Interleukin 6 is associated with subclinical atherosclerosis: a link with soluble intercellular adhesion molecule 1

Among the markers of inflammation, a cytokine, interleukin (IL)-6, promotes the expression of intercellular adhesion molecule 1 (ICAM-1), C-reactive protein (CRP) synthesis, and leads to a series of procoagulant actions with potential major implications on the progression of atherosclerosis.

To analyse in a population-based study, the relationship between IL-6 and atherosclerotic lesions and the role of serum ICAM-1 and CRP on this relationship.

Among 1015 individuals randomly recruited between 1995 and 1997 in Haute-Garonne, a French region with a low cardiovascular risk, 953 subjects with complete data for all measurements were analysed. Common carotid intima-media thickness (IMT) and the presence of plaques in the carotid and femoral arteries were assessed by ultrasonography.

Quartiles of IL-6, serum ICAM-1 and CRP were positively associated with plaques and IMT. After adjustment for traditional risk factors, IL-6 (P < 0.001) and serum ICAM-1 (P < 0.002) remained positively associated with plaques but not CRP (P = 0.20). Neither IL-6, nor serum ICAM-1, nor CRP were independently associated with IMT. When serum ICAM-1 was entered into the model in addition to traditional risk factors and IL-6, the percentage of variance in the number of plaques explained by the model did not increase significantly.

IL-6 levels are associated with subclinical atherosclerotic lesions independently of traditional risk factors; the influence of IL-6 on ICAM-1 secretion may play a role in this association. These results argue the interest of IL-6 in the stratification of cardiovascular risk.