Tumor-Induced Suppression of CTL Expansion and Subjugation by gp96-Ig Vaccination

Sheila and David Fuente Program in Cancer Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida 33101, USA.
Cancer Research (Impact Factor: 9.33). 03/2009; 69(5):2026-33. DOI: 10.1158/0008-5472.CAN-08-3706
Source: PubMed


Established tumors suppress antitumor immune responses and induce tolerance by incompletely characterized mechanisms, and this phenomenon is an important barrier to tumor immunotherapy. Single vaccination with tumor cells expressing gp96-Ig stimulates robust expansion of tumor-specific CTLs in tumor-naïve mice and this expansion is inhibited by established tumors. Interestingly, frequent vaccinations restore antitumor immune responses in the presence of established tumors. Syngeneic EG7 tumor-bearing mice have heterogeneous responses to frequent vaccination with EG7-gp96-Ig, with 32% complete responders and 68% partial responders. Comparison of responders to nonresponders revealed an inverse correlation between tumor-specific CTL expansion in the peripheral blood and tumor size. To identify immune cells and molecules associated with effective antitumor immune responses, reverse transcription-PCR arrays were performed using cells isolated from the vaccination site. ELISAs, cellular phenotyping, and tumor immunohistochemistry were also performed comparing vaccine responders to nonresponders. These data show that up-regulation of T-bet, RORgammat, IFNgamma, CCL8, CXCL9, and CXCL10 at the vaccination site are associated with vaccine-induced antitumor immunity. These data correlate with increased CTL expansion in the peripheral blood of responders, increased infiltration of responder tumors by CD8+ cells and interleukin-17+ cells, and decreased infiltration of responder tumors by CD11b+Gr-1+ cells and FoxP3+ cells. Furthermore, serum ELISAs revealed a significant elevation of transforming growth factor-beta in nonresponders as compared with responders. Interestingly, CD8+ T cells isolated from responders and nonresponders have equivalent cytotoxic activity in vitro. Taken together, our data suggest that established tumors may escape immunosurveillance by preventing clonal expansion of tumor-specific CTL without inducing anergy.


Available from: Taylor H Schreiber
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    • "A major impediment to cancer therapy is tumor-induced immunosuppression and tumor evasion of antitumor immune responses, which ultimately render the host tolerant to tumor-associated antigens (Goldman and DeFrancesco 2009; Kirkwood et al. 2008; Wei et al. 2008; Schreiber et al. 2009). "
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    ABSTRACT: Interleukin-2 (IL-2) is one of the most successful cytokines applied in tumor immunotherapy because of its ability to stimulate potent cellular immune response. The life-threatening toxicity of vascular leak syndrome (VLS) associated with the high-dose IL-2 treatment regimen has limited its use in tumor immunotherapy. To reverse this situation, a tumor-targeted fusion protein, recombinant human TNT-IL2 (rhTNT-IL2), was generated with both the cytokine activity of IL-2 and the tumor-targeting ability of TNT antibody. TNT is a human tumor necrosis therapy monoclonal antibody capable of binding intracellular antigens which are accessible and abundant in necrotic regions of tumors. The immunotherapeutic potential of this fusion protein was tested in murine melanoma and lung cancer models, and tumor-bearing mice showed satisfied tumor regressions after rhTNT-IL2 immunotherapy. Immunohistochemical study showed a distinct penetration of IL-2 in tumors in mice treated with rhTNT-IL2, indicating its evident tumor-targeting activity. Moreover, the rhTNT-IL2 was well tolerated in cynomolgus monkeys in a 12-week long-term repeated toxicity study. These studies indicate that the targeting of IL-2 to necrotic areas of tumors might be a new approach for the immunotherapy of solid tumors.
    Applied Microbiology and Biotechnology 11/2013; 98(9). DOI:10.1007/s00253-013-5349-0 · 3.34 Impact Factor
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    • "In many of these vaccine models [7] [8] [9], glycoprotein 96 combined with certain antigen prime enhanced immunogenicity, presumably through processing and presenting the antigen to host antigen presenting cells (APCs). In the present study, we investigated whether the immunogenecity of AFP could be improved by presenting to APCs through gp96 molecules. "
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    ABSTRACT: Purposes: To study the ability of gp96 to induce specific CTL response and its protective effect against AFP- producing tumor, a recombinant vaccine alpha-fetoprotein (AFP)-glycoprotein (gp96) complex was constructed. Material/Methods: A recombinant peptide vaccine was constructed by conjugating mouse alpha-fetoprotein to glycoprotein 96. By way of intracutaneous injection, mice were primed and boosted with recombinant vaccine mAFP/gp96, whereas single mAFP or gp96 injection as controls. The ELISPOT and ELISA were used to measure the frequency of cells producing the cytokine IFN-gama in splenocytes and the level of anti-AFP antibody in serum from immunized mice respectively. In vivo tumor challenge was carried out to assess the immune effect of the recombinant vaccine. Results: By recombinant mAFP/gp96 vaccine immunization, the number of splenic cells producing IFN-gama and the level of anti-AFP antibody in serum were significantly higher in mAFP/gp96 group than those in mAFP and gp96 groups (122.50±9.30 IFN-gama spots/106 cells vs 46.40±10.32 IFN-gama spots/106 cells, 12.14±7.33 IFN-gama spots/106 cells, P<0.01; 164.52±11.22 μg/mL vs 56.32±8.23 μg/mL, 7.56±3.47 μg/mL, P< 0.01). The tumor volume in mAFP/gp96 group was significantly smaller than that in mAFP and gp96 groups (32.46±6.35 mm3 vs 384.16±11.43 mm3, 832.54±12.72 mm3, P< 0.01). Conclusions: The study further confirmed the function of glycoprotein 96s immune adjuvant. Sequential immunization with recombinant mAFP/gp96 vaccine could generate effective specific antitumor immunity on AFP-producing tumor. The recombined mAFP/gp96 vaccine may be suitable for serving as an immunotherapy for hepatocellular carcinoma.
    12/2011; 8:440–445. DOI:10.1016/j.proenv.2011.10.069
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    • "Data are representative of two independent experiments. expansion [36]. Our previous study showed that high dose (100 ␮g) of gp96 immunization could result in detrimental bystander effects on HBV-specific T cells stimulation by activation of Treg in HBVnaïve mice, indicating a balance between Treg and CTLs mediated by gp96. "
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    ABSTRACT: More than 350 million people worldwide are chronically infected with hepatitis B virus (HBV). Broad repertoire and strong magnitude of HBV-specific T cell responses are thought to play key roles for virus control and clearance. Previous studies together with ours showed that heat shock protein gp96 as adjuvant induces antigen specific T cell responses, yet little is known for its anti-viral properties. Here, we investigated the role of gp96 mediated cellular and humoral immunity in antiviral effects in HBV transgenic mice. Immunization with HBV surface (HBsAg) and core (HBcAg) antigens combined formulation along with gp96 induced robust antiviral T-cell and antibody immunity against HBsAg and HBcAg. Compared with non-immunized control, immunization with gp96 adjuvant vaccine led to decrease of serum HBs level and HBc expression in hepatocyte by 45% and 90% at maximum, respectively, and decreased serum HBV-DNA level to below or close to the detection limit 4 weeks after the last immunization, suggesting the therapeutic effect. A significant enhancement in cellular responses towards HBcAg and increased infiltration of CD8+ T cells in liver of transgenic were observed under treatment with gp96 compared with no treatment (P<0.05 or 0.01). Treatment with gp96 was capable of reducing Tregs by overall 30-40%. The superior immune responses induced with the aid of gp96 correlated with improved antiviral effect by vaccination with HBsAg and HBcAg. We conclude that gp96 may contribute to enhanced antiviral immunity in transgenic mice at least partly by Treg down-regulation. HBcAg may act as potent adjuvant for Th1 response. Our study reveals the novel property of gp96 in immune modulation and its potential use for breaking immunotolerance in immunotherapy of chronic HBV infection.
    Vaccine 05/2011; 29(37):6342-51. DOI:10.1016/j.vaccine.2011.05.008 · 3.62 Impact Factor
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