Association between VEGF Receptors and Baseline Peritoneal Transport Status in New Peritoneal Dialysis Patients

Gene polymorphisms of VEGF and KDR are associated with initial fast peritoneal solute transfer rate in peritoneal dialysis

Background

Peritoneal dialysis (PD) is an effective and successful renal replacement therapy. The baseline peritoneal solute transfer rate (PSTR) is related to local membrane inflammation and may be partially genetically determined. Herein, we focused on vascular endothelial growth factor (VEGF) and its receptor, kinase insert domain containing receptor (KDR).

Methods

This study recruited 200 PD patients from Renji Hospital in Shanghai, China. We analysed the association between the polymorphisms of VEGF and KDR and the 4-hour dialysate-to-plasma ratio for creatinine (4 h D/P Cr), which was measured between one and three months after initiating PD.

Results

The CC genotype in VEGF rs3025039 and the AA genotype in KDR rs2071559 were both positively associated with a fast baseline PSTR (VEGF rs3025039 CC vs. TT + TC: 0.65 ± 0.12 vs. 0.61 ± 0.11; P = 0.029; KDR rs2071559 AA vs. GA + GG: 0.65 ± 0.12 vs. 0.62 ± 0.12; P = 0.039).

Conclusion

Baseline PSTR was partly determined by VEGF and KDR gene polymorphisms.

Angiogenic Factors and Risks of Technique Failure and Cardiovascular Events in Patients Receiving Peritoneal Dialysis

BACKGROUND

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor family that acts as a pleiotropic cytokine capable of stimulating angiogenesis and accelerating atherogenesis. Soluble fms-like tyrosine kinase-1 (sFlt-1) antagonizes PlGF action. Higher levels of PlGF and sFlt-1 have been associated with cardiovascular events in patients with chronic kidney disease, yet little is known about their relationship with adverse outcomes in patients on peritoneal dialysis (PD). The aim of this study was to investigate the association of PlGF and sFlt-1 with technique survival and cardiovascular events.

METHODS

We measured serum levels of PlGF and plasma levels of sFlt-1 in 40 PD patients at Nara Medical University.

RESULTS

PlGF and sFlt-1 levels were significantly correlated with the dialysate-to-plasma ratio of creatinine (r = 0.342, p = 0.04 and r = 0.554, p < 0.001) although PlGF and sFlt-1 levels were not correlated with total creatinine clearance and total Kt/V. Additionally, both PlGF and sFlt-1 levels were significantly higher in patients with high transport membranes compared to those without (p = 0.039 and p < 0.001, respectively). Patients with PlGF levels above the median had lower technique survival and higher incidence of cardiovascular events than patients with levels below the median, with hazard ratios of 11.9 and 7.7, respectively, in univariate Cox regression analysis. However, sFlt-1 levels were not associated with technique survival or cardiovascular events (p = 0.11 and p = 0.10, respectively).

CONCLUSION

Elevated PlGF and sFlt-1 are significantly associated with high transport membrane status. PlGF may be a useful predictor of technique survival and cardiovascular events in PD patients.

Supplementation with high-dose trans-resveratrol improves ultrafiltration in peritoneal dialysis patients: a prospective, randomized, double-blind study

BACKGROUND

Ultrafiltration (UF) failure mostly contributes to technical failure in peritoneal dialysis (PD) patients, and one of its responsible factors is peritoneal angiogenesis. Resveratrol has been proposed to have an angiogenesis-ameliorating effect on tumor patients. We hypothesize trans-resveratrol has beneficial effects on angiogenesis-related markers in PD patients.

METHODS

In this prospective, randomized, and double-blind trial, 72 patients were randomly assigned to 12-week treatment of low-dose or high-dose (150 or 450 mg/d) trans-resveratrol or a placebo. Visits were scheduled at 0, 4, 8, and 12 weeks after treatment. Clinical indices including 24-hour UF volume, UF rate, 24-hour urine volume, residual renal function, and dialysis adequacy (kt/v) were measured. Angiogenesis markers including vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1), angiopoietin-2 (Ang-2), tyrosine kinase 2 (Tie-2), and thrombospondin-1 (Tsp-1) in peritoneal effluent were also assessed by enzyme-linked immunosorbent assay.

RESULTS

Finally, 64 out of 72 patients were analyzed, 18 in the high-dose group, 22 in the low-dose group, and 24 in the placebo group. Over the 12-week period, patients in the high-dose group [mean change from baseline (95% CI): 171.4 (141.3-201.5) (mL), p = 0.003 (Net UF); 11.3(10.5-12.1) (mL/h), p = 0.02 (UF rate)] or the low-dose group [mean change from baseline (95% CI: 98.1 (49.5-146.7) (mL), p = 0.007 (Net UF); 6.5 (4.4-8.6) (mL/h), p = 0.04 (UF rate)] versus the placebo group had a significantly greater improvement in mean net UF volume and UF rate. The appearance rates of VEGF, Flk-1, and Ang-2 were more significantly reduced (appearance rates of Tie-2 and Tsp-1 increased) in the high-dose group versus the placebo group, but not in the low-dose group.

CONCLUSION

Supplementation with trans-resveratrol is beneficial to improve ultrafiltration in PD patients, and high-dose supplementation may improve ultrafiltration by ameliorating angiogenesis induced by conventional lactate-buffered PD solutions.

Cyclooxygenase-2 and vascular endothelial growth factor expressions are involved in ultrafiltration failure

BACKGROUND

Long-term peritoneal dialysis (PD) is associated with ultrafiltration failure (UFF). The aim of the study was to investigate changes in cyclooxygenase-2 (COX-2), vascular endothelial growth factor A (VEGF-A), and vascular endothelial growth factor C (VEGF-C) expressions in a rat model of UFF induced by PD solution.

METHODS

Sprague-Dawley rats were divided into six groups (n = 8/group): normal untreated control group, sham operation group, uremic group (nephrectomy without PD), uremic 2-wk PD group (PD solution for 2 wk), uremic 4-wk PD group (PD solution for 4 wk), and uremic 4-wk PD + celecoxib group (PD solution plus COX-2 inhibitor celecoxib 20 mg/kg for 4 wk). Peritoneal function was determined by peritoneal equilibration test. Peritoneal morphology was determined by hematoxylin and eosin and Masson staining. Microvessel and lymphatic microvessel formation was determined by immunohistochemistry. COX-2, VEGF-A, and VEGF-C expressions were determined by real-time polymerase chain reaction and immunohistochemistry.

RESULTS

Uremic rat model was successfully established. PD-induced peritoneal morphologic changes associated with UFF, characterized by inflammation, edema, and collagen accumulation. PD solution increased the density of microvessels marked by CD31 (microvessel density) and lymphatic microvessels marked by LYVE-1 (lymphatic vessel density) in peritoneum. COX-2, VEGF-A, and VEGF-C expression levels in the uremic 4-wk PD group were higher than those in the uremic group (all P < 0.05). All these changes were partially reversed by celecoxib. VEGF-A and VEGF-C protein expressions were positively correlated with microvessel density and lymphatic vessel density formation.

CONCLUSIONS

COX-2 could increase VEGF-A and VEGF-C expressions in peritoneal tissue, resulting in increased formation of peritoneal microvessels and lymphatic microvessels, playing pivotal roles in the development of UFF.