The influence of obesity on inflammation and clinical symptoms in asthma

The visceral adiposity index is associated with asthma, especially current asthma: A cross-sectional study of NHANES, 2003 to 2018

To investigate the association between the visceral adiposity index (VAI) and asthma using data from National Health and Nutrition Examination Survey 2003 to 2018 by a cross-sectional study. We explored the potential relationship between the VAI and asthma incidence via a cross-sectional study of the National Health and Nutrition Examination Survey from 2003 to 2018. Multiple logistic regression analysis, restricted cubic spline analysis and subgroup analysis were performed. Among the 80,312 participants, 1984 had been told by a doctor or other health professional, and 1142 still had asthma. With all confounders controlled, the VAI was positively associated with asthma incidence (odds ratios 1.04, 95% confidence interval: 1.01, 1.08). When comparing the second, third, and fourth VAI quartiles to the lowest quartile, the adjusted odds ratios (95% confidence intervals) for asthma risk were 1.02 (0.86, 1.21), 1.14 (0.96, 1.36), and 1.18 (1, 1.39), respectively (P for trend = .02). Subgroup analysis revealed no significant interaction effect among the subgroups (P > .05). The positive association was stronger in current asthma patients (odds ratios 1.13, 95% confidence interval: 1.03, 1.24). When comparing the second, third, and fourth VAI quartiles to the lowest quartile, the adjusted odds ratios for current asthma risk were 1.15 (0.81, 1.64), 1.29 (0.91, 1.84), and 1.51 (1.01, 2.24), respectively (P for trend .04). The restricted cubic spline regression analysis did not reveal a nonlinear correlation between the VAI and asthma or current asthma. Subgroup analysis revealed a significant interaction effect between age (P for interaction = .03) and diabetes status (P for interaction = .02). Except in the age ≥60 years, Less than high school, normal body mass index subgroup, VAI, and current asthma were positively correlated. A positive relationship between the VAI and asthma incidence was observed. In particular, there was a strong positive correlation between the VAI score and current asthma. According to the subgroup analysis, more attention should be given to individuals aged 40 to 59 years who have diabetes.

The Impact of High-Fructose Diet and Co-Sensitization to House Dust Mites and Ragweed Pollen on the Modulation of Airway Reactivity and Serum Biomarkers in Rats

The topic of ragweed pollen (RW) versus house dust mites (HDMs) has often been deliberated, but the increasing incidence of co-sensitization between them has been scarcely addressed. Utilizing Sprague Dawley rats, we explored the effects of co-sensitization with the combination of HDMs and RW pollen extracts in correlation with high-fructose diet (HFrD) by in vitro tracheal reactivity analysis in isolated organ bath and biological explorations. Our findings unveiled interrelated connections between allergic asthma, dyslipidemia, and HFrD-induced obesity, shedding light on their compounding role through inflammation. The increased CRP values and airway hyperresponsiveness to the methacholine challenge suggest a synergistic effect of obesity on amplifying the existing inflammation induced by asthma. One of the major outcomes is that the co-sensitization to HDMs and RW pollen led to the development of a severe allergic asthma phenotype in rats, especially in those with HFrD. Therefore, the co-sensitization to these allergens as well as the HFrD may play a crucial role in the modulation of systemic inflammation, obesity, and airway reactivity.

Weight-adjusted waist index is an independent predictor of all-cause and cause-specific mortality in patients with asthma

BACKGROUND

There is a close relationship between obesity and the occurrence of asthma.The weight-adjusted waist index (WWI) is a relatively novel anthropometric parameter that reflects obesity.

OBJECTIVE

We aimed to explore the association between WWI and mortality in the asthma population.

METHODS

We included adult with asthma from NHANES 1999-2018. WWI = Waist circumference (cm)/square root of body weight (kg). Current asthma was determined by the participant's responses in standardized questionnaires. All-cause, cardiovascular disease (CVD), cancer, and respiratory disease mortality information was obtained by prospectively matching these data to the National Death Index. Multivariate-adjusted Cox proportional hazards regression analyses, Kaplan Meier survival analyses, restricted cubic spline (RCS) analyses, stratified analyses, and sensitivity analyses were used to clarify these associations.

RESULTS

A total of 101,316 participants were included in the study, and 3223 were diagnosed with asthma.WWI was independently and positively associated with all-cause and all factor-specific mortality in asthma. In fully adjusted models, each unit increase in WWI was associated with 43 % (hazard ratio [HR] and 95 % confidence interval [CI] = 1.43 [1.25,1.64], p < 0.0001), 58 % (1.58 [1.25, 1.99], p < 0.001), 50 % (1.50 [1.19, 1.90], p < 0.001), and 79 % (1.79 [1.34, 2.39], p < 0.0001) increased all-cause, CVD, cancer, and respiratory disease mortality, respectively. RCS analyses showed largely linear associations between WWI and all mortality risks. Stratified analyses indicated that these associations were influenced by multiple factors, and that age was consistently the effect modifier across all associations.

CONCLUSIONS

WWI is an independent predictor of all-cause, CVD, cancer, and respiratory-related mortality in the adult asthma population. These findings highlight that WWI may have novel prognostic value as a simple and easily accessible obesity parameter in asthma patients.

Western diet reduces small intestinal intraepithelial lymphocytes via FXR-Interferon pathway

The prevalence of obesity in the United States has continued to increase over the past several decades. Understanding how diet-induced obesity modulates mucosal immunity is of clinical relevance. We previously showed that consumption of a high fat, high sugar "Western" diet (WD) reduces the density and function of small intestinal Paneth cells, a small intestinal epithelial cell type with innate immune function. We hypothesized that obesity could also result in repressed gut adaptive immunity. Using small intestinal intraepithelial lymphocytes (IEL) as a readout, we found that in non-inflammatory bowel disease (IBD) subjects, high body mass index correlated with reduced IEL density. We recapitulated this in wild type (WT) mice fed with WD. A 4-week WD consumption was able to reduce IEL but not splenic, blood, or bone marrow lymphocytes, and the effect was reversible after another 2 weeks of standard diet (SD) washout. Importantly, WD-associated IEL reduction was not dependent on the presence of gut microbiota, as WD-fed germ-free mice also showed IEL reduction. We further found that WD-mediated Farnesoid X Receptor (FXR) activation in the gut triggered IEL reduction, and this was partially mediated by intestinal phagocytes. Activated FXR signaling stimulated phagocytes to secrete type I IFN, and inhibition of either FXR or type I IFN signaling within the phagocytes prevented WD-mediated IEL loss. Therefore, WD consumption represses both innate and adaptive immunity in the gut. These findings have significant clinical implications in the understanding of how diet modulates mucosal immunity.

Allergic Diseases and Childhood Obesity: A Detrimental Link?

Several epidemiological studies have described childhood obesity as a risk factor for atopic disease, particularly asthma. At the same time, this association seems to be more conflicting for allergic rhinitis, atopic dermatitis, and chronic urticaria. This article aims to deepen the possibility of a relationship between childhood obesity and allergic diseases. As regards asthma, the mechanical and inflammatory effects of obesity can lead to its development. In addition, excess adiposity is associated with increased production of inflammatory cytokines and adipokines, leading to low-grade systemic inflammation and an increased risk of asthma exacerbations. Allergic rhinitis, atopic dermatitis, food allergies, and chronic urticaria also seem to be related to this state of chronic low-grade systemic inflammation typical of obese children. Vitamin D deficiency appears to play a role in allergic rhinitis, while dyslipidemia and skin barrier defects could explain the link between obesity and atopic dermatitis. Starting from this evidence, it becomes of fundamental importance to act on body weight control to achieve general and allergic health, disentangling the detrimental link between obesity allergic diseases and childhood obesity. Further studies on the association between adiposity and atopy are needed, confirming the biologically active role of fat tissue in the development of allergic diseases and exploring the possibility of new therapeutic strategies.

Leptin-deficient ob/ob mice exhibit periodontitis phenotype and altered oral microbiome

BACKGROUND AND OBJECTIVE

Leptin-deficient obesity is associated with various systemic diseases including diabetes and low bone mass phenotype. However, the periodontal status of leptin-deficient obese individuals is still unclear. In this study, we aimed to analyze the periodontal status, alveolar bone phenotype, and oral microbiome status in leptin-deficient obese mice (ob/ob mice).

METHODS

This study used 12-week-old wild-type and ob/ob male mice. The alveolar bone phenotype and periodontal status in the maxilla were analyzed by micro-CT and histological analysis. Osteoclasts in alveolar bone were visualized by TRAP staining. Expressions of inflammatory markers (MMP-9, IL-1β, and TGF-β1) and osteoclastogenic markers (RANKL and OPG) in periodontium were analyzed by immunohistochemistry and RT-qPCR. The oral microbiome was analyzed by 16 S rDNA sequencing.

RESULTS

CEJ-ABC distance in maxillary molars (M1-M3) of ob/ob mice was significantly higher compared with that of wild-type. The alveolar bone BV/TV ratio was reduced in ob/ob mice compared with wild-type. Higher numbers of osteoclasts were observed in ob/ob mice alveolar bone adjacent to the molar root. Epithelial hyperplasia in gingiva and disordered periodontal ligaments was observed in ob/ob mice. RANKL/OPG expression ratio was increased in ob/ob mice compared with wild-type. Expressions of inflammatory markers MMP-9, IL-1β, and TGF-β1 were increased in ob/ob mice compared with wild-type. Oral microbiome analysis showed that beneficial bacteria Akkermansia and Ruminococcaceae_UCG_014 were more abundant in the wild-type mice while the inflammation-related Flavobacterium was more abundant in ob/ob mice.

CONCLUSION

In conclusion, ob/ob mice showed higher expressions of inflammatory factors, increased alveolar bone loss, lower abundance of the beneficial bacteria, and higher abundance of inflammatory bacteria in the oral cavity, suggesting leptin-deficient obesity as a risk factor for periodontitis development in ob/ob mice.

The causal relationship between allergic diseases and heart failure: Evidence from Mendelian randomization study

Background

Emerging evidence shows allergic diseases, such as atopic dermatitis and asthma, are risk factors of heart failure. However, the causal relationship between allergic diseases and heart failure is not clear.

Methods

We performed a two-sample Mendelian randomization analysis between allergic diseases and heart failure using summary statistics of genome-wide association studies from large GWAS consortia, with total sample size of 1.2 million. Independent instrumental variables for asthma and atopic dermatitis (P<1×10−5) were used as the exposure. We applied five models for the Mendelian randomization analysis. Finally, we performed the sensitivity analyses to assess the robustness of the results.

Results

We have identified 55 independent single nucleotide polymorphisms (SNPs) for asthma 54 independent SNPs for atopic dermatitis as our instrumental variables. The inverse variance-weighted (IVW) analysis showed asthma was significantly associated with increased risk of heart failure (ORIVW = 1.04, 95% CI, 1.01–1.07, P = 0.03). The Mendelian randomization analysis using the other four models also showed consistent results with the IVW analysis. Similarly, atopic dermatitis was also significantly associated with an increased risk of heart failure (ORIVW = 1.03, 95% CI, 1.01–1.06, P = 0.01), consistent with the other four models. The sensitivity analysis showed no evidence of horizontal pleiotropy or results were driven by single SNPs.

Conclusion

Our study identified asthma and atopic dermatitis as a causal risk factor for heart failure and suggest inflammatory pathogenesis as a key factor contributing to the underlying mechanism. These findings emphasize the importance of asthma and allergy control in the prevention and management of heart failure.

A snapshot of exhaled nitric oxide and asthma characteristics: experience from high to low income countries

Nitric oxide is a gas produced in the airways of asthmatic subjects and related to T2 inflammation. It can be measured as fractional nitric oxide (FeNO) in the exhaled air and used as a non-invasive, easy to evaluate, rapid marker. It is now widely used in many settings to determine airway inflammation. The aim of this narrative review is to report relationship between FeNO and the physiopathologic characteristics of asthmatic patients. Factors affecting FeNO levels have also been analysed as well as the impact of corticosteroid, target therapies and rehabilitation programs. Considering the availability of the test, spreading this methodology to low income countries has also been considered as a possibility for evaluating airway inflammation and monitoring adherence to inhaled corticosteroid therapy. PubMed data search has been performed restricted to English language papers. Research was limited to studies in adults unless studies in children were the only ones reported for a particular issue. This revision could be useful to summarize the role of FeNO in relation to asthma characteristics and help in the use of FeNO in different clinical settings particularly in low income countries.

Dietary Fatty Acids Amplify Inflammatory Responses to Infection through p38 MAPK Signaling

Obesity is an important risk factor for severe asthma exacerbations, which are mainly caused by respiratory infections. Dietary fatty acids, which are increased systemically in obese patients and are further increased after high-fat meals, affect the innate immune system and may contribute to dysfunctional immune responses to respiratory infection. In this study we investigated the effects of dietary fatty acids on immune responses to respiratory infection in pulmonary fibroblasts and a bronchial epithelial cell line (BEAS-2B). Cells were challenged with BSA-conjugated fatty acids (ω-6 polyunsaturated fatty acids [PUFAs], ω-3 PUFAs, or saturated fatty acids [SFAs]) +/- the viral mimic polyinosinic:polycytidylic acid (poly[I:C]) or bacterial compound lipoteichoic acid (LTA), and release of proinflammatory cytokines was measured. In both cell types, challenge with arachidonic acid (AA) (ω-6 PUFA) and poly(I:C) or LTA led to substantially greater IL-6 and CXCL8 release than either challenge alone, demonstrating synergy. In epithelial cells, palmitic acid (SFA) combined with poly(I:C) also led to greater IL-6 release. The underlying signaling pathways of AA and poly(I:C)- or LTA-induced cytokine release were examined using specific signaling inhibitors and IB. Cytokine production in pulmonary fibroblasts was prostaglandin dependent, and synergistic upregulation occurred via p38 mitogen-activated protein kinase signaling, whereas cytokine production in bronchial epithelial cell lines was mainly mediated through JNK and p38 mitogen-activated protein kinase signaling. We confirmed these findings using rhinovirus infection, demonstrating that AA enhances rhinovirus-induced cytokine release. This study suggests that during respiratory infection, increased levels of dietary ω-6 PUFAs and SFAs may lead to more severe airway inflammation and may contribute to and/or increase the severity of asthma exacerbations.

Sex differences in the association between asthma incidence and modifiable risk factors in Korean middle-aged and older adults: NHIS-HEALS 10-year cohort

Background

This study investigated the sex-specific incidence of asthma and the effects of modifiable risk factors, particularly obesity, on asthma incidence among middle-aged and older individuals in Korea.

Methods

We used data from the National Health Insurance Service-Health Screening Cohort (NHIS-HEALS), which includes health examinees aged 40–79 years in 2002–2003. In total, 459,529 participants with baseline anthropometric measurements were followed-up for 10 years and the development of asthma was evaluated (2004–2013). For subgroup analysis, 246,019 participants who had body mass index (BMI) and waist circumference (WC) measurements taken in 2008–2009 were included in the analysis of the asthma incidence for 2010–2013. Factors associated with asthma were analysed using Cox proportional hazard models.

Results

The cohort comprised 4,248,813 (men, 2,358,541; women, 1,890,272) person-years of follow-up for 2004–2013. The asthma incidence was 10.58 and 15.03 per 1000 person-years for men and women, respectively. Asthma incidence increased with age, notably so in men. Obesity based on the baseline BMI was significantly associated with asthma development in both sexes (men, HR = 1.23, 95% confidence interval (CI) = 1.13–1.34; women, HR = 1.40 95% CI = 1.32–1.48). High WC was also related to asthma incidence in both sexes with statistical significance (men, HR = 1.34, 95% CI = 1.16–1.57; women, HR = 1.19 95% CI = 1.03–1.37). Analysis of the combined effects of BMI and WC showed that men had a higher asthma risk in the group with both general obesity and abdominal obesity than in the group with non-abdominal obesity and normal BMI. However, obese women had a higher risk of asthma regardless of abdominal obesity. Similarly, smoking was associated with asthma in both sexes but drinking and physical activity showed different associations between the sexes.

Conclusions

Our results revealed that asthma incidence was substantially high at old age and lifestyle factors were associated with asthma development. Practical strategies including weight control and healthy lifestyle modification are required to prevent asthma in older people.

Nutrient intake is a predictor of lung function in obese asthmatic adolescents undergoing interdisciplinary therapy

Asthma-obesity is a multifactorial disease with specific asthma phenotypes that aggravate due to overweight and an unbalanced diet. Furthermore, obese asthmatic patients are corticotherapy-resistant. Therefore, the aims of the present study were to evaluate the effects of an interdisciplinary intervention on food consumption, body composition, lung function and adipokines in asthmatic and non-asthmatic obese adolescents and to investigate the influence of nutrients on lung function. Obese non-asthmatic (n 42) and obese asthmatic (n 21) adolescents of both sexes were enrolled in the present study. Food intake, adipokine levels, body composition, asthma symptoms and lung function were assessed across the study. After the intervention of 1 year, there was a reduction (P ≤ 0·01) in BMI, body fat percentage, visceral and subcutaneous fat and an increase (P ≤ 0·01) in lean mass and all lung function variables in both groups, except the relation between forced expiratory volume in 1 s and forced vital capacity (FEV1:FVC) in non-asthmatic patients. Moreover, both groups decreased lipid and cholesterol consumption (P ≤ 0·01). The highest energy consumption (β = -0·021) was associated with lower values of FVC. Similarly, carbohydrate consumption (β = -0·06) and cholesterol were negative predictors (β = -0·05) in FEV1:FVC. However, the consumption of Ca (β = 0·01), fibres (β = 1·34) and vitamin A (β = 0·01) were positive predictors of FEV1:FVC. Asthma-obesity interdisciplinary treatment promoted an improvement on food consumption and lung function in adolescents and demonstrated that the consumption of nutrients influenced an increase in lung function.

Visceral Fat Accumulation Is Associated with Asthma in Patients with Type 2 Diabetes

OBJECTIVE

The number of patients with type 2 diabetes has increased in Japan, and type 2 diabetes has attracted attention as a risk factor for asthma. However, the risk factors for the development of asthma in patients with type 2 diabetes have not been determined. This study was performed to clarify whether visceral fat accumulation (VFA) and insulin resistance are risk factors for the development of asthma in patients with type 2 diabetes.

MATERIALS AND METHODS

A cross-sectional study was conducted. The study group comprised 15 patients with type 2 diabetes with asthma, and the control group comprised 145 patients with type 2 diabetes without asthma. Their fat distribution was evaluated by measuring the VFA by abdominal computed tomography at the umbilical level. Their glucose status was assessed by measuring the fasting plasma glucose (FPG) concentration, fasting immunoreactive insulin concentration, homeostasis model assessment (HOMA) index, and hemoglobin A1c concentration.

RESULTS

Among patients with type 2 diabetes, VFA was significantly greater in patients with asthma than those without asthma (P < 0.0001). The FPG concentration, fasting immunoreactive insulin concentration, and HOMA index were higher in patients with asthma than those without asthma (P < 0.05, P < 0.0001, and P < 0.0001, respectively). Multiple logistic regression analysis showed that VFA and the HOMA index were significantly associated with asthma in patients with type 2 diabetes (odds ratio, 1.78; 95% confidence interval, 1.31-3.89; P = 0.0115 and odds ratio, 3.65; 95% confidence interval, 1.37-7.85; P = 0.0078, respectively).

CONCLUSIONS

Our data suggest that VFA and insulin resistance are associated with the development of asthma in patients with type 2 diabetes.

Interleukin 4 affects lipid metabolism and the expression of pro-inflammatory factors in mature rat adipocytes

Chronic low-grade inflammation contributes to diseases associated with fat tissue metabolism such as obesity and diabetes by the disturbed production of adipose tissue proteins, both pro- and anti-inflammatory. Interleukin-4 (IL-4) is one of the main inflammatory cytokines that activates Th2-dependent immune response and its increased expression was observed in the course of diseases characterized by chronic low-grade systemic inflammation such as obesity and asthma. We aimed to investigate if IL-4 may influence lipid metabolism and inflammatory responses in primary mature rat adipocytes. Mature adipocytes were isolated from male Wistar rats in incubated with IL-4 at three concentrations. We measured lipogenesis and lipolysis as well as the expression of selected genes using ddCt method was used to calculate relative gene expression. Protein level in tissue was analyzed using Western blot. Protein concentration in cell medium was analyzed using ELISA. Statistical analysis was done using GraphPad Prism 5 software. In primary cell model, we found that IL-4 stimulated lipogenesis and inhibited lipolysis in mature rat adipocytes. It also stimulated the expression of pro-inflammatory cytokines produced by adipocytes and decreased the expression of anti-inflammatory protein, adiponectin. Moreover, we found increased expression of inflammatory cytokines and transcription factors associated with Th2 response. Our observations suggest that low-grade inflammation enhances fat accumulation and significantly alters adipocyte metabolism.

Dual effects of leptin in perioperative gas exchange of morbidly obese patients

Leptin has shown positive effects on respiratory function in experimental settings. The role of leptin on perioperative respiratory function in morbidly obese patients has not been established. We performed a retrospective analysis of morbidly obese patients undergoing laparoscopic sleeve gastrectomy. Fasting serum leptin and interleukin (IL)-6 were measured preoperatively, and arterial blood gases were obtained pre- and postoperatively. Outcome variables were arterial partial pressure of oxygen (PaO₂), arterial partial pressure of carbon dioxide (PaCO₂), and differences in PaO₂ and PaCO₂ between pre- and postoperative values (ΔPaO₂, ΔPaCO₂; postoperative minus preoperative). Patients with lower (<40 μg/L) and higher (≥40 μg/L) leptin levels were compared. Bravais-Pearson’s correlation, multiple linear regression, and logistic regression analysis were performed. A total of 112 morbidly obese patients were included. Serum leptin was significantly higher in females than in males (42.86±12.89 vs. 30.67±13.39 μg/L, p<0.0001). Leptin was positively correlated with body mass index (r = 0.238; p = 0.011), IL-6 (r = 0.473; p<0.0001), and ΔPaO₂ (r = 0.312; p = 0.0008). Leptin was negatively correlated with preoperative PaO₂ (r = -0.199; p = 0.035). Preoperative PaO₂ was lower, ΔPaCO₂ was smaller, and ΔPaO₂ was greater in the high leptin group than in the low leptin group. In multiple regression analysis, leptin was negatively associated with preoperative PaO₂ (estimate coefficient = -0.147; p = 0.023). In logistic regression analysis, leptin was associated with improved ΔPaO₂ (odds ratio [OR] = 1.104; p = 0.0138) and ΔPaCO₂ (OR = 0.968; p = 0.0334). Leptin appears to have dual effects related to perioperative gas exchange in obese patients undergoing bariatric surgery. It is associated with worse preoperative oxygenation but improved respiratory function after surgery.

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.

Dietary omega-6, but not omega-3, polyunsaturated or saturated fatty acids increase inflammation in primary lung mesenchymal cells

Obesity is an important risk factor for developing severe asthma. Dietary fatty acids, which are increased in sera of obese individuals and after high-fat meals, activate the innate immune system and induce inflammation. This study investigated whether dietary fatty acids directly cause inflammation and/or synergize with obesity-induced cytokines in primary human pulmonary fibroblasts in vitro. Fibroblasts were challenged with BSA-conjugated fatty acids [ω-6 polyunsaturated fatty acids (PUFAs) and ω-3 PUFAs or saturated fatty acids (SFAs)], with or without TNF-α, and release of the proinflammatory cytokines, IL-6 and CXCL8, was measured. We found that the ω-6 PUFA arachidonic acid (AA), but not ω-3 PUFAs or SFAs, upregulates IL-6 and CXCL8 release. Combined AA and TNF-α challenge resulted in substantially greater cytokine release than either alone, demonstrating synergy. Synergistic upregulation of IL-6, but not CXCL8, was mainly mediated via cyclooxygenase (COX). Inhibition of p38 MAPK reduced CXCL8 release, induced by AA and TNF-α alone, but not in combination. Synergistic CXCL8 release, following AA and TNF-α challenge, was not medicated via a single signaling pathway (MEK1, JNK, phosphoinositide 3-kinase, and NF-κB) nor by hyperactivation of NF-κB or p38. To investigate if these findings occur in other airway cells, effects of AA in primary human airway smooth muscle (ASM) cells and human bronchial epithelial cells were also investigated. We found proinflammatory effects in ASM cells but not epithelial cells. This study suggests that diets rich in ω-6 PUFAs might promote airway inflammation via multiple pathways, including COX-dependent and -independent pathways, and in an obese person, may lead to more severe airway inflammation.

Association Between Airway Parameters and Abdominal Fat Measured via Computed Tomography in Asthmatic Patients

Purpose

We aimed to investigate whether airway parameters, assessed via computed tomography (CT), are associated with abdominal fat areas and to compare the clinical characteristics of asthmatic patients with and without elevated visceral to subcutaneous fat area ratio (EV).

Methods

Asthmatic patients (aged ≥40 years) were prospectively recruited. Chest (airway) and fat areas were assessed via CT. Airway parameters, including bronchial wall thickness (WT), lumen diameter (LD), lumen area (LA), wall area (WA), total area (TA), as well as WA/TA percentage (wall area %) were measured at the apical segmental bronchus in the right upper lobe. Visceral (VFA), subcutaneous (SFA) and total (TFA) fat areas (cm²) were also measured. The correlations between abdominal fat areas and airway parameters were assessed. EV was defined as VFA/SFA ≥ 0.4.

Results

Fifty asthmatic patients were included (mean age 62.9 years; 52% female); 38% had severe asthma. Significant correlations were found between VFA and both LD and LA (r = −0.35, P = 0.01; r = −0.34, P = 0.02, respectively), and SFA and both WA and TA (r = 0.38, P = 0.007; r = 0.34, P = 0.02, respectively). Exacerbations, requiring corticosteroid therapy or ER visitation, were significantly more frequent in subjects without EV (83% vs. 34%, P = 0.05).

Conclusions

Abdominal fat is associated with asthma, according to the location of fat accumulation. In asthmatic subjects, visceral fat seems to be attributable to the bronchial luminal narrowing, while subcutaneous fat may be related to thickening of bronchial wall.

Asthma exacerbations and socio-economic status in French adults with persistent asthma: A prospective cohort study

INTRODUCTION

Adults disadvantaged by poor socio-economic status (SES) are more severely affected by asthma compared to those with better SES. We aimed to determine whether the frequency of asthma exacerbations (AEx), as well as aspects related to AEx management, differed based on SES in patients treated with daily treatments.

METHODS

This study, part of the prospective observational cohort ASTRO-LAB, included French adult patients with persistent asthma. Patients were considered as low SES if they benefited from publicly funded special health insurance and/or were perceived as low SES by their general practitioner. AEx was defined as at least one of the following: asthma-related oral corticosteroid course, medical contact, hospitalization, and death. We examined associations between SES and AEx frequency, perceived triggering factors and type of medical contact after AEx.

RESULTS

In our sample of 255 patients, 11.40% were considered as low SES. Patients with low SES did not report significantly more AEx than medium/high SES patients during one-year follow-up (0.79 versus 0.55, p = 0.38). The type of medical contact during AEx differed significantly between the two groups (p = 0.03): patients with medium/high SES consulted their general practitioner more frequently (OR = 2.23, 95% CI = 0.91-5.50, p = 0.08) and were less likely to visit an emergency department or be hospitalized (OR = 0.27, 95% CI = 0.09-0.84, p = 0.02).

CONCLUSIONS

AEx frequency did not differ significantly between low and medium/high SES patients, but differences were found in the management of AEx. Studies are needed to better understand the relation between precariousness and management of asthma.

Association between periodontitis and severe asthma in adults: A case-control study

OBJECTIVE

To evaluate the association between periodontitis and severe asthma, with participants in treatment for severe asthma, controlled by therapy.

METHODS

A case-control investigation was performed to compare 130 adults with severe asthma with 130 without asthma. Individuals with periodontitis were those with ≥4 teeth with ≥1 site with probing depth ≥4 mm, clinical attachment level ≥3 mm, and bleeding upon probing at the same site. Severe asthma diagnosis was based on Global Initiative for Asthma criteria.

RESULTS

Association between exposure to periodontitis and severe asthma was found: OR_crude  = 2.98 (95% CI: 1.74-5.11). When confounders were considered, the association between exposure to periodontitis and severe asthma was maintained: OR_adjusted  = 3.01-3.25. Individuals with periodontitis had about a threefold increased risk of severe asthma than those without periodontitis. Frequency of periodontitis in participants with severe asthma was greater than that of those without asthma (46.6% vs 22.3%, p ≤ .05).

CONCLUSIONS

Association between periodontitis and severe asthma was observed. Further investigation is required to determine the direction of this relationship. It may be causal, but it may also be a consequence of the immunopathological process that characterizes asthma, or else, consequence of the medication used for treatment.

Dynamic hyperinflation and exercise limitations in obese asthmatic women

Obese individuals and patients with asthma can develop dynamic hyperinflation (DH) during exercise; however, no previous study has investigated DH as a factor associated with reduced exercise capacity in obese asthmatic women. The aim of the present study was to examine the occurrence of DH and exercise limitations in obese asthmatics. Obese grade II [obese group (Ob-G); BMI 35-39.9 kg/m²; n=36] and nonobese [nonobese group (NOb-G); BMI 18.5-29.9 kg/m²; n=18] asthmatic patients performed a cardiopulmonary test to quantify peak V̇o₂ and a submaximal exercise test to assess DH. Anthropometric measurements, quadriceps endurance, and lung function were also evaluated. A forward stepwise regression was used to evaluate the association between exercise tolerance (wattage) and limiting exercise factors. Fifty-four patients completed the protocol. The Ob-G (n = 36) presented higher peak V̇o₂ values but lower power-to-weight ratio values than the NOb-G (P <0 .05). DH was more common in the Ob-G (72.2%) than in the NOb-G (38.9%, P < 0.05). The Ob-G had a greater reduction in the inspiratory capacity (-18 vs. -4.6%, P < 0.05). Exercise tolerance was associated with quadriceps endurance (r = 0.65; p<0.001), oxygen pulse (r = 0.52; p=0.001), and DH (r = -0.46, P = 0.005). The multiple regression analysis showed that the exercise tolerance could be predicted from a linear association only for muscular endurance (r = 0.82 and r² = 0.67). This study shows that dynamic hyperinflation is a common condition in obese asthmatics; they have reduced fitness for activities of daily living compared to nonobese asthmatics. However, peripheral limitation was the main factor associated with reduced capacity of exercise in these patients.NEW & NOTEWORTHY This is the first study to investigate the occurrence of dynamic hyperinflation (DH) in obese asthmatics. Our results demonstrate that obese asthmatics present a higher frequency and intensity of DH than nonobese asthmatics. We also show that physical deconditioning in this population is linearly associated with cardiac (O₂ pulse), respiratory (DH), and peripheral muscle (resistance) limitation. However, multiple linear regression demonstrated that peripheral muscle limitation may explain the exercise limitation in this population.

Ambient air pollution and low birth weight - are some women more vulnerable than others?

BACKGROUND AND OBJECTIVES

Ambient air pollution is controllable, and it is one of the greatest environmental threats to human health. Studies conducted worldwide have provided evidence that maternal exposure to ambient air pollution during pregnancy enhances the risk of low birth weight at term (TLBW, <2500g among infants born ≥37 completed weeks of gestation), a maker of intrauterine growth restriction (IUGR), and suggest that some subgroups of pregnant women who are smoking, of low or high body-mass index (BMI), low socioeconomic status (SES) or asthma are more vulnerable towards the effect of ambient air pollution. The aim of this commentary is to review the published literature on the association between ambient air pollution and TLBW regarding increased vulnerability for the above-mentioned subgroups.

RESULTS

Although more than fifty epidemiological studies have examined the associations between ambient air pollution and TLBW to date, we only identified six studies that examined the potential effect modification of the association between ambient air pollution and TLBW by the above listed maternal risk factors. Two studies assessed effect modification caused by smoking on the association between ambient air pollution and TLBW. The adjusted odds ratio (OR) for TLBW associated with exposure to ambient air pollution were in one study higher among women who smoked during pregnancy, as compared to the OR of non-smoking women, while in the other study the association was in the opposite direction. The association of ambient air pollution and TLBW were higher among women characterized by extreme BMI (two studies) and low SES compared to non-obese women or women of higher SES (four studies), respectively. Only one study reported the estimated effects among asthmatic and non-asthmatic women and no statistically significant effect modification was evident for the risk of TLBW associated with ambient air pollution.

CONCLUSION AND RECOMMENDATIONS

The current epidemiologic evidence is scarce, but suggests that pregnant women who are smoking, being underweight, overweight/obese or having lower SES are a vulnerable subpopulation when exposed to ambient air pollution, with and increased risk of having a child with TLBW. The limited evidence precludes for definitive conclusions and further studies are recommended.

Chitinase 3-like-1 deficient donor splenocytes accentuated the pathogenesis of acute graft-versus-host diseases through regulating T cell expansion and type I inflammation

Acute graft-versus-host disease (aGVHD) is a major complication following transplantation, limiting the success of this therapy. Chitinase 3-like-1 (CHI3L1), a member of the glycosyl hydrolase 18 family, plays a critical role in bacterial infections, allergic disease and a variety of malignancies. Here, we investigated whether CHI3L1 could affect the pathogenesis of aGVHD in a mouse allo-HCT model. In this study, we show that CHI3L1 deficiency in donor T cells increased the severity of aGVHD through enhancing systemic and local inflammation. In addition, we found that aGVHD induced by CHI3L1-knockout (CHI3L1-KO) donors resulted in massive expansion of donor CD3⁺ T cells, release of Th1-related cytokines and chemokines, and significant inhibition of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) without changing the suppressive ability of donor Tregs remarkably. Expression of PERK1/2 and PAkt increased both in the skin and intestine from CHI3L1-KO splenocytes-treated aGVHD mice. Moreover, at mRNA and protein levels, we defined several molecules that may account for the enhanced ability of CHI3L1-KO splenocytes to migrate into target organs and produce Th1-related cytokines and chemokines, such as CXCL9, CXCL11, IFN-γ and TNF-α. Therefore, these results imply that CHI3L1 levels in donor cells may be related to the risk of aGVHD and targeting CHI3L1 may be a promising clinical strategy to control aGVHD.

Role of Chitinase 3-Like-1 in Interleukin-18-Induced Pulmonary Type 1, Type 2, and Type 17 Inflammation; Alveolar Destruction; and Airway Fibrosis in the Murine Lung

Chitinase 3-like 1 (Chi3l1), which is also called YKL-40 in humans and BRP-39 in mice, is the prototypic chitinase-like protein. Recent studies have highlighted its impressive ability to regulate the nature of tissue inflammation and the magnitude of tissue injury and fibroproliferative repair. This can be appreciated in studies that highlight its induction after cigarette smoke exposure, during which it inhibits alveolar destruction and the genesis of pulmonary emphysema. IL-18 is also known to be induced and activated by cigarette smoke, and, in murine models, the IL-18 pathway has been shown to be necessary and sufficient to generate chronic obstructive pulmonary disease-like inflammation, fibrosis, and tissue destruction. However, the relationship between Chi3l1 and IL-18 has not been defined. To address this issue we characterized the expression of Chi3l1/BRP-39 in control and lung-targeted IL-18 transgenic mice. We also characterized the effects of transgenic IL-18 in mice with wild-type and null Chi3l1 loci. The former studies demonstrated that IL-18 is a potent stimulator of Chi3l1/BRP-39 and that this stimulation is mediated via IFN-γ-, IL-13-, and IL-17A-dependent mechanisms. The latter studies demonstrated that, in the absence of Chi3l1/BRP-39, IL-18 induced type 2 and type 17 inflammation and fibrotic airway remodeling were significantly ameliorated, whereas type 1 inflammation, emphysematous alveolar destruction, and the expression of cytotoxic T lymphocyte perforin, granzyme, and retinoic acid early transcript 1 expression were enhanced. These studies demonstrate that IL-18 is a potent stimulator of Chi3l1 and that Chi3l1 is an important mediator of IL-18-induced inflammatory, fibrotic, alveolar remodeling, and cytotoxic responses.

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.

Obesity and asthma: current knowledge and future needs

PURPOSE OF REVIEW

Obesity has significant impact on asthma incidence and manifestations. The purpose of the review is to discuss recent observations regarding the association between obesity and asthma focusing on underlying mechanisms, clinical presentation, response to therapy and effect of weight reduction.

RECENT FINDINGS

Clinical and epidemiological studies indicate that obese patients with asthma may represent a unique phenotype, which is more difficult to control, less responsive to asthma medications and by that may have higher healthcare utilization. A number of common comorbidities have been linked to both obesity and asthma, and may, therefore, contribute to the obese-asthma phenotype. Furthermore, recently published studies indicate that even a modest weight reduction can improve clinical manifestations and outcome of asthma.

SUMMARY

Compared with normal-weight patients, obese and overweight patients with asthma have poorer asthma control and respond less to corticosteroid therapy. Future studies focusing on the mechanism underlying both obesity and asthma including the obese-asthma phenotype are required to better characterize the link between the conditions and target the management of this patient group.

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.

How to estimate overweight in pubescent asthmatics?

PURPOSE

The purpose of our research was to compare the body mass index (BMI) and selected anthropometric parameters in asthmatic and non-asthmatic pubescents.

MATERIAL AND METHODS

The study group consisted of 64 asthmatic boys and 45 girls; the control group consisted of 68 nonasthmatic boys and 48 non-asthmatic girls. All the children were 12-14 years old. We measured anthropometric parameters by a standardized method and the percentage of fat using the simple 2-site skinfold method. Additionally, we calculated the percentage of body composition (Matiegka) and the components of somatotype (Heath-Carter). Statistical significance was estimated at the level of p<0.05 by ANOVA test.

RESULTS

The asthmatic boys were significantly shorter than the non-asthmatic (p=0.015), however, we did not find any significant differences in weight and/or BMI in boys nor girls. The asthmatic boys had significantly higher fat mass % than the non-asthmatic ones (p<0.001). Moreover, they had significantly lower muscle mass % (p<0.001) as well as the bone mass % (p<0.001). The asthmatic girls had higher fat mass % than the non-asthmatic ones (p=0.028) and lower muscle mass % (p<0.001). The simple 2-site skinfold method also showed higher fat % in the asthmatic boys (p<0.001) but not in the girls. Examining the Heath-Carter somatotype components, the higher endomorphy was the only significant difference in asthmatic boys (p<0.001) and near significant in asthmatic girls (p=0.053).

CONCLUSION

Examination of the BMI alone is not sufficient in asthmatic children because of their high percentage of fat. That is why additionally testing fat % is recommended.

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

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

Does periodontal infection have an effect on severe asthma in adults?

BACKGROUND

The effect of periodontal infection on systemic diseases and conditions has been the subject of numerous studies worldwide. It is considered that periodontitis may influence the hyperinflammatory response in patients with severe asthma as a result of immuno-inflammatory changes. This study aims to evaluate the influence of periodontitis on severe asthma in adults.

METHODS

A case-control study was carried out, comprising 220 adult individuals: 113 diagnosed with asthma (case group) and 107 without asthma diagnosis (control group). The diagnosis of periodontitis was established after a full clinical examination using probing depth, clinical attachment level, and bleeding on probing. The diagnosis of severe asthma was based on the criteria recommended by the Global Initiative of Asthma (2012). Descriptive analyses of the variables were performed, followed by bivariate analyses, using the χ(2) test. Association measurements (odds ratio [OR]), with and without adjustment for potential confounders, were obtained. A significance level of 5% was used.

RESULTS

The ORunadjusted for the main association was 4.38 (95% confidence interval [CI] = 2.47 to 7.75). In the logistic regression model, after adjusting for age, education level, osteoporosis, smoking habit, and body mass index, the ORadjusted was 4.82 (95% CI = 2.66 to 8.76), which was statistically significant. Individuals with periodontal infection showed, approximately, five times more likelihood to have bronchial inflammation than those without such periodontal tissue infection.

CONCLUSION

The findings demonstrate the influence of periodontitis on severe asthma, given that the frequency of periodontitis is higher in individuals with severe asthma than in those without a diagnosis of bronchial inflammation.

Age dependent sex disproportion in US asthma hospitalization rates, 2000-2010

BACKGROUND

Age-stratified sex differences in asthma hospitalizations rates have been reported to be most marked between the ages of 40 and 54 years in New York. It is not known whether age-dependent sex differences in asthma hospitalization rates also exist for the entire United States.

OBJECTIVES

To compare sex-specific hospitalization rates for asthma in adults in the United States and to describe the adjusted associations between female sex and age in the fifth to sixth decades of life.

METHODS

The National Inpatient Sample databases for 2000-2010 were queried for a principal diagnosis of asthma to calculate the ratio of female to male hospitalization rates for different decades of adult life. Logistic regression modeling was used to determine whether age in the fifth to sixth decades of life had associations with female sex that remained significant after adjusting for comorbidities and demographic features.

RESULTS

For all years of the study, there was a distinct peaking in female to male ratio most manifested in the fifth to sixth decades of life. This age grouping was significantly associated with female sex. Models revealed that female sex was significantly associated with this age grouping, even after adjustment for obesity, chronic obstructive pulmonary disease, race, insurance status, discharge year, and smoking. Excluding identifiable repeat admissions also did not abrogate the age grouping association.

CONCLUSION

There is a striking propensity of women in their fifth to sixth decades of life to be admitted for asthma, which appears to be independent of many known comorbidities.