Association between asthma and serum adiponectin concentration in women

A longitudinal study on the effect of PM2.5 components on blood pressure in the hypertensive patients from 2011 to 2019

Extensive research has established the link between PM2.5 exposure and blood pressure (BP) levels among normal individuals. However, the association between PM2.5 components and BP levels in hypertensive patients has not been fully explored. In this study, 12 971 hypertensive cases from Jinchang cohort (in Jinchang City, China) with nearly 9 years of follow-up were enrolled. Based on the linear mixed-effect model, the effects of fine particulate matter (PM2.5) and five major components [sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), black carbon (BC) and organic matter (OM)]on BP [systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP)]were evaluated by single-component model, component-joint model and component-residual model, respectively. A positive correlation was found between PM2.5 as well as its components (SO42-, NO3-, NH4+, BC and OM) exposure and BP levels. The effects of SO42-, BC and OM on BP were observed to be the most robust among the three models. Based on the results of interaction effects and stratified analysis, the effect of BC exposure on SBP, and the effect of PM2.5 and its five components on PP were greater in female than in males. Compared with elderly hypertensive patients, OM had more significant effects on SBP, DBP and MAP in young and (or) middle-aged hypertensive patients. During the heating season, the effect of PM2.5 and its components on BP was grater compared to the non-heating season. Meanwhile, PM2.5 and its components have a greater influence on BP in patients with hypertension combined with diabetes. Therefore, the findings suggested that both PM2.5 exposure and its components had a significant effect on BP in patients with hypertension. Women and young and middle-aged hypertensive patient were the sensitive population. The implementation of source control and reduction of PM2.5 emission (mainly for SO42-, BC and OM) may be of great significance to control BP level and could reduce the risk of cardiovascular disease in patients with hypertension.

Euiin-Tang Attenuates Obesity-Induced Asthma by Resolving Metaflammation

Euiin-tang reduces obesity and hypertension. Patients with obesity may develop obesity-induced asthma (OIA) owing to phlegm dampness. This study aimed to determine whether euiin-tang alleviates high-fat diet (HFD)-induced OIA in C57BL/6 mice. OIA was developed by HFD feeding for 15 weeks in C57BL/6 mice, and euiin-tang (5 mg/10 g/day) was orally administered for the last five weeks. Oral administration of euiin-tang suppressed HFD-induced changes in body weight, liver weight, airway hypersensitivity (AHR), and immune cell infiltration in bronchoalveolar lavage fluid. Histological analysis revealed that euiin-tang treatment suppressed HFD-induced mucosal inflammation, hypersecretion, and fibrosis. The lungs and gonadal white adipose tissue showed increased expression of inflammatory cytokines (IL-1β, IL-17A, TNF-α, IL-6, IL-13, IFN-γ, MPO, and CCL2) following HFD, whereas euiin-tang inhibited this increase. HFD also increased the number of pro-inflammatory CD86+ M1 macrophages and decreased the number of anti-inflammatory CD206+ M2 macrophages in the lungs, whereas euiin-tang treatment reversed these effects. HFD induced a decrease in adiponectin and an increase in leptin, which was reversed by euiin-tang. Therefore, euiin-tang may be a potential therapeutic agent for OIA because it suppresses metaflammation as demonstrated in the present study.

Association between ambient air pollutants and lipid profile: A systematic review and meta-analysis

BACKGROUND

Studies of the effects of atmospheric pollutants on lipid profiles remain inconsistent and controversial.

AIM

The study was aimed to investigate the relationship between the exposure to ambient air pollutants and variations in the blood lipid profiles in the population.

METHODS

A comprehensive search of three different databases (PubMed, Web of Science, and the Cochrane Library) until December 17, 2022, yielded 17 origional studies fulfilling the inclusion criteria for a meta-analysis. Aggregate effect measures and 95% confidence intervals (95% CI) for the relevant ambient air pollutants were deduced employing random effects models.

RESULTS

The collective meta-analysis indicated that long-term exposure to PM₁, PM_2.5, PM₁₀ and CO showed a substantial correlation with TC (PM₁: β = 2.04, 95%CI = 0.15-3.94; PM_2.5: β = 1.11, 95%CI = 0.39-1.84; PM₁₀: β = 1.70, 95%CI = 0.67-2.73; CO: β = 0.08, 95%CI = 0.06-0.10), PM₁₀ exhibited a significant association with TG (β = 0. 537,95% CI = 0.09-0.97), whereas HDL-C demonstrated notable relationships with PM₁, PM₁₀, SO₂ and CO (PM₁: β = -2.38, 95%CI = -4.00 to -2.76; PM₁₀: β = -0.77, 95%CI = -1.33 to -0.21; SO₂: β = -0.91, 95%CI = -1.73 to -0.10; CO: β = -0.03, 95%CI = -0.05 to 0.00). PM_2.5, PM₁₀ also showed significant associations with LDL-C (PM_2.5: β = 1.44 95%CI = 0.48-2.40; PM₁₀: β = 1.62 95%CI = 0.90-2.34). Subgroup analysis revealed significant or stronger correlations predominantly in cohort study designs, with higher male comparisons, and in regions exhibiting elevated contaminant levels.

CONCLUSION

In summary, the analysis substantiates that ambient air pollutants can be recognized as potent contributors to alterations in lipid profiles, particularly particulate pollutants which exert more obvious effects on lipid profiles.

Herbal medicine for the treatment of obesity-associated asthma: a comprehensive review

Obesity is fast growing as a global pandemic and is associated with numerous comorbidities like cardiovascular disease, hypertension, diabetes, gastroesophageal reflux disease, sleep disorders, nephropathy, neuropathy, as well as asthma. Studies stated that obese asthmatic subjects suffer from an increased risk of asthma, and encounter severe symptoms due to a number of pathophysiology. It is very vital to understand the copious relationship between obesity and asthma, however, a clear and pinpoint pathogenesis underlying the association between obesity and asthma is scarce. There is a plethora of obesity-asthma etiologies reported viz., increased circulating pro-inflammatory adipokines like leptin, resistin, and decreased anti-inflammatory adipokines like adiponectin, depletion of ROS controller Nrf2/HO-1 axis, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) associated macrophage polarization, hypertrophy of WAT, activation of Notch signaling pathway, and dysregulated melanocortin pathway reported, however, there is a very limited number of reports that interrelates these pathophysiologies. Due to the underlying complex pathophysiologies exaggerated by obese conditions, obese asthmatics respond poorly to anti-asthmatic drugs. The poor response towards anti-asthmatic drugs may be due to the anti-asthmatics approach only that ignores the anti-obesity target. So, aiming only at the conventional anti-asthmatic targets in obese-asthmatics may prove to be futile until and unless treatment is directed towards ameliorating obesity pathogenesis for a holistic approach towards amelioration of obesity-associated asthma. Herbal medicines for obesity as well as obesity-associated comorbidities are fast becoming safer and more effective alternatives to conventional drugs due to their multitargeted approach with fewer adverse effects. Although, herbal medicines are widely used for obesity-associated comorbidities, however, a limited number of herbal medicines have been scientifically validated and reported against obesity-associated asthma. Notable among them are quercetin, curcumin, geraniol, resveratrol, β-Caryophyllene, celastrol, tomatidine to name a few. In view of this, there is a dire need for a comprehensive review that may summarize the role of bioactive phytoconstituents from different sources like plants, marine as well as essential oils in terms of their therapeutic mechanisms. So, this review aims to critically discuss the therapeutic role of herbal medicine in the form of bioactive phytoconstituents against obesity-associated asthma available in the scientific literature to date.

Potential for repurposing oral hypertension/diabetes drugs to decrease asthma risk in obesity

OBJECTIVE

Risk for asthma in the overweight/obese may be mediated by adiponectin and peroxisome proliferator activated receptor pathways and may be reduced by the use of oral drugs impacting these pathways, such as angiotensin converting enzyme inhibitors (ACE-I), thiazolidinediones (TZD), and angiotensin receptor blockers (ARB). Our study objective was to determine whether ACE-I, TZD, and/or ARB use in overweight/obese adults with diabetes mellitus and/or hypertension is associated with a lower risk for incident asthma.

METHODS

Using an existing cohort of American veterans, we performed a longitudinal data analysis over 15 years. Exposure was defined by the prescription pickup of ACE-I, TZD, and/or ARB for at least 4 weeks. The outcome, time until new-onset of clinician-diagnosed asthma, was studied using survival analysis. The propensity scoring method controlled for treatment selection bias.

RESULTS

2.83 million eligible veterans, including 77,278 with incident asthma, were studied. As compared to those unexposed, the use of ACE-I alone, TZD alone, or their combinations were each associated with decreased risk for incident asthma (hazard ratios of 0.88, 0.74, and 0.20, respectively; p < 0.001 for all analyses in the fully adjusted statistical models). TZD lowered the risk among racial/ethnic minority subjects more than among White participants (p < 0.001). On the other hand, ARB use alone or in combination with TZD was associated with a higher risk for incident asthma.

CONCLUSIONS

Use of ACE-I and/or TZD was associated with a lower risk for incident asthma in overweight/obese patients with diabetes mellitus and/or hypertension.

Association of weight-adjusted-waist index with asthma prevalence and the age of first asthma onset in United States adults

Objective

The objective of this study was to assess whether the weight-adjusted-waist index(WWI) is associated with the prevalence of asthma and age when first asthma onset appears in US adults.

Methods

For analysis we selected participants from the National Health and Nutrition Examination Survey(NHANES)database between 2001 and 2018. A dose-response curve was calculated using logistic regression,subgroup analysis,and a dose-response curve.

Results

The study included 44480 people over the age of 20,including 6061 reported with asthma, and the increase in asthma prevalence was 15% associated with each unit increase in the WWI, after adjusting for all confounders(odds ratio(OR)=1.15,95% CI:1.11,1.20). The sensitivity analysis was performed by trichotomizing the WWI, and compared to the lowest tertile, the highest tertile WWI group displayed a 29% increase in asthma prevalence(OR=1.29,95% CI:1.19,1.40). A nonlinear correlation was found between the WWI index and the risk of asthma onset, with a threshold saturation effect indicating an inflection point of 10.53 (log-likelihood ratio test, P<0.05), as well as a positive linear correlation with age at first asthma onset.

Conclusions

A higher WWI index was associated with an increased prevalence of asthma and an older age of first asthma onset.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

The impact of obesity and uncontrolled asthma during pregnancy on metabolic and inflammatory pathways

Asthma and obesity are both inflammatory complications of pregnancy and when combined contribute to an increased risk of uncontrolled asthma during pregnancy and poor perinatal outcomes. Our previous work has identified the presence of maternal asthma is associated with a proinflammatory milieu in the placenta and reduced fetal growth. The current study was designed to determine the relationships between immunomodulatory metabolic pathways and inflammation and establish whether these pathways are associated with uncontrolled asthma in obese pregnant women.Fifty-three obese (BMI >30) pregnant women were recruited prospectively. Participants were classified as having no asthma, controlled asthma, and uncontrolled asthma based on a doctor diagnosis and assessment using the Asthma Control Questionnaire (ACQ). Circulating plasma concentrations of metabolic hormones leptin, adiponectin, insulin, glucose, and extracellular vesicle (EVs) associated cytokines were measured at 18- and 36-weeks gestation.Concentrations of metabolic and inflammatory markers among obese participants with or without asthma were not significantly different throughout gestation. However total adiponectin concentrations increased as gestation progressed in obese, non-asthmatic women but did not increase in women with asthma. Plasma adiponectin and leptin levels in women with uncontrolled asthma were positively correlated with EV inflammatory markers including GM-CSF, IL-6, TNFα and IFNγ protein.This study demonstrated that most metabolic markers remain unchanged with the presence and severity of asthma in obese pregnant women. However, differences in the associations between metabolic and inflammatory pathways were observed in women with asthma and may be one of the mechanisms contributing to uncontrolled asthma in obese pregnant women.

Cytokines Profile and Lung Function in Children with Obesity and Asthma: A Case Control Study

The existence of common inflammatory biomarkers linking obesity and asthma in children has been hypothesized. Nevertheless, laboratory and clinical characteristics of children with obesity and asthma are still poorly defined. The primary aim of the present study is to investigate the lung function and the cytokine profile, in children with obesity and asthma. In this prospective, cross-sectional pilot study, pulmonary function tests, biochemical parameters, and serum cytokines levels were compared in three groups of 28 children each, matched for age and sex. Obese children showed normal forced spirometry values except an increased distal airway resistance in subjects with obesity and no asthma. Both groups including obese children showed higher leptin and IL-10 levels and lower adiponectin and TNF-alpha levels compared to children with no obesity and asthma. IL-33 and TGF-beta1 levels were higher in children with obesity and asthma vs. children with normal weight and asthma. Finally, IL-6 was undetectable in approximately 70% of obese children with no asthma, in 57% obese asthmatic children and in 100% of children with normal-weight and asthma. Children with obesity and asthma show the most striking cytokine profile, suggesting a pro-inflammatory role of fat mass in asthma development.

Association between traffic-related air pollution and anxiety hospitalizations in a coastal Chinese city: are there potentially susceptible groups?

Motor vehicle exhaust emissions have become the main source of urban air pollution in China, but few studies have explored the association of short-term exposure to traffic-related air pollutants (TRAPs) with anxiety disorders. Thus, we used an overdispersed, generalized additive model (GAM) to investigate the association between TRAPs and hospital admissions (HAs) for anxiety in Qingdao, a coastal Chinese city with high vehicle ownership. In addition, stratified analyses were performed by gender, age, season and hospitalization frequency (first admission and readmission). A positive association between TRAPs and HAs for anxiety was observed. Both inhalable particulate matter (PM₁₀) and nitrogen dioxide (NO₂) showed significant effects at lag 3 in the single-day lag structure, and each 10 μg/m³ increase in the concentrations was significantly associated with increases of 0.88% [95% confidence interval (CI): 0.04%, 1.72%] for PM₁₀ and 2.74% (0.45%, 5.08%) for NO₂ on anxiety hospitalizations. For fine particulate matter (PM_2.5) and carbon monoxide (CO), the strongest effects were found at lag05 and lag04 [2.67% (0.77%, 4.62%) and 0.19% (0.04%, 0.34%), respectively] in the multiday lag structure. The estimates of PM_2.5 were relatively robust after adjusting for other pollutants in the two-pollutant model. Stratified analyses indicated that the associations were stronger in females and younger individuals (<45 in age) than in males and elderly individuals (≥45 in age). Furthermore, the effects of PM_2.5 and CO were most obvious during the cold season. Regarding hospitalization frequency, only PM_2.5 was found to have a significant effect in the first-admission group. The results showed that short-term exposure to TRAPs, especially to PM_2.5, was significantly associated with the increased risk of daily HAs for anxiety, which can help clinicians and policymakers better understand the effects of TRAPs to implement targeted interventions.

Sex-difference in air pollution-related acute circulatory and respiratory mortality and hospitalization

BACKGROUND

Numerous studies have estimated adverse effects of short-term exposure to ambient air pollution on public health. Few have focused on sex-differences, and results have been inconsistent. The purpose of this study was three-fold: to identify sex-differences in air pollution-related health outcomes; to examine sex-differences by cause and season; and to examine time trends in sex-differences.

METHODS

Daily data were collected on circulatory- and respiratory-related mortality (for 29 years) and cause-specific hospitalization (for 17 years) with hourly concentrations of ozone (O3), nitrogen dioxide (NO2), and fine particulate matter (PM2.5). For hospitalization, more specific causes were examined: ischemic heart disease (IHD), other heart disease (OHD), cerebrovascular disease (CEV), chronic lower respiratory diseases (CLRD), and Influenza/Pneumonia (InfPn). Generalized Poisson models were applied to 24 Canadian cities, and the city-specific estimates were combined for nationwide estimates for each sex using Bayesian hierarchical models. Finally, sex-differences were tested statistically based on their interval estimates, considering the correlation between sex-specific national estimates.

RESULTS

Sex-differences were more frequently observed for hospitalization than mortality, respiratory than circulatory health outcomes, and warm than cold season. For hospitalization, males were at higher risk (M > F) for warm season (OHD and InfPn from O3; IHD from NO2; and InfPn from PM2.5), but F > M for cold season (CEV from O3 and OHD from NO2). For mortality, we found F > M only for circulatory diseases from ozone during the warm season. Among the above-mentioned sex-differences, three cases showed consistent time trends over the years: while M > F for OHD from O3 and IHD from NO2, F > M for OHD from NO2.

CONCLUSIONS

We found that sex-differences in effect of ambient air pollution varied over health outcome, cause, season and time. In particular, the consistent trends (either F > M or M > F) across 17 years provide stronger evidence of sex-differences in hospitalizations, and warrant investigation in other populations.

Plasma adiponectin and risk of asthma: observational analysis, genetic Mendelian randomisation and meta-analysis

BACKGROUND

Adiponectin, an adipocyte-secreted protein-hormone with inflammatory properties, has a potentially important role in the development and progression of asthma. Unravelling whether adiponectin is a causal risk factor for asthma is an important issue to clarify as adiponectin could be a potential novel drug target for the treatment of asthma.

OBJECTIVE

We tested the hypothesis that plasma adiponectin is associated observationally and causally (using genetic variants as instrumental variables) with risk of asthma.

METHODS

In the Copenhagen General Population Study, we did an observational analysis in 28 845 individuals (2278 asthma cases) with plasma adiponectin measurements, and a genetic one-sample Mendelian randomisation analysis in 94 868 individuals (7128 asthma cases) with 4 genetic variants. Furthermore, in the UK Biobank, we did a genetic two-sample Mendelian randomisation analysis in 462 933 individuals (53 598 asthma cases) with 12 genetic variants. Lastly, we meta-analysed the genetic findings.

RESULTS

While a 1 unit log-transformed higher plasma adiponectin in the Copenhagen General Population Study was associated with an observational OR of 1.65 (95% CI 1.29 to 2.08) for asthma, the corresponding genetic causal OR was 1.03 (95% CI 0.75 to 1.42). The genetic causal OR for asthma in the UK Biobank was 1.00 (95% CI 0.99 to 1.00). Lastly, genetic meta-analysis confirmed lack of association between genetically high plasma adiponectin and causal OR for asthma.

CONCLUSION

Observationally, high plasma adiponectin is associated with increased risk of asthma; however, genetic evidence could not support a causal association between plasma adiponectin and asthma.

Regulatory Peptides in Asthma

Numerous regulatory peptides play a critical role in the pathogenesis of airway inflammation, airflow obstruction and hyperresponsiveness, which are hallmarks of asthma. Some of them exacerbate asthma symptoms, such as neuropeptide Y and tachykinins, while others have ameliorating properties, such as nociception, neurotensin or β-defensin 2. Interacting with peptide receptors located in the lungs or on immune cells opens up new therapeutic possibilities for the treatment of asthma, especially when it is resistant to available therapies. This article provides a concise review of the most important and current findings regarding the involvement of regulatory peptides in asthma pathology.

Metformin prevents airway hyperreactivity in rats with dietary obesity

Increased insulin is associated with obesity-related airway hyperreactivity and asthma. We tested whether the use of metformin, an antidiabetic drug used to reduce insulin resistance, can reduce circulating insulin, thereby preventing airway hyperreactivity in rats with dietary obesity. Male and female rats were fed a high- or low-fat diet for 5 wk. Some male rats were simultaneously treated with metformin (100 mg/kg orally). In separate experiments, after 5 wk of a high-fat diet, some rats were switched to a low-fat diet, whereas others continued a high-fat diet for an additional 5 wk. Bronchoconstriction and bradycardia in response to bilateral electrical vagus nerve stimulation or to inhaled methacholine were measured in anesthetized and vagotomized rats. Body weight, body fat, caloric intake, fasting glucose, and insulin were measured. Vagally induced bronchoconstriction was potentiated only in male rats on a high-fat diet. Males gained more body weight, body fat, and had increased levels of fasting insulin compared with females. Metformin prevented development of vagally induced airway hyperreactivity in male rats on high-fat diet, in addition to inhibiting weight gain, fat gain, and increased insulin. In contrast, switching rats to a low-fat diet for 5 wk reduced body weight and body fat, but it did not reverse fasting glucose, fasting insulin, or potentiation of vagally induced airway hyperreactivity. These data suggest that medications that target insulin may be effective treatment for obesity-related asthma.

Adiponectin and Asthma: Knowns, Unknowns and Controversies

Adiponectin is an adipokine associated with the healthy obese phenotype. Adiponectin increases insulin sensitivity and has cardio and vascular protection actions. Studies related to adiponectin, a modulator of the innate and acquired immunity response, have suggested a role of this molecule in asthma. Studies based on various asthma animal models and on the key cells involved in the allergic response have provided important insights about this relation. Some of them indicated protection and others reversed the balance towards negative effects. Many of them described the cellular pathways activated by adiponectin, which are potentially beneficial for asthma prevention or for reduction in the risk of exacerbations. However, conclusive proofs about their efficiency still need to be provided. In this article, we will, briefly, present the general actions of adiponectin and the epidemiological studies supporting the relation with asthma. The main focus of the current review is on the mechanisms of adiponectin and the impact on the pathobiology of asthma. From this perspective, we will provide arguments for and against the positive influence of this molecule in asthma, also indicating the controversies and sketching out the potential directions of research to complete the picture.

Pollutant-sex specific differences in respiratory hospitalization and mortality risk attributable to short-term exposure to ambient air pollution

BACKGROUND

Many studies have reported associations of individual pollutants with respiratory hospitalization and mortality based on different populations, which makes it difficult to directly compare adverse health effects among multiple air pollutants.

OBJECTIVES

The study goal is to compare acute respiratory-related hospitalization and mortality associated with short-term exposure to three ambient air pollutants and analyze differences in health risks by season, age and sex.

METHODS

Hourly measurements of air pollutants (ozone, NO₂, PM_2.5) and temperature were collected from ground-monitors for 24 cities along with daily hospitalization (1996-2012) and mortality (1984-2012) data. National associations between air pollutant and health outcome were estimated for season (warm, cold vs. year-round), age (base ≥ 1, seniors > 65), and sex (females ≥ 1 and males ≥ 1) using Bayesian hierarchical models.

RESULTS

Overall, the three air pollutants were significantly associated with acute respiratory health outcomes at different lag-days. For respiratory hospitalization, the increased risks in percent changes with 95% posterior intervals for a 10-unit increase in each pollutant were: ozone (lag1, 0.7% (0.4, 0.9)), NO₂ (lag0, 0.7% (0.1, 1.4)), and PM_2.5 (lag1, 1.3% (0.7, 1.9)). For respiratory mortality: ozone (lag2, 1.2% (0.4, 1.9)), NO₂ (lag1, 2.1% (0.6, 3.5)), and PM_2.5 (lag1, 0.6% (-1.0, 2.2)). While some differences in risk were observed by season and age group, sex-specific differences were more pronounced. Compared with males, females had a higher respiratory mortality risk (1.8% (0.6, 2.9) vs 0.5% (-0.3, 1.3)) from ozone, a higher respiratory hospitalization risk (0.9% (0.0, 1.8) vs 0.6% (-0.3, 1.4)) but lower mortality risk (1.4% (-1.0, 3.7) vs 2.2% (0.4, 4.0)) from NO₂, and a lower hospitalization risk (0.7% (-0.2, 1.7) vs 1.8% (1.0, 2.6)) from PM_2.5.

CONCLUSION

This study reports significant health effects of short-term exposure to three ambient air pollutants on respiratory hospitalization (ozone≈NO₂ < PM_2.5 per-10 unit; ozone>NO₂ ≈ PM_2.5 per-IQR) and mortality (ozone≈NO₂ > PM_2.5) in Canada. Pollutant-sex-specific differences were found, but inconclusive due to limited biological and physiological explanations. Further studies are warranted to understand the pollutant-sex specific differences.

Comparison of hospitalization and mortality associated with short-term exposure to ambient ozone and PM2.5 in Canada

BACKGROUND

Hospitalization and mortality (H-M) have been linked to air pollution separately. However, previous studies have not adequately compared whether air pollution is a stronger risk factor for hospitalization or mortality. This study aimed to investigate differences in H-M risk from short-term ozone and PM_2.5 exposures, and determine whether differences are modified by season, age, and sex.

METHODS

Daily ozone, PM_2.5, temperature, and all-cause H-M counts (ICD-10, A00-R99) were collected for 22-24 Canadian cities for up to 29 years. Generalized additive Poisson models were employed to estimate associations between each pollutant and health outcome, which were compared across season (warm, cold, or year-round), age (all ages or seniors > 65), and sex.

RESULTS

Overall, ozone and PM_2.5 showed higher season-specific risk of mortality than hospitalization: warm-season ozone: 0.54% (95% credible interval, 0.20, 0.85) vs. 0.14% (0.02, 0.27) per 10 ppb; and year-round PM_2.5: 0.90% (0.33, 1.41) vs. 0.29% (0.03, 0.56) per 10 μg/m³. While age showed little H-M difference, sex appeared to be a modifier of H-M risk. While females had higher mortality risk, males had higher hospitalization risk: for females, ozone 0.87% (0.36, 1.35) vs. -0.03% (-0.18, 0.11) and PM_2.5 1.19% (0.40, 1.90) vs. 0.19% (-0.10, 0.47); and for males ozone 0.20% (-0.28, 0.65) vs. 0.35% (0.18, 0.51).

CONCLUSION

This study found H-M differences attributable to ozone and PM_2.5, suggesting that both are stronger risk factors for mortality than hospitalization. In addition, there were clear H-M differences by sex: specifically, females showed higher mortality risk and males showed higher hospitalization risk.

How to apply the personalized medicine in obesity-associated asthma?

INTRODUCTION

Obesity-associated asthma (OA) is frequently severe, with an increased rate of hospitalizations, numerous comorbidities and low response to corticosteroids. Despite progress in applying for personalized medicine in asthma, no specific recommendations exist for the management of OA.

AREAS COVERED

The aim of this review is to summarize recent data about the relationship obesity-asthma, describe clinical characteristics, potential mechanisms involved and possible therapeutic interventions to improve OA outcomes. Extensive research in the PubMed was performed using the following terms: "asthma and obesity" and "obese asthma" in combination with "phenotypes", "airway inflammation", "biomarkers", "lung function", "weight loss", "lifestyle interventions", "therapies" Currently two phenotypes are described. Early-onset atopic asthma is conventional allergic asthma aggravated by the pro-inflammatory properties of adipose tissue in excess, while late-onset non-atopic asthma is due to airway dysfunction as a consequence of the chronic lung compression caused by the obese chest walls. Previous data showed that different therapeutic strategies used in weight loss have a positive impact on OA outcomes.

EXPERT OPINION

The presence of a multidisciplinary team (chest physician, nutritionist, exercise physiologist, physiotherapist, psychologist, bariatric surgeon) and the collaboration between different specialists are mandatory to optimize the management and to apply the personalized medicine in OA.

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.

Admixture mapping of asthma in southwestern Europeans with North African ancestry influences

The prevalence of asthma symptoms in Canary Islanders, a southwestern European population from Spain, is almost three times higher than the country average. Because the genetic risks identified so far explain <5% of asthma heritability, here we aimed to discover new asthma loci by completing the first admixture mapping study in Canary Islanders leveraging their distinctive genetic makeup, where significant northwest African influences coexist in the European genetic diversity landscape. A 2-stage study was conducted in 1,491 unrelated individuals self-declaring having a Canary Islands origin for the 4 grandparents. Local ancestry estimates were obtained for the shared positions with reference data from putative ancestral populations from Europe, North Africa, and sub-Saharan Africa. Case-control deviations in local ancestry were tested for each ancestry separately using logistic regressions adjusted for principal components, followed by fine-mapping analyses based on imputed genotypes and analyses of the likely deleterious exonic variants. The admixture mapping analysis of asthma detected that local North African ancestry in a locus spanning 365 kb of chromosome 16q23.3 was associated with asthma risk at study-wide significance [lowest P = 1.12 × 10^-4; odds ratio (OR) = 2.05; 95% confidence interval (CI) = 1.41-3.00]. Fine-mapping studies identified a variant associated with asthma, and results were replicated in independent samples (rs3852738, OR = 1.34; 95% CI = 1.13-1.59, P = 7.58 × 10^-4). Whole exome sequencing data from a subset of individuals revealed an enrichment of likely deleterious variants among asthma cases in 16q23.3, particularly in the phospholipase Cγ2 (PLCG2) gene (P = 3.67 × 10^-4). By completing the first mapping study of asthma in admixed populations from Europe, our results revealed a new plausible asthma locus.

Obesity-induced asthma: Role of free fatty acid receptors

Obesity is a major risk factor for the development of asthma, and worsens the key features of asthma including airway hyperresponsiveness, inflammation, and airway remodeling. Although pro- and anti-inflammatory adipocytokines may contribute to the pathogenesis of asthma in obesity, the mechanistic basis for the relationship between asthma and obesity remains unclear. In obese individuals, the increased amount of adipose tissue results in the release of more long-chain free fatty acids as compared to lean individuals, causing an elevation in plasma long-chain free fatty acid concentrations. Recent findings suggest that the free fatty acid receptor 1 (FFAR1), which is a sensor of medium- and long-chain free fatty acids, is expressed on airway smooth muscle and plays a pivotal role in airway contraction and airway smooth muscle cell proliferation. In contrast, FFAR4, which is a sensor for long-chain n-3 polyunsaturated fatty acids and also expressed on airway smooth muscle, does not contribute to airway contraction and airway smooth muscle cell proliferation. Functional roles for short-chain fatty acid receptors FFAR2 and FFAR3 in the pathogenesis of asthma is still under debate. Taken together, adipose-derived long-chain free fatty acids may contribute to the pathogenesis of asthma in obesity through FFAR1.

Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway

Samples of PM_2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM_2.5 was 93 ± 24 μg m^-3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2 ng m^-3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10 μg dL^-1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5 μg dL^-1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10^-6).

Global association between ambient air pollution and blood pressure: A systematic review and meta-analysis

Although numerous studies have investigated the association of ambient air pollution with hypertension and blood pressure (BP), the results were inconsistent. We performed a comprehensive systematic review and meta-analysis of these studies. Seven international and Chinese databases were searched for studies examining the associations of particulate (diameter<2.5 μm (PM_2.5), 2.5-10 μm (PM_2.5-10) or >10 μm (PM₁₀)) and gaseous (sulfur dioxide (SO₂), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), ozone (O₃), carbon monoxide (CO)) air pollutants with hypertension or BP. Odds ratios (OR), regression coefficients (β) and their 95% confidence intervals were calculated to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and meta-regression analysis were also conducted. The overall meta-analysis showed significant associations of long-term exposures to PM_2.5 with hypertension (OR = 1.05), and of PM₁₀, PM_2.5, and NO₂ with DBP (β values: 0.47-0.86 mmHg). In addition, short-term exposures to four (PM₁₀, PM_2.5, SO₂, NO₂), two (PM_2.5 and SO₂), and four air pollutants (PM₁₀, PM_2.5, SO₂, and NO₂), were significantly associated with hypertension (ORs: 1.05-1.10), SBP (β values: 0.53-0.75 mmHg) and DBP (β values: 0.15-0.64 mmHg), respectively. Stratified analyses showed a generally stronger relationship among studies of men, Asians, North Americans, and areas with higher air pollutant levels. In conclusion, our study indicates a positive association between ambient air pollution and increased BP and hypertension. Geographical and socio-demographic factors may modify the pro-hypertensive effects of air pollutants.

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

RATIONALE

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Serum levels of adiponectin and leptin in asthmatic patients and its relation with asthma severity, lung function and BMI

INTRODUCTION

Asthma is one of the diseases which has a high prevalence in developed and developing countries. The relationship between asthma and obesity has always been focused by researchers. In this field, adipokines, especially adiponectin and leptin have highly attended by the scientist. The aim of this study was to determine the serum level of adiponectin, leptin and the leptin/adiponectin ratio in asthmatic patients and its relationship with disease severity, lung function and BMI (body mass index).

METHODS

In this cross-sectional study, 90 asthmatic women admitted to the tertiary referral hospital in Kurdistan province - Iran, were examined. First, BMI was measured and then pulmonary function tests were performed in all asthmatics patient. Forced expiratory volume in 1s (FEV1), forced vital capacity (FVC), and FEV1/FVC, were measured. At the end, blood samples were collected and serum level of adiponectin and leptin were measured by ELISA method.

RESULT

Serum leptin and leptin/adiponectin levels correlated positively with asthma severity and BMI (p=0.0001), but there was no correlation between adiponectin level with asthma severity and BMI (p>0.05), also serum leptin and leptin/adiponectin levels inversely correlated with FEV1 and FVC in patient (p=0.0001).

CONCLUSION

Asthma is linked with obesity, and there is an association between asthma severity and BMI with serum leptin and leptin/adiponectin levels, but our results do not support a significant role of adiponectin in obesity or asthma.

The burden of obesity in asthma and COPD: Role of adiponectin

The influence of obesity on development, severity and prognosis of both asthma and COPD is attracting growing interest. The impact of obesity on the respiratory system ranges from structural modifications (decline of total lung capacity) to humoral alterations. Adipose tissue strongly contributes to the establishment of an inflammatory state being an important source of adipokines. Amongst adipokines, adiponectin is an important component of organ cross talk with adipose tissue exerting protective effects on a variety of pathophysiological processes. Adiponectin is secreted in serum where it abundantly circulates as complexes of different molecular weight. Adiponectin properties are mediated by specific receptors that are widely expressed with AdipoR1, AdipoR2, and T-cadherin being present on epithelial and endothelial pulmonary cells indicating a functional role on lung physiology. In COPD, mild to moderate obesity has been shown to have protective effects on patient's survival, while a higher mortality rate has been observed in patients with low BMI. A specific cluster of obese patients has been identified; in this group, asthma features are particularly severe and difficult to treat. Better understanding of the molecular mechanisms at the base of cross talk among different tissues and organs will lead to identification of new targets for both diagnosis and treatment of asthma and COPD.

Asthma in adolescence: Is there any news?

Asthma is a chronic disease that has a significant impact quality of life, which is particularly important in adolescence. We will discuss aspects of epidemiology, the clinical spectrum, diagnostics, and management of asthma in adolescence. In particular, we will highlight the psychological implications of having asthma during this developmental period. Data published in the past 10 years, since we last reviewed the subject, will be the main focus of this paper. The care of the teenager with asthma should take into account the rapid physical, emotional, cognitive, and social changes that occur during normal adolescence. The diagnostic process may be more difficult since teenagers tend to deny their illness. Thus, both under-diagnosis and under-assessment of asthma severity may lead to under-treatment and potentially avoidable morbidity and even mortality. Conversely, teenagers may be often misdiagnosed as having asthma or their asthma severity may be overestimated leading to inappropriate and sometimes excessive treatment. Educational programs, environmental avoidance measures, proper use of medications along with a skilled approach, and a caring attitude of health providers are all very important for successful management. Pediatr Pulmonol. 2017;52:129-138. © 2016 Wiley Periodicals, Inc.

Association of asthma diagnosis with leptin and adiponectin: a systematic review and meta-analysis

There is some evidence which shows that higher levels of serum leptin and lower levels of serum adiponectin are associated with the diagnosis of asthma. This meta-analysis evaluated the association of serum leptin and adiponectin levels with the diagnosis of asthma. We searched the MEDLINE, Cochrane, EMBASE and CINAHL Plus databases up to July 2015. Eligible studies were randomized controlled trials, prospective studies, retrospective studies, case-control studies and cohort studies. 13 studies with 3642 patients were included in the study. The meta-analysis found that in the overall study population, the diagnosis of asthma was associated with higher levels of leptin (pooled standardized difference in means=0.867, 95% CI 0.416 to 1.318, p<0.001) and lower levels of adiponectin (pooled standardized difference in means=-0.371, 95% CI -0.728 to -0.014, p=0.042) in patients with asthma compared with controls. Subgroup analysis found that higher leptin levels were associated with asthma both in adults (standardized difference in means=1.374, 95% CI 0.621 to 2.126, p<0.001) and children (standardized difference in means=0.302, 95% CI 0.010 to 0.594, p=0.042). However, borderline association of adiponectin with asthma was seen in adults (p=0.05), but not in children (p=0.509). Sensitivity analysis indicated that the findings for leptin were robust. Our findings are consistent with higher levels of serum leptin being associated with asthma regardless of age, and low adiponectin levels being associated with asthma in adults only.

Non-Invasive Ventilation (NIV) and Homeostatic Model Assessment (HOMA) Index in Stable Chronic Obstructive Pulmonary Disease (COPD) Patients with Chronic Hypercapnic Respiratory Failure: A Pilot Study

The effects of Non-invasive Ventilation (NIV) on Insulin Resistance (IR) in stable Chronic Obstructive Pulmonary Disease (COPD) patients have not been fully explored. The aim of this study was to assess the effects of NIV on IR and adiponectin levels during one year application of NIV in stable COPD patients with Chronic Hypercapnic Respiratory Failure. Twenty-five (25) stable COPD patients with Chronic Hypercapnic Respiratory Failure and with no self-reported comorbidities completed the study. NIV was administered in the spontaneous/timed mode via a full face mask using a bi-level positive airway pressure system. Spirometry, blood pressure, arterial blood gases, dyspnea, daytime sleepiness, serum fasting glucose and insulin levels were assessed. IR was assessed with the calculation of the Homeostatic Model Assessment (HOMA) index. Adiponectin was measured with radioimmunoassay. Study participants were re-evaluated on the first, third, sixth, ninth and twelfth month after the initial evaluation. There was a significant improvement in FEV1 values from the first month (34.1 ± 11.6% vs 37 ± 12.3%, p = 0.05). There was a significant decrease in IR by the ninth month of NIV use (3.4 ± 2.3 vs 2.2 ± 1.4, p < 0.0001), while adiponectin levels significantly improved from the first month of NIV use. Stepwise regression analysis revealed that baseline HOMA index was associated with paCO2 (β = 0.07 ± 0.02, p = 0.001), while baseline adiponectin levels were associated with FVC (β = 0.05 ± 0.02, p = 0.035) and the concentration of serum bicarbonate (HCO3-) (-β = 0.18 ± 0.06, p = 0.002). Insulin sensitivity and glucose metabolism as well as adiponectin levels improved along with the improvements in respiratory failure.

Adipokines and Cysteinyl Leukotrienes in the Pathogenesis of Asthma

Background. The prevalence of obesity has increased dramatically over the last decades, and its association with asthma is being increasingly recognized. Aims. Our hypothesis is that increased leptin and decreased adiponectin levels in obese subjects play a direct role in regulating inflammation in asthmatics. We wanted to examine the hypothesis that cysteinyl leukotrienes (cys-LT), inflammatory mediators that are regulated by adipokines, are involved in the pathogenesis of asthma. Methods. We studied a population of asthmatics and nonasthmatics, who in turn were divided into obese and nonobese categories. We examined leptin and its ratio to adiponectin, in asthmatics and nonasthmatics, with and without obesity. In addition, we measured cys-LT levels in exhaled breath condensate (EBC) and in peripheral blood monocytes (PBM) in these groups. Results. Leptin levels were increased in obese asthmatics compared to obese nonasthmatics. The leptin/adiponectin (L/A) ratio was higher in obese asthmatics compared to obese nonasthmatics. EBC cys-LT levels were elevated in asthmatics compared to nonasthmatics. Discussion. Proinflammatory adipokines, released from adipose tissue, may promote an asthma phenotype through enhanced cys-LT production that may result in more prevalent and difficult to control airway disease.

Obesity, asthma prevalence and IL-4: Roles of inflammatory cytokines, adiponectin and neuropeptide Y

BACKGROUND

Obesity is associated with asthma risk and severity, but the underlying biological mechanisms are poorly understood. We hypothesized that cytokine markers of systemic inflammation, and adiponectin and neuropeptide Y (NPY) markers of immuno-modulating and neurohormonal regulation are involved in the obesity-asthma association.

METHODS

We explored the relationships between body mass index (BMI), C-reactive protein (CRP), IL-6, TNF-α, adiponectin and NPY with asthma prevalence and IL-4 levels in 70 youth with asthma and 69 age- and gender-matched healthy controls using cross-sectional and longitudinal data.

RESULTS

Mean BMI level was higher among patients with asthma than healthy controls (p < 0.001). In logistic regression models controlling for potential confounders, independent associations with asthma prevalence were found for obesity (p = 0.001), increasing tertiles of CRP (linear trend p < 0.001), IL-6 (linear trend p < 0.001) and lowest and highest tertiles of TNF-α (quadratic trend p < 0.05), increasing adiponectin (linear p = 0.022) and decreasing tertiles of NPY (linear trend p = 0.001). Among patients with asthma, NPY level was positively correlated with adiponectin (p < 0.05) and TNF-α (p < 0.05), and levels of NPY and IL-6 were significantly associated with IL-4 level at baseline and 1-year follow-up.

CONCLUSIONS

The obesity-asthma association was not explained by systemic inflammation. Specifically, CRP, TNF-a, IL-6, NPY and adiponectin were independently associated with asthma prevalence. NPY and IL-6 were associated with IL-4 marker of allergic airway inflammation in asthma and should be further investigated as prognostic markers of asthma outcomes.

Adiponectin in Asthma and Obesity: Protective Agent or Risk Factor for More Severe Disease?

PURPOSE

The relationship between asthma and obesity is well established, although the pathophysiological mechanisms linking both diseases remain unknown. Adiponectin is a hormone secreted by adipose cells, plays a role in the modulation of inflammation and may be the key linking these two types of inflammation.

METHODS

We conducted a cross-sectional study with asthma with different body mass indices (BMI); the patients were classified as eutrophic, overweight, or obese. We assessed disease control using the GINA consensus, and the levels of adiponectin, C-reactive protein (CRP) and interleukin 33 (IL-33) in each of the patients.

RESULTS

We evaluated 75 of the 96 patients eligible for the study, including 25 in each BMI group. The CRP levels were significantly higher in the obese patients compared with both the eutrophic (p = 0.01) and the overweight (p = 0.03) patients. The mean adiponectin level was 21.82 ± 9.93 mg/L for the eutrophic asthmatics, which is a level that was significantly higher than in the overweight (15.31 ± 6.27 mg/L, p = 0.0140) and the obese (16.69 ± 11.45 mg/L, p = 0.0287) patients. The patients with higher adiponectin levels exhibited smaller FEV1 (p = 0.02) and lower FVC (p = 0.003). The IL-33 levels were not different between the groups.

CONCLUSIONS

Adiponectin does not protect against the development of inflammation in the setting of asthma and may in fact exacerbate the disease via its anti-TH1 inflammatory effects, allowing for increased TH2 differentiation and a more severe allergic response.

Asthma and obesity: mechanisms and clinical implications

Obesity is the most common asthma co-morbidity; it has been associated with increased risk for asthma exacerbations, worse respiratory symptoms and poor control. The exact mechanisms remain elusive and are probably multifactorial, stemming from mechanical alterations of the airways and lung parenchyma, to systemic and airway inflammatory and metabolic dysregulation that adversely influences lung function and or response to therapy. However, the fact that not every obese asthmatic is equally affected by weight gain highlights the many challenges and complexities in understanding this association. The factors that determine susceptibility may not depend on being obese alone, but rather the interactions with other phenotypical characteristics, such as age of asthma onset, gender and race to name a few. Inability to account for asthma phenotypes that are differentially affected by increasing body mass index (BMI) may contribute to the lack of consistent results across studies. This review will provide a succinct summary of obesity-related mechanisms and the clinical impact on asthma including highlights on recent progress.

Association of serum adiponectin with asthma and pulmonary function in the Japanese population

Conflicting findings have been reported regarding the role of adiponectin in asthma. The aim of this study was to evaluate the association of adiponectin with pulmonary functions and asthma in the Japanese population. First, among a general population that participated in a previous study (group 1), we selected 329 subjects after excluding those with asthma, chronic obstructive pulmonary disease, and a smoking history and examined the associations of the serum total adiponectin levels with pulmonary functions. In a second cohort (group 2) consisting of 61 asthmatic patients and 175 control non-asthmatic subjects, we examined the associations between asthma and the levels of total, high (HMW), middle (MMW) and low (LMW) molecular weight adiponectin isoforms as well as the ratio of each isoform to total adiponectin level. Although the total adiponectin levels were not significantly different between the asthmatic and control subjects in group 2, the levels were significantly and positively associated with the forced expiratory volume in 1 s after adjustments for confounding factors (P < 0.05) in women in group 1. In group 2, the LMW adiponectin level was significantly higher and the MMW/total adiponectin ratio was significantly lower among the asthmatic subjects than among the control subjects after adjustments for confounding factors in both sexes (P < 0.05). The present study showed that a low total adiponectin level may lead to airway narrowing compatible with asthmatic airways in women, and higher LMW adiponectin levels and lower MMW/total adiponectin ratio are significantly associated with current asthma in both sexes.

The association of asthma, nasal allergies, and positive skin prick tests with obesity, leptin, and adiponectin

BACKGROUND

Cross-sectional and longitudinal reports show that obese adults have more asthma than non-obese adults. A proposed mechanism is via effects of adipokines (leptin and adiponectin) on the immune system.

OBJECTIVE

We wished to measure the associations of asthma and other atopic diseases with serum adipokine levels and to find whether the associations with asthma were strong enough to rule out the possibility that they are secondary to the association of fatness measures with asthma.

METHODS

The Global Asthma and Allergy Network of Excellence (GA(2) LEN) clinical follow-up survey is a clinical survey, embedded in a larger multi-centre cross-sectional postal survey, involving, with a case/control design, enrichment of the sample with subjects with asthma and chronic rhinosinusitis (CRS). We recorded serum leptin or adiponectin in 845 men and 1110 women in 15 centres and also anthropometric measures of fatness including body mass index and waist/hip ratio, current asthma, and specific skin prick and IgE sensitisation. We used inverse sampling-probability-weighted rank and regression statistics to measure population associations of disease outcomes with adipokines in males and females, adjusting for confounders (area, age, smoking history, and number of elder siblings) and also mutually adjusting associations with adipokines and fatness measures.

RESULTS

One thousand nine hundred and fifty-five subjects aged 16-77 years had information on leptin or adiponectin levels. Leptin and leptin/adiponectin ratio were positively associated with the level of asthma, especially in females (Somers' D of leptin by asthma score, 0.20; 95% CI, 0.08-0.30; P = 0.00079). These associations were attenuated after adjusting for confounders and became non-significant after additionally adjusting for fatness measures and multiple comparisons.

CONCLUSIONS AND CLINICAL RELEVANCE

Asthma levels are positively associated with serum leptin. However, we cannot rule out the possibility that this association is secondary to associations of both with fatness measures.

Childhood obesity and risk of allergy or asthma

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

Mechanisms of obesity in asthma

PURPOSE OF REVIEW

Obesity and asthma are chronic conditions affecting millions of people worldwide. The two conditions also appear to be linked with an increased risk of asthma in people who are obese. The purpose of this review is to describe mechanism(s) that may explain the association between asthma and obesity.

RECENT FINDINGS

Current evidence suggests that the association between asthma and obesity is linked by two major phenotypes and three important pathways of obesity-related asthma: one phenotype with primary (often atopic) asthma that is aggravated by obesity and a second phenotype with late-onset nonatopic asthma, which predominantly affects women and primarily seems to be associated with neutrophilic inflammation. Proposed pathways include the mechanical effects of obesity (fewer deep inspirations leading to increased airway hyperresponsiveness), an inflammatory pathway driven by obesity-related cytokines (adipokines), and finally environment and lifestyle changes that have led to an increasing prevalence of obesity over the past 50 years (including exposures in utero, physical activity, and diet) may also result in asthma in predisposed individuals. How these environmental changes influence the occurrence and expression of asthma may depend on the age of exposure and on interactions with genetic susceptibilities.

SUMMARY

Future research should be directed to shed light on the associations between obesity and asthma phenotypes, modern lifestyles and environmental exposures and genetic susceptibilities.

VIDEO ABSTRACT

http://links.lww.com/COAI/A6.

Endocrine regulation of airway contractility is overlooked

Asthma is a prevalent respiratory disorder triggered by a variety of inhaled environmental factors, such as allergens, viruses, and pollutants. Asthma is characterized by an elevated activation of the smooth muscle surrounding the airways, as well as a propensity of the airways to narrow excessively in response to a spasmogen (i.e. contractile agonist), a feature called airway hyperresponsiveness. The level of airway smooth muscle (ASM) activation is putatively controlled by mediators released in its vicinity. In asthma, many mediators that affect ASM contractility originate from inflammatory cells that are mobilized into the airways, such as eosinophils. However, mounting evidence indicates that mediators released by remote organs can also influence the level of activation of ASM, as well as its level of responsiveness to spasmogens and relaxant agonists. These remote mediators are transported through circulating blood to act either directly on ASM or indirectly via the nervous system by tuning the level of cholinergic activation of ASM. Indeed, mediators generated from diverse organs, including the adrenals, pancreas, adipose tissue, gonads, heart, intestines, and stomach, affect the contractility of ASM. Together, these results suggest that, apart from a paracrine mode of regulation, ASM is subjected to an endocrine mode of regulation. The results also imply that defects in organs other than the lungs can contribute to asthma symptoms and severity. In this review, I suggest that the endocrine mode of regulation of ASM contractility is overlooked.

Interaction of metabolic syndrome with asthma in postmenopausal women: role of adipokines

The increasing prevalence of both asthma and obesity are major health problems. Recent studies established a possible link between obesity and asthma; however, the underlying mechanism is not clear. The aim of the study was to analyze the prevalence of metabolic syndrome in postmenopausal subjects with asthma and search the interactions between adipokines, metabolic syndrome, and asthma. A total of 45 female patients (57.5 ± 13.9 years) with asthma and 30 healthy subjects (59.6 ± 12.8 years) in postmenopausal status were enrolled in this study. For the diagnosis of metabolic syndrome, modified World Health Organization diagnostic criteria were used. Blood levels of glucose, lipid profile, HbA1c, insulin, CRP, leptin, adiponectin, tumor necrosis factor-alpha, interleukin (IL)-6, IL-8 and plasminogen activator inhibitor-1 (PAI-1) were measured. The mean body mass index was 29.6 ± 5.4 for asthma patients and 28.2 ± 5.3 for the control group. The incidence of metabolic syndrome was found as 26 % for both groups. Insulin resistance as calculated by homeostasis model assessment (HOMA-IR) and fasting insulin levels were significantly higher in asthma patients (p < 0.001 for both parameters). Leptin levels were significantly higher (p = 0.001) and adiponectin levels were lower (p = 0.029) in asthma patients compared to controls. We concluded that although incidence of obesity and metabolic syndrome was not higher in postmenopausal asthma patients than controls, there was an impairment of glucose metabolism and altered adipokine levels in asthma patients.

High sputum total adiponectin is associated with low odds for asthma

OBJECTIVE

Adipose tissue produces adiponectin, an anti-inflammatory protein. High systemic total adiponectin is associated with a low risk for incident asthma but the association with lung adiponectin is not known. Our objective was to evaluate the association between sputum total adiponectin and asthma.

METHODS

This case-control study included 44 cases with objectively-confirmed asthma and an equal number of body mass index (BMI) and sex-matched controls. Serum and sputum adiponectin were estimated by ELISA and Western Blot technique, respectively. While Fisher's exact test, t-test and Spearman's correlations were used for univariate analyses, Spearman and regression analyses were performed for multivariable analyses.

RESULTS

While high-molecular-weight adiponectin was the dominant isoform in serum, medium-molecular-weight isoform was dominant in sputum. Sputum total adiponectin was not correlated with serum adiponectin or BMI. Sputum total adiponectin was lower among asthmatics than controls (p = 0.03), although individual sputum isoforms were not similarly associated. High sputum total adiponectin was associated with lower odds for asthma (OR 0.33, 95% C.I. 0.12, 0.91), even after adjustment for systemic adiposity measures including serum adiponectin.

CONCLUSIONS

High sputum total adiponectin predicted lower odds for asthma, even after adjustment for serum adiponectin. Although not studied, it is possible that pharmacological modulation of sputum adiponectin may suggest new ways to prevent and/or treat asthma.

The influence of obesity on inflammation and clinical symptoms in asthma

Obesity and asthma are both important public health issues. Increasing number of studies suggest the association between obesity and asthma which may be causal or accidental. The studies on animal models show innate enhancement of airway hyper-responsiveness which suggest that chronic airway hyper-responsiveness may be related to chronic low-grade systemic inflammation occurring in obesity. These results are confirmed by studies on asthmatic patients which show that levels of inflammation markers were higher in obese asthma patients and are related to the parameters of obesity. However, adipokines secreted by adipose tissue have also been involved in the regulation of inflammation and allergic responses, and suggested to affect the risk of asthma, especially in obese female patients. The studies on the association between adiposity and atopy have conflicting results and the issue needs to be investigated in the future. Obesity also decreases lung volume and increases airway resistance inducing symptoms that could mimic asthma. Clinical studies suggest that asthma in obese subjects may differ from the classical phenotype of the disease. Obese patients referred for asthma exacerbation present a reduced response to standard asthma medications. The review indicates that mechanical and inflammatory effects of obesity may explain the influence on asthma. Further studies on the association between adiposity and atopy on airway inflammation may confirm the active role of fat tissue, not only simple mechanical impairment of the thorax movement. Longitudinal studies are needed to understand the association between asthma, and obesity, which may open new therapeutic options for asthma treatment in obese patients.

Serum Leptin and Adiponectin Levels in Obese and Nonobese Asthmatic School Children in relation to Asthma Control

There is growing evidence of a positive correlation between asthma and obesity in children and adults. Leptin and adiponectin regulate several metabolic and inflammatory functions. This study aims to evaluate serum leptin and adiponectin concentrations in asthmatic school children to investigate their association with obesity and the degree of asthma control. Obese asthmatic (OA) and nonobese asthmatic (NOA) children, aged 7 to 14, were randomly enrolled in this prospective study. Data on demographic, anthropometric, serum lipids, and spirometric measures and allergy status were collected and analyzed. Serum leptin was significantly higher (25.8 ± 11.1 versus 8.7 ± 11.1; P < 0.0001) and adiponectin levels were lower (2.5 ± 1.2 versus 5.4 ± 2.9; P < 0.0001) in OA compared to NOA children. The uncontrolled group had higher leptin and lower adiponectin levels compared to well and partially controlled asthma. BMI was positively correlated with leptin (r = 0.79; P < 0.001) and negatively with adiponectin (r = -0.73; P < 0.001). Mean BMI and leptin levels were observed to be higher in girls compared to boys. Stepwise multiple linear regression analysis showed that higher BMI and female gender had significant effect on serum leptin levels. Among asthmatic children higher serum leptin and lower adiponectin levels were significantly associated with obesity and showed no significant association with degree of asthma controls.

Adiponectin, Leptin, and Resistin in Asthma: Basic Mechanisms through Population Studies

Adipokines, factors produced by adipose tissue, may be proinflammatory (such as leptin and resistin) or anti-inflammatory (such as adiponectin). Effects of these adipokines on the lungs have the potential to evoke or exacerbate asthma. This review summarizes basic mechanistic data through population-based and clinical studies addressing the potential role of adipokines in asthma. Augmenting circulating concentrations of adiponectin attenuates allergic airway inflammation and airway hyperresponsiveness in mice. Murine data is supported by human data that suggest that low serum adiponectin is associated with greater risk for asthma among women and peripubertal girls. Further, higher serum total adiponectin may be associated with lower clinical asthma severity among children and women with asthma. In contrast, exogenous administration of leptin results in augmented allergic airway hyperresponsiveness in mice. Alveolar macrophages obtained from obese asthmatics are uniquely sensitive to leptin in terms of their potential to augment inflammation. Consistent with this basic mechanistic data, epidemiologic studies demonstrate that higher serum leptin is associated with greater asthma prevalence and/or severity and that these associations may be stronger among women, postpubertal girls, and prepubertal boys. The role of adipokines in asthma is still evolving, and it is not currently known whether modulation of adipokines may be helpful in asthma prevention or treatment.

Immunometabolism in obese asthmatics: are we there yet?

Obesity is now recognised as a worldwide epidemic. The recent International Association for the Study of Obesity/International Obesity Taskforce (IASO/IOTF) analysis estimates that approximately 1.0 billion adults are currently overweight and a further 475 million are obese. Obesity has huge psychosocial impact with obese children and adolescents facing discrimination and stigmatization in many areas of their lives leading to body dissatisfaction, low self-esteem and depression. Indeed, obesity is recognised as an important risk factor for the development of several chronic diseases such as hypertension, cancer, asthma and metabolic syndrome. Chronic low grade systemic inflammation is considered as a hallmark of obesity and may possibly explain the link between obesity and chronic disease, in particular the increased incidence, prevalence and severity of asthma in obese individuals. There is now strong evidence for infiltration of immune and inflammatory cells into adipose tissue that drives systemic inflammation and subsequent end organ damage. In addition to adipocytes, the key adipose tissue resident immune cells are macrophages and mast cells. Immunometabolism, as an emerging field of investigation, explores the pivotal role of these immune cells in translating immunological changes to metabolic effects in obesity. Abundance of free fatty acids, along with other inflammatory cytokines shift the balance of metabolic homeostasis to pro-inflammatory status by influencing the development of inflammatory cell lineage, which, further exhibits distinct functional phenotypes. There is emerging evidence for macrophage activation and functional polarization of an anti-inflammatory M₂ phenotype towards a pro-inflammatory M₁ phenotype of macrophages in obese adipose tissue. Similarly, studies in both obese humans and murine models reveal the pathognomic presence of an increased number of mast cells in visceral adipose tissue. These suggest a possible contribution of mast cells to the unique metabolome of obese asthma. This review examines proposed multilevel interactions between metabolic and immune systems in obese asthmatics that underlie the negative effects of obesity and may offer significant therapeutic promise.

Body mass index is a stronger predictor than the metabolic syndrome for future asthma in women. The longitudinal CARDIA study

RATIONALE

It is hypothesized that the metabolic syndrome explains the association between body mass index (BMI) and asthma in adults.

OBJECTIVES

Our objective was to longitudinally compare the relative strengths of the associations of the metabolic syndrome and BMI with incident asthma in adults.

METHODS

We included 4,619 eligible participants in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort followed over 25 years. Incident asthma was defined by a new self-reported provider asthma diagnosis plus either the presence of asthma symptoms and/or use of asthma medications. Cox proportional hazard analyses were performed.

MEASUREMENTS AND MAIN RESULTS

Six hundred two subjects (417 women and 185 men) developed incident asthma over 25 years of follow-up. Metabolic syndrome predicted incident asthma among women but not men (unadjusted hazard ratios, 1.50 and 0.98; P = 0.01 and 0.93, respectively). BMI had a similar predictive association among women but not men (unadjusted hazard ratios, 1.19 and 1.04 per 5 units of BMI; P < 0.001 and 0.60, respectively). The association of metabolic syndrome with incident asthma in women was no longer statistically significant after adjustment for BMI (P = 0.44). In contrast, the association of BMI with incident asthma in women remained statistically significant after adjusting for the metabolic syndrome (P = 0.01). In a stepwise model, BMI was a stronger predictor than the metabolic syndrome (P = 0.001).

CONCLUSIONS

BMI is a stronger predictor of incident asthma among women than the metabolic syndrome. Other obesity-associated factors that are not a part of the metabolic syndrome may play a role in the BMI-asthma association in women.