ABSTRACT
Recent years have seen a resurgence in interest in the development of efficient non-viral delivery systems for DNA vaccines and gene therapy. We have previously used oxidized and reduced mannan as carriers for protein delivery to antigen-presenting cells by targeting the receptors that bind mannose, resulting in efficient induction of cellular responses. In the present study, oxidized mannan and reduced mannan were used as receptor-mediated gene transfer ligands for cancer immunotherapy. In vivo studies in C57BL/6 mice showed that injection of DNA encoding ovalbumin (OVA) complexed to oxidized or reduced mannan-poly-L-lysine induced CD8 and CD4 T-cell responses as well as antibody responses leading to protection of mice from OVA+ tumours. Both oxidized and reduced mannan delivery was superior to DNA alone or DNA-poly-L-lysine. These studies demonstrate the potential of oxidized and reduced mannan for efficient receptor-mediated gene delivery in vivo, particularly as DNA vaccines for cancer immunotherapy.
Subject(s)
Cancer Vaccines/immunology , Gene Transfer Techniques , Mannans/immunology , Neoplasms, Experimental/prevention & control , Vaccines, DNA/immunology , Animals , Antibodies, Neoplasm/biosynthesis , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Cell Death/drug effects , Cell Line, Tumor , Enzyme-Linked Immunosorbent Assay/methods , Female , Genetic Therapy/methods , Lectins, C-Type/immunology , Lymphocyte Activation/immunology , Mannose Receptor , Mannose-Binding Lectins/immunology , Mice , Mice, Inbred C57BL , Neoplasm Transplantation , Neoplasms, Experimental/immunology , Ovalbumin/genetics , Ovalbumin/immunology , Oxidation-Reduction , Polylysine/immunology , Polylysine/pharmacology , Receptors, Cell Surface/immunologyABSTRACT
DNA formulations provide the basis for safe and cost efficient vaccines. However, naked plasmid DNA is only poorly immunogenic and new effective delivery strategies are needed to enhance the potency of DNA vaccines. In this study, we present a novel approach for the delivery of DNA vaccines using inert poly-L-lysine (PLL) coated polystyrene particles, which greatly enhance DNA immunogenicity. Intradermal injection of plasmid DNA encoding for chicken egg ovalbumin (OVA) complexed with PLL-coated polystyrene nanoparticles induced high levels of CD8 T cells as well as OVA-specific antibodies in C57BL/6 mice and furthermore inhibited tumour growth after challenge with the OVA expressing EG7 tumour cell line. Importantly, vaccine efficacy depended critically on the size of the particles used as well as on the presence of the PLL linker. Our data show that PLL-coated polystyrene nanoparticles of 0.05 microm but not 0.02 microm or 1.0 microm in diameter are highly effective for the delivery of DNA vaccines.
