ERYTHROPOIETIN PREVENTS DIALYSIS FLUID-INDUCED APOPTOSIS OF MESOTHELIAL CELLS

Background: In peritoneal dialysis (PD)-treated patients, denudation of the mesothelium correlates with peritoneal fibrosis and vascular changes. Since recombinant human erythropoietin (rHuEPO) induces a range of cyto-protective cellular responses, rHuEPO treatment may reduce PD fluid (PDF)-induced damage. Methods: To investigate the antiapoptotic effect and mechanism of rHuEPO in peritoneal mesothelial cells (PMCs), isolated mice PMCs were used for in vitro characterization of rHuEPO effects. To confirm the in vitro effects, active caspase-3 was analyzed in imprints of liver visceral peritoneum of mice pretreated overnight with rHuEPO (5000 U/kg intraperitoneally) and exposed to PDF (Dianeal 4.25%; Baxter Healthcare, Deerfield, Illinois, USA) for 4 hours. Results: Mouse PMCs expressed EPO-receptor mRNA and protein. Short exposure to rHuEPO (5 U/mL) induced phosphorylation of JAK2, STAT5, and ERK1/2. PMCs pretreated for 1 hour with rHuEPO showed reduced PDF-induced caspase-3 activation (49.6%) and DNA fragmentation (38.4%) in comparison to cells treated by PDF alone (p < 0.05). rHuEPO treatment induced an increase in ERK1/2 phosphorylation and reduced levels of PDF-induced phospho-P38. PD98059, a specific inhibitor of ERK activation, fully blocked the protective effect of rHuEPO. In mice, rHuEPO reduced the apoptotic effect of PDF, as assessed by the level of active caspase-3. Conclusions: Our study presents new insights into clinical use of rHuEPO in the setting of PD. We found that rHuEPO provides ERK1/2-dependent protection to PMCs from PDF-induced apoptosis. The use of rHuEPO, or any of its new derivatives that do not stimulate erythropoiesis, should be considered for peritoneal preservation.