The association between persistent eosinophilia and asthma in childhood is independent of atopic status

Bacteria and viruses and their role in the preschool wheeze to asthma transition

Wheezing is the cardinal symptom of asthma; its presence early in life, mostly caused by viral infections, is a major risk factor for the establishment of persistent or recurrent disease. Early-life wheezing and asthma exacerbations are triggered by common respiratory viruses, mainly rhinoviruses (RV), and to a lesser extent, respiratory syncytial virus, parainfluenza, human metapneumovirus, coronaviruses, adenoviruses, influenza, and bocavirus. The excess presence of bacteria, several of which are part of the microbiome, has also been identified in association with wheezing and acute asthma exacerbations, including haemophilus influenza, streptococcus pneumoniae, moraxella catarrhalis, mycoplasma pneumoniae, and chlamydophila pneumonia. While it is not clear when asthma starts, its characteristics develop over time. Airway remodeling already appears between the ages of 1 and 3 years of age even prior to the presence of atopic inflammation or an asthma diagnosis. The role of genetic defect or variations hampering the airway epithelium in response to environmental stimuli and severe disease morbidity are now considered as major determinants for early structural changes. Repeated viral infections can induce and perpetuate airway hyperresponsiveness. Allergic sensitization, that often precedes infection-induced wheezing, shifts inflammation toward type-2, while common respiratory infections themselves promote type-2 inflammation. Nevertheless, most children who wheeze with viral infections during infancy and during preschool years do not develop persistent asthma. Multiple factors, including illness severity, viral etiology, allergic sensitization, and the exposome, are associated with disease persistence. Here, we summarize current knowledge and developments in infection epidemiology of asthma in children, describing the known impact of each individual agent and mechanisms of transition from recurrent wheeze to asthma.

Limited clinical role of blood eosinophil levels in early life atopic disease: A mother-child cohort study

BACKGROUND

Blood eosinophil count is a well-established biomarker of atopic diseases in older children and adults. However, its predictive role for atopic diseases in preschool children is not well established.

OBJECTIVE

To investigate the association between blood eosinophil count in children and development of atopic diseases up to age 6 years.

METHODS

We investigated blood eosinophil count at age 18 months and 6 years in relation to recurrent wheeze/asthma, atopic dermatitis, allergic rhinitis, and allergic sensitization during the first 6 years of life in the two Copenhagen Prospective Studies on Asthma in Childhood cohorts (n = 1111). Blood eosinophil count was investigated in association with remission of existing atopic disease, current atopic disease, and later development of atopic disease.

RESULTS

Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis, while blood eosinophil count at age 6 years was associated with increased occurrence of current wheezing/asthma (OR = 1.1; 1.04-1.16, p = .0005), atopic dermatitis (OR = 1.06; 1.01-1.1, p = .02), and allergic rhinitis (OR = 1.11; 1.05-1.18, p = .0002). Blood eosinophil count at 18 months did not predict persistence or development of recurrent wheeze/asthma or atopic dermatitis at age 6 years.

CONCLUSION

Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis and did not predict persistence or development of disease. This implies a limited clinical role of blood eosinophil levels in early-life atopic disease and questions the clinical value of blood eosinophil counts measured in toddlers as a predictive biomarker for subsequent atopic disease in early childhood.

Early Prediction of Asthma

The clinical manifestations of asthma in children are highly variable, are associated with different molecular and cellular mechanisms, and are characterized by common symptoms that may diversify in frequency and intensity throughout life. It is a disease that generally begins in the first five years of life, and it is essential to promptly identify patients at high risk of developing asthma by using different prediction models. The aim of this review regarding the early prediction of asthma is to summarize predictive factors for the course of asthma, including lung function, allergic comorbidity, and relevant data from the patient's medical history, among other factors. This review also highlights the epigenetic factors that are involved, such as DNA methylation and asthma risk, microRNA expression, and histone modification. The different tools that have been developed in recent years for use in asthma prediction, including machine learning approaches, are presented and compared. In this review, emphasis is placed on molecular mechanisms and biomarkers that can be used as predictors of asthma in children.

Performance of Three Asthma Predictive Tools in a Cohort of Infants Hospitalized With Severe Bronchiolitis

Childhood asthma develops in 30–40% of children with severe bronchiolitis but accurate prediction remains challenging. In a severe bronchiolitis cohort, we applied the Asthma Predictive Index (API), the modified Asthma Predictive Index (mAPI), and the Pediatric Asthma Risk Score (PARS) to predict asthma at age 5 years. We applied the API, mAPI, and PARS to the 17-center cohort of infants hospitalized with severe bronchiolitis during 2011–2014 (35th Multicenter Airway Research Collaboration, MARC-35). We used data from the first 3 years of life including parent interviews, chart review, and specific IgE testing to predict asthma at age 5 years, defined as parent report of clinician-diagnosed asthma. Among 875/921 (95%) children with outcome data, parent-reported asthma was 294/875 (34%). In MARC-35, a positive index/score for stringent and loose API, mAPI, and PARS were 24, 68, 6, and 55%, respectively. The prediction tools' AUCs (95%CI) ranged from 0.57 (95%CI 0.54–0.59) to 0.68 (95%CI 0.65–0.71). The positive likelihood ratios were lower in MARC-35 compared to the published results from the original cohorts. In this high-risk population of infants hospitalized with severe bronchiolitis, API, mAPI, and PARS had sub-optimal performance (AUC <0.8). Highly accurate (AUC >0.8) asthma prediction tools are desired in infants hospitalized with severe bronchiolitis.

Predictive value of childhood airway hyper-responsiveness to indirect stimuli: 10-year longitudinal study

BACKGROUND

Airway hyper-responsiveness (AHR) is a common feature in asthma. The use of AHR in predicting active asthma or the persistence of AHR in childhood is poorly understood. By analyzing longitudinal connections including different measures of AHR, lung function, and inflammation markers, we sought to identify the best available method for predicting persistence of AHR and identification of later active asthma.

METHODS

We tested 105 asthmatic children aged 3-7 years with fractional exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and AHR evaluated by indirect methods (hypertonic saline and exercise challenge). Ten years later, 64 children participated in the follow-up visit and were tested with FeNO, IOS, spirometry, and methacholine challenge. At both study visits, blood samples were collected, and a questionnaire was completed.

RESULTS

Asthma was in remission in 66% of patients at adolescence. AHR measured by hypertonic saline challenge at preschool age was associated with asthma symptoms (OR 10.2; 95% CI 2.8, 37.3) but not with AHR estimated with methacholine challenge 10 years later. AHR measured by exercise challenge was not associated with AHR or recent asthma symptoms in adolescence. Preschool eosinophilia continued until adolescence in 87% of patients but was not associated with AHR or subjective signs of asthma 10 years later. Wheezy preschoolers with atopy had a higher risk for AHR in adolescence (OR 4.1; 95% CI 1.0, 16.2).

CONCLUSION

Results from hypertonic saline challenge are associated with persistent asthma symptoms even after a decade. AHR measured by indirect methods at preschool age did not predict AHR in adolescence.

Considerations for the Child with Nonatopic Asthma

Asthma guidelines provide clinicians with evidence-based management strategies for this chronic condition. The preferred therapy for patient with persistent asthma is inhaled corticosteroids. However, ∼40% of the patients with persistent asthma continue to present with symptoms while treated according to the guidelines. Multiple factors are being explored to explain the variability in response to inhaled corticosteroids including asthma phenotype and genetic predisposition among others. The nonatopic asthma phenotype has been described in the literature. These patients tend to have milder symptoms of asthma and typically outgrow their asthma by adolescence. They present with chronic asthma symptoms in the absence of a positive allergy test, either skin prick test or specific immunoglobulin E blood test. Although patients with nonatopic asthma share many characteristics with patients with atopic asthma, there are several studies that suggest a different inflammatory pathway may be involved in their pathophysiology. Therefore, it is possible that children with nonatopic asthma could respond differently to inhaled corticosteroids compared with those with atopic asthma. Currently there is a variable definition of this phenotype. Furthermore, there is a paucity of therapeutic trial directed toward the patients with nonatopic asthma specifically. Future research should be guided toward identifying the inflammatory pathways in nonatopic asthma and potential phenotype-guided therapies.

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.

Predicting Asthma Using Clinical Indexes

Asthma is no longer considered a single disease, but a common label for a set of heterogeneous conditions with shared clinical symptoms but associated with different cellular and molecular mechanisms. Several wheezing phenotypes coexist at preschool age but not all preschoolers with recurrent wheezing develop asthma at school-age; and since at the present no accurate single screening test using genetic or biochemical markers has been developed to determine which preschooler with recurrent wheezing will have asthma at school age, the asthma diagnosis still needs to be based on clinical predicted models or scores. The purpose of this review is to summarize the existing and most frequently used asthma predicting models, to discuss their advantages/disadvantages, and their accomplishment on all the necessary consecutive steps for any predictive model. Seven most popular asthma predictive models were reviewed (original API, Isle of Wight, PIAMA, modified API, ucAPI, APT Leicestersher, and ademAPI). Among these, the original API has a good positive LR~7.4 (increases the probability of a prediction of asthma by 2-7 times), and it is also simple: it only requires four clinical parameters and a peripheral blood sample for eosinophil count. It is thus an easy model to use in any rural or urban health care system. However, because its negative LR is not good, it cannot be used to rule out the development of asthma.

Non-atopic rhinitis at age 6 is associated with subsequent development of asthma

BACKGROUND

It has been postulated that the association between allergic rhinitis and asthma is attributable to the progressive clinical expression of respiratory inflammation during childhood. The role of non-allergic rhinitis in early life in relation to subsequent asthma has not been extensively explored.

OBJECTIVE

We sought to determine whether rhinitis in early life was associated with risk of asthma development into adulthood, and whether this relationship is independent of allergic sensitization.

METHODS

Participants were identified from the Tucson Children's Respiratory Study, a non-selected birth cohort. Allergy skin prick testing was performed at age 6 years using house dust mix, Bermuda, mesquite, olive, mulberry, careless weed, and Alternaria aeroallergens. Atopy was defined as ≥1 positive tests. Physician-diagnosed active asthma from age 6 to 32 and physician-diagnosed rhinitis at age 6 were determined by questionnaire. Participants with asthma or active wheezing at age 6 were excluded from analyses. Risk estimates were obtained with Cox regression.

RESULTS

There were 521 participants who met inclusion criteria. The hazard ratio for subsequently acquiring a diagnosis of asthma between the ages of 8 and 32 for those with non-atopic rhinitis was 2.1 (95% CI: 1.2, 3.4, P = 0.005), compared with the non-atopic no rhinitis group, after adjusting for sex, ethnicity, maternal asthma, maternal education and smoking, and history of 4+ colds per year at age 6. Among the atopic participants, both the active and no rhinitis groups were more likely to develop and have asthma through age 32. The relation between non-atopic rhinitis and asthma was independent of total serum IgE levels at age 6.

CONCLUSION AND CLINICAL RELEVANCE

Childhood rhinitis, even in the absence of atopy, confers significant risk for asthma development through adulthood. These findings underscore the importance of non-allergic mechanisms in the development of asthma.

Severe bronchiolitis profiles and risk of recurrent wheeze by age 3 years

BACKGROUND

A better understanding of bronchiolitis heterogeneity might help clarify its relationship with the development of recurrent wheezing and asthma.

OBJECTIVES

We sought to identify severe bronchiolitis profiles using a clustering approach and to investigate for the first time their association with allergy/inflammatory biomarkers, nasopharyngeal microbiota, and development of recurrent wheezing by age 3 years.

METHODS

We analyzed data from a prospective, 17-center US cohort study of 921 infants (age <1 year) hospitalized with bronchiolitis (2011-2014 winters) with posthospitalization follow-up. Severe bronchiolitis profiles at baseline (hospitalization) were determined by using latent class analysis based on clinical factors and viral etiology. Blood biomarkers and nasopharyngeal microbiota profiles were determined by using samples collected within 24 hours of hospitalization. Recurrent wheezing by age 3 years was defined based on parental report of breathing problem episodes after discharge.

RESULTS

Three severe bronchiolitis profiles were identified: profile A (15%), which was characterized by a history of breathing problems/eczema during infancy and non-respiratory syncytial virus (mostly rhinovirus) infection; profile B (49%), which has the largest probability of respiratory syncytial virus infection and resembled classic respiratory syncytial virus-induced bronchiolitis; and profile C (36%), which was composed of the most severely ill group. Profile A infants had higher eosinophil counts, higher cathelicidin levels, and increased proportions of Haemophilus-dominant or Moraxella-dominant microbiota profiles. Compared with profile B, we observed significantly increased risk of recurrent wheezing in children with profile A (hazard ratio, 2.64; 95% CI, 1.90-3.68) and, to a lesser extent, with profile C (hazard ratio, 1.51; 95% CI, 1.14-2.01).

CONCLUSION

Although longer follow-up is needed, our results might help identify, among children hospitalized for bronchiolitis, subgroups with particularly increased risk of asthma.

The absence of serum IgE antibodies indicates non-type 2 disease in young asthmatics

BACKGROUND

Atopic asthma is associated with elevated type-2 biomarkers such as fraction of exhaled nitric oxide (FeNO) and blood eosinophil (B-Eos) count. However, increased type 2 markers have also been reported in traditionally defined non-atopic asthma.

OBJECTIVE

To determine a clinically useful level of IgE sensitization for ruling out type 2 asthma.

METHODS

Asthmatics (N = 408; age 10-35 years) were analysed using the multi-allergen tests Phadiatop and fx5 (ImmunoCAP). Subjects were grouped based on IgE-antibody concentrations: ≥0.35 kU_A /L for at least one test (n = 326) or <0.35 kU_A /L for both tests (n = 82). Τhe latter group was subsequently divided into 2 groups: IgE 0.10-0.34 kU_A /L (n = 34) and IgE < 0.10 kU_A /L (n = 48). The relationships between type 2 biomarkers, and inadequate asthma control (ACT < 20), reduced lung function (FEV₁  < 80%), recent asthma attacks and airway hyperresponsiveness (AHR) to methacholine were determined.

RESULTS

In univariate analyses, at least one type 2 marker related to each asthma outcome in subjects with IgE ≥0.35 kU_A /L. In subjects with IgE 0.10-0.34 kU_A /L, elevated FeNO related to reduced lung function (P = .008) and B-Eos to AHR (P = .03). No associations were found in subjects with IgE < 0.10 kU_A /L. In multivariate analysis, a relationship between FeNO and reduced lung function remained in subjects with IgE < 0.35 kU_A /L (P = .03).

CONCLUSION AND CLINICAL RELEVANCE

Clinically relevant elevation of type 2 biomarkers was seen in young asthmatics with IgE antibodies <0.35 kU_A /L, but not those with IgE < 0.10 kU_A /L. It seems possible to define non-type 2 asthma through sensitive IgE-antibody measurement.

Current and future management of the young child with early onset wheezing

PURPOSE OF REVIEW

In this review, we discuss current thinking in relation to available guidelines for the care of preschool-aged children with recurrent wheezing, while highlighting the gaps in our knowledge and discussing changes that could occur over the next 5 years.

RECENT FINDINGS

The Asthma Predictive Index as well as allergen-specific IgE, peripheral eosinophil count and exhaled nitric oxide are perhaps underutilized sources of information that can assist in predicting progression to asthma and response to therapies. Inhaled corticosteroids and leukotriene receptor antagonists decrease impairment and exacerbation frequency in wheezing children but are not disease modifying. Macrolides may be useful during acute wheezing episodes for preventing progression to more severe symptoms. Monoclonal antibodies targeting IgE and TH2 cytokines have been successful in trials of adults and older children with asthma, but trials in younger children are needed.

SUMMARY

Establishing the phenotype and endotype of young wheezing children can be useful for prognostication of future asthma risk as well as for selection of the most appropriate treatment. Primary asthma prevention strategies are needed during the critical developmental window in early life prior to the onset of irrecoverable loss of lung function.

Humoral immune factors and asthma among American Indian children: a case-control study

Background

Asthma is recognized as intimately related to immunologic factors and inflammation, although there are likely multiple phenotypes and pathophysiologic pathways. Biomarkers of inflammation may shed light on causal factors and have potential clinical utility. Individual and population genetic factors are correlated with risk for asthma and improved understanding of these contributions could improve treatment and prevention of this serious condition.

Methods

A population-based sample of 108 children with clinically defined asthma and 216 control children were recruited from a small community in the northern plains of the United States. A complete blood count, high sensitivity C-reactive protein, total IgE and specific antibodies to 5 common airborne antigens (CAA), in addition to basic demographic and anthropomorphic data were obtained. Logistic regression was primarily used to determine the association between these humoral factors and risk of asthma.

Results

The body mass index (BMI) of those with asthma and their total leukocyte counts, percentage of eosinophils, and levels of total IgE were all greater than corresponding control values in univariate analysis. The presence of detectable, specific IgE antibodies to five common airborne antigens was more likely among cases compared with controls. In multivariate analysis, total IgE was independently associated with asthma; but not after inclusion of a cumulative measure of specific IgE sensitization.

Conclusion

Many previously reported associations between anthropomorphic and immune factors and increased risk of asthma appear to be also present in this American Indian population. In this community, asthma is strongly associated with sensitization to CAA.

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

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

Biomarkers to predict asthma in wheezing preschool children

Wheezing in preschool children is a very common symptom. An adequate prediction of asthma in these children is difficult and cannot be reliably assessed with conventional clinical tools. The study of potential predictive biomarkers in various media, ranging from invasive sampling (e.g. bronchoscopy) to non-invasive sampling (lung function testing and exhaled breath analysis), was comprehensively reviewed. The evolution in biomarker discovery has resulted in an 'omics' approach, in which hundreds of biomarkers in the field of genomics, proteomics, metabolomics, and 'breath-omics' can be simultaneously studied. First, results on gene expression and exhaled breath profiles in predicting an early asthma diagnosis are promising. However, many hurdles need to be overcome before clinical implementation is possible. To reliably predict asthma in a wheezing child, probably a holistic approach is needed, combining clinical information with blood sampling, lung function tests, and potentially exhaled breath analysis. The further development of predictive, non-invasive biomarkers may eventually improve an early asthma diagnosis in wheezing preschool children and assist clinicians in early treatment decision-making.

Low eosinophils during bronchiolitis in infancy are associated with lower risk of adulthood asthma

BACKGROUND

Infant bronchiolitis may be the first manifestation of asthma.

AIM

To evaluate the association of early-childhood risk or protective factors for asthma and lung function reduction in adults 30 years after bronchiolitis in infancy.

METHODS

Forty-seven former bronchiolitis patients attended the clinical study at the median age of 29.5 years, including doctoral examination and measurement of post-bronchodilator lung function with flow-volume spirometry. Data on early-life risk factors including blood eosinophil counts on admission for bronchiolitis and on convalescence 4-6 weeks after bronchiolitis were available.

RESULTS

Low blood eosinophil count <0.25 × 10E9/l on admission for bronchiolitis was a significant protective factor and high blood eosinophil count >0.45 × 10E9/l on convalescence was a significant risk factor for asthma in adulthood independently from atopic status in infancy. Parental asthma and high blood eosinophil count >0.45 × 10E9/l during bronchiolitis were significant risk factors for irreversible airway obstruction (FEV1/FVC ratio below the 5th percentile lower limit of normality after bronchodilation).

CONCLUSION

Our adjusted analyses confirmed that eosinopenia during infant bronchiolitis predicted low asthma risk and eosinophilia outside infection predicted high asthma risk up to the age of 28-31 years. Parental asthma and eosinophilia during bronchiolitis were recognized as risk factors for irreversible airway obstruction.

Maternal pregnancy weight gain and cord blood iron status are associated with eosinophilia in infancy

OBJECTIVE

Allergic disease is multifactorial in origin. Because iron nutrition affects immune responses and maternal pregnancy weight gain impairs fetal iron delivery while increasing fetal demands for growth, the study examined maternal pregnancy weight gain, newborn iron status and an index of atopic disease, infant eosinophilia.

STUDY DESIGN

Within a larger prospective study of healthy newborns at risk for developing iron deficiency anemia, umbilical cord iron indicators were compared to infant eosinophil counts.

RESULT

Infants who developed eosinophilia exhibited higher cord reticulocyte-enriched zinc protoporphyrin/heme ratio, P<0.05 and fewer cord ferritin values in the highest (best) quartile, P<0.05. If cord ferritin was in the upper three quartiles, the negative predictive value for infant eosinophilia was 90%. High maternal pregnancy weight gain predicted infant eosinophil counts, P<0.04, and contributed to cord ferritin predicting eosinophilia, P<0.003.

CONCLUSION

Poor fetal iron status may be an additional risk factor for infant eosinophilia.

Decreased levels of lipoxin A4 and annexin A1 in wheezy infants

OBJECTIVE

Wheezing is a common and challenging health issue in infancy and early childhood. Asthma diagnosis is frequent in patients with a history of recurrent wheezing. A relationship has been reported between asthma and anti-inflammatory mediators such as lipoxin A4 and annexin A1. However, this remains uncertain in wheezy infants. The aim of the present study was to determine lipoxin A4 and annexin A1 levels in wheezy infants.

MATERIALS AND METHODS

Eighty-seven patients aged 6-36 months were included in this study. Demographic characteristics, clinical features, laboratory data, clinical diagnoses, and treatments, if present, were recorded. Patients were divided into 2 groups: patients with wheezing (n = 59) and healthy controls (n = 28). Blood samples were taken and lipoxin A4 and annexin A1 levels were evaluated by ELISA.

RESULTS

Lipoxin A4 and annexin A1 levels were significantly lower in the wheezing group than in the control group (p < 0.05). A significant correlation was found between the serum total immunoglobulin E (IgE) level and the percentage and absolute number of eosinophils (p < 0.05). No significant correlation was found in terms of lipoxin A4 and annexin A1 levels, the serum total IgE level, and the percentage and absolute number of eosinophils among groups (p > 0.05).

CONCLUSION

This is the first study to assess lipoxin A4 and annexin A1 levels in wheezy infants. The levels of lipoxin A4 and annexin A1 were found to be low in wheezy infants. We hope that these results will lead to novel therapeutic options for asthma in cases where an optimal treatment modality is lacking.

The Asthma Predictive Index: a very useful tool for predicting asthma in young children

Recurrent wheezing is a common problem in young children: approximately 40% of children wheeze in their first year of life. However, only 30% of preschoolers with recurrent wheezing still have asthma at the age of 6 years. Nevertheless, asthma, the most prevalent chronic disease in children, is difficult to diagnose in infants and preschoolers. This article reviews the importance of determining at an early age which infants/preschoolers will have asthma later in life, analyzes the pros and cons of different predictive indices, and discusses the efficacy of the Asthma Predictive Index.

Response to budesonide among atopic and non-atopic infants/preschoolers with recurrent wheezing

BACKGROUND

The treatment in non-atopic young children with recurrent wheezing remains controversial.

OBJECTIVE

The aim of the study was to compare the response of inhaled budesonide in atopic versus non-atopic infants/preschoolers with recurrent wheezing (more than three episodes in the last year or one episode per month in the last three months).

METHODS

One hundred and seventy three infants/preschoolers (mean age 1.58+/-0.9 yrs) with recurrent wheezing without previous use of inhaled corticosteroids were enrolled and divided into two categories: atopics (eosinophils in peripheral blood > or =4%) and non-atopics (<4%). Both groups were treated with budesonide (200 mcg bid delivered by MDI and spacer) for three months. The primary outcome was the prevalence of wheezing exacerbation episodes at the end of the treatment.

RESULTS

Thirty-seven out of 173 (21.4%) were atopics and they were significantly younger, more frequently with a father with asthma, maternal grandparents with asthma and rhinitis, paternal and maternal grandparents with eczema, and higher number of wheezing episodes in the last year than non-atopics. At the end of the study, among those with good compliance (>70% of the weekly doses), the proportion of wheezing episodes were similar among atopics and non-atopics (57.7% vs. 44.1%, p=0.25, respectively); the number of exacerbations requiring emergency department (ED) visits and hospital admission were also similar.

CONCLUSION

Regular budesonide therapy may decrease the episodes of wheezing in infants/preschoolers with recurrent wheezing, independently of atopy.

Bronchiolitis: age and previous wheezing episodes are linked to viral etiology and atopic characteristics

BACKGROUND

: Diagnostic criteria for bronchiolitis are variable.

OBJECTIVE

: To study how the risk factors for recurrent wheezing and asthma vary by different definitions of bronchiolitis.

METHODS

: Viral etiology and atopic characteristics were studied in 259 hospitalized wheezing children (median age, 14 months; range, 0-36 months). The data were analyzed according to age (<6, <12, <24 and <36 months) and whether they had a history or no history of a previous wheezing episode. Sixteen viruses were detected by conventional and molecular methods. Atopic characteristics included the presence of eczema, specific and total IgE responses, blood eosinophil count, and modified asthma predictive index.

RESULTS

: Evidence of respiratory virus infection was found in 93% of the cases and allergic sensitization in 26% of the cases. Rhinovirus infections and atopic characteristics (sensitization, blood eosinophil count, and modified asthma predictive index) increased by age and were significantly more common in children with recurrent wheezing episodes than in first-time wheezers in age categories of <24 and <36 months (P < 0.05 for all).

CONCLUSIONS

: In children with bronchiolitis, 2 clinical factors, age and number of previous wheezing episodes, are linked to inflammatory (atopy-related factors) and virologic risk factors of asthma (rhinovirus-associated disease). According to current US and UK guidelines, bronchiolitis includes wheezing children <24 months of age. Our observations suggest that the clinical definition should include only children with their first episode of wheezing.

Lack of eosinophilia can predict remission in wheezy infants?

BACKGROUND

Early wheezing in infants is a potential risk factor for persistence of asthma into adulthood. Moreover, a personal or familial history of atopy are risk factors associated with persistence of pre-existing wheezing during childhood. However, their relative importance remains unclear.

OBJECTIVES

Firstly to determine the critical thresholds of common biological markers of atopy in wheezy infants associated with persistence of wheezing into childhood and secondly to rank these biological markers together with clinical parameters according to the strength of their association with wheezing persistence.

METHODS

A cohort of infants less than 30 months old with recurrent wheezing was established in order to assess severity of respiratory symptoms and to look for the presence of atopy. At the age of 6 years, they were re-evaluated regarding remission of wheezing over the previous 12-months period.

RESULTS

Data were available for 219 subjects. In 27% of them, wheezing persisted at 6 years of age. Critical biological thresholds associated with the risk of wheezing persistence were: (1) a blood eosinophilia count >or=470/mm(3) (defining eosinophilia), and (2) a total serum IgE level >or=45 IU/mL (defining elevated IgE) during infancy. A multiple component factorial analysis identified a dimension associating eosinophilia, elevated IgE and allergic sensitization on the one hand with persistent wheezing at 6 years of age on the other (lambda=0.15). According to a segmentation analysis, the main discriminative parameter of wheezing persistence was eosinophilia. Thus a lack of eosinophilia alone could account for 91% of infants in remission, and when combined with absence of allergic sensitization, remission was correctly discriminated in 96.9% of the study population.

CONCLUSION

Our data strongly suggest that the lack of eosinophilia in wheezy infants without ongoing infection could predict future remission of wheezing in a large majority of cases.

Eosinophilic airway inflammation and the prognosis of childhood asthma

BACKGROUND

Eosinophilic airway inflammation is a key pathophysiological feature of asthma that can predict treatment response. However, the prognostic value of sputum eosinophilia is not established.

OBJECTIVE

The aim of this study was to determine the influence of induced sputum eosinophilia on the prognosis of childhood asthma.

METHODS

A cohort of children with asthma was evaluated by induced sputum analysis at inception and classified as having either eosinophilic asthma (EA) (sputum eosinophils >2.5%) or non-eosinophilic asthma (NEA). After a mean follow-up period of 5 years, eligible subjects (n=83) were contacted and 69 subjects (33 EA, 36 NEA) evaluated. The children had a mean age of 15.9 years, and 61% were male.

RESULTS

Children with EA reported more wheeze during the follow-up period (27% vs. 6% wheezed most years; P<0.0001), increased night waking during the past 12 months (28% vs. 3% reported weekly waking; P=0.01), and greater impairment of quality of life due to asthma (P=0.04). Subsequent beta2-agonist use was increased in children with EA (P=0.02), although there was no difference in corticosteroid use. In EA, subsequent forced expiratory volume in 1 s/forced vital capacity was lower (79% vs. 86%; P=0.01) and grass pollen allergy was more prevalent (77% vs. 27%; P=0.006).

CONCLUSION

In children, eosinophilic airway inflammation is associated with deteriorating asthma over time. This is consistent with the hypothesis that airway inflammation has an adverse impact on the prognosis of childhood asthma, and suggests a role for monitoring inflammation in asthma management.

Wheezy babies--wheezy adults? Review on long-term outcome until adulthood after early childhood wheezing

Population-based birth cohort studies have documented that about 30% of children suffer from wheezing during respiratory infection before their third birthday. Recurrent wheezing is common in early childhood, but most patients outgrow their symptoms by school age. However, recent long-term postbronchiolitis follow-up studies from Sweden and Finland have revealed that asthma is present in about 40% of young adults and over half of the cases are relapses after many symptom-free years. In population studies, the principal predictors for later asthma have been parental asthma, recurrent wheezing, atopy and eosinophilia. In the Swedish postbronchiolitis study, atopic diathesis through the development of clinical atopy, and early passive smoking through bronchial hyper-reactivity or later active smoking led to adult asthma. The Finnish postbronchiolitis follow-up stressed early recurrence of wheezing, wheezing induced by less invasive viruses than respiratory syncytial virus (RSV), early-life atopy and eosinophilia and parental asthma as predictors for adult asthma.

CONCLUSION

The majority of wheezing infants and children outgrow their symptoms by school age, but based on recent long-term follow-up studies, asthma relapses are common in young adults. These studies have highlighted parental asthma, maternal smoking and wheezing induced by other viruses than RSV as predictive factors for later asthma.

Examining the hygiene hypothesis: the Trial of Infant Probiotic Supplementation

The hygiene hypothesis suggests that the absence of infectious exposure at a critical point in immune system development leads to a greater risk for the later development of atopic disease. As a result, it may be possible to devise strategies that can block the onset of atopic diseases such as asthma. This paper outlines the rationale, background and design for the Trial of Infant Probiotic Supplementation study, which is designed to test the effectiveness of a daily infant probiotic supplement in the first 6 months of life in preventing the development of early markers of asthma.

Childhood asthma after bacterial colonization of the airway in neonates

BACKGROUND

Pathological features of the airway in young children with severe recurrent wheeze suggest an association between bacterial colonization and the initiating events of early asthma. We conducted a study to investigate a possible association between bacterial colonization of the hypopharynx in asymptomatic neonates and later development of recurrent wheeze, asthma, and allergy during the first 5 years of life.

METHODS

The subjects were children from the Copenhagen Prospective Study on Asthma in Childhood birth cohort who were born to mothers with asthma. Aspirates from the hypopharyngeal region of asymptomatic 1-month-old infants were cultured for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Wheeze was monitored prospectively on diary cards during the first 5 years of life. Blood eosinophil count and total IgE and specific IgE were measured at 4 years of age. Lung function was measured and asthma was diagnosed at 5 years of age.

RESULTS

Hypopharyngeal samples were cultured from 321 neonates at 1 month of age. Twenty-one percent of the infants were colonized with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms; colonization with one or more of these organisms, but not colonization with S. aureus, was significantly associated with persistent wheeze (hazard ratio, 2.40; 95% confidence interval [CI], 1.45 to 3.99), acute severe exacerbation of wheeze (hazard ratio, 2.99; 95% CI, 1.66 to 5.39), and hospitalization for wheeze (hazard ratio, 3.85; 95% CI, 1.90 to 7.79). Blood eosinophil counts and total IgE at 4 years of age were significantly increased in children colonized neonatally with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms, but specific IgE was not significantly affected. The prevalence of asthma and the reversibility of airway resistance after beta2-agonist administration at 5 years of age were significantly increased in the children colonized neonatally with these organisms as compared with the children without such colonization (33% vs. 10% and 23% vs. 18%, respectively).

CONCLUSIONS

Neonates colonized in the hypopharyngeal region with S. pneumoniae, H. influenzae, or M. catarrhalis, or with a combination of these organisms, are at increased risk for recurrent wheeze and asthma early in life.

Outcome of asthma and wheezing in the first 6 years of life: follow-up through adolescence

RATIONALE

The effect of early life wheezing on respiratory function and continued symptoms through adolescence has not been fully described. Using data from a population-based birth cohort in Tucson, Arizona, we previously described four phenotypes based on the occurrence of wheezing lower respiratory illnesses before age 3 yr and active wheeze at age 6 yr: never wheezers (n = 425), transient early wheezers (n = 164), persistent wheezers (n = 113), and late-onset wheezers (n = 124).

OBJECTIVE

We sought to determine the prognosis for these phenotypes, with reference to lung function and symptoms, through adolescence.

METHODS

Current wheeze was assessed by questionnaire, lung function was measured by conventional spirometry, and atopy was determined by skin prick tests.

RESULTS

The prevalence of atopy and wheeze by age 16 yr was similar for never and transient wheezers and for persistent and late-onset wheezers. Both transient early, and persistent wheezers had significantly lower FEF(25-75) (-259 ml/s, p < 0.001, and -260 ml/s, p = 0.001, respectively), FEV1 (-75 ml, p = 0.02, and -87 ml, p = 0.03, respectively), and FEV1:FVC ratio (-1.9%, p = 0.002, and -2.5%, p = 0.001, respectively) through age 16 yr compared with never wheezers. Late-onset wheezers had levels of lung function similar to those of never wheezers through age 16 yr. There was no significant change in lung function among subjects with any of the four phenotypes, relative to their peers, from age 6 to 16 yr.

CONCLUSION

Patterns of wheezing prevalence and levels of lung function are established by age 6 yr and do not appear to change significantly by age 16 yr in children who start having asthma-like symptoms during the preschool years.

Familial correlations and inter-relationships of four asthma-associated quantitative phenotypes in 320 French EGEA families ascertained through asthmatic probands

Asthma is a complex disease, associated with biological and physiological phenotypes including immunoglobulin E (IgE) levels, sum of positive skin prick tests to allergens (SPTQ), eosinophil counts (EOS) and percent predicted forced expiratory volume in 1 s (%FEV1). We investigated the patterns of familial correlations and the inter-relationships of these four quantitative phenotypes, using the general class D regressive model, in 320 French EGEA nuclear families ascertained through 204 offspring (set A) and 116 parents (set B). Familial correlations of IgE and SPTQ were consistent with a model including no spouse correlation and equal parent-offspring and sib-sib correlations (rhoPO = rhoSS = 0.25 for IgE and 0.15 for SPTQ), this model being compatible with an additive polygenic model in the whole sample and the two family subsets A and B. Different patterns of familial correlations of EOS and %FEV1 were observed in these two sets. In set A, the best fitting model included no spouse correlation and equality of parent-offspring and sib-sib correlations (rhoPO = rhoSS = 0.14 for EOS and 0.23 for %FEV1). In set B, EOS had only a significant rhoSS of 0.28, while %FEV1 had significant rhoMO of 0.28 and rhoSS of 0.16. Analysis of shared familial determinants between these phenotypes indicated an overlap of at most 30% in rhoFO for IgE and SPTQ and in both rhoFO and rhoMO for IgE and EOS, while determinants of %FEV1 and atopy-related phenotypes appear distinct. These results may have implications for further linkage and association studies with genetic markers.