Peritoneal dialysate induces connective tissue growth factor expression in rat peritoneal mesotbelial cells

Objective To investigate the effects of peritoneal dialysis fluids (PDF) on connective tissue growth factor (CTGF) synthesis in rat peritoneal mesothelial cells (RPMCs). Methods Cultured RPMCs were stimulated by 1.5% Dextrose(LG), 2.5% Dextrose(MG), 4.25% Dextrose (HG), and 7.5% lcodextrin (ICO) dialysate for 24 hours. Serum free DMEM was used as negative control(Control), TGF-β1(2.5 ng/ml) as positive control(TGF-β1). The mRNA expression levels of CTGF, α-SMA, and collagen I were measured by RT-PCR. CTGF, α-SMA, and collagen I protein in cell layer, secreted CTGF protein in culture supernatant were detected by Western blot. Results The CTGF mRNA could be detected in all the groups. The CTGF mRNA in HG group was significantly higher than those of other PDF groups and control group(P 0.05). MG and ICO could also up-regulate CTGF mRNA synthesis (P 0.05). CTGF protein expression in cell layer could be detected in all groups. The major protein species was a 38 KD, and a minor species of 25 KD. Consistent with RT-PCR reslult, HG group showed the highest level of expression (P 0.05). In cell culture supernatant, only the species of 38 KD CTGF could be detected. The tendency was consistent with the CTGF protein expression in the cell layer. The expression levels of mRNA and protein of collagen I in HC and TGF-β1 group were obviously increased compared with other groups, the latter had no differences. However, no significant difference was found in α-SMA mRNA and protein expression among all the groups. Conclusions There is a low level of CTGF expression in cultured RPMCs, both in mRNA and protein. Exposure to PDF, especially hypertonic glucose solution, may increase CTCF synthesis in peritoneal mesothelial cells and contribute to chronic peritoneal membrane alterations. Icodextrin may be more biocompatible than hypertonic glucose solution.