Effects Of High Glucose Enriched Peritoneal Dialysis Solutions On Ultrastructure Of Rat Peritoneal Mesothelial Cells

BackgroundContinuous ambulatory peritoneal dialysis (CAPD) is now established as a major replacement therapy for end-stage renal disease (ESRD). Nevertheless, Long-term exposure to bioincompatible PD solutions cause injury to the peritoneal membrane, which progressively undergoes fibrosis and angiogenesis, and ultimately terminated in ultrafiltration failure. This became the main reason for CAPD patients withdraw from PD. However, accumulating evidence implicates that peritoneal mesothelial cells also play an active role in the process of peritoneal fibrosis. Epithelial to Mesenchymal Transition (EMT) is an initial and generally reversible process of peritoneal fibrosis.Until now,using electron microscopy to observe the ultrastructural changes of the intercellular junctions and the connection between cells and matrix in the EMT process in vivo is open to interpretation.ObjectiveTo inverstage ultrastructural changes of cell-cell and cell-matrix connection, and observe the expression changes in E-cadherin, ZO-1, a-SMA in peritoneal fibrosis rats model which were induced by high glucose enriched peritoneal dialysis solutions.MethodsEighteen female SD rats were randomly divided into three groups: normal control group (n=6),4.25%PDS7d group (n=6),4.25%PDS14d group (n=6).4.25%PDS7d group received a daily infusion of20mL 4.25%PDS for7days,4.25%PDS14d group received a daily infusion of20mL4.25%PDS for14days,The animals were sacrificed at day7or14, Parietal peritoneum was collected for transmission electron microscopy, the ultrastructural changes of the intercellular junctions and the connection between cells and matrix were observed.The expression of E-cadherin, ZO-1, a-SMA protein were examined with western blot.Results1. Western blot showed that in normal control group,the greater omentum tissue express E-cadherin and ZO-1,while only a small amount of a-SMA; Both of the expression of E-cadherin and ZO-1protein in greater omentum of4.25%PDS7d group decreased; The level of a-SMA protein elevated (p<0.05);The expression of E-cadherin and ZO-1protein in greater omentum of4.25%PDS14d group decreased more significantly;and a-SMA protein elevated more significantly.2. Transmission electron microscopy showed that in normal control group, the layer of peritoneal mesothelial were integrited, peritoneal mesothelial cells have normal morphology and structure, the connection between adjacent cells and the one between cell and matrix were intact;In4.25%PDS7d group, the peritoneal mesothelial cells showed mild shrinkage, partial of the connection between cells and matrix were dissociated, the gap widened;In4.25%PDS14d group, the peritoneal mesothelial cells showed obvious depression and shrinkage, partial of the connection between cells and matrix were dissociated,partial of the connection between cells were obviously widened,and the peritoneal matrix were exposed.Conclusion(1) High glucose enriched peritoneal dialysis solutions induces early change of EMT in rat peritoneal mesothelials. (2) In PD condition, the ultrastructure of rat peritoneal mesothelial cells showed that the connection between peritoneal mesothelial cells were abnormal, the gap between adjacent cells widened, and the connection between cells and matrix released, which were closely related to the early EMT process.