Journal Article

Co-expression of IL-15 enhances anti-neuroblastoma effectivity of a tyrosine hydroxylase-directed DNA vaccination in mice

Zumpe, Maxi, Lode, Holger N., Troschke-Meurer, Sascha, Marx, Madlen, Siebert, Nikolai, Shah, Diana

2018

Overview

Long-term survival of high-risk neuroblastoma (NB) patients still remains under 50%. Here, we report the generation, in vitro characterization and anti-tumor effectivity of a new bicistronic xenogenic DNA vaccine encoding tyrosine hydroxylase (TH) that is highly expressed in NB tumors, and the immune stimulating cytokine interleukin 15 (IL-15) that induces cytotoxic but not regulatory T cells. The DNA sequences of TH linked to ubiquitin and of IL-15 were integrated into the bicistronic expression vector pIRES. Successful production and bioactivity of the vaccine-derived IL-15- and TH protein were shown by ELISA, bioactivity assay and western blot analysis. Further, DNA vaccine-driven gene transfer to the antigen presenting cells of Peyer's patches using attenuated Salmonella typhimurium that served as oral delivery system was shown by immunofluorescence analysis. The anti-tumor effect of the generated vaccine was evaluated in a syngeneic mouse model (A/J mice, n = 12) after immunization with S. typhimurium (3× prior and 3× after tumor implantation). Importantly, TH-/IL-15-based DNA vaccination resulted in an enhanced tumor remission in 45.5% of mice compared to controls (TH (16.7%), IL-15 (0%)) and reduced spontaneous metastasis (30.0%) compared to controls (TH (63.6%), IL-15 (70.0%)). Interestingly, similar levels of tumor infiltrating CD8+ T cells were observed among all experimental groups. Finally, co-expression of IL-15 did not result in elevated regulatory T cell levels in tumor environment measured by flow cytometry. In conclusion, co-expression of the stimulatory cytokine IL-15 enhanced the NB-specific anti-tumor effectivity of a TH-directed vaccination in mice and may provide a novel immunological approach for NB patients.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Analysis / Animals / Anticancer properties / Antigen-presenting cells / Biological activity / Biology and life sciences / Bone marrow / Cancer / Cancer Vaccines - genetics / Cancer Vaccines - immunology / CD8 antigen / CD8-Positive T-Lymphocytes - immunology / CD8-Positive T-Lymphocytes - pathology / Cell growth / CHO Cells / Cricetulus / Cytokines / Cytotoxicity / Deoxyribonucleic acid / Diagnosis / DNA / DNA sequencing / DNA vaccines / Drug dosages / Enzyme-linked immunosorbent assay / Flow cytometry / Gene expression / Gene sequencing / Gene transfer / Genetic aspects / Hematology / Humans / Hydroxylase / Immune response / Immunity, Cellular / Immunization / Immunofluorescence / Immunology / Immunoregulation / Immunotherapy / Implantation / Interleukin 15 / Interleukin-15 - genetics / Interleukin-15 - immunology / Lymphocytes / Lymphocytes T / Medicine / Medicine and health sciences / Metastases / Mice / Neuroblastoma / Neuroblastoma - genetics / Neuroblastoma - immunology / Neuroblastoma - pathology / Neuroblastoma - therapy / Nucleotide sequence / Nucleotide sequencing / Oncology / Patients / Pediatrics / Plasmids / Proteins / Remission / Salmonella / Salmonella typhimurium - genetics / Salmonella typhimurium - immunology / T cells / Tumors / Tyrosine / Tyrosine 3-monooxygenase / Tyrosine 3-Monooxygenase - genetics / Tyrosine 3-Monooxygenase - immunology / Ubiquitin / Vaccination / Vaccines / Vaccines, DNA - genetics / Vaccines, DNA - immunology