Transforming Growth Factor-beta1(TGF-beta1) Synthesis of Human Peritoneal Mesothelial Cell

Yoon, Kyun Il; Kang, Duk Hee; Lim, Hyun Joung; Hong, Young Suk; Choi, Jin Hee; Han, Dae Suk

Abstract

OBJECTIVE: to investigate the effect of high glucose and spent peritoneal dialysate on the TGF-beta1 synthesis of cultured human peritoneal MC(HPMC); to examine the effect of costimulation with high glucose or dialysate and cytokines, interleukin-1beta(IL-1beta) and tumor necrosis factor-alpha(TNF-alpha), on transforming growth factor(TGF-beta1) synthesis of HPMC. DISIGN: HPMCs were exposed to different concentrations of glucose(30, 60 & 90 mM/L) or spent peritoneal dialysate for 48 hours in the absence or presence of IL-1beta(1ng/ml) and TNF-alpha(1ng/ml). TGF-beta1 mRNA expression was assessed by Northern blot analysis and TGF-beta1 protein synthesis and release by Western blot analysis with immunoprecipitation. RESULTS: Exposure of MC to high glucose condition(30mM, 60mM & 90mM of D- glucose) induced 2.3-, 3.6- and 4.0-fold increases in TGF-beta1 mRNA expression of MC with enhanced TGF-beta1 protein synthesis and secretion into the media. Incubation with spent dialysate also significantly increased TGF-beta1 mRNA expression & protein secretion compared to control media(P<0.05) Stimulation with IL-1beta(1ng/ml) or TNF-alpha(1ng/ml) significantly increased TGF-beta1 mRNA expression after 48 hours above the control level by 2.7-fold and 2.1-fold, respectively. However, TNF-alpha-induced increase in TGF-beta1 mRNA expression was not translated into TGF-beta1 protein secretion whereas IL-1beta stimulation induced a significant increase in TGF-beta1 protein secretion as well as TGF-beta1 mRNA expression. Combined stimulation of high glucose or spent dialysate together with IL-1beta or TNF-alpha showed a greater increase in TGF-beta1 mRNA expression and protein secretion compared to stimulation with high glucose or spent dialysate alone. CONCLUSION: Our results clearly show that high glucose concentration of peritoneal dialysate and spent dialysate themselves might be sufficient to stimulate the production of TGF-beta1 by peritoneal mesothelial cell. This state of chronic induction of TGF-beta1 is further exaggerated in the presence of peritonitis because of stimulatory effect of proinflammatory cytokines, resulting in the augmented TGF-beta1 synthesis, thus promoting peritoneal fibrosis.