MAChR activation induces epithelial‐mesenchymal transition on lung epithelial cells (1176.10)

Abstract

Objective: Epithelial‐mesenchymal transition (EMT) is a physiological process that plays important role in pathogenesis of chronic obstructive pulmonary disease (COPD). Although a number of molecules involved in ACh‐mediated airway inflammation and remodeling have been identified, little is known regarding the role of ACh in EMT. In this study, we examined the effects of ACh on TGF‐β1‐induced EMT, and the pathway involved in these processes Methods: Human lung epithelial cells were stimulated with carbachol, an analogue of ACh, and epithelial and mesenchymal marker proteins were evaluated using western blot and immunofluorescence analyses.Results: Decreased E‐cadherin expression and increased vimentin and α‐SMA expression induced by TGF‐β1 in the human alveolar epithelial cell line (A549) were significantly abrogated by the non‐selective mAChR antagonist atropine and enhanced by the acetylcholinesterase inhibitor physostigmine. An EMT event in lung epithelial cells also occurred in response to physostigmine alone. Furthermore, ChAT express and ACh release by A549 cells were enhanced by TGF‐β1 which release also trigged by ACh analogue carbachol. Interestingly, mAChR stimulation with carbachol also induced EMT in alveolar epithelial cells (A549) as well as in bronchial epithelial cells (16HBE) in a time‐ and concentration‐dependent manner, the induction of carbachol was abrogated by selective antagonist of M1 (pirenzepine) and M3 (4‐DAMP) mAChRs, but not by M2 (methoctramine) antagonist. Carbachol‐induced EMT occurred through phosphorylation of Smad2/3 and ERK, which was also inhibited by pirenzepine and 4‐DAMP.Conclusions: Our findings indicate that mAChR activation, perhaps via M1 and M3 mAChR, induced lung epithelial cells to undergo EMT and a cooperative regulation by mAChR activation and TGF‐β1 expression was involved in EMT, leading to airway remodeling.Grant Funding Source: Supported by National Natural Science Foundation of China Nos.30873109 and 81173084