Asthma and Obesity: The Chicken, the Egg, or More Than One Beast?

Severe and Difficult Asthma: Diagnosis and Management-Challenges for a Low-Resource Environment

Severe and difficult asthma in a low- and middle-income country (LMIC) can relate to (a) lack of availability of basic medications; (b) potentially reversible factors such as poor adherence or comorbidities such as obesity inhibiting a good response to treatment; and (c) (rarely) true severe, therapy-resistant asthma. However, definitions of severity should encompass not merely doses of prescribed medication, but also underlying risk. The nature of asthmatic airway disease shows geographical variation, and LMIC asthma should not be assumed to be phenotypically the same as that in high-income countries (HICs). The first assessment step is to ensure another diagnosis is not being missed. Largely, political action is needed if children with asthma are to get access to basic medications. If a child is apparently not responding to low dose, simple medications, the next step is not to increase the dose but perform a detailed assessment of what factors (for example co-morbidities such as obesity, or social factors like poor adherence) are inhibiting a treatment response; in most cases, an underlying reason can be found. An assessment of risk of future severe asthma attacks, side-effects of medication and impaired lung development is also important. True severe, therapy-resistant asthma is rare and there are multiple underlying molecular pathologies. In HICs, steroid-resistant eosinophilia would be treated with omalizumab or mepolizumab, but the cost of these is prohibitive in LMICs, the biomarkers of successful therapy are likely only relevant to HICs. In LMICs, a raised blood eosinophil count may be due to parasites, so treating asthma based on the blood eosinophil count may not be appropriate in these settings.

Exposure to PM2.5 and Lung Function Growth in Pre- and Early Adolescent Schoolchildren

Rationale

Epidemiological evidence indicates that ambient exposure to particulate matter ⩽2.5 μm in aerodynamic diameter (PM_2.5) has adverse effects on lung function growth in children, but it is not actually clear whether exposure to low-level PM_2.5 results in long-term decrements in lung function growth in pre- to early-adolescent schoolchildren.

Objectives

To examine long-term effects of PM_2.5 within the 4-year average concentration range of 10–19 μg/m³ on lung function growth with repeated measurements of lung function tests.

Methods

Longitudinal analysis of 6,233 lung function measurements in 1,466 participants aged 8–12 years from 16 school communities in 10 cities around Japan, covering a broad area of the country to represent concentration ranges of PM_2.5, was done with a multilevel linear regression model. Forced expiratory volume in 1 second, forced vital capacity (FVC), and maximal expiratory flow at 50% of FVC were used as lung function indicators to examine the effects of 10-μg/m³ increases in the PM_2.5 concentration on relative growth per each 10-cm increase in height.

Results

The overall annual mean PM_2.5 level was 13.5 μg/m³ (range, 10.4–19.0 μg/m³). We found no association between any of the lung function growth indicators and increases in PM_2.5 levels in children of either sex, even after controlling for potential confounders. Analysis with two-pollutant models with O₃ or NO₂ did not change the null results.

Conclusions

This nationwide longitudinal study suggests that concurrent, long-term exposure to PM_2.5 at concentrations ranging from 10.4 to 19.0 μg/m³ has little effect on lung function growth in preadolescent boys or pre- to early-adolescent girls.

Small Airway Disease in Pediatric Asthma: the Who, What, When, Where, Why, and How to Remediate. A Review and Commentary

Asthma affects all portions of the airways. Small airways, however, comprise a substantial component of the conducting lung air flow. In asthma, inflammatory processes can affect the whole respiratory tract, from central to peripheral/small airways. The emphasis in adult and pediatric respiratory disease clinics is to focus on large airway obstruction and reversibility. This information, although valuable, underemphasizes a large portion of the conduction airway of asthmatics. Standard descriptions of asthma management focus on a multiple medication approaches. We particularly focused on the management of asthma in the international guidelines for the Global Initiative for Asthma (GINA). Overall, however, minimal attention is placed on the small airway pool in asthma medical management. We took the opportunity to thoroughly review and present specific data from the adult asthma literature which supported the concept that small airway abnormalities may play a role in the pathogenesis and clinical expression of asthma. Based on the conclusions of the adult asthma literature, we here present a thorough review of the literature as it relates to small airway disease in children with asthma. We used, collectively, individual data sources of data to expand the information available from standard diagnostic techniques, especially spirometry, in the evaluation of small airway disease. As the pharmacological approaches to moderate to severe asthma are advancing rapidly into the realm of biologics, we sought to present potential pharmacological options for small airway dysfunction in pediatrics prior to biological modifier intervention.

Dietary Factors Associated with Asthma Prevalence Among Children in California

Background: Asthma continues to be the leading chronic disease affecting children in the United States. With mounting evidence of how diet plays a role in both chronic and allergic diseases, it is important to identify types of foods that may potentially promote a pro-inflammatory state. The study aims to examine the association between current asthma prevalence and intake of specific foods among children in California. Methods: Cross-sectional study conducting secondary analysis of data from the 2001 to 2015 California Health Interview Survey (CHIS) child surveys. A total of 65,565 completed surveys met the eligibility criteria (children ages 2-11) between the years 2001 and 2015. After excluding children with less than 2 years of age (for whom diet questions were not asked), analysis was conducted using 56,312 surveys. Multivariable logistic regression models estimated the adjusted odds ratios (ORs) and 95% CIs for the association of dietary intake with current asthma, controlling for confounding variables: gender, age, race, weight status, parent's education, English language proficiency of parent, household income, and location of residence. Analyses were survey weighted using raking variables to adjust for the oversampling and nonresponse surveys to reflect California Department of Finance Population Estimates for each survey period. Results: Approximately 13.4% of children in California currently have asthma. Consuming three or more sodas per day (adjusted OR = 1.83, 95% CI: 1.22-2.76, P = 0.004), two or more servings of French fries per day (adjusted odds ratio = 1.89, 95% CI: 1.08-3.21, P = 0.026), and fast food two or more times per week (adjusted odds ratio = 1.21, 95% CI: 1.02-1.45, P = 0.031) were positively associated with the prevalence for asthma. Conclusion: Analysis showed that children consuming energy dense foods were significantly associated with greater odds for current asthma after controlling for potential confounders.

General and Organ Fat Assessed by Magnetic Resonance Imaging and Respiratory Outcomes in Childhood

Rationale: Obesity has been implicated as a pathogenic factor in asthma, but the underlying role of general and organ fat is unclear.Objectives: We hypothesized that organ fat, rather than the total fat mass, increases the risk of asthma.Methods: In a population-based prospective cohort study among 5,421 children aged 10 years, we measured general fat including body mass index and fat mass index by dual-energy X-ray absorptiometry, and organ fat including subcutaneous fat index, visceral fat index, pericardial fat index, and liver fat fraction by magnetic resonance imaging. Lung function was measured by spirometry. Current asthma was assessed by questionnaire.Measurements and Main Results: Higher body mass index and fat mass index were associated with higher FEV₁ (z-score difference [95% confidence interval (CI)], 0.16 [0.14 to 0.19] and z-score difference [95% CI], 0.06 [0.03 to 0.09] per SD score increase, respectively), higher FVC (z-score difference [95% CI], 0.19 [0.17 to 0.22] and z-score difference [95% CI], 0.07 [0.04 to 0.10]), and lower FEV₁/FVC ratio (z-score difference [95% CI], -0.07 [-0.10 to -0.05] and z-score difference [95% CI], -0.03 [-0.06 to -0.00]) but not with forced expiratory flow after exhaling 75% of FVC or asthma. Higher visceral fat index, independent of fat mass index, was associated with higher FVC (z-score difference [95% CI], 0.07 [0.03 to 0.10]), lower FEV₁/FVC (z-score difference [95% CI], -0.05 [-0.09 to -0.01]), and higher risk of asthma (odds ratio, 1.20; 95% CI, 1.01 to 1.43 per SD score increase). No other organ fat measures were independently associated with lung function or asthma.Conclusions: The obesity-asthma link is driven mainly by visceral fat, independent of total fat mass; therefore, abdominal fat might contribute to asthma development.

Bidirectional Association Between Asthma and Obesity During Childhood and Adolescence: A Systematic Review and Meta-Analysis

Objective: Co-occurrence of pediatric asthma and obesity has been widely reported, yet the causal directions between these two disorders are still not well-understood. The objective of this meta-analysis is to explore whether there is a possibility of a bidirectional association for these two disorders in children and adolescents. Methods: PubMed, Embase, Web of Science, and CENTRAL databases were searched up to August 2020. Cohort studies reporting the associations of obesity with risk of physician-diagnosed asthma or physician-diagnosed asthma with risk of obesity in children and adolescents were eligible for the review. Results: A total of 3,091 records were identified from the four databases, with final inclusion of nine. Six studies reported the association between obesity and risk of asthma; three studies reported the association between asthma and risk of childhood obesity. As evaluated by the Newcastle-Ottawa quality assessment scale, all studies were assessed as high-quality studies. There was a statistically significant association between obesity and increased risk of physician-diagnosed asthma in children and adolescents. The pooled RR was 1.39 (95% CI: 1.28, 1.50; p < 0.001), with significant heterogeneity across studies (I ² = 81.7%; p _{heterogeneity} < 0.001). The pooled RR in boys was 1.53 (95% CI: 1.17, 1.99; p = 0.002), but such a significant association was not observed in girls (RR = 1.17, 95% CI: 0.79, 1.72; p = 0.434). For the association of asthma with risk of childhood obesity, the pooled RR was 1.47 (95%CI: 1.25, 1.72; p < 0.001) without statistical heterogeneity (I ² = 0%, p _{heterogeneity} = 0.652). Conclusion: There is a bidirectional association between obesity and asthma during childhood and adolescence, suggesting that childhood obesity drives an increase in the onset of asthma; meanwhile, childhood asthma may also increase risk of obesity for children and adolescents.

Maternal high fat diet compromises survival and modulates lung development of offspring, and impairs lung function of dams (female mice)

Background

Epidemiological studies have identified strong relationships between maternal obesity and offspring respiratory dysfunction; however, the causal direction is not known. We tested whether maternal obesity alters respiratory function of offspring in early life.

Methods

Female C57Bl/6 J mice were fed a high or low fat diet prior to and during two rounds of mating and resulting pregnancies with offspring lung function assessed at 2 weeks of age. The lung function of dams was measured at 33 weeks of age.

Results

A high fat diet caused significant weight gain prior to conception with dams exhibiting elevated fasting glucose, and glucose intolerance. The number of surviving litters was significantly less for dams fed a high fat diet, and surviving offspring weighed more, were longer and had larger lung volumes than those born to dams fed a low fat diet. The larger lung volumes significantly correlated in a linear fashion with body length. Pups born from the second pregnancy had reduced tissue elastance compared to pups born from the first pregnancy, regardless of the dam’s diet. As there was reduced offspring survival born to dams fed a high fat diet, the statistical power of lung function measures of offspring was limited. There were signs of increased inflammation in the bronchoalveolar lavage fluid of dams (but not offspring) fed a high fat diet, with more tumour necrosis factor-α, interleukin(IL)-5, IL-33 and leptin detected. Dams that were fed a high fat diet and became pregnant twice had reduced fasting glucose immediately prior to the second mating, and lower levels of IL-33 and leptin in bronchoalveolar lavage fluid.

Conclusions

While maternal high fat diet compromised litter survival, it also promoted somatic and lung growth (increased lung volume) in the offspring. Further studies are required to examine downstream effects of this enhanced lung volume on respiratory function in disease settings.

ENOblock inhibits the pathology of diet-induced obesity

Obesity is a medical condition that impacts on all levels of society and causes numerous comorbidities, such as diabetes, cardiovascular disease, and cancer. We assessed the suitability of targeting enolase, a glycolysis pathway enzyme with multiple, secondary functions in cells, to treat obesity. Treating adipocytes with ENOblock, a novel modulator of these secondary ‘moonlighting’ functions of enolase, suppressed the adipogenic program and induced mitochondrial uncoupling. Obese animals treated with ENOblock showed a reduction in body weight and increased core body temperature. Metabolic and inflammatory parameters were improved in the liver, adipose tissue and hippocampus. The mechanism of ENOblock was identified as transcriptional repression of master regulators of lipid homeostasis (Srebp-1a and Srebp-1c), gluconeogenesis (Pck-1) and inflammation (Tnf-α and Il-6). ENOblock treatment also reduced body weight gain, lowered cumulative food intake and increased fecal lipid content in mice fed a high fat diet. Our results support the further drug development of ENOblock as a therapeutic for obesity and suggest enolase as a new target for this disorder.

Obesity and asthma: risk, control and treatment

Asthma and obesity are currently one of the most common diseases. Observing an increase in morbidity of obesity and asthma, it can be concluded that there is a link between these diseases. But the mechanism of this relation is not well known. Due to reduced movement in patients and treatment, asthma is conducive to obesity, and obesity can exacerbate the symptoms associated with asthma. Obesity can affect bronchial hyperresponsiveness. Increasing body fat in obese people leads to systemic inflammation and elevated serum levels of many proinflammatory cytokines (e.g. leptin) and anti-inflammatory ones (e.g. adiponectin) that can have a causal relationship to bronchial asthma, but human studies are ambiguous. Obese asthmatics are characterized by a phenotype: heavier asthma, worse response to treatment and control of asthma. It has been found that in obese people, weight loss reduces the severity of asthma symptoms, so in these patients, treatment should include weight control.

Associations of ultra-processed food and drink products with asthma and wheezing among Brazilian adolescents

BACKGROUND

Although both consumptions of ultra-processed products and asthma are common during adolescence, the epidemiological evidence in regarding their association is unclear. We investigated the associations of ultra-processed products consumption with asthma and wheezing in a representative sample of Brazilian adolescents.

METHODS

We used data from a representative sample of 109 104 Brazilian adolescents enrolled in the National Survey of School Health, 2012. The consumption of ultra-processed products was based on the weekly consumption (0-2, 3-4, ≥5 d/wk) of sweet biscuits, salty biscuits, ultra-processed meats, sweets/candies, soft drinks, and packaged snacks over the previous 7 days. We also calculated an ultra-processed consumption score by adding partial scores corresponding to weekly frequency intake of each ultra-processed product. The ultra-processed consumption score ranged from 0 to 42, the higher score, the higher the intake of these products. The presence of wheezing in the previous 12 months and asthma at any time in the past was self-reported.

RESULTS

The adjusted odds ratios of asthma comparing the extreme categories ranged from 1.08 (95% CI 1.03-1.13) for sweets/candies to 1.30 (1.21-1.40) for ultra-processed meats. Similar magnitude of associations was found for wheezing outcome. The ultra-processed consumption score was positively associated with the presence of asthma and wheezing in a dose-response manner. The adjusted OR of asthma and wheezing comparing highest to lowest quintile of ultra-processed consumption score was 1.27 (95% CI 1.15-1.41) and 1.42 (1.35-1.50), respectively.

CONCLUSIONS

The consumption of ultra-processed products was positively associated with the presence of asthma and wheezing in adolescents.