The old-fashioned ways of the Amish are helping researchers make new discoveries about the origins of asthma.
By studying the blood, genes and environmental dust of 30 Amish children from traditional farming families in Indiana, scientists were able to zero in on the innate immune system as a key player in thwarting asthma and the allergic reactions that can trigger it. Their findings appeared in Thursday’s edition of the New England Journal of Medicine.
Experts have long recognized that exposure to farm animals — and the microbes associated with them — protects children from asthma. But exactly how and why this happens remained something of a mystery.
Amish children seemed to hold important clues. For some reason, they are less susceptible to asthma than other kids. Nationwide, 13.5 percent of U.S. children have been diagnosed with asthma, and 8.6 percent still have it, according to the Centers for Disease Control and Prevention. But the prevalence of asthma among Amish youths is only 5.2 percent.
To understand the factors behind this discrepancy, researchers recruited 30 Amish schoolchildren between the ages of 7 and 14. The kids provided blood samples so the researchers could examine their immune system cells, and their parents completed questionnaires about their child’s asthma symptoms.
The scientists also visited 10 of the children’s homes and collected dust samples.
The team reported that the Amish kids’ blood samples contained more neutrophils than other samples. Neutrophils are immune system cells that are among the first to respond when an infection unleashes harmful microorganisms.
The blood of Amish children also contained lower levels of eosinophils, another type of immune system cell that contributes to inflammation that can fuel allergies.
When the researchers examined the gene expression of these cells, they saw that genes involved in innate immunity were more active in the Amish kids.