Tamoxifen Ameliorates Peritoneal Membrane Damage by Blocking Mesothelial to Mesenchymal Transition in Peritoneal Dialysis

Jesús Loureiro,Guadalupe Gónzalez-Mateo,Abelardo I Aguilera,José Antonio Sánchez-Tomero,Maria Auxiliadora Bajo,Manuel López-Cabrera,Gloria Del Peso,Vanessa Fernández-Millara,Gonzalo Guerra-Azcona,Rafael Selgas,Pilar Sandoval,Beatríz Santamaria,Utpal Sen

doi:10.1371/journal.pone.0061165

Abstract

Mesothelial-to-mesenchymal transition (MMT) is an auto-regulated physiological process of tissue repair that in uncontrolled conditions such as peritoneal dialysis (PD) can lead to peritoneal fibrosis. The maximum expression of peritoneal fibrosis induced by PD fluids and other peritoneal processes is the encapsulating peritoneal sclerosis (EPS) for which no specific treatment exists. Tamoxifen, a synthetic estrogen, has successfully been used to treat retroperitoneal fibrosis and EPS associated with PD. Hence, we used in vitro and animal model approaches to evaluate the efficacy of Tamoxifen to inhibit the MMT as a trigger of peritoneal fibrosis. In vitro studies were carried out using omentum-derived mesothelial cells (MCs) and effluent-derived MCs. Tamoxifen blocked the MMT induced by transforming growth factor (TGF)-β1, as it preserved the expression of E-cadherin and reduced the expression of mesenchymal-associated molecules such as snail, fibronectin, collagen-I, α-smooth muscle actin, and matrix metalloproteinse-2. Tamoxifen-treatment preserved the fibrinolytic capacity of MCs treated with TGF-β1 and decreased their migration capacity. Tamoxifen did not reverse the MMT of non-epitheliod MCs from effluents, but it reduced the expression of some mesenchymal molecules. In mice PD model, we demonstrated that MMT progressed in parallel with peritoneal membrane thickness. In addition, we observed that Tamoxifen significantly reduced peritoneal thickness, angiogenesis, invasion of the compact zone by mesenchymal MCs and improved peritoneal function. Tamoxifen also reduced the effluent levels of vascular endothelial growth factor and leptin. These results demonstrate that Tamoxifen is a therapeutic option to treat peritoneal fibrosis, and that its protective effect is mediated via modulation of the MMT process.

Highlights

In peritoneal dialysis (PD), the peritoneal membrane (PM) is exposed to bio-incompatible dialysis solutions, with high content of glucose, which can cause peritoneal injury when associated with peritoneal incidents like repeated episodes of peritonitis or hemoperitoneum [1], [2], [3]
We first analyzed whether omentum-derived mesothelial cells (MCs) expressed estrogen receptor alpha (a-ER), and how its expression was affected by transforming growth factor (TGF)-b1 and/or different doses of Tamoxifen (3 and 6 mM)
These results indicated that Tamoxifen was not cytotoxic for MCs and that rather, it produced an anti-apoptotic effect in these cells (Figure S1)

Summary

Introduction

In peritoneal dialysis (PD), the peritoneal membrane (PM) is exposed to bio-incompatible dialysis solutions, with high content of glucose, which can cause peritoneal injury when associated with peritoneal incidents like repeated episodes of peritonitis or hemoperitoneum [1], [2], [3]. Given the high morbidity and mortality associated with EPS, the lack of specific treatments, and the therapeutic potential of Tamoxifen [14], in 1992 we started the first clinical study to analyze the effects of oral Tamoxifen treatment (20 mg every 12 h) in PD patients suffering this peritoneal complication. Their evolution was compared with a historic EPS control group collected between 1980 and 1992. Similar results were obtained in other clinical studies using Tamoxifen to treat EPS [16]

Methods

Results

Conclusion