ovalbumin and Glioma

Virus vector-based vaccination against tumor-specific antigens remains a promising therapeutic approach to overcome the immune suppressive tumor microenvironment. However, the extent that the desired CD8 T cell response against the targeted tumor antigen is impacted by the CD8 T cell response against the virus vector is unclear. To address this question, we used picornavirus vaccination with Theiler's murine encephalomyelitis virus (TMEV) as our vector against tumor-expressed ovalbumin (OVA257-264) antigen in both the B16-OVA murine melanoma and GL261-quad cassette murine glioma models. Prior to vaccination, we employed vector silencing to inhibit the CD8 T cell response against the immunodominant TMEV antigen, VP2121-130. We then monitored the resulting effect on the CD8 T cell response against the targeted tumor-specific antigen, ovalbumin. We demonstrate that employing vector silencing in the context of B16-OVA melanoma does not reduce tumor burden or improve survival, while TMEV-OVA vaccination without vector silencing controls tumor burden. Meanwhile, employing vector silencing during picornavirus vaccination against the GL261-quad cassette glioma resulted in a lower frequency of tumor antigen-specific CD8 T cells. The results of this study are relevant to antigen-specific immunotherapy, in that the virus vector-specific CD8 T cell response is not competing with tumor antigen-specific CD8 T cells. Furthermore, vector silencing may have the adverse consequence of reducing the tumor antigen-specific CD8 T cell response, as demonstrated by our findings in the GL261-quad cassette model.

Topics: Animals; Antigens, Viral; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Cytokines; Epitopes, T-Lymphocyte; Flow Cytometry; Genetic Vectors; Glioma; Humans; Melanoma, Experimental; Mice, Inbred C57BL; Neoplasms, Experimental; Ovalbumin; Picornaviridae; Theilovirus; Tumor Burden; Vaccination

Glioblastoma (GBM) is among the most invasive and lethal of cancers, frequently infiltrating surrounding healthy tissue and giving rise to rapid recurrence. It is therefore critical to establish experimental model systems and develop therapeutic approaches that enhance anti-tumor immunity. In the current study, we have employed a newly developed murine glioma model to assess the efficacy of a novel picornavirus vaccination approach for the treatment of established tumors. The GL261-Quad system is a variation of the GL261 syngeneic glioma that has been engineered to expresses model T cell epitopes including OVA257-264. MRI revealed that both GL261 and GL261-Quad tumors display characteristic features of human gliomas such as heterogeneous gadolinium leakage and larger T2 weighted volumes. Analysis of brain-infiltrating immune cells demonstrated that GL261-Quad gliomas generate detectable CD8+ T cell responses toward the tumor-specific Kb:OVA257-264 antigen. Enhancing this response via a single intracranial or peripheral vaccination with picornavirus expressing the OVA257-264 antigen increased anti-tumor CD8+ T cells infiltrating the brain, attenuated progression of established tumors, and extended survival of treated mice. Importantly, the efficacy of the picornavirus vaccination is dependent on functional cytotoxic activity of CD8+ T cells, as the beneficial response was completely abrogated in mice lacking perforin expression. Therefore, we have developed a novel system for evaluating mechanisms of anti-tumor immunity in vivo, incorporating the GL261-Quad model, 3D volumetric MRI, and picornavirus vaccination to enhance tumor-specific cytotoxic CD8+ T cell responses and track their effectiveness at eradicating established gliomas in vivo.

Topics: Animals; Antigens, Neoplasm; Biomarkers; Brain Neoplasms; Cancer Vaccines; Cell Line, Tumor; Cell Movement; Disease Models, Animal; Epitopes, T-Lymphocyte; Female; Gene Expression; Glioma; Humans; Injections, Intraventricular; Mice; Mice, Inbred C57BL; Ovalbumin; Peptide Fragments; Picornaviridae; Pore Forming Cytotoxic Proteins; Survival Analysis; T-Lymphocytes, Cytotoxic; Treatment Outcome; Vaccination

Dendritic cells (DCs) are professional APCs that are traditionally divided into two distinct subsets, myeloid DC (mDCs) and plasmacytoid DC (pDCs). pDCs are known for their ability to secrete large amounts of IFN-α. Apart from IFN-α production, pDCs can also process Ag and induce T cell immunity or tolerance. In several solid tumors, pDCs have been shown to play a critical role in promoting tumor immunosuppression. We investigated the role of pDCs in the process of glioma progression in the syngeneic murine model of glioma. We show that glioma-infiltrating pDCs are the major APC in glioma and are deficient in IFN-α secretion (p < 0.05). pDC depletion leads to increased survival of the mice bearing intracranial tumor by decreasing the number of regulatory T cells (Tregs) and by decreasing the suppressive capabilities of Tregs. We subsequently compared the ability of mDCs and pDCs to generate effective antiglioma immunity in a GL261-OVA mouse model of glioma. Our data suggest that mature pDCs and mDCs isolated from naive mice can be effectively activated and loaded with SIINFEKL Ag in vitro. Upon intradermal injection in the hindleg, a fraction of both types of DCs migrate to the brain and lymph nodes. Compared to mice vaccinated with pDC or control mice, mice vaccinated with mDCs generate a robust Th1 type immune response, characterized by high frequency of CD4(+)T-bet(+) T cells and CD8(+)SIINFEKEL(+) T cells. This robust antitumor T cell response results in tumor eradication and long-term survival in 60% of the animals (p < 0.001).

Topics: Adaptive Immunity; Animals; Brain; Brain Neoplasms; Cancer Vaccines; Cell Count; Cell Lineage; Cell Movement; Dendritic Cells; Glioma; Immunodominant Epitopes; Interferon-alpha; Lymph Nodes; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myeloid Cells; Ovalbumin; Peptide Fragments; Survival Analysis; T-Lymphocytes, Regulatory; Th1 Cells; Vaccination

To analyze the in vivo structure of antigen-specific immunological synapses during an effective immune response, we established brain tumors expressing the surrogate tumor antigen ovalbumin and labeled antigen-specific anti-glioma T cells using specific tetramers. Using these techniques, we determined that a significant number of antigen-specific T cells were localized to the brain tumor and surrounding brain tissue and a large percentage could be induced to express IFNgamma when exposed to the specific ovalbumin-derived peptide epitope SIINFEKL. Detailed morphological analysis of T cells immunoreactive for tetramers in direct physical contact with tumor cells expressing ovalbumin indicated that the interface between T cells and target tumor cells displayed various morphologies, including Kupfer-type immunological synapses. Quantitative analysis of adjacent confocal optical sections was performed to determine if the higher frequency of antigen-specific antiglioma T cells present in animals that developed an effective antitumor immune response could be correlated with a specific immunological synaptic morphology. Detailed in vivo quantitative analysis failed to detect an increased proportion of immunological synapses displaying the characteristic Kupfer-type morphology in animals mounting a strong and effective antitumor immune response as compared with those experiencing a clinically ineffective response. We conclude that an effective cytolytic immune response is not dependent on an increased frequency of Kupfer-type immunological synapses between T cells and tumor cells.

Topics: Animals; Antiviral Agents; Blotting, Western; Brain Neoplasms; Cell Line, Tumor; Female; Flow Cytometry; Ganciclovir; Genetic Therapy; Glioma; Herpesvirus 1, Human; Immunological Synapses; Interferon-gamma; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Confocal; Ovalbumin; T-Lymphocytes; T-Lymphocytes, Cytotoxic; Thymidine Kinase

Toll-like receptor (TLR)3 ligands serve as natural inducers of pro-inflammatory cytokines capable of promoting Type-1 adaptive immunity, and TLR3 is abundantly expressed by cells within the central nervous system (CNS). To improve the efficacy of vaccine strategies directed against CNS tumors, we evaluated whether administration of a TLR3 ligand, polyinosinic-polycytidylic (poly-IC) stabilized with poly-lysine and carboxymethylcellulose (poly-ICLC) would enhance the anti-CNS tumor effectiveness of tumor peptide-based vaccinations.. C57BL/6 mice bearing syngeneic CNS GL261 glioma or M05 melanoma received subcutaneous (s.c.) vaccinations with synthetic peptides encoding CTL epitopes--mEphA2 (671-679), hgp100 (25-33) and mTRP-2 (180-188) for GL261, or ovalbumin (OVA: 257-264) for M05. The mice also received intramuscular (i.m.) injections with poly-ICLC.. The combination of subcutaneous (s.c.) peptide-based vaccination and i.m. poly-ICLC administration promoted systemic induction of antigen (Ag)-specific Type-1 CTLs expressing very late activation antigen (VLA)-4, which confers efficient CNS-tumor homing of vaccine-induced CTLs based on experiments with monoclonal antibody (mAb)-mediated blockade of VLA-4. In addition, the combination treatment allowed expression of IFN-gamma by CNS tumor-infiltrating CTLs, and improved the survival of tumor bearing mice in the absence of detectable autoimmunity.. These data suggest that poly-ICLC, which has been previously evaluated in clinical trials, can be effectively combined with tumor Ag-specific vaccine strategies, thereby providing a greater index of therapeutic efficacy.

Topics: Animals; Antigens, Neoplasm; Cancer Vaccines; Carboxymethylcellulose Sodium; Cell Line, Tumor; Combined Modality Therapy; Disease Models, Animal; Encephalomyelitis, Autoimmune, Experimental; Ephrin-A2; Epitopes; Glioma; Humans; Injections, Intramuscular; Integrin alpha4beta1; Ligands; Lymphocytes, Tumor-Infiltrating; Mice; Mice, Inbred C57BL; Ovalbumin; Peptides; Poly I-C; Polylysine; Staining and Labeling; T-Lymphocytes, Cytotoxic; Toll-Like Receptor 3; Treatment Outcome; Up-Regulation; Vaccination

Tumor cells have been reported to exert inhibitory effects on the activation of T lymphocytes in vitro. We show that the IL-2-stimulated proliferation of a Th cell line is suppressed when the T cells are cocultured with human glioblastoma and melanoma cell lines. The use of two Th cell clones that differ in their responsiveness to growth-inhibition by transforming growth factor-beta (TGF-beta) and the analysis of tumor cell-derived supernatants as well as of TGF-beta 1/TGF-beta 2 gene expression allowed to distinguish two pathways of tumor-induced immunosuppression. Glioblastoma cells exert their immunosuppressive effects by producing biologically active TGF-beta 2, whereas the immunosuppressive state induced by melanoma cells is TGF-beta-independent and requires direct contact between tumor cell and T cell. The TGF-beta-dependent immunosuppression is down-regulated by various protease inhibitors and up-regulated by estradiol via modulation of the production of biologically active TGF-beta 2 by glioblastoma cells leaving total activatable TGF-beta 2 unaffected. No such modulation is functional for the TGF-beta-independent pathway of immunosuppression. We conclude that the production of active TGF-beta by tumor cells is regulated at a posttranslational level by the coordinated action of several proteolytic enzymes.

Topics: Animals; Cell Line; Dexamethasone; Estradiol; Glioma; Immune Tolerance; In Vitro Techniques; Lymphocyte Activation; Melanoma, Experimental; Mice; Ovalbumin; Protease Inhibitors; T-Lymphocytes; Transforming Growth Factor beta; Tumor Cells, Cultured; Tunicamycin