Metabolic abnormalities in children with 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.

Consistent Biomarkers and Related Pathogenesis Underlying Asthma Revealed by Systems Biology Approach

Asthma is a common chronic airway disease worldwide. Due to its clinical and genetic heterogeneity, the cellular and molecular processes in asthma are highly complex and relatively unknown. To discover novel biomarkers and the molecular mechanisms underlying asthma, several studies have been conducted by focusing on gene expression patterns in epithelium through microarray analysis. However, few robust specific biomarkers were identified and some inconsistent results were observed. Therefore, it is imperative to conduct a robust analysis to solve these problems. Herein, an integrated gene expression analysis of ten independent, publicly available microarray data of bronchial epithelial cells from 348 asthmatic patients and 208 healthy controls was performed. As a result, 78 up- and 75 down-regulated genes were identified in bronchial epithelium of asthmatics. Comprehensive functional enrichment and pathway analysis revealed that response to chemical stimulus, extracellular region, pathways in cancer, and arachidonic acid metabolism were the four most significantly enriched terms. In the protein-protein interaction network, three main communities associated with cytoskeleton, response to lipid, and regulation of response to stimulus were established, and the most highly ranked 6 hub genes (up-regulated CD44, KRT6A, CEACAM5, SERPINB2, and down-regulated LTF and MUC5B) were identified and should be considered as new biomarkers. Pathway cross-talk analysis highlights that signaling pathways mediated by IL-4/13 and transcription factor HIF-1α and FOXA1 play crucial roles in the pathogenesis of asthma. Interestingly, three chemicals, polyphenol catechin, antibiotic lomefloxacin, and natural alkaloid boldine, were predicted and may be potential drugs for asthma treatment. Taken together, our findings shed new light on the common molecular pathogenesis mechanisms of asthma and provide theoretical support for further clinical therapeutic studies.

Early testing of insulin resistance: a tale of two lipid ratios in a group of 5th graders screened by the Coronary Artery Risk Detection in Appalachian Communities Project (CARDIAC Project)

BACKGROUND

In West Virginia (WV), 47% of fifth-grade children are either overweight or obese. There is no clear consensus regarding the definition of insulin resistance in children, and directly measuring insulin on the population level is costly. Two proposed measures examined further in this study include triglyceride (TRIG)/high-density lipoprotein cholesterol (HDL-C) ratio and TRIG/low-density lipoprotein (LDL-C) ratio. The purpose of this study is to examine the relationship between TRIG/HDL-C ratio, TRIG/LDL-C ratio and insulin resistance in fifth-graders with acanthosis nigricans (AN).

METHODS

Between 2007 and 2016, 52,545 fifth-grade students in WV were assessed for AN. Fasting glucose and insulin levels were collected only for a sub-group of students who were AN-positive and was used to determine insulin resistance using the Homeostatic Model for Insulin Resistance (HOMA-IR) equation. Statistical analysis included t tests and logistic regression with receiver operating characteristic curves.

RESULTS

Of the students assessed for AN, 4.5% (n = 2360) tested positive. The prevalence of insulin resistance was 79% (n = 814) among 1030 with AN and complete HOMA-IR. TRIG/HDL-C ratio and TRIG/LDL-C ratio were significantly associated with insulin resistance (TRIG/HDL-C:Est. = 0.36, P < 0.0001, AUC = 0.68; TRIG/LDL-C: Est. = 0.87, P < 0.0001, AUC = 0.69). Multivariate analysis showed that increased body mass index (Est. = 0.05, P < 0.0001), gender (Est. = 0.49, p < 0.0001) and TRIG/HDL-C ratio (Est. = 0.21, P < 0.0001) were significantly associated with insulin resistance.

CONCLUSIONS

TRIG/HDL-C is a better surrogate marker of insulin resistance in AN-positive children compared to TRIG/LDL-C ratio; so, on a population-level, cholesterol rather than insulin may be obtained for preliminary testing of early insulin resistance in children.

Semantic integration of clinical laboratory tests from electronic health records for deep phenotyping and biomarker discovery

Electronic Health Record (EHR) systems typically define laboratory test results using the Laboratory Observation Identifier Names and Codes (LOINC) and can transmit them using Fast Healthcare Interoperability Resource (FHIR) standards. LOINC has not yet been semantically integrated with computational resources for phenotype analysis. Here, we provide a method for mapping LOINC-encoded laboratory test results transmitted in FHIR standards to Human Phenotype Ontology (HPO) terms. We annotated the medical implications of 2923 commonly used laboratory tests with HPO terms. Using these annotations, our software assesses laboratory test results and converts each result into an HPO term. We validated our approach with EHR data from 15,681 patients with respiratory complaints and identified known biomarkers for asthma. Finally, we provide a freely available SMART on FHIR application that can be used within EHR systems. Our approach allows readily available laboratory tests in EHR to be reused for deep phenotyping and exploits the hierarchical structure of HPO to integrate distinct tests that have comparable medical interpretations for association studies.

Metabolic health is more closely associated with decrease in lung function than obesity

Objective

Previous studies have evaluated the link between metabolic syndrome and obesity with impaired lung function, however findings have been controversial. We aimed to compare lung function among subjects with different metabolic health and obesity status.

Methods

Total 10,071 participants were evaluated at the Health Promotion Center in Seoul St. Mary’s Hospital between January 2012 and December 2014. Being metabolically healthy was defined as having fewer than three of the following risk factors: high blood pressure, high fasting blood glucose, high triglyceride, low high-density lipoprotein cholesterol and abdominal obesity. Obesity status was defined as body mass index (BMI) higher than 25 kg/m². Analyses of pulmonary function were performed in four groups divided according to metabolic health and obesity: metabolically healthy non-obese (MHNO), metabolically health obese (MHO), metabolically unhealthy non-obese (MUHNO), and metabolically unhealthy obese (MUHO).

Results

Metabolically unhealthy subjects were more prone to decreased lung function compared with their metabolically healthy counterparts, regardless of obesity status. When multinomial logistic regression analysis was performed according to quartiles of forced vital capacity (FVC) or forced expiratory volume in 1 second (FEV₁) (% pred), after adjusting for age, sex, and smoking status, odds ratio (OR) for the lowest FVC and FEV₁ (% pred) quartiles were significantly higher in MUHO subjects (1.788 [95% CI, 1.531–2.089] and 1.603 [95% CI, 1.367–1.881]) and lower in MHO subjects (0.768 [95% CI, 0.654–0.902] and 0.826 [95% CI, 0.700–0.976]) with MHNO group as the reference, when OR for highest FVC and FEV₁ quartiles were considered as 1.0

Conclusion

Metabolic health is more closely associated with impaired lung function than obesity.

Diet and Metabolism in the Evolution of Asthma and Obesity

Obesity is a major risk factor for asthma. This association appears related to altered dietary composition and metabolic factors that can directly affect airway reactivity and airway inflammation. This article discusses how specific changes in the western diet and metabolic changes associated with the obese state affect inflammation and airway reactivity and reviews evidence that interventions targeting weight, dietary components, lifestyle, and metabolism might improve outcomes in asthma.

Mitochondrial Dysfunction Linking Obesity and Asthma

The bidirectional epidemiological association between asthma and obesity is well known. Recent evidence suggests that there is an intersection of the pathophysiological molecular pathways leading to either obesity or asthma, at the level of mitochondria. This is not surprising, because mitochondria, beyond their roles as the metabolic powerhouses of the cell, serve as sensors of threats, regulators of stress signaling, and effectors of cytotoxicity. Reduced mitochondrial function and low metabolic activity are well-recognized features of obesity. Three distinct lines of experimental evidences connect mitochondrial dysfunction with asthma. First, asthma is associated with aberrant mitochondrial metabolism. Second, mitochondrial dysfunction may either induce asthma-like features or increase asthma severity. Third, mitochondria-targeted therapies appear effective in preventing or reversing asthma features. Importantly, mitochondrial dysfunction in airway epithelial cells appears to be a powerful trigger for airway remodeling that is independent of cellular inflammation. This is clinically relevant to the obese-asthma phenotype, with exaggerated symptoms despite apparently low levels of inflammation, and poor response to antiinflammatory treatment. In summary, mitochondrial dysfunction is a common thread tying together the twin epidemics of obesity and asthma. Environmental and lifestyle factors leading to primary mitochondrial dysfunction may be increasing the risk for either disease. Further, secondary mitochondrial dysfunction emerging from the pathogenesis of either obesity or asthma may increase the risk of the other. Mitochondrial health-centric strategies may be relevant to prevention and treatment of both obesity and asthma, and should be actively considered.

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.

Cellular Stresses and Stress Responses in the Pathogenesis of Insulin Resistance

Insulin resistance (IR), a key component of the metabolic syndrome, precedes the development of diabetes, cardiovascular disease, and Alzheimer's disease. Its etiological pathways are not well defined, although many contributory mechanisms have been established. This article summarizes such mechanisms into the hypothesis that factors like nutrient overload, physical inactivity, hypoxia, psychological stress, and environmental pollutants induce a network of cellular stresses, stress responses, and stress response dysregulations that jointly inhibit insulin signaling in insulin target cells including endothelial cells, hepatocytes, myocytes, hypothalamic neurons, and adipocytes. The insulin resistance-inducing cellular stresses include oxidative, nitrosative, carbonyl/electrophilic, genotoxic, and endoplasmic reticulum stresses; the stress responses include the ubiquitin-proteasome pathway, the DNA damage response, the unfolded protein response, apoptosis, inflammasome activation, and pyroptosis, while the dysregulated responses include the heat shock response, autophagy, and nuclear factor erythroid-2-related factor 2 signaling. Insulin target cells also produce metabolites that exacerbate cellular stress generation both locally and systemically, partly through recruitment and activation of myeloid cells which sustain a state of chronic inflammation. Thus, insulin resistance may be prevented or attenuated by multiple approaches targeting the different cellular stresses and stress responses.

Pediatric metabolic outcome comparisons based on a spectrum of obesity and asthmatic symptoms

RATIONALE

Asthma and obesity are 2 of the most prevalent public health issues for children in the U.S. Trajectories of both have roughly paralleled one another over the past several decades causing many to explore their connection to one another and to other associated health issues such as diabetes and dyslipidemia. Earlier models have commonly designated obesity as the central hub of these associations; however, more recent models have argued connections between pediatric asthma and other obesity-related metabolic conditions regardless of children's obesity risk.

OBJECTIVES

To examine the relationships between asthma, obesity, and abnormal metabolic indices.

METHODS

We conducted a cross-sectional study of 179 children ages 7 to 12 years recruited from a rural, Appalachian region. Our model controlled for children's smoke exposure, body mass index percentile, and gender to examine the association between children's asthma (based on pulmonary function tests, medical history, medications, and parent report of severity), lipids (fasting lipid profile), and measures of altered glucose metabolism (glycosylated hemoglobin and homeostatic model assessment 2-insulin resistance).

RESULTS

Our findings revealed a statistically significant model for low density lipids, high density lipids, log triglyceride, and homeostatic model assessment 2-insulin resistance; however, Asthma had a significant effect for the mean triglycerides. We also found an asthma-obesity interaction effect on children's glycosylated hemoglobin with asthmatic obese children revealing significantly higher glycosylated hemoglobin values than non-asthmatic obese children.

CONCLUSIONS

Our findings support a connection between asthma and children's glycosylated hemoglobin values; however, this association remains entwined with obesity factors.

CDC42-related genes are upregulated in helper T cells from obese asthmatic children

BACKGROUND

Pediatric obesity-related asthma is more severe and less responsive to medications than asthma in normal-weight children. Obese asthmatic children have nonatopic TH1-polarized systemic inflammation that correlates with pulmonary function deficits, but the pathways underlying TH1-polarized inflammation are not well understood.

OBJECTIVE

We compared the CD4+ T-cell transcriptome in obese children with asthma with that in normal-weight children with asthma to identify key differentially expressed genes associated with TH1-polarized inflammation.

METHODS

CD4+ T-cell transcriptome-wide differential gene expression was compared between 21 obese and 21 normal-weight children by using directional RNA sequencing. High-confidence differentially expressed genes were verified in the first cohort and validated in a second cohort of 20 children (10 obese and 10 normal-weight children) by using quantitative RT-PCR.

RESULTS

Transcriptome-wide differential gene expression among obese asthmatic children was enriched for genes, including VAV2, DOCK5, PAK3, PLD1, CDC42EP4, and CDC42PBB, which are associated with CDC42, a small guanosine triphosphate protein linked to T-cell activation. Upregulation of MLK3 and PLD1, genes downstream of CDC42 in the mitogen-activated protein kinase and mammalian target of rapamycin pathways and the inverse correlation of CDC42EP4 and DOCK5 transcript counts with FEV1/FVC ratio together support a role of CDC42 in the TH1 polarization and pulmonary function deficits found in patients with obesity-related asthma.

CONCLUSIONS

Our study identifies the CDC42 pathway as a novel target that is upregulated in TH cells of obese asthmatic children, suggesting its role in nonatopic TH1-polarized systemic inflammation and pulmonary function deficits found in patients with pediatric obesity-related asthma.

Metabolic Disorders in Chronic Lung Diseases

Chronic lung diseases represent complex diseases with gradually increasing incidence, characterized by significant medical and financial burden for both patients and relatives. Their increasing incidence and complexity render a comprehensive, multidisciplinary, and personalized approach critically important. This approach includes the assessment of comorbid conditions including metabolic dysfunctions. Several lines of evidence show that metabolic comorbidities, including diabetes mellitus, dyslipidemia, osteoporosis, vitamin D deficiency, and thyroid dysfunction have a significant impact on symptoms, quality of life, management, economic burden, and disease mortality. Most recently, novel pathogenetic pathways and potential therapeutic targets have been identified through large-scale studies of metabolites, called metabolomics. This review article aims to summarize the current state of knowledge on the prevalence of metabolic comorbidities in chronic lung diseases, highlight their impact on disease clinical course, delineate mechanistic links, and report future perspectives on the role of metabolites as disease modifiers and therapeutic targets.

Association between Allergies and Hypercholesterolemia: A Systematic Review

BACKGROUND

There is controversy in the literature regarding the potential relationship between atopic predisposition (AP) and serum cholesterol levels. To this purpose, we reviewed human studies that investigated this possible link.

METHODS

Following PRISMA guidelines, a literature search of PubMed and Science Direct for peer-reviewed journal articles in English from January 2003, with updates through to August 2016, was conducted. Relevant publications were reviewed that included pediatric and adult populations. Information on the study design, sample, intervention, comparators, outcome, time frame, and risk of bias were abstracted for each article.

RESULTS

Of 601 reviewed reports, 18 were included in this systematic review. Fifteen studies assessed the relationship between AP and serum cholesterol levels. Due to the lack both of observational and cross-sectional studies from the literature search at this time (only 8 studies also analyzed confounding factors) there is a high possibility of confounding variables (familial and genetic predisposition, age, gender, BMI, comorbidity, and medication status) that could not be ruled out.

CONCLUSION

Existing studies are heterogeneous, making it difficult to draw broad conclusions. Future studies and more detailed analyses, considering confounding variables and including a larger and homogeneous population, are needed to strengthen the argument for a link between lipid metabolism and atopy.

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.

Beyond BMI: Obesity and Lung Disease

The worldwide prevalence of obesity has increased rapidly in the last 3 decades, and this increase has led to important changes in the pathogenesis and clinical presentation of many common diseases. This review article examines the relationship between obesity and lung disease, highlighting some of the major findings that have advanced our understanding of the mechanisms contributing to this relationship. Changes in pulmonary function related to fat mass are important, but obesity is much more than simply a state of mass loading, and BMI is only a very indirect measure of metabolic health. The obese state is associated with changes in the gut microbiome, cellular metabolism, lipid handling, immune function, insulin resistance, and circulating factors produced by adipose tissue. Together, these factors can fundamentally alter the pathogenesis and pathophysiology of lung health and disease.

Obesity and Asthma: A Missing Link

Obesity and asthma are two chronic conditions that affect millions of people. Genetic and lifestyle factors such as diet, physical activity, and early exposure to micro-organisms are important factors that may contribute to the escalating prevalence of both conditions. The prevalence of asthma is higher in obese individuals. Recently, two major phenotypes of asthma with obesity have been described: one phenotype of early-onset asthma that is aggravated by obesity, and a second phenotype of later-onset asthma that predominantly affects women. Systemic inflammation and mechanical effect, both due to the expansion of the adipose tissue, have been proposed as the main reasons for the association between obesity and asthma. However, the mechanisms involved are not yet fully understood. Moreover, it has also been suggested that insulin resistance syndrome can have a role in the association between these conditions. The intestinal microbiota is an important factor in the development of the immune system, and can be considered a link between obesity and asthma. In the obese state, higher lipopolysaccharide (LPS) serum levels as a consequence of a microbiota dysbiosis have been found. In addition, changes in microbiota composition result in a modification of carbohydrate fermentation capacity, therefore modifying short chain fatty acid (SCFA) levels. The main objective of this review is to summarize the principal findings that link obesity and asthma.

An obesity-preventive lifestyle score is negatively associated with pediatric asthma

PURPOSE

Lifestyle (diet and physical activity) may increase asthma risk, but evidence in this area is lacking. The aims of the present study were to calculate an obesity-preventive lifestyle score comprising of eating and physical activity behaviors and investigate the overall effect of lifestyle on asthma in children.

METHODS

A cross-sectional case-control study was carried out in 514 children (217 asthma cases and 297 healthy controls). Data were collected on medical history, anthropometry, dietary intake, and physical activity. We constructed an overweight/obesity-preventive score (OPLS) using study-specific quartile rankings for nine target lifestyle behaviors that were either favorable or unfavorable in preventing obesity (i.e., screen time was an unfavorable lifestyle behavior). The score was developed using the recommendations of the Expert Committee of American Academy of Pediatrics. Score values ranged from 0-18 points; the higher the score, the more protective against high body weight.

RESULTS

The OPLS was negatively associated with obesity indices (BMI, waist circumference, and hip circumference), (p < 0.05). Control children had a higher score when compared to asthma cases (9.3 ± 2.7 vs. 8.6 ± 2.9, p = 0.007). A high OPLS was protective against physician-diagnosed asthma (OR 0.92; 95% CI 0.86-0.98, p = 0.014), adjusted for several confounders. The OPLS was no longer protective after adjustment for BMI.

CONCLUSION

Higher adherence to an obesity-preventive lifestyle score-consistent with several behaviors for the prevention of childhood overweight/obesity-is negatively associated with obesity indices and lowers the odds for asthma in children. Lifestyle behaviors that contribute to a higher body weight may contribute to the obesity-asthma link. These findings are hypothesis-generating and warrant further investigation in prospective intervention studies.

Examination of cardiovascular risk factors and rurality in Appalachian children

INTRODUCTOIN

The prevalence of childhood cardiovascular disease (CVD) risk factors often increases in more rural geographic regions in the USA. However, research on the topic often has conflicting results. Researchers note differences in definitions of rurality and other factors that would lead to differences in inference, including appropriate use of statistical clustering analysis, representative data, and inclusion of individual-level covariates. The present study's objective was to examine CVD risk factors during childhood by geographic distribution in the US Appalachian region as a first step towards understanding the health disparities in this area.

METHODS

Rurality and CVD risk factors (including blood pressure, body-mass index (BMI), and cholesterol) were examined in a large, representative sample of fifth-grade students (<i>N=</i>73 014) from an Appalachian state in the USA. A six-category Rural-Urban Continuum Codes classification system was used to define rurality regions. Mixed modeling analysis was used to appropriately cluster individuals within 725 unique zip codes in each of these six regions, and allowed for including several individual-level socioeconomic factors as covariates.

RESULTS

Rural areas had better outcomes for certain CVD risk factors (lowest low-density lipoprotein cholesterol (LDL-C), and blood pressure (BP) and highest high-density lipoprotein cholesterol (HDL-C)) whereas mid-sized metro and town areas presented with the worst CVD risk factors (highest BMI% above ideal, mean diastolic BP, LDL-C, total cholesterol, triglyceride levels and lowest HDL-C) outcomes in children and adolescence in this Appalachian state.

CONCLUSIONS

Counter to the study hypothesis, mid-sized metro areas presented with the worst CVD risk factors outcomes in children and adolescence in the Appalachian state. This data contradicts previous literature suggesting a straightforward link between rurality and cardiovascular risk factors. Future research should include a longitudinal design and explore some of the mechanisms between cardiovascular risk factors and rurality.

Lifestyle Risk Factors for Weight Gain in Children with and without Asthma

A higher proportion of children with asthma are overweight and obese compared to children without asthma; however, it is unknown whether asthmatic children are at increased risk of weight gain due to modifiable lifestyle factors. Thus, the aim of this cross-sectional study was to compare weight-gain risk factors (sleep, appetite, diet, activity) in an opportunistic sample of children with and without asthma. Non-obese children with (n = 17; age 10.7 (2.4) years) and without asthma (n = 17; age 10.8 (2.3) years), referred for overnight polysomnography, underwent measurement of lung function, plasma appetite hormones, dietary intake and food cravings, activity, and daytime sleepiness. Sleep latency (56.6 (25.5) vs. 40.9 (16.9) min, p = 0.042) and plasma triglycerides (1.0 (0.8, 1.2) vs. 0.7 (0.7, 0.8) mmol/L, p = 0.013) were significantly greater in asthmatic versus non-asthmatic children. No group difference was observed in appetite hormones, dietary intake, or activity levels (p > 0.05). Sleep duration paralleled overall diet quality (r = 0.36, p = 0.04), whilst daytime sleepiness paralleled plasma lipids (r = 0.61, p =0.001) and sedentary time (r = 0.39, p = 0.02). Disturbances in sleep quality and plasma triglycerides were evident in non-obese asthmatic children referred for polysomnography, versus non-asthmatic children. Observed associations between diet quality, sedentary behavior, and metabolic and sleep-related outcomes warrant further investigation, particularly the long-term health implications.

Effects of fetal exposure to high-fat diet or maternal hyperglycemia on L-arginine and nitric oxide metabolism in lung

Background/Objectives:

Alterations in the L-arginine/nitric oxide (NO) metabolism contribute to diseases such as obesity, metabolic syndrome and airway dysfunction. The impact of early-life exposures on the L-arginine/NO metabolism in lung later in life is not well understood. The objective of this work was to study the effects of intrauterine exposures to maternal hyperglycemia and high-fat diet (HFD) on pulmonary L-arginine/NO metabolism in mice.

Methods:

We used two murine models of intrauterine exposures to maternal (a) hyperglycemia and (b) HFD to study the effects of these exposures on the L-arginine/NO metabolism in lung in normal chow-fed offspring.

Results:

Both intrauterine exposures resulted in NO deficiency in the lung of the offspring at 6 weeks of age. However, each of the exposures leading to different metabolic phenotypes caused a distinct alteration in the L-arginine/NO metabolism. Maternal hyperglycemia leading to impaired glucose tolerance but no obesity in the offspring resulted in increased levels of asymmetric dimethylarginine and impairment of NO synthases. Although maternal HFD led to obesity without impairment in glucose tolerance in the offspring, it resulted in increased expression and activity of arginase in the lung of the normal chow-fed offspring.

Conclusions:

These data suggest that maternal hyperglycemia and HFD can cause alterations in the pulmonary L-arginine/NO metabolism in offspring.

Impaired glucose metabolism and bronchial hyperresponsiveness in obese prepubertal asthmatic children

INTRODUCTION

The prevalence of asthma and obesity has risen in parallel over the last decades, but the exact mechanisms linking these two diseases still remain unclear. The aim of the present study was to investigate the associations between bronchial hyperresponsiveness (BHR), impaired glucose metabolism, obesity, and asthma in prepubertal children.

METHODS

A total of 71 prepubertal children were included in the study and divided in four groups according to the presence of asthma and their Body Mass Index (BMI): Group 1-Healthy Controls (HC), Group 2-Non Obese Asthmatics (NOA), Group 3-Obese Non Asthmatics (ONA), Group 4-Obese Asthmatics (OA) Αll children underwent spirometry and bronchial hyperresponsiveness testing by using the cumulative Provoking Dose of mannitol (PD_15, primary study variable); homeostasis model assessment-estimated insulin resistance (HOMA-IR) index was calculated in order to evaluate insulin resistance. Obese children also underwent an oral glucose tolerance testing (OGTT).

RESULTS

A statistically significant difference in bronchial hyperreactivity (mean ± SD) was detected in the group of obese asthmatic children who had lower values ​​of PD₁₅ , (174.16 ± 126.42) as compared to normal weight asthmatic children (453.93 ± 110.27), (P < 0.001). Moreover, obese asthmatic children with confirmed insulin resistance (HOMA-IR ≥2.5), had significantly lower PD₁₅ values (89.05 ± 42.75) as ​​compared to those with HOMA-IR <2.5 (259.27 ± 125.75), (P = 0.006). Finally, obese asthmatic children with impaired OGTT had likewise significantly lower PD₁₅ (81.02 ± 42.16) measurements as compared to children with normal OGTT (267.3 ± 112.62), (P = 0.001).

CONCLUSION

Our findings suggest that obesity per se does not correlate to airway hyperreactivity unless it is accompanied by glucose intolerance and insulin resistance. Pediatr Pulmonol. 2017;52:160-166. © 2016 Wiley Periodicals, Inc.

Cholesterol-sensing liver X receptors stimulate Th2-driven allergic eosinophilic asthma in mice

INTRODUCTION

Liver X receptors (LXRs) are nuclear receptors that function as cholesterol sensors and regulate cholesterol homeostasis. High cholesterol has been recognized as a risk factor in asthma; however, the mechanism of this linkage is not known.

METHODS

To explore the importance of cholesterol homeostasis for asthma, we investigated the contribution of LXR activity in an ovalbumin- and a house dust mite-driven eosinophilic asthma mouse model.

RESULTS

In both models, airway inflammation, airway hyper-reactivity, and goblet cell hyperplasia were reduced in mice deficient for both LXRα and LXRβ isoforms (LXRα(-/-)β(-/-)) as compared to wild-type mice. Inversely, treatment with the LXR agonist GW3965 showed increased eosinophilic airway inflammation. LXR activity contributed to airway inflammation through promotion of type 2 cytokine production as LXRα(-/-)β(-/-) mice showed strongly reduced protein levels of IL-5 and IL-13 in the lungs as well as reduced expression of these cytokines by CD4(+) lung cells and lung-draining lymph node cells. In line herewith, LXR activation resulted in increased type 2 cytokine production by the lung-draining lymph node cells.

CONCLUSIONS

In conclusion, our study demonstrates that the cholesterol regulator LXR acts as a positive regulator of eosinophilic asthma in mice, contributing to airway inflammation through regulation of type 2 cytokine production.

Interaction between allergic asthma and atherosclerosis

Prior studies have established an essential role of mast cells in allergic asthma and atherosclerosis. Mast cell deficiency or inactivation protects mice from allergen-induced airway hyper-responsiveness and diet-induced atherosclerosis, suggesting that mast cells share pathologic activities in both diseases. Allergic asthma and atherosclerosis are inflammatory diseases that contain similar sets of elevated numbers of inflammatory cells in addition to mast cells in the airway and arterial wall, such as macrophages, monocytes, T cells, eosinophils, and smooth muscle cells. Emerging evidence from experimental models and human studies points to a potential interaction between the 2 seemingly unrelated diseases. Patients or mice with allergic asthma have a high risk of developing atherosclerosis or vice versa, despite the fact that asthma is a T-helper (Th)2-oriented disease, whereas Th1 immunity promotes atherosclerosis. In addition to the preferred Th1/Th2 responses that may differentiate the 2 diseases, mast cells and many other inflammatory cells also contribute to their pathogenesis by more than just T cell immunity. Here, we summarize the different roles of airway and arterial wall inflammatory cells and vascular cells in asthma and atherosclerosis and propose an interaction between the 2 diseases, although limited investigations are available to delineate the molecular and cellular mechanisms by which 1 disease increases the risk of the other. Results from mouse allergic asthma and atherosclerosis models and from human population studies lead to the hypothesis that patients with atherosclerosis may benefit from antiasthmatic medications or that the therapeutic regimens targeting atherosclerosis may also alleviate allergic asthma.

Probiotics modulate gut microbiota and health status in Japanese cedar pollinosis patients during the pollen season

BACKGROUND

Japanese cedar pollinosis (JCP) is a challenging public health problem in Japan. Altered gut microbiota is associated with several diseases, including allergic diseases. However, only a few studies have focused on JCP and the underlying mechanisms for probiotic effects remain unclear. In addition, this study is the first observation of the correlation between the gut microbiota and blood lipid in JCP.

METHODS

Faecal samples from JCP subjects were collected before and after treatment with (n = 14) and without (n = 11) LGG-TMC0356-fermented milk for 10 weeks. Gut microbiota composition was characterized from faecal DNA using sequencing of 16S rRNA genes.

RESULTS

16S rRNA-based operational taxonomic unit clustering of the microbiota revealed that LGG-TMC0356-fermented milk significantly altered gut microbiota after 10 weeks of milk consumption, and eight dominant genera of microbes were detected. During the JCP season, the Bacteroidetes/Firmicutes ratio, when compared to baseline, was significantly decreased in subjects at end of the study. Bacteroidetes showed positive correlation with LDL- and HDL-cholesterol levels, whereas Firmicutes showed negative correlation with total cholesterol, LDL- and HDL- cholesterol.

CONCLUSIONS

The altered gut microbiota through supplementation of fermented milk containing the study probiotics may be a prospective target for protection against JCP, with beneficial effects on blood lipid levels.

The Effect of Body Mass Index on Spirometric Parameters in Children with Asthma

Aim:

Asthma and obesity represent one of the most crucial public and health problems of modern society that frequently begin in childhood and have some mutual elements of risk. Abdominal distribution of connective tissue is important determinant which brings to decrease of lungs function. Multiple influence of overweight on function of the lungs would clearly manifest over reduction of forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC).

Method:

Examining was conducted at Pediatric Clinic of University Clinical Hospital Tuzla during the year 2013/2014. Research included 60 children with diagnosed asthma who were in relation to BMI were divided in 3 groups. The first group was children with BMI ranging from 5 to 85 percentile, the second were children with 85 to 95 percentile and the third was 95 percentile. By prospective study, compared identical pulmonary variable for all three age group of asthma patients were analyzed, the children with normal body mass a well as the overweight and the obese.

Results:

At the beginning of testing, the frequency of normal spirometric findings was significantly lower in the obese group in comparison with other two observed groups (p<0,05). The only cases of mixed and restrictive disorder of ventilation were registered in the obese group of tested at the beginning of the examined (p<r0,001).

Conclusion:

When being compared the values of spirometric parameters before and after the research, the only significant difference was in the obese group, the values after tests were significantly higher, with the exception of relation FEV1/FVC, that had the same distribution of values before and after research. However, the group with normal body mass and overweight, had all the spirometric parameters with equal distribution before and after research (p>0,05 for all measurements).

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.

Obesity, Asthma, and Exercise in Child and Adolescent Health

Obesity increases the risk of asthma throughout life but the underlying mechanisms linking these all too common threats to child health are poorly understood. Acute bouts of exercise, aerobic fitness, and levels of physical activity clearly play a role in the pathogenesis and/or management of both childhood obesity and asthma. Moreover, both obesity and physical inactivity are associated with asthma symptomatology and response to therapy (a particularly challenging feature of obesity-related asthma). In this article, we review current understandings of the link between physical activity, aerobic fitness and the asthma-obesity link in children and adolescents (e.g., the impact of chronic low-grade inflammation, lung mechanics, and direct effects of metabolic health on the lung). Gaps in our knowledge regarding the physiological mechanisms linking asthma, obesity and exercise are often compounded by imprecise estimations of adiposity and challenges of assessing aerobic fitness in children. Addressing these gaps could lead to practical interventions and clinical approaches that could mitigate the profound health care crisis of the increasing comorbidity of asthma, physical inactivity, and obesity in children.

Maternal high-fat hypercaloric diet during pregnancy results in persistent metabolic and respiratory abnormalities in offspring

BACKGROUND

We have shown in a previous population-based study significant correlation between childhood asthma and early abnormalities of lipid and glucose metabolism. This study's specific aim was to determine whether maternal nutrition in pregnancy affects postnatal metabolic and respiratory outcomes in the offspring.

METHODS

On gestation day 1, dams were switched from standard chow to either high-fat hypercaloric diet or control diet. Terminal experiments were performed on newborn and weanling offspring of dams fed the study diet during gestation and lactation, and on adult offspring maintained on the same diet as their mother.

RESULTS

Pups born from high-fat hypercaloric diet (HFD) dams developed metabolic abnormalities persistent throughout development. Cytokine expression analysis of lung tissues from newborns born to HFD dams revealed a strong proinflammatory pattern. Gene expression of neurotrophic factors and receptors was upregulated in lungs of weanlings born to HFD dams, and this was associated to higher respiratory system resistance and lower compliance at baseline, as well as hyperreactivity to aerosolized methacholine. Furthermore, HFD dams delivered pups prone to develop more severe disease after respiratory syncytial virus (RSV) infection.

CONCLUSION

Maternal nutrition in pregnancy is a critical determinant of airway inflammation and hyperreactivity in offspring and also increases risk for bronchiolitis independent from prepregnancy nutrition.

Metabolic Syndrome and the Lung

A link between metabolic syndrome (MetS) and lung diseases has been observed in several cross-sectional and longitudinal studies. This syndrome has been identified as an independent risk factor for worsening respiratory symptoms, greater lung function impairment, pulmonary hypertension, and asthma. This review will discuss several potential mechanisms to explain these associations, including dietary factors and the effect of adiposity and fat-induced inflammation on the lungs, and the role of other comorbidities that frequently coexist with MetS, such as OSA and obesity. In contrast to the well-known association between asthma and obesity, the recognition that MetS affects the lung is relatively new. Although some controversy remains as to whether MetS is a unique disease entity, its individual components have independently been associated with changes in pulmonary function or lung disease. There is, however, uncertainty as to the relative contribution that each metabolic factor has in adversely affecting the respiratory system; also, it is unclear how much of the MetS-related lung effects occur independently of obesity. In spite of these epidemiological limitations, the proposed mechanistic pathways strongly suggest that this association is likely to be causal. Given the wide prevalence of MetS in the general population, it is imperative that we continue to further understand how this metabolic disorder impacts the lung and how to prevent its complications.

Overlap syndrome--Asthma and obstructive sleep apnea

INTRODUCTION

Asthma is a chronic inflammatory disease with multiple phenotypes. There is still a major gap in the understanding of its complex causality. Obstructive sleep apnea (OSA) is a common condition that has been implicated as a risk factor for asthma exacerbations.

OBJECTIVES

This study aims to characterize patients with the diagnosis of asthma and suspected OSA; identify the presence of OSA and review, on the current literature, the association between asthma and OSA, as an overlap syndrome.

MATERIALS AND METHODS

The authors present a retrospective study that included patients diagnosed with asthma that underwent sleep study in a 3 year period. Demographic, clinical data, body mass index (BMI), sleep study parameters and treatments were analyzed.

RESULTS

The sample consisted of 47 patients. The majority of population was females (68%) and the mean age was 55.65 ± 13.04 years. The most common nighttime symptom was snoring (93.6%). Regarding BMI, values above the normal limit were observed in 89.36% of the patients. 68% underwent polysomnography and the others cardiorespiratory polygraphy. In 57.4% of the patients, OSA was confirmed with a higher prevalence in males (73.3%) compared to females (50%). The therapeutic approach in 81.8% of these patients was home ventilation therapy.

CONCLUSION

The combination of asthma and OSA has become increasingly more frequent. In the described study, the prevalence of OSA was 57.4%, value that is in fact higher than in general population. After the therapeutic approach, all patients referred improvement of symptoms. It is therefore essential that OSA is investigated in patients with asthma when there is poor control of symptoms, in order to achieve a better control.

The allergy epidemics: 1870-2010

Before the first description of hay fever in 1870, there was very little awareness of allergic disease, which is actually similar to the situation in prehygiene villages in Africa today. The best explanation for the appearance and subsequent increase in hay fever at that time is the combination of hygiene and increased pollen secondary to changes in agriculture. However, it is important to remember that the major changes in hygiene in Northern Europe and the United States were complete by 1920. Asthma in children did not start to increase until 1960, but by 1990, it had clearly increased to epidemic numbers in all countries where children had adopted an indoor lifestyle. There are many features of the move indoors that could have played a role; these include increased sensitization to indoor allergens, diet, and decreased physical activity, as well as the effects of prolonged periods of shallow breathing. Since 1990, there has been a remarkable increase in food allergy, which has now reached epidemic numbers. Peanut has played a major role in the food epidemic, and there is increasing evidence that sensitization to peanut can occur through the skin. This suggests the possibility that changes in lifestyle in the last 20 years could have influenced the permeability of the skin. Overall, the important conclusion is that sequential changes in lifestyle have led to increases in different forms of allergic disease. Equally, it is clear that the consequences of hygiene, indoor entertainment, and changes in diet or physical activity have never been predicted.

Serum apolipoprotein A-I and large high-density lipoprotein particles are positively correlated with FEV1 in atopic asthma

RATIONALE

Although lipids, apolipoproteins, and lipoprotein particles are important modulators of inflammation, varying relationships exist between these parameters and asthma.

OBJECTIVES

To determine whether serum lipids and apolipoproteins correlate with the severity of airflow obstruction in subjects with atopy and asthma.

METHODS

Serum samples were obtained from 154 atopic and nonatopic subjects without asthma, and 159 subjects with atopy and asthma. Serum lipid and lipoprotein levels were quantified using standard diagnostic assays and nuclear magnetic resonance (NMR) spectroscopy. Airflow obstruction was assessed by FEV1% predicted.

MEASUREMENTS AND MAIN RESULTS

Serum lipid levels correlated with FEV1 only in the subjects with atopy and asthma. Serum levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-I (apoA-I) were positively correlated with FEV1 in subjects with atopy and asthma, whereas a negative correlation existed between FEV1 and serum levels of triglycerides, low-density lipoprotein (LDL) cholesterol, apolipoprotein B (apoB), and the apoB/apoA-I ratio. NMR spectroscopy identified a positive correlation between FEV1 and HDLNMR particle size, as well as the concentrations of large HDLNMR particles and total IDLNMR (intermediate-density lipoprotein) particles in subjects with atopy and asthma. In contrast, LDLNMR particle size and concentrations of LDLNMR and VLDLNMR (very-low-density lipoprotein) particles were negatively correlated with FEV1 in subjects with atopy and asthma.

CONCLUSIONS

In subjects with atopy and asthma, serum levels of apoA-I and large HDLNMR particles are positively correlated with FEV1, whereas serum triglycerides, LDL cholesterol, and apoB are associated with more severe airflow obstruction. These results may facilitate future studies to assess whether apoA-I and large HDLNMR particles can reduce airflow obstruction and disease severity in asthma.

Platelets from Asthmatic Individuals Show Less Reliance on Glycolysis

Asthma, a chronic inflammatory airway disease, is typified by high levels of T_H2-cytokines and excessive generation of reactive nitrogen and oxygen species, which contribute to bronchial epithelial injury and airway remodeling. While immune function plays a major role in the pathogenesis of the disease, accumulating evidence suggests that altered cellular metabolism is a key determinant in the predisposition and disease progression of asthma. Further, several studies demonstrate altered mitochondrial function in asthmatic airways and suggest that these changes may be systemic. However, it is unknown whether systemic metabolic changes can be detected in circulating cells in asthmatic patients. Platelets are easily accessible blood cells that are known to propagate airway inflammation in asthma. Here we perform a bioenergetic screen of platelets from asthmatic and healthy individuals and demonstrate that asthmatic platelets show a decreased reliance on glycolytic processes and have increased tricarboxylic acid cycle activity. These data demonstrate a systemic alteration in asthma and are consistent with prior reports suggesting that oxidative phosphorylation is more efficient asthmatic individuals. The implications for this potential metabolic shift will be discussed in the context of increased oxidative stress and hypoxic adaptation of asthmatic patients. Further, these data suggest that platelets are potentially a good model for the monitoring of bioenergetic changes in asthma.

Blood lipid levels associate with childhood asthma, airway obstruction, bronchial hyperresponsiveness, and aeroallergen sensitization

BACKGROUND

Studies of children's blood lipid profiles in relation to asthma are few, and the results are ambiguous.

OBJECTIVE

We sought to examine whether the lipid profile is associated with concurrent asthma, altered lung function, and allergic sensitization in children.

METHODS

High-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride levels were measured at ages 5 to 7 years in the Copenhagen Prospective Studies on Asthma in Childhood2000 at-risk birth cohort. Asthma and allergic rhinitis were diagnosed based on predefined algorithms at age 7 years along with assessments of lung function, bronchial responsiveness, fraction of exhaled nitric oxide (Feno), and allergic sensitization. Associations between lipid levels and clinical outcomes were adjusted for sex, passive smoking, and body mass index.

RESULTS

High levels of low-density lipoprotein cholesterol were associated with concurrent asthma (adjusted odds ratio [aOR], 1.93; 95% CI, 1.06-3.55; P = .03) and airway obstruction: 50% of forced expiratory flow (aβ coefficient, -0.13 L/s; 95% CI, -0.24 to -0.03 L/s; P = .01) and specific airway resistance (aβ coefficient, 0.06 kPa/s; 95% CI, 0.00-0.11 kPa/s; P = .05). High levels of high-density lipoprotein cholesterol were associated with improved specific airway resistance (aβ coefficient, -0.11 kPa/s; 95% CI, -0.21 to -0.02; P = .02), decreased bronchial responsiveness (aβ coefficient, 0.53 log-μmol; 95% CI, 0.00-1.60 log-μmol; P = .05), decreased risk of aeroallergen sensitization (aOR, 0.27; 95% CI, 0.01-0.70; P = .01), and a trend of reduced Feno levels (aβ coefficient, -0.22 log-ppb; 95% CI, -0.50 to 0.01 log-ppb; P = .06). High triglyceride levels were associated with aeroallergen sensitization (aOR, 2.01; 95% CI, 1.14-3.56; P = .02) and a trend of increased Feno levels (aβ coefficient, 0.14 log-ppb; 95% CI, -0.02 to 0.30 log-ppb; P = .08).

CONCLUSION

The blood lipid profile is associated with asthma, airway obstruction, bronchial responsiveness, and aeroallergen sensitization in 7-year-old children. These findings suggest that asthma and allergy are systemic disorders with commonalities with other chronic inflammatory disorders.

Metabolic Syndrome Is Associated with Increased Oxo-Nitrative Stress and Asthma-Like Changes in Lungs

Epidemiological studies have shown an increased obesity-related risk of asthma. In support, obese mice develop airway hyperresponsiveness (AHR). However, it remains unclear whether the increased risk is a consequence of obesity, adipogenic diet, or the metabolic syndrome (MetS). Altered L-arginine and nitric oxide (NO) metabolism is a common feature between asthma and metabolic syndrome that appears independent of body mass. Increased asthma risk resulting from such metabolic changes would have important consequences in global health. Since high-sugar diets can induce MetS, without necessarily causing obesity, studies of their effect on arginine/NO metabolism and airway function could clarify this aspect. We investigated whether normal-weight mice with MetS, due to high-fructose diet, had dysfunctional arginine/NO metabolism and features of asthma. Mice were fed chow-diet, high-fat-diet, or high-fructose-diet for 18 weeks. Only the high-fat-diet group developed obesity or adiposity. Hyperinsulinemia, hyperglycaemia, and hyperlipidaemia were common to both high-fat-diet and high-fructose-diet groups and the high-fructose-diet group additionally developed hypertension. At 18 weeks, airway hyperresponsiveness (AHR) could be seen in obese high-fat-diet mice as well as non-obese high-fructose-diet mice, when compared to standard chow-diet mice. No inflammatory cell infiltrate or goblet cell metaplasia was seen in either high-fat-diet or high-fructose-diet mice. Exhaled NO was reduced in both these groups. This reduction in exhaled NO correlated with reduced arginine bioavailability in lungs. In summary, mice with normal weight but metabolic obesity show reduced arginine bioavailability, reduced NO production, and asthma-like features. Reduced NO related bronchodilation and increased oxo-nitrosative stress may contribute to the pathogenesis.

Gender differences in objectively assessed physical activity in asthmatic and non-asthmatic children

OBJECTIVE

To compare objectively assessed physical activity levels, between asthmatic children and non-asthmatic controls.

METHODS

From a random community sample of 794 children aged 8-9 years, in a case-control design, 104 children with ever doctor's diagnosis of asthma and 99 non-asthmatic controls were recruited and had assessment of physical activity with biaxial accelerometers for 7 days.

RESULTS

Children with active (also reporting at least one episode of wheezing in the last 12 months) and inactive (no wheezing in past 12 months) asthma appeared to have similar physical activity and sedentary activity levels compared to non-asthmatic children. However, girls with active asthma had significantly lower moderate-to-vigorous physical activity (MVPA) levels than their peers with adjusted geometric mean ratio of 0.59 (95% CI: 0.369, 0.929, P-value = 0.024). No difference in physical and sedentary activity levels was observed between asthmatic and non-asthmatic boys. The difference between genders in the comparison of MVPA levels in asthmatics and controls was statistically significant (P-value of likelihood ratio test [LRT] for effect modification by gender = 0.034).

CONCLUSIONS

Unlike boys, girls with active asthma appear to be less active than their healthy peers, and this gender difference might explain the inconsistent evidence from previous reports on physical activity levels in asthmatic children. Further studies are needed to confirm the gender interaction in the childhood asthma-physical activity relation and the implications on current guidelines for physical exercise prescriptions in asthmatic children.

Inflammation, metabolic dysregulation, and pulmonary function among obese urban adolescents with asthma

RATIONALE

Insulin resistance and low high-density lipoprotein (HDL) are associated with pulmonary morbidity, including asthma, but the underlying mechanisms are not well elucidated.

OBJECTIVES

To investigate whether systemic inflammation underlies the association of metabolic abnormalities with pulmonary function among urban adolescents.

METHODS

Th-cell responses and monocyte subsets, and their association with serum homeostatic model assessment of insulin resistance (HOMA-IR) and HDL, and pulmonary function were quantified in 168 adolescents, including 42 obese subjects with asthma, 42 normal-weight subjects with asthma, 40 obese subjects without asthma, and 44 healthy control subjects. Th-cell responses (Th1 [CD4(+)IFNγ(+)] and Th2 [CD4(+)IL4(+)] cells) to stimulation with phytohemagglutinin, leptin, and dust mite, and classical (CD14(+)CD16(-)), resident (CD14(+)CD16(+)), and patrolling (CD14dimCD16(+)) monocytes, and their C-C chemokine receptor type-2 (CCR2) expression were quantified by flow cytometry.

MEASUREMENTS AND MAIN RESULTS

Th1/Th2 ratio to all three stimuli was higher in obese subjects with asthma than normal-weight subjects with asthma and directly correlated with HOMA-IR. Classical monocytes inversely associated with Th1/Th2 ratio to phytohemagglutinin (r = -0.43; P = 0.01) and directly with Asthma Control Test score (β = 1.09; P = 0.04), while patrolling monocytes correlated with Composite Asthma Severity Index score (β = 1.11; P = 0.04) only among obese subjects with asthma. HDL was inversely associated with patrolling monocytes and directly associated with CCR2 expression on resident monocytes. CCR2 expression on patrolling monocytes predicted residual volume (RV), RV/TLC ratio, and FRC, after adjusting for HDL, but not after adjusting for body mass index. Association of Th1/Th2 ratio with RV, FRC, and inspiratory capacity was attenuated after adjusting for HOMA-IR.

CONCLUSIONS

Th1 polarization and monocyte activation among obese subjects with asthma correlates with metabolic abnormalities. Association of monocyte activation with pulmonary function is mediated by body mass index, whereas that of Th1 polarization is mediated by insulin resistance.

Insulin resistance, metabolic syndrome, and lung function in US adolescents with and without asthma

BACKGROUND

Obesity increases both the risk of asthma and asthma severity and is a well-known risk factor for insulin resistance and the metabolic syndrome (MS) in children and adolescents.

OBJECTIVE

We aimed to examine the association among obesity, insulin sensitivity, MS, and lung function in US adolescents with and without asthma.

METHODS

We performed a cross-sectional study of 1429 adolescents aged 12 to 17 years in the 2007-2010 National Health and Nutrition Examination Survey. Adjusted regression was used to assess the relationships among obesity, insulin sensitivity/resistance, MS, and lung function in children with and without asthma.

RESULTS

Insulin resistance was negatively associated with FEV1 and forced vital capacity (FVC) in adolescents with and without asthma, whereas MS was associated with lower FEV1/FVC ratios, with a more pronounced decrease found among asthmatic patients; these associations were driven by overweight/obese adolescents. Higher body mass index was associated with a decrease in FEV1/FVC ratios among adolescents with insulin resistance. Compared with healthy participants, adolescents with MS had an approximately 2% decrease in FEV1/FVC ratios, adolescents with asthma had an approximately 6% decrease, and those with MS and asthma had approximately 10% decreased FEV1/FVC ratios (P < .05).

CONCLUSION

Insulin resistance and MS are associated with worsened lung function in overweight/obese adolescents. Asthma and MS synergistically decrease lung function, as do obesity and insulin resistance. These factors might contribute to the pathogenesis of asthma severity in obese patients and warrant further investigation.

Association of pulmonary function with adiposity and metabolic abnormalities in urban minority adolescents

RATIONALE

Childhood obesity is a known risk factor for pulmonary diseases, likely due to obesity-mediated alteration of pulmonary function. Inflammation and mechanical fat load are two proposed causative mechanisms for altered pulmonary function among obese children; however, the association of metabolic abnormalities with pulmonary function among children is poorly understood.

OBJECTIVES

We investigated the independent association of truncal and general adiposity and metabolic abnormalities with pulmonary function in a sample of urban minority adolescents.

METHODS

Spirometry and lung volume indices were compared between adolescents with general (body mass index [BMI] > 95th percentile) or truncal adiposity (waist circumference > 90th percentile) and normal-weight (BMI < 85th percentile or waist circumference ≤ 90th percentile) and between those with metabolic abnormalities (homeostatic model assessment of insulin resistance [HOMA-IR] in the top quartile or high-density lipoprotein [HDL] < 40 mg/dl) and those with a normal metabolic profile.

MEASUREMENTS AND MAIN RESULTS

Obese adolescents had lower lung volumes, including residual volume (RV), RV/TLC ratio, expiratory reserve volume (ERV), and FRC, and higher inspiratory capacity (IC) than normal-weight adolescents, but did not differ in measures of lower airway obstruction, FEV1/FVC ratio, and mid-expiratory flow rate. Adolescents with high HOMA-IR had lower FEV1/FVC ratio, RV, RV/TLC ratio, ERV, and FRC and higher IC, whereas those with low HDL had lower FEV1/FVC and RV/TLC ratios. After adjusting for adiposity, HOMA-IR remained a predictor of ERV (β = -1.4; P = 0.02) and FEV1/FVC ratio (β = -0.5; P = 0.03), and HDL remained a predictor of FEV1/FVC ratio (β = 0.1; P = 0.01). General adiposity was a predictor of FRC (β = -0.5; P < 0.001), IC (β = 0.3; P < 0.001), RV (β = -0.8; P < 0.0001), and RV/TLC ratio (β = -0.2; P < 0.0001), and truncal adiposity was a predictor of RV (β = -20.3; P = 0.03) and FRC (β = -13.8; P = 0.004). Thus, adiposity and metabolic abnormalities were independent predictors of ERV, but only metabolic abnormalities independently predicted FEV1/FVC ratio. Although general adiposity predicted RV and RV/TLC ratio, truncal adiposity was predictive of RV and FRC, conferring additional risk above general adiposity.

CONCLUSIONS

These results suggest that metabolic abnormalities and adiposity are independently associated with pulmonary function deficits among urban adolescents. Metabolic assessment of obese adolescents may identify those at risk of developing obesity-associated pulmonary morbidity.

Asthma and obesity in children: current evidence and potential systems biology approaches

Both obesity and asthma are highly prevalent, complex diseases modified by multiple factors. Genetic, developmental, lung mechanical, immunological and behavioural factors have all been suggested as playing a causal role between the two entities; however, their complex mechanistic interactions are still poorly understood and evidence of causality in children remains scant. Equally lacking is evidence of effective treatment strategies, despite the fact that imbalances at vulnerable phases in childhood can impact long-term health. This review is targeted at both clinicians frequently faced with the dilemma of how to investigate and treat the obese asthmatic child and researchers interested in the topic. Highlighting the breadth of the spectrum of factors involved, this review collates evidence regarding the investigation and treatment of asthma in obese children, particularly in comparison with current approaches in 'difficult-to-treat' childhood asthma. Finally, the authors propose hypotheses for future research from a systems-based perspective.

Effects of dietary induced weight loss on exercise-induced bronchoconstriction in overweight and obese children

RATIONALE

Previous studies showed that obesity in asthmatic children is associated with more severe exercise-induced bronchoconstriction (EIB), compared with non-obese asthmatic children. This study investigates the effect of weight loss on EIB in overweight and obese asthmatic children.

METHODS

In this intervention study, children aged 8-18 years with EIB and moderate to severe overweight, followed a diet based on healthy daily intake for 6 weeks. Before and after the diet period they underwent an exercise challenge test in cold air. Primary outcome was change in exercise-induced fall in FEV1 and relation between weight loss and EIB. Secondary outcomes were changes in recovery of FEV1 ("area under the curve"; AUC), fraction of exhaled nitric oxide (FeNO) and scores of the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) and Asthma Control Questionnaire (ACQ).

RESULTS

Twenty children completed the study. After the diet period, weight, and body mass index (BMI) were significantly reduced (changes respectively -2.6% and -1.5 kg/m(2), P < 0.01). There was a significant improvement of the percentage exercise-induced fall in FEV1 (30.6% vs. 21.8%, P < 0.01), AUC and PAQLQ score. The reduction in BMI z-score was significantly related to the reduction in the percentage exercise-induced fall in FEV1 in children that lost weight (r = 0.53, P = 0.03). There were no changes in FeNO and ACQ.

CONCLUSIONS

Dietary induced weight loss in overweight and obese asthmatic children leads to significant reduction in severity of EIB and improvement of the quality of life. The reduction in BMI z-score is significantly related to the improvement of EIB.

Asthma: the role of low high-density-lipoprotein cholesterol in childhood and adolescence

BACKGROUND

Several studies have examined the relationship of asthma with serum dyslipidemia and reported positive, negative or no association. Most studies were limited by their cross-sectional design and the wide age range of the participants. In a cohort of children in Cyprus, we explored the association of asthma with serum high-density-lipoprotein cholesterol (HDL-C) at age 16-18 years (follow-up) independently of and in relation to HDL-C at age 11-12 years (baseline).

METHODS

In a case-control design, we recruited active asthmatics (AA; n = 68), current wheezers only (CWO; n = 123) and non-asthmatic controls (n = 660). Logistic regression models were used to evaluate associations of asthma with follow-up serum HDL-C and the role of baseline HDL-C.

RESULTS

At follow-up, mean HDL-C levels in AA and CWO patients were significantly lower than in the controls (47.9 and 49.7 vs. 53.4 mg/dl; p = 0.001 and p = 0.011). We observed significant associations of AA patients with low HDL-C (<15th percentile; OR 2.32, 95% CI 1.16-4.47) that remained significant after further adjustment for baseline HDL-C (OR 2.14, 95% CI 1.06-4.14). Stratification by baseline HDL-C indicated that the association was significant only in those with high baseline HDL-C (OR 2.40, 95% CI 1.03-5.20). Stratification by IgE sensitization showed that the association was pronounced only in subjects who were sensitized (OR 3.41, 95% CI 1.12-9.88).

CONCLUSIONS

Adolescent asthma is associated with low serum HDL-C independent of previous HDL-C levels in childhood. The association appears pronounced in those with a drop in HDL-C levels between childhood and adolescence and in those who have IgE sensitization.

Asthma and insulin resistance in obese children and adolescents

BACKGROUND

Obese children and adolescents have an increased risk for asthma. A few studies have evaluated the association of insulin resistance and asthma in obese pediatric populations. We examined whether there was a relationship between high degrees of insulin resistance and the presence of asthma in obese children and adolescents.

METHODS

A total of 153 patients aged 4-15 years with at or above the 95th percentile BMI for age were prospectively recruited. Assessments included diagnosis of asthma, skin prick test reactivity to common environmental aeroallergens, and HOMA estimated insulin resistance, with the median (2.22) used as a cutoff value to categorize insulin resistance.

RESULTS

There were 56 (36.6%) asthmatic and 97 (63.4%) non-asthmatic patients. HOMA values were significantly associated with positive skin tests (p = 0.008) and allergic asthma diagnosis (p = 0.016). Baseline insulin value was significantly associated with the risk of presenting asthma with positive skin testing (odds ratio 1.084, p = 0.037). Differences in age, BMI, and waist circumference were found between the groups of HOMA-IR <2.22 and ≥2.22. Waist circumference (WC) was significantly associated with FVC (p = 0.0001) and FEV1 (p < 0.0003); the greater the WC, the lower FVC and FEV1 values.

CONCLUSIONS

Insulin resistance is a risk for allergic asthma in obese children and adolescents. Waist circumference was related to CVF and FEV1 impairment.

Hyperinsulinemia potentiates airway responsiveness to parasympathetic nerve stimulation in obese rats

Obesity is a substantial risk factor for developing asthma, but the molecular mechanisms underlying this relationship are unclear. We tested the role of insulin in airway responsiveness to nerve stimulation using rats genetically prone or resistant to diet-induced obesity. Airway response to vagus nerve stimulation and airway M2 and M3 muscarinic receptor function were measured in obese-prone and -resistant rats with high or low circulating insulin. The effects of insulin on nerve-mediated human airway smooth muscle contraction and human M2 muscarinic receptor function were tested in vitro. Our data show that increased vagally mediated bronchoconstriction in obesity is associated with hyperinsulinemia and loss of inhibitory M2 muscarinic receptor function on parasympathetic nerves. Obesity did not induce airway inflammation or increase airway wall thickness. Smooth muscle contraction to acetylcholine was not increased, indicating that hyperresponsiveness is mediated at the level of airway nerves. Reducing serum insulin with streptozotocin protected neuronal M2 receptor function and prevented airway hyperresponsiveness to vagus nerve stimulation in obese rats. Replacing insulin restored dysfunction of neuronal M2 receptors and airway hyperresponsiveness to vagus nerve stimulation in streptozotocin-treated obese rats. Treatment with insulin caused loss of M2 receptor function, resulting in airway hyperresponsiveness to vagus nerve stimulation in obese-resistant rats, and inhibited human neuronal M2 receptor function in vitro. This study shows that it is not obesity per se but hyperinsulinemia accompanying obesity that potentiates vagally induced bronchoconstriction by inhibiting neuronal M2 muscarinic receptors and increasing acetylcholine release from airway parasympathetic nerves.