β-Hydroxybutyrate directly binds to ANXA2 and suppresses AAA progression by inhibiting macrophage infiltration and vascular smooth muscle cell apoptosis

Background Abdominal aortic aneurysm (AAA) is defined as a pathological dilation of the abdominal aorta exceeding 50% of its normal diameter. Due to its complex pathogenesis and limited treatment options, AAA is associated with high mortality and lacks effective pharmacological therapy. β-Hydroxybutyrate (β-HB), a major ketone body derived from fatty acid β-oxidation, has shown cardiovascular protective effects.β-HB supplementation alleviates hypertension and vascular remodeling in salt-sensitive models. However, the role of β-HB in AAA remains unclear. Purpose This study aimed to identify β-HB through targeted metabolomics and investigate its role in AAA progression via Annexin A2(ANXA2)-mediated regulation of inflammation and vascular smooth muscle cell (VSMC) apoptosis. Methods Targeted Q200-based metabolomic profiling of plasma samples identified differential metabolites in a discovery cohort, followed by single-target validation in an independent cohort. An Ang II–induced AAA model was established in 10-week-old male ApoE⁻/⁻ mice (1000 ng/kg/day, 28 days), with oral β-HB supplementation to assess its effect on aneurysm development. In vitro,Biacore T200–based affinity capture coupled with mass spectrometry identified ANXA2 as a binding partner of β-HB. Further mechanistic analyses demonstrated that ANXA2 mediates AAA progression through a critical signaling pathway. Results Consistent with findings in human subjects, plasma β-HB levels were reduced in an experimental AAA mouse model. Exogenous β-HB supplementation decreased AAA incidence and attenuated aneurysm progression. Affinity-based pull-down screening identified ANXA2 as a candidate β-HB binding partner, with direct interaction confirmed by microscale thermophoresis (MST), cellular thermal shift assay (CETSA), and complementary pull-down analyses. Molecular docking using AutoDock Vina further supported the interaction, yielding a predicted binding affinity of −4.9 kcal/mol.To define the role of ANXA2 in vivo, AAV9-mediated gene modulation was performed in the AAA mouse model. Overexpression of ANXA2 combined with β-HB supplementation reduced AAA incidence and limited aneurysm progression. Mechanistic analyses indicate that β-HB exerts protective effects through ANXA2-dependent pathways, characterized by reduced macrophage infiltration and diminished SMC apoptosis. Interaction of β-HB with ANXA2 appears to stabilize ANXA2–TLR4 and ANXA2–GSK3β complexes, thereby restraining inflammation and preserving SMC phenotypic stability. Conclusion Collectively, these findings indicate that β-HB modulates AAA initiation and progression, highlighting its potential as a therapeutic target. This study provides mechanistic insight into metabolic regulation of AAA and suggests a possible shift from reactive intervention toward preventive strategies.