Dataset Information

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

ABSTRACT: RATIONALE:Endotoxin initiates a proinflammatory response from the innate immune system. Studies in children suggest that endotoxin exposure from house dust may be an important risk factor for asthma, but few studies have been conducted in adult populations. OBJECTIVES:To investigate the association of house dust endotoxin levels with asthma and related phenotypes (wheeze, atopy, and pulmonary function) in a large U.S. farming population. METHODS:Dust was collected from the bedrooms (n?=?2,485) of participants enrolled in a case-control study of current asthma (927 cases) nested within the Agricultural Health Study. Dust endotoxin was measured by Limulus amebocyte lysate assay. Outcomes were measured by questionnaire, spirometry, and blood draw. We evaluated associations using linear and logistic regression. MEASUREMENTS AND MAIN RESULTS:Endotoxin was significantly associated with current asthma (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.14-1.47), and this relationship was modified by early-life farm exposure (born on a farm: OR, 1.18; 95% CI, 1.02-1.37; not born on a farm: OR, 1.67; 95% CI, 1.26-2.20; Interaction P?=?0.05). Significant positive associations were seen with both atopic and nonatopic asthma. Endotoxin was not related to either atopy or wheeze. Higher endotoxin was related to lower FEV1/FVC in asthma cases only (Interaction P?=?0.01). For asthma, there was suggestive evidence of a gene-by-environment interaction for the CD14 variant rs2569190 (Interaction P?=?0.16) but not for the TLR4 variants rs4986790 and rs4986791. CONCLUSIONS:House dust endotoxin was associated with current atopic and nonatopic asthma in a U.S. farming population. The degree of the association with asthma depended on early-life farm exposures. Furthermore, endotoxin was associated with lower pulmonary function in patients with asthma.

SUBMITTER: Carnes MU

PROVIDER: S-EPMC5427722 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

Carnes Megan Ulmer MU Hoppin Jane A JA Metwali Nervana N Wyss Annah B AB Hankinson John L JL O'Connell Elizabeth Long EL Richards Marie M Long Stuart S Freeman Laura E Beane LE Sandler Dale P DP Henneberger Paul K PK Barker-Cummings Christie C Umbach David M DM Thorne Peter S PS London Stephanie J SJ

Annals of the American Thoracic Society 20170301 3

<h4>Rationale</h4>Endotoxin initiates a proinflammatory response from the innate immune system. Studies in children suggest that endotoxin exposure from house dust may be an important risk factor for asthma, but few studies have been conducted in adult populations.<h4>Objectives</h4>To investigate the association of house dust endotoxin levels with asthma and related phenotypes (wheeze, atopy, and pulmonary function) in a large U.S. farming population.<h4>Methods</h4>Dust was collected from the ...[more]

PMID: 27977294

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Project description:BackgroundEnvironmental factors can influence the house dust microbiota, which may impact health outcomes. Little is known about how farming exposures impact the indoor microbiota.ObjectiveWe aimed to identify exposures related to bacterial communities in house dust in a U.S. farming population.MethodsWe used 16S rRNA amplicon sequencing to characterize bacterial communities in vacuumed dust samples from the bedrooms of a subset of 879 households of farmers and farmers' spouses enrolled in the Agricultural Lung Health Study (ALHS), a case-control study of asthma nested within the Agricultural Health Study (AHS) in North Carolina and Iowa. Information on current farming (past 12 mo), including both crop and animal farming, and other potential microbial sources was obtained via questionnaires. We used linear regression to evaluate associations between exposures and bacterial diversity within each sample, analysis of similarity (ANOSIM), and permutational multivariate analysis of variance (PERMANOVA) to identify exposures related to diversity between samples, and analysis of composition of microbiome to examine whether exposures related to diversity were also related to differential abundance of specific operational taxonomic units (OTUs).ResultsCurrent farming was positively associated with bacterial diversity in house dust, with or without adjustment for nonfarm exposures related to diversity, including presence of indoor pets, home condition, and season of dust collection. Many taxa exhibited differential abundance related to farming. Some taxa in the phyla Chloroflexi and Verrucomicrobia were associated [false discovery rate (FDR)<0.05] with farming but not with other nonfarm factors. Many taxa correlated with the concentration of house dust of endotoxin, commonly studied as a general marker of exposure to the farming environment.ConclusionsIn this farming population, house dust microbiota differed by current farming status. Understanding the determinants of the indoor microbiota is the first step toward understanding potential relationships with health outcomes. https://doi.org/10.1289/EHP3145.

Dataset Information

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

Publications

House Dust Endotoxin Levels Are Associated with Adult Asthma in a U.S. Farming Population.

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