Is obesity related to the lung function of non-asthmatic children?

Cytokines Profile and Lung Function in Children with Obesity and Asthma: A Case Control Study

The existence of common inflammatory biomarkers linking obesity and asthma in children has been hypothesized. Nevertheless, laboratory and clinical characteristics of children with obesity and asthma are still poorly defined. The primary aim of the present study is to investigate the lung function and the cytokine profile, in children with obesity and asthma. In this prospective, cross-sectional pilot study, pulmonary function tests, biochemical parameters, and serum cytokines levels were compared in three groups of 28 children each, matched for age and sex. Obese children showed normal forced spirometry values except an increased distal airway resistance in subjects with obesity and no asthma. Both groups including obese children showed higher leptin and IL-10 levels and lower adiponectin and TNF-alpha levels compared to children with no obesity and asthma. IL-33 and TGF-beta1 levels were higher in children with obesity and asthma vs. children with normal weight and asthma. Finally, IL-6 was undetectable in approximately 70% of obese children with no asthma, in 57% obese asthmatic children and in 100% of children with normal-weight and asthma. Children with obesity and asthma show the most striking cytokine profile, suggesting a pro-inflammatory role of fat mass in asthma development.

Interactions between ambient air pollution and obesity on lung function in children: The Seven Northeastern Chinese Cities (SNEC) Study

Children are vulnerable to air pollution-induced lung function deficits, and the prevalence of obesity has been increasing in children. To evaluate the joint effects of long-term PM₁ (particulate matter with an aerodynamic diameter ≤ 1.0 μm) exposure and obesity on children's lung function, a cross-sectional sample of 6740 children (aged 7-14 years) was enrolled across seven northeastern Chinese cities from 2012 to 2013. Weight and lung function, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF), were measured according to standardized protocols. Average PM₁, PM_2.5, PM₁₀ and nitrogen dioxide (NO₂) exposure levels were estimated using a spatiotemporal model, and sulphur dioxide (SO₂) and ozone (O₃) exposure were estimated using data from municipal air monitoring stations. Two-level logistic regression and general linear models were used to analyze the joint effects of body mass index (BMI) and air pollutants. The results showed that long-term air pollution exposure was associated with lung function impairment and there were significant interactions with BMI. Associations were stronger among obese and overweight than normal weight participants (the adjusted odds ratios (95% confidence intervals) for PM₁ and lung function impairments in three increasing BMI categories were 1.50 (1.07-2.11) to 2.55 (1.59-4.07) for FVC < 85% predicted, 1.44 (1.03-2.01) to 2.51 (1.53-4.11) for FEV₁ < 85% predicted, 1.34 (0.97-1.84) to 2.04 (1.24-3.35) for PEF < 75% predicted, and 1.34 (1.01-1.78) to 1.93 (1.26-2.95) for MMEF < 75% predicted). Consistent results were detected in linear regression models for PM₁, PM_2.5 and SO₂ on FVC and FEV₁ impairments (P_Interaction < 0.05). These modification effects were stronger among females and older participants. These results can provide policy makers with more comprehensive information for to develop strategies for preventing air pollution induced children's lung function deficits among children.

[Obesity in childhood: What are the respiratory risks?]

In childhood and adolescence overweight is defined as a body mass index (BMI) above the 97th percentile for age and sex, according to the curves established by the International Obesity Task Force (IOTF). In France, it is estimated that 25 % of children under 18 years old are overweight. Overweight and obesity in this population are multifactorial, with an important influence of genetic factors, modulated by pre and post-natal (maternal smoking), societal and psychological determinants. The impact of obesity on respiratory function in children is mostly characterized by a decreased FEV1/FCV. Moreover, several studies have shown an association between asthma and overweight/obesity, with a pejorative impact of BMI on asthma control. However, asthma is still poorly characterized in this population, and the determinants of bronchial obstruction seem to differ from non-obese children, with less eosinophilic inflammation. Obstructive sleep apnea syndrome (OSAS) is a frequent complication of obesity, affecting up to 80% of obese children and adolescents. It has a specific polysomnographic definition in children. Symptoms are similar to adult OSAS, but with cognitive and neurobehavioral alterations often more important in adolescents. The treatment consists in ENT surgery when indicated (with systematic post-operative polysomnography), and nocturnal continuous positive airway pressure (CPAP). The obesity-hypoventilation syndrome (OHS) has the same definition in children as in adults and affects up to 20% of obese patients. Treatment consists in nocturnal ventilation using bilevel positive airway pressure (BiPAP). Finally, in some extreme cases, bariatric surgery can be performed. The indication should be discussed in a specialised paediatric reference centre.