Background: Children who grow up in a farming environment show lower levels of atopic sensitization, hay fever, and asthma than children of the same age not living in such an environment. A number of investigations provided good evidence that this is due to an early-life contact with cowsheds, farm animals, and/or consumption of products like raw milk. Also, it had been indicated that microorganisms might have an important effect on the development of allergies, and thus the question arose of which farm microbial organisms, their products, or both might induce or influence allergy-protective mechanisms.
Objective: We sought to gain further insight into the potential allergy-protective properties of microbes isolated from the farming environment.
Methods: Of a number of bacterial species identified in cowsheds of farms, 2 were selected, isolated, and characterized, namely Acinetobacter lwoffii F78 and Lactococcus lactis G121. The isolates were investigated with regard to their activation of pattern-recognition receptors, the maturation of human monocyte-derived dendritic cells, the upregulation of inflammatory cytokines, the T(H)1-polarizing Notch ligand expression, and their influence on the allergic phenotype.
Results: It is shown that both bacterial isolates were able to reduce allergic reactions in mice, to activate mammalian cells in vitro, and to induce a T(H)1-polarizing program in dendritic cells.
Conclusion: Our data strongly support the hygiene hypothesis, which states that an environment rich in microbiologic structures, such as a farming environment, might protect against the development of allergies.
Clinical implications: This work provides the first data on a potential application of cowshed bacteria in allergy protection.