Superior anti-tumor protection and therapeutic efficacy of vaccination with dendritic cell/tumor cell fusion hybrids for murine Lewis lung carcinoma

BACKGROUND

The development of protocols for the ex vivo generation of dendritic cells (DCs) has led to intensive research into their potential use in immunotherapy in the treatment of cancer. In this study, we examined the efficacy of dendritic cell-tumor cell fusion hybrid vaccines in eliciting an immune response against Lewis lung carcinoma (LLC) cells, as compared to other types of tumor vaccines. In addition, we also tested whether the efficacy of the vaccines was affected by the route of administration. Four different tumor vaccines were compared: (1) HC (hybrid cell), consisting of DC/LLC hybrids; (2) DC+LLC (DCs pulsed with apoptotic LLCs); (3) DC without antigen loading/pulsing; (4) LLC (apoptotic/irradiated tumor cells). We also compared four different routes of administration for each vaccine: (1) Preimmunization; (2) Vaccination therapy; (3) Adoptive immunotherapy; (4) Vaccination therapy combined with adoptive immunotherapy. Anti-tumor immunity was assessed in vivo and the CTL (cytotoxic T lymphocyte) response as well as the expression of key cytokines, IFN-γ and IL-10 were further evaluated using in vitro assays.

RESULTS

Our data demonstrate that vaccination with HC hybrids provides more effective anti-tumor protective immunity and significantly greater therapeutic immunity than vaccination with DC+LLC, DC or LLC. Most remarkably, vaccination therapy with HC hybrids was more successful than combination (vaccination + adoptive) therapy for the induction of anti-tumor responses. Splenocytes harvested from mice immunized with HC hybrids demonstrated the greatest cytotoxic T lymphocyte (CTL) activity and their production of IFN-γ was high, while their production of IL-10 was very low.

CONCLUSIONS

Our results suggest that vaccination therapy with DC-tumor cell fusion hybrids provides more effective protection against lung cancer.

Cancer therapy and vaccination

Cancer remains one of the leading causes of death worldwide, both in developed and in developing nations. It may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Current therapeutic approaches which include surgery, chemotherapy and radiotherapy are associated with adverse side effects arising from lack of specificity for tumors. The goal of any therapeutic strategy is to impact on the target tumor cells with limited detrimental effect to normal cell function. Immunotherapy is cancer specific and can target the disease with minimal impact on normal tissues. Cancer vaccines are capable of generating an active tumor-specific immune response and serve as an ideal treatment due to their specificity for tumor cells and long lasting immunological memory that may safeguard against recurrences. Cancer vaccines are designed to either prevent (prophylactic) or treat established cancer (therapeutic). Identification of tumor-associated antigens (TAAs) and tumor-specific antigens (TSAs) has led to increased efforts to develop vaccination strategies. Vaccines may be composed of whole cells or cell extracts, genetically modified tumor cells to express costimulatory molecules, dendritic cells (DCs) loaded with TAAs, immunization with soluble proteins or synthetic peptides, recombinant viruses or bacteria encoding tumor-associated antigens, and plasmid DNA encoding TSAs or TAAs in conjunction with appropriate immunomodulators. All of these antitumor vaccination approaches aim to induce specific immunological responses and localized to TAAs, destroying tumor cells alone and leaving the vast majority of other healthy cells of the body untouched.

15 kDa granulysin causes differentiation of monocytes to dendritic cells but lacks cytotoxic activity

Granulysin is expressed as two isoforms by human cytotoxic cells: a single mRNA gives rise to 15 kDa granulysin, a portion of which is cleaved to a 9 kDa protein. Studies with recombinant 9 kDa granulysin have demonstrated its cytolytic and proinflammatory properties, but much less is known about the biologic function of the 15 kDa isoform. In this study, we show that the subcellular localization and functions of 9 and 15 kDa granulysin are largely distinct. Nine kilodalton granulysin is confined to cytolytic granules that are directionally released following target cell recognition. In contrast, 15 kDa granulysin is located in distinct granules that lack perforin and granzyme B and that are released by activated cytolytic cells. Although recombinant 9 kDa granulysin is cytolytic against a variety of tumors and microbes, recombinant 15 kDa granulysin is not. The 15 kDa isoform is a potent inducer of monocytic differentiation to dendritic cells, but the 9 kDa isoform is not. In vivo, mice expressing granulysin show markedly improved antitumor responses, with increased numbers of activated dendritic cells and cytokine-producing T cells. Thus, the distinct functions of granulysin isoforms have major implications for diagnosis and potential new therapies for human disease.

High hydrostatic pressure treatment generates inactivated mammalian tumor cells with immunogeneic features

Most of the classical therapies for solid tumors have limitations in achieving long-lasting anti-tumor responses. Therefore, treatment of cancer requires additional and multimodal therapeutic strategies. One option is based on the vaccination of cancer patients with autologous inactivated intact tumor cells. The master requirements of cell-based therapeutic tumor vaccines are the: (a) complete inactivation of the tumor cells; (b) preservation of their immunogenicity; and (c) need to remain in accordance with statutory provisions. Physical treatments like freeze-thawing and chemotherapeutics are currently used to inactivate tumor cells for vaccination purposes, but these techniques have methodological, therapeutic, or legal restrictions. For this reason, we have proposed the use of a high hydrostatic pressure (HHP) treatment (p >or= 100 MPa) as an alternative method for the inactivation of tumor cells. HHP is a technique that has been known for more than 100 years to successfully inactivate micro-organisms and to alter biomolecules. In the studies here, we show that the treatment of MCF7, B16-F10, and CT26 tumor cells with HHP >or= 300 MPa results in mainly necrotic tumor cell death forms displaying degraded DNA. Only CT26 cells yielded a notable amount of apoptotic cells after the application of HHP. All tumor cells treated with >or= 200 MPa lost their ability to form colonies in vitro. Furthermore, the pressure-inactivated cells retained their immunogenicity, as tested in a xenogeneic as well as syngeneic mouse models. We conclude that the complete tumor cell inactivation, the degradation of the cell's nuclei, and the retention of the immunogeneic potential of these dead tumor cells induced by HHP favor the use of this technique as a powerful and low-cost technique for the inactivation of tumor cells to be used as a vaccine.

Crystal ball - 2011

In this feature, leading researchers in the field of microbial biotechnology speculate on the technical and conceptual developments that will drive innovative research and open new vistas over the next few years.

Proteomics for development of vaccine

The success of genome projects has provided us with a vast amount of information on genes of many pathogenic species and has raised hopes for rapid progress in combating infectious diseases, both by construction of new effective vaccines and by creating a new generation of therapeutic drugs. Proteomics, a strategy complementary to the genomic-based approach, when combined with immunomics (looking for immunogenic proteins) and vaccinomics (characterization of host response to immunization), delivers valuable information on pathogen-host cell interaction. It also speeds the identification and detailed characterization of new antigens, which are potential candidates for vaccine development. This review begins with an overview of the global status of vaccinology based on WHO data. The main part of this review describes the impact of proteomic strategies on advancements in constructing effective antibacterial, antiviral and anticancer vaccines. Diverse aspects of disease mechanisms and disease preventions have been investigated by proteomics.

Artificial antigen-presenting cells for use in adoptive immunotherapy

The observation that T cells can recognize and specifically eliminate cancer cells has spurred interest in the development of efficient methods to generate large numbers of T cells with specificity for tumor antigens that can be harnessed for use in cancer therapy. Recent studies have demonstrated that during encounter with tumor antigen, the signals delivered to T cells by professional antigen-presenting cells can affect T-cell programming and their subsequent therapeutic efficacy. This has stimulated efforts to develop artificial antigen-presenting cells that allow optimal control over the signals provided to T cells. In this review, we will discuss the advantages and disadvantages of cellular and acellular artificial antigen-presenting cell systems and their use in T-cell adoptive immunotherapy for cancer.

Expression and purification of 15 kDa granulysin utilizing an insect cell secretion system

Granulysin is an antimicrobial and proinflammatory protein expressed in activated human T cells and natural killer cells. A single mRNA produces the 15 kDa isoform which is then cleaved at the amino and carboxy termini to produce the 9 kDa isoform. Recombinant 9 kDa granulysin has been studied in detail but little is known about the function of the 15 kDa isoform, and no protocol has been published describing expression and purification of this form. Two commercially available preparations of the recombinant 15 kDa granulysin contain tags that may affect function. Here we describe for the first time a method to produce 15 kDa granulysin as a secreted protein from insect cells. The 15 kDa granulysin is purified using a HiTrap Heparin column and a Resource S column. A typical a yield of purified 15 kDa granulysin is 0.6 mg/L of insect cell supernatant.

TAA polyepitope DNA-based vaccines: a potential tool for cancer therapy

DNA-based cancer vaccines represent an attractive strategy for inducing immunity to tumor associated antigens (TAAs) in cancer patients. The demonstration that the delivery of a recombinant plasmid encoding epitopes can lead to epitope production, processing, and presentation to CD8+ T-lymphocytes, and the advantage of using a single DNA construct encoding multiple epitopes of one or more TAAs to elicit a broad spectrum of cytotoxic T-lymphocytes has encouraged the development of a variety of strategies aimed at increasing immunogenicity of TAA polyepitope DNA-based vaccines. The polyepitope DNA-based cancer vaccine approach can (a) circumvent the variability of peptide presentation by tumor cells, (b) allow the introduction in the plasmid construct of multiple immunogenic epitopes including heteroclitic epitope versions, and (c) permit to enroll patients with different major histocompatibility complex (MHC) haplotypes. This review will discuss the rationale for using the TAA polyepitope DNA-based vaccination strategy and recent results corroborating the usefulness of DNA encoding polyepitope vaccines as a potential tool for cancer therapy.

Recombinant lambda-phage nanobioparticles for tumor therapy in mice models

Lambda phages have considerable potential as gene delivery vehicles due to their genetic tractability, low cost, safety and physical characteristics in comparison to other nanocarriers and gene porters. Little is known concerning lambda phage-mediated gene transfer and expression in mammalian hosts. We therefore performed experiments to evaluate lambda-ZAP bacteriophage-mediated gene transfer and expression in vitro. For this purpose, we constructed recombinant λ-phage nanobioparticles containing a mammalian expression cassette encoding enhanced green fluorescent protein (EGFP) and E7 gene of human papillomavirus type 16 (λ-HPV-16 E7) using Lambda ZAP- CMV XR vector. Four cell lines (COS-7, CHO, TC-1 and HEK-239) were transduced with the nanobioparticles. We also characterized the therapeutic anti-tumor effects of the recombinant λ-HPV-16 E7 phage in C57BL/6 tumor mice model as a cancer vaccine. Obtained results showed that delivery and expression of these genes in fibroblastic cells (COS-7 and CHO) are more efficient than epithelial cells (TC-1 and HEK-239) using these nanobioparticles. Despite the same phage M.O.I entry, the internalizing titers of COS-7 and CHO cells were more than TC-1 and HEK-293 cells, respectively. Mice vaccinated with λ-HPV-16 E7 are able to generate potent therapeutic antitumor effects against challenge with E7- expressing tumor cell line, TC-1 compared to group treated with the wild phage. The results demonstrated that the recombinant λ-phages, due to their capabilities in transducing mammalian cells, can also be considered in design and construction of novel and safe phage-based nanomedicines.

Therapeutic antibodies, vaccines and antibodyomes

The potential for antibodies to act as "magic bullets" for treatment of human disease was recognized a century ago, but its full realization has began to occur only during the last decade. A key to their current success is the ability to make libraries of antibodies/B cells, isolate a single species, and engineer it to be safe, efficacious and of high quality. Despite this progress, major challenges to the effective prevention, diagnosis and treatment of a vast majority of diseases remain. Limited success in the development of effective vaccines against diseases such as AIDS and cancer reflects our incomplete understanding of how antibodies are generated and function. Only a miniscule number of antibodies are characterized out of the universe of antibodies generated by the immune system. Knowledge of antibodyomes-the complete sets of antibodies-could help solve these and other challenges.