High glucose increases prostaglandin E2 synthesis in human peritoneal mesothelial cells: role of hyperosmolarity

Peritoneal mesothelial cells are considered the predominant source of peritoneal prostanoid formation because they represent the largest resident cell population in the peritoneal cavity. The present study was designed to evaluate the effect of D-glucose, which is widely used in commercially available peritoneal dialysis fluids as an osmotic compound, on the synthesis of prostaglandins in cultured human mesothelial cells (HMC). Analysis of eicosanoid synthesis in HMC by reversed-phase HPLC revealed that 6-keto-PGF1alpha, the spontaneous hydrolysis product of prostacyclin (PGI2), and prostaglandin E2 (PGE2) were the main eicosanoids produced. Addition of D-glucose resulted in a time- and concentration-dependent (30 to 120 mM) increase in PGE2 production in HMC (24 h, 90 mM: 3.9+/-0.5 ng/10(5) cells versus 2.3+/-0.3 in untreated cells; P < 0.05). Mannitol (90 mM) or L-glucose (90 mM). nonmetabolizable osmotic compounds, also led to a significant (P < 0.05) but less intense increase in PGE2 synthesis (3.3+/-0.4 and 3.2+/-0.5 ng/10(5) cells, respectively). Increased PGE2 synthesis was completely blunted by coincubation with the specific protein kinase C (PKC) inhibitor Ro 31-8220 or downregulation of PKC activity by preincubation with phorbol myristate acetate for 16 h. Furthermore, coincubation with PD 98059, an inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, also inhibited increased PGE2 synthesis by D-glucose or mannitol. In contrast, the iso-osmolar glucose polymer icodextrin, which is used as an alternative to D-glucose in peritoneal dialysis solutions, had no effect on PGE2 synthesis. These data indicate that D-glucose and metabolically inert sugars increase PGE2 synthesis in HMC at least in part by hyperosmolarity and that this effect requires activation of PKC and the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway of intracellular signaling.