Published in:
Open Access
01-12-2002 | Research
Mechanism of cigarette smoke condensate-induced acute inflammatory response in human bronchial epithelial cells
Authors:
Gary R Hellermann, Szilvia B Nagy, Xiaoyuan Kong, Richard F Lockey, Shyam S Mohapatra
Published in:
Respiratory Research
|
Issue 1/2001
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Abstract
Background
To demonstrate the involvement of tobacco smoking in the pathophysiology of lung disease, the responses of pulmonary epithelial cells to cigarette smoke condensate (CSC) — the particulate fraction of tobacco smoke — were examined.
Methods
The human alveolar epithelial cell line A549 and normal human bronchial epithelial cells (NHBEs) were exposed to 0.4 μg/ml CSC, a concentration that resulted in >90% cell survival and <5% apoptosis. Changes in gene expression and signaling responses were determined by RT-PCR, western blotting and immunocytofluorescence.
Results
NHBEs exposed to CSC showed increased expression of the inflammatory mediators sICAM-1, IL-1β, IL-8 and GM-CSF, as determined by RT-PCR. CSC-induced IL-1β expression was reduced by PD98059, a blocker of mitogen-actived protein kinase (MAPK) kinase (MEK), and by PDTC, a NFκB inhibitor. Analysis of intracellular signaling pathways, using antibodies specific for phosphorylated MAPKs (extracellular signal-regulated kinase [ERK]-1/2), demonstrated an increased level of phosphorylated ERK1/2 with increasing CSC concentration. Nuclear localization of phosphorylated ERK1/2 was seen within 30 min of CSC exposure and was inhibited by PD98059. Increased phosphorylation and nuclear translocation of IκB was also seen after CSC exposure. A549 cells transfected with a luciferase reporter plasmid containing a NFκB-inducible promoter sequence and exposed to CSC (0.4 μg/ml) or TNF-α (50 ng/ml) had an increased reporter activity of approximately 2-fold for CSC and 3.5-fold for TNF-α relative to untreated controls.
Conclusion
The acute phase response of NHBEs to cigarette smoke involves activation of both MAPK and NFκB.