How the presence of rhinoconjunctivitis and the severity of asthma modify the relationship between obesity and asthma in children 6-7 years old

Omalizumab for Severe Asthma: Beyond Allergic Asthma

Different subsets of asthma patients may be recognized according to the exposure trigger and the frequency and severity of clinical signs and symptoms. Regarding the exposure trigger, generally asthma can be classified as allergic (or atopic) and nonallergic (or nonatopic). Allergic and nonallergic asthma are distinguished by the presence or absence of clinical allergic reaction and in vitro IgE response to specific aeroallergens. The mechanisms of allergic asthma have been extensively studied with major advances in the last two decades. Nonallergic asthma is characterized by its apparent independence from allergen exposure and sensitization and a higher degree of severity, but little is known regarding the underlying mechanisms. Clinically, allergic and nonallergic asthma are virtually indistinguishable in exacerbations, although exacerbation following allergen exposure is typical of allergic asthma. Although they both show several distinct clinical phenotypes and different biomarkers, there are no ideal biomarkers to stratify asthma phenotypes and guide therapy in clinical practice. Nevertheless, some biomarkers may be helpful to select subsets of atopic patients which might benefit from biologic agents, such as omalizumab. Patients with severe asthma, uncontrolled besides optimal treatment, notwithstanding nonatopic, may also benefit from omalizumab therapy, although currently there are no randomized double-blind placebo controlled clinical trials to support this suggestion. However, omalizumab discontinuation according to each patient's response to therapy and pharmacoeconomical analysis are questions that remain to be answered.

The influence of gender and atopy in the relationship between obesity and asthma in childhood

BACKGROUND

The objective of the study was to examine the relationship between asthma and overweight-obesity in Spanish children and adolescents and to determine whether this relationship was affected by gender and atopy.

METHODS

The study involves 8607 Spanish children and adolescents from the International Study of Asthma and Allergies in Childhood phase III. Unconditional logistic regression was used to obtain adjusted odds ratios (OR) and 95% confidence intervals (95% CI) for the association between asthma symptoms and overweight-obesity in the two groups. Afterwards, it was stratified by sex and rhinoconjunctivitis.

RESULTS

The prevalence of overweight and obesity in 6-7-year-old children was 18.6% and 5.2% respectively and in 13-14 year-old teenagers was 11.4% and 1.1% respectively. Only the obese children, not the overweight children, of the 6-7 year old group had a higher risk of any asthma symptoms (wheezing ever: OR 1.68 [1.15-2.47], asthma ever: OR 2.29 [1.43-3.68], current asthma 2.56 [1.54-4.28], severe asthma 3.18 [1.50-6.73], exercise-induced asthma 2.71 [1.45-5.05]). The obese girls had an increased risk of suffering any asthma symptoms (wheezing ever: OR 1.73 [1.05-2.91], asthma ever: OR 3.12 [1.67-5.82], current asthma 3.20 [1.65-6.19], severe asthma 4.83[1.94-12.04], exercise-induced asthma 3.68 [1.67-8.08]). The obese children without rhinoconjunctivitis had a higher risk of asthma symptoms.

CONCLUSIONS

Obesity and asthma symptoms were associated in 6-7 year-old children but not in 13-14 year-old teenagers. The association was stronger in non-atopic children and obese girls.

Childhood obesity in relation to poor asthma control and exacerbation: a meta-analysis

To estimate the association between obesity and poor asthma control or risk of exacerbations in asthmatic children and adolescents, and to assess whether these associations are different by sex.

A meta-analysis was performed on unpublished data from three North-European paediatric asthma cohorts (BREATHE, PACMAN (Pharmacogenetics of Asthma medication in Children: Medication with Anti-inflammatory effects) and PAGES (Pediatric Asthma Gene Environment Study)) and 11 previously published studies (cross-sectional and longitudinal studies). Outcomes were poor asthma control (based on asthma symptoms) and exacerbations rates (asthma-related visits to the emergency department, asthma-related hospitalisations or use of oral corticosteroids). Overall pooled estimates of the odds ratios were obtained using fixed- or random-effects models.

In a meta-analysis of 46 070 asthmatic children and adolescents, obese children (body mass index ≥95th percentile) compared with non-obese peers had a small but significant increased risk of asthma exacerbations (OR 1.17, 95% CI 1.03–1.34; I2: 54.7%). However, there was no statistically significant association between obesity and poor asthma control (n=4973, OR 1.23, 95% CI 0.99–1.53; I2: 0.0%). After stratification for sex, the differences in odds ratios for girls and boys were similar, yet no longer statistically significant.

In asthmatic children, obesity is associated with a minor increased risk of asthma exacerbations but not with poor asthma control. Sex does not appear to modify this risk.

Pediatric Obesity-Related Asthma: The Role of Metabolic Dysregulation

The burden of obesity-related asthma among children, particularly among ethnic minorities, necessitates an improved understanding of the underlying disease mechanisms. Although obesity is an independent risk factor for asthma, not all obese children develop asthma. Several recent studies have elucidated mechanisms, including the role of diet, sedentary lifestyle, mechanical fat load, and adiposity-mediated inflammation that may underlie the obese asthma pathophysiology. Here, we review these recent studies and emerging scientific evidence that suggest metabolic dysregulation may play a role in pediatric obesity-related asthma. We also review the genetic and epigenetic factors that may underlie susceptibility to metabolic dysregulation and associated pulmonary morbidity among children. Lastly, we identify knowledge gaps that need further exploration to better define pathways that will allow development of primary preventive strategies for obesity-related asthma in children.

Metabolic origins of childhood asthma

Childhood obesity and incidence of asthma are increasing globally. The parallel increase of the two suggests that obesity and asthma may be related and that abnormalities in the lipid and/or glucose metabolism may contribute to the pathogenesis of asthma. The clinical presentation of obese asthma is distinct from other asthma phenotypes and depending on age of onset of symptoms. Asthma in obese people tends to be more severe, not typically associated with allergy, and less responsive to standard anti-inflammatory therapy, including corticosteroids. Obesity and obesity-related comorbidities may lead to asthma via a number of mechanisms including changes in lung mechanics, the nitric oxide metabolism, and by causing inflammation. Furthermore, evidence suggests that nutrition during pregnancy contributes to intrauterine immune and metabolic programming in the offspring, which may have major influences on predisposition to cardiovascular, metabolic, and allergic diseases, including asthma, later in life. This review will highlight some suggested mechanistic links between obesity and diabetes with asthma.

Adiposity, fractional exhaled nitric oxide, and asthma in U.S. children

RATIONALE

Whether allergic airway inflammation mediates the association between overweight or obesity and childhood asthma is unknown.

OBJECTIVES

To examine adiposity, asthma, and fractional exhaled nitric oxide (FeNO) in U.S. children.

METHODS

Cross-sectional study of indicators of adiposity or obesity, FeNO (a biomarker of eosinophilic airway inflammation), and asthma in 2,681 children aged 6-17 years in the 2007-2010 National Health and Nutrition Examination Survey. Adiposity measures included body mass index (BMI), percent body fat (PBF), and waist circumference (WC).

MEASUREMENTS AND MAIN RESULTS

BMI, PBF, and WC were associated with asthma among children with low FeNO (odds ratio, 1.54-1.68; P < 0.01), but not among children with increased FeNO. Among children without asthma, BMI, PBF, and WC were associated with higher FEV1 and FVC, and lower FEV1/FVC. Among children with asthma and a high FeNO, all adiposity indicators were associated with decreased FEV1/FVC (β = -1.5% to -1.7% per z score) but not with FEV1 or FVC. Higher BMI or PBF was associated with worse asthma severity or control in children with asthma and increased FeNO, but not in children with asthma and low FeNO. Similar results were obtained in a secondary multivariate analysis of overweight or obesity (defined as BMI ≥85th percentile) and asthma or indicators of asthma severity or control, stratified by FeNO level.

CONCLUSIONS

Adiposity indicators are associated with asthma in children with low FeNO. Among children with asthma, adiposity indicators are associated with worse asthma severity or control in those with high FeNO.

Childhood obesity and risk of allergy or asthma

The simultaneous increment in the prevalence of obesity and allergic diseases suggests a possible link between them. This review focuses on the consequences of obesity on allergic diseases, especially asthma in children and adolescents, and evaluates the available evidence on the possible mechanisms. Obesity is related more strongly to nonatopic than atopic asthma, suggesting non-eosinophilic inflammation and Th1 polarization. Among other allergic diseases, the association is more consistent with eczema compared to allergic rhinitis/rhinoconjunctivitis. The mechanisms of asthma in obese individuals could involve mechanical effects of obesity on lung function, adipokines-mediated inflammation, shared factors (diet, genetics, sedentary lifestyle) and comorbidities.

Peripheral Mononuclear Response to Antigenic Stimulation in Children with Obese Asthma Phenotype

An investigation of immunopathogenetic mechanisms of obesity-associated asthma may demonstrate novel therapeutic targets. The aim of this study was to compare levels of T-helper lymphocyte (Th)1, Th2, regulatory T lymphocyte (Treg), and Th17 cytokines secreted by peripheral blood mononuclear cell culture (PBMC) in response to nonspecific stimulation in obese and nonobese children with asthma. Obese and nonobese children with asthma aged 5-16 were enrolled into this case-control study consecutively. Age at asthma diagnosis and clinical severity were recorded. A skin prick test was performed. Serum adipokine levels and PBMC supernatant interleukin (IL)-4, IL-10, IL-17, IL-23, interferon (IFN)γ, and transforming growth factor (TGF)-β levels were measured. Mean (±standard deviation) ages of obese (n=28) and nonobese (n=39) children with asthma were 8.7±2.9 and 10.5±3.2, respectively. Asthma symptom score was higher, and age at asthma diagnosis was lower in obese compared with nonobese children with asthma (P=0.03 and P=0.004, respectively). Leptin levels were significantly higher in obese than in nonobese asthma group (P<0.001). IL-10 and IL-17 levels in obese group were significantly lower than in nonobese group (P=0.005 and P=0.017, respectively). On the other hand, TGF-β levels were significantly higher in obese compared with nonobese children with asthma (P=0.015). IL-4, IL-23, and IFNγ levels were not significantly different between the groups (P<0.05 for all). Low IL-10 and high TGF-β levels in obese compared with nonobese children with asthma might indicate lower anti-inflammatory cytokine secretion and Treg function as well as a higher remodeling process in obesity-associated asthma in children.

Obesity - a promoter of allergy?

The prevalence of both obesity and allergy has been increasing throughout the world, leading to the hypothesis that the two are linked to one another. This overview summarizes the results of 34 studies from 2002 to 2012 that investigated a possible contributing effect of increasing body mass on the development and prevalence of various atopic diseases. Obesity was found to clearly affect bronchial asthma. However, the correlation was stronger in the nonatopic asthma phenotype. Obesity was found to be associated with the development of atopic dermatitis in children only. No clear association was found between obesity and the prevalence of allergic rhinitis or allergic conjunctivitis or increased sensitization to food allergens. This review sums up our study results and discusses a possible role of obesity in the promotion of allergy and asthma.

The association between BMI, vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema in children and adolescents: ISAAC Phase Three

BACKGROUND

Several studies have observed an association between obesity and asthma, but whether or not there is an association with rhinoconjunctivitis or eczema is unclear.

AIMS

To examine the relationship between body mass index categories (underweight, overweight and obesity), vigorous physical activity and television viewing and the risk of symptoms of asthma, rhinoconjunctivitis and eczema.

METHODS

As part of International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three, parents or guardians of children aged 6-7 years completed written questionnaires about symptoms of asthma, rhinoconjunctivitis and eczema, and several potential risk factors, such as vigorous physical activity and television viewing, and other information such as the child's height and weight. Adolescents aged 13-14 years self-completed the questionnaires on these symptoms and potential risk factors and reported their own height and weight. For 28% of children and 24% of adolescents, the height and weight was objectively measured.

RESULTS

A total of 76 164 children aged 6-7 years (from 29 centres and 17 countries) and 201 370 adolescents aged 13-14 years (from 73 centres and 35 countries) provided data meeting the inclusion criteria. There were associations between overweight and obesity, but not underweight, and symptoms of asthma and eczema but not rhinoconjunctivitis. Vigorous physical activity was positively associated with symptoms of asthma, rhinoconjunctivitis and eczema in adolescents, but not children. Viewing television for five or more hours/day was associated with an increased risk of symptoms of asthma, rhinoconjunctivitis and eczema in adolescents and symptoms of asthma in children.

CONCLUSIONS AND CLINICAL RELEVANCE

This study has confirmed the association between overweight and obesity and symptoms of asthma. It has extended these observations to include significant associations with symptoms of eczema, but not rhinoconjunctivitis. There are complex relationships between obesity, vigorous physical activity and sedentary behaviour and the symptoms of asthma, rhinoconjunctivitis and eczema in children.

Relationships between molds and asthma suggesting non-allergic mechanisms. A rural-urban comparison

BACKGROUND

A fungal index, based on specific microbial volatile organic compounds (MVOCs) emission, was employed and related to asthma in children from rural and urban dwellings after stratification on the children atopic status.

METHODS

A nested case-control design was used to draw, from 2 cross-sectional surveys, 20 asthmatics and 26 controls living in urban areas, and 24 asthmatics and 25 controls in rural areas. MVOCs levels were assessed in the living-room during one week; during that week, children performed clinical tests and their parents were invited to fill in a questionnaire on respiratory health.

RESULTS

According to the objective fungal index, 70.5% of cases and 49.0% of controls were exposed to molds. More children with current asthma had experienced mold exposure in their homes (OR=3.38, 95% CI (1.16; 9.90)), especially amongst children living in rural areas. Atopic status modified this association: exposure to molds was found to be related to current asthma only in non-atopic children (OR=10.42, 95% CI (2.42; 44.81)). Among urban -dwelling children that could be screened at hospital, asthmatic children living in contaminated dwellings had a higher proportion of blood neutrophils and a lower FEV1 (forced expiratory volume in 1 second) than non-exposed ones.

CONCLUSION

Our findings based on an objective assessment of MVOCs suggest adverse respiratory effects of molds. Our results suggest that when looking at the aetiology of non-atopic asthma, mold exposure should be systematically assessed.

Truck traffic related air pollution associated with asthma symptoms in young boys: a cross-sectional study

OBJECTIVES

The aim of this study was to evaluate the influence of intensity of truck traffic on asthma symptomatology, and its relationship with age and gender.

STUDY DESIGN

A cross-sectional study was conducted on children and adolescents from Galicia (North-West Spain).

METHODS

Following the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC): children from schools randomly selected, answered a self-administered questionnaire included questions on asthma symptoms and some risk factors. The association between self-reported truck traffic on the street of residence and symptoms of asthma were investigated by logistic regression adjusted for body mass index, maternal education and parental smoking.

RESULTS

Almost 40% of children in Galicia are exposed to the frequent and constant passing of heavy goods vehicles. The odds of 6-7 year-old boys having severe or exercise induced asthma is tripled when they live in streets with the constant passing of heavy goods vehicles, compared with those living in streets where these vehicles never pass. In adolescents and 6-7 year-old girls, no relationship was observed between truck traffic and asthma symptoms.

CONCLUSIONS

The results of this study appear to support a distinct effect of truck traffic on asthma symptoms depending on the age and sex of the exposed population, being more harmful for young males.

Low serum high-density lipoprotein cholesterol in childhood is associated with adolescent asthma

BACKGROUND

Whilst emerging evidence from animal and cell experiments has shown high-density lipoprotein cholesterol to have anti-inflammatory effects consistent with a protective role in asthma, human studies investigating the relationship of high-density lipoprotein cholesterol with asthma have produced conflicting results.

OBJECTIVE

To examine the association between serum lipids among Cypriot children aged 11-12 years and prevalence of asthma at age 15-17 years.

METHODS

In 3982 children, we assessed serum lipids, body mass index and maximal oxygen consumption at baseline (2001-2003) and explored associations with respiratory health at follow-up (2007) using multiple logistic regression models.

RESULTS

Lower levels of high-density lipoprotein cholesterol at age 11-12 years were found in subjects who reported ever asthma (58.2 vs. 60.0 mg/dL, P = 0.005) and active asthma (57.5 vs. 59.9 mg/dL, P = 0.010) in adolescence, in comparison with their respective reference groups. Total cholesterol, low-density lipoprotein and triglycerides had no association with any of the asthma outcomes. In contrast, with estimated odds ratios of 1.89 (95% CI 1.19-3.00) and 1.89 (95% CI 1.02-3.53), ever asthma and active asthma respectively appeared particularly pronounced among those who at baseline had high-density lipoprotein cholesterol <40 mg/dL, even after adjusting for potential confounders including body mass index and maximal oxygen consumption.

CONCLUSIONS & CLINICAL RELEVANCE

Low-serum high-density lipoprotein cholesterol in childhood is associated with an increased risk for asthma in adolescence, suggesting a potential role of this lipoprotein in the pathogenesis of paediatric asthma.

Overweight does not increase asthma risk but may decrease allergy risk at school age after infantile bronchiolitis

AIM

Increasing evidence suggests that overweight children are at increased risk of asthma. The association between weight gain and allergy is more complex. The aim was to evaluate the association between overweight or obesity and asthma, allergy, bronchial reactivity or atopic sensitization at school age in children with bronchiolitis in infancy.

SUBJECTS AND METHODS

Eighty-one children hospitalized for bronchiolitis at <24 months of age attended control visits at 7.2 and 12.3 years of ages. The visits consisted of medical examinations, weight and height measurements, body mass index (BMI) calculations, skin prick tests and exercise challenge tests. BMI >1.3 SD from age- and gender-specific references meant overweight and BMI >2.0 SD obesity.

RESULTS

Current or previous overweight or obesity did not increase the risk of asthma, allergy, bronchial reactivity or atopic sensitization at 7.2 or 12.3 years of age. Previous and current obesity decreased the risk of atopic dermatitis, and current overweight and obesity decreased the risk of sensitization to outdoor allergens at 12.3 years of age.

CONCLUSION

Previous or current overweight does not increase asthma or allergy risk but current obesity may decrease allergy risk at school age after bronchiolitis in infancy.

Developments in the field of allergy in 2008 through the eyes of Clinical & Experimental Allergy

In 2008, many thousands of articles were published on the subject of allergic disease with over 200 reviews, editorials and original papers in Clinical & Experimental Allergy alone. These represent a considerable amount of data and even the most avid reader could only hope to assimilate a small fraction of this knowledge. There is therefore a pressing need for the key messages that emerge from a journal such as Clinical & Experimental Allergy to be summarized by experts in the field in a form that highlights the significance of the developments and sets them in the context of important findings in the field published in other journals. This also has the advantage of making connections between new data in conditions such as asthma, where articles often appear in different sections of the journal. As can be seen from this review, the body of work is diverse both in terms of the disease of interest and the discipline that has been used to investigate it. However, taken as a whole, we hope that the reader will gain a flavour of where the field is mature, where there remain controversies and where the cutting edge is leading.

Asthma and obesity in childhood: on the road ahead

Epidemiological data show a link between asthma and obesity, suggesting many different mechanisms that may underlie the association. However, diagnosis of asthma is often self-reported by patients or caregivers. Definition of asthma is crucial, particularly in childhood. Obesity can be associated with symptoms commonly attributed to asthma, such as wheezing, dyspnoea and sleep apnoea. Obese subjects are less fit and may have more frequent bouts of breathlessness on exertion accompanied by an exaggerated symptom perception. Therefore, the link between the two diseases should be analysed by focusing not only on reported diagnosis of asthma but also on objective markers that can better characterize the asthma phenotype. These markers should include lung function parameters, bronchial hyper-reactivity, atopic sensitization and indices of lung inflammation. As we look back and move forward, a multidisciplinary approach is increasingly necessary to understand the complexity of obesity and asthma, keeping in mind that diet and exercise could influence both diagnosis and treatment. In the meantime, in clinical settings, physicians should be cautious about diagnosing asthma in obese children on the basis of self-reported symptoms alone and should confirm the diagnosis by using objective measurements and marker evaluations that can better identify asthma phenotype and exclude overdiagnosis.

Obesity, adipokines and asthma

BACKGROUND

The prevalence of asthma and obesity is increasing concomitantly, but many aspects of this link are unclear. Our objective was to examine whether obesity is associated with asthma in three time points of life, and whether immunomodulatory adipokines, leptin and adiponectin are linked to overweight-associated asthma.

METHODS

We studied the association between obesity and asthma at ages 3-18 years [mean (SD), 10 years (5), n = 3582, year 1980], 9-24 years [16 years (5), n = 2764, 1986] and 24-39 years [32 years (5), n = 2620, 2001] in a prospective cohort study and further tested for associations with serum leptin and adiponectin concentrations. Data on allergy status, smoking and other laboratory values (serum insulin, plasma C-reactive protein and serum lipid values) were also analyzed.

RESULTS

Allergy and parental asthma were significantly associated with asthma at all ages. At ages 24-39 years, but not earlier, body mass index (BMI) (odds ratio, OR 1.05; P = 0.019) and female gender (OR 1.56; P = 0.031) were independently associated with asthma. Increase in BMI was also associated with incident asthma during adulthood (OR 1.08; P = 0.030). Levels of leptin, adiponectin or any other obesity-related biomarker were not independently associated with asthma.

CONCLUSIONS

Asthma is linked with obesity in adults, but our results do not support a significant role for leptin, adiponectin or any other obesity-related biomarker studied in this association. Other factors should be sought for better understanding the connection between obesity and asthma.

Wheezing and Asthma in childhood: an epidemiology approach

Wheezing/asthma in children is a complex problem due to its heterogeneous condition, with different pathogenic mechanisms, variations in duration and in severity; that make it difficult to totally understand. This relation between wheezing in infants and later development of asthma will be the result of alterations in the immune system maturation and congenital or acquired modifications of the airway. Several longitudinal studies have given us important information about the different phenotypes of wheezing/asthma that coexist in children. In this review, we analyse the recent potential mechanisms and risk factors for each of the three classic wheezing phenotypes presenting in children: transient, non-atopic and atopic; and we propose for consideration a fourth phenotype: overweight/obese girls with early menarche. A better understanding of those risk factors would be useful for the development of new strategies in wheezing/asthma management.