Development of Radical Treatment Modality for Curing Allergies and Immune Diseases by a Novel Consept, RTDDS

本课题提出了一种新的概念“反向靶向给药系统”，它是DDS的反向版本，即药物载体将被靶细胞识别。为此，我们研制了一种新一代的能够被抗原特异性免疫细胞识别的脂质体--抗原偶联脂质体，并将其命名为“反向靶向脂质体”。通过这种脂质体，我们选择性地将药物递送到免疫细胞并破坏细胞，以达到过敏和免疫性疾病的根治方式的目的。在这项研究中获得的结果表明，致敏的免疫细胞实际上反向靶向抗原偶联脂质体。为了验证RT-DDS的概念，我们选择卵清蛋白（OVA）作为模型抗原，并使用OVA致敏小鼠作为抗原敏感的变态反应模型。首先，我们成功地用卵清蛋白制备了RT-脂质体，并证明了卵清蛋白偶联的脂质体在血清中是稳定的。我们接下来观察到OVA偶联的脂质体被免疫细胞识别。我们观察到PEG化的OVA-脂质体本身诱导对OVA的脱敏。虽然RT-脂质体在未处理或OVA致敏小鼠中的生物分布没有太大差异，但与对照脂质体相比，OVA偶联的脂质体在脾脏中高度累积，表明OVA缀合改变了免疫系统的识别。此外，还显示OVA偶联的脂质体与B细胞共定位，并且比对照脂质体更早地在脾脏的生发中心累积。阿霉素脂质体可抑制致敏小鼠体内特异性IgE的产生。阿霉素RT-DDS可作为治疗IgE过敏的药物。在这项研究中，我们证明了概念的不可重解性。RT-DDS有望成为治疗变态反应和自身免疫性疾病的新策略。

In this project, we introduce a novel concept of "Reverse Targeting Drug Delivery System, RT-DDS", which is reverse version of DDS, namely, drug carriers would be recognized by target cells. For this purpose, we developed antigen-coupled liposome as one of next-generation liposomes which would be recognized by the antigen-specific immume cells, and named it as" Reverse Targeting Liposome (RT-liposome)". By this liposome, we selectively deliver drugs to the immume cells and damage the cells for the purpose of radical treatment modality of allergies and immune diseases. The results obtained in this study indicated that sensitized immune cells actually targeted inversely to antigen-coupled liposomes. In order to prove the concept of RT-DDS, we selected ovalbumin (OVA) as a model antigen and used OVA-sensitized mouse as an antigen sensitive allergy model. At first, we succeeded to prepare RT-liposomes using OVA, and it was shown that OVA-coupled liposomes were stable in serum. We next observed that OVA-coupled liposomes were recognized by immune cells. We observed that PEGylated OVA-liposome itself induces desensitization against OVA. Although the biodistribution of RT-liposomes in naive or OVA-sensitized mice was not much different, OVA-coupled liposomes highly accumulated in spleen compared to control liposomes, suggesting OVA-conjugation alters the recognition by immune systems. Moreover, it was also shown that OVA-coupled liposomes were co-localized with B cells and accumulated in germinal centers in spleen much earlier than control liposomes. The injection of adriamycin-encapsulated OVA-liposome supressed the production of OVA-specific IgE in OVA-presensitized mice. RT-DDS using adriamycin could be a therapy for IgE induced-allergy. In this study, we demonstrated irrefragability of the concept. RT-DDS could be a new therapeutic strategy for allergy and autoimmune diseases.