Multimeric vitronectin in ascites is involved in fibroblast spreading of EPS in patients on CAPD therapy

Although encapsulating peritoneal sclerosis (EPS) is a serious complication of continuous ambulatory peritoneal dialysis (CAPD) therapy, the mechanism of the fibroneogenesis in EPS remains unknown. Because fibroblast adhesion and spreading to the extracellular matrix is the first step in peritoneal fibrosis, we investigated fibroblast spreading factor in ascites obtained from patients with EPS (EPS ascites).

To analyze fibroblast spreading activity, various concentrations of EPS ascites obtained from two EPS patients were coated on culture plates, and then the number of human fibroblasts (TIG-3) that had spread was counted. Each fraction of gel-filtered EPS ascites was also analyzed by this activity. Next, we examined the effect of the addition of Arg-Gly-Asp (RGD) peptides, several antibodies against adhesion molecules, and heparin on the fibroblast spreading activity in the EPS ascites.

The fibroblast spreading activity of EPS ascites was about four times greater than that in ascites from a patient with nephrotic syndrome. Two major peaks (peak I and II) of spread cells were obtained when ascites were gel-filtered. The fibroblast spreading activities of the two peaks were abolished by the addition of RGD peptides and polyclonal antibody against vitronectin (VN). Immunoblotting analysis revealed that the two peaks contained VN and that peak I contained multimeric VN. Heparin, at 10 microg/ml, augmented the fibroblast spreading activity of peak I to about three times greater than the control.

The results indicate that multimeric VN in EPS ascites plays a potential role in peritoneal fibrogenesis in EPS and that heparin may participate in peritoneal fibrosis in EPS.