Abstract
Background
Long-term peritoneal dialysis using glucose-based dialysates is associated with peritoneal fibrosis. The object of this study was to investigate the hypothesis that endothelin (ET)-1, which is known to play an important role in various fibrotic diseases, may also be involved in peritoneal fibrosis using human peritoneal mesothelial cells (HPMC).
Methods
HPMC were cultured with 4% d- or l-glucose, or loaded with 10 nmol/L ET-1. In some experiments, the ETA receptor antagonist BQ-123, the ETB receptor antagonist BQ-788, and antioxidants 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL) and diphenyleneiodium chloride (DPI) were used. mRNA expression of ET-1, ETA receptor, ETB receptor, and fibronectin (FN) was analyzed by real-time polymerase chain reaction (real-time PCR). The protein levels for FN and ET-1 were measured by ELISA. CM-H2DCFDA-sensitive reactive oxygen species (ROS) were evaluated by flow cytometry.
Results
d-Glucose significantly induced mRNA expression of ET-1 and the ETB receptor but not the ETA receptor. FN production under high glucose conditions was inhibited by BQ-788. ET-1 directly stimulated HPMC to increase mRNA expression of FN and CM-H2DCFDA-sensitive ROS production. BQ-788, TEMPOL, and DPI inhibited mRNA expression of FN induced by ET-1.
Conclusion
The present study suggests that high-glucose-induced FN synthesis is mediated by the ET-1/ETB receptor pathway and, therefore, an ETB receptor antagonist may be useful in preventing FN production in HPMC.
Keywords
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