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Rationale: The molecular mechanisms involved in airway oxidative stress responses reported in healthy smokers and in those with chronic obstructive pulmonary disease (COPD) are poorly understood., Objectives: To assess the expression of genes involved in oxidative stress responses in the bronchial epithelium of smokers with or without COPD and in relation to disease severity., Methods: Global gene expression was assessed in bronchial brushings in 38 subjects with COPD, 14 healthy nonsmokers, and 18 healthy smokers., Results: Gene expression analysis using Affymetrix arrays revealed mRNAs representing 341 out of 642 oxidative stress genes from two predefined gene sets to be differentially expressed in healthy nonsmokers when compared with healthy smokers, and 200 differentially expressed oxidative genes in subjects with COPD when compared with healthy smokers. Gene set enrichment analysis showed that pathways involved in oxidant/antioxidant responses were among the most differentially expressed gene pathways in smoking individuals, with further differences seen in COPD. Distinct, nonlinear gene expression patterns were identified across the severity spectrum of COPD, which correlated with the presence of certain transcription factor binding sites in their promoters. Significant changes in oxidant response genes observed in vivo were reproduced in vitro using primary bronchial epithelial cells from the same donors cultured at an air-liquid interface and exposed to cigarette smoke extract., Conclusions: Cigarette smoke induces significant changes in oxidant defense responses; some of these are further amplified, but not in a linear fashion, in individuals who develop COPD.

Aims: To quantify the extent of squamous metaplasia in bronchial biopsies and relate it to the presence of chronic obstructive pulmonary disease (COPD), a smoking-related pathology. Methods: Bronchial biopsies (n = 15 in each group) from smokers with COPD GOLD stage1 and GOLD stage2, smokers without COPD and healthy non-smokers were stained immunohistochemically with a panel of antibodies that facilitated the identification of pseudostratified epithelium and distinction of squamous metaplasia and squamous epithelium from tangentially cut epithelium. The percentage length of each of these epithelial phenotypes was measured as a percent of total epithelial length using computerised image analysis. Sections were also stained for carcinoembryonic antigen and p53, early markers of carcinogenesis, and Ki67, and the percentage epithelial expression measured. Results: The extent of squamous metaplasia was significantly increased in both COPD1 and COPD2 compared to healthy smokers and healthy non-smokers. The amount of fully differentiated squamous epithelium was also increased in COPD1 and COPD2 compared to healthy non-smokers, as was the expression of carcinoembryonic antigen. These features correlated with one other. Conclusion: In subjects with COPD there is a loss of pseudostratified epithelium accompanied by an increase in squamous metaplasia with transition into a fully squamous epithelium and expression of early markers of carcinogenesis. [ABSTRACT FROM AUTHOR]

Background: Epidemiological evidence demonstrates that exposure to traffic-derived pollution worsens respiratory symptoms in asthmatics, but controlled human exposure studies have failed to provide a mechanism for this effect. Here we investigated whether diesel exhaust (DE) would induce apoptosis or proliferation in the bronchial epithelium in vivo and thus contribute to respiratory symptoms. Methods: Moderate (n = 16) andmild (n = 16) asthmatics, atopic non-asthmatic controls (rhinitics) (n = 13) and healthy controls (n = 21) were exposed to filtered air or DE (100 μg/m³) for 2 h, on two separate occasions. Bronchial biopsies were taken 18 h post-exposure and immunohistochemically analysed for pro-apoptotic and anti-apoptotic proteins (Bad, Bak, p85 PARP, Fas, Bcl-2) and a marker of proliferation (Ki67). Positive staining was assessed within the epithelium using computerized image analysis. Results: No evidence of epithelial apoptosis or proliferation was observed in healthy, allergic or asthmatic airways following DE challenge. Conclusion: In the present study, we investigated whether DE exposure would affect markers of proliferation and apoptosis in the bronchial epithelium of asthmatics, rhinitics and healthy controls, providing a mechanistic basis for the reported increased airway sensitivity in asthmatics to air pollutants. In this first in vivo exposure investigation, we found no evidence of diesel exhaust-induced effects on these processes in the subject groups investigated. [ABSTRACT FROM AUTHOR]

Background: Epidemiological studies have demonstrated adverse health effects of environmental pollution. Diesel exhaust (DE) is a major contributor to particulate matter pollution. DE exposure has been shown to induce a pronounced inflammatory response in the airways, together with an enhanced epithelial expression of cytokines such as IL-8, Gro-a, IL-13 and activation of redox sensitive transcription factors (NFκB, AP-1), and MAP kinases (p38, JNK). The aim of the present investigation was to elucidate the involvement of the epidermal growth factor receptor (EGFR) signalling pathway in the epithelial response to DE in-vivo. Results: Immunohistochemical staining was used to quantify the expression of the EGFR, phosphorylated Tyrosine residues, MEK and ERK in the bronchial epithelium of archived biopsies from 15 healthy subjects following exposure to DE (PM10, 300 µg/m³) and air. DE induced a significant increases in the expression of EGFR (p = 0.004) and phosphorylated C-terminal Tyr 1173 (p = 0.02). Other investigated EGFR tyrosine residues, Src related tyrosine (Tyr 416), MEK and ERK pathway were not changed significantly by DE. Conclusion: Exposure to DE (PM10, 300 µg/m³) caused enhanced EGFR expression and phosphorylation of the tyrosine residue (Tyr 1173) which is in accordance with the previously demonstrated activation of the JNK, AP-1, p38 MAPK and NFκB pathways and associated downstream signalling and cytokine production. No effects were seen on the MEK and ERK pathway suggesting that at the investigated time point (6 hours post exposure) there was no proliferative/differentiation signalling in the bronchial epithelium. The present findings suggest a key role for EGFR in the bronchial response to diesel exhaust. [ABSTRACT FROM AUTHOR]

Background: A recent NIH Workshop and an ERS Task Force concluded that more work was needed to understand mechanisms of severe and chronic asthma. This report describes a series of studies that identify aberrant epithelial mesenchymal signalling in the airways as an important event in maintaining inflammation and driving remodelling in response to environmental injury. Methods: Immunohistochemistry, genotyping and functional studies conducted on cultured asthmatic cells and mucosal biopsies were used to identify biochemical pathways involved in epithelial injury and repair in asthma and their relationship to disease severity. Results: Our findings suggest that the asthmatic state results from an interaction between a susceptible epithelium and Th-2-mediated inflammation to alter the communication between the epithelium and the underlying mesenchyme – the epithelial mesenchymal trophic unit – leading to disease persistence, airway remodelling and refractoriness to corticosteroid treatment. Conclusions: Asthma is more than an inflammatory disorder, but requires engagement of important signalling pathways involved in epithelial repair and tissue remodelling. These pathways involving EGFRs and TGF-βRs provide targets against which to develop novel therapies for chronic asthma.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]