Childhood overweight and asthma symptoms, the role of pro-inflammatory proteins

BACKGROUND Systemic inflammation is suggested as a mechanism by which overweight might induce asthma. However, few studies have linked childhood overweight, inflammation and asthma. OBJECTIVE To study the association between body mass index (BMI), asthma symptoms and pro-inflammatory proteins. METHODS High-sensitivity C-reactive protein (hs-CRP), complement factor 3 (C3) and 4 (C4) concentrations, and body weight and height were available for 359 4-year-old children participating in the Prevention and Incidence of Asthma and Mite Allergy birth cohort study. Data on asthma symptoms were obtained by yearly questionnaires. Logistic regression and generalized estimating equations were used to analyse the cross-sectional and prospective associations between BMI, asthma symptoms and pro-inflammatory proteins. RESULTS BMI was associated with asthma symptoms {odds ratio [OR] 1.43 [95% confidence interval (CI): 1.08-1.88] per BMI standard deviation scores [SDS]}. The inclusion of hs-CRP, C3 and C4 in the statistical models did not change this association. C3 was cross-sectionally associated with frequent asthma symptoms [OR per interquartile range of C3: 1.97 (95% CI: 1.20-3.24)] and prospectively with asthma symptoms [OR: 1.48 (95%CI: 1.04-2.09)], independent of BMI SDS. CONCLUSIONS AND CLINICAL RELEVANCE We showed no evidence for a role of hs-CRP, C3 and C4 in the association between BMI and asthma symptoms. C3 concentrations were associated with (frequent) asthma symptoms, independent of BMI.