Synergistic effect of-174 G/C polymorphism of the interleukin-6 gene promoter and 469 E/K polymorphism of the intercellular adhesion molecule-1 gene in Italian patients with history of ischemic stroke

Background and Purpose-Interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) are involved in the pathogenetic mechanisms responsible for several ischemic cardiovascular disorders, including cerebral ischemia. IL-6 and ICAM-1 plasma levels and/or function may be genetically influenced. We sought to evaluate distribution and reciprocal interaction of IL-6 G/C gene promoter polymorphism and ICAM-1 E/K gene polymorphism in Italian patients with history of ischemic stroke. Methods-One hundred nineteen patients with history of ischemic stroke and 133 age- and sex-matched controls were studied. IL-6 and ICAM-1 genotypes were evaluated by polymerase chain reaction and restriction enzyme analysis. Results-The GG genotype of -174 IL-6 G/C gene polymorphism was significantly associated with history of ischemic stroke at both univariate (P<0.0001) and multivariate analysis (odds ratio [OR], 8.6; P<0.0001). Additionally, the EE genotype of ICAM-1 E/K gene polymorphism was significantly more common in the group of patients with history of ischemic stroke (P=0.003) and was an independent variable associated with stroke history (OR, 4.0; P=0.002). Interestingly, a further increased risk of stroke was found in subjects who concomitantly carry the IL-6 GG and ICAM-1 EE genotypes (IL-6 GG/ICAM-1 EE double-homozygous subjects) (OR, 10.1; P=0.004). Conclusions-There is a synergistic effect of IL-6 G/C and ICAM-1 E/K gene polymorphisms in patients with stroke history. Reciprocal interactions between genotypes may contribute in determining the risk profile for cardiovascular diseases and may merit further investigation as potential therapeutic targets.