Cationic liposomes loaded with a synthetic long peptide and poly(I:C): a defined adjuvanted vaccine for induction of antigen-specific T cell cytotoxicity.
For effective cancer immunotherapy by vaccination, co-delivery of tumour antigens and adjuvants to dendritic cells and subsequent activation of antigen-specific cytotoxic T cells (CTLs) is crucial. In this study, a synthetic long peptide (SLP) harbouring the model CTL epitope SIINFEKL was encapsulated with the TLR3 ligand poly(inosinic-polycytidylic acid) (poly(I:C)) in cationic liposomes consisting of DOTAP and DOPC. The obtained particles were down-sized to about 140 nm (measured by dynamic light scattering) and had a positive zeta-potential of about 26 mV (according to laser Doppler electrophoresis). SLP loading efficiency was about 40% as determined by HPLC. Poly(I:C) loading efficiency was about 50%, as assessed from the fluorescence intensity of fluorescently labelled poly(I:C). Immunogenicity of the liposomal SLP vaccine was evaluated in vitro by its capacity to activate dendritic cells (DCs) and present the processed SLP to SIINFEKL-specific T cells. The effectiveness of the vaccine to activate CD8(+) T cells was analysed in vivo after intradermal and subcutaneous immunisation in mice, by measuring antigen-specific T cells in blood and spleens and assessing their functionality by cytokine production and in vivo cytotoxicity. The liposomal formulation efficiently delivered the SLP to DCs in vitro and induced a functional CD8(+) T cell immune response in vivo to the CTL epitope present in the SLP. The SLP-specific CD8(+) T cell frequency induced by the poly(I:C)-adjuvanted liposomal SLP formulation showed an at least 25 fold increase over the T cell frequency induced by the poly(I:C)-adjuvanted soluble SLP. In conclusion, cationic liposomes loaded with SLP and poly(I:C) have potential as a powerful therapeutic cancer vaccine formulation.
Division of Drug Delivery Technology, Leiden Academic Centre for Drug Research (LACDR), Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands.
Eleni Maria
EM
Varypataki
Koen
K
van der Maaden
Joke
J
Bouwstra
Ferry
F
Ossendorp
Wim
W
Jiskoot
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000951:Antigens, Neoplasm / Q000008:administration & dosage* / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000008:administration & dosage* / Q000276:immunology; D002412:Cations; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D008081:Liposomes; D051379:Mice; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology; D010316:Particle Size; D010446:Peptide Fragments / Q000276:immunology; D010455:Peptides / Q000008:administration & dosage* / Q000276:immunology; D011070:Poly I-C / Q000008:administration & dosage* / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D000276:Adjuvants, Immunologic; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D002412:Cations; D008081:Liposomes; C110366:OVA-8; D010446:Peptide Fragments; D010455:Peptides; D010047:Ovalbumin; D011070:Poly I-C