妊娠相关血浆蛋白-A促动脉粥样硬化斑块不稳定的机制研究

Unstable atherosclerotic plaque rupture is the important mechanism of acute coronary syndromes（ACS）,and inflammatory infiltration and degradation of extracellular matrix（ECM）play crucial roles in the development of unstable plaque. Pregnancy associated plasma protein-A(PAPP-A) accelerate the development of atherosclerotic plaques. However, the molecular mechanisms remains unclear. Our previous studies showed PAPP-A level in coronary circulation increased in the patients with ACS and expression in human peripherial blood monocytes is regulated by CRP and TNF-α, which indicated that PAPP-A is closely associated with inflammation. Foreign research showed PAPP-A might has the action of degradating ECM as a metal protease. Therefore, we hypothesized that PAPP-A play a role in development of unstable plaque by enhancing inflammatory infiltration and degradation of ECM. We will construct the mice model of atherosclerotic plaque and culture macrophage and vascular smooth myocytes. Based on the experiments in vivo and in vitro, we explore the relationship between PAPP-A and inflammatory cytokines or degradation of ECM by molecular biology methods，and investigate the development of vulnerable plaque after inhibition of PAPP-A gene expression by RNA interference techniques and mechanisms. Our study is of great significance on illustrating the mechanism of unstable plaque development，which will help to provide new target for prevention and treatment of ACS.

不稳定斑块破裂是急性冠脉综合征（ACS）的主要发病机制，其中炎症浸润、细胞外基质（ECM）降解是致斑块不稳定的重要触发因素。妊娠相关血浆蛋白-A(PAPP-A)可加剧动脉粥样硬化斑块的进展，但作用机制尚不清楚。前期研究我们发现ACS患者冠脉循环中存在PAPP-A高表达，CRP和TNF-α可调控PAPP-A表达，证实PAPP-A与炎症相关。国外研究推测PAPP-A作为金属蛋白酶，可能降解ECM。因此我们提出PAPP-A通过促进炎症浸润和/或ECM降解参与不稳定斑块形成。为证实这一假说，我们建立小鼠动脉粥样硬化斑块模型及体外细胞培养，采用分子生物学、基因沉默等技术，从整体-血管-细胞三个层次，探讨PAPP-A与不稳定斑块内炎症及ECM降解之间的相关性，PAPP-A基因沉默对斑块稳定性的影响及其作用机制。本课题将从新的视觉阐明不稳定斑块的发生机制，为ACS防治提供新的治疗靶点，具有重要科研价值。

不稳定斑块破裂是急性冠脉综合征（ACS）的主要发病机制，其中炎症浸润、细胞外基质（ECM）降解是致斑块不稳定的重要触发因素。妊娠相关血浆蛋白-A(PAPP-A)可加剧动脉粥样硬化斑块的进展，但作用机制尚不清楚。本课题从整体-血管-细胞三个层次，探讨了PAPP-A-IGF-I轴是否参与动脉粥样硬化斑块中巨噬细胞及主动脉血管平滑肌细胞（VSMCs）功能活化、炎性因子分泌及ECM降解，从而导致斑块不稳定。研究结果发现：（1）PAPP-A可促使RAW264.7细胞周期的S期发生阻滞，诱导其凋亡，并增加巨噬细胞吞噬脂质的能力。（2）重组PAPP-A呈剂量依赖性刺激RAW264.7细胞及VSMCs分泌胰岛素样生长因子（IGF-I）、巨噬细胞移动抑制因子（MIF）、单核细胞趋化因子-1（MCP-1）、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)等炎症因子，I型胶原和III型胶原水平增 加， I型/III型胶原比值降低，提示PAPP-A可促进巨噬细胞和VSMCs分泌炎症因子及细胞外基质降解增加。（3）重组PAPP-A刺激后呈剂量及时间依赖性促进RAW264.7细胞及VSMCs的IGF-I、MCP-1、MIF、TNF-α、IL-6蛋白和mRNA表达增加，抑制IGFBP-5表达，对IGF-IR表达无影响。（4）采用高脂饮食喂养ApoE 基因敲除小鼠的方法建立不稳定斑块模型，小鼠主动脉根部斑块内I型胶原面积减少，III型/I型比值增高，PAPP-A、IGF-I、MCP-1、MIF、TNF-α、IL-6蛋白及mRNA表达增加，IGFBP-5表达减少。PAPP-A蛋白表达与I型胶原面积和IGFBP-5表达呈负相关，与IGF-I、MCP-1、MIF、TNF-α、IL-6表达呈正相关。本课题将从新的视觉阐明不稳定斑块的发生机制，为ACS防治提供新的治疗靶点，具有重要科研价值。