High interleukin-6 plasma levels are associated with low HDL-C levels in community-dwelling older adults: the InChianti study.

Background: Low levels of high density lipoprotein cholesterol (HDL-C) are associated with increased incidence of coronary heart disease (CHD). A better understanding of the mechanisms leading to low HDL-C and CHD is essential for planning treatment strategies. Clinical studies have demonstrated that cytokines might affect both concentration and composition of plasma lipoproteins, including HDLs.

Methods: We investigated the possible association between low HDL-C levels, defined as < or =10th gender specific percentile, and circulating markers of inflammation (IL-1beta, TNF-alpha, IL-6, IL-10, IL-18, and CRP) in a population of 1044 community dwelling older Italian subjects from the InChianti study.

Results: Using logistic regression analysis we demonstrated that IL-6 levels (III versus I tertile, OR: 2.10; 1.10-3.75), TG (III versus I tertile OR: 27.45; 8.47-88.93), fasting insulin (III versus I tertile OR: 2.84; 1.50-5.42), and age (OR: 1.038; 1.002-1.075) were associated with low HDL-C independent of smoking, BMI, waist circumference, hypertension, diabetes, physical activity, alcohol intake, oral hypoglycaemics, CRP, IL-18, and TNF-alpha levels. The adjusted attributable risk of low HDL-C in the exposed group (III tertile of IL-6) was 54%.

Conclusions: The present study provides the epidemiological evidence that besides triglycerides, fasting insulin, and age, IL-6 is one of the main correlates of low HDL-C levels in older individuals.