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

本研究的目的是评价表面含有仙台病毒包膜糖蛋白的融合脂质体(FLS)对呼吸道粘膜大分子转运的有效性和特性。鼻腔给药后，FLS和含有FITC-葡聚糖(FD)的单层脂质体(LiPS)作为模型大分子化合物，任何时候都不能在血浆中检测到FD。FLS鼻腔和气管给药后FD的恢复明显低于FD液或Lips。时程分析表明，FLS在鼻腔和气管分别在15min和30min内可检测到与粘膜的快速融合，并在30min和60min达到最大值。FD的相对分子质量不影响FLS与粘膜的结合和融合。通过激光共聚焦扫描荧光显微镜观察，摄取研究显示上皮细胞内有荧光。联合应用DTT和唾液酸酶可减少FLS与粘膜的结合和融合。这些结果表明，FLS可能在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的融合量相近。蛋白水解酶抑制剂如唾液酸酶抑制剂、类型素抑制剂和Chamostat可增加FLS与粘膜的结合量和融合量，而杆菌肽不能增加FLS的结合量。根据这些结果，FLS可能有助于将大分子定位于鼻黏膜。

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.