自身具有佐剂功能的仿生型球形核酸纳米疫苗的构建及其用于肿瘤免疫治疗的研究

Immunotherapy has emerged as a promising strategy for cancer treatment in recent years. However, it has proven to be especially challenging to induce efficient antigen-specific immune responses using one single immunotherapy approach. Therefore, it is highly desirable for cancer immunotherapy to develop novel immunotherapeutic means to boost powerful antigen-specific immune responses. With the development of nanotechnology, cancer immunotherapy using nanoparticle vaccines (nanovaccines) is an emerging area. Many research have demonstrated that co-administration of antigen and various combination of adjuvants could promote strong immunity against tumors and significantly improve vaccine efficacy. In the design of biomimetic co-delivery of antigens and combination adjuvants, we intend to form self-assembled lipid bilayer nanocapsules using PhL-S-S-CpG ODN amphiphilic molecules synthesized with phospholipids and CpG ODNs, embed adjuvant squalene in the lipid bilayer of the nanocapsules by hydrophobic interaction, and immobilize tumor antigens (Ag) on the CpG ODNs of the hydrophilic layer with the complementary CpG chain of Ag-S-S-CpG complementary oligonucleotide conjugate through the cross-linking between DNA complementary base pairs. The prepared biomimetic nanovaccine based on spherical nucleic acids could deliver antigens to immune cells, and the immune responses would be significantly enhanced by CpG ODNs and squalene. The nanovaccine would be an economical and efficient immunotherapeutic option with the ability for controlled release of antigens and adjuvants without incurring adverse side effects.

肿瘤免疫治疗已成为近年来临床上治疗恶性肿瘤的一项新策略，但是，目前单一的免疫治疗方法很难获得预期的疗效。因此，发展新的高效抗原特异性免疫治疗手段，仍然是目前肿瘤免疫治疗急需解决的难题。随着纳米科技的发展，纳米颗粒介导的肿瘤纳米疫苗已成为一个重要的研究领域。多项研究表明将抗原与多种佐剂联合应用可以大大提高疫苗的疗效。基于分子仿生和不同功能分子共递送的设计理念，我们提出以磷脂和CpG ODN组成的PhL-S-S-CpG ODN双亲性分子为自组装基元制备具有类细胞膜双分子层结构的纳米囊，通过疏水作用将佐剂角鲨烯镶嵌于纳米囊的脂质双分子层，通过DNA碱基互补配对作用将连有CpG互补链的肿瘤抗原固定于纳米囊的CpG ODN亲水层，从而在纳米尺度内构建集抗原和不同佐剂于一体兼具抗原递送和佐剂功能的还原响应性仿生型球形核酸纳米疫苗，为肿瘤治疗提供一种经济高效、副作用小、给药可控的免疫治疗手段。

发展新的高效抗原特异性免疫治疗手段，仍然是目前肿瘤免疫治疗急需解决的难题。随着纳米科技的发展，纳米颗粒介导的肿瘤纳米疫苗已成为一个重要的研究领域。多项研究表明将抗原与多种佐剂联合应用可以大大提高疫苗的疗效。基于分子仿生和不同功能分子共递送的设计理念，我们采用以磷脂和CpG ODN组成的PhL-S-S-CpG ODN双亲性分子作为自组装基元制备具有类细胞膜双分子层结构的纳米囊，通过疏水作用将佐剂角鲨烯镶嵌于纳米囊的脂质双分子层，通过DNA碱基互补配对作用将连有CpG互补链的肿瘤抗原固定于纳米囊的CpG ODN亲水层，从而在纳米尺度内构建集抗原和不同佐剂于一体兼具抗原递送和佐剂功能的还原响应性仿生型球形核酸纳米疫苗。该纳米疫苗粒径为192.40±0.66 nm，Zeta电位为-31.20±2.43 mV，且具有较好的稳定性及还原响应性。该纳米疫苗NaVs依靠表层的球形寡核苷酸外壳与抗原提呈细胞表面的受体结合，可通过三条不同的内吞途径进入抗原提呈细胞，激活机体产生抗肿瘤细胞免疫反应和抗体免疫反应，显著延长荷瘤小鼠生存期（56天VS22天）。纳米疫苗体系中，加入其它佐剂如角鲨烯或QS21均可显著增强抗肿瘤的效果，实现免疫效应的协同作用。