Abstract 1652: Association of Interleukin-6 With Impaired Brachial Artery Endothelial Function in the Multi-Ethnic Study of Atherosclerosis (MESA)
Background. Endothelial dysfunction is a hallmark of early atherosclerosis. Flow-mediated dilation (FMD) is a non-invasive, reliable method for the assessment of endothelial function. Advancements in understanding of the pathobiology of atherothrombosis have implicated inflammation as a contributor to the progression of atherosclerotic vascular disease, although its precise role remains uncertain.
Hypothesis. We investigated the hypothesis that increased levels of systemic inflammatory markers are associated with an impairment of endothelial function.
Methods. We assessed brachial artery FMD in 3,404 participants in the Multi-Ethnic Study of Atherosclerosis (mean age 61 years, 50.3% women) and measured serum concentrations of interleukin (IL)-6, C-reactive protein (CRP), and tumor necrosis factor (TNF)-alpha R1. Spearman correlation coefficients were used to evaluate the association of each inflammatory marker with FMD, adjusting for the effect of other variables that may affect FMD.
Results. The mean (+/− S.D.) baseline brachial artery diameter was 3.8mm (+/−0.6) for women and 4.8 (+/−0.7) for men. The mean FMD for women was 0.18mm (+/−0.1) or 4.8%. The mean FMD for men was 0.18 (+/−0.11) or 3.9%. There was a significant inverse correlation between IL-6 levels and FMD (−0.115; p<0.001) but no significant correlation between either CRP (−0.010; p=0.575) or TNF-alpha (−0.054; p=0.148) and FMD. The inverse correlation between IL-6 levels and FMD remained significant (−0.036; p=0.038) after adjustment for age, gender, race/ethnicity, diabetes, LDL-C, triglycerides, hypertension, waist circumference, baseline brachial diameter, and medications that may alter inflammation. There was no significant difference in the association of IL-6 and FMD between the race/ethnic groups on multivariate analysis.
Conclusions. In our large, multi-ethnic community-based sample, we found that increased levels of the pro-inflammatory cytokine IL-6 is associated with impaired endothelial function as assessed by FMD. Elevated IL-6 concentrations may reflect a state that promotes vascular inflammation and the development of subclinical atherosclerosis, independent of traditional cardiovascular risk factors.