Abstract

Background: In pulmonary arterial hypertension (PAH), ferroptosis could influence vascular remodeling by affecting the pulmonary artery endothelial cells (PAECs). However, the underlying pathogenic mechanisms of ferroptosis in PAH and its impact on the pulmonary vascular cellular landscape remain poorly understood. Methods: In this study, we integrated single-cell transcriptomic sequencing, proteomics, and summary-data-based Mendelian randomization to investigate the regulatory mechanisms of ferroptosis in PAH. Our findings were validated using monocrotaline-induced PAH rat models and hypoxia-induced PAEC models. Results: Single-cell transcriptomic analysis revealed an increased propensity for ferroptosis in PAECs, while general capillary endothelial cells showed enhanced proliferative tendencies. Integrated analysis of single-cell transcriptomics, proteomics, and summary-data-based Mendelian randomization suggested that SMAD7 may serve as a negative regulator of ferroptosis in PAECs. Additionally, experiments conducted both in vitro and in vivo showed that reducing SMAD7 expression enhanced ferroptosis in PAECs, whereas SMAD7 overexpression alleviated ferroptosis and pulmonary vascular remodeling, potentially by blocking the transforming growth factor-beta-1-SMAD2/3 signaling pathway. Conclusions: This study provides preliminary evidence that SMAD7 may negatively regulate ferroptosis via the transforming growth factor-beta-1-SMAD2/3 pathway in PAECs and thereby contribute to pulmonary vascular remodeling in PAH. These findings highlight SMAD7 as a potential therapeutic target for PAH.