Molecular Mechanisms of Pulmonary Fibrosis: The Interaction of Epithelial-mesenchymal Transition and AMPK Pathways in a Bleomycin-induced Model

Abstract

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease marked by excessive extracellular matrix (ECM) deposition, largely mediated by activated fibroblasts. Epithelial-mesenchymal transition (EMT), regulated by transcription factors such as TGF-β, Twist1, and Snail, is a critical mechanism in fibrosis progression. AMP-activated protein kinase (AMPK) has been implicated in modulating fibrotic pathways, but its role in EMT remains unclear. This study aimed to explore the interaction between EMT and AMPK signaling in pulmonary fibrosis.

A bleomycin-induced pulmonary fibrosis mouse model was used. Histological analysis assessed fibrosis and inflammation, while gene expression (TGF-β, Twist1, Snail) was measured by qPCR. Protein levels of E-cadherin, α-SMA, and phosphorylated AMPK were analyzed using Western blotting to evaluate EMT and AMPK activity.

Bleomycin-treated mice showed significant lung inflammation and fibrosis, particularly in the lower region of the left lung. Gene expression analysis revealed elevated TGF-β, Twist1, and Snail in fibrotic areas. Protein analysis demonstrated increased α-SMA and decreased E-cadherin, confirming EMT induction. Notably, AMPK phosphorylation was significantly reduced in fibrotic regions, occurring concurrently with EMT activation.

These findings indicate an inverse relationship between AMPK signaling and EMT in pulmonary fibrosis. EMT may serve as a direct therapeutic target, either by inhibiting transcription factors such as Snail and Twist1 or by modulating upstream metabolic regulators including AMPK