and are therefore regularly exposed to farm dust turned out to be better protected against asthma and
allergies than their peers who do not live on a farm. A small number of children who live on a farm and still develop allergies turned out to have a genetically slightly different variant of the A20 protein that offers less protection.
