Isoorientin Ameliorates Macrophage Pyroptosis and Atherogenesis by Reducing KDM4A Levels and Promoting SKP1-Cullin1-F-box E3 Ligase-mediated NLRP3 Ubiquitination

Isoorientin (ISO) is a flavonoid compound with potential antioxidant and antiatherosclerotic properties. This investigation delves into the impact of ISO on macrophage pyroptosis in atherosclerosis (AS) progression and probes its functional mechanism. ApoE^-/- mice were fed a high-fat diet for AS modeling. ISO treatment significantly alleviated atherosclerotic lesions, lipid accumulation, the necrotic core area, and macrophage pyroptosis in model mice. In vitro, ISO reduced oxidized low-density lipoprotein-induced pyroptosis in mouse bone marrow-derived macrophages. The mechanism underlying these effects is linked to a reduction in lysine demethylase 4A (KDM4A) levels in macrophages. Artificial restoration of KDM4A levels reversed the protective effects of ISO and promoted atherogenesis. KDM4A was found to inhibit the transcription of S-phase kinase-associated protein 1 (SKP1), leading to impaired SKP1-Cullin1-F-box (SCF) E3 ligase-mediated ubiquitination of NLR family pyrin domain containing 3 (NLRP3). This disruption promoted NLRP3 inflammasome assembly and activation. Artificial SKP1 overexpression reduced NLRP3 levels and reversed the protective effects of ISO. In conclusion, this study demonstrated that ISO inhibits macrophage pyroptosis and atherogenesis by reducing KDM4A levels and restoring SCF complex-mediated ubiquitination of NLRP3.