Obesity and asthma: physiological perspective

Association of general and abdominal obesity with lung function, FeNO, and blood eosinophils in adult asthmatics: Findings from NHANES 2007-2012

Purpose: Obesity is considered a risk factor for asthma exacerbation. However, limited studies have focused on the association of different levels of weight clusters with asthma. As such, we study the associations between different weight clusters with FeNO, blood eosinophils, and lung function among adult asthmatics. Methods: Data from 789 participants aged 20 years or older in the National Health and Nutrition Examination Survey 2007-2012 were analyzed. Body mass index (BMI) and waist circumference (WC) were used to determine the weight status. The study population was divided into five groups, including normal weight and low WC (153), normal weight and high WC (43), overweight and high WC (67), overweight and abdominal obesity (128), and general and abdominal obesity (398). A Multivariate linear regression model was used to evaluate the abovementioned associations after adjusting for potential confounding factors. Results: The adjusted models showed that general and abdominal obesity cluster (adjusted β = -0.63, 95% confidence interval (CI): -1.08, -0.17 p < 0.01), and the normal weight with high WC cluster (adjusted β = -0.96, 95% CI: -1.74, -0.19 p < 0.05) were associated with lower levels of blood eosinophils percentage than normal weight and low WC cluster. A similar tendency was shown in the levels of FeNO, but the differences were not significant (p > 0.05). Furthermore, abdominal obesity clusters were significantly associated with lower FVC, FVC% predicted, and FEV₁ measures than normal weight and low WC cluster, especially those individuals with general and abdominal obesity cluster. No association was found between different weight clusters and FEV₁/FVCF ratio. The two other weight clusters did not show the association with any of the lung function measures. Conclusion: General and abdominal obesity were associated with lung function impairment and a significant reduction of FeNO and blood eosinophil percentage. This study emphasized the importance of concurrent determination of BMI and WC in asthma clinical practice.

Respiratory burden in obese and young asthmatics: a study of diaphragmatic kinetics

Objective

The aim of this study was to assess the diaphragm kinetics, respiratory function, and serum dosage of leptin and inflammatory cytokines (IL-6 and TNF-α) in three clinical groups: obese, asthmatic, and healthy.

Methods

This is a clinical exploratory study performed on 73 youths (12-24 years of age, 42.5% male) allocated into three groups: obesity (OG, n=33), body mass index (BMIz-score) ≥ +2, asthmatic (AG, n=26) controlled mild asthmatics, classified by GINA, and Healthy Control Group (CG, n=14). The participants were subjected to diaphragmatic ultrasound, spirometry, maximal respiratory pressure, serum leptin levels, and IL-6 and TNF-α whole blood cell culture levels.

Results

Diaphragm thickness was higher in OG in comparison to AG and CG (2.0±0.4 vs 1.7±0.5 and 1.6±0.2, both with p<0.05). Maximal voluntary ventilation (MVV) was significantly lower in OG and AG in relation to the CG (82.8±21.4 and 72.5±21.2 vs 102.8±27.3, both with p<0.05). OG has the highest leptin rate among the groups (with the other two groups had p<0.05). All groups had similar TNF-α and IL-6 levels.

Conclusion

The muscular hypertrophy found in the diaphragm of the obese individuals can be justified by the increase in respiratory work imposed by the chronic condition of the disease. Such increase in thickness did not occur in controlled mild asthmatics. The IL-6 and TNF-α markers detected no evidence of muscle inflammation, even though leptin was expected to be altered in obese individuals. Both obese and asthmatic patients had lower pulmonary resistance than the healthy ones.

Association between obesity and chronic rhinosinusitis with nasal polyps: a national population-based study

OBJECTIVES

We performed a cross-sectional analysis of data from the nationwide Korea National Health and Nutrition Examination Survey to evaluate the association between obesity and chronic rhinosinusitis with nasal polyps (CRSwNP) or without nasal polyp (CRSsNP).

DESIGN

Retrospective cross-sectional analysis of health survey data.

SETTING

Voluntary survey of representative South Korean populations.

PARTICIPANTS

In total, 32 384 individuals aged 19 years or older with available data on CRS and obesity were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Diagnosis of CRSwNP or CRSsNP was performed by trained otolaryngologists through sinus endoscopy and surveys of medical history. General and central obesity was diagnosed using body mass index (BMI) and waist circumference (WC), respectively.

METHODS

A multivariate logistic regression analysis was used to clarify the association between CRSwNP or CRSsNP and obesity according to BMI and WC. Non-obese individuals were recruited as controls.

RESULTS

The prevalence of CRSwNP was higher in the general (OR, 1.438; 95% CI, 1.170 to 1.768; p<0.001) and central (OR, 1.251; 95% CI, 1.031 to 1.520; p=0.033) obesity groups than in the control group. Prevalence of CRSsNP was not correlated with obesity. In a logistic regression analysis, olfactory dysfunction (OR, 1.329; 95% CI, 1.137 to 1.553; p<0.001) and purulent discharge (OR, 1.383; 95% CI, 1.193 to 1.603; p<0.001) showed a higher incidence in the central obesity group than in the control group.

CONCLUSIONS

We demonstrated an association between CRSwNP and general and central obesity. Further investigations on the mechanism underlying this correlation are necessary for an improved understanding of the pathogenesis of CRSwNP.

The Effects of Obesity in Asthma

PURPOSE OF REVIEW

Rising costs and increasing morbidity makes the identification and treatment of high-risk asthma phenotypes important. In this review, we outline the complex relationship between obesity and asthma.

RECENT FINDINGS

Studies have confirmed a bi-directional relationship between obesity and asthma. Pathophysiological factors implicated include genetic risk, the effect of diet and microbiome, and obesity-related cytokines. There have been robust, albeit derived, efforts to phenotype this group with distinct clinical presentations based on age of onset of asthma. Unfortunately, the poor performance of biomarkers and traditional lung function testing has impeded diagnosis, phenotyping, and management of the obese asthma patient. There is also a lack of targeted interventions with weight loss showing some benefits. Obesity increases the prevalence of asthma and is associated with worse outcomes. There are unique research and clinical challenges while managing this group of patients.

Type 2 Diabetes and Asthma: Systematic Review of the Bidirectional Relationship

BACKGROUND AND OBJECTIVE

Obesity is an important contributor to the risk of both asthma and Type 2 Diabetes (T2DM). However, it has been suggested that T2DM and asthma are also independently associated. The aim of this systematic review was to synthesize the evidence for an independent relationship between T2DM and asthma.

METHODS

MEDLINE and EMBASE were searched for studies reporting the relationship between asthma and T2DM in adults. Given a potential bidirectional relationship, articles relating to T2DM as a risk factor for asthma, and asthma as a risk factor for T2DM were examined separately.

RESULTS

Eight studies were identified for inclusion in the review (n=2,934,399 participants). Four studies examined incident diabetes in those with asthma. The pooled (random effects model) adjusted hazard ratio for incident T2DM in asthma was 1.37 (95%CI 1.12-1.69; p <0.001) after controlling for BMI. Four studies reported prevalence or incidence rates of asthma in people with T2DM; higher rates of asthma in those with T2DM were reported in all four studies. Meta-analysis of results was not possible due to methodological heterogeneity. The quality of included studies was good, but due to small numbers, publication bias cannot be excluded.

CONCLUSION

The published literature suggests a bidirectional independent relationship between T2DM and asthma, although we cannot exclude publication bias.

Type 2 diabetes: A protective factor for COPD?

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and type 2 diabetes (T2DM) are common comorbidities. COPD is a known risk factor for incident T2DM, however few studies have examined the relationship in reverse. The primary aim of this study was to compare the incidence of COPD in people with and without T2DM.

MATERIALS AND METHODS

We conducted a retrospective case-control study using a long-established English general practice network database (n=894,646). We matched 29,217 cases of T2DM with controls, adjusting for age, gender, smoking status, BMI and social deprivation, to achieve 1:1 propensity matching and compared the rate of incident COPD over eight years of follow-up. We performed a secondary analysis to investigate the effect of insulin, metformin and sulphonylureas on COPD incidence.

RESULTS

People with T2DM had a reduced risk of COPD compared to matched controls over the follow-up period (HR 0.89, 95%CI 0.79-0.93). 48.5% of those with T2DM were ex-smokers compared with 27.3% of those without T2DM. Active smoking rates were 20.4% and 23.7% respectively. Insulin, metformin and sulphonylureas were not associated with incident COPD.

CONCLUSIONS

People with T2DM are less likely to be diagnosed with COPD than matched controls. This may be due to positive lifestyle changes, such as smoking cessation in those with T2DM.

Association between the Serum Metabolic Profile and Lung Function in Chronic Obstructive Pulmonary Disease

OBJECTIVES

Although dietary patterns are known to modulate disease severity in patients with chronic obstructive pulmonary disease (COPD), the relationship between the circulating lipid profile and lung function in COPD has not been studied extensively.

MATERIAL AND METHODS

There were 43 COPD patients with a history of smoking and 39 patients with a history of biomass fuel exposure recruited in this study, along with 43 age-matched healthy controls. All participants underwent complete lung function profiling, and their glucose and lipid profiles were measured. The association between the metabolic profile and lung function was assessed using the Spearman's rank-order correlation coefficient.

RESULTS

52.4% of the COPD patients were smokers compared to the healthy group (46.5%). We found an inverse correlation between triglyceride and functional residual capacity (p=-0.21, p=0.05) and a positive association between serum cholesterol and overall airway resistance (R5) (p=0.24, p=0.04) and central airway resistance (R20) (p=0.32, p=0.004). Low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) ratio and LDL/HDL ratio were also found to correlate with R5 (p=0.25, 0.23, and 0.22, respectively) and R20 (p=0.31, 0.24, and 0.24, respectively). No significant association was observed between other metabolites and either spirometric or plethysmographic lung function indices.

CONCLUSION

High serum triglyceride and cholesterol may increase the resistance in the airways, which may lead to increased airway obstruction. Therefore, monitoring of lipid profile should be considered in the diagnosis and management of COPD.

Lung volumes and airway resistance in patients with a possible restrictive pattern on spirometry

Objective:

Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung volumes and airway resistance plays in the correct classification of patients with a possible restrictive pattern on spirometry.

Methods:

This was a prospective study involving adults with reduced FVC and FEV1, as well as an FEV1/FV(C) ratio within the predicted range. Restrictive lung disease (RLD) was characterized by TLC below the 5th percentile, as determined by plethysmography. Obstructive lung disease (OLD) was characterized by high specific airway resistance, significant changes in post-bronchodilator FEV1, or an FEF25-75% < 50% of predicted, together with a high RV/TLC ratio. Nonspecific lung disease (NLD) was characterized by TLC within the predicted range and no obstruction. Combined lung disease (CLD) was characterized by reduced TLC and findings indicative of airflow obstruction. Clinical diagnoses were based on clinical suspicion, a respiratory questionnaire, and the review of tests of interest.

Results:

We included 300 patients in the study, of whom 108 (36%) were diagnosed with RLD. In addition, 120 (40%) and 72 (24%) were diagnosed with OLD/CLD and NLD, respectively. Among the latter, 24 (33%) were clinically diagnosed with OLD. In this sample, 151 patients (50.3%) were obese, and obesity was associated with all patterns of lung disease.

Conclusions:

Measuring lung volumes and airway resistance is often necessary in order to provide an appropriate characterization of the pattern of lung disease in patients presenting with a spirometry pattern suggestive of restriction. Airflow obstruction is common in such cases.

Objetivo:

Muitos pacientes com redução proporcional de CVF e VEF1 na espirometria não têm CPT reduzida. O objetivo deste estudo foi avaliar o papel da medida dos volumes pulmonares e da resistência das vias aéreas para a classificação correta de pacientes com possível restrição à espirometria.

Métodos:

Estudo prospectivo de adultos com CVF e VEF1 reduzidos e relação VEF1/CV(F) na faixa prevista. Distúrbio ventilatório restritivo (DVR) foi definido por CPT < 5º percentil por pletismografia. Distúrbio ventilatório obstrutivo (DVO) foi caracterizado por resistência específica de vias aéreas elevada, resposta significativa do VEF1 pós-broncodilatador e/ou um FEF25-75% < 50% do previsto associado a uma relação VR/CPT elevada. Distúrbio ventilatório inespecífico (DVI) foi caracterizado por CPT na faixa prevista e ausência de obstrução. Distúrbio ventilatório combinado (DVC) foi caracterizado por CPT reduzida e achados indicativos de obstrução ao fluxo aéreo. Os diagnósticos clínicos foram baseados em suspeita clínica, um questionário respiratório e revisão de exames de interesse.

Resultados:

Foram incluídos 300 pacientes no estudo, dos quais 108 (36%) tiveram diagnóstico de DVR, enquanto 120 (40%) foram diagnosticados com DVO ou DVC e 72 (24%) com DVI. Destes últimos, 24 (33%) tinham diagnóstico clínico de DVO. Nesta amostra, 151 pacientes (50,3%) eram obesos, e isso se associou com todos os padrões de distúrbios funcionais.

Conclusões:

Medidas dos volumes pulmonares e da resistência das vias aéreas são frequentemente necessárias para a caracterização adequada do tipo de distúrbio funcional em casos com possível restrição à espirometria. A obstrução ao fluxo aéreo é comum nesses casos.

Effects of Childhood Asthma on the Development of Obesity among School-aged Children

RATIONALE

Asthma and obesity often occur together in children. It is unknown whether asthma contributes to the childhood obesity epidemic.

OBJECTIVES

We aimed to investigate the effects of asthma and asthma medication use on the development of childhood obesity.

METHODS

The primary analysis was conducted among 2,171 nonobese children who were 5-8 years of age at study enrollment in the Southern California Children's Health Study (CHS) and were followed for up to 10 years. A replication analysis was performed in an independent sample of 2,684 CHS children followed from a mean age of 9.7 to 17.8 years.

MEASUREMENTS AND MAIN RESULTS

Height and weight were measured annually to classify children into normal, overweight, and obese categories. Asthma status was ascertained by parent- or self-reported physician-diagnosed asthma. Cox proportional hazards models were fitted to assess associations of asthma history with obesity incidence during follow-up. We found that children with a diagnosis of asthma at cohort entry were at 51% increased risk of developing obesity during childhood and adolescence compared with children without asthma at baseline (hazard ratio, 1.51; 95% confidence interval, 1.08-2.10) after adjusting for confounders. Use of asthma rescue medications at cohort entry reduced the risk of developing obesity (hazard ratio, 0.57; 95% confidence interval, 0.33-0.96). In addition, the significant association between a history of asthma and an increased risk of developing obesity was replicated in an independent CHS sample.

CONCLUSIONS

Children with asthma may be at higher risk of obesity. Asthma rescue medication use appeared to reduce obesity risk independent of physical activity.

Obesity, Oxidative Stress, Adipose Tissue Dysfunction, and the Associated Health Risks: Causes and Therapeutic Strategies

Obesity is gaining acceptance as a serious primary health burden that impairs the quality of life because of its associated complications, including diabetes, cardiovascular diseases, cancer, asthma, sleep disorders, hepatic dysfunction, renal dysfunction, and infertility. It is a complex metabolic disorder with a multifactorial origin. Growing evidence suggests that oxidative stress plays a role as the critical factor linking obesity with its associated complications. Obesity per se can induce systemic oxidative stress through various biochemical mechanisms, such as superoxide generation from NADPH oxidases, oxidative phosphorylation, glyceraldehyde auto-oxidation, protein kinase C activation, and polyol and hexosamine pathways. Other factors that also contribute to oxidative stress in obesity include hyperleptinemia, low antioxidant defense, chronic inflammation, and postprandial reactive oxygen species generation. In addition, recent studies suggest that adipose tissue plays a critical role in regulating the pathophysiological mechanisms of obesity and its related co-morbidities. To establish an adequate platform for the prevention of obesity and its associated health risks, understanding the factors that contribute to the cause of obesity is necessary. The most current list of obesity determinants includes genetic factors, dietary intake, physical activity, environmental and socioeconomic factors, eating disorders, and societal influences. On the basis of the currently identified predominant determinants of obesity, a broad range of strategies have been recommended to reduce the prevalence of obesity, such as regular physical activity, ad libitum food intake limiting to certain micronutrients, increased dietary intake of fruits and vegetables, and meal replacements. This review aims to highlight recent findings regarding the role of oxidative stress in the pathogenesis of obesity and its associated risk factors, the role of dysfunctional adipose tissue in development of these risk factors, and potential strategies to regulate body weight loss/gain for better health benefits.

Association between obesity and asthma - epidemiology, pathophysiology and clinical profile

Obesity is a risk factor for asthma, and obese asthmatics have lower disease control and increased symptom severity. Several putative links have been proposed, including genetics, mechanical restriction of the chest and the intake of corticosteroids. The most consistent evidence, however, comes from studies of cytokines produced by the adipose tissue called adipokines. Adipokine imbalance is associated with both proinflammatory status and asthma. Although reverse causation has been proposed, it is now acknowledged that obesity precedes asthma symptoms. Nevertheless, prenatal origins of both conditions complicate the search for causality. There is a confirmed role of neuro-immune cross-talk mediating obesity-induced asthma, with leptin playing a key role in these processes. Obesity-induced asthma is now considered a distinct asthma phenotype. In fact, it is one of the most important determinants of asthma phenotypes. Two main subphenotypes have been distinguished. The first phenotype, which affects adult women, is characterised by later onset and is more likely to be non-atopic. The childhood obesity-induced asthma phenotype is characterised by primary and predominantly atopic asthma. In obesity-induced asthma, the immune responses are shifted towards T helper (Th) 1 polarisation rather than the typical atopic Th2 immunological profile. Moreover, obese asthmatics might respond differently to environmental triggers. The high cost of treatment of obesity-related asthma, and the burden it causes for the patients and their families call for urgent intervention. Phenotype-specific approaches seem to be crucial for the success of prevention and treatment.

CD4(+), CD25(+), FOXP3 (+) T Regulatory Cell Levels in Obese, Asthmatic, Asthmatic Obese, and Healthy Children

The aim of this prospective case control study is to determine CD4(+), CD25(+), and FoxP3(+) T regulatory cells (Tregs) and T helper cells (Ths) in obese, asthmatic, asthmatic obese, and healthy children. Obese (n = 40), asthmatic (n = 40), asthmatic obese (n = 40), and healthy children (n = 40) were included in this study. Blood samples collected from children were marked with CD4, CD25, ve Foxp3 in order to detect Tregs and Ths by flow cytometric method. Statistical analyses were performed. p ≤ 0.05 was chosen as meaningful threshold. Tregs exhibiting anti-inflammatory nature were significantly lower in obese (0.16 %; p ≤ 0.001), asthmatic (0.25 %; p ≤ 0.01), and asthmatic obese (0.29 %; p ≤ 0.05) groups than control group (0.38 %). Ths were counted higher in asthma group than control (p ≤ 0.01) and obese (p ≤ 0.001) groups. T cell immunity plays important roles in chronic inflammatory diseases such as obesity and asthma pathogeneses. Decreased numbers of Tregs found in obese, asthmatic, and asthmatic obese children might represent a challenge of these cells.

The impact of diet on asthma and allergic diseases

The incidence of allergic diseases is increasing, both in developed and developing countries, concomitantly with the rise in living standards and the adoption of a 'western lifestyle'. For two decades, the hygiene hypothesis - which proposes that the lack of early childhood exposure to infectious agents increases susceptibility to allergic diseases in later life - provided the conceptual framework for unravelling the mechanisms that could account for the increased incidence of allergic diseases. In this Review, we discuss recent evidence that highlights the role of diet as a key factor influencing immune homeostasis and the development of allergic diseases through a complex interplay between nutrients, their metabolites and immune cell populations. Although further investigations are still required to understand these complex relationships, recent data have established a possible connection between metabolic homeostasis and allergic diseases.

Alterations in Lung Functions Based on BMI and Body Fat % Among Obese Indian Population at National Capital Region

BACKGROUND

In India, non-asthmatic hospital admission case study has been conducted to find out the relationship between obesity and lung functions. The main objective of the present study was to find out the alterations in lung functions due to obesity among Indian population living at National Capital Region (NCR).

MATERIALS AND METHODS

We examined 609 non obese and 211 obese subjects in a cross sectional study from National Capital Region, India with age group ranges between 18-70 years. BMI and body fat % was determined using body fat analyzer. Obese and non-obese subjects were classified based on criteria for BMI and Body fat %. Lung function test viz., FEV1 and PEFR were conducted using portable spirometer (PIKO-1).

RESULTS

A significant correlation (p<0.05) was observed between BMI and PEFR among non-obese male and female subjects. Decline in PEFR and FEV1 values for corresponding increase in body fat % was observed among study subjects. A significant (p<0.01) decline in mean FEV1 and PEFR was observed among non-obese and obese subjects, compared to their Indian reference standards for lung functions. A significant negative correlation (p<0.01) was observed between body fat % and lung functions (FEV1, PEFR).

CONCLUSION

It is concluded that obese subjects are at a risk of lung function impairment, based on the criteria followed for BMI and body fat %. The study also demonstrate that body fat% classification as a better index for determination of obese subjects compared to BMI classification, with respect to lung function impairments.

Normocaloric diet improves asthma-related quality of life in obese pubertal adolescents

BACKGROUND

Restrictive, very low-energy diets focused on rapid weight loss have proven to be effective in improving asthma outcome in obese patients, but their use in children and pubescents is controversial due its potential consequences in growth. More conservative, normocaloric schemes are suggested as a more suitable dietary approach for these patients.

METHODS

A randomized clinical trial was run of 51 pubertal adolescents with asthma and obesity, who were allocated to either an interventional 28-week program of normocaloric diet based on normal requirements for height and meal planning (n = 26) or a non-interventional (free diet) control group (n = 25). Asthma-related quality of life (AR-QOL, assessed by the Standardized Pediatric Asthma Quality of Life Questionnaire, PAQLQ[S]) and clinical indicators of asthma control were measured before and after the intervention period.

RESULTS

Diet intervention was associated with a significant improvement in AR-QOL in relation to baseline (Δ PAQLQ[S] scores) compared with controls, both in overall score (p < 0.001) and its subdomains (activity limitation, p < 0.001; symptoms, p < 0.002; emotional function, p < 0.001). The group with normocaloric diet observed a significant decrease in body mass index z-score, which correlated positively with the improvement in AR-QOL (Spearman's r = 0.51, p < 0.01), in addition to have significantly fewer events of acute attacks of asthma and nighttime awakenings, plus a non-significant reduction in the use of inhaled corticosteroids. No significant changes were observed in the pulmonary function tests.

CONCLUSION

The normocaloric dietary intervention was associated with improvement of AR-QOL and some aspects of asthma control. Such structured dietary programs could probably have a role as a complementary non-pharmacological therapeutic strategy in obese pubertal adolescents with asthma.