Why the Amish could hold the key to curing asthma and allergies
INDIANAPOLIS — For more than a decade, researchers have known that growing up on a farm somehow protects people from developing asthma and allergies. But they did not fully understand what it was about farm life that conferred this protection.
Now, thanks to a team of doctors, including one from St. Vincent Health, and two farming communities – Indiana’s Amish and South Dakota’s Hutterites – scientists have a better sense of how that protection works.
In a study published in this week’s New England Journal of Medicine, the authors report that microbes found in dust in Amish homes help teach the immune system not to respond to potential allergens with an allergic asthma reaction.
“This gives us the first insight into whether there are ways that we could impact infants to develop their immunity so they don’t go towards developing allergies,” said Dr. Mark Holbreich, a St. Vincent Health allergist. “The goal of all the research is to one day say we have found the major protective factor for the development of allergies and asthma and in some way use it as the primary prevention of allergies.”
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Holbreich’s interest in the Amish dates back more than 25 years, when his wife, who treats hemophilia, begin providing free care for the community. Holbreich offered his specialty, too.
Many patients came to him, complaining of allergies, but when he tested them, he learned few actually had allergies. In 2012, he published a study showing that a mere 7 percent of Amish children had been sensitized to common allergens, such as cats, dogs or mold. In the general population, about 45 percent of people tend to show such sensitivities.
Suggesting that genetics alone could not explain this difference, Hutterite children — who shared a similar diet, lifestyle (no pets, no television), and genetics — had a sensitivity prevalence closer to that of the general participation. One of the few factors that distinguish Hutterites from Amish, however, is their farming style.
Whereas both live in agricultural communities, where dairy farming offers the main livelihood, the Hutterites live a little distance from their barns. While the men work there, the women and children rarely visit. Amish children and women, however, live close to the barns and frequently go in between house and barn, inadvertently tracking in dust rich in barn microbes.
So Holbreich, also with Allergy and Asthma Consultants, teamed up with researchers at the University of Chicago, the University of Iowa and elsewhere to study how this difference could impact the development of asthma and allergies.
The researchers collected dust from Amish and Hutterite homes and sent that to their colleagues at the University of Arizona, who sprayed that dust inside the noses of mice before trying to induce an asthma attack. The mice who were pretreated with the Amish dust, however, did not oblige, suggesting that somehow that exposure had protected them.
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Scientists know that the immune system works in a complicated fashion. We’re all born with some innate immunity. But then we react to things we find in our environment to build up additional immunity. That innate immune system plays a critical role in this process by signaling the so-called adaptive immune system to tell it what it’s supposed to do, Holbreich said.
So the researchers looked once more at mice, this time knocking out two genes that allow the innate immune system to communicate with the adaptive one. And these mice enjoyed no protection from the Amish dust, the study found.
“The conclusion was when you have these microbial exposures early in life, your innate system signals your adaptive system not to have asthma, not to have allergies,” Holbreich said. “We have an insight into how this whole process of developing allergies is happening."
Future studies will explore exactly what critical substance that Amish dust contains, with an eye to finding ways to prevent the development of allergies.
Follow Shari Rudavsky on Twitter: @srudavsky