Simultaneous immunisation with a Wilms' tumour 1 epitope and its ubiquitin fusions results in enhanced cell mediated immunity and tumour rejection in C57BL/6 mice

Induced pluripotent stem cell-derived dendritic cell vaccine therapy genetically modified on the ubiquitin-proteasome system

We previously reported that dendritic cells (DCs) transduced with the full-length tumor-associated antigen (TAA) gene induced TAA-specific cytotoxic T lymphocytes (CTLs) to elicit antitumor responses. To overcome the issue of quantity and quality of DCs required for DC vaccine therapy, we focused on induced pluripotent stem cells (iPSCs) as a new tool for obtaining DCs and reported efficacy of iPSCs-derived DCs (iPSDCs). However, in clinical application of iPSDC vaccine therapy, further enhancement of the antitumor effect is necessary. In this study, we targeted mesothelin (MSLN) as a potentially useful TAA, and focused on the ubiquitin-proteasome system to enhance antigen-presenting ability of iPSDCs. The CTLs induced by iPSDCs transduced with MSLN gene (iPSDCs-MSLN) from healthy donors showed cytotoxic activity against autologous lymphoblastoid cells (LCLs) expressing MSLN (LCLs-MSLN). The CTLs induced by iPSDCs transduced ubiquitin-MSLN fusion gene exhibited higher cytotoxic activity against LCLs-MSLN than the CTLs induced by iPSDCs-MSLN. The current study was designed that peripheral T-cell tolerance to MSLN could be overcome by the immunization of genetically modified iPSDCs simultaneously expressing ubiquitin and MSLN, leading to a strong cytotoxicity against tumors endogenously expressing MSLN. Therefore, this strategy may be promising for clinical application as an effective cancer vaccine therapy.

Dendritic Cells Transfected with MHC Antigenic Determinants of CBA Mice Induce Antigen-Specific Tolerance in C57Bl/6 Mice

Background

Nonspecific immunosuppressive therapy for graft rejection and graft-versus-host disease (GVHD) is often accompanied by severe side effects such as opportunistic infections and cancers. Several approaches have been developed to suppress transplantation reactions using tolerogenic cells, including induction of FoxP3⁺ Tregs with antigen-loaded dendritic cells (DCs) and induction of CD4⁺IL-10⁺ cells with interleukin IL-10-producing DCs. Here, we assessed the effectiveness of both approaches in the suppression of graft rejection and GVHD.

Methods

IL-10-producing DCs were generated by the transfection of DCs with DNA constructs encoding mouse IL-10. Antigen-loaded DCs from C57BL/6 mice were generated by transfection with DNA constructs encoding antigenic determinants from the H2 locus of CBA mice which differ from the homologous antigenic determinants of C57BL/6 mice.

Results

We found that both IL-10-producing DCs and antigen-loaded immature DCs could suppress graft rejection and GVHD but through distinct nonspecific and antigen-specific mechanisms, respectively. Discussion. We provide data that the novel approach for DCs antigen loading using DNA constructs encoding distinct homologous determinants derived from major histocompatibility complex genes is effective in antigen-specific suppression of transplantation reactions. Such an approach eliminates the necessity of donor material use and may be useful in immunosuppressive therapy side effects prevention.

[Development of the drug oncolytic immunotherapy based on vaccinia viruses (Vaccinia virus, Orthopoxvirus, Chordopoxvirinae, Poxviridae) against breast cancer.]

INTRODUCTION

Currently, new directions in cancer therapy are actively developing, one of which is oncolytic immunotherapy. This approach would be to use of viruses as cancer specific cytolytic agents capable of stimulating both the tumor-specific and non-specific immune response. The objective paper was obtain a recombinant vaccinia virus containing genes encoding immunostimulating molecules and study oncolytic and immunostimulating properties of recombinant virus.

MATERIAL AND METHODS

MTT test, ELISA, methods of transient dominant selection.

RESULTS

The recombinant vaccinia virus (L-IVP_oncoB) were obtained with deletion of the gene encoding thymidine kinase and had an integrated gene encoding GM-CSF. Also the virus have deletion of the gene encoding viral growth factor and integrated genes encoding synthetic tumor-specific polyepitopic immunogens. It was shown that the modifications made to the viral genome did not affect the growth characteristics of the virus when cultured on CV-1 and 4647 cell cultures, and the cytopathogenic efficacy of the virus was determined in relation to cancer cultures of cells of various genesis. In in vivo experiment, it was revealed that the polyepitopic construct in the genome L-IVP_oncoB is able to initiate a change in the profile of cytokines.

DISCUSSION

The obtained data characterized L-IVP_oncoB as a promising cytopathogenic and immunostimulating agent and showed the need for further study of its properties as means of oncolytic immunotherapy.

CONCLUSION

The basic experiments on the evaluation of the biological properties of the obtained L-IVP_oncoB, which are necessary for the characterization of the oncolytic virus, have been carried out.

DNA Vaccine Encoding HPV16 Oncogenes E6 and E7 Induces Potent Cell-mediated and Humoral Immunity Which Protects in Tumor Challenge and Drives E7-expressing Skin Graft Rejection

We have previously shown that a novel DNA vaccine technology of codon optimization and the addition of ubiquitin sequences enhanced immunogenicity of a herpes simplex virus 2 polynucleotide vaccine in mice, and induced cell-mediated immunity when administered in humans at relatively low doses of naked DNA. We here show that a new polynucleotide vaccine using the same technology and encoding a fusion protein of the E6 and E7 oncogenes of high-risk human papillomavirus type 16 (HPV16) is immunogenic in mice. This vaccine induces long-lasting humoral and cell-mediated immunity and protects mice from establishment of HPV16-E7-expressing tumors. In addition, it suppresses growth of readily established tumors and shows enhanced efficacy when combined with immune checkpoint blockade targeted at PD-L1. This vaccine also facilitates rejection of HPV16-E7-expressing skin grafts that demonstrate epidermal hyperplasia with characteristics of cervical and vulvar intraepithelial neoplasia. Clinical studies evaluating the efficacy of this vaccine in patients with HPV16 premalignancies are planned.

Expression, Polyubiquitination, and Therapeutic Potential of Recombinant E6E7 from HPV16 Antigens Fused to Ubiquitin

Ubiquitin-proteasome system plays an essential role in the immune response due to its involvement in the antigen generation and presentation to CD8⁺ T cells. Hereby, ubiquitin fused to antigens has been explored as an immunotherapeutic strategy that requires the activation of cytotoxic T lymphocytes. Here we propose to apply this ubiquitin fusion approach to a recombinant vaccine against human papillomavirus 16-infected cells. E6E7 multi-epitope antigen was fused genetically at its N- or C-terminal end to ubiquitin and expressed in Escherichia coli as inclusion bodies. The antigens were solubilized using urea and purified by nickel affinity chromatography in denatured condition. Fusion of ubiquitin to E6E7 resulted in marked polyubiquitination in vitro mainly when fused to the E6E7 N-terminal. When tested in a therapeutic scenario, the fusion of ubiquitin to E6E7 reinforced the anti-tumor protection and increased the E6/E7-specific cellular immune responses. Present results encourage the investigation of the adjuvant potential of the ubiquitin fusion to recombinant vaccines requiring CD8⁺ T cells.

A Novel DNA Vaccine Platform Enhances Neo-antigen-like T Cell Responses against WT1 to Break Tolerance and Induce Anti-tumor Immunity

Tumor-associated antigens have emerged as important immunotherapeutic targets in the fight against cancer. Germline tumor antigens, such as WT1, Wilms' tumor gene 1, are overexpressed in many human malignancies but have low expression in somatic tissues. Recent vaccination approaches to target WT1 have been hampered by poor in vivo immune potency, likely due to the conserved self-antigen nature of WT1. In this study, we use a novel synthetic micro-consensus SynCon DNA vaccine approach with the goal of breaking tolerance and increasing vaccine immune potency. This approach induced new, neo-antigen-like responses that were superior to those induced by native WT1 DNA immunogens for driving T cell immunity and breaking tolerance. Non-human primates (NHPs) vaccinated with SynCon WT1 antigens elicited immune responses against native rhesus WT1 peptides. When delivered by electroporation (EP) in mice, SynCon-based WT1 constructs elicited strong CD4 and CD8 T cell responses (including IFN-γ, CD107a, and TNF-α) to both native and consensus peptides. In addition, SynCon WT1 vaccine-induced antibodies recognized native WT1 in vitro. Vaccination with the SynCon WT1 immunogens was capable of slowing tumor growth in therapeutic models in vivo. These data support the further study of synthetic consensus DNA vaccines for breaking tolerance to important germline antigens.

Post-Genomics and Vaccine Improvement for Leishmania

Leishmaniasis is a parasitic disease that primarily affects Asia, Africa, South America, and the Mediterranean basin. Despite extensive efforts to develop an effective prophylactic vaccine, no promising vaccine is available yet. However, recent advancements in computational vaccinology on the one hand and genome sequencing approaches on the other have generated new hopes in vaccine development. Computational genome mining for new vaccine candidates is known as reverse vaccinology and is believed to further extend the current list of Leishmania vaccine candidates. Reverse vaccinology can also reduce the intrinsic risks associated with live attenuated vaccines. Individual epitopes arranged in tandem as polytopes are also a possible outcome of reverse genome mining. Here, we will briefly compare reverse vaccinology with conventional vaccinology in respect to Leishmania vaccine, and we will discuss how it influences the aforementioned topics. We will also introduce new in vivo models that will bridge the gap between human and laboratory animal models in future studies.

A Toxoplasma gondii vaccine encoding multistage antigens in conjunction with ubiquitin confers protective immunity to BALB/c mice against parasite infection

BACKGROUND

Toxoplasma gondii is a widely prevalent intracellular parasite which infects almost all warm-blooded animals including humans and causes serious zoonotic toxoplasmosis. DNA vaccines have proved effective in the protection against parasites. However, the problems of weak immunity and inefficient delivery of DNA vaccine remain major issues. Therefore, comprehensive antigens derived from all stages of the parasite, effective adjuvants and delivery systems should be considered in the vaccine construction.

METHODS

SAG3101-144,ROP18347-396, MIC6288-347, GRA7182-224, MAG158-125, BAG1156-211 and SPA142-200, derived from antigens in tachyzoite, bradyzoite and sporozoite stages of T. gondii were screened based on CD8(+) T cell epitope binding affinity to HLA and H-2. We constructed a recombinant DNA vaccine and an adenovirus vaccine encoding multi-stage antigen of T. gondii linked to ubiquitin molecules and vaccinated BALB/c mice with different strategies. Antibodies, cytokines, splenocytes proliferation, as well as the percentage of CD4(+) and CD8(+) T cells in immunized mouse were analyzed by the Enzyme-Linked Immunosorbent Assays (ELISA), Flow Cytometry (FCM). Protective efficacy was evaluated by challenging immunized mice with type I and type II parasite.

RESULTS

Our results indicated that the DNA vaccine had the advantage of inducing a stronger humoral response, whereas the adenovirus-vectored vaccine effectively improved the cellular immune response. Priming with DNA vaccine and boosting with adenovirus-vectored vaccine induced Th1-type immune responses with highest levels of IgG2a and secretion of cytokines IL-2 and IFN-γ. Effective protection against type I and type II parasite with an increase in survival rate and a decrease in brain cyst burden was achieved in immunized mice.

CONCLUSIONS

Priming vaccination with DNA vaccine and boosting with the recombinant adenovirus vaccine encoding ubiquitin conjugated multi-stage antigens of T. gondii was proved to be a potential strategy against the infection of type I and type II parasite.

Neoadjuvant anti-tumor vaccination prior to surgery enhances survival

Background

This study was conducted to determine if anti-tumor vaccination administered prior to partial debulking surgery could improve survival using a murine solid tumour model.

Methods

Tumor incidence and survival rates were compared in mice bearing subcutaneous AB1-HA mesothelioma tumors that received either sham surgery, debulking surgery or vaccination prior to debulking surgery. Additionally, mice were depleted of CD4 and/or CD8 T lymphocytes during vaccination to assess their involvement in vaccine induced anti-tumor immunity. Flow cytometry was performed to characterise changes in the proportion and activation status of immune cells associated with anti-tumor immunity.

Results

Neoadjuvant vaccination combined with debulking surgery resulted in decreased tumor burden, increased survival and generation of tumor-specific immunity compared to surgery alone. Depletion of CD8 T cells completely abrogated any vaccine induced anti-tumor immune response. Conversely, CD4 depletion enhanced CD8 T cell activation resulting in complete tumor regression in 70% of mice treated with combined surgery and vaccination therapy. Tumor free survival was associated with established immunological memory as defined by the induction of effector memory T cells and resistance to rechallenge with parental AB1 mesothelioma cells.

Conclusions

Neoadjuvant anti-cancer vaccination combined with partial debulking surgery induced CD8-dependent anti-tumor immunity that significantly delayed tumor outgrowth relative to surgery alone. Complete tumor eradication was observed when vaccination and surgery were performed in CD4 T cell depleted animals. This demonstrates that adjuvant immunotherapy can improve post-surgical survival following cancer debulking surgery and provides a scientific rational for clinical trials of such an approach.

The role of peptide and DNA vaccines in myeloid leukemia immunotherapy

While chemotherapy and targeted therapy are successful in inducing the remission of myeloid leukemia as acute myeloid leukemia (AML) and chronic myeloid leukemia (CML), the disease remains largely incurable. This observation is likely due to the drug resistance of leukemic cells, which are responsible for disease relapse. Myeloid leukemia vaccines may most likely be beneficial for eradicating minimal residual disease after treatment with chemotherapy or targeted therapy. Several targeted immunotherapies using leukemia vaccines have been heavily investigated in clinical and preclinical trials. This review will focus on peptides and DNA vaccines in the context of myeloid leukemias, and optimal strategies for enhancing the efficacy of vaccines based on myeloid leukemia immunization are also summarized.