肿瘤坏死因子α及其可溶性II型受体调控主动脉夹层血管重构的机制研究

Aortic dissection was one of the most devastating cardiovascular diseases. Many patients died of aortic rupture before treatment, even before making a definite diagnosis. Although endovascular therapy had minimally invasive advantage, its overall in-hospital mortality was still up to 17.6%. Previous studies revealed that about 15% patients had to undergo another intervention due to the life-threatening complications. The mechanism of vascular remodeling and reintervention of aortic dissection needed to be elucidated. The preliminary results of my master's and doctoral project indicated that tumor necrosis factor-α (TNF-α) and its soluble receptor II (TNF-sRII) played a vital role in vascular remodeling. However, the exact mechanism was still poorly understood. The present project was composed of two parts. First, the concentration of TNF-α and TNF-sRII in aortic dissection patients and healthy volunteers was measured by enzyme-linked immunosorbent assay. The potential relationship between them and influence factors were determined according to the clinical information. Second, the animal model of aortic dissection was established in wild-type mice and TNF-α gene knock-out mice. The main observations were the mortality of mice, the incidence of aortic dissection, the external diameter and maximum diameter of aorta, the collagen and elastic fibers difference, and the quantitative change of endothelial cells and smooth muscle cells, the concentration and RNA level of downstream cytokines, signal pathway, etc. Moreover, the biomechanical tests were performed to further elucidate the effect of TNF-α on vascular remodeling. This project would provide experimental evidence for uncovering the mechanism of vascular remodeling in aortic dissection, and help to offer a novel and attractive target of reintervention.

许多主动脉夹层患者在开始治疗前甚至在明确诊断前即因夹层破裂而死亡。尽管腔内隔绝术微创优势明显，但其总体在院死亡率仍高达17.6%。前期发现约15%的患者因并发症需要再次干预，主动脉夹层血管重构和再干预机制亟待阐明。本人的硕博士课题发现肿瘤坏死因子α（TNF-α）及其可溶性II型受体（TNF-sRII）在主动脉夹层血管重构中发挥了重要作用，但具体机制不清。本项目拟（1）检测夹层患者和健康对照者血清TNF-α及TNF-sRII含量，探讨两者含量关系及影响因素；（2）用野生型和TNF-α基因敲除小鼠建立主动脉夹层模型，比较小鼠死亡率、夹层发生率、主动脉外径和最大径、主动脉胶原和弹力纤维含量、管壁细胞数量、下游炎症因子及RNA含量、信号通路等，并对主动脉行生物力学检测，明确TNF-α对血管重构的影响。本项目是课题研究的进一步深入，能为阐明主动脉夹层血管重构机制、寻找再干预的可干预靶点提供实验支撑。

主动脉夹层起病急骤，病情凶险，可在短期内造成患者猝死或重要脏器功能不全，其血管重构机制亟待阐明。本人的硕博士课题发现肿瘤坏死因子α（TNF-α）及其可溶性II型受体在主动脉夹层血管重构中发挥了重要作用，但具体机制不清。本项目研究内容分为两部分：（1）临床样本研究：检测夹层患者和健康对照者血清TNF-α及TNF-sRII含量，并结合临床信息探讨TNF-α含量的影响因素；（2）实验动物研究：用野生型和TNF-α基因敲除小鼠建立主动脉夹层模型，比较小鼠死亡率、夹层发生率、主动脉外径和最大径、主动脉胶原和弹力纤维含量、下游炎症因子含量、信号通路等，并对主动脉行生物力学检测，明确TNF-α对血管重构的影响。临床样本研究发现主动脉夹层患者血清中不仅TNF-α和TNF-sRII含量明显高于健康对照者，下游炎症因子如IL-1β、IL-6、IL-18、MMP-9、MCP-1含量也高于健康对照者。结合患者临床信息分析发现C反应蛋白和血沉含量是TNF-α的影响因素。实验动物研究发现造模组小鼠血清中IL-6、MMP-9、MCP-1、TNF-α含量明显高于非造模组，外加TNF-α干预后提高了上述炎症因子的含量，TNF-sRII含量呈现反向趋势。进一步分析发现，造模组小鼠主动脉外径、最大径、中膜厚度明显大于非造模组，外加TNF-α干预后小鼠死亡率、夹层发生率增高，管壁IL-6、MMP-9、MCP-1含量明显升高，主动脉胶原含量明显降低，弹力纤维更易于断裂。细胞免疫荧光证实TNF-α是巨噬细胞来源的，外加TNF-α干预后，IL-6、MMP-9、MCP-1的RNA含量明显增高。WB发现上述变化可能是通过PI3K-AKT-mTOR通路实现的。此项目进一步揭示了TNF-α及TNF-sRII在主动脉夹层血管重构中的重要作用及可干预靶点，为将来研发载药移植物正性调控血管重构，改善主动脉夹层预后提供了实验数据。