靶向肠道上皮细胞顶侧OCTN2转运体口服高效纳米粒的构建及其对OCTN2活性调控的研究

Currently, there are few available targets for active targeting nanoparticles. However, the body has a lot of transporters in determining the drug disposition's fate, such as novel organic cation transporter 2(OCTN2)，which is the main absorption carrier of L-carnitine. Transporter-mediated targeting nanoparticles are still at the initial stage and need to be studied. In order to increase the target types of nanoparticles and to elucidate the target difference between transporter and receptor, L-carnitine derivatives modified nanoparticles are developed to target OCTN2 transporter on the apical side of enterocytes. When encapsulating and solubilizing insoluble drug paclitaxel, active targeting nanoparticles also have bioadhesion, membrane permeation and reduce first-pass effect. Physicochemical, biological, pharmacokinetic and pharmacodynamic propeties of OCTN2 targeting nanoparticles are studied from the cell level, the organization level and the whole animal level. And then the quantitative relationships between nanoparticle structure and cellular binding/uptake and memrbane permeability, are estabilished to elucidate the key pharmaceutical mechanism of enhanced oral absorption of nanoparticles. Sepcial emphasis is put on studying regulation mechanism of OCTN2 activity from protein and gene level, endocytosis pathway of nanoparticles and transporting charactersitic of transporter, which would provide support for the research and development of the transporter-mediated targeting nanoparticles.

目前可供主动靶向纳米粒选择的靶点种类较少，而机体内存在着许多决定药物体内动态的药物转运体，例如新型有机阳离子转运体2(OCTN2)是L-肉毒碱吸收的主要载体。转运体介导靶向纳米粒的研究现在仍处于探索初期，尚待深入研究。为了丰富纳米粒的靶点选择范围和解析转运体与受体作为靶点的差别，本项目以肠道上皮细胞顶侧OCTN2为靶点，构建系列L-肉毒碱衍生物修饰的主动靶向纳米粒。在包裹增溶难溶性药物紫杉醇的同时，靶向纳米粒还具有与肠细胞的高度亲和性和内吞力，提高膜转运，降低首过效应等优势。本研究从细胞、组织和动物水平对靶向纳米粒进行制剂学、生物学、药动学和药效学评价，建立纳米结构/组成与其细胞结合/摄取和膜渗透性的定量关系，解析靶向纳米粒高吸收性的关键制剂学性质，重点从蛋白和基因水平、纳米粒内化机制和转运体的膜转运特征等多角度解析对OCTN2的调控机制，为后续转运体－纳米粒体系的研究提供理论和技术支撑。

目前可供主动靶向纳米粒选择的靶点种类较少，而机体内存在着许多决定药物体内动态的药物转运体，例如新型有机阳离子转运体2(OCTN2)是L-肉毒碱吸收的主要载体。转运体介导靶向纳米粒的研究现在仍处于探索初期，尚待深入研究。为了丰富纳米粒的靶点选择范围和解析转运体与受体作为靶点的差别，本项目以肠道上皮细胞顶侧OCTN2为靶点，构建系列L-肉毒碱衍生物修饰的主动靶向纳米粒，对其理化性质进行了表征；考察L-肉毒碱修饰纳米粒的结构设计（配体密度和连接臂长度）与其靶向效率之间的量-效关系，解析L-肉毒碱修饰的纳米粒靶向OCTN2的摄取机制，并从蛋白和基因水平考察基于OCTN2靶向的纳米粒对OCTN2的调控，指导纳米粒的合理设计；体内药动学结果显示L-肉毒碱修饰的纳米粒可以显著提高所包载紫杉醇的口服生物利用度（3.22倍），说明OCTN2靶向纳米粒具有应用于口服药物递送的潜力；进一步研究发现L-肉毒碱修饰的纳米粒可以靶向结肠癌细胞高表达的OCTN2和ATB0,+两个转运体，从而实现结肠癌治疗药物的精准递送；L-肉毒碱修饰、含有PEG连接臂的纳米粒在体内口服方面表现不佳，但在注射之后，可以有效靶向血脑屏障表达的OCTN2转运体增加脑部药物递送，进而与脑胶质瘤高表达的OCTN2相互作用，实现脑胶质瘤药物的靶向递送。截止到目前，本课题已发表论文12篇，其中SCI11篇，申请专利两项，超过了我们初始定的目标。

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