You are here:
*Assessing differential transcriptional regulation of IL-8 expression by human airway epithelial cells exposed to diesel exhaust particles
Citation:
Tal, T., S. SIMMONS, R. A. SILBAJORIS, L. A. DAILEY, W. REED, T. V. RAMABHADRAN, P. A. BROMBERG, AND J. M. SAMET. *Assessing differential transcriptional regulation of IL-8 expression by human airway epithelial cells exposed to diesel exhaust particles. TOXICOLOGY AND APPLIED PHARMACOLOGY. Academic Press Incorporated, Orlando, FL, 243(1):46-54, (2010).
Impact/Purpose:
To determine whether DEP with varying organic content induces IL-8 expression in lung epithelial cells. 2. To develop a method to rapidly evaluate the upstream mechanism(s) by which DEP induces IL-8 expression.
Description:
Background: Exposure to Diesel Exhaust Particles (DEP) induces inflammatory signaling characterized by MAP kinase-mediated activation of NFkB and AP-l in vitro and in bronchial biopsies obtained from human subjects exposed to DEP. NFkB and AP-l activation results in the upregulation of genes involved in promoting inflammation in airway epithelial cells, a principal target of inhaled DEP. IL-8 is a proinflammatory chemokine expressed by the airway epithelium in response to environmental pollutants. Objectives: 1. To determine whether DEP with varying organic content induces IL-8 expression in lung epithelial cells. 2. To develop a method to rapidly evaluate the upstream mechanism(s) by which DEP induces IL-8 expression. Methods: IL-8 expression, IL-8 promoter activity and NFkB and AP-l transcriptional activity were measured by qRT-PCR. Mutational analysis of the IL-8 promoter was also performed by qRT-PCR using recombinant cell lines expressing reporters linked to the mutated promoters. Results: Exposure to DEP with varying organic content differentially induced IL-8 expression in primary human lung epithelial cells and BEAS-2B cells. Treatment with a low organic-containing DEP stimulated IL-8 expression by a mechanism that is predominantly NFkB-dependent. In contrast, exposure to high organic-containing DEP induced IL-8 expression independently of NFkB through a mechanism that requires AP-l activity. Conclusions: Exposure to DEP of varying organic content induces proinflammatory gene expression through multiple specific mechanisms in human airway epithelial cells. The approaches used in the present study demonstrate the utility of a qRT-PCR-based promoter-reporter assay ensemble for identifying transcriptional pathways activated by pollutant exposure. 4 Assessing differential transcriptional regulation of IL-8 expression by human airway epithelial cells exposed to diesel exhaust particles Tamara L. Tall, Steve Simmons', Robert Silbajoris"; Lisa Dailey", William Reed", Ram Ramabhadrarr'", Philip A. Bromberg', and James M. Samet':' 'Curriculum in Toxicology and 2Center for Environmental Medicine, Asthma, and Lung Biology, University of North Carolina, Chapel Hill; and Integrated Systems Toxicology and Environmental and Public Health4 Divisions, National Health and Environmental Effects Research Laboratory, U.S. EPA. Address Correspondence to: Dr. James M. Samet, Human Studies Division MD-58D, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, 104 Mason Farm, Chapel Hill, NC 27599-7315 (Email: samet.james@epa.gov; Tel. 919-966-0665; Fax 919-966¬6271) Disclaimer: The research described herein has been reviewed by the National Health and Environmental Effects Research Laboratory and has been approved for publication. Approval does not signify thatthe contents necessarily reflect the views and policies of the U.S. EPA, nor does mention oftrade names constitute endorsement of recommendation for use.
