Showing papers by "Peter J. Barnes published in 1999"
TL;DR: The role of eosinophils in asthma is confirmed but a potential role of neutrophils in more severe asthma is suggested, as well as the role of interleukin-8 and neutrophil myeloperoxidase levels, with the highest levels in severe asthma.
Abstract: Airway inflammation in severe asthma is not well characterized but may involve neutrophils. We have compared induced sputum profiles in patients with asthma of varying severity and normal control subjects. We have also measured exhaled nitric oxide (NO) as a noninvasive marker of inflammation. Asthma severity was based on clinical features before treatment and the minimum medication required to maintain asthma control at the time of sputum induction, and classified as (1) mild: treated with inhaled beta(2)-agonist occasionally (n = 23; FEV(1), 91%; peak expiratory flow (PEF) variability, 10.5%), (2) moderate: requiring medium dose inhaled steroids to maintain control (n = 16; FEV(1), 88%; PEF variability, 9.1%), and (3) severe: despite using inhaled and oral steroids (n = 16; FEV(1), 61%; PEF variability, 36.2%). The asthmatic patients were nonsmokers with evidence of airway hyperresponsiveness or reversible airway obstruction, and free of respiratory tract infection for at least 6 wk. Sputum revealed significantly increased neutrophil numbers in severe asthma (53.0 [38.4- 73.5]%, p < 0.05) compared with mild asthma (35.4 [29.8-46.1]%) and normal control subjects (27.7 [20.6-42.2]%). Interleukin-8 (IL-8) and neutrophil myeloperoxidase (MPO) levels were increased in asthmatic patients, with the highest levels in severe asthma. Eosinophil numbers were increased in both mild and severe asthma, but interleukin-5 (IL-5) levels were highest in mild asthma, whereas eosinophil cationic protein (ECP) levels were highest in severe asthma. Exhaled NO levels were highest in asthmatic untreated with corticosteroids, but there was no significant difference between asthmatics using corticosteroids (Groups 2 and 3), regardless of clinical asthma severity. This confirms the role of eosinophils in asthma but suggests a potential role of neutrophils in more severe asthma.
861 citations
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TL;DR: It is apparent that there is a wide pleiotropy and element of redundancy in the cytokine family in that each cytokine has many overlapping functions, with each function potentially mediated by more than one cytokine.
Abstract: Cytokines are usually extracellular signalling proteins, usually less than 80 kD in size, and many are glycosylated. They are produced by many different cell types that are involved in cell-to-cell interactions acting through specific receptors on the surface of target cells. Cytokines usually have an effect on closely adjacent cells and therefore function in a predominantly paracrine fashion, although they may also act at a distance (endocrine) and may have effects on the cell of origin (autocrine). Cytokines may be regarded as a mechanism for cell-cell communication, and within this group may be included growth factors and cytokines with primarily chemoattractant properties (chemokines). They act on target cells to cause a wide array of cellular functions including activation, proliferation, chemotaxis, immunomodulation, release of other cytokines or mediators, growth and cell differentiation, and apoptosis. Cytokines were originally characterised (and named) according to some aspect of their functional activity that was initially discovered, but the cloning of the genes for these cytokines has now provided a better insight into their classification and grouping. It is apparent that there is a wide pleiotropy and element of redundancy in the cytokine family in that each cytokine has many overlapping functions, with each function potentially mediated by more than one cytokine.
The effect of an individual cytokine in the context of disease may not be easy to predict because it may be influenced by other cytokines released simultaneously from the same cell or from target cells following activation by the cytokine. The effects of cytokines are mediated by binding to cell surface high affinity receptors usually present in low numbers. The number of these receptors can be upregulated with cell activation, and there the effect of a cytokine may depend on the modulation of its receptors. Cytokines themselves may induce the expression of receptors which may …
654 citations
TL;DR: It is shown that oxidative stress is increased in asthmatic subjects as reflected by 8-isoprostane concentrations in breath condensate, which is a biomarker of oxidative stress in the airways.
Abstract: Oxidative stress has an important role in the pathogenesis of asthma. 8-Isoprostane is a prostaglandin (PG)-F2-like compound belonging to the F2 isoprostane class that is produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid. 8-Isoprostane is a biomarker of oxidative stress, and its concentration is increased in the bronchoalveolar lavage fluid of patients with interstitial lung diseases. We measured 8-isoprostane concentrations in exhaled breath condensate in healthy subjects and in patients with mild (steroid naive, n = 12), moderate (inhaled steroid treatment, n = 17), and severe asthma (oral steroid treatment, n = 15). We also measured exhaled carbon monoxide (CO) and nitric oxide (NO), which may also reflect oxidative stress in the airways. 8-Isoprostane was detectable in breath condensate of normal subjects (15.8 +/- 1.6 pg/ml), and was increased in the breath condensate of patients with mild (33.7 +/- 2.8, p < 0.001), moderate (38.3 +/- 3.7 pg/ml, p < 0. 001), and severe asthma (48.9 +/- 5.0 pg/ml, p < 0.001). There was a positive correlation (r = 0.68, p < 0.05) of 8-isoprostane with NO, but not with CO, in the exhaled air of patients with mild asthma, but not in that of patients with moderate or severe asthma. There was no correlation between 8-isoprostane and lung function tests in any group of patients. Our study shows that oxidative stress is increased in asthmatic subjects as reflected by 8-isoprostane concentrations in breath condensate.
540 citations
TL;DR: There was no clinical benefit in terms of lung function or symptom scores, and induced sputum inflammatory cells, percentage neutrophils, and IL-8 levels were unchanged, adding to previous evidence that inhaled steroids have no anti-inflammatory action in stable COPD.
Abstract: Inhaled corticosteroids are widely prescribed for the treatment of stable chronic obstructive pulmonary disease (COPD), despite lack of proven efficacy. Because COPD involves airway inflammation and probable protease-antiprotease imbalance, we examined the effect of high dose fluticasone propionate on markers of activity of both pathogenetic mechanisms. Thirteen patients with COPD were treated with fluticasone propionate (500 μ g twice a day) for 4 wk, delivered via MDI and spacer, in a double-blind crossover study. There was no clinical benefit in terms of lung function or symptom scores, and induced sputum inflammatory cells, percentage neutrophils, and IL-8 levels were unchanged. Sputum supernatant elastase activity, matrix metalloproteinase (MMP)-1, MMP-9, and the antiproteases secretory leukoprotease inhibitor (SLPI) and tissue inhibitor of metalloproteinase (TIMP)-1 were similarly unaffected by treatment. These results add to previous evidence that inhaled steroids have no anti-inflammatory action i...
401 citations
TL;DR: Exacerbations identified by the need for oral corticosteroids were associated with more symptoms and smaller changes in PEF than those identified on the basis of PEF criteria, and female sex was the main patient characteristic associated with an increased risk of having a severe exacerbation.
Abstract: The identification, prevention, and prompt treatment of exacerbations are major objectives of asthma management. We looked at change in PEF, symptoms, and use of rescue beta-agonists during the 425 severe exacerbations that occurred during a 12-mo parallel group study (FACET) in which low and high doses of budesonide with and without formoterol were compared in patients with asthma. Oral corticosteroids were prescribed for severe exacerbations, the main study end point, defined as the need for a course of oral corticosteroids (n = 311) or a reduction in morning PEF of > 30% on two consecutive days. PEF, symptoms, and bronchodilator use over the 14 d before and after the exacerbation were obtained from diary cards. Exacerbations were characterized by a gradual fall in PEF over several days, followed by more rapid changes over 2 to 3 d; an increase in symptoms and rescue beta-agonist use occurred in parallel, and both the severity and time course of the changes were similar in all treatment groups. Exacerbations identified by the need for oral corticosteroids were associated with more symptoms and smaller changes in PEF than those identified on the basis of PEF criteria. Female sex was the main patient characteristic associated with an increased risk of having a severe exacerbation. Exacerbations may be characterized predominantly by change in symptoms or change in PEF, but the pattern was not affected by the dose of inhaled corticosteroid or by whether the patient was taking formoterol.
349 citations
TL;DR: Monitoring the number of eosinophils in induced sputum may be the most accurate guide to establish the minimum dose of inhaled steroids needed to control inflammation, however, this requires further studies involving a larger number of patients.
Abstract: BACKGROUND—It is desirable to prescribe the minimal effective dose of inhaled steroids to control asthma. To ensure that inflammation is suppressed whilst using the lowest possible dose, a sensitive and specific method for assessing airway inflammation is needed.
METHODS—The usefulness of exhaled nitric oxide (NO), sputum eosinophils, and methacholine airway responsiveness (PC20) for monitoring airway inflammatory changes following four weeks of treatment with an inhaled corticosteroid (budesonide via Turbohaler) were compared. Mild stable steroid naive asthmatic subjects were randomised into two double blind, placebo controlled studies. The first was a parallel group study involving three groups receiving either 100 µg/day budesonide (n = 8), 400 µg/day budesonide (n = 7), or a matched placebo (n = 6). The second was a crossover study involving 10 subjects randomised to receive 1600 µg budesonide or placebo. The groups were matched with respect to age, PC20, baseline FEV1 (% predicted), exhaled NO, and sputum eosinophilia.
RESULTS—There were significant improvements in FEV1 following 400 µg and 1600 µg budesonide (11.3% and 6.5%, respectively, p<0.05). This was accompanied by significant reductions in eosinophil numbers in induced sputum (0.7 and 0.9 fold, p<0.05). However, levels of exhaled NO were reduced following each budesonide dose while PC20 was improved only with 1600 µg budesonide. These results suggest that exhaled NO and PC20 may not reflect the control of airway inflammation as accurately as the number of eosinophils in sputum. There were dose dependent changes in exhaled NO, sputum eosinophils, and PC20 to inhaled budesonide but a plateau response of exhaled NO was found at a dose of 400 µg daily.
CONCLUSION—Monitoring the number of eosinophils in induced sputum may be the most accurate guide to establish the minimum dose of inhaled steroids needed to control inflammation. This, however, requires further studies involving a larger number of patients.
265 citations
TL;DR: The effect of inhaled budesonide on lung function and various markers of airway inflammation including airway responsiveness to methacholine, exhaled nitric oxide, eosinophils in induced sputum, bronchoalveolar lavage, and airway biopsies from patients with mild asthma needing beta2- agonist therapy only is examined.
Abstract: In a double-blind, cross-over study, we examined the effect of inhaled budesonide (800 μ g twice daily via Turbohaler) on lung function and various markers of airway inflammation including airway responsiveness to methacholine (PC20), exhaled nitric oxide (NO), eosinophils in induced sputum, bronchoalveolar lavage (BAL), and airway biopsies from 14 patients with mild asthma needing β2- agonist therapy only. After inhaled steroids, there was a significant increase in FEV1 and PC20, and reduction in exhaled NO. Eosinophils in induced sputum and airway biopsy sections were also significantly decreased, although BAL eosinophil counts remained unchanged. At baseline, significant correlations were observed between exhaled NO and PC20 methacholine (r = 0.64, p < 0.05), exhaled NO and peak expiratory flow rate (PEFR) variability (r = 0.65, p < 0.05), sputum eosinophils and FEV1 (r = − 0.63, p = 0.05), and sputum eosinophils and log PC20 methacholine (r = − 0.67, p < 0.05). After treatment with inhaled steroids, t...
241 citations
TL;DR: Most of the many new therapies in development are aimed at inhibiting components of the allergic inflammatory response, but in the future there are real possibilities for the development of preventative and even curative treatments.
Abstract: Many drugs are now in development for the treatment of atopic diseases, including asthma, allergic rhinitis and atopic dermatitis. These treatments are based on improvements in existing therapies or on a better understanding of the cellular and molecular mechanisms involved in atopic diseases. Although most attention has been focused on asthma, treatments that inhibit the atopic disease process would have application to all atopic diseases, as they often coincide. Most of the many new therapies in development are aimed at inhibiting components of the allergic inflammatory response, but in the future there are real possibilities for the development of preventative and even curative treatments.
240 citations
TL;DR: The lack of correlation between DNA binding and transcriptional activation plus the fact that PP1 and genistein both inhibited kappaB-dependent transcription without affecting DNA binding activity demonstrate the existence of regulatory steps downstream of NF-kappaB DNA binding.
159 citations
TL;DR: Assessment of airway responsiveness to AMP, rather than inflammatory parameters in induced sputum, represents a sensitive method to evaluate a dose-response relationship of an inhaled corticosteroid and may have applications in evaluating other novel inhaled Corticosteroids.
Abstract: Inhaled corticosteroids decrease airway responsiveness in asthma partly through suppression of airway inflammation. We have previously demonstrated that inhaled budesonide reduced airway responsiveness to the mast cell stimulus adenosine-5 9 -monophosphate (AMP) to a threefold greater extent than to methacholine and sodium metabisulfite, suggesting that AMP responsiveness may be a more sensitive marker of airway inflammation and steroid action in order to assess a dose‐response relationship. To investigate this, we studied the effects of three doses of the novel corticosteroid ciclesonide (50 m g, 200 m g, and 800 m g) inhaled as a dry powder twice daily on airway responsiveness to AMP and inflammatory parameters in induced sputum. In a three-parallel-dose group, doubleblind, placebo-controlled, randomized, crossover study, with a washout period of 3 to 8 wk, a total of 29 patients with mild to moderate allergic asthma underwent AMP challenge and sputum induction before and after 14 d of treatment with ciclesonide or matched placebo. Compared with placebo, ciclesonide 100 m g, 400 m g, and 1,600 m g daily reduced airway responsiveness to AMP by 1.6 (95% confidence interval [CI], 2 0.1 to 3.4, not significant [NS]), 2.0 (95% CI, 0.4 to 3.6, p , 0.05), and 3.4 (95% CI, 2.3 to 4.4, p , 0.05) doubling doses, respectively, and this reduction in airway responsiveness was dose-dependent (p 5 0.039). A significant reduction in the percentage of eosinophils in induced sputum was observed after 400 m g and 1,600 m g daily ciclesonide (p , 0.05), but this was not dosedependent. Sputum eosinophil cationic protein (ECP) was significantly reduced after 400 m g daily ciclesonide only (p , 0.05). Thus, in patients with mild to moderate asthma, assessment of airway responsiveness to AMP, rather than inflammatory parameters in induced sputum, represents a sensitive method to evaluate a dose‐response relationship of an inhaled corticosteroid and may have applications in evaluating other novel inhaled corticosteroids. Taylor DA, Jensen MW, Kanabar V, Engelstatter R, Steinijans VW, Barnes PJ, O’Connor BJ. A dose-dependent effect of the novel inhaled corticosteroid ciclesonide on airway responsiveness to adenosine-5 9 -monophosphate in asthmatic patients. AM J RESPIR CRIT CARE MED 1999;160:237‐243.
143 citations
TL;DR: In Caucasians only 10–20% of chronic heavy cigarette smokers develop symptomatic COPD, suggesting that genetic factors are likely to be important in determining which cigarette smokers are at risk from developing airflow obstruction.
Abstract: Chronic obstructive pulmonary disease (COPD) is a major cause of ill health and is increasing in many parts of the world. It is one of the commonest causes of death and the only common cause of death which is increasing. COPD is characterised by a slowly progressive irreversible airflow obstruction that is due to a loss of lung elasticity resulting from parenchymal destruction and peripheral airflow obstruction. Cigarette smoking is currently a causal factor in more than 90% of patients in westernised societies, so environmental factors are clearly very important in the disease.1However, in Caucasians only 10–20% of chronic heavy cigarette smokers develop symptomatic COPD, suggesting that genetic factors are likely to be important in determining which cigarette smokers are at risk from developing airflow obstruction. Furthermore, some patients develop airflow obstruction at an earlier age, again suggesting that genetic factors may determine the progression of COPD. Patients who have a genetic deficiency in the anti-protease α1-antitrypsin (α1-AT) have a very high risk of developing emphysema at an early age if they smoke, indicating the importance of genetic factors in some patients with COPD. Despite the clinical importance of COPD, relatively few studies have searched for genetic factors using modern molecular genetic techniques.
There may also be differences in the prevalence of COPD in different ethnic groups, but these are difficult to separate from lifestyle factors. For example, the prevalence of COPD is apparently low in China and this cannot be entirely accounted for by a lower tobacco consumption.2 Anecdotally, COPD is uncommon in Chinese living in the USA which suggests that there may be genetic differences in the factors that protect against COPD. In Hawaii, the prevalence of COPD in Japanese-Americans smoking more than 20 cigarettes daily was 7.9% compared with 16.7% …
TL;DR: Although the major action of racemic beta(2 )-agonists on the airways is relaxation of airway smooth muscle, these drugs have several other effects mediated through beta( 2 )-adrenergic receptors expressed on other cell types that may contribute to the efficacy of beta(1)-agonists in relieving asthma symptoms.
Abstract: Although the major action of racemic beta(2 )-agonists on the airways is relaxation of airway smooth muscle, these drugs have several other effects mediated through beta(2 )-adrenergic receptors expressed on other cell types. These additional actions of beta(2 )-agonists may contribute to the efficacy of beta(2 )-agonists in relieving asthma symptoms. beta(2 )-agonists inhibit plasma exudation in the airways by acting on beta(2 )-receptors on postcapillary venule cells. They inhibit the secretion of bronchoconstrictor mediators from airway mast cells and inhibit effects on release of mediators from eosinophils, macrophages, T-lymphocytes, and neutrophils. In addition, beta(2 )-agonists may have an inhibitory effect on the release of neuropeptides from sensory nerves. The effect of beta(2 )-agonists on mediator release from structural cells in the airways such as epithelial cells is uncertain. Despite all of these inhibitory effects on inflammatory cells in vitro, beta(2 )-agonists do not appear to reduce the chronic inflammation of asthma. Desensitization is more readily seen in inflammatory cells than in airway smooth muscle cells and may account for this discrepancy. Corticosteroids may increase expression of beta(2 )-receptors in inflammatory cells to overcome the desensitization in response to chronic beta(2 )-agonist exposure.
TL;DR: The data suggest that the anti‐inflammatory properties of a range of glucocorticoids relate to their ability to transrepress rather than transactivate genes.
Abstract: 1. Glucocorticoids are highly effective in controlling chronic inflammatory diseases, such as asthma and rheumatoid arthritis, but the exact molecular mechanism of their anti-inflammatory action remains uncertain. They act by binding to a cytosolic receptor (GR) resulting in activation or repression of gene expression. This may occur via direct binding of the GR to DNA (transactivation) or by inhibition of the activity of transcription factors such as AP-1 and NF-kappaB (transrepression). 2. The topically active steroids fluticasone propionate (EC50= 1.8 x 10(-11) M) and budesonide (EC50=5.0 x 10(-11) M) were more potent in inhibiting GM-CSF release from A549 cells than tipredane (EC50 = 8.3 x 10(-10)) M), butixicort (EC50 = 3.7 x 10(-8) M) and dexamethasone (EC50 = 2.2 x 10(-9) M). The anti-glucocorticoid RU486 also inhibited GM-CSF release in these cells (IC50= 1.8 x 10(-10) M). 3. The concentration-dependent ability of fluticasone propionate (EC50 = 9.8 x 10(-10) M), budesonide (EC50= 1.1 x 10(-9) M) and dexamethasone (EC50 = 3.6 x 10(-8) M) to induce transcription of the beta2-receptor was found to correlate with GR DNA binding and occurred at 10-100 fold higher concentrations than the inhibition of GM-CSF release. No induction of the endogenous inhibitors of NF-kappaB, IkappaBalpha or I-kappaBbeta, was seen at 24 h and the ability of IL-1beta to degrade and subsequently induce IkappaBalpha was not altered by glucocorticoids. 4. The ability of fluticasone propionate (IC50=0.5 x 10(-11) M), budesonide (IC50=2.7 x 10(-11) M), dexamethasone (IC50=0.5 x 10(-9) M) and RU486 (IC50=2.7 x 10(-11) M) to inhibit a 3 x kappaB was associated with inhibition of GM-CSF release. 5. These data suggest that the anti-inflammatory properties of a range of glucocorticoids relate to their ability to transrepress rather than transactivate genes.
TL;DR: Exposure to 200 ppb ozone leads to a neutrophil inflammatory response in normal and asthmatic subjects but no changes in exhaled NO or nitrite levels.
Abstract: BACKGROUND Nitric oxide (NO) may have a role in the pathophysiology of tissue injury in response to inhaled ozone in animals. METHODS A double blind, randomised, placebo controlled, crossover study was undertaken to investigate the effects of inhaled ozone in 10 normal and 10 atopic asthmatic volunteers. Subjects were exposed to 200 ppb ozone or clean air for four hours with intermittent exercise, followed by hourly measurement of spirometric parameters and exhaled NO for four hours. Nasal NO and methacholine reactivity were measured and exhaled breath condensate and induced sputum samples were collected four and 24 hours after exposure. RESULTS Exposure to ozone caused a fall in forced expiratory volume in one second (FEV 1 ) of 7% in normal subjects (p CONCLUSIONS Exposure to 200 ppb ozone leads to a neutrophil inflammatory response in normal and asthmatic subjects but no changes in exhaled NO or nitrite levels.
TL;DR: Neutrophils and cytokines associated with neutrophil chemotaxis and activation may contribute to the pathogenesis of non-asthmatic chronic dry cough.
Abstract: BACKGROUND—The pathogenesis of non-asthmatic chronic dry cough remains unclear.
METHODS—A study was undertaken to determine whether airway inflammation could be a contributing factor by analysing inflammatory cells and cytokines in induced sputum from 19 patients with chronic dry cough of varying aetiology, excluding asthma and bronchiectasis, and from 10 normal controls. The associated causes for the chronic cough were post-nasal drip (n = 5), gastro-oesophageal reflux (n = 4), and idiopathic (n = 10). All patients had an enhanced cough reflex to capsaicin.
RESULTS—Sputum neutrophilia (median (interquartile range)) was found in the patients with chronic cough (59.4 (27.1)%) compared with the normal controls (28.4 (22.0)%; p<0.01, 95% CI 11.3 to 42.2). Sputum levels of interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α) were also significantly increased compared with normal controls (0.57 (1.08) and 0.25 (0.72) ng/ml; p<0.05 (95% CI 0.05to 1.75) for IL-8; 48.3 (34.4) and 12.6 (33.6) pg/ml, p<0.01 (95% CI 8.8 to 69.8) for TNF-α).
CONCLUSION—Neutrophils and cytokines associated with neutrophil chemotaxis and activation may contribute to the pathogenesis of non-asthmatic chronic dry cough.
TL;DR: There is a driving need to develop new and effective treatments for COPD and a new long-acting anticholinergic bronchodilator, tiotropium bromide, is now in advanced clinical trials as a once daily dry powder inhaler.
Abstract: There is a driving need to develop new and effective treatments for COPD. Bronchodilators are now the mainstay of symptomatic therapy and a new long-acting anticholinergic bronchodilator, tiotropium bromide, is now in advanced clinical trials as a once daily dry powder inhaler. Several inflammatory mediators are involved in the chronic neutrophilic inflammation that typifies COPD, including leukotriene B(4) and interleukin 8, for which specific receptor antagonists have been developed. Since the inflammatory process in COPD is essentially steroid resistant, new antiinflammatory treatments are needed. Drugs that may be effective include phosphodiesterase 4 inhibitors, NF-kappaB inhibitors, and interleukin 10. Inhibition of proteases is another approach and inhibitors of neutrophil elastase, cathepsins, and matrix metalloproteases are now in clinical development. Supply of endogenous antiproteases, such as alpha(1)-antitrypsin and secretory leukocyte protease inhibitors as recombinant proteins or by gene transfer, is also being explored. In future drugs that may stimulate alveolar repair might be developed, including retinoid receptor agonists and hepatic growth factor. Future directions will include earlier detection of disease, gene profiling to identify which smokers are at risk of COPD, and the development of noninvasive surrogate markers to monitor disease activity in order to monitor new therapies. Identification of genes that confer a risk for COPD in smokers may identify novel targets for drug development. Barnes PJ. Novel approaches and targets for treatment of chronic obstructive pulmonary disease.
TL;DR: Elevated levels of exhaled CO in diabetes may reflect HO-1 induction and oxidative stress, and the measurement of CO may be a new tool for disease monitoring.
TL;DR: Exhaled nitric oxide may be a useful addition to BAL cell counts in disease monitoring and there was a significant correlation between exhaled NO and lymphocyte cell count in patients with FASSc.
TL;DR: High exhaled CO concentrations in patients with cystic fibrosis may reflect induction of HO-1, a product of heme degradation by heme oxygenase 1 which is induced by inflammatory cytokines and oxidants, which may be clinically useful in the management and monitoring of oxidation and inflammatory mediated lung injury.
Abstract: BACKGROUND—Inflammation, oxidative stress, and recurrent pulmonary infections are major aggravating factors in cystic fibrosis. Nitric oxide (NO), a marker of inflammation, is not increased, however, probably because it is metabolised to peroxynitrite. Exhaled carbon monoxide (CO), a product of heme degradation by heme oxygenase 1 (HO-1) which is induced by inflammatory cytokines and oxidants, was therefore tested as a non-invasive marker of airway inflammation and oxidative stress.
METHODS—Exhaled CO and NO concentrations were measured in 29 patients (15 men) with cystic fibrosis of mean (SD) age 25 (1) years, forced expiratory volume in one second (FEV1) 43 (6)%, 14 of whom were receiving steroid treatment.
RESULTS—The concentration of exhaled CO was higher in patients with cystic fibrosis (6.7 (0.6) ppm) than in 15 healthy subjects (eight men) aged 31 (3) years (2.4 (0.4) ppm, mean difference 4.3 (95% CI 2.3 to 6.1), p 0.05). Patients homozygous for the ΔF508 CFTR mutation had higher CO and NO concentrations than heterozygous patients (CO: 7.7 (1.8) ppm and 4.0 (0.6) ppm, respectively, mean difference 3.7 (95% CI -7.1 to -0.3), p<0.05; NO: 4.1 (0.5) ppb and 1.9 (0.7) ppb, respectively, mean difference 2.2 (95% CI -3.7 to -0.6), p<0.05).
CONCLUSIONS—High exhaled CO concentrations in patients with cystic fibrosis may reflect induction of HO-1. Measurement of exhaled CO concentrations may be clinically useful in the management and monitoring of oxidation and inflammatory mediated lung injury.
TL;DR: Exhaled CO and NO levels are elevated in asthmatic patients and are decreased after corticosteroid treatment, suggesting they may be useful as noninvasive markers of airway inflammation, and may provide complementary data for assessment of asthma control in children.
TL;DR: The data suggest that Pde isoenzymes are important in airway inflammation and that PDE inhibitors exert anti-inflammatory effects by acting on AEC.
Abstract: Epithelial cells actively participate in inflammatory airway disease by liberating mediators such as arachidonate metabolites and cytokines. Inhibition of phosphodiesterases (PDEs) may be a useful anti-inflammatory approach. The PDE isoenzyme pattern and the effects of PDE inhibition on mediator generation were analyzed in primary cultures of human and porcine airway epithelial cells (AEC) and in the bronchial epithelial cell line BEAS-2B. PDE4 and PDE5 were detected in lysates of all cell types studied. In primary cultures of human AEC, the PDE4 variants PDE4A5, PDE4C1, PDE4D2, and PDE4D3 were identified by polymerase chain reaction analysis. Evidence of the recently described PDE7 was obtained by rolipram- insensitive cyclic adenosine monophosphate (cAMP) degradation, and its presence was verified by the demonstration of PDE7 messenger RNA. Primary cultures of human airway epithelium also expressed PDE1. Enhanced epithelial cAMP levels, induced by forskolin and PDE4 inhibition, increased formation of prostaglandin E2 (PGE2), but not of interleukin (IL)-8 or 15-hydroxyeicosatetraenoic acid (15-HETE) in airway epithelial cells. Increased cyclic guanosine monophosphate levels in these cells provoked by sodium nitroprusside and the PDE5 inhibitor zaprinast reduced the PGE2 synthesis, whereas 15-HETE and IL-8 formation were unchanged. The data suggest that PDE isoenzymes are important in airway inflammation and that PDE inhibitors exert anti-inflammatory effects by acting on AEC.
TL;DR: Early and noninvasive detection of inflammation would be useful in atopic subjects because airway inflammation may be present before the onset of clinical symptoms of asthma.
Abstract: Background
Atopy is a genetically determined condition and some atopic people develop airway hyperresponsiveness and sometimes asthma later in life. Since airway inflammation may be present before the onset of clinical symptoms of asthma, early and noninvasive detection of inflammation would be useful in atopic subjects. Mediators produced by activated inflammatory cells may lead to induction of inducible nitric oxide synthase producing nitric oxide (NO) and inducible heme oxygenase releasing carbon monoxide (CO) in the airways. Both monoxides are present in exhaled air and their levels are elevated in asthma reflecting airway inflammation.
Objective
We have measured exhaled NO and CO levels in atopic and nonatopic healthy non-smoking subjects to determine whether inflammation is present in the airways.
Methods
Exhaled NO was measured by a chemiluminescence analyser and exhaled CO electrochemically and NO in asymptomatic atopic and age-matched nonatopic normal subjects.
Results
Exhaled NO and CO levels were both significantly elevated in 15 atopic subjects compared with 40 nonatopic individuals (means ± sem: 18.3 ± 3.0 p.p.b. vs 6.3 ± 0.3 p.p.b., P < 0.0001 and 4.7 ± 0.3 p.p.m. vs 2.8 ± 0.2 p.p.m., P = 0.0005, respectively).
Conclusion
Increase in exhaled monoxide levels may be an early and noninvasive marker of airway inflammation in asymptomatic atopic subjects.
TL;DR: The data indicate that the cysteinyl leukotrienes are important mediators in allergen‐induced ASM cell DNA synthesis and ASM thickening in rats, while both LTB4 and cysteiny leukOTrienes contribute to ASM Thickening and eosinophil recruitment following repeated allerGEN exposure.
Abstract: Airway smooth muscle thickening is a characteristic feature of airway wall remodelling in chronic asthma. We have investigated the role of the leukotrienes in airway smooth muscle (ASM) and epithelial cell DNA synthesis and ASM thickening following repeated allergen exposure in Brown Norway rats sensitized to ovalbumin. There was a 3 fold increase in ASM cell DNA synthesis, as measured by percentage bromodeoxyuridine (BrdU) incorporation, in repeatedly ovalbumin-exposed (4.1%, 3.6-4.6; mean, 95% c.i.) compared to chronically saline-exposed rats (1.3%, 0.6-2.1; P<0.001). Treatment with a 5-lipoxygenase enzyme inhibitor (SB 210661, 10 mg kg(-1), p.o.) and a specific cysteinyl leukotriene (CysLT1) receptor antagonist, pranlukast (SB 205312, 30 mg kg(-1), p.o.), both attenuated ASM cell DNA synthesis. Treatment with a specific leukotriene B4 (BLT) receptor antagonist (SB 201146, 15 mg kg(-1), p.o.) had no effect. There was also a significant, 2 fold increase in the number of epithelial cells incorporating BrdU per unit length of basement membrane after repeated allergen exposure. This response was not inhibited by treatment with SB 210661, pranlukast or SB 201146. A significant increase in ASM thickness was identified following repeated allergen exposure and this response was attenuated significantly by SB 210661, pranlukast and SB 201146. Rats exposed to chronic allergen exhibited bronchial hyperresponsiveness to acetylcholine and had significant eosinophil recruitment into the lungs. Treatment with SB 210661, pranlukast or SB 201146 significantly attenuated eosinophil recruitment into the lungs, whilst having no significant effect on airway hyperresponsiveness. These data indicate that the cysteinyl leukotrienes are important mediators in allergen-induced ASM cell DNA synthesis in rats, while both LTB4 and cysteinyl leukotrienes contribute to ASM thickening and eosinophil recruitment following repeated allergen exposure.
TL;DR: Patients with apparent SRA are important to identify as they require supportive treatment which should not consist of high doses of glucocorticosteroids and beta2 adrenergic agonists, and may respond to alternative treatment.
Abstract: BACKGROUND Steroid resistant asthma (SRA) represents a small subgroup of those patients who have asthma and who are difficult to manage. Two patients with apparent SRA are described, and 12 additional cases who were admitted to the same hospital are reviewed. METHODS The subjects were selected from a tertiary hospital setting by review of all asthma patients admitted over a two year period. Subjects were defined as those who failed to respond to high doses of bronchodilators and oral glucocorticosteroids, as judged by subjective assessment, audible wheeze on examination, and serial peak flow measurements. RESULTS In 11 of the 14 patients identified there was little to substantiate the diagnosis of severe or steroid resistant asthma apart from symptoms and upper respiratory wheeze. Useful tests to differentiate this group of patients from those with severe asthma appear to be: the inability to perform reproducible forced expiratory manoeuvres, normal airway resistance, and a concentration of histamine causing a 20% fall in the forced expiratory volume (FEV 1 ) being within the range for normal subjects (PC 20 ). Of the 14 subjects, four were health care staff and two reported childhood sexual abuse. CONCLUSION Such patients are important to identify as they require supportive treatment which should not consist of high doses of glucocorticosteroids and β 2 adrenergic agonists. Diagnoses other than asthma, such as gastro-oesophageal reflux, hyperventilation, vocal cord dysfunction and sleep apnoea, should be sought as these may be a cause of glucocorticosteroid treatment failure and pseudo-SRA, and may respond to alternative treatment.
TL;DR: The results suggest that glycopyrrolate bind human and guinea‐pig airway muscarinic receptors with high affinity and is suggested to be the underlying mechanism by which this drug accomplishes its long duration of action.
Abstract: In this study we have evaluated the pharmacological profile of the muscarinic antagonist glycopyrrolate in guinea-pig and human airways in comparison with the commonly used antagonist ipratropium bromide.
Glycopyrrolate and ipratropium bromide inhibited EFS-induced contraction of guinea-pig trachea and human airways in a concentration-dependent manner. Glycopyrrolate was more potent than ipratropium bromide.
The onset of action (time to attainment of 50% of maximum response) of glycopyrrolate was similar to that obtained with ipratropium bromide in both preparations. In guinea-pig trachea, the offset of action (time taken for response to return to 50% recovery after wash out of the test antagonist) for glycopyrrolate (t1/2 [offset]=26.4±0.5 min) was less than that obtained with ipratropium bromide (81.2±3.7 min). In human airways, however, the duration of action of glycopyrrolate (t1/2 [offset]>96 min) was significantly more prolonged compared to ipratropium bromide (t1/2 [offset]=59.2±17.8 min).
In competition studies, glycopyrrolate and ipratropium bromide bind human peripheral lung and human airway smooth muscle (HASM) muscarinic receptors with affinities in the nanomolar range (Ki values 0.5–3.6 nM). Similar to ipratropium bromide, glycopyrrolate showed no selectivity in its binding to the M1–M3 receptors. Kinetics studies, however, showed that glycopyrrolate dissociates slowly from HASM muscarinic receptors (60% protection against [3H]-NMS binding at 30 nM) compared to ipratropium bromide.
These results suggest that glycopyrrolate bind human and guinea-pig airway muscarinic receptors with high affinity. Furthermore, we suggest that the slow dissociation profile of glycopyrrolate might be the underlying mechanism by which this drug accomplishes its long duration of action.
British Journal of Pharmacology (1999) 127, 413–420; doi:10.1038/sj.bjp.0702573
TL;DR: It is demonstrated that human eosinophils adhere to BSA‐coated plastic by a CD11b/CD18‐dependent mechanism, which is responsible for activation of the NADPH oxidase.
Abstract: 1 Incubation of human eosinophils in BSA-coated tissue culture plates resulted in time-dependent adhesion and attendant activation of the NADPH oxidase that were both inhibited (by >85%) by blocking antibodies raised against CD11b and CD18. 2 SB 203580, an inhibitor of p38 mitogen-activated protein (MAP) kinase, did not influence adhesion but inhibited superoxide anion generation (pIC50=-6.57). 3 PP1, an inhibitor of the src-family of protein tyrosine kinases, inhibited adhesion and CD11b/CD18-mediated superoxide anion generation with similar potencies (pEC50s=-5.53 and -5.99 respectively) suggesting that inhibition of the NADPH oxidase was a direct consequence of blocking adhesion. 4 The protein kinase C (PKC) inhibitors Ro-31 8220 (broad spectrum inhibitor), GF 109203X (inhibitor of conventional and novel isoforms) and Go 6976 (inhibitor of conventional isoforms) suppressed adhesion-dependent NADPH oxidase activation (pIC50s=-6.61, -6.05 and -4.89 respectively) without affecting adhesion. Based upon the selectivity of these drugs PKCdelta and PKCepsilon are implicated in the suppression of oxidant production. 5 Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PtdIns 3-kinase), abolished superoxide anion production in adherent eosinophils (pEC50=-9.06). Similarly, CD11b/CD18-dependent adhesion was suppressed with the same potency (pEC50=-9.29) although the maximum effect did not exceed 50% implying that wortmannin also had an affect on those processes that govern adhesion-driven oxidase activation. 6 PD 098059 and piceatannol, inhibitors of MAP kinase kinase-1 and the syk tyrosine kinase respectively, had no effect on CD11b/CD18-mediated adhesion or NADPH oxidase activation. 7 The results of this study demonstrate that human eosinophils adhere to BSA-coated plastic by a CD11b/CD18-dependent mechanism, which is responsible for activation of the NADPH oxidase. Although the signalling pathway(s) utilized by CD11b/CD18 is still to be elucidated, the data presented herein implicate p38 MAP kinase, novel PKCs and PtdIns 3-kinase.
TL;DR: The long-acting beta2-agonist formoterol appears to have a mast cell-stabilizing effect in vivo in mild asthma, which is thought to cause bronchoconstriction via release of mediators from mast cells in vivo.
Abstract: Short-acting β2-agonists provide greater protection against bronchoconstriction induced by adenosine 5 ′ -monophosphate (AMP) than by direct-acting bronchoconstrictors such as histamine and methacholine. AMP is thought to cause bronchoconstriction via release of mediators from mast cells, which suggests that these drugs stabilize mast cells in vivo. This in vivo property has not yet been demonstrated for long-acting β2-agonists. We undertook a double-blind, randomized, placebo-controlled, cross-over study to investigate the effects of a single dose of formoterol inhaled via Turbuhaler (12 μ g) and of albuterol inhaled via Turbuhaler (200 μ g) on airway responsiveness to AMP and histamine in 16 subjects with mild atopic asthma. Albuterol reduced airway responsiveness to AMP and histamine by 4.1 ± 0.5 and 3.5 ± 0.4 doubling doses, respectively. In contrast, formoterol caused a greater protective effect against AMP than against histamine challenge, decreasing airway responsiveness by 6.0 ± 0.8 and 4.2 ± 0.4 ...
TL;DR: There is increased expression and activation of eosinophil PKC-ζ that correlates with late asthmatic responses recorded between 4 and 10 h postallergen challenge.
Abstract: Protein kinase (PK) C is an increasingly diverse family of enzymes that has been implicated in a range of cellular functions within the eosinophil. Using isoform-specific polyclonal antibodies, we have explored the expression of PKC isoforms in circulating eosinophils. Initial studies demonstrated the presence of the alpha, betaI, betaII, and zeta and the low-level expression of the delta, epsilon, iota, and micro isoforms but no detectable expression of the gamma, eta, and theta isoforms in both normal and asthmatic subjects. There was no difference in the total protein expression between these two groups. Subsequent studies examined the expression and activation of PKC isoforms in circulating eosinophils from asthmatic patients before and 24 h after a late asthmatic response to an inhaled allergen. Cellular fractionation showed PKC-alpha and PKC-betaII to be mainly located in the cytosol, whereas PKC-betaI was constitutively more expressed in the membrane. No changes in expression or subcellular localization of these isoforms were seen after allergen challenge. In contrast, PKC-zeta expression was increased after allergen challenge, and we demonstrated a significant PKC-zeta translocation to the membrane, in keeping with activation of the enzyme. Our results suggest that 24 h after allergen exposure of asthmatic patients, there is increased expression and activation of eosinophil PKC-zeta that correlates with late asthmatic responses recorded between 4 and 10 h postallergen challenge.
TL;DR: Antileukotrienes are the only new class of drugs to treat asthma that have been introduced in the past 25 years, but their efficacy is somewhat limited and unpredictable, as compared with that of inhaled corticosteroids.
Abstract: Over the past 10 years there have been striking improvements in the treatment of asthma, largely as a result of the earlier and more widespread use of inhaled corticosteroids. The development of new treatments for asthma has proved difficult, although several immunologic approaches are undergoing preclinical and clinical assessment.1 Antileukotrienes are the only new class of drugs to treat asthma that have been introduced in the past 25 years, but their efficacy is somewhat limited and unpredictable, as compared with that of inhaled corticosteroids. Mild asthma can be controlled in most patients by relatively low doses of inhaled corticosteroids, and . . .
TL;DR: It is shown that at low concentrations of dexamethasone, ATII cells probably contribute more annexin I to respiratory tract secretions than AMs, although at high concentrations, both cellsProbably contribute.
Abstract: Annexin I (lipocortin 1) is abundant in lung secretions. Concentrations rise after oral glucocorticoid, but the effect of inhaled budesonide on annexin I release is unknown. Extracellular annexin I...