Ethyl acetate fraction of Thesium chinense Turcz. alleviates chronic obstructive pulmonary disease through inhibition of ferroptosis mediated by activating Nrf2/SLC7A11/GPX4 axis

Thesium chinense Turcz., a traditional Chinese herbal medicine, displays good therapeutic efficiency against respiratory diseases (e.g. pneumonia, pharyngitis) in clinical applications, however, its effects on COPD and the mechanism of action are still unclear. This study aims to investigate the therapeutic effect of the ethyl acetate fraction of Thesium chinense Turcz. (TCEA) on COPD and reveal the underlying mechanism. A cigarette smoke (CS)-induced mouse COPD model was established, and the efficacy of TCEA was evaluated using peripheral blood testing, HE and Masson staining, qRT-PCR and ELISA assays. TCEA was analyzed for chemical composition by LC-MS/MS and HPLC. Prediction of major signaling pathways and potential targets was performed by network pharmacology. The molecular mechanism of TCEA was explored by immunoblotting, immunofluorescence staining, flow cytometry, and ubiquitination assay. Finally, potential active small molecules in TCEA were identified by molecular virtual screening. TCEA treatment significantly inhibited the secretion of pro-inflammatory factors and attenuated pathological emphysema. The main chemical constituents of TCEA were identified as flavonoids by UPLC-MS/MS. Network pharmacology analysis enriched the Nrf2 signaling pathway closely related to oxidative stress. Our results suggested that TCEA inhibited ferroptosis by activating Nrf2/SLC7A11/GPX4 axis and inhibiting lipid metabolism-related proteins, ACSL4, ALOX5 and COX2 in vivo and in vitro. Noteworthily, the beneficial impact of TCEA on regulation of SLC7A11 and GPX4 vanished after silencing Nrf2. Moreover, Nrf2 ubiquitination was inhibited by TCEA treatment. Finally, several flavonoids modulating Nrf2 were identified by molecular virtual screening. TCEA significantly alleviated COPD progression by inhibiting ferroptosis primarily through activation of Nrf2/SLC7A11/GPX4 signaling. Flavonoids are the main active components that exert their effects. These findings shed light on the mechanism of action of TCEA and its potential active components, providing a feasible approach for the treatment of COPD.