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 ≤10th gender specific percentile, and circulating markers of inflammation (IL-1β, TNF-α, 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-α 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.