Phillyrin attenuates TGF-β1-induced pulmonary fibrosis by modulating the Nrf2/HO-1 pathway and epithelial-mesenchymal transition

Background: Phillyrin (Phi), a natural lignan glycoside derived from Fructus Forsythiae, has been reported to exhibit anti-inflammatory and antioxidant activities. In this study, we investigated its therapeutic potential in a TGF-β1-induced model of epithelial-mesenchymal transition (EMT) in A549 human alveolar epithelial cells. Methods: The mechanisms of Phi were initially predicted using network pharmacology and molecular docking. Subsequently, A549 cells were stimulated with TGF-β1 and treated with Phi. Key assessments included cell viability, inflammatory and oxidative stress markers, EMT-related proteins (E-cadherin, α-SMA, vimentin), and fibrosis-associated molecules (collagen I, fibronectin, MMP-2). The activation of the Nrf2/HO-1 antioxidant pathway was also examined. Results: Phi significantly attenuated TGF-β1-induced EMT and fibrotic responses in A549 cells. It not only suppressed inflammatory cytokine production and oxidative stress but also restored epithelial marker expression and reduced mesenchymal and fibrotic protein levels. Moreover, Phi upregulated the Nrf2/HO-1 signaling pathway, enhancing cellular antioxidant capacity. Conclusion: These findings suggest that Phi possesses potent anti-inflammatory, antioxidant, and anti-fibrotic properties, effectively inhibiting TGF-β1-driven EMT in alveolar epithelial cells. Phi may represent a promising therapeutic candidate for treating idiopathic pulmonary fibrosis and other fibrotic lung diseases.