Immune System This is how farm life protects against allergies

Immune mechanisms of farm effect identified
Numerous studies have already linked the exaggerated hygiene in everyday life with health disadvantages, in particular the increased risk of autoimmune diseases or allergies was in the foreground. In return, advantages of living in agricultural environments were found, which are attributed to the increased contact with microbial life forms. Scientists at the University Hospital Geneva have now examined the underlying immune mechanisms in a recent study.

Growing up on the farm provides long-lasting protection against allergies, with life in the microbial environment of livestock being crucial to inducing this protective effect, explains the research team around Philippe Eigenmann of the University Hospital Geneva. Which immune mechanisms are responsible for this, however, remains unclear. The researchers have now tried using a mouse model to find out and publish their findings in the journal "Clinical & Experimental Allergy".

Life on the farm protects against allergies and autoimmune diseases. (Image: Kzenon / fotolia.com)

Hygiene as a cause of illness?
Although the transmission of infectious diseases can be minimized by thorough hygiene, the lack of utilization of the immune system also leads to an increased risk of autoimmune diseases and allergies, according to the key message of the so-called hygiene hypothesis. Hay fever, asthma, atopic dermatitis and many other diseases are therefore to be seen in the context of exaggerated hygiene. However, living in an agricultural environment has a protective effect here, as confirmed in the current study.

Studying mouse colonies on the farm and in the lab
The scientists used a mouse model to study the effects of the microbial environment of agricultural life or the immunological changes associated with the protection against allergies. So a mouse colony was bred on a farm with cowshed and a colony in the laboratory at the University Hospital Geneva. The researchers exposed mice from both sites to a contact allergen and observed the response. Blood cells and cell cytokine production were also assessed in both populations, Eigenmann and colleagues report. In addition, the intestinal microbiome has been characterized at various ages.

Reduced susceptibility to allergies
According to the researchers, the mice born on the farm were less susceptible to allergies than mice bred in the laboratory. Also, a transfer of mice from the laboratory on the farm had a positive effect on the susceptibility to allergies. Overall, the farm mice showed an earlier "immune activation with a higher CD4 + T-cell population, in particular CD4 + CD25 + FoxP3- (activated cells)" compared to the laboratory mice, write the Geneva researchers. Also, the cytokine profile of mice on the farm is much different. The differences are strongest within a certain age window between birth and an age of eight weeks. Similarly, microbiome analysis revealed significant differences in the mice from the farm and from the laboratory.

"The agricultural environment requires a strong, allergy-protective IL-22 stimulus and generates activated CD4 + T cells," the scientists report on their analysis of immune mechanisms. Exposure to the agricultural environment also resulted in better protection against contact allergies. To what extent viral causes have an influence, should be clarified in further investigations. (Fp)