Metabolic abnormalities in children with asthma

Lung function trajectories from school age to adulthood and their relationship with markers of cardiovascular disease risk

RATIONALE

Lung function in early adulthood is associated with subsequent adverse health outcomes.

OBJECTIVES

To ascertain whether stable and reproducible lung function trajectories can be derived in different populations and investigate their association with objective measures of cardiovascular structure and function.

METHODS

Using latent profile modelling, we studied three population-based birth cohorts with repeat spirometry data from childhood into early adulthood to identify trajectories of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). We used multinomial logistic regression models to investigate early-life predictors of the derived trajectories. We then ascertained the extent of the association between the derived FEV1/FVC trajectories and blood pressure and echocardiographic markers of increased cardiovascular risk and stroke in ~3200 participants at age 24 years in one of our cohorts.

RESULTS

We identified four FEV1/FVC trajectories with strikingly similar latent profiles across cohorts (pooled N=6377): above average (49.5%); average (38.3%); below average (10.6%); and persistently low (1.7%). Male sex, wheeze, asthma diagnosis/medication and allergic sensitisation were associated with trajectories with diminished lung function in all cohorts. We found evidence of an increase in cardiovascular risk markers ascertained by echocardiography (including left ventricular mass indexed to height and carotid intima-media thickness) with decreasing FEV1/FVC (with p values for the mean crude effects per-trajectory ranging from 0.10 to p<0.001). In this analysis, we considered trajectories as a pseudo-continuous variable; we confirmed the assumption of linearity in all the regression models.

CONCLUSIONS

Childhood lung function trajectories may serve as predictors in the development of not only future lung disease, but also the cardiovascular disease and multimorbidity in adulthood.

Prevalence of Metabolic Abnormalities and their Association with Asthma Symptom Control in Children

OBJECTIVES

To determine the prevalence of insulin resistance (IR), dyslipidemia and metabolic syndrome (MS) in children with asthma, aged 10 to 15 y, and to determine if these metabolic abnormalities showed an association with asthma symptom control and lung function.

METHODS

A cross-sectional study was conducted at a tertiary centre in north India. Consecutive children with physician diagnosed asthma were enrolled. Asthma symptom control over previous four weeks was assessed as per Global Initiative for Asthma (GINA) recommendations. Fasting plasma glucose, serum insulin and lipid levels were estimated. Homeostasis Model Assessment- Insulin Resistance (HOMA-IR) was used as a marker of IR. Spirometry was performed for assessing lung function.

RESULTS

Eighty-three children were enrolled. Median (IQR) age was 12.0 (11.0, 13.5) y and mean (SD) body mass index (BMI) Z score was -0.42 (1.0). Median (IQR) HOMA-IR was 1.65 (1.06, 2.39). Prevalence of IR was 42.3% (95% CI: 31.7-52.9%). Number of children with elevated triglycerides, total cholesterol, and low-density lipoprotein (LDL)-cholesterol was 4 (4.8%), 4 (4.8%) and 5 (6%), respectively. Sixty-seven (80.7%) children had low high-density lipoprotein (HDL)-cholesterol. Only one subject was found to have metabolic syndrome. Presence of IR and elevation in serum insulin and triglycerides were associated with poorer asthma control, independent of BMI. None of the metabolic parameters were associated with lung function, after adjusting for height.

CONCLUSIONS

Among children with asthma, aged 10 to 15 y, the prevalence of IR was 42.3% (95% CI: 31.7-52.9%). Elevated serum insulin, triglycerides, and presence of IR were associated with poorer asthma control, after adjusting for BMI.

The relationship between lipid parameters and the course of allergic rhinitis in children

Introduction

A possible mechanism in the pathogenesis of allergic rhinitis (AR) is hypercholesterolemia, which may shift the balance between Th1- and Th2-dependent immune responses towards the latter.

Aim

To assess the prevalence of lipid metabolism abnormalities in children with AR and their influence on the clinical course of AR.

Material and methods

The study sample comprised 80 children (7-17 y.o.) with AR, including 28 with associated asthma, and 40 healthy children. Total blood cholesterol, HDL, LDL and triglyceride levels were evaluated (ARCHITECTcSystem). Skin prick tests (Allergopharma) for airborne allergens and a methacholine challenge test (Lungtest 1000, Ispa) were performed. Allergen-specific IgE for airborne allergens (Biocheck GmbH), FeNO and nNO concentrations (HypAir FeNO Medisoft) were measured.

Results

Children with AR were significantly more likely to have normal HDL levels than the control group (n = 70; 87.5% vs. n = 27; 67.50%; p = 0.03). No significant differences were observed between these two groups regarding total cholesterol, LDL or triglyceride levels (p > 0.05). Abnormally high total cholesterol levels were associated with a higher risk of sensitisation to D. pteronyssinus (n = 18; 72%, p = 0.023). Children with normal levels of total cholesterol and normal triglyceride values were less likely to be sensitized to dog dander (n = 43; 78.18%, p = 0.049) (n = 42; 72.41%, p = 0.042). No significant correlations were observed between lipid parameters and the clinical course of AR, FeNO concentrations, nNO concentrations and bronchial hyperreactivity in children with AR (p > 0.05).

Conclusions

Children with AR are as likely to demonstrate dyslipidaemia as the general population. However, the presence of lipid abnormalities in this group may increase the likelihood of sensitization to perennial allergens.

Platycoside E alleviates allergic airway inflammation in obesity-related asthma mouse model

BACKGROUND

Overweight and obesity are related to an increased risk of asthma. The effect of platycoside E (PE) on obesity-related asthma remains unknown.

METHODS

To mimic obesity-related asthma conditions in vivo, C57BL/6 mice were exposed to a high-fat diet (HFD) and challenged with ovalbumin (OVA). PE was administrated intraperitoneally during the OVA treatment. Body weight was measured at 8th week before PE treatment and after sacrificing the mice. Airway inflammation and airway hyperresponsiveness (AHR) were evaluated. Immunohistochemistry staining was performed to evaluate eosinophils. Histopathological changes were determined by HE staining. Cellular model of asthma was established using IL-13 in BEAS-2B cells. Levels of proinflammatory cytokines and oxidative stress indicators were measured by ELISA kits and commercial kits, respectively. Cell viability was detected by CCK-8 assays.

RESULTS

IL-13 treatment led to inflammatory and oxidative damage in bronchial epithelial cells, which was relieved by PE. PE administration significantly reduced HFD-induced obesity and relieved AHR and airway inflammation in obese asthmatic mice. The expression of proinflammatory cytokines in BALF and lung tissues in obese asthmatic mice were reduced by PE. PE administration also reduced infiltration of eosinophils and inflammation scores in obese asthmatic mice.

CONCLUSION

PE suppresses airway inflammation and AHR in obese asthmatic mice and serves as an effective option for treating obesity-related asthma.

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.

Exhaled volatile organic compounds for diagnosis and monitoring of asthma

The asthmatic inflammatory process results in the generation of volatile organic compounds (VOCs), which are subsequently secreted by the airways. The study of these elements through gas chromatography-mass spectrometry (GC-MS), which can identify individual molecules with a discriminatory capacity of over 85%, and electronic-Nose (e-NOSE), which is able to perform a quick onboard pattern-recognition analysis of VOCs, has allowed new prospects for non-invasive analysis of the disease in an "omics" approach. In this review, we aim to collect and compare the progress made in VOCs analysis using the two methods and their instrumental characteristics. Studies have described the potential of GC-MS and e-NOSE in a multitude of relevant aspects of the disease in both children and adults, as well as differential diagnosis between asthma and other conditions such as wheezing, cystic fibrosis, COPD, allergic rhinitis and last but not least, the accuracy of these methods compared to other diagnostic tools such as lung function, FeNO and eosinophil count. Due to significant limitations of both methods, it is still necessary to improve and standardize techniques. Currently, e-NOSE appears to be the most promising aid in clinical practice, whereas GC-MS, as the gold standard for the structural analysis of molecules, remains an essential tool in terms of research for further studies on the pathophysiologic pathways of the asthmatic inflammatory process. In conclusion, the study of VOCs through GC-MS and e-NOSE appears to hold promise for the non-invasive diagnosis, assessment, and monitoring of asthma, as well as for further research studies on the disease.

Dyslipidemia Is Associated With Worse Asthma Clinical Outcomes: A Prospective Cohort Study

BACKGROUND

Dyslipidemia has been widely documented to be associated with cardiovascular disease, and recent studies have found an association with asthma prevalence. However, longitudinal studies investigating the relationships between dyslipidemia, asthma phenotypes, and future asthma exacerbations (AEs) are lacking.

OBJECTIVE

To investigate the relationships between dyslipidemia, asthma phenotypes, and AEs.

METHODS

This study used an observational cohort study design with a 12-month follow-up. All subjects underwent serum lipid measurement, and they were then classified into 2 groups: the normal-lipidemia group and the dyslipidemia group. Demographic and clinical information and details regarding pulmonary function and asthma phenotypes at baseline were collected. All patients were followed up regularly to assess AEs. Associations of dyslipidemia with airway obstruction and asthma phenotypes were assessed at baseline, whereas dyslipidemia and AEs were assessed longitudinally.

RESULTS

A total of 477 patients with asthma were consecutively enrolled in this study. At baseline, the dyslipidemia group (n = 218) had a higher proportion of uncontrolled asthma, defined by the 6-item Asthma Control Questionnaire score (≥1.5). Furthermore, dyslipidemia was associated with severe asthma, nonallergic asthma, asthma with fixed airflow limitation, and older adult asthma phenotypes at baseline. In addition, dyslipidemia was associated with increased frequencies of severe AEs and moderate to severe AEs during the 12-month follow-up. In sensitivity analyses, after excluding the patients who were receiving statins, results did not differ significantly from those of the main analysis.

CONCLUSIONS

We identified the clinical relevance of dyslipidemia, which is associated with specific asthma phenotypes and increased AEs, independent of other components of metabolic syndrome. These findings highlight the importance of considering dyslipidemia as an "extrapulmonary trait" in asthma management.

Pediatric obesity and severe asthma: Targeting pathways driving inflammation

Asthma affects more than 300 million people of all ages worldwide, including about 10-15% of school-aged children, and its prevalence is increasing. Severe asthma (SA) is a particular and rare phenotype requiring treatment with high-dose inhaled corticosteroids plus a second controller and/or systemic glucocorticoid courses to achieve symptom control or remaining "uncontrolled" despite this therapy. In SA, other diagnoses have been excluded, and potential exacerbating factors have been addressed. Notably, obese asthmatics are at higher risk of developing SA. Obesity is both a major risk factor and a disease modifier of asthma in children and adults: two main "obese asthma" phenotypes have been described in childhood with high or low levels of Type 2 inflammation biomarkers, respectively, the former characterized by early onset and eosinophilic inflammation and the latter by neutrophilic inflammation and late-onset. Nevertheless, the interplay between obesity and asthma is far more complex and includes obese tissue-driven inflammatory pathways, mechanical factors, comorbidities, and poor response to corticosteroids. This review outlines the most recent findings on SA in obese children, particularly focusing on inflammatory pathways, which are becoming of pivotal importance in order to identify selective targets for specific treatments, such as biological agents.

Metabolic Contributions to Pathobiology of Asthma

Asthma is a heterogenous disorder driven by inflammatory mechanisms that result in multiple phenotypes. Given the complex nature of this condition, metabolomics is being used to delineate the pathobiology of asthma. Metabolomics is the study of metabolites in biology, which includes biofluids, cells, and tissues. These metabolites have a vital role in a disease as they contribute to the pathogenesis of said condition. This review describes how macrometabolic and micrometabolic studies pertaining to these metabolites have contributed to our current understanding of asthma, as well as its many phenotypes. One of the main phenotypes this review will discuss in further detail is obesity as well as diabetes. Distinct roles of metabolites in endotyping asthma and their translation to potential therapy development for asthma is also discussed in this review.

Life Course of Asthma

Asthma is a heterogeneous chronic airway disease that can vary over a lifetime. Although broad categories of asthma by severity and type have been constructed, there remains a tremendous opportunity to discover an approach to managing asthma with additional factors in mind. Many in the field have suggested and are pursuing a novel paradigm shift in how asthma might be better managed, considering the life course of exposures, management priorities, and predicted trajectory of lung function growth. This approach will require a more holistic view of prenatal, postnatal, adolescence, hormonal and gender aspects, and the aging process. In addition, the environment, externally and internally, including in one's genetic code and epigenetic changes, are factors that affect how asthma progresses or becomes more stable in individuals. This chapter focuses on the various influences that may, to differing degrees, affect people with asthma, which can develop at any time in their lives. Shifting the paradigm of thought and strategies for care and advocating for public policies and health delivery that focus on this philosophy is paramount to advance asthma care for all.

Mid-childhood fat mass and airflow limitation at 15 years: The mediating role of insulin resistance and C-reactive protein

BACKGROUND

We previously reported an association of high fat mass levels from age 9 to 15 years with lower forced expiratory flow in 1 s (FEV₁ )/forced vital capacity (FVC) ratio (i.e., increased risk of airflow limitation) at 15 years. Here, we aimed to assess whether insulin resistance and C-reactive protein (CRP) at 15 years partially mediate this association.

METHODS

We included 2263 children from the UK Avon Longitudinal Study of Parents and Children population-based cohort (ALSPAC). Four fat mass index (FMI) trajectories ("low," "medium-low," "medium-high," "high") from 9 to 15 years were previously identified using Group-Based Trajectory Modeling. Data on CRP, glucose, insulin, and post-bronchodilator FEV₁ /FVC were available at 15 years. We defined insulin resistance by the homeostasis model assessment-estimated insulin resistance index (HOMA-IR). We used adjusted linear regression models and a causal mediation analysis to assess the mediating role of HOMA-IR and CRP.

RESULTS

Compared to children in the "low" FMI trajectory, children in the "medium-high" and "high" FMI trajectories had lower FEV₁ /FVC at 15 years. The percentage of the total effect explained by HOMA-IR was 19.8% [-114.1 to 170.0] and 20.4% [1.6 to 69.0] for the "medium-high" and "high" trajectories, respectively. In contrast, there was little evidence for a mediating role of CRP.

CONCLUSION

The association between mid-childhood fat mass and FEV₁ /FVC ratio at 15 years may be partially mediated by insulin resistance.

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.

Obesity elicits a unique metabolomic signature in human airway smooth muscle cells

Obesity can aggravate asthma by enhancing airway hyperresponsiveness (AHR) and attenuating response to treatment. However, the precise mechanisms linking obesity and asthma remain unknown. Human airway smooth muscle (HASM) cells exhibit amplified excitation-contraction (EC) coupling and force generation in obesity. Therefore, we posit that airway smooth muscle (ASM) cells obtained from obese donors manifest a metabolomic phenotype distinct from that of nonobese donor cells and that a differential metabolic phenotype, at least in part, drives enhanced ASM cell EC coupling. HASM cells derived from age-, sex-, and race-matched nonobese [body mass index (BMI) ≤ 24.9 kg·m-2] and obese (BMI ≥ 29.9 kg·m-2) lung donors were subjected to unbiased metabolomic screening. The unbiased metabolomic screening identified differentially altered metabolites linked to glycolysis and citric acid cycle in obese donor-derived cells compared with nonobese donor cells. The Seahorse assay measured the bioenergetic profile based on glycolysis, mitochondrial respiration, palmitate oxidation, and glutamine oxidation rates in HASM cells. Glycolytic rate and capacity were elevated in obese donor-derived HASM cells, whereas mitochondrial respiration, palmitate oxidation, and glutamine oxidation rates were comparable between obese and nonobese groups. PFKFB3 mRNA and protein expression levels were also elevated in obese donor-derived HASM cells. Furthermore, pharmacological inhibition of PFKFB3 attenuated agonist-induced myosin light chain (MLC) phosphorylation in HASM cells derived from obese and nonobese donors. Our findings identify elevated glycolysis as a signature metabolic phenotype of obesity and inhibition of glycolysis attenuates MLC phosphorylation in HASM cells. These findings identify novel therapeutic targets to mitigate AHR in obesity-associated asthma.

Comorbidities in childhood-onset and adult-onset asthma

BACKGROUND

Age of asthma onset has emerged as an important determinant of asthma phenotypes; however, the comorbidities that predominate in either childhood- or adult-onset asthma are not known.

OBJECTIVE

To identify comorbidities associated with adult-onset asthma vs childhood-onset asthma and with age of asthma diagnosis.

METHODS

We analyzed data on 27,437 adult participants in the National Health and Nutrition Examination Surveys conducted from 2001 to 2018. Logistic regression adjusted for covariates was used to identify comorbidities associated with the asthma phenotypes and age of asthma diagnosis.

RESULTS

Approximately 12.6% of participants were ever diagnosed with asthma; the prevalence of childhood-onset (before 18 years old) and adult-onset (≥ 18 years old) current asthma was 2.7% and 5.5%, respectively. After adjustment for covariates including age, adult-onset asthma was associated with higher odds of obesity (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.09-1.96), hypercholesterolemia (OR, 1.67; 95% CI, 1.08-2.56), borderline high serum triglycerides (OR, 1.78; 95% CI, 1.17-2.71), and osteoarthritis (OR, 1.52; 95% CI, 1.04-2.20) than was childhood-onset asthma. Older age of asthma diagnosis (per 5-year increase) was also associated with higher odds of diabetes (OR, 1.04; 95% CI, 1.00-1.07) and hypertension (OR, 1.05; 95% CI, 1.02-1.07), whereas younger age of asthma diagnosis was associated with higher odds of chronic obstructive pulmonary disease (OR, 1.12; 95% CI, 1.04-1.19).

CONCLUSION

Age- and covariates-adjusted prevalence of obesity, dyslipidemia, arthritis, diabetes, and hypertension is higher in adult-onset asthma than in childhood-onset asthma, and with older age of asthma diagnosis. Conversely, the prevalence of chronic obstructive pulmonary disease increases with younger age of asthma diagnosis.

Pediatric asthma and non-allergic comorbidities: a review of current risk and proposed mechanisms

It is increasingly recognized that children with asthma are at a higher risk of other non‐allergic concurrent diseases than the non‐asthma population. A plethora of recent research has reported on these comorbidities and progress has been made in understanding the mechanisms for comorbidity. The goal of this review was to assess the most recent evidence (2016–2021) on the extent of common comorbidities (obesity, depression and anxiety, neurodevelopmental disorders, sleep disorders and autoimmune diseases) and the latest mechanistic research, highlighting knowledge gaps requiring further investigation. We found that the majority of recent studies from around the world demonstrate that children with asthma are at an increased risk of having at least one of the studied comorbidities. A range of potential mechanisms were identified including common early life risk factors, common genetic factors, causal relationships, asthma medication and embryologic origins. Studies varied in their selection of population, asthma definition and outcome definitions. Next, steps in future studies should include using objective measures of asthma, such as lung function and immunological data, as well as investigating asthma phenotypes and endotypes. Larger complex genetic analyses are needed, including genome‐wide association studies, gene expression–functional as well as pathway analyses or Mendelian randomization techniques; and identification of gene–environment interactions, such as epi‐genetic studies or twin analyses, including omics and early life exposure data. Importantly, research should have relevance to clinical and public health translation including clinical practice, asthma management guidelines and intervention studies aimed at reducing comorbidities.

Challenges in uncontrolled asthma in pediatrics: important considerations for the clinician

INTRODUCTION

Despite symptoms control being the primary focus of asthma management according to guidelines, uncontrolled asthma is still an issue worldwide, leading to huge costs and asthma deaths at all ages. In childhood, poor asthma control can be even more harmful, as it can irreversibly compromise the children's lung function and the whole family's well-being.

AREAS COVERED

Given the problem extent, this review aims to discuss the leading modifiable causes of uncontrolled asthma in Pediatrics, giving some practical insights regarding the critical role of families and the main tools for monitoring control and drug adherence, even at a distance. The most recent GINA documents were used as the primary reference, along with the latest evidence regarding the management of asthma control and the impact of the COVID-19 pandemic on asthma.

EXPERT OPINION

In managing pediatric asthma, a multidisciplinary, multi-determinant, personalized approach is needed, actively involving families, schools, and other specialists. In addition to current strategies for implementing control, electronic health strategies, new validated asthma control tools, and the identification of novel inflammatory biomarkers could lead to increasingly tailored therapies with greater effectiveness in reaching asthma control.

The Prevalence of Metabolic Syndrome, Scoring, and Comparison in People With and Without COPD: Evidence from Shahrekord PERSIAN Cohort Study

Background: Comorbidities are common in patients with chronic obstructive pulmonary diseases (COPDs), including metabolic syndrome (MetS). This study aimed to determine the prevalence of MetS and its components in people with and without COPD. Methods: This population-based study was performed on 6961 adults in the Shahrekord Prospective Epidemiological Research Studies in Iran. Data collection, spirometry, and COPD diagnosis were performed according to the cohort protocol from 2015 to 2019. The data were analyzed by two independent sample t-tests, analysis of covariance, chi-square, and odds ratio (OR) with 95% confidence interval (95% CI) in logistic regression models. P value <0.05 was considered statistically significant. All analyses were conducted using Stata Statistical Software Release 16 (Stata Corp., College Station, TX). Results: The prevalence of MetS in patients with and without COPD was 28.4% and 31%, respectively. The most common components of MetS in people with COPD were low high-density lipoprotein cholesterol (47.4%), waist circumference (43.9%), and high fasting plasma glucose (39.3%). There was a statistically significant difference in the frequency of respiratory dysfunction between people with and without MetS. Being older than 60 (OR = 2.20, 95% CI: 1.72-2.80), female (OR = 1.36, 95% CI: 1.49-1.97), obese (OR = 11.17, 95% CI: 9.02-13.62), and uneducated (OR = 1.80, 95% CI: 1.49-2.17), and living in urban areas (OR = 1.96, 95% CI: 1.64-2.35) are stronger predictors of MetS in this population. Conclusion: There was no significant difference in the prevalence of MetS between patients with and without COPD. Spirometry parameters and respiratory problems were significant in subjects with and without MetS.

The Precision Interventions for Severe and/or Exacerbation-Prone (PrecISE) Asthma Network: An overview of Network organization, procedures, and interventions

Asthma is a heterogeneous disease, with multiple underlying inflammatory pathways and structural airway abnormalities that impact disease persistence and severity. Recent progress has been made in developing targeted asthma therapeutics, especially for subjects with eosinophilic asthma. However, there is an unmet need for new approaches to treat patients with severe and exacerbation-prone asthma, who contribute disproportionately to disease burden. Extensive deep phenotyping has revealed the heterogeneous nature of severe asthma and identified distinct disease subtypes. A current challenge in the field is to translate new and emerging knowledge about different pathobiologic mechanisms in asthma into patient-specific therapies, with the ultimate goal of modifying the natural history of disease. Here, we describe the Precision Interventions for Severe and/or Exacerbation-Prone Asthma (PrecISE) Network, a groundbreaking collaborative effort of asthma researchers and biostatisticians from around the United States. The PrecISE Network was designed to conduct phase II/proof-of-concept clinical trials of precision interventions in the population with severe asthma, and is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Using an innovative adaptive platform trial design, the PrecISE Network will evaluate up to 6 interventions simultaneously in biomarker-defined subgroups of subjects. We review the development and organizational structure of the PrecISE Network, and choice of interventions being studied. We hope that the PrecISE Network will enhance our understanding of asthma subtypes and accelerate the development of therapeutics for severe asthma.

A new perspective on cholesterol in pediatric health: association of vitamin D metabolism, respiratory diseases, and mental health problems

Cholesterol, the main structural molecule of cell membranes, is involved in essential functions of the human body. Dyslipidemia is an established risk factor for cardiovascular diseases (CVDs) that is observed even in childhood. To reduce the risk of CVDs in children, several clinical guidelines have been published for the management of pediatric dyslipidemia. However, pediatric dyslipidemia is also associated with several health problems other than CVDs. This article reviews the current data on dyslipidemia-related pediatric health issues. There is strong evidence that low serum vitamin D levels, asthma, and mental health problems may be associated with dyslipidemia in the pediatric population regardless of body mass index. This review also highlights the need for further large-scale population-based studies in the Korean pediatric population to establish effective strategies for promoting children's health.

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.

An Overview of the Obese-Asthma Phenotype in Children

Asthma is the most common chronic disease in childhood. Overweight and obesity are included among the comorbidities considered in patients with difficult-to-treat asthma, suggesting a specific phenotype of the disease. Therefore, the constant increase in obesity prevalence in children and adolescents raises concerns about the parallel increase of obesity-associated asthma. The possible correlation between obesity and asthma has been investigated over the last decade by different authors, who suggest a complex multifactorial relationship. Although the particular non-eosinophilic endotype of obesity-related asthma supports the concept that high body weight precedes asthma development, there is ongoing debate about the direct causality of these two entities. A number of mechanisms may be involved in asthma in combination with obesity disease in children, including reduced physical activity, abnormal ventilation, chronic systemic inflammation, hormonal influences, genetics and additional comorbidities, such as gastroesophageal reflux and dysfunctional breathing. The identification of the obesity-related asthma phenotype is crucial to initiate specific therapeutic management. Besides the cornerstones of asthma treatment, lifestyle should be optimized, with interventions aiming to promote physical exercise, healthy diet, and comorbidities. Future studies should clarify the exact association between asthma and obesity and the mechanisms underlying the pathogenesis of these two related conditions with the aim to define personalized therapeutic strategies for asthma management in this population.

Asthma and obesity: endotoxin another insult to add to injury?

Low-grade inflammation is often an underlying cause of several chronic diseases such as asthma, obesity, cardiovascular disease, and type 2 diabetes mellitus (T2DM). Defining the mediators of such chronic low-grade inflammation often appears dependent on which disease is being investigated. However, downstream systemic inflammatory cytokine responses in these diseases often overlap, noting there is no doubt more than one factor at play to heighten the inflammatory response. Furthermore, it is increasingly believed that diet and an altered gut microbiota may play an important role in the pathology of such diverse diseases. More specifically, the inflammatory mediator endotoxin, which is a complex lipopolysaccharide (LPS) derived from the outer membrane cell wall of Gram-negative bacteria and is abundant within the gut microbiota, and may play a direct role alongside inhaled allergens in eliciting an inflammatory response in asthma. Endotoxin has immunogenic effects and is sufficiently microscopic to traverse the gut mucosa and enter the systemic circulation to act as a mediator of chronic low-grade inflammation in disease. Whilst the role of endotoxin has been considered in conditions of obesity, cardiovascular disease and T2DM, endotoxin as an inflammatory trigger in asthma is less well understood. This review has sought to examine the current evidence for the role of endotoxin in asthma, and whether the gut microbiota could be a dietary target to improve disease management. This may expand our understanding of endotoxin as a mediator of further low-grade inflammatory diseases, and how endotoxin may represent yet another insult to add to injury.

Dynamic Metabolic Risk Profiling of World Trade Center Lung Disease: A Longitudinal Cohort Study

Rationale: Metabolic syndrome (MetSyn) increases the risk of World Trade Center (WTC) lung injury (LI). However, the temporal relationship of MetSyn, exposure intensity, and lung dysfunction is not well understood. Objective: To model the association of longitudinal MetSyn characteristics with WTC lung disease to define modifiable risk. Methods: Firefighters, for whom consent was obtained (N = 5,738), were active duty on September 11, 2001 (9/11). WTC-LI (n = 1,475; FEV₁% predicted <lower limit of normal [LLN]) and non-WTC-LI (n = 4,263; FEV₁% predicted ⩾LLN at all exams) was the primary outcome, and FVC% predicted <LLN and FEV₁/FVC <0.70 were secondary outcomes. We assessed 1) the effect of concurrent MetSyn on longitudinal lung function by linear mixed models, 2) the temporal effect of MetSyn and exposure by Weibull proportional hazards, 3) the effects of MetSyn's rate of change by two-stage models, and 4) the nonlinear joint effect of longitudinal MetSyn components by a partially linear single-index model (PLSI). Measurements and Main Results: WTC-LI cases were more often ever-smokers, arrived in the morning (9/11), and had MetSyn. Body mass index ⩾30 kg/m² and high-density lipoprotein <40 mg/dl were most contributory to concurrent loss of FEV₁% predicted and FVC% predicted while conserving FEV₁/FVC. Body mass index ⩾30 kg/m² and dyslipidemia significantly predicted WTC-LI, FVC% predicted <LLN in a Weibull proportional hazards model. Dynamic risk assessment of WTC-LI on the basis of MetSyn and exposure showed how reduction of MetSyn factors further reduces WTC-LI likelihood in susceptible populations. PLSI demonstrates that MetSyn has a nonlinear relationship with WTC lung disease, and increases in cumulative MetSyn risk factors exponentially increase WTC-LI risk. An interactive metabolic-risk modeling application was developed to simplify PLSI interpretation. Conclusions: MetSyn and WTC exposure contribute to the development of lung disease. Dynamic risk assessment may be used to encourage treatment of MetSyn in susceptible populations. Future studies will focus on dietary intervention as a disease modifier.

Pediatric Obesity-Related Asthma: The Role of Nutrition and Nutrients in Prevention and Treatment

Childhood obesity rates have dramatically risen in numerous countries worldwide. Obesity is likely a factor in increased asthma risk, which is already one of the most widespread chronic respiratory pathologies. The pathogenic mechanism of asthma risk has still not yet been fully elucidated. Moreover, the role of obesity-related inflammation and pulmonary overreaction to environmental triggers, which ultimately result in asthma-like symptoms, and the importance of dietary characteristics is well recognized. Diet is an important adjustable element in the asthma development. Food-specific composition of the diet, in particular fat, sugar, and low-quality nutrients, is likely to promote the chronic inflammatory state seen in asthmatic patients with obesity. An unbalanced diet or supplementation as a way to control asthma more efficiently has been described. A personalized dietary intervention may improve respiratory symptoms and signs and therapeutic response. In this narrative review, we presented and discussed more recent literature on asthma associated with obesity among children, focusing on the risk of asthma among children with obesity, asthma as a result of obesity focusing on the role of adipose tissue as a mediator of systemic and local airway inflammation implicated in asthma regulation, and the impact of nutrition and nutrients in the development and treatment of asthma. Appropriate early nutritional intervention could possibly be critical in preventing and managing asthma associated with obesity among children.

Metabolomics in asthma: A platform for discovery

Asthma, characterized by airway hyperresponsiveness, inflammation and remodeling, is a chronic airway disease with complex etiology. Severe asthma is characterized by frequent exacerbations and poor therapeutic response to conventional asthma therapy. A clear understanding of cellular and molecular mechanisms of asthma is critical for the discovery of novel targets for optimal therapeutic control of asthma. Metabolomics is emerging as a powerful tool to elucidate novel disease mechanisms in a variety of diseases. In this review, we summarize the current status of knowledge in asthma metabolomics at systemic and cellular levels. The findings demonstrate that various metabolic pathways, related to energy metabolism, macromolecular biosynthesis and redox signaling, are differentially modulated in asthma. Airway smooth muscle cell plays pivotal roles in asthma by contributing to airway hyperreactivity, inflammatory mediator release and remodeling. We posit that metabolomic profiling of airway structural cells, including airway smooth muscle cells, will shed light on molecular mechanisms of asthma and airway hyperresponsiveness and help identify novel therapeutic targets.

Pioglitazone prevents obesity-related airway hyperreactivity and neuronal M2 receptor dysfunction

Obesity-related asthma often presents with more severe symptoms than non-obesity-related asthma and responds poorly to current treatments. Both insulin resistance and hyperinsulinemia are common in obesity. We have shown that increased insulin mediates airway hyperreactivity in diet-induced obese rats by causing neuronal M2 muscarinic receptor dysfunction, which normally inhibits acetylcholine release from parasympathetic nerves. Decreasing insulin with streptozotocin prevented airway hyperreactivity and M2 receptor dysfunction. The objective of the present study was to investigate whether pioglitazone, a hypoglycemic drug, prevents airway hyperreactivity and M2 receptor dysfunction in obese rats. Male rats fed a low- or high-fat diet were treated with pioglitazone or PBS by daily gavage. Body weight, body fat, fasting insulin, and bronchoconstriction and bradycardia in response to electrical stimulation of vagus nerves and to aerosolized methacholine were recorded. Pilocarpine, a muscarinic receptor agonist, was used to measure M2 receptor function. Rats on a high-fat diet had potentiated airway responsiveness to vagal stimulation and dysfunctional neuronal M2 receptors, whereas airway responsiveness to methacholine was unaffected. Pioglitazone reduced fasting insulin and prevented airway hyperresponsiveness and M2 receptor dysfunction but did not change inflammatory cytokine mRNA expression in alveolar macrophages. High-fat diet, with and without pioglitazone, had tissue-specific effects on insulin receptor mRNA expression. In conclusion, pioglitazone prevents vagally mediated airway hyperreactivity and protects neuronal M2 muscarinic receptor function in obese rats.

Cardio-metabolic risk factors during childhood in relation to lung function and asthma

BACKGROUND

Cardio-metabolic risk factors might have an adverse effect on respiratory outcomes, but associations in children are unknown. We aimed to study the longitudinal associations of cardio-metabolic risk factors with lung function and asthma at school age. We also examined whether any association was explained by child's body mass index (BMI).

METHODS

In a population-based cohort study among 4988 children, cardio-metabolic risk factors were measured at 6 and 10 years and included blood pressure, cholesterol, triglycerides, insulin, and C-reactive protein (CRP) concentrations. At age 10 years, lung function was measured by spirometry and current physician-diagnosed asthma was assessed by questionnaire.

RESULTS

After adjustment for confounders, child's BMI, and multiple testing, we observed that a higher diastolic blood pressure at the age of 6 years was associated with a higher forced vital capacity (FVC) at the age of 10 years (Z-score difference (95% CI): 0.05 (0.01, 0.08), per SDS increase in diastolic blood pressure). Also, child's CRP concentrations above the 75th percentile at both ages 6 and 10 years were related to a lower FVC as compared to CRP concentrations below the 75th percentile at both ages (Z-score difference (95% CI) -0.21 (-0.36, -0.06)). No consistent associations of other cardio-metabolic risk factors with respiratory outcomes were observed.

CONCLUSION

Blood pressure and CRP, but not lipids and insulin, were associated with lower lung function but not with asthma. The underlying mechanisms and long-term effects of these associations require further investigation.

Indoor bacterial, fungal and viral species and functional genes in urban and rural schools in Shanxi Province, China-association with asthma, rhinitis and rhinoconjunctivitis in high school students

BACKGROUND

Studies in developed countries have reported that the prevalence of asthma and rhinitis is higher in urban areas than in rural areas, and this phenomenon is associated with urbanization and changing indoor microbiome exposure. Developing countries such as China have experienced rapid urbanization in past years, but no study has investigated microbiome exposure and urban-rural health effects in these countries.

METHODS

Nine high schools from urban and rural areas were randomly selected in Shanxi Province, China, and classroom vacuum dust was collected for shotgun metagenomic sequencing. A self-administered questionnaire was collected from 1332 students for personal information and health data. Three-level logistic regression was performed between microbial richness/abundance/functional pathways and the occurrence of asthma and rhinitis symptoms.

RESULTS

Consistent with developed countries, the prevalence of wheeze and rhinitis was higher in urban areas than in rural areas (p < 0.05). Metagenomic profiling revealed 8302 bacterial, 395 archaeal, 744 fungal, 524 protist and 1103 viral species in classroom dust. Actinobacteria (mean relative abundance 49.7%), Gammaproteobacteria (18.4%) and Alphaproteobacteria (10.0%) were the most abundant bacterial classes. The overall microbiome composition was significantly different between urban and rural schools (p = 0.001, Adonis). Species from Betaproteobactera, Gammaproteobacteria and Bacilli were enriched in urban schools, and species from Actinobacteria and Cyanobacteria were enriched in rural schools. Potential pathogens were present in higher abundance in urban schools than in rural schools (p < 0.05). Pseudoalteromonas, Neospora caninum and Microbacterium foliorum were positively associated with the occurrence of wheeze, rhinitis and rhinoconjunctivitis, and Brachybacterium was protectively (negatively) associated with rhinitis (p < 0.01). The abundance of human endocrine and metabolic disease pathways was positively associated with rhinitis (p = 0.008), and butyrate and propionate metabolic genes and pathways were significantly enriched in rural schools (p < 0.005), in line with previous findings that these short-chain fatty acids protect against inflammatory diseases in the human gut.

CONCLUSIONS

We conducted the first indoor microbiome survey in urban/rural environments with shotgun metagenomics, and the results revealed high-resolution microbial taxonomic and functional profiling and potential health effects. Video abstract.

Association of Metabolic Syndrome and Asthma Status; A Prospective Study from Guilan Province-Iran

INTRODUCTION

Asthma is defined as a chronic inflammatory airway disease. Recent studies have shown the association between metabolic syndrome and deterioration of the lung functions in patients with asthma. The aim of this study was to evaluate the relation between metabolic syndrome and asthma status.

METHODS

In this prospective cross-sectional study, 160 asthmatic patients attending Razi hospital in Guilan province, were divided equally into two groups of 80 patients. The case group was contained asthmatic patient with metabolic syndrome and the control group contain asthmatic patient without metabolic syndrome. Blood pressure, height, weight, waist circumferences, fasting blood glucose and lipid profiles were measured by standard methods. Asthma severity was determined based on clinical symptoms and GINA criteria. To evaluate pulmonary function parameters, spirometry was performed for the patients.

RESULTS

Pulmonary function test including FEF, FVC and FEV1 were significantly lower in the case group compared to control group (P < 0.05). Also, a significant negative correlation was found between waist circumference, cardiovascular risk factors (including diabetes, hypertriglyceridemia, hypertension) with spirometric indices (P < 0.05).

CONCLUSION

Metabolic syndrome causes major declines of pulmonary parameters in asthma patients, thus controlling metabolic syndrome might improve symptoms of asthma.

Oxidative stress and obesity-related asthma

Obesity is an asthma comorbidity associated with poor control, increased exacerbation risk and reduced response to inhaled and systemic corticosteroids. It affects children and adults differentially. In those with early onset asthma, it associated with increased eosinophilic inflammation, whereas in late onset, it correlates with lower nitric oxide (NO) and predominantly non-T2 inflammation. There are probably multiple pathways by which obesity impacts asthma; airway and systemic oxidative stress has been proposed as a mechanism that could potentially explain the obesity mediated increased comorbidity and poor response to treatment. More likely than not, oxidative stress is an epiphenomenon of a very diverse set of processes driven by complex changes in airway and systemic metabolism. This article provides a comprehensive overview of the clinical, metabolic, pathophysiological and therapeutic aspects of oxidative stress in patients with obesity and asthma.

Insulin acutely increases agonist-induced airway smooth muscle contraction in humans and rats

Obesity increases incidence and severity of asthma but the molecular mechanisms are not completely understood. Hyperinsulinemia potentiates vagally induced bronchoconstriction in obese rats. Since bronchoconstriction results from airway smooth muscle contraction, we tested whether insulin changed agonist-induced airway smooth muscle contraction. Obesity-prone and resistant rats were fed a low-fat diet for 5 wk and treated with insulin (Lantus, 3 units/rat sc) 16 h before vagally induced bronchoconstriction was measured. Ex vivo, contractile responses to methacholine were measured in isolated rat tracheal rings and human airway smooth muscle strips before and after incubation (0.5-2 h) with 100 nM insulin or 13.1 nM insulin like growth factor-1 (IGF-1). M₂ and M₃ muscarinic receptor mRNA expression was quantified by qRT-PCR and changes in intracellular calcium were measured in response to methacholine or serotonin in isolated rat tracheal smooth muscle cells treated with 1 µM insulin. Insulin, administered to animals 16 h prior, potentiated vagally induced bronchoconstriction in both obese-prone and resistant rats. Insulin, not IGF-1, significantly increased methacholine-induced contraction of rat and human isolated airway smooth muscle. In cultured rat tracheal smooth muscle cells, insulin significantly increased M₂, not M_3, mRNA expression and enhanced methacholine- and serotonin-induced increase in intracellular calcium. Insulin alone did not cause an immediate increase in intracellular calcium. Thus, insulin acutely potentiated agonist-induced increase in intracellular calcium and airway smooth muscle contraction. These findings may explain why obese individuals with hyperinsulinemia are prone to airway hyperreactivity and give insights into future targets for asthma treatment.

Association between Asthma and Type 2 Diabetes Mellitus: Mechanisms and Impact on Asthma Control-A Literature Review

The study aimed to analyze the scientific production on the association between asthma and type 2 diabetes mellitus (T2DM) in adults, the mechanisms that explain this association, and its impact on asthma control. A literature review of scientific articles indexed in the MEDLINE/PUBMED, BVS, CINAHL, Cochrane Library, and Web of Science databases was carried out, considering publications from January 2009 to December 2019, using the following descriptors: "asthma", "type 2 diabetes", "adult," and "association". Of 962 articles found, 18 were included because they met the eligibility criteria. It is suggested that the association between asthma and T2DM is caused by low-grade systemic inflammation (7 articles) or the use of corticosteroids (7 articles). It is noticed that there is a limited scientific production regarding the consequences of this association for the control of asthma (5 articles). It is concluded that asthma and T2DM are two common chronic conditions of increasing prevalence and that often coexist in the same patient. It is suggested that this coexistence worsens asthma control. Therefore, the study may support public policies and clinical health practices that value the approach of comorbidities associated with asthma such as T2DM, in order to minimize additional health risks and reduce the quality of life.

Asthma and Obesity: Two Diseases on the Rise and Bridged by Inflammation

Asthma and obesity are two epidemics affecting the developed world. The relationship between obesity and both asthma and severe asthma appears to be weight-dependent, causal, partly genetic, and probably bidirectional. There are two distinct phenotypes: 1. Allergic asthma in children with obesity, which worsens a pre-existing asthma, and 2. An often non allergic, late-onset asthma developing as a consequence of obesity. In obesity, infiltration of adipose tissue by macrophages M1, together with an increased expression of multiple mediators that amplify and propagate inflammation, is considered as the culprit of obesity-related inflammation. Adipose tissue is an important source of adipokines, such as pro-inflammatory leptin, produced in excess in obesity, and adiponectin with anti-inflammatory effects with reduced synthesis. The inflammatory process also involves the synthesis of pro-inflammatory cytokines such as IL-1β, IL-6, TNFα, and TGFβ, which also contribute to asthma pathogenesis. In contrast, asthma pro-inflammatory cytokines such as IL-4, IL-5, IL-13, and IL-33 contribute to maintain the lean state. The resulting regulatory effects of the immunomodulatory pathways underlying both diseases have been hypothesized to be one of the mechanisms by which obesity increases asthma risk and severity. Reduction of weight by diet, exercise, or bariatric surgery reduces inflammatory activity and improves asthma and lung function.

High-Density Lipoprotein (HDL) in Allergy and Skin Diseases: Focus on Immunomodulating Functions

From an evolutionary perspective, lipoproteins are not only lipid transporters, but they also have important functions in many aspects of immunity. High-density lipoprotein (HDL) particles are the most abundant lipoproteins and the most heterogeneous in terms of their composition, structure, and biological functions. Despite strong evidence that HDL potently influences the activity of several immune cells, the role of HDL in allergies and skin diseases is poorly understood. Alterations in HDL-cholesterol levels have been observed in allergic asthma, allergic rhinitis, atopic dermatitis (eczema), psoriasis, urticaria, and angioedema. HDL-associated apolipoprotein (apo) A-I, apoA-IV, and apoC-III, and lyso-phosphatidylcholines potently suppress immune cell effector responses. Interestingly, recent studies provided evidence that allergies and skin diseases significantly affect HDL composition, metabolism, and function, which, in turn, could have a significant impact on disease progression, but may also affect the risk of cardiovascular disease and infections. Interestingly, not only a loss in function, but also, sometimes, a gain in function of certain HDL properties is observed. The objective of this review article is to summarize the newly identified changes in the metabolism, composition, and function of HDL in allergies and skin diseases. We aim to highlight the possible pathophysiological consequences with a focus on HDL-mediated immunomodulatory activities.

Obesity-associated asthma in childhood

Obesity and bronchial asthma are very common diseases in children and adolescents, associated with a considerable burden of disease, reduced quality of life and comorbidities. Obesity is a significant risk factor for bronchial asthma. On the one hand, obesity leads to changes in the mechanics and function of the lungs and chest. On the other hand, obesity-associated inflammatory processes with increased production of leptin and cytokines may trigger bronchial inflammation with the appearance of asthmatic symptoms. The diseases are also linked by genetic factors. Physical activity and weight reduction have a significant benefit. Pharmacotherapy must be based on the pattern of inflammation. This article summarizes the current state of the literature on the association of asthma and obesity and presents current and possible future treatment options.

Metabolic Dysfunction and Asthma: Current Perspectives

The increasing knowledge of the mechanisms involved in metabolism is shifting the paradigms by which the pathophysiology of many pulmonary diseases is understood. Metabolic dysfunction is recognized in obesity-associated asthma, but other metabolic conditions have been shown to be independently related to asthma. Novel insights have also recently been brought by metabolomics in this filed. The purpose of this review is to discuss current perspectives regarding metabolic dysfunction in asthma, from obesity-related asthma to other metabolic conditions and the role of current pharmacological therapeutic strategies and lifestyle interventions. Obesity is a well-recognized risk factor for asthma across the lifespan, which is generally associated with poorer response to current available treatments, rendering a more severe, refractory disease status. Besides the epidemiological and clinical link, untargeted metabolomics studies have recently supported the obesity-associated asthma phenotype at the molecular level. Not only obesity-related, but also other aspects of metabolic dysregulation can be independently linked to asthma. These include hyperinsulinemia, dyslipidemia and hypertension, which need to be taken into account, even in the non-obese patient. Untargeted metabolomics studies have further highlighted several other metabolic pathways that can be altered in asthma, namely regarding oxidative stress and systemic inflammation, and also suggesting the importance of microbiota in asthma pathogenesis. Considering the reduced response to corticosteroids, other pharmacologic treatments have been shown to be effective regardless of body mass index. Non-pharmacologic treatments (namely weight reduction and dietary changes) may bring substantial benefit to the asthmatic patient. Taken together, this evidence points towards the need to improve our knowledge in this filed and, in particular, to address the influence of environmental factors in metabolic dysfunction and asthma development. Personalized medicine is definitely needed to optimize treatment, including a holistic view of the asthmatic patient in order to set accurate pharmacologic therapy together with dietary, physical exercise and lifestyle interventions.

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.

Glycated Hemoglobin A1c, Lung Function, and Hospitalizations Among Adults with Asthma

BACKGROUND

Insulin resistance and metabolic dysfunction have been associated with asthma risk and asthma severity.

OBJECTIVE

To examine the association between glycated hemoglobin A_1c (HbA_1c), asthma-related hospitalizations, and lung function measures among adults in the United Kingdom.

METHODS

A cross-sectional study was conducted of 47,606 adults aged 40 to 69 years who participated in the UK Biobank and had asthma but no diagnosis of diabetes mellitus. HbA_1c level was analyzed as a continuous measure and also categorized as normal (<42 mmol/mol) or as consistent with prediabetes/diabetes (≥42 mmol/mol). An asthma-related hospitalization was defined as ever having had a hospitalization with an International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification code of a main diagnosis compatible with asthma (International Classification of Diseases, Ninth Revision, Clinical Modification code 493.x or International Classification of Diseases, Tenth Revision, Clinical Modification codes J45.x and J46.x). Logistic or linear regression was used for the multivariable analysis of asthma hospitalizations and lung function measures (FEV₁, forced vital capacity [FVC], and FEV₁/FVC). All models were adjusted for age, sex, ethnic background, body mass index, average annual household income, current smoking status, pack-years of smoking, fasting time, and C-reactive protein level.

RESULTS

Both HbA_1c level (odds ratio, 1.03; 95% CI, 1.01-1.04) and an HbA_1c level in the prediabetes/diabetes range (odds ratio, 1.68; 95% CI, 1.18-2.41) were associated with 1 or more asthma hospitalizations. Moreover, both HbA_1c level and an HbA_1c level in the prediabetes/diabetes range were significantly and inversely associated with FEV₁ and FVC.

CONCLUSIONS

HbA_1c is linked to asthma-related hospitalizations and small decrements in FEV₁ and FVC among British adults with asthma but no diagnosis of diabetes mellitus.

Maternal asthma and gestational diabetes mellitus: Exploration of potential associations

Asthma and gestational diabetes mellitus are prevalent during pregnancy and associated with adverse perinatal outcomes. The risk of gestational diabetes mellitus is increased with asthma, and more severe asthma; yet, the underlying mechanisms are unknown. This review examines existing literature to explore possible links.  Asthma and gestational diabetes mellitus are associated with obesity, excess gestational weight gain, altered adipokine levels and low vitamin D levels; yet, it's unclear if these underpin the gestational diabetes mellitus-asthma association. Active antenatal asthma management reportedly mitigates asthma-associated gestational diabetes mellitus risk. However, mechanistic studies are lacking.  Existing research suggests asthma management during pregnancy influences gestational diabetes mellitus risk; this may have important implications for future antenatal strategies to improve maternal-fetal outcomes by addressing both conditions. Addressing shared risk factors, as part of antenatal care, may also improve outcomes. Finally, mechanistic studies, to establish the underlying pathophysiology linking asthma and gestational diabetes mellitus, could uncover new treatment approaches to optimise maternal and child health outcomes.

Asthma and metabolic syndrome: a comprehensive systematic review and meta-analysis of observational studies

Introduction: This study aimed to perform a meta-analysis on the prevalence of metabolic syndrome (MetS) among patients with asthma and to measure the association asthma has with MetS.

Methods: The Web of Science, Medline, Scopus, Embase and Google Scholar were searched using the "Asthma", "Metabolic Syndrome", "Dysmetabolic Syndrome", "Cardiovascular Syndrome", "Insulin Resistance Syndrome", "Prevalence", "Odds Ratio", "Cross-Sectional Studies", and "Case-Control Studies" keywords. All observational studies reporting the prevalence of MetS among people with and without asthma were included in the study. In the presence of heterogeneity, random-effects models were used to pool the prevalence and odds ratios (OR), as measures of association in cross-sectional and case-control/ cohort studies, respectively.

Results: The prevalence of MetS among patients with asthma (8 studies) and the OR comparing the prevalence of MetS among patients with and without asthma (5 studies) were pooled separately. The pooled prevalence of MetS among patients with asthma was found to be 25% (95% confidence interval (CI): 13%–38%). In contrast, the overall pooled OR for MetS in patients with asthma, compared to healthy controls, was 1.34 (95% CI: 0.91–1.76), which was not statistically significant.

Conclusion: The prevalence of MetS was relatively high in patients with asthma. Furthermore, the odds of MetS was higher in patients with asthma, compared to healthy controls, although this difference was not statistically significant. More original studies among different populations are needed in order to more accurately examine the association between asthma and MetS, as well as the relationship asthma has with the individual components of MetS.

Lifetime overweight and adult asthma: 1978/1979 Ribeirão Preto Birth Cohort, São Paulo, Brazil

Studies focusing on obesity and asthma frequently consider the weight at a given time; thus, modeling pathways through lifetime overweight may contribute to elucidate temporal aspects in this relationship. This study modeled the pathways in the association of lifetime overweight with asthma in adult life, using data from the 1978/1979 Birth Cohort, Ribeirão Preto, São Paulo, Brazil (n = 2,063) at birth (baseline), school age (9/11 years) and adult age (23/25 years). A theoretical model was proposed to explore the effects of lifetime overweight on asthma in adult life analyzed by structural equation modeling. Parental obesity (SC - standardized coefficenttotal = 0.211, p < 0.001; SCdirect = 0.115, p = 0.007) and overweight at school age (SCtotal = 0.565, p < 0.0001; SCdirect = 0.565, p < 0.0001) were associated with overweight in adult life. Parental obesity (SCdirect = 0.105, p = 0.047) and nutritional status at birth (SCtotal = -0.124, p = 0.009; SCdirect = -0.131, p = 0.007) were associated with asthma in adult life. A higher "current adult socieconomic situation" was inversely associated to overweight (SCdirect = -0.171, p = 0.020) and to asthma in adult life (SCtotal = -0.179, p = 0.041; SCdirect = -0.182, p = 0.039). Parental obesity showed a transgenerational effect in weight, triggering to childhood and adulthood overweight. Parallel to underweight at birth, parental obesity was also a risk to asthma in adult life. While, the socioeconomic status in adult life protected from both, overweight and asthma.

Pediatric obesity-related asthma: A prototype of pediatric severe non-T2 asthma

Childhood obesity contributes to many diseases, including asthma. There is literature to suggest that asthma developing as a consequence of obesity has a nonallergic or non-T2 phenotype. In this review, obesity-related asthma is utilized as a prototype of non-T2 asthma in children to discuss several nonallergic mechanisms that underlie childhood asthma. Obesity-related asthma is associated with systemic T helper (Th)1 polarization occurring with monocyte activation. These immune responses are mediated by insulin resistance and dyslipidemia, metabolic abnormalities associated with obesity, that are themselves associated with pulmonary function deficits in obese asthmatics. As in other multifactorial diseases, there is both a genetic and an environmental contribution to pediatric obesity-related asthma. In addition to genetic susceptibility, differential DNA methylation is associated with non-T2 immune responses in pediatric obesity-related asthma. Initial investigations into the biology of non-T2 immune responses have identified the 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, and cytokine production and exocytosis. Although these novel pathways are promising findings to direct targeted therapy development for obesity-related asthma to address the disease burden, there is evidence to suggest that dietary interventions, including diet modification, rather than caloric restriction alone, decrease disease burden. Adoption of a diet rich in micronutrients, including carotenoids and 25-OH cholecalciferol, a vitamin D metabolite, may be beneficial since these are positively correlated with pulmonary function indices, while being protective against metabolic abnormalities associated with the obese asthma phenotype.

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.

Hyperinsulinemia promotes heterologous desensitization of β2 adrenergic receptor in airway smooth muscle in obesity

β-Adrenergic receptor (β-AR) agonists are the most common clinical bronchodilators for asthma. Obesity influences asthma severity and may impair response to β-AR agonists. Previous studies show that in obese mice, hyperinsulinemia plays a crucial role in β-AR desensitization in the heart. We therefore investigated whether insulin promotes β-AR desensitization in airway smooth muscle (ASM) and compromises airway relaxation responsiveness to β-AR agonists. We found that human ASM cells and mouse airway tissues exposed to insulin exhibit impaired β₂ AR-induced cAMP accumulation and airway relaxation. This impaired relaxation is associated with insulin-induced phosphorylation and expression of phosphodiesterase 4D (PDE4D) through transactivation of a G protein-coupled receptor kinase 2 (GRK2)-dependent β₂ AR-G_i -ERK1/2 cascade. Both acute and chronic pharmacological inhibition of PDE4 effectively reversed impaired β₂ AR-mediated ASM relaxation in an obesity mouse model induced by a high fat diet. Collectively, these findings reveal that cross talk between insulin and β₂ AR signaling promotes ASM β₂ AR desensitization in obesity through upregulation of PDE4D phosphorylation and expression. Our results identify a novel pathway of asthma pathogenesis in patients with obesity/metabolic syndrome, in which the GRK2-mediated signaling can be a potential therapeutic modality to prevent or treat β₂ AR desensitization in ASM. Moreover, PDE4 inhibitors may be used as efficacious therapeutic agents for asthma in obese and diabetic subjects.

Effects of maternal-fetal transmission of viruses and other environmental agents on lung development

New information is emerging concerning the influence of environmental factors (e.g., viruses, pollutants, nutrients) on fetal lung development and the prenatal modulation of cellular and molecular effectors essential to the control of airway function, which may shed new light into the pathogenesis of chronic obstructive pulmonary disease in childhood. In particular, recent studies have shown that nanosize biological and inorganic particles (e.g., respiratory viruses and pollutants) are able to spread hematogenously across the placenta from mother to offspring and interfere with lung development during critical "windows of opportunity". Furthermore, the nutritional balance of maternal diet during pregnancy can affect postnatal lung structure and function. Adverse prenatal environmental conditions can predispose to increased airway reactivity by inducing aberrant cholinergic innervation of the respiratory tract, enhanced contractility of the airway smooth muscle, and impaired innate immunity. Such changes can persist long after birth and might provide a plausible explanation to the development of chronic airway dysfunction in children, even in the absence of atopic predisposition. Insight into maternal-fetal interactions will contribute to a better understanding of the pathogenesis of highly prevalent diseases like bronchiolitis and asthma, and may lead to more precise preventative and therapeutic strategies, or new indications for existing ones.

Bioenergetic Differences in the Airway Epithelium of Lean Versus Obese Asthmatics Are Driven by Nitric Oxide and Reflected in Circulating Platelets

Aims: Asthma, characterized by airway obstruction and hyper-responsiveness, is more severe and less responsive to treatment in obese subjects. While alterations in mitochondrial function and redox signaling have been implicated in asthma pathogenesis, it is unclear whether these mechanisms differ in lean versus obese asthmatics. In addition, we previously demonstrated that circulating platelets from asthmatic individuals have altered bioenergetics; however, it is unknown whether platelet mitochondrial changes reflect those observed in airway epithelial cells. Herein we hypothesized that lean and obese asthmatics show differential bioenergetics and redox signaling in airway cells and that these alterations could be measured in platelets from the same individual. Results: Using freshly isolated bronchial airway epithelial cells and platelets from lean and obese asthmatics and healthy individuals, we show that both cell types from obese asthmatics have significantly increased glycolysis, basal and maximal respiration, and oxidative stress compared with lean asthmatics and healthy controls. This increased respiration was associated with enhanced arginine metabolism by arginase, which has previously been shown to drive respiration. Inducible nitric oxide synthase (iNOS) was also upregulated in cells from all asthmatics. However, due to nitric oxide synthase uncoupling in obese asthmatics, overall nitric oxide (NO) bioavailability was decreased, preventing NO-dependent inhibition in obese asthmatic cells that was observed in lean asthmatics. Innovation and Conclusion: These data demonstrate bioenergetic differences between lean and obese asthmatics that are, in part, due to differences in NO signaling. They also suggest that the platelet may serve as a useful surrogate to understand redox, oxidative stress and bioenergetic changes in the asthmatic airway.

The Metabolic Requirements of Th2 Cell Differentiation

Upon activation, naïve CD4⁺ T cells differentiate into a number of specialized T helper (Th) cell subsets. Th2 cells are central players in immunity to helminths and are implicated in mediating the inflammatory pathology associated with allergies. The differentiation of Th2 cells is dependent on transcription factors such as GATA3 and STAT6, which prime Th2 cells for the secretion of interleukin- (IL-) 4, IL-5, and IL-13. Several lines of work now suggest that differentiating Th2 cells in the lymph node are potent IL-4 cytokine producers, but do not become competent IL-5- and IL-13-producing cells until after receiving cues from non-lymphoid tissue. It is evident that Th2 cells that enter tissues undergo considerable changes in chromatin architecture and gene expression, and that over this time, the metabolic requirements of these cells change considerably. Herein, we discuss the metabolic requirements of Th2 cells during their early and late differentiation, focusing on the impact of glucose and lipid metabolism, mTOR activation, the nuclear receptor PPAR-γ and several metabolites.

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.