基于脂包被中空介孔纳米粒的混合多肽癌症疫苗研究

Cancer immunotherapy is mainly focused on manipulating patient's own immune system to recognize and destroy cancer cells. Nanoimmunotherapy may be one of the promising strategies due to its dose-sparing, prolonged antigen-presentation, and elicited much stronger T-cell responses features. Our previous research mainly focused on single epitope and toll like receptor co-delivery nanoparticles, however, the protective immunity developed in a mouse model can't completely result in tumor rejection. This may be attributed to that tumor cells could down regulate the antigen expression at their surface that makes them invisible to CTLs. In this project, we will co-deliver multi-MHC I/II peptide and TLR 4 agonist to DCs to develop peptide-cocktail effect for making tumor cells more difficult to escape from the surveillance of the immune system and CD4+ T-helper (Th) lymphocytes to promote CD8 CTL response and thus improve anticancer efficiency. To increase the efficiency of antigen delivery to DCs and the peptide-cocktail, novel DCs targeted anti-DEC205 conjugated lipid-enveloped mesoporous nanoparticles will be constructed. The system may realize high targeting efficiency through mobile targeting with nanoporous suported lipid membrane. This cancer vaccine system will provide a novel antigen delivery system and a mechanism of inhibiting tumor immune escape.

肿瘤免疫疗法是新兴的肿瘤生物学治疗方法，可激活患者自身免疫系统，识别和杀死肿瘤细胞，抑制肿瘤转移，预防复发。结合纳米技术，可实现靶向持久递送抗原给树突状细胞DCs，诱导强烈的肿瘤特异性T细胞反应,杀死肿瘤细胞。前期研究发现，单一抗原多肽纳米粒虽可诱导T细胞免疫反应，但不能彻底清除肿瘤，这可能与肿瘤对单一抗原的免疫耐受和免疫逃逸导致的抗原调变有关，只有通过混合多肽才可诱导多种复合体特异性T细胞免疫反应，以引起多基因对肿瘤的免疫监视，并减少免疫耐受风险。针对不同亲、疏水性多肽难以共包封的问题，本项目拟构建抗体偶联的脂包被中空介孔纳米粒，实现靶向DCs的多组分共输送，并通过脂膜表面的流动性实现偶联抗体的高效移动靶向；并以黑色素瘤为模型，研究结合多组分MHC I、II类抗原表位多肽和佐剂的协同抗肿瘤作用，筛选混合多肽最优配伍。为发展癌症疫苗纳米递送系统和筛选抗原多肽等研究提供理论基础和研究新思路。

持久、高效递送混合抗原表位多肽给树突状细胞，并诱导多种复合体特异性T细胞免疫反应，可实现多基因对肿瘤的免疫监视并减少免疫耐受风险。然而不同抗原多肽亲、疏水性差异较大，如何实现其高效共装载是目前急需解决的一个重要科学问题。本项目研究制备了具有单分散特性、稳定性好的中空介孔二氧化硅纳米粒（HMSN），相关纳米粒可实现粒径（67.3±8.9至468.1±10.5 nm）和介孔孔径（3.1至4.8 nm）可控，壁厚（12.9±1.6至48.6±2.3 nm）可调；通过筛选磷脂组分比例，制备了脂包被中空介孔硅纳米粒（HMSN@SLB），并实现了对亲水性多肽HGP100和疏水性多肽TRP2的共包封，包封率分别为27.5%和88.8%。该脂包被结构纳米粒不仅提高了混合多肽的包封率，延缓多肽在生物体内的释放；也进一步增强了HMSN纳米粒的稳定性，促进DC细胞的摄取效率。该项目构建的脂包被中空介孔硅纳米载药体系成功实现了对亲、疏水抗原多肽的混合共包封和靶细胞的高效摄取，为DC细胞高效呈递抗原，诱导抗肿瘤特异性免疫反应打下了坚实的基础，为发展癌症疫苗纳米递送系统提供了理论基础和研究新思路。项目均按计划完成，研究成果已先期发表“2013年中国药物制剂大会”会议摘要1篇，在国际学术期刊Nanomedicine、Nanoscale、Biomacromolecule、International Journal of Nanomedicine、Expert Opinion on Drug Delivery、European Journal of Pharmaceutical Sciences等发表该基金资助文章，多次参加国际国内学术会议并做分组报告。