Intra-peritoneal interleukin-6 system is a potent determinant of the baseline peritoneal solute transport in incident peritoneal dialysis patients.
BACKGROUND
Interleukin-6 (IL-6) is a key player in modulating inflammation. IL-6 and soluble IL-6 receptor (sIL-6R) complex induces the synthesis and secretion of various chemokines, adhesion molecules and angiogenic molecules. We hypothesized that the baseline peritoneal solute transport rate (PSTR) early after commencing peritoneal dialysis (PD) may depend largely on the IL-6/sIL-6R system. We also hypothesized that the dialysate concentrations of IL-6/sIL-6R could be closely related to local inflammation or angiogenesis in the peritoneal cavity.


METHODS
Fifty incident patients with a modified peritoneal equilibration test result within 3 months after commencing PD and without a previous history of peritonitis were enrolled. Clinical parameters such as age, sex, comorbid disease, body mass index, residual renal function and C-reactive protein were assessed. Serum and dialysate markers including CA125, IL-6, sIL-6R, monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) were measured and correlated with PSTR.


RESULTS
Dialysate concentrations of IL-6 (r = 0.576, P < 0.001), MCP-1 (r = 0.408, P = 0.003) and Ang-2 (r = 0.408, P = 0.003) correlated with mass transfer area coefficient for creatinine (MTAC(cr)), respectively. Dialysate appearance rate (AR) of albumin correlated with dialysate concentrations of CA125 (r = 0.751, P < 0.001), IL-6 (r = 0.303, P = 0.039), sIL-6R (r = 0.497, P < 0.001), MCP-1 (r = 0.488, P < 0.001), VEGF (r = 0.443, P = 0.004) and Ang-2 (r = 0.488, P < 0.001). Neither MTAC(cr) nor AR of albumin was associated with systemic markers. Multivariate analysis showed that MTAC(cr) is independently associated with dialysate IL-6 and serum albumin. It also showed that AR of albumin is independently predicted by dialysate sIL-6R. Dialysate IL-6 correlated with dialysate concentrations of CA125 MCP-1, VEGF and Ang-2.


CONCLUSIONS
Our study from incident PD patients suggested that (i) dialysate the IL-6 system is a potent determinant of baseline PSTR and (ii) elevation of IL-6 in the dialysate is associated with up-regulation of intra-peritoneal inflammatory and angiogenic molecules.
Oh
Kook-Hwan
KH
Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
Jung
Ji Yong
JY
Yoon
Myeong Ok
MO
Song
Aeran
A
Lee
Hajeong
H
Ro
Han
H
Hwang
Young-Hwan
YH
Kim
Dong Ki
DK
Margetts
Peter
P
Ahn
Curie
C
D000328:Adult; D000368:Aged; D000418:Albumins / Q000378:metabolism; D042702:Angiopoietin-2 / Q000097:blood; D001692:Biological Transport; D018394:CA-125 Antigen / Q000097:blood; D018932:Chemokine CCL2 / Q000097:blood; D003404:Creatinine / Q000378:metabolism; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000097:blood
D000418:Albumins; D042702:Angiopoietin-2; D018394:CA-125 Antigen; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D015850:Interleukin-6; D042461:Vascular Endothelial Growth Factor A; D003404:Creatinine