Serum Levels of Eosinophil-Derived Neurotoxin: A Biomarker for Asthma Severity in Adult Asthmatics

PURPOSE: Eosinophilic inflammation is a key component of severe asthma (SA). However, there has been no reliable serum biomarker for the eosinophilic inflammation of SA. We hypothesized that serum eosinophil-derived neurotoxin (EDN) could predict the eosinophilic inflammation of SA in adult asthmatics. METHODS: Severe asthmatics (n = 235), nonsevere asthmatics (n = 898), and healthy controls (n = 125) were enrolled from Ajou University Hospital, South Korea. The serum levels of EDN and periostin were measured by enzyme-linked immunosorbent assay and compared between severe and nonsevere asthmatics. Their associations with total eosinophil count (TEC) and clinical parameters were evaluated; clinical validation of the K-EDN kit for the measurement of serum EDN was evaluated. RESULTS: Severe asthmatics were older and had longer disease duration with significantly lower levels of forced expiratory volume in 1 second and methacholine PC20 than nonsevere asthmatics. Significant differences were found in TEC or sputum eosinophil count (%) between the groups. The serum levels of EDN and periostin were significantly higher in severe asthmatics than in nonsevere asthmatics and in healthy controls (all P < 0.05). Although significant correlations were found between serum EDN levels measured by the 2 kits (ρ = 0.545, P < 0.0001), higher correlation coefficients between serum EDN levels measured by the K-EDN kit and TEC were higher (ρ = 0.358, P < 0.0001) than those between serum EDN levels measured by the MBL kit and TEC (ρ = 0.319, P < 0.0001) or serum periostin level (ρ = 0.222, P < 0.0001). Multivariate regression analysis demonstrated that serum EDN levels measured by the K-EDN kit predicted the phenotype of SA (P = 0.003), while 2 other biomarkers did not. CONCLUSIONS: The serum EDN level may be a useful biomarker for assessing asthma severity in adult asthmatics.

Biomarkers for Recurrent Wheezing and Asthma in Preschool Children

Wheezing is one of the characteristic symptoms of asthma, but all preschool children with wheezing are not diagnosed with asthma. Preschool children are not cooperative enough to participate in spirometry and invasive tests. Thus, there is no conventional method to diagnose asthma in preschool children. We reviewed studies on non-invasive biomarkers for assessing asthma in preschool children. Specimens that can be easily obtained by non-invasive methods are blood, exhaled breath and urine. Eosinophils, eosinophil cationic protein and eosinophil-derived neurotoxin (EDN) in blood are helpful in evaluating eosinophilic inflammation of the airways. Exhaled breath contains nitric oxide, volatile organic compounds, various cytokines and mediators as analytical components. Fraction of exhaled nitric oxide has been used to assess the degree of eosinophil inflammation and has been standardized in school-age children and adults, but not yet in preschool children. Exhaled breath condensate (EBC) pH and various cytokines/mediators that are detected in EBC seem to be promising biomarkers for assessing asthma, but need more standardization and validation. There are several biomarkers useful for assessing asthma, but none are ideal. Some biomarkers need standardized methods of obtaining samples from uncooperative preschool children for clinical use and require sufficient validation. Recently, another activated eosinophil marker, serum EDN, has shown promising results as a biomarker for recurrent wheezing and asthma in preschool children.

Montelukast Reduces Serum Levels of Eosinophil-Derived Neurotoxin in Preschool Asthma

PURPOSE: Several markers for eosinophilic inflammation have been proposed to predict response to asthma treatment. However, definitive criteria for treatment decisions have not yet been established. We investigate a potentially useful relatively non-invasive biomarker, eosinophil-derived neurotoxin (EDN), to predict favorable responses to budesonide or montelukast, common treatment for children with asthma. METHODS: Young children (1 to 6 years old) were enrolled in this randomized, parallel, 2-group, open-label trial. Criteria for eligibility included: 1) being symptomatic during the run-in period; and 2) having a serum EDN (sEDN) level ≥ 53 ng/mL, with positive specific immunoglobulin E to house dust mite. Eligible patients were randomly placed into 2 groups: the BIS group received budesonide inhalation suspension (BIS) 0.5 mg once daily; the MONT group received montelukast 4 mg once daily. Ineligible patients were invited to receive montelukast 4 mg once daily (OBS group). Treatment period was 12 weeks. RESULTS: Asthma control days increased significantly in the BIS and MONT groups (P < 0.000) over the 12-week study period. There was no significant change in sEDN in the BIS group but there was a significant decrease in the MONT group (P < 0.000). Patients in the OBS group with high EDN levels (< 53 ng/mL) showed a significant decrease due to MONT treatment (P = 0.023). Rescue medication usage significantly decreased in the BIS and MONT groups (P < 0.000). CONCLUSIONS: EDN is a useful relatively non-invasive biomarker for predicting responses to montelukast and budesonide treatment of preschool children with beta2-agonist responsive recurrent wheeze and multiple-trigger wheeze (Trial registry at UMIN Clinical Trials Registry, UMIN000008335).

A Double-Blind, Randomized, Crossover Study to Compare the Effectiveness of Montelukast on Atopic Dermatitis in Korean Children

PURPOSE: Some studies report a role of leukotrienes in the pathogenesis of atopic dermatitis and suggest a rationale for the use of leukotriene receptor antagonist (LTRA) in the treatment of atopic dermatitis. This study aimed to evaluate the treatment effectiveness of montelukast in children with atopic dermatitis. METHODS: Fifty-four children between the ages of 2 and 6 years with moderate to severe atopic dermatitis were enrolled. Group A received montelukast for 8 weeks, followed by a crossover to 8 weeks of placebo after a 2-week washout period. Group B reversed the administration according to a randomized, double-blind, placebo-controlled, crossover design. The SCORing atopic dermatitis (SCORAD) index, urinary leukotriene E4 (LTE4), and eosinophil-derived neurotoxin (EDN) were assessed at every visit. RESULTS: Forty-three patients (21 males) completed the study. Although the SCORAD index was decreased in both groups, there was no statistically significant difference between montelukast and placebo (-3.0±11.2 vs -5.7±11.3, P=0.43). The level of urinary LTE4 was decreased after taking montelukast when compared to placebo, but there was no statistically significant difference (-65.9±556.2 vs 87.7±618.3, P=0.26). The changes in urinary EDN after taking montelukast and placebo had no significant difference (37.0±1,008.6 vs -195.8±916.7, P=0.10). When analyzing SCORAD indices, urinary LTE4, and EDN, we could not prove the effectiveness of montelukast in the atopic, non-atopic or high ECP (ECP ≥15 µg/L) subgroups. CONCLUSIONS: There was no statistically significant difference in clinical improvement or biomarkers between montelukast and placebo treatment. Therefore, conventional treatments with skin care and infection control might be more important strategies in the treatment of atopic dermatitis.

Eosinophil-derived neurotoxin: a novel biomarker for diagnosis and monitoring of asthma / 소아과

Asthma is associated with increased levels of eosinophils in tissues, body fluids, and bone marrow. Elevated levels of eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) have been noted in asthma patients. Higher levels of EDN and ECP are also associated with exacerbated asthmatic conditions. Thus, EDN, along with ECP, may aid the diagnosis and monitoring of asthma. Several groups have suggested that EDN is more useful than ECP in evaluating disease severity. This may partially be because of the recoverability of EDN (not sticky, 100% recovery rate), as ECP is a sticky and more highly charged protein. In terms of clinical utility, EDN level is a more accurate biomarker than ECP when analyzing the underlying pathophysiology of asthma. As a monitoring tool, EDN has shown good results in children with asthma as well as other allergic diseases. In children too young to fully participate in lung function tests, EDN levels may be useful as an alter native measurement of eosinophilic inflammation. EDN can also be used in adult patients and in multiple specimen types (e.g., serum, sputum, bronchoalveolar lavage fluid, and nasal lavage fluid). These results are repeatable and reproducible. In conclusion, EDN may be a novel biomarker for the diagnosis, treatment, and monitoring of asthma/allergic disease.

Infection, eosinophilia and childhood asthma

There is a growing list of viruses and bacteria associated with wheezing illness and asthma. It is well known that a few of these pathogens are strongly associated with wheezing illness and asthma exacerbations. What is not known is if early childhood infections with these pathogens cause asthma, and, if so, exactly what are the pathophysiologic mechanisms behind its development. The current consensus is respiratory infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between respiratory infection and asthma may be the eosinophil, a cell that plays prominently in asthma and allergy, but can also be found in the body in response to infection. In turn, the eosinophil and its associated products may be novel therapeutic targets, or at the very least used to elucidate the complex pathophysiologic pathways of asthma and other respiratory illnesses. Together or separately, they can also be used for diagnosis, treatment and monitoring. The optimal care of a patient must take into consideration not only symptoms, but also the underlying disease mechanisms.

Marked Deposition of Eosinophil-Derived Neurotoxin in Adult Patients With Eosinophilic Esophagitis (Am J Gastroenterol 2010;105:298-307)

No abstract available.

The Association of Eosinophilic Airway Inflammation in Mycoplasma pneumonia and Asthma / 소아알레르기및호흡기학회지

PURPOSE:To investigate whether airway eosinophilic degranulation develops in Mycoplasma pneumonia (M. pneumonia), and to elucidate the association between M. pneumonia and asthma. METHODS:Forty patients with M. pneumonia, 20 stable asthma patients (stable asthma) and 20 normal controls were recruited from October 2005 to February 2007. In the M. pneumonia, blood and induced sputum sampling were collected at admission (acute stage) and 6 to 8 weeks later (convalescent stage). Eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) levels in sputum and serum were measured in all 3 groups. RESULTS:Serum levels of EDN and ECP in the acute stage of M. pneumonia were comparable to those in the stable asthma group. However, in the convalescent stage of M. pneumonia, EDN and ECP levels were significantly lower than in the stable asthma (P<0.01 and P<0.05, respectively). Sputum levels of EDN and ECP levels in the acute stage of M. pneumonia were comparable to those in the stable asthma. Sputum EDN levels in the convalescent stage of M. pneumonia were significantly lower than those in the stable asthma (P<0.05), and sputum ECP levels were lower than those in the stable asthma, which was not statistically significant. CONCLUSION:Eosinophilic degranulation may play an important role in the pathogenesis of M. pneumonia, which suggests the association between M. pneumonia and asthma.

The Role of TNF-alpha in Eosinophilic Inflammation of RSV Bronchiolitis / 소아알레르기및호흡기학회지

PURPOSE: Tumor necrosis factor (TNF)-alpha and eosinophilic inflammation have their role in asthma, but there were no studies on respiratory syncytial virus (RSV) bronchiolitis. The aim of our study was to investigate whether TNF-alpha has a role in eosinophilic inflammation of lower respiratory tract infections with RSV and has the correlation with other cytokines. METHODS: Fifty children with first RSV bronchiolitis (RSV group) and 18 healthy children without any respiratory symptom and sign (control group) were enrolled. Clinical data, such as eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), were analyzed. We measured interleukin (IL)-5, IL-8, TNF-alpha, granulocyte macrophage-colony stimulating factor (GM-CSF), interferon (IFN)-gamma, eotaxin, and regulated on activation, normal T cell expressed and secreted (RANTES) in nasal lavage fluid in both groups. RESULTS: Eotaxin, GM-CSF, IL-8, IFN-gamma and TNF-alpha were higher in the RSV group than the control group. TNF-alpha correlated with an eosinophil-active cytokine, GM-CSF (r=0.86, P<0.0001), IFN-gamma (r=0.90, P<0.0001), and with eosinophil-active C-C chemokines such as eotaxin (r=0.50, P<0.0001). TNF-alpha also correlated with proinflammatory cytokines such as IL-8 (r= 0.81, P<0.0001). CONCLUSION: TNF-alpha correlated with eosinophil-active chemokines and cytokines. Therefore, TNF-alpha may have a role in eosinophilic inflammation in children with RSV bronchiolitis.

Relationship with Eosinophil Cationic Protein (ECP)/Eosinophil-derived Neurotoxin (EDN) Levels and Growth Status among Asthmatic Children / 대한소아내분비학회지

PURPOSE: Short statue or obesity has been reported in asthmatic children, but the results are inconsistent. Recently eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN) levels has been known as important markers of airway inflammation and reflect asthma severity as well. The aim of this study is to evaluate the growth status and to analyze the possible relation with serum EDN and ECP levels. METHODS: A total of 90 children (57 boys and 33 girls, 4 to 16 years old) who had been admitted for bronchial asthma were included. To standardize the data for age and sex, standard deviation scores (SDS) were calculated for height and weight. Values less than -2 SDS below the mean were considered to be extremely low, -1 SDS to 1 SDS as normal, values higher than 2 SDS considered very high. Serum EDN and ECP levels were measured. RESULTS: The mean height SDS was 0.33+/-0.85 and weight SDS was 0.23+/-1.20. The prevalence of short stature was 2.2%, normal stature 75.5%, and tall stature 22.2%. The prevalence of underweight was 7.8%, normal weight 71.1%, and overweight 21.1%. Height SDS was negatively correlated with serum ECP (r=-0.27, P=0.01) and EDN (r=-0.27, P=0.009) and weight SDS was negatively correlated with serum ECP (r=-0.20, P=0.05). Height SDS were significantly lower in high ECP and EDN groups compared to normal ECP and EDN groups (P<0.01 and P<0.009, respectively). Weight SDS was lower in high ECP group compared to normal ECP group (P<0.05). CONCLUSION: Growth (height and weight) was inversely correlated with serum EDN and ECP levels. These results suggest that high ECP and EDN levels might be related with growth retardation of asthmatic children.

Eosinophil-derived Neurotoxin and Eosinophil Cationic Protein Levels Correlate with Bronchial Wall Thickness in Children with Asthma Exacerbation / 소아알레르기및호흡기학회지

PURPOSE: Eosinophilic inflammation plays a critical role in asthma and high-resolution computed tomography (HRCT) scoring systems have been used to evaluate the extent and severity in long standing adult asthma. We investigated if there is a correlation between eosinophil degranulation markers and HRCT scores in childhood asthma. METHODS: Children with acute asthma exacerbation (n=25) underwent HRCT and were assessed for bronchial wall thickening (BWT), low lung density (LLD), and bronchial dilatation (BD) using semi-quantitative scoring techniques. Serum eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) levels indicating eosinophil degranulation were determined. Comparisons were made with normal control subjects (n=14). RESULTS: BWT (P<0.001) and LLD (P<0.001) scores were higher in the childhood asthma group than in the control group, but BD scores were not. The EDN (r=0.405, P<0.05) and ECP (r=0.565, P<0.01) levels significantly correlated with BWT scores, but not with LLD and BD in the childhood asthma group. The EDN (r=0.710, P<0.0001) and the ECP (r=0.580, P<0.0001) levels were significantly correlated with serum total eosinophil counts. CONCLUSION: The EDN and ECP levels were correlated with BWT scores on HRCT. These findings suggest that EDN and ECP may be valuable for quantifying airway thickening in children with asthma exacerbation.

Degranulation of human eosinophils induced by Paragonimus westermani-secreted protease

Eosinophil degranulation is considered to be a key effector function for the killing of helminthic worms and tissue inflammation at worm-infected lesion sites. However, relatively little data are available with regard to eosinophil response after stimulation with worm-secreted products which contain a large quantity of cysteine proteases. In this study, we attempted to determine whether the degranulation of human eosinophils could be induced by the direct stimulation of the excretory-secretory products (ESP) of Paragonimus westermani, which causes pulmonary paragonimiasis in human beings. Incubation of eosinophils for 3 hr with Paragonimus-secreted products resulted in marked degranulation, as evidenced by the release of eosinophil-derived neurotoxin (EDN) in the culture supernatants. Moreover, superoxide anion was produced by eosinophils after stimulation of the ESP. The ESP-induced EDN release was found to be significantly inhibited when the ESP was pretreated with protease inhibitor cocktail or the cysteine protease inhibitor, E-64. These findings suggest that human eosinophils become degranulated in response to P. westermani-secreted proteases, which may contribute to in vivo tissue inflammation around the worms.

Activation of Eosinophils with Airborne Fungi / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Allergic fungal sinusitis is characterized by allergic mucin which includes eosinophils and fungal hyphae. But we don't know why eosinophils are accumulated at the nasal secretion and activated, so authors tried to explain the pathophysiologic function of eosinophils by directly stimulating eosinophils with fungal antigens. SUBJECTS AND METHOD: Eosinophils were isolated from healthy volunteers and stimulated with extracts from 5 common fungal species (Alternaria, Aspergillus, Candida, Cladosporium, and Penicillium). Superoxide production and eosinophil derived neurotoxin (EDN) were measured to determine whether fungi activated eosinophils. An inhibition study was done using serine and cystein protease inhibitors. RESULTS: When cultured with fungal antigens, eosinophils produced superoxide by Alternaria and Cladosporium but only Alternaria induced EDN production. Serine protease inhibitors (PMSF, Pefabloc?) and heat treatment of fungi significantly inhibited the activation of eosinophils but the cystein protease inhibitor (E-64) wasn't inhibited. CONCLUSION: Eosinophils are directly activated by Alternaria and their activity was inhibited by serine protease inhibitors. In AFS, fungal serine proteases may activate eosinophils which play important roles in the pathogenesis of AFS, resulting in the destruction of fungi and respiratory epithelial cells.

Differential Excretion of Urinary Eosinophil Protein X after Methacholine Challenge Test in Children with Asthma

PURPOSE: Eosinophil is one of the important inflammatory cell involved in the airway inflammation in childhood asthma. It has been demonstrated that markers of eosinophil activation, including eosinophil cationic protein or eosinophil protein X(EPX), are increased in childhood asthma. Furthermore, they are related to disease activity and are assumed to be helpful in monitoring the treatment effect as urinary EPX(U-EPX) can be obtained easily and in a noninvasive way in children of all ages. METHODS: Twenty-five children(22 male and three female) aged 11.87+/-3.82 years with stable asthma were challenged with methacholine and urine was collected from each child during the following periods; before methacholine challenge test(MCT); 0-3 hr after the end of MCT; 4-7 hr after the end of MCT; and 8-24 hr after the end of MCT. Bronchial reactivity was determined by using Dosimeter(Jeager, Germany) with serially diluted methacholine from 0.05 to 25.0 mg. The FEV1 less than 80% of baseline value were classified into positive MCT. U-EPX was measured with a sensitive and specific radioimmunoassay(Pharmacia & Upjohn AB, Uppsala, Sweden). Results were expressed as microgramEPX/mmol creatinine. RESULTS: An early airway response after MCT was associated with an increase of U-EPX excretion for 0-3 hr after methacholine inhalation in comparison with beseline values. Most subjects showed a small increase in U-EPX excretion during late asthmatic response for 4-7 hr, which then decreased to normal level in 8-24 hr. Also, a tendency for a higher increase of U-EPX was associated with a lower threshold of methacholine challenge and a longer duration of asthma. CONCLUSION: Measurement of EPX in urine is a noninvasive and easy method to assess the severity of airway inflammation in asthmatic children. It may be a helpful index of the events underlying the airway inflammatory responses during nonspecific bronchial challenge, and in monitoring asthma management.