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SummaryElevated plasma IL-6 levels have been implicated in the pathogenesis of coronary heart disease. We have investigated the association of two polymorphisms in the promoter of IL-6 (-572G>C and -174G>C) with levels of inflammatory markers and risk of myocardial infarction (MI) in a European study of MI survivors and age-matched controls from two high-risk centres in the North of Europe, and two low risk centres in the South. IL-6 and CRP levels were similar in controls in both regions, but were higher in cases. For the -174G>C polymorphism the rare -174C allele showed a regional difference in allele frequency, being more common in the North European group (0.43 vs 0.28; p < 0.0005), where -174C allele carriers showed an apparent reduced risk of MI compared to -174GG homozygotes (OR 0.53, 95%CI 0.32, 0.86). No such effect was observed in the South or with the -572G>C in either group. Neither genotype was associated with a significant effect on plasma IL-6 levels in either cases or controls. Furthermore, no regional difference was observed in the frequency of the -572G>C SNP, suggesting that these polymorphisms are unlikely to be contributing to the observed increased risk of cardiovascular disease in Northern Europe.

Summary. Although the potential role of plasminogen activator inhibitor-1 (PAI-1) in the development of coronary artery disease is strongly supported by its biological characteristics, results of clinical studies remain controversial. Objectives: To investigate whether plasma PAI-1 concentrations and the −675 4G/5G polymorphism located in the PAI-1 gene could constitute risk markers for myocardial infarction (MI). Patients and methods: We used a European case–control study, the HIFMECH study, comparing 598 men with MI and 653 age-matched controls. Results: Insulin resistance explained a major part of the variation in PAI-1 (24%) whereas inflammation had only a minor contribution (0.01%). For both cases and controls plasma PAI-1 concentrations were significantly higher in the North than the South, and in both regions were higher in individuals with MI compared with control subjects [overall odds ratio (OR) for a 1 SD increase = 1.54, 95% confidence interval (CI) 1.34, 1.77]. This difference was observed in all the centers studied. Overall, the difference between cases and control subjects remained significant after controlling for inflammation variables (OR = 1.30, 95% CI 1.08, 1.57), but lost significance after controlling for insulin resistance variables (OR = 1.17, 95% CI 0.98, 1.40). The 4G allele was associated with significantly higher PAI-1 levels in cases but not controls and, taken independently, did not modify the risk of MI (P = 0.9). However, a significant interaction was observed with both insulin or proinsulin and the risk of MI (P = 0.05 and 0.02, respectively), but not with triglycerides or body mass index (BMI). The insulin or proinsulin effect on risk was observed only in the carriers of the 4G/4G genotype. This interaction appeared not to be mediated by plasma PAI-1 antigen concentrations (P = 0.01 and 0.02 after adjustment for PAI-1 plasma levels). The interaction with proinsulin but not insulin remained statistically significant after further adjustment for other factors associated with insulin resistance (triglycerides and BMI) and C-reactive protein (P = 0.01). Conclusion: This study suggests that PAI-1 has a role in risk of MI in the presence of underlying insulin resistance. A significant interaction between insulin or proinsulin and the −675 4G/5G polymorphism was observed in risk for MI. The mechanisms for these interactions remain to be determined.