Approach for Elucidating the Molecular Mechanism of Epithelial to Mesenchymal Transition in Fibrosis of Asthmatic Airway Remodeling Focusing on Cl- Channels

Abstract

Airway remodeling caused by asthma is characterized by structural changes of subepithelial fibrosis, goblet cell metaplasia, submucosal gland hyperplasia, smooth muscle cell hyperplasia, and angiogenesis, leading to symptoms such as dyspnea, which cause marked quality of life deterioration. In particular, fibrosis exacerbated by asthma progression is reportedly mediated by epithelial-mesenchymal transition (EMT). It is well known that the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling is closely associated with several signaling pathways, including the TGF-β1/Smad, TGF-β1/non-Smad, and Wnt/β-catenin signaling pathways. However, the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling has not yet been fully clarified. Given that Cl^- transport through Cl^- channels causes passive water flow and consequent changes in cell volume, these channels may be considered to play a key role in EMT, which is characterized by significant morphological changes. In the present article, we highlight how EMT, which causes fibrosis and carcinogenesis in various tissues, is strongly associated with activation or inactivation of Cl^- channels and discuss whether Cl^- channels can lead to elucidation of the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling.

Keywords: Cl− channel; airway; asthma; cell volume; epithelial to mesenchymal transition; fibrosis.

Figure 1

Elucidation of the EMT mechanism in fibrosis of asthmatic airway remodeling by Cl⁻ channel. Activation or inactivation of Cl⁻ channels by genetic manipulation or chemical compound changes the flow of Cl⁻ and water molecule, leading to cell swelling or cell shrinkage. Activation or inactivation of Cl⁻ channels by genetic manipulation or chemical compound also activates or inactivates specific signal pathways such as the TGF-β1/Smad signaling pathway, TGF-β1/non-Smad signaling pathway, Wnt/β-catenin signaling pathway, SHH signaling pathway, and AKT/mTOR signaling pathway. Consequently, Cl⁻ channels may contribute to EMT in fibrosis of asthmatic airway remodeling.