Environmental Exposures and Asthma

Abstract

Research Article| December 01 2016 Environmental Exposures and Asthma AAP Grand Rounds (2016) 36 (6): 67. https://doi.org/10.1542/gr.36-6-67 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Environmental Exposures and Asthma. AAP Grand Rounds December 2016; 36 (6): 67. https://doi.org/10.1542/gr.36-6-67 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search toolbar search search input Search input auto suggest filter your search All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: asthma, environmental exposure Stein MM, Hrusch CL, Gozdz J, et al. Innate immunity and asthma risk in Amish and Hutterite farm children. N Engl J Med. 2016; 375(5): 411– 421; doi: https://doi.org/10.1056/NEJMoa1508749Google Scholar Investigators from multiple institutions studied the effect of the environment on asthma among 2 distinctive US farming populations—the Amish of Indiana and the Hutterites of South Dakota. These 2 populations were chosen because the prevalence of asthma in each is strikingly different (5% in Amish and 21% in Hutterites) despite having similar lifestyles with respect to most of the factors known to influence the risk of asthma (eg, large sibship size, minimal exposure to tobacco smoke and air pollution, long durations of breastfeeding) and similar genetic ancestry (both populations originated in Europe and have remained reproductively isolated since immigrating to the United States). One important difference between the 2 populations is that the Amish practice traditional farming (eg, single-family dairy farms and use of horses for fieldwork) and the Hutterites live on large, highly industrialized communal farms. Amish children aged 7–14 years were eligible. Hutterite children were age- and gender-matched to the enrolled Amish children. Whole blood was collected from all participants to measure serum IgE and cytokine levels. Investigators also extracted DNA to assess ancestry by performing genotyping and comparing allele frequencies with European populations included in the Human Genome Diversity Project. Dust was collected in 10 Amish and 10 Hutterite homes and analyzed for endotoxin levels. Extract from Amish or Hutterite dust was then instilled intranasally every 2–3 days for 7 days in wild-type mice and mice deficient in proteins (MyD88 and Trif) involved in multiple innate immunity signaling pathways. Airway inflammation in mice was measured by assessing airway hyperresponsiveness and bronchoalveolar lavage (BAL) eosinophilia. The investigators compared the differences in distributions of IgE and cytokine levels between Amish and Hutterite children as well as differences in airway inflammation in mice exposed to Amish and Hutterite dust extract. There were 30 Amish and 30 Hutterite children enrolled. None of the Amish children had asthma, and 20% of the Hutterite children did. In ancestry analysis, Amish and Hutterite children were genetically similar compared with other European populations. Serum IgE and cytokine levels were significantly lower in Amish children compared to Hutterite children. Mean endotoxin levels were significantly higher in Amish versus Hutterite homes. When Hutterite dust extract was administered to wild-type mice, airway inflammation was observed. When Amish dust extract was administered, airway inflammation was suppressed. This protection was lost when Amish dust extract was applied to mice lacking the innate immunity proteins MyD88 and Trif. The investigators conclude that the Amish farm dust is protective against asthma through stimulation of innate immunity. Dr. Phillipi has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device. Asthma is increasingly common, affecting 6.3 million US children with an estimated prevalence of 8.6%.1 Reasons... You do not currently have access to this content.