Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
Terumo Corp., Ltd., Ashigarakami-gun, Kanagawa 259-0151, Japan.
Biomaterials. 2014 Sep;35(28):8186-96. doi: 10.1016/j.biomaterials.2014.05.077. Epub 2014 Jun 23.
Cationic lipid-incorporated liposomes modified with pH-sensitive polymers were prepared by introducing 3, 5-didodecyloxybenzamidine as a cationic lipid to egg yolk phosphatidylcholine liposomes modified with 3-methylglutarylated hyperbranched poly(glycidol) (MGlu-HPG) as a pH-sensitive polymer. These liposomes were stable at neutral pH, but were destabilized below pH 6.0 because MGlu-HPG changed its characteristics from hydrophilic to hydrophobic in response to the pH decrease. Cationic lipid inclusion improved their pH sensitivity at weakly acidic pH and association of liposomes with murine dendritic cell (DC) lines. Cationic lipid-incorporated liposomes delivered entrapped ovalbumin (OVA) molecules not only to cytosol but also to endosome/lysosome. Treatment with cationic lipid-incorporated liposomes induced up-regulation of antigen presentation-involved molecules on DCs, the promotion of cytokine production, and antigen presentation via both major histocompatibility complex (MHC) class I and II molecules. Especially, antigen presentation via MHC class II was promoted by cationic lipid inclusion, which might correspond to efficient endosome/lysosome delivery of OVA. Subcutaneous administration of OVA-loaded cationic lipid-incorporated liposomes induced antigen-specific antibody production in serum and Th1-dominant immune responses in the spleen. Furthermore, administration of the cationic lipid-incorporated liposomes to mice bearing E.G7-OVA tumor more significantly reduced the tumor volume than liposomes without cationic lipids. Therefore, cationic lipid inclusion into pH-sensitive polymer-modified liposomes, which can achieve both efficient antigen intracellular delivery and activation of antigen presenting cell, is an effective approach to develop antigen carriers for efficient cancer immunotherapy.
采用 3,5-二正十二氧基苯甲脒作为阳离子脂质，将其引入到经 3-甲基戊二酰化超支化聚（缩水甘油）（MGlu-HPG）修饰的蛋黄磷脂脂质体中，制备了带正电荷的脂质体。这些脂质体在中性 pH 下稳定，但在 pH 值低于 6.0 时不稳定，因为 MGlu-HPG 在响应 pH 值降低时从亲水变为疏水。阳离子脂质的包含物提高了它们在弱酸性 pH 下的敏感性，并增强了与鼠树突状细胞（DC）系的脂质体的结合。阳离子脂质包封的脂质体不仅可以将包封的卵清蛋白（OVA）分子递送到细胞质中，还可以递送到内体/溶酶体中。用阳离子脂质包封的脂质体处理可诱导 DC 中抗原呈递相关分子的上调、细胞因子的产生以及通过主要组织相容性复合物（MHC）I 类和 II 类分子的抗原呈递。特别是，阳离子脂质的包含物促进了 MHC II 类分子的抗原呈递，这可能与 OVA 的有效内体/溶酶体递送有关。OVA 负载的阳离子脂质包封的脂质体的皮内给药可在血清中诱导抗原特异性抗体产生，并在脾脏中诱导 Th1 优势免疫应答。此外，与不含阳离子脂质的脂质体相比，向携带 E.G7-OVA 肿瘤的小鼠给药阳离子脂质包封的脂质体可更显著地减少肿瘤体积。因此，将阳离子脂质纳入 pH 敏感聚合物修饰的脂质体中，既可以实现有效的抗原细胞内递呈，又可以激活抗原提呈细胞，是开发用于有效癌症免疫治疗的抗原载体的有效方法。
