Obesity and asthma: directions for research

Association of blood lipid profiles and asthma: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Observational studies and meta-analyses have indicated associations between blood lipid profiles and asthma. However, the causal association is unknown. Therefore, this study investigated the causal relationship between blood lipid profiles and asthma using bidirectional Mendelian randomization analysis.

METHODS AND MATERIALS

Our analyses were performed using individual data from the Taiwan Biobank and summary statistics from the Asian Genetic Epidemiology Network (AGEN). The causal estimates between all genetic variants, exposures of interest and asthma were calculated using an inverse-variance weighted method based on Taiwan Biobank data from 24,853 participants (mean age, 48.8 years; 49.8% women). Sensitivity analyses, including the weighted median, MR Egger regression, MR-PRESSO, mode-based estimate, contamination mixture methods, and leave-one-out analysis, were applied to validate the results and detect pleiotropy.

RESULTS

In the inverse-variance weighted (IVW) analyses, we found evidence of a significant causal effect of an increased level of low-density lipoprotein cholesterol on asthma risk (βIVW = 1.338, p = 0.001). A genetically decreased level of high-density lipoprotein cholesterol was also associated with asthma risk (βIVW = -0.338, p = 0.01). We also found that an increased level of total cholesterol was associated with an increased risk of asthma (βIVW = 1.343, p = 0.001). Several sensitivity analyses generated consistent findings. We did not find evidence to support the causality between asthma and blood lipid profiles in either direction.

CONCLUSION

Our results supported the causal relationship between higher levels of LDL cholesterol and total cholesterol and lower levels of HDL cholesterol with an increased risk of asthma.

Role of Sex Hormones at Different Physiobiological Conditions and Therapeutic Potential in MBD2 Mediated Severe Asthma

Sex hormone has become a “hot topic” to evaluate the hormonal therapeutic potential in severe asthma. Th17 cell is one of the main influencing factors involved in the pathogenesis of severe asthma, hence also called as kernel of severe asthma, and Th17 subtype of non-T2 asthma is less responsive (resistance) to inhaled corticosteroid (ICS), so severe in nature. Methyl-CpG binding domain protein 2 (MBD2) is overexpressed and regulates the Th17 differentiation, showing the possibility of therapeutic target in treating Th17 mediated severe asthma. Sex hormone fluctuates at the different physiobiological conditions of the human body and affects the asthma pathobiology showing its role in asthma prevalence, severity, remission, and therapy. This review briefly overviews the sex hormones, their influence in asthma at the different physiobiological conditions of human body, and MBD2 severe asthma connection with the possible therapeutic potential of sex steroids in MBD2 mediated Th17 predominant severe asthma. Male sex hormone tends to show a beneficial effect and possibly downregulates the expression of Th17 cells via regulating MBD2 through a mechanism distinct from corticosteroid treatment and guides us towards discovery of new therapeutic agent, reduces the asthma-related complications, and promotes long-term survival by lowering the risk of therapy-resistant issues of old age severe asthma.

Adult but not childhood onset asthma is associated with the metabolic syndrome, independent from body mass index

INTRODUCTION

Adult-onset asthma (AOA) is usually more severe compared to childhood onset asthma (CoA). Given the increasing evidence that AoA is associated with obesity, we investigated the relationship of other related metabolic comorbid conditions with AoA compared to CoA.

STUDY DESIGN AND METHODS

This cross-sectional study compared the metabolic syndrome and lipid derived inflammatory markers in patients with AoA, CoA and age- and sex-matched control subjects without asthma. Participants were asthma patients visiting the outpatient clinic of two teaching hospitals in Rotterdam, The Netherlands. All participants underwent lung function tests, blood tests and physical activity tracking. AoA was defined as asthma age of onset after the age of 18 years. Metabolic syndrome was defined according to the international joint interim statement criteria.

RESULTS

Eighty-one participants were included (27 AoA, 25 CoA, 29 controls). AoA was associated with the metabolic syndrome (Odds Ratio = 3.64 95% CI (1.16-11.42) p = 0.03, Nagelkerke R² = 0.26), adjusted for age, sex, body mass index and smoking habits. AoA patients had higher median serum IL-6 and leptin-adiponectin (LA) ratio compared to controls (IL-6 (pg/mL): 3.10 [1.11-4.30] vs. 1.13 [0.72-1.58], p = 0.002 and LA ratio (pg/mL): 6.21 [2.45-14.11] vs. 2.24 [0.67-4.71], p = 0.0390). This was not observed in CoA and controls.

CONCLUSION

AoA was associated with the metabolic syndrome and its related pro-inflammatory endocrine and cytokine status. This may suggest adipose tissue derived inflammatory markers play a role in the pathophysiology of AoA.

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

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

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

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

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

Predictors of a good response to inhaled corticosteroids in obesity-associated asthma

INTRODUCTION

Asthma in obese subjects is poorly understood. According to GINA guidelines, pulmonologists increase ICS in case of poor asthma control but lung volume restriction may also worsen respiratory symptoms in obese asthmatics leading to overtreatment in this subpopulation.

METHODS

We conducted a retrospective study on 1217 asthmatics recruited from University Hospital of Liege. 92 patients with a BMI ≥30 came at least two times at the asthma clinic (mean interval: 335 days). In this obese population, we identified predictors of good (decrease in ACQ ≥0.5) versus poor response (rise in ACQ ≥0.5) to ICS step-up therapy.

RESULTS

Obese asthmatics had a poorer asthma control and quality of life as compared to non-obese and exhibited reduced FVC, higher levels of blood leucocytes and markers of systemic inflammation. The proportion of asthma inflammatory phenotypes was similar to that observed in a general population of asthmatics. Among uncontrolled obese asthmatics receiving ICS step-up therapy, 53% improved their asthma control while 31% had a worsening of their asthma. Uncontrolled obese asthmatics showing a good response to increase in ICS had higher ACQ, lower CRP levels, higher sputum eosinophil counts and higher FeNO levels at visit 1. Uncontrolled obese asthmatics that worsened after increasing the dose of ICS had lower FVC, lower sputum eosinophil counts and higher sputum neutrophil counts.

CONCLUSION

We observed poorer asthma control in obese asthmatics despite similar bronchial inflammation. Managing obese asthmatics according to ACQ alone seems to underestimate asthma control and the contribution of restriction to dyspnea. Increasing the dose of ICS in the absence of sputum eosinophilic inflammation or in the presence of restriction or bronchial neutrophilia led to poorer asthma control. In those patients, management of obesity should be the first choice.

Evaluation of Interleukin-6, Leukotriene B-4, and Nitric Oxide Levels in Exhaled Breath Condensate of Asymptomatic Obese Individuals: Are Obese Patients Under Risk of Developing Asthma?

Objective

If systemic inflammation in relation with obesity causes asthma, the detection of increased airway inflammation among obese individuals who do not have any respiratory symptoms can be also beneficial in indentifying obese patients who are at risk of developing asthma. The aim of this study was to evaluate the systemic and airway inflammation of asymptomatic obese and non-obese individuals.

Materials and Methods

Obese and non-obese individuals with no respiratory symptoms were included. Inflammatory biomarkers such as C-reactive protein (CRP), exhaled breath condensate (EBC) interleukin-6 (IL-6), EBC leukotriene B-4 (LTB-4), and EBC nitric oxide (NO) levels of obese and non-obese individuals were determined.

Results

Forty-five obese individuals (body mass index [BMI]≥30) and 31 non-obese individuals (BMI≤25) as a control group were included in this study. The mean age of the obese group (38.7±11.4 years) was significantly higher than the one of the non-obese group (29.5±8.6 years; p<0.001). There was no significant relationship between gender and BMI (χ² =1.471, p=0.225). CRP levels were significantly higher in the obese group (6.94±8.28) than the non-obese group (3.29±0.39; p<0.001). The levels of EBC IL-6 in obese and non-obese group were found as 22.61±12.53 and 21.08±14.39, respectively (p=0.624). There was no significant difference between EBC NO levels of the obese group and non-obese group (24.35±10.9 vs. 21.56±7.83; p=0.226). No significant difference was found between the EBC LTB-4 level in the obese group and the non-obese group (36.39±89.82 vs. 16.64±17.45; p=0.231).

Conclusion

Increased systemic inflammation in obese individuals who had no respiratory symptoms might indicate the tendency of asthma. However, airway inflammation was not significantly different between groups. Therefore the relationship between obesity and asthma should be investigated in future large-scale studies determining the direct effects of adipokines on airways.

Functional state of the small airways in patients with bronchial asthma associated with obesity

AIM

To assess the functional status of the small Airways in patients with bronchial asthma associated with obesity, by body plethysmography.

MATERIALS AND METHODS

65 patients with bronchial asthma of mild severity, partially controlled course, including 30 patients with normal body weight and 35 patients with obesity of I degree were examined. Control group-30 healthy volunteers. Examined forced vital capacity (FVC), forced expiratory volume in first second (FEV1) ratio of FEV1 to FVC (FEV1/FVC), maximum volumetric exhalation rate after 25.50 and 75% FVC (MEF75, MEF50, MEF25), average flow velocity in the exhalation interval 25-75% of FVC (MMEF25-75). Method bodyplethysmography was evaluated in bronchial resistance, functional residual capacity (FRC), residual volume of the lungs (RV), total lung capacity (TLC), the percentage of RV/TLC.

RESULTS

Patients with bronchial asthma with obesity showed a reduction of indicators of bronchial obstruction: FEV1 of 14% (p=0.02), FEV1/FVC by 14% (p=0.001), MEF75 30% (p=0.001), MEF50 by 35% (p=0.001), MEF25 by 44% (p=0.003), MMEF25-75 by 38% (p=0.001). The increase of bronchial resistance on inhalation in 2 times (p=0.001), on exhalation in 3.3 times (p=0.003) was found, which is typical for generalized bronchial obstruction at the proximal level. An increase in RV by 24% (p=0.03), TLC - by 9% (p=0.03), RV/TLC - by 18% (p=0.03), indicating the presence of &quot;air traps&quot; and dysfunction of the small respiratory tract.

CONCLUSION

In patients with asthma of mild severity associated with obesity, both the central bronchis and the distal lung are affected, which are manifested by generalized bronchial obstruction, the formation of &quot;air traps&quot; and dysfunction of the small respiratory tract.

Association Between Vitamin D Metabolism Gene Polymorphisms and Risk of Tunisian Adults' Asthma

INTRODUCTION

Several studies have shown a strong correlation between the serum vitamin D level and asthma severity and deficits in lung function.

OBJECTIVE

Study the relationship between vitamin D and the severity of asthma by targeting five SNPs of vitamin D metabolism gene pathway in a Tunisian adult asthmatics population.

METHODS

Our case-control study includes 154 adult asthmatic patients and 154 healthy Tunisian subjects. We genotyped many variants in three human genes encoding key components of the vitamin D metabolism, CYP2R1, CYP27B1, GC. The GC gene rs4588 and rs7041 polymorphisms were analysed using the PCR-RFLP method, while rs10741657 and rs12794714 for CYP2R1 gene and rs10877012 of CYP27B1 gene were investigated using TaqMan PCR genotyping techniques.

RESULTS

We found that the presence of at least one copy of the rs12794714 A, allele was associated with lower risk of developing asthma (OR 0.61). Further, the rs12794714 is a protector factor against asthma severity (OR 0.5). However, the presence of rs10877012 TG genotype is a risk factor related to asthma severity (OR 1.89). When we classified the population according to sex, our results showed that rs10877012 TT genotype was a risk factor for women subjects (OR 6.7). Moreover, the expression of TT genotype was associated with a higher risk of asthma in non-smoker patients (OR 7.13). We found a significant lower VD serum levels in asthmatics than controls but no impact of the polymorphisms on VD levels.

CONCLUSIONS

We found that rs12794714 and rs10877012 SNPs were associated with asthma risk.

Association between lipid profile and the prevalence of asthma: a meta-analysis and systemic review

OBJECTIVE

To explore the association of asthma with serum levels of high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol, and triglyceride.

METHODS

PubMed, Cochrane, and Embase databases were systematically searched through November 2015 using the following search terms: dyslipidemia, HDL, LDL, triglyceride, cholesterol, and asthma. Eligible studies included randomized controlled trials (RCTs), retrospective, cohort, and cross-sectional studies. Sensitivity analysis and publication bias were performed.

RESULTS

Twenty studies were included in the analysis, with a total 32,604 patients (3,458 in the asthma group and 29,146 in the control group). The pooled analysis found that the mean difference between groups was significantly higher in the asthma group for levels of LDL (6.026 mg/dL, 95% CI = 2.696-9.356, p < .001) and total cholesterol (8.161 mg/dL, 95% CI = 3.006-13.316, p = .002) compared with the control group. No association was observed between asthma and control groups for levels of HDL (mean difference = -0.728, 95% CI = -3.146-1.691, p = .555) or triglycerides (mean difference = 1.436, 95% CI = -2.768-5.640, p = .503).

CONCLUSIONS

Levels of LDL and total cholesterol were higher in patients with asthma than non-asthmatic patients.

Gender aspects and influence of hormones on bronchial asthma - Secondary publication and update

There is good evidence for gender-specific differences in asthma regarding all affected areas, from intra- to extra-cellular mediators to the whole organ structure und functioning of the lung. These result from complex, in parts synergistic, in other parts opposing, effects - especially of female sex hormones, and rather protective effects of male hormones against asthma, which include effects on the cellular immune system. Additionally, there are gender differences of sociocultural origin, regarding presentation, doctor's diagnosis and treatment of asthma symptoms, as well as the undertaken coping strategies concerning the female or male patient's complaints. Taking into account gender-specific differences in asthma would contribute to improved individual diagnosis and therapies.

Neuropeptide Y associated with asthma in young adults

OBJECTIVE

Neuropeptide Y, a widely circulating neurotransmitter, plays a pivotal role in energy balance, immunomodulation and asthma, and several NPY polymorphisms are promising genetic risk factors for asthma and obesity. We explored the associations of candidate NPY gene polymorphisms with prevalent asthma and its relationship with obesity in young adult asthma patients free of other chronic medical morbidity.

METHODS

Five common gene variants of NPY (rs16147 (-399T/C), rs17149106 (-602G/T), rs16140 (+1000C/G), rs5573 (+1201A/G), rs5574 (+5327C/T)) previously validated to account for most of the NPY expression in vitro and in vivo were investigated in 126 physician-diagnosed asthma patients without other chronic medical morbidity and 182 healthy controls (21-35years). Plasma levels of NPY, adiponectin, and CRP were determined using ELISA, and IL-6 was measured by Luminex in a subgroup of 70 patients and 69 age- and sex-matched healthy controls.

RESULTS

In logistic regression models controlling for gender and obesity, the CT genotype of rs5574 (OR=0.54, 95%CI: 0.30-0.89) and the GT genotype of rs17149106 (OR=5.58, 95%CI: 1.09-28.54) were significantly associated with asthma. No significant interaction between NPY SNP polymorphisms and obesity were detected. Plasma NPY level was correlated with adiponectin levels (p<0.05). Compared with the healthy controls, patients with asthma had higher BMI (p<0.001), adiponectin (p<0.05), IL-6 (p=0.001) and CRP (p<0.001), and lower NPY levels (p<0.01).

CONCLUSIONS

The CT genotype of rs5574 and the GT genotype of rs17149106 are significantly associated with prevalent asthma.

Effect of Obesity on Acute Ozone-Induced Changes in Airway Function, Reactivity, and Inflammation in Adult Females

We previously observed greater ozone-induced lung function decrements in obese than non-obese women. Animal models suggest that obesity enhances ozone-induced airway reactivity and inflammation. In a controlled exposure study, we compared the acute effect of randomized 0.4ppm ozone and air exposures (2 h with intermittent light exercise) in obese (N = 20) (30<BMI<40Kg/m2) vs. non-obese (N = 20) (BMI<25Kg/m2) non-smoking 18–35 year old women. We measured spirometry and bronchial reactivity to inhaled methacholine (3h post-exposure). Inflammation and obesity markers were assessed in the blood (pre, 4h post, and 20h post exposures) and induced-sputum (4h post-exposures and on 24h pre-exposure training day, no exercise): measures of C reactive protein (CRP) (blood only), leptin (blood only), adiponectin, interleukins IL-6, IL-1b, and IL-8, and tumor necrosis factor alpha, and sputum cell differential cell counts. The pre- to post-exposure decrease in forced vital capacity after ozone (adjusted for the change after air exposure) was significantly greater in the obese group (12.5+/-7.5 vs. 8.0+/-5.8%, p<0.05). Post ozone exposure, 6 obese and 6 non-obese subjects responded to methacholine at ≤ 10mg/ml (the maximum dose); the degree of hyperresponsiveness was similar for the two groups. Both BMI groups showed similar and significant ozone-induced increases in sputum neutrophils. Plasma IL-6 was increased by exercise (4 hr post air exposure vs. pre) only in the obese but returned to pre-air exposure levels at 20hr post-exposure. Plasma IL-6 was significantly increased at 4hr post ozone exposure in both groups and returned to pre-exposure levels by 20h post-exposure. These results confirm our previous findings of greater post-ozone spirometric decrements in obese young women. However, acute ozone-induced airway reactivity to methacholine and airway inflammation did not differ by obesity at the exposure and exercise levels used.

Bronchospasm in obese patients undergoing elective laparoscopic surgery under general anesthesia

Background

Existing data suggest that obesity correlates with airway hyper-reactivity. However, the incidence of bronchospasm during bariatric surgery in obese patients has not been well studied.

Methods

This was a prospective observational study comparing 50 obese versus 50 non obese patients undergoing elective laparoscopic surgery over a 2 year period. Bronchospasm was detected clinically by auscultation and was confirmed by measuring peak airway pressure during mechanical ventilation. Blood gases were measured at predetermined time intervals intraoperatively. Categorical variables were analyzed using Fisher’s exact test, while numerical variables within and between groups were compared using repeated measures general linear model.

Results

The incidence of bronchospasm was significantly higher in obese compared to non obese patients (P = 0.027). Peak airway pressures and blood gases differed significantly when comparing non obese patients versus obese patients without bronchospasm versus obese patients with bronchospasm. Hypoventilation resulting in gradual increase of arterial PaCO₂ was noted in all groups during surgery.

Conclusion

The incidence of bronchospasm is higher in obese patients compared to non obese patients undergoing elective laparoscopic surgery. Airway pressures and blood gas values in obese patients are somewhere between values in non obese patients and values in patients with bronchospasm, thereby implying that obesity is associated with a state where bronchial smooth muscles are not fully relaxed. Consideration of increased airway reactivity in obese patients undergoing laparoscopic surgery is important for improved patient care and uneventful anesthetic course.

Obesity risk class and asthma outpatient service utilization by the middle aged and elderly in Taiwan

BACKGROUND

According to the estimates of the World Health Organization (WHO), there were about 300 million people in the world suffering from asthma in 2005. Among the risk factors of asthma is obesity, which was found to be significantly associated with asthma in recent decades.

OBJECTIVES

In this study, we analyze the relationship between obesity risk class and asthma outpatient service utilization by the middle-aged and elderly in Taiwan.

METHODS

Adopting data from the 2005 Nation Health Interview Survey (NHIS) and National Health Insurance Research Database (NHIRD), we first utilize latent class analysis (LCA) to identify obesity risk classes. Next, we utilize a logit and a negative binominal model to analyze the relationship between each obesity risk class and asthma outpatient service utilization.

RESULTS

Results indicate that compared with the "overweight/obese with low consumption of vegetable/fruit and little exercise" class, the classes "normal-weight with high consumption of vegetable/fruit and moderate exercise" and "overweight/obese with high consumption of vegetable/fruit and moderate exercise" tend to have low probabilities and less number of visits of utilizing asthma outpatient services.

CONCLUSIONS

Our results may constitute useful references for clinicians and government policy makers formulating strategies for asthma management and prevention. Better informed strategies for asthma management could, in turn, increase the efficiency of asthmatic patients' care, which could provide efficient assistance to the target group based on the obesity risk classes.

[Impact of obesity on response to therapy and pulmonary function in children with asthma]

OBJECTIVE

To investigate the effects of obesity on response to therapy and pulmonary function in children with asthma who receive inhaled corticosteroid (ICS) treatment.

METHODS

A total of 129 children with asthma were divided into two groups according to their body mass index: normal weight group (n=64) and obese group (n=65). The asthma control status and pulmonary function were compared between the two groups after one year of ICS treatment. The pulmonary function was expressed as percent forced expiratory volume in 1 second (FEV1%), percent predicted forced vital capacity (FVC%), peak expiratory flow (PEF), peak expiratory flow at 25% of vital capacity (PEF25), and peak expiratory flow at 50% of vital capacity (PEF50). The asthma control status was expressed as complete control rate, partial control rate, and uncontrolled rate. Sixty-eight healthy children were selected as the healthy control group.

RESULTS

There were significant differences in the indices of pulmonary function between the three groups before treatment (P<0.01); the healthy control group had the best values of pulmonary function, while the obese group had the worst values. After 1 year of treatment, the normal weight group showed significantly more improvements in FEV1% and FVC% than the obese group (P<0.01). However, there were no significant differences in improvements in PEF, PEF25, and PEF50 between the two groups. The complete control rate, partial control rate, and uncontrolled rate in the normal weight group were 72%, 19%, and 9%, respectively, while the rates in the obese group were 28%, 51%, and 22%, respectively; the normal weight group had a significantly better asthma control status than the obese group (P<0.01).

CONCLUSIONS

The asthmatic children with obesity have a significantly less improvement in large airway function and a poorer asthma control status after ICS treatment than those with the normal weight.

Prediction of basal metabolic rate in overweight/obese and non-obese subjects and its relation to pulmonary function tests

BACKGROUND

Few studies investigated the association between basal metabolic rate (BMR) and indicators of pulmonary function. This study was conducted to estimate BMR in overweight/obese and non-obese healthy subjects using four commonly used predictive equations and to investigate its relation to the indicators of lung function tests (LFT). A cross sectional study was conducted in Tabuk University, Tabuk, Saudi Arabia. A total of 201 students (98 males and 103 females) participated in the study. Four different values of BMR were calculated for each participant using four different predictive equations (Harris-Benedict, Mifflin, FAO/WHO/UNU and Henry-Rees). A portable All-flow spirometer (Clement Clarke International, Harlow, UK) was used for measurements of LFT.

RESULTS

Significantly higher values of spirometric indicators (p < 0.05) were found in males compared to females, except for FEF75 and FEF75-85. Mean BMR values predicted with the four equations were significantly higher in the males compared to the females and among the overweight/obese compared to the non-obese subjects (p < 0.05). The relation between mean BMR values and the indicators of LFT was statistically insignificant (p > 0.05).

CONCLUSION

Mean values of LFT indicators are not related to the estimated values of BMR. A practical calculation of BMR based on direct measurement of oxygen consumption is recommended to confirm the absence of this association.

Chitinase 3-like-1 regulates both visceral fat accumulation and asthma-like Th2 inflammation

RATIONALE

Obesity, especially truncal obesity, is a risk factor for asthma incidence, prevalence, and severity. Chitinase 3-like-1 (Chi3l1) is an evolutionarily conserved moiety that plays a critical role in antipathogen and Th2 responses. However, the mechanisms that underlie the association between asthma and obesity and the role(s) of Chi3l1 in fat accumulation have not been defined.

OBJECTIVES

To determine whether Chi3l1 is regulated by a high-fat diet (HFD) and simultaneously plays an important role(s) in the pathogenesis of asthma and obesity.

METHODS

We evaluated the regulation of Chi3l1 by an HFD and Th2 inflammation. We also used genetically modified mice to define the roles of Chi3l1 in white adipose tissue (WAT) accumulation and Th2 inflammation and blockers of sirtuin 1 (Sirt1) to define its roles in these responses. Finally, the human relevance of these findings was assessed with a case-control study involving obese and lean control subjects and those with asthma.

MEASUREMENTS AND MAIN RESULTS

These studies demonstrate that an HFD and aeroallergen challenge augment the expression of WAT and pulmonary Chi3l1. Chi3l1 also played a critical role in WAT accumulation and lung Th2 inflammation. In addition, Chi3l1 inhibited Sirt1 expression, and the deficient visceral fat and Th2 responses in Chi3l1 null mice were reversed by Sirt1 inhibition. Finally, serum and sputum Chi3l1 were positively associated with truncal adiposity, and serum Chi3l1 was associated with persistent asthma and low lung function in obese subjects with asthma.

CONCLUSIONS

Chi3l1 is induced by an HFD and Th2 inflammation, and simultaneously contributes to the genesis of obesity and asthma.

Asthma and metabolic syndrome: Current knowledge and future perspectives

Asthma and obesity are epidemiologically linked; however, similar relationships are also observed with other markers of the metabolic syndrome, such as insulin resistance and dyslipidemia, which cannot be accounted for by increased body mass alone. Obesity appears to be a predisposing factor for the asthma onset, both in adults and in children. In addition, obesity could make asthma more difficult to control and to treat. Although obesity may predispose to increased Th2 inflammation or tendency to atopy, other mechanisms need to be considered, such as those mediated by hyperglycaemia, hyperinsulinemia and dyslipidemia in the context of metabolic syndrome. The mechanisms underlying the association between asthma and metabolic syndrome are yet to be determined. In the past, these two conditions were believed to occur in the same individual without any pathogenetic link. However, the improvement in asthma symptoms following weight reduction indicates a causal relationship. The interplay between these two diseases is probably due to a bidirectional interaction. The purpose of this review is to describe the current knowledge about the possible link between metabolic syndrome and asthma, and explore potential application for future studies and strategic approaches.

Piecewise Mixed Effects Model to Compare the Weight-gain Patter ns Before and After Diagnosis of Asthma in Children Younger than 5 Years

Asthma and obesity are two significant public health problems that both originate in early childhood and have shared risk factors and manifestations. Studies suggest a strong association between asthma development and subsequent accelerated weight gain. Children are diagnosed with asthma in early childhood and are often exposed to factors associated with rapid weight gain. This article intends to demonstrate an innovative application of the piecewise mixed effects model to characterize the difference in the temporal rate of change in BMIz, the standardized scores of body mass index and weight-for-length that measure weight status, before and after asthma diagnosis in children younger than 5 years. The data consist of unique sequences from 1194 children's clinic visits during the first 5 years of life. We used a knot at the time of diagnosis and detected a differential weight-gain pattern before and after asthma diagnosis. The pre- and post-asthma-diagnosis weight-gain patterns further differ by sex and race-ethnicity. After asthma diagnosis, female children showed a higher increase in the rate of change in BMIz than males. Non-Hispanic African Americans and Hispanics had higher post-diagnosis rates of change in BMIz than Caucasians. The differential weight-gain patterns between male and female children were mainly contributed by Caucasian children. These findings could have important implications in the clinical care of children after asthma diagnosis.

Metabolic asthma: is there a link between obesity, diabetes, and asthma?

Childhood asthma and obesity have reached epidemic proportions worldwide, and the latter is also contributing to increasing rates of related metabolic disorders, such as diabetes. However, the relationship between asthma, obesity, and abnormal metabolism is not well understood nor has it been adequately explored in children. This article discusses the concept of metabolic asthma and the recent hypothesis that early derangement in lipid and glucose metabolism is independently associated with increased risk for asthma.

Investigating the association between obesity and asthma in 6- to 8-year-old Saudi children: a matched case-control study

BACKGROUND

Previous studies have demonstrated an association between obesity and asthma, but there remains considerable uncertainty about whether this reflects an underlying causal relationship.

AIMS

To investigate the association between obesity and asthma in pre-pubertal children and to investigate the roles of airway obstruction and atopy as possible causal mechanisms.

METHODS

We conducted an age- and sex-matched case-control study of 1,264 6- to 8-year-old schoolchildren with and without asthma recruited from 37 randomly selected schools in Madinah, Saudi Arabia. The body mass index (BMI), waist circumference and skin fold thickness of the 632 children with asthma were compared with those of the 632 control children without asthma. Associations between obesity and asthma, adjusted for other potential risk factors, were assessed separately in boys and girls using conditional logistic regression analysis. The possible mediating roles of atopy and airway obstruction were studied by investigating the impact of incorporating data on sensitisation to common aeroallergens and measurements of lung function.

RESULTS

BMI was associated with asthma in boys (odds ratio (OR)=1.14, 95% confidence interval (CI), 1.08-1.20; adjusted OR=1.11, 95% CI, 1.03-1.19) and girls (OR=1.37, 95% CI, 1.26-1.50; adjusted OR=1.38, 95% CI, 1.23-1.56). Adjusting for forced expiratory volume in 1 s had a negligible impact on these associations, but these were attenuated following adjustment for allergic sensitisation, particularly in girls (girls: OR=1.25; 95% CI, 0.96-1.60; boys: OR=1.09, 95% CI, 0.99-1.19).

CONCLUSIONS

BMI is associated with asthma in pre-pubertal Saudi boys and girls; this effect does not appear to be mediated through respiratory obstruction, but in girls this may at least partially be mediated through increased risk of allergic sensitisation.

Body mass index and comorbidities in adult severe asthmatics

Both severe asthma and obesity are growing health problems. Severe asthma leads to a poor quality of life. The relationship among BMI, comorbidities, and severe asthma control in adults is still unclear. The aim of the study is to better understand the effect of the comorbidities as atopy, type II diabetes, OSAS, gastroesophageal reflux, hypertension, cardiovascular diseases, osteoporosis, infections, and psychological factors with BMI on asthma control in a cohort of adult severe asthmatics. One hundred and two patients were enrolled in a cross-sectional study assessing asthma control, treatments, pulmonary function, inflammatory markers, and comorbidities. Patients were divided into 3 classes according to BMI: normal weight, overweight, and obese. We found that the optimal state of asthma control is lower. whereas the score of Asthma Control Questionnaire, the number of asthma exacerbations during last year, the oral corticosteroids requirement during the previous year, and the LABA treatments are higher in obese than in overweight and normal weight severe asthmatics. The number of subjects with type II diabetes and OSAS are higher among obese and overweight patients than in normal weight asthmatics. In conclusion, BMI represents per se a factor for the deterioration in disease control in severe asthma.

Obesity--a risk factor for asthma, but not for atopic dermatitis, allergic rhinitis and sensitization

OBJECTIVE

To analyse the relationship between obesity and overweight and the prevalence of allergic diseases and sensitization, and the impact of gender and place of residence.

DESIGN

Questionnaire based on those used in ISAAC (International Study of Asthma and Allergies in Childhood) and ECRHS (European Community Respiratory Health Survey).

SETTING

Our study involved populations of the eight largest cities and one rural region in Poland (each with over 150,000 inhabitants).

SUBJECTS

The study included 18,617 participants (24·2% aged 6-7 years, 25·4% aged 13-14 years, 50·4% adults aged 20-44 years) in eight cities and one rural area. The out-patient study involved 4783 patients (25·7%); we performed skin prick testing with fifteen aeroallergens.

RESULTS

Overweight was found in 16·13% of participants (9·11% of 6-7-year-olds, 4·90% of 13-14-year-olds and 25·61% of adults), obesity in 6·41% (7·16%, 2·45% and 8·36%, respectively). In adults, overweight (OR=1·34) and obesity (OR=1·80) increased the prevalence of asthma, especially in women (OR=1·53, OR=2·01). Among 13-14-year-olds the prevalence was higher only in the obese (OR=1·76). Overweight (OR=1·99) and obesity (OR=2·17) affected the incidence of doctor-diagnosed asthma in 6-7-year-olds. Overweight (OR=0·81) and obesity (OR=0·76) reduced the prevalence of allergic rhinitis in men. There was no relationship between BMI and asthma in people from rural areas. Obesity and overweight did not affect the frequency of sensitization to aeroallergens.

CONCLUSIONS

Overweight and obesity increased the prevalence of symptomatic asthma in adults, especially in women. In 13-14-year-olds, only obesity increased the prevalence of asthma. In children, overweight was associated with increased prevalence of clinically diagnosed and declared asthma and a trend towards atopy. Higher BMI was negatively associated with the prevalence of allergic rhinitis in overweight and obese man. There was no correlation between BMI and sensitization to aeroallergens.

Asthma and obesity

The prevalence and incidence of asthma have increased among obese children and adults, particularly among women. Obesity seems to be a predisposing factor for the development of asthma, but the underlying mechanisms of its influence are still uncertain. Various hypotheses have been proposed to explain the link between obesity and asthma such as a common genetic predisposition, developmental changes, altered lung mechanics, the presence of a systemic inflammatory process, and an increased prevalence of associated comorbid conditions. Over-diagnosis of asthma does not seem to be more frequent in obese compared to non-obese subjects, but the added effects of obesity on respiratory symptoms can affect asthma control assessment. Obesity can make asthma more difficult to control and is associated with a reduced beneficial effect of asthma medications. This could be due to a change in asthma phenotype, particularly evidenced as a less eosinophilic type of airway inflammation combined to the added effects of changes in lung mechanics. Weight loss is associated with a universal improvement of asthma and should be part of asthma management in the obese patient. Additional research should be conducted to better determine how obesity influences the development and clinical expression of asthma, establish the optimal management of asthma in this population and determine how obesity affects long-term asthma outcomes in these patients.

Association of general and central obesity and atopic and nonatopic asthma in US adults

OBJECTIVE

To examine the association of body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) with the prevalence of asthma by atopic status and sex using nationally representative data in the US.

METHODS

The National Health and Nutrition Examination Survey 2005-2006 data were analyzed using areas under the receiver operating characteristic (ROC) curves (AUCs) and multivariate logistic regression models.

RESULTS

Women had higher AUCs (0.59-0.64) than men (0.50-0.58) across anthropometric indices and asthma outcomes. After controlling for sociodemographic characteristics and smoking status, only WHtR was positively associated with atopic asthma in both sexes (odds ratio per 1 SD [95% confidence interval]: men, 1.018 [1.004, 1.032], p = .01; women, 1.018 [1.006, 1.030], p = .003), and the associations persisted after further adjustment of BMI. Only in women was nonatopic asthma significantly associated with every 1 SD increase of BMI (odds ratio [95% confidence interval]: 1.018 [1.006, 1.030], p = .003), WC (1.018 [1.006, 1.030], p = .004), and WHtR (1.016 [1.004, 1.028], p = .008).

CONCLUSIONS

Using US national data, this study adds to the emerging evidence suggesting two possible distinct phenotypes: (1) obese men and women with atopic asthma and (2) obese women with nonatopic asthma. The mechanistic and therapeutic implications of these findings warrant further investigation.

Association of Age at Menarche and Menstrual Characteristics with Adult Onset Asthma among Reproductive Age Women

BACKGROUND

Observations of increasing asthma incidence, decreasing age at menarche, and common risk factors have led investigators to hypothesize potential associations of age at menarche or menstrual characteristics with incidence of adult onset asthma. We evaluated these associations among reproductive age women.

METHODS

Study participants were selected from among women enrolled in a pregnancy cohort study. Information on age at menarche, menstrual characteristics, and history of asthma was collected using interviewer-administered questionnaires. Adult onset asthma was defined as asthma first diagnosed after onset of menarche. Women who had no information on asthma and menstrual history and those who were diagnosed with asthma before menarche were excluded. A total of 3,461 women comprised the analytic population. Logistic regression was used to estimate adjusted relative risk (aRR) and 95% confidence intervals (95% CI) relating age at menarche and menstrual characteristics with adult onset asthma.

RESULTS

Mean age at menarche was 12.8 years (standard deviation=1.46). Among study participants, 7.5% were diagnosed with asthma after the onset of menarche. After controlling for potential confounders (age, race, body mass index, and socio-economic status), women who had early menarche (<12 years old) had 60% higher risk of being diagnosed with adult onset asthma as compared with women who did not have early menarche (≥ 12 years old) (aRR= 1.59, 95% CI 1.19 - 2.13). Menstrual irregularities or abnormal (short or long) cycle length were not associated with risk of adult onset asthma. In addition, no significant interaction was observed between age at menarche or menstrual characteristics with body mass index or physical activity (in adolescence) in relation to adult onset asthma.

CONCLUSION

Early menarche is associated with a higher risk of developing adult onset asthma among reproductive age women. Mechanisms for this association are potential areas of future research.

Obesity, Nutrition, and Asthma in Children

Obesity rates have increased dramatically among children in many parts of the world, especially in North America and several other English-speaking countries. The impact of obesity on pediatric health has become a major prevention initiative by the Obama administration and several public health organizations. Children with obesity are at increased risk for developing asthma, which is already one of the most common chronic diseases among children. The cause underlying obesity's impact on asthma risk is unknown. Commonly cited potential etiologies include airway smooth muscle dysfunction from thoracic restriction, obesity-related circulating inflammation priming the lung, and obesity-related comorbidities mediating asthma symptom development. Each of these theories does not fit precisely with all of the data that have accumulated over the last decade. In this review, I will explore other possible causes including: (1) dietary characteristics common in Westernized countries that might lead to both obesity and asthma; (2) reductions in physical activity; and (3) genetic alterations that increase the propensity to both obesity and asthma together. Next, I will review the current data on how obesity affects common characteristics of asthma such as airway inflammation, lung function, risk of exacerbation, atopy, and response to treatment. Obesity in children with asthma appears to be associated with greater airflow obstruction and a mildly diminished response to inhaled corticosteroids. Little objective evidence in children suggests that obesity significantly heightens the risk of exacerbation or worsens disease stability in children. Lastly, I will discuss the current literature that suggests that obese children with asthma generally should receive the same guidelines-based management as lean children. However, interventions that encourage daily physical activity, weight-loss, normalization of nutrient levels, and monitoring of common obesity-related sequelae should be considered by healthcare providers managing obese children with difficult-to-control asthma.

Emerging role of mast cells and macrophages in cardiovascular and metabolic diseases

Mast cells are essential in allergic immune responses. Recent discoveries have revealed their direct participation in cardiovascular diseases and metabolic disorders. Although more sophisticated mechanisms are still unknown, data from animal studies suggest that mast cells act similarly to macrophages and other inflammatory cells and contribute to human diseases through cell-cell interactions and the release of proinflammatory cytokines, chemokines, and proteases to induce inflammatory cell recruitment, cell apoptosis, angiogenesis, and matrix protein remodeling. Reduced cardiovascular complications and improved metabolic symptoms in animals receiving over-the-counter antiallergy medications that stabilize mast cells open another era of mast cell biology and bring new hope to human patients suffering from these conditions.

Prevalence and severity of asthma in obese adult candidates for bariatric surgery

OBJECTIVE

To determine the prevalence of asthma in a group of obese adult candidates for bariatric surgery and to evaluate the severity of asthma in this group of patients.

METHODS

This was a cross-sectional study involving 363 obese adults (body mass index > 35 kg/m²) evaluated by a pulmonologist, using clinical evaluation as a diagnostic tool for asthma. All patients underwent clinical evaluation and spirometry and were divided into two groups (asthma and control). The patients with asthma were stratified by the severity of asthma.

RESULTS

The prevalence of asthma in the obese population studied was 18.5% (95% CI: 14.5-22.4). That prevalence was 20.4% (95% CI: 16.2-24.5) and 13.7% (95% CI: 10.1-17.2) in the women and the men, respectively. Asthma symptoms in the last twelve months were present in 8.0% (95% CI: 5.2-10.7), and the initial manifestation of asthma symptoms occurred during childhood/adolescence in 17.4% (95% CI: 13.5-21.3). In the asthma group, intermittent asthma was present in 29 patients (43.3%), mild persistent asthma in 7 (10.4%), moderate asthma in 25 patients (37.3%), and severe persistent asthma in 6 (9.0%).

CONCLUSIONS

Using clinical evaluation as the diagnostic criterion, we found the prevalence of asthma to be high in this group of obese adults. Asthma was more common in females, and the initial manifestation of asthma symptoms more commonly occurred during childhood/adolescence. The severity of asthma in this group of obese adults was within the range of mean values predicted for the general population. Intermittent asthma, mild persistent asthma, and moderate persistent asthma predominated.

Per capita sugar consumption is associated with severe childhood asthma: an ecological study of 53 countries

AIMS

To examine the ecological association between population asthma symptom prevalence in six to seven year-old children and per capita sugar consumption seven years earlier (during the perinatal period).

METHODS

The asthma data (from the International Study of Asthma and Allergies in Childhood [ISAAC] study) were collected between 1999 and 2004 from 53 countries, and per capita sugar consumption data (seven years before the asthma prevalence) were extracted from United Nations Food and Agriculture (UNFAO) food balance sheets. Linear regression and Spearman's rank coefficient were used to evaluate the relationship between exposure and disease outcome.

RESULTS

Per capita sugar consumption varied more than six fold-between countries. A log-linear relationship was found between severe asthma symptoms (%) and per capita added sugar consumption in kg/capita/year (exponentiated beta coefficient 1.020; 95% CI 1.005 to 1.034; P = 0.012). Spearman's rank correlation coefficient was 0.34 (P= 0.015), which indicates moderate correlation.

CONCLUSIONS

We have demonstrated an ecological association between sugar consumption during the perinatal period and subsequent risk of severe asthma symptoms in six and seven year-olds.

Leptin is inversely associated with lung function in African Americans, independent of adiposity: the Jackson Heart Study

Leptin, a 16-kDa protein, has proinflammatory properties and has been linked to respiratory physiological responses in majority white populations. Little is known, however, about the relationship of leptin with lung function in nonwhites. Cross-sectional associations of circulating serum leptin concentrations with forced expiratory volume in 1 s (FEV(1)), FEV in 6 s (FEV(6)), and vital capacity (FVC), assessed by spirometry, were examined in 4,679 African-American men and women participants (54.3 ± 12.4 years; 62.7% women) in the Jackson Heart Study (JHS). The independent association of leptin was examined in relation to FEV(1), FEV(6), and FVC% predicted after adjustment for age, education, smoking status, pack-years of cigarette smoking, respiratory medication use, and menopausal status in women; additional adjustment included total body weight, waist circumference, and BMI. Serum leptin was inversely related to FEV(1), FEV(6), and FVC% predicted values in men. A dose-response relationship was observed with men in the highest leptin quartile having a significantly lower lung function compared to men in the lower leptin quartile. BMI significantly modified this relationship in women: leptin was most consistently associated with lung function in obese women, less consistent in overweight women, and absent in normal-weight women. Serum leptin concentration was strongly, inversely, and independently associated with lung function in African Americans, especially African-American men and obese women.

Systemic inflammation and reduced pulmonary function in chronic spinal cord injury

OBJECTIVE

To evaluate the relationship between systemic inflammation and pulmonary function in persons with chronic spinal cord injury (SCI).

DESIGN

Cross-sectional study.

SETTING

Veterans Affairs Medical Center.

PARTICIPANTS

Fifty-nine men with chronic SCI participating in a prior epidemiologic study.

METHODS

Standardized assessment of pulmonary function and measurement of plasma C-reactive protein (CRP) and interleukin-6 (IL-6).

MAIN OUTCOME MEASUREMENTS

Forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC).

RESULTS

Persons with the highest values of IL-6 had the lowest %-predicted FEV(1) and FVC. There was a significant inverse linear trend between quartile of IL-6 and %-predicted FEV(1) (P < .001) and FVC (P < .006), unadjusted and adjusted for SCI level and completeness of injury, obstructive lung disease history, smoking, and body mass index (P = .010-.039). Although not as strong as for IL-6, there also were similar trends for %-predicted FEV(1) and FVC with CRP.

CONCLUSIONS

In chronic SCI, higher levels of IL-6 and CRP were associated with a lower FEV(1) and FVC, independent of level and completeness of injury. These results suggest that the reduction of pulmonary function after SCI is related not only to neuromuscular impairment but also to factors that promote systemic inflammation.

Metabolic abnormalities in children with asthma

RATIONALE

Childhood asthma and obesity have reached epidemic proportions worldwide, and the latter is also contributing to increasing rates of related metabolic disorders, such as diabetes. Yet, the relationship between asthma, obesity, and abnormal lipid and glucose metabolism is not well understood, nor has it been adequately explored in children.

OBJECTIVES

To analyze the relationship between asthma diagnosis and body mass in children across the entire range of weight percentile categories, and to test the hypothesis that early derangement in lipid and glucose metabolism is independently associated with increased risk for asthma.

METHODS

Cross-sectional analysis of a representative sample of public school children from a statewide community-based screening program, including a total of 17,994 children, 4 to 12 years old, living in predominantly rural West Virginia, and enrolled in kindergarten, second, or fifth grade classrooms.

MEASUREMENTS AND MAIN RESULTS

We analyzed demographics; family history; smoke exposure; parent-reported asthma diagnosis; body mass index; evidence of acanthosis nigricans as a marker for developing insulin resistance; and fasting serum lipid profile including total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. Regardless of their body mass index percentile, children diagnosed with asthma were more likely than children without asthma to have higher triglyceride levels and acanthosis nigricans after controlling for sex differences and smoke exposure.

CONCLUSIONS

This study provides the first set of community-based data linking asthma, body mass, and metabolic variables in children. In particular, these findings uniquely describe a statistically significant association between asthma and abnormal lipid and glucose metabolism beyond body mass index associations.

Obesity and poor asthma control in patients with severe asthma

BACKGROUND

Asthma is a public health problem as it leads to hospitalization and eventual death, particularly in its severe forms. Many studies have demonstrated an association between obesity and asthma.

OBJECTIVE

The aim of this study was to investigate the relationship between obesity and asthma control in a group of patients at a reference center for severe asthma in Brazil.

METHODS

This cross-sectional study was conducted in the outpatient central reference clinic of the Program for Control of Asthma in the State of Bahia. It included 508 subjects with severe asthma of both genders and above 18 years of age. All the participants answered a sociodemographic and a clinical questionnaire to collect information on their asthma and comorbidities, such as rhinitis and gastro-esophageal reflux disease (GERD). Participants also completed the Asthma Control Questionnaire, performed a spirometry test, and had their weight, height, and waist and hip circumferences registered.

RESULTS

Logistic regression analysis demonstrated a positive association between body mass index (BMI) and uncontrolled asthma [odds ratio (OR) 1.5; 95% confidence interval (CI) 1.02-2.20]. Symptoms of chronic rhinitis and GERD were also significantly associated with uncontrolled asthma (OR 3.68, 95% CI 1.50-9.01; and OR 2.78, 95% CI 1.91-4.03, respectively). There was no correlation between waist-to-hip ratios and asthma control.

CONCLUSION

In our sample of patients with severe asthma, those who were obese were more likely to have uncontrolled asthma than patients with a normal BMI. Nevertheless, this is not conclusive evidence for a direct causal association between obesity and poor asthma control. Future studies are necessary to dissect the relationship between obesity and asthma outcomes.

Influence of obesity on control in asthmatic Japanese patients defined by the Japanese definition of obesity

BACKGROUND Despite the use of inhaled corticosteroid (ICS) becoming increasingly widespread, many problems related to asthma management still need to be addressed. One of them, obesity, has been reported to exert a harmful influence on asthma control. However, there have been few reports focusing not only on both obesity and its influence on Japanese asthma patients but also on the Japanese definition of obesity, as defined by the Japan Society for the Study of Obesity (JASSO). AIMS & METHODS The aim of this study was to confirm the influence of obesity, as defined by the JASSO, on asthma management in Japanese asthmatic patients. Using data from the Niigata Asthma Treatment Study Group 2008 questionnaire survey, differences between the "normal" group (18.5 kg/m(2) ≤ BMI <25 kg/m(2)) and the "obese" group (25 kg/m(2) ≤ BMI) were analyzed. RESULTS There was a significantly lower step 1 rate (19.4% v.s. 26.8%) and a higher proportion of patients using inhaled salmeterol (43.6% v.s. 35.8%) and leukotriene receptor antagonist (49.8% v.s. 40.8%) in the obese group relative to the normal group, although there were no significant differences in indicators of asthma control, including asthma control test scores. CONCLUSION This study investigated influences of JASSO-defined obesity on asthma severity and management in a clinical setting in Japan. It is possible that there are strong interactions between asthma and obesity, such as obesity causing decreased ICS therapy efficacy and leukotriene (LT)-related inflammation, although further investigation is necessary.

The role of leptin in the respiratory system: an overview

Since its cloning in 1994, leptin has emerged in the literature as a pleiotropic hormone whose actions extend from immune system homeostasis to reproduction and angiogenesis. Recent investigations have identified the lung as a leptin responsive and producing organ, while extensive research has been published concerning the role of leptin in the respiratory system. Animal studies have provided evidence indicating that leptin is a stimulant of ventilation, whereas researchers have proposed an important role for leptin in lung maturation and development. Studies further suggest a significant impact of leptin on specific respiratory diseases, including obstructive sleep apnoea-hypopnoea syndrome, asthma, COPD and lung cancer. However, as new investigations are under way, the picture is becoming more complex. The scope of this review is to decode the existing data concerning the actions of leptin in the lung and provide a detailed description of leptin's involvement in the most common disorders of the respiratory system.

[The role of respiratory physiotherapy in the lung function of obese patients undergoing bariatric surgery. A review]

INTRODUCTION

Obesity, considered a new worldwide epidemic, is characterised by excess adipose tissue and contributes to a series of chronic diseases and increased mortality. Obesity associated to surgical procedure in these patients makes respiratory physiotherapy a must to recover lung function and prevent postoperative pulmonary complications.

AIMS

To assess the effects of respiratory physiotherapy on the lung function of obese patients undergoing weight loss surgery.

MATERIAL AND METHODS

We conducted a literature review October 2008-June 2009 of data which had been published over the last thirty years and which was available on the Medline, Pubmed ans Scielo databases.

CONCLUSION

Pre- and postoperative respiratory physiotherapy is vital for patients undergoing weight loss surgery irrespective of technique used, as it can prevent pulmonary complications inherent in the surgical procedure and aid lung function recovery.

Lean mass predicts asthma better than fat mass among females

The obesity phenotype associated with asthma is not known. Our objective was to define the relative contribution of various distributions of fat and lean mass to asthma prevalence. Data were obtained from 2,525 participants (including 1,422 females) who underwent dual-energy X-ray absorptiometry (DEXA) at the year 20 examination in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort. Total, truncal, arm and leg distributions of fat and lean mass were adjusted to the person's height. Self-reported asthma was the outcome. Asthma among females was associated with greater total fat mass, arm fat mass, total lean mass, truncal lean mass and arm lean mass. Among males, none of these mass measures were significantly associated with asthma. Among females, the association with asthma was stronger for total lean mass than for total fat mass. Further, among various regional distributions of lean and fat mass in females, truncal lean mass was the strongest predictor. Total lean mass is more strongly associated with asthma than total fat mass among females. These findings are contrary to the popular perception that excess physiological fat drives the obesity-asthma association. Rather, we hypothesise that ectopic fat within the "lean" tissues drives this association among females.

Respiratory medication prescriptions before and after bariatric surgery

BACKGROUND

Increased body mass index is associated with asthma and frequent respiratory complaints. Bariatric surgery often results in rapid weight loss associated with an improved respiratory status.

OBJECTIVE

To assess whether patients undergoing bariatric surgery would have fewer respiratory symptoms after surgery as evidenced by decreases in respiratory prescription drug claims.

METHODS

A retrospective cohort of 320 patients continuously enrolled in a large, southeast Michigan health maintenance organization were studied for 1 year before and 1 year after bariatric surgery. The health maintenance organization claims database was used to compare respiratory prescriptions filled before and after surgery. Respiratory medications included bronchodilator inhalers, inhaled corticosteroids, oral corticosteroids, theophylline, and leukotriene antagonists.

RESULTS

Of 320 surgical patients, 64 (20%) filled at least 1 respiratory medication prescription for a total of 468 prescriptions during the 2-year observation period. Of the prescriptions filled, 35% were beta-agonists, 38% inhaled corticosteroids, 12% oral corticosteroids, 15% leukotriene antagonists, and less than 1% theophylline. Total respiratory medication prescription fills decreased by 49% (from 314 to 154 prescriptions) in the postsurgical year, with only 43.1% of patients filling prescriptions in the year before surgery also filling a prescription in the postsurgical surveillance period. Analyses restricted to 40 patients with physician-diagnosed asthma revealed mean (SD) presurgical prescription fills of 7.0 (6.9) per year, decreasing to 3.8 (6.1) per year in the postsurgical year (P = .002).

CONCLUSION

Respiratory medication use decreases significantly after bariatric surgery. A secondary benefit of bariatric surgery may include a decrease in respiratory symptoms and concomitant medication use.

Mild asthma in overweight women: A new phenotype?

BACKGROUND

Epidemics of asthma and overweight have been linked recently. They might be associated with systemic inflammation. In asthma hyperresponsiveness to adenosine (AMP) is more closely related to inflammation than to methacholine (MCh). The aim of the study was to determine responsiveness to AMP and MCh in overweight compared with normal weight asthmatics.

METHODS

Thirty women were enrolled (19 overweight) with mild controlled asthma according to GINA. A Body Mass Index (BMI) less than 25kg/m(2) was considered as normal and a BMI above 25kg/m(2) as overweight. We assessed the recent control of asthma (ACQ), pulmonary function tests, bronchial responsiveness to MCh and AMP (PC(20) and O'Connor two-point dose-response slope), perception of symptoms (Borg scale), and blood inflammatory markers (leptin and hs-CRP by ELISA).

RESULTS

Overweight had a significant lower dose-response slope of the MCh challenge (p=0.009) as compared to normal weight patients, whereas no significant difference was observed for AMP challenge (p=0.27). Overweight patients had higher intercepts of the Borg scale measured before the MCh and AMP challenge tests (p=0.01 and p=0.03). Plasma leptin (p=0.001) and hs-CRP (p=0.05) concentrations were higher in overweight than normal weight patients. There was no correlation between challenges and inflammatory markers.

CONCLUSIONS

Overweight asthmatic women have more pronounced systemic inflammation, but are less responsive to MCh. AMP responsiveness appeared to be comparable between both groups. Our findings suggest that overweight asthmatic women do not feature increased airway inflammation, but do represent a distinct phenotype as compared to normal weight patients.

Asthma in Black African, Black Caribbean and South Asian adolescents in the MRC DASH study: a cross sectional analysis

Background

Ethnic differences in the prevalence of asthma among children in the UK are under-researched. We aimed to determine the ethnic differences in the prevalence of asthma and atopic asthma in children from the main UK ethnic groups, and whether differences are associated with differential distributions in social and psychosocial risk factors.

Methods

6,643 pupils aged 11-13 years, 80% ethnic minorities. Outcomes were asthma/wheeze with (atopic) and without hay fever/eczema. Risk factors examined were family history of asthma, length of residence in the UK, socioeconomic disadvantage, tobacco exposure, psychological well-being, and body mass index (BMI).

Results

There was a pattern of lower prevalence of asthma in Black African boys and girls, and Indian and Bangladeshi girls compared to White UK. The overall prevalence was higher in Mixed Black Caribbean/White boys, with more atopic asthma in Black Caribbean boys and Mixed Black Caribbean/White boys due to more hayfever. Poor psychological well-being and family history of asthma were associated with an increased risk of asthma within each ethnic group. UK residence for ≤ 5 years was protective for Black Caribbeans and Black Africans. Increased BMI was associated with an increased reporting of asthma for Black Africans. Adjustments for all variables did not remove the excess asthma reported by Black Caribbean boys (atopic) or Mixed Black Caribbean/White boys.

Conclusion

The protective effect of being born abroad accounted for ethnic differences in some groups, signalling a role for socio-environmental factors in patterning ethnic differences in asthma in adolescence.

The Breathe Easier through Weight Loss Lifestyle (BE WELL) Intervention: a randomized controlled trial

BACKGROUND

Obesity and asthma have reached epidemic proportions in the US. Their concurrent rise over the last 30 years suggests that they may be connected. Numerous observational studies support a temporally-correct, dose-response relationship between body mass index (BMI) and incident asthma. Weight loss, either induced by surgery or caloric restriction, has been reported to improve asthma symptoms and lung function. Due to methodological shortcomings of previous studies, however, well-controlled trials are needed to investigate the efficacy of weight loss strategies to improve asthma control in obese individuals.

METHODS/DESIGN

BE WELL is a 2-arm parallel randomized clinical trial (RCT) of the efficacy of an evidence-based, comprehensive, behavioral weight loss intervention, focusing on diet, physical activity, and behavioral therapy, as adjunct therapy to usual care in the management of asthma in obese adults. Trial participants (n = 324) are patients aged 18 to 70 years who have suboptimally controlled, persistent asthma, BMI between 30.0 and 44.9 kg/m2, and who do not have serious comorbidities (e.g., diabetes, heart disease, stroke). The 12-month weight loss intervention to be studied is based on the principles of the highly successful Diabetes Prevention Program lifestyle intervention. Intervention participants will attend 13 weekly group sessions over a four-month period, followed by two monthly individual sessions, and will then receive individualized counseling primarily by phone, at least bi-monthly, for the remainder of the intervention. Follow-up assessment will occur at six and 12 months. The primary outcome variable is the overall score on the Juniper Asthma Control Questionnaire measured at 12 months. Secondary outcomes include lung function, asthma-specific and general quality of life, asthma medication use, asthma-related and total health care utilization. Potential mediators (e.g., weight loss and change in physical activity level and nutrient intake) and moderators (e.g., socio-demographic characteristics and comorbidities) of the intervention effects also will be examined.

DISCUSSION

This RCT holds considerable potential for illuminating the nature of the obesity-asthma relationship and advancing current guidelines for treating obese adults with asthma, which may lead to reduced morbidity and mortality related to the comorbidity of the two disorders.

TRIAL REGISTRATION

NCT00901095.

Obesity induced bronchopulmonary hyperresponsiveness in Tunisian women

OBJECTIVE

The specific objective of this investigation was to determine whether bronchopulmonary responsiveness (BPR) to methacholine (MCH) was associated with the body mass index (BMI) of Tunisian women.

SUBJECTS

In all, 160 healthy nonsmoker women (52 lean, 45 overweight and 63 obese) were recruited and examined in the Clinical Laboratory of Physiology located in the Medical School of Sousse. The average ages (+/-s.e.) of the three categories of lean, overweight and obese subjects were 27.7+/-1.1, 33.2+/-1.7 and 37.5+/-1.3 years, respectively. Their corresponding mean BMIs (+/-s.e.) were 21.9+/-0.3, 27.7+/-0.2 and 36.5+/-0.8 kg m(-2), respectively.

MEASUREMENTS

Before their inclusion into the study, subjects were screened for their lung status by measuring their pulmonary function testing parameters using a whole body plethysmograph. BPR was assessed, using a cumulative concentration response curve technique, by measuring with a spirometer the decrease in forced expiratory volume in 1 s (FEV(1)) in response to a cumulative dose of MCH.

RESULTS

After adjusting for age, significant differences in both FEV(1) and forced vital capacity (VC) were found between the obese and lean groups (P<0.01), as well as between the obese and overweight groups (P<0.01). In addition, forced expiratory flow between 25 and 75% of VC was significantly different between the obese and lean groups (P<0.001), as well as between the lean and overweight groups (P=0.015). The mean maximum fall of FEV(1) in response to MCH challenge was significantly higher for the obese group (12.0%) than for the overweight (9.8%) or the lean (6.6%) group (P<0.01). Furthermore, the efficacy of the MCH agonist promoting the maximal response (E(max)) and its potency or effective dose producing 50% of the maximal response (ED(50)) were both associated with BMI (the higher the BMI, the higher the E(max) and the lower the ED(50)).

CONCLUSION

Our data clearly show that obesity affects pulmonary function performance in Tunisian women by potentially promoting their bronchial hyperreactivity as suggested by the significant correlation between their BMI and the efficacy of the MCH, as well as its potency.

Obesity-induced impairment of endothelium-dependent vasodilation in Tunisian women

OBJECTIVE

It is now well recognized that obesity is a major public health concern, and its prevalence has tremendously increased worldwide over the last decades, including Tunisia. As obesity is associated with cardiovascular diseases, the purpose of this study was to investigate the effect of obesity on forearm skin blood flow (FSBF) response to acetylcholine (Ach), an endothelium-dependent vasodilator, in Tunisian women over a wide range of body mass indices (BMIs).

SUBJECTS

One hundred and eighty healthy women with an average age of 34+/-6 years, an average height of 162+/-7 cm and an average weight of 78+/-19 kg participated in this investigation. The mean BMIs of the 60 lean, 50 overweight and 70 obese subjects were 22.1+/-0.3, 27.7+/-0.2 and 38.4+/-0.7 kg m(-2), respectively.

MEASUREMENTS

The FSBF was measured non-invasively using a laser Doppler flowmeter in response to local infusion of a cumulative dose of Ach.

RESULTS

After adjusting for age, the mean response of FSBF to Ach was significantly greater in lean (1168%+/-78) than in overweight (643%+/-38) and obese subjects (323%+/-18) (P=0.002; P<0.0001, respectively), suggesting a reduction of the endothelium-dependent nitric oxide (NO) release by obesity. Our regression analysis also revealed that the maximum FSBF response to Ach (that is, its efficacy) was inversely correlated with BMI, waist and hip circumferences (r=-0.994, P=0.002; r=-0.2, P<0.0001, and r=-0.321, P=0.001, respectively).

CONCLUSION

Our data demonstrate a reduction of skin vasodilatory reserve in obese patients and suggest a defect of both endothelial-dependent relaxation and wall compliance associated with obesity.

Asthma symptom perception and obesity in children

This study examined the relationship between obesity and asthma symptom perception in 200 youth with asthma. Repeated subjective and objective peak flow measurements were summarized using the Asthma Risk Grid (Klein et al., 2004), resulting in Accurate, Symptom Magnification and Danger Zone scores. Analyses were stratified by age and included ethnicity. For younger children, obesity was not significantly related to perception scores. For older children, a significant obesity-by-ethnicity interaction for Accurate Symptom Perception scores indicated that obese white children had lower accuracy than white nonobese children, while there was no difference for obese versus nonobese minority children. Obesity was also related to higher Symptom Magnification scores regardless of ethnicity for older children. These findings suggest that obesity may complicate asthma management by interfering with the ability to accurately perceive symptoms for some patients. More remains to be learned about the role of sociodemographic factors underlying this relationship.