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Researchers How does the farm protect children from allergies and asthma?
It has been known for some time that farm life protects children from allergies, mainly due to contact with special microbes. However, scientists from the University of Zurich have shown in a recent study that the non-microbial molecules also appear to have a protective effect.
The University of Zurich immunologists found that sialic acid found in farm animals works against inflammation of the lung tissue. This opens up promising new perspectives for allergy prevention, the scientists report. The caressing of cat and cow as well as the sip of milk directly from the farm have, according to the researchers, not only because of the contact with microbes a preventive effect against allergies. The results of the scientists were published in the journal "Journal of Allergy and Clinical Immunology".
Life on the farm not only protects from allergies and asthma through contact with microbes, even non-microbial molecules have a positive effect. (Image: dietwalther / fotolia.com) Farmer children protected from allergies
The team led by Remo Frei from the Swiss Institute of Allergy and Asthma Research of the University of Zurich, in collaboration with researchers from the Center for Allergy Research and Education (CK-CARE) in Davos and the Children's Hospital St. Gallen, has shown the effect of early childhood contact with farm animals on the Allergy and asthma risk investigated. Contrary to the general trend of increasing allergies and asthma diseases, which has been observed in recent decades, peasant children show a degree of immunity here. "With them, the increase in disease is less dramatic than that of their comrades, who live in the same village but not on a farm"; the scientists report. Overall, around 30 percent of all children are affected by at least one allergy.
Positive effect on the development of the immune system
From previous studies, it was already known that microbes found in farms in greater numbers and higher diversity protect the peasant children from allergies and asthma. According to the researchers, a "not very hygienic environment has a positive effect on the development of the immune system" because it learns to tolerate the actually harmless substances and to show no reaction, as it would be the case with an allergy. The protective effects, however, according to the Zurich researchers, not only on the microbes back.
Certain sialic acid with far-reaching effects
Early childhood contact with animals and also the consumption of animal food seems to affect the inflammatory responses of the immune system via a specific sialic acid - N-glycolylneuraminic acid (Neu5Gc), the researchers report. These are common in vertebrates, as they live on the farm, but lack in the human organism. According to the experts, humans do not produce Neu5Gc due to a genetic mutation. However, sialic acid can be taken up via the animal contact or also via the food of animal foods and incorporated into the own glycoproteins.
Data from over a thousand children compared
"Contact with Neu5Gc triggers an antibody reaction in humans that can be used as a measure of contact with Neu5Gc, ie for contact with farm animals," explain the scientists. The research team has also measured the levels of Neu5Gc antibodies in serum samples from children from two large epidemiological studies (PARSIFAL and PASTURE study) and compared the data of over a thousand children in its current study. The relationship with the disease risk for asthma was also evaluated. "Farmer's children had much more antibodies against Neu5Gc in the blood - and children with more antibodies suffered much less often from asthma," summarizes the study results.
Effect confirmed in the mouse model
The scientists further report that the positive effect of the sialic acid Neu5Gc on the respiratory tract was also confirmed in the mouse model. Nutritionally ingested Neu5Gc molecules would have improved the lung function of the mice and thus reduced the symptoms of asthma. In further steps, researchers sought to understand the mechanism by which Neu5Gc acts on the human immune system. They analyzed various cells of the immune system that play a role in an inflammatory response.
Preventive mechanism decrypted
Investigating the cells, the researchers found that exposure to Neu5Gc does not reduce the immunoglobulins E (the antibodies), which are more likely to be involved in allergic reactions. Rather, an anti-inflammatory reaction of the immune system is triggered. This happens via so-called regulatory T cells, which are more present. "These T cells attenuate immune system reactions and have a strong anti-inflammatory effect," says Frei. According to the researchers, the current research results also open up possibilities to transfer the protective effect of the farm to all children and thus possibly lay the foundation for effective allergy prevention. (Fp)