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Yvonne Paterson

Publications and source records attributed to Yvonne Paterson.

At least 19 recordsLinked to original sources
PubMed2006

In the FVB/N HER-2/neu transgenic mouse both peripheral and central tolerance limit the immune response targeting HER-2/neu induced by Listeria monocytogenes-based vaccines.

Listeria monocytogenes-based vaccines for HER-2/neu are capable of breaking tolerance in FVB/N rat HER-2/neu transgenic mice. The growth of implanted NT-2 tumors, derived from a spontaneously occurring tumor in the FVB/N HER-2/neu transgenic mouse, was significantly slower in these mice following vaccination with a series of L. monocytogenes-based vaccines for HER-2/neu. Mechanisms of T cell tolerance that exist in these transgenic mice include the absence of functional high avidity anti-HER-2/neu CD8(+) T cells and the presence of CD4(+)CD25(+) regulatory T cells. The in vivo depletion of these regulatory T cells resulted in the slowing in growth of tumors even without the treatment of mice with an anti-HER-2/neu vaccine. The average avidities of responsive CD8(+) T cells to six of the nine epitopes in HER-2/neu we examined, four of which were identified in this study, are shown here to be of a lower average avidity in the transgenic mice versus wild type FVB/N mice. In contrast, the average avidity of CD8(+) T cells to three epitopes that showed the lowest avidity in the wild-type mice did not differ between wild type and transgenic mice. This study demonstrates the ability of L. monocytogenes-based vaccines to impact upon tolerance to HER-2/neu in FVB/N HER-2/neu transgenic mice and further defines some of the aspects of tolerance in these mice.

Animals↗
PubMed2006

Adjuvant properties of listeriolysin O protein in a DNA vaccination strategy.

The use of infectious agents as vaccine adjuvants has shown utility in both prophylactic and therapeutic vaccinations. Listeria monocytogenes has been used extensively as a vaccine vehicle due to its ability to initiate both CD4(+) and CD8(+) immune responses. Previous work from this laboratory has used transgenic Listeria to deliver vaccine constructs. A chimeric protein composed of tumor antigen and a non-hemolytic variant of the Listeria protein, listeriolysin O (LLO), has demonstrated effective tumor protection beyond that of antigen alone expressed in the same system. To address the question of how fusion with LLO improves vaccine efficacy, we constructed a number of DNA plasmid vaccines to isolate this effect in the absence of other endogenous Listeria effects. Here we have analyzed the ability of these vaccines to induce the regression of previously established tumors. A vaccine strategy using DNA vaccines bearing the tumor antigen either alone or in combination with LLO in addition to plasmids encoding MIP-1alpha and GM-CSF was examined. Further, LLO was used either as a chimera or in a bicistronic construct to address the importance of fusion between these elements. Notably, the strategies employing both chimeric and bicistronic vaccines were effective in reducing tumor burden suggesting that LLO can act as an adjuvant that does not require fusion with the tumor antigen to mediate its effect.

Adjuvants, Immunologic↗
PubMed2006

A DNA prime-oral Listeria boost vaccine in rhesus macaques induces a SIV-specific CD8 T cell mucosal response characterized by high levels of alpha4beta7 integrin and an effector memory phenotype.

In this study in Rhesus macaques, we tested whether IL-12 or IL-15 in a DNA prime-oral Listeria boost amplifies the SIV-Gag-specific CD8 mucosal response. SIV-specific CD8 T cells were demonstrated in the peripheral blood (PB) in all test vaccine groups, but not the control group. SIV-Gag-specific CD8 T cells in the PB expressed alpha4beta7 integrin, the gut-homing receptor; a minor subset co-express alphaEbeta7 integrin. SIV-Gag-specific CD8 T cells were also detected in the gut tissue, intraepithelial (IEL) and lamina propria lymphocytes (LPL) of the duodenum and ileum. These cells were characterized by high levels of beta7 integrin expression and a predominance of the effector memory phenotype. Neither Il-12 nor IL-15 amplified the frequency of SIV-specific CD8 T cells in the gut. Thus, the DNA prime-oral Listeria boost strategy induced a mucosal SIV-Gag-specific CD8 T cell response characterized by expression of the alpha4beta7 integrin gut-homing receptor.

AIDS Vaccines↗
PubMed2006

Vaccination strategy determines the emergence and dominance of CD8+ T-cell epitopes in a FVB/N rat HER-2/neu mouse model of breast cancer.

The HER-2/neu oncogene has >25 HLA epitopes, yet only one FVB/N mouse CD8(+) T-cell epitope has been mapped to date. This epitope has been termed the immunodominant epitope for the FVB/N mouse, but we propose that the vaccination strategy determines the dominance of epitopes. Using a series of overlapping peptides, we have mapped another CD8(+) T-cell epitope that emerges in the FVB/N mouse following vaccination with Listeria monocytogenes-based vaccines that express fragments of HER-2/neu. Following the identification of this novel H-2K(q)-restricted epitope, we sought to compare the T-cell response to this epitope with the previously identified PDSLRDLSVF epitope. This newly identified epitope and the previously identified epitope lie within fragments contained in different vaccines, the PDSLRDLSVF epitope in Lm-LLO-EC2 and the newly identified PYNYLSTEV epitope in Lm-LLO-EC1; thus, it has been possible to compare the responses of these epitopes independent of any competing response between the epitopes. CTL analysis of individual peptide-pulsed target cells and intracellular cytokine stain for IFN-gamma produced by splenocytes from Lm-LLO-EC1 compared with Lm-LLO-EC2 vaccinated FVB/N mice shows that there is no difference between the responses generated to either of these epitopes. We also show that the avidity of the CD8(+) T cells for either of these epitopes is similar based on the concentration of peptide necessary to mediate similar levels of lysis of target cells. In addition, HER-2/neu DNA vaccination followed by CTL analysis further showed that both of these peptides can emerge as epitopes.

Amino Acid Sequence↗
PubMed2006

Effects of the tumor microenvironment on the efficacy of tumor immunotherapy.

Cancer immunotherapy utilizes vaccines targeting tumor antigens or tumor endothelium to prevent or regress tumors. Many cancer vaccines are designed to induce antigen-specific effector T cells that migrate to the tumor site. In an optimal situation, the effector T cells penetrate the tumor, release their effector molecules, induce tumor cell death and tumor regression. However, the tumor microenvironment is frequently immunosuppressive and contributes to a state of immune ignorance, impacting on the vaccine's ability to break tolerance to tumor antigen/s. This review discusses the factors in the tumor microenvironment that can affect the efficacy of cancer vaccines. In particular, the review focuses on pathways leading to effector T cell penetration of tumors or the inhibition of this process.

Animals↗
PubMed2006

Listeria monocytogenes as a vector for tumor-associated antigens for cancer immunotherapy.

As a facultative intracellular bacterium, Listeria monocytogenes has adapted to live within the cytosol of the host cell. It is actively taken up by antigen-presenting cells through phagocytosis, and as Listeria survive within these cells, it is an ideal vector for the delivery of antigens to be processed and presented through both the class I and II antigen-processing pathways. Once phagocytosed, Listeria produces virulence factors within the phagolysosome of the host cell, which allows it to break out of this organelle and live in the host cytosol. It is possible that these virulence factors can enhance the immunogenicity of tumor-associated antigens, which are poorly immunogenic. Recent progress in the development of this bacterium as a vaccine vector for tumor-associated antigens is discussed in the context of bacterial vectors in general. In several mouse models, Listeria-based vaccines have been demonstrated to be an effective method of influencing tumor growth and eliciting potent antitumor immune responses. Safety issues and the transition of Listeria into human clinical trials will also be discussed in this review.

Antigens, Neoplasm↗
PubMed2005

Fusion to Listeriolysin O and delivery by Listeria monocytogenes enhances the immunogenicity of HER-2/neu and reveals subdominant epitopes in the FVB/N mouse.

Five overlapping fragments of rat HER-2/neu have been expressed in recombinant Listeria monocytogenes. Each fragment of HER-2/neu is secreted as a fusion protein with a truncated, nonhemolytic form of listeriolysin O (LLO). Lm-LLO-EC1, Lm-LLO-EC2, and Lm-LLO-EC3 overlap the extracellular domain of HER-2/neu, whereas Lm-LLO-IC1 and Lm-LLO-IC2 span the intracellular domain. All five strains controlled the growth of established NT-2 tumors, a rat HER-2/neu-expressing tumor line derived from a spontaneously arising mammary tumor in a FVB/N HER-2/neu-transgenic mouse. The antitumor effect of each of these vaccine constructs was abrogated by the in vivo depletion of CD8(+) T cells, although only one known epitope has been defined previously and is present in Lm-LLO-EC2. Anti-HER-2/neu CTL responses were generated by each of the rLm vaccine constructs. With the use of a panel of 3T3 cell lines expressing overlapping fragments of HER-2/neu, regions of HER-2/neu with potential CD8(+) T cell epitopes have been defined. DNA vaccines expressing either a fragment or full-length HER-2/neu were constructed in LLO-fused and non-LLO-fused forms. CTL analysis of the DNA vaccines revealed a broadening in the regions of HER-2/neu recognizable as targets when the target Ag is fused to LLO. These studies show the efficacy of L. monocytogenes-based HER-2/neu vaccines in a murine model of breast cancer and also that the immunogenicity of self-Ags can be increased by fusion to LLO and delivery by L. monocytogenes revealing subdominant epitopes.

Animals↗
PubMed2005

Rhesus macaques with high levels of vaccine induced IFN-gamma producing cells better control viral set-point following challenge with SIV239.

HIV-1 specific cellular immune responses play a significant part in controlling HIV-1 viral replication and are an important component of an HIV-1 vaccine induced immune response. We reported earlier that recombinant DNA vaccine delivered intramuscularly, and recombinant Listeria monocytogenes, delivered orally induced CD8+ and CD4+ T cell immune responses in rhesus macaques and that this vaccine protocol showed partial protection against an SIV239 challenge. In this paper, we have analyzed the SIV antigen-specific immune responses at the time of challenge and during the subsequent infection course. We find that the immune status of the animals, as measured by the frequency of antigen-specific IFN-gamma secreting peripheral blood mononuclear cells, at the time of challenge correlates more strongly with viral loads at set point than peak viral loads. The correlation between the immune response and viral load was strongest early, as viral set-point was just being established and disintegrates overtime. This study demonstrates the cellular immune response to SIV at the time of challenge of a nonhuman primate is able to impact on viral set-point following SIV239 challenge. Further, this study demonstrates that as virus replicates the T cell immune response to SIV antigens induced by the vaccine is modulated by antigen encountered by immune cells during viral replication.

Animals↗
PubMed2005

DNA prime Listeria boost induces a cellular immune response to SIV antigens in the rhesus macaque model that is capable of limited suppression of SIV239 viral replication.

DNA vaccines and recombinant Listeria monocytogenes that express and secrete SIV Gag and Env antigens were combined in a nonhuman primate prime-boost immunogenicity study followed by a challenge with SIV239. We report that recombinant DNA vaccine delivered intramuscularly, and recombinant L. monocytogenes delivered orally each individually have the ability to induce CD8+ and CD4+ T cell immune responses in a nonhuman primate. Four rhesus monkeys were immunized at weeks 0, 4, 8, and 12 with the pCSIVgag and pCSIVenv DNA plasmids and boosted with SIV expressing L. monocytogenes vaccines at weeks 16, 20, and 28. Four rhesus monkeys received only the L. monocytogenes vaccines at weeks 16, 20, and 28. A final group of monkeys served as a control group. Blood samples were taken before vaccination and 2 weeks post each injection and analyzed by ELISPOT for CD4+ and CD8+ T cell responses. Moderate vaccine induced SIV-specific cellular immune responses were observed following immunization with either DNA or L. monocytogenes vectors. However, the SIV antigen-specific immune responses were significantly increased when Rhesus macaques were primed with SIV DNA vaccines and boosted with the SIV expressing L. monocytogenes vectors. In addition, the combined vaccine was able to impact SIV239 viral replication following an intrarectal challenge. This study demonstrates for the first time that oral L. monocytogenes can induce a cellular immune response in a nonhuman primate and is able to enhance the efficacy of a DNA vaccine as well as provide modest protection against SIV239 challenge.

Animals↗
PubMed2005

What is needed for effective antitumor immunotherapy? Lessons learned using Listeria monocytogenes as a live vector for HPV-associated tumors.

As a vaccine vector, Listeria monocytogenes targets the innate immune system, resulting in a cytokine response that enhances antigen-presenting cell function as well as inducing a Th1 profile. It also enhances cell-mediated immunity by targeting antigen delivery in antigen-presenting cells to both the MHC class I pathway of exogenous presentation that activates CD8 T cells and the MHC class II pathway that processes antigen endogenously and presents it to CD4 T cells. In this review, we describe the development of vaccine constructs that target the human papillomavirus 16 (HPV-16) E7 antigen, and we characterize their effects on tumor regression as well as various immune parameters both innate and adaptive. In particular, we describe the effect on tumor angiogenesis, induction of antitumor suppressor factors like CD4+CD25+ T cells and regulatory cytokines TGF-beta and IL-10, homing and infiltration of antigen-specific CD8+ T cells to the tumor, and also effects of the vaccines on antigen-presenting cells, especially focusing on dendritic cell maturation and ability to influence tumor regression. We believe that the identification of several immune parameters that correlate with antitumor efficacy, and of some that have a negative correlation, may have wider application for other cancer immunotherapeutic approaches.

Animals↗
PubMed2005

Technology evaluation: HspE7 (Stressgen).

Stressgen is developing HspE7, a recombinant fusion protein comprising the human papillomavirus (HPV) E7 antigen and the heat shock protein Hsp65 from Mycobacterium bovis, as a potential therapy for conditions associated with HPV infection. This therapy is currently undergoing phase III clinical trials.

Animals↗
PubMed2005

Listeria-based vaccines for cancer treatment.

Listeria monocytogenes is a facultative intracellular bacterium that enters professional antigen-presenting cells by active phagocytosis. As a live bacterium, it induces antigen-presenting cell maturation and strong innate immunity which may assist in the immune response to poorly immunogenic antigens, such as tumor-associated antigens. Listeria produces virulence factors that allow it to escape from the phagolysosome and colonize the cytosol of the host cell. It is thus a potent vaccine vector for the presentation of passenger antigens to the major histocompatibility complex class I and II pathways of antigen processing and presentation. Recent progress in developing this bacterium as a vaccine vector for tumor-associated antigens is reviewed. In mouse models, recombinant Listeria carrying a number of such antigens has provided therapeutic immunity directed towards established tumors. Safety issues associated with live bacterial vaccine vectors and problems to be overcome in developing Listeria as a cancer immunotherapeutic for human use are also discussed.

Animals↗
PubMed2004

Recombinant Listeria vaccines containing PEST sequences are potent immune adjuvants for the tumor-associated antigen human papillomavirus-16 E7.

Previous work in our laboratory has established that the fusion of tumor-associated antigens to a truncated form of the Listeria monocytogenes virulence factor listeriolysin O (LLO) enhances the immunogenicity and antitumor efficacy of the tumor antigen when delivered by Listeria or by vaccinia. LLO contains a PEST sequence at the NH(2) terminus. These sequences, which are found in eukaryotic proteins with a short cellular half-life, target proteins for degradation in the ubiquitin-proteosome pathway. To investigate whether the enhanced immunogenicity conferred by LLO is due to the PEST sequence, we constructed new Listeria recombinants that expressed the HPV-16 E7 antigen fused to LLO, which either contained or had been deleted of this sequence. We then compared the antitumor efficacy of this set of vectors and found that Listeria expressing the fusion protein LLO-E7 or PEST-E7 were effective at regressing established macroscopic HPV-16 immortalized tumors in syngeneic mice. In contrast, Listeria recombinants expressing E7 alone or E7 fused to LLO from which the PEST sequence had been genetically removed could only slow tumor growth. Because CD8(+) T cell epitopes are generated in the ubiquitin-proteosome pathway, we also investigated the ability of the vaccines to induce E7-specific CD8(+) T cells in the spleen and to generate E7-specific tumor-infiltrating lymphocytes. A strong correlation was observed between CD8(+) T-cell induction and tumor homing and the antitumor efficacy of the Listeria-E7 vaccines. These findings suggest a strategy for the augmentation of tumor antigen-based immunotherapeutic strategies that may be broadly applicable.

Amino Acid Sequence↗
PubMed2004

Tumor sensitivity to IFN-gamma is required for successful antigen-specific immunotherapy of a transplantable mouse tumor model for HPV-transformed tumors.

PURPOSE: Many human tumors lose responsiveness to IFN-gamma, providing a possible mechanism for the tumor to avoid immune recognition and destruction. Here we investigate the importance of tumor responsiveness to IFN-gamma in the successful immunotherapy of TC1 tumors that were immortalized with human papillomavirus proteins E6 and E7. METHODS: To investigate the role of IFN-gamma in vivo, we constructed a variant of TC1, TC1.mugR, that is unresponsive to IFN-gamma due to overexpression of a dominant negative IFN-gamma receptor. RESULTS: Using recombinant Listeria monocytogenes that express HPV-16 E7 (Lm-LLO-E7) to stimulate an antitumor response, we demonstrate that sensitivity to IFN-gamma is required for therapeutic efficacy in that Lm-LLO-E7 induces regression of TC1 tumors but not TC1.mugR. In addition, we show that tumor sensitivity to IFN-gamma is not required for inhibition of tumor angiogenesis by Lm-LLO-E7 or for trafficking of CD4+ and CD8+ T cells to the tumor. However, it is required for penetration of lymphocytes into the tumor mass in vivo. CONCLUSIONS: Our findings identify a role for IFN-gamma in immunity to TC1 tumors and show that loss of tumor responsiveness to IFN-gamma poses a challenge to antigen-based immunotherapy.

Animals↗
PubMed2004

The ability of two Listeria monocytogenes vaccines targeting human papillomavirus-16 E7 to induce an antitumor response correlates with myeloid dendritic cell function.

Previous work from our laboratory has shown that Lm-LLO-E7 induces complete regression of approximately 75% of established TC-1 tumors, whereas Lm-E7 only slows the growth of such tumors. In this study, we examine the effects of Lm-LLO-E7 vs Lm-E7 on APCs. We hypothesize that the difference in antitumor efficacy of the two vaccines is due to the ability of each of these vectors to render immature dendritic cells (DCs) effective APCs in terms of MHC class II or costimulatory molecule expression. We also examine the ability of these vectors to stimulate cytokine production by DCs. Both vectors induced IL-12 and TNF-alpha, but only Lm-LLO-E7 induced IL-2 production by DCs. Lm-LLO-E7 also induced significantly higher levels of MHC class II molecules, CD40, and B7 costimulatory molecules (CD86, B7-H1, and B7-DC) on DCs than Lm-E7. Interestingly, a shift of CD11c(+) cells from CD86(low) to CD86(high) is observed post-Lm-LLO-E7 infection. A similar shift is also observed for B7-H1 and B7-DC molecules. Moreover, Lm-LLO-E7, but not Lm-E7-pulsed DCs, stimulate naive T cell proliferation. These results indicate that Lm-LLO-E7 is more effective than Lm-E7 at inducing DC maturation. This effect is independent of the E7 Ag, because Lm-LLO-NP, and a mixture of Lm-LLO-NP and Lm-E7 induce the same changes in DC phenotype as Lm-LLO-E7. Taken together, the changes in DC expression correlate well with the differences in antitumor efficacy between these two vaccines.

Animals↗
PubMed2004

Improved protection conferred by vaccination with a recombinant vaccinia virus that incorporates a foreign antigen into the extracellular enveloped virion.

Recombinant poxviruses have shown promise as vaccine vectors. We hypothesized that improved cellular immune responses could be developed to a foreign antigen by incorporating it as part of the extracellular enveloped virion (EEV). We therefore constructed a recombinant vaccinia virus that replaced the cytoplasmic domain of the B5R protein with a test antigen, HIV-1 Gag. Mice immunized with the virus expressing Gag fused to B5R had significantly better primary CD4 T-cell responses than recombinant virus expressing HIV-Gag from the TK-locus. The CD8 T-cell responses were less different between the two groups. Importantly, although we saw differences in the immune response to the test antigen, the vaccinia virus-specific immune responses were similar with both constructs. When groups of vaccinated mice were challenged 30 days later with a recombinant Listeria monocytogenes that expresses HIV-Gag, mice inoculated with the virus that expresses the B5R-Gag fusion protein had lower colony counts of Listeria in the liver and spleen than mice vaccinated with the standard recombinant. Thus, vaccinia virus expressing foreign antigen incorporated into EEV may be a better vaccine strategy than standard recombinant vaccinia virus.

Animals↗
PubMed2004

Regression of HPV-positive tumors treated with a new Listeria monocytogenes vaccine.

BACKGROUND: Human papillomavirus (HPV) has been implicated in the pathogenesis of 15% to 23% of head and neck squamous cell carcinomas as well as most oropharyngeal carcinomas. The viral oncoproteins E6 and E7 are expressed in HPV-positive tumor cells and therefore provide ideal targets for tumor immunotherapy. Because of its unique ability to induce a cellular immune response, the intracellular bacteria Listeria monocytogenes has been studied as a potential HPV-positive tumor vaccine. OBJECTIVE: To present a new recombinant strain of L monocytogenes that is effective in treating HPV-positive tumors in a murine model. DESIGN: A new recombinant L monocytogenes vaccine, Lm-ActA-E7, was designed by transforming an attenuated Listeria strain with an E7 expression cassette. The cassette consists of the HPV-16 E7 sequence fused to the Listeria protein ActA. The resultant strain of bacteria secretes E7 antigen as a fusion protein with ActA. METHODS: Tumors were established in C57BL/6 mice with a syngeneic HPV-positive cell line prior to treatment with vaccine. INTERVENTION: The Lm-ActA-E7 vaccine was administered intraperitoneally to the mice 5 days after tumors were established. A booster dose was administered 7 days after the first dose. Tumor progression was measured in 2 dimensions periodically after the vaccination. RESULTS: In C57BL/6 mice, the administration of Lm-ActA-E7 caused the complete regression of HPV-positive tumors in 6 of 8 mice tested. A cytotoxic T-lymphocyte assay revealed that administration of the vaccine caused the generation of cytotoxic T cells specific for E7. CONCLUSION: Our results demonstrate the ability of a new Listeria-based vaccine to generate a specific antitumor T-cell response and cause the regression of HPV-positive tumors in a murine model.

Animals↗