Background: Pro-inflammatory cytokine interleukin-1b (IL-1b) plays a role in atherosclerosis. The results of several studies on the association between polymorphism of the IL-1b gene cluster and the course of coronary atherosclerosis have been inconclusive.
Aim: To investigate retrospectively whether the patients with the most common variants of polymorphism of the IL-1b gene cluster differ with respect to localisation and extent of coronary atherosclerosis to a degree which may influence the treatment strategy.
Methods: Ninety-two consecutive out-patients (age 39-83, male sex 74%) with coronary artery disease confirmed by angiography were included. In this group, 23 patients underwent coronary artery bypass grafting (CABG) and 69 percutaneous coronary interventions (PCI) of whom in 16 repeated treatment was performed. The polymorphisms of the IL-1b gene - transition C/T at -511 and -31 position - as well as of the IL-1 receptor antagonist gene (IL-1RN) - an 86-base pair variable-number tandem repeat in intron 2 - were determined by PCR. Out of the 54 theoretically possible combinations of polymorphisms, 17 were found in the studied group. The three most common combinations of polymorphisms were selected. The fraction of patients treated by means of primary or elective percutaneous coronary intervention (pPCI, ePCI) and by means of CABG were compared between the subgroups with one of the 3 most common combinations of polymorphisms.
Results: The most frequent combinations of polymorphisms were - Variant A: -31 C/T, -511C/T, RN 1/1 - 32.6%; Variant B: -31T/T, -511C/C, RN 1/1 - 27.1%; Variant C: -31C/T, -11C/T, RN 1/2 - 10.8%. The remaining patients (29.5%) represented 14 variants present in very small subgroups consisting only of 1, 2 or 3 persons. Statistical analysis showed that patients with the second most common variant of studied polymorphisms (variant B) were significantly more frequently treated with CABG in comparison to the two other variants. Also, repeated PCI was most frequent in this subgroup.
Conclusion: The data presented here suggest that carriers of the two relatively frequent variants of the IL-1b gene at -31 and -511 position, i.e. -31TT and -511CC, are at a higher risk of developing coronary artery disease requiring surgical treatment or two-stage percutaneous angioplasty.