A randomized intervention of montelukast for post-bronchiolitis: effect on eosinophil degranulation

Eosinophil-derived neurotoxin levels in early childhood and association with preschool asthma - A prospective observational study

INTRODUCTION

Eosinophil-derived neurotoxin (EDN) is related to childhood asthma, while normal values are lacking. We aimed to document serum EDN levels at 1 and 3 years in general and in non-atopic children, and explore if EDN levels differed by sex or were associated with preschool asthma at 3 years.

METHODS

From the PreventADALL birth cohort, we included 1233 children with EDN analysed using ImmunoCAP at 1 and/or 3 years. Non-atopic children had no history of wheeze, asthma, allergic sensitization or atopic dermatitis. Preschool asthma was defined as having ≥3 episodes of bronchial obstruction between 2 and 3 years, plus doctor diagnosed asthma and/or asthma medication use by 3 years. The upper limit of normal (ULN) of EDN was defined as the 95th percentile. With Youden Index we calculated EDN cut-off levels for risk of preschool asthma.

RESULTS

The overall median (ULN) EDN levels were 27.4 (121) μg/L at 1 year (n = 787), and 20.1 (87.8) μg/L at 3 years (n = 857). Non-atopic children had EDN levels of 24.0 (107) μg/L at 1 year (n = 147), and 17.3 (84.6) μg/L at 3 years (n = 173). EDN levels were higher in boys compared to girls; 32.0 (133) versus 24.5 (97.0) μg/L at 1 year, and 20.9 (96.3) versus 19.0 (72.4) μg/L at 3 years. Preschool asthma was observed in 109/892 (12.2%) children. Higher EDN levels at 1 (>26.7 μg/L) and 3 (≥20.5 μg/L) years were associated with preschool asthma; adjusted OR (95% CI) 2.20 (1.09, 4.41) and 4.68 (2.29, 9.55), respectively.

CONCLUSION AND CLINICAL RELEVANCE

We report EDN values in early childhood, demonstrating higher levels at 1 compared to 3 years and in boys compared to girls at both ages. Higher EDN levels at both ages were associated with preschool asthma. However, EDN cut-off levels for preschool asthma were overall lower than the ULN of non-atopic children, limiting translation into clinical practice.

Clinical Potential of Eosinophil-Derived Neurotoxin in Asthma Management

The assessment and management of patients with asthma is challenging because of the complexity of the underlying inflammatory mechanisms and heterogeneity of their clinical presentation. Optimizing disease management requires therapy individualization that should rely on reliable biomarkers to unravel the phenotypes and endotypes of asthma. The secretory activity and turnover of eosinophils, as assessed by measuring eosinophil-derived proteins, may provide an accurate and complementary tool that mirrors the eosinophil activation status. Emerging evidence suggests that eosinophil-derived neurotoxin has considerable potential as a precision medicine biomarker. In this review, we explore the suitability of eosinophil-derived neurotoxin as a biomarker in asthma management, with particular emphasis on its clinical significance in the management of both pediatric and adult populations.

Bronchiolitis therapies and misadventures

Viral bronchiolitis, which is most commonly caused by an infection with the respiratory syncytial virus (RSV), can lead to respiratory difficulties in young children which may require hospitalization. Despite years of research and medical trials, the mainstay of bronchiolitis treatment remains supportive only. This review provides an overview of the history of different treatments for bronchiolitis, including those that failed, as well as new therapies that are under study. Future studies for the treatment of bronchiolitis should consider different age-groups, important subgroups (i.e., those with a prior history of wheezing, those with a family history of asthma and those with non-RSV viral etiologies) whose response to treatment may differ from that of the composite group.

Increase in eosinophil-derived neurotoxin level in school children with allergic disease

Background

Eosinophils are major effector cells of allergic disease and excellent markers of eosinophilic inflammation. Accurate and reliable biomarkers are helpful in the diagnosis, treatment, and control of allergic disease.

Objective

This study aimed to investigate an alternate marker of eosinophilic inflammation, eosinophil-derived neurotoxin (EDN), in a number of allergic diseases.

Methods

Three hundred ninety-six elementary school-age children with various allergic conditions were recruited for this study. Subgroups included food allergies (FAs), atopic dermatitis (AD), bronchial asthma (BA), and allergic rhinitis (AR). EDN levels in these groups were compared to those in 93 healthy controls (HC).

Results

All subjects with allergic disease had elevated levels of serum EDN (median [interquartile range]: FA, 124.2 ng/mL [59.13–160.5 ng/mL]; AD, 110.8 ng/mL [57.52–167.9 ng/mL]; BA, 131.5 ng/mL [60.60–171.0 ng/mL]; AR, 91.32 ng/mL [46.16–145.0 ng/mL]) compared to HC (38.38 ng/mL [32.40–55.62 ng/mL]) (p < 0.0001). These elevated levels were consistent throughout the age range (6–12 years) of the healthy study subjects (p = 0.0679). EDN levels also correlated well with total immunoglobulin E (Rs = 0.5599, p < 0.0001). Looking at all individuals with an allergic disease, the area under the curve was 0.790.

Conclusions

Direct measures of eosinophilic inflammation are needed for accurate diagnosis, treatment, and monitoring of allergic diseases. EDN may be a worthy biomarker of eosinophil activity and a useful screening tool for allergic diseases including FA, AD, BA, and AR.

Targeting eosinophils in respiratory diseases: Biological axis, emerging therapeutics and treatment modalities

Eosinophils are bi-lobed, multi-functional innate immune cells with diverse cell surface receptors that regulate local immune and inflammatory responses. Several inflammatory and infectious diseases are triggered with their build up in the blood and tissues. The mobilization of eosinophils into the lungs is regulated by a cascade of processes guided by Th2 cytokine generating T-cells. Recruitment of eosinophils essentially leads to a characteristic immune response followed by airway hyperresponsiveness and remodeling, which are hallmarks of chronic respiratory diseases. By analysing the dynamic interactions of eosinophils with their extracellular environment, which also involve signaling molecules and tissues, various therapies have been invented and developed to target respiratory diseases. Having entered clinical testing, several eosinophil targeting therapeutic agents have shown much promise and have further bridged the gap between theory and practice. Moreover, researchers now have a clearer understanding of the roles and mechanisms of eosinophils. These factors have successfully assisted molecular biologists to block specific pathways in the growth, migration and activation of eosinophils. The primary purpose of this review is to provide an overview of the eosinophil biology with a special emphasis on potential pharmacotherapeutic targets. The review also summarizes promising eosinophil-targeting agents, along with their mechanisms and rationale for use, including those in developmental pipeline, in clinical trials, or approved for other respiratory disorders.

Montelukast use over the past 20 years: monitoring of its effects and safety issues

Montelukast, a leukotriene receptor antagonist, was launched 20 years ago in Korea. It is recommended as an alternative treatment for asthma in children with mild persistent symptoms or as an add-on treatment to existing low-dose inhaled corticosteroids (ICSs) in children who require additional treatment. However, in the real-world setting, many doctors and patients prefer montelukast over ICSs despite their lower efficacy. Although montelukast is considered to be a safe drug, there are concerns regarding adverse drug reactions, including the rare occurrence of Churg-Strauss syndrome and, despite insufficient data, the possibility of neuropsychiatric events such as anxiety, depression, sleep disturbance, and suicidality. This review identified that montelukast has significantly contributed to asthma control over the past 20 years in Korea and has been critical for reducing asthma severity, especially early wheezing and disease control. Our findings suggest that the effects of montelukast treatment can be monitored by measuring serum eosinophilderived neurotoxin levels.

Granulocyte-targeted therapies for airway diseases

The average respiration rate for an adult is 12-20 breaths per minute, which constantly exposes the lungs to allergens and harmful particles. As a result, respiratory diseases, which includes asthma, chronic obstructive pulmonary disease (COPD) and acute lower respiratory tract infections (LTRI), are a major cause of death worldwide. Although asthma, COPD and LTRI are distinctly different diseases with separate mechanisms of disease progression, they do share a common feature - airway inflammation with intense recruitment and activation of granulocytes and mast cells. Neutrophils, eosinophils, basophils, and mast cells are crucial players in host defense against pathogens and maintenance of lung homeostasis. Upon contact with harmful particles, part of the pulmonary defense mechanism is to recruit these cells into the airways. Despite their protective nature, overactivation or accumulation of granulocytes and mast cells in the lungs results in unwanted chronic airway inflammation and damage. As such, understanding the bright and the dark side of these leukocytes in lung physiology paves the way for the development of therapies targeting this important mechanism of disease. Here we discuss the role of granulocytes in respiratory diseases and summarize therapeutic strategies focused on granulocyte recruitment and activation in the lungs.

Advances in paediatrics in 2019: current practices and challenges in allergy, endocrinology, gastroenterology, public health, neonatology, nutrition, nephrology, neurology, respiratory diseases and rheumatic diseases

We highlight the main developments that have been published during the first semester of the last year in the Italian Journal of Pediatrics. We have carefully chosen information from numerous exciting progresses issued in the Journal in the field of allergy, endocrinology, gastroenterology, neonatology, nutrition, nephrology, neurology, public health, respiratory diseases and rheumatic diseases. The impact on the care of patients has been placed in the broader context of studies that appeared in other journals. We think that many observations can be used directly to upgrade management of patients.

[Respiratory syncytial virus]

Respiratory syncytial virus (RSV) is worldwide a very important virus leading to infection of the respiratory system. In particular preterm babies, infants and elderly adults are prone to developing severe diseases such as bronchiolitis or pneumonia, which require intensive care and cause increased mortality. Although RSV is rapidly detected, preventive and therapeutic measures are limited. New antivirals are already in clinical trials.

Comparison of serum eosinophil-derived neurotoxin levels between wheezing and non-wheezing groups in children with respiratory tract infection

Objective: Eosinophil-derived neurotoxin (EDN) is associated with recurrent wheezing episodes after bronchiolitis, childhood asthma, and allergic rhinitis. We investigated if there is a measurable difference between serum EDN levels in children with wheezing and non-wheezing respiratory infections.Methods: 171 children who visited a university hospital with respiratory infections were enrolled in the study. Subjects were divided into two groups: wheezing (n = 46) and non-wheezing (n = 125). Serum EDN levels were compared.Results: Serum EDN levels in the wheezing group were significantly higher than in the non-wheezing group (P < 0.001). The non-wheezing group was divided into three sub-groups: pneumonia, common cold, and tonsillitis. Serum EDN levels in the wheezing group were significantly higher than in the pneumonia, common cold, or tonsillitis subgroups (P < 0.001). There was no significant difference in serum EDN levels among the pneumonia, common cold, and tonsillitis subgroups.Conclusions: These findings suggest that elevated serum EDN levels could be a distinctive feature of respiratory infections with wheezing. EDN's utility as a biomarker for wheezing-associated disease should be explored through further study.

Analysis of the predicting factors of recurrent wheezing in infants

Background

Clinically, asthma in children under 5 years old is under estimated because lack of diagnostic criteria. The current study was, therefore, designed to identify the predicting factors for recurrent wheezing in infants.

Methods

One hundred forty-five infants under 3-year old hospitalized with respiratory diseases were enrolled into this study. Patients were followed up for one-year period after being discharged from the hospital and were, then, divided into recurrent wheezing group and non-recurrent wheezing group based on whether there was recurrent wheezing or not. Wheezing or recurrent wheezing was specifically monitored in addition to blood tests for allergic and respiratory diseases.

Results

The prevalence of eczema and respiratory syncytial virus (RSV) infection were significantly higher in recurrent wheezing group than in control group (74.2% vs 45.8%; 32.3% vs. 13.3%, respectively, both P < 0.05); the percentage of blood eosinophil and serum eosinophil-derived neurotoxin (EDN) concentration at admission were also higher in recurrent wheezing group than in control group (3.10 ± 2.54% vs. 1.31 ± 1.15%; 68.67 ± 55.05 ng/mL vs. 27. 36 ± 19.51 ng/mL; respectively, both P < 0.001). Multivariate logistic regression analysis on eosinophil count and serum EDN concentration in predicting recurrent wheezing revealed that the eosinophil count showed the lowest sensitivity (51.6%) and highest specificity (90.4%), with the area under the ROC curve (AUC) of 0.752 ± 0.041; and that, in contrast, the serum EDN showed the highest sensitivity (88.7%) and lowest specificity (56.6%), with AUC of 0.795 ± 0.037.

Conclusion

Combination of eosinophil count and serum EDN measurement may be better to predict the risk of recurrent wheezing in early life of childhood.

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).

Expression and Regulation of Thymic Stromal Lymphopoietin and Thymic Stromal Lymphopoietin Receptor Heterocomplex in the Innate-Adaptive Immunity of Pediatric Asthma

Asthma is a chronic inflammatory disease affecting the airway, and it is characterized by a wheezing breathing sound, variable airflow obstruction and the presence of inflammatory cells in the submucosa of the bronchi. Viral infection, pollutants and sensitivity to aeroallergens damage the epithelium from childhood, which causes asthma. The pathogenesis of asthma includes pathways of innate stimulation by environmental microbes and irritant pathogens. Damaged epithelial cells produce thymic stromal lymphopoietin (TSLP) and stimulate myeloid dendritic cell maturation through the thymic stromal lymphopoietin receptor (TSLPR) heterocomplex. TSLP-activated myeloid dendritic cells promote naive CD4⁺ T cells to differentiate into T helper type 2 (Th2) phenotype CD4⁺ T cells. Re-exposure to allergens or environmental stimuli causes an adaptive immune response. TSLP-activated dendritic cells expressing the OX40 ligand (OX40L; CD252) trigger naive CD4⁺ T cells to differentiate into inflammatory Th2 effector cells secreting the cytokines interleukin-4, 5, 9, and 13 (IL-4, IL-5, IL-9 and IL-13), and the dendritic cells (DCs) promote the proliferation of allergen-specific Th2 memory cells. Allergen presentation by Th2 cells through its interaction with their receptors in the presence of major histocompatibility complex (MHC) class II on B cells and through costimulation involving CD40 and CD40L interactions results in immunoglobulin class switching from IgM to IgE. DCs and other blood cell subsets express the TSLPR heterocomplex. The regulatory mechanism of the TSLPR heterocomplex on these different cell subsets remains unclear. The TSLPR heterocomplex is composed of the IL-7Rα chain and TSLPR chain. Moreover, two isoforms of TSLP, short isoform TSLP (sfTSLP) and long isoform TSLP (lfTSLP), have roles in atopic and allergic development. Identifying and clarifying the regulation of TSLPR and IL-7Rα in pediatric asthma are still difficult, because the type of blood cell and the expression for each blood cell in different stages of atopic diseases are poorly understood. We believe that further integrated assessments of the regulation mechanism of the TSLP–TSLPR heterocomplex axis in vitro and in vivo can provide a faster and earlier diagnosis of pediatric asthma and promote the development of more effective preventive strategies at the onset of allergies.

Early control treatment with montelukast in preschool children with asthma: A randomized controlled trial

BACKGROUND

While Japanese guideline recommends initial control treatment for preschool children with asthma symptoms more than once a month, Western guidelines do not. To determine whether control treatment with montelukast was more effective than as-needed β₂-agonists in this population, we conducted a randomized controlled trial.

METHODS

Eligible patients were children aged 1-5 years who had asthma symptoms more than once a month but less than once a week. Patients were randomly assigned in a 1:1 ratio to receive montelukast 4 mg daily for 48 weeks or as-needed β₂-agonists. The primary endpoint was the number of acute asthma exacerbations before starting step-up treatment with inhaled corticosteroids. This study is registered with the University Hospital Medical Information Network clinical trials registry, number UMIN000002219.

RESULTS

From September 2009 to November 2012, 93 patients (47 in the montelukast group and 46 in the no-controller group) were enrolled into the study. All patients were included in the analysis. During the study, 13 patients (28%) in the montelukast group and 23 patients (50%) in the no-controller group had acute exacerbations with the mean numbers of 0.9 and 1.9/year, respectively (P = 0.027). In addition, 10 (21%) and 19 (41%) patients received step-up treatment, respectively. Cumulative incidence of step-up treatment was significantly lower in the montelukast group (hazard ratio 0.45, 95% confidence interval 0.21 to 0.92; P = 0.033).

CONCLUSIONS

Montelukast is an effective control treatment for preschool children who had asthma symptoms more than once a month but less than once a week.

Antibiotics for persistent cough or wheeze following acute bronchiolitis in children

BACKGROUND

Bronchiolitis is a common acute respiratory condition with high prevalence worldwide. This clinically diagnosed syndrome is manifested by tachypnoea (rapid breathing), with crackles or wheeze in young children. In the acute phase of bronchiolitis (≤ 14 days), antibiotics are not routinely prescribed unless the illness is severe or a secondary bacterial infection is suspected. Although bronchiolitis is usually self-limiting, some young children continue to have protracted symptoms (e.g. cough and wheezing) beyond the acute phase and often re-present to secondary care.

OBJECTIVES

To compare the effectiveness of antibiotics versus controls (placebo or no treatment) for reducing or treating persistent respiratory symptoms following acute bronchiolitis within six months of acute illness.

SEARCH METHODS

We searched the following databases: the Cochrane Airways Group Register of Trials, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid), the World Health Organization (WHO) trial portal, the Australian and New Zealand Clinical Trials Registry, and ClinicalTrials.gov, up to 26 August 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing antibiotics versus controls (placebo or no treatment) given in the post-acute phase of bronchiolitis (> 14 days) for children younger than two years with a diagnosis of bronchiolitis.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies against predefined criteria, and selected, extracted, and assessed data for inclusion. We contacted trial authors for further information.

MAIN RESULTS

In this review update, we added one study with 219 children. A total of two RCTs with 249 children (n = 240 completed) were eligible for inclusion in this review. Both studies contributed to our primary and secondary outcomes, but we assessed the quality of evidence for our three primary outcomes as low, owing to the small numbers of studies and participants; and high attrition in one of the studies. Data show no significant differences between treatment groups for our primary outcomes: proportion of children (n = 249) who had persistent symptoms at follow-up (odds ratio (OR) 0.69, 95% confidence interval (CI) 0.37 to 1.28; fixed-effect model); and number of children (n = 240) rehospitalised with respiratory illness within six months (OR 0.54, 95% CI 0.05 to 6.21; random-effects model). We were unable to analyse exacerbation rate because studies used different methods to report this information. Data showed no significant differences between treatment groups for our secondary outcome: proportion of children (n = 240) with wheeze at six months (OR 0.47, 95% CI 0.06 to 3.95; random-effects model). One study reported bacterial resistance, but only at 48 hours (thus with limited applicability for this review). Another study reported adverse events from which all children recovered and remained in the study.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to inform whether antibiotics should be used to treat or prevent persistent respiratory symptoms in the post-acute bronchiolitis phase. Future RCTs are needed to evaluate the efficacy of antibiotics for reducing persistent respiratory symptoms. This is particularly important in populations with high acute and post-acute bronchiolitis morbidity (e.g. indigenous populations in Australia, New Zealand, and the USA).

Utility of serum eosinophil-derived neurotoxin (EDN) measurement by ELISA in young children with asthma

BACKGROUND

This study was done to compare the efficacy of a recently developed eosinophil-derived neurotoxin (EDN) ELISA kit ("BioTracer™ K^® EDN ELISA Kit") to a commercially available EDN ELISA kit ("MBL EDN ELISA Kit") and demonstrate the usefulness of serum EDN measurement in young asthmatic children.

METHODS

Forty-eight children with physician-diagnosed asthma (Asthma group) and 31 age-matched normal controls (Control group) were recruited from the Asthma and Allergy Center at Inje University Sanggye Paik Hospital, Seoul, Korea from January 2010 to September of 2012. EDN levels in each serum specimen were measured 2 times using the: 1) BioTracer™ K^® EDN ELISA Kit and 2) MBL EDN ELISA Kit at the Inje University Sanggye Paik Hospital laboratory. EDN level measurements in each serum specimen were compared.

RESULTS

EDN measurements from the BioTracer™ K^® EDN ELISA Kit correlated well with those from the MBL EDN ELISA Kit: r = 0.9472 at the Inje University Sanggye Paik Hospital laboratory. These r values were considered both clinically relevant (i.e., r > 0.85) and statistically significant (p < 0.0001). EDN measurements from both kits positively correlated with asthma symptom severity (p < 0.0001). No serious adverse events occurred during the study.

CONCLUSIONS

The BioTracer™ K^® EDN ELISA Kit was accurate and useful in measuring EDN levels in young asthma patient serum. Because of our kit's distinct advantages and utility, we suggest this kit can be used for the timely diagnosis, treatment, and monitoring of asthma in asthma patients of all ages, especially those too young to perform pulmonary function tests.

Latest options for treatment of bronchiolitis in infants

Bronchiolitis is the most frequent pathology associated with lower respiratory tract infection in newborns and young infants. The treatment of bronchiolitis is essentially supportive therapy for respiratory distress, hypoxia and dehydration. To date, no specific antiviral drug is used on a routine basis for the treatment of RSV infections. Currently, the only antiviral drug approved for the infection is ribavirin; however, its use is limited due to adverse side effects and the risks it poses to healthcare providers. Moreover, several drugs have been routinely administered for years in infants with acute RSV bronchiolitis, even if their efficacy is often not confirmed by clinical evidence, and studies on emerging antiviral drugs are still ongoing. In the present paper we review the recent literature about the drugs used during acute bronchiolitis and we summarize the main recommendations of national and international guidelines and the latest options for the treatment of bronchiolitis.

Characteristics of respiratory syncytial virus-induced bronchiolitis co-infection with Mycoplasma pneumoniae and add-on therapy with montelukast

BACKGROUND

The influence of Mycoplasma pneumoniae (MP) infection on bronchiolitis remains unclear. Additionally, reports on the efficacies of leukotriene receptor antagonists in the treatment of bronchiolitis have been inconclusive.

METHODS

Children with respiratory syncytial virus (RSV)-induced bronchiolitis were divided into two groups: RSV+MP group and RSV group. Each group was randomly divided into two subgroups: one received routine and placebo treatment, while the other received routine and montelukast treatment for 9 months. The cumulative numbers of wheezing episodes and recurrent respiratory tract infections were recorded. Blood parameters were determined.

RESULTS

Patients in the RSV+MP group exhibited an older average age, fever, more frequent flaky and patchy shadows in chest X-rays, more frequent extrapulmonary manifestations, and longer hospital stays compared with patients in the RSV group. Additionally, higher baseline blood eosinophil counts, eosinophil cationic protein (ECP), total immunoglobulin E (IgE), interleukin (IL)-4, IL-5, IL-4/interferon-γ ratios, leukotriene (LT) B4, and LTC4, and lower baseline lipoxin A4 (LXA4)/LTB4 ratios were observed in the RSV+MP group compared with the RSV group. Montelukast treatment decreased the cumulative numbers of recurrent wheezing episodes and recurrent respiratory tract infections at 9 and 12 months. This efficacy may be related to the montelukast-induced reductions in peripheral eosinophil counts, ECP and total IgE, as well as the montelukast-dependent recovery in T helper (Th) 1/Th2 balance and LXA4/LTB4 ratios in children with bronchiolitis.

CONCLUSIONS

RSV bronchiolitis with MP infection was associated with clinical and laboratory features that differed from those of RSV bronchiolitis without MP infection. Add-on therapy with montelukast for 9 months was beneficial for children with bronchiolitis at 9 and 12 months after the initiation of treatment.

Respiratory Emergencies in Children

Focused clinical observation is the key in the initial recognition of respiratory distress in an acutely ill child.

MIP-1α level in nasopharyngeal aspirates at the first wheezing episode predicts recurrent wheezing

BACKGROUND

Respiratory virus-induced wheezing, such as that induced by respiratory syncytial virus (RSV) and human rhinovirus, is an important risk factor for recurrent wheezing and childhood asthma. However, no biomarkers for predicting recurrent wheezing have been identified.

OBJECTIVE

We searched for predictors of recurrent wheezing using nasopharyngeal aspirates obtained from patients during the first wheezing episode who were hospitalized with an acute lower respiratory tract illness.

METHODS

We enrolled 82 infants during the first wheezing episode (median age, 5.0 months) who were hospitalized for acute lower respiratory tract illness between August 2009 and June 2012 and followed these patients for 2.5 years. Nasopharyngeal aspirates and blood samples were obtained on the first day of hospitalization. Viral genomes were identified by using RT-PCR and sequencing. Levels of 33 cytokines, tryptase, IgE, anti-RSV IgE, and anti-RSV IgG were measured by using ELISAs or the Bio-Plex multiplex assay. Predictors of recurrent wheezing were examined by using a stepwise logistic regression model with backward elimination.

RESULTS

Sixty percent of the patients experienced recurrent wheezing episodes. One or more viruses were detected in the nasopharynxes of 93% of the patients during the first wheezing episode. IFN-γ, IL-2, IL-9, MIP-1α, and MIP-1β levels were significantly higher among patients with recurrent wheezing than among those without recurrent wheezing (P < .05 or .01). The stepwise model demonstrated that the MIP-1α level (odds ratio, 7.72; 95% CI, 1.50-39.77; P = .015) was the strongest independent predictor of the occurrence of recurrent wheezing.

CONCLUSION

An increased MIP-1α level in nasopharyngeal aspirates from patients with acute respiratory symptoms during the first wheezing episode caused by viral infections might predict recurrent wheezing.

Leukotriene inhibitors for bronchiolitis in infants and young children

BACKGROUND

Bronchiolitis is an acute inflammatory illness of the bronchioles common among infants and young children. It is often caused by the respiratory syncytial virus (RSV). Management of bronchiolitis varies between clinicians, reflecting the lack of evidence for a specific treatment approach. The leukotriene pathway has been reported to be involved in the pathogenesis of bronchiolitis. Leukotriene inhibitors such as montelukast have been used in infants and young children with bronchiolitis. However, the results from limited randomised controlled trials (RCTs) are controversial and necessitate a thorough evaluation of their efficacy for bronchiolitis in infants and young children.

OBJECTIVES

To assess the efficacy and safety of leukotriene inhibitors for bronchiolitis in infants and young children.

SEARCH METHODS

We searched CENTRAL (2014, Issue 5), MEDLINE (1946 to April week 4, 2014), EMBASE (1974 to May 2014), CINAHL (1981 to May 2014), LILACS (1982 to May 2014), Web of Science (1985 to May 2014), WHO ICTRP and ClinicalTrials.gov (6 May 2014).

SELECTION CRITERIA

RCTs comparing leukotriene inhibitors versus placebo or another intervention in infants and young children under two years of age diagnosed with bronchiolitis. Our primary outcomes were length of hospital stay and all-cause mortality. Secondary outcomes included clinical severity score, percentage of symptom-free days, percentage of children requiring ventilation, oxygen saturation, recurrent wheezing, respiratory rate and clinical adverse effects.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Collaboration methodological practices. Two authors independently assessed trial eligibility and extracted data, such as general information, participant characteristics, interventions and outcomes. We assessed risk of bias and graded the quality of the evidence. We used Review Manager software to pool results and chose random-effects models for meta-analysis.

MAIN RESULTS

We included five studies with a total of 1296 participants under two years of age hospitalised with bronchiolitis. Two studies with low risk of bias compared 4 mg montelukast (a leukotriene inhibitor) daily use from admission until discharge with a matching placebo. Both selected length of hospital stay as a primary outcome and clinical severity score as a secondary outcome. However, the effects of leukotriene inhibitors on length of hospital stay and clinical severity score were uncertain due to considerable heterogeneity between the study results and wide confidence intervals around the estimated effects (hospital stay: mean difference (MD) -0.95 days, 95% confidence interval (CI) -3.08 to 1.19, P value = 0.38, low quality evidence; clinical severity score on day two: MD -0.57, 95% CI -2.37 to 1.23, P value = 0.53, low quality evidence; clinical severity score on day three: MD 0.17, 95% CI -1.93 to 2.28, P value = 0.87, low quality evidence). The other three studies compared montelukast for several weeks for preventing post-bronchiolitis symptoms with placebo. We assessed one study as low risk of bias, whereas we assessed the other two studies as having a high risk of attrition bias. Due to the significant clinical heterogeneity in severity of disease, duration of treatment, outcome measurements and timing of assessment, we did not pool the results. Individual analyses of these studies did not show significant differences between the leukotriene inhibitors group and the control group in symptom-free days and incidence of recurrent wheezing. One study of 952 children reported two deaths in the leukotriene inhibitors group: neither was determined to be drug-related. No data were available on the percentage of children requiring ventilation, oxygen saturation and respiratory rate. Finally, three studies reported adverse events including diarrhoea, wheezing shortly after administration and rash. No differences were reported between the study groups.

AUTHORS' CONCLUSIONS

The current evidence does not allow definitive conclusions to be made about the effects of leukotriene inhibitors on length of hospital stay and clinical severity score in infants and young children with bronchiolitis. The quality of the evidence was low due to inconsistency (unexplained high levels of statistical heterogeneity) and imprecision arising from small sample sizes and wide confidence intervals, which did not rule out a null effect or harm. Data on symptom-free days and incidence of recurrent wheezing were from single studies only. Further large studies are required. We identified one registered ongoing study, which may make a contribution in the updates of this review.

Inter-society consensus document on treatment and prevention of bronchiolitis in newborns and infants

Acute bronchiolitis is the leading cause of lower respiratory tract infection and hospitalization in children less than 1 year of age worldwide. It is usually a mild disease, but some children may develop severe symptoms, requiring hospital admission and ventilatory support in the ICU. Infants with pre-existing risk factors (prematurity, bronchopulmonary dysplasia, congenital heart diseases and immunodeficiency) may be predisposed to a severe form of the disease. Clinical diagnosis of bronchiolitis is manly based on medical history and physical examination (rhinorrhea, cough, crackles, wheezing and signs of respiratory distress). Etiological diagnosis, with antigen or genome detection to identify viruses involved, may have a role in reducing hospital transmission of the infection. Criteria for hospitalization include low oxygen saturation (<90-92%), moderate-to-severe respiratory distress, dehydration and presence of apnea. Children with pre-existing risk factors should be carefully assessed.To date, there is no specific treatment for viral bronchiolitis, and the mainstay of therapy is supportive care. This consists of nasal suctioning and nebulized 3% hypertonic saline, assisted feeding and hydration, humidified O2 delivery. The possible role of any pharmacological approach is still debated, and till now there is no evidence to support the use of bronchodilators, corticosteroids, chest physiotherapy, antibiotics or antivirals. Nebulized adrenaline may be sometimes useful in the emergency room. Nebulized adrenaline can be useful in the hospital setting for treatment as needed. Lacking a specific etiological treatment, prophylaxis and prevention, especially in children at high risk of severe infection, have a fundamental role. Environmental preventive measures minimize viral transmission in hospital, in the outpatient setting and at home. Pharmacological prophylaxis with palivizumab for RSV bronchiolitis is indicated in specific categories of children at risk during the epidemic period. Viral bronchiolitis, especially in the case of severe form, may correlate with an increased incidence of recurrent wheezing in pre-schooled children and with asthma at school age.The aim of this document is to provide a multidisciplinary update on the current recommendations for the management and prevention of bronchiolitis, in order to share useful indications, identify gaps in knowledge and drive future research.

Recent advances in management of bronchiolitis

Background

Bronchiolitis is one of the major causes for hospital admissions in infants. Managing bronchiolitis, both in the outpatient and inpatient setting remains a challenge to the treating pediatrician. The effectiveness of various interventions used for infants with bronchiolitis remains unclear.

Need and purpose

To evaluate the evidence supporting the use of currently available treatment and preventive strategies for infants with bronchiolitis and to provide practical guidelines to the practitioners managing children with bronchiolitis.

Methods

A search of articles published on bronchiolitis was performed using PubMed. The areas of focus were diagnosis, treatment and prevention of bronchiolitis in children. Relevant information was extracted from English language studies published over the last 20 years. In addition, the Cochrane Database of Systematic Reviews was searched.

Results and Conclusions

Supportive care, comprising of taking care of oxygenation and hydration, remains the corner-stone of therapy in bronchiolitis. Pulse oximetry helps in guiding the need for oxygen administration. Several recent evidence-based reviews have suggested that bronchodilators or corticosteroids lack efficacy in bronchiolitis and should not be routinely used. A number of other novel therapies (such as nebulized hypertonic saline, heliox, CPAP, montelukast, surfactant, and inhaled furosemide) have been evaluated in clinical trials, and although most of them did not show any beneficial results, some like hypertonic saline, surfactant, CPAP have shown promising results.

Systematic review of montelukast's efficacy for preventing post-bronchiolitis wheezing

Infants often develop reactive airway diseases subsequent to respiratory syncytial virus (RSV) bronchiolitis. Cysteinyl leukotrienes (cysLTs), a class of lipid mediators that have been implicated in the pathogenesis of allergic rhinitis and asthma, are released during RSV infection, thereby contributing to the pathogenic changes in airway inflammation. Many pediatric patients, especially those of very young age, continue to have recurrent episodes of lower airway obstruction after bronchiolitis treatment. This study was to systematically review and assessed the efficacy of montelukast for preventing wheezing in patients with post-bronchiolitis. The Cochrane library, PubMed, China National Knowledge Infrastructure (CNKI) periodical databases were screened for studies related to use of montelukast for preventing post-bronchiolitis wheezing published up to 31 December 2012. Randomized controlled trials (RCTs) and quasi-RCTs using montelukast alone as an active intervention in infants up to 24 months of age with post-bronchiolitis were selected. Two authors independently extracted data and assessed trial quality using the recommendations published by the Cochrane Collaboration. The meta-analyses were performed using the Cochrane statistical package RevMan5.0.0. Four trials, containing 1430 infants with confirmed diagnosis of acute bronchiolitis, were analyzed. Patients were administered montelukast at post-bronchiolitis. Three trials showed no effects of montelukast on reducing the incidence of recurrent wheezing risk ratios (RR = 0.78, 95% CI: 0.55-1.12, p = 0.17), while two trials found that montelukast did reduce the frequency of recurrent wheezing and another two trials demonstrated no effects of montelukast on symptom-free days. The pooled montelukast treatment group showed no significant effect on reducing the usage of corticosteroids, as compared to the placebo group (RR = 1.11, 95% CI: 0.85-1.44, p = 0.45). Two trials showed that montelukast significantly decreased serum eosinophil-derived neurotoxin levels, as compared to the control group. In general, the side effects of rash, vomiting, and insomnia caused by montelukast occurred in 1.5% of patients analyzed. The recent evidences indicate that montelukast may reduce the frequency of post-bronchiolitic wheezing without causing significant side effects but that it has no effects on decreasing incidences of recurrent wheezing, symptom-free days, or the associated usage of corticosteroid in post-bronchiolitis patients. The small number of enrolled participants and the inability to pool all clinical outcomes precludes us from making solid recommendations.

Predicting the severity of acute bronchiolitis in infants: should we use a clinical score or a biomarker?

Krebs von den Lungen 6 antigen (KL-6) has been shown to be a useful biomarker of the severity of Respiratory syncytial virus bronchiolitis. To assess the correlation between the clinical severity of acute bronchiolitis, serum KL-6, and the causative viruses, 222 infants with acute bronchiolitis presenting at the Pediatric Emergency Department of Estaing University Hospital, Clermont-Ferrand, France, were prospectively enrolled from October 2011 to May 2012. Disease severity was assessed with a score calculated from oxygen saturation, respiratory rate, and respiratory effort. A nasopharyngeal aspirate was collected to screen for a panel of 20 respiratory viruses. Serum was assessed and compared with a control group of 38 bronchiolitis-free infants. No significant difference in KL-6 levels was found between the children with bronchiolitis (mean 231 IU/mL ± 106) and those without (230 IU/mL ± 102), or between children who were hospitalized or not, or between the types of virus. No correlation was found between serum KL-6 levels and the disease severity score. The absence of Human Rhinovirus was a predictive factor for hospitalization (OR 3.4 [1.4-7.9]; P = 0.006). Older age and a higher oxygen saturation were protective factors (OR 0.65[0.55-0.77]; P < 0.0001 and OR 0.67 [0.54-0.85] P < 0.001, respectively). These results suggest that in infants presenting with bronchiolitis for the first time, clinical outcome depends more on the adaptive capacities of the host than on epithelial dysfunction intensity. Many of the features of bronchiolitis are affected by underlying disease and by treatment.

Respiratory syncytial virus bronchiolitis in children

Respiratory syncytial virus is a highly infectious virus that commonly causes bronchiolitis and leads to high morbidity and a low, but important, incidence of mortality. Supportive therapy is the foundation of management. Hydration/nutrition and respiratory support are important evidence-based interventions. For children with severe disease, continuous positive airway pressure or mechanical ventilation may be necessary. Ribavirin may be used for treatment of patients with severe disease. Palivizumab provides important ongoing immunoprophylaxis during epidemic months for high-risk infants. Caregiver education and incorporating an explanation of all therapies and anticipatory guidance, including strategies for reducing the risk of infection, are vital.

Antileukotriene agents for the treatment of lung disease

Leukotrienes (LTs) C4, D4, and E4, collectively termed cysteinyl LTs (cysLTs), are lipid mediators formed by the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism. Originally recognized for their potent bronchoconstrictor actions, they were subsequently determined also to promote inflammation, microvascular permeability, and mucus secretion. These actions that are so central to asthma pathophysiology are mediated to a significant extent by ligation of the cysLT receptor 1 (CysLT1). Antagonism of CysLT1 and inhibition of 5-LO have both been shown to have clinical use in the management of asthma, but substantial interindividual heterogeneity is observed in the response to these agents. In this article, we review the biologic actions of LTs, their biosynthetic pathways and cognate receptors, the pharmacology of available anti-LT agents, and the clinical evidence for the use of anti-LT agents as monotherapy and combination therapy in asthma. We also consider heterogeneity of response, the possible roles of cysLT receptors other than CysLT1, the role of another class of LT, LTB4, and the potential role of LTs in lung diseases other than asthma.

Virus/allergen interactions in asthma

Understanding the underlying mechanisms that cause and exacerbate allergic asthmatic disease is of great clinical interest. Clinical studies have revealed that allergies and viral respiratory illnesses are strongly linked to the inception and exacerbation of asthma, and suggest the possibility that there are interactive inflammatory mechanisms. Recent work has revealed a number of mechanisms of virus and allergen cross-talk that may play a role in the pathophysiology of allergic asthma, including (1) deficiency in virus-induced interferon responses, (2) defective epithelial barrier function, (3) increased release of epithelium-derived cytokines (e.g., thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, IL-33), (4) dysregulation of lymphocytes [e.g., innate lymphoid cells (ILCs), regulatory T cells (Tregs)], and (5) altered activation of purinergic receptors. One or more of these processes may provide targets for new therapeutics to treat allergic asthma and prevent disease exacerbation.

Treatment of bronchiolitis: state of the art

Bronchiolitis is a leading cause of acute illness and hospitalization for infants and young children worldwide. It is usually a mild disease, but the few children developing severe symptoms need to be hospitalized and some will need ventilatory support. To date, the mainstay of therapy has been supportive care, i.e. assisted feeding and hydration, minimal handling, nasal suctioning and oxygen therapy. In recent years the delivery of oxygen has been improved by using a high-flow nasal cannula. At the same time, the discovery of nebulized hypertonic saline enables better airway cleaning with a benefit for respiratory function. The possible role of any pharmacological approach is still debated: many pharmacological therapies tried in the past, ranging from bronchodilators to corticosteroids, were found to offer no benefit in this disease. More recently, nebulized adrenaline demonstrated a short-term benefit. Prophylaxis and prevention, especially in children at high risk of severe infection, such as prematurely born infants and children with bronchopulmonary dysplasia, have a fundamental role in dealing with this disease. In this review, we focus on current recommendations for the management and prevention of bronchiolitis, paying particular attention to the latest literature in search of answers to the questions that remain open.

Eosinophil-derived neurotoxin levels at 3 months post-respiratory syncytial virus bronchiolitis are a predictive biomarker of recurrent wheezing

OBJECTIVE

To determine whether eosinophil-derived neurotoxin (EDN) is a predictive marker of recurrent wheezing episodes in post-respiratory syncytial virus (RSV) bronchiolitis.

METHODS

EDN levels and recurrent wheezing episodes were serially measured in 200 infants hospitalized with RSV bronchiolitis.

RESULTS

Serum EDN levels at 3 months correlated significantly with total wheezing episodes at 12 months in the RSV-PLC (n  = 71; r = 0.720, p < 0.0001) and RSV-MONT groups (n = 79; r = 0.531, p < 0.001). Positive predictive value of 3-mo EDN level for total wheezing episodes was 57%; negative predictive value, 76%; sensitivity, 72%; specificity, 62%.

CONCLUSION

EDN levels have predictive value for the development of recurrent wheezing post-RSV bronchiolitis.

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

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.

Antibiotics for persistent cough or wheeze following acute bronchiolitis in children

BACKGROUND

Bronchiolitis is a common acute respiratory infectious condition, with a high prevalence worldwide. It is a clinically diagnosed syndrome, manifested by tachypnoea (rapid breathing), with crackles or wheeze in young children. In the acute phase of bronchiolitis (< 14 days), antibiotics have only been recommended when a secondary bacterial infection is suspected. Although bronchiolitis is usually a self-limiting condition, a number of children have persistent respiratory symptoms such as cough and wheezing in post-acute bronchiolitis, and they present or re-present to secondary care.

OBJECTIVES

To determine the effectiveness of antibiotics compared to a control (no treatment or placebo) for persistent respiratory symptoms (within six months), following acute bronchiolitis.

SEARCH METHODS

The following databases were searched, The Cochrane Airways Group Register of Trials, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), EMBASE (Ovid) and ClinicalTrials.gov. We searched all databases from their inception to the present, and did not impose restriction on language of publication. The search was performed in October 2012.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing antibiotics with controls (placebo or no treatment) given in the post-acute phase of bronchiolitis (> 14 days) for children younger than two years of age diagnosed with bronchiolitis were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies against pre-defined criteria; and selected, extracted and assessed the data for inclusion. Several subgroup analyses were planned and this included when antibiotics commenced (early commencement classified as preventing; later commencement as treatment for post-bronchiolitis symptoms).

MAIN RESULTS

A single study met the inclusion criteria but had a high attrition rate. Thirty infants with respiratory syncytial virus (RSV)-confirmed bronchiolitis were randomised to receive either a daily dose of oral clarithromycin 15 mg/kg or placebo for three weeks. Using an intention-to-treat (ITT) analysis, there was no significant difference between groups for the proportion of children who had persistent symptoms (odds ratio (OR) 0.20; 95% confidence interval (CI) 0.02 to 2.02) or re-hospitalisation within six months (OR 0.11; 95% CI 0.01 to 1.29). There were no treatment studies of later commencement of antibiotics.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to inform whether antibiotics should be used to treat or prevent persistent respiratory symptoms in the post-acute bronchiolitis phase. Future RCTs that evaluate the efficacy of antibiotics to reduce persistent respiratory symptoms are required, especially in areas where both acute and post-bronchiolitis morbidity is high such as in Indigenous communities in the US, New Zealand and Australia.

Environmental factors association between asthma and acute bronchiolitis in young children--a perspective cohort study

Acute bronchiolitis and asthma are respiratory tract diseases of childhood that are characterized by wheezing. However, the diagnosis of asthma is difficult in patients younger than 2 years. We evaluated the association between asthma or acute bronchiolitis and various risk factors in young children. This perspective cohort study included a study group of children younger than 2 years with a recorded diagnosis of acute bronchiolitis (N = 4,586) as well as a control group (N = 4,263). Children in both groups were registered between January 1, 2004 and December 31, 2004, on the Taiwan Longitudinal Health Insurance Database (2005), and each child was followed in our study until December 31, 2006, using data from the same source. Of the 8,849 children in our study, 355 experienced asthma during the 3-year follow-up period. Among these 355 asthma patients, 332 children (29.1 per 1,000 person-years, 95% CI 26.2-36.4) belonged to the acute bronchiolitis cohort and 23 children (2.0 per 1,000 person-years, 95% CI 13.3-29.9) belonged to the comparison cohort. Cox proportional hazard regression analysis showed that children with acute bronchiolitis were more likely to have asthma than the control population, after adjustment for potential confounders (adjusted hazard ratio [HR] 13.55, 95% CI 8.87-20.71). Boys with acute bronchiolitis had a higher HR for asthma than girls during the 3-year follow-up. Children with acute bronchiolitis who lived in rural areas had a 1.49 HR for asthma compared with their urban counterparts. Children living in the northern region of Taiwan had a higher HR ratio than those in other regions. Sex, urbanization, and geographic region all showed significant associations with acute bronchiolitis and asthma. Based on the asthma-free survival curves of Kaplan-Meier analysis in our study, young children with acute bronchiolitis should be monitored for 2 years to prevent them from developing asthma. This was the first study to evaluate the length of time for which acute bronchiolitis poses a risk for the development of asthma in young children.

Update on leukotriene receptor antagonists in preschool children wheezing disorders

Asthma is the most common chronic disease in young children. About 40% of all preschool children regularly wheeze during common cold infections. The heterogeneity of wheezing phenotypes early in life and various anatomical and emotional factors unique to young children present significant challenges in the clinical management of this problem. Anti-inflammatory therapy, mainly consisting of inhaled corticosteroids (ICS), is the cornerstone of asthma management. Since Leukotrienes (LTs) are chemical mediators of airway inflammation in asthma, the leukotriene receptor antagonists (LTRAs) are traditionally used as potent anti-inflammatory drugs in the long-term treatment of asthma in adults, adolescents, and school-age children. In particular, montelukast decreases airway inflammation, and has also a bronchoprotective effect. The main guidelines on asthma management have confirmed the clinical utility of LTRAs in children older than five years. In the present review we describe the most recent advances on the use of LTRAs in the treatment of preschool wheezing disorders. LTRAs are effective in young children with virus-induced wheeze and with multiple-trigger disease. Conflicting data do not allow to reach definitive conclusions on LTRAs efficacy in bronchiolitis or post-bronchiolitis wheeze, and in acute asthma. The excellent safety profile of montelukast and the possibility of oral administration, that entails better compliance from young children, represent the main strengths of its use in preschool children. Montelukast is a valid alternative to ICS especially in poorly compliant preschool children, or in subjects who show adverse effects related to long-term steroid therapy.

RCT of montelukast as prophylaxis for upper respiratory tract infections in children

BACKGROUND

Infections with viruses causing upper respiratory tract infection (URI) are associated with increased leukotriene levels in the upper airways. Montelukast, a selective leukotriene-receptor antagonist, is an effective treatment of asthma and allergic rhinitis.

OBJECTIVE

To determine whether prophylactic treatment with montelukast reduces the incidence and severity of URI in children.

METHODS

A randomized, double-blind, placebo-controlled study was performed in 3 primary care pediatric ambulatory clinics in Israel. Healthy children aged 1 to 5 years were randomly assigned in a 1:1 ratio to receive 12-week treatment with 4 mg oral montelukast or look-alike placebo. Patients were excluded if they had a previous history of reactive airway disease. A study coordinator contacted the parents by phone once a week to obtain information regarding the occurrence of acute respiratory episodes. The parents received a diary card to record any acute symptoms of URI. The primary outcome measure was the number of URI episodes.

RESULTS

Three hundred children were recruited and randomly assigned into montelukast (n = 153) or placebo (n = 147) groups. One hundred thirty-one (85.6%) of the children treated with montelukast and 129 (87.7%) of the children treated with placebo completed 12 weeks of treatment. The number of weeks in which URI was reported was 30.4% in children treated with montelukast and 30.7% in children treated with placebo. There was no significant difference in any of the secondary variables between the groups.

CONCLUSIONS

In preschool-aged children, 12-week treatment with montelukast, compared with placebo, did not reduce the incidence of URI.

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.

Progress in understanding and controlling respiratory syncytial virus: still crazy after all these years

Human respiratory syncytial virus (RSV) is a ubiquitous pathogen that infects everyone worldwide early in life and is a leading cause of severe lower respiratory tract disease in the pediatric population as well as in the elderly and in profoundly immunosuppressed individuals. RSV is an enveloped, nonsegmented negative-sense RNA virus that is classified in Family Paramyxoviridae and is one of its more complex members. Although the replicative cycle of RSV follows the general pattern of the Paramyxoviridae, it encodes additional proteins. Two of these (NS1 and NS2) inhibit the host type I and type III interferon (IFN) responses, among other functions, and another gene encodes two novel RNA synthesis factors (M2-1 and M2-2). The attachment (G) glycoprotein also exhibits unusual features, such as high sequence variability, extensive glycosylation, cytokine mimicry, and a shed form that helps the virus evade neutralizing antibodies. RSV is notable for being able to efficiently infect early in life, with the peak of hospitalization at 2-3 months of age. It also is notable for the ability to reinfect symptomatically throughout life without need for significant antigenic change, although immunity from prior infection reduces disease. It is widely thought that re-infection is due to an ability of RSV to inhibit or subvert the host immune response. Mechanisms of viral pathogenesis remain controversial. RSV is notable for a historic, tragic pediatric vaccine failure involving a formalin-inactivated virus preparation that was evaluated in the 1960s and that was poorly protective and paradoxically primed for enhanced RSV disease. RSV also is notable for the development of a successful strategy for passive immunoprophylaxis of high-risk infants using RSV-neutralizing antibodies. Vaccines and new antiviral drugs are in pre-clinical and clinical development, but controlling RSV remains a formidable challenge.

Virus/allergen interactions and exacerbations of asthma

Clinical research findings indicate that there are synergistic interactions between allergy and viral infection that cause increased severity of asthma exacerbations. This article summarizes the current literature linking these 2 risk factors for asthma exacerbation, and reviews experimental data suggesting potential mechanisms for interactions between viral infection and allergy that cause asthma exacerbations. In addition, the authors discuss clinical evidence that treatment of allergic inflammation could help to reduce the frequency and severity of virus-induced exacerbations of asthma.

Effects of montelukast on patients with asthma after experimental inoculation with human rhinovirus 16

BACKGROUND

Leukotrienes are induced by viral infections.

OBJECTIVES

To determine whether treatment with montelukast would improve asthma disease control in patients with mild allergic asthma during an experimentally induced rhinovirus infection.

METHODS

Patients with mild allergic asthma were randomized to receive treatment with either montelukast or placebo, and 7 days later both groups were inoculated with human rhinovirus 16. Patients were evaluated at baseline, during the acute infection phase, and during the recovery phase for asthma and cold symptoms by questionnaire. Sputum, nasal lavage fluid, and blood were analyzed for viral shedding and cellular inflammation, and peak expiratory flow was measured daily.

RESULTS

A total of 19 patients (11 in the placebo group and 8 in the active group) completed the study. No significant differences were found in asthma control and cold symptom scores between the control and treatment groups. The change in peak expiratory flow from the randomization to acute illness phase was greater in the placebo group than the treatment group (mean, -22 vs 0 L/min; P = .05). During the recovery phase, the percentage of sputum eosinophils increased in the placebo group and remained at baseline levels in the montelukast group (median, 2.7% vs 0.2%; P = .05 between groups).

CONCLUSIONS

In this pilot study, montelukast did not improve asthma control or cold symptom scores caused by experimental rhinovirus infection. Analysis of secondary outcomes suggests that montelukast may prevent reductions in lung function and increases in sputum eosinophils caused by common cold infections. Further studies are needed to determine whether these effects are associated with clinically significant improvements in health outcomes during natural colds.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00359073.

Respiratory viruses, eosinophilia and their roles in childhood asthma

With the advent of highly sensitive and specific screening of respiratory specimens for viruses, new viruses are discovered, adding to the growing list of those associated with wheezing illness and asthma exacerbations. It is not known whether early childhood infections with these viruses cause asthma, and, if so, what exactly are the pathophysiologic mechanisms behind its development. The current consensus is that respiratory viral infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between viruses and asthma may be the eosinophil, a cell that plays a prominent role in asthma and allergy, but can also be found in the body in response to viral 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 be used for diagnosis, treatment and monitoring. Not only symptoms, but also the underlying disease mechanisms must be taken into consideration for the optimal care of a patient.

The infectious march: the complex interaction between microbes and the immune system in asthma

There has been significant progress in our knowledge about the relationship between infectious disease and the immune system in relation to asthma, but many unanswered questions still remain. Respiratory tract infections such as those caused by respiratory syncytial virus and rhinovirus during the first 2 years of life are still clearly associated with later wheezing and asthma, but the mechanism has not been completely worked out. Is there an "infectious march" triggered by infection in infancy that progresses to disease pathology or are infants who contract respiratory infections predisposed to developing asthma? This review focuses on the common themes in the interaction between microbes and the immune system, and presents a critical appraisal of the evidence to date. The various mechanisms whereby microbes alter the immune response and how this might influence asthma are discussed along with new and promising clinical practices for prevention and therapy. Recent advances in using sensitive polymerase chain reaction detection methods have allowed more rigorous testing of the causality hypothesis of virus infection leading to asthma, but the evidence is still equivocal. Various exceptions and inconsistencies in the clinical trials are discussed in light of new guidelines for subject inclusion/exclusion in hopes of providing some standardization. Despite past failures in vaccination and disappointing results of some clinical trials, the new strategies for prophylaxis including RNA interference and targeted delivery of microbicides offer a large dose of hope to a world suffering from an increasing incidence of asthma as well as a huge burden of health care cost and loss of quality of life.