Vascular smooth muscle cell ferroptosis and abdominal aortic aneurysm

项目摘要/摘要 腹主动脉瘤(Aaa)是一种永久性腹主动脉扩张，病死率高，但病死率有限。 治疗方案。目前，还没有有效的临床药物来预防、延缓或逆转这种生长。 或腹主动脉破裂，但对症状性动脉瘤或动脉瘤的开放性或血管内修补术除外 破裂的风险很高。血管平滑肌细胞(VSMC)在维持血管壁完整性中起着关键作用 而VSMC耗竭是AAA的一个特征。铁性下垂是一种程序性细胞 铁中毒依赖于铁的死亡，其特征是过氧化脂质的积累吸烟是一口井- 已确定AAA危险因素，香烟烟雾提取物可诱导VSMC铁下垂。谷胱甘肽过氧化物酶4 (Gpx4)已被确定为铁下垂和细胞凋亡的关键抑制因子。人类遗传学与基因 Expression Omnibus数据库已经证明，Gpx4表达减少与 患AAA的风险增加。我们的初步研究表明，Gpx4在大鼠的主动脉中显著减少。 AAA患者和动物模型。尼古丁，一种公认的AAA风险因素，降低了Gpx4和SMC 收缩蛋白的表达。我们假设AAA危险因素可通过 被低估的途径，即动脉内的铁性下垂导致AAA的形成和破裂。我们生成了 VSMC特异性Gpx4基因敲除小鼠(Gpx4SMKO)，将MYH11-CRE与Gpx4Flox/Flox小鼠杂交。什么时候 血管紧张素II(Ang II)诱发动脉瘤并伴有高胆固醇血症，约50% Gpx4SMKO小鼠因AAA破裂而死亡。Gpx4SMKO小鼠的发病率和最大直径 均大于Gpx4FLOX/FLOX对照组小鼠。特定目标1将定义特定于VSMC的保护作用 使用我们的新型VSMC选择性Gpx4转基因小鼠在AAA中检测Gpx4。我们还将研究以下方面的影响 血管周围应用弹性蛋白酶AAA的不同小鼠模型的VSMC特异性Gpx4基因敲除 不会产生破裂的型号。目标2将确定依赖于Gpx4的保护机制 VSMC使用增益型和损失型功能策略。我们将研究Gpx4对AAA相关基因的影响 刺激诱导的细胞死亡、VSMC表型转换和炎症反应 小鼠腹主动脉平滑肌细胞。目标3将定义Gpx4的局部激活可减弱AAA 发病机制是通过增强VSMC抵抗病理因素的能力来实现的。此外，我们将研究 Gpx4激活剂是否可以预防动脉瘤的发展和破裂。圆满完成 拟议的研究将建立调控AAA中VSMC丢失和血管炎症的新机制， 这可能会促进我们对AAA形成的理解，并最终导致新的策略 治疗AAA。

PROJECT SUMMARY/ABSTRACT Abdominal aortic aneurysm (AAA) is a permanent abdominal aorta expansion with high mortality but limited treatment options. Currently, there are no effective clinical medicines to prevent, delay, or reverse the growth or rupture of AAA, except an open or endovascular surgical repair for symptomatic aneurysms or aneurysms at high risk for rupture. Vascular smooth muscle cells (VSMC) are crucial in maintaining vascular wall integrity and function, while VSMC depletion is a characteristic feature of AAA. Ferroptosis is a type of programmed cell death dependent on iron and characterized by the accumulation of lipid peroxides. Smoking is a well- established AAA risk factor, and cigarette smoke extract induces VSMC ferroptosis. Glutathione peroxidase 4 (GPX4) has been identified as a critical inhibitor of ferroptosis and apoptosis. Human genetics and Gene Expression Omnibus database have demonstrated that decreased GPX4 expression is associated with an increased risk of AAA. Our preliminary studies demonstrate that GPX4 is significantly reduced in the aorta of AAA patients and animal models. Nicotine, a well-established AAA risk factor, reduced GPX4 and SMC contractile protein expression. We posit that AAA risk factors can result in VSMC death via an underappreciated pathway, i.e., ferroptosis in the artery resulting in AAA formation and rupture. We generated VSMC-specific Gpx4 knockout mice (Gpx4SMKO) by crossing Myh11-Cre with Gpx4flox/flox mice. When subjected to aneurysm induction by angiotensin II (Ang II) coupled with hypercholesterolemia, about 50% of Gpx4SMKO mice died due to AAA rupture. The incidence rate and maximal diameters in Gpx4SMKO mice were larger than in Gpx4flox/flox control mice. Specific Aim 1 will define the protective effects of VSMC-specific GPX4 in AAA using our novel VSMC-selective GPX4 transgenic mice. We will also examine the effects of VSMC-specific Gpx4 knockout using a different murine model with perivascular application of elastase, an AAA model that does not produce rupture. Aim 2 will determine the GPX4-dependent protective mechanisms in VSMC using gain- and loss-of-function strategies. We will examine the effects of GPX4 on AAA-relevant stimuli-induced cell death, VSMC phenotypic switch, and inflammatory responses in primary human and mouse abdominal aortic smooth muscle cells. Aim 3 will define that local activation of GPX4 attenuates AAA pathogenesis by enhancing VSMC capacity of resistance to pathologic factors. Further, we will examine whether the GPX4 activator protects against aneurysm development and rupture. Successful completion of the proposed studies will establish novel mechanisms regulating VSMC loss and vascular inflammation in AAA, which are likely to advance our understanding of the AAA formation and ultimately lead to novel strategies for treating AAA.