Barnyard Dust Composition and Implications for Asthma in Children

Academic Research Topics in Environmental Measurement and Monitoring
Oral Presentation

Prepared by M. Marques dos Santos, C. Hoppe-Jones, S. Snyder
University of Arizona, 1133 E James E. Rogers Way, Tucson, Arizona, 85721, United States


Contact Information: mauricius@email.arizona.edu; 520-245-1848


ABSTRACT

Asthma is a heterogeneous group of conditions that result in recurrent, reversible bronchial obstruction and affects 5-16% of the population worldwide. In the US as many as 10.6 % of grade school children have asthma. Numerous epidemiological studies have shown that children who grow up on traditional farms are protected from asthma, hay fever and allergic sensitization, with prevalence reduced over 5-fold.
In the effort of understanding probable causes for the effect of asthma protection, barnyard dust composition from a traditional farming community was studied in association with in vitro bioassays. Effects of different extraction methods, temperature influence, molecular size distribution and the role of major biomolecule classes were assessed. Dust extracts were fractionated using size exclusion chromatography (SEC) in the range of 3 kDa to 100 kDa and tested in an in vitro model using epithelial cells (NuLi-1) in an air-liquid interface culture (ALI). Cells were exposed to different concentrations of extracts (3 mg, 1mg and 0.33 mg of Dust equivalents) and assessed for the secretion of different cytokines. A 1.5 min SEC fraction has shown the highest potency to inhibit secretion of Interleukin-6 (IL-6; pro-inflammatory cytokine) in the in vitro assay, with three other adjacent fractions also showing activity. SEC fractions were analyzed by LC-QTOF-MS using reversed phase chromatography (C18) and hydrophilic interaction chromatography (HILIC) with electrospray ionization (ESI) in positive and negative modes for chemical fingerprinting of samples and putative identification of compounds/classes relevant for asthma prevention. Agilent Mass Profiler Professional (MPP) was used for MS analysis. Analytical standards of common allergens (Dust mites and Lipopolysaccharides) and a standard reference material dust (SRM 2585) were also compared. Complementary techniques such as MALDI-TOF-MS and NMR were applied to further study active SEC fractions capable of reducing the secretion of IL-6 in bioassay as measured by ELISA assay.