Amish children are innately protected against asthma

Liz Meszaros, MDLinx | August 15, 2016

Amish children may be protected against allergic asthma, and this protection may be due to an environment rich in microbes that has far-reaching effects on their innate immunity, according to researchers who studied differences in the prevalence of asthma in children from two farming communities, the Amish of Indiana and the Hutterites of South Dakota.

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Are Amish kids protected against asthma?

Are Amish kids protected against asthma?

The rich concentration of microbes present in Amish house dust may have a protective effect against allergic asthma.

“We have proven that the reason the Amish children are so strongly protected from asthma is how they live,” said study co-author, immunologist Donata Vercelli, MD, associate director of the Asthma and Airway Disease Research Center at the University of Arizona Health Sciences, Tucson, AZ, professor of cellular and molecular medicine at the UA College of Medicine College of medicine, and director of the Arizona Center for the Biology of Complex Diseases.

“We now have a model that over time may allow us to understand what component of the environment is required; basically, we are learning from the Amish environment how to prevent asthma,” added Dr. Vercelli.

They hope that their findings will help guide the search for future management, treatment, and even preventive options for asthma.

Dr. Vercelli and colleagues from the University of Arizona, the University of Chicago, and the Dr. von Hauner Children’s Hospital in Munich, Germany, studied these two agricultural populations, both founded by immigrants from Central Europe in the 18th and 19th centuries and both having similar genetic ancestry. These communities have similar lifestyles and customs, with large families, and allowing for childhood vaccinations and breastfeeding, no television, adhering to a Germanic farming diet, drinking raw milk, and not allowing any indoor pets.

Farming practices in these two communities, however, differ greatly. The Amish have adhered to traditional farming practices, living on single-family dairy farms, and relying on horses for fieldwork and transportation. The Hutterites, on the other hand, live on large communal farms, and use modern, industrialized farm machinery.

The other great difference seen in these two communities is in the prevalence of asthma. In Amish schoolchildren aged 6 to 14 years, the prevalence of asthma is about one-half the US average for this age group (5% compared with 10.3%, respectively). The prevalence of asthma in Amish children is also much lower than that found among Hutterite children (21.3%).

In this recent study, published in the August 4, 2016 issue of the New England Journal of Medicine, researchers studied 30 Amish children aged 7 to 14 years old, and compared them with 30 age-matched Hutterite children. Genetic profiles showed similarities between the two groups. Researchers also compared serum immune cells, airborne dust, and microbial loads in homes.

They found that Amish children had more and younger neutrophils and fewer eosinophils, cells involved in both immunity and allergic inflammation, compared with Hutterite children. Gene expression profiles in the blood cells also showed enhanced activation of key innate immunity genes in Amish children.

Researchers then conducted studies in mice, which were exposed to house-dust extracts. The airways of mice exposed to Amish dust exhibited protection from asthma-like responses to allergens, while the mice exposed to Hutterite house dust exhibited no such protection. To further break this down, researchers then studied mice lacking MyD88 and Trif, which are genes vital for innate immune responses. In these mice, the protective effects of the Amish dust did not manifest.

“The results of the mouse experiments conclusively prove that products from the Amish environment are sufficient to confer protection from asthma, and highlight the novel, central role that innate immunity plays in directing this process,” said Dr. Vercelli.

Substances in the house dust in Amish, specifically microbial products—plentiful in the Amish dust but much less so in Hutterite house dust—played a role in engaging and shaping the immune system in Amish children that may have suppressed pathologic responses that lead to the development of allergic asthma, concluded these researchers.

“Neither the Amish nor the Hutterites have dirty homes,” explained co-author Carole Ober, PhD, professor and chairman of human genetics, University of Chicago, Chicago, IL. “Both are tidy. The Amish barns, however, are much closer to their homes. Their children run in and out of them, often barefoot, all day long. There’s no obvious dirt in the Amish homes, no lapse of cleanliness. It’s just in the air, and in the dust.”

“You can’t put a cow in every family’s house,” Dr. Ober concluded, “but we may be able to protect children from asthma by finding a way to re-create the time-tested Amish experience.”

The study was supported by the National Institutes of Health, St. Vincent Foundation, and the American Academy of Allergy, Asthma & Immunology Foundation.

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