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INDOOR FUNGAL CONTAMINANTS: ASSESSING THE ALLERGIC POTENTIAL
Citation:
Ward, MDW, M. E. Viana, Y. Chung, N HaykalCoates, L B. Copeland, M J. Donohue, J A. Shoemaker, AND MJK Selgrade. INDOOR FUNGAL CONTAMINANTS: ASSESSING THE ALLERGIC POTENTIAL. Presented at Environ. Influences on the Induction and Incidence of Asthma, Research Triangle Park, NC, October 18-19, 2004.
Description:
The indoor environment has increased in importance to children's health with children now spending more than 90% of their time indoors. Molds are an important component of this environment and have been associated with exacerbation of asthma as well as a number of other health effects. Their contribution to the induction of allergic asthma is less certain. Our objectives are 1) to develop methods to assess the allergic potential of two fungal extracts, the biopesticide Metarhizium anisopliae (MACA) and Stachybotrys chartarum (SCE-1) (associated with water damaged buildings and sick building syndrome), 2) to identify the specific allergenic components, and 3) to assess the relative risks of exposure to these agents compared to a known indoor allergen, dust mite. Methods: In a series of studies female BALB/c mice were exposed 4 times by involuntary aspiration (IA) to 10 ?g of MACA, SCE-1, or bovine serum albumin (BSA) (negative control), or vehicle control Hank's balanced salt solution (HBSS). Additional mice were exposed one time to MACA, SCE-1, or BSA as inflammatory controls. Serum and bronchoalveolar lavage fluid (BALF) were collected before (D0), and at 1 (D1) and 3 (D3) days following the final IA exposure. Additionally, whole-body plethysmography (Buxco) was used as an index of pulmonary resistance and bronchoconstriction. Mice were assessed for immediate responses for 1 hour following each aspiration exposure and airway hyperresponsiveness to methacholine (D1 and D3). Western blot analysis was used to identify IgE inducing proteins in the extracts. The MACA proteins were further characterized by 2-dimensional (2-D) gel electrophoresis and mass spectrometric analysis. Results: Exposure to both MACA and SCE-1 extracts caused increases in non-specific parameters such as BALF total protein, LDH, and neutrophilic influx compared to vehicle and negative controls. Furthermore, adaptive immune parameters such as BALF IL-5 and eosinophilic influx were increased, as were serum total and antigen specific IgE. The fungal extracts also caused significant increases in Buxco measures compared to both HBSS and BSA. Additionally, IgE-inducing proteins were identified in both MACA and SCE-1 by Western blot analysis. 2-D gel immunoblots of MACA extract shows 8 protein spots with acidic pIs ranging between pH 4.8 and pH 5.5. Following matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization mass spectrometry (ESI-MS/MS) analysis of these MACA fungal peptides/proteins, databases were searched for potential sequence or domain homology to known allergens using MASCOT (database-mining algorithm). MACA 2-D gel protein spots #1-5 have demonstrated sequence or antibody binding homology to the enzyme catalase. Conclusions: Respiratory exposure to either MACA or SCE-1 causes responses similar to those observed in human allergic lung disease suggesting that these two molds, at least, may have a role in the induction of asthma. Additionally, both fungal extracts have IgE binding proteins providing further evidence that these fungal extracts have the potential to induce allergy. (This abstract does not reflect EPA policy. Supported by NCSU/EPA Cooperative Training Agreement CT826512010 and UNC/EPA Cooperative Training Agreement CT829471.)