High Serum Osteoprotegerin Is Associated with Arterial Stiffness in Kidney Transplant Patients

High Serum Osteoprotegerin Is Associated with Arterial Stiffness in Kidney Transplant Patients

BANG-GEE HSU,^1,2 MING-HUI SHIH,³ YEN-CHENG CHEN,⁴ GUAN-JIN HO,⁴ TENG-YI LIN⁵ and MING-CHE LEE^2,4

¹Division of Nephrology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
²School of Medicine, Tzu Chi University, Hualien, Taiwan
³Department of Nursing, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
⁴Department of Surgery, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
⁵Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan

Osteoprotegerin (OPG) is a cytokine that regulates bone resorption by inhibiting osteoclastogenesis, and OPG has been implicated in the process that causes vascular stiffness. An increase in serum OPG level has been associated with the development of arterial stiffness. Kidney transplant (KT) patients are susceptible to aortic stiffness, which is considered to be a predictor of cardiovascular events in this patient population. Carotid-femoral pulse wave velocity (cfPWV) has emerged as a gold standard for non-invasive evaluation of aortic stiffness. The aim of this study was to evaluate the relationship between serum OPG concentration and cfPWV among KT patients. Fasting blood samples were obtained from 57 KT patients and their cfPWV was measured using applanation tonometry. The serum OPG levels were measured using an enzyme-linked immunosorbent assay. Univariable linear regression analysis showed that the cfPWV in KT patients was significantly and positively correlated with age, body weight, waist circumference, body mass index, log-creatinine, systolic blood pressure, diastolic blood pressure, pulse pressure, and the log-OPG concentration. KT patients with metabolic syndrome had higher cfPWV values than those without metabolic syndrome (P = 0.036), which indicates a higher incidence of aortic stiffness in this patient population. Multivariable forward stepwise linear regression analysis of the significant variables showed that the log-OPG (P = 0.001), the log-creatinine (P = 0.004), and the SBP (P = 0.005) remained as independent and positive predictors of cfPWV values. These findings indicate that serum OPG levels are positively associated with cfPWV in KT patients.

keywords —— arterial stiffness; carotid-femoral pulse wave velocity; kidney transplantation; osteoprotegerin; pulse pressure

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Tohoku J. Exp. Med., 2015, 236, 247-253

Correspondence: Ming-Che Lee, Department of Surgery, Buddhist Tzu Chi General Hospital, No. 707, Section 3, Chung-Yang Road, Hualien 970,Taiwan.

e-mail: mingche1229@gmail.com