Immunization with genetically attenuated P52-deficient Plasmodium berghei sporozoites induces a long-lasting effector memory CD8+ T cell response in the liver

Background

The induction of sterile immunity and long lasting protection against malaria has been effectively achieved by immunization with sporozoites attenuated by gamma-irradiation or through deletion of genes. For mice immunized with radiation attenuated sporozoites (RAS) it has been shown that intrahepatic effector memory CD8⁺ T cells are critical for protection. Recent studies have shown that immunization with genetically attenuated parasites (GAP) in mice is also conferred by liver effector memory CD8⁺ T cells.

Findings

In this study we analysed effector memory cell responses after immunization of GAP that lack the P52 protein. We demonstrate that immunization with p52 ^-GAP sporozoites also results in a strong increase of effector memory CD8⁺ T cells, even 6 months after immunization, whereas no specific CD4⁺ effector T cells response could be detected. In addition, we show that the increase of effector memory CD8⁺ T cells is specific for the liver and not for the spleen or lymph nodes.

Conclusions

These results indicate that immunization of mice with P. berghei p52 ^-GAP results in immune responses that are comparable to those induced by RAS or GAP lacking expression of UIS3 or UIS4, with an important role implicated for intrahepatic effector memory CD8⁺ T cells. The knowledge of the mediators of protective immunity after immunization with different GAP is important for the further development of vaccines consisting of genetically attenuated sporozoites.     

The mucosal immune system: From dentistry to vaccine development

The oral cavity is the beginning of the aero-digestive tract, which is covered by mucosal epithelium continuously under the threat of invasion of pathogens, it is thus protected by the mucosal immune system. In the early phase of our scientific efforts for the demonstration of mucosal immune system, dental science was one of major driving forces due to their foreseeability to use oral immunity for the control of oral diseases. The mucosal immune system is divided functionally into, but interconnected inductive and effector sites. Intestinal Peyer’s patches (PPs) are an inductive site containing antigen-sampling M cells and immunocompetent cells required to initiate antigen-specific immune responses. At effector sites, PP-originated antigen-specific IgA B cells become plasma cells to produce polymeric IgA and form secretory IgA by binding to poly-Ig receptor expressed on epithelial cells for protective immunity. The development of new-generation mucosal vaccines, including the rice-based oral vaccine MucoRice, on the basis of the coordinated mucosal immune system is a promising strategy for the control of mucosal infectious diseases.     

Tumor-infiltrating effector cells of α-galactosylceramide-induced antitumor immunity in metastatic liver tumor

Background  

α-Galactosylceramide (α-GalCer) can be presented by CD1d molecules of antigen-presenting cells, and is known to induce a potent NKT cell-dependent cytotoxic response against tumor cells. However, the main effector cells in α-GalCer-induced antitumor immunity are still controversial.     

Antigenized antibodies expressing Vbeta8.2 TCR peptides immunize against rat experimental allergic encephalomyelitis

BACKGROUND: Immunity against the T cell receptor (TCR) is considered to play a central role in the regulation of experimental allergic encephalomyelitis (EAE), a model system of autoimmune disease characterized by a restricted usage of TCR genes. Methods of specific vaccination against the TCR of pathogenetic T cells have included attenuated T cells and synthetic peptides from the sequence of the TCR. These approaches have led to the concept that anti-idiotypic immunity against antigenic sites of the TCR, which are a key regulatory element in this disease. METHODS: The present study in the Lewis rat used a conventional idiotypic immunization based on antigenized antibodies expressing selected peptide sequences of the Vbeta8.2 TCR (93ASSDSSNTE101 and 39DMGHGLRLIHYSYDVNSTEKG59). RESULTS: The study demonstrates that vaccination with antigenized antibodies markedly attenuates, and in some instances, prevents clinical EAE induced with the encephalitogenic peptide 68GSLPQKSQRSQDENPVVHF88 in complete Freunds' adjuvant (CFA). Antigenized antibodies induced an anti-idiotypic response against the Vbeta8.2 TCR, which was detected by ELISA and flowcytometry. No evidence was obtained of a T cell response against the corresponding Vbeta8.2 TCR peptides. CONCLUSIONS: The results indicate that antigenized antibodies expressing conformationally-constrained TCR peptides are a simple means to induce humoral anti-idiotypic immunity against the TCR and to vaccinate against EAE. The study also suggests the possibility to target idiotypic determinants of TCR borne on pathogenetic T cells to vaccinate against disease.     

A novel method to identify and characterise peptide mimotopes of heat shock protein 70-associated antigens

The heat shock protein, Hsp70, has been shown to play an important role in tumour immunity. Vaccination with Hsp70-peptide complexes (Hsp70-PCs), isolated from autologous tumour cells, can induce protective immune responses. We have developed a novel method to identify synthetic mimic peptides of Hsp70-PCs and to test their ability to activate T-cells. Peptides (referred to as "recognisers") that bind to Hsp70-PCs from the human breast carcinoma cell line, MDA-MB-231, were identified by bio-panning a random peptide M13 phage display library. Synthetic recogniser peptides were subsequently used as bait in a reverse bio-panning experiment to identify potential Hsp70-PC mimic peptides. The ability of the recogniser and mimic peptides to prime human lymphocyte responses against tumour cell antigens was tested by stimulating lymphocytes with autologous peptide-loaded monocyte-derived dendritic cells (DCs). Priming and subsequent stimulation with either the recogniser or mimic peptide resulted in interferon-γ (IFN-γ) secretion by the lymphocytes. Furthermore, DCs loaded with Hsp70, Hsp70-PC or the recogniser or the mimic peptide primed the lymphocytes to respond to soluble extracts from breast cells. These results highlight the potential application of synthetic peptide-mimics of Hsp70-PCs, as modulators of the immune response against tumours.     

Design of Gold Nanoparticles in Dendritic Cell‐Based Vaccines

The design of effective cancer vaccines must be able to activate dendritic cells (DCs) of the innate immune system in order to induce immunity to pathogens and cancer. DCs patrol the body and once they encounter antigens, they orchestrate a complex mechanism of events and signals that can alert the adaptive immune system to action. However, DC‐based vaccines remain a challenge in part because the source and quality of antigens, the DC targeting molecule, type of adjuvant, and delivery vehicle must be optimized to induce a robust immune response. Gold nanoparticles (AuNPs) have now entered clinical trials as carriers due to their ease of functionalization with antigens, adjuvants, and targeting molecules. This progress report discusses how AuNPs can influence DC activation and maturation, as well as their potential impact on T helper (Th) differentiation. Ultimately, successful AuNP‐based DC vaccines are able to induce phagocytosis, activation/maturation, migration, T cell costimulation, and cytokine secretion, which is named AuNP‐induced DC tuning (AuNP‐DC tuning). Although at its infancy, understanding the processes of AuNP‐DC tuning will give a better understanding of how best to engineer AuNPs and will redefine the next generation of DC‐based vaccines.     

Antigenized antibodies expressing Vβ8.2 TCR peptides immunize against rat experimental allergic encephalomyelitis

Background  

Immunity against the T cell receptor (TCR) is considered to play a central role in the regulation of experimental allergic encephalomyelitis (EAE), a model system of autoimmune disease characterized by a restricted usage of TCR genes. Methods of specific vaccination against the TCR of pathogenetic T cells have included attenuated T cells and synthetic peptides from the sequence of the TCR. These approaches have led to the concept that anti-idiotypic immunity against antigenic sites of the TCR, which are a key regulatory element in this disease.     

Analysis of the toxicity of gold nano particles on the immune system: effect on dendritic cell functions

The effect of manufactured gold nanoparticles (NPs) on the immune system was analysed through their ability to perturb the functions of dendritic cells (DCs), a major actor of both innate and acquired immune responses. For this purpose, DCs were produced in culture from mouse bone marrow progenitors. The analysis of the viability of the cells after their incubation in the presence of gold NPs shows that these NPs are not cytotoxics even at high concentration. Furthermore, the phenotype of the DC is unchanged after the addition of NPs, indicating that there is no activation of the DC. However, the analysis of the cells at the intracellular level reveals important amounts of gold NPs amassing in endocytic compartments. Furthermore, the secretion of cytokines is significantly modified after such internalisation indicating a potential perturbation of the immune response.     

Recognition and elimination of diversified pathogens in insect defense systems

Summary The elimination of infectious non-self by the host defense systems of multicellular organisms requires a variety of recognition and effector molecules. The diversity is generated in somatic cells or encoded in the germ-line. In adaptive immunity in jawed vertebrates, the diversity of immunoglobulins and antigen receptors is generated by gene rearrangements in somatic cells. In innate immunity, various effector molecules and pattern recognition receptors, such as antimicrobial peptides and peptidoglycan recognition proteins, are encoded in the germ-line of multicellular organisms, including insects and jawed vertebrates. In the present review, we discuss how insect host defense systems recognize and eliminate a multitude of microbes via germ-line-encoded molecules, including recent findings that a Drosophila member of the immunoglobulin superfamily is extensively diversified by alternative splicing in somatic immune cells and participates in the elimination of bacteria.     

Improved generation of anti-tumor immunity by antigen dose limitation

Background  

The malignant cells of cutaneous T cell lymphoma (CTCL) display immunogenic peptides derived from the clonal T cell receptor (TCR) providing an attractive model for refinement of anti-tumor immunization methodology. To produce a clinically meaningful anti-tumor response, induction of cytotoxic anti-CTCL cells must be maximized while suppressive T regulatory cells (Treg) should be minimized. We have demonstrated that engulfment of apoptotic CTCL cells by dendritic cells (DC) can lead to either CD8 anti-CTCL responses or immunosuppressive Treg induction. Treg generation is favored when the number of apoptotic cells available for ingestion is high.     

Dendritic cells: In the forefront of immunopathogenesis and vaccine development - A review

Dendritic cellls (DCs) comprise an essential component of the immune system. These cells, as antigen presenting cells (APCs) to na?ve T cells, are crucial in the initiation of antigen specific immune responses. In the past years, several DC subsets have been identified in different organs which exert different effects in order to elicit adaptive immune responses. Thus, identification of such DC subsets has led to a better understanding of their distribution and function in the body. In this review, several key properties of the immunobiology, immunopathogenesis and vaccine strategies using DCs will be discussed.     

Dendritic cells: In the forefront of immunopathogenesis and vaccine development – A review

Dendritic cellls (DCs) comprise an essential component of the immune system. These cells, as antigen presenting cells (APCs) to na?ve T cells, are crucial in the initiation of antigen specific immune responses. In the past years, several DC subsets have been identified in different organs which exert different effects in order to elicit adaptive immune responses. Thus, identification of such DC subsets has led to a better understanding of their distribution and function in the body. In this review, several key properties of the immunobiology, immunopathogenesis and vaccine strategies using DCs will be discussed.     

Modeling the Dynamics of T-Cell Development in the Thymus

The thymus hosts the development of a specific type of adaptive immune cells called T cells. T cells orchestrate the adaptive immune response through recognition of antigen by the highly variable T-cell receptor (TCR). T-cell development is a tightly coordinated process comprising lineage commitment, somatic recombination of Tcr gene loci and selection for functional, but non-self-reactive TCRs, all interspersed with massive proliferation and cell death. Thus, the thymus produces a pool of T cells throughout life capable of responding to virtually any exogenous attack while preserving the body through self-tolerance. The thymus has been of considerable interest to both immunologists and theoretical biologists due to its multi-scale quantitative properties, bridging molecular binding, population dynamics and polyclonal repertoire specificity. Here, we review experimental strategies aimed at revealing quantitative and dynamic properties of T-cell development and how they have been implemented in mathematical modeling strategies that were reported to help understand the flexible dynamics of the highly dividing and dying thymic cell populations. Furthermore, we summarize the current challenges to estimating in vivo cellular dynamics and to reaching a next-generation multi-scale picture of T-cell development.     

DNA vaccine containing the mycobacterial hsp65 gene prevented insulitis in MLD-STZ diabetes

Background  

Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases.     

Detection of Cancer Cell Death Mediated by a Synthetic Granzyme B-like Peptide Fluorescent Conjugate and the same Peptide Binding in Bacteria

Granzyme-mediated apoptosis, supported by pore-forming perforin, plays an important role in CD8+ T lymphocytes (CTL)-dependent cellular immunity protection against both cancer and viral infection. Quantitative and qualitative problems with CTL are potential contributing factors to disease progression. The feasibility of developing CTL-independent cellular immunity is desired but must first overcome the barrier of CTL-independent target cell recognition. Granzyme B with its strong pro-apoptotic activity in many different target cells is investigated for use in the CTL-independent cellular immunity approach, and granzyme B or its bioactive peptides without the enzymatic activity are more desirable for use. Native granzyme B with enzymatic activity is usually investigated in cancer cells for its mediation of apoptosis by detection of DNA fragmentation. Detection of cell death mediated by such peptides in cancer cells is needed to demonstrate the potential therapeutic purposes. We show with never-before-seen microscopic images using fluorescence microscopy that a synthetic granzyme B-like peptide fluorescent conjugate (GP1R) can: 1) mediate cell death of different cancer cells via membrane extrusion, 2) bind to constitutively expressed binding targets in different cancer cells and bacteria, and 3) promote bacterial phagocytosis. The putative binding targets may serve as a universal pathologic biomarker detectable by GP1R. Our data taken together demonstrate the potential applications of GP1R for use in CTL-independent target cell recognition and target cell death induction. It may lead to development of rapid targeted detection and new treatment of cancer, viral and bacterial infections. The new treatment may show mutual benefits for two or more diseases.     

CTLA-4 blockade during dendritic cell based booster vaccination influences dendritic cell survival and CTL expansion

Dendritic cells (DCs) are potent antigen-presenting cells and critical for the priming of CD8+ T cells. Therefore the use of these cells as adjuvant cells has been tested in a large number of experimental and clinical vaccination studies, in particular cancer vaccine studies. A number of protocols are emerging that combine vaccination with CTL expanding strategies, such as e.g. blockade of CTLA-4 signalling. On the other hand, the lifespan and in vivo survival of therapeutic DCs have only been addressed in a few studies, although this is of importance for the kinetics of CTL induction during vaccination. We have previously reported that DCs loaded with specific antigens are eliminated by antigen specific CTLs in vivo and that this elimination affects the potential for in vivo CTL generation. We now show that CTLA-4 blockade increases the number of DC vaccine induced LCMV gp33 specific CTLs and the lysis of relevant in vivo targets. However, the CTLA-4 blockage dependent expansion of CTLs also affect DC survival during booster DC injections and our data suggest that during a booster DC vaccine, the largest increase in CTL levels is already obtained during the first vaccination.     

Fluorescent Probe ABM and Estimation of Immune State in Patients with Different Pathologies (Review Article)

The fluorescent probe ABM (3-aminobenzanthrone derivative) one of the fluorescent probes synthesized in Riga Technical University proved to be an excellent, independent model for studying cell membranes. In our work we have investigated the possibility of using the fluorescent probe ABM for detection of immune state in patients with different pathologies. There is a strong correlation among all studied ABM spectral parameters, immunological characteristics, clinical and laboratory investigations of the all observed patients groups. The obtained results suggest that ABM spectral parameters in cell suspension reflect the alterations of the cellular mechanisms of immunity. Therefore fluorescent method could be used as preliminary screening test in immune diagnostics instead of more expensive, time consuming methods (subset detection, radioisotope method etc.) used as routine in clinics. Spectral parameters of ABM reflect a wide range of interrelated (interdependent) characteristics of cells (physico-chemical state and microviscosity of membrane, proliferating and lipid metabolic activity of cells, distribution of cells among subsets). The observed change of the studied parameters reflects alterations of the cellular mechanisms of immunity which is a main focus for its application as preliminary screening test in immune diagnostics. The fluorescence based method is sensitive, less expensive and time consuming, technically simple and convenient.