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2628376 
Journal Article 
Abstract 
Exposure to Mexicali PM10 induces IL-8 expression through an alternative NFºB mechanism in human airway epithelial cells 
Silbajoris, R; Dailey, LA; Simmons, S; Osornio-Vargas, AR; Samet, JM 
2010 
Yes 
American Journal of Respiratory and Critical Care Medicine
ISSN: 1073-449X
EISSN: 1535-4970 
181 
A1154 
English 
WOS:000208771000155 
is part of a larger document 3452678 Proceedings of the American Thoracic Society 2010 International Conference, May 14-19, 2010, New Orleans
Studies have shown associations between exposure to ambient air particulate matter (PM) and increased rates of cardio-pulmonary morbidity and mortality. The aim of this study was to examine the signaling events involved in the expression of inflammatory genes in cultured human airway epithelial cells (HAEC) exposed to PM10 derived from vehicle emissions in an urban area of Mexicali, Mexico. PM10 fractions were collected on cellulose membranes using High-Vol samplers between October 2005 and March 2006. Real Time (RT)-PCR showed that HAEC exposed for 4 h to 10-80 μg/cm^2 PM resuspended in media resulted in a dose-dependent increase in IL-8 mRNA expression that was 2-8-fold higher than media controls. PM exposure induced IL-8 transcriptional activity in BEAS-2B cells expressing an IL-8 promoter reporter construct. Mutation of the NFκB response element in the IL-8 promoter resulted in a significant impairment in IL-8 transcriptional activity. The activation of NFκB-dependent transcriptional activity was confirmed using a synthetic luciferase reporter driven by a tandem repeat of the canonical NFκB binding site. Chromatin Immunoprecipitation (CHiP) assay was used to immunoprecipitate NFκB-bound DNA fragments. RT-PCR, employing primers and a fluorescent probe directed against the NFκB sequence in the IL-8 gene promoter region, was then used to measure % of input, comparing signals of CHiP samples to total input DNA. We found a 3-fold enrichment of IL-8 promoter sequence in HAEC exposed to PM compared to media controls. Expression of IL-8 mRNA in PM treated HAEC was reduced when cells were pretreated with BAY 11-7082, an NFκB inhibitor, but not with the IΚΚ-2 inhibitor BMS-345541, and Western blot analyses showed increased NFκBp65 phosphorylation independent of IΚBα degradation or phosphorylation. Taken together, this data suggests that activation of NFκB occurs through a non-canonical pathway. We conclude that the increase in IL-8 mRNA expression in HAEC exposed to PM10 is mediated through an NFκB-dependent signaling mechanism that involves direct phosphorylation of the transcription factor p65. These findings show that PM10 exposure can induce inflammatory responses by activating specific signaling mechanisms in human airway epithelial cells. THIS ABSTRACT OF A PROPOSED PRESENTATION DOES NOT NECESSARILY REFLECT EPA POLICY. 
American Thoracic Society 2010 International Conference 
New Orleans, LA 
May 14-19, 2010