Drug Delivery to Respiratory Mucosa using Fusogenic Liposomes and its Molecular Design.

本研究的目的是评价具有仙台病毒包膜糖蛋白表面的融合性脂质体（FLs）在向呼吸道粘膜递送大分子中的作用和特性。经鼻给药FLs和以fitc -葡聚糖（FD）为模型大分子化合物的单层脂质体（Lips）后，任何时候血浆中均未检测到FD。鼻部和气管给药后FD的恢复明显低于FD溶液或唇部。时间过程分析表明，FLs与粘膜的快速融合在鼻内15min，气管内30min可检测到，在鼻内30min，气管内60min达到最大值。FD的分子量不影响fl与粘膜的结合和融合。通过共聚焦激光扫描荧光显微镜评估，摄取研究显示上皮细胞的细胞内荧光。DTT联合唾液酸酶预处理可降低fl与粘膜的结合和融合。这些结果表明，荧光蛋白可能在与唾液酸的结合和融合过程中识别唾液酸。阳离子FLs与鼻黏膜的结合量大于阴离子FLs，但阳离子FLs与阴离子FLs的融合量基本相同。蛋白酶抑制剂如唾液酸酶抑制剂、抑型酶抑制剂和chamostat可增加fl与粘膜的结合和融合量，而杆菌肽则无此作用。从这些结果来看，fl可能有助于将大分子定位到鼻黏膜。

The objective of the present investigation was to evaluate the usefulness and characterization of fusogenic liposomes (FLs), which have envelope glycoproteins of the Sendai virus on their surface, on a delivery of macromolecules to respiratory mucosa.After nasal administration of FLs and unilaminar liposomes (Lips) containing FITC-dextran (FD) as a model macromolecular compound, FD was not detected in plasma at any times. The recovery of FD after administration of Fls to nose and trachea was significantly lower than that of FD solution or Lips. Time course analysis showed that the rapid fusion to the mucosa in FLs was detectable within 15 min in nose and 30 min in trachea, and reached a maximum value at 30 min in nose and 60 min in trachea. The molecular weights of FD did not affect the binding and fusion of FLs to the mucosa. As evaluated by confocal laser scanning fluorescence microscopy, uptake studies revealed intracellular fluorescence in the epithelial cells. The binding and fusion of FLs to the mucosa were decreased with the coadministration of DTT and pretreatment of sialidase. These results suggested that FLs may recognize sialic acid in the process of the binding and fusion. The binding amount of cationic FLs to nasal mucosa was larger than of anionic FLs, but the fusion amount was almost same between cationic and anionic FLs. Protease inhibitors, such as sialidase inhibitor, typsin inhibitor and chamostat, increased the binding and fusion amount of FLs to the mucosa, but bacitracin did not. From these results, FLs may be useful in localizing macromolecules to nasal mucosa.