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.

steroids 4 and the levels are not modulated by bronchodilator therapy. 5 However, in asthmatic Background -Eosinophils in induced sputum and exhaled nitric oxide (NO) are subjects receiving inhaled corticosteroids the levels are reduced. 6 This suggests that exhaled currently used as non-invasive markers in the assessment of airway inflammation in NO may be used as a surrogate marker of airway inflammation. asthma. As both sputum eosinophils (%) and exhaled NO are raised in asthmaticThe number of sputum eosinophils and the amount of eosinophil cationic protein (ECP) subjects not receiving inhaled steroids and decreased following corticosteroid in induced sputum is associated with asthma severity. There are correlations between sputherapy, a relationship between them is plausible.tum eosinophils and sputum ECP levels with FEV 1 . 7-9 Also, sputum obtained from asthMethods -Exhaled NO was measured by chemiluminescence analyser, sputum in-matics under exacerbation contain very high numbers of eosinophils 7 10 11 but they are reduction by 3.5% saline inhalation, and bronchial responsiveness was measured as duced following corticosteroid treatment. 13This evidence justifies the validity of using PC 20 FEV 1 methacholine in 35 stable asthmatic patients using 2 agonist alone and sputum eosinophil number or sputum levels of ECP to monitor asthma severity. the correlation between these non-invasive markers of airway inflammation was Bronchial hyperresponsiveness (BHR), an exaggerated bronchoconstrictor response to instudied. Results -There were significant cor-haled stimuli, is a key feature of asthma and may be used as an indicator of asthma severity. relations between exhaled NO and PC 20 (r=−0.64), exhaled NO and sputum eos-BHR relates closely to the severity of asthma, the frequency of symptoms, and the need for inophils (%) (r=0.48), and also between sputum eosinophils (%) and PC 20 (r= treatment.14 The aim of our study was to examine the −0.40). Conclusion -The correlation between ex-relationship between exhaled NO and other non-invasive markers of inflammation, inhaled NO and PC 20 suggests that exhaled NO or the mechanisms leading to its in-cluding the number of eosinophils, the amount of ECP in induced sputum, and BHR, and also crease may contribute to airway hyperresponsiveness in asthma. Furthermore, its relationship with % predicted FEV 1 . Such a correlation would allow us to evaluate the the relationship between sputum eosinophils (%), exhaled NO, and PC 20 high-clinical utility of exhaled NO and its potential as a surrogate marker of airway inflammation light the potential use of eosinophils (%) in induced sputum and exhaled NO to in asthma. monitor the severity of asthma. (Thorax 1998;53:91-95)

The role of glucocorticoids in the treatment of chronic obstructive pulmonary disease (COPD) is controversial. We have previously described high numbers of neutrophils and high concentrations of the inflammatory cytokines interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha), and of the cell activation markers eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), myeloperoxidase (MPO), and human neutrophil lipocalin (HNL) in COPD patients as compared with controls, and have postulated that the cytokines TNF-alpha and IL-8 play a role in propagating the inflammatory response in COPD. We have now studied the effects of inhaled and oral glucocorticoids on these inflammatory indices in induced sputum. Initially, we studied the effect of a 2-wk course of inhaled budesonide (800 mg twice daily for 2 wk) in 13 patients with severe COPD (mean FDV1: 35% predicted). There was no clinical benefit in either lung function or symptom scores, and no significant change in the inflammatory indices as measured by total and differential cell counts and concentrations of TNF-alpha eosinophil activation markers ECP and EPO, and neutrophil activation markers MPO and HNL. Because the lack of anti-inflammatory effect might have been due to poor drug delivery as a result of severe airflow limitation, we undertook a study examining the antiinflammatory effect of oral prednisolone (30 mg daily for 2 wk) in patients with COPD and undertook the same measurements in 10 patients with atopic asthma. Sputum eosinophil numbers, ECP, and EPO were significantly reduced in the asthmatic patients but were not modified in COPD. This confirms the clinical impression that inhaled steroids have little antiinflammatory effect, at least in the short term in this group of patients, and suggests that the inflammatory process in COPD is resistant to the antiinflammatory effect of glucocorticoids.

Exacerbations of asthma are likely to be due to an increase in airway inflammation. We have studied noninvasive markers of airway inflammation in asthma exacerbations induced by reducing the dose of inhaled corticosteroids. Following a 2-wk run-in period, mild exacerbations were induced in subjects with stable asthma controlled with medium- to high-dose inhaled corticosteroids (beclomethasone dipropionate >/= 800 microg or equivalent daily) by switching them to budesonide 200 microg daily given from a dry-powder inhaler (Turbohaler). Fifteen subjects were enrolled and were seen twice weekly for 8 wk after steroid reduction. At each visit, exhaled nitric oxide (NO), and methacholine airway responsiveness were measured and spirometry and sputum induction were performed. Mild exacerbation was defined as: (1) a decrease in morning peak expiratory flow (PEF) of >/= 20% but < 30% on at least two consecutive days as compared with the mean for the last 7 d of the run-in period; (2) awakening on two consecutive nights because of asthma; or (3) increased use of a short-acting beta(2)-agonist to eight or more puffs daily. Eight subjects did not develop exacerbations during the 8-wk study, whereas seven subjects developed mild exacerbations at Week 4 (n = 1), Week 6 (n = 1), and Week 8 (n = 5). The only significant difference between these two groups at baseline was a higher baseline sputum eosinophil count in subjects with subsequent exacerbations (p < 0.05). The increases in sputum eosinophils and exhaled NO were correlated with decreases in airway function, including decreases in morning PEF and FEV(1). However, multiple regression analysis suggested that the change in sputum eosinophils is a potentially useful marker in predicting loss of asthma control reflected by loss of airway function.

Background-It is desirable to prescribe the minimal eVective 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 (PC 20 ) 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, PC 20 , baseline FEV 1 (% predicted), exhaled NO, and sputum eosinophilia. Results-There were significant improvements in FEV 1 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 PC 20 was improved only with 1600 µg budesonide. These results suggest that exhaled NO and PC 20 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 PC 20 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.

In a double-blind, cross-over study, we examined the effect of inhaled budesonide (800 microgram 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 beta2- 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, there was a significant correlation between eosinophils in biopsy sections, and BAL, with log PC20 methacholine. It is likely that these parameters represent different aspects of the inflammatory process, which are all inhibited by inhaled steroids.

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Background-Exhaled levels of nitric oxide (NO) are raised in asthma but the relationship between exhaled NO levels and a direct measure of airway inflammation has not been investigated in asthmatic patients treated with inhaled steroids. Methods-The relationship between exhaled NO levels, clinical measures of asthma control, and direct markers of airway inflammation were studied in patients with asthma treated with and without inhaled corticosteroids. Thirty two asthmatic patients (16 not using inhaled steroids and 16 using inhaled beclomethasone dipropionate, 400-1000 µg/day) were monitored with respect to measures of asthma control including lung function, symptom scores, medication usage, and variability of peak expiratory flow (PEF) for one month. Measurements of exhaled NO and fibreoptic bronchoscopy were performed at the end of the monitoring period. Bronchial mucosal biopsy specimens were stained with an anti-MBP antibody for quantification of eosinophils. Results-There was no significant diVerence in lung function, symptom scores, or medication usage between the two groups, but there was a significant diVerence in PEF variability (8.7 (1.2)% in steroid naive patients versus 13.6 (1.9)% in steroid treated patients, p<0.05) and exhaled NO levels (9.9 (3.5) ppb in steroid naive patients versus 13.6 (2.0) ppb in steroid treated patients, p<0.05). There was no correlation between exhaled NO and mucosal eosinophils, or between NO and conventional measures of asthma control. There was a significant correlation between mucosal eosinophils and lung function (r = -0.43, p<0.05). Conclusions-Exhaled NO levels do not reflect airway mucosal eosinophilia and these markers reflect diVerent aspects of airway inflammation. The clinical usefulness of exhaled NO needs to be determined in prospective longitudinal studies.