Apelin, a Novel Adipocytokine, in Relation to Endothelial Function and Inflammation in Kidney Allograft Recipients

Apelin, a newly discovered adipocytokine produced by white adipose tissue, is also expressed in kidney and heart. It has been reported that apelin is related to echocardiographic features in hemodialyzed patients. Cardiovascular disease is a major contributor to the mortality and morbidity among patients with chronic renal failure as well as kidney allograft recipients. The aim of this study was to assess the association between apelin and coronary artery disease (CAD) among kidney allograft recipients. We investigated plasma apelin levels in 100 clinically stable, kidney allograft recipients with versus without CAD. We also assessed markers of endothelial cell injury—von Villebrand factor (vWF), thrombomodulin, intracellular adhesion molecule (ICAM), and CD146; markers of inflammation—high-sensitivity-reactive protein (hsCRP); other hemostatic parameters—tissue plasminogen activator (tPA) and its inhibitor (PAI-1); as well as other adipocytokines—adiponectin and resistin—using commercially available kits. Markers of endothelial dysfunction and inflammation were significantly elevated among patients with CAD levels, as well as with CAD or diabetes, compared with those without CAD. Apelin was significantly lower among patients with CAD, but higher in diabetic patients. Apelin content was similar in hypertensive versus normotensive kidney allograft recipients. We observed significant correlations between apelin and ICAM, resistin, adiponectin, calcium, phosphate, alanine and aspartate aminotransferase levels, with CAD or diabetes. Upon multiple regression analysis as well as CAD, adiponectin, and ICAM were predictors of apelin. Apelin was significantly reduced in kidney allograft recipients with CAD; its level was predicted by the presence of CAD, endothelial damage, or inflammation. Apelin and other adipocytokines may be associated with inflammation and its clinical consequences.