Serum and exhaled breath condensate leptin levels in asthmatic and obesity children: a pilot study

Background: Recent studies have highlighted the possible involvement of leptin in inflammation. The leptin receptor is also expressed by alveolar macrophages, T lymphocytes and bronchial epitelial cells, suggesting a possible role in the cascade of airway inflammation. Objectives: The aim of the study was to evaluate the levels of leptin in exhaled breath condensate (EBC) from asthmatic, normal-and overweight children, in relationship with airway inflammation. Methods: 15 asthmatic non-obese children, 15 healthy non-asthmatic non-obese children, 11 obese children with asthma (OA) and 20 obese children without asthma (ONA) were enrolled. Body impedance of body weight, EBC collection, FeNO, spirometry and a blood sampling for serum leptin were assessed. Results: Leptin EBC levels were significantly higher (3.9 ng ml(-1) +/- 1.3) in overweight children than those obese with asthma (3.6 ng ml(-1) +/- 1.6; p=0.97), non-owerweight asthmatics (2.2 ng ml(-1) +/- 1.2; p < 0.0001) and in healthy children (0.9 ng ml(-1) +/- 0.6; p < 0.001). Leptin EBC levels in asthmatic children were significantly higher than in healthy children (p= 0.05). Leptin serum levels were significantly higher in the overweight children compared with the asthmatics (12.7 ng ml(-1) +/- 13.2; p < 0.001) and the healthy group (11.1 ng ml(-1) +/- 11.2; p < 0.001). We observed a significant correlation between EBC-leptin levels and the serum-leptin levels (p= 0.001). No correlations were found between EBC-leptin levels, FeNO and lung function. Conclusions: This study shows that leptin is measurable in EBC in children and that EBC-leptin levels are significantly higher in the obese subjects and in asthmatic ones compared with healthy subjects. Leptin may therefore represent a non-invasive marker of non-specific airway inflammation in children.