Antifibrotic Effects of Thymus syriacus Essential Oil in Bleomycin-Induced Pulmonary Fibrosis via the TGF-β1/Smad2 Pathway

Background: Pulmonary fibrosis (PF) is an irreversible interstitial lung disease in which TGF-β/SMAD signaling pathway plays a critical role in pathogenesis. Thymus species are known for their anti-inflammatory and antioxidant properties and may suppress PF by modulating this pathway. Therefore, this study aimed to investigate the potential antifi-brotic effects of Thymus syriacus essential oil (TS) on TGF-β/SMAD pathway in bleomycin-induced PF. Metods: PF was induced with bleomycin and TS was administered at concentrations of 50 and 100 mg/ml for 28 days. At the end of the experiment, mRNA and protein levels of TGF-β, Smad2, Col1, and α-SMA in lung tissues were analyzed using real-time PCR and ELISA. TNF-α levels in BALF were measured by ELISA, while tissue ROS levels were determined using 2,7-DHCFDA. Histopathological evaluation was performed using Hematoxylin-Eosin and Masson’s-trichrome staining. Blood samples were ana-lyzed for kidney, liver, and cardiac toxicity markers. The chemical composition of TS was determined by GC-MS. Results: TS-treated groups showed increased body weight and sig-nificantly reduced levels of TGF-β, Smad2, Col1, α-SMA, TNF-α, and ROS compared to the BLM group. PF alterations were markedly attenuated by TS treatment. Carvacrol was identified as major constituent of TS. Conclusion: Overall, TS alleviates pulmonary fibro-sis by suppressing the TGF-β/SMAD2 signaling pathway.