Blood eosinophil number and activity in relation to lung function in patients with asthma and with eosinophilia

Label-free optical hemogram of granulocytes enhanced by artificial neural networks

An outstanding challenge for immunology is the classification of immune cells in a label-free fashion with high speed. For this purpose, optical techniques such as Raman spectroscopy or digital holographic microscopy have been used successfully to identify immune cell subsets. To achieve high accuracy, these techniques require a post-processing step using linear methods of multivariate processing, such as principal component analysis. Here we demonstrate for the first time a comparison between artificial neural networks and principal component analysis (PCA) to classify the key granulocyte cell lineages of neutrophils and eosinophils using both digital holographic microscopy and Raman spectroscopy. Artificial neural networks can offer advantages in terms of classification accuracy and speed over a PCA approach. We conclude that digital holographic microscopy with convolutional neural networks based analysis provides a route to a robust, stand-alone and high-throughput hemogram with a classification accuracy of 91.3 % at a throughput rate of greater than 100 cells per second.

Surfactant protein D alleviates eosinophil-mediated airway inflammation and remodeling in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Surfactant protein D (SPD) is a member of the collectin family that lines the airway epithelial cells with host defense. However, the role of SPD in the pathogenesis of aspirin-exacerbated respiratory disease (AERD) is still unclear.

METHODS

The serum SPD level was measured in patients with AERD (n = 336), those with aspirin-tolerant asthma (ATA, n = 442), and healthy controls (HC, n = 104). Polymorphisms of SFTPD in the study subjects were analyzed. The effect of LTE4 on SPD production through eosinophil infiltration was investigated in BALB/c mice. The protective function of SPD against eosinophils inducing inflammation and remodeling was assessed in vitro/vivo. The potential efficacy of nintedanib against airway remodeling through the production of SPD was evaluated.

RESULTS

The serum SPD level was significantly lower (P < .001) in AERD compared with ATA patients, and negatively correlated with fall in FEV₁ (%) after lysine-aspirin bronchoprovocation test and/or the urinary LTE4 level. In addition, polymorphism of SFTPD at rs721917 was significantly different in the study subjects (odds ratio, 1.310; 95% confidence intervals, 2.124-3.446; P = .002). LTE4-exposed mice showed an increased eosinophil count with a decreased SPD level in bronchoalveolar lavage fluid. Eosinophils increased α-smooth muscle actin expression in airway epithelial cells, which was attenuated by SPD treatment. Furthermore, nintedanib protected the airway epithelial cells against eosinophils by enhancing the production of SPD.

CONCLUSION

The decreased level of SPD in AERD was associated with airway inflammation/remodeling under the eosinophilic condition, suggesting that modulation of SPD may provide a potential benefit in AERD.

Biological function of eosinophil extracellular traps in patients with severe eosinophilic asthma

Eosinophil extracellular traps (EETs), a complex of DNA fibers and cytotoxic granule proteins, are implicated in the development of asthma; however, the pathophysiological function of EETs in immune responses has not been fully determined. The present study investigated the characteristics of EETs from patients with non-severe asthma (NSA, n = 20) and severe eosinophilic asthma (SEA, n = 20) and evaluated EET function. The percentage of EET-forming peripheral blood eosinophils stimulated with IL-5 and LPS was significantly higher in patients with SEA than in those with NSA (P = 0.009). This percentage negatively correlated with baseline FEV₁ (r = -0.350, P = 0.027) and positively correlated with serum eosinophil-derived neurotoxin levels in asthmatic subjects (r = 0.437, P = 0.018). In addition, EET formation was markedly associated with reactive oxygen species production (r = 0.750, P < 0.001). These EETs exhibited an autocrine function to induce eosinophil degranulation, which led to granule protein production. Airway epithelial cells stimulated with EETs exhibited increased epithelial detachment and permeability and pro-inflammatory cytokine release. However, EETs were not significantly associated with mast cell activation. The present study suggests that peripheral blood eosinophils from patients with SEA may be more activated to produce EETs than those from patients with NSA, which further induces inflammation in asthmatic airways. Therefore, regulation of EET formation and function may be a novel therapeutic approach for asthma management.

Effect of prenatal waterpipe tobacco smoke on airway inflammation in murine model of asthma of adult offspring mice

OBJECTIVE

Worldwide popularity of waterpipe tobacco smoking has increased, including in pregnant women. This study investigates the effect of prenatal waterpipe tobacco smoke (WTS) exposure on airway inflammation in a murine model of asthma of adult offspring mice.

MATERIALS AND METHODS

Pregnant BALB/c mice were exposed to fresh air or WTS, using a whole-body exposure system that mimics human use during WTS. Adult male offspring mice were divided into; (1) control (prenatal fresh air, postnatal ovalbumin sensitization and saline challenge), (2) postnatal Ova S/C (prenatal fresh air, postnatal ovalbumin sensitization and challenge (Ova S/C)), (3) prenatal WTS (prenatal WTS, postnatal ovalbumin sensitization and saline challenge) and (4) prenatal WTS + postnatal Ova S/C. Cells from the bronchoalveolar lavage fluid, cytokines, and oxidative stress markers (superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and thiobarbituric acid reactive substances (TBARS)) from lung homogenates were evaluated.

RESULTS

Prenatal WTS increased recruitment of cells in lungs and levels of SOD and catalase when compared to unexposed offspring's. The levels of cytokines, GPx and TBARS were not affected by prenatal WTS. Prenatal WTS exposure and postnatal Ova S/C increased airway inflammation and activity of SOD compared to control and Ova S/C mice and reduced IL-18 levels compared to Ova S/C mice.

DISCUSSION AND CONCLUSIONS

Prenatal exposure to WTS induced airway inflammation, further enhanced by a murine model of asthma in adult offspring. Prenatal exposure to WTS adversely affects the lung function of the offspring and careful strategies for increasing public awareness regarding the harmful effects of WTS during pregnancy is important.

Blood biomarkers in chronic airways diseases and their role in diagnosis and management

INTRODUCTION

The complexity and heterogeneous nature of asthma and chronic obstructive pulmonary disease (COPD) results in difficulties in diagnosing and treating patients. Biomarkers that can identify underlying mechanisms, identify patient phenotypes and to predict treatment response could be of great value for adequate treatment. Areas covered: Biomarkers play an important role for the development of novel targeted therapies in airways disease. Blood biomarkers are relatively non-invasive, easy to obtain and easy to apply in routine care. Several blood biomarkers are being used to diagnose and monitor chronic airways diseases, as well as to predict response to treatment and long-term prognosis. Blood eosinophils are the best studied biomarker, the most applied in clinical practice, and until now the most promising of all blood biomarkers. Other blood biomarkers, including serum periostin, IgE and ECP and plasma fibrinogen are less studied and less relevant in clinical practice. Recent developments include the use of antibody assays of many different cytokines at the same time, and 'omics' techniques and systems medicine. Expert commentary: With the exception of blood eosinophils, the use of blood biomarkers in asthma and COPD has been rather disappointing. Future research using new technologies like big-data analysis of blood samples from real-life patient cohorts will probably gain better insight into underlying mechanisms of different disease phenotypes. Identification of specific molecular pathways and associated biomarkers will then allow the development of new targets for precision medicine.

Effect of waterpipe tobacco smoking on airway inflammation in murine model of asthma

OBJECTIVE

There has been an increase in the popularity of waterpipe tobacco smoking (WTS) worldwide, especially in the younger population, including asthma patients. In this study, we investigated the effects of waterpipe smoking on airway inflammation, cytokine levels and oxidative stress markers in an antigen-driven murine model of asthma.

MATERIALS AND METHODS

Balb/c mice were divided into four groups; (1) control (received fresh air, ovalbumin sensitization and saline challenge), (2) WTS (received WTS, ovalbumin sensitization and saline challenge), (3) Ova S/C (received fresh air, ovalbumin sensitization and ovalbumin challenge) and (4) simultaneous WTS and Ova S/C (received WTS, ovalbumin sensitization and ovalbumin challenge). Airway inflammatory cells were evaluated in the broncho-alveolar lavage fluid. Cytokines [interleukin (IL)-13, 10 and 18] and oxidative stress markers [superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx)] were evaluated in the lung homogenates.

RESULTS

Chronic exposure to WTS significantly increased the number of airway inflammatory cells in mice, specifically: eosinophils, neutrophils, macrophages and lymphocytes. The level of IL-13 in the lungs was increased and the level of IL-10 was reduced (p < 0.05) by WTS. Chronic WTS potentiated the increase in inflammatory cells induced by Ova S/C (p < 0.05). The level of IL-13 in the lungs was increased by simultaneous WTS and Ova S/C (p < 0.05) while, levels of IL-10, IL-18, SOD, catalase and GPx in the lungs were not affected.

CONCLUSIONS

Chronic WTS exposure induced airway inflammation in control mice and enhanced airway inflammation in murine model of asthma.

New Insights in Oxidant Biology in Asthma

Research over the past 30 years has identified mechanistic biochemical oxidation pathways that contribute to asthma pathophysiology. Redox imbalance is present in asthma and strongly linked to the pathobiology of airflow obstruction, airway hyperreactivity, and remodeling. High levels of reactive oxygen species, reactive nitrogen species, and oxidatively modified proteins in the lung, blood, and urine provide conclusive evidence for pathologic oxidation in asthma. Concurrent loss of antioxidants, such as superoxide dismutases and catalase, is attributed to redox modifications of the enzymes, and further amplifies the oxidative injury in the airway. The presence of high levels of urine bromotyrosine, an oxidation product of eosinophil peroxidase, identifies activated eosinophils, and shows promise for use as a noninvasive biomarker of poor asthma control.

Blood eosinophils as a marker of likely corticosteroid response in children with preschool wheeze: time for an eosinophil guided clinical trial?

Childhood wheezing is common particularly in children under the age of 6 years and in this age group is generally referred to as preschool wheezing. Particular diagnostic and treatment uncertainties exist in these young children due to the difficulty in obtaining objective evidence of reversible airways narrowing and inflammation. A diagnosis of asthma depends on the presence of relevant clinical signs and symptoms and the demonstration of reversible airways narrowing on lung function testing, which is difficult to perform in young children. Few treatments are available and inhaled corticosteroids are the recommended preventer treatment in most international asthma guidelines. There is, however, considerable controversy about its effectiveness in children with preschool wheeze and a corticosteroid responder phenotype has not been established. These diagnostic and treatment uncertainties in conjunction with the knowledge of corticosteroid side effects, in particular the reduction of growth velocity, have resulted in a variable approach to inhaled corticosteroid prescribing by medical practitioners and a reluctance in carers to regularly administer the treatment. Identifying children who are likely responders to corticosteroid therapy would be a major benefit in the management of this condition. Eosinophils have emerged as a promising biomarker of corticosteroid responsive airways disease, and evaluation of this biomarker in sputum has successfully been employed to direct management in adults with asthma. Obtaining sputum from young children is time consuming and difficult, and it is hard to justify more invasive procedures such as a bronchoscopy in young children routinely. Recently, in children, interest has shifted to assessing the value of less invasive biomarkers of likely corticosteroid response and the biomarker 'blood eosinophils' has emerged as an attractive candidate. The aim of this review was to summarize the evidence for blood eosinophils as a predictive biomarker for corticosteroid responsive disease with a particular focus on the difficult area of preschool wheeze.

Serum decoy receptor 3 is a biomarker for disease severity in nonatopic asthma patients

BACKGROUND/PURPOSE

Decoy receptor 3 (DcR3), a soluble receptor of the tumor necrosis factor receptor superfamily, is a pleiotropic immunomodulator. The aim of this study was to investigate serum DcR3 levels in atopic and nonatopic asthma patients.

METHODS

The serum DcR3 levels of 70 adults with asthma and 20 healthy controls were determined by enzyme-linked immunosorbent assay (ELISA). The asthma patients were divided into atopic and nonatopic subgroups, based on the presence or absence of immunoglobulin E (IgE) specific to allergen. Correlations between serum DcR3 levels and blood total-eosinophil counts, forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity (FVC), and Asthma Control Test (ACT) scores were analyzed.

RESULTS

The mean serum DcR3 level was significantly higher in asthma patients than in healthy controls (266.1 ± 60.6 pg/mL vs. 63.7 ± 21.9 pg/mL, p = 0.003), but there was no significant difference between the mean serum DcR3 level of asthma patients with atopy (37 patients) and patients without atopy (33 patients; 298.7 ± 111.2 pg/mL vs. 230.6 ± 38.5 pg/mL, p = 0.064). However, the serum DcR3 level was positively correlated with the total eosinophil count (r = 0.448, p = 0.012) and inversely correlated with the percentages of predicted FEV1, FEV1/FVC, and ACT score (r = 0.409, p = 0.018; r = -0.399, p = 0.021; and r = -0.505, p = 0.003, respectively) in nonatopic asthma patients, but not in atopic patients.

CONCLUSION

High serum DcR3 levels are associated with disease severity in nonatopic asthma patients, which suggests that DcR3 is a potential biomarker that can be used to predict the severity of nonatopic asthma.

Blood eosinophilia is associated with unfavorable hospitalization outcomes in children with bronchiolitis

BACKGROUND

Bronchiolitis, the most common indication for hospitalization of young children, is associated with subsequent asthma. Blood eosinophilia is associated with increased severity of asthma, but it is unclear if eosinophilia is associated with severity of illness in bronchiolitis. We hypothesized that blood eosinophilia is associated with unfavorable short-term outcomes of bronchiolitis hospitalizations.

METHODS

Data from initial bronchiolitis admissions to our institution between 2010 and 2013 were extracted using Population Explorer software (Explorys, Cleveland, OH). Children were categorized as "CBC-none" (no complete blood count [CBC] data during the first 7 days of hospitalization), EOS-positive (at least one CBC with ≥300 eosinophils per microliter or ≥3% of all leukocytes identified as eosinophils) or EOS-negative (at least one CBC and no eosinophilia). The association between hospitalization duration and maximum absolute eosinophil count (AEC) was analyzed using Spearman correlation. Variables independently associated with prolonged (≥72 hr) hospitalization were identified using stepwise multivariate logistic regression.

RESULTS

In 1356 inpatients <24 months with bronchiolitis, median hospitalization duration was 2.46 days and 38.0% had prolonged hospitalization. CBC data were available in 32.4% of subjects: 20.7% were EOS-positive and 79.3% were EOS-negative. Increased maximum AEC was significantly associated with longer duration of hospitalization. Prolonged hospitalization was independently associated with EOS-positive versus EOS-negative children (OR 1.88, 95%CI: 1.12-3.17, P = 0.020). Mechanical ventilation was most common in EOS-positive subjects (24.2% of cases), versus EOS-negative (7.2%) and CBC-none (0.7%) (P < 0.001).

CONCLUSIONS

Blood eosinophilia is associated with unfavorable clinical outcomes in a large cohort of inpatients with bronchiolitis.

Symptoms, complaints, ocular and nasal physiological signs in university staff in relation to indoor environment - temperature and gender interactions

Symptoms, signs, perceptions, and objective measures were studied in university buildings. Two problem buildings with a history of dampness and complaints were compared with two control buildings. Health investigations among university staff were performed at the workplace (n = 173) including tear film stability [non-invasive break-up time (NIBUT) and self-reported break-up time (SBUT)], nasal patency (acoustic rhinometry), nasal lavage fluid analysis [NAL: eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme and albumin] and atopy by total serum IgE and IgE antibodies (Phadiatop). Exposure assessment included inspections, thermal and atmospheric climate at 56 points modelled for all work sites. Multiple regressions were applied, controlling for age and gender. Exposure differences between problem buildings and controls were small, and variations between rooms were greater. Workers in the problem buildings had more general and dermal symptoms, but not more objective signs than the others. Adjusted day NIBUT and SBUT increased at higher night air temperatures, with B (95% CI) 0.6 (0.04-1.2) and 1.3 (-0.02 to 2.5), respectively. Higher relative humidity at mean day air temperature <22.1 degrees C was associated with adjusted NIBUT and SBUT, with B (95% CI) 0.16 (0.03-0.29) and 0.37 (-0.01 to 0.75), respectively. Air velocity below recommended winter values and reduced relative humidity in the range of 15-30% were associated with dry air and too low temperature.

PRACTICAL IMPLICATIONS

Thermal climate in university buildings may be associated with both perceptions and physiological signs. Reduced night time air temperature, increased difference in air temperature between day and night, and fast changes in air temperature might impair indoor environment. This may have implication for energy-saving policies. It might be difficult to identify the exposure behind, and find the reason why, some buildings are defined as 'problem buildings'.

IL-5-induced hypereosinophilia suppresses the antigen-induced immune response via a TGF-beta-dependent mechanism

Although eosinophils play an essential role in allergic inflammation, their role has recently been under controversy. Epidemic studies suggest that hypereosinophilia induced by parasite infection could suppress subsequent Ag sensitization, although the mechanism has not been fully clarified. In this study, we investigated whether eosinophils could suppress the Ag-specific immune response in the airway. BALB/c mice were sensitized and airway challenged with OVA. Systemic hypereosinophilia was induced by delivery of an IL-5-producing plasmid. IL-5 gene delivery suppressed the Ag-specific proliferation and cytokine production of CD4+ T cells in the spleen. IL-5 gene delivery before OVA sensitization significantly suppressed airway eosinophilia and hyperresponsiveness provoked by subsequent OVA airway challenge, while delivery during the OVA challenge did not suppress them. This IL-5-induced immune suppression was abolished in eosinophil-ablated mice, suggesting an essential role of eosinophils. IL-5 treatment increased the production of TGF-beta1 in the spleen, and we demonstrated that the main cellular source of TGF-beta1 production was eosinophils, using eosinophil-ablated mice and depletion study. TGF-beta1, but not IL-5 itself, suppressed the Ag-specific immune response of CD4+ T cells in vitro. Furthermore, IL-5 treatment enhanced phosphorylation of Smad2 in CD4+ T cells. Finally, a TGF-beta type I receptor kinase inhibitor restored this IL-5-induced immune suppression both in vitro and in vivo. These results suggest that IL-5-induced hypereosinophilia could suppress sensitization to Ag via a TGF-beta-dependent mechanism, thus suppressed allergic airway inflammation. Therefore, hypereosinophilia could reveal an immunosuppressive effect in the early stage of Ag-induced immune response.

Relationship of Allergic Degree and PC20 Level in Adults with Positive Methacholine Challenge Test

BACKGROUND

The relationship between allergic markers and PC(20) (provocative concentration causing a 20% fall in FEV(1)) in adults with positive methacholine challenge test (MCT) is still subject to discussion.

OBJECTIVE

The goal of this study is to determine whether the degree of bronchial hyperresponsiveness (BHR) is correlated with the severity of atopy or not.

METHODS

Forty patients with persistent cough and/or unexplained episodes of dyspnea exhibiting a normal baseline pulmonary function test and positive MCT were enrolled in this study. They were divided into two groups according to their Phadiatop response (positive and negative), and three groups by PC(20) level: PC(20) < 1.25 mg/ml, 1.25 mg/ml < or = PC(20) < 5 mg/ml, and 5 mg/ml < or = PC(20) < 25 mg/ml.

RESULTS

Twenty-three patients (57.5%) were Phadiatop positive. Of the 23 Phadiatop-positive patients, 20 patients (87%) were positive for specific serum IgE to Dermatophagoides pteronyssinus (D1) and Dermatophagoides farinae (D2). The total serum IgE and eosinophil cationic protein (ECP) level of the Phadiatop-positive group were higher than those of the Phadiatop-negative group (p < 0.0001 and p = 0.005, respectively). The age, gender, FEV(1)/FVC ratio, ECP and total serum IgE level were not significantly different in the three PC(20) subgroups. The Phadiatop response and PC(20) level were significantly correlated (p = 0.0063). For Phadiatop-positive adults, PC(20) level was not significantly correlated with total serum IgE and specific serum IgE to D1 and D2.

CONCLUSION

Atopy is related to adults with positive MCT. However, the degree of BHR to methacholine is not significantly correlated with the severity of atopy.

Blood eosinophilia: a new paradigm in disease classification, diagnosis, and treatment

Acquired blood eosinophilia is considered either a primary or a secondary phenomenon. Causes of secondary (ie, reactive) eosinophilia include tissue-invasive parasitosis, allergic or inflammatory conditions, and malignancies in which eosinophils are not considered part of the neoplastic process. Primary eosinophilia is classified operationally into 2 categories: clonal and idiopathic. Clonal eosinophilia stipulates the presence of either cytogenetic evidence or bone marrow histological evidence of an otherwise classified hematologic malignancy such as acute leukemia or a chronic myeloid disorder. Idiopathic eosinophilia is a diagnosis of exclusion (ie, not secondary or clonal). Hypereosinophilic syndrome is a subcategory of idiopathic eosinophilia; diagnosis requires documentation of both sustained eosinophilia (absolute eosinophil count > or = 1500 cells/microL for at least 6 months) and target organ damage (eg, involvement of the heart, lung, skin, or nerve tissue). Genetic mutations involving the platelet-derived growth factor receptor genes (PDGFR-alpha and PDGFR-beta) have been pathogenetically linked to clonal eosinophilia, and their presence predicts treatment response to imatinib. Accordingly, cytogenetic and/or molecular investigations for the presence of an imatinib-sensitive molecular target should accompany current evaluation for primary eosinophilia. In the absence of such a drug target, specific treatment is dictated by the underlying hematologic malignancy in cases of clonal eosinophilia; however, the initial treatment of choice for symptomatic patients with hypereosinophilic syndrome is prednisone and/or interferon alfa.

Blood eosinophilia: a new paradigm in disease classification, diagnosis, and treatment

Acquired blood eosinophilia is considered either a primary or a secondary phenomenon. Causes of secondary (ie, reactive) eosinophilia include tissue-invasive parasitosis, allergic or inflammatory conditions, and malignancies in which eosinophils are not considered part of the neoplastic process. Primary eosinophilia is classified operationally into 2 categories: clonal and idiopathic. Clonal eosinophilia stipulates the presence of either cytogenetic evidence or bone marrow histological evidence of an otherwise classified hematologic malignancy such as acute leukemia or a chronic myeloid disorder. Idiopathic eosinophilia is a diagnosis of exclusion (ie, not secondary or clonal). Hypereosinophilic syndrome is a subcategory of idiopathic eosinophilia; diagnosis requires documentation of both sustained eosinophilia (absolute eosinophil count > or = 1500 cells/microL for at least 6 months) and target organ damage (eg, involvement of the heart, lung, skin, or nerve tissue). Genetic mutations involving the platelet-derived growth factor receptor genes (PDGFR-alpha and PDGFR-beta) have been pathogenetically linked to clonal eosinophilia, and their presence predicts treatment response to imatinib. Accordingly, cytogenetic and/or molecular investigations for the presence of an imatinib-sensitive molecular target should accompany current evaluation for primary eosinophilia. In the absence of such a drug target, specific treatment is dictated by the underlying hematologic malignancy in cases of clonal eosinophilia; however, the initial treatment of choice for symptomatic patients with hypereosinophilic syndrome is prednisone and/or interferon alfa.

Absence of association of peripheral blood eosinophilia or increased eosinophil cationic protein with bronchial hyperresponsiveness during asthma remission

BACKGROUND

The mechanisms responsible for persistent bronchial hyperresponsiveness (BHR) in adolescents with long-term asthma remission are poorly understood.

OBJECTIVE

To determine whether BHR in adolescents with asthma remission is associated with peripheral blood eosinophilia, increased serum levels of eosinophil cationic protein (ECP), or both findings.

METHODS

We classified 51 adolescents with long-term asthma remission (neither asthma-related symptoms nor medication during the previous 2 years) into 28 BHR-positive patients (methacholine PC20 [provocative concentration causing a 20% decrease in forced expiratory volume in 1 second] <18 mg/mL) and 23 BHR-negative patients. The peripheral blood eosinophil counts and serum ECP concentrations were compared between these 2 groups. Twenty-eight patients with symptomatic asthma (symptomatic group), matched for methacholine PC20 level with study subjects in the BHR-positive remission group, and 28 healthy adolescents (control group) were also studied.

RESULTS

No significant differences in the peripheral blood eosinophil counts (262.1 +/- 117.0/microL vs 253.9 +/- 165.0/microL) and the serum ECP levels (15.6 +/- 10.0 microg/L vs 15.8 +/- 11.9 microg/L) were found between the BHR-positive and BHR-negative remission groups, respectively. The BHR-positive remission group differed from the symptomatic group (372.9 +/- 190.3/microL, P < 0.05; 26.6 +/- 11.3 microg/L, P < 0.01) in both blood indices but resembled the control group (214.6 +/- 118.6/microL and 12.1 +/- 4.8 microg/L; both, no significant difference).

CONCLUSIONS

BHR in adolescents with long-term asthma remission is not associated with peripheral blood eosinophilia or an increase in serum ECP concentration. This finding suggests that the mechanism underlying BHR in this clinical setting may differ from that in symptomatic asthma.

Oxidative and nitrosative events in asthma

Asthma affects over 15 million individuals in the United States, with over 1.5 million emergency room visits, 500,000 hospitalizations, and 5500 deaths each year, many of which are children. Airway inflammation is the proximate cause of the recurrent episodes of airflow limitation in asthma. Research applying molecular biology, chemistry, and cell biology to human asthma and model systems of asthma over the last decade has revealed that numerous biologically active proinflammatory mediators lead to increased production of reactive oxygen species (ROS) and the gaseous molecule nitric oxide (NO). Persistently increased ROS and NO in asthma lead to reactive nitrogen species (RNS) formation and subsequent oxidation and nitration of proteins, which may cause alterations in protein function that are biologically relevant to airway injury/inflammation. Eosinophil peroxidase and myeloperoxidase, leukocyte-derived enzymes, amplify oxidative events and are another enzymatic source of NO-derived oxidants and nitrotyrosine formation in asthma. Concomitant with increased generation of oxidative and nitrosative molecules in asthma, loss of protective antioxidant defense, specifically superoxide dismutase (SOD), contributes to the overall toxic environment of the asthmatic airway. This review discusses the rapidly accruing data linking oxidative and nitrosative events as critical participants in the acute and chronic inflammation of asthmatic airways.

Regulation of the interleukin-5 receptor alpha-subunit on peripheral blood eosinophils from healthy subjects

The aim was to study in vitro regulation of the IL-5 receptor alpha (IL-5R alpha) on purified peripheral blood eosinophils from healthy subjects. The IL-5R alpha was down-regulated, in a dose-dependent manner, by recombinant IL-5 and GM-CSF, with IL-5 being most potent. This down-regulation was not induced by autocrine release of GM-CSF or IL-5, respectively. Incubation of eosinophils with cell-free peritoneal dialysis fluid (PF) collected from a patient with peritoneal fluid eosinophilia (PFE), induced up-regulation of the proportion of CD69 positive eosinophils, in parallel with down-regulation of the proportion of IL-5R alpha positive eosinophils. Experiments with neutralizing antibodies against IL-5 and GM-CSF, revealed that IL-5 was the principal cytokine responsible for the down-regulation of the IL-5R alpha. When eosinophils were incubated with PF collected from the same patient in remission or with PF collected from a newly started patient or a patient with bacterial peritonitis, less down-regulation of the IL-5R alpha was observed. In conclusion our data indicate that IL-5, as opposed to its proposed action on eosinophil progenitors, down-regulates the IL-5R alpha chain on mature eosinophils. We therefore suggest that an IL-5 driven inflammation generates an eosinophil tissue phenotype that is characterized by a low IL-5R alpha expression. These aspects of IL-5 action on IL-5R alpha expression could gain new insights into the mechanisms of specific immuno-modulatory therapies, such as anti-IL-5.

Asthma attack severity and urinary concentration of eosinophil X protein in children

OBJECTIVE

Determination of the urinary concentration of eosinophil protein X (U-EPX) may objectively predict the severity and activity of asthma in children.

METHODS

Concentrations of U-EPX in 80 non- atopic asthmatic children were compared with those in 25 healthy control children. The patients were studied during attacks and two weeks later. The severity of asthma attacks was determined according to a pre-existing score. U-EPX was measured by the specific radioimmunoassay technique (Pharmacia, Uppsala, Sweden). This measurement was correlated with the clinical and radiological investigations as well as with other variables such as blood oxygen saturation, peak expiratory rate and eosinophil count.

RESULTS

U-EPX concentrations were significantly higher in all asthmatic children during attacks (139.6 11.7 microg/mmol of creatinine) than those in the control group (35.3 6.2 microg/mmol of creatinine) (p < 0.001). Two weeks after resolution of the exacerbation, U-EPX significantly decreased (66.5 9.3 microg/mmol of creatinine) (p < 0.001). U-EPX concentrations were highest in patients with severe attacks (191.5 11.3 microg/mmol of creatinine) (p < 0.001). No statistically significant differences were found between mild (88.2 7.2 microg/mmol of creatinine) and moderate attacks (119.6 8.5 microg/mmol of creatinine). At the two-week follow-up, U-EPX concentrations in patients with mild or moderate attacks was similar to those in controls but were persistently elevated in the subgroup with severe attacks (103.8 9.4 microg/mmol of creatinine) (p < 0.001). No significant correlation was found between U-EPX concentrations and blood oxygen saturation, peak expiratory rate or eosinophil count.

CONCLUSION

A statistically significant correlation was found between U-EPX concentrations and the severity of attacks in asthmatic children. This substance could be useful in quantifying bronchial inflammation. This result could further be used as a marker of severity of disease exacerbation and would not only facilitate early diagnosis and staging of inflammatory and allergic disorders but would also allow therapy and interventions to be monitored.

Down-regulated IL-5 receptor expression on peripheral blood eosinophils from budesonide-treated children with asthma

BACKGROUND

The expression and function of cytokine receptors on peripheral blood eosinophils (PBE) from healthy and asthmatic children are poorly characterized.

METHODS

The PBE count and expression of IL-5 receptor (R) and GM-CSFR positive PBE was analyzed in nonsteroid-treated asthmatic children (n = 13), budesonide-treated asthmatic children (n = 24) and healthy children (n = 16) by flow cytometry. Alterations in intracellular EG2-epitope expression were used to measure the in vitro responsiveness of PBE to recombinant IL-5 and GM-CSF.

RESULTS

The PBE count was increased (P < 0.05) in both asthmatic groups, independent of treatment, as compared to healthy children. The IL-5R expression on PBE, as well as the in vitro responsiveness of PBE to recombinant IL-5, was reduced (P < 0.05), in budesonide-treated asthmatic children compared to nonsteroid-treated asthmatic children and healthy children. The proportion of GM-CSFR positive PBE and in vitro responsiveness of PBE to recombinant GM-CSF were not different between the groups. In vitro treatment with budesonide did not down-regulate the proportion of IL-5R positive PBE.

CONCLUSIONS

Budesonide-treatment of asthmatic children induces a selectively reduced IL-5R expression on PBE, concomitant with a reduced in vitro responsiveness of PBE to IL-5. We suggest that this budesonide-related down-regulation of the IL-5R might be a mechanism by which steroid treatment inhibits the action of IL-5 on eosinophil accumulation and activation in vivo.

Which factors predict success after discontinuation of inhaled budesonide therapy in children with asthma?

Urinary eosinophil protein X (UEPX) concentration, lung function, and nonspecific bronchial hyperreactivity were determined in 40 asthmatic children (asymptomatic for 6.4 +/- 3.0 months) (mean age 9.8 +/- 2.9 years) receiving inhaled budesonide, in order to establish whether measurement of these parameters is useful in determining discontinuation of inhaled corticosteroid therapy. After the discontinuation of therapy, patients were asked to come to the Outpatient Clinic if symptoms recurred and did not respond to beta2 mimetic usage in 24 hr. Otherwise they were to be seen 2-3 months later for a follow-up visit. UEPX concentration was determined and spirometry was performed on this visit. While UEPX concentrations had increased (p < 0.0001), FEV1, FEF 25-75 and PEF had decreased significantly 2.3 +/- 0.53 months after the cessation of inhaled budesonide therapy in all children (p = 0.004, p = 0.02, p = 0.02, respectively). Due to clinical deterioration, inhaled corticosteroid therapy had to be restarted in 19 (48%) of the children (Group I), while the remaining 21 (52%) (Group II) continued to be asymptomatic during the 2.3 +/- 0.5 months follow-up period. Although the initial UEPX concentrations, spirometer variables, and methacholine PC20 values of these two groups were not statistically different, the duration of clinical remission before discontinuation of budesonide prophylaxis was significantly longer in group II (p = 0.0037). We concluded that, in determining discontinuation of inhaled corticosteroid prophylaxis, duration of clinical remission seems to be a more useful criterion than measurement of UEPX levels, lung function test, and assessment of bronchial hyperreactivity.

Serum eosinophil cationic protein levels measured during exacerbation of asthma: characteristics of patients with low titres

BACKGROUND

Serum eosinophil cationic protein (ECP) levels reflect ongoing eosinophilic airway inflammation and are used as a marker for asthma activity. ECP levels, however, may not be elevated in some asthmatic patients, even when they are symptomatic.

OBJECTIVE

To clarify the characteristics of patients with 'low' ECP titres despite asthma exacerbation.

METHODS

Serum ECP levels were measured in 113 asthmatic patients during exacerbation. Patients were divided into two groups according to ECP titre: a high ECP group (H; ECP > or = 16.0 microg/L) and a low ECP group (L; ECP <16.0 microg/L). Twenty-two patients who had recently received systemic steroids were excluded and the clinical features of the remaining patients in H (n = 54) and L (n = 37 were compared.

RESULTS

Gender, atopic or smoking status, disease severity, inhaled steroid or theophylline usage, peak expiratory flow (% personal best) and forced expiratory volume in 1 s (FEV1) (% predicted) did not significantly differ between the two groups. Patients in L were significantly older and had longer disease duration and lower serum IgE levels than those in H. Multivariate analysis combining age, disease duration and IgE levels showed that age and disease duration were independently associated with ECP level. Airway wall thickness, assessed in a subset of patients using computed tomography, was significantly larger in L.

CONCLUSION

Serum ECP levels in asthmatic patients may not be elevated during exacerbation and thus may not be a useful marker in patients who are older, have longer disease duration or possibly have thicker airway walls. Mechanisms other than eosinophilic inflammation, such as airway remodelling, may be involved in asthma exacerbation in these patients.

Eosinophil cationic protein (ECP) in saliva: a new marker of disease activity in bronchial asthma

Eosinophil cells play a crucial role in the pathogenesis of asthma, and concentration of eosinophil cationic protein (ECP) in serum has been used to monitor activity of the disease. Our aim was to determine the feasibility and usefulness of measuring ECP in saliva and to use it as a marker of the disease. Thirty-eight patients with asthma and 16 healthy volunteers were included in this study. Repeatability of measurements of ECP in saliva was acceptable [intra-class correlation coefficients (Ri) = 0.74 and coefficients of repeatability (CR) = 0.37 in five healthy subjects]. Levels of ECP in saliva were higher in asthmatics than in volunteers (P < 0.01). There was a significant inverse association between a surrogate variable reflecting disease activity (i.e. change over a few weeks in dose of inhaled corticosteroid required by a change in clinical status of asthma) and a change over the same time period in salivary ECP in 19 patients with stable asthma (r = -0.64, P = 0.02). Our findings indicate that levels of salivary ECP are elevated in patients with asthma and associated with presumed activity of disease as recorded by alteration of taken dose of inhaled corticosteroid.

Eosinophils are a major source of nitric oxide-derived oxidants in severe asthma: characterization of pathways available to eosinophils for generating reactive nitrogen species

Eosinophil recruitment and enhanced production of NO are characteristic features of asthma. However, neither the ability of eosinophils to generate NO-derived oxidants nor their role in nitration of targets during asthma is established. Using gas chromatography-mass spectrometry we demonstrate a 10-fold increase in 3-nitrotyrosine (NO(2)Y) content, a global marker of protein modification by reactive nitrogen species, in proteins recovered from bronchoalveolar lavage of severe asthmatic patients (480 +/- 198 micromol/mol tyrosine; n = 11) compared with nonasthmatic subjects (52.5 +/- 40.7 micromol/mol tyrosine; n = 12). Parallel gas chromatography-mass spectrometry analyses of bronchoalveolar lavage proteins for 3-bromotyrosine (BrY) and 3-chlorotyrosine (ClY), selective markers of eosinophil peroxidase (EPO)- and myeloperoxidase-catalyzed oxidation, respectively, demonstrated a dramatic preferential formation of BrY in asthmatic (1093 +/- 457 micromol BrY/mol tyrosine; 161 +/- 88 micromol ClY/mol tyrosine; n = 11 each) compared with nonasthmatic subjects (13 +/- 14.5 micromol BrY/mol tyrosine; 65 +/- 69 micromol ClY/mol tyrosine; n = 12 each). Bronchial tissue from individuals who died of asthma demonstrated the most intense anti-NO(2)Y immunostaining in epitopes that colocalized with eosinophils. Although eosinophils from normal subjects failed to generate detectable levels of NO, NO(2-), NO(3-), or NO(2)Y, tyrosine nitration was promoted by eosinophils activated either in the presence of physiological levels of NO(2-) or an exogenous NO source. At low, but not high (e.g., >2 microM/min), rates of NO flux, EPO inhibitors and catalase markedly attenuated aromatic nitration. These results identify eosinophils as a major source of oxidants during asthma. They also demonstrate that eosinophils use distinct mechanisms for generating NO-derived oxidants and identify EPO as an enzymatic source of nitrating intermediates in eosinophils.

Effect of natural allergen exposure on non-specific bronchial reactivity in asthmatic farmers

The aim of the study was to assess the seasonal variability of non-specific bronchial reactivity (NSBR) evaluated with methacholine in asthmatic farmers allergic to pollens. Twenty farmers (16 male and four female) with allergy to pollens, e.g. 'Graminae' and 'Parietaria', entered the study. None of the patients had been previously treated with specific immunotherapy. Patients underwent a methacholine challenge at the first visit and then in the subsequent seasons. Four groups of tests were obtained according to the period when the challenge was performed. Group 1: challenges performed in December, January and February; group 2 in March, April and May; group 3 in June, July and August; group 4 in September, October and November. PD20 values were expressed as the natural logarithm of the cumulative dose of methacholine causing at least a 20% fall in FEV1. Bronchial hyperreactivity was highest in summer, followed by spring and autumn; in winter it was much lower. Multiple group analysis (ANOVA) showed statistically significant differences between the groups (P < 0.01). When the groups were compared individually, statistically significant differences existed only between group 1 (winter) and each of the other groups, respectively 2 (spring) (P = 0.02), 3 (summer) (P = 0.004) and 4 (autumn) (P = 0.02). The results underlined the importance of allergic inflammation in determining changes in NSBR. In the region where the study was carried out (central Italy), the grass and Paretaria pollination lasts from March to November. Therefore, farmers had a progressive increase in NSBR from spring to summer and a decrease in fall as a consequence of the varying pollen concentration in different seasons. The level of allergen exposure is, in fact, the main factor that determines the severity of bronchial inflammation, thus affecting NSBR.

Role of eosinophil peroxidase in the origins of protein oxidation in asthma

Eosinophils are uniquely endowed with an arsenal of enzymes that enable them to generate an array of reactive oxidants and diffusible radical species. The formidable arsenal at their disposal likely evolved because of the central role these phagocytes play in combating invading helminths and other large metazoan pathogens. Although these leukocytes constitute an essential component of the effector limb of host defenses, they also are implicated in contributing to inflammatory tissue injury. The growing prevalence and severity of asthma, a respiratory disease characterized by recruitment and activation of eosinophils in the airways of affected individuals, has focused research efforts on elaborating the many potential mechanisms through which eosinophils may contribute to tissue injury and oxidative modification of biological targets in asthma. Eosinophil activation is strongly suspected as playing a contributory role in the pathogenesis of asthma. Accordingly, an understanding of the basic chemical pathways available to the leukocytes for generating specific reactive oxidants and diffusible radical species in vivo is required. In the following review, recent progress in the elaboration of specific mechanisms through which eosinophils generate oxidants and other reactive species are discussed. The potential contributions of these intermediates to modification of biological targets during asthma are described. Particular emphasis is placed upon the secreted hemoprotein eosinophil peroxidase (EPO), a central participant in generation of reactive oxidants and diffusible radical species by the phagocytes.

The relation between peripheral blood leukocyte counts and respiratory symptoms, atopy, lung function, and airway responsiveness in adults

STUDY OBJECTIVES

Eosinophils and neutrophils play major roles, respectively, in the pathogenesis of asthma and COPD, and it is well recognized that levels of these cells in peripheral blood are increased in relation to their pulmonary involvement. However, the relation between peripheral blood cell counts of the other major leukocyte groups and these lung diseases or markers of allergy or airflow obstruction is less clear. We have therefore investigated the association between peripheral blood levels of eosinophils, neutrophils, basophils, monocytes, and lymphocytes and the occurrence of chronic respiratory symptoms, atopy, lung function, and bronchial hyperresponsiveness, and the modifying effect of age, in adults.

DESIGN

A cross-sectional general population study.

SETTING

Data on > 2,000 British adults, who originally participated in a study of diet and lung health, were analyzed using multiple linear and logistic regression to adjust for potential confounders, including age, sex, and smoking history.

RESULTS

We found that, like eosinophils, the peripheral basophil count was increased in relation to asthma and associated symptoms, and to airway hyperreactivity and increased total IgE, but differed from eosinophils in that basophils were unrelated to atopy. Monocytes were predominantly associated with symptoms indicative of obstructive airway disease, in similar relation to neutrophils, but both of these leukocyte counts were also increased in asthma patients in older age groups. Lymphocyte counts were unrelated to any objective or subjective marker of disease.

CONCLUSIONS

If peripheral blood cell counts reflect pulmonary involvement of these leukocyte groups, basophils and monocytes may play a distinct role in the pathogenesis of allergic and nonallergic respiratory disease.

Systemic activation of basophils and eosinophils: markers and consequences

Basophils and eosinophils are important effector cells in human allergic diseases; they play a significant role in promoting allergic inflammation through the release of proinflammatory mediators (such as histamine, leukotriene C(4), major basic protein, eosinophil cationic protein, IL-4, and IL-13, among others). Notably, in allergic subjects, these cells exist in higher numbers and in a more activated state compared with nonatopic control subjects. Evidence for the greater activation state includes increased expression of intracellular and surface markers and hyperreleasability of allergy mediators. We have been interested in the phenotypic markers of effector-cell activation for many years. There is considerable overlap among activation markers, and few activation markers have been found that define a unique phenotype that is quantifiable in the assessment of the presence and severity of allergic disease. This review summarizes the existing evidence for systemic activation of human basophils and eosinophils in allergic diseases. The potential mechanisms responsible for functional and morphologic alterations in these effector cells and the specificity and utility of surface markers in the assessment of allergic disease activity or severity are also discussed.

Influence of total IgE and seasonal increase of eosinophil cationic protein on bronchial hyperreactivity in asthmatic grass-sensitized farmers

BACKGROUND

This study correlates biomarkers of atopy (serum total and specific IgE) and inflammation (serum eosinophil cationic protein) with bronchial hyperreactivity assessed after the complete end of pollination, in a group of farmers suffering from grass-allergic asthma.

METHODS

A total of 28 asthmatic farmers, with allergy to grass pollen, reporting persistent asthma symptoms after grass pollination, were enrolled. An accurate allergologic screening excluded other sensitizations. Analysis of total and grass-specific IgE and eosinophil cationic protein was carried out before (March) and during (May) the following spring. After the complete end of pollination, bronchial hyperreactivity was assessed.

RESULTS

Symptoms (cough, wheezing) persisted during the autumn for a mean period of 41 days (range 13-69). Total IgE was moderately high and grass-specific IgE ranged from 9.25 to 41.12 kU/l without significant differences before and during spring. On the contrary, serum ECP levels significantly increased during the pollination period. PD20 methacholine evaluated after the end of grass pollination was negatively significantly correlated with levels of total IgE (r=-0.73; P<0.01) and the increase (from March to May) of serum ECP (r=-0.75; P<0.01). However, PD20 methacholine did not correlate with grass-specific IgE and serum ECP absolute values of both March and May. A positive correlation was found between number of postseasonal days with symptoms and both spring increase of serum ECP (r=0.75; P=0.04) and levels of total IgE (r=0.76; P<0.01). The number of postseasonal days with symptoms inversely correlated with postseason PD20 methacholine (r=-0.76; P<0.01).

CONCLUSIONS

The study demonstrates that in grass-sensitized farmers with asthmatic symptoms persisting for several weeks after grass pollination has ceased, the degree of airways hyperreactivity and the duration of postseasonal symptoms are directly related to the spring increase of ECP levels, as well as to the level of total IgE in serum. This allows us to identify two candidate biomarkers for the risk of developing prolonged asthma symptoms, and for the effective monitoring of anti-inflammatory treatment and allergen-specific immunotherapy.

Quantitative, rather than qualitative, differences in CD69 upregulation in human blood eosinophils upon activation with selected stimuli

BACKGROUND

The study aimed to investigate whether CD69 expression on granulocytes is subject to specific regulation by inflammatory mediators, and, if so, to identify these factors in relation to eosinophil activity markers such as the EG2 epitope and ECP release.

METHODS

Peripheral blood leukocytes from healthy donors were used. The surface and intracellular distribution of CD69 was investigated with a whole-blood cell-membrane permeabilization technique, the FOG method, and flow cytometry. In vitro stimulation was performed with GM-CSF, IL-5, IL-5 plus eotaxin, LPS, and fMLP.

RESULTS

A preformed intracellular pool of CD69 was demonstrated in both eosinophils and neutrophils, but not in monocytes. Almost no resting eosinophils, neutrophils, or monocytes expressed CD69 on the cell surface. However, in vitro stimulation with selected stimuli increased the proportion of CD69-positive eosinophils to various extents, with GM-CSF being the most and fMLP the least efficient stimulus. The neutrophils did not respond under these conditions. Increased expression of the EG2 epitope and initiation of degranulation preceded CD69 upregulation.

CONCLUSIONS

Eosinophils and neutrophils from healthy donors have a preformed intracellular pool of CD69, which is mobilized on the cell surface on eosinophils, but not on neutrophils, to various extents by selected stimuli. Monocytes, however, do not have a preformed intracellular pool of CD69. Our data indicate that a kinetic order exists among the EG2 expression, the degranulation process, and CD69 upregulation. Due to a quantitative, rather then a qualitative, upregulation of CD69 by stimuli associated with both allergic and bacterial inflammation, CD69 may be a potential activity marker of clinical value.

Eotaxin in serum of patients with asthma or chronic obstructive pulmonary disease: relationship with eosinophil cationic protein and lung function

This study was undertaken to investigate the correlation between the serum ECP and the serum eotaxin level, and disease activity as evaluated with pulmonary function in patients with asthma or chronic obstructive pulmonary disease (COPD). 20 patients with stable asthma and 15 patients with COPD, and 15 subjects of the control group took part in this study. The analysis of ECP was performed according to the manufacturer's directions (Pharmacia Diagnostics AB, Uppsala, Sweden). The ELISA test was used to measure eotaxin levels in sserum (kits from R&D, USA). The levels of ECP were 16.9+/-6.3 microg/L in patients with asthma, 15.1+/-9.3 microg/L in patients with COPD and 11.8+/-6.2 microg/L in the control group (P<0.05). There was no significant difference in the asthma ECP level compared with the ECP level in COPD. There was a significant difference between the ECP plasma level in asthma compared with the ECP plasma level in the control group (p<0.05). The levels of eotaxin were 175.8+/-49.3 pg/mL in the control group. There was a correlation of ECP and the eotaxin level in asthma patients (r=+0.5, p<0.05). The percentage fall in FEV1 correlated with eotaxin level in asthma (r=-0.3, p<0.05) and with the eotaxin level in COPD (r=-0.5, p<0.05). Serum outcomes of eotaxin and ECP levels appear to be a useful indicator of atopic asthma, and might provide complementary data disease monitoring. Therefore, further investigations are required to clarify whether serum eotaxin measurements have a role in the clinical evaluation in COPD.

Conditions in blood sampling procedures that extend the ex vivo stability of eosinophil activity markers in peripheral blood from allergic patients and healthy controls

BACKGROUND

Serum-ECP, EG2-epitope on intracellular ECP and surface expression of CD9 and CD11b in peripheral blood eosinophils (PBE) are considered to be markers that mirror clinical parameters in allergic inflammation.

OBJECTIVE

The aim was to investigate the impact of the blood sampling procedure on PBE markers and to identify optimal conditions for extended pre-analysis storage.

METHODS

Blood, from healthy individuals and patients with allergic rhinitis/asthma, was collected in tubes with EDTA, citrate, or without anti-coagulant. The expression of EG2-epitope, CD9, and CD11b were analyzed in eosinophils and neutrophils after 1, 5, and 24 hours of storage at +4 degrees C, according to the FOG-method and flow cytometry. In vitro stimulation with fMLP/PMA was used for metabolic activity analysis and CD11b mobilization. Following a 1-hour clotting period at +20 to 22 degrees C, samples were stored at +4 degrees C and serum-ECP levels were measured.

RESULTS

The EG2-epitope, serum-ECP, and CD9 were stable in samples from both healthy controls and allergic patients at all storage conditions. The EG2-epitope, serum-ECP and PBE count were significantly increased in the patient group, whereas no differences were observed in the expression of CD9 or CD11b. Both granulocytes and monocytes retained their metabolic activity for 24 hours. Neutrophils in citrate-blood increased their ability to respond to fMLP, as compared with EDTA-blood.

CONCLUSION

In vitro analysis of selected activity markers and functional tests could be performed on granulocytes from both healthy individuals and allergic patients after 24 hours storage at +4 degrees C. The anticoagulant citrate seems to be preferable to EDTA when monocytes or CD11b expression are analyzed.

Intracellular expression and serum levels of eosinophil peroxidase (EPO) and eosinophil cationic protein in asthmatic children

BACKGROUND

Eosinophils are involved in the chronic inflammatory response in asthma and their basic proteins are thought to play a major pathophysiological role in this process. While serum levels of basic proteins have been used to monitor the ongoing allergic disease, little is known about the intracellular expression of these proteins in clinical situations.

OBJECTIVE

The aim of the study was to determine the intracellular expression of eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) in asthmatic children and control subjects and relate it to serum levels of both proteins, lung function tests and immunoglobulin (Ig)E levels.

METHODS

Serum ECP and EPO concentrations were determined by immunoassays in 13 asthmatic children (mean age: 9 +/- 1 years, mean FEV1: 92 +/- 10% predicted, geometric mean PC20 histamine 0.5 mg/mL) and 10 age-matched, healthy control subjects. A flow cytometric single cell assay was employed to detect intracellular ECP and EPO in peripheral blood eosinophils.

RESULTS

While serum concentrations of both ECP (asthma: median 15.0 microg/L [range 3.6-57.7] vs control: 5.9 microg/L [2.7-9.1]; P = 0.02) and EPO (22.9 microg/L [5.2-82.5] vs 7. 2 microg/L [2.5-12.7]; P = 0.008) were significantly elevated in asthmatics, the intracellular expression of ECP and EPO (measured as mean fluorescence intensity) was decreased (EG1: 55.3 [17.7-120.8] vs 100.3 [46.5-264.4]; P = 0.01; EG2: 80.2 [24.1-135.3] vs 133.7 [32. 1-244.9]; P = 0.04 and EPO: 49.7 [23.1-155.8] vs 94.9 [28.8-115.2]; P = 0.03). In asthmatics there was a significant correlation of FEV1 with intracellular ECP and of bronchial hyperresponsiveness with serum EPO and ECP. Furthermore, total IgE levels were positively correlated with serum EPO only.

CONCLUSION

We conclude that in asthmatics the intracellular content of ECP and EPO in peripheral eosinophils is reduced possibly due to degranulation. Epitope masking in activated eosinophils or a shift to early bone marrow-derived progenitors with less granule proteins are further possible explanations.

Serum eosinophil cationic protein (ECP): reference values in healthy nonatopic children

BACKGROUND

Although serum ECP concentrations have been reported in normal children, there are currently no published upper cutoff reference limits for serum ECP in normal, nonatopic, nonasthmatic children aged 1-15 years.

METHODS

We recruited 123 nonatopic, nonasthmatic normal children attending the Royal Belfast Hospital for Sick Children for elective surgery and measured serum ECP concentrations. The effects of age and exposure to environmental tobacco smoke (ETS) on the upper reference limits were studied by multiple regression and fractional polynomials.

RESULTS

The median serum ECP concentration was 6.5 microg/l and the 95th and 97.5 th percentiles were 18.8 and 19.9 microg/l. The median and 95th percentile did not vary with age. Exposure to ETS was not associated with altered serum ECP concentrations (P = 0.14).

CONCLUSIONS

The 95th and 97.5 th percentiles for serum ECP for normal, nonatopic, nonasthmatic children (aged 1-15 years) were 19 and 20 microg/l, respectively. Age and exposure to parental ETS did not significantly alter serum ECP concentrations or the normal upper reference limits. Our data provide cutoff upper reference limits for normal children for use of serum ECP in a clinical or research setting.

Linkage and association of atopic asthma to markers on chromosome 13 in the Japanese population

Chromosome 13 contains several candidate genes for asthma and atopy, and markers on this chromosome have been shown to be linked to phenotypes of atopy or asthma in two genome-wide searches. We conducted a linkage study for atopic asthma using markers spanning the whole of chromosome 13 in Japanese families ascertained through asthmatic children and examined associations of atopic asthma with markers where linkage was suggested. Data were analysed using MAPMAKER/SIBS for the multipoint lod score (MLS) analysis and SIB-PAIR for the transmission dis-equilibrium test (TDT). Three peaks which exceeded a lod score of 1.0 were observed (MLS 2.4 between D13S175 and D13S217, MLS 2.0 between D13S153 and D13S156, and MLS 1.4 between D13S285 and D13S293). The global TDT for atopic asthma was significant for the marker D13S153 ( P = 0.0065) and the 96 bp allele of D13S153 was preferentially transmitted to atopic asthma-affected children ( P = 0.0009, Bonferroni correction 5% = 0. 0037, 1% = 0.00072). These findings indicate that genes on chromosome 13 may play an important role in the development of atopy or asthma across various populations.

Effect of inhaled interleukin-5 on number and activity of eosinophils in circulation from asthmatics

The aim of the present study was to examine the effects of interleukin-5 (IL-5) inhalation on changes in the activity and number of circulating eosinophils, as well as concentrations of serum total IgE, in allergic asthmatics. A randomized double-blind, placebo-controlled study design was employed in which each subject acted as his or her own control. Eight nonsmoking patients with allergic asthma were administered recombinant human IL-5 by nebulization. Total white blood cell counts and differentials, as well as concentrations of ECP and total IgE in serum, were determined before and at 2, 24, and 48 h after inhalation. Our results demonstrated that eosinophil numbers increased from baseline (3.6 +/- 1.1 x 10(5)/ml) to 6.3 +/- 1.2 x 10(5)/ml (P < 0.01) at 24 h and to 5.7 +/- 0.9 x 10(5)/ml (P < 0.01) at 48 h after IL-5 inhalation in asthmatics. Accompanying this significantly increased blood eosinophilia were significantly elevated serum ECP levels. Compared with baseline (6.3 +/- 1.1 ng/ml), ECP levels increased with time following IL-5 inhalation, reaching 17.6 +/- 2.8 ng/ml (P < 0.01) at 24 h and remaining elevated at 48 h (18.1 +/- 2.9 ng/ml, P < 0.01). IL-5 inhalation had no significant effect on levels of serum total IgE, however. These findings provide direct evidence that nebulized IL-5 not only induces a significant blood eosinophilia but also results in the activation of circulating eosinophils. Our data further support the importance of IL-5 in the pathogenesis of bronchial asthma in humans.

Increased levels of IL-5 positive peripheral blood eosinophils and lymphocytes in mild asthmatics after allergen inhalation provocation

BACKGROUND

In allergic inflammation eosinophils and TH2-like lymphocytes are supposed to be the major effector cells and considered to contribute as cellular source of the key cytokine interleukin (IL)-5.

OBJECTIVE

The purpose of this study was to enable detection of IL-5 containing leucocytes and to investigate whether the number of these cells in the blood circulation differed between healthy and asthmatics before and after allergen provocation.

METHODS

The distribution of intracellular IL-5 in human peripheral blood eosinophils (PBE) and lymphocytes (PBL) has been investigated using fixation and cell membrane permeabilization with octyl-glucopyranoside, the FOG-method, and flow cytometry. The intracellular staining was performed on leucocytes without any prior purification and in vitro stimulation. The specificity of IL-5 binding to intracellular compartment of both PBE and PBL was confirmed by complete inhibition with human recombinant IL-5.

RESULTS

Preformed intracellular IL-5 was detected in the main population of PBE (> 70%) in both healthy individuals and asymptomatic patients. Moreover, preformed intracellular IL-5 was also detected in 4.8% and 2.4% of PBL from healthy individuals and asymptomatic patients, respectively. There was a correlation between the absolute number of PBE and IL-5 positive PBE. In patients with pollen-related asthma, the number of IL-5 positive PBE and PBL increased significantly 24 h after an allergen inhalation provocation (P < 0.05). In the healthy control group no differences regarding IL-5 positive PBE and PBL were obtained pre- and post-allergen challenge.

CONCLUSIONS

In patients with mild allergic asthma, but not in healthy individuals, allergen provocation induces an increased absolute number of IL-5 positive PBE and PBL. The reason for the relatively high number of IL-5 positive PBL is unclear, but a plausible explanation might be that other lymphocyte subsets besides CD4+ TH2 can produce IL-5. However, enumeration of IL-5 positive leucocytes may be used as an activity marker and also be a useful tool in monitoring the inflammation in asthma.

Eosinophils, eosinophil cationic protein and eosinophil-derived neurotoxin in serum and urine of patients with onchocerciasis coinfected with intestinal nematodes and in urinary schistosomiasis

Eosinophils, eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN/EPX), myeloperoxidase (MPO) and IgE were measured in blood, serum and/or urine in Schistosoma haematobium- and Onchocerca volvulus-infected Guineans and O. volvulus- and S. haematobium-negative Guineans coinfected or infected with intestinal nematodes. The number of eosinophils and levels of eosinophil granule proteins but not of MPO were found to be strongly elevated in all Africans as compared to European controls. The highest serum ECP and serum and urinary EDN/EPX levels were observed in the hyperreactive form of onchocerciasis (sowda). Onchocerciasis patients and O. volvulus-negative Africans coinfected or infected with intestinal nematodes (hookworm and/or Ascaris lumbricoides) revealed higher serum granule protein concentrations and/or absolute eosinophil counts and urinary ECP than those without nematode infections. Statistical differences between both sections were found for the absolute eosinophil counts and for serum EDN/EPX and IgE in generalized onchocerciasis, and for urinary ECP in sowda, indicating stimulation of the eosinophil potential of O. volvulus-positive patients by coexistent hookworm infection. This worm species, in contrast to A. lumbricoides, causes especially high eosinophil counts and EDN/EPX and IgE levels. From these results it is concluded that in nematode diseases, ECP and EDN/EPX levels reflect the degree of antigenic stimulation, eosinophil activation and eosinophil turnover rates. Serum ECP and serum and urinary EDN/EPX may, therefore, serve as parameters to monitor helminth infection. Urinary ECP may be a marker of eosinophiluria secondary to urogenital manifestation of S. haematobium. It is elevated in hyperreactive onchocerciasis activated by intestinal nematodes.

Norm values for eosinophil cationic protein in nasal secretions: influence of specimen collection

BACKGROUND

Eosinophil granulocytes play an important role in allergic inflammation of the nasal mucosa. Eosinophil cationic protein (ECP) is a specific eosinophil granule protein released upon activation of these cells. ECP concentration in nasal secretions has been demonstrated to be a good marker for the activity of eosinophilic nasal mucosal inflammation. The clinical use of such a marker requires defined values which are regarded as pathological or within normal range. In analyses of nasal secretion samples, the sampling method has an important influence on the data obtained.

OBJECTIVE

We investigated ECP levels in nasal secretions (NS) of healthy volunteers obtained by seven different methods of sample collection to define norm values and to evaluate the clinical use of the different methods.

METHODS

A total of 839 healthy individuals were evaluated using blowing the nose (Bl: n = 82), suction (Suc: n = 69), Okuda microsuction technique (MSuc: n = 93), absorbent cotton wool samplers (CWS: n = 156), rubber-foam samplers (RFS: n = 193), nasal lavage (Lav: n = 112) and nasal spray washing (NSW: n = 134).

RESULTS

Missing values occurred in more than 60% in Bl, Suc and MSuc, so that no norm range was defined for these methods. Norm range for ECP in NS was 5-46 ng/mL for CWS, 7-41 ng/mL for RFS, 4-51 ng/mL for NSW, and 3-31 ng/mL for Lav.

CONCLUSIONS

When comparing seven different methods used in this study to collect nasal secretions and determine ECP levels, the method based upon absorption or nasal washing was the best.

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.

The effect of short-term immunotherapy with molecular standardized grass and rye allergens on eosinophil cationic protein and tryptase in nasal secretions

BACKGROUND

Activation of mast cells and eosinophils under pollen exposure can be inhibited by specific immunotherapy.

OBJECTIVE

The effect of short-term immunotherapy with 7 preseasonal injections of molecular standardized allergens from grass and rye pollen on eosinophil cationic protein (ECP) and tryptase levels in nasal secretions has been compared with symptomatic drug treatment in an open, randomized study with 48 patients.

METHODS

Nasal reactivity and mediator levels in nasal secretions were measured at baseline, before season, in season, and after season.

RESULTS

Symptom scores in the immunotherapy group were 134.5 (95% CI, 65 to 336) versus 386. 0 (95% CI, 185 to 563), significantly lower as in the drug-treated group. ECP and tryptase levels increased significantly during natural allergen exposition. The seasonal levels in the immunotherapy group were significantly lower than in the drug-treated group with 272.1 ng/mL (252.0 to 293.9 ng/mL; immunotherapy) versus 470.4 ng/mL (SEM, 435.6 to 508.0 ng/mL; drugs) for ECP and with 8.73 ng/mL (SEM, 8.20 to 9.29 ng/mL) versus 17.47 ng/mL (16.42 to 18.60 ng/mL) for tryptase (all, P <.001). The ECP level induced by nasal provocation was 105.6 ng/mL (99.0 to 112.6 ng/mL) versus 180.4 ng/mL (169.2 to 192.4 ng/mL), significantly lower (P <.001) in the immunotherapy group, as was the tryptase level with 12.12 ng/mL (11.53 to 12.75 ng/mL) versus 8.19 ng/mL (7. 79 to 8.62 ng/mL; P <.001) at the after-season visit.

CONCLUSION

Short-term immunotherapy is able to reduce tryptase and ECP in nasal secretions more effectively than drug treatment in patients with allergic rhinitis.

Mild experimental exacerbation of asthma induced by individualised low-dose repeated allergen exposure. A double-blind evaluation

Low doses of environmental allergens have been proposed to increase bronchial hyperreactivity in sensitised individuals, without causing immediate asthmatic reactions. The primary aim of the present study was to evaluate whether repeated low doses of allergen, that do not cause overt bronchoconstriction, cause augmented non-specific bronchial reactivity. A secondary aim was to evaluate whether any changes in reactivity are associated with increased variability of lung function, and whether signs of inflammatory activity could be found. To do this, mild asthmatic patients without regular symptoms, but with both immediate and late reactions in response to a high dose of inhaled cat allergen extract, were included in a double blind, placebo controlled, cross-over study in which a low dose of allergen was administered on four consecutive days (Monday to Thursday). The dose of allergen was individualised for each patient, and was calculated to be 25% of the total dose given to produce an immediate and late response at screening. Repeated low dose allergen exposure produced a significant increase in methacholine reactivity compared to placebo, whereas FEV1 in the morning did not significantly change during the allergen week. Each low dose allergen exposure caused small changes in FEV1 (approximately 7% drop), which was significant vs. placebo only on day 2 (Tuesday). During the allergen week, six of eight patients reported asthma symptoms on at least one occasion, and variability in lung function, measured with a portable spirometer, was increased. Repeated low doses of allergen also produced a significant increase of P-ECP vs. placebo, without a significant rise in circulating eosinophils. However, no significant changes in circulating CD3, CD4, CD8, CD19, or CD25 cells were found, evaluated by FACS analysis. We conclude that low doses of allergen produce signs of a mild exacerbation of asthma, including increased bronchial reactivity to methacholine. This clinical model may be useful to evaluate both the pathophysiological mechanisms of asthma, and the effects of novel anti-asthma drugs.