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Biomedical subjects

W MacNee

Publications and source records attributed to W MacNee.

At least 73 records · Page 4Linked to original sources
PubMed1998

Expression of adhesion molecules and G proteins in circulating neutrophils in chronic obstructive pulmonary disease.

We investigated the expression of adhesion molecules in circulating neutrophils (lymphocyte function-associated antigen-1 [LFA-1], Mac-1, and L-selectin) and endothelial cells (soluble intercellular adhesion molecule-1[sICAM-1]) in 23 patients with stable chronic obstructive pulmonary disease (COPD), 18 subjects with exacerbated COPD, and 23 healthy volunteers. Also, in these circulating neutrophils, we assessed the expression of two G protein subunits (Galphas and Galphai1/2). Compared with control subjects, patients with stable COPD showed increased expression of Mac-1 (p < 0.001) and lower levels of sICAM-1 (p = 0.002); LFA-1 and L-selectin expression was similar in patients and control subjects. During exacerbations, compared with stable patients, the expression of Mac-1 and LFA-1 was reduced (p < 0.001). Finally, the expression of Galphas (but not Galphai1/2) was also reduced (p < 0.001) in circulating neutrophils of patients with COPD, irrespective of the clinical condition of the patient. These results indicate that in patients with COPD: (1) the expression of some neutrophil adhesion molecules (Mac-1) is abnormal, and that this pattern changes during exacerbations; (2) there may be a form of endothelial dysfunction, as suggested by the low sICAM-1 levels; (3) the expression of G protein subunit (Galphas) in circulating neutrophils is downregulated, irrespective of their clinical conditions. Overall, these results indicate the presence of significant systemic abnormalities in COPD.

Analysis of Variance↗
PubMed1998

Hydrogen peroxide-induced epithelial injury: the protective role of intracellular nonprotein thiols (NPSH).

Injury to the alveolar region is a hallmark of the adult respiratory distress syndrome (ARDS) whereas injury to the epithelium of the conducting airways is a characteristic of asthma. Reactive oxygen species have been implicated as mediators of lung injury in both of these conditions. We have investigated the relationship between intracellular nonprotein thiols (NPSH), and the release of the cytosolic enzyme lactate dehydrogenase (LDH), as an index of cell injury, following treatment of the human alveolar type II-like epithelial cell line (A549 cells) or the human bronchial epithelial cell line (16HBE140-) with hydrogen peroxide (H2O2). We have also assessed the protective effects of pre-incubation of both of these cells lines with H2O2 or enhancement of intracellular NPSH against H2O2-induced cell injury. Exposure of A549 and 16HBE140- cells to H2O2 (0.1 mM and 1 mM respectively for 16 h) produced the release of 40% of the total cellular LDH. H2O2 exposure produced an initial dose-dependent decrease in NPSH in A549 cells, with a subsequent increase to above control values. 16HBE140- cells also showed a dose-dependent decrease in NPSH following exposure to H2O2. Pretreatment of A549 cells with 0.1 mM H2O2 followed by subsequent exposure to H2O2 did not protect against H2O2-induced LDH release in this epithelial cell line. Pre-incubation with 2 mM N-acetylcysteine (NAC) increased NPSH but not intracellular reduced glutathione and resulted in total inhibition of H2O2-induced LDH release in both cell types. Pretreatment with reduced glutathione protected both cell types against the injurious effects of H2O2, whereas glutathione monethyl ester (GSHMEE) only partially protected A549 cells and had no effect in 16HBE140- cells. Intracellular cysteine levels were increased in both cell lines following NAC exposure but not sufficiently to account for the increase in NPSH levels. These observations raise the possibility that a critical concentration of nonprotein thiols may be necessary to protect pulmonary epithelial cells against hydrogen peroxide-induced injury.

Acetylcysteine↗
PubMed1998

A comparison of three methods of measuring 99mTc-DTPA lung clearance and their repeatability.

The lung clearance of technetium-99m diethylenetriamine penta-acetic acid (99mTc-DTPA) is a measure of respiratory epithelial permeability. Many factors may contribute to the wide range of normal values, including the method of correction for background activity. The aim of this study was to compare three methods of analysis, including their repeatability. 99mTc-DTPA lung clearance imaging was performed on eight nonsmokers (age 32+/-2 yrs, forced expiratory volume in one second (FEV1) 102.8+/-3.3% predicted yrs, mean+/-SEM and seven smokers (age 46+/-4 yrs, p<0.01, versus nonsmokers; FEV1 88.9+/-8.9%, p<0.05 versus nonsmokers) on two occasions each. The smokers were asked to refrain from smoking for 12 h. An uncorrected analysis was compared with two methods corrected for recirculating background activity using an intravenous correction and inter-renal and shoulder background regions of interest. The uncorrected method gave higher mean values for 50% lung clearance of 99mTc-DTPA (t50) values than the inter-renal (p<0.001) and shoulder (p<0.001) methods of correction in nonsmokers and the inter-renal method gave lower values than the shoulder-corrected method (p<0.05). In smokers there was no difference. There were no differences in mean t50 values obtained on two separate visits. There was no difference in the repeatability of the three methods of analysis. The three methods of analysis produced comparable results with no differences in repeatability.

Adult↗
PubMed1998

Neutrophil chemokines in bronchoalveolar lavage fluid and leukocyte-conditioned medium from nonsmokers and smokers.

Polymorphonuclear neutrophils (PMN) have been implicated in the pathogenesis of emphysema. The chemokines interleukin-8(IL-8), growth-related oncogene (GRO-alpha) and extractable nuclear antigen (ENA)-78 may be involved in the increased numbers of PMN in smokers' airspaces. The levels of these cytokines in bronchoalveolar lavage fluid (BALF) and bronchoalveolar lavage leukocyte conditioned medium (LCM), along with BALF PMN numbers in 12 smokers who abstained for 12 h (chronic smoking) or continued to smoke until I h before study (acute smoking) and seven nonsmokers were compared. Neutrophils in BALF increased in acute (1.96+/-0.53%, 0.99+/-0.32x10(6) cells) compared with chronic smokers (0.59+/-0.25%, 0.61+/-0.24x10(6) cells, p<0.05 nonsmokers) and nonsmokers (0.79+/-0.29%, 0.05+/-0.01x 10(6) cells, p<0.05). There were no differences in IL-8 or GRO-alpha in BALF between smokers and nonsmokers. ENA-78 levels were lower in smokers (p=0.006). There was no difference in IL-8, GRO-alpha or ENA-78 in LCM from unstimulated cells in smokers versus nonsmokers. After stimulation with lipopolysaccharide (LPS) 10 ng mL(-1), IL-8 release in acute smokers (p=0.04) and GRO-alpha release in smokers (p=0.009) were significantly higher than in nonsmokers. Following stimulation with LPS 100 ng.mL(-1), GRO-alpha release was higher in smokers (p=0.03) and increased further in acute smokers (p=0.02 versus nonsmokers, p=0.04 versus chronic smokers) and ENA-78 release increased in smokers (p=0.02 versus non-smokers). In conclusion, influx of polymorphonuclear neutrophils into smokers' airspaces is an acute phenomenon and neutrophil chemokine release from mixed bronchoalveolar lavage leukocytes is influenced by cigarette smoking and endotoxins.

Adult↗
PubMed1997

The adequacy of oxygenation in patients with hypoxic chronic obstructive pulmonary disease treated with long-term domiciliary oxygen.

Survival in patients with hypoxic chronic obstructive pulmonary disease (COPD) is improved by long-term oxygen therapy (LTOT). Such patients are known to desaturate during activity and at night. The aim of this study was to assess the adequacy of oxygenation in patients with COPD receiving LTOT. Oxygen saturation (SaO2) was measured at home over 24 h in 20 patients with hypoxic COPD receiving LTOT. Eleven had arterial oxygen partial pressure values (PaO2) > or = 8 kPa (Group 1) and nine had PaO2 < 8 kPa (Group 2), at rest, breathing oxygen. There was no difference in SaO2 during the day and night when breathing oxygen. In Group 1, SaO2 was > 90% for 78 +/- 24% of the 24-h period. Four patients spent between 75 and 90%, and three spent < 75% of the 24-h period with SaO2 > 90%. In Group 2, SaO2 was < 90% for 69 +/- 27% of the 24-h period (P = 0.02). Two patients spent between 75 and 90%, and four spent < 75% of the 24-h period with SaO2 > 90%. Measurements of SaO2 over 24 h in patients with hypoxic COPD, while breathing oxygen, add further information to arterial blood gas sampling on the adequacy of oxygenation, and reveal inadequate oxygenation in many patients.

Aged↗
PubMed1997

Attenuation of oxidant/antioxidant imbalance during treatment of exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: An oxidant/antioxidant imbalance is thought to occur in patients with chronic obstructive pulmonary disease (COPD). It has recently been shown that during exacerbations of COPD the antioxidant capacity and protein sulfhydryls of plasma are lower and the levels of products of lipid peroxidation are higher than in age matched healthy subjects. The aims of this study were to confirm these data and to measure the time course of these changes. METHODS: The plasma Trolox equivalent antioxidant capacity (TEAC), protein sulfhydryls, and products of lipid peroxidation were measured throughout the course of treatment in 13 patients who presented with an acute exacerbation of COPD. RESULTS: TEAC values (mmol/l) were low on admission (mean 0.67, 95% confidence interval (CI) 0.32 to 0.88; p < 0.05) and had increased by discharge (0.98, 95% CI 0.88 to 1.2; p < 0.05) but still remained lower than in healthy subjects (1.33, 95% CI 1.11 to 1.65). There was also restoration of plasma protein sulfhydryl levels (mmol/l) from admission (0.32, 95% CI 0.20 to 0.43) to discharge (0.49, 95% CI 0.42 to 0.62, p < 0.001) to levels similar to those in healthy subjects (0.52, 95% CI 0.43 to 0.65). Products of lipid peroxidation, measured as thiobarbituric acid-malondialdehyde adducts (mumol/l), were significantly higher (2.08, 95% CI 1.8 to 2.5) than in control subjects (1.3, 95% CI 0.85 to 1.32; p < 0.01) and returned to normal values by the time of discharge (1.2, 95% CI 0.88 to 1.29). CONCLUSIONS: These data confirm the presence of a profound oxidant/antioxidant imbalance in the blood of patients with acute exacerbations of COPD which returns towards normal values during the course of treatment.

Adrenergic beta-Agonists↗
PubMed1997

Nebulized glutathione induces bronchoconstriction in patients with mild asthma.

To assess the effects on bronchial responsiveness of nebulized glutathione (GSH), one of the most efficient scavengers of oxidant substances in the airways, we studied eight patients with mild asthma (FEV1, 88 +/- 11% predicted [SD]) in a randomized, double-blind, cross-over, placebo-controlled fashion. Bronchial challenge was measured using both FEV1 and total pulmonary resistance (Rrs) by the forced oscillation technique. Patients received nebulized GSH (600 mg with 4 ml of 0.9% sodium chloride) or placebo (identical saline solution) over a period of 25 min, 1 wk apart. Placebo provoked subclinical mild bronchoconstriction (changes from baseline: FEV1, -1%; Rrs, +17%); by contrast, GSH caused major airway narrowing (changes from baseline: FEV1, -19%; Rrs, +61%) and induced cough (four patients) or breathlessness (three patients). Differences between placebo and GSH after challenge were also noticeable in both FEV1 (p = 0.03) and Rrs (p = 0.02). Neither osmolarity (660 mosm.kg-1) nor pH (3.0) of the GSH solution accounted for these effects. Nebulized salbutamol (5.0 mg) given before the GSH challenge blocked GSH-induced bronchoconstriction. Furthermore, GSH-induced FEV1 falls were inversely correlated with metabisulfite bronchoprovocation (provocative dose [PD20], 1.49 +/- 1.83 mumol) but not with methacholine challenge. The detrimental effects of nebulized GSH on the airway bronchial tone in patients with mild asthma strongly suggests bronchoconstriction provoked by sulfite formation.

Adult↗
PubMed1997

Measurement of CT lung density in patients with chronic asthma.

Evidence for the presence of emphysema in patients with asthma is controversial. We have previously shown that decreased lung density, measured by computed tomographic (CT) scanning, preoperatively, correlates with morphometric measurements of microscopic emphysema in subsequently resected lungs. The aim of this study was to compare CT lung density, in 17 patients with chronic asthma (forced expiratory volume in one second (FEV1) 1.98 (SD 0.77) L), 17 patients with chronic bronchitis and emphysema (FEV1 0.97 (0.56) L) and seven normal subjects (FEV1 3.5 (034) L). All subjects underwent CT scanning of the lungs and respiratory function testing within 2 days of each other. In five of the asthmatic patients a CT scan was performed on two occasions before and after treatment with nebulized bronchodilator. In a different group of five asthmatics these measurements were performed at the end of and 6 weeks after an exacerbation. The mean value of the lowest fifth percentile of the CT lung density in the patients with chronic obstructive pulmonary disease (COPD) was -942 (SD 36) Hounsfield units (HU), in the 17 asthmatic patients was -912 (34) HU, and in normal subjects was -880 (13). Despite a significant increase in peak expiratory flow rate from 266 (SD 102) to 406 (83) L x s(-1) (p<0.02) following nebulized beta2-agonist in five patients with chronic asthma, there was no significant change in CT lung density (p>0.05) Our study indicates that at least some patients with chronic, stable asthma develop a reduction in computed tomography lung density, similar to that in patients with emphysema.

Acute Disease↗
PubMed1997

In vivo and in vitro proinflammatory effects of particulate air pollution (PM10).

Epidemiologic studies have reported associations between fine particulate air pollution, especially particles less than 10 mm in diameter (PM10), and the development of exacerbations of asthma and chronic obstructive pulmonary disease. However, the mechanism is unknown. We tested our hypothesis that PM10 induces oxidant stress, causing inflammation and injury to airway epithelium. We assessed the effects of intratracheal instillation of PM10 in rat lungs. The influx of inflammatory cells was measured in bronchoalveolar lavage (BAL). Airspace epithelial permeability was assessed as total protein in bronchoalveolar lavage fluid (BALF) in vivo. The oxidant properties of PM10 were determined by their ability to cause changes in reduced glutathione (GSH) and oxidized glutathione (GSSG). We also compared the effects of PM10 with those of fine (CB) and ultrafine (ufCB) carbon black particles. Six hours after intratracheal instillation of PM10, we noted an influx of neutrophils (up to 15% of total BAL cells) in the alveolar space, increased epithelial permeability, an increase in total protein in BALF from 0.39 +/- 0.01 to 0.62 +/- 0.01 mg/ml (mean +/- SEM) and increased lactate dehydrogenase concentrations in BALF. An even greater inflammatory response was observed after intratracheal instillation of ufCB, but not after CB instillation. PM10 had oxidant activity in vivo, as shown by decreased GSH in BALF (from 0.36 +/- 0.05 to 0.25 +/- 0.01 nmol/ml) after instillation. BAL leukocytes from rats treated with PM10 produced greater amounts of nitric oxide, measured as nitrite (control 3.07 +/- 0.33, treated 4.45 +/- 0.23 mM/1 x 10(6) cells) and tumor necrosis factor alpha (control 21.0 +/- 3.1, treated 179.2 +/- 29.4 unit/1 x 10(6) cells) in culture than BAL leukocytes obtained from control animals. These studies provide evidence that PM10 has free radical activity and causes lung inflammation and epithelial injury. These data support our hypothesis concerning the mechanism for the adverse effects of particulate air pollution on patients with airway diseases.

Air Pollutants↗
PubMed1997

Free radical activity of PM10: iron-mediated generation of hydroxyl radicals.

The purpose of this study was to test the hypothesis that particulate matter < or = 10 microns in aerodynamic diameter (PM10) particles have the ability to generate free radical activity at their surface. We collected PM10 filters from the Edinburgh, United Kingdom, Enhanced Urban Network sampling site, removed particles from the filter, and tested their ability to cause free radical damage to supercoiled plasmid DNA. We found that the PM10 particles did cause damage to the DNA that was mediated by hydroxyl radicals, as shown by inhibition of the injury with mannitol. The PM10-associated hydroxyl radical activity was confirmed using a high-performance liquid chromatography-based assay to measure the hydroxyl radical adduct of salicylic acid. Desferrioxamine abolished the hydroxyl radical-mediated injury, which suggests that iron was involved. Analysis of PM10 filters confirmed the presence of large amounts of iron and leaching studies confirmed that the PM10 samples could release substantial amounts of Fe(III) and lesser amounts of Fe(II). To investigate the size of the particles involved in the hydroxyl radical injury, we centrifuged the suspension of PM10 to clarity, tested the clear supernatant, and found that it had all of the suspension activity. We conclude, therefore, that the free radical activity is derived either from a fraction that is not centrifugeable on a bench centrifuge, or that the radical generating system is released into solution.

Air Pollutants↗
PubMed1997

Free radical activity of industrial fibers: role of iron in oxidative stress and activation of transcription factors.

We studied asbestos, vitreous fiber (MMVF10), and refractory ceramic fiber (RCF1) from the Thermal Insulation Manufacturers' Association fiber repository regarding the following: free radical damage to plasmid DNA, iron release, ability to deplete glutathione (GSH), and activate redox-sensitive transcription factors in macrophages. Asbestos had much more free radical activity than any of the man-made vitreous fibers. More Fe3+ was released than Fe2+ and more of both was released at pH 4.5 than at pH 7.2. Release of iron from the different fibers was generally not a good correlate of ability to cause free radical injury to the plasmid DNA. All fiber types caused some degree of oxidative stress, as revealed by depletion of intracellular GSH. Amosite asbestos upregulated nuclear binding of activator protein 1 transcription factor to a greater level than MMVF10 and RCF1; long-fiber amosite was the only fiber to enhance activation of the transcription factor nuclear factor kappa B (NF kappa B). The use of cysteine methyl ester and buthionine sulfoximine to modulate GSH suggested that GSH homeostasis was important in leading to activation of transcription factors. We conclude that the intrinsic free radical activity is the major determinant of transcription factor activation and therefore gene expression in alveolar macrophages. Although this was not related to iron release or ability to deplete macrophage GSH at 4 hr, GSH does play a role in activation of NF kappa B.

Animals↗
PubMed1997

Causes of death in patients with COPD and chronic respiratory failure.

Although the factors associated with mortality, such as forced expiratory volume in one second (FEV1), arterial oxygen tension (Pa,O2) and pulmonary arterial pressure, have been well described, there is limited information on the circumstances of death in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the causes and circumstances of death in patients with COPD and chronic respiratory failure (Pa,O2 < 8.0 kPa (60 mmHg) breathing air), treated with long-term oxygen therapy (LTOT). Ten European centres participated in the study and data were collected from patients both during a period of clinical stability and at the time of death. Of the 215 patients evaluated (161 males and 54 females; aged 66 +/- 10 yrs), the major causes of death were: acute on chronic respiratory failure (38%); heart failure (13%); pulmonary infection (11%); pulmonary embolism (10%); cardiac arrhythmia (8%); and lung cancer (7%). Seventy five percent of patients died in hospital. There was no difference in the number of patients who died in the morning, afternoon and night hours. Twenty percent of the total died during sleep and in 26% death was unexpected. A lower arterial carbon dioxide tension (Pa,CO2), less oxygen usage per 24 h, and increased incidence of arrhythmias were seen in those patients who died suddenly. Drug therapy was not related to unexpected death. The majority of patients with chronic obstructive pulmonary disease on long-term oxygen therapy died from chronic or acute on chronic respiratory failure. Prevention and treatment of respiratory failure in patients with chronic obstructive pulmonary disease is likely to have the greatest impact in reducing mortality.

Aged↗
PubMed1997

Chronic obstructive pulmonary disease from science to the clinic: the role of glutathione in oxidant-antioxidant balance.

The data presented in this manuscript suggest that there is a profound change in oxidant/anti-oxidant balance in smokers and in patients with chronic obstructive pulmonary disease, particularly during exacerbations. This may be important in the pathogenesis of the condition. The antioxidant glutathione appears to be a critical protective mechanism in the distal airspace against oxidant-induced damage to epithelial cells. Studies of the regulation of antioxidants in the lungs, including glutathione, may well lead to the development of new therapeutic options to enhance the oxidant screen in the lungs, which should be useful in many conditions of lung inflammation.

Antioxidants↗
PubMed1996

Induction of gamma-glutamylcysteine synthetase by cigarette smoke is associated with AP-1 in human alveolar epithelial cells.

Increased levels of glutathione (GSH) occur in the epithelial lining fluid (ELF) of chronic cigarette smokers. Therefore we investigated the effect of cigarette smoke condensate solution (CSC) on GSH synthesis and the regulation of gamma-glutamylcysteine synthetase (gammaGCS) in human type II alveolar epithelial cells (A549). CSC exposure increased GSH levels, gammaGCS activity and gammaGCS heavy subunit (HS) mRNA, as well as increasing DNA binding of the activator protein-1 (AP-1) and the human antioxidant response element (hARE). Transfection of deletion constructs of the gammaGCS-HS promoter in a chloramphenicol acetyl transferase (CAT) reporter system revealed that an hARE, present within promoter, is not required for the CSC mediated induction. We conclude that CSC induction of gammaGCS-HS expression is associated with AP-1/AP-1-like responsive elements.

Antioxidants↗
PubMed1996

Role of oxidants/antioxidants in smoking-induced lung diseases.

An imbalance between oxidants and antioxidants has been considered in the pathogenesis of smoking-induced lung diseases, such as chronic obstructive pulmonary disease (COPD), particularly emphysema. Recent evidence indicates that increased neutrophil sequestration and activation occurs in the pulmonary microvasculature in smokers and in patients with COPD, with the potential to release reactive oxygen species (ROS). ROS generated by airspace phagocytes or inhaled directly from the environment also increase the oxidant burden and may contribute to the epithelial damage. Although much research has focused on the protease/antiprotease theory of the pathogenesis of emphysema, less attention has been paid to the role of ROS in this condition. The injurious effects of the increased oxidant burden in smokers and in patients with COPD are opposed by the lung antioxidant defences. Hence, determining the mechanisms regulating the antioxidant responses is critical to our understanding of the role of oxidants in the pathogenesis of smoking-induced lung disease and to devising future strategies for antioxidant therapy. In this article we have reviewed the evidence for the presence of an oxidant/antioxidant imbalance in smoking-induced lung disease and its relevance to therapy in these conditions.

Antioxidants↗
PubMed1996

Adverse health effects of PM10 particles: involvement of iron in generation of hydroxyl radical.

OBJECTIVES: Environmental particles < 10 microns average aerodynamic diameter (PM10) are associated with mortality, exacerbation of airways diseases, and decrement in lung function. It is hypothesised that PM10 particles, along with other pathogenic particles, generate free radicals at their surface in reactions involving iron, and that this is a factor in the pathogenicity of PM10 particles. Identification of free radical activity in PM10 and examination of the content and role of iron in this process was undertaken. METHODS: Free radical activity was detected with a supercoiled plasmid, phi X174 RF1 DNA, and measured as scission of the supercoiled DNA (mediated by free radicals) by scanning laser densitometry. The role of the hydroxyl radical was confirmed by the use of the specific scavenger mannitol, and the role of iron investigated with the iron chelator desferrioxamine-B (DSF-B). Iron released from PM10 particles at pH 7.2 and pH 4.6 (to mimic conditions on the lung surface and in macrophage phagolysosomes, respectively) was assessed spectrophotometrically with the Fe++ chelator ferrozine and the Fe+ + + chelator DSF-B. RESULTS: PM10 particles showed significant free radical activity by their ability to degrade supercoiled DNA. A substantial part of this activity was due to the generation of hydroxyl radicals, as shown by partial protection with mannitol. Similarly, DSF-B also conferred protection against the damage caused to plasmid DNA indicating the role of iron in generation of hydroxyl radicals. Negligible Fe++ was released at either pH 7.2 or pH 4.6 by contrast with Fe+ + +, which was released in substantial quantities at both pHs, although twice as much was released at pH 4.6. CONCLUSIONS: PM10 particles generate the hydroxyl radical, a highly deleterious free radical, in aqueous solution. This occurs by an iron dependent process and hydroxyl radicals could play a part in the pathogenicity of PM10 particles. Iron release was greatest at the pH of the lysosome (pH 4.6) indicating that iron may be mobilised inside macrophages after phagocytosis, leading to oxidative stress in the macrophages.

Air Pollutants↗
PubMed1996

Free radical activity and pro-inflammatory effects of particulate air pollution (PM10) in vivo and in vitro.

BACKGROUND: Epidemiological evidence has implicated fine particulate air pollution, particularly particles less than 10 microns in diameter (PM10), in the development of exacerbations of asthma and chronic obstructive pulmonary disease (COPD) although the mechanism is unknown. The hypothesis that PM10 particles induce oxidant stress, causing inflammation and injury to airway epithelium, was tested. METHODS: The effects of intratracheal instillation of PM10 was assessed in rat lungs (three per group). Inflammatory cell influx was measured by bronchoalveolar lavage (BAL) and air space epithelial permeability was assessed as the total protein in BAL fluid in vivo. The oxidant properties of PM10 particles were determined by their ability to cause damage to plasmid DNA and by changes in reduced (GSH) and oxidised (GSSG) glutathione. The effects of PM10 particles were compared in some experiments with those of fine (CB) and ultrafine (ufCB) carbon black particles. RESULTS: Six hours after intratracheal instillation of PM10 there was an influx of neutrophils (up to 15% of total cells in BAL fluid) into the alveolar space, increased epithelial permeability, the mean (SE) total protein in the BAL fluid increasing from 0.39 (0.01) to 0.62 (0.01) mg/ml, and increased lactate dehydrogenase (LDH) concentrations in the BAL fluid. An even greater inflammatory response was seen following intratracheal instillation of ufCB but not following CB instillation. PM10 particles had free radical activity in vivo, as shown by a decrease in GSH levels in the BAL fluid from 0.36 (0.05) to 0.25 (0.01) nmol/ml following instillation. The free radical activity of PM10 was confirmed in vitro by its ability to deplete supercoiled plasmid DNA, an effect which could be reversed by mannitol, a specific hydroxyl radical scavenger. BAL fluid leucocytes from rats treated with PM10 produced greater amounts of nitric oxide (NO), measured as nitrite (control 3.07 (0.33), treated 4.45 (0.23) microM/1 x 10(6) cells), and tumour necrosis factor alpha (control 21.0 (3.1), treated 179.2 (29.4) units/l x 10(6) cells) in culture than those obtained from control animals. Since the PM10 preparation was contaminated with small amounts of filter fibres due to the extraction process, the effects of instillation of filter fibres alone was assessed. These studies showed that filter fibres did not account for the proinflammatory and injurious effects of the PM10 suspension. CONCLUSIONS: These findings provide evidence that PM10 has free radical activity and causes lung inflammation and epithelial injury. These data support the proposed hypothesis for the mechanism by which particulate air pollution causes adverse effects in patients with airways diseases.

Air Pollutants↗