Researchers are deciphering non-microbial protective mechanisms in farm life
It has been known for some time that life on the farm protects children from allergies, which is mainly attributed to contact with special microbes. However, scientists from the University of Zurich have shown in a recent study that the non-microbial molecules also apparently have a protective effect.
The immunologists at the University of Zurich found that a 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 stroking of cats and cows and the sip of milk directly from the farm have a preventive effect against allergies not only because of the contact with microbes, according to the researchers. The results of the scientists were published in the journal "Journal of Allergy and Clinical Immunology".
Farmers' children protected from allergies
The team led by Remo Frei from the Swiss Institute for Allergy and Asthma Research at the University of Zurich, in collaboration with researchers from the Center for Allergy Research and Education (CK-CARE) in Davos and the St. Gallen Children's Hospital, has the effect of early childhood contact with farm animals Allergy and asthma risk examined. Because contrary to the general trend of increasing allergies and asthma diseases, which has been observed in the past decades, farmers' children show a certain immunity here. "For them, the increase in diseases is less dramatic than for 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
It was already known from previous studies that microbes, which are found in large numbers and in greater diversity on farms, protect farm 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 harmless substances and not to show a reaction, as would be the case with an allergy. According to the Zurich researchers, the protective effects are not only due to the microbes.
Certain sialic acid with far-reaching effects
The early childhood contact with animals and the consumption of animal foods seem to influence the inflammatory reactions of the immune system via a certain sialic acid - N-glycolylneuraminic acid (Neu5Gc) - the researchers report. This is common in vertebrates as they live on the farm, but is absent 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 and incorporated into one's own glycoproteins through animal contact or through eating animal food.
Comparing data from over a thousand children
"Contact with Neu5Gc triggers an antibody reaction in humans, which can serve as a measure of contact with Neu5Gc, ie for contact with farm animals," the scientists explain. In their current study, the research team also measured the concentrations of Neu5Gc antibodies in children's serum samples from two large epidemiological studies (PARSIFAL and PASTURE studies) and compared the data from over a thousand children. The connection with the risk of developing asthma was also evaluated: "Farming children had a lot more antibodies against Neu5Gc in the blood - and children with more antibodies suffered a lot less from asthma," summarizes the study leader.
Effect in the mouse model confirmed
The scientists also report that the positive effect of sialic acid Neu5Gc on the respiratory tract was also confirmed in the mouse model. Neu5Gc molecules ingested through food would have improved the lung function of the mice and thus reduced the symptoms of asthma. In further steps, the researchers tried 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
When examining the cells, the researchers found that contact with Neu5Gc does not reduce immunoglobulins E (the antibodies), which are more common in allergic reactions. Instead, an anti-inflammatory reaction of the immune system is triggered, which is done via so-called regulatory T cells, which are more strongly present. "These T cells dampen wrong reactions of the immune system and are highly anti-inflammatory," says Frei. According to the researchers, the current research results also open up opportunities to transfer the protective effect of the farm to all children and thus possibly lay the foundation for effective allergy prevention. (fp)