Leptin levels in exhaled breath condensate

Demet Inci, Pavel Basek, Johannes H Wildhaber, Alexander Moeller
A cross-sectional analysis of the Third National Health and Nutrition Examination Survey (NHANES III) found that overweight children aged between 6 and 16 years had three times more asthma risk than their healthy weight peers (1) . Another cross-sectional study supported the relationship between asthma and being overweight in childhood and showed that the prevalence of asthma was greater in overweight children (2) . Leptin, a 167-amino-acid peptide, is a recently discovered hormone which is
more » ... ormone which is believed to play a major role in the regulation of body weight. Recently, it has been reported that serum leptin levels are increased in asthmatic children (3) . Leptin has also been reported to have a specifi c effect on T-lymphocyte responses. It has been hypothesized that leptin is involved in the regulation of asthmatic airway infl ammation levels by regulating T-cell responses by polarizing Th cells toward a Th1 phenotype and by inhibiting immune responses, such as Th2 activation and may have a role in asthma (4) . Mai et al. (5) found twice as high serum levels of leptin in overweight asthmatic children compared to overweight children without current asthma. Serum leptin levels are associated with asthma in adult women, independent of BMI (6) . In children with asthma close associations have been shown between serum adiponectin and leptin and pulmonary function, but it has been suggested that they may play a regulatory role rather than being an etiologic mechanism of asthma development (7) . As very little is known about the role of leptin within the airways and lung tissue and asthma, non-invasive tools to investigate, such associations would allow epidemiological and longitudinal studies to be performed on a larger scale. Such studies are needed to confi rm the relationships of leptin and asthma and improve our understanding of associations between asthma and being overweight. Exhaled breath condensates (EBC) contain aerosolized airway lining fl uid and volatile compounds from the airways and the lung periphery. The assessment of EBC compounds is recognized to be a potentially useful research tool in children for the non-invasive quantifi cation of airway infl ammation and metabolic processes in asthma and other airway diseases. The aim of this pilot study was to evaluate whether leptin can be found in EBC and to investigate differences between condensate leptin levels in overweight and healthy weight children. A total of 20 children (fi ve overweight asthmatics, fi ve healthy weight asthmatics, fi ve overweight healthy and fi ve healthy weight healthy controls), aged 6 -15 years, were included in this study. We obtained data on weight and length (body mass index), lung function, fractional exhaled nitric oxide (FE NO ) and allergic sensitization by the means of skin prick testing using a panel of common allergens including house dust mite, mold mix, tree mix, grass mix, weed mix, cat and dog hair. Informed consent was taken from the parents. Exhaled breath condensates were collected using the commercial EcoScreen breath condenser system (Jaeger, Wuerzburg, Germany). Approximately 1.5 mL of condensate was collected in 15 min and immediately stored at -70 ° C for later analysis. We standardized possible variables during and after EBC collection, according to the methodological recommendations of the ATS/ERS task force (8) . Condensate leptin levels were measured according to the instruction by the manufacturer using a commercially available ChemoKine TM Human leptin EIA kit (Chemicon International Inc., CA, USA) with a lower detection limit of 0.488 ng/mL. Leptin levels were measured in un-concentrated, native EBC and after concentrating the breath condensate 3-fold by freeze drying. The patient characteristics, results of spirometry, FE NO, skin prick test and EBC leptin levels are summarized in Table 1 . Leptin levels were below the detection limit of the assay (0.488 ng/mL) in the native, un-concentrated EBC and in 3-fold concentrated samples and were therefore considered as non-detectable in any of the EBC samples. We were not able to detect leptin in the EBC from asthmatic, healthy overweight and healthy weight children, even after 3-fold concentration of the EBC samples. We strictly followed the methodological recommendations of the ATS/ ERS task force (8) and the instructions of the manufacturers and standardized possible variables during and after EBC
doi:10.5167/uzh-154615 fatcat:kakkigubdjgp3kqlkdhhq7p3bu