Effects of tranilast on the epithelial-to-mesenchymal transition in peritoneal mesothelial cells.

Background: We investigated the effects of tranilast on epithelial-to-mesenchymal transition (EMT) in an animal model and on the EMT signaling pathway in human peritoneal mesothelial cells (HPMCs).

Methods: We performed studies (cytotoxicity, cell morphology, and western blot analyses) on HPMCs from human omenta, along with studies (peritoneal membrane function and morphometric and immunohistochemical analyses) on Sprague Dawley rats. Thirty-two rats were divided into three groups: control (C) group (peritoneal dialysis [PD] catheter but not infused with dialysate), PD group (4.25% glucose-containing dialysate), and PD + tranilast group (4.25% glucose-containing dialysate along with tranilast).

Results: In experiments, transforming growth factor-beta 1 (TGF-β1) increased α-smooth muscle actin and Snail expression and reduced E-cadherin expression in HPMCs. TGF-β1 also reduced cell contact, induced a fibroblastoid morphology, and increased phosphorylation of Akt, Smad2, and Smad3 in HPMCs. Tranilast significantly inhibited TGF-β1-induced EMT and attenuated these morphological changes in HPMCs. In studies, after 6 weeks of experimental PD, the peritoneal membrane was significantly thicker in the PD group than in the C group. Tranilast protected against PD-induced glucose mass transfer change and histopathological changes in rats.

Conclusion: Tranilast prevented EMT both in HPMCs triggered with TGF-β1 and in rats with PD-induced peritoneal fibrosis. Thus, tranilast may be considered a therapeutic intervention that enables long-term PD by regulating TGF-β1 signaling pathways.