ABSTRACT
RNA vaccines based on lipid nanoparticles (LNPs) with in vitro transcribed mRNA (IVT-mRNA) encapsulated are now a currently successful but still evolving modality of vaccines. One of the advantages of RNA vaccines is their ability to induce CD8+ T-cell-mediated cellular immunity that is indispensable for excluding pathogen-infected cells or cancer cells from the body. In this study, we report on the development of LNPs with an enhanced capability for inducing cellular immunity by using an ionizable lipid with a vitamin E scaffold. An RNA vaccine that contained this ionizable lipid and an IVT-mRNA encoding a model antigen ovalbumin (OVA) induced OVA-specific cytotoxic T cell responses and showed an antitumor effect against an E.G7-OVA tumor model. Vaccination with the LNPs conferred protection against lethal infection by Toxoplasma gondii using its antigen TgPF. The vitamin E scaffold-dependent type I interferon response was important for effector CD8+ T cell differentiation induced by the mRNA-LNPs. Our findings also revealed that conventional dendritic cells (cDCs) were essential for achieving CD8+ T cell responses induced by the mRNA-LNPs, while the XCR1-positive subset of cDCs, cDC1 specialized for antigen cross-presentation, was not required. Consistently, the mRNA-LNPs were found to selectively transfect another subset of cDCs, cDC2 that had migrated from the skin to lymph nodes, where they could make vaccine-antigen-dependent contacts with CD8+ T cells. The findings indicate that the activation of innate immune signaling by the adjuvant activity of the vitamin E scaffold and the expression of antigens in cDC2 are important for subsequent antigen presentation and the establishment of antigen-specific immune responses.
Subject(s)
Nanoparticles , T-Lymphocytes, Cytotoxic , Animals , Mice , CD8-Positive T-Lymphocytes , Vitamin E/pharmacology , Vaccines, Synthetic , mRNA Vaccines , Antigens , Ovalbumin , RNA, Messenger/genetics , Lipids/pharmacology , Mice, Inbred C57BL , Dendritic CellsABSTRACT
Cytoplasmic DNA triggers cellular immunity via activating the stimulator of interferon genes pathway. Since DNA is degradable and membrane impermeable, delivery system would permit cytoplasmic delivery by destabilizing the endosomal membrane for the use as an adjuvant. Herein, we report on the development of a plasmid DNA (pDNA)-encapsulating lipid nanoparticle (LNP). The structural components include an SS-cleavable and pH-activated lipid-like material that mounts vitamin E as a hydrophobic scaffold, and dual sensing motifs that are responsive to the intracellular environment (ssPalmE). The pDNA-encapsulating LNP (ssPalmE-LNP) induced a high interferon-ß production in Raw 264.7 cells. The subcutaneous injection of ssPalmE-LNP strongly enhanced antigen-specific cytotoxic T cell activity. The ssPalmE-LNP treatment efficiently induced antitumor effects against E.G7-OVA tumor and B16-F10 melanoma metastasis. Furthermore, when combined with an anti-programmed death 1 antibody, an extensive therapeutic antitumor effect was observed. Therefore, the ssPalmE-LNP is a promising carrier of adjuvants for cancer immunotherapy.
Subject(s)
Antibodies, Monoclonal/pharmacology , DNA/chemistry , Immunotherapy , Lipids/chemistry , Melanoma, Experimental/drug therapy , Nanoparticles/administration & dosage , Ovarian Neoplasms/drug therapy , Vitamin E/administration & dosage , Adjuvants, Immunologic , Animals , Antibodies, Monoclonal/administration & dosage , Cells, Cultured , Female , Humans , Hydrophobic and Hydrophilic Interactions , Liposomes/administration & dosage , Liposomes/chemistry , Macrophages/drug effects , Macrophages/immunology , Macrophages/metabolism , Melanoma, Experimental/immunology , Melanoma, Experimental/metabolism , Melanoma, Experimental/pathology , Mice , Mice, Inbred C57BL , Nanoparticles/chemistry , Ovarian Neoplasms/immunology , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/pathology , Programmed Cell Death 1 Receptor/antagonists & inhibitors , T-Lymphocytes, Cytotoxic/drug effects , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/metabolism , Vitamin E/chemistryABSTRACT
The use of gold nanorods (AuNRs) that produce heat in response to near infrared (NIR) irradiation is an attractive approach to cancer photothermal therapy. AuNRs are usually prepared by using a highly toxic detergent: cetyltrimethylammonium bromide (CTAB). Thus, the removal of CTAB from the reaction mixture, and further stabilization of the surface of the AuNRs is required. In the present study, AuNRs were encapsulated in a multifunctional envelope-type nano device (AuNR-MEND) formed with an SS-cleavable and pH-activated lipid-like material. In the process of encapsulation, AuNRs were first stabilized with bovine serum albumin (AuNR-BSA), and then further encapsulated in the lipid envelope by the ethanol dilution method. The in vitro photothermal cytotoxicity of AuNR-MEND was further demonstrated on 4T1 breast cancer cells. After NIR radiation, the temperature of the medium was increased to approximately 60°C, and cell viability was drastically decreased to approximately 11%. However, this cytotoxic effect cannot simply be explained by medium heating. It therefore appears that intracellular delivery of the AuNRs is a key factor for achieving a high degree of cytotoxicity. Dose dependent cytotoxicity data revealed that a higher dose of AuNR-MEND resulted in the complete destruction of the cells when they were subjected to NIR irradiation, while the cell survival rate reached a plateau at 30% in the case of AuNR-BSA. Apoptosis was induced after treatment with the nanoparticles. AuNR-MEND showed superior cellular uptake activity over AuNR-BSA. Thus, delivering AuNR by means of functionalized lipid nanoparticles represents a promising approach to induce NIR-triggered apoptosis.