N-acetylcysteine prevents mitochondria from oxidative injury induced by conventional peritoneal dialysate in human peritoneal mesothelial cells.

INTRODUCTION: Bioincompatible peritoneal dialysate fluids (PDFs) may lead to peritoneal injury. The present study investigated the possible effects of N-acetylcysteine (NAC) during conventional PDF exposure for human peritoneal mesothelial cells (HPMCs). METHODS: Cultured HPMCs were incubated with conventional 1.5% dextrose PDF for different time periods, and NAC was utilized as the antioxidant. The cell survival, superoxide accumulation, mitochondrial membrane potential (Deltapsim), expression of heat shock protein 72(HSP72), catalase, superoxide dismutase (SOD), and glutathione content of HPMCs were evaluated. RESULTS: HPMC exposed to PDF resulted in a significant decrease in cell survival in a time-dependent manner, which was reversed by NAC. PDF exposure resulted in intracellular accumulation of superoxide in a time-dependent manner, with collapse of Deltapsim as well. The activity of enzymatic antioxidant, SOD and catalase remained the same in all groups. However, the reduced glutathione was significantly suppressed after PDF exposure. NAC treatment preserved the content of intracellular reduced glutathione, and also attenuated the PDF-induced superoxide accumulation and Deltapsim collapse. Moreover, the enhanced expression of HSP72 induced by PDF exposure was also reversed by NAC. CONCLUSION: Depletion of a nonenzymatic antioxidant, i.e. reduced glutathione, in HPMC is a crucial cause of PDF-induced oxidative stress. NAC protects HPMCs from PDF-induced cellular damage by preserving the reduced glutathione.

Heat shock response protects human peritoneal mesothelial cells from dialysate-induced oxidative stress and mitochondrial injury.

BACKGROUND: Chronic peritoneal dialysis (PD) is one of the major therapies for uremic patients. However, the peritoneal mesothelial cells (PMCs) are subject to the injury by bioincompatible dialysates. The aim of this study is to investigate the protective roles and mechanisms of heat shock response in PMCs. METHODS: Primary cultured human PMCs (HPMCs) were subjected to commercial peritoneal dialysates. The cell viability was assayed by MTT test and Annexin V assay. The expression of HSPs was detected by Western blots analysis. Intracellular hydrogen peroxide and superoxide anion were detected using H(2)DCFDA and dHE probe, respectively, with flow cytometry. The mitochondrial membrane potential (DeltaPsim) of HPMCs was evaluated using JC1 probe with flow-cytometry. RESULTS: Exposure of HPMCs to 1.5%, 2.5%, and 4.25% dextrose, and 7.5% icodextrin dialysates, respectively, for 60 min resulted in significantly accumulation of intracellular reactive oxygen species (ROS), DeltaPsim loss, and cell death in HPMCs. Amino acid dialysates exhibited no significant cytotoxicity. Adjusting the acidity in 1.5% dextrose and icodextrin dialysate significantly attenuated the dialysate-induced ROS generation and cell death in HPMCs. Heat pretreatment (41 degrees C, 30 minutes), which induced HSP 27 and 72 syntheses, significantly attenuated the dialysate-induced intracellular ROS accumulation, Dym loss, and cell death in HPMCs. CONCLUSIONS: In conclusion, the acidic bioincompatible dialysates induce oxidative stress, DeltaPsim loss, and subsequent cell death in HPMCs. Amino acid dialysates is more biocompatible than glucose and icodextrin dialysates to HPMCs. Heat shock response protects HPMCs from the bioincompatible dialysates-induced cellular damage.