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Biomarkers of Acute Respiratory Allergen Exposure: Screening For Sensitization Potential
Citation:
PUCHEU-HASTON, C. M., L. B. COPELAND, B. VALLANAT, AND M. D. WARD. Biomarkers of Acute Respiratory Allergen Exposure: Screening For Sensitization Potential. Presented at AMERICAN ACADEMY OF ALLERGY, ASTHMA AND IMMUNOLOGY, WASHINGTON, DC, March 13 - 17, 2009.
Impact/Purpose:
This abstract describes a research effort to identify biomarkers that differentiate the responses to allergens vs. non-allergens following an acute exposure. Biomarkers genes obtained from this analysis will facilitate improvements in methods of screening for respiratory sensitizers.
Description:
Rationale: An in vitro assay to identify respiratory sensitizers will provide a rapid screen and reduce animal use. The study goal was to identify biomarkers that differentiate allergen versus non-allergen responses following an acute exposure. Methods: Female BALB/c mice received a single intratracheal aspiration (IA) exposure to Metarhizium anisopliae crude antigen (MACA) or bovine serum albumin (BSA) in Hank’s Balanced Salt Solution (HBSS) or HBSS alone. Mice were sacrificed after 1, 3, 6, 12, 18 and 24 hours. Bronchoalveolar lavage fluid (BALF) was evaluated to determine total and differential cellularity, total protein concentration and LDH activity. RNA was isolated from lung tissue for microarray analysis and RT-PCR. Results: Administration of MACA induced a rapid increase in BALF neutrophils, lymphocytes, eosinophils and total protein levels as compared to BSA or HBSS. Microarray analysis demonstrated differential expression of genes involved in cytokine production and signaling, as well as inflammatory cell recruitment, adhesion and activation in 3h and 12h MACA-treated samples as compared to BSA or HBSS. Further statistical and pathway analyses allowed identification of ~100 candidate biomarker genes. Eleven genes (CCL19, CCL17, CCL22, CCL7, C3aR1, CXCL10, CXCL2, Saa1, SOCS3, Arg2 and VCAM1) were selected for further assessment by qRT-PCR. Conclusions: A single respiratory exposure of mice to an allergenic mold extract induces an inflammatory response which is distinct in phenotype and gene expression from the response to a control protein. Biomarker genes obtained from this analysis will facilitate improvements in screening methods. (Supported by UNC/EPA Cooperative Training Agreement CR83323701. This abstract does not reflect EPA policy).