Plasma and dialysate IL-6 and VEGF concentrations are associated with high peritoneal solute transport rate.
BACKGROUND
It has been speculated that increased levels of circulating or intraperitoneal pro-inflammatory cytokines such as interleukin 6, and pro-angiogenic vascular endothelial growth factor (VEGF) may contribute to high peritoneal small-solute transport rate (PSTR) in continuous ambulatory peritoneal dialysis (CAPD) patients. In this study we evaluated possible relationships between plasma and dialysate IL-6 and VEGF levels and PSTR.


METHODS
Forty CAPD patients (mean age+/-SD of 58+/-14 years) with no apparent inflammation process or disease, who had been on CAPD for 19+/-15 months (range 3-56 months) were included in the study. Peritoneal equilibration test (PET) was used to evaluate PSTR. Patients were divided into two groups: high-average and high transporters (H/A; D/P(creat)>/=0.65) and low-average and low transporters (L/A; D/P(creat)<0.64). Albumin and IgG clearances were used in the evaluation of permeability to larger solutes. Plasma and overnight dialysate levels of IL-6 and VEGF were measured.


RESULTS
Plasma IL-6 (7.6 vs 4.3 pg/ml) and VEGF (342 vs 163 pg/ml) as well as dialysate IL-6 (174 vs 80 pg/ml) and VEGF (96 vs 69 pg/ml) levels were significantly higher in the H/A than in the L/A group. The dialysate appearance of IL-6 and VEGF correlated with D/P(creat), as well as with albumin and IgG clearances. Moreover, significant correlations were noted between dialysate IL-6 and dialysate VEGF levels.


CONCLUSIONS
The findings of (i) increased plasma and dialysate levels of IL-6 and VEGF in the H/A group compared to the L/A group, (ii) an association between PSTR and both plasma and dialysate IL-6 and VEGF levels, and (iii) a significant correlation between dialysate IL-6 and VEGF concentrations suggest that inflammation, angiogenesis, and peritoneal transport may be interrelated and involved in the pathophysiology of high PSTR in CAPD patients. However, due to the cross-sectional design of this study, the cause and effect relationships between plasma and dialysate IL-6 and VEGF concentrations and high PSRT remain unclear.
Pecoits-Filho
Roberto
R
Nephrology Division, University of São Paulo School of Medicine, São Paulo, Brazil. pecoits@usp.br
Araújo
Maria Regina T
MR
Lindholm
Bengt
B
Stenvinkel
Peter
P
Abensur
Hugo
H
Romão
João Egídio
JE
Marcondes
Marcelo
M
De Oliveira
André H Freiria
AH
Noronha
Irene L
IL
D003404:Creatinine / Q000097:blood; D016207:Cytokines / Q000097:blood; D016228:Endothelial Growth Factors / Q000097:blood*; D005260:Female; D005921:Glomerulonephritis / Q000097:blood / Q000276:immunology / Q000628:therapy; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D007700:Kinetics; D008222:Lymphokines / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010529:Peritoneal Cavity; D010531:Peritoneal Dialysis, Continuous Ambulatory; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016207:Cytokines; D016228:Endothelial Growth Factors; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D003404:Creatinine