集光疗/免疫激活/免疫检查点抑制于一体的纳米治疗体系抗转移性乳腺癌研究

It is of great importance to explore the new methods for damaging tumor cells and activating immune system effectively for the treatment of metastatic breast cancer. Although phototherapy can trigger immunogenic cell death (ICD), the application of this ICD induced by phototherapy is limited by weak immune response and complex immune suppressive problems. Firstly, the manganese (II) phosphate nanoparticles will be used for loading near-infrared (NIR) fluorescence imaging agent indocyanine green and immune checkpoint inhibitor JQ1. Moreover, poly (glutamic acid) will be modified on the surface of this nanoplatform to facilitate tumor targeting as well as adjuvant function, forming the therapeutic nanoplatform. When the nanoplatform transports through endosomes or lysosomes with low pH, it would degrade into manganese ions enabling nucler magnetic resonance imaging (MRI), and release ICG and JQ1 simultaneously. When the primary tumor was irradiated, the poly (glutamic acid) in the system will help the ICD to generate strong immunological responses. This effect would be combined with the inhibitions of both programmed cell death ligand 1 (PD-L1) and integrin associated protein CD47 by JQ1. Thus, the combined anticancer effects of immune activation and immune checkpoints inhibition will mobilize effector T cells and macrophages for eradication of residual tumors and metastases without phototherapy. We will investigate the anti-metastatic breast cancer effect and their mechanisms in vitro and in vivo with the help of MRI/NIR dual-mode imaging in details. This project would pay a way for metastatic breast cancer therapy with the combination strategy of phototherapy and immune regulation.

探索杀伤癌细胞并有效激活免疫系统的新策略对于转移性乳腺癌的治疗具有重要意义。光疗能够触发免疫原性细胞死亡（ICD），但是弱的免疫应答以及复杂的免疫抑制问题限制了光疗所触发ICD的应用。本项目拟以磷酸亚锰为载体，先装载近红外荧光光敏剂吲哚菁绿和免疫检查点小分子抑制剂-JQ1，再修饰具有肿瘤靶向和佐剂功能的聚谷氨酸，形成纳米治疗系统。经由低pH内涵体/溶酶体，载体降解为可用于核磁共振成像（MRI）的锰离子，并释放吲哚菁绿和JQ1。激光照射原发灶肿瘤，光疗效应触发ICD，并依赖体系中聚谷氨酸的佐剂功能，从而有效激活免疫效应，联合JQ1共抑制免疫检查点细胞程序性死亡配体（PD-L1）和整合素相关蛋白CD47表达，最终调动效应T细胞和巨噬细胞消除单纯光疗未能根除的原发性肿瘤和未能光疗的转移瘤。我们将研究该体系在MRI/近红外荧光示踪下抗乳腺癌的作用及机制，为利用光疗和免疫调节抗转移性乳腺癌奠定基础。

探索杀伤癌细胞并有效激活免疫系统的新方法对于转移性乳腺癌的治疗具有重要意义。光疗能够触发免疫原性细胞死亡，但是弱的免疫应答以及复杂的免疫抑制问题限制了光疗的应用。（1）开发了介孔MnCO3纳米粒，然后装载碳自由基引发剂AIPH，最后包裹混合JQ1的脂质层后，修饰可以识别肿瘤细胞的靶向多肽LyP-1，形成集碳自由基疗法和免疫调节于一体的肿瘤靶向纳米治疗系统。该系统依赖AIPH产生碳自由基杀伤肿瘤细胞并激活免疫效应，协同JQ1降低肿瘤细胞PD-L1和CD47的水平，综合发挥对转移性乳腺癌的高效抑制。（2）通过增加肿瘤细胞内的铁离子水平，增加细胞内活性氧水平进而杀伤肿瘤细胞是一种有前景的肿瘤治疗方式。采用热溶剂法制备了一种内部多孔的磷酸铁纳米粒，然后对其PEG修饰，得到水溶性磷酸铁纳米粒，最后制备了载阿霉素的磷酸铁纳米粒（FeP-PEG/DOX）并对其理化性质进行了表征。以4T1细胞为模型，研究了FeP-PEG/DOX能够增加细胞内的铁离子水平，促进活性氧的产生，协调化疗作用能够产生有效肿瘤杀伤作用。以4T1-荷瘤小鼠为模型，证实了磷酸铁纳米粒是一种优异的T2 磁共振造影剂。体内抗肿瘤实验结果证实，FeP-PEG/DOX不仅能够抑制原发灶肿瘤的生长，而且能够抑制乳腺癌肺转移。此外，针对纳米粒在肿瘤部位蓄积量不足的问题，项目还探索了增强纳米粒在肿瘤部位蓄积的方法。项目探索的集肿瘤治疗和免疫激活的纳米治疗系统，可望用于乳腺癌的安全高效治疗。