Pattern of airway inflammation and its determinants in children with acute severe asthma

The aim of this study was to examine the relationship between sputum cell counts and clinical variables in children with an acute exacerbation of asthma. Sputum was successfully obtained from 37 of 42 children presenting to the Emergency Department with acute asthma, using ultrasonically nebulized normal saline (n = 19) or spontaneous expectoration (n = 18). Sputum portions were selected and dispersed, and total and differential cell counts were performed. Sputum supernatant was assessed for eosinophil cationic protein (ECP), interleukin (IL)-5, and IL-8. The exacerbations were of 3 inflammatory cell patterns: eosinophilic (n = 16 or 43% of total), combined eosinophilic/neutrophilic (E/N; n = 13.3 or 35% of total), or noneosinophilic (n = 8 or 22% of total). IL-5 was highest in eosinophilic exacerbations. Combined E/N exacerbations had increased mast cells (77%) and higher sputum ECP levels than eosinophilic exacerbations: 2,146 ng/mL vs. 666 ng/mL (P = 0.04). The speed of onset of the exacerbation was not related to the inflammatory cell profile. Logistic regression identified maintenance asthma treatment (odds ratio (OR), 5.9; 95% confidence interval (CI), 1.3-26.8) and lung function during the acute episode (OR, 4.0; 95% CI, 1.7-93) as significantly associated with the intensity of sputum eosinophilia. Eosinophils were lowest in children who received maintenance treatment with oral corticosteroids compared to those with no background asthma preventer therapy (P = 0.001). In conclusion, we identified three distinct patterns of airway inflammation in children with acute asthma; they included increased eosinophils, combined eosinophilic-neutrophilic infiltration, and a noneosinophilic pattern. Eosinophil degranulation was greatest with the combined eosinophilic/neutrophilic pattern of airway inflammation. Sputum eosinophils were associated with clinical severity, and background asthma therapy, but not with outcome, nor with speed of onset of exacerbations. These different inflammatory cell profiles imply different etiological agents and may require differing treatment strategies.

Presence of substance P and neurokinin 1 receptors in human sputum macrophages and U-937 cells

Tachykinins such as substance P (SP) may be involved in the pathogenesis of inflammatory airway diseases such as asthma. This study investigated the presence of SP and its receptor in the differentiated macrophage-like U-937 cell line and in macrophages from sputum induced in healthy subjects (n=8). In situ hybridization with digoxigenin-labelled sense and antisense complementary ribonucleic acid (cRNA) probes was used to determine the expression of SP and its receptor (neurokinin (NK)1 receptor). SP-immunoreactive material was detected using a rabbit anti-SP antiserum and the alkaline phosphatase anti-alkaline phosphatase technique. Beta-preprotachykinin (PPT)-I messenger ribonucleic acid (mRNA) encoding SP, was detected using in situ hybridization in differentiated U-937 cells as well as in CD45+ human leukocyte antigen (HLA) DR+ sputum macrophages. The expression of the beta-PPT-I mRNA was increased in lipopolysaccharide (LPS)-stimulated U-937 cells. SP-immunoreactive material was found in differentiated U-937 cells and in CD68+ sputum macrophages. NK1 receptor mRNA was detected in differentiated U-937 cells and sputum macrophages. Incubation of U-937 cells with SP considerably increased the expression of NK1 receptor mRNA. This study demonstrates that human monocytes/macrophages express substance P and that this expression is upregulated by lipopolysacharide. Human monocytes/macrophages also express neurokinin1 receptor messenger ribonucleic acid, suggesting an autocrine effect of substance P on these cells.

Diagnosis of left-ventricular dysfunction from induced sputum examination

We have shown that the examination of induced sputum for haemosiderin-laden macrophages is sensitive and specific for detecting raised left-sided filling pressures associated with left-ventricular dysfunction.

Kinetics of allergen-induced airway eosinophilic cytokine production and airway inflammation

Airway eosinophilia is the hallmark of asthma exacerbation. Coordination of cytokines such as interleukin (IL)-5, eotaxin and regulated on activation, normal T-cell expressed and secreted (RANTES) seem to be necessary for eosinophil extravasation including adhesion, chemotaxis, and activation. The purpose of this study was to characterize both the kinetics of allergen-induced inflammatory cell recruitment to the airways and cytokines selective for eosinophil chemotaxis, activation, or resolution. Eight atopic asthmatic individuals demonstrating a dual response to inhaled allergen completed a diluent-controlled crossover study. The subjects showed significant allergen-induced early and late airway asthmatic responses (p < 0.001), and an increase in the number of sputum eosinophils and metachromatic cells (p < 0.05). The number of eosinophils immunopositive for IL-5, eotaxin, and RANTES increased 7 h after allergen inhalation (p < 0.05), coincident with the peak number of activated eosinophils. Sputum cells immunopositive for IL-10 decreased significantly following allergen challenge (p = 0. 04), and correlated negatively with sputum eosinophils (r = -0.34, p = 0.02). This study shows that allergen-induced increases in sputum eosinophils are associated with the presence of cytokines specific for the activation and chemotaxis of eosinophils, and suggests that cooperation of eosinophilic cytokines may be important for the accumulation and regulation of activated eosinophils at the site of allergic inflammation.

A comparison of biomarkers of ozone exposure in human plasma, nasal lavage, and sputum

We examined ozone-induced upper and lower airway inflammatory responses and the concentrations of hydroxylated salicylate metabolites using nasal lavage fluid and induced sputum, in order to identify noninvasive and sensitive biomarkers for ozone exposure and effects. A time course for plasma concentration of 2, 3-dihydroxybenzoic acid (2,3-DHBA, a salicylate metabolite and an indicator for hydroxyl radical) in response to 0.12 ppm ozone was also studied. Healthy, young, nonsmoking volunteers were given acetylsalicylic acid (ASA, 975 mg) or placebo orally. Subjects were exposed to ozone (0.12 or 0.4 ppm) or filtered air in an environmental chamber for 2 h, while performing intermittent exercise. Blood was collected hourly over a 4-h period. After exposure, nasal lavage fluid was collected, and sputum was induced using hypertonic saline. Results show that in sputum the percentage of neutrophils was significantly higher after the subjects were exposed to 0.4 ppm ozone (p<.05) than after they were exposed to filtered air or 0.12 ppm ozone. The absolute number and the percentage of macrophages were significantly lower at 0.4 ppm ozone than for filtered air control or 0.12 ppm ozone. The percentage of lymphocytes in sputum was also significantly lower at 0.4 ppm ozone than for filtered air control or 0.12 ppm ozone. The sputum cellular responses to ozone were not significantly altered by ASA treatment. In nasal lavage, cell counts and differentials did not change significantly after exposure to ozone in comparison to filtered air control. The cellular data indicate an acute inflammation developed during ozone exposure in the lower respiratory tract. The concentrations of total protein and interleukin-8 and the activity of N-acetyl-beta-D-glucosaminidase (a lysosomal enzyme) in nasal lavage and sputum did not change significantly following exposure to ozone in comparison to filtered air control. Plasma 2,3-DHBA concentration increased significantly following exposure to 0.12 ppm ozone in an exposure-dependent temporal pattern. Salicylate metabolites in nasal lavage fluid and sputum did not increase significantly following exposure to ozone. There was a marked variation of 2,3-DHBA concentrations in airway fluids. Data suggest that plasma 2,3-DHBA is a sensitive marker indicating acute ozone exposure, even at an ozone concentration that causes minimal observable airway effects in healthy subjects.

Occupational asthma in a grain worker due to Lepidoglyphus destructor, assessed by bronchial provocation test and induced sputum

BACKGROUND

Occupational asthma (OA) can be a debilitating disease even when removal from the workplace is achieved. Today, the "gold standard" in the assessment of OA is the bronchial provocation test (BPT). Induced sputum is a non-invasive method of exploring airway inflammation which can provide additional information about such challenges and thus could be applied in OA diagnosis and monitoring.

METHODS

We report the study carried out in a grain worker sensitized to Lepidoglyphus destructor (Ld), who suffered from mild asthma at the workplace. Skin prick test and specific serum IgE were measured. Ld-BPT was performed, and the changes in eosinophil rates, and ECP and tryptase levels in induced sputum were studied 30 min and 18 h after Ld-BPT. We also determined the changes in nonspecific bronchial hyperresponsiveness (NSBH), given as PD20 values. To assess the specificity of the changes, we also carried out sputum induction and methacholine challenge after barley-BPT.

RESULTS

An isolated immediate response was obtained with Ld-BPT, while barley-BPT was negative. Induced sputum showed higher tryptase levels 30 min after Ld-BPT, and higher eosinophil and epithelial cell percentages and ECP levels 18 h after Ld-BPT. There was also a decrease in methacholine PD20 values after Ld-BPT. Those changes were not observed after barley-BPT.

CONCLUSIONS

The study of eosinophilic and mast-cell markers in induced sputum provides additional knowledge about the inflammatory process occurring in the airways, suggesting that the study of induced sputum should be considered in the assessment of OA.

Eosinophilic bronchitis is an important cause of chronic cough

Eosinophilic bronchitis presents with chronic cough and sputum eosinophilia, but without the abnormalities of airway function seen in asthma. It is important to know how commonly eosinophilic bronchitis causes cough, since in contrast to cough in patients without sputum eosinophilia, the cough responds to inhaled corticosteroids. We investigated patients referred over a 2-yr period with chronic cough, using a well-established protocol with the addition of induced sputum in selected cases. Eosinophilic bronchitis was diagnosed if patients had no symptoms suggesting variable airflow obstruction, and had normal spirometric values, normal peak expiratory flow variability, no airway hyperresponsiveness (provocative concentration of methacholine producing a 20% decrease in FEV(1) ([PC(20)] > 8 mg/ml), and sputum eosinophilia (> 3%). Ninety-one patients with chronic cough were identified among 856 referrals. The primary diagnosis was eosinophilic bronchitis in 12 patients, rhinitis in 20, asthma in 16, post-viral-infection status in 12, and gastroesophageal reflux in seven. In a further 18 patients a diagnosis was established. The cause of chronic cough remained unexplained in six patients. In all 12 patients with eosinophilic bronchitis, the cough improved after treatment with inhaled budesonide 400 micrograms twice daily, and in eight of these patients who had a follow-up sputum analysis, the eosinophil count decreased significantly, from 16.8% to 1.6%. We conclude that eosinophilic bronchitis is a common cause of chronic cough, and that sputum induction is important in the investigation of cough.

Airway responsiveness to methacholine: effects of deep inhalations and airway inflammation

We determined the dose-response curves to inhaled methacholine (MCh) in 16 asthmatic and 8 healthy subjects with prohibition of deep inhalations (DIs) and with 5 DIs taken after each MCh dose. Flow was measured on partial expiratory flow-volume curves at an absolute lung volume (plethysmographically determined) equal to 25% of control forced vital capacity (FVC). Airway inflammation was assessed in asthmatic subjects by analysis of induced sputum. Even when DIs were prohibited, the dose of MCh causing a 50% decrease in forced partial flow at 25% of control FVC (PD(50)MCh) was lower in asthmatic than in healthy subjects (P < 0.0001). In healthy but not in asthmatic subjects, repeated DIs significantly decreased the maximum response to MCh [from 90 +/- 4 to 62 +/- 8 (SD) % of control, P < 0.001], increased PD(50)MCh (P < 0.005), without affecting the dose causing 50% of maximal response. In asthmatic subjects, neither PD(50)MCh when DIs were prohibited nor changes in PD(50)MCh induced by DIs were significantly correlated with inflammatory cell numbers or percentages in sputum. We conclude that 1) even when DIs are prohibited, the responsiveness to MCh is greater in asthmatic than in healthy subjects; 2) repeated DIs reduce airway responsiveness in healthy but not in asthmatic subjects; and 3) neither airway hyperresponsiveness nor the inability of DIs to relax constricted airways in asthmatic subjects is related to the presence of inflammatory cells in the airways.

Fractional analysis of sequential induced sputum samples during sputum induction: evidence that different lung compartments are sampled at different time points

BACKGROUND

The effect of the duration of sputum induction on markers of inflammation in induced sputum is unknown, and the optimal duration of sputum induction for research purposes in airway disease is uncertain.

OBJECTIVE

We sought to determine whether the duration of sputum induction influences the cellular or biochemical characteristics of induced sputum.

METHODS

Induced sputum was collected sequentially at 4-minute intervals during a 20-minute sputum induction in 12 subjects with mild and moderate asthma. Each 4-minute sample was collected and analyzed separately for total and differential cell counts and for levels of eosinophil cationic protein, fibrinogen, mucin-like glycoprotein, and surfactant protein SP-A.

RESULTS

The percentages of eosinophils and neutrophils were significantly higher at the beginning of the 20-minute sputum induction than at the end, whereas the percentage of macrophages was significantly lower at the beginning than at the end. In addition, the levels of eosinophil cationic protein and mucin-like glycoprotein were significantly higher at the beginning of the 20-minute induction than at the end, whereas the level of surfactant protein SP-A was significantly lower.

CONCLUSIONS

The duration of sputum induction significantly affects the cellular and biochemical composition of induced sputum in a manner suggesting that large airways are sampled at the beginning of sputum induction, whereas peripheral airways and alveoli are sampled at later time periods. Our data demonstrate the importance of standardizing the duration of sputum induction in clinical research studies, and on the basis of these data, we have chosen 12 minutes as the optimal duration for sputum induction in asthmatic subjects.

Repeatability of allergen-induced airway inflammation

BACKGROUND

Allergen inhalation challenge is a useful clinical model to investigate the effects of asthma therapies on allergen-induced airway responses; however, the repeatability of allergen-induced airway inflammation is not known.

OBJECTIVE

The purpose of this study was to investigate the repeatability of allergen-induced increases in sputum eosinophils. This information will allow the prediction of the number of subjects required in studies evaluating asthma therapies.

METHODS

Seventeen subjects completed 2 allergen challenges using the same dose of allergen, at least 3 weeks apart. Allergen-induced airway responses were measured for 7 hours after challenge. Differential cell counts from induced sputum were determined the day before and 7 and 24 hours after challenge; methacholine PC20 was measured the day before and 24 hours after challenge.

RESULTS

The intraclass correlation coefficient for maximum percent late fall in FEV1 was 0.32 and for the area of the late response was 0.61. The sample size predicted to be necessary to observe 50% attenuation of the maximum percent late fall in FEV1 and the late area under the curve with a power of 0.95 was 9 subjects. The intraclass correlation coefficient for percent of allergen-induced sputum eosinophils was 0.60 at 7 hours and 0.53 at 24 hours after challenge. With a randomized cross-over study design, the sample size predicted to be necessary to observe 50% attenuation of allergen-induced percent of eosinophils with a power of 0.95 was 5 subjects.

CONCLUSION

Allergen inhalation challenge with measurements of sputum eosinophils is a noninvasive and reliable method for evaluating the anti-inflammatory effects of asthma therapies.

Microsatellite DNA instability in COPD

STUDY OBJECTIVES

Cigarette smoking is the prime cause of COPD; however, only a few smokers develop the disease. In a previous study, we demonstrated that microsatellite DNA instability (MSI) is a detectable phenomenon in sputum cells of COPD patients. Therefore, we hypothesize that this genetic alteration may indicate susceptibility to COPD.

DESIGN

In order to investigate this hypothesis, we compared smokers who developed COPD with smokers who did not develop COPD (referred to as non-COPD smokers).

SETTING

Seven highly polymorphic microsatellite markers were targeted on the DNA of sputum cells and of WBCs.

PATIENTS AND PARTICIPANTS

We studied 60 non-COPD smokers and 59 severe COPD patients with a similar smoking history (mean +/- SD) of 48+/-25 and 54+/-33 pack-years, respectively (p = 0.77). Non-COPD smokers were tested once; COPD smokers were tested twice, with an interval of 24 months between tests.

RESULTS

MSI was detected in 14 COPD patients (24%) but in none of the non-COPD smokers. In 10 COPD patients, MSI was exhibited by one microsatellite marker; in the remaining 4 COPD patients, MSI was exhibited by two different alleles. The most commonly affected marker was THRA1 on chromosome 17 (43%). No significant differences were found between MSI-positive and MSI-negative COPD patients for clinical or laboratory parameters, survival, and development of lung cancer. No change in the microsatellite alleles was found between the tests performed with a 24-month interval.

CONCLUSIONS

This study demonstrated that MSI was found exclusively in the sputum cells of smokers with COPD. The results support the hypothesis that MSI could be part of the complex genetic basis of COPD, and it could be a marker of the genetic alteration caused by smoking that allows COPD to develop.

Efficacy of two sputum collection techniques in patients with air flow obstruction

OBJECTIVE

To compare the efficacy of two sputum collection techniques in patients with chronic obstructive pulmonary disease (COPD) in order to diagnose dysplasia or neoplasia.

STUDY DESIGN

This was a crossover study design comparing induced sputum with sputum collected at home. One hundred seven patients with COPD were enrolled. Fifty-six were randomized to collect induced sputum first followed by sputum collection at home. Fifty-one randomly assigned patients collected the sputum in reverse order.

RESULTS

The second sputum collection technique for both random assignments gave the greatest yield of adequate sputum. There was no significant difference in efficacy between the collection of the two sputum collection techniques in the presence of the learning (period) effect.

CONCLUSION

Sputum collection is equally efficacious by the induced method and the home collection method. A learning effect was responsible for the increased yield of sputum abnormalities in the second collection session. Sputum collection at home may facilitate the amount of dysplasic and neoplastic bronchial epithelial changes in heavy smokers with COPD.

Evidence for the induction of a tumour associated cell surface protease on cytologically normal epithelial cells present in the sputum of patients possessing lung tumours

Sputum obtained from healthy subjects and patients with known lung tumours has been challenged with fluorescent probes for the presence of an active cell surface protease. The mature epithelial cells from healthy patients' sputum lacked ability to bind these fluorescent probes whilst the majority of mature epithelial cells in the tumour patients' sputum bound these probes and consequently fluoresced. This demonstrable difference in the cell surface chemistry of mature epithelial cells was linked to the presence of lung tumour cells, which also possessed this cell surface protease. The mechanism of this induced cell surface enzyme appearance is not understood.

Markers of nitric oxide metabolism in sputum and exhaled air are not increased in chronic obstructive pulmonary disease

BACKGROUND

Nitric oxide (NO) is involved in inflammation and host defence of the lung. It has been found in increased concentrations in the airways in asthmatic subjects but its levels in patients with chronic obstructive pulmonary disease (COPD) have not been investigated. A study was undertaken to determine whether markers of NO metabolism (NO in exhaled air, iNOS expression in sputum cells, and nitrite + nitrate (NO2-/NO3-) in sputum supernatant) are increased in subjects with COPD, and whether they correlate with inflammatory indices in induced sputum. The associations of these markers with smoking were also assessed.

METHODS

Sixteen subjects with COPD (median age 66 years, median forced expiratory volume in one second (FEV1) 63% predicted, eight current smokers) and 16 healthy subjects (median age 63 years, median FEV1 113% predicted, eight current smokers) participated in the study. NO was measured during tidal breathing and sputum was induced by inhalation of hypertonic saline.

RESULTS

No differences were observed between subjects with COPD and healthy controls in exhaled NO excretion rate (median 5.15 and 6.25 nmol/min), sputum macrophage iNOS expression (14% and 12%), and sputum supernatant NO2-/NO3- (46 and 73 microM). NO in exhaled air correlated with the percentage of sputum eosinophils in patients with COPD (rho = 0.65, p = 0.009) but not in healthy individuals. Exhaled NO and supernatant NO2-/NO3- levels were lower in healthy smokers than in healthy non/ex-smokers.

CONCLUSIONS

Our findings indicate that NO metabolism is not increased in patients with stable COPD. The close association between exhaled NO levels and sputum eosinophils suggests a role for NO in airway inflammation in COPD. Studies performed during exacerbations may clarify this role.

Carbon and hemosiderin-laden macrophages in sputum of traffic policeman exposed to air pollution

In this study, we evaluated (a) quantitative modifications of dust cells and siderocytes and (b) qualitative modifications (i.e., cellular changes and inflammatory infiltrate) in sputum of 164 traffic policemen occupationally exposed to environmental pollution in an urban area. Such modifications were correlated with time of exposure and smoking habits. Seventy-three (45%) of the policemen were smokers, and a control group of 119 nonexposed individuals (24% smokers) who resided in a rural district near Perugia, Italy, were examined. The sputa, which was collected for 3 d, were smeared on glass slides stained according to Papanicolaou's and Perl's methods. The mean numbers of dust cells in the sputa policemen and the rural population were 103.8 and 12.48, respectively (p < .0001). The numbers of dust cells were highest in policemen who smoked (relative risk = 3.95; p < .006). The mean numbers of siderocytes in policemen and the rural population were 0.99 and 5.31, respectively (not statistically significant, Mann-Whitney test). The difference between the number of subjects with hemosiderin-laden macrophages in traffic policemen and in the control group was small, but it was significant statistically (p < .004). In traffic policemen, it was related to smoking and time of exposure to air pollution, whereas in the control population it was related to heart-pulmonary diseases. In this study, we observed a synergistic effect between smoking and environmental pollution. In addition, less than 5 y of exposure can caused significantly increased (a) numbers of macrophages and (b) inflammatory infiltrate in sputa. The results of the cytological diagnosis revealed a statistically significant difference between policemen and the rural population (p < .001). The cytological exam of sputa and correlations with smoking within each population were not statistically significant. In conclusion, macrophage count in sputum is a sensitive and reproducible method for investigators to verify pulmonary changes that may be observed before they can be measured by functional tests.

Nonasthmatic chronic cough: No effect of treatment with an inhaled corticosteroid in patients without sputum eosinophilia

BACKGROUND

Inhaled corticosteroids are effective in suppressing a chronic cough without asthma associated with sputum eosinophilia.

OBJECTIVE

To investigate the inflammatory characteristics in the induced sputum of patients with a chronic cough without asthma or known cause and the effects of budesonide treatment on chronic cough in those patients.

PATIENTS AND METHODS

Forty-four adults (mean [minimu, maximum] age of 45 years [20,75], 28 women, 17 atopic subjects and 32 nonsmokers], with a daily bothersome cough for at least one year and who had no evidence of asthma or other known cause for the cough, were consecutively enrolled. The trial was a randomized, double-blind, controlled parallel group trial of budesonide 400 mg twice daily for two weeks versus placebo. Patients then received open administration of the same dose of budesonide for a further two weeks. Sputum was induced before and at the end of each treatment period. Cough severity was documented by a visual analogue scale.

RESULTS

Thirty-nine (89%) patients produced mucoid sputum after induction on at least one study visit. At baseline, the majority (59%) had a mild elevation in the median proportion of neutrophils (65%). All had elevated fluid phase levels of fibrinogen (3200 mg/L) and albumin (880 mg/L), and high levels of interleukin-8 and substance P. Interleukin-8 correlated with neutrophils (rho=0.72, P<0.001), fibrinogen (rho=0.65, P<0.001), albumin (rho=0.67, P=0. 001) and eosinophil cationic protein (rho=0.60, P=0.001). Substance P correlated with albumin (rho=0.60, P=0.006). No subject had an increase in eosinophils. Treatment with budesonide did not affect cough or sputum measurements.

CONCLUSIONS

Patients with nonasthmatic chronic cough enrolled in this study had evidence of a mild neutrophilia and/or microvascular leakage. Chronic cough did not respond to treatment with budesonide, perhaps because the cause was not associated with sputum eosinophilia.

Increases in eotaxin-positive cells in induced sputum from atopic asthmatic subjects after inhalational allergen challenge

BACKGROUND

Eosinophils are believed to be critical proinflammatory cells in airway mucosal damage in asthma. Eotaxin is a C-C chemokine with selective activity for eosinophils and basophils. Previous studies have shown increased expression of eotaxin in the airways of asthmatics at baseline. We aimed to investigate eotaxin expression during the late-phase reaction to allergen inhalation in atopic asthmatics.

METHODS

Sputum induction was performed before and 24 h after inhalational allergen challenge in atopic asthmatics, and eotaxin protein was detected immunocytochemically.

RESULTS

Thirteen patients with a mean decrease in forced expiratory volume in 1 s of 28% (+/-1.5) during the early asthmatic reaction, and 39% (+/-4.7) during the late asthmatic reaction produced sufficient sputum for study. The percentage of eosinophils in sputum was increased 24 h after allergen challenge (P<0.004), and eosinophil percentages in sputum after challenge correlated with the magnitude of the late-phase reaction (r=0.56, P=0.05). The percentage of eotaxin-positive cells increased from 12.6% (range 2-43.8) to 24.3% (8.1-47.1, P<0.005). Allergen-induced increases in eotaxin-positive cells correlated with increases in eosinophils (r=0.63, P<0.01).

CONCLUSIONS

These findings suggest that eotaxin may contribute to allergen-induced recruitment of eosinophils to the airway in asthmatic subjects.

Montelukast reduces airway eosinophilic inflammation in asthma: a randomized, controlled trial

Leukotrienes are pro-inflammatory mediators which may contribute to tissue, sputum, and blood eosinophilia seen in allergic and inflammatory diseases, including asthma. Montelukast is a cysteinyl leukotriene1 (CysLT1) receptor antagonist which improves asthma control; the aim of this study was to investigate its effect on induced sputum eosinophils. Montelukast 10 mg (n=19) or placebo (n=21) were administered orally once in the evening for 4 weeks to 40 chronic adult asthmatic patients, aged 19-64 yrs, in a double-blind, randomized, parallel group study. Patients were included if, at prestudy, they had >5% sputum eosinophils, symptomatic asthma with a forced expiratory volume in one second > or =65% of the predicted value and were being treated only with "as needed" inhaled beta2-agonists. In addition to sputum eosinophils, blood eosinophils and clinical endpoints were also assessed. Four weeks of montelukast treatment decreased sputum eosinophils from 7.5% to 3.9% (3.6% decrease, 95% confidence interval (CI) -16.6-0.4). In contrast, placebo treatment was associated with an increase in sputum eosinophils from 14.5% to 17.9% (3.4% increase, 95% CI -3.5-9.8). The least squares mean difference between groups (-11.3%, 95% CI -21.1-(-1.4)) was significant (p=0.026). Compared with placebo, montelukast significantly reduced blood eosinophils (p=0.009), asthma symptoms (p=0.001) and beta2-agonist use (p<0.001) while significantly increasing morning peak expiratory flow (p=0.001). Montelukast was generally well tolerated in this study, with a safety profile similar to the placebo. These results demonstrate that montelukast decreases airway eosinophilic inflammation in addition to improving clinical parameters. Its efficacy in the treatment of chronic asthma may be due, in part, to the effect on airway inflammation.