Exposure To Bacteria Modulates Immune Response And Decreases Allergy In Farm Children

Findings from a Research Letter in this week’s issue of THE LANCET provide support for the idea that children who grow up on farms have fewer allergies because they are exposed to more microbes than other children.

Farmers’ children are known to be less prone to allergies than children who do not grow up on farms, but the exact reason is not known. Previous work has shown a circumstantial link between exposure to bacteria and reduced allergy; Dr Roger Lauener and colleagues from Zurich University Children’s Hospital, Switzerland, aimed to find out the mechanism behind this possible association.

Exposure of cells to certain bacterial components results in increased expression of the genes that code for receptor proteins such as CD14 and TLR2. These interactions can also modulate the way the innate immune system achieves its goals, pushing it in a direction away from that which causes allergic responses. Lauener and colleagues found significantly higher expression of the CD14 and TLR2 genes in 25 farmers’ children than in 71 children from other backgrounds, providing evidence of a link between exposure to bacteria, modulation of innate immunity, and decreased allergy in children who grow up on farms.

Dr Josef Riedler, one of the co-authors, comments: “Our current findings point towards the mechanisms by which growing up on a farm protects against the development of allergic diseases. It seems that the innate immune system is involved via gene-environment interactions. Finding out more about the precise nature of these interactions between exposure and susceptibility could provide ideas for potential strategies for the prevention of allergy.”