AIM2对动脉粥样硬化斑块发生及其稳定性的机制研究

Atherosclerosis is a chronic inflammatory pathological process which is the critical risk factor leading to acute coronary syndrome. It has become a hot topic in contemporary cardiovascular area to explore the mechanism of development in atherosclerosis and formation of vulnerable plaques..Recent studies demonstrated that absent in melanoma 2 (AIM2) expression is increased in atherosclerotic plaques and exogenous stimulus could induce the expression of AIM2 in vascular endothelial cells and smooth muscle cells.AIM2 increase could activate the inflammasome which subsequently could cause the recruitment of apoptosis-associated speck-like protein containing a CARD(ASC) and following the progression of inflammation.Thus，we speculate AIM2 involves in the progression and stability of atherosclerotic plaques while the specific mechanism remains unclear yet.Based on previous work, we plan to investigate the mechanism of AIM2 in the development of AS by building AIM2 -/- ApoE-/- double knockout mice and overexpression of AIM2 transfected by lentivirus in ApoE-/-mice. And then we build vulnerable plaque model by applying carotid artery casing to further explore the effect and mechanism of AIM2 on vulnerability of carotid artery AS plaque . In vitro, we explore the target and relative signaling pathway of AIM2 affecting the development of AS plaque and plaque vulnerability in further studies, aiming to provide a new intervention target and experimental evidence for ACS.

探讨动脉粥样硬化（Atherosclersis，AS）形成及易损斑块的发生机制，寻找有效的急性冠脉综合征（acute coronary syndrome,ACS）干预靶点成为AS研究领域的热点之一。新近研究及我们的前期工作发现，AIM2（absent in melanoma2）在AS斑块中表达增加，且诱导血管内皮及平滑肌细胞中炎症小体激活。据此我们提出AIM2影响AS发生及斑块稳定性的科学假说，而AIM2在AS发生、易损斑块形成中的作用及其机制研究国内外尚未见报道。本课题组拟构建AIM2-/-ApoE-/-双基因敲除小鼠及慢病毒转染AIM2过表达ApoE-/-小鼠，探讨AIM2对AS斑块发生的影响及其机制，继而用颈动脉套管法构建易损斑块模型，进而探讨AIM2对颈动脉AS斑块易损性的影响及其机制。体外实验研究AIM2影响AS的机制及相关信号通路，为ACS的防治提供新的干预靶点和实验佐证。

黑色素瘤缺如因子2（AIM2）是控制细胞死亡与炎症的炎症小体，它对动脉粥样硬化进展的体内研究尚未明确。本课题组对AIM2在ApoE-/-小鼠中促进动脉粥样硬化斑块形成的影响进行了研究。构建AIM2过表达慢病毒载体和干扰慢病毒载体，通过静脉注入ApoE-/-小鼠体内。实验小鼠给予固定食物喂养（0.25%胆固醇和16%脂肪）12周。结果显示：AIM2炎症小体及GSDMD-N在动脉粥样硬化斑块中表达增高。抑制AIM2表达能够显著影响动脉粥样硬化斑块的形成。AIM2过表达能显著影响血管平滑肌细胞的死亡。AIM2可促进MMP2和ICAM-1的表达。因此，增加AIM2水平直接加速了ApoE-/-动脉粥样硬化的进展，AIM2不仅仅是动脉粥样硬化的标记物也是重要的参与者。.越来越多的证据显示，细胞焦亡作为一种caspase1依赖的细胞死亡形式，在动脉粥样硬化斑块发生和不稳定性中发挥着重要作用。AIM2对动脉粥样硬化斑块稳定性的作用尚未明确，本课题组通过AIM2慢病毒转染APOE-/-小鼠斑块易损模型来探究AIM2在斑块破裂中的作用及分子机制。结果发现OX-LDL能诱导血管平滑肌细胞发生焦亡。OX-LDL可通过激活NF-KB导致血管平滑肌细胞AIM2炎症小体表达升高。AIM2介导了氧化低密度诱导的血管平滑肌焦亡。AIM2能够促进MMP2表达，进而促进血管平滑肌细胞迁移。因此，AIM2直接参与了ApoE-/-动脉粥样硬化发生发展过程中平滑肌细胞的焦亡和迁移，AIM2不仅仅是动脉粥样硬化的标记物也是重要的参与者。.AIM2在多种组织及细胞中分布广泛，并在调节细胞焦亡、炎症反应及增殖迁移过程中发挥着重要作用。电镜结果表明糖尿病状态下心肌细胞可呈现类似于焦亡细胞的形态特征，且在高糖处理的H9c2心肌细胞中，AIM2炎症小体表达升高。通过AIM2干扰慢病毒进行体内干预，我们发现糖尿病大鼠的心肌结构异常及功能紊乱得到显著改善。细胞水平的研究证实高糖刺激可通过促进心肌细胞中ROS生成增多诱导AIM2过表达，进一步诱导caspase-1/GSDMD-N介导的细胞焦亡。而心肌细胞中AIM2基因沉默可缓解GSDMD-N介导的细胞焦亡。