酪氨酸激酶受体B对内皮通透性的影响及其在动脉粥样硬化发生发展中的作用研究

Atherosclerosis is a pathological basis of cardiovascular diseases such as coronary heart disease, which is the leading cause of death globally.Enhanced vascular permeability is an early alteration in arterial function during the formation of atherosclerotic lesions. Increased permeability of the endothelium is believed to allow entry of lipoproteins into the vessel wall. Once present, lipoproteins become oxidized and exhibit chemotactic and proinflammatory properties, thus leading to monocyte accumulation, foam cell formation, and lesion formation. Mechanism of regulating endothelial permeability is unknown..Tyrosine kinase receptor B (TrkB) is a high-affinity receptor for brain-derived neurotrophic factor (BDNF). The BDNF-TrkB pathway has critical roles in the survival, growth, maintenance, and death of central and peripheral neurons. The pathway is also expressed in endothelial cells. However, its role in pathological development of atherosclerosis is unclear.We reported the association of the pathway and occurrence and prognosis of Coronary Heart disease. In present study, with small interfering RNA and lentivirus-TrkB, we will study effect of TrkB on endothelial permeability in vitro and in vivo; study role of TrkB in TNF-α-induced endothelial hyperpermeability; study effect of TrkB on lipid and macrophage content in lesions in ApoE-/-mice maintained on highfat diet. We attempt to find a novel regulator and a novel pathway of endothelial permeability, and a novel target for prevention and treatment of atherosclerosis. Considering that TrkB located on chromosome 9p21 is a susceptibility region for coronary heart disease, this study will contribute to uncovering the mechanistic link between chromosome 9p21 and coronary heart disease.

动脉粥样硬化（AS）是冠心病等心脑血管病的主要病理基础，已严重危害人类健康。近年研究发现脑源性神经营养因子（BDNF）- - 酪氨酸激酶受体B（TrkB）通路在血管内皮细胞中表达，但其是否参与AS的病理过程尚未阐明。我们前期研究发现该通路涉及冠心病的发病及预后，为进一步研究其机制，本项目拟在体外培养的人主动脉内皮细胞和ApoE-/-小鼠体内，通过基因沉默和过表达TrkB，研究TrkB对血管内皮通透性的影响及机制；体外研究TrkB在炎性诱导的内皮高通透性中的作用及机制；进一步通过高脂喂养ApoE-/-小鼠构建小鼠AS模型，体内研究TrkB是否通过影响内皮通透性进而影响AS的发生发展。本研究旨在揭示TrkB对内皮通透性的调节作用和分子机制，为AS的防治开辟新思路。TrkB基因位于冠心病的易感区-染色体9P21区，因此本项目的预期结果有助于部分解释染色体9P21区与冠心病相关的分子基础。

寻找调控动脉粥样硬化发生发展的关键调控因子，并阐明其分子机理对于心血管病的防治和发现新的药物靶点具有重要的意义。我们及其他学者的前期研究结果提示脑源性神经营养因子（BDNF）及其酪氨酸激酶受体B（TrkB）可能在动脉粥样硬化的病理发展中发挥重要作用。在此背景下，本项目采用病例-对照研究和荧光素酶报告基因分析，首先检测了TrkB基因多态与冠心病的相关性，发现TrkB -69C>G基因多态和冠心病相关，TrkB -69C纯合子对应降低的TrkB表达和升高的冠心病风险。接下来的机制分析，发现TrkB主要表达在人及ApoE敲基因小鼠早期斑块的内皮层，TrkB信号通过促进Ets1介导的内皮钙粘蛋白合成保护内皮完整防止内皮泄漏。为研究TrkB在动脉粥样硬化发生发展中的关键作用，我们利用ApoE敲基因小鼠通过尾静脉注射AAV9病毒载体调控内皮TrkB的表达，发现TrkB能保护内皮防止脂质沉积巨噬细胞浸润以及早期动脉粥样硬化斑块的发生发展。本项目首次揭示了内皮TrkB在冠心病的发病过程中发挥以前未知的保护作用及其分子机理，为将BDNF-TrkB开发成为治疗动脉粥样硬化的新的药物或靶点提供了理论依据。