ANGIOTENSIN Ⅱ MEDIATES HIGH GLUCOSE-INDUCED TGF-β1 AND FIBRONECTIN UPREGULATION IN HPMC THROUGH REACTIVE OXYGEN SPECIES

다국어 초록 (Multilingual Abstract)

Objective: To demonstrate the presence of an independent renin-angiotensin system (RAS) in the peritoneum and to determine the role of locally produced angiotensin (Ang) Ⅱ in high glucose-induced upregulation of transforming growth factor (TGF)-β1 and fibronectin by human peritoneal mesothelial cells (HPMC).
Methods: In cultured HPMC, the expression of mRNAs for angiotensinogen, angiotensin-converting enzyme (ACE), Ang Ⅱ type 1 receptor (AT1), and TGF-β1 was evaluated by real-time polymerase chain reaction; ACE, AT1, and fibronectin proteins by Western blot analysis; and Ang Ⅰ, Ang Ⅱ, and TGF-β1 proteins by ELISA. Dichlorofluorescein (DCF) -sensitive cellular reactive oxygen species (ROS) were measured by fluorometry.
Results: HPMC constitutively expressed all the components of RAS, and 50 mmol/LD-glucose (high glucose) significantly increased angiotensinogen, ACE, and AT1 mRNAs and ACE, AT1, and Ang Ⅱ proteins. Ang Ⅱ increased TGF-β1 and fibronectin protein expression and DCF-sensitive cellular ROS. Losartan prevented Ang Ⅱ-induced increase in cellular ROS. Both losartan and captopril inhibited high glucose-induced upregulation of TGF-β1 and fibronectin expression in HPMC in a dose-dependent manner. Antioxidant catalase and NADPH oxidase inhibitor diphenyleneiodinium effectively inhibited Ang Ⅱ-induced TGF-β1 and fibronectin protein expression.
Conclusions: The present data demonstrate that H PMC constitutively express RAS, that AngⅡI produced by HPMC mediates high glucose-induced upregulation of TGF-β1 and fibronectin expression, and that Ang Ⅱ-induced TGF-β1 and fibronectin expression in HPMC is medicted by NADPH oxidase-dependent ROS. These data suggest that locally produced Ang Ⅱ and ROS in the peritoneum may be potential therapeutic targets in peritoneal fibrosis during long-term peritoneal dialysis.