Apelin: a peptide involved in cardiovascular risk in hemodialysis patients?

Inflammation, oxidative stress, and obesity are important features associated with pathogenesis of cardiovascular disease, a major contributor to the mortality of hemodialysis (HD) patients. Apelin is an adipokine involved in a variety of physiological functions; however, little is known about apelin in chronic kidney disease (CKD). Thus, the purpose of this study was to analyze apelin plasma levels in HD patients and verify whether there is any relationship with inflammation, oxidative markers, and obesity. Twenty-four HD patients [53.6 ± 14.4 years, 14 men, and body mass index (BMI) of 25.0 ± 4.2 kg/m(2)] were studied and compared with 15 healthy subjects (51.3 ± 13.5 years, 7 men, and BMI of 26.3 ± 3.7 kg/m(2)). Plasma apelin-12 and -36 were measured using the enzyme immunometric assay method. Plasma electronegative low-density lipoprotein [LDL(-)] levels were measured using ELISA method, and tumor necrosis factor-α, interleukin-6, leptin, and plasminogen activator inhibitor-1 levels were measured by a multiplex assay kit. C-Reactive protein (CRP) was determined by immunoturbidimetry. Anthropometric data were also evaluated. There was no difference between apelin-36 levels in HD patients (0.82 ± 0.60 ng/mL) and healthy subjects (0.83 ± 0.23 ng/mL). In contrast, apelin-12 levels were significantly higher in patients (0.34 ± 0.15 ng/mL vs. 0.24 ± 0.13 ng/mL in healthy subjects). TNF-α, CRP, and LDL(-) levels were higher in patients; however, there was no correlation among apelin-12 or -36 and inflammatory or oxidative markers. The adiposity parameters were also not associated with apelin-12 or -36. In conclusion, plasma apelin seems to be not associated with cardiovascular risk in HD patients.