Obesity, smooth muscle, and airway hyperresponsiveness

Harvard University, Cambridge, Massachusetts, United States
Journal of Allergy and Clinical Immunology (Impact Factor: 11.25). 06/2005; 115(5):925-7. DOI: 10.1016/j.jaci.2005.01.064
Source: PubMed

ABSTRACT Both asthma and obesity are large and growing public health issues. Mounting evidence now implicates obesity as a major risk factor for asthma, thus linking these 2 major epidemics. Moreover, both in human subjects and in mice, obesity appears to predispose toward airway hyperresponsiveness. This review describes potential mechanisms whereby obesity might modify airway smooth muscle function to explain these observations. These mechanisms include both static and dynamic mechanical factors attributable to decreases in functional residual capacity and decreases in tidal volume that are observed in the obese. They include also obesity-related changes in lung development, chronic systemic inflammation (including increased serum levels of inflammatory cytokines and chemokines), and adipocyte-derived factors, including leptin, adiponectin, and plasminogen activator inhibitor.

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    ABSTRACT: Obesity is a major health problem worldwide. The prevalence of obesity is increasing in both developed and developing countries. In the UK, for example, 60% of adults are overweight and 25% are obese. Obesity is associated with many pathological complications including respiratory, cardiovascular and endocrine, but it also affects fertility and is associated with many reproductive complications. This has led us and others to investigate links between women with high BMI, pregnancy outcome and uterine function. These studies in turn have led investigators to ask how obesity can have such an impact on reproduction and, as part of this, to consider the role of the adipokines released from adipose tissue. Our focus in this short review is on adipokines and myometrial activity, and for completeness we overview their effects on other smooth muscles. To date four adipokines (leptin, visfatin, apelin and ghrelin) have been investigated and all affect myometrial contractility, but some more potently than others. We consider the possible mechanisms involved in how adipokines may modify uterine contractility, and discuss the potential impact on labour and delivery. Copyright © 2015. Published by Elsevier Inc.
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    ABSTRACT: The impact of obesity on the inflammatory process has been described in asthma, however little is known about the influence of diet-induced obesity on lung remodeling. For this purpose, 56 recently weaned A/J mice were randomly divided into 2 groups. In the C group, mice were fed a standard chow diet, while OB animals received isocaloric high-fat diet to reach 1.5 of the mean body weight of C. After 12 weeks, each group was further randomized to be sensitized and challenged with ovalbumin (OVA) or saline. Twenty-four hours after the last challenge, collagen fiber content in airways and lung parenchyma, the volume proportion of smooth muscle-specific actin in alveolar ducts and terminal bronchiole, and the number of eosinophils in bronchoalveolar lavage fluid were higher in OB-OVA than C-OVA. In conclusion, diet-induced obesity enhanced lung remodeling resulting in higher airway responsiveness in the present experimental chronic allergic asthma.
    Respiratory Physiology & Neurobiology 03/2011; 177(2):141-8. DOI:10.1016/j.resp.2011.03.019 · 1.97 Impact Factor
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    ABSTRACT: Objective. The study objective was to examine relationships between different body size measurements and asthma in ethnic minority children. Methods. We used data from a community-based study of 505 children aged 6-to-8 years old to study the association of percent body fat, fat distribution, and BMI percentile with asthma diagnosis. Poisson regression models were used to compute prevalence ratios (PRs) for sex-specific quintiles of the body fat measures on the main outcome of asthma. Results. When comparing the highest quintile of each body fat measure to the combined lowest two quintiles, higher body mass index percentile, percent body fat, and waist circumference all were associated with a higher likelihood of physician-diagnosed asthma (PR = 1.63 (95% CI 1.12-2.39), 1.50 (95% CI 1.02-2.21), and 1.56 (95% CI 1.04-2.34), resp.). Conclusions. This study found a significant association between increased body size and asthma diagnosis, regardless of the measurement examined.
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