pH/MMP-2双响应智能纳米探针用于肺癌免疫治疗的研究

免疫检查点抑制剂（ICIs）在肺癌治疗中展示出巨大发展潜力，但存在T细胞依赖、脱靶毒性作用等局限性。针对ICIs治疗缺陷，本项目拟构建基于siPD-L1、aPD-L1和P2RX7激活剂（P2RX7a）的联合免疫治疗纳米探针。先将siPD-L1和显像剂AuNP@G负载于探针核心，aPD-L1和P2RX7a分别通过MMP-2可切割肽和pH敏感材料mPEG-CDM连接探针表面，适配体1和5靶向性修饰探针。当探针靶向输送至肺癌组织，在肿瘤pH6.5弱酸性环境中PEG脱落释放P2X7a，促进效应T细胞聚集；肿瘤过表达的MMP-2切断连接肽链释放aPD-L1，P2RX7a和aPD-L1在细胞外发挥协同免疫治疗作用；siPD-L1及AuNP@G被癌细胞吞噬，siPD-L1触发癌细胞程序性凋亡。最终实现肺癌细胞靶向输送、pH/MMP-2双响应智能控释、细胞内外多层次协同免疫治疗及实时监测等功能，提高疗效。

Immune Checkpoint Inhibitors (ICIs) has shown great potential in the treatment of lung cancer, but it has limitations such as T cell dependence and off-target toxicity. Aiming at the deficiency of ICIs, this project plans to build up a combined immunotherapy nanoprobe based on siPD-L1, aPD-L1 and P2RX7 activator (P2RX7a). Firstly, SiPD-L1 and imaging agent AuNP@G were loaded on the core of the probe, aPD-L1 and P2RX7a were connected to the surface of the nanoprobe by MMP-2 cleavable peptide and pH sensitive material mPEG-CDM, respectively. The nanoprobe was targeted modified with aptamer 1 and 5. When the nanoprobes are delivered to lung cancer tissue, PEG exfoliates and releases P2X7a in the weak acidic environment of pH6.5, which promoted the aggregation of effector T cells; MMP-2, which is highly expressed in tumor tissue, cuts off the peptide chain and releases aPD-L1, P2RX7a and aPD-L1 exert synergistic immunotherapeutic effect at the extracellular level; siPD-L1 and AuNP@G are phagocytosed by lung cancer cells, programmed apoptosis of lung cancer cells are triggered by siPD-L1. Finally, lung cancer cells specific targeted drug delivery, pH/MMP-2 dual response intelligent controlled drug release, multi-level synergistic immunotherapy effect inside and outside lung cancer cells and real-time monitoring can be realized, providing an overall improvement in immunotherapy efficacy of lung cancer.