Polymorphisms in interleukin-1B and its receptor antagonist genes and the risk of chronic obstructive pulmonary disease in a Korean population: a case–control study

SummaryBackgroundAlthough several studies have evaluated the association between interleukin-1B (IL1B) polymorphisms and the risk of chronic obstructive pulmonary disease (COPD), most of these studies have focused on −511C → T and −31T → C polymorphisms, and the results of these studies have been inconsistent. This study was conducted to investigate the association between four potentially functional polymorphisms of the IL1B gene (−3737C → T, −1464G → C, −511C → T, and −31T → C) and the risk of COPD. In addition, we examined a potential interaction of the IL1B polymorphisms with the VNTR polymorphism of the IL-1 receptor antagonist (IL1RN) gene in determining the risk of COPD.MethodsThe IL1B and IL1RN genotypes were determined in 311 COPD patients and 386 healthy controls.ResultsIndividuals with at least one variant allele of the −511C → T and −31T → C polymorphisms were at a significantly increased risk for COPD when compared to carriers with each homozygous wild-type allele [adjusted odds ratio (OR) 1.53, 95% confidence interval (CI) 1.03–2.26, P = 0.03; and adjusted OR 1.50, 95% CI 1.02–2.24, P = 0.04, respectively]. When the COPD cases were stratified according to disease severity, the presence of at least one −511T and −31C alleles was significantly associated with severe COPD (adjusted OR 2.80, 95% CI 1.47–5.33, P = 0.002; and adjusted OR 2.33, 95% CI 1.24–4.40, P = 0.01, respectively), however, there was no significant association between the −511C → T and −31T → C genotypes and mild-to-moderate COPD. In addition, individuals carrying at least one IL1RN*2 allele were at a significantly lower risk for COPD compared to subjects carrying no IL1RN*2 allele (adjusted OR 0.51, 95% CI 0.26–0.98, P = 0.04). In haplotype/diplotype analyses, individuals with one or two copies of the IL1B CCTC haplotype that carried the risk allele at all of the −3737C → T, −1464G → C, −511C → T, and −31T → C loci, were at a significantly increased risk of severe COPD when compared with subjects with zero copy of the CCTC haplotype (adjusted OR 1.96, 95% CI 1.16–3.29, P = 0.01).ConclusionThese findings suggest that polymorphisms in the IL1B and IL1RN genes might be useful markers for determining genetic susceptibility to COPD in a Korean population.