Apelin Serum Levels are not Associated with Early Atherosclerosis or Fat Distribution in Young Subjects with Increased Risk for Type 2 Diabetes

Abstract

Apelin is proposed to possess protective cardiovascular properties and may furthermore promote favorable effects on glucose metabolism. First data in humans seem to support this hypothesis. Therefore we aimed to assess the meaning of apelin as an early risk indicator in young subjects prone to atherosclerosis and type 2 diabetes. Furthermore we examined the association of apelin serum levels with insulin sensitivity/resistance and body fat distribution as probably dependent cardiovascular risk factors. We examined 344 individuals (f/m=216/128, mean age 46±1 years) with an increased risk for type 2 diabetes. Apelin-36 serum levels were measured via ELISA. Endothelial dysfunction and intima media thickness (IMT) were assessed using high resolution ultrasound. Visceral adipose tissue (VAT) was measured with an axial T1-weighted fast spin echo technique with a 1.5 T whole-body imager. According to the study population's age, FMD (6.4±0.2%) and IMT (0.56±0.01 mm) were within the expected ranges. Gender or age had no influence on serum apelin levels. When looked at early stages of atherosclerosis, we could not detect a significant correlation between apelin serum levels and FMD or IMT. Blood pressure as well was unaffected by serum apelin levels. Furthermore, neither parameters of insulin sensitivity like insulin sensitivity index (ISI), nor fat distribution like BMI, grade of adiposity, total adipose tissue or VAT were associated with apelin serum levels. We conclude that apelin serum levels do not add further information on the cardiovascular-, or diabetes risk pattern in a diabetes prone population.

Adipokines: a novel link between adiposity and carotid plaque vulnerability

“…In contrast, Rittig et al. (2011) [19] have recently documented the absence of relationship between early carotid atherosclerosis and apelin levels in young individuals with increased risk of type 2 diabetes. Compared to that study, we enrolled patients with advanced carotid atherosclerosis and multiple cardiovascular risk factors, which could explain the above divergent results.…”

Adipose tissue and vascular inflammation in coronary artery disease

“…However from a pathophysiological point of view, some conflicting data have been reported. For example, Rittig et al [166] observed that plasma apelin levels are not associated with early stages of atherosclerosis in young subjects prone to atherosclerosis and type 2 diabetes. Interestingly, other studies in animal models suggested a role of apelin-APJ system in vasculature oxidative stress.…”

Apelin and APJ, a novel critical factor and therapeutic target for atherosclerosis

“…Rittig et al [3] found that serum apelin-36 levels were not associated with early AS using apelin-36 as an early risk indicator in young subjects prone to AS. However, plasma apelin levels were lower in patients with elevated low-density lipoprotein-cholesterol (LDL-C) compared with healthy controls [4].…”