Gypenosides Attenuate Pulmonary Fibrosis by Inhibiting the AKT/mTOR/c-Myc Pathway.

Suqing Liu,Shan He,Qingqing Yang,Baojun Liu,Jinfeng Wu,Ming Li,Chunhui Qi,Binbin Dong,Tao Yang

doi:10.3389/fphar.2021.806312

Abstract

Gypenosides (Gyps), the major active constituents isolated from Gynostemma pentaphyllum, possess anti-inflammatory and antioxidant activities. Previous studies have demonstrated that Gyps displayed potent ameliorative effects on liver fibrosis and renal fibrosis. In this study, we found that Gyps significantly reduced the mortality of bleomycin-induced pulmonary fibrosis mice (40% mortality rate of mice in the model group versus 0% in the treatment group). Masson staining showed that Gyps could reduce the content of collagen in the lung tissue of pulmonary fibrosis mice Masson staining and immunohistochemistry demonstrated that the expression of the collagen gene α-SMA and fibrosis gene Col1 markedly decreased after Gyps treatment. The active mitosis of fibroblasts is one of the key processes in the pathogenesis of fibrotic diseases. RNA-seq showed that Gyps significantly inhibited mitosis and induced the G2/M phase cell cycle arrest. The mTOR/c-Myc axis plays an important role in the pathological process of pulmonary fibrosis. RNA-seq also demonstrated that Gyps inhibited the mTOR and c-Myc signaling in pulmonary fibrosis mice, which was further validated by Western blot and immunohistochemistry. AKT functions as an upstream molecule that regulates mTOR. Our western blot data showed that Gyps could suppress the activation of AKT. In conclusion, Gyps exerted anti-pulmonary fibrosis activity by inhibiting the AKT/mTOR/c-Myc pathway.

Highlights

Pulmonary fibrosis (PF) is a chronic, progressive, and lethal interstitial lung disease, with a poor prognosis and median survival of 3–5 years after diagnosis (Masefield et al, 2019)
Twenty-one days after BLM injection, hematoxylin and eosin (HE) and Masson’s trichrome staining showed a remarkably thick alveolar wall and collapse of alveolar septa, inflammatory cell infiltration, loss of lung architecture, and excess deposition of collagen in the BLM-treated group compared with the control group, whereas treatment with Gyps markedly attenuated the injury of lung architecture and the deposition of collagen caused by BLM (Figures 3A,B,E,F)
The data showed that BLM upregulated the expressions of the collagen gene α-SMA and fibrosis gene Col1 in the lung tissue compared with the control group, while the expressions of αSMA and Col1 in the lung tissue of Gyps-treated mice were significantly lower than those in the model mice (Figures 3C,D,G,H)

Summary

Introduction

Pulmonary fibrosis (PF) is a chronic, progressive, and lethal interstitial lung disease, with a poor prognosis and median survival of 3–5 years after diagnosis (Masefield et al, 2019). There are only two drugs approved by the U.S Food and Drug Administration (FDA) for the treatment of PF: nintedanib and pirfenidone (Yamazaki et al, 2021). These two small molecule drugs target receptor tyrosine kinase (RTK). Gypenosides Attenuate Pulmonary Fibrosis and the transforming growth factor (TGF-β), respectively. They can slow down the progression of PF, the high cost and strong toxic effects on the liver and kidneys limit their clinical application (Yang et al, 2019). Owing to the characteristics of multi-components, multi-targets, and multilevel interactions, TCM can improve the survival and life quality of the patients with PF disease to a certain extent (Wang et al, 2020)

Methods

Results

Conclusion