Predictors of remitting, periodic, and persistent childhood asthma

[Mild asthma in children: new data and a revival of interest]

According to the Global Initiative for Asthma (GINA) classification, mild asthma includes intermittent and mild persistent asthma. It represents more than 75% of asthmatic children. The symptoms and functional impact are well described. Mild asthma can lead to severe exacerbations. Progression to more severe disease may occur. Consequently, it is important to diagnose mild asthma, to initiate the appropriate treatment early, and to identify the risk factors for aggravation. Nevertheless, mild asthma is under-diagnosed and under-treated. Bronchial inflammation and remodeling are observed in mild asthma. A daily low-dose of inhaled corticosteroids is the reference treatment for mild persistent asthma. Intermittent inhaled corticosteroids cannot be recommended in children with mild persistent asthma.

The Childhood Asthma Management Program (CAMP): Contributions to the Understanding of Therapy and the Natural History of Childhood Asthma

The Childhood Asthma Management Program (CAMP) has been in continuous existence for almost two decades, which makes it the largest randomized, placebo-controlled clinical trial with extended follow-up for children with mild to moderate asthma. As such, its cumulative data from baseline, active treatment, and post-treatment have proved to be an invaluable resource for not only assessing the efficacy and safety of long-term inhaled corticosteroid therapy in childhood, but for discovery of many other aspects of childhood asthma, including genetics and biomarkers.

RANTES gene polymorphisms and risk of pediatric asthma: A meta-analysis

Numerous studies have evaluated the association between regulated upon activation, normal T cells expressed and secreted (RANTES) gene polymorphisms (-403G/A and -28C/G) and risk of pediatric asthma. However, the results have been inconsistent. A meta-analysis of the association between RANTES gene polymorphisms and pediatric asthma risk was performed in the current study. A search for published literature was conducted in the Google Scholar, PubMed and the CNKI databases (January 2000 to April 2012) and seven studies were retrieved. The associations between RANTES gene polymorphisms and pediatric asthma risk were estimated by pooled odds ratio (OR) and 95% confidence interval (CI) using a fixed- or random-effects model. Meta-analysis results revealed no significant association between the -403G/A polymorphism and risk of pediatric asthma. In the subgroup analysis by ethnicity, no association was identified between the -403G/A polymorphism and pediatric asthma risk in Caucasian and Asian populations. In the -28C/G group, the meta-analysis indicated a significant association between the -28C/G polymorphism and pediatric asthma susceptibility among the total population (recessive model: OR, 1.34; 95% CI, 1.04-1.72). However, when the subgroup analysis was performed by ethnicity, no significant associations were identified in Asians and Europeans. This result suggests that the -28C/G polymorphism may not be associated with pediatric asthma risk, while the observed increase in the risk of pediatric asthma may be due to racial differences. Additional large-scale studies are required to provide conclusive evidence on the effects of RANTES gene polymorphisms on the risk of pediatric asthma.

International consensus on (ICON) pediatric asthma

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Several guidelines and/or consensus documents are available to support medical decisions on pediatric asthma. Although there is no doubt that the use of common systematic approaches for management can considerably improve outcomes, dissemination and implementation of these are still major challenges. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), recently formed by the EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus on (ICON) Pediatric Asthma. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences, thus providing a concise reference. The principles of pediatric asthma management are generally accepted. Overall, the treatment goal is disease control. To achieve this, patients and their parents should be educated to optimally manage the disease, in collaboration with healthcare professionals. Identification and avoidance of triggers is also of significant importance. Assessment and monitoring should be performed regularly to re-evaluate and fine-tune treatment. Pharmacotherapy is the cornerstone of treatment. The optimal use of medication can, in most cases, help patients control symptoms and reduce the risk for future morbidity. The management of exacerbations is a major consideration, independent of chronic treatment. There is a trend toward considering phenotype-specific treatment choices; however, this goal has not yet been achieved.

Severe asthma in childhood: recent advances in phenotyping and pathogenesis

PURPOSE OF REVIEW

Children with severe asthma have a high degree of respiratory morbidity despite treatment with high doses of inhaled corticosteroids and are therefore very difficult to treat. This review will discuss phenotypic and pathogenic aspects of severe asthma in childhood, as well as remaining knowledge gaps.

RECENT FINDINGS

As a group, children with severe asthma have a number of distinct phenotypic features compared with children with mild-to-moderate asthma. Clinically, children with severe asthma are differentiated by greater allergic sensitization, increased exhaled nitric oxide, and significant airflow limitation and air trapping that worsens as a function of age. These findings are accompanied by structural airway changes and increased and dysregulated airway inflammation and oxidant stress which may explain the differential nature of corticosteroid responsiveness in this population. Because children with severe asthma themselves are a heterogeneous group, current efforts are focused on improved definition and sub-phenotyping of the disorder. Whereas the clinical relevance of phenotyping approaches in severe asthma is not yet clear, they may provide important insight into the mechanisms underlying the disorder.

SUMMARY

Improved classification of severe asthma through unified definitions, careful phenotypic analyses, and mechanism-focused endotyping approaches may ultimately advance knowledge and personalized treatment.

Long-term outcomes of early-onset wheeze and asthma

Evidence from longitudinal cohort studies demonstrates that wheezing that begins in early life and continues into the school years generally persists into adulthood. This persistent wheezing is associated with lung function deficits and airways hyperresponsiveness that appear to be established in the first few years of life. Allergic sensitization early in life, early-life infection with rhinovirus, or colonization with any of a number of bacteria have been associated with increased risk of persistent wheeze. Early life, whether in utero or in the first few years of life, presents a window of vulnerability during which airway injury results in persistent airways dysfunction. Available data further suggest that a second such window of vulnerability might be present in the preadolescent and adolescent years. Lung function growth patterns established by age 6 years generally continue into early adulthood to middle adulthood, typically leaving groups of subjects with wheezing that persists into or relapses during adulthood with a mean FEV(1) of about 10% of predicted value less than their peers who do not wheeze. Subgroups of patients with persistent asthma, however, can have progressive decreases in lung function and enter adulthood with even lower lung function. The concern exists that these deficits in lung function apparent in early adulthood might put subjects at risk for the later development of chronic obstructive pulmonary disease.

Pediatric asthma phenotypes

PURPOSE OF REVIEW

There is currently limited ability to identify which infants and young children with recurrent wheezing will ultimately develop persistent asthma. In addition, it is not clear how risk factors influence the development of asthma in later childhood and adulthood. This review will discuss efforts to categorize these children with recurrent wheezing and develop asthma-predictive tools.

RECENT FINDINGS

Transient and persistent wheezing phenotypes have been identified with atopy, reduced lung function, and viral and bacterial respiratory infection as major risk factors for persistence of asthma. Children with severe asthma tend to have greater magnitude of atopy and lower lung function than those with mild-moderate asthma. These phenotypes and risk factors have been described in previous studies and are supported by the recent literature.

SUMMARY

Heterogeneity of wheezing phenotypes may account for different responses to treatment and varied outcomes. Overlap in phenotypes and instability over time also add additional challenges to defining discrete groups of children with specific outcomes. Further studies are needed to determine combinations of variables that may improve phenotype designation with the goal of improving asthma prevention and treatment as well as predicting outcomes and understanding the pathogenesis of asthma.

IgE antibodies to animal-derived lipocalin, kallikrein and secretoglobin are markers of bronchial inflammation in severe childhood asthma

BACKGROUND

Component-resolved allergy diagnostics enables the detection of crossreactive or species-specific allergen components. This study analysed Immunoglobulin E (IgE) profiles to single allergen components in relation to bronchial inflammation in severe childhood asthma.

METHODS

Ninety-five schoolchildren were assessed, 39 with controlled mild-to-moderate asthma and 56 uncontrolled severe asthmatics. Allergen components (n = 111) of food allergens, pollen and perennial aeroallergens were analysed using an immunosolid-phase allergen chip. Blood eosinophils (10(9) × l(-1)), bronchial inflammation (FeNO, ppb), lung function (FEV(1)%) and bronchial hyper-responsiveness (BHR) (dose-response slope of methacholine challenge) were measured.

RESULTS

A specific IgE response to more than three animal-derived components--lipocalin (nMus m 1, rEqu c 1, Fel d 4, rCan f 1, 2), kallikrein (rCan f 5) and secretoglobin (rFel d 1)--was more common among severe asthmatics compared to children with controlled asthma (n = 14 vs n = 3, P = 0.030). These subjects also displayed higher blood eosinophils (0.65 vs 0.39, P = 0.021), higher Fractional exhaled nitric oxide (38 ppb vs 25 ppb, P = 0.021) and increased BHR (112 vs 28, P = 0.002) compared to other severe asthmatics positive to fewer lipocalin/kallikrein/secretoglobin components. Among all sensitized subjects, there were correlations between specific IgE levels for rFel d 4 and nMus m 1 (r = 0.751, P ≤ 0.001) and for rFel d 4 and rEqu c 1 (r = 0.850, P ≤ 0.001).

CONCLUSION

Multi-sensitization towards lipocalin, kallikrein and secretoglobin components is associated with increased bronchial inflammation in severe asthmatics. In addition, crossreactive patterns were observed between different lipocalin components.

Development and comorbidity of eczema, asthma and rhinitis to age 12: data from the BAMSE birth cohort

BACKGROUND

Allergy-related diseases are a public health issue, but knowledge on development and comorbidity among children is scarce. The aim was to study the development of eczema, asthma and rhinitis in relation to sex and parental allergy, in a population-based cohort, during childhood.

METHODS

At 1, 2, 4, 8 and 12 years, parental questionnaires were used to obtain data on allergy-related diseases. Complete data for all five follow-up occasions were available from 2916 children. Odds ratios for the risk of any allergy-related disease in relation to heredity and sex were calculated using generalized estimating equations.

RESULTS

At 12 years, 58% of the children had had eczema, asthma and/or rhinitis at some time. Disease turnover was high for all three diseases throughout the study. Comorbidity increased with age, and at 12 years, 7.5% of all the children were affected by at least two allergy-related diseases. Parental allergy was associated with increased comorbidity and more persistent disease and increased the risk of having any allergy-related disease (adjusted OR 1.76; 95% CI 1.57-1.97) up to 12 years. Male sex was associated with an increased risk throughout childhood. Boys and girls did not differ in disease persistence, and for comorbidity, the differences were minor.

CONCLUSIONS

Allergy-related diseases may affect a majority of children. Eczema, asthma and rhinitis develop dynamically throughout childhood, and allergic comorbidity is common. These findings indicate that allergy-related diseases should be neither seen nor studied as isolated entities.

The role of immunotherapy in the management of childhood asthma

Subcutaneous immunotherapy (SCIT) is still questioned as a safe and efficacious way of treating allergic asthma in children. In a Cochrane review published in 2010 it was, however, concluded that SCIT has significant and beneficial effects on symptoms and medication use in both children and adults with mostly mild asthma. Only a few studies have been performed to specifically study if SCIT in children with moderate asthma reduces the need for inhaled corticosteroids. There are conflicting results that illustrate the problem of the heterogeneity of the asthma disease and the fact that allergies may play different roles on the severity and symptoms of the disease. Furthermore, children with severe allergic asthma are often sensitized to multiple allergens, which makes SCIT both complicated and less safe to administer. On the other hand, if the child suffers from asthmatic symptoms despite adherence to pharmacotherapy, omalizumab or a combination of omalizumab and allergen immunotherapy might be useful. There is a need for more studies on this combination before it can be considered as an additional therapy in children with asthma and severe allergies. Sublingual immunotherapy (SLIT) has also been shown to improve asthma symptoms and medication use. SLIT is safe although its efficacy compared with SCIT has been studied very little. Another approach is to try to prevent asthma by treating children with SCIT for allergic rhinoconjunctivitis before asthma has developed. The most attractive prospect, however, is to find ways of preventing asthma by vaccination against the most common viruses, particularly rhinovirus. There is evidence that there are children at high risk of developing asthma in whom a viral infection can also enhance the risk of allergen sensitization. So far this vaccination has not been achievable although research is in progress.

Pediatric asthma: natural history, assessment, and treatment

Wheezing and childhood asthma are not synonymous but rather comprise a heterogeneous group of conditions that have different outcomes over the course of childhood. Most infants who wheeze have a transient condition associated with diminished airway function at birth and have no increased risk of asthma later in life. However, children with persistent wheezing throughout childhood and frequent exacerbations represent the main challenge today. Studying the natural history of asthma is important for the understanding and accurate prediction of the clinical course of different phenotypes. To date, a great improvement has been achieved in reducing the frequency of asthma symptoms. However, neither decreased environmental exposure nor controller treatment, as recommended by the recent National Asthma Education And Prevention Program, can halt the progression of asthma in childhood or the development of persistent wheezing phenotype. This review focuses on the recent studies that led to the current understanding of asthma phenotypes in childhood and the recommended treatments.

New insights into the natural history of asthma: primary prevention on the horizon

Recent studies of the natural history of asthma have shifted attention toward viral respiratory tract illness in early life as a major risk factor associated with the development of the most persistent forms of the disease. Although early aeroallergen sensitization is strongly associated with chronic asthma, several trials in which single-aeroallergen exposure in pregnancy and early childhood was successfully accomplished and compared with sham avoidance have failed to show any decrease in asthma incidence. New evidence suggests that complex interactions occur between viral infection and aeroallergen sensitization in genetically susceptible subjects that trigger the immune responses and airway changes that are characteristic of persistent asthma. The finding that exposure to bacterial products among children raised on farms is associated with diminished asthma prevalence during the school years has now been replicated, and experimental studies have suggested that these effects are mediated by the activation of regulatory T cells in the airway. It is thus plausible to hypothesize that primary prevention of asthma could be attained through surrogate therapeutic interventions that activate similar mechanisms in young children at high risk for asthma.

Advancing asthma care: the glass is only half full!

Over the past 20 years, there has been a concerted effort in the United States to reduce morbidity related to chronic disease, including asthma. Attention was initially directed toward asthma in response to the recognition that asthma mortality was increasing and that the burden of disease was significant. These efforts to address asthma mortality led to many new initiatives to develop clinical practice guidelines, implement the asthma guidelines into clinical practice, conduct research to fill the gaps in the guidelines, and continuously revise the asthma guidelines as more information became available. An assessment of our progress shows significant accomplishments in relation to reducing asthma mortality and hospitalizations. Consequently, we are now at a crossroads in asthma care. Although we have recognized some remarkable accomplishments in reducing asthma mortality and morbidity, the availability of new tools to monitor disease activity, including biomarkers and epigenetic markers, along with information technology systems to monitor asthma control hold some promise in identifying gaps in disease management. These advances should prompt the evolution of new strategies and new treatments to further reduce disease burden. It now becomes imperative to continue a focus on ways to further reduce the burden of asthma and prevent its onset.

New insights into asthma pathogenesis and treatment

Although national asthma guidelines help organize standards for asthma care, current asthma management is still primarily symptom based. Recent reports provide insights on how to improve asthma management through steps to better understand the natural history of asthma, individualize asthma care, reduce asthma exacerbations, manage inner city asthma, and some potential new ways to use available medications to improve asthma control. Despite many significant gains in managing asthma, we must now find improved strategies to prevent asthma exacerbations, alter the natural history of the disease, and to reduce health disparities in asthma care. Perhaps new directions in personalized medicine including a systems biology approach, along with improved health care access and communication will lead to better methods to alleviate the burden of asthma. This review will discuss the benefits and limitations of the current approach to asthma management, new studies that could impact new directions in asthma management, and new insights related to mechanisms of asthma and allergic airways inflammation that could eventually lead to improved asthma control.

Maternal and childhood asthma: risk factors, interactions, and ramifications

Asthma is emerging as a premier example of a health risk that can largely be molded by the status of the mother and the environmental conditions encountered during sensitive windows of prenatal and early childhood development. While genetic background, allergic status of parents, and predisposition for atopy and inflammation play a role, early-life environmental conditions can completely alter the course of immune and respiratory system development. Environmentally induced alterations that (1) maintain the Th2 bias seen during gestation, (2) block the maturation of innate immune cells and (3) create inflammatory dysfunction in the infant provide the foundation for childhood asthma. No single risk factor can fully explain the increased prevalence of asthma in recent decades but it is assumed that the rapid increase is due to environmental and/or epigenetic changes. Well-established and suspected environmental risk factors cover all categories of early life interactions from diet, exposure to environmental contaminants and drugs, maternal and neonatal infections, hygiene, timing of vaccinations and even the mode of birth delivery. Because asthma is connected to the risk of several comorbid chronic conditions, the benefit of asthma risk reduction and prevention is greater than initially may be apparent. This review discusses strategies to optimize preventative and therapeutic options across life stages.

Risk factors for bronchial hyperresponsiveness in teenagers differ with sex and atopic status

BACKGROUND

Sex-related differences in bronchial hyperresponsiveness (BHR) have been reported in adolescents, but the mechanisms remain obscure.

OBJECTIVE

To investigate the risk factors for BHR in the Raine Study, a community-based longitudinal birth cohort.

METHODS

At 14 years of age, children underwent a respiratory assessment including a questionnaire, lung function testing, methacholine challenge, and determination of atopic status.

RESULTS

A total of 1779 children provided data for assessment, with 1510 completing lung function and methacholine challenge testing. Current asthma was present in 152 (10.4%), 762 (50.5%) were atopic, and 277 (18.6%) had BHR. BHR was more common in girls, whereas atopy was more common in boys, with no sex differences in asthma or current wheeze. Independent risk factors for BHR were being female (odds ratio [OR], 3.45; P < .001), atopy at 14 years (OR, 1.27; P = .004), and current asthma (OR, 2.15; P = .005). Better lung function was protective against BHR (forced expiratory flow between 25% and 75% of forced vital capacity/forced vital capacity, OR, 0.09; P < .001). Risk factors differed with sex and atopic status. Early-life factors were generally not independent risk factors for BHR at 14 years of age, with the exception of being smaller at birth in boys (birth length, OR, 6 × 10(-9); P = .017) and maternal asthma in girls (OR, 1.84; P = .041). Current asthma was not a risk for BHR in nonatopic children.

CONCLUSION

Bronchial hyperresponsiveness was more common and more severe in girls. These differences could not be explained by differences in lung function or atopic status.

Problematic severe asthma: a proposed approach to identifying children who are severely resistant to therapy

Children with problematic severe asthma (PA) are either difficult to treat because of the presence of aggravating factors or else severely resistant to therapy. We investigated a cohort of school-aged children with PA and compared these children to age-matched peers with controlled persistent asthma (CA). The aims were to characterize features of children suffering from PA and identify children who were severely resistant to therapy. In this cross-sectional, multicenter comparison of children with different manifestations of persistent asthma, PA was defined as insufficient asthma control despite level 4 treatment, according to GINA. The protocol included questionnaires, spirometry, methacholine provocation, measurement of fraction of nitric oxide in exhaled (FE(NO) ) and nasal air, blood sampling for inflammatory biomarkers and atopy, and computerized tomography of sinuses and lungs (in the PA group only). Of the 54 children with PA, 61% had therapy-resistant asthma, with the remaining being difficult to treat because of identified aggravating factors. Children with PA more often had parents with asthma (p=0.003), came from families with a lower socioeconomic status (p=0.01), were less physically active (p=0.04), and had more comorbidity with rhinoconjunctivitis (p=0.01) than did the 39 children with CA. The former also exhibited lower FEV(1) values (p=0.02) and increased bronchial hyper-responsiveness (p=0.01), but there were no differences in atopy (p=0.81) or FE(NO) (p=0.16). A non-invasive protocol, involving a standardized and detailed clinical characterization, revealed distinguishing features of children with PA and enabled the identification of children with therapy-resistant asthma.

Advances in pediatric asthma in 2010: addressing the major issues

Last year's "Advances in pediatric asthma" concluded with the following statement: "If we can close these [remaining] gaps through better communication, improvements in the health care system and new insights into treatment, we will move closer to better methods to intervene early in the course of the disease and induce clinical remission as quickly as possible in most children." This year's summary will focus on recent advances in pediatric asthma that take steps moving forward as reported in Journal of Allergy and Clinical Immunology publications in 2010. Some of these recent reports show us how to improve asthma management through steps to better understand the natural history of asthma, individualize asthma care, reduce asthma exacerbations, and manage inner-city asthma and some potential new ways to use available medications to improve asthma control. It is clear that we have made many significant gains in managing asthma in children, but we have a ways to go to prevent asthma exacerbations, alter the natural history of the disease, and reduce health disparities in asthma care. Perhaps new directions in personalized medicine and improved health care access and communication will help maintain steady progress in alleviating the burden of this disease in children, especially young children.

Using genetics to predict the natural history of asthma?

Clinical practice reminds us that there is considerable variability in the course of asthma over time. Treatment of patients with asthma would be considerably improved if one could accurately predict the likely course of disease over the life course. Recently, with the advent of the era of genome-wide association studies, there has been a monumental shift in our understanding of the genetic factors that underlie inherited susceptibility to asthma. Genes have been identified that modulate many aspects of the natural history of asthma, such as susceptibility to atopy, altered lung development, and susceptibility to more severe disease. Heritability studies have even suggested a role for genetic factors in remission of asthma. However, although the discovery of novel genetic factors underlying disease susceptibility has undoubtedly improved our understanding of disease pathogenesis, whether these advances have improved the ability to predict the natural history in individual patients is questionable, and the application of genetic testing to clinical practice remains some way off.

Long-term studies of the natural history of asthma in childhood

Segmentation of children with asthma and other wheezy disorders remains the main research challenge today, as it was when described 2 centuries ago. Early childhood wheezy disorders follow different temporal trajectories, probably representing different underlying mechanisms (endophenotypes). Prospective identification of endophenotypes allowing accurate prediction of the clinical course is currently not possible. The variability of the clinical course remains an enigma and difficult to predict. Three of 4 school-aged children with asthma have outgrown disease by midadulthood. The risk of persistence increases with severity, sensitization, smoking, and female sex. Genetic risk variants might help disentangle the heterogeneity of asthma and other wheezy disorders. At early school age, children with asthma have reduced lung function. It is an important and unresolved question whether the airflow limitation associated with asthma already existed at birth or developed along with symptoms. Likewise, the association between the infant's bronchial responsiveness and development of asthma and other wheezy disorders is unclear. Neither primary prevention through manipulation of environmental factors nor secondary prevention through the use of inhaled corticosteroids can effectively halt the long-term disease progression in childhood. In conclusion, the natural history of asthma and the associated airway changes is still poorly understood, and we have not managed to translate findings from long-term studies into a deeper understanding of the underlying endophenotypes or improved disease management. We propose the need for a translational research approach based on long-term clinical studies of birth cohorts with comprehensive and objective assessments of intermediate phenotypes and environmental exposures combined with interdisciplinary basic research and a systems biology approach.

Severe Asthma in Children: Insights from the National Heart, Lung, and Blood Institute's Severe Asthma Research Program

Severe asthma in children is a complicated disorder characterized by ongoing symptoms and persistent airway inflammation despite treatment with high doses of inhaled and oral corticosteroids. Although knowledge of asthma and its associated mechanisms has increased substantially over the past decade, significant gaps remain about the determinants of severe asthma in children and the progression of the disorder across the lifespan. This review highlights recent insights into severe asthma in children derived from the National Heart, Lung, and Blood Institute's Severe Asthma Research Program (SARP), with an emphasis on age-specific findings and differences from severe asthma in adults. While the existence of a true severe asthma phenotype in children is subject to some debate, given the results of SARP and other investigators, we conclude that there is indeed a subgroup of children with severe asthma who have extreme morbidity and differentiating clinical features that are identifiable very early in life. However, unlike adults with severe asthma, children with severe asthma are more likely to fall in a more narrow cluster that is characterized by marked atopy and reversible airflow obstruction. While SARP has advanced knowledge of severe asthma in children, considerable gaps remain for which additional studies are needed.