EL-7013 Suppresses Pulmonary Fibrosis Partially By Promoting Sirt1 To Modulate The TGF-β1/smad3 Signaling Pathway

Purpose:Idiopathic pulmonary fibrosis（IPF）,a chronic,irreversible and lethal disease,currently lacks a specific therapeutic regimen so new drugs are urgently needed.Pirfenidone（PFD）has been approved by the FDA for IPF treatment.EL-7013 is a new pirfenidone-derived drug.The aim of this study is to investigate whether EL-7013 has a prospective antifibrotic effect and its potential mechanisms.Methods:In this study,we compared the effects of EL-7013 and PFD on the pulmonary fibrosis induced by bleomycin（BLM）administration in vivo or recombinant human TGF-β₁ stimulation in vitro.BLM（3mg/kg）was administered to mice in a single intratracheal instillation.Mice were administereddifferentconcentrationsofEL-7013（50?mg/kg,150?mg/kg,300?mg/kg）and PFD（300?mg/kg）from days 7 to 21.Analogously,10ng/ml recombinant human TGF-β₁ was administered to human embryonic lung fibroblasts（HLF-1）to model fibrosis progression in vitro with or without either 1mM EL-7013 or 1mM PFD treatment.Furthermore,the Sirt1 inhibitor EX-527 was used to simulate the protein expression and activity inhibition of Sirt1.HE and Masson staining were used to evaluate the pathological changes of lung tissue.The content of hydroxyproline（HYP）in lung tissue was detected by HYP test kit.The expression of COL1A1,COL3A1,α-SMA,TGF-β₁,Smad1,Smad3,Phospho-Smad1 and Phospho-Smad3 was detected by Western blot,RT-qPCR and Immunofluorescence staining.Cellular proliferation was detected using a CCK-8 assay.Results:EL-7013treatmentsignificantlymitigatedlung histopathologic changes,collagen deposition,fibroblast proliferation and myofibroblastic transformation while activating Sirt1 and inhibiting the TGF-β₁/Smad3 signaling pathway selectively.Specific inhibition of Sirt1partially neutralized the anti-fibrotic effect of EL-7013 and the inhibition of phosphorylated Smad3.Conclusion:EL-7013 presents a protective effect in pulmonary fibrosis related to Sirt1 activation and TGF-β₁/Smad3 signaling pathway inhibition,indicating a latent therapeutic role of EL-7013 in IPF.