Objective: Interleukin (IL)-18 has been associated with severity of atherosclerosis and discussed to predict cardiovascular (CV) events. We have previously shown that the IL-18+183 G-allele significantly reduces IL-18 levels. This study was aimed to investigate the prognostic significance of the IL-18+183 A/G polymorphism (rs5744292), single and in coexistence with the matrix metalloproteinase (MMP)-9 -1562 C/T (rs3918242) polymorphism, in patients with stable coronary artery disease (CAD). Serum levels of IL-18, MMP-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were additionally assessed.
Methods: 1001 patients with angiographically verified CAD were genotyped and the biomarkers were measured accordingly. After two years follow-up, 10.6% experienced new clinical events; acute myocardial infarction (AMI), stroke, unstable angina pectoris and death.
Results: The IL-18+183 G-allele associated with 35% risk reduction in composite endpoints after adjusting for potential covariates (p = 0.044). The IL-18+183 AA/MMP-9 -1562 CT/TT combined genotypes associated with a significant increase in risk of composite endpoints (OR = 1.87; 95% CI = 1.13-3.11, p = 0.015, adjusted). Patients with clinical events presented with significantly higher IL-18 levels as compared to patients without (p = 0.011, adjusted). The upper tertile of IL-18 levels associated with an increase in risk of AMI as compared to lower tertiles (OR = 2.36; 95% CI = 1.20-4.64, p = 0.013, adjusted).
Conclusion: The IL-18+183 A/G polymorphism, single and in combination with MMP-9 genotypes, may influence the risk of clinical events in stable CAD patients.