title: Leptin and asthma in overweight children at 12 years of age.
abstract: Obesity is suggested as a risk factor for asthma, but the mechanisms are unclear. The relationship between obesity and asthma has not been considered in children born with very low-birth weight (VLBW). We hypothesized that overweight was a contributing factor for asthma in VLBW children, and that leptin and leptin-associated cytokines might play roles in overweight-related asthma. Seventy-four VLBW and 64 normal birth weight (NBW) children participated in a 12-yr follow up study assessing asthma and allergy. Twenty-seven (12 VLBW) of the 138 children were overweight according to the proposed international definition. The diagnosis of current asthma was made by a pediatrician. Serum levels of leptin and interferon (IFN)-gamma were analyzed by enzyme-linked immunosorbent assay (ELISA). Leptin levels were considerably higher in the overweight than in the non-overweight children (median value: 18.1 vs. 2.8 ng/ml, p < 0.001). In the overweight children, current asthmatics had twice as high levels of leptin as children without current asthma (median value: 30.8 vs. 14.3 ng/ml, p = 0.14), but this was not the case in the non-overweight children. IFN-gamma was more often detected in the overweight than in the non-overweight children (61% vs. 12%, p < 0.001), and there was a positive correlation between the levels of leptin and the levels of IFN-gamma (Rho = 0.40, p < 0.001). In the VLBW group, the overweight children had a significantly increased risk for current asthma compared with the non-overweight children after adjustment for the neonatal risk factors [adjusted odds ratio (OR) 5.8, 95% confidence interval (CI): 1.2-27]. Thus, overweight was associated with asthma in the VLBW children. Our hypothesis remained that leptin might be involved in the pathogenesis of asthma in the overweight children, and IFN-gamma might be a pathway in the process of leptin-induced inflammation.
authors.affiliation: Department of Molecular and Clinical Medicine, Division of Pediatrics, Linköping University, Linköping, Sweden. xiama@imk.liu.se
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Mai
authors.forename: Malin F
authors.initials: MF
authors.lastname: Böttcher
authors.forename: Ingemar
authors.initials: I
authors.lastname: Leijon
mesh_terms: D001249:Asthma / Q000097:blood* / Q000453:epidemiology*; D002648:Child; D015897:Comorbidity; D016207:Cytokines / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008297:Male; D009765:Obesity / Q000097:blood* / Q000453:epidemiology*; D016017:Odds Ratio; D012737:Sex Factors; D012882:Skin Tests / Q000379:methods; D013147:Spirometry / Q000379:methods; D018709:Statistics, Nonparametric; D013548:Sweden / Q000453:epidemiology
chemical_list: D016207:Cytokines; D020738:Leptin