Sulforaphane attenuates pulmonary fibrosis by inhibiting the epithelial-mesenchymal transition

Sun Young Kyung,Eun Suk Son,Sung Hwan Jeong,Jin Young Yoon,Yu Jin Kim,Jeong Woong Park,Dae Young Kim

doi:10.1186/s40360-018-0204-7

Sun Young Kyung, Eun Suk Son + Show 5 more

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https://doi.org/10.1186/s40360-018-0204-7

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Abstract

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease with no effective treatment. The epithelial-mesenchymal transition (EMT) is a critical stage during the development of fibrosis. To assess the effect of sulforaphane (SFN) on the EMT and fibrosis using an in vitro transforming growth factor (TGF)-β1-induced model and an in vivo bleomycin (BLM)-induced model.MethodsIn vitro studies, cell viability, and cytotoxicity were measured using a Cell Counting Kit-8. The functional TGF-β1-induced EMT and fibrosis were assessed using western blotting and a quantitative real-time polymerase chain reaction. The lungs were analyzed histopathologically in vivo using hematoxylin and eosin and Masson’s trichrome staining. The BLM-induced fibrosis was characterized by western blotting and immunohistochemical analyses for fibronectin, TGF-β1, E-cadherin (E-cad), and α-smooth muscle actin (SMA) in lung tissues.ResultsSFN reversed mesenchymal-like changes induced by TGF-β1 and restored cells to their epithelial-like morphology. The results confirmed that the expression of the epithelial marker, E-cadherin, increased after SFN treatment, while expression of the mesenchymal markers, N-cadherin, vimentin, and α-SMA decreased in A549 cells after SFN treatment. In addition, SFN inhibited TGF-β1-induced mRNA expression of the EMT-related transcription factors, Slug, Snail, and Twist. The SFN treatment attenuated TGF-β1-induced expression of fibrosis-related proteins, such as fibronection, collagen I, collagen IV, and α-SMA in MRC-5 cells. Furthermore, SFN reduced the TGF-β1-induced phosphorylation of SMAD2/3 protein in A549 cells and MRC-5 cells. BLM induced fibrosis in mouse lungs that was also attenuated by SFN treatment, and SFN treatment decreased BLM-induced fibronectin expression, TGF-β1 expression, and the levels of collagen I in the lungs of mice.ConclusionsSFN showed a significant anti-fibrotic effect in TGF-β-treated cell lines and BLM-induced fibrosis in mice. These findings showed that SFN has anti-fibrotic activity that may be considered in the treatment of IPF.

Highlights

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease with no effective treatment
Growth factors downregulate genes expressed in epithelial cells, such as E-cadherin (E-cad), and upregulate genes normally expressed in mesenchymal cells, such as N-cadherin (N-cad), vimentin, and α-smooth muscle actin (α-SMA) [8, 9]
transforming growth factor (TGF)-β1 treatment of A549 lung epithelial-like cells resulted in a spindle-like mesenchymal phenotype and the loss of cellcell contact

Summary

Introduction

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal disease with no effective treatment. Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrotic lung disease characterised by expansion of fibroblast/myofibroblast populations and aberrant remodelling, which can lead to respiratory failure and death [1]. In IPF, the ability of alveolar epithelial cells to repair against recurrent microinjury is impaired and they secrete fibrogenic growth factors, such as TGF-β, and exhibit fibroblast/ myofibroblast proliferation and activation. Epithelial mesenchymal transition (EMT), and circulating fibroblasts are likely sources of myofibroblasts [4]. EMT is a process whereby epithelial cells transition into cells of the mesenchymal phenotype, such as fibroblasts or myofibroblasts [5,6,7]. This process is controlled by a group of transcription factors referred to as EMT regulators, which include Snail, Slug, Twist, ZEB1, SIP1, and E12/47 [7, 8, 10, 11]

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