Kids on farms have lower allergy risks, says study

Children growing up on farms have fewer seasonal allergies like hay fever and allergic asthma compared to their urban counterparts, finds a study, adding that breathing in dust from farms seems to stimulate the production of a protein called A20, which limits inflammation in the lungs leading to lower rates of asthma.

Researchers found that exposure to farm dust increases expression of A20 that suppresses the inflammatory immune system by modifying the communication between the lining of the lungs and the immune system.

The findings were presented at the Joint Congress of the British and Dutch Societies for Immunology.

A team, including Martijn Schuijs at the VIB-UGent Inflammation Research Center in Belgium, carried out several experiments to look at this question.

For the experiment, mice were exposed to a low dose of either LPS (a component of the bacterial cell wall that is found in farm dust), farm dust, or a control substance every other day for two weeks.

The mice were then sensitised with house dust mite extracts (HDM), which caused them to mount an allergic response when later confronted with a high dose of HDM.

The study showed that the mice exposed to farm dust or LPS significantly showed lower asthmatic responses to the HDM than controls.

The researchers found that exposure to LPS or farm dust induced A20 expression in mice, which suppresses the inflammatory immune response.

These findings were also valid in human cells, as using cells from the lining of the airways in the lungs taken from patients with mild, severe, or no asthma.

Finally, the researchers examined the relationship between common genetic mutations in the gene encoding A20 (called Tnfaip3), and prevalence of asthma in 1,707 European children aged six to 12.

Children with a mutation that altered one amino acid in the A20 protein showed higher levels of asthma; however, growing up on farms had a protective effect on those with the mutation compared to those that had not been brought up on a farm.

"Breathing in dust from farms seems to stimulate the production of a protein called A20, which limits inflammation in the lungs leading to lower rates of asthma,"

"By targeting the A20 protein in the cells that line the airways, we hope this will lead towards the development of more effective medication for people with allergic asthma.