The Relationship Between Osteoprotegerin/RANKL Axis and Arterial Stiffness in Osteopenic/Osteoporotic Renal Transplantation Recipients

OBJECTIVE: Cardiovascular diseases are the main reason of death in patients with renal transplantation (Rtx). Osteoprotegerin (OPG) is produced by osteoblasts and is linked to increased cardiovascular risk in Rtx. OPG acts as a decoy receptor binding receptor activator of nuclear factor kappa-B ligand (RANKL) and this interaction plays a role in bone resorption and vascular function. This study aimed to investigate the relation between OPG, RANKL, osteoporosis and arterial stiffness in Rtx patients.

MATERIAL and METHODS: This cross-sectional study included 80 adult Rtx recipients. Femoral neck mineral density was obtained by dual-energy X-ray absorptiometry. Serum OPG and RANKL were measured by the ELISA method. Pulse-wave analysis was measured in the carotid and femoral arteries using a pulse wave velocity (PWV) machine.

RESULTS: Patients were divided into two groups as normal (n:24) and osteopenia/osteoporosis group (n:56). Body mass index was significantly lower in the osteopenic/osteoporotic group compared to the normal group. Pulse wave velocity was positively correlated with age (r:0.204,p:0.072), osteoprotegerin (r:0.219,p:0.052), calcium x phosphate product (r:0.605,p:<0.001), and systolic blood pressure (r:0.198,p:0.058) and negatively correlated with RANKL (r:-0.261,p:0.020) and creatinine clearance (r:-0.220,p:0.051). PWV was independently predicted by calcium x phosphate product but not creatinine clearance, RANKL, osteoprotegerin and systolic blood pressure.

CONCLUSION: In our study, serum calcium x phosphate product but not OPG and RANKL levels were found to be the main predictor of arterial stiffness in Rtx patients.