Effect of methacholine challenge on cellular composition of sputum induction

The Effects of a Transgelin-2 Agonist Administered at Different Times in a Mouse Model of Airway Hyperresponsiveness

Airway hyperresponsiveness (AHR) is one of the most important features of asthma. Our previous study showed that inhaled transgelin-2 agonist, TSG12, effectively reduced pulmonary resistance in a mouse model of asthma in a dose-dependent manner. However, the optimal administration time of TSG12 to reduce AHR and the pharmacological effects are still unclear. In this study, the effects of TSG12 inhalation before and during AHR occurrence were examined. The results showed that the pulmonary resistance was reduced by 57% and the dynamic compliance was increased by 46% in the TSG12 Mch group (atomize TSG12 10 min before methacholine, p < 0.05 vs. model). The pulmonary resistance was reduced by 61% and the dynamic compliance was increased by 47% in the TSG12 + Mch group (atomize TSG12 and methacholine together, p < 0.05 vs. model). Quantitative real-time PCR showed that the gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 6.4-, 1.9-, and 2.8-fold, respectively, in the TSG12 Mch group. The gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 3.2-, 1.4-, and 1.9-fold, respectively, in the TSG12 + Mch group. The results suggested that TSG12 effectively reduces pulmonary resistance when TSG12 inhalation occurred both before and during AHR occurrence. Gene expression levels of transgelin-2 and myosin light chain were significantly up-regulated when TSG12 inhalation occurred before AHR occurrence. This study may provide a basis for the administration time of TSG12 for asthma treatment in the future.

Possible involvement of acetylcholine-mediated inflammation in airway diseases

Inhaled bronchodilator treatment with a long acting muscarinic antagonist (LAMA) reduces symptoms and the risk of exacerbations in COPD and asthma. However, increasing evidence from cell culture and animal studies suggests that anti-muscarinic drugs could also possess anti-inflammatory effects. Recent studies have revealed that acetylcholine (ACh) can be synthesized and released from both neuronal and non-neuronal cells, and the released ACh can potentiate airway inflammation and remodeling in airway diseases. However, these anti-inflammatory effects of anti-muscarinic drugs have not yet been confirmed in COPD and asthma patients. This review will focus on recent findings about the possible involvement of ACh in airway inflammation and remodeling, and the anti-inflammatory effect of anti-muscarinic drugs in airway diseases. Clarifying the acetylcholine-mediated inflammation could provide insights into the mechanisms of airway diseases, which could lead to future therapeutic strategies for inhibiting the disease progression and exacerbations.

Clinical, physiological and anti-inflammatory effect of montelukast in patients with cough variant asthma

BACKGROUND

Cough variant asthma (CVA) is a phenotype of asthma presenting solely with coughing, characterized by airway hyperresponsiveness, eosinophilic inflammation and a cough response to bronchodilators. Leukotriene receptor antagonists (LTRAs) are antiasthma medications with anti-inflammatory and bronchodilatory properties. Although LTRAs exert antitussive effects in CVA, the mechanisms involved are unknown.

OBJECTIVES

This study aimed to clarify the antitussive mechanisms of LTRAs in CVA patients.

METHODS

We prospectively observed the effect of montelukast (10 mg) daily for 4 weeks in 23 consecutive nonsmoking adults with anti-inflammatory treatment-naive CVA. We evaluated, before and after treatment, the cough visual analogue scale (VAS), pulmonary function (spirometry and impulse oscillation), methacholine airway responsiveness, cough receptor sensitivity, expressed by the concentration of capsaicin inducing 2 or more (C2) and 5 or more (C5) coughs, sputum eosinophil counts and levels of inflammatory mediators, including cysteinyl leukotrienes, leukotriene B(4), prostaglandin (PG) D(2), PGE(2), PGF(2)(α) and thromboxane B(2). We compared the baseline characteristics of the patients based on the symptomatic response to montelukast, defined as a decrease in the cough VAS of >25% (n = 15) or ≤25% (n = 8).

RESULTS

Montelukast significantly decreased the cough VAS (p = 0.0008), sputum eosinophil count (p = 0.013) and cough sensitivity (C2: p = 0.007; C5: p = 0.039), whereas pulmonary function, airway responsiveness and sputum mediator levels remained unchanged. Multivariate analysis showed that a better response to montelukast was associated solely with younger age (p = 0.032).

CONCLUSION

The antitussive effect of montelukast in CVA may be attributed to the attenuation of eosinophilic inflammation rather than its bronchodilatory properties.

Effects of budesonide and formoterol on allergen-induced airway responses, inflammation, and airway remodeling in asthma

BACKGROUND

Combining inhaled corticosteroids with long-acting beta(2)-agonists results in improved asthma symptom control and fewer asthma exacerbations compared with those seen after inhaled corticosteroids alone. However, there are limited data as to whether these beneficial effects are due to enhanced anti-inflammatory actions or whether such combination therapies affect airway remodeling in patients with asthma.

OBJECTIVE

We sought to determine the effects of inhaled budesonide/formoterol combination therapy versus inhaled budesonide alone or inhaled placebo on allergen-induced airway responses, airway inflammation, and airway remodeling.

METHODS

Fourteen asthmatic subjects with dual responses after allergen inhalation were included in this prospective, randomized, double-blind, 3-period crossover study. Outcomes included early and late asthmatic responses, changes in airway responsiveness, sputum eosinophilia measured before and after allergen challenge, numbers of airway submucosal myofibroblasts, and smooth muscle area measured before and after study treatment.

RESULTS

Allergen-induced sputum eosinophilia was significantly reduced by combination treatment to a greater extent than by budesonide alone. Allergen inhalation resulted in a significant increase in submucosal tissue myofibroblast numbers and produced a significant decrease in percentage smooth muscle area. Combination therapy, but not budesonide monotherapy, significantly attenuated these changes in myofibroblast numbers and smooth muscle area.

CONCLUSIONS

The effects on allergen-induced changes in sputum eosinophils, airway myofibroblast numbers, and smooth muscle seen with combination therapy suggest that the benefits associated with this treatment might relate to effects on airway inflammation and remodeling. The attenuation of early asthmatic responses and airway hyperresponsiveness by combination treatment was likely due to the known functional antagonistic effect of formoterol.

Airway responsiveness and inflammation in adolescent elite swimmers

BACKGROUND

Whereas increased airway hyperresponsiveness (AHR) and airway inflammation are well documented in adult elite athletes, it remains uncertain whether the same airway changes are present in adolescents involved in elite sport.

OBJECTIVE

To investigate airway responsiveness and airway inflammation in adolescent elite swimmers.

METHODS

We performed a cross-sectional study on adolescent elite swimmers (n = 33) and 2 control groups: unselected adolescents (n = 35) and adolescents with asthma (n = 32). The following tests were performed: questionnaire, exhaled nitric oxide (FeNO), spirometry, induced sputum, methacholine challenge, eucapnic voluntary hyperpnea (EVH) test, and exhaled breath condensate pH.

RESULTS

There were no differences in FeNO, exhaled breath condensate pH, cellular composition in sputum, or prevalence of AHR to either EVH or methacholine among the 3 groups. When looking at airway responsiveness as a continuous variable, the swimmers were more responsive to EVH than unselected subjects, but less responsive to methacholine compared with subjects with asthma. We found no differences in the prevalence of respiratory symptoms between the swimmers and the unselected adolescents. There was no difference in FeNO, cellular composition of sputum, airway reactivity, or prevalence of having AHR to methacholine and/or EVH between swimmers with and without respiratory symptoms.

CONCLUSION

Adolescent elite swimmers do not have significant signs of airway damage after only a few years of intense training and competition. This leads us to believe that elite swimmers do not have particularly susceptible airways when they take up competitive swimming when young, but that they develop respiratory symptoms, airway inflammation, and AHR during their swimming careers.

Association between neutrophilic airway inflammation and airflow limitation in adults with asthma

BACKGROUND

There is debate about the mechanisms of persistent airflow limitation in patients with asthma. Chronic inflammation is assumed to be important, although there is limited and contradictory information about the relationship between airway inflammation and postbronchodilator FEV1.

METHODS

We have assessed the cross-sectional relationship between prebronchodilator and postbronchodilator FEV1 and measures of airway inflammation after allowing for the effects of potential confounding factors. Multivariate analysis was performed on data collected from 1,197 consecutive patients with asthma seen at the respiratory outpatient clinic at Glenfield Hospital between 1997 and 2004. Relationships between induced sputum total neutrophil and differential eosinophil cell counts, and prebronchodilator and postbronchodilator lung function were examined.

RESULTS

Sputum total neutrophil but not differential eosinophil count was associated with lower postbronchodilator FEV1. Both differential eosinophil and total neutrophil count were associated with lower prebronchodilator FEV1. These effects were independent after adjustment for age, smoking, ethnicity, asthma duration, and inhaled corticosteroid use. A 10-fold increase in neutrophil count was associated with a 92 mL reduction (95% confidence interval, 29 to 158; p = 0.007) in postbronchodilator FEV1.

CONCLUSIONS

In this large heterogeneous population of adults with asthma, we have shown that prebronchodilator FEV1 is associated with neutrophilic and eosinophilic airway inflammation, whereas sputum total neutrophil counts alone are associated with postbronchodilator FEV1. This supports the hypothesis that neutrophilic airway inflammation has a role in the progression of persistent airflow limitation in asthma and raises the possibility that this progression and the development of COPD share a common mechanism.

Structural changes and airway remodelling in occupational asthma at a mean interval of 14 years after cessation of exposure

BACKGROUND

Occupational asthma (OA) may cause alterations of airways with inflammation and remodelling after cessation of exposure. Although the long-term clinical, functional and induced sputum sequelae have been examined in workers removed from exposure, the long-term pathological outcomes are unknown.

OBJECTIVE

We aimed to investigate whether airway inflammation and remodelling were present in bronchial biopsies of subjects with prior OA but without evidence of persisting asthma at a mean interval of 14 years after cessation of exposure.

METHODS

Ten clinically and functionally asymptomatic subjects with a prior diagnosis of OA were recruited and underwent bronchoscopy, bronchoalveolar lavage and bronchial biopsy. Comparisons were made with biopsies from normal control subjects. Epithelial detachment, epithelial metaplasia, mucous gland and airway smooth muscle (ASM) areas as well as the distance between the epithelium and ASM were measured by image analysis. The amount of collagen present was assessed by van Gieson staining. The numbers of TGF-beta1- and eosinophil cationic protein (ECP)-positive cells were evaluated by specific immunostaining.

RESULTS

Statistically significant increases were found in the numbers of TGF-beta1- and ECP-positive cells and in the amount of subepithelial fibrosis present in the biopsies of subjects with prior OA compared with control biopsies. The distance between the epithelium and ASM was significantly reduced in the OA group. Increases in epithelial metaplasia, ASM mass, mucous gland numbers, collagen deposition and eosinophilia in the OA group were not statistically significant. There was no evidence of ongoing inflammation in the group with prior OA as assessed by the number of T lymphocytes present.

CONCLUSION

Some aspects of airway inflammation and remodelling persist in subjects with prior OA long after cessation of exposure even in the absence of clinical, sputum and functional abnormalities. These findings are relevant to the assessment of long-term sequelae in subjects with OA when reviewed after cessation of exposure.

Effect of histamine and adenosine 5'-monophosphate provocation on sputum neutrophils and related mediators in atopic patients

BACKGROUND

Airway hyperresponsiveness and inflammation can be noninvasively studied by bronchial provocation using direct (histamine) or indirect (adenosine 5'-monophosphate [AMP]) stimuli and induced sputum.

OBJECTIVE

To report on the immediate effects of histamine and AMP challenge on induced sputum neutrophil counts and related mediator levels.

METHODS

We performed a single-masked, randomized, placebo-controlled, 3-way, crossover, methodological study in 14 atopic patients (median age, 25 years; 8 males; mean +/- SD forced expiratory volume in 1 second, 99% +/- 5%) without anti-inflammatory medication use. At baseline, sputum induction was performed. Bronchial challenges with AMP, histamine, or placebo were performed 48 hours later. Thirty minutes after challenge, sputum induction was performed again. Challenge periods in each patient were separated by more than 2 weeks. Sputum cells and the mediators leukotriene B4, interleukin 8, myeloperoxidase, and albumin were quantified.

RESULTS

Comparing median challenge-induced relative changes in cells and mediators, neither histamine nor AMP challenge altered the induced sputum neutrophil counts (histamine, 2.7%; AMP, 2.95%; placebo, -2%; P > .07 for all), interleukin 8 levels (histamine, 2.4 ng/mL; AMP, -3.8 ng/mL; placebo, -0.2 ng/mL; P > .06), leukotriene B4 levels (histamine, -4.8 pg/mL; AMP, 3 pg/mL; placebo, 6 pg/mL; P > .08), or myeloperoxidase levels (histamine, 0.16 microg/mL; AMP, 0 microg/mL; placebo, -0.03 microg/mL; P > .07). Sputum albumin levels were increased after histamine challenge compared with AMP and placebo challenge (P < .01 for both).

CONCLUSIONS

Histamine and AMP provocation have no major effects on induced neutrophil counts and related mediator levels in atopic patients, whereas histamine challenge induces plasma leakage. Potential interactions of noninvasive methods to evaluate airway reactivity and inflammation should be carefully considered.

Comparison of sputum induction using inhaled methacholine or hypertonic saline

OBJECTIVES

Hypertonic saline is recommended for the induction of sputum to assess airway inflammation. Methacholine is most commonly used to assess airway responsiveness. The aim of this study was to compare sputum induction by methacholine and hypertonic saline challenges, and the subsequent inflammatory cell differential counts.

METHODOLOGY

Subjects (n = 56) underwent inhaled hypertonic saline (4.5% for < or = 15 min without bronchodilator pretreatment) and methacholine (maximum cumulative dose 4 micromol) challenges 1 week apart, in random order. Sputum was processed, and on cytospins stained with May-Grunwald-Giemsa, a total of 400 inflammatory plus squamous cells were counted to obtain a differential cell count.

RESULTS

A satisfactory sputum sample was obtained from 29 subjects following hypertonic saline and also from 10 subjects following methacholine. For these 10 subjects, the mean percent macrophages, neutrophils, eosinophils, and lymphocytes were similar after methacholine (64%, 26%, 7% and 1%) or hypertonic saline (67%, 26%, 6% and 1%). The results were similar for squamous cells (42% and 45%) and when asthmatics and nonasthmatics were compared separately.

CONCLUSIONS

Inhaled methacholine has a much lower yield of sputum induction compared with hypertonic saline. However, the differential sputum cell count is similar following both challenge agents.

Provocation with adenosine 5'-monophosphate, but not methacholine, induces sputum eosinophilia

INTRODUCTION

Bronchial hyper-responsiveness is usually measured with direct stimuli such as methacholine (MCh) or histamine. Adenosine 5'-monophosphate (AMP), which acts indirectly via the secondary release of mediators, is another stimulus to measure bronchial hyper-responsiveness.

AIM

To investigate whether provocation with inhaled AMP itself initiates an inflammatory response resulting in an influx of eosinophils into the airway lumen.

METHODS

We have included 21 non-smoking atopic asthmatic subjects (mean FEV1 101% predicted, mean age 34 years). Each subject performed three sputum inductions on different days, at least seven days apart: one without previous provocation, one hour after PC20 methacholine, and one hour after PC20 AMP.

RESULTS

After provocation with AMP, but not methacholine, the percentage of sputum eosinophils increased significantly (from 1.9+/-0.5% to 4.5+/-1% (P<0.01) and 1.9+/-0.5% (P=0.89)). No changes in the percentages of neutrophils, lymphocytes, macrophages, or bronchial epithelial cells were found.

CONCLUSION

A provocation test with AMP leads to an increased percentage of sputum eosinophils. This observation cannot be explained by a non-specific response of the airways to a vigorous bronchoconstriction, since methacholine had no effect on inflammatory cells.

Airway Inflammation after Cessation of Exposure to Agents Causing Occupational Asthma

Subjects with occupational asthma (OA) generally present asthma symptoms and airway hyperresponsiveness after cessation of exposure. We hypothesized that they are also left with airway inflammation. We assessed 133 subjects with OA at a mean interval of 8.7 years (0.5-20.8 years) after cessation of exposure by questionnaire, airway caliber, and responsiveness to methacholine. Satisfactory samples of induced sputum were obtained from 98 subjects. We defined three groups of subjects: (1) cured: normalization of the concentration of methacholine provoking a 20% decrease in FEV1 (PC20), (2) improved: increase in PC20 by 3.2-fold or more but PC20 still abnormal, and (3) not improved: no significant change in PC20. In all, 9/28 subjects (32.1%) with no improvement versus 6/56 (10.7%) subjects with partial and complete improvements had sputum eosinophils equal to or greater than 2% and 11/28 (39.3%) subjects versus 11/56 (19.6%) subjects showed sputum neutrophils equal to or greater than 61%. Levels of interleukin-8 and of the neutrophil-derived myeloperoxidase were significantly more elevated in sputum of subjects with no improvement. Those in the cured or improved groups had a significantly longer time lapse since diagnosis and a higher PC20 at the time of diagnosis. We conclude that failure to improve after cessation of exposure to an agent causing OA is associated with airway inflammation at follow-up.

Smoking and atopy as determinants of sputum eosinophilia and bronchial hyper-responsiveness in adults with normal lung function

Data concerning the determinants of sputum eosinophilia and bronchial hyper-responsiveness (BHR) in large cohorts of individuals with normal lung function are limited. Here, we assessed the occurrence of sputum eosinophilia and BHR and identified the risk factors for these variables in two populations living in North Karelia, Finland, and in Pitkäranta, the Republic of Karelia, Russia. These areas are geographically adjacent, but differ, however, fundamentally in major cultural, socioeconomical and lifestyle aspects. The study population comprised 790 Finns and 387 Russian, aged 25-54 years, who were randomly enrolled from the population registers. A methacholine challenge test to measure BHR was successfully performed in 581 (74%) Finns and 307 (79%) Russians with virtually normal lung function (FEV1 > 70% of predicted). Of these, induced sputum samples were obtained from 41% of the Finns and from 67% of the Russians. The proportion of current smokers was 27% among the former and 42% among the latter. Sputum eosinophilia was assessed using a semi-quantitative method, and total concentrations of sputum eosinophilic cationic protein (ECP) and myeloperoxidase (MPO) were measured using an immunoassay. Risk factors for BHR and sputum eosinophilia were identified with a regression analysis. The prevalence of sputum eosinophilia was 22% among the Finns and 19% among the Russians, and the respective figures for BHR were 14% and 13%. The median ECP concentration in sputum was significantly higher among the Russians as compared with the Finns (P<0.001), whereas for MPO, the difference did not achieve significance. Current smoking was significantly associated with both sputum eosinophilia and BHR in Russia (OR 3.1, 95% CI 1.2-7.6 for sputum eosinophilia, 2.8, 1.3-6.1 for BHR) and with BHR in Finland (2.1, 1.3-3.7). Atopy showed a tendency to be another risk factor for BHR in Finland (1.6, 0.98-2.6). In conclusion, sputum eosinophilia and BHR occurred commonly among the Finns and the Russians with normal lung function. Current smoking was significantly associated with BHR in both countries and additionally with sputum eosinophilia in Russia. Atopy was identified as a risk factor, albeit of borderline significance, for BHR in Finland only, suggesting that there may be differences in the aetiology and nature of BHR between the two countries.

Effects of low dose fluticasone/salmeterol combination on surrogate inflammatory markers in moderate persistent asthma

BACKGROUND

Noninvasive surrogate markers provide valuable information on the asthmatic inflammatory process. We wished to examine the effects of low dose fluticasone/salmeterol combination on different commonly used inflammatory markers in moderate persistent asthma.

METHODS

Twenty-five moderate persistent atopic asthmatics were enrolled of whom 20 completed an open label study. Following an initial 4 week steroid washout period in which patients took salmeterol 50 microg dry powder inhaler 1 puff BD, they received the addition of fluticasone as fluticasone 100 microg/salmeterol 50 microg combination dry powder inhaler 1 puff BD for the next 2 weeks. Exhaled nitric oxide, spirometry, methacholine PD20, sputum/blood eosinophils and sputum/serum eosinophil cationic protein (ECP) were measured following the salmeterol only and fluticasone/salmeterol combination treatment periods.

RESULTS

Compared to salmeterol alone (i.e. after the steroid washout), the use of fluticasone/salmeterol combination conferred significant improvements (P < 0.05) in all surrogate markers of inflammation apart from serum ECP. Geometric mean fold changes were 4.3-fold/1.3-fold for sputum/blood eosinophils, 2.2-fold/1.2-fold for sputum/serum ECP, 2.3-fold for methacholine PD20 and 1.8-fold for exhaled nitric oxide.

CONCLUSIONS

Surrogate markers apart from serum ECP may be used as a guide to evaluate the anti-inflammatory effects of low dose inhaled corticosteroids. Sputum markers tend to be more sensitive than blood when assessing the anti-inflammatory response.

Effects of montelukast and budesonide on airway responses and airway inflammation in asthma

Inhaled corticosteroids are effective antiinflammatory therapy for asthma; however, they do not completely abolish allergen-induced airway inflammation. Leukotriene modifiers attenuate both early and late allergen responses and have antiinflammatory properties. We reasoned that treatment with budesonide and montelukast in combination might provide greater antiinflammatory effects than either drug alone, and the purpose of this study was to compare the effects of treatment with budesonide and montelukast, alone or in combination, on outcome variables after allergen inhalation. Ten subjects with asthma with dual responses after allergen inhalation were included in this randomized, double-blind, crossover study. Outcomes included early and late asthmatic responses, and changes in airway responsiveness and sputum eosinophilia, measured before and after challenge. Treatment with montelukast attenuated the maximal early asthmatic response compared with placebo (p < 0.001) and budesonide (p = 0.002). Both budesonide and montelukast, alone and in combination, attenuated the maximal late asthmatic response compared with placebo (p < 0.01). Budesonide and montelukast, alone and in combination, afforded protection against allergen-induced airway hyperresponsiveness (p < 0.05), although the treatment effect of budesonide was greater than that of montelukast (p < 0.05). Treatment with budesonide and montelukast, alone and in combination, also attenuated allergen-induced sputum eosinophilia. Thus, montelukast and budesonide attenuated allergen-induced asthmatic responses, airway hyperresponsiveness, and sputum eosinophilia, although combination treatment did not provide greater antiinflammatory effects than either drug alone.

Asymptomatic worsening of airway inflammation during low-dose allergen exposure in asthma: protection by inhaled steroids

Asthma is a chronic inflammatory disease that persists even during adequate therapy and asymptomatic episodes. We questioned whether "silent" chronic allergen exposure can induce and maintain airway inflammation and whether this still occurs during regular treatment with inhaled steroids. Twenty-six patients with house dust mite allergy and mild asthma (dual responders) participated in a parallel, double-blind study. All patients inhaled a low-dose of allergen on 10 subsequent working days (Days 1-5, 8-12). They were treated with 400 micro g budesonide once daily (n = 13) or placebo (n = 13) from Days -3 to 19. At baseline (Day -6) and on Days 5, 12, and 19 we measured the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)), and percent eosinophils, interleukin (IL)-5/interferon-gamma messenger RNA ratio (in sputum cells by real-time reverse transcription-polymerase chain reaction [RT-PCR]), and eosinophilic cationic protein (ECP) in induced sputum. Symptoms, peak expiratory flow (PEF), FEV(1), and exhaled nitric oxide (NO) were recorded repeatedly during the study. In the placebo group, repeated low-dose allergen exposure resulted in a significant increase in sputum eosinophils (p = 0.043), ECP (p = 0.011), IL-5/IFN-gamma messenger RNA ratio (p = 0.04), and in exhaled NO (p = 0.001), without worsening of symptoms, PEF, or baseline FEV(1) (p > 0.07). In the budesonide group, the changes in PC(20), sputum ECP, and exhaled NO were significantly different as compared with the placebo group (p < 0.03). We conclude that repeated low-dose allergen exposure in asthma can lead to airway inflammation without worsening of symptoms, which can be prevented by inhaled steroid treatment. This suggests that antiinflammatory therapy is beneficial during allergen exposure, even during asymptomatic episodes.

Airway neutrophil inflammation in nonasthmatic patients with food allergy

BACKGROUND

Patients with food allergy (FA) have been recently shown to develop bronchial hyperresponsiveness (BHR), despite the absence of any concomitant asthmatic manifestation. In order to explain this observation, we sought to examine the presence of a bronchial inflammation in induced sputum of nonasthmatic patients with FA.

METHODS

Twelve nonasthmatic patients with FA (urticaria, digestive symptoms, anaphylaxis) were included in the study. Results were compared to these obtained from eight asthmatic patients without food allergy and eight healthy controls. Diagnosis of FA was based on double-blind placebo-controlled challenge. Sputum cells and fluid-phase eosinophil cationic protein (ECP), myeloperoxidase (MPO) and interleukin-8 (IL-8) were measured in induced sputum. BHR was evaluated using methacholine inhalation.

RESULTS

Sputum from asthmatics, in comparison with the sputum of healthy subjects and patients with FA contained a higher proportion of eosinophils and higher levels of ECP (< 0.001). In marked contrast, patients with FA exhibited an increased proportion of neutrophils and IL-8 in comparison with asthmatics and controls (P < 0.05 for neutrophils and P < 0.001 for IL-8). There was a significant correlation between sputum neutrophils and IL-8 (r = 0.68, P < 0.001). MPO levels were not different between the groups. There was a trend toward higher levels of IL-8 and ECP in food allergic patients with BHR in comparison with patients with FA without BHR.

CONCLUSION

Our results demonstrate that a subclinical neutrophil airway inflammation is present in patients with food allergy free of clinical respiratory symptoms and that IL-8 may be an important mediator of this neutrophilia.

Evidence for systemic rather than pulmonary effects of interleukin-5 administration in asthma

BACKGROUND

Interleukin 5 (IL-5) has an important role in mobilisation of eosinophils from the bone marrow and in their subsequent terminal differentiation. A study was undertaken to determine whether inhaled and intravenous IL-5 could induce pulmonary eosinophilia and bronchial hyperresponsiveness (BHR) independently of these effects.

METHODS

Nine mild asthmatics received inhaled (15 microg) or intravenous (2 microg) IL-5 or placebo in random order in a double blind, crossover study. Blood samples were taken before and at 0.5, 1, 2, 3, 4, 5, 24, and 72 hours following IL-5 or placebo, and bronchial responsiveness (PC(20) methacholine) and eosinophil counts in induced sputum were determined.

RESULTS

Serum IL-5 levels were markedly increased 30 minutes after intravenous IL-5 (p=0.002), and sputum IL-5 levels increased 4 and 24 hours after inhaled IL-5 (p<0.05). Serum eotaxin was raised 24 hours after intravenous IL-5 but not after inhaled IL-5 or placebo. Blood eosinophils were markedly reduced 0.5-2 hours after intravenous IL-5 (p<0.05), followed by an increase at 3, 4, 5, and 72 hours (p<0.05). Sputum eosinophils rose significantly in all three groups at 24 hours but there were no differences between the groups. Bronchial responsiveness was not affected by IL-5.

CONCLUSION

The effects of IL-5 appear to be mainly in the circulation, inducing peripheral mobilisation of eosinophils to the circulation without any effect on eosinophil mobilisation in the lungs or on bronchial responsiveness.

Safety and reproducibility of sputum induction in asthmatic subjects in a multicenter study

The safety of sputum induction and the reproducibility of measurements in induced sputum in multicenter studies is unknown. We examined the safety of sputum induction in a two-visit, six-center study in 79 subjects with moderate to severe asthma (mean +/- SD FEV(1) 71 +/- 12% predicted, 67% taking inhaled corticosteroids). In addition, we compared the reproducibility of markers of inflammation in induced sputum with the reproducibility of the FEV(1) and the methacholine PC(20). The FEV(1) decreased > or = 20% from the postbronchodilator baseline in 14% of all subjects and in 25% of subjects whose initial prebronchodilator baseline was 40 to 60% of predicted. All subjects responded promptly to additional albuterol treatment, and no subject developed refractory bronchoconstriction requiring treatment other than reversal of bronchospasm in the study laboratory. The reproducibility of measurements of the eosinophil percentage, eosinophil cationic protein, tryptase, and methacholine PC(20) were similar (concordance correlation coefficients of 0.74, 0.81, 0.79, and 0.74, respectively), without any significant among-center effect. We conclude that sputum induction can be performed safely in subjects with moderate to severe asthma in multicenter clinical trials when carried out under carefully monitored conditions. Importantly, we demonstrate that measurement of markers of inflammation in induced sputum is as reproducible as methacholine PC(20) and should prove useful in the assessment of airway inflammation in multicenter clinical trials.

Eosinophil influx into the airways in patients with exercise-induced asthma

Exercise-induced asthma is a common phenomenon, the mechanism of which is undetermined. Eosinophils have been suggested as playing a role in its occurrence. We studied the effect of exercise-induced asthma on the cellular and mediator composition of spontaneously obtained sputum. Twenty-five patients with bronchial asthma were investigated by studying sputum spontaneously obtained before and following challenge. One group with (n=9) and one without (n=9) exercise-induced asthma performed exercise challenge. A third group (n=7) performed methacholine challenge. The sputum was analysed using Giemsa staining for differential cell count, measuring eosinophil cationic proteins and mixtures of leukotrienes (D4, E4 and C4) in the liquid phase using ELISA. The group with exercise-induced asthma had a mean drop of 23.7+/-7.4% in FEV1, significantly (P=0.001) higher than the group without it. Following challenges, there were significant increases in sputum eosinophils only in the group with exercise-induced asthma (from 8.1+/-13.9% to 18.3+/-20.2%, P=0.0017) and not in control groups (from 0.9+/-0.9% to 1.5+/-15%) or in those who had methacholine challenge (from 23.6+/-27.2% to 22.3+/-23.8%). Eosinophil cationic proteins did not change significantly in any group. In the liquid phase of the sputum, the amount of leukotrienes increased following exercise in six of the seven patients with exercise-induced asthma in whom it was measured. The influx of eosinophils to the airway in patients who develop exercise-induced asthma can be partially explained by the leukotrienes in the airways of those patients.

Noninvasive measurement of airway inflammation using exhaled nitric oxide and induced sputum. Current status and future use

The recent use of IS and the analysis of exhaled mediators such as NO are important steps forward in our ability to noninvasively assess airway inflammation without the need to resort to bronchoscopy. Exhaled NO and IS are complementary techniques that provide different information (Table 1). Induced sputum can provide knowledge regarding the cells and mediators participating in the inflammatory response, but is time consuming and expensive. Exhaled NO measurement is performed simply and quickly, and is a nonspecific marker of an inflammatory process. The initial capital costs of equipment for NO analysis are high, however. Once the problems of standardized collection and oropharyngeal contamination have been dealt with, BC may also prove to be an additional tool for the assessment of airway inflammation. It is likely that the next 10 years will see the establishment of these noninvasive tools for the clinical assessment of airway inflammation and oxidative stress, and change the entire way we manage asthma.

Induced sputum cell counts in healthy adults

Induced sputum cell counts provide a relatively noninvasive method to evaluate the presence, type, and degree of inflammation in the airways of the lungs. Their interpretation requires a knowledge of normal values from a healthy population. The objective was to examine the total and differential cell counts in induced sputum from a sample of healthy adults. A total of 118 healthy nonsmoking adults were studied. None had asthma or airflow obstruction (negative history, FEV(1) >/= 80% predicted, ratio of FEV(1) to vital capacity [FEV(1)/VC] >/= 80%, methacholine PC(20) >/= 16 mg/ml). Forty-six were atopic. Sputum induction produced an adequate sample in 96 subjects [53 males, mean age (range) 36 (18 to 60) yr]. The expectorate was processed within 2 h; sputum was selected, treated with dithiothreitol, filtered, and examined in a hemocytometer for total cell count and viability and on Wright-stained cytospins for a differential cell count. The mean, median (90th percentile) total cell count was 4.1, 2.4 (9.7) x 10(6) cells/g and cell viability was 69.6, 72.0 (89.7)%. The proportions of eosinophils were 0.4, 0.0 (1.1)%, neutrophils 37.5, 36.7 (64.0)%, macrophages 58.8, 60.8 (86.1)%, lymphocytes 1.0, 0.5 (2.6)%, metachromatic cells 0.0, 0.0 (0.04)%, and bronchial epithelial cells 1.6, 0.3 (4.4)%, respectively. Female gender and atopy were associated with a significant elevation of eosinophils; mean difference between male/female was 0.3% (p = 0.043) and between atopic/nonatopic 0.4% (p = 0.024). This study has identified reference values for total and differential cell counts in induced sputum of healthy adults.