Impinging flow regulates endothelial cell injury via HMGB1-mediated ferroptosis to promote intracranial aneurysm formation and progression.

Abstract

BACKGROUND: Intracranial aneurysms (IA) are a life-threatening cerebrovascular condition whose pathogenesis involves endothelial cell (EC) dysfunction driven by haemodynamic forces. While High Mobility Group Box 1 (HMGB1) and ferroptosis, an iron-dependent form of cell death, have been implicated in vascular diseases, their specific roles and interplay within IA remain unclear. METHODS: Human IA and superficial temporal artery (STA) tissues were analysed. A rat IA model was established and treated with the HMGB1 inhibitor glycyrrhizic acid (GA). In vitro, human umbilical vein endothelial cells (HUVECs) were subjected to impinging flow using a T-chamber system to simulate pathological haemodynamics. Interventions included HMGB1 knockdown, and treatment with GA, the Nrf2 inhibitor ML385, or the ferroptosis inhibitor Ferrostatin-1 (Fer-1). RESULTS: Human and rat IA tissues exhibited significant EC loss, elevated HMGB1 expression, and hallmarks of ferroptosis, including iron deposition, increased ACSL4, and decreased GPX4. In rats, GA treatment mitigated IA severity and vascular pathological damage. In vitro, impinging flow induced EC ferroptosis, evidenced by increased lipid peroxidation, iron accumulation, and ACSL4/GPX4 imbalance, alongside the activation and nuclear translocation of Nrf2, NF-κB, and HMGB1. HMGB1 knockdown or inhibition via GA attenuated impinging flow-induced ferroptosis and NF-κB activation, but did not affect Nrf2. Conversely, Nrf2 inhibition using ML385 exacerbated ferroptosis and upregulated HMGB1 and NF-κB. Inhibiting ferroptosis with Fer-1 suppressed HMGB1 and NF-κB expression while enhancing Nrf2 pathway activity. CONCLUSION: Our findings demonstrate that impinging flow promotes EC ferroptosis via the HMGB1/NF-κB pathway, while the Nrf2/HO-1 axis acts as a compensatory protective mechanism. HMGB1 is a critical driver of IA progression, positioning it as a promising therapeutic target for preventing IA formation and rupture.