The effect of statin on epithelial-mesenchymal transition in peritoneal mesothelial cells.

Tae Ik Chang,Tae-Hyun Yoo,Bo Young Nam,Sun Ha Lee,Shin-Wook Kang,Kyung Sik Kim,Jisun Paeng,Seung Hyeok Han,Hye-Young Kang,Jung Tak Park,Seonghun Kim,Jung Weon Lee

doi:10.1371/journal.pone.0109628

Tae Ik Chang, Tae-Hyun Yoo + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0109628

Copy DOI

Abstract

BackgroundStatins have recently been highlighted for their pleiotropic actions distinct from cholesterol-lowering effects. Despite this interest, it is currently unknown whether statin therapy inhibits peritoneal dialysis (PD)-related epithelial-mesenchymal transition (EMT).Methods In vitro, human peritoneal mesothelial cells (HPMCs) were exposed to 5.6 mM glucose (NG) or 100 mM glucose (HG) with or without simvastatin (1 µM). In vivo, PD catheters were inserted into 32 Sprague-Dawley rats, and saline (C, n = 16) or 4.25% peritoneal dialysis fluid (PDF) (PD, n = 16) was infused for 4 weeks. Eight rats from each group were treated with 5 mg/kg/day of simvastatin intraperitoneally. Changes in the protein expression of EMT markers such as E-cadherin, α-SMA, Snail, and fibronectin in HPMCs and the peritoneum were evaluated by Western blot analysis and immunofluorescence or immunohistochemical staining. We also explored whether activation of the mevalonate pathway and its downstream small GTPases were involved in dialysis-related peritoneal EMT and could be inhibited by statin treatment.ResultsCompared to NG cells, E-cadherin expression was significantly decreased, while α-SMA, Snail, and fibronectin expression were significantly increased in HPMCs exposed to HG, and these changes were abrogated by simvastatin (p<0.05). In addition, the cobblestone-like appearance of normal HPMCs was converted into a fibroblast-like morphology after HG treatment, which was reversed by simvastatin. These EMT-like changes were also observed in HPMCs treated with geranyl-geranyl pyrophosphate (5 µM). HG significantly increased the protein expression of RhoA and Rac1 in the membrane fractions, and these increases were ameliorated by simvastatin (p<0.05). In PD rats, E-cadherin in the peritoneum was significantly decreased, whereas α-SMA, Snail, and fibronectin expression were significantly increased (p<0.05) compared to C rats. The thickness of the mesothelial layer in the peritoneum were also significantly greater in PD rats than in C rats (p<0.05). These changes of the peritoneum in PD rats were significantly attenuated by simvastatin.ConclusionThis study demonstrated that PD-related EMT was mediated via the mevalonate pathway, and statin treatment inhibited the EMT changes in HG-treated HPMCs and PDF-stimulated PD rats. These findings suggest that statins may be a promising therapeutic strategy for preservation of peritoneal membrane integrity in long-term PD patients.

Highlights

Even though peritoneal dialysis (PD) is generally accepted as an established modality for the management of patients with endstage renal disease (ESRD), a concern about peritoneal membrane failure has consistently been raised in long-term PD
To evaluate the effects of statins on epithelialmesenchymal transition (EMT) in vitro, human peritoneal mesothelial cells (HPMCs) were incubated for 72 hr with NG, NG+M, NG+simvastatin, or HG with or without simvastatin
HPMCs cultured under HG medium showed a weak staining of E-cadherin, a strong signal intensity of a-SMA, and increased nuclear translocation of Snail, all of which were ameliorated by the administration of simvastatin (Fig. 2B)

Summary

Introduction

Even though peritoneal dialysis (PD) is generally accepted as an established modality for the management of patients with endstage renal disease (ESRD), a concern about peritoneal membrane failure has consistently been raised in long-term PD. The nonphysiologic nature of PD solutions—high concentrations of glucose and lactate, low pH, and glucose degradation products—is a major factor responsible for deleterious effects on the peritoneal membrane [1,2]. These components induce chronic inflammation in the peritoneal cavity, which is often exacerbated by recurrent episodes of peritonitis and leads to structural and functional alterations of the peritoneal membrane [3]. Statins have recently been highlighted for their pleiotropic actions distinct from cholesterol-lowering effects Despite this interest, it is currently unknown whether statin therapy inhibits peritoneal dialysis (PD)-related epithelialmesenchymal transition (EMT)

Methods

Results

Discussion

Conclusion