Serum leptin levels correlate with bronchial hyper-responsiveness to mannitol in asthmatic children

ABSTRACT

PURPOSE: Epidemiological data indicate that obesity is a risk factor in asthma, however effects related to obesity and adipokines on airway inflammation and bronchial hyper-responsiveness (BHR) have not yet been demonstrated in the human airway. The aim of this study was to investigate the relationship between serum adipokine levels and BHR to mannitol in asthmatic children. METHODS: Serum adipokine levels were measured and pulmonary function tests were perfomed: baseline, postbronchodilator inhalation, methacholine inhalation, and mannitol inhalation. The response to mannitol was expressed as the dose causing a 15% decrease in forced expiratory volume in one second (FEV1) (PD15), and as the response-dose ratio (RDR) (% fall in FEV1/cumulative dose). RESULTS: Sixty-nine prepubertal children between the ages of 6 and 10 years were participated in the study. They comprised asthmatic children (n=40) and healthy (n=29). Twenty-two subjects (55.5%) with asthma had a positive mannitol bronchial provocation test (BPT) result. The body mass index (BMI) was higher in those asthmatics with positive mannitol BPTs than in asthmatics with negative mannitol BPTs and in the control group (19.30 kg/m2 vs. 17.60 kg/m2 vs. 17.93 kg/m2, P=0.035, P=0.046). Serum leptin levels were also significantly higher in asthmatics with positive mannitol BPTs than in asthmatics with negative mannitol BPTs and in the control group (10.58 ng/mL vs. 5.49 ng/mL vs. 6.75 ng/mL, P=0.002, P=0.016). Leptin values were significantly associated with a PD15 (r=-0.498, P=0.022) and RDR to mannitol (r=0.346, P=0.033) in asthmatic children after adjustment for BMI. CONCLUSION: Serum leptin levels were significantly associated with BHR to mannitol in asthmatic children.