Abstract
Pulmonary fibrosis is common in a variety of inflammatory lung diseases, there is currently no effective clinical drug treatment. It has been reported that the ethanol extract of Eclipta prostrata L. can improve the lung collagen deposition and fibrosis pathology induced by bleomycin (BLM) in mice. In the present study, we studied whether wedelolactone (WEL), a major coumarin ingredient of E. prostrata, provided protection against BLM-induced pulmonary fibrosis. ICR or C57/BL6 strain mice were treated with BLM to establish lung fibrosis model. WEL (2 or 10 mg/kg) was given daily via intragastric administration for 2 weeks starting at 7-day after intratracheal instillation. WEL at 10 mg/kg significantly reduced BLM-induced inflammatory cells infiltration, pro-inflammatory factors expression, and collagen deposition in lung tissues. Additionally, treatment with WEL also impaired BLM-induced increases in fibrotic marker expression (collagen I and α-SMA) and decrease in an anti-fibrotic marker (E-cadherin). Treatment with WEL significantly prevented BLM-induced increase in TGF-β1 and Smad2/3 phosphorylation in the lungs. WEL administration (10 mg/kg) also significantly promoted AMPK activation compared to model group in BLM-treated mice. Further investigation indicated that activation of AMPK by WEL can suppressed the transdifferentiation of primary lung fibroblasts and the epithelial mesenchymal transition (EMT) of alveolar epithelial cells, the inhibitive effects of WEL was significantly blocked by an AMPK inhibitor (compound C) in vitro. Together, these results suggest that activation of AMPK by WEL followed by reduction in TGFβ1/Raf-MAPK signaling pathways may have a therapeutic potential in pulmonary fibrosis.
Highlights
Eclipta prostrata L. is widely used to treat respiratory diseases such as diphtheria, pertussis, tuberculosis in the traditional medicine of China (Roy et al, 2008; Deng and Fang, 2012), which exhibits hepatoprotective (Tabassum and Agrawal, 2004; Manvar et al, 2012), anti-tumor (Liu et al, 2012) and other biological activities (Tewtrakul et al, 2011; Jaiswal et al, 2012)
WEL Protects Against Bleomycin-Induced Pulmonary Fibrosis in ICR Mice
Bleomycin-induced pulmonary fibrosis (PF) model in mice is characterized by activated myofibroblasts (Bhattacharyya et al, 2013)
Summary
Eclipta prostrata L. is widely used to treat respiratory diseases such as diphtheria, pertussis, tuberculosis in the traditional medicine of China (Roy et al, 2008; Deng and Fang, 2012), which exhibits hepatoprotective (Tabassum and Agrawal, 2004; Manvar et al, 2012), anti-tumor (Liu et al, 2012) and other biological activities (Tewtrakul et al, 2011; Jaiswal et al, 2012). It has been reported that the methanol extract of this plant significantly attenuated experimental pulmonary fibrosis in mice (You et al, 2015). It has been found that WEL, a main component of E. prostrata, can improve bronchial epithelial cell injury (Ding et al, 2015) and fibrosis process of activated hepatic stellate cells (Xia et al, 2013), its effects on pulmonary function, collagen deposition and epitheliamesenchymal transition remain to be researched. Researchers have identified the close relationship between AMPK activation and lung fibrogenesis (Sato et al, 2016; Rangarajan et al, 2018). The administration of WEL can attenuate hepatic steatosis in mice by activating AMPK (Zhao Y. et al, 2015), but the therapeutic effect of WEL on pulmonary fibrosis is not sure. The fibrotic response is driven by abnormally activated alveolar epithelial cells resulting in epithelial to mesenchyme transition (EMT) and formation of myofibroblast foci secreting amounts of ECM (Ley et al, 2011; Wynn, 2011)
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