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

Associations of urinary organophosphate esters metabolites with asthma and lung function in adolescents

BACKGROUND

Organophosphate esters (OPEs) are ubiquitously detected in environments and their exposure may affect respiratory health. However, epidemiological evidence, particularly among adolescents, is very limited.

OBJECTIVE

We aimed to investigate the associations of urinary OPEs metabolites with asthma and lung function among adolescents and to identify potential effect modifiers.

METHODS

Included were 715 adolescents aged 12-19 years old participating in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Multivariable binary logistic regression and linear regression were used to assess associations with asthma and lung function, respectively. Stratified analyses were conducted to assess the effect modifications of serum sex hormones, vitamin D levels, and body mass index (BMI).

RESULTS

After multivariable adjustment, we found that bis(2-chloroethyl) phosphate (BCEP) (3rd tertile [T3] vs 1st tertile [T1], OR = 1.87, 95% CI: 1.08, 3.25; P-trend=0.029) and diphenyl phosphate (DPHP) (T3 vs T1, OR = 2.52, 95%CI: 1.25, 5.04; P-trend=0.013) were associated with elevated odds of asthma in all adolescents. Sex-stratified analyses revealed that associations of these two OPEs metabolites tended to be stronger in males. Meanwhile, BCEP and the molecular sum of OPEs metabolites (∑OPEs) were significantly associated with declined lung function, either in all adolescents or by sex. Furthermore, stratified analyses revealed that positive associations of OPEs metabolites with asthma tended to be stronger among adolescents with insufficient levels of Vitamin D (VD < 50 nmol/L), relatively high levels of total testosterone (≥356 ng/dL and ≥22.5 ng/dL for males and females, respectively), or low levels of estradiol (<19.1 pg/mL and <47.3 pg/mL for males and females, respectively).

SIGNIFICANCE

Certain urinary OPEs metabolites, especially DPHP and BCEP, were associated with elevated odds of asthma and declined lung function in adolescents. Such associations might be partly modified by levels of VD and sex steroid hormones.

IMPACT STATEMENT

The observed associations of urinary OPEs metabolites with increased risk of asthma and declined lung function highlight the potential hazard of OPEs exposure to respiratory health among adolescents.

Combined with multiplex and network analysis to reveal the key genes and mechanisms of nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) has become a significant cause of chronic liver disease in developed countries, as a result of the worldwide trend of obesity and associated metabolic syndrome. Obesity and high-fat diet (HFD) are very common in patients with NAFLD. However, how to screen out key differentially expressed genes (DEGs) is a challenging task. The purpose of this study is to study the screen of key genes and pathways of HFD on the formation process of non-alcoholic fatty liver through network pharmacological analysis.

METHODS

In this study, 173 genes associated with NAFLD were collected from the Gene Expression Omnibus (GEO) database. To find significant genes and pathways, combine network clustering analysis, topology analysis, and pathway analysis.

RESULTS

The results showed that there were four key signaling pathways related to HFD, including complement cascade, Atorvastatin ADME, Asthma and Aflatoxin activation and detoxification. In addition, we identified six representative key genes, including Ccl5, Tlr2, Cd274, Cxcl10, Cxcl9 and Cd74, and screened three intersecting genes in Mus musculus and Homo sapiens sample, including C3, F2 and C7.

CONCLUSIONS

In conclusion, our study constructed the NAFLD gene regulatory network of C57BL/6J mice for the first time and jointly analyzed the Mus musculus samples and Homo sapiens samples. It provides new insights for identifying potential biomarkers and valuable therapeutic clues, and puts forward a new method for web-based research. These findings may provide potential targets for early diagnosis, effective therapy and prognostic markers of NAFLD.

Effect of Obesity on Lung Function in the Pediatric and Adult Populations with Asthma: A Review

Obesity and asthma are major global health concerns, particularly in industrialized nations. Obesity has been shown to have detrimental effects on the respiratory system and lung function owing to metabolic issues and immunological consequences. Research has indicated that obese patients with asthma (atopic or T2-high and non-atopic or T2-low) have diminished lung function in terms of functional residual capacity (FRC), residual volume (RV), expiratory reserve volume (ERV), the FEV1/FVC ratio, and FEF 25-75% due to mechanical fat loading on the diaphragm and central adiposity when compared to non-obese asthmatic patients. Therefore, it is plausible that changes in lung function are the result of a combination of mechanical (fat loading on the diaphragm, central adiposity, bronchial hyper-reactivity, and an increase in cholinergic tone), environmental (diet and exercise), and inflammatory factors (local and systemic), which can lead to the obesity-related asthma phenotype characterized by severe asthma symptoms, poor response to corticosteroid treatment, loss of lung function, and poor quality of life from an early age.

Mechanistic Links Between Obesity and Airway Pathobiology Inform Therapies for Obesity-Related Asthma

Obesity-related asthma is associated with a high disease burden and a poor response to existent asthma therapies, suggesting that it is a distinct asthma phenotype. The proposed mechanisms that contribute to obesity-related asthma include the effects of the mechanical load of obesity, adipokine perturbations, and immune dysregulation. Each of these influences airway smooth muscle function. Mechanical fat load alters airway smooth muscle stretch affecting airway wall geometry, airway smooth muscle contractility, and agonist delivery; weight loss strategies, including medically induced weight loss, counter these effects. Among the metabolic disturbances, insulin resistance and free fatty acid receptor activation influence distinct signaling pathways in the airway smooth muscle downstream of both the M2 muscarinic receptor and the β2 adrenergic receptor, such as phospholipase C and the extracellular signal-regulated kinase signaling cascade. Medications that decrease insulin resistance and dyslipidemia are associated with a lower asthma disease burden. Leptin resistance is best understood to modulate muscarinic receptors via the neural pathways but there are no specific therapies for leptin resistance. From the immune perspective, monocytes and T helper cells are involved in systemic pro-inflammatory profiles driven by obesity, notably associated with elevated levels of interleukin-6. Clinical trials on tocilizumab, an anti-interleukin antibody, are ongoing for obesity-related asthma. This armamentarium of therapies is distinct from standard asthma medications, and once investigated for its efficacy and safety among children, will serve as a novel therapeutic intervention for pediatric obesity-related asthma. Irrespective of the directionality of the association between asthma and obesity, airway-specific mechanistic studies are needed to identify additional novel therapeutic targets for obesity-related asthma.

Association of fractional exhaled nitric oxide with asthma morbidity in urban minority children

OBJECTIVE

Fractional exhaled nitric oxide (FeNO) is a well-established measure of allergic airway inflammation and possible useful adjunct disease management tool. We investigated the association of baseline and follow-up FeNO measurements with disease burden in minority children with persistent asthma.

METHODS

A retrospective chart review was conducted on 352 African American and Hispanic children seen at an urban Asthma Center in Bronx, NY. Demographic, clinical characteristics, and pulmonary function tests (PFTs) were compared between children with low, intermediate, and high baseline FeNO levels. Among 95 children with subsequent follow up visits, associations of change in FeNO with demographics, clinical characteristics, and PFTs were examined using mixed effects linear regression models.

RESULTS

A higher proportion of children with intermediate (54%) and high FeNO (58%) levels had lower airways obstruction compared to those with low FeNO levels (33%). Children with intermediate FeNO levels had more annual hospitalizations (2.8 ± 6.2) compared to those with low and high FeNO levels (1.3 ± 2.8 and 1.3 ± 2.5). These associations did not differ between ethnicities. An increase in FeNO over time was associated with higher BMI z-scores (β = 6.2, 95% CI: 1.0 to 11.4) and two or more hospitalizations in the past year (β = 16.1, 95% CI: 1.5 to 30.8).

CONCLUSIONS

Intermediate and high FeNO levels are associated with lower airways obstruction and hospitalizations. Initial and serial FeNO measurements can be a useful adjunctive tool in identifying asthma-related morbidity in urban African American and Hispanic children.

Obesity-related asthma in children and adolescents

There is substantial epidemiological and experimental evidence of an obesity-related asthma phenotype. Compared to children of healthy weight, children with obesity are at higher risk of asthma. Children with obesity who have asthma have greater severity and poorer control of their asthma symptoms, more frequent asthma exacerbations, and overall lower asthma-related quality of life than children with asthma who have a healthy weight. In this Review, we examine some of the latest evidence on the characteristics of this phenotype and its main underlying mechanisms, including genetics and genomics, changes in airway mechanics and lung function, sex hormone differences, alterations in immune responses, systemic and airway inflammation, metabolic dysregulation, and modifications in the microbiome. We also review current recommendations for the treatment of these children, including in the management of their asthma, and current evidence for weight loss interventions. We then discuss initial evidence for potential novel therapeutic approaches, such as dietary modifications and supplements, antidiabetic medications, and statins. Finally, we identify knowledge gaps and future directions to improve our understanding of asthma in children with obesity, and to improve outcomes in these susceptible children. We highlight important needs, such as designing paediatric-specific studies, implementing large multicentric trials with standardised interventions and outcomes, and including racial and ethnic groups along with other under-represented populations that are particularly affected by obesity and asthma.

Asthma interactions between obesity and other risk factors

OBJECTIVE

To review and critically discuss published evidence on interactions between obesity and selected risk factors on asthma in children and adults, and to discuss potential future directions in this field.

DATA SOURCES

National Library of Medicine (via PubMed) STUDY SELECTION: A literature search was conducted for human studies on obesity and selected interactions (with sex, race and ethnicity, socioeconomic status, indoor and outdoor pollutants, depression, anxiety, and diet) on asthma. Studies that were published in English and contained a full text were considered for inclusion in this review.

RESULTS

Current evidence supports interactions between obesity and outdoor and indoor air pollutants (including second-hand smoke [SHS]) on enhancing asthma risk, although there are sparse data on the specific pollutants underlying such interactions. Limited evidence also suggests that obesity may modify the effects of depression or anxiety on asthma, whereas little is known about potential interactions between obesity and sex-hormone levels or dietary patterns.

CONCLUSION

Well-designed observational prospective studies (eg, for pollutants and sex hormones) and randomized clinical trials (eg, for the treatment of depression) should help establish the impact of modifying coexisting exposures to reduce the harmful effects of obesity on asthma. Such studies should be designed to have a sample size that is large enough to allow adequate testing of interactions between obesity and risk factors that are identified a priori and thus, well characterized, using objective measures and biomarkers (eg, urinary or serum cotinine for SHS, epigenetic marks of specific environmental exposures).

Association between obesity and lung function in South African adolescents of African Ancestry

Background

There is a growing body of literature on the increasing prevalence of obesity in adolescents of Sub-Saharan African ancestry. However, limited data is available on the impact of obesity on pulmonary function. This study assessed the relationship between obesity and lung function in South African adolescents of African ancestry.

Methods

This was a cross-sectional study involving 10–14 year old adolescents recruited from middle schools of the Eastern Cape Province of South Africa. Anthropometric measurements were performed. Body mass index (BMI) was converted to percentiles for age and sex and used to classified obesity. Spirometry was performed to assess lung function. Chi-square test of association and binary regression analysis were used to assess the relationship between obesity and airway obstruction. Adjusted linear regression was used to determine the relationship between obesity and lung function parameters.

Results

A total of 540 adolescents were recruited for the study among which 77 (14.3%) were obese. Lung function parameters: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁) were higher (p < 0.001) in obese than in non-obese adolescents while peak expiratory flow (PEF) % and FEV₁/FVC ratio were lower (p < 0.05) in obese than non-obese adolescents. Obesity was associated (χ2 = 9.614; p < 0.01) with airway obstruction and obese adolescents were over 1.5 times more likely to have pulmonary obstruction (OR: 1.57; p < 0.05) than their non-obese counterparts. Anthropometric measures were positively associated (p < 0.05) with FVC, FEV1, PEF and/or FEV_25-75 but negatively associated with FEV₁/FVC ratio.

Conclusions

Obesity was associated with airway obstruction in South Africa adolescents of African ancestry.

A nationwide survey of the association between nonalcoholic fatty liver disease and the incidence of asthma in Korean adults

Background

Asthma and nonalcoholic fatty liver disease (NAFLD) are chronic diseases known to be associated with metabolic abnormalities. We aimed to clarify the association between NAFLD and asthma incidence in a large population-based cohort.

Methods and findings

We selected 160,603 individuals without comorbidities from the National Health Insurance Service-National Sample cohort between 2009 and 2014. NAFLD was defined using a surrogate marker, fatty liver index (FLI). During a median of 5.08 years’ follow-up, 16,377 subjects (10.2%) were newly diagnosed with asthma and categorized into three groups according to FLI. The cumulative incidence of asthma was higher in subjects with higher vs. lower FLIs (FLI < 30, 10.1%; 30 ≤ FLI < 60, 10.8%; FLI ≥ 60, 10.5%). Higher FLI was associated with an increased incidence of asthma (Hazard ratios (HR)_{highest vs. lowest FLI}, 1.25; 95% CI, 1.15–1.36). The results using another definition of NAFLD, as measured by the hepatic steatosis index (HSI), were similar to the primary results. This association was more pronounced in women than in men (HR 1.46; 95% CI, 1.13–1.64 vs. HR 1.07; 95% CI, 0.94–1.20).

Conclusions

This study demonstrated that NAFLD, as measured by FLI and HSI, may influence the incidence rates of asthma in adults, especially in women.

Investigating obesity-related risk factors for childhood asthma

BACKGROUND

We tested the hypothesis that multiple obesity-related risk factors (obesity, physical activity, cardiopulmonary physical fitness, sleep-disorder breathing (SDB), and sleep quality) are associated with childhood asthma using a Mendelian randomization (MR) design. Furthermore, we aim to investigate whether these risk factors were associated with incident asthma prospectively.

METHODS

In total, 7069 children aged 12 from the Taiwan Children Health Study were enrolled in the current study. Cross-sectional logistic regression, one-sample MR, summary-level MR sensitivity analyses, and prospective survival analyses were used to investigate each causal pathway.

RESULTS

In MR analysis, three of the five risk factors (obesity, SDB, and sleep quality) were associated with asthma, with the highest effect sizes per inter-quartile range (IQR) increase observed for sleep quality (odds ratio [OR] = 1.42; 95% confidence interval [CI]: 1.06 to 1.92) and the lowest for obesity (OR = 1.08; 95% CI: 1.00-1.16). In the prospective survival analysis, obesity showed the highest risk of incident asthma per IQR increase (hazard ratio [HR] = 1.28; 95% CI: 1.05 to 1.56), followed by SDB (HR = 1.18; 95% CI: 1.08 to 1.29) and sleep quality (HR = 1.10; 95% CI: 1.03 to 1.17).

CONCLUSION

Among the examined factors, the most plausible risk factors for asthma were obesity, SDB, and poor sleep quality. For the prevention of childhood asthma, relevant stakeholders should prioritize improving children's sleep quality and preventing obesity comorbidities such as SDB.

Relationship of Nutritional Status and Spirometric Parameters in Children with Bronchial Asthma

The potential mechanisms of bronchial asthma (BA) negative modification under the influence of obesity are currently being actively studied. However, at present, the effect of nutritional status on bronchial obstruction in children with BA cannot be considered established. In this regard, the purpose of this work was to study the relationship of spirometric parameters reflecting bronchial patency with nutritional status in children with asthma.

Association between exposure to polyfluoroalkyl chemicals and increased fractional exhaled nitric oxide in adults

BACKGROUND

Perfluoroalkyl chemicals (PFCs) are widely detected in the environment and human body, and they have been linked to asthma and a number of respiratory responses in children and mice. However, no previous studies have investigated the association between exposure to PFCs and airway inflammation in adults.

OBJECTIVES

To evaluate the associations between serum PFCs and fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation, in adults.

METHODS

A cross-sectional study of 3630 adults aged 20-79 years who participated in the National Health and Nutrition Examination Survey (NHANES, 2007-2012) was conducted. Serum concentrations of five major PFCs were measured using SPE-HPLC-TIS-MS/MS method, including perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorodecanoic acid (PFDE). The detection rates of them were all >85%. Weighted multivariable linear regression and Bayesian kernel machine regression (BKMR) analyses were applied to examine the associations between serum PFCs and FeNO.

RESULTS

After adjusted for potential confounding factors, linear regression analyses found that compared with their lowest tertiles, highest tertiles of PFOS, PFDE and PFOA were significantly associated with 5.02% (95% CI: 1.40%, 8.77%), 3.77% (95% CI: 0.30%, 7.36%) and 6.34% (95% CI: 2.81%, 10.01%) increases in FeNO, respectively. The second tertile of PFNA was significantly correlated with a 4.79% (95% CI: 1.41%, 8.29%) increase in FeNO compared with the lowest tertile. In the BKMR analysis, the mixture effect of PFCs on FeNO increased significantly when the PFC levels were at or above the 60th percentiles compared to those at their medians. PFOS and PFOA displayed significant positive single-exposure effects on FeNO when all the other PFCs are set at a particular threshold.

CONCLUSIONS

This study provided preliminary evidence that serum PFCs were positively associated with increased FeNO in adults.

The impact of obesity on immune function in pediatric asthma

PURPOSE OF REVIEW

Pediatric obese asthma is a complex disease that remains poorly understood. The increasing worldwide incidence of both asthma and obesity over the last few decades, their current high prevalence and the challenges in treating obese asthmatic patients all highlight the importance of a better understanding of the pathophysiological mechanisms in obese asthma. While it is well established that patients with obesity are at an increased risk of developing asthma, the mechanisms by which obesity drives the onset of asthma, and modifies existing asthma, remain unclear. Here, we will focus on mechanisms by which obesity alters immune function in asthma.

RECENT FINDINGS

Lung parenchyma has an altered structure in some pediatric obese asthmatics, known as dysanapsis. Central adiposity is linked to reduced pulmonary function and a better predictor of asthma risk in children than BMI. Obesity in young children is associated with an increased risk of developing asthma, as well as early puberty, and hormonal alterations are implicated in obese asthma. Obesity and asthma each yield immunometabolic dysregulation separately and we are learning more about alterations in these pathways in pediatric obese asthma and the potential impact of bariatric surgery on those processes.

SUMMARY

The recent progress in clarifying the connections between childhood obesity and asthma and their combined impacts on immune function moves us closer to the goals of improved understanding of the pathophysiological mechanisms underpinning obese asthma and improved therapeutic target selection. However, this common inflammatory disease remains understudied, especially in children, and much remains to be learned.

Paediatric obesity-related asthma: Disease burden and effects on pulmonary physiology

The prevalence of asthma and obesity in children has been steadily increasing globally over the past several decades, with increased concern in low and middle income countries. In this review, we summarize the current literature on these two parallel epidemics and explore the relationship between paediatric obesity and asthma in the paediatric population. Finally, we focus on the current literature as it relates to underlying physiologic alterations and changes in pulmonary function for children with obesity and asthma.

Contribution of systemic and airway immune responses to pediatric obesity-related asthma

Childhood obesity contributes to many diseases, including asthma. Although the precise mechanism by which obesity causes asthma is not known, there is literature to suggest that innate and adaptive systemic and airway immune responses in obese children with asthma differ from those in normal-weight children with asthma. Both non-allergic or non-T2 phenotype with systemic T helper (Th)1 polarization and allergic Th cell responses have been reported in childhood obesity-related asthma. There is preliminary evidence to suggest that genetic and epigenetic mechanisms contribute to these immune responses. Initial investigations into the biology of non-T2 immune responses have identified upregulation of genes in the CDC42 pathway. CDC42 is a RhoGTPase that plays a key role in Th cell physiology, including preferential naïve Th cell differentiation to Th1 cells, as well as cytokine production and exocytosis. These novel pathways are promising findings to direct targeted therapy development for obesity-related asthma to address the disease burden.

The Effect of Adiposity Markers on Fractional Exhaled Nitric Oxide (FeNO) and Pulmonary Function Measurements

Background

The effect of increasing body weight on pulmonary function and the fractional exhaled nitric oxide (FeNO) remains controversial and the role of different body compositions in the relationship between obesity with pulmonary function and FeNO is still unrevealed. Thus, we aim to determine the effect of overweight/obesity on lung function and FeNO, focusing on the relationship with different body compositions.

Methods

Eighty-two non-smoker students (20 ± 1.9 years) were divided into two groups: 38 subjects with normal weight (BMI = 18.5–24.99) and 44 overweight/obese subjects (BMI ≥ 25). Spirometric parameters and FeNO were measured and compared between groups and were correlated with different adiposity markers.

Results

FeNO measurements were elevated in the overweight/obese group [median (IQR) 19.5 (13)] in comparison to the normal weight group [11 (10), p value = 0.017]. A positive correlation was found between FeNO measurements and body mass index (BMI), waist circumference, hip circumference, waist-hip ratio, and visceral fat percentage (all p values < 0.01). The absolute values of forced vital capacity (FVC) forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF), forced expiratory flow during mid-expiration (FEF_25–75%), and FEV₁/FVC ratio showed no significant differences between groups. However, the percentage of the predicted values of FEV₁ and FVC was significantly higher and the value of percentage predicted FEF_25–75% was reduced significantly in the overweight/obese subjects.

Conclusion

Increase in BMI could significantly increase airway inflammation as measured by FeNO, as well as on distal airway function as determined by the percentage predicted values of FEF_25–75%. A significant correlation was also identified between visceral fat and FeNO measurement.

A Multi-Omics Approach Reveals New Signatures in Obese Allergic Asthmatic Children

Background: Asthma is a multifactorial condition where patients with identical clinical diagnoses do not have the same clinical history or respond to treatment. This clinical heterogeneity is reflected in the definition of two main endotypes. We aimed to explore the metabolic and microbiota signatures that characterize the clinical allergic asthma phenotype in obese children. Methods: We used a multi-omics approach combining clinical data, plasma and fecal inflammatory biomarkers, metagenomics, and metabolomics data in a cohort of allergic asthmatic children. Results: We observed that the obese allergic asthmatic phenotype was markedly associated with higher levels of leptin and lower relative proportions of plasma acetate and a member from the Clostridiales order. Moreover, allergic children with a worse asthma outcome showed higher levels of large unstained cells, fecal D lactate and D/L lactate ratio, and with a higher relative proportion of plasma creatinine and an unclassified family member from the RF39 order belonging to the Mollicutes class. Otherwise, children with persistent asthma presented lower levels of plasma citrate and dimethylsulfone. Conclusion: Our integrative approach shows the molecular heterogeneity of the allergic asthma phenotype while highlighting the use of omics technologies to examine the clinical phenotype at a more holistic level.

Asthma and Obesity in Children

Asthma and obesity are two major chronic diseases in children and adolescents. Recent scientific evidence points out a causative role of obesity in asthma predisposition. However, studies assessing the real impact of excessive weight gain on lung function in children have shown heterogeneous results. In this review, the pathological mechanisms linking obesity and development of asthma in children are summarized and factors influencing this relationship are evaluated. Common disease modifying factors including age, sex, ethnicity, development of atopic conditions, and metabolic alterations significantly affect the onset and phenotypic characteristics of asthma. Given this, the impact of these several factors on the obesity–asthma link were considered, and from revision of the literature we suggest the possibility to define three main clinical subtypes on the basis of epidemiological data and physiological–molecular pathways: obese-asthmatic and atopy, obese-asthmatic and insulin-resistance, and obese-asthmatic and dyslipidemia. The hypothesis of the different clinical subtypes characterizing a unique phenotype might have an important impact for both future clinical management and research priorities. This might imply the necessity to study the obese asthmatic child with a “multidisciplinary approach”, evaluating the endocrinological and pneumological aspects simultaneously. This different approach might also make it possible to intervene earlier in a specific manner, possibly with a personalized and tailored treatment. Surely this hypothesis needs longitudinal and well-conducted future studies to be validated.

Functional Genomics of the Pediatric Obese Asthma Phenotype Reveal Enrichment of Rho-GTPase Pathways

Rationale: Obesity-related asthma disproportionately affects minority children and is associated with nonatopic T-helper type 1 (Th1) cell polarized inflammation that correlates with pulmonary function deficits. Its underlying mechanisms are poorly understood.Objectives: To use functional genomics to identify cellular mechanisms associated with nonatopic inflammation in obese minority children with asthma.Methods: CD4+ (cluster of differentiation 4-positive) Th cells from 59 obese Hispanic and African American children with asthma and 61 normal-weight Hispanic and African American children with asthma underwent quantification of the transcriptome and DNA methylome and genotyping. Expression and methylation quantitative trait loci revealed the contribution of genetic variation to transcription and DNA methylation. Adjusting for Th-cell subtype proportions discriminated loci where transcription or methylation differences were driven by differences in subtype proportions from loci that were independently associated with obesity-related asthma.Measurements and Main Results: Obese children with asthma had more memory and fewer naive Th cells than normal-weight children with asthma. Differentially expressed and methylated genes and methylation quantitative trait loci in obese children with asthma, independent of Th-cell subtype proportions, were enriched in Rho-GTPase pathways. Inhibition of CDC42 (cell division cycle 42), one of the Rho-GTPases associated with Th-cell differentiation, was associated with downregulation of the IFNγ, but not the IL-4, gene. Differential expression of the RPS27L (40S ribosomal protein S27-like) gene, part of the p53/mammalian target of rapamycin pathway, was due to nonrandom distribution of expression quantitative trait loci variants between groups. Differentially expressed and/or methylated genes, including RPS27L, were associated with pulmonary function deficits in obese children with asthma.Conclusions: We found enrichment of Rho-GTPase pathways in obese asthmatic Th cells, identifying them as a novel therapeutic target for obesity-related asthma, a disease that is suboptimally responsive to current therapies.

Overweight Proxies Are Associated with Atopic Asthma: A Matched Case-Control Study

BACKGROUND

Many studies have documented a link between overweight and asthma in children with contradictory results regarding the best way to measure overweight. Moreover, often, the dynamic development of atopy, overweight, and asthma is controlled for age dependency insufficiently.

OBJECTIVE

This study assesses and compares the associations of overweight measured as waist circumference, waist to height ratio (WHtR), neck circumference, and body mass index with the occurrence of asthma - best possibly controlling for age-dependencies of these parameters.

METHODS

From a sample of 2,511 children aged 6-17 years, we matched 157 children with asthma with 2 controls (n = 471) according to age and atopy status and performed conditional logistic regression analyses. We further investigated the role of known influencing factors of asthma occurrence.

RESULTS

In children with atopy, all overweight proxies were consistently positively associated with asthma. Statistical significance was reached for WHtR-SD score (OR 1.26, 95% CI 1.03-1.54, p = 0.025) and persisted when further covariates, such as birth weight or social status, were added to the model. Groups of atopic versus nonatopic participants do not differ in levels of interleukin-6 or high-sensitivity C-reactive protein.

CONCLUSION

In our cohort, overweight seems to carry a risk for asthma only if accompanied with atopy. We call for more strict age matching in pediatric cohort studies and longitudinal studies for a better understanding for causal links of overweight, atopy, and asthma.

Obesity and childhood asthma

PURPOSE OF REVIEW

Asthma is a common chronic disease of the airways characterized by recurrent respiratory symptoms, bronchoreactivity, and airway inflammation. The high toll on quality of life has led to sustained efforts to understand the factors leading to asthma inception and poor disease control. Obesity is another increasingly common pediatric disease, which appears to increase the risk for incident asthma and worsened disease severity. Currently, our understanding of how obesity affects asthma risk and affects its phenotypic characteristics remains incomplete. The current review describes our current understanding of the epidemiology, clinical characteristics, and management considerations of obesity-related asthma in children.

RECENT FINDINGS

The epidemiologic relationship between obesity in children and incident asthma remains confusing despite numerous longitudinal cohort studies, and appears to be influenced by early life exposures, patterns of somatic growth and underlying familial risks of allergic disease. Children with comorbid obesity and asthma demonstrate diverse phenotypic characteristics which are still becoming clear.

SUMMARY

Like any child with asthma, a child with comorbid obesity requires an individualized approach adhering to current best-practice guidelines and an understanding of how obesity and asthma may interact.

[Obesity and asthma: Mechanisms and therapeutic options]

Asthma and obesity are both common conditions, which lead to a substantial public health burden. The obese-asthma phenotype is characterized by poor asthma control, impaired lung function and decreased efficacy of inhaled treatment. However, this phenotype is highly heterogeneous and involves numerous mechanisms, including systemic inflammation and adipokines. A role for microbiota modifications and genetics has been suggested. Obese-asthma patient management currently consists in weight loss and usual anti-asthmatic treatment. New therapeutic options are being evaluated.

Measurement of nitric oxide and assessment of airway diseases in children: an update

INTRODUCTION

Nitric oxide (NO) is a gas synthesized by the inducible NO synthase enzyme in airway cells and it is thought to make important functions in the airway inflammation of several respiratory diseases.

EVIDENCE ACQUISITION

This current study is a review of the literature from 1990 to present about NO and its use in clinical practice. The databases used were PubMed, Scopus, and Cochrane Library.

EVIDENCE SYNTHESIS

At the respiratory level there are three different measurements sites of NO: nNO (nasal nitric oxide), FeNO (exhaled fraction of nitric oxide), CaNO (alveolar nitric oxide). Each of them is produced at different levels of the respiratory tract and is involved in various diseases. nNO finds its use, principally, in the allergic rhinitis in fact it can be used as a measure of therapeutic efficacy, but not for the evaluation of the severity; also in primary ciliary dyskinesia (PCD), where high levels exclude the disease, and in chronic rhinosinusitis, but it is not currently used as a diagnostic or prognostic marker. FeNO has a greatest use in bronchial asthma, particularly, it is considered a non-invasive biomarker to identify and to monitor airway inflammation but currently, there is not a consensus on the use of the FeNO in the management of asthma treatment. Finally, CaNO is the least used in clinical practice, because lack of standardization of measurement techniques.

CONCLUSIONS

Nitric oxide is a sensitive indicator of the presence of airway inflammation and ciliary dysfunction, although some studies have shown varying or conflicting results.

Lung function, obesity and physical fitness in young children: The EXAMIN YOUTH study

OBJECTIVE

The prevalence of obesity and physical inactivity in children are increasing globally. The study aimed to investigate the association of obesity and cardiorespiratory fitness (CRF) with patterns of lung function in young children.

METHODS

In this cross-sectional study, lung function, body mass index (BMI), blood pressure (BP) and CRF (shuttle run stages) were measured in an unselected cohort of 1246 children aged 7.2 ± 0.4 years. All parameters and lung function, such as the ratio of forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC), were assessed by standardized procedures for children. Statistical models were applied for systematic adjustment of potential confounders.

RESULTS

Obese children had significantly higher FEV1 (Coef. (95% CI) (1.57 (1.50; 1.64) L) and FVC (1.75 (1.67; 1.83) L) compared to normal weight children (1.38 (1.37; 1.40) L; (1.53 (1.51; 1.54) L, respectively). However, with each unit increase of BMI, FEV1/FVC decreased (-0.003 (-0.005; -0.001)) due to a disproportional increase in FVC compared to FEV1. Per stage increase of CRF, FEV1 (0.017 (0.008; 0.025) L) and FVC increased (0.022 (0.012; 0.031) L)). In obese children, higher CRF was independently associated with higher FEV1/FVC (0.03 (0.5E-4; 0.06)) due to a higher increase of FEV1 over FVC with increasing fitness.

CONCLUSIONS

The decrease of FEV1/FVC with increasing BMI suggests that childhood obesity is associated with an imbalance of ventilation and airway flow. In children with obesity, higher CRF is associated with an improved FEV1/FVC ratio. Physical exercise programs may have the potential to improve patterns of lung function in children with obesity.

[Obesity in childhood: What are the respiratory risks?]

In childhood and adolescence overweight is defined as a body mass index (BMI) above the 97th percentile for age and sex, according to the curves established by the International Obesity Task Force (IOTF). In France, it is estimated that 25 % of children under 18 years old are overweight. Overweight and obesity in this population are multifactorial, with an important influence of genetic factors, modulated by pre and post-natal (maternal smoking), societal and psychological determinants. The impact of obesity on respiratory function in children is mostly characterized by a decreased FEV1/FCV. Moreover, several studies have shown an association between asthma and overweight/obesity, with a pejorative impact of BMI on asthma control. However, asthma is still poorly characterized in this population, and the determinants of bronchial obstruction seem to differ from non-obese children, with less eosinophilic inflammation. Obstructive sleep apnea syndrome (OSAS) is a frequent complication of obesity, affecting up to 80% of obese children and adolescents. It has a specific polysomnographic definition in children. Symptoms are similar to adult OSAS, but with cognitive and neurobehavioral alterations often more important in adolescents. The treatment consists in ENT surgery when indicated (with systematic post-operative polysomnography), and nocturnal continuous positive airway pressure (CPAP). The obesity-hypoventilation syndrome (OHS) has the same definition in children as in adults and affects up to 20% of obese patients. Treatment consists in nocturnal ventilation using bilevel positive airway pressure (BiPAP). Finally, in some extreme cases, bariatric surgery can be performed. The indication should be discussed in a specialised paediatric reference centre.

Weight Status and Respiratory Health in Asthmatic Children

In this study,we explored the effect of adiposity as measured by BMI on lung function in 72 asthmatic school children (5-12 years) using baseline data from the Mediterranean diet enriched with fatty fish intervention study. Bronchial function was assessed using spirometry and fractional exhaled nitric oxide (FeNO). BMI categories were classified as normal and overweight/obese based on International Obesity Task Force cut-offs. Weak correlations were observed between BMI and FVC (p = 0.013) and FEV₁ (p = 0.026). Median FeNO was lower in the overweight/obese as compared to normal weight group (p = 0.027). Linear regression showed an increment in FEF_25-75% in the overweight/obese group as compared to normal weight after controlling for confounders namely age, height, sex, regular physical activity, medication and KIDMED score (p = 0.043; β = 11.65 units, 95% CI 0.36-22.94), although with no effect on FeNO. In conclusion, the findings of this study suggest that excess body weight could impact pulmonary dynamics in childhood asthma.

Association of pediatric obesity and asthma, pulmonary physiology, metabolic dysregulation, and atopy; and the role of weight management

Introduction: Obesity affects about 40% of US adults and 18% of children. Its impact on the pulmonary system is best described for asthma. Areas covered: We reviewed the literature on PubMed and Google Scholar databases and summarize the effect of obesity, its associated metabolic dysregulation and altered systemic immune responses, and that of weight gain and loss on pulmonary mechanics, asthma inception, and disease burden. We include a distinct approach for diagnosing and managing the disease, including pulmonary function deficits inherent to obesity-related asthma, in light of its poor response to current asthma medications. Expert opinion: Given the projected increase in obesity, obesity-related asthma needs to be addressed now. Research on the contribution of metabolic abnormalities and systemic immune responses, intricately linked with truncal adiposity, and that of lack of atopy, to asthma disease burden, and pulmonary function deficits among obese children is fairly consistent. Since current asthma medications are more effective for atopic asthma, investigation for atopy will guide management by distinguishing asthma responsive to current medications from the non-responsive disease. Future research is needed to elucidate mechanisms by which obesity-mediated metabolic abnormalities and immune responses cause medication non-responsive asthma, which will inform repurposing of medications and drug discovery.

Phenotypes favoring fractional exhaled nitric oxide discordance vs guideline-based uncontrolled asthma

BACKGROUND

Despite potential value of identification of allergic inflammation with fractional exhaled nitric oxide (FeNO) in managing asthma, randomized clinical trials have not consistently shown better outcomes compared with guideline management alone.

OBJECTIVE

To assess the effectiveness of FeNO vs non-FeNO-based therapeutic algorithms in managing asthma, and the phenotypic profile associated with FeNO >35 ppb yet well controlled by guidelines, as a potential model to predict better FeNO-based algorithm outcomes.

METHODS

This is a randomized controlled study (RCT) in 88 high-risk children with asthma 7 to 18 years of age across 352 visits over a 1-year period. Generalized estimating equations analysis assessed algorithm group differences in outcomes and characteristics associated with higher odds uncontrolled by FeNO alone in the treatment decision algorithm.

RESULTS

The FeNO treatment algorithm did not show superiority in reducing exacerbations and morbidity (P > .05). Phenotypes that more than doubled the odds FeNO alone identified uncontrolled asthma included adolescence, non-adherence, high atopy (>6+), and baseline FeNO >35 ppb, whereas obesity, FEF_25-75% < 65% predicted, and bronchodilator response >10% decreased the odds. Uncontrolled asthma by FeNO alone (F) vs guidelines alone (G) showed overall F/G > 1.0 in adolescents, but <1.0 in younger patients unless the FeNO threshold was reduced to >20 ppb.

CONCLUSION

Our study suggests that age and phenotypes play a key role in FeNO discordance compared with the conventional guideline-based uncontrolled asthma. The FeNO-based therapeutic algorithm, if confirmed further, could provide the clinician with an effective asthma management tool. The clinical implication could improve future FeNO-based RCTs and treatment decision algorithms in managing asthma by considering phenotypes and age-dependent FeNO thresholds.

The Association Between ENT Diseases and Obesity in Pediatric Population: A Systemic Review of Current Knowledge

Obesity in pediatric population is an important global problem. The prevalence of obesity in children is dramatically rising. According to World Health Organization, about 41 million children under the age of 5 years are obese or overweight worldwide. Overweight and obesity are well-known risk factors for a number of health disorders. Diseases commonly observed in this group of patients are metabolic disorders, type 2 diabetes mellitus, cardiovascular diseases, fatty liver disease, musculoskeletal problems, and many others. The main aim of this study was to present the current knowledge of the association between childhood obesity and common otorhinolaryngological disorders. It is suggested that obese children are more prone to suffer from otorhinolaryngological illnesses than the lean ones. Obesity may predispose to otorhinolaryngological diseases in various ways. It strongly interferes with the immune system (increases serum levels of interleukin 6, tumor necrosis factor, C-reactive protein, and leptin and reduces adiponectin concentration) affecting organs of the upper respiratory tract. Additionally, obesity induces mechanical disorders in the upper airways. According to our review, obesity predisposes to otitis media with effusion, acute otitis media, recurrent otitis media, obstructive sleep apnea, sensorineural hearing loss, adenotonsillar hypertrophy, and post-/perioperative complications after adenotonsillectomy. Obesity in children significantly correlates with both obstructive sleep apnea (OSA) and asthma and constitutes a significant component of "OSA, obesity, asthma" triad.

Metabolic Dysregulation, Systemic Inflammation, and Pediatric Obesity-related Asthma

Obesity-related asthma is a distinct pediatric asthma phenotype. It is associated with higher disease burden, lower pulmonary function, and suboptimal response to current asthma medications. Recent studies have made inroads into elucidating its pathophysiology. Systemic immune responses in obese children with asthma are skewed to a nonatopic T-helper cell type 1 (Th1) pattern that correlates with pulmonary function deficits. The prevalence of metabolic dysregulation is also higher among obese children with asthma than among normal-weight children with asthma. Insulin resistance and dyslipidemia, particularly low levels of high-density lipoprotein (HDL), are associated with lower airway obstruction and low expiratory reserve volume. These associations are independent of truncal and general adiposity and thereby suggest a direct association between metabolic abnormalities and pulmonary function. Furthermore, insulin resistance is associated with Th1 polarization, whereas low HDL is associated with monocyte activation. Although insulin resistance mediates the association of Th1 polarization with pulmonary function, HDL does not have a similar influence on the association of monocyte activation with pulmonary function. Together, these recent studies have paved the way to the understanding of obesity-related asthma as a distinct asthma phenotype and have begun to identify the complex relationships between metabolic dysregulation, systemic inflammation, and pulmonary function deficits in obese children with asthma. Studies are now needed to elucidate the mechanisms that link metabolic dysregulation and systemic immune responses to pulmonary function.

A novel nutritional intervention improves lung function in overweight/obese adolescents with poorly controlled asthma: the Supplemental Nutrition in Asthma Control (SNAC) pilot study

Asthma in the obese is often severe, difficult to treat, and characterized by less eosinophilic inflammation than asthma in the nonobese. Obesity-associated metabolic dysregulation may be a causal factor. We previously reported that a nutrient- and fiber-dense bar [Children's Hospital Oakland Research Institute (CHORI)-bar], which was designed to fill gaps in poor diets, improved metabolism in healthy overweight/obese (OW/OB) adults. In this pilot trial, OW/OB adolescents with poorly controlled asthma were randomized to weekly nutrition/exercise classes with or without twice-daily CHORI-bar consumption. Intent-to-treat analysis did not indicate CHORI-bar-specific effects. However, restricting the analysis to participants with acceptable compliance and a relatively low fraction of exhaled nitric oxide (FENO; <50/ ppb, a surrogate for noneosinophilic asthma; study participants: CHORI-bar, n = 16; controls, n = 15) indicated that CHORI-bar-specific, significant improvements in lung function (forced vital capacity, percent-predicted forced expiratory volume in 1 s, and percent-predicted forced expiratory flow between 25 and 75% of forced vital capacity), primarily in participants with low chronic inflammation (high-sensitivity C-reactive protein <1.5 mg/L). (We previously observed that chronic inflammation blunted CHORI-bar-induced metabolic improvements in healthy OW/OB adults.) Lung function improvement occurred without weight loss and was independent of improvements in metabolic and anthropometric end points and questionnaire-based measures of asthma control and quality of life. This study suggests that a nutritional intervention can improve lung function in OW/OB adolescents with asthma and relatively low FENO without requiring major changes in dietary habits, lifestyle, or weight loss and that this effect is blunted by chronic inflammation.-Bseikri, M., McCann, J. C., Lal, A., Fong, E., Graves, K., Goldrich, A., Block, D., Gildengoren, G. L., Mietus-Snyder, M., Shigenaga, M., Suh, J., Hardy, K., Ames, B. N. A novel nutritional intervention improves lung function in overweight/obese adolescents with poorly controlled asthma: the Supplemental Nutrition in Asthma Control (SNAC) pilot study.

Causal relationships between adiposity and childhood asthma: bi-directional Mendelian Randomization analysis

BACKGROUND/OBJECTIVES

Obesity and asthma are common chronic diseases and have been reported to be mutually causative. We investigated the causal direction of the relationship between adiposity and asthma using genetic markers as instrumental variables (IVs) in bi-directional Mendelian randomization (MR) analysis.

SUBJECTS/METHODS

We used data from the Taiwan Children Health Study with 24 body mass index (BMI)-single-nucleotide polymorphisms (SNPs, combined into a weighted allelic score) and 16 asthma-SNPs (combined into two weighted allelic scores, separately for asthma inflammatory and antioxidative genes) to yield genetic IVs for adiposity and asthma, respectively.

RESULTS

The weighted allele score for BMI was strongly associated with adiposity (p = 2 × 10^-16) and active asthma (p = 0.03). The two-stage least square regression risk ratio (RR) for the effect of BMI on asthma was 1.04 (95% confidence interval: 1.00-1.07, p = 0.03). Although the weighted asthma genetic scores were significantly associated with asthma (p = 8.4 × 10^-3), no association was seen for genetically instrumented asthma with BMI using MR. Central obesity was the most accurate predictor of asthma. Adiposity showed higher causal effects on asthma in boys and children with non-atopic asthma. Sensitivity analysis for MR revealed no directional genetic pleiotropy effects. The causal effect RRs of BMI on asthma were 1.04, 1.08, and 1.03 for inverse-variance weighted, MR-Egger regression (slope), and weighted median methods, respectively, all in accordance with the MR estimates.

CONCLUSIONS

High adiposity may lead to asthma, whereas the effects of asthma on adiposity accumulation are likely to be small.

[Usefulness of measurement of nitric oxide in exhaled air in diagnostics and treatment of allergic rhinitis and asthma in children and adolescents]

Nitric oxide is produced by enzymes called nitric oxide synthases. It fulfills many important functions in the human body, but produced in excess amount has a proinflammatory activity. Fractional exhaled nitric oxide measurements are used in the diagnosis and monitoring of eosinophilic inflammation in the lower airways, but should not be used as an independent parameter to make a diagnosis of asthma or for the monitoring of asthma treatment. Evaluation of fractional exhaled nitric oxide concentrations is also used to determine the pathogenesis of symptoms in patients with rhinitis. In addition, they are helpful in detecting and monitoring eosinophilic inflammation in the lower respiratory tract that coexists with inflammation in the upper airways. Fractional exhaled nitric oxide concentrations may be abnormal (lowered or elevated) in other chronic diseases, such as cystic fibrosis, primary ciliary dyskinesia and inflammatory bowel diseases. Many factors, e.g. atopy, genetic polymorphisms of NOS, and the lipid profile affect the fractional exhaled nitric oxide measurement. Nasal nitric oxide measurement is useful in assessing the prevalence and severity of eosinophilic inflammation in the upper respiratory tract.

Is obesity related to the lung function of non-asthmatic children?

Overweight and obesity are highly prevalent in developed and developing countries among children and adolescents. During the last two decades, it became evident that excess weight is adversely related to respiratory health in childhood and adolescence mainly in terms of asthma occurrence. Additionally, there is a mounting body of evidence that overweight/obesity may also affect lung function in non-asthmatic subjects. The aim of this review was to present and discuss the studies that investigated this issue in non-asthmatic children and adolescents. Only a few studies have evaluated the impact of excess weight on static volumes and their results point towards an inverse relationship between overweight/obesity and functional residual capacity. More studies have been conducted on the impact of excess weight on dynamic lung volumes with inconsistent, however, results. Nevertheless, a relatively consistent finding was that the ratio of forced expiratory volume in 1 s/forced vital capacity was significantly lower among overweight/obese children compared to their counterparts with normal weight. The underlying mechanisms of these observations have not been adequately elucidated but it is believed to result from complex interaction of mechanical, developmental, and metabolic causes. There is a need for more well-designed studies in order to clarify the impact of excess weight on lung function in non-asthmatic subjects, as well as to explore the contribution of factors such as duration and degree of obesity, and fat distribution. Despite the absence of conclusive data, there are still convincing evidence to be communicated to the children and their families as part of the arguments to encourage them to adopt a healthier lifestyle.

Obesity and asthma

Obesity is a vast public health problem and both a major risk factor and disease modifier for asthma in children and adults. Obese subjects have increased asthma risk, and obese asthmatic patients have more symptoms, more frequent and severe exacerbations, reduced response to several asthma medications, and decreased quality of life. Obese asthma is a complex syndrome, including different phenotypes of disease that are just beginning to be understood. We examine the epidemiology and characteristics of this syndrome in children and adults, as well as the changes in lung function seen in each age group. We then discuss the better recognized factors and mechanisms involved in disease pathogenesis, focusing particularly on diet and nutrients, the microbiome, inflammatory and metabolic dysregulation, and the genetics/genomics of obese asthma. Finally, we describe current evidence on the effect of weight loss and mention some important future directions for research in the field.

Adiposity and Asthma in a Nationwide Study of Children and Adults in the United States

RATIONALE

Although obesity has been associated with asthma, body mass index is suboptimal to fully characterize adiposity.

OBJECTIVES

We examined the relation between adiposity and asthma in a large sample of the U.S. population, using indices defined by dual-energy X-ray absorptiometry.

METHODS

We analyzed data from 8,886 children (aged 8-19 yr) and 12,795 adults (aged 20-69 yr) from the 2001 to 2006 National Health and Nutrition Examination Survey. In addition to body mass index, percent body fat, waist circumference, and waist-to-height ratio, dual-energy X-ray absorptiometry was used to calculate whole-body and local adiposity indices: fat mass index; total, trunk, and legs percent fat; and trunk-to-total fat mass ratio, legs-to-total fat mass ratio, and trunk-to-legs fat mass ratios. Logistic regression was used for the analysis of adiposity measures and asthma.

RESULTS

Among children, general adiposity was significantly associated with asthma, with no major differences by sex. Results were driven by nonatopic children, in whom trunk-predominant (central) adiposity (assessed by waist circumference, waist-to-height ratio, trunk-to-total fat mass ratio, and trunk-to-legs fat mass ratio) was also associated with asthma. There were no significant associations among atopic children. Among adults, all adiposity indices were associated with asthma, with central adiposity significant only among women. The results in adults were driven by atopy, especially in women.

CONCLUSIONS

Adiposity measured by dual-energy X-ray absorptiometry provides similar information to that obtained by using anthropometric indices among children of both sexes and among adult men. However, dual-energy X-ray absorptiometry provides additional information in adult women, in whom dual-energy X-ray absorptiometry-measured central adiposity is significantly associated with asthma, particularly atopic asthma.

Association of leptin with disease severity and inflammation indicators in Chinese obese children with allergic rhinitis

BACKGROUND

The prevalence of both obesity and allergic diseases in children has increased over the last several decades. However, the direct relationship between diverse allergic diseases and obesity has varied in different studies. Therefore, we aimed to examine the effect of obesity on the incidence and severity of allergic rhinitis (AR) and the possible key inflammation mediators during AR.

METHODS

A total of 3126 healthy students (without chronic diseases) were recruited from 14 randomly selected secondary schools in Guangzhou, China. Body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHR), and body fat percentage (PBF) were measured and compared. The effect of obesity indicators and leptin level (exposures) on the incidence (primary outcome) and severity of AR (secondary outcomes) was analyzed. Inflammatory markers were detected and compared among groups.

RESULTS

The symptom score (9.5 ± 3.1 vs 8.2 ± 3.5, P < .05) and medication score (3.6 ± 1.6 vs 2.9 ± 1.8, P < .05) were significantly higher in obese children with AR than in non-obese children with AR. After adjusting for potential confounders, multiple linear regression analysis showed that the serum leptin concentration was significantly correlated with the levels of T-helper (TH) 2 cytokines (coefficient, 0.48 [95% CI, 0.05-0.91]), TH17 cytokines (coefficient, 0.39 [95% CI, 0.11-0.89]), and regulatory T-cell cytokines (IL-10, coefficient, -0.43 [95% CI, -0.02-0.65]; TGF-β, coefficient, -0.65 [95% CI, -0.06-1.35]) in patients with AR.

CONCLUSIONS

Our study shows that obesity exacerbates inflammation and contributes to disease severity in AR. Our study provides evidence that leptin was involved in enhanced TH inflammation as well as the accumulation and activation of inflammatory cells in obese children with AR.

A review of obesity and asthma across the life span

OBJECTIVE

This literature review aims to compare obese-asthmatic adults and children, and to characterize differences and similarities between the two subgroups from epidemiological, demographical, phenotypical, and physiological perspectives.

METHODS

Literature search was conducted using Pubmed database with "obesity," "asthma," "epidemiology," "cluster analysis," "demography," "mechanics," and ''FeNO'' as search terms.

METHODS

Articles investigating epidemiological, demographic, phenotypical variation, and mechanical aspects of breathing specifically in obese asthmatics were identified. The studies were then divided according to age: children (<18 years of age) and adults (>18 years of age).

RESULTS

Increase in asthma incidence and prevalence is observed in both obese-asthmatic children and adults. Asthma prevalence is greater in adult females regardless of ethnic background, and in men of African American and Hispanic ethnicities. Degree of weight gain and early onset of menarche appears to directly affect asthma severity in adolescent girls and females. Airway hyperresponsiveness and fractional exhaled nitric oxide do not have any positive correlation with high BMI in obese-asthmatic children and adults. Obesity also alters lung mechanics in asthmatics, but the impact is different for children and adults likely due to differential effect of obesity on central and peripheral airway.

CONCLUSION

Existing literature suggests both similarities and differences in obese-asthmatic children and adults. The most pertinent differences are related to gender, ethnicity, and lung functions.

Body mass index status and peripheral airway obstruction in school-age children: a population-based cohort study

BACKGROUND

Few large prospective studies have investigated the impact of body mass index (BMI) on lung function during childhood.

METHODS

Using data collected between 2002 and 2013, we analysed associations between BMI status and lung function (assessed by spirometry) from 8 to 16 years, as well as cross-sectional associations with small airway function (impulse oscillometry) at 16 years in the BAMSE cohort (n=2889). At 16 years, cross-sectional associations with local and systemic inflammation were investigated by analysing FE_NO, blood eosinophils and neutrophils.

RESULTS

Overweight and obesity at 8 years were associated with higher FVC, but lower FEV₁/FVC ratio at 8 and 16 years. In boys, but not girls, obesity at 8 years was associated with a further reduction in FEV₁/FVC between 8 and 16 years. In cross-sectional analyses, overweight and obesity were associated with higher frequency dependence of resistance (R_5-20) and larger area under the reactance curve (AX^0.5) at 16 years. Increased blood neutrophil counts were seen in overweight and obese girls, but not in boys. No association was found between BMI status and FE_NO. Persistent, but not transient, overweight/obesity between 8 and 16 years was associated with higher R_5-20 and AX^0.5 and lower FEV₁/FVC (-2.8% (95% CI -4.1 to -1.2) in girls and -2.7% (95% CI -4.4 to -1.1) in boys) at 16 years, compared with persistent normal weight.

CONCLUSION

In childhood and adolescence, overweight and obesity, particularly persistent overweight, were associated with evidence of airway obstruction, including the small airways.

The effect of obesity, weight gain, and weight loss on asthma inception and control

PURPOSE OF REVIEW

There is ample and growing evidence that obesity increases the risk of asthma and morbidity from asthma. Here, we review recent clinical evidence supporting a causal link between obesity and asthma, and the mechanisms that may lead to 'obese asthma'.

RECENT FINDINGS

Although in some children obesity and asthma simply co-occur, those with 'obese asthma' have increased asthma severity, lower quality of life, and reduced medication response. Underlying mechanistic pathways may include anatomical changes of the airways such as obstruction and dysanapsis, systemic inflammation, production of adipokines, impaired glucose-insulin metabolism, altered nutrient levels, genetic and epigenetic changes, and alterations in the airway and/or gut microbiome. A few small studies have shown that weight loss interventions may lead to improvements in asthma outcomes, but thus far research on therapeutic interventions for these children has been limited.

SUMMARY

Obesity increases the risk of asthma - and worsens asthma severity or control - via multiple mechanisms. 'Obese asthma' is a complex, multifactorial phenotype in children. Obesity and its complications must be managed as part of the treatment of asthma in obese children.

Contribution of weight status to asthma prevalence racial disparities, 2-19 year olds, 1988-2014

PURPOSE

Racial disparities in childhood asthma prevalence increased after the 1990s. Obesity, which also varies by race/ethnicity, is an asthma risk factor but its contribution to asthma prevalence disparities is unknown.

METHODS

We analyzed nationally representative National Health Examination and Nutrition Survey data for 2-19 year olds with logistic regression and decomposition analyses to assess the contributions of weight status to racial disparities in asthma prevalence, controlling for sex, age, and income status.

RESULTS

From 1988-1994 to 2011-2014, asthma prevalence increased more among non-Hispanic black (NHB) (8.4% to 18.0%) than non-Hispanic white (NHW) youth (7.2% to 10.3%). Logistic regression showed that obesity was an asthma risk factor for all groups but that a three-way "weight status-race/ethnicity-time" interaction was not significant. That is, weight status did not modify the race/ethnicity association with asthma over time. In decomposition analyses, weight status had a small contribution to NHB/NHW asthma prevalence disparities but most of the disparity remained unexplained by weight status or other asthma risk factors (sex, age and income status).

CONCLUSIONS

NHB youth had a greater asthma prevalence increase from 1988-1994 to 2011-2014 than NHW youth. Most of the racial disparity in asthma prevalence remained unexplained after considering weight status and other characteristics.

Overweight in childhood and adolescence: Does it lead to airway hyperresponsiveness in adulthood?

BACKGROUND

Obesity is increasing worldwide among children and adolescents, and has been associated with an increased incidence of asthma. However, the mechanisms underlying this association are incompletely understood.

OBJECTIVE

In this cohort study we aimed to investigate whether being overweight in childhood and adolescence is associated with an increased risk of airway hyperresponsiveness (AHR), a hallmark of asthma, in early adulthood.

METHODS

Of 527 subjects from a random population sample of children and adolescents (7-17 years) examined at baseline, a total of 184 subjects completed the follow-up visit 20 years later and were included in the present analysis. Both visits included assessment of height and weight, case history and spirometry. At both visits, bronchial provocation tests were performed using either histamine (baseline) or methacholine (follow-up). In addition, fractional exhaled nitric oxide (FeNO) was measured at follow-up.

RESULTS

No significant difference in the prevalence of AHR at follow-up was found between subjects who were overweight or obese at baseline visit (n = 26) (pediatric definition, body mass index ≥ 85%percentile) and normal weight subjects (n = 158) (positive bronchial provocation tests: 15.4% vs. 22.2%, respectively, p = 0.35). Likewise, follow-up FeNO levels did not differ significantly between subjects who were lean and those who were overweight or obese at baseline (geometric mean (95% confidence interval [CI]) 15.1 (13.7, 16.6) parts per billion (ppb) versus 13.0 (10.6, 15.9) ppb, p = 0.23).

CONCLUSION

In children and adolescents, being obese or overweight seems not to be associated with an increased risk of AHR or increased FeNO levels in early adulthood.

Prevalence of high fractional exhaled nitric oxide among US youth with asthma

BACKGROUND

High fractional exhaled nitric oxide (FeNO) is an indicator of poor asthma control and has been proposed as a non-invasive assessment tool to guide asthma management.

OBJECTIVE

We aimed to describe the prevalence of and factors associated with high FeNO among US youth with asthma.

METHODS

Data from 716 children and adolescents with asthma ages 6-19 years who participated in the 2007-2012 National Health and Nutrition Examination Survey were analyzed. Using American Thoracic Society guidelines, high FeNO was defined as >50 ppb for ages 12-19 years and >35 ppb for ages 6-11 years. Multivariate logistic regression examined associations between high FeNO and age, sex, race/Hispanic origin, income status, weight status, tobacco smoke exposure, and other factors associated with asthma control (recent use of inhaled corticosteroids, recent respiratory illness, asthma-related respiratory signs/symptoms, and spirometry).

RESULTS

About 16.5% of youth with asthma had high FeNO. The prevalence of high FeNO was higher among non-Hispanic black (27%, P < 0.001) and Hispanic (20.2%, P = 0.002) youth than non-Hispanic white (9.7%) youth. Differences in high FeNO prevalence by sex (girls < boys), weight status (obese < normal weight), tobacco smoke exposure (smokers < home exposure < no exposure), and FEV1/FVC (normal < abnormal) were also observed. No differences were noted between categories for the remaining covariates.

CONCLUSION

High FeNO was observed to be associated with sex, race/Hispanic origin, weight status, tobacco smoke exposure, and abnormal FEV1/FVC, but was not associated with asthma-related respiratory symptoms. These findings may help inform future research and clinical practice guidelines on the use of high FeNO in the assessment of asthma control.

Obesity disproportionately impacts lung volumes, airflow and exhaled nitric oxide in children

Background

The current literature focusing on the effect of obesity and overweight on lung function and fraction of exhaled nitric oxide (FeNO) in children, particularly among healthy children of non-European descent, remains controversial. Furthermore, whether the relationship of obesity and overweight with lung function and FeNO in children is modified by atopy is unclear. The objective of this study was to examine the effect of excess weight on lung function parameters and FeNO among Asian children, with a particular focus on exploring the potential effect modification by atopy.

Methods

We investigated the effect of excess weight on lung function and FeNO in a population sample of 1,717 children aged 5 to 18 years and explored the potential modifying effect of atopy.

Results

There were positive associations of body mass index (BMI) z-score with forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), peak expiratory flow (PEF), and forced expiratory flow at 25–75% (FEF_25-75) (all P<0.001), after controlling for confounders. The beta coefficient for FEV₁ (0.084) was smaller than that for FVC (0.111). In contrast, a negative association was found between BMI z-score and FEV₁/FVC ratio (P<0.001) and FeNO (P = 0.03). A consistent pattern of association for lung function variables was observed when stratifying by atopy. There was a negative association of BMI z-score with FeNO in atopic subjects (P = 0.006), but not in non-atopic subjects (P = 0.46).

Conclusions

Excess weight disproportionately impacts lung volumes and airflow in children from the general population, independent of atopic status. Excess weight inversely affects FeNO in atopic but not in non-atopic children.

Rapid adiposity growth increases risks of new-onset asthma and airway inflammation in children

BACKGROUND/OBJECTIVES

We aim to (1) examine the influence of long-term adiposity status/short-term adiposity changes on asthma with high or low fractional exhaled nitric oxide (Fe_NO), and (2) to determine the differences in long-term adiposity status/short-term adiposity changes on atopy, airway inflammation and pulmonary function.

SUBJECTS/METHODS

We recruited 2450 fourth- to sixth-grade children from the nationwide Taiwan Children Health Study. Data regarding various adiposity indicators, atopic status, pulmonary function tests and asthma outcomes were collected annually. New-onset asthma was stratified by airway inflammation status using Fe_NO. The generalized estimating equation was used for analyzing longitudinal relationships between long-term adiposity status/short-term adiposity changes and new-onset asthma. Individual adiposity growth slopes were obtained using a hierarchical linear model to establish the relationships between short-term adiposity changes and asthma among children with high airway inflammation.

RESULTS

We found long-term adiposity status predicted childhood asthma with low Fe_NO, whereas short-term adiposity changes may increase risks of childhood asthma with high Fe_NO. Long-term adiposity status reduced pulmonary function, whereas short-term adiposity increase were associated with atopic diseases and airway inflammation.

CONCLUSIONS

Obesity-induced asthma could be mediated by high or low airway inflammation, depending on the velocity of increase in adiposity. Rapid adiposity growth may increase risks of childhood asthma and airway inflammation.

Obesity and Airway Dysanapsis in Children with and without Asthma

RATIONALE

For unclear reasons, obese children with asthma have higher morbidity and reduced response to inhaled corticosteroids.

OBJECTIVES

To assess whether childhood obesity is associated with airway dysanapsis (an incongruence between the growth of the lungs and the airways) and whether dysanapsis is associated with asthma morbidity.

METHODS

We examined the relationship between obesity and dysanapsis in six cohorts of children with and without asthma, as well as the relationship between dysanapsis and clinical outcomes in children with asthma. Adjusted odds ratios (ORs) were calculated for each cohort and in a combined analysis of all cohorts; longitudinal analyses were also performed for cohorts with available data. Hazard ratios (HRs) for clinical outcomes were calculated for children with asthma in the Childhood Asthma Management Program.

MEASUREMENTS AND MAIN RESULTS

Being overweight or obese was associated with dysanapsis in both the cross-sectional (OR, 1.95; 95% confidence interval [CI], 1.62-2.35 [for overweight/obese compared with normal weight children]) and the longitudinal (OR, 4.31; 95% CI, 2.99-6.22 [for children who were overweight/obese at all visits compared with normal weight children]) analyses. Dysanapsis was associated with greater lung volumes (FVC, vital capacity, and total lung capacity) and lesser flows (FEV1 and forced expiratory flow, midexpiratory phase), and with indicators of ventilation inhomogeneity and anisotropic lung and airway growth. Among overweight/obese children with asthma, dysanapsis was associated with severe disease exacerbations (HR, 1.95; 95% CI, 1.38-2.75) and use of systemic steroids (HR, 3.22; 95% CI, 2.02-5.14).

CONCLUSIONS

Obesity is associated with airway dysanapsis in children. Dysanapsis is associated with increased morbidity among obese children with asthma and may partly explain their reduced response to inhaled corticosteroids.

Gender-specific determinants of asthma among U.S. adults

BACKGROUND

Asthma, a chronic respiratory disease affecting over 18.7 million American adults, has marked disparities by gender, race/ethnicity and socioeconomic status. Our goal was to identify gender-specific demographic and socioeconomic determinants of asthma prevalence among U.S. adults using data from the Behavioral Risk Factors Surveillance System (BRFSS) and the National Health and Nutrition Examination Survey (NHANES).

METHODS

Gender-specific regression analyses were performed to model the relationship between asthma prevalence with age, race/ethnicity, income, education level, smoking status, and body mass index (BMI), while taking into account the study designs.

RESULTS

Based on BRFSS data from 1,003,894 respondents, weighted asthma prevalence was 6.2% in males and 10.6% in females. Asthma prevalence among grade 2 obese and grade 3 obese vs. not overweight or obese women was 2.5 and 3.5 times higher, respectively, while that in men was 1.7 and 2.4 times higher; asthma prevalence among current vs. never smoker women was 1.4 times higher, while that in men was 1.1 times higher. Similar results were obtained with NHANES data from 13,364 respondents: asthma prevalence among grade 2 obese and grade 3 obese vs. not overweight or obese respondents was 2.0 and 3.3 times higher for women, though there was no significant difference for men; asthma prevalence among current vs. never smokers was 1.8 times higher for women and not significantly different in men. Asthma prevalence by race/ethnicity and income levels did not differ considerably between men and women.

CONCLUSIONS

Our results underscore the importance of obesity and smoking as modifiable asthma risk factors that most strongly affect women.

Longitudinal study of maternal body mass index, gestational weight gain, and offspring asthma

BACKGROUND

Sparse data are available on the relationship between prenatal exposures and asthma during later childhood. In a longitudinal study of adolescents and their mothers, we examined the association of (i) maternal prepregnancy body mass index (BMI) and (ii) gestational weight gain (GWG), with incidence of allergic and nonallergic asthma in offspring.

METHODS

Analyses were conducted using data from 12 963 children aged 9-14 years at enrolment in the Growing Up Today Study, and their mothers, who are participants in the Nurses' Health Study II. Physician-diagnosed asthma and allergies were assessed by questionnaires sent regularly to participants and their mothers. Logistic regression was used to evaluate associations of maternal BMI and GWG with offspring asthma, overall and by subtype.

RESULTS

Physician-diagnosed asthma during childhood or adolescence was reported by 2694 children (21%). Maternal prepregnancy overweight (OR: 1.19, 95% CI: 1.03-1.38) and obesity (1.34, 1.08-1.68) were associated with offspring asthma. In asthma subtype analyses, the association was seen only for asthma onset before age 12 years. Moreover, the association of maternal obesity with nonallergic asthma was observed in boys (2.39, 1.40-4.09) and not in girls (0.96, 0.50-1.85; Pinteraction = 0.03); the opposite pattern was suggested for allergic asthma. With regard to GWG, an association was suggested between gains of <15 lb and higher risk of offspring asthma (1.28, 0.98-1.66), without clear allergy- or sex-related patterns.

CONCLUSION

The relation of several prenatal factors to risk of childhood asthma supports the early origins hypothesis for asthma. The observed allergy- and sex-specific patterns suggest multiple etiologic pathways.