Pharmacological Inhibition of Ferroptosis Attenuates Experimental Abdominal Aortic Aneurysm Formation

BACKGROUND: The pathogenesis of abdominal aortic aneurysm (AAA) formation involves vascular inflammation, thrombosis formation, and programmed cell death, leading to aortic remodeling. In this study, we deciphered the role of ferroptosis, an excessive iron-mediated cell death in macrophages during aortic inflammation and vascular remodeling in AAA formation. METHODS: Single-cell RNA sequencing analysis was performed on the human AAA tissue database. AAAs were induced in male and female C57BL/6 (wild-type) mice using 2 models with topical elastase or elastase+β-aminopropionitrile, with or without liproxstatin-1, a specific ferroptosis inhibitor, treatment. Aortic diameter, cytokine expression, histology, hallmarks of ferroptosis such as lipid peroxidation and glutathione, and lipid analysis using mass spectrometry were measured in aortic tissue extracts. In vitro studies deciphered the crosstalk of macrophages and smooth muscle cells and analyzed ferroptosis and MMP (matrix metalloproteinase) expressions. RESULTS: Single-cell RNA sequencing analysis demonstrated significant differences in ferroptosis-related genes in macrophages from human AAAs compared with control aortic tissue. Using 2 established murine models of AAA and aortic rupture in wild-type mice, we observed that treatment with liproxstatin-1 significantly attenuated aortic diameter, proinflammatory cytokine production, immune cell infiltration (neutrophils and macrophages), elastic fiber disruption, and increased smooth muscle cell α-actin expression compared with untreated mice. Lipidomic analysis using mass spectrometry shows a significant increase in ceramides and a decrease in intact lipid species levels in murine AAA tissue compared with controls in the murine AAA model. Mechanistically, in vitro studies demonstrate that liproxstatin-1 treatment of macrophages mitigated ferroptosis and MMP9 expression, as well as the crosstalk with aortic smooth muscle cells by downregulating MMP2 secretion. CONCLUSIONS: Taken together, this study demonstrates that pharmacological inhibition by liproxstatin-1 mitigates macrophage-dependent ferroptosis, contributing to the inhibition of aortic inflammation and remodeling during AAA formation.