title: Functional characterization of an endosome-disruptive peptide and its application in cytosolic delivery of immunoliposome-entrapped proteins.
abstract: Antibody-directed liposomes (immunoliposomes) are frequently used for targeted drug delivery. However, delivery of large biotherapeutic molecules (i.e. peptides, proteins, or nucleic acids) with immunoliposomes is often hampered by an inefficient cytosolic release of entrapped macromolecules after target cell binding and subsequent endocytosis of immunoliposomes. To enhance cytosolic drug delivery from immunoliposomes present inside endosomes, a pH-dependent fusogenic peptide (diINF-7) resembling the NH(2)-terminal domain of influenza virus hemagglutinin HA-2 subunit was used. Functional characterization of this dimeric peptide showed its ability to induce fusion between liposome membranes and leakage of liposome-entrapped compounds when exposed to low pH. In a second series of experiments, diINF-7 peptides were encapsulated in immunoliposomes to enhance the endosomal escape of diphtheria toxin A chain (DTA), which inhibits protein synthesis when delivered into the cytosol of target cells. Immunoliposomes targeted to the internalizing epidermal growth factor receptor on the surface of ovarian carcinoma cells (OVCAR-3) and containing encapsulated DTA did not show any cytotoxicity toward OVCAR-3 cells. Cytotoxicity was only observed when diINF-7 peptides and DTA were co-encapsulated in the immunoliposomes. Thus, diINF-7 peptides entrapped inside liposomes can greatly enhance cytosolic delivery of liposomal macromolecules by pH-dependent destabilization of endosomal membranes after cellular uptake of liposomes.
authors.affiliation: Department of Pharmaceutics, Utrecht University, P.O. Box 80 082, Utrecht 3508 TB, The Netherlands.
authors.forename: Enrico
authors.initials: E
authors.lastname: Mastrobattista
authors.forename: Gerben A
authors.initials: GA
authors.lastname: Koning
authors.forename: Louis
authors.initials: L
authors.lastname: van Bloois
authors.forename: Ana C S
authors.initials: AC
authors.lastname: Filipe
authors.forename: Wim
authors.initials: W
authors.lastname: Jiskoot
authors.forename: Gert
authors.initials: G
authors.lastname: Storm
mesh_terms: D002942:Circular Dichroism; D003600:Cytosol / Q000378:metabolism*; D004167:Diphtheria Toxin / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D005434:Flow Cytometry; D006389:Hemagglutinins, Viral / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism*; D018613:Microscopy, Confocal; D010452:Peptide Biosynthesis; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D004167:Diphtheria Toxin; D006389:Hemagglutinins, Viral; D008055:Lipids; D008081:Liposomes; D010446:Peptide Fragments; D010455:Peptides; C029795:diphtheria toxin fragment A; C452559:hemagglutinin HA-2 fusogenic peptide, Influenza virus