Interleukin-6 promoter polymorphism and cardiovascular risk factors: the Health 2000 Survey.

Objective: Inflammatory factors modify the risk of cardiovascular diseases and atherosclerosis. The single base genetic polymorphism in the promoter region of inflammatory cytokine interleukin-6 (IL6 -174 G>C, rs1800795) is associated with the variation of IL-6 production. The aim of this study was to investigate whether IL6 -174 G>C is associated with the risk factors and early markers of atherosclerosis.

Methods: As part of Finnish Health 2000 Study, we performed carotid artery ultrasound examinations, IL6 -174 G>C genotyping and cardiovascular risk factor determination for 1334 subjects aged 46-76 years.

Results: In men, serum total cholesterol was higher in IL6 -174 GG (5.70+/-0.88mmol/L) than in the GC (5.51+/-0.98mmol/L) or CC (5.38+/-0.97mmol/L, mean+/-SD, p=0.0059) groups. The same order was seen in LDL-C (GG 3.64+/-0.83mmol/L, GC 3.41+/-0.88mmol/L, CC 3.30+/-0.91mmol/L, p=0.0017). The opposite association was observed with plasma fasting glucose levels (GG 5.93+/-0.97, GC 6.11+/-1.34, CC 6.34+/-1.59mmol/L, p=0.043) and BMI (GG 26.8+/-3.42, GC 27.5+/-4.32, CC 28.0+/-3.81kg/m(2), p=0.027). IL6 -174 allele C homozygous men indicated a trend towards higher systolic blood pressure. IL6 -174 G>C was not associated with carotid artery compliance, intima media thickness or CRP. The effect size of IL6 -174 G>C on cardiovascular risk factors was not significant in women. These results suggest that IL6 -174 G>C modifies the levels of several metabolic risk factors of atherosclerosis in men.