Repeatability of cellular and soluble markers of inflammation in induced sputum from patients with asthma

Induced sputum in cystic fibrosis: within-week reproducibility of inflammatory markers

Analysis of induced sputum has provided significant insight into the inflammatory response in chronic respiratory diseases such as asthma. The thick, tenacious nature of cystic fibrosis (CF) sputum presents certain challenges to such evaluation. We describe the development of a methodology to assess CF sputum, and the within-week reproducibility (to limit the possibility of any change in clinical status) of cellular and inflammatory markers.

METHODS

Seventeen young adults [9 males, 8 females, mean age 24 (5), median (quartile range) years, percentage of predicted FEV(1) = 64.0 (18.0%)] with CF underwent sputum inductions on the Monday and Thursday of the same week. Patients were pretreated with 400 microg salbutamol and subsequently inhaled 5% saline via a breath enhanced nebulizer. Every 3-min nebulization was interrupted to allow for expectoration of sputum into a polypropylene pot. Sputum samples were dispersed with a solution of dithiothreitol (DTT) and deoxyribonuclease to allow for analysis of total cell count (TCC) and percentage neutrophils (%Neut). Measurement of tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), and neutrophil elastase was performed on samples dispersed with DTT alone.

RESULTS

There were no significant differences between the measurements taken in the same week. Values for Day 1 versus Day 2 were as follows: TCC 20.8 (6.4) vs. 17.6 (2.5) x 10(6) cells/ml; %Neut: 94.1 (0.0) vs. 95.4 (0.5) %; TNF-alpha 7.5 (26.0) vs. 21.0 (44.0) pg/ml; IL-8 610.0 (422.0) vs. 524.0 (587.0) ng/ml and neutrophil elastase 110.0 (19.75) vs. 49.75 (60.75) microM. High intraclass correlation coefficients (ICC) for TCC, %Neut, TNF-alpha IL-8 and neutrophil elastase were found (ICC = 0.76, 0.82, 0.93, 0.82, 0.74, respectively).

CONCLUSIONS

The method developed here for the analysis of CF sputum shows good reproducibility and can be used to evaluate therapeutic interventions in patients with cystic fibrosis.

Relationship between dendritic cells and activated eosinophils in induced sputum of asthmatics

It has been suggested that dendritic cells (DCs) are critical antigen presenting cells for eosinophilic airway inflammation in a mouse model of asthma, and cysteinyl leukotrienes may play a role in DC trafficking in asthmatics. We investigated whether the number of DCs is increased in the induced sputum of both atopic and nonatopic asthmatics and is related to activated eosinophil count in the sputum. Sputum was induced by inhalation of hypertonic saline in 9 atopic and 12 nonatopic asthmatics and 10 nonatopic normal controls, and differential cell counts were performed. DCs and activated eosinophils were identified by immunocytochemistry with monoclonal antibodies (anti-CD1a and EG2, respectively). There were significantly higher percentages of eosinophils, EG2+ cells, and CD1a+ DC in the sputum of atopic and nonatopic asthmatics compared with normal controls, respectively. In asthmatics, the percentage of CD1a+ DC was significantly correlated with that of EG2+ cells (Rs=0.62, p=0.004). We demonstrated that the increased number of DCs was evident in the induced sputum of both atopic and nonatopic asthmatics, and the DC number was related to the activated eosinophil count, which suggests that DCs may contribute to the ongoing eosinophilic inflammation in asthmatic airways, and vice versa.

Brief exposures to NO2 augment the allergic inflammation in asthmatics

Exposure to high ambient levels of nitrogen dioxide (NO2) enhances the airway reaction in humans to allergen, measured as decreased pulmonary function. We tested whether this NO2 effect is associated with an increased inflammatory response to allergen in the airways. To mimic real-life conditions, in which exposure to high ambient levels of NO2 occurs only during short periods of time but often several times a day, we used a repeated-exposure model. On day 1, 18 subjects with allergic asthma were exposed, in randomized order, to purified air or to 500 microg/m3 NO2 for 15 min, and on day 2 for 2 x 15 min. Allergen was inhaled 3-4h after the NO2 exposures on both days. Symptoms, pulmonary function, and inflammatory response in sputum and blood were measured daily. Eosinophil cationic protein in both sputum and blood increased more from day 1 to day 3 after NO2+allergen than after air+allergen, whereas eosinophil counts did not differ. The change in myeloperoxidase was significantly greater after NO2+allergen than after air+allergen in blood but not in sputum. This finding was not accompanied by raised levels of neutrophils in sputum and blood. Symptoms and pulmonary function were equally affected by NO2+allergen and air+allergen. We conclude that two to three brief exposures to ambient levels of NO2 can prime circulating eosinophils and enhance the eosinophilic activity in sputum in response to inhaled allergen. This might be an important mechanism by which air pollutants amplify the inflammatory reactions in the airways.

Sputum tests in the diagnosis and monitoring of asthma

OBJECTIVE

To review the techniques of sputum analysis with relevance to the diagnosis and monitoring of asthma.

DATA SOURCES

MEDLINE databases were searched to identify all publications involving sputum studies related to the diagnosis and treatment of asthma from 1990 to October 2003. We also used internal reference files related to sputum and searched bibliographies of relevant articles. The review was limited to human data in English-language publications.

STUDY SELECTION

Studies were selected by the expert opinions of the authors for quality and relevance to the evaluation of asthmatic inflammation by induced sputum.

RESULTS

During the past 10 years, there have been an increasing number of publications concerning the diagnosis and treatment of asthma using sputum analysis. Analysis of induced sputum provides similar data to secretions obtained through bronchial wash, bronchoalveolar lavage, and, to some extent, bronchial biopsy. The techniques of cellular counting and immunochemical analysis are described along with potential problems and pitfalls of these methods. Clinical application of sputum analysis is discussed as it pertains to the diagnosis and monitoring of asthma and asthma-related conditions.

CONCLUSIONS

Analysis of induced sputum is increasingly being considered as a noninvasive means of evaluating airway inflammation and may provide useful information with regard to the diagnosis and monitoring of asthma in select individuals.

Adenosine 5'-monophosphate increases levels of leukotrienes in breath condensate in asthma

Hyperresponsiveness (AHR) is a key physiological abnormality in asthma. In clinical and research studies AHR is measured bronchial challenge, with methacholine (MCh), but more recently with adenosine-5'-monophosphate (AMP). In the search for markers of airway inflammation in asthmatic patients, we measured the concentrations of histamine and cysteinyl-leukotrienes (cys-LTs) before and after MCh and AMP challenges in the exhaled breath condensate of 13 patients with mild asthma (FEV1 78.5%pred) and nine healthy non-smokers, using specific enzyme immunoassays. With methacholine challenge we did not find any differences between asthmatics and normal subjects in the pre- and post-challenge concentrations of cys-LTs: 27.2+/-1.4 vs. 29.2+/-1.2 pg/ml and 26.3+/-2.2 vs. 27.5+/-4.2 pg/ml, respectively or histamine: 5.1+/-0.4 vs. 5.1+/-0.6 nM and 4.5+/-0.4 vs. 4.4+/-0.3 nM; P>0.05). In asthmatic patients cys-LT levels were significantly higher after AMP challenge (56.2+/-9.7 vs. 31.7+/-6.9 pg/ml; P<0.05); but there was no difference in healthy subjects (27.2+/-4.6 vs. 30.3+/-4.7 pg/ml). There was no difference in histamine concentrations in asthmatic (5.9+/-1.8 vs. 4.5+/-0.5 nM), or healthy subjects (5.5+/-0.4 vs.5.7+/-0.9 nM) after AMP challenge. In conclusion, our results show that the cys-LTs are increased in exhaled breath condensate after AMP challenge, which may indicate that the AMP acts indirectly by releasing cys-LTs from primed mast cells. The detection of LTs and histamine in exhaled breath condensate may be useful in monitoring asthma.

Induced sputum in children with newly diagnosed mild asthma: the effect of 6 months of treatment with budesonide or disodium cromoglycate

BACKGROUND

There are few controlled studies on the effects of anti-inflammatory treatment on airway inflammation in newly diagnosed childhood asthma.

METHODS

Sixty children with newly diagnosed mild persistent asthma, 5-10 years of age, and 17 healthy control subjects were studied. Asthmatic children were randomized into an open study with two treatment groups: (1) budesonide 400 microg twice daily for 1 month, 200 microg twice daily for 5 months and (2) disodium cromoglycate (DSCG) 10 mg three-times daily for 6 months. All exacerbations were treated with budesonide 400 microg twice daily for 2 weeks. Symptoms and lung function were recorded throughout the study.

RESULTS

Sputum induction was safe and the overall success rate was 71%. This improved with age and decreased after treatment. At baseline, the asthmatic children had more eosinophils in blood (0.26 vs 0.18 x 10(9)/l, P = 0.03) and sputum (1.1 vs 0.0 %, P = 0.0001) than the control subjects. The numbers of sputum eosinophils correlated with bronchial responsiveness (R = -0.58, P = 0.0002). Eosinophils were higher in children with atopic asthma than with nonatopic asthma (P < 0.0001), and in children with a history wheezing than in children without wheezing (P = 0.02). Six months of budesonide treatment, but not of DSCG, improved lung function (P = 0.007), decreased symptoms (P = 0.007) and sputum eosinophils (P = 0.003). The effects of budesonide were pronounced in children with intense sputum eosinophilia (>3%).

CONCLUSION

Sputum eosinophilia is present in children with newly diagnosed mild persistent asthma. Treatment with inhaled budesonide, but not with DSCG, decreases sputum eosinophils along with clinical and functional improvement.

An effective strategy for diagnosing occupational asthma: use of induced sputum

Monitoring airway inflammation by means of induced sputum cell counts seems to improve the management of asthma. We sought to assess whether such monitoring at the end of periods at and away from work combined with the monitoring of PEF could improve the diagnosis of occupational asthma. We enrolled subjects suspected of having occupational asthma. Serial monitoring of PEF was performed during 2 weeks at and away from work. At the end of each period, induced sputum was collected. Specific inhalation challenge was subsequently performed. PEF graphs were interpreted visually by five independent observers. Forty-nine subjects, including 23 with positive specific inhalation challenge, completed the study. The addition of sputum cell counts to the monitoring of PEF increased the specificity of this test, respectively, by 18 (range [r] 13.7-25.5) or 26.8% (r 24.8-30.4) depending if an increase of sputum eosinophils greater than 1 or 2% when at work was considered as significant. The sensitivity increased by 8.2% (r 4.1-13.4) or decreased by 12.3% (r 3.1-24.1) depending on the cutoff value in sputum eosinophils chosen (greater than 1 or 2%, respectively). The addition of sputum cell counts to PEF monitoring is useful to improve the diagnosis of occupational asthma.

Efficacy of the novel phosphodiesterase-4 inhibitor BAY 19-8004 on lung function and airway inflammation in asthma and chronic obstructive pulmonary disease (COPD)

Selective inhibitors of phosphodiesterase-4 (PDE4) inhibit the hydrolysis of intracellular cAMP, which may result in bronchodilation and suppression of inflammation. We examined the effect of 1 week treatment with BAY 19-8004 (5 mg once daily), a novel orally administered PDE4 inhibitor, on trough FEV1 and markers of inflammation in induced sputum in patients with asthma or chronic obstructive pulmonary disease (COPD). Seven patients with asthma (mean [SD] FEV1 69.5 [9.3]% predicted; reversibility in FEV1 26.2 [10.1]%; all non-smokers) and 11 patients with COPD (FEV1 58.6 [8.3]% predicted; reversibility in FEV1 6.5 [4.7]%; median [range] 44 [21-90] pack years of smoking) were included in this randomized, double-blind, placebo-controlled trial. FEV1 was measured before and after 1 week of treatment; sputum was induced by 4.5% saline inhalation on the last day of treatment. FEV1 did not improve during either treatment in both patient groups (p>0.2). Sputum cell counts were not different following placebo and BAY 19-8004 treatment in asthma and COPD patients (p>0.2). However, only in patients with COPD, small but significant reductions in sputum levels of albumin and eosinophil cationic protein were observed (p<0.05). In conclusion, 1 week of treatment with the selective PDE4 inhibitor BAY 19-8004 does not affect FEV1 and sputum cell numbers in patients with asthma or COPD. However, such treatment does seem to reduce levels of albumin and eosinophil cationic protein in sputum samples obtained from patients with COPD.

"Refractory" eosinophilic airway inflammation in severe asthma: effect of parenteral corticosteroids

It has been suggested that patients with refractory eosinophilic airway inflammation represent a separate "eosinophilic" asthma phenotype associated with increased morbidity and a poor prognosis. To investigate whether persistent eosinophilia in these patients is a fixed feature or can still be modified by treatment, we investigated the effect of high-dose intramuscular corticosteroids on eosinophils in induced sputum. Twenty-two patients with stable severe asthma (15 women, aged 21-73 years) participated in this double-blind, placebo-controlled study. All were using inhaled corticosteroids (> or = 1,600 microg/day) or chronic oral prednisone. They were included if the percentage of eosinophils in induced sputum was above the upper limit of normal (> or = 2%). Two weeks after treatment with triamcinolone, but not placebo, sputum eosinophils almost completely disappeared from a median of 12.6-0.2% (p < 0.001). In 82% of patients, no eosinophils could be observed at all. In addition, the rescue medication score decreased from 1.4 to 0.8 (p = 0.01), and FEV1 improved from a median of 73.8-88.3% predicted (p = 0.001). We conclude that persistent sputum eosinophilia despite extensive antiasthma treatment is not a refractory phenomenon but is still sensitive to high-dose systemic corticosteroids. This implies that these patients with severe asthma need additional or alternative antiinflammatory treatment to combat the eosinophilia and associated poor prognosis.

Dissociation of lung function and airway inflammation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is defined by progressive, irreversible airflow limitation and an inflammatory response of the lungs, usually to cigarette smoke. However, COPD is a heterogeneous disease in terms of clinical, physiologic, and pathologic presentation. We aimed to evaluate whether airflow limitation, airway responsiveness, and airway inflammation are separate entities underlying the pathophysiology of COPD by using factor analysis. A total of 114 patients (99 males/15 females, age 62 +/- 8 years, 42 pack-years smoking, no inhaled or oral steroids > 6 months) with irreversible airflow limitation (postbronchodilator FEV(1) 63 +/- 9% predicted, FEV(1)/inspiratory vital capacity [IVC] 48 +/- 9%) and symptoms of chronic bronchitis or dyspnea were studied in a cross-sectional design. Postbronchodilator FEV(1) and FEV(1)/IVC, reversibility to inhaled beta(2)-agonists, diffusing capacity, provocative concentration of methacholine required to produce a 20% drop in FEV(1), total serum IgE, exhaled nitric oxide, and induced sputum cell counts (% eosinophils, % neutrophils) were collected. Factor analysis yielded 4 separate factors that accounted for 63.6% of the total variance. Factor 1 was comprised of FEV(1), FEV(1)/IVC, and residual volume/total lung capacity. Factor 2 included reversibility, IgE, provocative concentration of methacholine required to produce a 20% drop in FEV(1,) and diffusing capacity. Factor 3 contained exhaled nitric oxide and factor 4 included sputum % neutrophils and % eosinophils. We conclude that airflow limitation, airway inflammation, and features commonly associated with asthma are separate and largely independent factors in the pathophysiology of COPD.

Clinical usefulness of inflammatory markers in asthma

Asthma is a significant and increasing health problem. Airway inflammation and hyperresponsiveness are key pathophysiological mechanisms underlying asthma. Currently, effective treatments target these two processes and can lead to clinically important improvements in disease control. At present, decisions to initiate or modify therapy are based on symptoms and measures of airway caliber, with no direct assessment of airway inflammation or hyperresponsiveness. It is now possible to measure airway inflammation using noninvasive markers such as exhaled gases, induced sputum and serum measurements. Exhaled nitric oxide (eNO) and induced sputum eosinophils show the greatest promise as clinically useful markers of airway inflammation in asthma. Induced sputum can now be applied to the diagnosis of airway diseases, based on its ability to detect eosinophilic bronchitis in cough, and to differentiate between eosinophilic and non-eosinophilic asthma. The place of induced sputum and eNO in the ongoing monitoring of patients with asthma are now being investigated in controlled trials.

Are rhinovirus-induced airway responses in asthma aggravated by chronic allergen exposure?

Airway inflammation in asthma may represent a favorable environment for respiratory viral infections, augmenting virus-induced exacerbations in asthma. We postulated that repeated low-dose allergen exposure preceding experimental rhinovirus 16 (RV16) infection increases the severity of RV-induced airway obstruction and inflammation. Thirty-six house dust mite-allergic patients with mild to moderate asthma participated in a three-arm, parallel, placebo-controlled, double-blind study. Patients inhaled a low dose of house dust mite allergen for 10 subsequent working days (Days 1-5 and 8-12) and/or were subsequently infected with RV16 (Days 15 and 16). Allergen exposure resulted in a significant fall in FEV1 (p < 0.001) and provocative concentration of histamine causing a 20% fall in FEV1 (p < 0.001) and an increase in exhaled nitric oxide (p < 0.001) and percentage of sputum eosinophils (p < 0.001). RV16 infection led to a fall in FEV1 (p = 0.02) and increases in the percentage of sputum neutrophils (p = 0.01), sputum interleukin-8 (p = 0.04), and neutrophil elastase (p = 0.04). Successive allergen exposure and RV16 infection had no synergistic or additive effect on any of the clinical or inflammatory outcomes. In conclusion, repeated low-dose allergen exposure and RV16 infection induce distinct inflammatory profiles within the airways in asthma without apparent interaction between these two environmental triggers. This suggests that preceding allergen exposure, at the used dose and duration, is not a determinant of the severity of RV-induced exacerbations in patients with mild to moderate asthma.

Induced sputum in the investigation of airway inflammation of COPD

During the last decade, the method of sputum induction (SI) has offered the opportunity to study inflammation in patients with chronic obstructive pulmonary disease (COPD). This paper reviews methodological aspects of SI and summarizes its uses in the research of inflammation in COPD, including sputum cellularity and soluble markers. SI is a relatively safe, reliable, and reproducible technique, used to investigate different aspects of airway inflammation. Although various methods of induction and processing have been proved safe and highly reproducible, a generally accepted method is needed. Sputum analysis has given evidence for increased numbers of macrophages and neutrophils in COPD patients compared to normal subjects. In some studies, increased numbers of eosinophils have been also reported. Changes in various mediators have been found in sputum supernatant of COPD patients (IL-8, LTB-4 and TNF-a). The clinical usefulness of the method in the follow-up of the disease has not been explored extensively. A number of observations in patients with different clinical characteristics could be proven useful in identifying patterns of inflammation associated with different prognosis. Finally, SI could also guide treatment; such as, sputum eosinophilia in COPD could predict response to inhaled corticosteroids.

The effect of seratrodast on eosinophil cationic protein and symptoms in asthmatics

Thromboxane A2 (TXA2), an arachidonate derivative, is a potent bronchoconstrictor; therefore, blocking TXA2 should attenuate airway narrowing. Seratrodast, a TXA2 receptor antagonist, is expected to be a potent antiasthmatic. It was reported that seratrodast reduced bronchial hyperresponsiveness. However, it is controversial whether it reduces airway inflammation. We studied some additional effects of oral seratrodast to inhaled corticosteroids on 10 adult asthmatics in an open-label, crossover design study. Eosinophil cationic protein (ECP) levels in serum and sputum, peak expiratory flow rate (PEF), clinical symptoms, and airway responsiveness were evaluated. Clinical symptom scores were improved by administration of seratrodast (p < 0.05). The addition of seratrodast to asthmatic patients significantly improved mean PEF (p < 0.05). In addition, withdrawal of seratrodast resulted in deterioration of PEF. Airway hyperresponsiveness to acetylcholine measured by Astograph was improved by administration of seratrodast (p < 0.01), and returned to the level of "run-in period" after withdrawal. Administration of seratrodast decreased the concentration of ECP in sputum significantly (p < 0.05), and sputum ECP significantly increased again after withdrawal of (p < 0.05). These results suggest that seratrodast improves clinical symptoms andairway hyperresponsiveness by reducing airway inflammation. Seratrodast may be useful as an anti-inflammatory agent and beneficial when added to inhaled corticosteroids in the treatment of bronchial asthma.

Long-term repeatability of induced sputum cells and inflammatory markers in stable, moderately severe COPD

STUDY OBJECTIVES

Neutrophilic inflammation is a major feature of COPD. Induced sputum is increasingly used to monitor inflammatory airway diseases. Although short-term repeatability of selected sputum markers has been extensively studied in several populations, data on the long-term repeatability of induced sputum markers in stable COPD are scant.

DESIGN

Sputum supernatant of 12 patients with stable COPD was analyzed on three separate occasions with 4-weekly intervals. Sputum cells and inflammatory markers interleukin (IL)-8 and soluble intercellular adhesion molecule (sICAM)-1 were measured in supernatant using enzyme-linked immunosorbent assay. Repeatability of sputum markers was expressed by intraclass correlation coefficients (Ri).

MEASUREMENTS AND RESULTS

Sputum induction was safe in all patients. None of the sputum parameters analyzed changed significantly throughout the study. The repeatability for cell differential counts in stable COPD was as follows: total cells, Ri = 0.07; neutrophils, Ri = 0.66; macrophages, Ri = 0.47; eosinophils, Ri = 0.49; and lymphocytes, Ri = 0.58. The repeatability of soluble markers was as follows: IL-8, Ri = 0.50; and sICAM, Ri = 0.58. Sputum neutrophils were negatively correlated with lung function on each separate occasion, whereas soluble markers were not correlated with sputum cells (p > 0.16, all correlations) or lung function (p > 0.24, all correlations).

CONCLUSIONS

Clinically stable, moderate COPD is associated with equally stable sputum inflammatory markers. Repeatability of induced-sputum markers of neutrophilic inflammation in stable COPD is satisfactory, even over extended periods of time. These data support the usefulness of serial monitoring of induced-sputum inflammatory markers in COPD.

Circadian variation of sputum inflammatory cells in mild asthma

BACKGROUND

Asthma, like many conditions, demonstrates a circadian rhythm with a worsening of lung function in the early morning hours compared with in the late afternoon.

OBJECTIVE

Because eosinophilic airway inflammation is a proposed mechanism for worsening asthma, we characterized circadian variation in airway eosinophils and determined its relationship to variability in airway function.

METHODS

Pulmonary function testing, sputum induction, and phlebotomy were performed at 7 am and 4 pm in 11 allergic subjects with mild asthma. Sputum was analyzed for cell viability, differential, and eosinophil-derived neurotoxin levels. IL-5 levels in serum were measured by means of ELISA.

RESULTS

Subjects had a significant decrease in FEV(1) (median [interquartile range] = 80% [70%-86%] vs 85% [82%-94%], P =.009) and a greater beta-agonist reversibility (median [interquartile range] = 13% [7%-32%] vs 8% [5%-14%], P =.024) in the early morning compared with in the late afternoon. Sputum analysis showed an increase in early morning total sputum leukocytes (median [interquartile range] = 4.3 x 10(6) [2.3 x 10(6) to 6.1 x 10(6)] vs 2.6 x 10(6) [1.7 x 10(6) to 3.6 x 10(6)], P =.044) and eosinophils (median [interquartile range] = 7.0 x 10(4) [2.7 x 10(4) to 18.7 x 10(4)] vs 3.6 x 10(4) [1.0 x 10(4) to 8.2 x 10(4)], P =.024). Furthermore, sputum eosinophils correlated with beta-agonist reversibility (R (s) = 0.665, P =.019). Finally, levels of IL-5 in serum and eosinophil-derived neurotoxin in sputum were significantly increased at 7 am.

CONCLUSION

These data suggest that circadian variability in pulmonary function in asthma could be related to changes in airway eosinophil recruitment and activation.

Methods for "indirect" challenge tests including exercise, eucapnic voluntary hyperpnea, and hypertonic aerosols

Bronchial provocation tests that use stimuli that act indirectly to cause airway narrowing have a high specificity for identifying people with active asthma who have the potential to respond to treatment with antiinflammatory drugs. The first test to be developed was exercise and it was used to assess the efficacy of drugs such as sodium cromoglycate. Eucapnic voluntary hyperpnea was developed later, as a surrogate test for exercise. Hypertonic aerosols were introduced to mimic the dehydrating effects of evaporative water loss that occurs during hyperpnea. A wet aerosol of 4.5% saline or a dry powder formulation of mannitol is used. At present the indirect challenge tests are becoming increasingly recognised as appropriate for monitoring treatment with inhaled steroids. Indirect tests identify those with potential for exercise-induced bronchoconstriction, an important problem for some occupations, such as the defence forces, fire fighters and the police force and for some athletic activities. The advantage in using an indirect challenges, over a direct challenge with a single pharmacological agonist, is that a positive response indicates that inflammatory cells and their mediators (prostaglandins, leukotrienes and histamine) are present in the airways in sufficient numbers and concentration to indicate that asthma is active at the time of testing. The corollary to this is that a negative test in a known asthmatic indicates good control or mild disease. Another advantage is that healthy subjects do not have significant airway narrowing to indirect challenge tests. The protocols used for challenge with indirectly acting stimuli are presented in detail.

Induced sputum inflammatory measures correlate with lung function in children with cystic fibrosis

OBJECTIVE

To validate a sputum induction technique in cystic fibrosis (CF), we examined the relation between airway inflammation and pulmonary function in children with CF by correlating inflammatory indexes in induced sputum with FEV(1).

STUDY DESIGN

We measured baseline spirometry and oxygen saturations and then performed sputum inductions with 3% hypertonic saline in 20 clinically stable children with CF (11 girls). We examined the relation of airway inflammation and lung function in the 19 individuals (95%) who expectorated an adequate sputum sample. Measures of airway inflammation in induced sputum included total cell counts, neutrophil (PMN) counts, interleukin-8 levels, and free neutrophil elastase activity.

RESULTS

There were significant inverse relations between FEV(1) and total cell counts and PMN counts (r = -0.57, P <.01 for both), interleukin-8 (r = -0.72, P =.002), and elastase (r = -0.75, P =.001). Airway infection, as assessed by bacterial density in induced sputum, did not correlate with lung function or indexes of inflammation.

CONCLUSIONS

We conclude that measures of inflammation in induced sputum correlate with FEV(1) in clinically stable children with CF with normal to mildly abnormal lung function and that they may be useful as surrogate outcome measures in clinical trials.

Airway hyperresponsiveness: using bronchial challenge tests in research and management of asthma

Bronchial challenge tests have been standardized in detail during the past two decades. They are providing relevant pathophysiological and clinical information about patients with asthma or chronic obstructive pulmonary disease (COPD), by allowing the measurement of the degree of airway hyperresponsiveness, which includes an increased sensitivity as well as increased maximal response to bronchoconstrictor stimuli. There are various types of challenges, to which the responses are not interchangeable. Responses to so-called "indirect" challenges are largely dependent on the state of activation of inflammatory or resident cells within the airways, and the state of activation can vary rapidly, either spontaneously or through intervention. Responses to "direct" challenges are dependent on less variable, rather chronic features of airways inflammation or remodeling. Bronchoprovocation tests provide integrated information about multiple pathophysiological pathways within the airway. This is in contrast to the measurements of cells, mediators, or cytokines in biological fluids, which provide only very specific information on selected inflammatory pathways. It has recently been shown that the outcome of asthma can substantially be improved when long-term treatment is not only guided by symptoms and lung function, but also by the degree of airway hyperresponsiveness to direct stimuli. Taken together, current data warrant a broader usage of bronchoprovocation tests in the research as well as clinical management of asthma and COPD. In asthma, it allows selective, individually targeted therapy of the patient as opposed to the currently recommended regimens that are (increasingly) unselective in their approach. The potential benefits of monitoring other phenotypic disease markers is currently under investigation.

Induced sputum is a reproducible method to assess airway inflammation in asthma

To evaluate the reproducibility of induced sputum analysis, and to estimate the sample size required to obtained reliable results, sputum was induced by hypertonic saline inhalation in 29 asthmatic subjects on two different days. The whole sample method was used for analysis, and inflammatory cells were counted on cytospin slides. Reproducibility, expressed by intra-class correlation coefficients, was good for macrophages (+0.80), neutrophils (+0.85), and eosinophils (+0.87), but not for lymphocytes (+0.15). Detectable differences were 5.5% for macrophages, 0.6% for lymphocytes, 5.2% for neutrophils, and 3.0% for eosinophils. We conclude that analysis of induced sputum is a reproducible method to study airway inflammation in asthma. Sample sizes greater than ours give little improvement in the detectable difference of eosinophil percentages.

Lower airway inflammatory responses to repeated very-low-dose allergen challenge in allergic rhinitis and asthma

BACKGROUND

Low-dose allergen challenge (LDAC) may be a useful tool for studying the capacity of allergens to induce airway inflammation in atopic subjects.

OBJECTIVE

To evaluate lower airway inflammatory changes following repeated inhalation of very low doses of allergen (VLDAC) in non-asthmatic subjects with allergic rhinitis (NAAR) compared with mild allergic asthmatic subjects (AA).

METHODS

Fourteen NAAR and 11 AA were seen out of the pollen season and had skin prick tests with common aeroallergens. Baseline spirometry (S) and methacholine challenge (MC) were done and blood and induced sputum (IS) differential cell counts were obtained. Each subject underwent VLDAC on four consecutive mornings with a relevant allergen. S, MC, and blood and IS samplings were repeated 6 h after the second and fourth VLDAC and one week later.

RESULTS

Although there were, as expected, no changes in FEV1 or PC20 in either group, mean percentage eosinophils on IS were significantly increased in NAAR on day 2 of VLDAC and decreased in all but one subject on day 4, with a tendency to return to baseline levels one week later. In AA, there was a non-significant trend for sputum eosinophils to increase on day 2; four subjects showed a decrease of eosinophils on day 4 of VLDAC. There was a correlation between eosinophil cationic protein (ECP) levels and eosinophil counts in NAAR throughout the study. There were no variations in other sputum cells or blood inflammatory cells.

CONCLUSION

VLDAC can increase the percentage of eosinophils in IS of NAAR subjects without associated respiratory symptoms nor physiological modifications. A reduction in eosinophilic response despite repeated exposure, more common in NAAR subjects, suggests an adaptation process that needs to be further evaluated.

Quality evaluation of samples obtained by spontaneous or induced sputum: comparison between two methods of processing and relationship with clinical and functional findings

The aim of the study was to assess, on a large group of spontaneous or induced sputum samples, the difference in quality between slides processed by two different methods, and the relationship between quality assessment and some clinical and functional characteristics of the examined subjects. We examined 631 sputum samples obtained from 337 subjects with proven (n = 291) or suspected bronchial asthma. Of these, 467 samples were processed using the whole-sample method (Group I), while 164 samples were processed using the plug method (Group II). Salivary contamination, cell distribution on the slide, and cell borders were evaluated, and samples were classified as inadequate, adequate, or good. Inadequate samples were equally represented in both groups, while good samples were represented more in Group II. No significant difference in most clinical and functional findings was observed between the different quality categories of both groups. A higher proportion of inadequate samples was observed in Group I samples spontaneously collected. Mild intermittent asthmatics produced a better quality of slides in comparison with other groups of asthma severity. In conclusion, sputum quality partially depends on the different methods of sputum collection and/or processing, although the percentage of inadequate samples is similar for the two methods of processing. Sputum quality is only marginally affected by clinical and functional characteristics of asthma, or by asthma severity.

Comparison of sputum induction using high-output and low-output ultrasonic nebulizers in normal subjects and patients with COPD

STUDY OBJECTIVE

s: Induced sputum is used to investigate pulmonary diseases. Low-output ultrasonic nebulizers have become available and have potential advantages over high-output nebulizers. We hypothesized that a low-output nebulizer would give comparable results to a high-output nebulizer, with an acceptable safety profile.

DESIGN

Randomized, crossover study.

SETTING

University teaching hospital.

PARTICIPANTS

Ten normal subjects and 10 patients with COPD.

INTERVENTIONS

Participants attended for sputum induction on two occasions in random order using low-output and high-output nebulizers.

MEASUREMENTS AND RESULTS

Lung function and oxygen saturation were measured during sputum induction, and tolerability of the procedure was assessed. Cell counts, interleukin 8, and neutrophil elastase were measured in sputum. Use of the high-output nebulizer resulted in a greater FEV(1) (mean +/- SEM, 0.29 +/- 0.04 L vs 0.21 +/- 0.04 L; p = 0.04) and percentage drop in FEV(1) (25.8 +/- 2.6% vs 19.5 +/- 2.9%, respectively; p = 0.02) compared with the low-output nebulizer in patients with COPD. There was a shorter tolerated nebulization time with the high-output nebulizer compared with the low-output nebulizer: 12.7 +/- 2.0 min vs 16.5 +/- 1.8 min, respectively (p = 0.02). Modified Borg scores were lower with the low-output nebulizer than the high-output nebulizer in normal subjects: median, 0 (interquartile range [IQR], 0 to 1) vs median, 1.5 (IQR, 0 to 2), respectively (p = 0.05). There were no differences in cell counts and soluble markers of inflammation.

CONCLUSIONS

The low-output ultrasonic nebulizer is comparable to high-output nebulizer for cellular and soluble markers of inflammation, results in a smaller reduction in FEV(1), is better tolerated, and is a suitable tool for investigating airway inflammation in patients with COPD.

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.

Relationship between sputum inflammatory markers, lung function, and lung pathology on high-resolution computed tomography in children with cystic fibrosis

High-resolution computed tomography (HRCT) is a sensitive technique for early visualisation and location of cystic fibrosis (CF) bronchopathology, and has been shown to detect acute reversible and chronic changes. It would be expected to correlate with markers of the underlying pathological processes, such as sputum cytokines and cytology, as well as with pulmonary function tests (PFTs). Our aim was to study the relationship between PFTs, sputum cytology, and sputum cytokine interleukin-8 (IL-8) and HRCT in CF patients. Prospective standardized collection of sputum samples was performed at the time of routine annual high-resolution CT scans. Forced expired volume in 1 sec (FEV(1)) and forced vital capacity (FVC) were recorded. Sputum processing was selective, with dispersal by the three-enzyme technique. IL-8 measurements were by kit assay. HRCT scans were scored by a pediatric radiologist, blinded to clinical condition, using a modified Bhalla score.Forty-three CT scans were performed on 34 children with CF between March 1998 and April 2000. Mean age was 12.3 years (range, 6-21 years), FEV(1) (% predicted) was 67% (range, 23-120%), and mean modified Bhalla score was 11.2 (range, 0-22). Sputum IL-8 concentration (mean, 86; range, 4-150 ng/mL) and total cell count (mean, 31.9 x 10(6)/mL; range, 21.8-42.0 x 10(6)/mL) were high. FEV(1) and FVC correlated with modified Bhalla score (r = -0.66, P < 0.0001 for both), and most individual components of the score, especially mosaic perfusion (r = -0.64, r = -0.61 respectively, P < 0.0001) and extent of bronchiectasis (r = -0.61, P < 0.0001 for both). The combination of these two predicted 58% of the variability in FEV(1) on analysis of variance (P < 0.0001). Sputum total cell count correlated weakly with modified Bhalla score (r = 0.38, P < 0.05) and with FEV(1) and FVC (r = -0.36, P < 0.05; and r = -0.46, P < 0.01). Differential cell counts, cell viability, and IL-8 did not correlate with modified Bhalla scores, or with reversible components such as mucus plugging, centrilobular nodules, or peribronchial thickening. In conclusion, pathological changes on HRCT correlated with lung function but not with sputum markers of inflammation.

Up-regulation of heme oxygenase-I in alveolar macrophages of newly diagnosed asthmatics

Exhaled carbon monoxide (CO), which has been found to be elevated in asthma, is generated primarily by heme oxygenase I (HO-I), an enzyme induced by oxidant stress and cytokines. The aim of this study was to assess the distribution and expression of HO-I in various human lung cells in acute and stable asthma. Normal lung tissue biopsies (from 6 non-smoking subjects operated on for a lung tumour) and macrophages from induced sputum (from 5 healthy controls, 5 untreated asthmatics, 7 stable treated asthmatics and 5 asthmatics recovering from exacerbation and being on systemic steroids) were investigated for HO-I by immunohistochemistry. The time response of HO-I induction was examined in cultured monocytes, which are known to maturate into monocyte-derived macrophages in culture. Lung biopsies showed prominent HO-I immunoreactivity only in alveolar macrophages. Macrophages in the induced sputum of healthy controls showed no HO-I immunoreactivity, with the exception of one case. Moderate or intense HO-I immunoreactivity could be observed in alveolar macrophages in 4/5 cases with recent asthma, and 2/7 with stable asthma, but in none ofthe patients treated with systemic corticosteroids for acute exacerbation. Experiments with cultured cells revealed that HO-I was induced by oxidants within the first 24 h, but the induction was reversed during the next 48 h. HO-I is mainly expressed in alveolar macrophages of human lung. Macrophages of induced sputum show prominent but transient HO-I immunoreactivity, in untreated asthmatics, but not in asthmatics treated with corticosteroids.

Assessment of microvascular leakage via sputum induction: the role of substance P and neurokinin A in patients with asthma

Microvascular leakage is an important feature of inflammation. However, the assessment of vascular leakage has seldom been used to monitor airway inflammation in asthma. The aim of this study was to determine the effect of inhaled substance P, a potent neurokinin 1 (NK1) agonist and mediator of plasma extravasation, on markers of microvascular leakage in induced sputum from patients with asthma. In a crossover study, sputum was induced before and 30 minutes after inhalation of substance P or neurokinin A (as control) by 12 subjects with atopic and mild, steroid-naive asthma. The levels of alpha2-macroglobulin, ceruloplasmin, albumin, and fibrinogen were determined in induced sputum as markers of leakage. Substance P induced a significant increase in the levels of alpha2-macroglobulin, ceruloplasmin, and albumin in induced sputum (median fold change, 3.1, 2.2, and 2.9, respectively) (p < 0.013), whereas inhaled neurokinin A was not able to induce significant changes (p > 0.31). The increase in sputum leakage markers was not associated with the cumulative dose of substance P (p > 0.12). These results indicate that NK1 receptor stimulation causes a rapid increase in microvascular leakage as shown in induced sputum in patients with asthma. This investigational model of "dual induction" (first leakage, then sputum) may therefore be useful to test the antiexudative effect of newly develop drugs, such as NK1 antagonists.

Chronic sinusitis in severe asthma is related to sputum eosinophilia

BACKGROUND

Chronic rhinosinusitis and asthma are conditions that frequently coexist, particularly in severe asthma. The precise mechanism of the relationship between upper and lower airway inflammation is still a matter of debate. We hypothesized that the extent of inflammation in the nasal mucosa is related to lung function and inflammation in the bronchial mucosa in patients with severe asthma.

OBJECTIVE

We sought to investigate the relationship between sinonasal inflammation as assessed on computed tomography (CT) scanning, lung function, sputum eosinophilia, and nitric oxide (NO) in exhaled air in patients with severe asthma.

METHODS

Eighty-nine nonsmoking outpatients with severe asthma (29 men and 60 women; mean age 45 years; age range, 18-74 years) were included in this study. CT scans were scored (0-30) by a blinded investigator using a validated method. Lung function, NO in exhaled air, and sputum eosinophils were measured by using standard procedures.

RESULTS

CT scans showed abnormalities in 84% of patients. Extensive sinus disease (score 12-30) was found in 24% of patients. There was a significant positive correlation between CT scores and eosinophils in peripheral blood (R(s) = 0.46) and induced sputum (R(s) = 0.40) and level of exhaled NO (R(s) = 0.45, P <.01). CT scores were also positively related to functional residual capacity and inversely related to diffusion capacity, particularly in patients with adult-onset asthma (R(s) = 0.47 and R(s) = -0.53, respectively).

CONCLUSIONS

The results of this study show a direct relationship between sinonasal mucosa thickness and bronchial inflammation in severe asthma, particularly in patients with adult-onset disease. Whether sinus disease directly affects the intensity of bronchial inflammation is still an unanswered question.

Monitoring asthma severity and response to treatment

Guidelines for the management of asthma rely on various methods of assessing severity and how it changes in order to select the appropriate treatment. These methods have been developed from the basic clinical skills of history taking and physical examination to which attempts at improving objectivity have been added, such as the use of asthma diaries, the home recording of peak expiratory flow (PEF) or measurements of bronchial reactivity. The present review was an attempt to determine to what extent monitoring asthma by various techniques is justified. Unfortunately, diaries and home recording of PEF are easily faked and generally unreliable while objective tests, such as the measurement of bronchial reactivity or studies of induced sputum cannot be undertaken often enough for monitoring, and there is certainly the need for prospective longitudinal controlled studies.

Eosinophilic airway inflammation as an underlying mechanism of undiagnosed prolonged cough in primary healthcare patients

Prolonged cough is a common problem in patients seen in general practice. Using a simple method of sputum induction and processing of sputum samples, we determined whether eosinophilic airway inflammation could be a cause of undiagnosed prolonged cough. Eighty-two patients who had had cough for more than 1 month were enrolled into the study, in six primary healthcare centres. Patients with known pulmonary disease, including asthma or chronic obstructive pulmonary disease (COPD), or who were known to have another cause of cough, or to have recently suffered from a respiratory infection, were excluded. Fifty-three healthy individuals served as controls. Sputum was induced by inhalation of 3% saline. Inflammatory cells in smears were studied semi-quantitatively. Concentrations of eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), myeloperoxidase (MPO) and human neutrophilic lipocalin (HNL) were determined. Sputum induction proved safe and adequate samples were obtained from 91%. Sputum eosinophilia (eosinophils accounting for more than 5% of all cells in smears) was present in 14 patients with prolonged cough (19%) but in no healthy individual (P=0.001). Five of the 14 individuals (36%) who exhibited sputum eosinophilia appeared to have asthma, while nine of the 14 (64%) did not. Concentrations of ECP and EPO were higher in patients with prolonged cough than in healthy individuals (P=0.02 for ECP; 0.005 for EPO). We conclude that eosinophilic airway inflammation is a fairly common cause of prolonged cough, even in patients not suffering from asthma or COPD, or in whom no other cause of cough is known to be present. Induced sputum samples obtained in health centres can be studied in a central laboratory. Detection of eosinophilic airway inflammation could aid the decision regarding treatment.

Induced sputum: comparison between isotonic and hypertonic saline solution inhalation in patients with asthma

BACKGROUND

Sputum induction by hypertonic saline solution inhalation is widely used to study airways secretions in patients with asthma. However, hypertonic saline solution is a potent indirect bronchoconstrictor.

STUDY OBJECTIVES

We studied the validity of isotonic saline solution (0.9%) inhalation as a means to induce sputum by comparing it to hypertonic saline solution (4.5%) inhalation.

PATIENTS

Sixteen patients with moderate-to-severe asthma reporting a clinical history of mucus hypersecretion.

METHODS

Subjects underwent sputum induction twice at 1-week intervals. Saline solution (hypertonic or isotonic) was inhaled for three periods of 5 min. The parameters assessed in sputum samples were cell counts, sodium, eosinophil cationic protein (ECP), and albumin concentrations, osmolality, and pro-matrix metalloproteinase (MMP)-9 activity by zymography.

RESULTS

The maximal fall in peak expiratory flow during sputum induction was greater after inhalation of hypertonic saline solution than after inhalation of isotonic saline solution (p < 0.01). Each subject produced analyzable sputum on both visits. There were no statistically significant differences in total and differential sputum cell counts, and the reproducibility coefficients were high for eosinophils and neutrophils when comparing the two methods. Likewise, sputum levels of ECP and albumin as well as sputum pro-MMP-9 activity were not different between the two methods, and were highly reproducible as shown by high intraclass coefficients (Ri) of correlation (0.72, 0.74, and 0.77 for ECP, albumin, and pro-MMP-9, respectively). Sputum sodium concentrations and osmolality were higher after inhalation of hypertonic saline solution (p < 0.05).

CONCLUSION

In patients with moderate-to-severe asthma reporting a clinical history of mucus hypersecretion, inducing sputum by isotonic or hypertonic saline solution inhalation leads to comparable results in eosinophil and neutrophil cell counts and fluid phase mediators/proteins.

Safety of sputum induction with isotonic saline in adults with acute severe asthma

BACKGROUND

Sputum induction is a safe and effective technique to study airway inflammation in stable asthma. However, it has the potential to induce bronchospasm and the safety and efficacy of the technique in acute asthma has not been determined.

OBJECTIVE

The objective of this study was to evaluate the safety and efficacy of a protocol to induce sputum using isotonic saline in adults with acute exacerbations of asthma.

METHODS

Adults (n = 47) presenting to the emergency room with acute asthma and an FEV1 > 1.0 L underwent supervised sputum induction with 0.9% saline delivered by an ultrasonic nebuliser. Induction was ceased if there was a fall of 20% or greater from baseline FEV1.

RESULTS

Subjects had moderate to severe exacerbations of acute asthma. An adequate sputum sample was obtained in 87% of subjects. Four subjects ceased induction because of symptom distress. There was a fall > or = 20% in 28% of subjects. Bronchoconstriction was successfully reversed by salbutamol in all subjects. Predictors of significant bronchoconstriction were older age, use of ingested corticosteroids, and a requirement for high-dose nebulized salbutamol for the exacerbation. Maintenance long-acting beta2-agonist therapy protected against bronchoconstriction during sputum induction.

CONCLUSIONS

Sputum induction in acute asthma using isotonic saline is highly efficacious in obtaining an adequate sputum sample. There is the potential for significant bronchoconstriction to occur but this can be managed safely with minimal discomfort to subjects.

Relationship between airway inflammation, hyperresponsiveness, and obstruction in asthma

BACKGROUND

Although the role of eosinophils in airway inflammation in chronic asthma has been extensively studied, a role for neutrophils has not been well characterized. Furthermore, prior studies have not systematically sought or controlled for factors that might confound the relationship between cellular markers of inflammation and physiologic measures of airway function.

OBJECTIVE

The purpose of this study was to determine whether eosinophilic and neutrophilic inflammation independently contribute to abnormalities of airway function in asthma.

METHODS

Multivariate analysis of data collected during screening and enrollment of 205 asthmatic adults for clinical trials was conducted to examine the relationships between cellular inflammation in induced sputum and FEV(1) and methacholine responsiveness (PC(20)) while confounding factors were controlled for.

RESULTS

We found that age, sex, ethnicity, and use of inhaled corticosteroids were important confounding factors of the relationship between cellular inflammation and airway function. When these factors were controlled for, multivariate analysis showed that eosinophil percentage in induced sputum is independently associated with lower FEV(1) and lower PC(20) (P = .005 and P = .005, respectively). In the same models, increased sputum neutrophil percentage is independently associated with lower FEV(1) (P = .038) but not with PC(20) (P = .49).

CONCLUSIONS

These results suggest that both eosinophilic inflammation and neutrophilic inflammation independently contribute to abnormalities of FEV(1) in asthma. Therapies directed specifically at control of neutrophilic inflammation might be useful in improving airway caliber in patients with chronic asthma.

Effects after inhalation of (1-->3)-beta-D-glucan in healthy humans

BACKGROUND AND AIM

This study was performed to assess the effects of an exposure to a pure (1-->3)-beta-D-glucan, a cell wall component of fungi, plants and certain bacteria.

METHODS

Twenty-one healthy subjects inhaled saline or (1-->3)-beta-D-glucan suspended in saline in a random, double-blind, cross-over design. They were examined before exposure and 24 and 72h afterwards with spirometry, blood sampling and collection of induced sputum. Differential cell counts and eosinophilic cationic protein (ECP) were determined in blood and sputum, and myeloperoxidase (MPO), tumour necrosis factor-alpha (TNF-alpha), and interleukin (IL)-8 and IL-10 were determined in sputum supernatants. TNF-alpha was determined after cultivation of blood mononuclear cells.

RESULTS

In sputum, inhalation of saline caused a significant increase in ECP and TNF-alpha. (1-->3)-beta-D-Glucan inhalation caused a further increase in these cytokines, although not statistically significantly different from the increase induced by inhalation of saline alone. In blood, the number of eosinophils was significantly decreased 72 h after the challenge with (1-->3)-beta-D-glucan. This effect was not found after the inhalation of saline alone. TNF-alpha production from stimulated blood mononuclear cells was significantly decreased 72 h after the (1-->3)-beta-D-glucan inhalation as compared with the increase induced by saline inhalation.

CONCLUSIONS

The results suggest that (1-->3)-beta-D-glucan causes a different type of response as compared with inflammatory agents such as bacterial endotoxin that cause a neutrophil-dominated inflammatory response.

Effect of inhaled ciclesonide on airway responsiveness to inhaled AMP, the composition of induced sputum and exhaled nitric oxide in patients with mild asthma

To assess the efficacy of ciclesonide, a novel corticosteroid pro-drug, we compared its effect on lung function, airway responsiveness to inhaled AMP, the composition of induced sputum, and the level of exhaled nitric oxide (NO) with the effect of budesonide in patients with asthma. Fifteen non-smoking steroid-naive patients (mean FEV(1), 94%pred) inhaled either 400 microg ciclesonide or 400 microg budesonide as a single morning dose for two weeks each separated by a > or =3 week wash-out period. The study was performed in a double-observer, randomized, cross-over design. FEV(1)increased significantly during treatment with budesonide (3.38 vs. 3.64 l P=0,003), but not after ciclesonide (3.60 vs. 3.69 l). PC(20)FEV(1)of AMP increased (P<0,001, each) after both budesonide (4.59 vs. 32.48 mg/ml, 2.8 doubling doses) and ciclesonide (3.92 vs. 20.00 mg/ml, 2.4 doubling doses). The percentage of sputum eosinophils was significantly reduced after ciclesonide (7.9 vs. 3.4% P=0.01), but not budesonide (6.0 vs. 4.3%). After both budesonide and ciclesonide, a significant (P<0.001) reduction in the level of exhaled NO occurred. In none of the parameters studied, the changes differed significantly between treatment with budesonide or ciclesonide. These data suggest that ciclesonide is equi-effective to budesonide with regard to its potency to reduce the airway responsiveness to inhaled AMP as well as airway inflammation in patients with mild asthma.

Benefits of high altitude allergen avoidance in atopic adolescents with moderate to severe asthma, over and above treatment with high dose inhaled steroids

Some patients with severe asthma cannot be controlled with high doses of inhaled steroids (ICS), which may be related to ongoing environmental allergen exposure. We investigated whether 10 weeks of high altitude allergen avoidance leads to sustained benefits regarding clinical and inflammatory markers of disease control in adolescents with persistent asthma despite treatment with high dose ICS. Eighteen atopic asthmatic adolescents (12-18 yr, 500-2000 microg ICS daily) with established house dust mite allergy, participated in a parallel-group study. Quality of life (PAQL), lung function, bronchial hyperresponsiveness (BHR) to adenosine and histamine, induced sputum and urine samples were collected repeatedly from 10 patients during a 10-week admission period to the Swiss Alps (alt. 1560 m) and at 6 weeks after return to sea level. Results were compared with those in eight patients, studied in their home environment at sea level for a similar time period. Throughout the study, asthma medication remained unchanged in both groups. During admission to high altitude, PAQL, lung function, BHR to adenosine and histamine, and urinary levels of eosinophil protein X (U-EPX), leukotriene E4 (U-LTE4) and 9alpha11beta prostaglandin F2 (U-9alpha11beta PGF2) improved significantly (P < 0.05), with a similar tendency for sputum eosinophils (P < 0.07). Furthermore, the changes in PAQL and BHR to adenosine and histamine were greater in the altitude than in the control group (P < 0.05). At 6 weeks after renewed allergen exposure at sea level, the improvements in PAQL (P < 0.05), BHR to adenosine (P < 0.07) and histamine (P < 0.05), as well as U-EPX (P < 0.05) and U-LTE4 (P < 0.05) were maintained. A short period of high altitude allergen avoidance, on top of regular treatment with ICS and long-acting beta2-agonists, results in improvement of asthma, as assessed by clinical and inflammatory markers of disease severity. These findings indicate that short-term, rigorous allergen avoidance can improve the long-term control of severe asthma over and above what can be achieved even by high doses of inhaled steroids.

Granulocyte markers in induced sputum in patients with respiratory disorders and healthy persons obtained by two sputum-processing methods

Induced sputum is increasingly used to detect and monitor airway inflammation in respiratory diseases. However, the processing of sputum has been rather laborious for clinical practice. The aim of this study was to improve the practicality of induced-sputum studies by simplifying sample processing. Eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), neutrophil lipocalin (HNL) and myeloperoxidase (MPO) were used as biochemical markers of airway inflammation and the results of the study method were compared with a previously validated (reference) method. Induced sputum was obtained from 42 healthy controls, 10 subjects with acute respiratory infection, eight patients with chronic obstructive pulmonary disease (COPD) and 17 asthmatics. The sputum sample was divided into two parts and treated either: (i) by the reference method (released markers), where sputum was homogenized with dithiotreitol and centrifuged to yield cell-free supernatant and a cell pellet, or (ii) by the study method (total markers), where the cells were lysed after homogenization so that cell-associated markers were released and solubilized. For comparison, the four biochemical markers were measured in sputum supernatant and in sputum lysate. The differential cell count was performed from the cell pellet in the reference method. Repeatability was assessed in a group of 16 subjects. The effect of reagents and the recovery of assays were also evaluated. Released and total markers correlated well (ECP r(s)=0.80, P<0.0001; EPO r(s)=0.49, P<0.0001; HNL r(s)=0.87, P<0.0001; MPO r(s)=0.71, P<0.0001). Incubation with dithiotreitol and lysis reagent had no negative influence on marker assays. The within-subject variability of total ECP, MPO and HNL in both methods was small in two measurements taken I week apart. The study method, measuring total inflammatory markers, gave comparable results to the reference method, measuring released markers. In the study method the sputum processing was simplified, which may improve its applicability.

Induced sputum cellularity. Reference values and distribution in normal volunteers

Sputum induction has recently been proposed as the only direct noninvasive method for measuring airway inflammatory indices. The reference values and the distribution of cells in induced sputum in a control population have not yet been well defined. We therefore evaluated data from a large number of healthy volunteers. One hundred fourteen healthy, nonatopic, nonsmoking volunteers without airway hyperreactivity were enrolled (age: 38 +/- 13 yr [mean +/- SD]; FEV(1): 105 +/- 10% predicted; provocative dose of methacholine inducing a 20% decrease FEV(1) > 3,200 microgram). Ninety-six subjects (84%) produced adequate analysis samples. The subjects had a normal age distribution. Their induced sputum was rich in macrophages (69.2 +/- 13%) and neutrophils (27.3 +/- 13%), and poor in eosinophils (0.6 +/- 0.8%), lymphocytes (1.0 +/- 1.2%), and epithelial cells (1.5 +/- 1.8%). Only macrophages and neutrophils showed a normal distribution; total and differential counts of other cells did not. We propose that these data be used in comparison of the induced sputum cells of normal subjects and those of patients with airway inflammation.

Induced sputum: diagnostic value in interstitial lung disease

Induced sputum by inhalation of hypertonic saline solution is a noninvasive technique used to collect cellular and soluble material from lung airways. During the past decade, this method has been widely used to assess airway inflammation in asthma and chronic obstructive pulmonary disease, since it produces reliable results and compares favorably to other invasive techniques, such as biopsy and bronchoalveolar lavage (BAL). Induced sputum has been recently used to study interstitial lung disease (ILD), more specifically pneumoconiosis, sarcoidosis, and nongranulomatous ILD. Moreover, results from induced sputum supplied information comparable to BAL findings for occupational lung disease and were able to distinguish sarcoidosis patients from healthy subjects and from patients with nongranulomatous ILD. Although induced sputum had previously provided promising results in assessing patients with ILD, its diagnostic role has not yet been well defined. Further studies of the evaluation by induced sputum of grading of severity, follow-up of disease, and effects of treatment are needed. Additionally, to date no specific studies have been undertaken to evaluate the safety and functional effects of sputum induction on patients with ILD. In conclusion, we think that induced sputum can be used as a complementary tool to BAL both in research and in clinical monitoring of patients with ILD.

Induced sputum in children: feasibility, repeatability, and relation of findings to asthma severity

BACKGROUND

The collection of induced sputum provides a non-invasive method of investigating airway inflammation. Few studies have been performed in children, so a study was undertaken to determine the feasibility of sputum induction, the repeatability of eosinophil counts and sputum eosinophil cationic protein (ECP) levels, and the relation of these to current asthma severity. For comparison, serum ECP levels were also measured.

METHODS

In a cross sectional study of children aged 5-15 years, 27 healthy children and 60 with asthma underwent sputum induction using inhaled nebulised hypertonic saline. The whole sputum sample was used for analysis. Ten children with stable asthma repeated the procedure within 10 days.

RESULTS

A satisfactory sample (>500 non-squamous cells) was obtained in 61% of children with asthma and in 60% of healthy controls. The limits of agreement within subjects ranged from a 0.68 to 2.8 fold difference for eosinophil differential counts and from 0.38 to 4.4 fold for sputum ECP. Despite a median of 42% squamous cells, significant differences were found between asthma and healthy controls for the eosinophil differential count (p = 0.0004), total eosinophil counts (p = 0.03), and sputum ECP level (p = 0.0001). Overall, there was no correlation between any marker of airway inflammation and asthma severity, however expressed, including lung function.

CONCLUSIONS

Sputum induction is only possible in a proportion of children. The repeatability of sputum cell counts and ECP levels, measured in a small number of children, was similar to that reported in adults. Sputum analysis revealed no evidence of airway inflammation in a number of highly symptomatic children with asthma.

Induced sputum and bronchoalveolar lavage as tools for evaluating the effects of inhaled corticosteroids in patients with asthma

Changes in airway inflammation can be studied with bronchoalveolar lavage, but the widespread use of this procedure is limited by its invasiveness. The aim of this study was to evaluate the usefulness of induced sputum as a non-invasive alternative to bronchoalveolar lavage for studying changes in airway inflammation in patients with asthma. Thirty patients were treated for 12 weeks with an inhaled corticosteroid (fluticasone propionate (FP), 250 microg twice daily) or a short-acting beta-agonist (salbutamol (Sb), 400 microg twice daily) in a double-blind, double-dummy, randomized parallel group study. Sputum induction with hypertonic saline solution was performed twice before treatment and after 4, 8, 10, and 11 weeks of treatment. Bronchoalveolar lavage fluid divided into two pools (first 60 mL portion as bronchoalveolar lavage/bronchial wash (BAL/BW) and subsequent 80 mL as bronchoalveoalar lavage (BAL)) was obtained before and after 12 weeks of treatment. Changes in cell differentials and plasma-protein leakage (alpha2-macroglobulin, albumin, and their ratio (relative coefficient of excretion, RCE)) were analyzed in induced sputum and were compared with changes in BAL/BW and BAL. During treatment with FP, the PC20histamine (interpolated concentration of histamine that caused a fall in FEV1 of 20% of the baseline value) increased (P < .0001), and the percentage of eosinophils (P = .004), levels of (alpha2-macroglobulin (P = .09) and RCE (P = .007) decreased in sputum. These changes were different from those in the Sb group (PC20histamine P< .0001, eosinophils P= .004, alpha2-macroglobulin P= .003, RCE P = .01), in which alpha2-macroglobulin showed a significant increase (P = .015). Changes in the percentage of eosinophils and in the levels of alpha2-macroglobulin in sputum were associated with changes in the PC20histamine (Rs = -0.59, P = .007 and Rs = -0.47, P = .03, respectively). These correlations did not reach significance in BAL/BW and BAL fluid. The statistical power to detect changes in induced sputum was higher for the percentage of eosinophils and similar for plasma protein leakage as compared with analysis of BAL/BW and BAL fluid. We conclude that the analysis of induced sputum is a useful, non-invasive alternative to bronchoalveolar lavage for assessing the effects of antiinflammatory drugs in asthma.

Induced sputum: validity of fluid-phase IL-5 measurement

BACKGROUND

IL-5 measurement in the fluid phase of induced sputum is considered to be important in the assessment of asthma, but the validity of these measurements is uncertain.

OBJECTIVE

We investigated the validity of sputum IL-5 measurements through a series of spiking experiments and examined the effect of dithiothreitol (DTT) on these measurements.

METHODS

Induced sputum from 26 asthmatic subjects was spiked with IL-5 and processed, and the percentage of recovery was measured by means of immunoassay. In 6 of the 26 samples the effect of adding albumin to the processing fluids was studied. In 3 separate samples radiolabeled IL-5 was added, and the recovery measured by means of gamma counting and immunoassay were compared. In addition, the effect of DTT on the immunoassay was examined.

RESULTS

The mean +/- SD recovery of spiked IL-5 was 26.1% +/- 14.6% measured by means of immunoassay; adding albumin increased the recovery to 47.7% +/- 8.0% (P <.001). The mean recovery measured by means of gamma counting was 84.8% +/- 5.7% (P <.001); adding albumin had no effect on recovery. DTT had no significant effect on IL-5 measurement.

CONCLUSION

The validity of IL-5 measurement by means of current methods is poor. The discrepancy in recovery as measured by gamma counting compared with immunoassay suggests that there is a problem with the recognition of IL-5 epitopes by immunoassay in induced sputum. This cannot be attributed to DTT but may be due to other interfering substances present in sputum, such as sputum proteases, soluble receptors, or autoantibodies.

Airway mast cells and eosinophils correlate with clinical severity and airway hyperresponsiveness in corticosteroid-treated asthma

BACKGROUND

The relationship between airway inflammation and asthma severity in corticosteroid-treated asthma is unclear.

OBJECTIVES

Our purpose was to characterize the inflammatory cell profile of the airway lumen and epithelium in corticosteroid-treated asthma and to relate these findings to clinical and physiologic markers of asthma severity.

METHODS

Adults (n = 20) with asthma received standardized high-dose inhaled corticosteroid therapy with beclomethasone 2000 microgram per day for 8 weeks. Airway responsiveness to methacholine and hypertonic (4.5%) saline solution was then assessed, followed by sputum induction and, 1 week later, bronchoscopy with bronchoalveolar lavage and bronchial brush biopsy to assess inflammatory cells.

RESULTS

Clinical asthma severity was associated with airway hyperresponsiveness. Metachromatic cells were the main granulocyte present in bronchial brush biopsy specimens and correlated with airway responsiveness to saline solution (r = -0.75), methacholine (r = -0.74), peak flow variability (r = 0.59), and clinical asthma severity (r = 0.57). Eosinophils were the main granulocyte present in sputum and correlated with airway responsiveness to saline solution (r = -0.63) but not with other clinical markers of asthma severity. Bronchoalveolar lavage cell counts were not related to clinical asthma severity.

CONCLUSIONS

In asthmatic patients treated with cortico-steroids, the dominant inflammatory effector cell in the epithelium is the metachromatic cell, and in sputum it is the eosinophil. These cells correlate with the degree of airway hyperresponsiveness. Clinical asthma severity correlates with airway responsiveness and epithelial metachromatic cells. Induced sputum eosinophils and airway responsiveness to hypertonic saline solution may be useful markers of airway inflammation for clinical practice.

A long-term study of the antiinflammatory effect of low-dose budesonide plus formoterol versus high-dose budesonide in asthma

Adding inhaled long-acting beta(2)-agonists to a low dose of inhaled corticosteroids (ICS), results in better clinical asthma control than increasing the dose of ICS. However, this approach may mask underlying airway inflammation. In a double-blind parallel-group study, we evaluated the effect of adding formoterol to a low dose of budesonide, compared with a higher dose of budesonide, on the composition of induced sputum. After a 4-wk run-in period of treatment with budesonide (800 microg, twice daily), 60 patients with moderate asthma were randomly assigned to a 1-yr treatment with 400 microg of budesonide plus placebo, twice daily (BUD800), or 100 microg of budesonide plus 12 microg of formoterol, twice daily (BUD200+F). All drugs were administered via Turbuhaler. Budesonide (800 microg, twice daily) during run-in significantly reduced median sputum eosinophils from 4.5 to 0.68%. No significant changes in the proportion of eosinophils, EG2(+) cells, other inflammatory cells, or ECP levels in sputum were observed over the ensuing 1-yr treatment with BUD200+F or BUD800. Clinical asthma control was not significantly different between both groups. In conclusion, no significant differences in sputum markers of airway inflammation were observed during a 1-yr treatment with a low dose of inhaled budesonide plus formoterol compared with a higher dose of budesonide.

Once-daily theophylline reduces serum eosinophil cationic protein and eosinophil levels in induced sputum of asthmatics

BACKGROUND

Because eosinophilic airway inflammation is a characteristic feature of bronchial asthma, the treatment of airway inflammation is important in the management of asthma. Theophylline has been reported to reduce airway inflammation, in addition to its well-known bronchodilating effect.

OBJECTIVE

In order to evaluate the effects of theophylline on airway inflammation, we investigated 48 subjects with mild and moderate asthma.

METHODS

The patients were randomly divided into two groups, with or without theophylline treatment (control n = 24; theophylline, n = 24). We examined the level of serum eosinophil cationic protein (ECP), induced sputum samples, and peak expiratory flow (PEF) and obtained spirograms before and after 4 weeks of treatment with once-daily theophylline (200-600 mg/day) of subjects with mild or moderate asthma.

RESULTS

Theophylline significantly increased morning and evening PEF and significantly decreased the diurnal variation of PEF. After treatment with theophylline, both serum ECP and the percentage of eosinophils in induced sputum were significantly decreased. In contrast, peripheral blood eosinophil count was unchanged after treatment with theophylline.

CONCLUSIONS

These findings suggest that theophylline reduces airway inflammation and the severity of asthma, presumably via suppression of both eosinophil activity and subsequent eosinophil infiltration of the airways.

Ozone-induced inflammation assessed in sputum and bronchial lavage fluid from asthmatics: a new noninvasive tool in epidemiologic studies on air pollution and asthma

We investigated correlations between ozone-induced increases in inflammatory markers in induced sputum and in bronchial lavage fluid. Sixteen volunteers with intermittent asthma participated in a placebo-controlled parallel study with two exposures. Six days before and 16 h after the first exposure to ozone (0.4 ppm during 2 h) sputum was induced with hypertonic saline. This resulted in a significant increase in the sputum levels of eosinophil cationic protein (ECP; 1.8-fold; p = .03), neutrophil elastase (5.0-fold; p = .005) and the total cell number (1.6-fold; p = .02). After 4 weeks, a second exposure was randomized for air or ozone. Six days before and 16 h after the second exposure a bronchial lavage was performed. ECP values in sputum and in bronchial lavage fluid obtained after ozone correlated significantly (Rs = .79; p = .04), as did interleukin-8 (IL-8) values (Rs = .86; p = .01), and the percentage eosinophils (Rs = .89; p = .007). Moreover, the ozone-induced changes in percentage eosinophils observed in sputum and lavage fluid were highly correlated (Rs = .93; p = .003). In conclusion, changes in eosinophils, IL-8, and ECP markers induced by ozone and measured in sputum reflect the inflammatory responses in the lower airways of asthmatics, and may provide a noninvasive tool in epidemiologic studies on air pollution and asthma.

Neutrophilic inflammation in severe persistent asthma

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.