脑神经元靶向纳米递药系统的构建及对阿尔茨海默病双靶点联合用药的研究

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease with few effective treatments. Currently, there are mainly three key problems exit in its therapy. Firstly, most drugs available now just aim at one target and provide symptomatic therapy, which could not cover the complex pathologic mechanisms of AD. Secondly, the blood-brain barrier (BBB) acts as a protective barrier for the central nerves system (CNS) and prevents the brain delivery of most drugs. Thirdly,most drugs are difficult to concentrate on the diseased region after passage through the BBB. drug distribution in normal brain tissues would not only decrease the amount of drugs at the lesion, but might cause serious CNS side effects. Considering these problems, "combination therapy" and "precise brain neuron delivery" are applied together in this project for AD therapy. For combination therapy, a novel β-sheet breaker peptide, H102 peptide, and a microtubule- stabilizing agent, NAP peptide, are chosen as therapeutic drugs for the two key hallmarks of AD, β-amyloid and tau protein, respectively. Moreover, precise drug delivery to the brain lesion is critical for AD therapy due to the complexity of brain and the susceptibility to damage of neurons. For this purpose, d-TGN (consensus peptide sequence "TGNYKALHPHNG"), a specific ligand of BBB, is chosen to enhance the brain penetration of the delivery system, while Tet1(consensus peptide sequence "HLNILSTLWKYP"), with high binding affinity to GTb1 trisialganglioside expressed on neuronal cells, is used as a brain neuron targeting moiety. Thus, H102 and NAP are respectively encapsulated into nanoparticles modified with both d-TGN and Tet1, constructing a brain neuron-targeted delivery system. This drug delivery system is supposed to increase the specific delivery of AD therapeutic drugs to the brain neuron lesion, exerting the combined effects of two drugs to enhance the curative effects. This project would be not only a beneficial exploration in the combination therapy of drugs targeting β-amyloid and tau protein for AD, but also an extensive research of brain targeted drug delivery.

阿尔茨海默病(AD)治疗难度大，目前药物治疗面临三大关键问题：①AD病理机制复杂，只针对单一靶点的药物疗效有限；②血脑屏障(BBB)对药物入脑的阻碍作用；③药物入脑后难以浓集于病变部位，不仅降低了对AD的治疗效果，也给正常脑组织带来了重大安全隐患。为此，本项目拟将"联合用药"与"脑神经元靶向"策略相结合，同时以AD重要的神经病理标志物-β-淀粉样蛋白和tau蛋白为治疗靶点，选择两个针对性多肽药物-β-片层阻断肽H102和微管蛋白稳定剂NAP，将其分别载于表面修饰有短肽d-TGN(靶向BBB)和Tet1(靶向神经元)的纳米粒中，构建载多肽的脑神经元靶向递释系统。通过双靶向功能基的介导，增加多肽药物的入脑递释和在病变神经元的浓集；通过联合用药发挥协同作用，增强对AD的治疗效果。本项目既是针对β-淀粉样蛋白和tau蛋白联合用药治疗AD的有益探索，又是脑靶向递药系统研究的拓展。

阿尔茨海默病 (Alzheimer’s disease, AD) 是最常见的中枢神经系统退行性疾病，迄今仍无有效药物可逆转病程。目前AD药物干预主要面临几个瓶颈问题：①AD病理机制复杂，各异常因素间常相互促进、相互诱导，例如：β-淀粉样蛋白(Aβ)和tau蛋白间存在毒性的协同作用：主要表现在Aβ能够促使tau蛋白异常磷酸化，而过度磷酸化的tau蛋白又可加剧Aβ对神经元的毒性作用。因此，仅针对单一靶点进行治疗，药效往往有限；②血脑屏障(BBB)对药物入脑的阻碍作用；③药物入脑后呈全脑分布，难以浓集于病变部位，进一步降低了治疗效果。因此，如何将药物精准递送至AD病变部位，并发挥多靶点治疗作用，成为AD治疗关注的一大重点。. 基于此，本项目将“联合用药”和“脑神经元靶向”策略相结合，以AD主要的神经病理标志物—Aβ和磷酸化tau蛋白为治疗靶点，选择两个针对性多肽药物—β-片层阻断肽H102和微管蛋白稳定剂NAP，将其分别载于表面修饰有短肽CGN (靶向BBB)和Tet1(靶向神经元)的纳米粒中，通过双靶功能基的介导，增加多肽药物的入脑递释和在病变神经元的浓集；通过联合用药发挥协同作用，旨增强对AD的治疗效果。. 具体内容为：以PEG-PLA为载体材料制备纳米粒，表面修饰CGN和Tet1 (经筛选Mal/CGN比为3:1，Mal/Tet1比为2:1)，构建靶向脑神经元的纳米递释系统(CT-NP)。研究发现，CT-NP具有强的BBB透过能力，其脑部荧光强度分别是NP和C-NP的3.42和2.01倍；入脑后，CT-NP与神经元有良好共定位，显示出优良的脑神经元靶向性。将其分别包载H102肽和NAP肽，细胞药效实验显示，当两种纳米粒以3:1、5:1分别给药或共载药比例为2:1、3:1时具有协同作用，其中联合用药比例为2:1，共载给药方式具有最强抑制Aβ毒性、降低p-tau的能力。体内给药后，也显示CT-NP/(H102:NAP=2:1)组能显著改善AD小鼠空间记忆障碍，且具有优良的清除Aβ斑块、抗炎和神经保护作用。治疗效果显著优于两种药物单独使用，证实具有协同增效作用。. 本项目为采用 “联合用药”策略治疗AD提供了实验资料和理论依据，拓宽了脑靶向递药系统在AD治疗中的应用，具有较高的科学价值和临床意义。