Deca who live on rural farms suffer from hay fever, asthma and neurodermatitis much less often than children who grow up in the city. The reason for this is now revealed by a new study by a research group from Munich.
The research team was successful with bacteria that are part of the gut microbiome collar for the first time to follow the entire biological chain of action of the so-called "farming effect", writes DW.
Two thirds of the protective effect in asthma
During the cow's digestive process, bacteria produce metabolic products and release them into the air in the barn. When humans inhale these substances, immune receptors on airway cells in the lungs react.
The study was led by Markus Ege, who works at the Children's Hospital of the LMU University Clinic (and at the Institute for Asthma and Allergy Prevention in Munich): "Those receptors have multiple functions, including in the immune system. They probably prevent an excessive inflammatory response."
Those processes and the role of the newly discovered bacteria in the "village effect" were previously unknown.
According to the study, these bacteria are responsible for about two-thirds of the protective effect in allergic asthma and about half of that protective effect in hay fever and neurodermatitis. However, children's genes also play a certain role, i.e. family tendency to allergies.
Identifying bacteria using cowshed dust
The "farmhouse effect" was observed by allergy experts in the field of epidemiology in an earlier, large-scale international study.
Twenty years ago, allergy researchers took nasal swabs from more than a thousand children in Europe.
For their study, the Munich experts additionally collected data from 47 children who grew up on rural farms.
They took dust samples from the mattresses, floors and window sills of traditional cowsheds. Study leader Ege explains: "We were able to show that the farm effect reduced the risk of allergic asthma by half, but we didn't know why. Thanks to the new stepwise elimination process we were now able to show which bacteria were crucial."
Bioinformatics and gene analysis
With the help of bioinformatics and modern methods of gene analysis, the unification and evaluation of all data has now succeeded, explains Ege:
"We found two bacteria that originate from the microbiome in the cow's intestines and that are crucial for the protective effect. However, the names or types of bacteria are less important to us, and more their function. Because only their metabolic products affect humans."
In the barn, children come into contact with a large number of microorganisms. This variety is considered crucial for the child's immune system to "train" and learn to distinguish dangerous disease-causing agents from harmless allergens.
The microbiome in the human intestines and on the skin is crucial. Apart from bacteria, it also includes fungi, viruses and bacteriophages. For the prevention of allergies, this variety, as well as the concept of the first 1.000 days, play an important role.
Namely, the immune system is formed in early childhood. Experts therefore recommend that mothers stay in nature as often as possible during pregnancy, and later with a baby or a small child.
The new findings should be verified in the laboratory to clarify the molecular and cellular mechanisms of the farm effect. The long-term goal is to develop new forms of prevention or drugs to train the immune system, without the need for children to stay in the cowshed.
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