Human peritoneal fibroblast proliferation in 3-dimensional culture: Modulation by cytokines, growth factors and peritoneal dialysis effluent

Structural and functional alternations of the peritoneal membrane are a significant problem in long-term peritoneal dialysis patients. The present study has established a 3-dimensional (3D) cell culture system to study the human peritoneal fibroblast (HPFB) and to examine its proliferative responses to cytokines and growth factors as well as dialysis effluent obtained from patients during peritoneal infection. PDGF-(AB), basic FGF and IL-1 beta induced a time and dose dependent increase in 3D-HPFB proliferation. At day 9 proliferation, as assessed by MTT uptake, was increased by 2.4-, 2.3- and 1.5-fold above control by PDGF-(AB) (50 ng/ml), bFGF (50 ng/ml) and IL-1 beta (10 ng/ml), respectively (N = 5, P = 0.04 for all). These effects could be inhibited by co-incubation with anti-PDGF-(AB) antibody, anti-bFGF or IL-1ra, respectively. Exposure of 3D-HPFB to TGF-beta(1) did not result in an increase in cell proliferation. Incubation of 3D-HPFB with peritoneal macrophage (PMO) or human peritoneal mesothelial cell (HPMC) conditioned medium also resulted in a time and dose dependent increase in proliferation. At day 9, proliferation was maximally increased 1.65- and 1.92-fold by peritoneal macrophage- adn mesothelial cell-conditioned medium, respectively. Cell free PDE, obtained from CAPD patients during episodes of peritonitis, induced 3D-HPFB proliferation above control values (2- to 6.5-fold increases, N = 5, P < 0.05 for all). This mitogenic potential of PDE was reduced following dilution, and with time following peritonitis there was a gradual decrease in the mitogenic effect of PDE. The proliferative potential of PDE was significantly reduce following co-incubation with IL-1ra (45.7% inhibition), anti-bFGF (34.9% inhibition) and anti PDGF-(AB) (27.4% inhibition). These data indicate that infected PDE causes fibroblast hyperplasia which might potentially contribute to pro-fibrotic processes during CAPD.