Endothelin B Receptor Blocker Inhibits High Glucose-Induced Synthesis of Fibronectin in Human Peritoneal Mesothelial Cells

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 ET_A receptor antagonist BQ-123, the ET_B 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, ET_A receptor, ET_B 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 ET_B receptor but not the ET_A 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/ET_B receptor pathway and, therefore, an ET_B receptor antagonist may be useful in preventing FN production in HPMC.