METHODS: ApoE-/- mice were continuously infused with angiotensin II (Ang II) for 4 weeks to develop the AAA model. Intragastric administration of PMQ was initiated 5 days before Ang II infusion and continued for 4 weeks. In vitro, VSMCs were cultured and pretreated with PMQ, stimulated with Ang II. Real-time PCR, western blotting, and immunofluorescence staining were used to examine the roles and mechanisms of PMQ on the phenotypic switching and apoptosis of VSMCs.
RESULTS: PMQ dose-dependently reduced the incidence of Ang II-induced AAA, aneurysm diameter enlargement, elastin degradation, VSMCs phenotypic switching and apoptosis. Furthermore, PMQ also inhibited phenotypic switching and apoptosis in Ang II-stimulated VSMCs. PMQ exerted protective effects by regulating the C/EBPβ/PTEN/AKT/GSK-3β axis. AAV-mediated overexpression of PTEN reduced the therapeutic effects of PMQ in the AAA model mice, suggesting that the effects of PMQ on Ang II-mediated AAA formation were related to the PTEN/AKT/GSK-3β axis. PMQ inhibited VSMCs phenotypic switching and apoptosis by bounding to C/EBPβ at Lys253 with hydrogen bond to regulate C/EBPβ nuclear translocation and PTEN/AKT/GSK-3β axis, thereby inhibiting Ang II-induced AAA formation.
CONCLUSIONS: Pentamethylquercetin inhibits angiotensin II-induced abdominal aortic aneurysm formation by bounding to C/EBPβ at Lys253. Therefore, PMQ prevents the formation of AAA and reduces the incidence of AAA.
方法:ApoE-/-小鼠连续输注血管紧张素II(AngII)4周以建立AAA模型。在AngII输注前5天开始胃内给药PMQ,并持续4周。体外,培养VSMC并用PMQ预处理,用AngII刺激。实时PCR,西方印迹,免疫荧光染色检测PMQ在VSMCs表型转换和凋亡中的作用及机制。
结果:PMQ剂量依赖性地降低了AngII诱导的AAA的发生率,动脉瘤直径扩大,弹性蛋白降解,VSMCs表型转换和凋亡。此外,PMQ还抑制AngII刺激的VSMC中的表型转换和凋亡。PMQ通过调节C/EBPβ/PTEN/AKT/GSK-3β轴发挥保护作用。AAV介导的PTEN过表达降低了PMQ在AAA模型小鼠中的治疗作用,提示PMQ对AngII介导的AAA形成的影响与PTEN/AKT/GSK-3β轴有关。PMQ通过在Lys253处以氢键结合C/EBPβ来调节C/EBPβ核易位和PTEN/AKT/GSK-3β轴,从而抑制VSMCs表型转换和凋亡,从而抑制AngII诱导的AAA形成。
结论:五甲基槲皮素通过在Lys253处与C/EBPβ结合而抑制血管紧张素II诱导的腹主动脉瘤形成。因此,PMQ防止AAA的形成并降低AAA的发生率。