Design Of New Vaccination Strategies Research Articles

A Critical Role of CD40 and CD70 Signaling in Conventional Type 1 Dendritic Cells in Expansion and Antitumor Efficacy of Adoptively Transferred Tumor-Specific T Cells

In vivo expansion of adoptively transferred CD8+ T cells is a critical determinant of successful adoptive T cell therapy. Emerging evidence indicates Batf3-dependent conventional type 1 dendritic cells (cDC1s) rarely found within the tumor myeloid compartment are crucial for effector T cell recruitment to the tumor microenvironment. However, the role of cDC1s in expansion of tumor-specific CD8+ T cells remains unclear. In this article, we addressed the role of cDC1s and their costimulatory molecules, CD40, CD70, and CD80/CD86, in expansion and antitumor efficacy of adoptively transferred in vitro-primed CD8+ T cells recognizing nonmutated tumor-associated self-antigens. We found that TLR/CD40-mediated expansion and antitumor efficacy of adoptively transferred tumor-specific CD8+ T cells were abrogated in Batf3-/- mice. Further mechanistic studies using mixed bone marrow chimeric mice identified that CD40 and CD70 but not CD80/CD86 signaling in cDC1s played a critical role in expansion and antitumor efficacy of adoptively transferred CD8+ T cells. Moreover, induction and activation of cDC1s by administration of FMS-like tyrosine kinase 3 ligand (Flt3L) and TLR/CD40 agonists augmented expansion of adoptively transferred CD8+ T cells, delayed tumor growth, and improved survival. These findings reveal a key role for CD40 and CD70 signaling in cDC1s and have major implications for the design of new vaccination strategies with adoptive T cell therapy.

The Molecular Interactions of ZIKV and DENV with the Type-I IFN Response

Zika Virus (ZIKV) and Dengue Virus (DENV) are related viruses of the Flavivirus genus that cause significant disease in humans. Existing control measures have been ineffective at curbing the increasing global incidence of infection for both viruses and they are therefore prime targets for new vaccination strategies. Type-I interferon (IFN) responses are important in clearing viral infection and for generating efficient adaptive immune responses towards infection and vaccination. However, ZIKV and DENV have evolved multiple molecular mechanisms to evade type-I IFN production. This review covers the molecular interactions, from detection to evasion, of these viruses with the type-I IFN response. Additionally, we discuss how this knowledge can be exploited to improve the design of new vaccine strategies.

Approaches to Improve Chemically Defined Synthetic Peptide Vaccines.

Progress made in peptide-based vaccinations to induce T-cell-dependent immune responses against cancer has invigorated the search for optimal vaccine modalities. Design of new vaccine strategies intrinsically depends on the knowledge of antigen handling and optimal epitope presentation in both major histocompatibility complex class I and -II molecules by professional antigen-presenting cells to induce robust CD8 and CD4 T-cell responses. Although there is a steady increase in the understanding of the underlying mechanisms that bridges innate and adaptive immunology, many questions remain to be answered. Moreover, we are in the early stage of exploiting this knowledge to clinical advantage. Several adaptations of peptide-based vaccines like peptide-adjuvant conjugates have been explored and showed beneficial outcomes in preclinical models; but in the clinical trials conducted so far, mixed results were obtained. A major limiting factor to unravel antigen handling mechanistically is the lack of tools to efficiently track peptide vaccines at the molecular and (sub)cellular level. In this mini-review, we will discuss options to develop molecular tools for improving, as well as studying, peptide-based vaccines.

Aluminum adjuvant potentiates gilthead seabream immune responses but induces toxicity in splenic melanomacrophage centers

A key goal of a successful vaccine formulation is the strong induction of persistent protective immune responses without producing side-effects. Adjuvants have been proved to be successful in several species at inducing increased immune responses against poorly immunogenic antigens. Fish are not the exception and promising results of adjuvanted vaccine formulations in many species are needed. In this study, over a period of 300 days, we characterized the apparent damage and immune response in gilthead seabream immunized by intraperitoneal injection with the model antigen keyhole limpet hemocyanin (KLH) alone or formulated with Montanide ISA water-in-oil (761 or 763), or Imject™ aluminum hydroxide (aluminium), as adjuvants. Throughout the trial, external tissue damage was examined visually, but no change was observed. Internally, severe adhesions, increased fat tissue, and hepatomegaly were recorded, but, without impairing animal health. At 120 days post priming (dpp), histopathological evaluations of head-kidney, spleen and liver revealed the presence of altered melanomacrophage centers (MMC) in HK and spleen, but not in liver. Surprisingly, in all aluminium treated fish, classical stains unmasked a toxic effect on splenic-MMC, unequivocally characterized by a strong cell depletion. Furthermore, at 170 dpp transmission electron microscopy confirmed this data. Paradoxically, at the same time powerful immune responses were recorded in most vaccinated groups, including the aluminium treatment. Whatever the case, despite the observed adhesions and MMC depletion, fish physiology was not affected, and most side-effects were resolved after 300 dpp. Therefore, our data support adjuvant inclusion, but strongly suggest that use of aluminium must be further explored in detail before it might benefit the rational design of new vaccination strategies in aquaculture.

Oil-in-Water Emulsion MF59 Increases Germinal Center B Cell Differentiation and Persistence in Response to Vaccination.

Induction of persistent protective immune responses is a key attribute of a successful vaccine formulation. MF59 adjuvant, an oil-in-water emulsion used in human vaccines, is known to induce persistent high-affinity functional Ab titers and memory B cells, but how it really shapes the Ag-specific B cell compartment is poorly documented. In this study, we characterized the Ab- and Ag-specific B cell compartment in wild-type mice immunized with HlaH35L, a Staphylococcus aureus Ag known to induce measurable functional Ab responses, formulated with MF59 or aluminum salts, focusing on germinal centers (GC) in secondary lymphoid organs. Taking advantage of single-cell flow cytometry analyses, HlaH35L-specific B cells were characterized for the expression of CD38 and GL-7, markers of memory and GC, respectively, and for CD80 and CD73 activation markers. We demonstrated that immunization with MF59-, but not aluminum salt-adjuvanted HlaH35L, induced expanded Ag-specific CD73(+)CD80(-) GC B cells in proximal- and distal-draining lymph nodes, and promoted the persistence of GC B cells, detected up to 4 mo after immunization. In addition to increasing GC B cells, MF59-adjuvanted HlaH35L also increased the frequency of T follicular helper cells. This work extends previous knowledge regarding adaptive immune responses to MF59-adjuvanted vaccines, and, to our knowledge, for the first time an adjuvant used in human licensed products is shown to promote strong and persistent Ag-specific GC responses that might benefit the rational design of new vaccination strategies.

Vaccine-mediated B cell responses to Staphylococcus aureus alpha-Hemolysin (Hla) and effect of different boosting intervals on functional antibodies (VAC7P.979)

Abstract Primary exposure to an antigen generates, along with antibody-secreting cells (ASCs), a heterogeneous B-cell memory compartment that changes over time and that may respond in different ways when re-encountering the cognate antigen. The goal of this study is to characterize B-cell responses after priming and the effect of different boosting intervals on the differentiation and function of ASCs and memory B cells. We used an immunization strategy based on the Hla protein from S. aureus, adjuvanted with Alum, as it was previously reported to induce protective antibodies in several animal infection models. In this study we performed a time course analysis following one or two immunizations, two weeks apart. Mice immunized twice had increased magnitude and quality of the Hla-specific humoral responses compared to mice immunized once. Increasing the boosting interval from two weeks to 1 month or 4 months, Hla-specific humoral responses increased in term of total IgG, affinity, and Hla-neutralizing titers. Hla-specific ASCs and memory B cells persisted for 4 months after the last immunization. We recently set up a method to identify Hla-specific B cells by flow cytometry (FACS).In the future we intend to further characterize their phenotype and to extend these analyses to Hla-specific memory B cells induced by different adjuvant formulations. This work will provide new insights in the memory B-cell compartment that might benefit the design of new vaccination strategies.

Vaccine-mediated B cells responses to S. aureus hemolysin, and effect of different boosting intervals on functional humoral responses

Event Abstract Back to Event Vaccine-mediated B cells responses to S. aureus hemolysin, and effect of different boosting intervals on functional humoral responses Giuseppe Lofano1*, Maria Teresa Fiorillo1 and Sylvie Bertholet2 1 University of Rome "Sapienza", Italy 2 Novartis V&D, Italy Although antibody titers are usually considered the best readout for vaccine efficacy, the importance of memory B-cell responses in conferring protection has remained controversial. Primary exposure to an antigen generates, along with antibody-secreting cells (ASCs), a heterogeneous B-cell memory compartment that changes over time and that may respond in different ways when re-encountering the cognate antigen. The goal of this study is to characterize B-cell responses after priming and the effect of different boosting intervals on the differentiation and function of ASCs and memory B cells. We used a vaccine model based on the alpha-Hemolysin (Hla) protein from Staphylococcus aureus, adjuvanted with Alum. This vaccine induced high antibody titers and was protective in sepsis and pneumonia animal infection models. We performed a time course analysis following one or two immunizations, two weeks apart: mice immunized twice had higher anti-Hla IgG titers compared to mice immunized once. ASCs measured by Elispot were increased in spleen 10 days after boosting and remained elevated in bone-marrow for at least 4 months. A similar trend was observed between the two groups when looking at the frequencies of Hla-specific memory B cells. Next steps will address the phenotypic and functional characterization of Hla-specific memory B cells to define a correlation between different boosting intervals and the protective humoral response. This work aims at providing new insights in the memory B-cell compartment that might benefit the design of new vaccination strategies. Keywords: Vaccine, B cells, S.aureus hemolysin, boosting intervals, Elispot Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Translational immunology and immune intervention Citation: Lofano G, Fiorillo M and Bertholet S (2013). Vaccine-mediated B cells responses to S. aureus hemolysin, and effect of different boosting intervals on functional humoral responses. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00019 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 Mar 2013; Published Online: 22 Aug 2013. * Correspondence: Mr. Giuseppe Lofano, University of Rome "Sapienza", Rome, Italy, giuseppe.lofano@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Giuseppe Lofano Maria Teresa Fiorillo Sylvie Bertholet Google Giuseppe Lofano Maria Teresa Fiorillo Sylvie Bertholet Google Scholar Giuseppe Lofano Maria Teresa Fiorillo Sylvie Bertholet PubMed Giuseppe Lofano Maria Teresa Fiorillo Sylvie Bertholet Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Cutting edge: CD8+ T cell priming in the absence of NK cells leads to enhanced memory responses.

It is uncertain whether NK cells modulate T cell memory differentiation. By using a genetic model that allows the selective depletion of NK cells, we show in this study that NK cells shape CD8(+) T cell fate by killing recently activated CD8(+) T cells in an NKG2D- and perforin-dependent manner. In the absence of NK cells, the differentiation of CD8(+) T cells is strongly biased toward a central memory T cell phenotype. Although, on a per-cell basis, memory CD8(+) T cells generated in the presence or the absence of NK cells have similar functional features and recall capabilities, NK cell deletion resulted in a significantly higher number of memory Ag-specific CD8(+) T cells, leading to more effective control of tumors carrying model Ags. The enhanced memory responses induced by the transient deletion of NK cells may provide a rational basis for the design of new vaccination strategies.

Wnt signaling arrests effector T cell differentiation and generates CD8+ memory stem cells

Self-renewing cell populations such as hematopoietic stem cells and memory B and T lymphocytes might be regulated by shared signaling pathways1. Wnt/β-catenin is an evolutionarily conserved pathway that promotes hematopoietic stem cell self-renewal and multipotency by limiting stem cell proliferation and differentiation2,3, but its role in the generation and maintenance of memory T cells is unknown. We found that the induction of Wnt/β-catenin signaling using inhibitors of glycogen-sythase-kinase-3β or the Wnt protein family member, Wnt3a, arrested CD8+ T cell development into effector cells. By blocking T-cell differentiation, Wnt signaling enabled the generation of CD44low, CD62Lhigh, Sca-1high, CD122high, Bcl-2high self-renewing, multipotent CD8+ memory stem cells with proliferative and anti-tumor capacities exceeding those of central and effector memory T cell subsets. These findings reveal a key role for Wnt signaling in the maintenance of stemness in mature memory CD8+ T cells and have important implications for the design of novel vaccination strategies and adoptive immunotherapies.

Extracellular and Intracellular Pattern Recognition Receptors Cooperate in the Recognition of Helicobacter pylori

Helicobacter pylori infects half of the world's population, thereby causing significant human morbidity and mortality. The mechanisms by which professional antigen-presenting cells recognize the microbe are poorly understood. Using dendritic cells (DCs) from TRIF, MyD88, TLR 2/4/7/9(-/-), and multiple double/triple/quadruple mutant mice, we characterized receptors and pathways mediating innate immune recognition of H pylori. We identified a MyD88-dependent component of the DC activation program, which was induced by surface TLRs, with TLR2 and to a minor extent also TLR4 being the exclusive surface receptors recognizing H pylori. A second MyD88-dependent component could be blocked in TLR2/4(-/-) DCs by inhibitors of endosomal acidification and depended on intracellular TLRs. We identified TLR9-mediated recognition of H pylori DNA as a principal H pylori-induced intracellular TLR pathway and further showed that H pylori RNA induces proinflammatory cytokines in a TLR-dependent manner. Microarray analysis showed complementary, redundant, and synergistic interactions between TLRs and additionally revealed gene expression patterns specific for individual TLRs, including a TLR2-dependent anti-inflammatory signature. A third component of the DC activation program was primarily composed of type I interferon-stimulated genes. This response was MyD88 and TRIF independent but was inducible by RIG-I-dependent recognition of H pylori RNA. These results provide novel comprehensive insights into the mechanisms of H pylori recognition by DCs. Understanding these processes provides a basis for the rational design of new vaccination strategies.

Chimeric hepatitis B and C viruses envelope proteins can form subviral particles: implications for the design of new vaccine strategies

The hepatitis B virus (HBV) envelope protein (S) self-assembles into subviral particles used as commercial vaccines against hepatitis B. These particles are excellent carriers for foreign epitopes, which can be inserted into the external hydrophilic loop or at the N- or C-terminal end of the HBV S protein. We show here that the N-terminal transmembrane domain (TMD) of HBV S can be replaced by the TMDs of the hepatitis C virus (HCV) envelope proteins E1 and E2, to generate fusion proteins containing the entire HCV E1 or E2 sequence that are efficiently coassembled with the HBV S into particles. This demonstrates the remarkable tolerance of the HBV S protein to sequence substitutions conserving its subviral particle assembly properties. These findings may have implications for the design of new vaccine strategies based on the use of HBV subviral particles as carriers for various transmembrane proteins and produced using the same industrial procedures that are established for the HBV vaccine.

Cytomegalovirus vaccine strategies

Background: Many patients are at high risk for serious disease caused by human cytomegalovirus (HCMV). These include solid organ and hematopoietic stem cell transplant patients, individuals with HIV infection, and newborn infants, who typically acquire the infection in utero, most commonly via transplacental transmission. Objective: The objective of this review is to provide consideration and overview of the approaches that have been explored to date in design and development of HCMV vaccines. Methods: The literature as well as the United States Patent Office database were reviewed. Conclusion: Considerable effort has been made to develop vaccines at the preclinical level but more effort is required to move these into clinical testing. There is merit in exploring novel technologies and applying these to the design of new vaccine strategies for this significant public health problem.

Characterization of immune responses elicited in mice by intranasal co-immunization with HIV-1 Tat, gp140 ΔV2Env and/or SIV Gag proteins and the nontoxicogenic heat-labile Escherichia coli enterotoxin

The development of a vaccine against HIV/AIDS capable of inducing broad humoral and cellular responses at both systemic and mucosal sites, able to stop or reduce viral infection at the portal of entry, represents the only realistic way to control the infection caused by HIV world-wide. The promising results obtained with the HIV-1 Tat-based vaccines in preclinical and clinical settings, the evidence that a broad immunity against HIV correlates with reduced viral load or virus control, as well as the availability of novel gp140 V2-loop deleted HIV-1 Env (DeltaV2Env) immunogens capable of inducing cross-reactive neutralizing antibodies, have led to the design of new vaccine strategies based on the combination of non-structural and structural proteins. In this study, we demonstrate that immunization with a biologically active HIV-1 Tat protein in combination with the oligomeric HIV-1 gp140 DeltaV2Env and/or SIV Gag proteins, delivered intranasally with the detoxified LTK63 mucosal adjuvant, whose safety has been recently shown in humans, elicits long-lasting local and systemic antibody and cellular immune responses against the co-administered antigens in a fashion similar to immune responses induced by vaccination with Tat, DeltaV2Env and Gag proteins alone. The results indicate lack of antigen interference implying that HIV-1 Tat is an optimal co-antigen for combined vaccine strategies employing DeltaV2Env and/or Gag proteins.

The Tat protein broadens T cell responses directed to the HIV-1 antigens Gag and Env: Implications for the design of new vaccination strategies against AIDS

We have previously shown that the biologically active Tat protein targets and efficiently enters dendritic cells, and increases the proteolytic activities of the immunoproteasome, thereby favoring the generation and presentation of the subdominant MHC-I binding CTL epitopes of heterologous antigens. In the present study, we demonstrate that Tat broadens in vivo epitope-specific T cell responses directed to heterologous antigens including HIV structural proteins. Specifically, co-immunization of mice with OVA and Tat proteins induces CTL responses against subdominant and cryptic OVA-derived epitopes, which are not detected in mice vaccinated with OVA alone. Similarly, mice vaccinated with the HIV-1 Gag, Env or V2-deleted Env antigens in combination with Tat show Th1-type and CTL responses directed to a larger number of T cell epitopes, as compared to mice vaccinated with these proteins in absence of Tat. In contrast, Tat did not affect Th2-type responses to these structural HIV proteins. These results indicate that Tat is not only an antigen but also a novel Th1-type adjuvant capable of broadening in vivo the spectrum of epitopes recognized by T cells, and suggest that Tat can be considered an optimal co-antigen in the development of novel vaccination strategies against AIDS.

Antigenic sites of foot-and-mouth disease virus (FMDV): an analysis of the specificities of anti-FMDV antibodies after vaccination of naturally susceptible host species.

Of the known neutralizing antigenic sites of foot-and-mouth disease virus (FMDV), site 1 or A, formed in part by the G-H loop of VP1, has historically been considered immunodominant because of evidence implicating its importance in the induction of a protective immune response. However, no systematic study has been done to determine the relative importance of the various specificities of antibodies against the known neutralizing antigenic sites of FMDV in the polyclonal immune response of a natural host after vaccination. In this report, we have adopted a monoclonal antibody-based competition ELISA and used antibodies specific to sites 1, 2 and 3 to provide some insight into this issue. Following vaccination of the three main target species, cattle, pigs and sheep, with an O1 serotype strain, results indicate that none of these three antigenic sites can be considered immunodominant in a polyclonal serum. Interestingly, pigs did not respond to epitopes on the carboxy terminus end of VP1 as efficiently as the ruminant species. In addition to the known sites, other as yet undefined sites might also be important in the induction of a protective immune response. Possible implications for the design of new vaccine strategies for foot-and-mouth disease are discussed.

Chimeric plant virus particles as immunogens for inducing murine and human immune responses against human immunodeficiency virus type 1.

The high-yield expression of a neutralizing epitope from human immunodeficiency virus type 1 (HIV-1) on the surface of a plant virus and its immunogenicity are presented. The highly conserved ELDKWA epitope from glycoprotein (gp) 41 was expressed as an N-terminal translational fusion with the potato virus X (PVX) coat protein. The resulting chimeric virus particles (CVPs), purified and used to immunize mice intraperitoneally or intranasally, were able to elicit high levels of HIV-1-specific immunoglobulin G (IgG) and IgA antibodies. Furthermore, the human immune response to CVPs was studied with severe combined immunodeficient mice reconstituted with human peripheral blood lymphocytes (hu-PBL-SCID). hu-PBL-SCID mice immunized with CVP-pulsed autologous dendritic cells were able to mount a specific human primary antibody response against the gp41-derived epitope. Notably, sera from both normal and hu-PBL-SCID mice showed an anti-HIV-1-neutralizing activity. Thus, PVX-based CVPs carrying neutralizing epitopes can offer novel perspectives for the development of effective vaccines against HIV and, more generally, for the design of new vaccination strategies in humans.