Sputum ECP levels correlate with parameters of airflow obstruction

Urine eosinophil-derived neurotoxin: A potential marker of activity in select eosinophilic disorders

BACKGROUND

Biomarkers of eosinophilic disease activity, especially in the context of novel therapies that reduce blood eosinophil counts, are an unmet need. Absolute eosinophil count (AEC) does not accurately reflect tissue eosinophilia or eosinophil activation. Therefore, the aims of this study were to compare the reliability of plasma and urine eosinophil major basic protein 1, eosinophil cationic protein, eosinophil-derived neurotoxin (EDN), and eosinophil peroxidase measurement and to evaluate the usefulness of eosinophil granule protein (EGP) measurement for the assessment of disease activity in patients with eosinophil-associated diseases treated with mepolizumab, benralizumab, or dexpramipexole.

METHODS

Eosinophil granule protein concentrations were measured in serum, plasma, and urine from healthy volunteers and patients with hypereosinophilic syndrome (HES), eosinophilic granulomatosis with polyangiitis (EGPA), and eosinophilic asthma using a multiplex assay.

RESULTS

Urine EGP concentrations remained stable, whereas serum and plasma EGP concentrations increased significantly with delayed processing. Plasma (p) EDN, but not urine (u) EDN, concentration correlated with AEC and negatively correlated with prednisone dose. Both pEDN and uEDN decreased significantly following treatment of HES patients with benralizumab and EGPA patients with mepolizumab. uEDN appeared to increase with clinical relapse in both patient groups.

CONCLUSIONS

Measurement of EGP in urine is noninvasive and unaffected by cellular lysis. Although plasma and urine EDN concentrations showed a similar pattern following benralizumab and mepolizumab treatment, the lack of correlation between AEC or prednisone dose and uEDN concentrations suggests that measurement of uEDN may provide a potential biomarker of disease activity in patients with HES and EGPA.

Regulation and directed inhibition of ECP production by human neutrophils

Background

Neutrophils are involved in the pathophysiology of allergic asthma, where the Eosinophil Cationic Protein (ECP) is a critical inflammatory mediator. Although ECP production is attributed to eosinophils, we reported that ECP is also present in neutrophils from allergic patients where, in contrast to eosinophils, it is produced in an IgE-dependent manner. Given the key role of ECP in asthma, we investigated the molecular mechanisms involved in ECP production as well as the effects induced by agonists and widely used clinical approaches. We also analyzed the correlation between ECP production and lung function.

Methods

Neutrophils from allergic asthmatic patients were challenged with allergens, alone or in combination with cytokines, in the presence of cell-signaling inhibitors and clinical drugs. We analyzed ECP levels by ELISA and confocal microscopy. Lung function was assessed by spirometry.

Results

IgE-mediated ECP release is dependent on phosphoinositide 3-kinase, the extracellular signal-regulated kinase (ERK1/2) and the production of reactive oxygen species by NADPH-oxidase. Calcineurin phosphatase and the transcription factor NFAT are also involved. ECP release is enhanced by the cytokines interleukin (IL)-5 and granulocyte macrophage-colony stimulating factor, and inhibited by interferon-γ, IL-10, clinical drugs (formoterol, tiotropium and budesonide) and allergen-specific IT. We also found an inverse correlation between asthma severity and ECP levels.

Conclusions

Our results suggest the molecular pathways involved in ECP production and potential therapeutic targets. We also provide a new method to evaluate disease severity in asthmatic patients based on the quantification of in vitro ECP production by peripheral neutrophils.

Exposure-Response and Clinical Outcome Modeling of Inhaled Budesonide/Formoterol Combination in Asthma Patients

Exposure-response and clinical outcome (CO) model for inhaled budesonide/formoterol was developed to quantify the relationship among pharmacokinetics (PK), pharmacodynamics (PD) and CO of the drugs and evaluate the covariate effect on model parameters. Sputum eosinophils cationic proteins (ECP) and forced expiratory volume (FEV1) were selected as PD markers and asthma control score was used as a clinical outcome. One- and two-compartment models were used to describe the PK of budesonide and formoterol, respectively. The indirect response model (IDR) was used to describe the PD effect for ECP and FEV1. In addition, the symptomatic effect on the disease progression model for CO was connected with IDR on each PD response. The slope for the effect of ECP and FEV1 to disease progression were estimated as 0.00008 and 0.644, respectively. Total five covariates (ex. ADRB2 genotype etc.) were searched using a stepwise covariate modeling method, however, there was no significant covariate effect. The results from the simulation study were showed that a 1 puff b.i.d. had a comparable effect of asthma control with a 2 puff b.i.d. As a result, the 1 puff b.i.d. of combination drug could be suggested as a standardized dose to minimize the side effects and obtain desired control of disease compared to the 2 puff b.i.d.

Immunological and hematological effects of IL-5(Rα)-targeted therapy: An overview

IL‐5 is an important cytokine for priming and survival of mature eosinophils and for proliferation and maturation of their progenitors. Hence, IL‐5(Rα) targeting will be increasingly used in diseases where eosinophils are the key immune effector cells such as eosinophilic asthma (EA), hypereosinophilic syndrome (HES), eosinophilic esophagitis (EE), and eosinophilic granulomatosis with polyangiitis (EGPA). Therefore, several neutralizing monoclonal antibodies directed against IL‐5 (mepolizumab and reslizumab) and its receptor IL‐5Rα (benralizumab) have found or will find their way to the clinic. While the clinical effect of these drugs has been extensively investigated and reviewed, the understanding of the underlying immunological and hematological mechanisms remains less clear. This review will discuss the translational outcomes of treatment with these monoclonal antibodies in humans to shed light on the mechanisms underlying the main immunological and hematological findings from these clinical trials in humans.

Eosinophil Cationic Protein Concentrations among Crop and Dairy Farmers with Asthma

OBJECTIVE

To assess the mean serum eosinophil cationic protein (s-ECP) concentrations among crop and dairy farmers and office controls, and further examine its relation to exposure duration, smoking habit, as well as presence or absence of asthma.

METHODS

A cross-sectional survey was performed including examined group (EG), composed by agricultural workers (87 crop - EG1 and 83 dairy farmers - EG2), and control group (CG) composed by 80 office workers within the same enterprise. We have used a questionnaire to record the chronic respiratory symptoms, detailed work history, specific farming activities and tasks performed and smoking history. Evaluation of examined subjects also included lung function tests, diagnosis of asthma, and measurement of s-ECP as a marker of inflammation.

RESULTS

The main finding of the present study is that s-ECP concentrations were raised in subjects with asthma independent of the smoking habit. The mean s-ECP concentrations were higher in subjects of EG1 and EG2 compared with those in CG, but without reaching statistical significance. Mean s-ECP concentrations were significantly higher among subjects in EG1 exposed more than 20 years, while mean s-ECP concentrations were non-significantly higher in subjects of EG2 exposed more than 20 years, compared to those exposed less than 20 years. Mean s-ECP concentrations were higher among smokers within all three groups, but without reaching statistical significance between smokers and non-smokers. Mean s-ECP concentrations were significantly higher in subjects with asthma within EG1 (P = 0.049) and EG2 (P = 0.040), but also within those in CG (P = 0.046).

CONCLUSION

Data obtained suggest that airway inflammation is present in farmers with asthma, and s-ECP is an important biomarker in means of reflecting disease severity and prognosis among exposed workers.

Are sputum eosinophil cationic protein and eosinophils differently associated with clinical and functional findings of asthma?

BACKGROUND

Sputum eosinophil counts and eosinophil cationic protein (ECP) levels are usually increased in asthmatic patients. The correlation between sputum eosinophils or ECP and clinical findings of asthma has been previously investigated but many of these studies have been performed on small samples of asthmatic patients, considering only few clinical indices and often including patients on oral or inhaled corticosteroids, which might be confounding when interpreting the relationship between disease activity and airway inflammation.

OBJECTIVE

To assess whether sputum eosinophils and ECP were differently related to functional and clinical parameters of asthma in a large number of steroid-naïve asthmatic patients, taking into account several potential determinants of activity and chronicity of asthma.

METHODS

One hundred and twenty-nine patients with mild-moderate asthma were studied. Sputum was induced by hypertonic saline inhalation and processed using the whole sample method.

RESULTS

Sputum eosinophils and ECP significantly correlated with each other (r = 0.41, P < 0.001). When patients were grouped on the basis of high/low sputum eosinophils and high/low sputum ECP levels, significant differences were observed among groups, with patients with high sputum eosinophils and ECP showing the greatest asthma severity. In the overall sample, disease duration inversely correlated with sputum eosinophils, whereas FEV1 and peak expiratory flow (PEF) inversely correlated with sputum ECP. Rescue β2 -agonist use and total symptom score positively correlated with both eosinophil counts and sputum ECP. Stepwise regression analysis showed that symptom score and disease duration accounted for 17.6% of sputum eosinophil variance, whereas symptom score and FEV1 accounted for 14.7% of sputum ECP variance.

CONCLUSIONS AND CLINICAL RELEVANCE

Both sputum eosinophils and ECP are weakly related to clinical markers of asthma severity. However, ECP was more closely related to lung function parameters than eosinophil counts.

Development of a suspension array assay in multiplex for the simultaneous measurement of serum levels of four eosinophil granule proteins

The concentrations of major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil derived neurotoxin (EDN) and eosinophil peroxidase (EPO) have been associated with eosinophilic disease severity. Whereas a variety of techniques have been used to measure individual eosinophil granule protein concentration, none of these methods efficiently measures MBP, ECP, EDN and EPO simultaneously. A multiplex suspension array system was developed to simultaneously measure the concentrations of MBP, ECP, EDN and EPO in serum. The assay showed excellent inter- and intra-assay reliability, and serum levels of MBP, ECP and EDN from eosinophilic subjects analyzed by ELISA and multiplex were highly correlated (r=0.8579; P<0.0001, r=0.6356; P=0.0006 and r=0.8600; P<0.0001, respectively, Spearman rank correlation). Moreover, the multiplex assay required 500-fold less serum than a single ELISA to achieve comparable sensitivity. Absolute eosinophil count and eosinophil surface expression of the activation marker, CD69, were significantly correlated with concentrations of MBP, EDN and EPO, but not ECP, in serum from eosinophilic subjects. Furthermore, subjects with eosinophilic gastrointestinal disorder and normal peripheral absolute eosinophil counts (<0.5×10(9)/l) had significantly increased concentrations of MBP (P<0.0001), ECP (P<0.0001), EDN (P=0.0001) and EPO (P<0.0001) compared to normal donors. In summary, the eosinophil granule protein multiplex assay provides a rapid and reliable way to measure eosinophil granule protein levels and should prove useful in assessing patterns of degranulation in patients with eosinophilic disorders.

Eosinophilic esophagitis: asthma of the esophagus?

The question whether eosinophilic esophagitis (EoE) might be an 'asthma of the esophagus' is reasonable. There are a number of similarities between the two diseases: EoE and asthma, as well as other atopic diseases, are frequently associated and have a number of similarities in their pathogenesis. Thus, investigating differences and similarities between the diseases might be a worthwhile endeavor. Both EoE and asthma are chronic immune-mediated conditions characterized by inflammatory changes in the mucosa and submucosa with a characteristic and diagnostic infiltration of eosinophils. They result in organ dysfunction with considerable morbidity and (in the case of asthma) even mortality. Asthma and EoE affect all ages, but frequently start in childhood or adolescence. While asthma has seen a large increase in its prevalence in the past 50 years, EoE was first described in the 1970s. Since then the frequency of the diagnosis of EoE has increased significantly. The prevalence for both diseases seems to be highest in the Western world. In contrast to asthma, where females are more often affected, EoE is more frequent in males. Asthma in children, however, is also more common in boys, but this changes after puberty. EoE is frequently associated with asthma, and up to 80% of patients with EoE are atopic, similar to childhood asthma. Adult-onset asthma is not necessarily associated with atopy (termed intrinsic asthma) and similar observations have been made for EoE. Endoscopically, asthmatic airway mucosa as well as esophageal mucosa in EoE can appear normal, and biopsies are required for diagnosis. Long-standing disease in asthma has been associated with 'remodeling' compared to predominantly reversible inflammatory changes early in the course of the disease. Similar observations have been made in EoE. Toxic proteins derived from eosinophils such as major basic protein, eosinophil-derived neurotoxin and eosinophil cationic protein can be found in the mucosa of both diseases, which are also characterized by a thickening of the lamina propria or basement membrane, respectively. Despite these histologic and immunochemistry findings, asthma as well as EoE remain clinical diagnoses, and diagnosing either condition can be challenging. Therapeutically, both diseases respond well to corticosteroids. Ironically, corticosteroids for inhalation are deliberately swallowed in EoE to reach the esophageal mucosa. Allergen/food avoidance can improve symptoms in asthma and EoE. Taken together, allergic asthma and EoE have a number of common features which make a common pathogenesis manifested in different organs for reasons not yet fully understood likely. Combining allergological research with gastroenterologic and pneumologic expertise with a focus on similarities between these diseases might be a way forward.

Eosinophils as diagnostic tools in chronic lung disease

Chronic lung diseases are very common and form a major threat to large proportions of the population with increased morbidity and mortality. Asthma is one of the most common eosinophilic airway diseases. However, there is growing evidence that eosinophilic inflammation is also important in subgroups of patients with chronic obstructive pulmonary disease, chronic cough and idiopathic pulmonary fibrosis. Several studies have shown that sputum eosinophilia is associated with a favorable response to treatment of corticosteroids in both asthma and chronic obstructive pulmonary disease, and tailored strategies aimed to normalize sputum eosinophils have resulted in a significant reduction in exacerbation rates. In this article, the authors review the role of eosinophilic inflammation in the diagnosis and management of chronic respiratory diseases.

Airway eosinophilia in remission and progression of asthma: accumulation with a fast decline of FEV(1)

BACKGROUND

As it is unknown whether complete asthma remission or progression of asthma is associated with airway inflammation and remodeling, we assessed these characteristics in bronchial biopsies of relevant subsets of asthma patients.

METHODS

Sputum and bronchial biopsies were obtained from asthma patients in remission (PC(20) histamine> 32 mg/ml, PC(20) AMP> 320 mg/ml) and from those with either a slow FEV(1) decline (< 30 ml/year) or fast decline (> 30 ml/year). Inflammatory cells and mediators were determined in sputum, inflammatory cells and aspects of airway remodeling in bronchial biopsies.

RESULTS

Asthmatics in remission and asthma patients with a slow FEV(1) decline had a similar extent of airway inflammation and remodeling in sputum and bronchial biopsies. Asthma patients with a fast FEV(1) decline had high sputum eosinophil numbers. Moreover, FEV(1) decline (ml/year) correlated with sputum eosinophil numbers (Rs=0.51, p=0.003) and ECP levels (Rs=0.57, p=0.001). Airway remodeling, i.e. basement membrane thickness, correlated with sputum eosinophils (Rs=0.69, p<0.001), sputum ECP (Rs=0.46, p=0.018) and airway wall eosinophil numbers (Rs=0.49, p=0.002).

CONCLUSIONS

Asthma, even when in remission, is accompanied by airway inflammation and remodeling. Data suggest that eosinophils are important in a subset of asthma patients by association to accelerated FEV(1) decline and change of basement membrane thickness.

Occupational and environmental lung disease: occupational asthma

Occupational exposures cause 10-15% of new-onset asthma in adults, and that represents a considerable health and economic burden. Exposure to many causative agents is now well controlled but workplace practices are constantly evolving and new hazards being introduced. Overall, there is no good evidence that the incidence of occupational asthma is decreasing. Evidence-based guidelines such as those published by the British Occupational Health research Foundation and Standards of Care documents should help raise awareness of the problem and improve management. Key targets include the control of occupational exposures, a high index of suspicion in any adult with new onset asthma, and early detailed investigation.

A multivariate analysis of risk factors for the air-trapping asthmatic phenotype as measured by quantitative CT analysis

BACKGROUND

Patients with severe asthma have increased physiologically measured air trapping; however, a study using CT measures of air trapping has not been performed. This study was designed to address two hypotheses: (1) air trapping measured by multidetector CT (MDCT) quantitative methodology would be a predictor of a more severe asthma phenotype; and (2) historical, clinical, allergic, or inflammatory risk factors could be identified via multivariate analysis.

METHODS

MDCT scanning of a subset of Severe Asthma Research Program subjects was performed at functional residual capacity. Air trapping was defined as >or= 9.66% of the lung tissue < - 850 Hounsfield units (HU). Subjects classified as having air trapping were then compared to subjects without air trapping on clinical and demographic factors using both univariate and multivariate statistical analyses.

RESULTS

Subjects with air trapping were significantly more likely to have a history of asthma-related hospitalizations, ICU visits, and/or mechanical ventilation. Duration of asthma (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.08 to 1.87), history of pneumonia (OR, 8.55; 95% CI, 2.07 to 35.26), high levels of airway neutrophils (OR, 8.67; 95% CI, 2.05 to 36.57), airflow obstruction (FEV(1)/FVC) [OR, 1.61; 95% CI, 1.21 to 2.14], and atopy (OR, 11.54; 95% CI, 1.97 to 67.70) were identified as independent risk factors associated with the air-trapping phenotype.

CONCLUSIONS

Quantitative CT-determined air trapping in asthmatic subjects identifies a group of individuals at high risk for severe disease. Several independent risk factors for the presence of this phenotype were identified: perhaps most interestingly, history of pneumonia, neutrophilic inflammation, and atopy.

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.

Asthma management in police study

Asthma is a common condition and, therefore, may be seen by the clinical forensic physician and police in widely different circumstances ranging from the autopsy room to roadside breath alcohol testing. This paper concentrates on the assessment and treatment of asthmatics detained in custody and does not refer to the Road Traffic Act provisions. A careful history and objective recording of simple severity markers and peak expiratory flow rate should identify patients who may require hospitalization or urgent treatment. Asthma mortality may be reduced by better understanding of the disease and its treatment and by greater use of prophylactic rather than reliance on relief therapy for bronchospasm.

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.

Assessment of inhaled BDP-dose dependency of exhaled nitric oxide and local and serum eosinophilic markers in steroids-naive nonatopic asthmatics

The aim of the present study was to assess the dose-dependency from inhaled steroids of changes of airways inflammation [eosinophils count and eosinophil cationic protein (ECP)] measures in induced sputum and in serum, as well as that of exhaled nitric oxide. Twenty steroid-naive patients with nonatopic asthma of mild to moderate degree [forced expiratory volume in 1 s (FEV1) = 70% of predicted] and with negative response to the standard tests for allergy were selected; after a 1-week run-in period they were randomized to receive a 12-week treatment period of inhaled beclomethasone dipropionate dry powder given with the Pulvinal inhaler (Clenil P, Chiesi Farmaceutici S.p.A., Parma, Italy) in two different dose regimens, 400 microg bid (high dose) or 200 microg bid (low dose), over a double blind, parallel groups design. The following outcome measures were assessed in baseline and after 1, 6 and 12 weeks of treatment: FEV1 (l), eosinophils count in sputum (%), is ECP (microg/l), serum eosinophils count (%), serum ECP (microg/l) and exhaled NO (ppb). The results showed that all the considered parameters improved in both groups: the increase over baseline of FEV1 and the decrease of NO were significant at any time in the high-dose group and only at week 12 in the low-dose group (NS between groups), whereas the markers of eosinophilic activity showed more consistent reductions in the high-dose than in the low-dose group when measured in induced sputum (P < 0.05 between groups after 6 and 12 weeks for eosinophils count and after 12 weeks for ECP). Decreases over baseline of markers measured in serum were more rapid in the high-dose group, without differences between groups. A marked trend towards a negative correlation was found between FEV1 and ECP, (r = -0.72, P < 0.05), between FEV1 and eosinophils in sputum (r = -0.31, NS) and between FEV1 and exhaled NO (r = -0.38, NS), all of them only in the high-dose group. The results of the study demonstrate that changes of levels of eosinophilic activity in the airways are dependent from the daily dose of inhaled steroids when measured in induced sputum and that the local assessment can therefore represent a practical and noninvasive method to monitor the extent of airways inflammation.

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.

Comparison of the effects of repetitive low-dose and single-dose antigen challenge on airway inflammation

BACKGROUND

Airway allergen provocation provides a model to study allergic inflammation in relationship to pulmonary physiology. Allergen provocation is usually administered as a relatively large single-dose challenge that might not reflect a chronic, natural, low-dose airborne allergen exposure.

OBJECTIVE

We sought to compare the magnitude, characteristic features, and kinetics of airway inflammation induced by means of repetitive low-dose antigen challenges with those factors induced by means of an equivalent single-dose allergen challenge in allergic asthma.

METHODS

This was a 2-period crossover study. During separate phases, each subject was administered either a predetermined single-dose antigen challenge or 25% of that dose on each of 4 consecutive days. The airway response to allergen challenge was determined by means of measurement of pulmonary function and sputum features of inflammation, including eosinophil, eosinophil-derived neurotoxin, and fibronectin levels.

RESULTS

Both models of antigen challenge caused significant and equivalent sputum eosinophilia. The immediate decrease in FEV(1) and the FEV(1)/forced vital capacity ratio and the increase in sputum eosinophilia, eosinophil-derived neurotoxin, and fibronectin levels occurred gradually over the first 3 low doses and then reached a plateau or tended to decrease with the fourth antigen exposure.

CONCLUSION

Our data suggest that although the 2 challenge models had similar quantitative effects on lung function and sputum eosinophilia, the qualitative responses and kinetics of these changes were distinct. Repetitive low doses of antigen, as might mimic natural allergy exposure, produced an equivalent inflammatory response to the large single-dose challenge but with a smaller amount of antigen, suggesting that priming and accumulative effects might have occurred. Moreover, our limited data also suggest that immunologic tolerance might be induced by frequent challenges.

Inhibition by fenoterol of human eosinophil functions including beta2-adrenoceptor-independent actions

Agonists at beta2 adrenoceptors are used widely as bronchodilators in treating bronchial asthma. These agents also may have important anti-inflammatory effects on eosinophils in asthma. We examined whether widely prescribed beta2-adrenoceptor agonists differ in ability to suppress stimulus-induced eosinophil effector functions such as superoxide anion (O2-) generation and degranulation. To examine involvement of cellular adhesion in such responses, we also investigated effects of beta2 agonists on cellular adhesion and on CD11b expression by human eosinophils. O2- was measured using chemiluminescence. Eosinophil degranulation and adhesion were assessed by a radioimmunoassay for eosinophil protein X (EPX). CD11b expression was measured by flow cytometry. Fenoterol inhibited platelet-activating factor (PAF)-induced O2- generation by eosinophils significantly more than salbutamol or procaterol. Fenoterol partially inhibited PAF-induced degranulation by eosinophils similarly to salbutamol or procaterol. Fenoterol inhibited phorbol myristate acetate (PMA)-induced O2- generation and degranulation by eosinophils, while salbutamol or procaterol did not. Fenoterol inhibition of PMA-induced O2- generation was not reversed by ICI-118551, a selective beta2-adrenoceptor antagonist. Fenoterol, but not salbutamol or procaterol, significantly inhibited PAF-induced eosinophil adhesion. Fenoterol inhibited O2- generation and degranulation more effectively than salbutamol or procaterol; these effects may include a component involving cellular adhesion. Inhibition also might include a component not mediated via beta2 adrenoceptors.

Effect of physical and chemical methods of homogenization on inflammatory mediators in sputum of asthma patients

BACKGROUND

Dithiothreitol (DTT), which is used for sputum homogenization, may split S-S bonds of the bronchial mucins as well as other proteins and, thus, may have a detrimental effect on inflammatory mediators that are present in sputum.

OBJECTIVE

To evaluate the effects of physical sputum homogenization, using ultrasonic and chemical (ie, DTT) means, on the concentrations of eosinophil cationic protein (ECP), eosinophil protein X (EPX), eosinophil peroxidase (EPO), and myeloperoxidase (MPO) in the sputum of patients with asthma.

METHODS

The collection of sputum samples from nine patients with asthma was induced by their inhaling a sterile 3% saline solution for 10 min from an ultrasonic nebulizer. One half of the sputum sample was homogenized by ultrasound, and the other half was liquefied by DTT. The supernatant of the ultrasonically homogenized specimen was divided into the following three portions: (1) immediately frozen; (2) stored for 15 min at 37 degrees C; and (3) additionally treated with DTT. The supernatant of the sputum sample that was liquefied by DTT was divided into the following two portions: (1) immediately frozen; and (2) additionally subjected to ultrasound. The concentrations of ECP, EPO, EPX, and MPO in the sputum samples were measured using immunoassays.

RESULTS

Statistically significant differences were found between the ultrasonically homogenized specimens that had been either processed immediately or stored at 37 degrees C and those treated by DTT, but only for concentrations of EPO and MPO (p < 0.005). No effect of temperature on the mediators in the ultrasonically homogenized specimens could be detected. Ultrasonic homogenization had no influence on the mediators in the samples liquefied by DTT. However, the addition of DTT to the cell-free supernatant of the ultrasonically homogenized sputum samples caused a significant fall in measured EPO and MPO concentrations.

CONCLUSIONS

The sputum processing by DTT caused a statistically significant fall in EPO and MPO concentrations but did not significantly influence the measured concentrations of ECP and EPX.

The serum levels of eosinophil cationic protein (ECP) are related to the infiltration of eosinophils in the tumours of patients with Hodgkin's disease

We have previously described a relation between abundance of eosinophilic granulocytes in Hodgkin's disease (HD) tumours and poor prognosis. In order to further explore the importance of the eosinophilic infiltration, we immunohistochemically examined the presence of eosinophils, using the monoclonal antibodies EG 1 and EG 2, in the tumours of 54 newly diagnosed patients with HD and related the degree of infiltration to clinical characteristics and the serum levels of eosinophil cationic protein (S-ECP). S-ECP levels (upper normal value 16 micrograms/l) varied between 2.2 and 71.7 micrograms/l, mean 25.4 micrograms/l. There was an association (p = 0.01) between the number of eosinophils in the tumour tissue and S-ECP. S-ECP levels were also associated to high erythrocyte sedimentation rate (ESR, p < 0.01) and nodular sclerosis (NS) histology (p < 0.05), and there was a tendency of a correlation to bulky disease (p = 0.06). The number of eosinophils stained with EG 2 correlated to high ESR (p < 0.05), and to high leukocyte count (p = 0.02). A follow-up value of S-ECP after treatment was, in most of the cases measured, lower than the initial value. The high values of S-ECP in several patients with HD probably originates from eosinophils infiltrating the tumours. The same patients had a higher ESR and tended to have a more advanced stage and bulky disease. There are no significant correlations with disease-free and overall survival, as the follow-up time is short, and prognosis favourable.

Sputum induction as a research tool for sampling the airways of subjects with cystic fibrosis

BACKGROUND

Sputum induction (SI) has proved to be a reliable non-invasive tool for sampling inflammatory airway contents in asthma, with distinct advantages over collection of expectorated sputum (ES) and bronchoalveolar lavage (BAL). A study was undertaken to evaluate the safety of SI and to assess if it might be an equally valuable outcome tool in patients with cystic fibrosis (CF).

METHODS

The safety of the procedure was examined and sample volume, cell counts, cytokine concentrations, and bacterial culture results obtained by SI, spontaneous ES, and fibreoptic bronchoscopy were compared in 10 adults with CF.

RESULTS

SI was well tolerated and was preferred to BAL by all subjects. The mean (SE) sample volume obtained by SI was significantly greater than ES (6.74 (1.46) ml v 1.85 (0.33) ml, p = 0.005). There was no significant difference in the number of cells per ml of sample collected. There was a difference in the mean (SD) percentage of non-epithelial, non-squamous cells collected (67 (28)%, 86 (21)%, and 99 (1)% for ES, SI, and BAL, respectively). These percentage counts were different between ES and both SI and BAL (p=0.03 and p=0.006, respectively). Cell differential counts (excluding squamous cells) from all collection methods were similar (mean (SD) 84 (9)%, 87 (7)%, and 88 (11)% polymorphonuclear cells for ES, SI, and BAL, respectively). The concentrations of interleukin (IL)-8 and tumour necrosis factor (TNF)-alpha were the same in all three samples when corrected for dilution using urea concentration. The test specific detection rate for recovery of bacteriological pathogens was 79% for SI, 76% for ES, and 73% for BAL.

CONCLUSION

SI offers safety advantages over BAL and may be a more representative airway outcome measurement in patients with CF.

Increased eosinophil cationic protein levels in bronchoalveolar lavage from wheezy infants

Although studies examining the serum suggest a role for eosinophils in wheezing episodes in infants and toddlers, the presence of a chronic eosinophilic inflammation within their airways remains to be demonstrated. In this study we investigated whether eosinophil cationic protein (ECP) levels are increased in BAL fluid (BALF) from infants and toddlers with recurrent wheezing episodes, during an asymptomatic period. The levels of ECP in BALF were quantitated by radioimmunoassay in 61 children (36 with severe recurrent episodes of wheezing and 25 who were non-wheezy), aged 6-36 months, in whom flexible bronchoscopy was clinically indicated. BALF eosinophil counts were < or = 1% in all patients and did not differ in wheezers, compared to non-wheezers. In contrast, ECP levels in BALF were > or = 2.2 micrograms/l in 18 of 36 (50%) wheezy infants but in only three of 25 (12%) control infants (p < 0.01). Neutrophil counts were significantly higher in the wheezer group than in the non-wheezer group (8.1 x 10(3) cells/ml vs. 3.0 x 10(3) cells/ml). ECP levels in the BALF were not correlated with the absolute number of eosinophils (r = 0.03; p = 0.8) but were correlated with the absolute number of neutrophils (r = 0.54; p = 0.001). There was no association between high ECP levels in BALF and the atopic status of the wheezers. In conclusion, ECP levels are increased in BALF from young children with recurrent wheezing episodes, even during relatively quiescent periods, suggesting a chronic increased cell activation in the lower airways.

Association between airway hyperreactivity and bronchial macrophage dysfunction in individuals with mild asthma

Little is known about the functional capabilities of bronchial macrophages (BMs) and their relationship to airway disease such as asthma. We hypothesize that BMs from asthmatics may be modulated in their function compared with similar cells from healthy individuals. BMs obtained by induced sputum from mild asthmatics (n = 20) and healthy individuals (n = 20) were analyzed using flow cytometry for CD16, CD64, CD11b, CD14, and human leukocyte antigen-DR expression, phagocytosis of IgG opsonized yeast, and oxidant production. Asthma status was assessed by lung function [percent predicted forced vital capacity and forced expiratory volume in 1 s (FEV(1))], percent sputum eosinophils, and nonspecific airway responsiveness [provocative concentration that produces a 20% fall in FEV(1) (PC(20,FEV1))]. Asthmatics with >5% airway eosinophils (AEo+) had decreased BM CD64 expression and phagocytosis compared with asthmatics with <5% eosinophils (AEo-). Among asthmatics, a significant correlation was found between CD64 expression and BM phagocytosis (R = 0.7, P < 0.009). Phagocytosis was also correlated with PC(20,FEV1) (R = 0.6, P < 0.007), lung function (%predicted FEV(1), R = 0.7, P < 0.002) and percent eosinophils (R = -0.6, P < 0.01). In conclusion, BM from asthmatics are functionally modulated, possibly by Th2 cytokines involved in asthma pathology.

Detection and treatment of early asthma

BACKGROUND

We sought answers to two questions: 1) how can mild, early asthma best be detected? 2) how should it be treated and the treatment effect monitored?

METHODS

Eighty adult patients with early, mostly mild asthma and 30 control subjects were examined by lung-function and biochemical tests. Patients were randomly assigned to two treatment groups. One group was treated with an inhaled steroid (budesonide) for 6 weeks, and the other first with an inhaled beta2-agonist (terbutaline) for 6 weeks and then with an inhaled steroid for 2 weeks.

RESULTS

Treatment with budesonide was effective: symptom scores, PEF, blood eosinophils, and sputum ECP values all improved. Terbutaline was ineffective by these criteria. For the detection of early asthma and for the following treatment effects, sputum and serum ECP assays are useful supplements to lung-function tests.

CONCLUSIONS

Treatment of early, mild asthma with an inhaled steroid is effective and worthwhile. Detection of the disease remains a problem, as both lung-function and biochemical tests have low sensitivities.

Characterization of chemokine CCR3 agonist-mediated eosinophil recruitment in the Brown-Norway rat

1. The ability of various C-C chemokines to elicit tissue eosinophil infiltration following intradermal injection or peripheral blood eosinophilia following intravenous injection were compared in the Brown-Norway rat. 2. Eotaxin (0.1 - 3 microg site-1) of human and murine origin produced equivalent, dose-dependent increases in eosinophil peroxidase activity in rat dermis 4 h post-injection. 3. Human eotaxin-2 was equipotent with human eotaxin in terms of dermal eosinophil recruitment. Other human CCR3 agonists, such as MCP-3, RANTES and MCP-4 failed to increase dermal eosinophil peroxidase activity at doses up to 1 microg site-1 whereas the latter did produce a small effect at 3 microg site-1. 4. Consistent with observations in vivo, human eotaxin displaced [125I]-eotaxin from rat spleen membranes more potently (IC50=2 nM) than did MCP-4 (IC50=500 nM). RANTES did not compete with the radiolabelled chemokine at concentrations up to 1 microM. 5. Human eotaxin (5 microg) administered intravenously increased circulating eosinophils approximately 3 fold whereas MCP-4 (5 microg i.v.) increased circulating monocytes approximately 3 fold without affecting eosinophil numbers. 6. Dexamethasone pretreatment inhibited eotaxin-induced dermal eosinophil influx only at a steroid dose (0.1 mg kg-1, s.c.) which significantly reduced circulating eosinophil numbers. The steroid also reduced eosinophilia in peripheral blood resulting from systemic eotaxin administration (5 microg, i.v.). 7. These data suggest differences in rat CCR3 relative to other species as surmised from a distinctive rank order of chemokine potency. In addition to its chemotactic effects eotaxin, but not MCP-4, promotes eosinophil recruitment into the circulation. One of the mechanisms by which glucocorticoids, such as dexamethasone, acutely inhibits eotaxin-induced dermal eosinophil influx is to diminish the circulating numbers of these cells available for tissue recruitment.

Major basic protein, but not eosinophil cationic protein or eosinophil protein X, is related to atopy in cystic fibrosis

Increased eosinophil granule proteins have been described in serum and sputum samples of patients with cystic fibrosis (CF). It has been assumed that eosinophil degranulation is enhanced in atopic subjects - as in asthmatics. Since in CF no differences in eosinophil cationic protein (ECP), eosinophil protein X (EPX), and eosinophil peroxidase between atopic and nonatopic subjects have been detected, we investigated whether major basic protein (MBP) is increased in serum and sputum samples derived from atopic (n = 14) compared with nonatopic CF subjects (n = 26). In CF patients, high mean serum (sputum) levels of ECP 29.7 microg/l (2.7 mg/l), EPX 53.7 microg/l (7.9 mg/l), and MBP 984.6 microg/l but low sputum MBP levels (57.4 microg/l) were measured. In addition, in serum and in sputum samples, a significant correlation between MBP and ECP (P<0.03 and P<0.0001, respectively) or EPX (P<0.05 and P<0.0004, respectively) was detected. By subdivision of the patients into allergic and nonallergic subjects, significant differences were found for serum MBP values only(mean 1382.2 microg/l vs. 770.5 microg/l; P<0.0001), but not for ECP or EPX serum levels or for eosinophil proteins in sputum. Although no differences between atopic and nonatopic CF patients in ECP and EPX were found, serum MBP levels were higher in patients sensitized to inhalant allergens than in nonsensitized subjects. These results indicate differential release of eosinophil granule proteins in peripheral blood from eosinophils, and they also indicate that MBP in serum likely is to be a better discriminator of atopy in CF.

Relationship between induced sputum cell counts and fluid-phase eosinophil cationic protein and clinical or physiologic profiles in mild asthma

BACKGROUND

Sputum analysis is the only non-invasive method to examine airway inflammatory processes in subjects with asthma. The aim of this study was to investigate the relationship between cell counts and fluid phase levels in induced sputum in subjects with mild asthma, and the severity of asthma as assessed by clinical, physiologic and blood measurements.

METHODS

Forty patients with mild asthma, aged 17 to 49 years were studied (good sputum sample only from 31). On the first day, spirometry and methacholine challenges were performed. After 2 to 4 days, venous blood for absolute eosinophil count and eosinophil cationic protein (ECP) measurement was obtained and sputum was induced by inhalation of hypertonic saline. For the next 15 days subjects recorded their peak expiratory flow (PEF), symptom scores, and beta2-agonist requirements twice daily. Differential counts of leukocytes were done on cytospin preparations of homogenized sputum and the supernatant was examined for eosinophil cationic protein (ECP).

RESULTS

Sputum eosinophil counts and not neutrophil, epithelial cells, macrophages, or lymphocytes, were inversely correlated to FEV1/FVC % (r = -.57, P = .0008) and to PC20-methacholine (r = -.40, P = .024). No statistical relationship was obtained between eosinophil counts and either symptom scores, bronchodilator requirements, or daily PEF variability. Sputum ECP values were correlated to FEV1/FVC% (r = -.41, P = .026) but not to PC20 (r = -.32, P = .08) or clinical scores or PEF variation. A trend to significance was appreciated between peripheral blood and sputum eosinophil counts (r = .34, P = .067) and no relationship was found between sputum and serum ECP values (r = .10, P = .38).

CONCLUSIONS

Although sputum markers give some information about disordered lung function and physiologic changes in the airways, they are not the only factors concerned in the clinical expression of mild asthma.

Eosinophils in the bronchial mucosa in relation to methacholine dose-response curves in atopic asthma

Asthma is characterized by both local infiltration of eosinophils in the bronchial mucosa and bronchial hyperreactivity (BHR). A detailed characterization of BHR implies analysis of a histamine or methacholine dose-response curve yielding not only the dose at 20% fall of baseline forced expiratory volume in 1 s (FEV1), but also a plateau (P) representing the maximal narrowing response in terms of percent change in FEV1 and reactivity as the steepest slope at 50% of P (%FEV1/doubling dose). In the baseline condition, the specific airway conductance (sGaw) may be considered closely related to airway lumen diameter. In 20 nonsmoking asthmatic patients, methacholine dose-response curves were obtained, and a sigmoid model fit yielded the BHR indexes. Immunohistochemistry with the monoclonal antibodies (EG1 and EG2) was used to recognize the total number of eosinophils and activated eosinophils, respectively. The number of activated eosinophils was significantly correlated to both P (r = 0.62; P < 0.05) and sGaw (r = -0.52; P < 0.05), whereas weaker and nonsignificant correlations were found for dose at 20% fall of baseline FEV1 and the total number of eosinophils. We conclude that the number of activated eosinophils can be considered a marker of the inflammation-induced decrease of airway lumen diameter as represented by the plateau index and sGaw.

Eosinophilic inflammation assessed by induced sputum in corticosteroid-dependent asthma

Sputum induction can be used to study airway inflammation in asthmatics. However, it has not been used in patients with corticosteroid-dependent asthma requiring long-term oral corticosteroids. The aim of the study was to assess the number of eosinophils and the levels of eosinophil cationic protein (ECP) in sputum of 17 corticosteroid-dependent asthmatics by comparison with nine mild untreated asthmatics, 10 moderate asthmatics receiving inhaled steroids (ICS) and 11 healthy subjects. In the 17 corticosteroid-dependent asthmatics, we examined sputum eosinophil markers on two occasions and correlated with the control of asthma. Eosinophils were undetectable in controls and were detected in 63.8% of asthmatics. There were no significant differences between the three groups of asthmatics. ECP levels were significantly increased in ICS or corticosteroid-dependent asthmatics by comparison to controls and mild asthmatics. There was no significant difference between ICS and corticosteroid-dependent asthmatics. During follow-up, corticosteroid-dependent asthmatics with a controlled disease had no significant change in eosinophil numbers or ECP levels. On the other hand, corticosteroid-dependent asthmatics with recent exacerbations had a non-significant increase in eosinophil numbers and a significant increase in ECP levels. This study shows that ECP levels may be more accurate than eosinophil numbers in assessing exacerbations in corticosteroid-dependent asthmatics.

Serum measurement of eosinophil cationic protein in the management of asthma

Asthma is a disease characterized by chronic eosinophilic inflammation of the airways. Serum eosinophil cationic protein (ECP) has been increasingly used as a noninvasive inflammatory marker in asthma. The serum ECP level seems to reflect, although indirectly, the intensity of ongoing eosinophilic inflammation of the airways and respond sensitively to intervention, whereas it is unlikely to be useful for establishing the diagnosis of asthma in an individual patient. Monitoring of serum ECP could be of utility in the long-term follow-up of asthmatic patients. However, further longitudinal studies are required to establish the role of serum ECP measurement in the treatment modulation in asthma.

Sputum analysis, bronchial hyperresponsiveness, and airway function in asthma: results of a factor analysis

BACKGROUND

Recent studies have shown weak associations among FEV1, bronchial hyperresponsiveness (BHR), sputum eosinophils, and sputum eosinophil cationic protein (ECP), suggesting that they are nonoverlapping quantities. The statistical method of factor analysis enables reduction of many parameters that characterize the disease to a few independent factors, with each factor grouping associated parameters.

OBJECTIVE

The purpose of this study was to demonstrate, by using factor analysis, that reversible airway obstruction, BHR, and eosinophilic inflammation of the bronchial tree, as assessed by cytologic and biochemical analysis of sputum, may be considered separate dimensions that characterize chronic bronchial asthma.

METHODS

Ninety-nine clinically stable patients with a previous diagnosis of asthma underwent spirometry, sputum induction, and histamine inhalation tests.

RESULTS

Most patients were nonobstructed (FEV1, 91% +/- 20%); a low level of bronchial reversibility (FEV1 increase after beta2 -agonist, 7.8% +/- 9.2%) and BHR (histamine PC20 FEV1 geometric mean, 0.98 mg/mL) were found. Sputum eosinophil differential count (12.4% +/- 17.7%) and sputum ECP (1305 +/- 3072 microg/mL) were in the normal range of our laboratory in 38 and 22 patients, respectively. Factor analysis selected 3 different factors, explaining 74.8% of variability. Measurements of airway function and age loaded on factor I, PC20 FEV1 and beta2 -response loaded on factor II, and sputum ECP and eosinophils loaded on factor III. Additional post hoc factor analyses provided similar results when the sample was divided into 2 subgroups by randomization, presence of airway obstruction, degree of BHR, percentage of sputum eosinophils, or concentration of sputum ECP.

CONCLUSIONS

We conclude that airway function, baseline BHR, and airway inflammation may be considered separate dimensions in the description of chronic asthma. Such evidence supports the utility of routine measurement of all these dimensions.

Inflammatory response after inhalation of bacterial endotoxin assessed by the induced sputum technique

BACKGROUND

Organic dusts may cause inflammation in the airways. This study was performed to assess the usefulness of the induced sputum technique for evaluating the presence of airways inflammation using inhaled endotoxin (lipopolysaccharide) as the inducer of inflammation.

METHODS

To characterise the inflammatory response after inhalation of endotoxin, 21 healthy subjects inhaled 40 micrograms lipopolysaccharide and were examined before and 24 hours after exposure. Examinations consisted of a questionnaire for symptoms, spirometric testing, blood sampling, and collection of induced sputum using hypertonic saline. Eleven of the subjects inhaled hypertonic saline without endotoxin exposure as controls. Cell counts, eosinophilic cationic protein (ECP), and myeloperoxidase (MPO) were determined in blood and sputum.

RESULTS

A significantly higher proportion of subjects reported respiratory and general symptoms after endotoxin inhalation. MPO and the number of neutrophils in the blood were higher and spirometric values were decreased after the lipopolysaccharide challenge. In the sputum MPO, ECP, and the numbers of neutrophils and lymphocytes were higher after the lipopolysaccharide challenge. No significant differences were found after the inhalation of hypertonic saline compared with before, except for a significantly lower number of lymphocytes in the sputum.

CONCLUSIONS

The results support previous studies that inhaled endotoxin causes an inflammation at the exposure site itself, as well as general effects. Sampling of sputum seems to be a useful tool for assessing the presence of airways inflammation, and the inhalation of hypertonic saline used to induce sputum did not significantly interfere with the results found after inhalation of lipopolysaccharide.

Induced sputum eosinophil cationic protein (ECP) measurement in asthma and chronic obstructive airway disease (COAD)

BACKGROUND

Induced sputum is a useful way to monitor airway inflammation in asthma, but cell counts are time-consuming and labour intensive.

OBJECTIVE

The aim of this study was to evaluate a novel processing method using eosinophil cationic protein (ECP) as a biochemical marker of sputum eosinophil number and activation in subjects with asthma and other airway diseases.

METHODS

Sputum was dispersed with dithiothreitol and centrifuged to yield cell free supernatant and a cell pellet. The pellet was treated with a cellular lysis buffer to release cell-associated ECP. ECP was measured in sputum supernatant and in the lysed cell pellet and was compared with sputum eosinophil counts in 31 adults with asthma, chronic obstructive airway disease (COAD), bronchiectasis and healthy controls. The ratio of supernatant to pellet ECP was evaluated as an index of eosinophil degranulation. The effect of sputum processing reagents and storage time on ECP measurement was also evaluated.

RESULTS

ECP measured in the cell pellet lysate correlated closely with sputum absolute eosinophil counts across a range of subject groups (r = 0.72, P = 0.004). Sputum eosinophil counts were less well correlated with supernatant ECP levels (r = 0.54, P < 0.05). Incubation with dithiothreitol or lysis buffer did not influence ECP measurement and sputum ECP levels were stable over a 6-9 month period. Sputum supernatant and pellet lysate ECP concentrations were increased in stable asthma, asthma exacerbations and COAD/bronchiectasis (P < 0.05). The ratio of supernatant to pellet ECP was used as an index of eosinophil degranulation and found to be elevated in asthma exacerbations, COAD and bronchiectasis, but not in stable asthma.

CONCLUSION

The measurement of ECP in the sputum cell pellet provides a reliable and efficient estimate of sputum eosinophil counts which can potentially be used in clinical trials and epidemiological surveys. The ECP ratio may be a useful marker of eosinophil activation, and was increased in asthma exacerbation and COAD. The increased ECP in COAD reflects a non-selective accumulation of eosinophils in this condition.

Role of eosinophilic airway inflammation in models of asthma

Eosinophils play a central role in the establishment and outcome of bronchial inflammation in asthma. Animal models of allergy are useful to answer questions related to mechanisms of allergic inflammation. We have used models of sensitized and boosted guinea pigs to investigate the nature of bronchial inflammation in allergic conditions. These animals develop marked bronchial infiltration composed mainly of CD4+ T-lymphocytes and eosinophils. Further provocation with antigen leads to degranulation of eosinophils and ulceration of the bronchial mucosa. Eosinophils are the first cells to increase in numbers in the mucosa after antigen challenge and depend on the expression of alpha 4 integrin to adhere to the vascular endothelium and transmigrate to the mucosa. Blockage of alpha 4 integrin expression with specific antibody prevents not only the transmigration of eosinophils but also the development of bronchial hyperresponsiveness (BHR) to agonists in sensitized and challenged animals, clearly suggesting a role for this cell type in this altered functional state. Moreover, introduction of antibody against Major Basic Protein into the airways also prevents the development of BHR in similar model. BHR can also be suppressed by the use of FK506, an immunosuppressor that reduces in almost 100% the infiltration of eosinophils into the bronchi of allergic animals. These data support the concept that eosinophil is the most important pro-inflammatory factor in bronchial inflammation associated with allergy.

Cytolysis and piecemeal degranulation as distinct modes of activation of airway mucosal eosinophils

BACKGROUND

Cytotoxic eosinophil granule proteins are considered important in the pathogenesis of inflammatory airway diseases, including asthma, rhinitis, and polyposis. However, little is known about the mechanisms involved in the deposition of these tissue-damaging granular products in vivo.

OBJECTIVE

We sought to determine the occurrence of degranulating eosinophils, those with morphologic evidence of cytolysis with associated clusters of free eosinophil granules (Cfegs), and to identify the frequency of apoptotic eosinophils in inflamed upper airway tissue.

METHODS

Eosinophil-rich nasal polyps were processed for transmission electron microscopy and for light microscopic evaluation of whole-mount preparations subjected to deep tissue staining for eosinophil peroxidase.

RESULTS

The mean proportion of eosinophil subtypes were intact and resting (6.8%), intact but degranulating (83%), cytolytic or Cfegs (9.9%), and apoptotic (0.0%). All degranulating eosinophils exhibited piecemeal degranulation. The occurrence of Cfegs was confirmed in nonsectioned whole-mount preparations. Depending on the appearance of their core and matrix, the specific granules were divided into four subtypes, and a degranulation index (altered per total granules) was calculated for each eosinophil. Cytolytic eosinophils had a much lower degranulation index than intact eosinophils present in the same tissue (P < .001).

CONCLUSIONS

These data indicate that eosinophil cytolysis is present in human airway mucosa, that its occurrence is not an artifact of the means of tissue handling, and that cytolysis of eosinophils may occur without prior extensive degranulation. We suggest that eosinophil cytolysis is a major activation mechanism, which occurs along with, but is distinct from, other types of degranulation.

Clinical implication of protein levels of IL-5 in induced sputum in asthmatic patients

To determine whether protein levels of interleukin-5 (IL-5) in induced sputum reflect the degree of eosinophilic inflammation, we evaluated the role of IL-5 on clinical characteristics in stable asthmatic patients. IL-5 level, differential eosinophil count, and level of eosinophil cationic protein (ECP) in induced sputum were all significantly higher for asthmatics than for normal controls. Both eosinophil counts and ECP levels in induced sputum were inversely correlated with the degree of airflow limitation (FEV1/FVC). In addition, patients with measurable IL-5 in sputum had significantly more eosinophils, higher levels of ECP in sputum, and lower FEV1 (percent predicted) than did patients with levels of IL-5 beneath the limit of detection. However, we found no significant difference in IL-5 levels between atopic and nonatopic asthmatics. IL-5 level in induced sputum is a good indicator of eosinophilic inflammation in atopic and nonatopic asthmatic patients.

Serum level of eosinophil cationic protein in patients with chronic cough: relationship to blood eosinophils and airway hyperresponsiveness

We measured the serum level of eosinophil cationic protein (ECP), determined the blood eosinophil count, and assessed pulmonary function by spirometry and airway responsiveness to methacholine in 80 patients with a cough lasting longer than 3 weeks without an obvious cause. The serum level of ECP was above the cutoff value of 15.7 ng/mL (mean + 2 SD in 105 healthy control adults) in 30 (37.5%) of 80 patients (high-serum-ECP group). The blood eosinophil count was significantly higher in the high-serum-ECP group than in the normal-serum-ECP group (p < 0.01). The cumulative dose of methacholine causing a 35% decrease in respiratory conductance (PD35Grs) was significantly lower in the high-serum-ECP group than in the normal-serum-ECP group (p < 0.001). The serum concentration of ECP was correlated with the blood eosinophil count and the PD35Grs (r = 0.59, p < 0.001 and r = -0.48, p < 0.001, respectively). These findings suggest a possible role for serum level of ECP in management of patients with chronic cough.

CD11b and L-selectin expression on eosinophils and neutrophils in blood and induced sputum of patients with asthma compared with normal subjects

BACKGROUND

Patients with asthma show altered surface expression of the adhesion molecules CD11b and L-selectin on airway granulocytes compared with blood granulocytes.

OBJECTIVE

To investigate whether this modulation is related to disease activity or due to transendothelial migration, we compared the CD11b and L-selectin expression on blood and induced sputum eosinophils and neutrophils between patients with asthma and normal subjects.

METHODS

Eleven normal subjects (21-43 years), nine patients (21-34 years) with mild atopic asthma and 10 patients (20-47 years) with moderate to severe atopic asthma on regular treatment with inhaled steroids underwent sputum induction by inhalation of nebulized hypertonic saline (4.5%). CD11b and L-selectin expression on granulocytes from blood and DTT-homogenized sputum were analysed by flow cytometry. Eosinophils could be discriminated from neutrophils by using depolarized light scatter. Disease activity was assessed by baseline FEV1 and airway responsiveness to histamine (PC20).

RESULTS

Sputum eosinophils showed higher expression of CD11b (P<0.001) and lower expression of L-selectin (P<0.001) compared with peripheral blood eosinophils. CD11b and L-selectin expression on eosinophils from blood or sputum did not differ between the three groups. Similar results were obtained for neutrophils. The PC20 in the patients with moderate-to-severe asthma was related to CD11b expression on blood (R=-0.92, P=0.001) and sputum eosinophils (R=0.75, P=0.02).

CONCLUSIONS

Flow cytometry of induced sputum granulocytes from asthmatic as well as normal subjects is feasible. We conclude that the modulated expression of CD11b and L-selectin on airway granulocytes is not specific for asthmatic airway inflammation, but is probably the result of tissue migration per sé. This implies that CD11b and L-selectin expression on granulocytes in induced sputum cannot be used as marker of disease activity.

Brittle asthma

We believe that the asthma phenotypes we have defined as types 1 and 2 brittle asthma appear to be defined subgroups of asthma. For example, we have characterised patients with type 1 brittle asthma, as defined in this review, on the basis of peak flow variability and treatment and these patients remain a separate group when assessed by other means such as psychosocial factors, immunoglobulin levels, and atopy. The question remains as to whether they are truly separate groups with entirely different pathogenetic influences or whether they simply represent the severe end of the spectrum. Our suggested classification into types 1 and 2 forms a useful start for studies of this condition, although prospective evaluation of patients with severe asthma is the only way of substantiating the validity of these definitions which will then enable investigation of possible mechanisms. However, these patients are rare and in order to study them as a group a national register would need to be set up along the lines of the West Midlands Brittle Asthma Register, perhaps recruiting all "at risk" patients and then using this resource as a means of exploring the different asthma phenotypes within this broad grouping, including brittle asthma.

Safety of inducing sputum in patients with asthma of varying severity

Inducing sputum using hypertonic saline is a noninvasive method to investigate airway inflammation in people with asthma. However, hypertonic saline may also induce bronchoconstriction in some patients. The aim of the study was to examine whether the overall safety of using hypertonic saline to induce sputum in patients with mild to moderate asthma could be extended to patients with severe and/or uncontrolled asthma. Nine control subjects and 64 asthmatic patients with varying severity of the disease (FEV1 40-126% predicted values) were studied. Twenty-one of those patients had uncontrolled asthma. Sputum was induced in a standardized manner using hypertonic saline. The safety of the procedure was evaluated by assessing the clinical response and measuring FEV1 just before and during sputum induction. The procedure was well tolerated in most patients, but it had to be stopped due to side effects in 11.6% of patients with severe asthma. None of the side reactions were severe. Few patients with uncontrolled (17.3%) or severe asthma (18.6%) had a drop in FEV1 of 10-20%. The fall in FEV1 was significantly greater in patients with severe asthma than those with mild disease (p < 0.02 Mann-Whitney U test). We conclude that hypertonic saline-induced sputum is a safe technique even in patients with severe asthma.

The effect of theophylline on blood and sputum eosinophils and ECP in patients with bronchial asthma

It was recently reported that theophylline has an anti-inflammatory and bronchodilating effect on bronchial asthma. Accordingly, to examine the anti-inflammatory effect of theophylline on asthma, especially its effect on eosinophil activation, a sustained-release theophylline preparation (Theolong) was administered (daily dose: 400 mg) to 18 patients with mild to moderate bronchial asthma. This was done in order to study the preparation's effects on lung function, blood and sputum eosinophils and ECP four weeks pre- and post-administration. Lung function was determined by spirometry and sputum by induced sputum. Blood and sputum ECP levels were determined using an ECP RIA kit. In lung function, there were no differences in vital capacity (VC) or in forced expiratory volume 1 s (FEV 1.0) pre- and post-administration. There were also no differences in the number of blood and sputum eosinophils, but serum and sputum ECP levels decreased. Theophylline is thus expected to exert an inhibitory effect on eosinophil activation and it is suggested as an effective therapeutic drug for bronchial asthma.

Serum eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in childhood asthma: the influence of atopy

The purpose of this study was to determine the value of serum measurements of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in diagnosing asthma in children, and to investigate the influence of concomitant allergic diseases and atopic sensitization, assessed by skin prick tests (SPT), on these markers. ECP and EPX were determined in 36 children with asthma, in 33 children with other symptoms from lower airways disease (OSLA), and in 166 control children. Sixteen children with asthma but no anti-inflammatory therapy had significantly higher concentrations of ECP and EPX (ECP: 27.5 microg/L, P < 0.001; EPX: 59.9 microg/L, P < 0.001) than the control children (ECP: 11.2 microg/L; EPX: 26.2 microg/L). In the 20 children on anti-inflammatory therapy, ECP values were similar to those of controls. The children with OSLA (ECP: 13.6 microg/L, P < 0.01; EPX: 47.2 microg/L, P < 0.001) differed significantly from controls. When using the value of 24.7 microg/L (97.5 percentile in the 68 non-atopic controls) as a pathologic upper limit for ECP, 10 (63%) of the 16 asthmatic children on no maintenance medication, two (10%) of the 20 asthmatics on maintenance therapy, and 11 (33%) of the 33 children with OSLA had high ECP; the same figure was only 18 (11%) in the 166 control children. Both ECP and EPX had a significant association with allergic disorders and with SPT reactivity. In multivariate logistic regression analysis, an elevated ECP was significantly associated with asthma (OR 2.3, 95%CI 1.1-4.9) and atopic dermatitis (2.9, 1.2-6.9), and an elevated EPX was significantly associated with asthma (2.61, 1.19-5.74) and allergic rhinoconjunctivitis (5.23, 1.46-18.73). We conclude that serum concentrations of both ECP and EPX are higher in asthmatic than in healthy children. However, other allergic diseases, such as allergic rhinoconjunctivitis, atopic dermatitis, and allergic skin sensitization also raise the concentrations of these markers. This limits their usefulness in the diagnosis of childhood asthma.

Serum eosinophil cationic protein as a marker of eosinophilic inflammation in asthma

BACKGROUND

The serum level of eosinophil cationic protein (ECP) has been used as a clinical marker in asthma, on the assumption that it reflects ongoing eosinophilic inflammation of the airways. However, only a few studies have investigated this issue, using bronchial secretions but not tissue specimens.

OBJECTIVE

To evaluate cross-sectionally the correlation between serum ECP level or blood eosinophil count, and the degree of eosinophilia in bronchoalveolar lavage fluid (BALF) and bronchial biopsy tissue, and disease activity, in asthmatic patients.

METHODS

Thirty-three adults with symptomatic asthma and six healthy controls were studied. The blood eosinophil count, ECP levels in serum and BALF, percentage of eosinophils in BALF, number of eosinophils in bronchial tissue, pulmonary function, and methacholine bronchial responsiveness of these subjects were clarified. An asthma severity score and inhaled beta2-agonist requirement (puffs/day) were also assessed for the asthmatic patients.

RESULTS

The asthmatic patients, compared with the controls, had more obstructive (as tested by %FEV1, FEV1/FVC, and FEF25-75%) and more responsive airways, and showed a significant increase in the number of eosinophils in the blood, BALF, and tissue, and in the serum ECP levels. The ECP levels in BALF were below the detection limit for most of the subjects in both groups examined. In the asthmatic patients, serum ECP level demonstrated correlations with the number or percentage of eosinophils in BALF and tissue, whereas the blood eosinophil count correlated only with the percentage of eosinophils in BALF. Serum ECP level correlated with all indices of disease activity examined; %FEV1, FEV1/FVC, FEF25-75% bronchial responsiveness, severity score and beta2-agonist usage, whereas the blood eosinophil count correlated only with %FEV1 and bronchial responsiveness.

CONCLUSION

The data suggest that serum ECP level reflects the intensity of eosinophilic airway inflammation, as well as the disease activity, and may be useful as an inflammatory marker in asthma.

Correlation between exhaled nitric oxide, sputum eosinophils, and methacholine responsiveness in patients with mild asthma

BACKGROUND

Eosinophils in induced sputum and exhaled nitric oxide (NO) are currently used as non-invasive markers in the assessment of airway inflammation in asthma. As both sputum eosinophils (%) and exhaled NO are raised in asthmatic subjects not receiving inhaled steroids and decreased following corticosteroid therapy, a relationship between them is plausible.

METHODS

Exhaled NO was measured by chemiluminescence analyser, sputum induction by 3.5% saline inhalation, and bronchial responsiveness was measured as PC20FEV1 methacholine in 35 stable asthmatic patients using beta 2 agonist alone and the correlation between these non-invasive markers of airway inflammation was studied.

RESULTS

There were significant correlations between exhaled NO and PC20 (r = -0.64), exhaled NO and sputum eosinophils (%) (r = 0.48), and also between sputum eosinophils (%) and PC20 (r = -0.40).

CONCLUSION

The correlation between exhaled NO and PC20 suggests that exhaled NO or the mechanisms leading to its increase may contribute to airway hyperresponsiveness in asthma. Furthermore, the relationship between sputum eosinophils (%), exhaled NO, and PC20 highlight the potential use of eosinophils (%) in induced sputum and exhaled NO to monitor the severity of asthma.