Improving dendritic cell vaccine immunogenicity by silencing PD-1 ligands using siRNA-lipid nanoparticles combined with antigen mRNA electroporation

• Published in: Cancer Immunology, Immunotherapy Immunotherapy, 2013-02, Vol.62 (2), p.285-297
• Main Authors: Hobo, Willemijn, Novobrantseva, Tatiana I., Fredrix, Hanny, Wong, Jamie, Milstein, Stuart, Epstein-Barash, Hila, Liu, Ju, Schaap, Nicolaas, van der Voort, Robbert, Dolstra, Harry
• Format: Article
• Language: English
• Subjects: Antigens; Antigens, Neoplasm - genetics; Antigens, Neoplasm - immunology; Cancer; Cancer Research; Cancer Vaccines - genetics; Cancer Vaccines - immunology; CD8-Positive T-Lymphocytes - immunology; Dendritic cells; Dendritic Cells - immunology; Electroporation; Gene Silencing; Hematology; Humans; Immunology; Immunotherapy; Leukocytes, Mononuclear - immunology; Ligands; Lipids; Lipids - immunology; Lymphocyte Activation - immunology; Lymphocytes; Medicine; Medicine & Public Health; Nanoparticles; Oncology; Original; Original Article; Peptides; Polyethylene glycol; Programmed Cell Death 1 Ligand 2 Protein - genetics; Programmed Cell Death 1 Ligand 2 Protein - immunology; Programmed Cell Death 1 Receptor - genetics; Programmed Cell Death 1 Receptor - immunology; RNA, Messenger - genetics; RNA, Small Interfering - genetics; Transfection; Vaccines; Viral infections
• ISSN: 0340-7004; 1432-0851
• DOI: 10.1007/s00262-012-1334-1

Dendritic cell (DC)-based vaccination boosting antigen-specific immunity is being explored for the treatment of cancer and chronic viral infections. Although DC-based immunotherapy can induce immunological responses, its clinical benefit has been limited, indicating that further improvement of DC vaccine potency is essential. In this study, we explored the generation of a clinical-grade applicable DC vaccine with improved immunogenic potential by combining PD-1 ligand siRNA and target antigen mRNA delivery. We demonstrated that PD-L1 and PD-L2 siRNA delivery using DLin-KC2-DMA-containing lipid nanoparticles (LNP) mediated efficient and specific knockdown of PD-L expression on human monocyte-derived DC. The established siRNA-LNP transfection method did not affect DC phenotype or migratory capacity and resulted in acceptable DC viability. Furthermore, we showed that siRNA-LNP transfection can be successfully combined with both target antigen peptide loading and mRNA electroporation. Finally, we demonstrated that these PD-L-silenced DC loaded with antigen mRNA superiorly boost ex vivo antigen-specific CD8 + T cell responses from transplanted cancer patients. Together, these findings indicate that our PD-L siRNA-LNP-modified DC are attractive cells for clinical-grade production and in vivo application to induce and boost immune responses not only in transplanted cancer patients, but likely also in other settings.