Copyright ©ERS Journals Ltd 2009 Joint effect of obesity and TNFA variability on asthma: two international cohort studiesFor affiliations, see Acknowledgements section. CORRESPONDENCE: M. Kogevinas, Centre for Research in Environmental Epidemiology, 88 Dr Aiguader Rd, Barcelona 08003, Spain. Fax: 34 933160575. E-mail: kogevinas{at}creal.cat
Keywords: Asthma, atopy, genetic polymorphism, obesity, tumour necrosis factor-
Received: September 12, 2008
Obesity is a risk factor for asthma. Adipose tissue expresses pro-inflammatory molecules including tumour necrosis factor (TNF), and levels of TNF are also related to polymorphisms in the TNF-
The European Community Respiratory Health Survey and the Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults used comparable protocols, questionnaires and measures of lung function and atopy. DNA samples from 9,167 participants were genotyped for TNFA -308 and lymphotoxin-
Obesity and TNFA were associated with asthma when mutually adjusting for their independent effects (odds ratio (OR) for obesity 2.4, 95% confidence interval (CI) 1.7–3.2; OR for TNFA -308 polymorphism 1.3, 95% CI 1.1–1.6). The association of obesity with asthma was stronger for subjects carrying the G/A and A/A TNFA -308 genotypes compared with the more common G/G genotype, particularly among nonatopics (OR for G/A and A/A genotypes 6.1, 95% CI 2.5–14.4; OR for G/G genotype 1.7, 95% CI 0.8–3.3).
The present findings provide, for the first time, evidence for a complex pattern of interaction between obesity, a pro-inflammatory genetic factor and asthma.
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