Angiotensin II mediates high glucose-induced TGF-beta1 and fibronectin upregulation in HPMC through reactive oxygen species.
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)-beta1 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-beta1 was evaluated by real-time polymerase chain reaction; ACE, AT1, and fibronectin proteins by Western blot analysis; and Ang I, Ang II, and TGF-beta1 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/L D-glucose (high glucose) significantly increased angiotensinogen, ACE, and AT1 mRNAs and ACE, AT1, and Ang II proteins. Ang II increased TGF-beta1 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-beta1 and fibronectin expression in HPMC in a dose-dependent manner. Antioxidant catalase and NADPH oxidase inhibitor diphenyleneiodinium effectively inhibited Ang II-induced TGF-beta1 and fibronectin protein expression.


CONCLUSIONS
The present data demonstrate that HPMC constitutively express RAS, that Ang II produced by HPMC mediates high glucose-induced upregulation of TGF-beta1 and fibronectin expression, and that Ang II-induced TGF-beta1 and fibronectin expression in HPMC is mediated 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.
Noh
Hyunjin
H
Hyonam Kidney Laboratory, Soon Chun Hyang University, Seoul, Korea.
Ha
Hunjoo
H
Yu
Mi Ra
MR
Kim
Young Ok
YO
Kim
Ji Hye
JH
Lee
Hi Bahl
HB
D000804:Angiotensin II / Q000502:physiology*; D018929:Cell Culture Techniques; D015314:Dialysis Solutions / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D010537:Peritoneum / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D015854:Up-Regulation / Q000502:physiology
D015314:Dialysis Solutions; D005353:Fibronectins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000804:Angiotensin II; D005947:Glucose