Interleukin-1 gene cluster variants and abdominal aortic aneurysms

Inflammation is a key factor in the pathogenesis of abdominal aortic aneurysms (AAA). Interleukin 1 (IL-1), a fundamental regulator of the inflammatory cascade, has been shown to be involved in this process. Several functional polymorphisms in the IL-1 gene cluster are known. In this matched case-control study, we investigated a potential association between six genetic variants in IL-1 and IL-1 receptor antagonist (IL-1 RN) with AAA. We enrolled 405 individuals, 135 consecutive patients with AAA were individually age- and sex-matched to 270 patients with coronary artery disease (CAD).Traditional cardiovascular risk factors and IL-1 genotypes were determined, and the distribution of six single nucleotide polymorphisms were compared between patients and controls by multivariable conditional logistic regression analysis: IL-1A (-889) C>T, IL-1A (+4845) G>T, IL-1B (-511) C>T, IL-1B (-31) C>T, IL-1B (+3954) C>T and IL-1RN (+2018) C>T. IL-1A (-889) C>T and IL-1A (+4845) G>T (kappa 0.98,95% CI 0.96 to 1.00), and IL-1B (-511) C>T and IL-1B (-31) C>T (kappa 0.98, 95% CI 0.96 to 1.00) were closely linked, therefore IL-1A (-889) C>T and IL-1B (-31) C>T were not considered for further analyses. None of the 4 remaining polymorphisms showed a significant association with AAA: IL-1RN (+2018) C>T (p = 0.061), IL-1B (+3954) C>T (p = 0.51), IL-1B (-511) C>T (p = 0.61) and IL-1A (+4845) G>T (p = 0.81). No significant first-degree interactions between the genetic variants and AAA were detected. In conclusion,these six genetic variants in the interleukin- I gene cluster do not seem to play a clinically relevant role in the pathogenesis of AAA, although we cannot rule out the existence of higher degree gene-gene or gene-environment interactions.