FOXO1-driven endothelial senescence in bicuspid aortic valve-associated thoracic aortic aneurysm.

Bicuspid aortic valve (BAV) is a congenital malformation that predisposes individuals to thoracic aortic aneurysm (TAA), with endothelial dysfunction playing a pivotal role in its pathogenesis. Endothelial cell senescence is a hallmark of endothelial dysfunction, yet direct evidence linking endothelial senescence to BAV-TAA has not been established. In this study, we generated induced pluripotent stem cells (iPSCs) from both BAV-TAA patients and healthy controls, subsequently differentiating them into endothelial cells (iECs). Our findings revealed that BAV-TAA-iECs exhibited senescence phenotype, including impaired proliferation, diminished migratory capacity, upregulated senescence markers (p53, p21, p16), and a pronounced senescence-associated secretory phenotype (SASP). Transcriptomic analysis through RNA sequencing indicated aberrant activation of the FOXO signaling pathway in BAV-TAA-iECs which might contribute to BAV-TAA-iEC senescence. Inhibition of FOXO1 signaling using AS1842856 effectively reversed the senescence phenotype, restored endothelial nitric oxide synthase (eNOS) expression, attenuated SASP cytokine levels, and mitigated inflammation through the p65 and p38 signaling pathways. These findings suggest that endothelial cell senescence plays a critical role in the pathogenesis of BAV-TAA, and targeting FOXO1 signaling may represent a promising therapeutic strategy for BAV-associated aortic diseases.