Leptin: Does it have any role in childhood asthma?

Background: Although there is evidence of a positive association between asthma and obesity in adults and children, very little is known about the role of leptin in asthmatic children. Objectives: The aims of this study were to evaluate the relation between leptin and parameters of atopy and asthma in children. Methods: Body mass index (BMI) and serum leptin levels were measured in 102 (37 female, 65 male; mean age, 5.9 +/- 3.4 years) asthmatic and 33 (14 female, 19 male; mean age, 6.1 3.4 years) healthy children. Skin prick tests, total serum IgE, and pulmonary function tests were performed and were completed. Results: A significant difference was observed in serum leptin levels between asthmatic and healthy children. Median (interquartile range) levels were 3.53 (2.06-7.24) ng/mL and 2.26 (1.26-4.71) ng/mL, respectively (P = .008). Subgroup analysis revealed that this difference in leptin levels was confined entirely to boys: 3.09 (1.99-7.51) ng/mL in boys with asthma versus 1.52 (1.06-3.17) ng/mL in boys without asthma (P = .003). By logistic regression analysis, we found that leptin was a predictive factor for having asthma (odds ratio, 1.98; CI, 1.10-3.55; P = .021), whereas sex, age, or BMI were not. In a stepwise multiple regression analysis including sex (P = .001), age (P = .016), BMI (P < .001), and asthma (P = .022), all of these variables were found to affect log leptin levels (R-2 = 0.404). There was no significant sex difference in serum leptin levels among asthmatic children, whereas healthy boys had significantly lower leptin levels than healthy girls (P = .019). Atopic asthmatic subjects had significantly higher leptin levels than nonatopic asthmatic subjects (P = .038) with similar BMI. A significant, but weak, correlation was observed between leptin levels and IgE in the overall group of asthmatic children (r = 0.231; P = .019). Again, this correlation was confined entirely to boys (r = 0.319; P = .010). There was no relation between leptin levels and skin prick tests, pulmonary function tests, passive smoking, birth weight, and duration of breast-feeding. Conclusion: Our findings suggest that leptin may play a role in atopic asthma. High serum leptin levels in asthmatic boys may partly explain the higher prevalence of childhood asthma in male sex.