Antifibrotic Mechanism of Cinobufagin in Bleomycin-Induced Pulmonary Fibrosis in Mice.

Xiaohe Li,Lixin Li,Shaoyan Gao,Yunyao Cui,Kai Huang,Jingjing Gao,Mengying Huang,Shuaishuai Liu,Honggang Zhou,Jiahe Mao,Cheng Yang,Tao Sun,Zhun Bi

doi:10.3389/fphar.2019.01021

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually fatal lung disease that is characterized by fibroblast proliferation and extracellular matrix remodeling, which result in irreversible distortion of the lung’s architecture and the formation of focal fibrous hyperplasia. The molecular mechanism by which pulmonary fibrosis develops is not fully understood, and no satisfactory treatment currently exists. However, many studies consider that aberrant activation of TGF-β1 frequently promotes epithelial-mesenchymal transition (EMT) and fibroblast activation in pulmonary fibrosis. Cinobufagin (CBG), a traditional Chinese medicine, has been widely used for long-term pain relief, cardiac stimulation, and anti-inflammatory and local anesthetic treatments. However, its role in pulmonary fibrosis has not yet been established. We investigated the hypothesis that cinobufagin plays an inhibitory role on TGF-β1 signaling using a luciferase-reporter assay. We further explored the effect of cinobufagin on pulmonary fibrosis both in vitro and in vivo. The in vitro experiments showed that cinobufagin suppresses TGF-β1/Smad3 signaling in a dose-dependent manner, attenuates the activation and differentiation of lung fibroblasts and inhibits EMT induced by TGF-β1 in alveolar epithelial cells. The in vivo experiments indicated that cinobufagin significantly alleviates bleomycin-induced collagen deposition and improves pulmonary function. Further study showed that cinobufagin could attenuate bleomycin-induced inflammation and inhibit fibroblast activation and the EMT process in vivo. In summary, cinobufagin attenuates bleomycin-induced pulmonary fibrosis in mice via suppressing inflammation, fibroblast activation and epithelial–mesenchymal transition.

Highlights

Pulmonary fibrosis (PF) is the final stage of various interstitial lung diseases and is characterized by excessive deposition of extracellular matrix and destruction of lung parenchyma
The results showed that cinobufagin inhibited the Transforming growth factor-β1 (TGF-β1)/ Smad3 signaling pathway in a concentration-dependent manner (Figure 1B)
Since TGF-β1 signaling pathway plays an important role in the progression of epithelial-mesenchymal transition (EMT), and former studies showed that cinobufagin could suppressing TGF-β1/Smad3 and transforming growth factor-β (TGF-β)/MAPK signaling pathway in the activation of fibroblasts, we further evaluated whether cinobufagin could regulated Smad3 and MAPK signaling in EMT process of A549 cells

Summary

Introduction

Pulmonary fibrosis (PF) is the final stage of various interstitial lung diseases and is characterized by excessive deposition of extracellular matrix and destruction of lung parenchyma. Idiopathic pulmonary fibrosis (IPF) is the most common and fatal respiratory disease, with a mean survival of 2.5 years after diagnosis (Borensztajn et al, 2013; Maher, 2013). IPF is characterized by diffuse alveolitis and alveolar structure disorder, the formation of honeycomb focal fibrous in the patient’s lungs, and the occurrence of pulmonary interstitial fibrosis. The incidence and mortality of Cinobufagin Alleviates Bleomycin-Induced Pulmonary Fibrosis. There are only two drugs available for the treatment of mild/moderate IPF, pirfenidone and nintedanib, but these two drugs cannot prolong the survival of patients (Ogura et al, 2015; Jo et al, 2016). It is important to study the pathogenesis of the disease and develop new therapeutic drugs or methods

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Results

Conclusion