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

在本项目中，我们引入了反向靶向药物传递系统(RT-DDS)的新概念，它是DDS的反向版本，即药物载体将被靶细胞识别。为此，我们研制了能被抗原特异性免疫细胞识别的下一代脂质体--抗原偶联脂质体，并将其命名为反向靶向脂质体(RT-liposome)。通过这种脂质体，我们选择性地将药物输送到免疫细胞并破坏细胞，以达到根治过敏和免疫性疾病的目的。这项研究的结果表明，致敏的免疫细胞实际上相反地靶向于抗原偶联脂质体。为了验证RT-DDS的概念，我们选择卵白蛋白(OVA)作为模型抗原，并用OVA致敏的小鼠作为抗原敏感的变态反应模型。首先，我们利用卵清蛋白成功地制备了逆转录脂质体，并证明了卵清蛋白偶联脂质体在血清中的稳定性。接下来，我们观察到卵清蛋白偶联脂质体能够被免疫细胞识别。我们观察到，聚乙二醇化的卵清蛋白脂质体本身对卵清蛋白具有脱敏作用。虽然RT-脂质体在幼稚和OVA致敏小鼠体内的生物分布没有太大差异，但与对照脂质体相比，OVA偶联脂质体在脾中高度蓄积，这表明OVA偶联改变了免疫系统的识别。此外，还发现OVA偶联脂质体与B细胞共定位，并在脾生发中心蓄积的时间比对照脂质体要早得多。注射阿霉素包裹的卵清蛋白脂质体可抑制卵清蛋白预敏小鼠体内卵清蛋白特异性IgE的产生。使用阿霉素的RT-DDS可用于治疗IgE诱导的变态反应。在这项研究中，我们证明了这一概念的不可分割性。RT-DDS可能成为变态反应和自身免疫性疾病的一种新的治疗策略。

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.