Bronchoalveolar lavage findings suggest two different forms of childhood asthma

Emergency management and asthma risk in young Medicaid-enrolled children with recurrent wheeze

OBJECTIVES

To describe clinical characteristics of young children presenting to the emergency department (ED) for early recurrent wheeze, and determine factors associated with subsequent persistent wheeze and risk for early childhood asthma.

METHODS

Retrospective cohort study of Medicaid-enrolled children 0-3 years old with an index ED visit for wheeze (e.g. bronchiolitis, reactive airway disease) from 2009 to 2013, and at least one prior documented episode of wheeze at an ED or primary care visit. The primary outcome was persistent wheeze between 4 and 6 years of age. Demographics and clinical characteristics were collected from the index ED visit. Logistic regression was used to estimate the association between potential risk factors and subsequent persistent wheeze.

RESULTS

During the study period, 41,710 children presented to the ED for recurrent wheeze. Mean age was 1.3 years; 59% were male, 42% Black, and 6% Hispanic. At index ED visits, the most common diagnosis was acute bronchiolitis (40%); 77% of children received an oral corticosteroid prescription. Between 4 and 6 years of age, 11,708 (28%) children had persistent wheeze. A greater number of wheezing episodes was associated with an increased odds of ED treatment with asthma medications. Subsequent persistent wheeze was associated with male sex, Black race, atopy, prescription for bronchodilators or corticosteroids, and greater number of visits for wheeze.

CONCLUSIONS

Young children with persistent wheeze are at risk for childhood asthma. Thus, identification of risk factors associated with persistent wheeze in young children with recurrent wheeze might aid in early detection of asthma and initiation of preventative therapies.

Benefits and risks of bronchoalveolar lavage in severe asthma in children

Background

Although bronchoscopy can be part of the exploration of severe asthma in children, the benefit of bronchoalveolar lavage (BAL) is unknown. The present study aimed to decipher whether systematic BAL during a flexible bronchoscopy procedure could better specify the characteristics of severe asthma and improve asthma management.

Material and methods

The study took place in two departments of a university hospital in Paris. Children who underwent flexible bronchoscopy for the exploration of severe asthma between April 2017 and September 2019 were retrospectively included.

Results

In total, 203 children were included, among whom 107 had a BAL. BAL cell count was normal in most cases, with an increasing number of eosinophils with age, independently from the atopic status of the patients. Compared with bronchial aspiration only, BAL increased the rate of identified bacterial infection by 1.5. Nonatopic patients had more bacterial infections (p<0.001). BAL induced a therapeutic modification only for azithromycin and omalizumab prescriptions. The practice of a BAL decreased bronchoscopy tolerance (p=0.037), especially in the presence of tracheobronchial malacia (p<0.01) and when performed in a symptomatic patient (p=0.019).

Discussion and conclusion

Although BAL may provide interesting information in characterising severe asthma, in most cases its impact on the patient's management remains limited. Moreover, BAL can be poorly tolerated and should be avoided in the case of tracheobronchial malacia or current asthma symptoms.

Bronchoalveolar lavage can help characterise severe asthma in children. However, it can be poorly tolerated and, in most cases, its impact on the patient's management remains limited.https://bit.ly/39XOlMt

Time to Say Goodbye to Bronchiolitis, Viral Wheeze, Reactive Airways Disease, Wheeze Bronchitis and All That

The diagnosis and management of infants and children with a significant viral lower respiratory tract illness remains the subject of much debate and little progress. Over the decades various terms for such illnesses have been in and fallen out of fashion or have evolved to mean different things to different clinicians. Terms such as "bronchiolitis," "reactive airways disease," "viral wheeze," and many more are used to describe the same condition and the same term is frequently used to describe illnesses caused by completely different dominant pathologies. This lack of clarity is due, in large part, to a failure to understand the basic underlying inflammatory and associated processes and, in part, due to the lack of a simple test to identify a condition such as asthma. Moreover, there is a lack of insight into the fact that the same pathology can produce different clinical signs at different ages. The consequence is that terminology and fashions in treatment have tended to go around in circles. As was noted almost 60 years ago, amongst pre-school children with a viral LRTI and airways obstruction there are those with a "viral bronchitis" and those with asthma. In the former group, a neutrophil dominated inflammation response is responsible for the airways' obstruction whilst amongst asthmatics much of the obstruction is attributable to bronchoconstriction. The airways obstruction in the former group is predominantly caused by airways secretions and to some extent mucosal oedema (a "snotty lung"). These patients benefit from good supportive care including supplemental oxygen if required (though those with a pre-existing bacterial bronchitis will also benefit from antibiotics). For those with a viral exacerbation of asthma, characterized by bronchoconstriction combined with impaired b-agonist responsiveness, standard management of an exacerbation of asthma (including the use of steroids to re-establish bronchodilator responsiveness) represents optimal treatment. The difficulty is identifying which group a particular patient falls into. A proposed simplified approach to the nomenclature used to categorize virus associated LRTIs is presented based on an understanding of the underlying pathological processes and how these contribute to the physical signs.

Eosinophil cell count in bronchoalveolar lavage fluid in early childhood wheezing: is it predictive of future asthma?

Objective: Increased eosinophil level in bronchoalveolar lavage fluid (BALF) characterizes asthma in school-age children and adults and has been suggested as a marker for disease severity and response to treatment. We aimed to investigate the occurrence and yield of BALF eosinophil cell count in preschool children with recurrent wheezing and its possible relation to future diagnosis of asthma. Methods: BALF was retrospectively studied in young wheezy children and its relation to asthma at age 6 years was evaluated. BALF from children aged 1-48 months (mean = 20.4) was analyzed in preschool wheezy children. Children with anatomical airway obstruction and other lower airway/lung diseases who underwent BALF served as controls. Assessment of asthma was accomplished at 6 years. Results: Eighty-two children were included. The mean age during bronchoscopy and BAL was 20.4 ± 14.4 months (range: 1-48 months). Twenty-six patients had recurrent preschool wheezing, 13 anatomical airway obstruction and 43 had other lower airways/lung diseases. Groups were comparable for age during bronchoscopy and gender. No difference was found between groups for any of the BALF cell types. Eosinophils were very low in all three groups [mean (interquartile range): 0 (0-0.4), 0 (0-0.8), and 0.4 (0-1), respectively, p = 0.25]. No difference in eosinophil levels during bronchoscopy was found between asthmatic children to non-asthmatic as defined at age 6 years. Conclusions: Wheezing in preschool children is not associated with increased BALF eosinophils; hence, at this age, the diagnostic yield of BALF for cell count analysis for diagnosing asthma is limited and is not routinely indicated.

Lung Lavage Granulocyte Patterns and Clinical Phenotypes in Children with Severe, Therapy-Resistant Asthma

BACKGROUND

Children with severe asthma have frequent exacerbations despite guidelines-based treatment with high-dose corticosteroids. The importance of refractory lung inflammation and infectious species as factors contributing to poorly controlled asthma in children is poorly understood.

OBJECTIVE

To identify prevalent granulocyte patterns and potential pathogens as targets for revised treatment, 126 children with severe asthma underwent clinically indicated bronchoscopy.

METHODS

Diagnostic tests included bronchoalveolar lavage (BAL) for cell count and differential, bacterial and viral studies, spirometry, and measurements of blood eosinophils, total IgE, and allergen-specific IgE. Outcomes were compared among 4 BAL granulocyte patterns.

RESULTS

Pauci-granulocytic BAL was the most prevalent granulocyte category (52%), and children with pauci-granulocytic BAL had less postbronchodilator airflow limitation, less blood eosinophilia, and less detection of BAL enterovirus compared with children with mixed granulocytic BAL. Children with isolated neutrophilia BAL were differentiated by less blood eosinophilia than those with mixed granulocytic BAL, but greater prevalence of potential bacterial pathogens compared with those with pauci-granulocytic BAL. Children with isolated eosinophilia BAL had features similar to those with mixed granulocytic BAL. Children with mixed granulocytic BAL took more maintenance prednisone, and had greater blood eosinophilia and allergen sensitization compared with those with pauci-granulocytic BAL.

CONCLUSIONS

In children with severe, therapy-resistant asthma, BAL granulocyte patterns and infectious species are associated with novel phenotypic features that can inform pathway-specific revisions in treatment. In 32% of children evaluated, BAL revealed corticosteroid-refractory eosinophilic infiltration amenable to anti-T_H2 biological therapies, and in 12%, a treatable bacterial pathogen.

Pulmonary epithelial barrier and immunological functions at birth and in early life - key determinants of the development of asthma? A description of the protocol for the Breathing Together study

Background.  Childhood asthma is a common complex condition whose aetiology is thought to involve gene-environment interactions in early life occurring at the airway epithelium, associated with immune dysmaturation.  It is not clear if abnormal airway epithelium cell (AEC) and cellular immune system functions associated with asthma are primary or secondary.  To explore this, we will (i) recruit a birth cohort and observe the evolution of respiratory symptoms; (ii) recruit children with and without asthma symptoms; and (iii) use existing data from children in established STELAR birth cohorts.    Novel pathways identified in the birth cohort will be sought in the children with established disease.  Our over-arching hypothesis is that epithelium function is abnormal at birth in babies who subsequently develop asthma and progression is driven by abnormal interactions between the epithelium, genetic factors, the developing immune system, and the microbiome in the first years of life.

Methods.  One thousand babies will be recruited and nasal AEC collected at 5-10 days after birth for culture.  Transcriptomes in AEC and blood leukocytes and the upper airway microbiome will be determined in babies and again at one and three years of age. In a subset of 100 individuals, AEC transcriptomes and microbiomes will also be assessed at three and six months.  Individuals will be assigned a wheeze category at age three years.  In a cross sectional study, 300 asthmatic and healthy children aged 1 to 16 years will have nasal and bronchial AEC collected for culture and transcriptome analysis, leukocyte transcriptome analysis, and upper and lower airway microbiomes ascertained.  Genetic variants associated with asthma symptoms will be confirmed in the STELAR cohorts. 

Conclusions.  This study is the first to comprehensively study the temporal relationship between aberrant AEC and immune cell function and asthma symptoms in the context of early gene-microbiome interactions.

Should a Preschool Child with Acute Episodic Wheeze be Treated with Oral Corticosteroids? A Pro/Con Debate

Traditionally, preschool-aged children with an acute wheezing episode have been treated with oral corticosteroids (OCSs) based on the efficacy of OCSs in older children and adolescents. However, this practice has been recently challenged based on the results of recent studies. The argument supporting the use of OCSs underscores the observation that many children with recurrent preschool wheezing develop atopic disease in early life which predicts both an increased risk to develop asthma in later life and response to OCS therapy. Further, review of the literature demonstrates heterogeneity of study designs, OCS dosage, interventions, study medication adherence, and settings and overall lack of predefined preschool wheezing phenotypes. The heterogeneity of these studies does not allow a definitive recommendation discouraging OCS use. Advocates against the use of OCSs in this population argue that most of studies investigating the efficacy of OCSs in acute episodic wheeze in preschool-aged children have not demonstrated beneficial effects. Moreover, repeated OCS bursts may be associated with adverse effects. Finally, both sides can agree that there is a significant need to conduct efficacy trials evaluating OCS treatment in preschool-aged children with recurrent wheezing targeted at phenotypes that would be expected to respond to OCSs. This article presents a summary of recent literature regarding the use of OCSs for acute episodic wheezing in preschool-aged children and a "pro" and "con" debate for such use.

Leukotriene receptor antagonists in virus-induced wheezing : evidence to date

Virus-induced wheezing is a relatively benign entity that is usually transient in early childhood but is responsible for much health care utilization. The condition, seen traditionally as a subset of those children diagnosed as having frequent episodic asthma, is often treated with inhaled corticosteroids, despite their lack of efficacy. However, there remains some confusion differentiating atopic asthma from virus-induced wheezing in young children and their respective treatment strategies.The demonstration of cysteinyl leukotrienes in the nasopharyngeal secretions of infants and young children who wheeze prompted investigation of the role of leukotriene receptor antagonists in the treatment of virus-induced wheezing for young children with bronchiolitis and virus-induced wheezing.Montelukast, the only leukotriene receptor antagonist studied in young children, has been proven useful in increasing the number of symptom-free days and delaying the recurrence of wheeze in the month following a diagnosis of respiratory syncytial virus-induced wheezing in children aged 3-36 months. Subsequently, in children aged 2-5 years with frequent episodic asthma, primarily involving viral induced attacks in this age group, regular therapy with daily montelukast for 12 months reduced the rate of asthma exacerbations by 31% over placebo, delayed the time to the first exacerbation by 2 months, and lowered the need to prescribe inhaled corticosteroids as preventative therapy. Additionally, montelukast has been demonstrated to be efficacious as an acute episode modifier in children aged 2-14 years (85% children <6 years) with virus-induced wheezing where it was prescribed at the onset of a viral infection in children with an established pattern of viral induced episodes of wheeze in the preceding year. In this study, emergency department visits were reduced by 45%, visits to all health care practitioners were reduced by 23%, and time of preschool/school and parental time off work was reduced by 33% for children who took montelukast for a median of 10 days.At present, there is good evidence to support the use of bronchodilators in the acute treatment of virus- induced wheezing, and increasing evidence to support the use of leukotriene receptor antagonists, in particular montelukast, in the management of children with virus-induced wheezing.

Exhaled breath temperature measurement and asthma control in children prescribed inhaled corticosteroids: A cross sectional study

BACKGROUND

Exhaled breath temperature (EBT) reflects airways (both eosinophilic and neutrophilic) inflammation in asthma and thus may aid the management of children with asthma that are treated with anti-inflammatory drugs. A new EBT monitor has become available that is cheap and easy to use and may be a suitable monitoring device for airways inflammation. Little is known about how EBT relates to asthma treatment decisions, disease control, lung function, or other non-invasive measures of airways inflammation, such as exhaled nitric oxide (ENO).

OBJECTIVE

To determine the relationships between EBT and asthma treatment decision, current control, pulmonary function, and ENO.

METHODS

Cross-sectional prospective study on 159 children aged 5-16 years attending a pediatric respiratory clinic. EBT was compared with the clinician's decision regarding treatment (decrease, no change, increase), asthma control assessment (controlled, partial, uncontrolled), level of current treatment (according to British Thoracic Society guideline, BTS step), ENO, and spirometry.

RESULTS

EBT measurement was feasible in the majority of children (25 of 159 could not perform the test) and correlated weakly with age (R = 0.33, P = <0.01). EBT did not differ significantly between the three clinician decision groups (P = 0.42), the three asthma control assessment groups (P = 0.9), or the current asthma treatment BTS step (P = 0.57).

CONCLUSIONS & CLINICAL IMPLICATIONS

EBT measurement was not related to measures of asthma control determined at the clinic. The routine intermittent monitoring of EBT in children prescribed inhaled corticosteroids who attend asthma clinics cannot be recommended for adjusting anti-inflammatory asthma therapy.

Epidermal Growth Factor Removal or Tyrphostin AG1478 Treatment Reduces Goblet Cells & Mucus Secretion of Epithelial Cells from Asthmatic Children Using the Air-Liquid Interface Model

Rationale

Epithelial remodelling in asthma is characterised by goblet cell hyperplasia and mucus hypersecretion for which no therapies exist. Differentiated bronchial air-liquid interface cultures from asthmatic children display high goblet cell numbers. Epidermal growth factor and its receptor have been implicated in goblet cell hyperplasia.

Objectives

We hypothesised that EGF removal or tyrphostin AG1478 treatment of differentiating air-liquid interface cultures from asthmatic children would result in a reduction of epithelial goblet cells and mucus secretion.

Methods

In Aim 1 primary bronchial epithelial cells from non-asthmatic (n = 5) and asthmatic (n = 5) children were differentiated under EGF-positive (10ng/ml EGF) and EGF-negative culture conditions for 28 days. In Aim 2, cultures from a further group of asthmatic children (n = 5) were grown under tyrphostin AG1478, a tyrosine kinase inhibitor, conditions. All cultures were analysed for epithelial resistance, markers of differentiation using immunocytochemistry, ELISA for MUC5AC mucin secretion and qPCR for MUC5AC mRNA.

Results

In cultures from asthmatic children the goblet cell number was reduced in the EGF negative group (p = 0.01). Tyrphostin AG1478 treatment of cultures from asthmatic children had significant reductions in goblet cells at 0.2μg/ml (p = 0.03) and 2μg/ml (p = 0.003) as well as mucus secretion at 2μg/ml (p = 0.04).

Conclusions

We have shown in this preliminary study that through EGF removal and tyrphostin AG1478 treatment the goblet cell number and mucus hypersecretion in differentiating air-liquid interface cultures from asthmatic children is significantly reduced. This further highlights the epidermal growth factor receptor as a potential therapeutic target to inhibit goblet cell hyperplasia and mucus hypersecretion in asthma.

Airway epithelial cytokine responses in childhood wheeze are independent of atopic status

BACKGROUND

Airway epithelial cells (AEC) are key contributors to immune function in the lungs but little is known about their role and function in children.

OBJECTIVES

Having previously established that nasal AEC mediator release correlates with that of bronchial AEC, we assessed AEC responses in children with and without a history of wheeze.

METHODS

Nasal AEC cultures were established from children (0.6-14.9 years) undergoing elective surgical procedures under general anaesthetic categorised as atopic asthmatic (n = 12), virus-induced wheeze (n = 8) or children without wheeze (n = 32). Mediator release by AEC monolayers at passage 2 was determined by cytometric bead array assay or ELISA.

RESULTS

Unstimulated AEC from children with a history of wheeze produced significantly less IL-8, IL-6, MCP-1 and G-CSF than AEC from healthy controls. There were no group differences in AEC release of VEGF, RANTES, MMP-9 or TIMP-1. After stimulation with the pro-inflammatory cytokines IL-1β and TNFα, AEC from children with current wheeze produced significantly less IL-8, IL-6 and MCP-1 than children without wheeze. Release of G-CSF, VEGF, MMP-9 and TIMP-1 did not differ between the wheeze and control group. There were no differences in mediator release between subjects with atopic asthma and those with virus-induced wheeze or between atopic and non-atopic controls. On multivariate analysis, wheeze was the only significant predictor of AEC mediator release.

CONCLUSION & CLINICAL RELEVANCE

Intrinsic differences in AEC from children with a history of wheeze may reflect a defect in cytokine production in vivo or an altered state of differentiation in vitro, independent of atopic status.

Bronchoalveolar lavage in infants with recurrent lower respiratory symptoms

BACKGROUND

Few data are available about the inflammatory cytokine profile of bronchoalveolar lavage (BAL) from young children with frequent wheeze. The first aim was to investigate the BAL cellular and cytokine profiles in infants with recurrent lower respiratory symptoms in whom bronchoscopy was indicated for clinical symptom evaluation. The second aim was to relate the BAL results with the histological findings of the endobronchial carina biopsies.

METHODS

Thirty-nine infants (median age 0.9 years) underwent lung function testing by whole-body plethysmography prior to the bronchoscopy. The BAL differential cell counts and cytokine levels were quantified. These findings were compared with the histological findings of the endobronchial carina biopsies.

RESULTS

The differential cytology reflected mainly that described for healthy infants with lymphocyte counts at the upper range level. A positive association between BAL CD8+ lymphocytes and neutrophils and endobronchial reticular basement membrane was found. Detectable levels of pro-inflammatory cytokine proteins IL-1β, IL-17A, IL-18, IL-23, and IL-33 were found, whereas levels of Th2-type cytokine proteins were low. Frequent wheeze was the only clinical characteristic significantly related to detectable combined pro-inflammatory cytokine profile. Lung function did not correlate with any cytokine.

CONCLUSIONS

A positive association between BAL CD8+ lymphocytes and neutrophils and endobronchial reticular basement thickness was found. Detectable production of pro-inflammatory cytokines associated positively with frequent wheeze.

Exhaled nitric oxide is related to atopy, but not asthma in adolescents with bronchiolitis in infancy

Background

The fraction of exhaled nitric oxide (FeNO) has been suggested as a non-invasive marker of eosinophilic inflammation in asthma, but lately rather as a biomarker of atopy than of asthma itself. Asthma after bronchiolitis is common up to early adolescence, but the inflammation and pathophysiology may differ from other phenotypes of childhood asthma. We aimed to assess if FeNO was different in children with former hospitalization for bronchiolitis and a control group, and to explore whether the role of FeNO as a marker of asthma, atopy or bronchial hyperresponsiveness (BHR) differed between these two groups of children.

Methods

The study included 108 of 131 children (82%) hospitalized for bronchiolitis in 1997–98, of whom 82 (76%) had tested positive for Respiratory syncytial virus, and 90 age matched controls. The follow-up took place in 2008–2009 at 11 years of age. The children answered an ISAAC questionnaire regarding respiratory symptoms and skin prick tests, spirometry, methacholine provocation test and measurement of FeNO were performed.

Results

Analysed by ANOVA, FeNO levels did not differ between the post-bronchiolitis and control groups (p = 0.214). By multivariate regression analyses, atopy, height (p < 0.001 for both) and BHR (p = 0.034), but not asthma (p = 0.805) or hospitalization for bronchiolitis (p = 0.359), were associated with FeNO in the post-bronchiolitis and control groups. The associations for atopy and BHR were similar in the post-bronchiolitis and in the control group.

Conclusion

FeNO did not differ between 11 year old children hospitalized for bronchiolitis and a control group. FeNO was associated with atopy, but not with asthma in both groups.

Difficult childhood asthma: management and future

Diagnosis and management of severe asthma implies the definition of different entities, that is, difficult asthma and refractory severe asthma, but also the different phenotypes included in the term refractory severe asthma. A complete evaluation by a physician expert in asthma is necessary, adapted for each child. Identification of mechanisms involved in different phenotypes in refractory severe asthma may improve the therapeutic approach. The quality of care and monitoring of children with severe asthma is as important as the prescription drug, and is also crucial for differentiating between severe asthma and difficult asthma, whereby expertise is required.

TNF-alpha is a key mediator in the development of Th2 cell response to inhaled allergens induced by a viral PAMP double-stranded RNA

BACKGROUND

Viral pathogen-associated molecular patterns, such as dsRNA, disrupt airway tolerance to inhaled allergens. Specifically, the Th2 and Th17 cell responses are induced by low-dose dsRNA and the Th1-dominant response by high-dose dsRNA.

OBJECTIVE

In this model, we evaluate the role of TNF-α in the development of adaptive immune dysfunction to inhaled allergens induced by airway sensitization with dsRNA-containing allergens.

METHODS

A virus-associated asthma mouse model was generated via simultaneous airway administration of ovalbumin (OVA) and low (0.1 μg) or high (10 μg) doses of polyinosine-polycytidylic acid (poly[I:C]). The effect of TNF-α on Th2 airway inflammation was evaluated using TNF-α-deficient mice and recombinant TNF-α.

RESULTS

TNF-α production was enhanced by airway exposure to low and high doses of poly[I:C]. After airway sensitization with OVA plus low-dose poly[I:C], TNF-α-deficient mice exhibited less OVA-induced airway inflammation than did wild-type (WT) mice. However, this did not occur upon sensitization with high-dose poly[I:C]. In terms of T-cell response, the production of IL-4 from lung T cells after OVA challenge was enhanced by airway sensitization with OVA plus low-dose poly[I:C] in WT mice, and this phenotype was inhibited by the absence of TNF-α. Moreover, the Th2 cell response induced by sensitization with OVA plus low-dose poly[I:C], which was abolished in TNF-α-deficient mice, was restored in these mice upon addition of recombinant TNF-α.

CONCLUSION

The results of this study suggest that TNF-α produced by airway exposure to low-dose dsRNA is a key mediator in the development of Th2 cell response to inhaled allergens.

Does bronchial hyperresponsiveness in childhood predict active asthma in adolescence?

RATIONALE

Bronchial hyperresponsiveness (BHR) is an important, but not specific, asthma characteristic.

OBJECTIVES

We aimed to assess the predictive value of BHR tested by methacholine and exercise challenge at age 10 years for active asthma 6 years later.

METHODS

From a Norwegian birth cohort, 530 children underwent methacholine challenge and exercise-induced bronchoconstriction (EIB) test (n = 478) at 10 years and structured interview and clinical examination at age 16 years. The methacholine dose causing 20% reduction in FEV(1) (PD(20)) and the reduction in FEV(1) (%) after a standardized treadmill test were used for BHR assessment. Active asthma was defined with at least two criteria positive: doctor's diagnosis of asthma, symptoms of asthma, and/or treatment for asthma in the last year.

MEASUREMENTS AND MAIN RESULTS

PD(20) and EIB at 10 years of age increased the risk of asthma (β = 0.94 [95% confidence interval (CI), 0.92-0.96] per μmol methacholine and β = 1.10 [95% CI, 1.06-1.15] per %, respectively). Separately the tests explained 10 and 7%, respectively, and together 14% of the variation in active asthma 6 years later. The predicted probability for active asthma at the age of 16 years increased with decreasing PD(20) and increasing EIB. The area under the curve (receiver operating characteristic curves) was larger for PD(20) (0.69; 95% CI, 0.62-0.75) than for EIB (0.60; 95% CI, 0.53-0.67).

CONCLUSIONS

BHR at 10 years was a significant but modest predictor of active asthma 6 years later, with methacholine challenge being superior to exercise test.

Trends in childhood asthma hospitalisation in three Asia Pacific countries

AIM

The study aims to examine recent childhood asthma hospitalisation rates in the Asia Pacific countries of Australia, Hong Kong and Singapore. On the background of reported decline in many countries with high asthma prevalence during late 1990s.

METHODS

Annual asthma hospitalisation (ICD9-CM: 493 or ICD10-AM: J45-46)* and population data from 1994 to 2008, of children aged 0-14 years old, were obtained from the Australian National Hospital Morbidity Database, from the Hospital Authority in Hong Kong and from the Ministry of Health in Singapore. Data were stratified in two age groups: 0-4 and 5-14 years old, and also in different periods of calendar years. Time-series regression analyses were used to examine temporal trends. Diagnostic transfer was addressed by examining bronchitis hospitalisations.

RESULTS

Significant decreases of up to 6.5% per annum in childhood asthma hospitalisation rates were found over the study period. However, the latter half of the study period showed increases in hospitalisation rates in all countries studied. No evidence of diagnostic transfer was found.

CONCLUSION

Although there has been a decrease in childhood asthma hospitalisation rates since the 1990s, a modest increase was observed from 2003 to 2008. Ongoing monitoring is required.

Rapamycin decreases airway remodeling and hyperreactivity in a transgenic model of noninflammatory lung disease

Airway hyperreactivity (AHR) and remodeling are cardinal features of asthma and chronic obstructive pulmonary disease. New therapeutic targets are needed as some patients are refractory to current therapies and develop progressive airway remodeling and worsening AHR. The mammalian target of rapamycin (mTOR) is a key regulator of cellular proliferation and survival. Treatment with the mTOR inhibitor rapamycin inhibits inflammation and AHR in allergic asthma models, but it is unclear if rapamycin can directly inhibit airway remodeling and AHR, or whether its therapeutic effects are entirely mediated through immunosuppression. To address this question, we utilized transforming growth factor-α (TGF-α) transgenic mice null for the transcription factor early growth response-1 (Egr-1) (TGF-α Tg/Egr-1(ko/ko) mice). These mice develop airway smooth muscle thickening and AHR in the absence of altered lung inflammation, as previously reported. In this study, TGF-α Tg/Egr-1(ko/ko) mice lost body weight and developed severe AHR after 3 wk of lung-specific TGF-α induction. Rapamycin treatment prevented body weight loss, airway wall thickening, abnormal lung mechanics, and increases in airway resistance to methacholine after 3 wk of TGF-α induction. Increases in tissue damping and airway elastance were also attenuated in transgenic mice treated with rapamycin. TGF-α/Egr-1(ko/ko) mice on doxycycline for 8 wk developed severe airway remodeling. Immunostaining for α-smooth muscle actin and morphometric analysis showed that rapamycin treatment prevented airway smooth muscle thickening around small airways. Pentachrome staining, assessments of lung collagen and fibronectin mRNA levels, indicated that rapamycin also attenuated fibrotic pathways induced by TGF-α expression for 8 wk. Thus rapamycin reduced airway remodeling and AHR, demonstrating an important role for mTOR signaling in TGF-α-induced/EGF receptor-mediated reactive airway disease.

Effects of IL-13 on mucociliary differentiation of pediatric asthmatic bronchial epithelial cells

Goblet cell hyperplasia (GCH) and decreased ciliated cells are characteristic of asthma. We examined the effects of IL-13 (2 and 20 ng/mL) on in vitro mucociliary differentiation in pediatric bronchial epithelial cells (PBECs) of normal PBEC [PBEC(N)] and asthmatic PBEC [PBEC(A)] children. Markers of differentiation, real-time PCR for MUC5AC, MUC5AC ELISA, and transepithelial electrical resistance (TEER) were assessed. Stimulation with 20 ng/mL IL-13 in PBEC(N) resulted in GCH [20 ng/mL IL-13: mean, 33.8% (SD, 7.2) versus unstimulated: mean, 18.9% (SD, 5.0); p < 0.0001] and decreased ciliated cell number [20 ng/mL IL-13: mean, 8% (SD, 5.6) versus unstimulated: mean, 22.7% (SD,7.6); p < 0.01]. PBEC(N) stimulated with 20 ng/mL IL-13 resulted in >5-fold (SD, 3.2) increase in MUC5AC mRNA expression, p < 0.001, compared with unstimulated PBEC(N). In PBEC(A), GCH was also seen [20 ng/mL IL-13: mean, 44.7% (SD, 16.4) versus unstimulated: mean, 30.4% (SD, 13.9); p < 0.05] with a decreased ciliated cell number [20 ng/mL IL-13: mean, 8.8% (SD, 7.5) versus unstimulated: mean, 16.3% (SD, 4.2); p < 0.001]. We also observed an increase in MUC5AC mRNA expression with 20 ng/mL IL-13 in PBEC(A), p < 0.05. IL-13 drives PBEC(N) toward an asthmatic phenotype and worsens the phenotype in PBEC(A) with reduced ciliated cell numbers and increased goblet cells.

Does airway allergic inflammation pre-exist before late onset wheeze in children?

Epidemiological studies show that some children develop wheezing after 3 yr of age which tends to persist. It is unknown how this starts or whether there is a period of asymptomatic inflammation. The aim of this study is to determine whether lower airway allergic inflammation pre-exists in late onset childhood wheeze (LOCW). Follow-up study of children below 5 yr who had a non-bronchoscopic bronchoalveolar lavage (BAL) performed during elective surgery. The children had acted as normal controls. A modified ISAAC questionnaire was sent out at least 7 yr following the initial BAL, and this was used to ascertain whether any children had subsequently developed wheezing or other atopic disease (eczema, allergic rhinitis). Cellular and cytokine data from the original BAL were compared between those who never wheezed (NW) and those who had developed LOCW. Eighty-one normal non-asthmatic children were recruited with a median age of 3.2. Of the 65 children contactable, 9 (16.7%) had developed wheeze, 11 (18.5%) developed eczema and 14 (22.2%) developed hay fever. In five patients, wheeze symptoms developed mean 3.3-yr (range: 2-5 yr) post-BAL. Serum IgE and blood eosinophils were not different in the LOCW and NW, although the blood white cell count was lower in the LOCW group. The median BAL eosinophil % was significantly increased in the patients with LOCW (1.55%, IQR: 0.33 to 3.92) compared to the children who never wheezed, NW (0.1, IQR: 0.0 to 0.3, p = 0.01). No differences were detected for other cell types. There were no significant differences in BAL cytokine concentrations between children with LOCW and NW children. Before late onset childhood wheezing developed, we found evidence of elevated eosinophils in the airways. These data suggest pre-existent airways inflammation in childhood asthma some years before clinical presentation.

A viral PAMP double-stranded RNA induces allergen-specific Th17 cell response in the airways which is dependent on VEGF and IL-6

BACKGROUND

Innate immune response by a viral pathogen-associated molecular pattern dsRNA modulates the subsequent development of adaptive immune responses. Although virus-associated asthma is characterized by noneosinophilic inflammation, the role of Th17 cell response in the development of virus-associated asthma is still unknown.

OBJECTIVE

To evaluate the role of the Th17 cell response and its underlying polarizing mechanisms in the development of an experimental virus-associated asthma.

METHODS

An experimental virus-associated asthma was created via airway sensitization with ovalbumin (OVA, 75 μg) and a low (0.1 μg) or a high (10 μg) doses of synthetic dsRNA [polyinosine-polycytidylic acid; poly(I:C)]. Transgenic (IL-17-, IL-6-deficient mice) and pharmacologic [a vascular endothelial growth factor receptor (VEGFR) inhibitor] approaches were used to evaluate the roles of Th17 cell responses.

RESULTS

After cosensitization with OVA and low-dose poly(I:C), but not with high-dose poly(I:C), inflammation scores after allergen challenge were lower in IL-17-deficient mice than in wild-type (WT) mice. Moreover, inflammation enhanced by low-dose poly(I:C), but not by high-dose poly(I:C), was impaired in IL-6-deficient mice; this phenotype was accompanied by the down-regulation of IL-17 production from T cells from both lymph nodes and lung tissues. Airway exposure of low-dose poly(I:C) enhanced the production of VEGF and IL-6, and the production of IL-6 was blocked by treatment with a VEGFR inhibitor (SU5416). Moreover, the allergen-specific Th17 cell response and subsequent inflammation in the low-dose poly(I:C) model were impaired by the VEGFR inhibitor treatment during sensitization.

CONCLUSIONS

Airway exposure of low-level dsRNA induces an allergen-specific Th17 cell response, which is mainly dependent on VEGF and IL-6.

Markers of eosinophilic and neutrophilic inflammation in bronchoalveolar lavage of asthmatic and atopic children

BACKGROUND

Recent studies performing fiberoptic bronchoscopy in children have improved our understanding of asthma pathophysiology. Eosinophilic, but also neutrophilic, inflammation has been described in asthma, but the relationship with atopy was incompletely investigated. The aim of this study is to examine inflammatory cells and mediators in children with asthma compared to the appropriate controls, i.e. atopic children without asthma and children with no atopy or asthma. Moreover, asthmatic children were analysed separately based on the presence of atopy and stratified by age.

METHODS

We recruited 191 children undergoing fiberoptic bronchoscopy for appropriate indications: 91 asthmatics (aged 1.4-17 years), 44 atopics without asthma (1.6-17.8 years) and 56 nonasthmatic nonatopic controls (1.4-14 years). In bronchoalveolar lavage, total and differential cell counts and inflammatory mediators, including ECP, eotaxin, IL-8 and TNFalpha, were analysed.

RESULTS

Eosinophils and ECP levels were increased in asthmatic children when compared to controls (P = 0.002 and P = 0.01, respectively), but also atopic children without asthma had increased ECP levels compared to controls (P = 0.0001). Among asthmatic children, eosinophils and ECP levels were not different between atopic and nonatopic individuals. Neither neutrophils nor the related mediators (IL-8 and TNFalpha) differed significantly in the three groups. This pattern of inflammation was observed in both preschool and school-aged asthmatic children.

CONCLUSIONS

This study suggests that markers of eosinophilic, but not neutrophilic inflammation, are increased in asthmatic children and also in atopic children without asthma. Of interest, in asthmatic children, the activation of the eosinophilic response is not solely because of the presence of atopy.

Quantitative analysis of hyperpolarized 3He ventilation changes in mice challenged with methacholine

The capability to use high-resolution (3)He MRI to depict regional ventilation changes and airway narrowing in mice challenged with methacholine (MCh) offers the opportunity to gain new insights into the study of asthma. However, to fully exploit the value of this novel technique, it is important to move beyond visual inspection of the images toward automated and quantitative analysis. To address this gap, we describe a postprocessing approach to create ventilation difference maps to better visualize and quantify regional ventilation changes before and after MCh challenge. We show that difference maps reveal subtle changes in airway caliber, and highlight both focal and diffuse regional alterations in ventilation. Ventilation changes include both hypoventilation and compensatory areas of hyperventilation. The difference maps can be quantified by a histogram plot of the ventilation changes, in which the standard deviation increases with MCh dose (R(2) = 0.89). This method of analysis is shown to be more sensitive than simple threshold-based detection of gross ventilation defects.

Phenotypes of childhood asthma: are they real?

It has been suggested that there are several distinct phenotypes of childhood asthma or childhood wheezing. Here, we review the research relating to these phenotypes, with a focus on the methods used to define and validate them. Childhood wheezing disorders manifest themselves in a range of observable (phenotypic) features such as lung function, bronchial responsiveness, atopy and a highly variable time course (prognosis). The underlying causes are not sufficiently understood to define disease entities based on aetiology. Nevertheless, there is a need for a classification that would (i) facilitate research into aetiology and pathophysiology, (ii) allow targeted treatment and preventive measures and (iii) improve the prediction of long-term outcome. Classical attempts to define phenotypes have been one-dimensional, relying on few or single features such as triggers (exclusive viral wheeze vs. multiple trigger wheeze) or time course (early transient wheeze, persistent and late onset wheeze). These definitions are simple but essentially subjective. Recently, a multi-dimensional approach has been adopted. This approach is based on a wide range of features and relies on multivariate methods such as cluster or latent class analysis. Phenotypes identified in this manner are more complex but arguably more objective. Although phenotypes have an undisputed standing in current research on childhood asthma and wheezing, there is confusion about the meaning of the term 'phenotype' causing much circular debate. If phenotypes are meant to represent 'real' underlying disease entities rather than superficial features, there is a need for validation and harmonization of definitions. The multi-dimensional approach allows validation by replication across different populations and may contribute to a more reliable classification of childhood wheezing disorders and to improved precision of research relying on phenotype recognition, particularly in genetics. Ultimately, the underlying pathophysiology and aetiology will need to be understood to properly characterize the diseases causing recurrent wheeze in children.

Respiratory viral infection in lower airways of asymptomatic children

Aim:  The aim of this study was to determine if asthmatic children have viruses more commonly detected in lower airways during asymptomatic periods than normal children.

Methods:  Fifty‐five asymptomatic children attending elective surgical procedures (14 with stable asthma, 41 normal controls) underwent non‐bronchoscopic bronchoalveolar lavage. Differential cell count and PCR for 13 common viruses were performed.

Results:  Nineteen (35%) children were positive for at least one virus, with adenovirus being most common. No differences in the proportion of viruses detected were seen between asthmatic and normal ‘control’ children. Viruses other than adenovirus were associated with higher neutrophil counts, suggesting that they caused an inflammatory response in both asthmatics and controls (median BAL neutrophil count, 6.9% for virus detected vs. 1.5% for virus not detected, p = 0.03).

Conclusions:  Over one‐third of asymptomatic children have a detectable virus (most commonly adenovirus) in the lower airway; however, this was not more common in asthmatics. Viruses other than adenovirus were associated with elevated neutrophils suggesting that viral infection can be present during relatively asymptomatic periods in asthmatic children.

[Asthma: a disease of the whole bronchial tree]

Inflammation and remodelling are constant features of asthma. They are present throughout the whole bronchial tree, even in the small airways (less than 2 mm). The inflammatory cell infiltrate and structural changes are, in most cases, identical. However, in severe asthma, nocturnal asthma and fatal asthma, the cellular infiltrate in the distal airways is more intense and the number of activated cells is increased. In fatal asthma there are major alterations in the distal airways involving the smooth muscle and the bronchial epithelium, and mucus hypersecretion leading to distal airway plugging. Thus the histopathological changes in the distal airways contribute to the most severe stages of asthma and should be targeted by treatment. Currently the non-invasive tools that reflect inflammation are unable to assess these changes in the distal airways.

A 3-D well-differentiated model of pediatric bronchial epithelium demonstrates unstimulated morphological differences between asthmatic and nonasthmatic cells

There is a need for reproducible and effective models of pediatric bronchial epithelium to study disease states such as asthma. We aimed to develop, characterize, and differentiate an effective, an efficient, and a reliable three-dimensional model of pediatric bronchial epithelium to test the hypothesis that children with asthma differ in their epithelial morphologic phenotype when compared with nonasthmatic children. Primary cell cultures from both asthmatic and nonasthmatic children were grown and differentiated at the air-liquid interface for 28 d. Tight junction formation, MUC5AC secretion, IL-8, IL-6, prostaglandin E2 production, and the percentage of goblet and ciliated cells in culture were assessed. Well-differentiated, multilayered, columnar epithelium containing both ciliated and goblet cells from asthmatic and nonasthmatic subjects were generated. All cultures demonstrated tight junction formation at the apical surface and exhibited mucus production and secretion. Asthmatic and nonasthmatic cultures secreted similar quantities of IL-8, IL-6, and prostaglandin E2. Cultures developed from asthmatic children contained considerably more goblet cells and fewer ciliated cells compared with those from nonasthmatic children. A well-differentiated model of pediatric epithelium has been developed that will be useful for more in vivo like study of the mechanisms at play during asthma.

The validity of induced sputum and bronchoalveolar lavage in childhood asthma

There are a number of useful direct airway sampling procedures to help diagnose and monitor asthma in patients. However, non-invasive techniques are the ideal, especially in children, given the necessity of safe and repeatable measurements to monitor treatment efficacy and disease progression. Bronchoalveolar lavage (BAL) may be too invasive for clinical use in children, while questions still surround the utility of induced sputum (IS). More novel techniques, such as fractional exhaled nitric oxide (FE(NO)) and exhaled breath condensate (EBC), are still unproven. Eosinophilic airway inflammation is a major feature of childhood asthma, and it has been revealed as a major treatment target with inhaled corticosteroids. Moreover, treatment protocols governed by sputum eosinophil counts may be more efficacious - by reducing the frequency and severity of exacerbations - than treatment based on clinical symptoms and other traditional objective measures of lung function. The selection of an appropriate airway inflammation monitoring technique must take everything into consideration, including safety, reproducibility, repeatability, sensitivity to treatment, and the overall clinical/research goals.

15-lipoxygenase metabolites play an important role in the development of a T-helper type 1 allergic inflammation induced by double-stranded RNA

BACKGROUND

We recently demonstrated that the T-helper type 1 (Th1) immune response plays an important role in the development of non-eosinophilic inflammation induced by airway exposure of an allergen plus double-stranded RNA (dsRNA). However, the role of lipoxygenase (LO) metabolites in the development of Th1 inflammation is poorly understood.

OBJECTIVE

To evaluate the role of LO metabolites in the development of Th1 inflammation induced by sensitization with an allergen plus dsRNA.

METHODS

A Th2-allergic inflammation mouse model was created by an intraperitoneal injection of lipopolysaccharide-depleted ovalbumin (OVA, 75 microg) and alum (2 mg) twice, and the Th1 model was created by intranasal application of OVA (75 microg) and synthetic dsRNA [10 microg of poly(I : C)] four times, followed by an intranasal challenge with 50 microg of OVA four times. The role of LO metabolites was evaluated using two approaches: a transgenic approach using 5-LO(-/-) and 15-LO(-/-) mice, and a pharmacological approach using inhibitors of cysteinyl leucotriene receptor-1 (cysLTR1), LTB4 receptor (BLT1), and 15-LO.

RESULTS

We found that the Th1-allergic inflammation induced by OVA+dsRNA sensitization was similar between 5-LO(-/-) and wild-type (WT) control mice, although Th2 inflammation induced by sensitization with OVA+alum was reduced in the former group. In addition, dsRNA-induced Th1 allergic inflammation, which is associated with down-regulation of 15-hydroxyeicosateraenoic acids production, was not affected by treatment with cysLTR1 or BLT1 inhibitors, whereas it was significantly lower in 12/15-LO(-/-) mice compared with WT control mice. Moreover, dsRNA-induced allergic inflammation and the recruitment of T cells following an allergen challenge were significantly inhibited by treatment with a specific 15-LO inhibitor (PD146176).

CONCLUSION

15-LO metabolites appear to be important mediators in the development of Th1-allergic inflammation induced by sensitization with an allergen plus dsRNA. Our findings suggest that the 15-LO pathway is a novel therapeutic target for the treatment of virus-associated asthma characterized by Th1 inflammation.

The natural history of fatal childhood asthma--a case from the Isle of Wight Birth Cohort

Subjects with severe and unstable asthma are at high risk of fatal asthma attack. We describe a case of fatal childhood asthma in an 11-year old girl whose asthma was apparently stable with supranormal lung function and identify additional characteristics that should be considered as increasing the risk for fatal asthma. This opportunity was provided by this girl's participation in the Isle of Wight Whole Population Birth Cohort Study. Prospectively collected data identified her as an early-onset persistent wheezer with significant allergic comorbidity. She was highly atopic with multiple allergen sensitization and a total IgE exceeding 5000 Ku/L (normal range: 0-180 ku/l) at 10 years. Additionally at that age, whilst possessing normal lung function (FEV(1) 2.15 Litres; 110% predicted), she was found to have marked bronchial hyper-responsiveness (PC(20) Methacholine 1.71 mg/ml). At the age of 11 years, despite apparent clinical stability and use of regular controller asthma therapy, she suffered a fatal acute asthma attack that may have been related to acute allergen exposure. This report provides further insight into factors associated with fatal childhood asthma. We propose that highly atopic children with early onset persistent asthma are at a higher risk of fatal asthma even if their asthma is apparently stable and lung function is normal. Marked bronchial hyper-responsiveness provides a clue and should be assessed if there is concern.

Oral prednisolone for preschool children with acute virus-induced wheezing

BACKGROUND

Attacks of wheezing induced by upper respiratory viral infections are common in preschool children between the ages of 10 months and 6 years. A short course of oral prednisolone is widely used to treat preschool children with wheezing who present to a hospital, but there is conflicting evidence regarding its efficacy in this age group.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial comparing a 5-day course of oral prednisolone (10 mg once a day for children 10 to 24 months of age and 20 mg once a day for older children) with placebo in 700 children between the ages of 10 months and 60 months. The children presented to three hospitals in England with an attack of wheezing associated with a viral infection; 687 children were included in the intention-to-treat analysis (343 in the prednisolone group and 344 in the placebo group). The primary outcome was the duration of hospitalization. Secondary outcomes were the score on the Preschool Respiratory Assessment Measure, albuterol use, and a 7-day symptom score.

RESULTS

There was no significant difference in the duration of hospitalization between the placebo group and the prednisolone group (13.9 hours vs. 11.0 hours; ratio of geometric means, 0.90; 95% confidence interval, 0.77 to 1.05) or in the interval between hospital admission and signoff for discharge by a physician. In addition, there was no significant difference between the two study groups for any of the secondary outcomes or for the number of adverse events.

CONCLUSIONS

In preschool children presenting to a hospital with mild-to-moderate wheezing associated with a viral infection, oral prednisolone was not superior to placebo. (Current Controlled Trials number, ISRCTN58363576.)

Wheeze and asthma prevalence and related health-service use in white and south Asian pre-schoolchildren in the United Kingdom

BACKGROUND

Epidemiological data for south Asian children in the United Kingdom are contradictory, showing a lower prevalence of wheeze, but a higher rate of medical consultations and admissions for asthma compared with white children. These studies have not distinguished different asthma phenotypes or controlled for varying environmental exposures.

OBJECTIVE

To compare the prevalence of wheeze and related health-service use in south Asian and white pre-schoolchildren in the United Kingdom, taking into account wheeze phenotype (viral and multiple wheeze) and environmental exposures.

METHODS

A postal questionnaire was completed by parents of a population-based sample of 4366 white and 1714 south Asian children aged 1-4 years in Leicestershire, UK. Children were classified as having viral wheeze or multiple trigger wheeze.

RESULTS

The prevalence of current wheeze was 35.6% in white and 25.5% in south Asian 1-year-olds (P<0.001), and 21.9% and 20.9%, respectively, in children aged 2-4 years. Odds ratios (ORs) (95% confidence interval) for multiple wheeze and for viral wheeze, comparing south Asian with white children, were 2.21 (1.19-4.09) and 1.43 (0.77-2.65) in 2-4-year-olds after controlling for socio-economic conditions, environmental exposures and family history. In 1-year-olds, the respective ORs for multiple and viral wheeze were 0.66 (0.47-0.92) and 0.81 (0.64-1.03). Reported GP consultation rates for wheeze and hospital admissions were greater in south Asian children aged 2-4 years, even after adjustment for severity, but the use of inhaled corticosteroids was lower.

CONCLUSIONS

South Asian 2-4-year-olds are more likely than white children to have multiple wheeze (a condition with many features of chronic atopic asthma), after taking into account ethnic differences in exposure to some environmental agents. Undertreatment with inhaled corticosteroids might partly explain their greater use of health services.

Nonatopic children with multitrigger wheezing have airway pathology comparable to atopic asthma

RATIONALE

Epidemiologic studies have shown that, in atopic children, wheezing is more likely to persist into adulthood, eventually becoming asthma, whereas it appears to resolve by adolescence in nonatopic children.

OBJECTIVES

To investigate whether among children with multitrigger wheeze responsive to bronchodilators the airway pathology would be different in nonatopic wheezers, who are often considered nonasthmatic, compared with atopic wheezers, who are more frequently diagnosed as having asthma.

METHODS

Bronchial biopsies were obtained from 55 children undergoing bronchoscopy for appropriate clinical indications: 18 nonatopic children with multitrigger wheeze (median age, 5 yr; range, 2-10 yr), 20 atopic children with multitrigger wheeze (medan age, 5 yr; range, 2-15 yr), and 17 control children with no atopy or wheeze (median age, 4; range, 2-14 yr). By histochemistry and immunohistochemistry, we quantified epithelial loss, basement membrane thickness, angiogenesis, inflammatory cells, IL-4(+,) and IL-5(+) cells in subepithelium.

MEASUREMENTS AND MAIN RESULTS

Unexpectedly, all pathologic features examined were similar in atopic and nonatopic wheezing children. Compared with control subjects, both nonatopic and atopic wheezing children had increased epithelial loss (P = 0.03 and P = 0.002, respectively), thickened basement membrane (both P < 0.0001), and increased number of vessels (P = 0.003 and P = 0.03, respectively) and eosinophils (P < 0.0001 and P = 0.002, respectively). Moreover, they had increased cytokine expression, which was highly significant for IL-4 (P = 0.002 and P = 0.0001, respectively) and marginal for IL-5 (P = 0.02 and P = 0.08, respectively).

CONCLUSIONS

This study shows that the airway pathology typical of asthma is present in nonatopic wheezing children just as in atopic wheezing children. These results suggest that, when multitrigger wheezing responsive to bronchodilators is present, it is associated with pathologic features of asthma even in nonatopic children.

Natural history of asthma: persistence versus progression-does the beginning predict the end?

Environmental exposures during the early years and airway obstruction that develops during this time, in conjunction with genetic susceptibility, are important factors in the development of persistent asthma in childhood. Established risk factors for childhood asthma include frequent wheezing during the first 3 years, a parental history of asthma, a history of eczema, allergic rhinitis, wheezing apart from colds, and peripheral blood eosinophilia, as well as allergic sensitization to aeroallergens and certain foods. Risk factors for the development of asthma in adulthood remain ill defined. Moreover, reasons for variability in the clinical course of asthma--persistence in some individuals and progression in others--remain an enigma. The distinction between disease persistence and disease progression suggests that these are different entities or phenotypes. There is currently no consensus on whether disease progression requires either airway inflammation or airway remodeling or the combination of the two. For patients with irreversible airway obstruction, inflammation might, in part, be necessary but perhaps not entirely sufficient to induce the irreversible component, some of which could be attributed to alterations in the structure of the bronchial wall. Intervening with intermittent or daily inhaled corticosteroids in high-risk infants and children does not prevent disease progression or impaired lung growth. These findings, however, might not apply to adults, and further study in adults is needed to determine the effect of inhaled corticosteroid therapy on disease progression.

Cord blood hemopoietic progenitor profiles predict acute respiratory symptoms in infancy

Atopy is characterized by eosinophilic inflammation associated with recruitment of eosinophil/basophil (Eo/B) progenitors. We have previously shown that Eo/B progenitor phenotypes are altered in cord blood (CB) in infants at high risk of atopy/asthma, and respond to maternal dietary intervention during pregnancy. As respiratory tract viral infections have been shown to induce wheeze in infancy, we investigated the relationship between CB progenitor function and phenotype and acute respiratory illness (ARI), specifically wheeze and fever. CB from 39 high-risk infants was studied by flow cytometry for CD34(+) progenitor phenotype and by ex vivo Eo/B-colony forming unit (CFU) responses to cytokine stimulation in relation to ARI in the first year of life. A consistent relationship was observed between increased numbers of granulocyte/macrophage (GM)-colony-stimulating factor (CSF)- and IL-3-responsive Eo/B-CFU in CB and the frequency/characteristics of ARI during infancy. Comparable associations were found between ARI and CB IL-3R(+) and GM-CSFR(+)CD34(+) cell numbers. Conversely, a reciprocal decrease in the proportion of CB IL-5R(+) cells was found in relation to the clinical outcomes. The elevation of IL-3/GM-CSF-responsive Eo/B progenitors in high-risk infants in relation to ARI outcomes suggests a mechanism for the increased severity of inflammatory responses in these subjects following viral infection.

How early do airway inflammation and remodeling occur?

Eosinophilic airway inflammation and structural airway changes are present in school age asthmatics. When these changes occur, and their relationship, are controversial. Some structural airway changes, up-regulation of collagens 1 and 111, and increased distance between alveolar tethering points, may be antenatal, and independent of inflammation. We have established that there is no eosinophilic inflammation or reticular basement membrane thickening in wheezing infants median age one year; but by age three years, both are present. This accords with cohort studies, showing that children who become persistent wheezers have a drop in lung function in the pre-school years. Thereafter, lung function tracks into middle age, so the preschool years represent window during which an intervention might have long term benefit. Supportive are measurements in blood and bronchoalveolar lavage fluid, implicating the neutrophil as the key inflammatory cell in early wheeze. Models of the pathophysiology of asthma include (1) that eosinophilic inflammation is the primary event, and leads to remodelling as a secondary event, which itself results in progressive airflow obstruction (the least likely model); (2) eosinophilic inflammation is the primary event, but remodelling is protective, preventing worsening AHR. It should be noted that these first two are not mutually exclusive; rbm thickening may be protective, but other components of remodeling, for example increased ASM, may have adverse effects; (3) eosinophilic inflammation and airway remodelling are parallel processes, driven by some underlying 'asthma factor'; and (4) the primary abnormality is not airway inflammation, but some form of disordered airway repair.

Two main subtypes of wheezing illness? Evidence from the 2004 Aberdeen schools asthma survey

To compare risk factors for wheezy bronchitis (WB) and multi-trigger wheeze (MTW) in pre-pubertal children along the spectrum of disease severity. Cross-sectional survey of children aged 7-12 yr in Aberdeen city primary schools in 2004 using parent-completed questionnaires as used in surveys in 1964, 1989, 1994, and 1999. Children were grouped into five categories: no wheeze in the past three years, non-severe wheeze triggered only by a cold (non-severe WB), non-severe wheeze triggered by other factors (non-severe MTW), severe WB, or severe MTW. Severe wheeze was defined as greater than four wheezing attacks, greater than or equal to one disturbed night per week, or speech limitation in the last 12 months. Questionnaires were returned by 3271 children (57.3%), of whom 7.4% had WB (6.1% non-severe and 1.3% severe) and 17.2% had MTW (9.4% non-severe and 7.8% severe). Severe disease was more frequent in children with MTW (31.8%) than in those with WB (5.1%). Whereas the prevalence of MTW had increased since 1964, the prevalence of WB had remained stable over this period. After adjustment for confounders, age had no influence on either wheeze type, and male sex was only associated with non-severe WB [OR 1.44, 95% confidence intervals (1.03-2.02)]. In the WB group eczema or/and hay fever in the child were more strongly associated with severe wheeze [OR 3.28(1.49-7.23) vs. OR 1.84(1.31-2.60)]. In the MTW group, this association was noticeably higher than in the WB group, but did not differ much between non-severe and severe wheeze [OR 5.46(3.70-7.20) and OR 6.01(4.1-8.75) respectively]. The presence of any allergic diseases in either parent increased the odds for non-severe and severe MTW at the same level of magnitude [OR 1.92(1.38-2.68) and OR 1.92(1.34-2.76) respectively], and statistically non-significantly for severe WB [OR 1.75(0.78-3.94)]. Living in a deprived area increased both severe WB and severe MTW, reaching statistical significance only for severe MTW [OR 1.96(1.39-2.78)]. Smoking in the house was associated with increased risk of WB and MTW of any severity. WB and MTW differ in prevalence trends and severity. Within severity levels, the influence of age, allergic diseases in children and parents also differed between these two wheezing subtypes.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

Exhaled breath condensate pH in infants and children with acute and recurrent wheezy bronchitis

The analysis of exhaled breath condensate (EBC) is a promising new method to measure airway inflammation. So far only limited data exist about methodological issues of EBC sampling in infants and young children. We evaluated 18 children with acute wheezy bronchitis (median age 24.3 months (min-max: 4-89.9)), 54 children with recurrent wheezy bronchitis (median age 52.5 months (7.2-94.8)), and 32 healthy controls (median age 49.6 months (25.3-67.8)). EBC was sampled with a modified commercially available EBC-sampler, pH was measured after deaeration. EBC volume was significantly correlated to age (r = 0.56, P < 0.001). EBC pH was significantly decreased in all patients compared to the healthy controls (acute wheezy bronchitis 7.87 (7.16-8.19), P = 0.003, recurrent wheezy bronchitis 7.86 (6.95-8.39), P = 0.002, and healthy controls 8.04 (7.81-8.87), respectively). There were no significant differences of the EBC pH between the disease groups. When divided into different subgroups, an influence of inhaled steroid treatment was found with steroid-naive recurrent wheezers having significantly lower EBC pH levels compared to healthy controls (7.80 (6.95-8.37), P = 0.018), but not so steroid treated (7.94 (7.24-8.39), P = 0.055). Both, recurrent wheezers with or without a positive allergy test had significantly lower EBC pH compared to healthy controls (7.91 (6.95-8.37), P = 0.007 and 7.82 (7.32-8.39), P = 0.005, respectively). This study indicates that EBC can be collected with a modified commercially available EBC sampler in infants and young children. Further studies need to be performed to evaluate the relevance and meaning of pH differences of EBC in this age group.