Glutathione depletion as a mechanism of 3,4-dideoxyglucosone-3-ene-induced cytotoxicity in human peritoneal mesothelial cells: role in biocompatibility of peritoneal dialysis fluids.

BACKGROUND

The potential detrimental effects of glucose degradation products (GDPs) contained in peritoneal dialysis fluids (PDFs) on peritoneal mesothelial cells (PMCs) may impair intraperitoneal homeostasis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A recent study showed that 3,4-dideoxyglucosone-3-ene (3,4-DGE) was the most strongly cytotoxic among all identified GDPs in PDFs. The present study examined the effects of clinically relevant concentrations of 3,4-DGE on the proliferative capacity of PMCs and oxidative injury to them.

METHOD

The concentrations of eight GDPs in commercially available PDFs were determined by HPLC. The effect of cell growth media spiked with GDPs on the proliferation capacity of PMCs was evaluated. As a marker of the cellular redox status, total cellular glutathione (tGSH) was determined in PMCs incubated with GDPs. The reaction of 3,4-DGE with GSH under nonenzymatic conditions was analysed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS).

RESULT

The concentrations of 3,4-DGE in a heat-sterilized single-compartment standard-type PDF (S-PDF) and in a heat-sterilized dual-chamber-type PDF (N-PDF) were 16 microM and 1.7 microM, respectively. The most cytotoxic GDP was 3,4-DGE, and the concentration at which it causes 50% inhibition of cell growth was 35 microM. A significant decrease in the cellular tGSH levels was observed in the cells treated with 10 microM 3,4-DGE. 3,4-DGE disappeared on incubation with GSH under nonenzymatic conditions for 1 h, and the 3,4-DGE-GSH conjugate was confirmed by accurate mass measurement using LC-ESI-MS. These data demonstrated that the change in the cellular redox status by GSH depletion might be a contributory factor in 3,4-DGE-induced cytotoxicity.

CONCLUSION

3,4-DGE is a highly reactive GDP and is responsible for the depletion of the total intracellular glutathione. 3,4-DGE has an intense impact on PMC growth at concentrations found in standard PDFs. It is desired that the amount of 3,4-DGE in PDFs should be minimized.