High Glucose Solution and Spent Dialysate Stimulate the Synthesis of Transforming Growth Factor-β₁ of Human Peritoneal Mesothelial Cells: Effect of Cytokine Costimulation

Abstract

Objective To investigate the effect of high glucose and spent peritoneal dialysate on the transforming growth factor-β1 (TGFβ1) synthesis of cultured human peritoneal mesothelial cells (HPMCs) and to examine the effect of costimulation with high glucose or spent dialysate, and cytokines, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNFα) on TGFβ1 synthesis of HPMCs. Design HPMCs were exposed to different concentrations of glucose (30, 60, and 90 mmol/L) or spent peritoneal dialysate for 48 hours in the absence or presence of IL-1β (1 ng/mL) and TNFα (1 ng/mL). TGFβ1 mRNA expression was assessed by Northern blot analysis and TGFβ1 protein release by Western blot analysis and enzymelinked immunosorbent assay (ELISA). Results Exposure of HPMCs to high glucose conditions (30, 60, and 90 mmol/L of D-glucose) induced 2.3-, 3.6-, and 4.0-fold increases in TGFβ1 mRNA expression of HPMC with enhanced TGFβ1 protein synthesis and secretion into the media, whereas there were no significant changes in TGFβ1 synthesis with equimolar concentrations of D-mannitol. Incubation with spent dialysate also significantly increased TGFβ1 mRNA expression and protein secretion compared to control media ( p < 0.05). Stimulation with IL-1β (1 ng/mL) or TNFα (1 ng/mL) resulted in a significant increase in TGFβ1 mRNA expression after 48 hours: 2.7 and 2.1 times the control level, respectively. However, TNFα-induced increase in TGFβ1 mRNA expression was not translated into TGFβ1 protein secretion, while IL-1β stimulation induced a significant increase in TGFβ1 protein secretion as well as TGFβ1 mRNA expression. Combined stimulation by high glucose or spent dialysate, together with IL-1β or TNFα, showed a greater increase in TGFβ1 mRNA expression and protein secretion compared to stimulation by high glucose or spent dialysate alone. Conclusion Our results clearly show that high glucose solution and spent dialysate themselves might be sufficient to stimulate the production of TGFβ1 by peritoneal mesothelial cells. In peritoneal dialysis patients, this state of chronic induction of TGFβ1 is further exacerbated in the presence of peritonitis because of the stimulatory effect of proinflammatory cytokines, resulting in augmented TGFβ1 synthesis, thus promoting peritoneal fibrosis.

Effects of Low Glucose Degradation Products Peritoneal Dialysis Fluid on the Peritoneal Fibrosis and Vascularization in a Chronic Rat Model

“…Chronic exposure of the rat peritoneal membrane to a high-glucose conventional PDF resulted in mesothelial damage, submesothelial and interstitial fibrosis and neoangiogenesis. This result supports previous reports that in vitro exposure of endothelial and mesothelial cells to high glucose stimulates the expressions of VEGF (12) and TGF-β (13), and that chronic in vivo exposure of the peritoneal membrane to high glucose concentrations results in microvascular proliferation and submesothelial fibrosis, which are mediated by VEGF and TGF-β, respectively (14). Glucose degradation products are produced from glucose because of both heat sterilization and storage of PDF, and are known to be one of the bioincompatible factors of glucose-based dialysis solutions, which induce both functional and structural alterations of the peritoneum (7,15).…”

A selective cyclooxygenase‐2 inhibitor decreases transforming growth factor‐β1 synthesis and matrix production in human peritoneal mesothelial cells

“…Peritoneal mesothelial cells play an important role in the process of peritoneal fibrosis. Researches have suggested that peritoneal mesothelial cells can produce TGF-b with the stimulation of high concentration of sugar (Kang et al, 1999). TGF-b1, a cytokine with multiple function, can not only stimulate the synthesis of extracellular matrix, but also inhibit its degradation, therefore, it is the critical factor in the process of peritoneal fibrosis (Border and Noble, 1994).…”

Effects of Glucose and Plasminogen Activator Inhibitor‐1 on Collagen Metabolism in the Peritoneum

“…They concluded that glucose induced damage to the peritoneal membrane is due not only to osmolality but also the polyol pathway. Kang et al (24) reported that glucose stimulates TGFb mRNA expression, while mannitol at the same osmolarity does not. Further study on the osmotic effects of glucose on PAI-1 mRNA expression is needed.…”