Cellular and molecular mechanisms of memory T-cell survival

Tuberculosis Vaccines and T Cell Immune Memory

Tuberculosis (TB) remains a major infectious disease partly due to the lack of an effective vaccine. Therefore, developing new and more effective TB vaccines is crucial for controlling TB. Mycobacterium tuberculosis (M. tuberculosis) usually parasitizes in macrophages; therefore, cell-mediated immunity plays an important role. The maintenance of memory T cells following M. tuberculosis infection or vaccination is a hallmark of immune protection. This review analyzes the development of memory T cells during M. tuberculosis infection and vaccine immunization, especially on immune memory induced by BCG and subunit vaccines. Furthermore, the factors affecting the development of memory T cells are discussed in detail. The understanding of the development of memory T cells should contribute to designing more effective TB vaccines and optimizing vaccination strategies.

Nanoparticle-Based Immunotherapy for Reversing T-Cell Exhaustion

T-cell exhaustion refers to a state of T-cell dysfunction commonly observed in chronic infections and cancer. Immune checkpoint molecules blockading using PD-1 and TIM-3 antibodies have shown promising results in reversing exhaustion, but this approach has several limitations. The treatment of T-cell exhaustion is still facing great challenges, making it imperative to explore new therapeutic strategies. With the development of nanotechnology, nanoparticles have successfully been applied as drug carriers and delivery systems in the treatment of cancer and infectious diseases. Furthermore, nanoparticle-based immunotherapy has emerged as a crucial approach to reverse exhaustion. Here, we have compiled the latest advances in T-cell exhaustion, with a particular focus on the characteristics of exhaustion that can be targeted. Additionally, the emerging nanoparticle-based delivery systems were also reviewed. Moreover, we have discussed, in detail, nanoparticle-based immunotherapies that aim to reverse exhaustion, including targeting immune checkpoint blockades, remodeling the tumor microenvironment, and targeting the metabolism of exhausted T cells, etc. These data could aid in comprehending the immunopathogenesis of exhaustion and accomplishing the objective of preventing and treating chronic diseases or cancer.

Phenotypic and Functional Characterization of Memory CD4+ and CD8+ T Cells After Antigenic Stimulation

The encounter of T cells with the antigen through the interaction of T cell receptors with peptides and major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APCs) can generate effector response and memory T cells. Memory T cells developed following infections or vaccination may persist, leading to the generation of a specific immune response upon reexposure to the same pathogen through rapid clonal proliferation and activation of effector functions. T cell memory subsets can be identified based on the expression of several membrane markers such as CCR7, CD27, and CD45RA. Using fluorescent antibodies against these markers and a flow cytometer, it is possible to perform immunophenotyping via the analysis of cell surface expression of proteins by different subpopulations such as the subsets of naïve, effector, and memory T cells as well as via the analysis of functional markers that further characterize each sample. Intracellular cytokine staining allows for the evaluation of intracellular proteins expressed in T cells in response to antigenic stimulation. This chapter presents the phenotypic and functional characterization of memory T cells after antigenic stimulation, detailing the procedures for identifying intracellular and surface protein markers. Herein, we review and present a reproducible standardized protocol using antibodies for specific markers and applying flow cytometry.

Mouse models in COVID-19 research: analyzing the adaptive immune response

The emergence of SARS-CoV-2, the severe acute respiratory syndrome coronavirus type 2 causing the COVID-19 pandemic, resulted in a major necessity for scientific countermeasures. Investigations revealing the exact mechanisms of the SARS-CoV-2 pathogenesis provide the basis for the development of therapeutic measures and protective vaccines against COVID-19. Animal models are inevitable for infection and pre-clinical vaccination studies as well as therapeutic testing. A well-suited animal model, mimicking the pathology seen in human COVID-19 patients, is an important basis for these investigations. Several animal models were already used during SARS-CoV-2 studies with different clinical outcomes after SARS-CoV-2 infection. Here, we give an overview of different animal models used in SARS-CoV-2 infection studies with a focus on the mouse model. Mice provide a well-established animal model for laboratory use and several different mouse models have been generated and are being used in SARS-CoV-2 studies. Furthermore, the analysis of SARS-CoV-2-specific T cells during infection and in vaccination studies in mice is highlighted.

Identification and validation of hub genes and potential drugs involved in osteoarthritis through bioinformatics analysis

Purpose: Osteoarthritis (OA) is a common degenerative disease, which still lacks specific therapeutic drugs. Synovitis is one of the most important pathological process in OA. Therefore, we aim to identify and analyze the hub genes and their related networks of OA synovium with bioinformatics tools to provide theoretical basis for potential drugs. Materials and methods: Two datasets were obtained from GEO. DEGs and hub genes of OA synovial tissue were screened through Gene Ontology (GO) annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment as well as protein-protein interaction (PPI) network analysis. Subsequently, the correlation between expression of hub genes and ferroptosis or pyroptosis was analyzed. CeRNA regulatory network was constructed after predicting the upstream miRNAs and lncRNAs. The validation of hub genes was undertook through RT-qPCR and ELISA. Finally, potential drugs targeting pathways and hub genes were identified, followed by the validation of the effect of two potential drugs on OA. Results: A total of 161 commom DEGs were obtained, of which 8 genes were finally identified as hub genes through GO and KEGG enrichment analysis as well as PPI network analysis. Eight genes related to ferroptosis and pyroptosis respectively were significantly correlated to the expression of hub genes. 24 miRNAs and 69 lncRNAs were identified to construct the ceRNA regulatory network. The validation of EGR1, JUN, MYC, FOSL1, and FOSL2 met the trend of bioinformatics analysis. Etanercept and Iguratimod reduced the secretion of MMP-13 and ADAMTS5 of fibroblast-like synoviocyte. Conclusion: EGR1, JUN, MYC, FOSL1, and FOSL2 were identified as hub genes in the development of OA after series of bioinformatics analysis and validation. Etanercept and Iguratimod seemed to have opportunities to be novel drugs for OA.

Inflammation Control and Immunotherapeutic Strategies in Comprehensive Cancer Treatment

Tumor growth and expansion are determined by the immunological tumor microenvironment (TME). Typically, early tumorigenic stages are characterized by the immune system not responding or weakly responding to the tumor. However, subsequent tumorigenic stages witness the tumor promoting its growth and metastasis by stimulating tumor-protective (pro-tumor) inflammation to suppress anti-tumor immune responses. Here, we propose the pivotal role of inflammation control in a successful anti-cancer immunotherapy strategy, implying that available and novel immunotherapeutic modalities such as inflammation modulation, antibody (Ab)-based immunostimulation, drug-mediated immunomodulation, cancer vaccination as well as adoptive cell immunotherapy and donor leucocyte transfusion could be applied in cancer patients in a synergistic manner to amplify each other's clinical effects and achieve robust anti-tumor immune reactivity. In addition, the anti-tumor effects of immunotherapy could be enhanced by thermal and/or oxygen therapy. Herein, combined immune-based therapy could prove to be beneficial for patients with advanced cancers, as aiming to provide long-term tumor cell/mass dormancy by restraining compensatory proliferation of surviving cancer cells observed after traditional anti-cancer interventions such as surgery, radiotherapy, and metronomic (low-dose) chemotherapy. We propose the Inflammatory Prognostic Score based on the blood levels of C-reactive protein and lactate dehydrogenase as well as the neutrophil-to-lymphocyte ratio to effectively monitor the effectiveness of comprehensive anti-cancer treatment.

Potential Application of Exosomes in Vaccine Development and Delivery

Exosomes are cell-derived components composed of proteins, lipid, genetic information, cytokines, and growth factors. They play a vital role in immune modulation, cell-cell communication, and response to inflammation. Immune modulation has downstream effects on the regeneration of damaged tissue, promoting survival and repair of damaged resident cells, and promoting the tumor microenvironment via growth factors, antigens, and signaling molecules. On top of carrying biological messengers like mRNAs, miRNAs, fragmented DNA, disease antigens, and proteins, exosomes modulate internal cell environments that promote downstream cell signaling pathways to facilitate different disease progression and induce anti-tumoral effects. In this review, we have summarized how vaccines modulate our immune response in the context of cancer and infectious diseases and the potential of exosomes as vaccine delivery vehicles. Both pre-clinical and clinical studies show that exosomes play a decisive role in processes like angiogenesis, prognosis, tumor growth metastasis, stromal cell activation, intercellular communication, maintaining cellular and systematic homeostasis, and antigen-specific T- and B cell responses. This critical review summarizes the advancement of exosome based vaccine development and delivery, and this comprehensive review can be used as a valuable reference for the broader delivery science community.

CARTmath-A Mathematical Model of CAR-T Immunotherapy in Preclinical Studies of Hematological Cancers

Immunotherapy has gained great momentum with chimeric antigen receptor T cell (CAR-T) therapy, in which patient's T lymphocytes are genetically manipulated to recognize tumor-specific antigens, increasing tumor elimination efficiency. In recent years, CAR-T cell immunotherapy for hematological malignancies achieved a great response rate in patients and is a very promising therapy for several other malignancies. Each new CAR design requires a preclinical proof-of-concept experiment using immunodeficient mouse models. The absence of a functional immune system in these mice makes them simple and suitable for use as mathematical models. In this work, we develop a three-population mathematical model to describe tumor response to CAR-T cell immunotherapy in immunodeficient mouse models, encompassing interactions between a non-solid tumor and CAR-T cells (effector and long-term memory). We account for several phenomena, such as tumor-induced immunosuppression, memory pool formation, and conversion of memory into effector CAR-T cells in the presence of new tumor cells. Individual donor and tumor specificities are considered uncertainties in the model parameters. Our model is able to reproduce several CAR-T cell immunotherapy scenarios, with different CAR receptors and tumor targets reported in the literature. We found that therapy effectiveness mostly depends on specific parameters such as the differentiation of effector to memory CAR-T cells, CAR-T cytotoxic capacity, tumor growth rate, and tumor-induced immunosuppression. In summary, our model can contribute to reducing and optimizing the number of in vivo experiments with in silico tests to select specific scenarios that could be tested in experimental research. Such an in silico laboratory is an easy-to-run open-source simulator, built on a Shiny R-based platform called CARTmath. It contains the results of this manuscript as examples and documentation. The developed model together with the CARTmath platform have potential use in assessing different CAR-T cell immunotherapy protocols and its associated efficacy, becoming an accessory for in silico trials.

Clinically feasible and prospective immunotherapeutic interventions in multidirectional comprehensive treatment of cancer

INTRODUCTION

The immune system is able to exert both tumor-destructive and tumor-protective functions. Immunotherapeutic technologies aim to enhance immune-based anti-tumor activity and (or) weaken tumor-protective immunity.

AREAS COVERED

Cancer vaccination, antibody (Ab)-mediated cytotoxicity, Ab-based checkpoint molecule inhibition, Ab-based immunostimulation, cytokine therapy, oncoviral therapy, drug-mediated immunostimulation, exovesicular therapy, anti-inflammatory therapy, neurohormonal immunorehabilitation, metabolic therapy, as well as adoptive cell immunotherapy, could be coherently used to synergize and amplify each other in achieving robust anti-cancer responses in cancer patients. Tumor-specific immunotherapy applied at early stages is capable of eliminating remaining tumor cells after surgery, thus preventing the development of minimal residual disease. Patients with advanced disease stages could benefit from combined immunotherapy, which would be aimed at providing tumor cell/mass dormancy. Traditional therapeutic anti-cancer interventions (chemoradiotherapy, hyperthermia, anti-hormonal therapy) could significantly enhance tumor sensitivity to anti-cancer immunotherapy. It is important that lower-dose (metronomic) chemotherapy regimens, which are well-tolerated by normal cells, could advance immune-mediated control over tumor growth.

EXPERT OPINION

We envisage that combined immunotherapy regimens in the context of traditional treatment could become the mainstream modality for treating cancers in all phases of the tumorigenesis. The effectiveness of the anti-cancer treatment could be monitored by the following blood parameters: C-reactive protein, lactate dehydrogenase, and neutrophil-to-lymphocyte ratio.

Deciphering the Molecular Targets and Mechanisms of HGWD in the Treatment of Rheumatoid Arthritis via Network Pharmacology and Molecular Docking

Background

Huangqi Guizhi Wuwu Decoction (HGWD) has been applied in the treatment of joint pain for more than 1000 years in China. Currently, most physicians use HGWD to treat rheumatoid arthritis (RA), and it has proved to have high efficacy. Therefore, it is necessary to explore the potential mechanism of action of HGWD in RA treatment based on network pharmacology and molecular docking methods.

Methods

The active compounds of HGWD were collected, and their targets were identified from the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and DrugBank database, respectively. The RA-related targets were retrieved by analyzing the differentially expressed genes between RA patients and healthy individuals. Subsequently, the compound-target network of HGWD was constructed and visualized through Cytoscape 3.8.0 software. Protein-protein interaction (PPI) network was constructed to explore the potential mechanisms of HGWD on RA using the plugin BisoGenet of Cytoscape 3.8.0 software. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed in R software (Bioconductor, clusterProfiler). Afterward, molecular docking was used to analyze the binding force of the top 10 active compounds with target proteins of VCAM1, CTNNB1, and JUN.

Results

Cumulatively, 790 active compounds and 1006 targets of HGWD were identified. A total of 4570 differentially expressed genes of RA with a p value <0.05 and |log 2(fold change)| > 0.5 were collected. Moreover, 739 GO entries of HGWD on RA were identified, and 79 pathways were screened based on GO and KEGG analysis. The core target gene of HGWD in RA treatment was JUN. Other key target genes included FOS, CCND1, IL6, E2F2, and ICAM1. It was confirmed that the TNF signaling pathway and IL-17 signaling pathway are important pathways of HGWD in the treatment of RA. The molecular docking results revealed that the top 10 active compounds of HGWD had a strong binding to the target proteins of VCAM1, CTNNB1, and JUN.

Conclusion

HGWD has important active compounds such as quercetin, kaempferol, and beta-sitosterol, which exert its therapeutic effect on multiple targets and multiple pathways.

Metabolic Reprogramming in Immune Response and Tissue Inflammation

Innate and adaptive immunity participate in and regulate numerous human diseases. Increasing evidence implies that metabolic reprogramming mediates immune cell functional changes during immune responses. In this review, we present and discuss our current understanding of metabolic regulation in different immune cells and their subsets in response to pathological stimuli. An interactive biochemical and molecular model was established to characterize metabolic reprogramming and their functional implication in anti-inflammatory, immune resolution, and proinflammatory responses. We summarize 2 major features of metabolic reprogramming in inflammatory stages in innate and adaptive immune cells: (1) energy production and biosynthesis reprogramming, including increased glycolysis and decreased oxidative phosphorylation, to secure faster ATP production and biosynthesis for defense response and damage repair and (2) epigenetic reprogramming, including enhanced histone acetylation and suppressed DNA methylation, due to altered accessibility of acetyl/methyl group donor and metabolite-modulated enzymatic activity. Finally, we discuss current strategies of metabolic and epigenetic therapy in cardiovascular disease and recommend cell-specific metabolic and gene-targeted site-specific epigenetic alterations for future therapies.

Monitoring HIV DNA and cellular activation markers in HIV-infected humanized mice under cART

Background

The major obstacle to cure of HIV type-1 infection is the presence of the HIV reservoir, hidden from the immune system and insensitive to combined antiretroviral therapy (cART). Eradication approaches have been hindered by the difficulty for accurately monitoring its size in vivo, especially in the lymphoid organs. Humanized mouse models are a valuable tool for systematically assess the efficacy of therapeutic interventions in reducing the HIV reservoir. Nonetheless, persistence of the HIV reservoir over time, in the presence of cART, has yet to be analyzed in this in vivo model.

Findings

We found that the proviral DNA as well as the total DNA were very stable in the spleen and mesenteric lymph node irrespective of the length of cART. Notably, the amount of proviral DNA was very similar in the spleen and lymph node. Furthermore, we observed a correlation between the percentage of splenic human CD4+ T-cells with total HIV DNA, between the number of human CD38 + CD8+ T-cells in the spleen with the amount of integrated HIV DNA, and eventually between the hCD4/hCD8 ratio in the spleen with integrated as well as total HIV DNA implying that the CD8+ T cells influence the size of the HIV reservoir.

Conclusions

Here, we demonstrated the stability of this reservoir in humanized mice irrespective of the length of cART, confirming the relevancy of this model for HIV latency eradication investigations. Notably, we also found correlates between the frequency of CD4+ T-cells, their activation status and viral parameters, which were analogous to the ones in HIV-infected patients. Thus, hu-mice represent a very valuable HIV latency model.

Eomesodermin driven IL-10 production in effector CD8+ T cells promotes a memory phenotype

CD8⁺ T cell differentiation is controlled by the transcription factors T-bet and Eomesodermin, in concert with the cytokines IL-2, IL-10 and IL-12. Among these pathways, the mechanisms by which T-box proteins and IL-10 interact to promote a memory T cell fate remain poorly understood. Here, we show that Eomes and IL-10 drive a central memory phenotype in murine CD8⁺ T cells. Eomes expression led to increased IL-10 expression by the effector CD8⁺ T cells themselves as well as an increase in the level of the lymph node homing selectin CD62L. Furthermore, exposure of effector CD8⁺ T cells to IL-10 maintained CD62L expression levels in culture. Thus, Eomes promotes a step-wise transition of effector T cells towards a memory phenotype, synergizing with IL-10 to enhance the expression of CD62L. The early augmentation of lymph node homing markers by Eomes may facilitate the retention of effector T cells in the relatively low inflammatory milieu of the secondary lymphoid organs that promotes central memory development.

IL-21 Receptor Signaling Is Essential for Optimal CD4+ T Cell Function and Control of Mycobacterium tuberculosis Infection in Mice

In this study, we determined the role of IL-21R signaling in Mycobacterium tuberculosis infection, using IL-21R knockout (KO) mice. A total of 50% of M. tuberculosis H37Rv-infected IL-21R KO mice died in 6 mo compared with no deaths in infected wild type (WT) mice. M. tuberculosis-infected IL-21R KO mice had enhanced bacterial burden and reduced infiltration of Ag-specific T cells in lungs compared with M. tuberculosis-infected WT mice. Ag-specific T cells from the lungs of M. tuberculosis-infected IL-21R KO mice had increased expression of T cell inhibitory receptors, reduced expression of chemokine receptors, proliferated less, and produced less IFN- γ, compared with Ag-specific T cells from the lungs of M. tuberculosis-infected WT mice. T cells from M. tuberculosis-infected IL-21R KO mice were unable to induce optimal macrophage responses to M. tuberculosis. This may be due to a decrease in the Ag-specific T cell population. We also found that IL-21R signaling is associated with reduced expression of a transcriptional factor Eomesodermin and enhanced functional capacity of Ag-specific T cells of M. tuberculosis-infected mice. The sum of our findings suggests that IL-21R signaling is essential for the optimal control of M. tuberculosis infection.

A Possible Role for Idiotype/Anti-idiotype B-T Cell Interactions in Maintaining Immune Memory

Variable regions of both B-cell receptors (BCRs) and T-cell receptors (TCRs) are completely formed in the postnatal period, and, consequently, no innate immune tolerance against these structures exists in adulthood. Indeed, antibodies (Abs) specific to TCRs have been found in both animals and humans. These facts clearly indicate the existence of B cells able to directly interact with T cells through binding of BCRs to TCRs without implicating major histocompatibility complex molecules. A novel paradigm is proposed in that the immune memory is based on idiotype/anti-idiotype interactions occurring between BCRs and TCRs following clearance of the antigen that elicited immune responses. It is envisaged that direct contact between memory T and B cells could provide co-stimulatory signals needed to sustain viability, growth, and differentiation of the interacting immune cells. In contrast, plasma cells originating from memory B-cells could produce anti-TCR Abs that inhibit direct BCR-to-TCR interactions, thereby downregulating the B- to T-cell contact-based immune memory via a negative feedback mechanism.

Antiparasitic Treatment Induces an Improved CD8+ T Cell Response in Chronic Chagasic Patients

Chagas disease is a chronic infection caused by Trypanosoma cruzi, an intracellular protozoan parasite. Chronic chagasic patients (CCPs) have dysfunctional CD8⁺ T cells that are characterized by impaired cytokine production, high coexpression of inhibitory receptors, and advanced cellular differentiation. Most patients diagnosed in the chronic phase of Chagas disease already exhibit heart involvement, and there is no vaccination that protects against the disease. Antiparasitic treatment is controversial as to its indication for this stage of the disease. There is a lack of biological markers to evaluate the effectiveness of antiparasitic treatment, and little is known about the effect of the treatment on CD8⁺ T cells. Thus, the aim of the current study was to analyze the early effects of antiparasitic treatment on CD8⁺ T cells from CCPs with asymptomatic clinical forms of disease. To evaluate the CD8⁺ T cell subsets, expression of inhibitory receptors, and functionality of T cells in CCPs, PBMCs were isolated. The results showed that treatment of CCPs with the asymptomatic form of the disease induces an increase in the frequency of CD8⁺ central memory T cells and terminal effector T cells, a decrease in the coexpression of inhibitory receptors, an improved Ag-specific CD8⁺ T cell response exhibited by the individual production of IFN-γ or IL-2, and a multifunctional CD8⁺ T cell profile of up to four functions (IFN-γ⁺IL-2⁺Perforin⁺Granzyme B⁺). These findings suggest that, in CCPs, antiparasitic treatment improved the quality of Ag-specific CD8⁺ T cell responses associated with a decrease in inhibitory receptor coexpression, which could serve as biomarkers for monitoring the effectiveness of antiparasitic treatment.

CCR7+ selected gene-modified T cells maintain a central memory phenotype and display enhanced persistence in peripheral blood in vivo

BACKGROUND

Adoptive T cell immunotherapy (ATCT) for cancer entails infusing patients with T cells that recognise and destroy tumour cells. Efficient engraftment of T cells and persistence in the circulation correlate with favourable clinical outcomes. T cells of early differentiation possess an increased capacity for proliferation and therefore persistence, using these cells for ATCT could therefore lead to improved clinical outcomes.

METHOD

We describe a method to enrich T cells of early differentiation status using paramagnetic beads and antibodies targeting cells expressing C-C motif chemokine receptor 7 (CCR7).

RESULTS

Selection of cells expressing CCR7 enriches T cells of bearing markers of early differentiation status. This was validated through analysis of an array of surface markers and an observed reduction in effector cell functions ex vivo. CCR7 selection resulted in dramatic 83.6 and 137 fold increases in circulating levels of CD4 and CD8 T cells respectively compared to non-sorted T cells 3 weeks after adoptive transfer to NSG mice. We observed no significant difference in the engraftment levels of CCR7 or CD62L selected cells in the NSG mouse model. Comparison of cells ex vivo, however, suggests CCR7 selection is superior to CD62L selection in enriching T cells of early differentiation status.

CONCLUSIONS

CCR7 selection offers a means to enrich T cells of early differentiation status for ACTC. Together our data suggests that these T cells are likely to display enhanced engraftment and persistence in patients in vivo and could therefore improve therapeutic efficacy of ACTC.

Immune responses to polyclonal T-cell vaccination in patients with progressive multiple sclerosis

The overall objective of disease management in autoimmune diseases is to suppress chronic inflammation and prevent organ damage. Therapies often revolve around five drug classes: non-steroidal anti-inflammatory drugs (NSAIDS), anti-malarials, steroids, immunosuppressants, and bio-therapies. However, none of these is a 'cure' and each displays a potential for adverse events. In particular, while all of them suppress harmful autoimmune responses, they also impact on useful protective immune responses. T-Cell receptor (TCR) immunogenicity provides a rationale for T-cell vaccinations to induce anti-idiotypic immune responses with the purpose of down-regulating functionality of idiotype-bearing self-reactive T-cells. To explore this, in this study, 39 patients with progressive (chronic) multiple sclerosis (MS) were multiply immunized with autological polyclonal T-cell vaccines (TCVs). None of the TCV-treated patients experienced any significant side-effects during the entire follow-up period (2 years). T-Cell vaccination had no significant effects on T-cell sub-population contents in the blood of MS patients after 2 years of immunotherapy initiation. However, a substantial reduction in the frequency of CD4⁺and CD8⁺memory T-cells able to produce interferon (IFN)-γ following activation were noted in the blood of TCV-treated patients. Moreover, significant and sustained reduction in plasma IFNγ levels and concomitant increases in interleukin (IL)-4 levels were documented in these samples. The TCV-treated subjects, however, exhibited no significant changes in plasma IL-17 and IL-18. More importantly was a significant decline in proliferative T-cell responses to myelin antigens in the TCV-treated patients, indicating attenuation of myelin-specific T-cell activity. Collectively, the results suggest that polyclonal T-cell vaccination is safe to use, able to induce measurable, long-lasting, anti-inflammatory immune effects in patients with advanced MS.

[Cytokine-mediated regulation of expression of Gfi1 and U2afll4 genes activated by T-cells with different differentiation status in vitro]

The dose-dependent effects of cytokines (IL-2, IL-7, and IL-15), which have a common g-chain, on mRNA expression of U2afll4 and GFi1 genes involved in regulation of alternative splicing of the Ptprc gene, have been investigated in vitro using T-lymphocyte cultures with different degrees of differentiation. IL-2, IL-7, and IL-15 caused a similar unidirectional inhibitory effect of various severity on restimulated CD45RO+ T-cells exposed to an antigen-independent activation; they caused a dose-dependent decrease of the U2af1l4 gene expression, and an increase of Gfi1 gene expression. This may suggest formation of active forms of the CD45 receptor, and also limitation of the formation of low-molecular short splice variants of the CD45RO receptor. Under conditions of antigen-independent stimulation of naive CD45RA+-cells rIL-7 and IL-15 exhibited opposite effects on U2af1l4 and Gfi1 gene expression. The increase of IL-7 concentrations in the incubation medium of naive cells was accompanied by a decrease in expression of both genes. IL-15 IL-7 exhibited opposite effects. Cytokines possessing a common g-chain (IL-2, IL-7, and IL-15) prevented antigen-independent differentiation of naive T-cells, by preventing the formation of polyclonal "surrogate" cells. In general, the study of the molecular mechanisms of genetic control determining homeostatic processes of T-cells in response to exposure to antigenic or non-antigenic treatments may be important for construction of a general model of self-maintenance and differentiation of immune cells.

Effects of Immunoregulatory Cytokines (IL-2, IL-7, and IL-15) on Expression of Gfi1 and U2afll4 Genes in T Cells at Different Stages of Differentiation

Opposite effects of common γ-chain cytokines (IL-2, IL-7, and IL-15) on the expression of Gfi1 and U2af1l4 genes regulating alternative splicing of Ptprc gene in T cells at different stages of differentiation were demonstrated in vitro. Generally, produced a dose-dependent activating effect on T cells, while to the effects of rIL-7 and rIL-15 on T cells at different stages of differentiation were opposite to that of rIL-2: maximum concentrations of recombinant cytokines IL-7 and IL-15 produced the most pronounced inhibitory effect on U2af1l4 and to a lesser extent on Gfi1 gene expression, thus limiting activation of resting cells. This is consistent with their biological effects on T cells. In general, common γ-chain cytokines IL-2, IL-7, and IL-15 prevent differentiation of naïve T cells in vitro and limit activation of primed T cells in the absence of antigenic stimulus, which can contribute to the formation of cytokine imbalance.

Assessment of the effector function of CMV-specific CTLs isolated using MHC-multimers from granulocyte-colony stimulating factor mobilized peripheral blood

BACKGROUND

Adoptive transfer of CMV-specific T cells has shown promising results in preventing pathological effects caused by opportunistic CMV infection in immunocompromised patients following allogeneic hematopoietic stem cell transplantation. The majority of studies have used steady-state leukapheresis for CMV-reactive product manufacture, a collection obtained prior to or months after G-CSF mobilization, but the procurement of this additional sample is often not available in the unrelated donor setting. If the cellular product for adoptive immunotherapy could be generated from the same G-CSF mobilized collection, the problems associated with the additional harvest could be overcome. Despite the tolerogenic effects associated with G-CSF mobilization, recent studies described that CMV-primed T cells generated from mobilized donors remain functional.

METHODS

MHC-multimers are potent tools that allow the rapid production of antigen-specific CTLs. Therefore, in the present study we have assessed the feasibility and efficacy of CMV-specific CTL manufacture from G-CSF mobilized apheresis using MHC-multimers.

RESULTS

CMV-specific CTLs can be efficiently isolated from G-CSF mobilized samples with Streptamers and are able to express activation markers and produce cytokines in response to antigenic stimulation. However, this anti-viral functionality is moderately reduced when compared to non-mobilized products.

CONCLUSIONS

The translation of Streptamer technology for the isolation of anti-viral CTLs from G-CSF mobilized PBMCs into clinical practice would widen the number of patients that could benefit from this therapeutic strategy, although our results need to be taken into consideration before the infusion of antigen-specific T cells obtained from G-CSF mobilized samples.

New prospects for a preventive HIV-1 vaccine

The immune correlates of risk analysis and recent non-human primate (NHP) challenge studies have generated hypotheses that suggest HIV-1 envelope may be essential and, perhaps, sufficient to induce protective antibody responses against HIV-1 acquisition at the mucosal entry. New prime-boost mosaic and conserved-sequence, together with replicating vector immunisation strategies aiming at inducing immune responses or greater breadth, as well as the development of immunogens inducing broadly neutralising antibodies and mucosal responses, should be actively pursued and tested in humans. Whether the immune correlates of risk identified in RV144 can be extended to other vaccines, other populations, or different modes and intensity of transmission, and against increasing HIV-1 genetic diversity, remains to be demonstrated. Although NHP challenge studies may guide vaccine development, human efficacy trials remain key for answering the critical questions leading to the development of a global HIV-1 vaccine for licensure.

The clinical significance of memory T cells and its subsets in gastric cancer

BACKGROUND

Long life of memory T cell (Tm) determines its crucial role in the carcinogenesis and carcinogenic progression which usually take long time. The Tm compartment contains two populations, central memory T cells (Tcm) and effector memory T cells (Tem), based on their phenotypic markers, functional attributes, and migratory properties.

METHODS

We investigated the subsets of the Tm in peripheral blood and tumor microenvironments in patients with gastric cancer by flow cytometry, and aimed to explore the correlation between the Tm and clinicopathologic features of gastric cancer.

RESULTS

The percentages of CD4(+)/CD8(+) Tm and CD4(+)/CD8(+) Tcm in peripheral blood from gastric cancer patients were statistically lower, whereas the percentages of CD4(+)/CD8(+) Tem were significantly higher than healthy controls. The proportion of CD4(+)/CD8(+) Tcm increased after tumor resection, while the percentage of the CD4(+)/CD8(+) Tem decreased significantly. Significant associations were detected between the peripheral CD4(+)/CD8(+) Tm and clinical stage, as well as the CD8(+) Tcm and clinical stage and nodal involvement. Tumor infiltrating CD8(+) Tm expressed both central and effector memory phenotypes, whereas CD4(+) Tm displayed predominantly an effector memory phenotype. Higher percentages of tumor infiltrating CD4(+)/CD8(+) Tm were significantly associated with the early disease stage.

CONCLUSIONS

Tm and its subsets were good immune indicators for the disease stage of gastric cancer. The proportion of Tm subsets may reflect the immune suppressive and immune response to the tumor associated antigen.

The gamma-chain cytokine/receptor system in fish: more ligands and receptors

The mammalian gamma-chain (γC) cytokine family consists of interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15 and IL-21. They signal through a receptor complex containing the common γC and a private alpha chain, and in the case of IL-2 and IL-15 an additional common IL-2/15Rβ chain. Deficiency of γC signalling in mammals prevents CD4+ T cells from developing effector functions and CD8+ T cells from developing immunological memory. Thus γC cytokines are critical for the generation and peripheral homeostasis of naïve and memory T cells. This review will give an update on the γC ligands and receptor subunits in fish, and also present some new data on the cloning and expression of a second γC and two IL-2Rβ chains in rainbow trout Oncorhynchus mykiss. In recent years, aided by the availability of sequenced fish genomes and expressed sequence tag databases, five of the six mammalian γC cytokines and their cognate receptors have been discovered in fish, with only the IL-9/IL-9R homologues apparently absent. Paralogues have been discovered in diploid fish and all the receptors described in the tetraploid rainbow trout, including γC itself, IL-2Rβ, IL-4Rα, IL-13Rα1, IL-13Rα2 and IL-2/15Rα, have duplicates. As a consequence of the teleost and salmonid whole genome duplications, even more paralogues may yet be discovered. Some of the paralogues have changes in domain structures and show differential expression and modulation, suggesting the potential for a change in function. Functional characterisation of fish γC cytokines is beginning but made more difficult by the co-existence of so many paralogues of the ligands and their receptors. Initial functional studies have shown that fish γC cytokines can modulate the expression of key cytokines (e.g. interferon-γ, IL-10 and IL-22) of the adaptive immune response, and may thus have promise as adjuvants to improve vaccination efficiency in fish.

Phenotypic definition of effector and memory T-lymphocyte subsets in mice chronically infected with Mycobacterium tuberculosis

The bacterium Mycobacterium tuberculosis remains one of the world's most successful pathogens, a situation that is aggravated by the fact that the existing vaccine, Mycobacterium bovis BCG, is not effective in adults. As with any vaccine, the purpose of giving BCG vaccination is to establish a long-lived state of memory immunity, but whether this is successfully completely established is still unclear. It is generally accepted that memory T cells can be divided into central and effector memory populations by function and by phenotype; however, the majority of data supporting this division have been generated using transgenic mouse models or mice that have recovered from acute viral infections. Tuberculosis, on the other hand, represents a persistent, chronic state of immunity in which the presence of memory T cells is far less well defined. We show here that mice vaccinated with BCG or chronically infected with M. tuberculosis establish antigen-specific populations of cells within the lungs that predominantly express a cellular phenotype consistent with their being effector or effector memory cells. In contrast, cells with a central memory phenotype exist in much lower numbers in the lungs but can be found in significantly larger numbers in the spleen, where they may represent a potential reservoir. These data suggest that the effector-to-central-memory T-cell transition may well be minimal in these persisting mycobacterial infections, and they support a novel hypothesis that this may explain the fundamental basis of the failure of the BCG vaccine in humans.