Pulse wave velocity and proteins regulating vascular calcification and bone mineralization in patients treated with peritoneal dialysis

Diabetes mellitus modifies the association between chronic kidney disease-mineral and bone disorder biomarkers and aortic stiffness in peritoneal dialysis patients

This study aimed to investigate the relationship of four chronic kidney disease-mineral and bone disorder (CKD-MBD) biomarkers, including intact parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), soluble klotho, and fetuin-A, with aortic stiffness in peritoneal dialysis (PD) patients, comparing those with and without diabetes mellitus (DM). A total of 213 patients (mean age 58 ± 14 years; 81 (38.0%) patients with DM) were enrolled. Their aortic pulse wave velocity (PWV) was measured using pressure applanation tonometry, while serum intact PTH, FGF23, α-klotho, and fetuin-A levels were measured using enzyme-linked immunosorbent assay. Overall, patients with DM had higher aortic PWV than those without (9.9 ± 1.8 vs. 8.6 ± 1.4 m/s, p < 0.001). Among the four CKD-MBD biomarkers, FGF23 levels were significantly lower in DM group (462 [127-1790] vs. 1237 [251-3120] pg/mL, p = 0.028) and log-FGF23 independently predicted aortic PWV in DM group (β: 0.61, 95% confidence interval: 0.06-1.16, p = 0.029 in DM group; β: 0.10, 95% confidence interval: - 0.24-0.45, p = 0.546 in nonDM group; interaction p = 0.016). In conclusion, the association between FGF23 and aortic PWV was significantly modified by DM status in PD patients.

Relationship between aortic pulse wave velocity, selected proinflammatory cytokines, and vascular calcification parameters in peritoneal dialysis patients

INTRODUCTION

Vascular calcification and arterial stiffening are cardiovascular risk factors among chronic kidney disease patients. Elevated aortic pulse wave velocity (AoPWV) is an independent predictor of increased cardiovascular morbidity and mortality.

OBJECTIVES

The aim of the study was to analyze the relationships between inflammatory and vascular calcification parameters and arterial wall stiffness in chronic kidney disease (CKD) patients treated by peritoneal dialysis.

PATIENTS AND METHODS

The study included 57 patients (27 women and 30 men) aged from 19 to 75 years (mean age 53 ± 13), treated by peritoneal dialysis during 4-100 months (mean 30.4 months). The concentrations of albumin, lipids, interleukin-6 (IL-6), IL-18, high-sensitive C-reactive protein, transforming growth factor-β1 (TGF-β1), osteocalcin, osteoprotegerin (OPG), fibroblast growth factor 23, fetuin A, parathyroid hormone (iPTH), total calcium (Ca), and phosphates (Pi) were measured. AoPWV was performed using a tonometric method, common carotid artery intima-media thickness (CCA-IMT) by ultrasonography evaluation, and calcium scoring (CaSc) with multirow spiral computed tomography (MSCT).

RESULTS

In univariate analysis, AoPWV correlated negatively with osteocalcin (R = -0.37; P = 0.005) and positively with OPG (R = 0.41; P = 0.002). Additionally, AoPWV was significantly positively associated with inflammatory parameters: IL-6 (R = 0.35; P = 0.009), TGF-β1 (R = 0.27; P = 0.047), and white blood cell (WBC) count (R = 0.33; P = 0.01). There were also positive correlations between AoPWV and imaging data: CCA-IMT (R = 0.32; P = 0.02) and CaSc (R = 0.38; P = 0.004). AoPWV did not correlate with calcium, phosphate, Ca × Pi index, or iPTH concentration. After multiple adjustments, osteocalcin was the only significant predictor of AoPWV. In logistic regression adjusted for age, hypertension, and mean arterial pressure at AoPWV evaluation, only osteocalcin was significantly associated with high (above median) AoPWV values [odds ratio 0.96 (0.92-0.99) per unit increase in osteocalcin].

CONCLUSION

OPG concentration and some inflammatory markers (WBC count, IL-6, TGF-β1) influenced the severity of arterial wall stiffness in CKD patients. Measurement of osteocalcin seems to be the best predictor of AoPWV.

A cut-off value of plasma osteoprotegerin level may predict the presence of coronary artery calcifications in chronic kidney disease patients

BACKGROUND

Expression of bone proteins resulting from transdifferentiation of vascular smooth muscle cells into osteoblasts suggests that vascular calcifications are a bioactive process. Osteoprotegerin (OPG) could play a key role in bone-vascular calcification imbalance and could be a marker of vascular calcification extent and progression. The purpose of this study was to evaluate relationships between vascular risk biomarkers (including classic risk factors and OPG) and coronary artery calcification (CAC) extent in chronic kidney disease (CKD) patients and to establish within the markers the appropriate cut-off value to predict CAC.

METHODS

A total of 133 non-dialyzed CKD patients at various stages of kidney disease [75 males/58 females, median age: 69.9 (27.4-94.6)] were enrolled, excluding extrarenal replacement therapy patients. All underwent chest multidetector computed tomography for CAC scoring. Blood samples were collected for measurement of vascular risk markers (kidney disease, inflammation, nutrition, calcium phosphate and OPG). A potential relationship between CAC and these biological markers was investigated, and a receiver-operating characteristic (ROC) curve was designed thereafter to identify a cut-off value of involved markers that best predicted the presence of CAC.

RESULTS

After adjustment for age, diabetes, smoking and gender, among biological markers, only low-estimated glomerular filtration rate using Modification of Diet in Renal Disease [OR = 3.63 (1.10-12.02)], high FEPO(4) [OR = 3.99 (1.17-13.6)] and high OPG levels [OR = 8.54 (2.14-34.11)] were associated with the presence of CAC. A protective effect of 1.25(OH)(2) vitamin D [OR = 0.20 (0.05-0.79)] and LDL cholesterol [OR = 0.27 (0.08-0.94)] on CAC was also observed. ROC curve analysis showed that the OPG best cut-off value predicting CAC was 757.7 pg/mL.

CONCLUSION

These results suggest that a CAC increase is strongly associated with a plasma OPG increase in CKD patients. The values of OPG >757.7 pg/mL allow us to predict the presence of CAC in these patients.

Serum osteoprotegerin level, carotid-femoral pulse wave velocity and cardiovascular survival in haemodialysis patients

BACKGROUND

Osteoprotegerin (OPG) is a marker and regulator of arterial calcification, and it is related to cardiovascular survival in haemodialysis patients. The link between OPG and aortic stiffening--a consequence of arterial calcification--has not been previously evaluated in this population, and it is not known whether OPG-related mortality risk is mediated by arterial stiffening.

METHODS

At baseline, OPG and aortic pulse wave velocity (PWV) were measured in 98 chronic haemodialysis patients who were followed for a median of 24 months. The relationship between OPG and PWV was assessed by multivariate linear regression. The role of PWV in mediating OPG related cardiovascular mortality was evaluated by including both OPG and PWV in the same survival model.

RESULTS

At baseline mean (standard deviation) PWV was 11.2 (3.3) m/s and median OPG (interquartile range) was 11.1 (7.5-15.9) pmol/L. There was a strong, positive, linear relationship between PWV and lnOPG (P = 0.009, model R(2) = 0.540) independent of covariates. During follow-up 23 patients died of cardiovascular causes. In separate univariate survival models both PWV and lnOPG were related to cardiovascular mortality [hazard ratios 1.31 (1.14-1.50) and 8.96 (3.07-26.16), respectively]. When both PWV and lnOPG were entered into the same model, only lnOPG remained significantly associated with cardiovascular mortality [hazard ratio 1.11 (0.93-1.33) and 7.18 (1.89-27.25), respectively).

CONCLUSION

In haemodialysis patients OPG is strongly related to PWV and OPG related cardiovascular mortality risk is, in part, mediated by increased PWV.