Animal studies have reported that diesel exhaust particles (DEP), which constitute an important fraction of particulate air pollution, lead to inflammation and/or damage of the airways. To investigate the mechanisms underlying DEP-induced airway disease in humans, we have cultured human bronchial epithelial cells (HBEC) from surgically obtained bronchial explants and investigated the effects of purified DEP on the permeability and ciliary beat frequency (CBF) of HBEC, and on the release of inflammatory mediators from these cells. Exposure to 10-100 microg/ml DEP and a filtered solution of 50 microg/ml DEP significantly increased the electrical resistance of the cultures, reaching a maximum of 200% over baseline after 6 h incubation with 100 microg/ml DEP. In contrast, movement of 14C-labeled bovine serum albumin across cell cultures was not significantly altered by incubation of HBEC with DEP. Exposure to 50 microg/ml DEP, filtered DEP solution, and 100 migrog/ml DEP significantly attenuated the CBF of these cells by 51%, 33%, and 73%, respectively, from baseline after 24 h incubation. Similarly, 50 microg/ml DEP, filtered DEP solution, and 100 microg/ml DEP significantly increased the release of interleukin-8 from 12.9 pg/microg cellular protein to 41.6, 114.9, and 44.3 pg/microg cellular protein, respectively, after 24 h incubation. The release of granulocyte-macrophage colony stimulating factor (GM-CSF) and soluble intercellular adhesion molecule-1 (sICAM-1) was also significantly increased after exposure for 24 h to 50 microg/ml DEP (GM-CSF from 0.033 pg/microg cellular protein to 0.056 pg/mug cellular protein and sICAM-1 from 7.2 pg/microg cellular protein to 12.5 pg/microg cellular protein). These results suggest that exposure of HBEC to DEP may lead to adverse functional changes and release of proinflammatory mediators from these cells, and that these effects may influence the development of airway disease.

Background-Although sputum induction is used as a technique to investigate lower airway inflammation in asthmatic subjects, advantages over spontaneous sputum in patients with chronic obstructive pulmonary disease (COPD) have not been investigated. Methods-Samples of spontaneous sputum and sputum induced with 3% hypertonic saline for 14 minutes were collected from 27 patients with chronic obstructive pulmonary disease (COPD) who usually produced spontaneous sputum. Spirometric indices and oxygen saturation (SaO 2 ) were measured at seven minute intervals. The spontaneous, seven and 14 minute sputum samples were analysed for total and diVerential cell counts, cell viability, and interleukin 8 levels. Results-Analysis of the sputum revealed that median cell viability was higher in the seven minute (62.8%; p = 0.004) and 14 minute (65%; p = 0.001) induced sputum samples than in spontaneous sputum (41.2%). There was no significant diVerence in total and diVerential cell counts or in interleukin 8 levels between spontaneous and induced sputum. During the sputum induction procedure the mean (SD) fall in forced expiratory volume in one second (FEV 1 ) was 0.098 (0.111) l (p < 0.001) and in forced vital capacity (FVC) was 0.247 (0.233) l (p < 0.001). There was a small but significant fall in SaO 2 during sputum induction (p = 0.03). Conclusions-Induced sputum contains a higher proportion of viable cells than spontaneous sputum. There are no significant diVerences between the sputum samples obtained at seven minutes and at 14 minutes of hypertonic saline nebulisation. Sputum induction is safe and well tolerated in patients with COPD. (Thorax 1998;53:953-956)

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The airway epithelium is a complex physicochemical barrier that plays a pivotal role in host defense. Epithelial cells have been shown to be a rich source of several classes of modulatory compounds, of which the cytokines form the largest group and possibly play the most important role in the etiology of airway disease. Evidence suggests that there are differences in the airway epithelial cells of individuals with and without respiratory disease, both with regard to (1) their capacity to express and release different types and quantities of specific cytokines and (2) their reactivity to inhaled irritants. Consequently, it is tempting to speculate that differences in epithelial cell function are an important determinant of the predisposition to respiratory disease. However, whether the differences are a result of an intrinsic defect, an acquired property due to the disease process itself, or a combination of the two, remains to be determined. In view of advances that have been made in the understanding of the putative underlying mechanisms in airway diseases, it should be possible to formulate novel therapeutic agents in the form of specific monoclonal antibodies directed against specific proinflammatory cytokines. Mills PR, Davies RJ, Devalia JL. Airway epithelial cells, cytokines, and pollutants.

Although cigarette smoking is of paramount importance in the development of chronic obstructive pulmonary disease (COPD), only a small proportion of smokers develop the disease. We tested the hypothesis that the response of the bronchial epithelium to cigarette smoke (CS) differs in patients with COPD. Such a difference might explain in part why only some cigarette smokers develop the disease. We established primary explant cultures of human bronchial epithelial cells (HBEC) from biopsy material obtained from never-smokers who had normal pulmonary function, smokers with normal pulmonary function, and smokers with COPD, and exposed these for 20 min to CS or air. Measurements were subsequently made over a period of 24 h of transepithelial permeability and release of interleukin (IL)-1beta and soluble intercellular adhesion molecule-1 (sICAM-1). In addition, intracellular reduced glutathione (GSH) levels were measured after 24 h incubation. Exposure to CS increased the permeability of these cultures in all study groups, but the most marked effect was observed in cultures from patients with COPD (mean increase, 85.5%). The smallest CS-induced increase in the permeability was observed in HBEC cultured from smokers with normal pulmonary function (mean, 25.0%), and this was significantly lower than that of HBEC from never-smokers (mean, 53.4%) (P<0.001). Compared with exposure to air, exposure to CS led to a significantly increased release of these mediators from cultures of the never-smoker group (mean 250.0% increase in IL-1beta and mean 175.3% increase in sICAM-1 24 h after exposure) and COPD group (mean 383.3% increase in IL-1beta and mean 97.4% increase in sICAM-1 24 h after exposure). In contrast, CS exposure did not influence significantly the release of either mediator from the cells of smokers with normal pulmonary function. Levels of intracellular GSH were significantly higher in cultures of HBEC derived from smokers, both those with normal pulmonary function and those with COPD, compared with cultures from healthy never-smokers. Exposure to CS significantly decreased the concentration of intracellular GSH in all cultures. However, the fall in intracellular GSH was significantly greater in cells from patients with COPD (mean 72.9% decrease) than in cells from never-smokers (mean 61.4% decrease; P = 0.048) or smokers with normal pulmonary function (mean 43.9% decrease; P = 0.02). These results suggest that whereas smokers with or without COPD demonstrate increased levels of GSH within bronchial epithelial cell cultures, those with COPD have a greater susceptibility to the effects of CS in reducing GSH levels and causing increased permeability and release of proinflammatory mediators such as IL-1beta and sICAM-1.

Although studies of nitrogen dioxide (NO2) inhalation, in both animals and humans, have demonstrated that this agent can cause epithelial cell damage and inflammation of the airway epithelium, the mechanisms underlying these effects are not well understood. We have cultured human bronchial epithelial cells, as explant cultures from surgical tissue, and studied these firstly from their ability to constitutively synthesize specific proinflammatory cytokines and then investigated the effect of exposure to NO2 on the generation of these cytokines. Constitutive synthesis of cytokines was evaluated by analysis of both the expression of the mRNA for interleukin (IL)-1 beta, IL-4, IL-8, granulocyte/macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma), by the polymerase chain reaction (PCR), and by immunocytochemical staining for the presence of cell-associated IL-1 beta, IL-8, GM-CSF, TNF-alpha, and IFN-gamma, using specific monoclonal and polyclonal antibodies directed towards these cytokines. Release of IL-4, IL-8, GM-CSF, TNF-alpha, and IFN-gamma following exposure to 5% CO2 in air or 400 ppb and 800 ppb NO2 for 6 h was investigated by enzyme-linked immunosorbent assay. PCR demonstrated that the human bronchial epithelial cells expressed the mRNA for IL-1 beta, IL-8, GM-CSF, and TNF-alpha but not for IL-4 and IFN-gamma. Immunocytochemical staining confirmed the presence of endogenous IL-1 beta, IL-8, GM-CSF, and TNF-alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

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