Plasma apelin is lower in patients with elevated LDL-cholesterol.

Hypercholesterolemia is a major risk factor for atherosclerosis. Dysregulation of adipokines contribute to atherosclerotic diseases. Apelin has recently been shown to be secreted by the adipose tissue in association with hyperinsulinemia and inflammation. We searched plasma apelin levels in patients with elevated low density lipoprotein (LDL)-cholesterol having no additional disorder. Thirty-three patients with hypercholesterolemia and 50 age-, sex-, and body mass index-matched healthy controls were evaluated for their apelin, adiponectin and high sensitivity C-reactive protein (hsCRP) levels, and homeostasis model assessment (HOMA) indexes. Plasma apelin-12 and adiponectin were determined by ELISA and RIA, respectively. Plasma apelin levels were lower in patients with elevated LDL-cholesterol compared to healthy controls (p<0.001). Plasma adiponectin concentration was also lower in the dyslipidemic patients (p<0.001). hsCRP levels were similar in the two groups. Fasting plasma glucose was normal in both groups. HOMA indexes in the dyslipidemic group were higher than the controls (p=0.005). A mild to moderate negative correlation with HOMA and positive correlation with high density lipoprotein cholesterol of apelin was found in the dyslipidemic group. Plasma apelin is decreased in non-obese, non-diabetic and normotensive patients with elevated LDL-cholesterol. Low apelin levels in hypercholesterolemia seem associated with insulin resistance, which needs to be investigated in larger populations as well as in other atherosclerotic conditions.