Effect of different dialysis modalities on microinflammatory status and endothelial damage

Abstract

Background and objectives: We studied the relationship between microinflammation and endothelial damage in chronic kidney disease (CKD) patients on different dialysis modalities.

Design, setting, participants, & measurements: Four groups of CKD stage 5 patients were studied: 1) 14 nondialysis CKD patients (CKD-NonD); 2) 15 hemodialysis patients (HD); 3) 12 peritoneal dialysis patients with residual renal function >1 ml/min (PD-RRF >1); and 4) 13 peritoneal dialysis patients with residual renal function <or=1 ml/min (PD-RRF <or=1). Ten healthy subjects served as controls. CD14(+)CD16(+) cells and apoptotic endothelial microparticles (EMPs) were measured by flow cytometry. Serum vascular endothelial growth factor (VEGF) was measured by ELISA.

Results: CKD-NonD and HD patients had a higher percentage of CD14(+)CD16(+) monocytes than PD groups and controls. CD14(+)CD16(+) was similar in the PD groups, regardless of their RRF, and controls. The four uremic groups displayed a marked increase in apoptotic EMPs and VEGF compared with controls. Apoptotic EMPs and VEGF were significantly higher in HD patients than in CKD-NonD and both PD groups. However, there were no significant differences between CKD-NonD and the two PD groups. There was a correlation between CD14(+)CD16(+) and endothelial damage in CKD-NonD and HD patients, but not in PD and controls.

Conclusions: There was an increase in CD14(+)CD16(+) only in CKD-NonD and HD patients. In these patients, there was a relationship between increased CD14(+)CD16(+) and endothelial damage. These results strongly suggest that other factors unrelated to the microinflammatory status mediated by CD14(+)CD16(+) are promoting the endothelial damage in PD, regardless of their RRF.

Figure 1.

Representative flow cytometry analysis. (A) CD14 monocytes (G1) were assessed using an SSC-Height/CD14-PerCP dot plot and backgated (G2) within the FCS-Height/SSC-Height (B). Subsequently, CD14⁺CD16⁺ monocytes within the G2 population were assessed using CD16-FITC/CD14-PerCP dot plot (C, D, E, F). Representative histograms of CD14⁺CD16⁺ expression in different CKD patients and a healthy subject (C, D, E, F). The region represents CD14⁺CD16⁺ monocytes from controls, chronic kidney disease patients (CKD-NonD), hemodialysis patients (HD), and peritoneal dialysis patients (PD).

Figure 2.

Serum VEGF concentrations were measured by ELISA in control, chronic kidney disease (CKD-NonD), hemodialysis (HD), and peritoneal dialysis with RRF >1 ml/min (PD-RRF >1) patients, and peritoneal dialysis with RRF ≤1 ml/min (PD-RRF ≤1) patients. Values are shown as mean ± standard deviation. *P < 0.05 versus controls, CKD-NonD, PD-RRF >1, PD-RRF ≤1. #P < 0.05 versus controls.

Figure 3.

Apoptotic EMPs in platelet-free plasma from control, chronic kidney disease (CKD-NonD), hemodialysis (HD), and peritoneal dialysis with RRF >1 ml/min (PD-RRF >1) patients, and peritoneal dialysis with RRF ≤1 ml/min (PD-RRF ≤1) patients. Apoptotic EMPs were measured by flow cytometry. Apoptotic EMPs are expressed as events per microliter. *P < 0.05 versus controls, CKD-NonD, PD-RRF > 1, PD-RRF ≤ 1. #P < 0.05 versus controls.

Figure 4.

Correlation between CD14⁺CD16⁺ cells and serum VEGF concentration or apoptotic EMPs. (A) Percentages of CD14⁺CD16⁺ cells were correlated with serum VEGF concentrations in each group. (B) Percentages of CD14⁺CD16⁺ cells were correlated with the numbers of apoptotic EMPs in the controls, CKD-NonD, HD, and PD groups. We have shown only a single PD graph because both PD groups displayed similar results.