The relation between obesity and asthmatic airway inflammation

Abstract

Epidemiologic studies suggest increased asthma prevalence in obese subjects. However, the relation between obesity and airway inflammation remains unclear. This cross‐sectional study aims to investigate the relation between obesity indices and exhaled nitric oxide (ENO) and leukotriene B4 (LTB4) in children with asthma. Asthmatic patients aged 7–18 yr old were recruited. Weight‐for‐height Z score was calculated from anthropometry. ENO was measured by online single‐breath method using a chemiluminescence analyzer, whereas LTB4 concentrations in exhaled breath condensate (EBC) were quantified using competitive enzyme immunoassay. Ninety‐two asthmatics and 23 controls were recruited. The mean ENO and LTB4 concentrations in EBC were higher in asthmatic patients (87 p.p.b. and 40.5 pg/ml) than controls (25 p.p.b. and 18.7 pg/ml) (p < 0.0001 for both). Obesity, as defined by weight >120% median weight‐for‐height, was not associated with any alteration in ENO or LTB4 concentrations in patients with asthma. Besides, these inflammatory markers did not differ between asthmatics in the highest and lowest quartiles of weight‐for‐height Z score. On multivariate analysis, ENO showed significant correlation with age (β = 0.511, p < 0.0001), peripheral blood eosinophil count (β = 0.222, p = 0.019), plasma total IgE concentration (β = 0.187, p = 0.050) and forced expiratory volume in 1‐s (FEV1; β = −0.221, p = 0.014). None of the factors was associated with LTB4 concentration in EBC. In conclusion, ENO and LTB4 concentration in EBC are increased in childhood asthma. However, these inflammatory markers did not differ between obese and non‐obese children with asthma.

Avaliação do broncoespasmo induzido pelo exercício avaliado pelo Peak Flow Meter em adolescentes obesos

“…It is particularly interesting that obesity increases the TNFα seric concentration, which when connecting to the receptors placed in the straight muscles of the airways, promotes bronchoconstriction. In addition to these factors, there are others which when altering their concentrations may affect the airways function leading to their hyper responsiveness, which include: leptin, adiponectin and PAI-1 (18,29,30) . It is believed that in obese individuals an association between these hypotheses possibly occurs, which predisposes them to more remarkable EIB triggering.…”

Effect of obesity on breathlessness and airway responsiveness to methacholine in non-asthmatic subjects

“…However, there is little evidence from population studies that obesity is associated with objective markers of asthma such as airway hyperresponsiveness (AHR), [3][4][5][6][7] airway obstruction 8 or airway inflammation. 9 Asthma is defined by both episodic symptoms and variable airway obstruction. AHR, defined as excessive airway narrowing in response to provoking stimuli, is a marker of the tendency to variable airway obstruction and is a fundamental characteristic of asthma.…”

Obesity, Nutrition, and Asthma in Children

“…112,113 Obese asthmatic children did not have elevated airway LTB 4 . 134 Recent adult studies suggest that obesity may enhance neutrophilic airway inflammation 139 and systemic leukotriene production, 140 though this has not been evaluated in children. Since inhaled steroids are generally ineffective against neutrophilic inflammation, the discovery of neutrophilic inflammation in obese asthmatics is consistent with findings of reduced corticosteroids efficacy in the obese.…”

“…Exhaled nitric oxide levels (a surrogate of eosinophilic inflammation) among obese asthmatic children may be the same or even reduced compared to similar leans. [134][135][136][137][138] A few studies in adult obese asthmatics have shown reduced eosinophilic inflammation compared with similar leans. 112,113 Obese asthmatic children did not have elevated airway LTB 4 .…”