Association of IL-1β and IL-1 receptor antagonist haplotypes with rate of decline in lung function in smokers

Background - There is increasing evidence that the cytokine network is central to the immunopathology of inflammatory airway diseases. The interleukin 1 (IL-1) receptor antagonist (IL-1RN) is a naturally occurring anti-inflammatory agent that binds to the IL-1 receptor but does not possess agonist activity. Each of the genes of the IL-1 locus on chromosome 2q14 is polymorphic. The IL1RN gene contains an 86 bp tandem repeat and allele 2 of this polymorphism has been associated with various inflammatory diseases. The IL-1β (IL1B) gene contains a promoter polymorphism (C-511T) that has been associated with inflammatory diseases and is in linkage disequilibrium with the IL1RN polymorphism. Methods - We investigated whether polymorphisms in the IL1B and IL1RN genes were associated with rate of decline of lung function. Genotypes were determined in 284 smokers with a rapid decline in lung function and 306 smokers with no decline in lung function. Results - None of the genotypes was associated with the rate of decline of lung function. However, the distribution of IL1B/IL1RN haplotypes was different between smokers with a rapid decline in lung function and those with no decline in lung function (p=0.0005). Conclusion - These results suggest that IL1B/IL1RN haplotypes play a role in the rate of decline in lung function in smokers.