cytoplasmic fungal lipases release fungicides from ultra-deformable vesicular drug carriers细胞质真菌脂酶释放杀菌剂从ultra-deformable疱疹药物载体.pdfVIP

Cytoplasmic Fungal Lipases Release Fungicides from Ultra-Deformable Vesicular Drug Carriers Gero Steinberg* Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom Abstract The TransfersomeH is a lipid vesicle that contains membrane softeners, such as Tween 80, to make it ultra-deformable. This feature makes the TransfersomeH an efficient carrier for delivery of therapeutic drugs across the skin barrier. It was reported that TDT 067 (a topical formulation of 15 mg/ml terbinafine in TransfersomeH vesicles) has a much more potent antifungal activity in vitro compared with conventional terbinafine, which is a water-insoluble fungicide. Here we use ultra-structural studies and live imaging in a model fungus to describe the underlying mode of action. We show that terbinafine causes local collapse of the fungal endoplasmic reticulum, which was more efficient when terbinafine was delivered in TransfersomeH vesicles (TFVs). When applied in liquid culture, fluorescently labeled TFVs rapidly entered the fungal cells (T1/2,2 min). Entry was F-actin- and ATP-independent, indicating that it is a passive process. Ultra-structural studies showed that passage through the cell wall involves significant deformation of the vesicles, and depends on a high concentration of the surfactant Tween 80 in their membrane. Surprisingly, the TFVs collapsed into lipid droplets after entry into the cell and the terbinafine was released from their interior. With time, the lipid bodies were metabolized in an ATP-dependent fashion, suggesting that cytosolic lipases attack and degrade intruding TFVs. Indeed, the specific monoacylglycerol lipase inhibitor URB602 prevented TransfersomeH degradation and neutralized the cytotoxic effect of T