Abstract
BackgroundParticulate matters (PMs) in ambient air pollution are closely related to the incidence of respiratory diseases and decreased lung function. Our previous report demonstrated that PMs-induced oxidative stress increased the expression of proinflammatory intracellular adhesion molecule-1 (ICAM-1) through the IL-6/AKT/STAT3/NF-κB pathway in A549 cells. However, the role of O-PMs in epithelial-mesenchymal transition (EMT) development and pulmonary fibrosis and the related mechanisms have not been determined. The aim of this study was to investigate the effects of O-PMs on the pathogenesis of EMT and pulmonary fibrosis as well as the expression of ETS-1 and NF-κB p65, in vitro and in vivo.ResultsO-PMs treatment induced EMT development, fibronectin expression, and cell migration. O-PMs affected the expression of the EMT-related transcription factors NF-κB p65 and ETS-1. Interference with NF-κB p65 significantly decreased O-PMs-induced fibronectin expression. In addition, O-PMs affected the expression of fibronectin, E-cadherin, and vimentin through modulating ETS-1 expression. ATN-161, an antagonist of integrin α5β1, decreased the expression of fibronectin and ETS-1 and EMT development. EMT development and the expression of fibronectin and ETS-1 were increased in the lung tissue of mice after exposure to PMs for 7 and 14 days. There was a significant correlation between fibronectin and ETS-1 expression in human pulmonary fibrosis tissue.ConclusionO-PMs can induce EMT and fibronectin expression through the activation of transcription factors ETS-1 and NF-κB in A549 cells. PMs can induce EMT development and the expression of fibronectin and ETS-1 in mouse lung tissues. These findings suggest that the ETS-1 pathway could be a novel and alternative mechanism for EMT development and pulmonary fibrosis.
Highlights
Fine particulate matter (PM) from the environment is inhaled into the respiratory tract, accumulates and penetrates into alveolar cells, and may result in structural damage and functional impairment of the respiratory system [1]
O-PMs induced cell migration and epithelial-mesenchymal transition (EMT) development To determine whether O-PMs exposure plays an important role in promoting EMT, we examined the concentration- and time- dependence of O-PMs-induced A549 cell migration using a wound healing assay
A549 cells were incubated with different concentrations of organic solvent soluble PMs (OPMs) for 24 h, and the expression of E-cadherin and vimentin in the cell lysates was determined by Western blot (Fig. 1c)
Summary
Fine particulate matter (PM) from the environment is inhaled into the respiratory tract, accumulates and penetrates into alveolar cells, and may result in structural damage and functional impairment of the respiratory system [1]. Our previous study demonstrated that PMs increased oxidative stress and inflammatory responses in A549 cells [3]. Few studies have focused on the formation of fibrosis, the development of epithelial-mesenchymal transition (EMT) and the related mechanisms caused by PMs exposure. This is the most representative event associated with cell fate and requires attention. Particulate matters (PMs) in ambient air pollution are closely related to the incidence of respiratory diseases and decreased lung function. Our previous report demonstrated that PMs-induced oxidative stress increased the expression of proinflammatory intracellular adhesion molecule-1 (ICAM-1) through the IL-6/AKT/ STAT3/NF-κB pathway in A549 cells. The aim of this study was to investigate the effects of O-PMs on the pathogenesis of EMT and pulmonary fibrosis as well as the expression of ETS-1 and NF-κB p65, in vitro and in vivo
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