Abstract

Pulmonary arterial hypertension (PAH) is a progressive vascular disorder in which oxidative stress and ferroptosis are key pathogenic drivers. Although β-sitosterol (BS) shows therapeutic potential in PAH; however, its link to ferroptosis modulation remain poorly elucidated. This study evaluated the anti‑PAH efficacy of BS and its underlying mechanisms, focusing on the Nrf2–GPX4 axis, using a monocrotaline (MCT)‑induced rat model and hypoxia‑induced pulmonary arterial endothelial cells (PAECs) and smooth muscle cells (PASMCs). Inflammation responses, reactive oxygen species (ROS), and ferroptosis-related markers were assessed, along with molecular docking and pharmacological inhibition. In vivo , BS significantly ameliorated pulmonary vascular remodeling, improved right ventricular function, and mitigated oxidative stress by reducing ROS and MDA while restoring GSH levels, while up regulating the ferroptosis-protecive proteins xCT and GPX4. Molecular docking suggested direct interaction between BS and Nrf2. Notably, immunofluorescence revealed Nrf2 localization in both CD31 + endothelial and α‑SMA + smooth muscle cells, with BS treatment substantially enhancing Nrf2 accumulation in both lineages. In vitro , BS promoted Nrf2 nuclear translocation in hypoxia-induced PAECs and PASMCs, correlating with suppressed oxidative and inflammatory responses and elevated xCT and GPX4 expression. Notably, the anti-oxidative and anti-ferroptotic effects of BS were abolished by the Nrf2 inhibitor ML385. These findings demonstrate that BS attenuates PAH via Nrf2‑GPX4‑driven ferroptosis inhibition in both in PAECs and PASMCs, uncovering a novel therapeutic target and new research directions regarding PAH pathogenesis and treatment.