Leptin and asthma in overweight children at 12 years of age

Authors

  • Xiao-Mei Mai,

    1. Department of Molecular and Clinical Medicine, Division of Pediatrics, Linköping University, Linköping
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  • Malin F. Böttcher,

    1. Department of Molecular and Clinical Medicine, Division of Pediatrics, Linköping University, Linköping
    2. Clinical Research Center, Faculty of Health Sciences, Linköping University, Linköping, Sweden
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  • Ingemar Leijon

    1. Department of Molecular and Clinical Medicine, Division of Pediatrics, Linköping University, Linköping
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Xiao-Mei Mai, Department of Molecular and Clinical Medicine, Division of Pediatrics, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
Tel.: +46 13 22 47 00
Fax: +46 13 22 47 73
E-mail: xiama@imk.liu.se

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)-γ 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-γ 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-γ (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-γ might be a pathway in the process of leptin-induced inflammation.

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