Impaired glucose metabolism and bronchial hyperresponsiveness in obese prepubertal asthmatic children

Non-T2 asthma

PURPOSE OF REVIEW

This review provides a comprehensive overview of the non-T asthma phenotypes. Asthma is an umbrella term that defines a complex group of heterogenous airway disorders, which are broadly categorized into predominantly T2 or non-T2 phenotypes depending on the presence and levels of airway and systemic biomarkers associated with a T2 inflammatory response. Individuals with predominant T2 asthma have greater numbers of peripheral blood eosinophils, exhaled nitric oxide and IgE. These patients have more atopy and earlier onset asthma. In contrast, the absence or low levels of these biomarkers define non-T2 asthma. This is a heterogenous group with a later onset of asthma that is also more commonly associated with obesity and with females.

RECENT FINDINGS

This article summarizes new information regarding the plasticity that exists between T2 and non-T2 mechanisms, including their role in exacerbation-prone and nonexacerbating asthma, and many of the risk factors associated with the non-T2 phenotype, such as viral infections, ambient air pollution exposure, smoking, genetic and metabolic factors. It also provides new information on the immunological and metabolic mechanisms associated with non-T2 asthma. We also discuss how to manage this asthma phenotype and how treatment responses differ for these patients.

SUMMARY

Non-T2 asthma defines a heterogenous group of asthma phenotypes. However, acknowledging that the absence of T2 biomarkers is influenced by several factors is important and can longitudinally change in relation to exacerbations, particularly in children.

Diabetes-inducing effects of bronchial asthma

BACKGROUND

The relationship between diabetes mellitus (DM) and asthma is complex and can impact disease trajectories.

AIM

To explore the bidirectional influences between the two conditions on clinical outcomes and disease control.

METHODS

We systematically reviewed the literature on the relationship between DM and asthma, focusing on their impacts, mechanisms, and therapeutic implications. Various studies were assessed, which investigated the effect of glycemic control on asthma outcomes, lung function, and exacerbations. The study highlighted the role of specific diabetes medications in managing asthma.

RESULTS

The results showed that poor glycemic control in diabetes can exacerbate asthma, increase hospitalizations, and reduce lung function. Conversely, severe asthma, especially in obese individuals, can complicate diabetes management and make glycemic control more difficult. The diabetes-associated mechanisms, such as inflammation, microangiopathy, and oxidative stress, can exacerbate asthma and decrease lung function. Some diabetes medications exhibit anti-inflammatory effects that show promise in mitigating asthma exacerbations.

CONCLUSION

The complex interrelationship between diabetes and asthma suggests bidirectional influences that affect disease course and outcomes. Inflammation and microvascular complications associated with diabetes may worsen asthma outcomes, while asthma severity, especially in obese individuals, complicates diabetes control. However, the current research has limitations, and more diverse longitudinal studies are required to establish causal relationships and identify effective treatment strategies for individuals with both conditions.

A clinician's guide to effects of obesity on childhood asthma and into adulthood

INTRODUCTION

Obesity, one of the most common chronic conditions affecting the human race globally, affects several organ systems, including the respiratory system, where it contributes to onset and high burden of asthma. Childhood onset of obesity-related asthma is associated with high persistent morbidity into adulthood.

AREAS COVERED

In this review, we discuss the disease burden in children and adults to highlight the overlap between symptoms and pulmonary function deficits associated with obesity-related asthma in both age ranges, and then discuss the potential role of three distinct mechanisms, that of mechanical fat load, immune perturbations, and of metabolic perturbations on the disease burden. We also discuss interventions, including medical interventions for weight loss such as diet modification, that of antibiotics and anti-inflammatory therapies, as well as that of surgical intervention on amelioration of burden of obesity-related asthma.

EXPERT OPINION

With increase in obesity-related asthma due to increasing burden of obesity, it is evident that it is a disease entity distinct from asthma among lean individuals. The time is ripe to investigate the underlying mechanisms, focusing on identifying novel therapeutic targets as well as consideration to repurpose medications effective for other obesity-mediated complications, such as insulin resistance, dyslipidemia and systemic inflammation.

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.

Obesity-related asthma and its relationship with microbiota

Obesity and asthma are global public health problems. Obesity-related asthma is a special phenotype of asthma with a complex pathogenesis. Its occurrence and development are related to mechanical compression, inflammatory response, metabolic regulation, gene regulation, and vitamin D deficiency. Different treatment strategies used in the process of weight loss have a beneficial impact on asthma. Alterations in gut and airway microbial community structure and their metabolites may also contribute to obesity-related asthma. The role of the Th17/Treg balance in the gut microbiota regulating the immune responses and host metabolism is important. Therapeutic measures associated with the gut microbiota variety may contribute to improving chronic inflammation associated with obesity by regulating the Th17/Treg balance. An early reduction in microbial diversity can predict the development of asthma and lead to allergy through an imbalance of Th2/Th1 responses. Short-chain fatty acids (SCFAs) regulate the differentiation and activation of regulatory T cells, thereby regulating immune homeostasis in the lung to suppress allergic inflammation and weight gain. Therefore, clarifying the microbial mechanism of obesity-related asthma has important guiding significance for clinical treatment. In this review, we used the following terms: "asthma and obesity" and "obesity-related asthma", combining "phenotype", "airway inflammation" and "lung function", and reviewed the characteristics and pathogenesis of obesity-related asthma, the relationship between the gut and airway microbiota and obesity-related asthma, and the current treatment measures for the disease.

High-fat Western diet alters crystalline silica-induced airway epithelium ion transport but not airway smooth muscle reactivity

OBJECTIVES

Silicosis is an irreversible occupational lung disease resulting from crystalline silica inhalation. Previously, we discovered that Western diet (HFWD)-consumption increases susceptibility to silica-induced pulmonary inflammation and fibrosis. This study investigated the potential of HFWD to alter silica-induced effects on airway epithelial ion transport and smooth muscle reactivity.

METHODS

Six-week-old male F344 rats were fed a HFWD or standard rat chow (STD) and exposed to silica (Min-U-Sil 5®, 15 mg/m3, 6 h/day, 5 days/week, for 39 d) or filtered air. Experimental endpoints were measured at 0, 4, and 8 weeks post-exposure. Transepithelial potential difference (Vt), short-circuit current (ISC) and transepithelial resistance (Rt) were measured in tracheal segments and ion transport inhibitors [amiloride, Na+ channel blocker; NPPB; Cl- channel blocker; ouabain, Na+, K+-pump blocker] identified changes in ion transport pathways. Changes in airway smooth muscle reactivity to methacholine (MCh) were investigated in the isolated perfused trachea preparation.

RESULTS

Silica reduced basal ISC at 4 weeks and HFWD reduced the ISC response to amiloride at 0 week compared to air control. HFWD + silica exposure induced changes in ion transport 0 and 4 weeks after treatment compared to silica or HFWD treatments alone. No effects on airway smooth muscle reactivity to MCh were observed.

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

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

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.

Perioperative respiratory adverse events during ambulatory anesthesia in obese children

Obesity is one of the most common clinical conditions in the pediatric population with an increasing prevalence ranging from 20 to 30% worldwide. It is well known that during ambulatory anesthesia, obese children are more prone to develop perioperative respiratory adverse events (PRAEs) associated with obesity. To avoid or at least minimize these adverse effects, a thorough preoperative assessment should be undertaken as well as consideration of specific anesthetic approaches such as preoxygenation before induction of anesthesia and optimizing drug dosing. The use of short-acting opioid and nonopioid analgesics and the frequent implementation of regional anesthesia should also be included. Noninvasive airway management, protective mechanical ventilation, and complete reversion of neuromuscular blockade and awake extubation also proved to be beneficial in preventing PRAEs. During the postoperative period, continuous monitoring of oxygenation and ventilation is mandatory in obese children. In the current review, we sought to provide recommendations that might help to reduce the severity of perioperative respiratory adverse events in obese children, which could be of particular importance for reducing the rate of unplanned hospitalizations and ultimately improving the overall postoperative recovery.

Dyspnea and Pulmonary Function Among Participants in the Multicenter AIDS Cohort Study Using Protease Inhibitors: A Cross-Sectional Study

People living with HIV (PLWH) have a higher prevalence of respiratory symptoms than people without human immunodeficiency virus (HIV). Antiretroviral therapy has been associated with worsened airflow limitation. This cross-sectional study assessed respiratory health impairment among PLWH and its association with protease inhibitor use using data from Multicenter AIDS Cohort Study visits between April 1, 2017 and March 31, 2018. Participants completed the St. George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnea scale, spirometry, and diffusion capacity measurement. Visit data were compared among PI users, non-PI users, and men without HIV. Binary and ordinal logistic models were used to determine the associations between HIV status, PI use, and covariates with primary outcomes of dichotomized SGRQ and mMRC dyspnea scores. Of PI users, 57/177 (32.2%) self-reported pulmonary disease compared with 132/501 (26.4%) of non-PI users and 105/547 (19.2%) men without HIV. Of PI users, 77/177 (45.3%) had SGRQ scores ≥10, while 171/501 (34.7%) of non-PI users and 162/549 (29.9%) of people living without HIV had SGRQ scores ≥10 (p = .001). Adjusted models found an association between PI use and SGRQ score ≥10 [odds ratio (OR) 1.91 (95% confidence interval [CI] 1.29-2.82), ref: HIV negative and OR 1.50 (95% CI 1.01-2.22) ref: non-PI users]. A similar association was found with mMRC scores and PI use [OR 1.79 (95% CI 1.21-2.64), ref: HIV negative and OR 1.53 (95% CI 1.04-2.25), ref: non-PI users]. PI use is associated with worse respiratory health status, increased dyspnea, and an increased prevalence of self-reported pulmonary disease.

Mediator production and severity of aspirin-induced respiratory reactions: Impact of sampling site and body mass index

BACKGROUND

Patients with aspirin-exacerbated respiratory disease can experience severe reactions during aspirin challenge that are associated with high levels of mast cell mediators. The tissue source and clinical factors contributing to systemic mediator levels are unknown.

OBJECTIVE

To determine the concordance between respiratory tract and systemic inflammatory mediator levels and identify clinical factors associated with these mediators.

METHODS

We performed an oral aspirin challenge in 30 subjects with aspirin-exacerbated respiratory disease. Respiratory symptoms and function, nasal mucosal fluid, blood, and urine were collected at baseline, at the onset of a respiratory reaction and over a 3-hour observation period. Changes in nasal and systemic mediator levels were compared.

RESULTS

Neither tryptase nor leukotriene E₄ levels in nasal fluid correlated with serum tryptase or urinary leukotriene E₄ at baseline or during reactions. We observed no association between the baseline or aspirin-induced change in nasal versus urinary leukotriene E₄ and serum tryptase levels. Body mass index inversely correlated with baseline and aspirin-induced urinary leukotriene E₄, prostaglandin D₂ metabolite, and serum tryptase levels, as well as with aspirin-induced symptoms and respiratory function, but not with nasal mediators.

CONCLUSION

The levels of nasal and systemic aspirin-induced mast cell products are discordant in aspirin-exacerbated respiratory disease. Systemically detected levels are likely derived from mast cells outside of the sinonasal cavity and do not accurately reflect upper respiratory tract production. Increased body mass index decreases systemic mast cell mediator production and reaction severity, supporting a contribution of metabolic regulation in aspirin-induced systemic reactions.

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.

An Elevated METS-IR Index Is Associated With Higher Asthma Morbidity and Earlier Age of First Asthma in US Adults: Results Based on a Cross-Sectional Study

OBJECTIVE

The purpose of this study was to evaluate whether there is a correlation between the METS-IR index and asthma among Americans.

METHODS

In an attempt to establish the relationship between the METS-IR index and asthma prevalence and age at first onset of asthma, we conducted a logistic regression analysis, subgroup analysis, and dose-response curve analysis using the National Health and Nutrition Examination Survey (NHANES) database.

RESULTS

In model 3, each unit increase in METS-IR index led to 1.5% increase in asthma prevalence (OR= 1.015, 95% CI: 1.012, 1.018) and an earlier age of onset of asthma by 0.057years (β= -0.057, 95% CI: -0.112, -0.002).Stratified analysis determined that an increase in METS-IR index was associated with asthma prevalence in almost all subgroups, except in the group where it was not known whether a blood relative had asthma, and a positive linear relationship was found between METS-IR index and asthma prevalence, as well as a linear negative relationship with age at asthma onset.

CONCLUSION

Despite the fact that a direct causal relationship cannot be demonstrated, a higher METS-IR index is positively related to asthma prevalence and correspondingly may result in asthma onset at younger ages.

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.

Association between Lung Function and New-Onset Diabetes Mellitus in Healthy Individuals after a 6-Year Follow-up

BACKGROUND

We analyzed hemoglobin A1c (HbA1c) levels and various lung function test results in healthy individuals after a 6-year follow-up period to explore the influence of lung function changes on glycemic control.

METHODS

Subjects whose HbA1c levels did not qualify as diabetes mellitus (DM) and who had at least two consecutive lung function tests were selected among the people who visited a health promotion center. Lung function parameters, including forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV/FVC ratio, and forced expiratory flow 25% to 75% (FEF25%-75%), were divided into four groups based on their baseline quantiles. To evaluate future DM onset risk in relation to lung function changes, the correlation between baseline HbA1c levels and changes in lung function parameters after a 6-year follow-up period was analyzed.

RESULTS

Overall, 17,568 individuals were included; 0.9% of the subjects were diagnosed with DM. The individuals included in the quartile with FEV1/FVC ratio values of 78% to 82% had lower risk of DM than those in the quartile with FEV1/FVC ratio values of ≥86% after adjusting for age, sex, and body mass index (P=0.04). Baseline percent predicted FEV1, FVC, FEV1/FVC ratio, and FEF25%-75%, and differences in the FEV1/FVC ratio or FEF25%-75%, showed negative linear correlations with baseline HbA1c levels.

CONCLUSION

Healthy subjects with FEV1/FVC ratio values between 78% and 82% had 40% lower risk for future DM. Smaller differences and lower baseline FEV1/FVC ratio or FEF25%-75% values were associated with higher baseline HbA1c levels. These findings suggest that airflow limitation affects systemic glucose control and that the FEV1/FVC ratio could be one of the factors predicting future DM risk in healthy individuals.

School-Age Obese Asthmatic Children have Distinct Lung Function Measures From Lean Asthmatics and Obese Children

Background: The lung functions of children with obese asthma seem to be distinct from those of obese children or lean asthmatics.Aim: To measure baseline lung function, exercise-induced bronchoconstriction (EIB), and bronchial hyperreactivity (BHR) in school-age obese asthmatics (OA group) and to compare the data with obese children (O group), lean asthmatics (A group), and healthy controls (H group).Methods: One hundred seventy school-age children were enrolled in this prospective cross-sectional study. Baseline fractionated exhaled nitric oxide (FeNO), and baseline, post-exercise (post-E), and post-bronchodilation (post-BD) impulse oscillometry (IOS) and spirometry tests were performed. EIB and BHR were evaluated based on the difference (Δ) in post-E - baseline, and post-BD - baseline values.Results: The mean FeNO level was higher in the OA group than in the other groups (p = 0.002). Baseline zR5 and R5-20 were higher (p = 0.013 and p = 0.044), but zFEF25-75 was lower (p < 0.01), in the OA group. ΔPost-E - baseline zFEV1 was lower in the A group (p = 0.003) but was higher in the OA group (p = 0.014) than the other groups. ΔPost-BD - baseline zFEV1 was lower in the H group compared to the other three groups (p = 0.004), but no significant difference was observed among the O, A, and OA groups (p > 0.05).Conclusion: A higher airway inflammation (high FeNO), peripheral airway resistance (high zR5 and zR5-20) and a lower peripheral airway flow (low FEF25-75) were observed at baseline measurement in school-age obese asthmatics compared to lean asthmatics and obese children. Obese asthmatics had no EIB but exhibited a similar BHR to that of asthmatics.

The Gut/Lung Microbiome Axis in Obesity, Asthma, and Bariatric Surgery: A Literature Review

Mounting evidence suggests that obesity, parameters of metabolic syndrome, and asthma are significantly associated. Interestingly, these conditions are also associated with microbiome dysbiosis, notably in the airway microbiome for patients with asthma and in the gut microbiome for patients with obesity and/or metabolic syndrome. Considering that improvements in asthma control, lung function, and airway hyperresponsiveness are often reported after bariatric surgery, this review investigated the potential role of bacterial gut and airway microbiome changes after bariatric surgery in ameliorating asthma symptoms. Rapid and persistent gut microbiota alterations were reported following surgery, some of which can be sustained for years. The gut microbiome is thought to modulate airway cellular responses via short-chain fatty acids and inflammatory mediators, such that increased propionate and butyrate levels following surgery may aid in reducing asthma symptoms. In addition, increased prevalence of Akkermansia muciniphila after Roux-en-Y gastric bypass and sleeve gastrectomy may confer protection against airway hyperreactivity and inflammation. Metabolic syndrome parameters also improved following bariatric surgery, and whether weight-loss-independent metabolic changes affect airway processes and asthma pathobiology merits further research. Fulfilling knowledge gaps outlined in this review could facilitate the development of new therapeutic options for patients with obesity and asthma.

Weight loss in obese children with asthma - is it important?

Obesity is a significant public health problem worldwide, and it has been identified as an independent risk factor for asthma in both adults and children. Not only does obesity increase asthma risk, but it is also associated with decreased asthma-related quality of life, worsened symptoms and asthma control, increased frequency and severity of asthma exacerbations and reduced response to asthma medications. In this review we examine the epidemiology and implications of obesity in both children and adults with asthma, and how the obesogenic "western" diet contributes to asthma prevalence and progression. Finally, we summarise the current evidence on the impact of weight loss on asthma outcomes in both adults and children, highlighting the need for further research to be conducted in the paediatric population.

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.

Cross talk between Hsp72, HMGB1 and RAGE/ERK1/2 signaling in the pathogenesis of bronchial asthma in obese patients

BACKGROUND

The incidence of obesity-related asthma has shown a remarkable increase.

OBJECTIVES

We aimed to explore the role of heat shock protein 72 (Hsp72) and receptor for advanced glycation end products (RAGE) axis with its downstream signaling in the pathogenesis of obesity-related asthma.

METHODS

We enrolled a total of 55 subjects and divided them into three groups. Groups I and II included healthy, normal weight (n = 15) and obese (n = 15) subjects, respectively. Twenty-five obese asthmatics (group III) were subdivided into group IIIa (10 patients with mild to moderate asthma) and group IIIb (15 patients with severe asthma). High mobility group box 1 (HMGB1), interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), and urinary Hsp72 were immunoassayed. Hydrogen peroxide (H₂O₂) and free fatty acids (FFAs) levels were photometrically measured. RAGE mRNA expression was relatively quantified by real-time PCR.

RESULTS

We found significant elevations of serum HMGB1, IL-8, MCP1, ERK1/2, FFAs, and H₂O₂ levels as well as urinary Hsp72 levels in obese subjects compared to healthy control. These were more evident in patients with severe asthma (group IIIb). Multivariate regression analysis identified Hsp72 and ERK1/2 as independent predictors of bronchial asthma severity. Receiver operating characteristic (ROC) curve analysis revealed that areas under the curve (AUC) for Hsp72 and ERK1/2 were 0.991 and 0.981, respectively, which denotes a strong predictive value for identifying the severity of bronchial asthma in obese patients.

CONCLUSION

The current study highlights the role of Hsp72 and HMGB1/RAGE/ERK1/2 signaling cascade in the pathogenesis of bronchial asthma and its link to obesity, which could be reflected on monitoring, severity grading, and management of this disease.

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.

Asthma, exercise and metabolic dysregulation in paediatrics

Asthma is the most frequent chronic disease in childhood. Chest tightness, cough, wheezing and dyspnoea during or after exercise may be unique manifestations of asthma in up to 90% of subjects. Physical activity may be reduced by uncontrolled asthma symptoms and parental beliefs, impairing physical fitness of asthmatic children. Clinicians working in the field of allergy are aware of evidence supporting the benefits of physical activity for patients with asthma. Treatment of asthma is required in order to obtain its control and to avoid any limitation in sports and active play participation. As exercise performance in children with controlled asthma is not different from that of healthy controls, any exercise limitation cannot be accepted. Overweight and obesity may interfere with asthma and exercise, leading to dyspnoea symptoms. Evidences on the effect of insulin resistance on airway smooth muscle and on bronchial hyperactivity are presented. CONCLUSION: Exercise is part of the strategy to obtain the best control of asthma in childhood, but we have to optimise the asthma control therapy before starting exercise programming. Furthermore, it is crucial to give best attention on the effects of obesity and insulin resistance, because they could in turn influence patients' symptoms.

Pediatric Pulmonology year in review 2017: Part 3

Pediatric Pulmonology publishes original research, reviews, and case reports related to a wide range of children's respiratory disorders. We here summarize the past year's publications in our major topic areas, in the context of selected literature in these areas from other journals relevant to our discipline. This review (Part 3 of a 5-part series) covers selected articles on asthma, physiology/lung function testing, and respiratory infections.

Obesity and asthma

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

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.