Inactivation of T cell receptor peptide-specific CD4 regulatory T cells induces chronic experimental autoimmune encephalomyelitis (EAE)

Low Expression of TSTD2 Serves as a Biomarker for Poor Prognosis in Kidney Renal Clear Cell Carcinoma

Introduction

Kidney renal clear cell carcinoma (KIRC) is a common cancer in people worldwide, and one of the main issues is developing suitable biomarkers. This study aims to investigate the expression of TSTD2 in KIRC and its impact on prognosis.

Methods

RNA sequencing data from TCGA and GTEx were gathered to examine the functional enrichment of TSTD2-related differentially expressed genes (DEGs) using GO/KEGG, GSEA, immunocyte permeation analysis, and protein-protein interaction (PPI) network analysis. The Kaplan‒Meier-Cox regression model and the prognostic nomograph model were used to assess the clinical importance of TSTD2 in KIRC. R software was used to analyze the included studies. Finally, verification of cells and tissues was performed using immunohistochemical staining and quantitative real‒time PCR.

Results

In contrast to normal samples, it was discovered that TSTD2 was underexpressed in a number of malignancies, including KIRC. Furthermore, in 163 KIRC samples, low expression of TSTD2 was linked to a poor prognosis, as were subgroups with age greater than 60, the integrin pathway, the development of elastic fibers, and high TNM stage, pathologic stage, and histologic grade (P < 0.05). Age and TNM stage were included in the nomogram prognostic model, and low TSTD2 was a prognostic predictor that could be used independently in Cox regression analysis. In addition, 408 DEGs with 111 upregulated genes and 297 downregulated genes were found between the high- and low-expression groups.

Conclusion

The diminished expression of TSTD2 may serve as a biomarker for unfavorable outcomes in KIRC, and holds potential as a target for therapeutic interventions.

Modulation of CD4 T Cell Response According to Tumor Cytokine Microenvironment

The advancement of knowledge on tumor biology over the past decades has demonstrated a close link between tumor cells and cells of the immune system. In this context, cytokines have a major role because they act as intermediaries in the communication into the tumor bed. Cytokines play an important role in the homeostasis of innate and adaptive immunity. In particular, they participate in the differentiation of CD4 T lymphocytes. These cells play essential functions in the anti-tumor immune response but can also be corrupted by tumors. The differentiation of naïve CD4 T cells depends on the cytokine environment in which they are activated. Additionally, at the tumor site, their activity can also be modulated according to the cytokines of the tumor microenvironment. Thus, polarized CD4 T lymphocytes can see their phenotype evolve, demonstrating functional plasticity. Knowledge of the impact of these cytokines on the functions of CD4 T cells is currently a source of innovation, for therapeutic purposes. In this review, we discuss the impact of the major cytokines present in tumors on CD4 T cells. In addition, we summarize the main therapeutic strategies that can modulate the CD4 response through their impact on cytokine production.

Opposing T cell responses in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis is a model for multiple sclerosis. Here we show that induction generates successive waves of clonally expanded CD4+, CD8+ and γδ+ T cells in the blood and central nervous system, similar to gluten-challenge studies of patients with coeliac disease. We also find major expansions of CD8+ T cells in patients with multiple sclerosis. In autoimmune encephalomyelitis, we find that most expanded CD4+ T cells are specific for the inducing myelin peptide MOG35-55. By contrast, surrogate peptides derived from a yeast peptide major histocompatibility complex library of some of the clonally expanded CD8+ T cells inhibit disease by suppressing the proliferation of MOG-specific CD4+ T cells. These results suggest that the induction of autoreactive CD4+ T cells triggers an opposing mobilization of regulatory CD8+ T cells.

T-cell repertoire profiling by next-generation sequencing reveals tissue migration dynamics of TRBV13-family clonotypes in a common experimental autoimmune encephalomyelitis mouse model

The experimental autoimmune encephalomyelitis (EAE) model is indispensable for autoimmunity research, but model-specific T cell dynamics are sparsely studied. We used next-generation immunosequencing across lymphoid organs, blood and spinal cord in response to immunization with myelin basic protein (MBP) to study T cell repertoires and migration patterns. Surprisingly, most spinal cord T cells were unique to the individual animal despite the existence of shared MBP-specific clones, suggesting a previously underestimated T cell diversity. Almost complete emigration of pathogenic clones from blood to spinal cord indicates that blood is not a suitable compartment to study EAE-mediating T cells.

Interferon β-Mediated Protective Functions of Microglia in Central Nervous System Autoimmunity

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) leading to demyelination and axonal damage. It often affects young adults and can lead to neurological disability. Interferon β (IFNβ) preparations represent widely used treatment regimens for patients with relapsing-remitting MS (RRMS) with therapeutic efficacy in reducing disease progression and frequency of acute exacerbations. In mice, IFNβ therapy has been shown to ameliorate experimental autoimmune encephalomyelitis (EAE), an animal model of MS while genetic deletion of IFNβ or its receptor augments clinical severity of disease. However, the complex mechanism of action of IFNβ in CNS autoimmunity has not been fully elucidated. Here, we review our current understanding of the origin, phenotype, and function of microglia and CNS immigrating macrophages in the pathogenesis of MS and EAE. In addition, we highlight the emerging roles of microglia as IFNβ-producing cells and vice versa the impact of IFNβ on microglia in CNS autoimmunity. We finally discuss recent progress in unraveling the underlying molecular mechanisms of IFNβ-mediated effects in EAE.

Activation of astrocytes and expression of inflammatory cytokines in rats with experimental autoimmune encephalomyelitis

The aim of the study was to investigate and discuss the activation of astrocytes and the expression of inflammatory cytokines in rats with experimental autoimmune encephalomyelitis (EAE). Twenty Wistar rats were randomly divided into the normal control (n=10) and EAE group (n=10). The rats in the EAE group were injected intraperitoneally with myelin oligodendrocyte glycoprotein 35–55 emulsion, and those in the control group were injected with the equivalent volume of normal saline. Wear neurological function scale was applied to evaluate the neurological functions of the rats, and the weight changes were recorded. At 21 days after immunization, hematoxylin and eosin staining was used to detect the histomorphology, and immunofluorescence was used to measure the activation conditions of the brain astrocytes. Reverse transcription-polymerase chain reaction and western blot analysis were utilized to detect the messenger RNA (mRNA) and protein levels of inflammatory factors. The disease occurred in rats of the EAE group at 9 days after immunization, and the incidence rate was 80%. The Wear score of the rats in the EAE group was significantly increased compared with that in the control group (P<0.05). At 9 days after immunization, the weight of the rats in the EAE group was obviously lower than that in the control group (P<0.05). The inflammatory lesion of rats in the EAE group mainly occurred in the region of brain parenchyma. The glial fibrillary acidic protein level in the brain sections of the rats in the EAE group was markedly elevated compared with that in control group. The mRNA and protein levels of interleukin-10 in the rat brain in EAE group were decreased notably (P<0.05), while those of interferon-γ and tumor necrosis factor-α were increased significantly (P<0.05). The significant increases in the activation level of astrocytes and inflammatory cytokine level have a close relationship with EAE progression.

Strategies for calibrating models of biology

Computational and mathematical modelling has become a valuable tool for investigating biological systems. Modelling enables prediction of how biological components interact to deliver system-level properties and extrapolation of biological system performance to contexts and experimental conditions where this is unknown. A model's value hinges on knowing that it faithfully represents the biology under the contexts of use, or clearly ascertaining otherwise and thus motivating further model refinement. These qualities are evaluated through calibration, typically formulated as identifying model parameter values that align model and biological behaviours as measured through a metric applied to both. Calibration is critical to modelling but is often underappreciated. A failure to appropriately calibrate risks unrepresentative models that generate erroneous insights. Here, we review a suite of strategies to more rigorously challenge a model's representation of a biological system. All are motivated by features of biological systems, and illustrative examples are drawn from the modelling literature. We examine the calibration of a model against distributions of biological behaviours or outcomes, not only average values. We argue for calibration even where model parameter values are experimentally ascertained. We explore how single metrics can be non-distinguishing for complex systems, with multiple-component dynamic and interaction configurations giving rise to the same metric output. Under these conditions, calibration is insufficiently constraining and the model non-identifiable: multiple solutions to the calibration problem exist. We draw an analogy to curve fitting and argue that calibrating a biological model against a single experiment or context is akin to curve fitting against a single data point. Though useful for communicating model results, we explore how metrics that quantify heavily emergent properties may not be suitable for use in calibration. Lastly, we consider the role of sensitivity and uncertainty analysis in calibration and the interpretation of model results. Our goal in this manuscript is to encourage a deeper consideration of calibration, and how to increase its capacity to either deliver faithful models or demonstrate them otherwise.

Presenilin1 regulates Th1 and Th17 effector responses but is not required for experimental autoimmune encephalomyelitis

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) where pathology is thought to be regulated by autoreactive T cells of the Th1 and Th17 phenotype. In this study we sought to understand the functions of Presenilin 1 (PSEN1) in regulating T cell effector responses in the experimental autoimmune encephalomyelitis (EAE) murine model of MS. PSEN1 is the catalytic subunit of γ-secretase a multimolecular protease that mediates intramembranous proteolysis. γ-secretase is known to regulate several pathways of immune importance. Here we examine the effects of disrupting PSEN1 functions on EAE and T effector differentiation using small molecule inhibitors of γ-secretase (GSI) and T cell-specific conditional knockout mice (PSEN1 cKO). Surprisingly, blocking PSEN1 function by GSI treatment or PSEN1 cKO had little effect on the development or course of MOG35-55-induced EAE. In vivo GSI administration reduced the number of myelin antigen-specific T cells and suppressed Th1 and Th17 differentiation following immunization. In vitro, GSI treatment inhibited Th1 differentiation in neutral but not IL-12 polarizing conditions. Th17 differentiation was also suppressed by the presence of GSI in all conditions and GSI-treated Th17 T cells failed to induce EAE following adoptive transfer. PSEN cKO T cells showed reduced Th1 and Th17 differentiation. We conclude that γ-secretase and PSEN1-dependent signals are involved in T effector responses in vivo and potently regulate T effector differentiation in vitro, however, they are dispensable for EAE.

Automated multi-objective calibration of biological agent-based simulations

Computational agent-based simulation (ABS) is increasingly used to complement laboratory techniques in advancing our understanding of biological systems. Calibration, the identification of parameter values that align simulation with biological behaviours, becomes challenging as increasingly complex biological domains are simulated. Complex domains cannot be characterized by single metrics alone, rendering simulation calibration a fundamentally multi-metric optimization problem that typical calibration techniques cannot handle. Yet calibration is an essential activity in simulation-based science; the baseline calibration forms a control for subsequent experimentation and hence is fundamental in the interpretation of results. Here, we develop and showcase a method, built around multi-objective optimization, for calibrating ABSs against complex target behaviours requiring several metrics (termed objectives) to characterize. Multi-objective calibration (MOC) delivers those sets of parameter values representing optimal trade-offs in simulation performance against each metric, in the form of a Pareto front. We use MOC to calibrate a well-understood immunological simulation against both established a priori and previously unestablished target behaviours. Furthermore, we show that simulation-borne conclusions are broadly, but not entirely, robust to adopting baseline parameter values from different extremes of the Pareto front, highlighting the importance of MOC's identification of numerous calibration solutions. We devise a method for detecting overfitting in a multi-objective context, not previously possible, used to save computational effort by terminating MOC when no improved solutions will be found. MOC can significantly impact biological simulation, adding rigour to and speeding up an otherwise time-consuming calibration process and highlighting inappropriate biological capture by simulations that cannot be well calibrated. As such, it produces more accurate simulations that generate more informative biological predictions.

NKT cell subsets as key participants in liver physiology and pathology

Natural killer T (NKT) cells are innate-like lymphocytes that generally recognize lipid antigens and are enriched in microvascular compartments of the liver. NKT cells can be activated by self- or microbial-lipid antigens and by signaling through toll-like receptors. Following activation, NKT cells rapidly secrete pro-inflammatory or anti-inflammatory cytokines and chemokines, and thereby determine the milieu for subsequent immunity or tolerance. It is becoming clear that two different subsets of NKT cells-type I and type II-have different modes of antigen recognition and have opposing roles in inflammatory liver diseases. Here we focus mainly on the roles of both NKT cell subsets in the maintenance of immune tolerance and inflammatory diseases in liver. Furthermore, how the differential activation of type I and type II NKT cells influences other innate cells and adaptive immune cells to result in important consequences for tissue integrity is discussed. It is crucial that better reagents, including CD1d tetramers, be used in clinical studies to define the roles of NKT cells in liver diseases in patients.

Role of glycine N-methyltransferase in the regulation of T-cell responses in experimental autoimmune encephalomyelitis

Glycine N-methyltransferase (GNMT) is known for its function as a tumor suppressor gene. Since 100% of female Gnmt(-/-) mice developed hepatocellular carcinoma, we hypothesized that Gnmt(-/-) mice may have defective immune surveillance. In this study, we examined the immune modulation of GNMT in T-cell responses using experimental autoimmune encephalomyelitis (EAE). The results showed that EAE severity was reduced significantly in Gnmt(-/-) mice. Pathological examination of the spinal cords revealed that Gnmt(-/-) mice had significantly lower levels of mononuclear cell infiltration and demyelination than the wild-type mice. In addition, quantitative real-time PCR showed that expression levels of proinflammatory cytokines, including interferon (IFN)-γ and interleukin (IL)-17A, were much lower in the spinal cord of Gnmt(-/-) than in that of wild-type mice. Accordingly, myelin oligodendrocyte glycoprotein (MOG)-specific T-cell proliferation and induction of T-helper (Th)1 and Th17 cells were markedly suppressed in MOG(35-55)-induced Gnmt(-/-) mice. Moreover, the number of regulatory T (Treg) cells was increased significantly in these mice. When the T-cell receptor was stimulated, the proliferative capacity and the activation status of mTOR-associated downstream signaling were decreased significantly in Gnmt(-/-) CD4(+) T cells via an IL-2- and CD25-independent manner. Moreover, GNMT deficiency enhanced the differentiation of Treg cells without affecting the differentiation of Th1 and Th17 cells. Furthermore, the severity of EAE in mice adoptive transferred with GNMT-deficient CD4(+) T cells was much milder than in those with wild-type CD4(+) T cells. In summary, our findings suggest that GNMT is involved in the pathogenesis of EAE and plays a crucial role in the regulation of CD4(+) T-cell functions.

The contribution of immune and glial cell types in experimental autoimmune encephalomyelitis and multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterised by widespread areas of focal demyelination. Its aetiology and pathogenesis remain unclear despite substantial insights gained through studies of animal models, most notably experimental autoimmune encephalomyelitis (EAE). MS is widely believed to be immune-mediated and pathologically attributable to myelin-specific autoreactive CD4+ T cells. In recent years, MS research has expanded beyond its focus on CD4+ T cells to recognise the contributions of multiple immune and glial cell types to the development, progression, and amelioration of the disease. This review summarises evidence of T and B lymphocyte, natural killer cell, macrophage/microglial, astrocytic, and oligodendroglial involvement in both EAE and MS and the intercommunication and influence of each cell subset in the inflammatory process. Despite important advances in the understanding of the involvement of these cell types in MS, many questions still remain regarding the various subsets within each cell population and their exact contribution to different stages of the disease.

Determining disease intervention strategies using spatially resolved simulations

Predicting efficacy and optimal drug delivery strategies for small molecule and biological therapeutics is challenging due to the complex interactions between diverse cell types in different tissues that determine disease outcome. Here we present a new methodology to simulate inflammatory disease manifestation and test potential intervention strategies in silico using agent-based computational models. Simulations created using this methodology have explicit spatial and temporal representations, and capture the heterogeneous and stochastic cellular behaviours that lead to emergence of pathology or disease resolution. To demonstrate this methodology we have simulated the prototypic murine T cell-mediated autoimmune disease experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. In the simulation immune cell dynamics, neuronal damage and tissue specific pathology emerge, closely resembling behaviour found in the murine model. Using the calibrated simulation we have analysed how changes in the timing and efficacy of T cell receptor signalling inhibition leads to either disease exacerbation or resolution. The technology described is a powerful new method to understand cellular behaviours in complex inflammatory disease, permits rational design of drug interventional strategies and has provided new insights into the role of TCR signalling in autoimmune disease progression.

In silico investigation into dendritic cell regulation of CD8Treg mediated killing of Th1 cells in murine experimental autoimmune encephalomyelitis

Background

Experimental autoimmune encephalomyelitis has been used extensively as an animal model of T cell mediated autoimmunity. A down-regulatory pathway through which encephalitogenic CD4Th1 cells are killed by CD8 regulatory T cells (Treg) has recently been proposed. With the CD8Treg cells being primed by dendritic cells, regulation of recovery may be occuring around these antigen presenting cells. CD4Treg cells provide critical help within this process, by licensing dendritic cells to prime CD8Treg cells, however the spatial and temporal aspects of this help in the CTL response is currently unclear.

Results

We have previously developed a simulator of experimental autoimmune encephalomyelitis (ARTIMMUS). We use ARTIMMUS to perform novel in silico experimentation regarding the priming of CD8Treg cells by dendritic cells, and the resulting CD8Treg mediated killing of encephalitogenic CD4Th1 cells. Simulations using dendritic cells that present antigenic peptides in a mutually exclusive manner (either MBP or TCR-derived, but not both) suggest that there is no significant reliance on dendritic cells that can prime both encephalitogenic CD4Th1 and Treg cells. Further, in silico experimentation suggests that dynamics of CD8Treg priming are significantly influenced through their spatial competition with CD4Treg cells and through the timing of Qa-1 expression by dendritic cells.

Conclusion

There is no requirement for the encephalitogenic CD4Th1 cells and cytotoxic CD8Treg cells to be primed by the same dendritic cells. We conjecture that no significant portion of CD4Th1 regulation by Qa-1 restricted CD8Treg cells occurs around individual dendritic cells, and as such, that CD8Treg mediated killing of CD4Th1 cells occurring around dendritic cells is not critical for recovery from the murine autoimmune disease. Furthermore, the timing of the CD4Treg licensing of dendritic cells and the spatial competition between CD4Treg and CD8Treg cells around the dendritic cell is critical for the size of the cytotoxic T lymphocyte response, because dendritic cells have a limited lifespan. If treatments can be found to either speed up the licensing process, or increase the spatial competitiveness of CD8Treg cells, the magnitude of the cytotoxic T lymphocyte response can be increased.

In silico investigation of novel biological pathways: the role of CD200 in regulation of T cell priming in experimental autoimmune encephalomyelitis

The use of simulation to investigate biological domains will inevitably lead to the need to extend existing simulations as new areas of these domains become more fully understood. Such simulation extensions can entail the incorporation of additional cell types, molecules or molecular pathways, all of which can exert a profound influence on the simulation behaviour. Where the biological domain is not well characterised, a structured development methodology must be employed to ensure that the extended simulation is well aligned with its predecessor. We develop and discuss such a methodology, relying on iterative simulation development and sensitivity analysis. The utility of this methodology is demonstrated using a case study simulation of experimental autoimmune encephalomyelitis (EAE), a murine T cell-mediated autoimmune disease model of multiple sclerosis, where it is used to investigate the activity of an additional regulatory pathway. We discuss how application of this methodology guards against creating inappropriate simulation representations of the biology when investigating poorly characterised biological mechanisms.

A2A adenosine receptor signaling in lymphocytes and the central nervous system regulates inflammation during experimental autoimmune encephalomyelitis

Extracellular adenosine has an important role in regulating the severity of inflammation during an immune response. Although there are four adenosine receptor (AR) subtypes, the A2AAR is both highly expressed on lymphocytes and known as a prime mediator of adenosine's anti-inflammatory effects. To define the importance of A2AAR signaling during neuroinflammatory disease progression, we used the experimental autoimmune encephalomyelitis (EAE) animal model for multiple sclerosis. In EAE induction experiments, A2AAR antagonist treatment protected mice from disease development and its associated CNS lymphocyte infiltration. However, A2AAR(-/-) mice developed a more severe acute EAE phenotype characterized by more proinflammatory lymphocytes and activated microglia/macrophages. Interestingly, very high levels of A2AAR were expressed on the choroid plexus, a well-established CNS lymphocyte entry point. To determine the contribution of A2AAR signaling in lymphocytes and the CNS during EAE, we used bone marrow chimeric mice. Remarkably, A2AAR(-/-) donor hematopoietic cells potentiated severe EAE, whereas lack of A2AAR expression on nonhematopoietic cells protected against disease development. Although no defect in the suppressive ability of A2AAR(-/-) regulatory T cells was observed, A2AAR(-/-) lymphocytes were shown to proliferate more and produced more IFN-γ following stimulation. Despite this more proinflammatory phenotype, A2AAR antagonist treatment still protected against EAE when A2AAR(-/-) lymphocytes were adoptively transferred to T cell-deficient A2AAR(+/+) mice. These results indicate that A2AAR expression on nonimmune cells (likely in the CNS) is required for efficient EAE development, while A2AAR lymphocyte expression is essential for limiting the severity of the inflammatory response.

Trauma equals danger--damage control by the immune system

Traumatic injuries induce a complex host response that disrupts immune system homeostasis and predisposes patients to opportunistic infections and inflammatory complications. The response to injuries varies considerably by type and severity, as well as by individual variables, such as age, sex, and genetics. These variables make studying the impact of trauma on the immune system challenging. Nevertheless, advances have been made in understanding how injuries influence immune system function as well as the immune cells and pathways involved in regulating the response to injuries. This review provides an overview of current knowledge about how traumatic injuries affect immune system phenotype and function. We discuss the current ideas that traumatic injuries induce a unique type of a response that may be triggered by a combination of endogenous danger signals, including alarmins, DAMPs, self-antigens, and cytokines. Additionally, we review and propose strategies for redirecting injury responses to help restore immune system homeostasis.

Sercarzian immunology--In memoriam. Eli E. Sercarz, 1934-2009

During his long career as a principal investigator and educator, Eli Sercarz trained over 100 scientists. He is best known for developing hen egg white lysozyme (HEL) as a model antigen for immunologic studies. Working in his model system Eli furthered our understanding of antigen processing and immunologic tolerance. His work established important concepts of how the immune system recognizes antigenic determinants processed from whole protein antigens; specifically he developed the concepts of immunodominance and crypticity. Later in his career he focused more on autoimmunity using a variety of established animal models to develop theories on how T cells can circumvent tolerance induction and how an autoreactive immune response can evolve over time. His theory of "determinant spreading" is one of the cornerstones of our modern understanding of autoimmunity. This review covers Eli's entire scientific career outlining his many seminal discoveries.

IL-1β and TNFα-initiated IL-6-STAT3 pathway is critical in mediating inflammatory cytokines and RANKL expression in inflammatory arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that causes irreversible joint damage and significant disability. However, the fundamental mechanisms underlying how inflammation and joint destruction in RA develop and are sustained chronically remain largely unknown. Here, we show that signal transducer and activator of transcription 3 (STAT3) is the key mediator of both chronic inflammation and joint destruction in RA. We found that inflammatory cytokines highly expressed in RA patients, such as IL-1β, tumor necrosis factor alpha and IL-6, activated STAT3 either directly or indirectly and in turn induced expression of IL-6 family cytokines, further activating STAT3 in murine osteoblastic and fibroblastic cells. STAT3 activation also induced expression of receptor activator of nuclear factor kappa B ligand (RANKL), a cytokine essential for osteoclastogenesis, and STAT3 deficiency or pharmacological inhibition promoted significant reduction in expression of both IL-6 family cytokines and RANKL in vitro. STAT3 inhibition was also effective in treating an RA model, collagen-induced arthritis, in vivo through significant reduction in expression of IL-6 family cytokines and RANKL, inhibiting both inflammation and joint destruction. Leukemia inhibitory factor expression and STAT3 activation by IL-1β were mainly promoted by IL-6 but still induced in IL-6-deficient cells. Thus, our data provide new insight into RA pathogenesis and provide evidence that inflammatory cytokines trigger a cytokine amplification loop via IL-6-STAT3 that promotes sustained inflammation and joint destruction.

Role for MyD88, TLR2 and TLR9 but not TLR1, TLR4 or TLR6 in experimental autoimmune encephalomyelitis

The potential roles of TLRs in the cause and pathogenesis of autoimmune CNS inflammation remain contentious. In this study, we examined the effects of targeted deletions of TLR1, TLR2, TLR4, TLR6, TLR9, and MyD88 on the induction of myelin oligodendrocyte glycoprotein 35-55 (MOG(35-55)) peptide/CFA/pertussis toxin-induced autoimmune encephalomyelitis. Although C57BL/6.Tlr1(-/-), C57BL/6.Tlr4(-/-) and C57BL/6.Tlr6(-/-) mice showed normal susceptibility to disease, signs were alleviated in female C57BL/6.Tlr2(-/-) and C57BL/6.Tlr9(-/-) mice and C57BL/6.Tlr2/9(-/-) mice of both sexes. C57BL/6.Myd88(-/-) mice were completely protected. Lower clinical scores were associated with reduced leukocyte infiltrates. These results were confirmed by passive adoptive transfer of disease into female C57BL/6.Tlr2(-/-) and C57BL/6.Tlr9(-/-) mice, where protection in the absence of TLR2 was associated with fewer infiltrating CD4(+) cells in the CNS, reduced prevalence of detectable circulating IL-6, and increased proportions of central (CD62L(+)) CD4(+)CD25(+)Foxp3(+) regulatory T cells. These results provide a potential molecular mechanism for the observed effects of TLR signaling on the severity of autoimmune CNS inflammation.

CD8alpha+ dendritic cells prime TCR-peptide-reactive regulatory CD4+FOXP3- T cells

CD4(+) T cells with immune regulatory function can be either FOXP3(+) or FOXP3(-). We have previously shown that priming of naturally occurring TCR-peptide-reactive CD4(+)FOXP3(-) Treg specifically controls Vbeta8.2(+)CD4(+) T cells mediating EAE. However, the mechanism by which these Treg are primed to recognize their cognate antigenic determinant, which is derived from the TCRVbeta8.2-chain, is not known. In this study we show that APC derived from splenocytes of naïve mice are able to stimulate cloned CD4(+) Treg in the absence of exogenous antigen, and their stimulation capacity is augmented during EAE. Among the APC populations, DC were the most efficient in stimulating the Treg. Stimulation of CD4(+) Treg was dependent upon processing and presentation of TCR peptides from ingested Vbeta8.2TCR(+)CD4(+) T cells. Additionally, DC pulsed with TCR peptide or apoptotic Vbeta8.2(+) T cells were able to prime Treg in vivo and mediate protection from disease in a CD8-dependent fashion. These data highlight a novel mechanism for the priming of CD4(+) Treg by CD8alpha(+) DC and suggest a pathway that can be exploited to prime antigen-specific regulation of T-cell-mediated inflammatory disease.

Regulatory T cells and human myeloid dendritic cells promote tolerance via programmed death ligand-1

Immunotherapy using regulatory T cells (Treg) has been proposed, yet cellular and molecular mechanisms of human Tregs remain incompletely characterized. Here, we demonstrate that human Tregs promote the generation of myeloid dendritic cells (DC) with reduced capacity to stimulate effector T cell responses. In a model of xenogeneic graft-versus-host disease (GVHD), allogeneic human DC conditioned with Tregs suppressed human T cell activation and completely abrogated posttransplant lethality. Tregs induced programmed death ligand-1 (PD-L1) expression on Treg-conditioned DC; subsequently, Treg-conditioned DC induced PD-L1 expression in vivo on effector T cells. PD-L1 blockade reversed Treg-conditioned DC function in vitro and in vivo, thereby demonstrating that human Tregs can promote immune suppression via DC modulation through PD-L1 up-regulation. This identification of a human Treg downstream cellular effector (DC) and molecular mechanism (PD-L1) will facilitate the rational design of clinical trials to modulate alloreactivity.

Intragraft selection of the T cell receptor repertoire by class I MHC sequences in tolerant recipients

BACKGROUND

Allograft tolerance of ACI (RT1(a)) recipients to WF (RT1(u)) hearts can be induced by allochimeric class I MHC molecules containing donor-type (RT1A(u)) immunogenic epitopes displayed on recipient-type (RT1A(a)) sequences. Here, we sought the mechanisms by which allochimeric sequences may affect responding T cells through T cell receptor (TCA) repertoire restriction.

METHODOLOGY/PRINCIPAL FINDINGS

The soluble [alpha(1h) (u)]-RT1.A(a) allochimeric molecule was delivered into ACI recipients of WF hearts in the presence of sub-therapeutic dose of cyclosporine (CsA). The TCR Vbeta spectrotyping of the splenocytes and cardiac allografts showed that the Vbeta gene families were differentially expressed within the TCR repertoire in allochimeric- or high-dose CsA-treated tolerant recipients at day +5 and +7 of post-transplantation. However, at day 30 of post-transplantation the allochimeric molecule-treated rats showed the restriction of TCR repertoire with altered dominant size peaks representing preferential clonal expansion of Vbeta7, Vbeta11, Vbeta13, Vbeta 14, and Vbeta15 genes. Moreover, we found a positive correlation between the alteration of Vbeta profile, restriction of TCR repertoire, and the establishment of allograft tolerance.

CONCLUSIONS

Our findings indicate that presentation of allochimeric MHC class I sequences that partially mimic donor and recipient epitopes may induce unique tolerant state by selecting alloresponsive Vbeta genes.

Lithium prevents and ameliorates experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) models, in animals, many characteristics of multiple sclerosis, for which there is no adequate therapy. We investigated whether lithium, an inhibitor of glycogen synthase kinase-3 (GSK3), can ameliorate EAE in mice. Pretreatment with lithium markedly suppressed the clinical symptoms of EAE induced in mice by myelin oligodendrocyte glycoprotein peptide (MOG35-55) immunization and greatly reduced demyelination, microglia activation, and leukocyte infiltration in the spinal cord. Lithium administered postimmunization, after disease onset, reduced disease severity and facilitated partial recovery. Conversely, in knock-in mice expressing constitutively active GSK3, EAE developed more rapidly and was more severe. In vivo lithium therapy suppressed MOG35-55-reactive effector T cell differentiation, greatly reducing in vitro MOG35-55- stimulated proliferation of mononuclear cells from draining lymph nodes and spleens, and MOG35-55-induced IFN-gamma, IL-6, and IL-17 production by splenocytes isolated from MOG35-55-immunized mice. In relapsing/remitting EAE induced with proteolipid protein peptide139-151, lithium administered after the first clinical episode maintained long-term (90 days after immunization) protection, and after lithium withdrawal the disease rapidly relapsed. These results demonstrate that lithium suppresses EAE and identify GSK3 as a new target for inhibition that may be useful for therapeutic intervention of multiple sclerosis and other autoimmune and inflammatory diseases afflicting the CNS.

Immunodominance in the TCR repertoire of a [corrected] TCR peptide-specific CD4+ Treg population that controls experimental autoimmune encephalomyelitis

Immunodominance in self-Ag-reactive pathogenic CD4(+) T cells has been well established in several experimental models. Although it is clear that regulatory lymphocytes (Treg) play a crucial role in the control of autoreactive cells, it is still not clear whether immunodominant CD4(+) Treg clones are also involved in control of autoreactivity. We have shown that TCR-peptide-reactive CD4(+) and CD8(+) Treg play an important role in the spontaneous recovery and resistance from reinduction of experimental autoimmune encephalomyelitis in B10.PL mice. We report, by sequencing of the TCR alpha- and beta-chain associated with CD4(+) Treg, that the TCR repertoire is limited and the majority of CD4(+) Treg use the TCR Vbeta14 and Valpha4 gene segments. Interestingly, sequencing and spectratyping data of cloned and polyclonal Treg populations revealed that a dominant public CD4(+) Treg clonotype expressing Vbeta14-Jbeta1.2 with a CDR3 length of 7 aa exists in the naive peripheral repertoire and is expanded during the course of recovery from experimental autoimmune encephalomyelitis. Furthermore, a higher frequency of CD4(+) Treg clones in the naive repertoire correlates with less severity and more rapid spontaneous recovery from disease in parental B10.PL or PL/J and (B10.PL x PL/J)F(1) mice. These findings suggest that unlike the Ag-nonspecific, diverse TCR repertoire among the CD25(+)CD4(+) Treg population, TCR-peptide-reactive CD4(+) Treg involved in negative feedback regulation of autoimmunity use a highly limited TCR V-gene repertoire. Thus, a selective set of immunodominant Treg as well as pathogenic T cell clones can be targeted for potential intervention in autoimmune disease conditions.

Synergistic antitumor effect of chemotactic-prostate tumor-associated antigen gene-modified tumor cell vaccine and anti-CTLA-4 mAb in murine tumor model

In this study, we demonstrate that an effective immune response against prostate tumors in mouse tumor model can be elicited using a strategy that combines CTLA-4 blockade and pSLC-3P-Fc-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). Treatment of B16F10-3P-bearing mice resulted in a significant reduction in tumor incidence as assessed 2 months after treatment. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8+ T cells and CD4+ T lymphocytes were required for the induction of CD8+ CTL response in B16F10-SLC-3P-Fc+anti-CTLA-4 mAb-immunized mice. Moreover, mice that were cured of an established tumor were protected against a rechallenge with the same tumor for at least 4 months, suggesting the generation of memory responses. Adoptive transfer experiments further indicate that antitumor reactivity can be transferred to naïve mice by splenocytes. These findings demonstrate that this combinatorial treatment can elicit a potent anti-tumor immune response and suggest potential of this approach for treatment of prostate cancer.

Lack of effective MUC1 tumor antigen-specific immunity in MUC1-transgenic mice results from a Th/T regulatory cell imbalance that can be corrected by adoptive transfer of wild-type Th cells

Glycoprotein tumor Ag MUC1 is overexpressed on the majority of epithelial adenocarcinomas. CTLs that recognize MUC1 and can kill tumor cells that express this molecule have been found in cancer patients, yet they are present in low frequency and unable to eradicate MUC1(+) tumors. Patients also make anti-MUC1 Abs but predominantly of the IgM isotype reflecting the lack of effective MUC1-specific Th responses. Mice transgenic for the human MUC1 gene (MUC1-Tg) are similarly hyporesponsive to MUC1. We used a vaccine consisting of dendritic cells loaded with a long synthetic MUC1 peptide to investigate the fate and function of MUC1-specific CD4(+) Th elicited in wild-type (WT) or MUC1-Tg mice or adoptively transferred from vaccinated WT mice. We show that hyporesponsiveness of MUC1-Tg mice to this vaccine is a result of insufficient expansion of Th cells, while at the same time their regulatory T cells are efficiently expanded to the same extent as in WT mice and exert a profound suppression on MUC1-specific B and T cell responses in vivo. Adoptive transfer of WT Th cells relieved this suppression and enhanced T and B cell responses to subsequent MUC1 immunization. Our data suggest that the balance between Th and regulatory T cells is a critical parameter that could be modulated to improve the response to cancer vaccines.

A Potential Side Effect of Cyclosporin A: Inhibition of CD4+CD25+ Regulatory T Cells in Mice

BACKGROUND

CD4CD25 regulatory T (Treg) cells are essential for the induction and maintenance of immunologic self-tolerance as well as transplant tolerance. The effects of cyclosporin A (CsA), a widely used immunosuppressive agent, on CD4CD25Treg cells in mice were investigated.

METHODS

Balb/c mice were injected with CsA or control solution for one month. The levels, phenotype, and function of CD4CD25Treg cells in these mice were then assayed.

RESULTS

The percentages and total cell numbers of CD4CD25Treg cells in the peripheral blood and spleen were significantly reduced after the treatment with CsA. The total numbers of CD4CD25Treg cells in the thymus of CsA-treated mice were markedly reduced as compared to the control mice. However, the percentage of CD4CD25Treg cells in the thymus of CsA-treated mice was markedly enhanced. More CD4CD25Treg cells expressing high levels of CD44 and CD45RB, and less CD4CD25Treg cells expressing CD62L were observed in CsA-treated mice, compared with the control mice. CD4CD25Treg cells expressed slightly lower levels of Foxp3 in CsA-treated mice. Furthermore, CsA markedly impaired the immunosuppressive function of CD4CD25Treg cells.

CONCLUSIONS

CsA significantly impaired the development and function of CD4CD25Treg cells. The present studies suggest that CsA may block the potential induction of immune tolerance and increase the susceptibility to develop autoimmune diseases while preventing graft rejection.

Immunotherapy of tumors with protein vaccine based on chicken homologous Tie-2

PURPOSE

Tie-2 is an endothelium-specific receptor tyrosine kinase known to play a key role in tumor angiogenesis. The present study explores the feasibility of immunotherapy of tumors by using a protein vaccine based on chicken Tie-2 as a model antigen to break the immune tolerance against Tie-2 in a cross-reaction between the xenogeneic homologous and self-Tie-2.

EXPERIMENTAL DESIGN AND RESULTS

In this study, a chicken homologous Tie-2 protein vaccine (chTie-2) and a corresponding mouse Tie-2 vaccine as a control were prepared and the antitumor effect of these vaccines was tested in two tumor models (murine B16F10 melanoma and murine H22 hepatoma). Immunotherapy with chTie-2 was found effective in two tumor models. Autoantibodies against mouse Tie-2 were detected in sera of mice immunized with chTie-2 through Western blot analysis and ELISA assay. Anti-Tie-2 antibody-producing B cells were detectable by ELISPOT. Histologic examination revealed that autoantibodies were deposited on the endothelial cells of tumor tissues. Purified immunoglobulins from chTie-2-immunized mice could induce the apoptosis of human umbilical vein endothelial cells in vitro. Importantly, adoptive transfer of purified immunoglobulins led to antitumor effect in vivo; apparently, angiogenesis was significantly inhibited in these tumors. Furthermore, the antitumor activity and production of autoantibodies could be abrogated by depletion of CD4+ T lymphocytes.

CONCLUSIONS

Our findings may provide a vaccine strategy for cancer therapy and show the potential utilization of interference with Tie-2 pathway.

Autologous immune strategies to reduce the risk of leukemic relapse: Consideration for IL-15

The graft-versus-leukemia effect following allogeneic stem cell transplantation (SCT) reduces the incidence of leukemic relapse and establishes that effector cells can eliminate or at least contain resistant leukemic stem cells. Natural killer cells also appear to play a role in directly lowering the rate of relapse following allogeneic SCT in patients with acute myeloid leukemia. To date, however, effective prevention of leukemic relapse by autologous immune effector cells has not been demonstrated. This article examines some of the challenges that limit autologous antileukemia immunity as well as some possible immunotherapeutic approaches that may help control leukemic relapse following autologous SCT.

Feedback regulation of autoimmunity via TCR-centered regulation

The complexity of a self-regulatory system demands a balance between effectors and regulators; that is, it is necessary for both cell types to exist. Regulation of self-reactive T cells can occur at several complementary but different levels: (1) at the level of priming itself: for example, inhibition of expansion of antigen-reactive T cells by regulatory CD4+ CD25+ T cells; (2) after the priming of self-reactive T cells, regulatory T-cell populations with reactivity to distinct self-determinants derived from the T-cell receptor (TCR) can be engaged via a negative feedback mechanism. Thus, these mechanisms ensure induction of effective and appropriately limited responses against foreign antigens while preventing autoreactivity from inflicting self-damage.

Homeostatic control of immunity by TCR peptide-specific Tregs

Regulation of the immune response is a multifaceted process involving lymphocytes that function to maintain both self tolerance as well as homeostasis following productive immunity against microbes. There are 2 broad categories of Tregs that function in different immunological settings depending upon the context of antigen exposure and the nature of the inflammatory response. During massive inflammatory conditions such as microbial exposure in the gut or tissue transplantation, regulatory CD4+CD25+ Tregs broadly suppress priming and/or expansion of polyclonal autoreactive responses nonspecifically. In other immune settings where initially a limited repertoire of antigen-reactive T cells is activated and expanded, TCR-specific negative feedback mechanisms are able to achieve a fine homeostatic balance. Here I will describe experimental evidence for the existence of a Treg population specific for determinants that are derived from the TCR and are expressed by expanding myelin basic protein-reactive T cells mediating experimental autoimmune encephalomyelitis, an animal prototype for multiple sclerosis. These mechanisms ensure induction of effective but appropriately limited responses against foreign antigens while preventing autoreactivity from inflicting escalating damage. In contrast to CD25+ Tregs, which are most efficient at suppressing priming or activation, these specific Tregs are most efficient in controlling T cells following their activation.

Suppression of autoimmune disease after vaccination with autoreactive T cells that express Qa-1 peptide complexes

The ability of autoreactive T cells to provoke autoimmune disease is well documented. The finding that immunization with attenuated autoreactive T cells (T cell vaccination, or TCV) can induce T cell-dependent inhibition of autoimmune responses has opened the possibility that regulatory T cells may be harnessed to inhibit autoimmune disease. Progress in the clinical application of TCV, however, has been slow, in part because the underlying mechanism has remained clouded in uncertainty. We have investigated the molecular basis of TCV-induced disease resistance in two murine models of autoimmunity: herpes simplex virus-1 (KOS strain)-induced herpes stromal keratitis and murine autoimmune diabetes in non-obese diabetic (NOD) mice. We find that the therapeutic effects of TCV depend on activation of suppressive CD8 cells that specifically recognize Qa-1-bound peptides expressed by autoreactive CD4 cells. We clarify the molecular interaction between Qa-1 and self peptides that generates biologically active ligands capable of both inducing suppressive CD8 cells and targeting them to autoreactive CD4 cells. These studies suggest that vaccination with peptide-pulsed cells bearing the human equivalent of murine Qa-1 (HLA-E) may represent a convenient and effective clinical approach to cellular therapy of autoimmune disease.

Genomic absence of the gene encoding T cell receptor Vbeta7.2 is linked to the presence of autoantibodies in Sjögren's syndrome

OBJECTIVE

It is not yet known whether the absence of certain T cell receptor V(beta) (TCRBV) genes (e.g., due to genomic deletion) has functional significance. We examined this question in relation to a known 21.6-kb insertion/deletion-related polymorphism (IDRP) in the human BV locus.

METHODS

New polymerase chain reaction (PCR) genotyping methods were used. Monoclonal antibodies to TCRBV gene products were used to confirm the absence of the relevant proteins. Patients with Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) were compared with normal controls with regard to TCR genotypes and serologic profiles.

RESULTS

There are 3 known haplotypes (I, D1, D2) and 6 possible genotypes related to the 21.6-kb IDRP. Novel PCR-based methods were used to define these genotypes. In subjects with deleted/deleted (D/D) genotypes, T cells could not express V(beta)7.2 TCRs, as assayed with a new antibody specific for V(beta)7.2. This was the sole significant difference between subjects without the insertion and those with either 1 or 2 copies. Surprisingly, we found that the D/D genotype was associated with primary SS, but only when pathogenic autoantibodies were present.

CONCLUSION

These results suggest that T cells expressing TCRs with V(beta)7.2 are protective against a pathogenic immune response in SS. Thus, genomic polymorphism of TCR genes (along with the correct HLA alleles) determines whether T cells can direct a pathogenic autoimmune response.

Immunotherapy of tumors with vaccine based on quail homologous vascular endothelial growth factor receptor-2

The breaking of immune tolerance of "self-antigens" associated with angiogenesis is an attractive approach to cancer therapy by active immunity. We used vascular endothelial growth factor receptor-2 (VEGFR-2) as a model antigen to explore the feasibility of the immunotherapy with a vaccine based on a xenogeneic homologous protein. To test this concept, we prepared a quail homologous VEGFR-2 protein vaccine (qVEGFR) based on quail VEGFR-2. At the same time, a protein vaccine based on the corresponding ligand-binding domain of mouse self-VEGFR-2 (mVEGFR) was also prepared and used as a control. We found that immunotherapy with qVEGFR was effective at protective and therapeutic antitumor immunity in several solid and hematopoietic tumor models in mice. Autoantibodies against mouse VEGFR-2 (Flk-1) were identified by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Anti-VEGFR antibody-producing B cells were detectable by ELISPOT. Endothelial deposition of immunoglobulins developed within tumor. VEGF-mediated endothelial cell proliferation was inhibited in vitro by immunoglobulins from qVEGFR-immunized mice. Antitumor activity was caused by the adoptive transfer of the purified immunoglobulins. Antitumor activity and production of autoantibodies against Flk-1 could be abrogated by the depletion of CD4+ T lymphocytes. Angiogenesis was apparently inhibited within the tumors, and the vascularization of alginate beads was also reduced. No marked toxicity was found in the immunized mice. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factor receptor associated with angiogenesis in a cross-reaction with single xenogeneic homologous protein.

Inhibition of tumor growth with a vaccine based on xenogeneic homologous fibroblast growth factor receptor-1 in mice

Angiogenesis is important for the growth of solid tumors. The breaking of the immune tolerance against the molecule associated with angiogenesis should be a useful approach for cancer therapy. However, the immunity to self-molecules is difficult to elicit by a vaccine based on autologous or syngeneic molecules due to immune tolerance. Basic fibroblast growth factor (bFGF) is a specific and potent angiogenic factor implicated in tumor growth. The biological activity of bFGF is mediated through interaction with its high-affinity receptor, fibroblast growth factor receptor-1 (FGFR-1). In this study, we selected Xenopus FGFR-1 as a model antigen by the breaking of immune tolerance to explore the feasibility of cancer therapy in murine tumor models. We show here that vaccination with Xenopus FGFR-1 (pxFR1) is effective at antitumor immunity in three murine models. FGFR-1-specific autoantibodies in sera of pxFR1-immunized mice could be found in Western blotting analysis. The purified immunoglobulins were effective at the inhibition of endothelial cell proliferation in vitro and at the antitumor activity in vivo. The antitumor activity and production of FGFR-1-specific autoantibodies could be abrogated by depletion of CD4+ T lymphocytes. Histological examination revealed that the autoantibody was deposited on the endothelial cells within tumor tissues from pxFR1-immunized mice, and intratumoral angiogenesis was significantly suppressed. Furthermore, the inhibition of angiogenesis could also be found in alginate-encapsulate tumor cell assay. These observations may provide a new vaccine strategy for cancer therapy through the induction of autoimmunity against FGFR-1 associated with angiogenesis in a cross-reaction.

Immunogene therapy of tumors with vaccine based on xenogeneic epidermal growth factor receptor

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4(+) T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8(+) cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8(+)) or CD8-depleted (CD4(+)) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-gamma and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.

Regulatory T cells control autoimmunity in vivo by inducing apoptotic depletion of activated pathogenic lymphocytes

Clinical autoimmunity requires both activation of self-reactive T cells as well as a failure of peripheral tolerance mechanisms. We previously identified one such mechanism that involves regulatory T cells recognizing TCR V beta 8.2 chain-derived peptides in the context of MHC. How this regulation affects the fate of target V beta 8.2(+) T lymphocytes in vivo that mediate experimental autoimmune encephalomyelitis has remained unknown. The present study using immunoscope and CFSE-labeling analysis demonstrates that the expansion of regulatory CD4 and CD8 T cells in vivo results in apoptotic depletion of the dominant, myelin basic protein-reactive V beta 8.2(+) T cells, but not subdominant V beta 13(+) T cells. The elimination of only activated T cells by this negative feedback mechanism preserves the remainder of the naive V beta 8.2(+) T cell repertoire and at the same time results in protection from disease. These studies are the first in clearly elucidating the fate of myelin basic protein-specific encephalitogenic T cells in vivo following regulation.

Protection against experimental autoimmune encephalomyelitis generated by a recombinant adenovirus vector expressing the V beta 8.2 TCR is disrupted by coadministration with vectors expressing either IL-4 or -10

Adenovirus vectors are increasingly being used for genetic vaccination and may prove highly suitable for intervention in different pathological conditions due to their capacity to generate high level, transient gene expression. In this study, we report the use of a recombinant adenovirus vector to induce regulatory responses for the prevention of autoimmune diseases through transient expression of a TCR beta-chain. Immunization of B10.PL mice with a recombinant adenovirus expressing the TCR Vbeta8.2 chain (Ad5E1 mVbeta8.2), resulted in induction of regulatory type 1 CD4 T cells, directed against the framework region 3 determinant within the B5 peptide (aa 76-101) of the Vbeta8.2 chain. This determinant is readily processed and displayed in an I-A(u) context, on ambient APC. Transient genetic delivery of the TCR Vbeta8.2 chain protected mice from Ag-induced experimental autoimmune encephalomyelitis. However, when the Ad5E1 mVbeta8.2 vector was coadministered with either an IL-4- or IL-10-expressing vector, regulation was disrupted and disease was exacerbated. These results highlight the importance of the Th1-like cytokine requirement necessary for the generation and activity of effective regulatory T cells in this model of experimental autoimmune encephalomyelitis.

Endogenous CD4+BV8S2- T cells from TG BV8S2+ donors confer complete protection against spontaneous experimental encephalomyelitis (Sp-EAE) in TCR transgenic, RAG-/- mice

To investigate regulatory mechanisms which naturally prevent autoimmune diseases, we adopted the genetically restricted immunodeficient (RAG-1(-/-)) myelin basic protein (MBP)-specific T cell receptor (TCR) double transgenic (T/R-) mouse model of spontaneous experimental autoimmune encephalomyelitis (Sp-EAE). Sp-EAE can be prevented after transfer of CD4+splenocytes from naïve immunocompetent mice. RAG-1+ double transgenic (T/R+) mice do not develop Sp-EAE due to the presence of a very small population (about 2%) of non-Tg TCR specificities. In this study, CD4+BV8S2+ T cells that predominate in T/R+ mice, and three additional populations, CD4+BV8S2-, CD4-CD8-BV8S2+, and CD4-CD8+BV8S2+ T cells that expanded in T/R+ mice after immunization with MBP-Ac1-11 peptide, were studied for their ability to prevent Sp-EAE in T/R- mice. Only the CD4+BV8S2- T cell population conferred complete protection against Sp-EAE, similar to unfractionated splenocytes from non-Tg donors, whereas CD4-CD8-BV8S2+ and CD4+BV8S2+ T cells conferred partial protection. In contrast, CD4-CD8+BV8S2+ T cells had no significant protective effects. The highly protective CD4+BV8S2- subpopulation was CD25+, contained non-clonotypic T cells, and uniquely expressed the CCR4 chemokine receptor. Protected recipient T/R- mice had marked increases in CD4+CD25+ Treg-like cells, retention of the pathogenic T cell phenotype in the spleen, and markedly reduced inflammation in CNS tissue. Partially protective CD4+BV8S2+ and CD4- CD8-BV8S2+ subpopulations appeared to be mainly clonotypic T cells with altered functional properties. These three Sp-EAE protective T cell subpopulations possessed distinctive properties and induced a variety of effects in T/R- recipients, thus implicating differing mechanisms of protection.

Immunotherapy of tumors with vaccines based on xenogeneic homologous molecules

This review summarizes and discusses a new vaccine strategy based on xenogeneic homologous molecules by the breaking of immune tolerance against the growth factors or their receptors associated with tumor growth in a cross-reaction between the xenogeneic homologs and self-molecules. The xenogeneic vaccine may circumvent the fact that few tumor-specific antigens have been identified in human solid tumors and that the host usually shows immune tolerance to self-molecules as antigens. It may be of importance for the further exploration of the applications of xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Immunogene therapy of tumors with a vaccine based on the ligand-binding domain of chicken homologous integrin beta3

The breaking of immune tolerance against angiogenesis-associated molecules should be a useful approach for cancer therapy by active immunity. We used chicken integrin beta3 as a model antigen to explore the feasibility of immunogene therapy of the tumors with a vaccine based on a single xenogeneic homologous gene, targeting the molecules associated with angiogenesis. To test this concept we constructed a plasmid DNA encoding the ligand-binding domain of chicken integrin beta3 (P-BD-C) and control vectors. We found that immunogene therapy of tumors with a vaccine based on the ligand-binding domain of chicken integrin beta3 (P-BD-C) was effective in both protective and therapeutic anti-tumor immunity in several tumor models in mice. Autoantibodies against integrin beta3 in sera of mice immunized with the ligand-binding domain of chicken integrin beta3 could be found by Western blot analysis and ELISA assay. The purified immunoglobulins were effective in the inhibition of endothelial cell proliferation in vitro, and in anti-tumor activity as well as in the inhibition of angiogenesis by adoptive transfer in vivo. The anti-tumor activity and the production of integrin beta3-specific autoantibodies (manifested by significantly elevated Ig G1 and Ig G2b) could be abrogated by the depletion of CD4+ T lymphocytes. These observations may provide a vaccine strategy for cancer therapy through the induction of the autoimmunity against the molecules associated with tumor growth in a cross-reaction with a single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Regulatory T cells overexpress a subset of Th2 gene transcripts

There is now compelling evidence for subpopulations of CD4+ T cells whose role is to prevent immune pathology in both autoimmunity and transplantation. We have cloned CD4+ T cells against a male transplantation Ag that, unlike Th1 or Th2 clones, suppresses the rejection of male skin grafts and are therefore considered examples of regulatory T cells. We have identified, using serial analysis of gene expression, transcripts that are overexpressed in regulatory T cells compared with Th1 and Th2 clones. Some of these transcripts are increased in tolerated rather than rejecting skin grafts and in addition are expressed by the natural regulatory CD4+CD25+ subpopulation of naive mice. These genes include prepro-enkephalin, GM2 ganglioside activator protein, glucocorticoid-induced TNFR superfamily member 18, and integrin alpha(E)beta(7). They seem to represent a subset of transcripts shared with Th2 cells, suggesting that transplantation tolerance and normal immunoregulation may represent a unique form of Th2-like differentiation.

Activation of natural killer T cells potentiates or prevents experimental autoimmune encephalomyelitis

Natural killer (NK) T cells recognize lipid antigens in the context of the major histocompatibility complex (MHC) class 1-like molecule CD1 and rapidly secrete large amounts of the cytokines interferon (IFN)-gamma and interleukin (IL)-4 upon T cell receptor (TCR) engagement. We have asked whether NK T cell activation influences adaptive T cell responses to myelin antigens and their ability to cause experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. While simultaneous activation of NK T cells with the glycolipid alpha-galactosylceramide (alpha-GalCer) and myelin-reactive T cells potentiates EAE in B10.PL mice, prior activation of NK T cells protects against disease. Exacerbation of EAE is mediated by an enhanced T helper type 1 (Th1) response to myelin basic protein and is lost in mice deficient in IFN-gamma. Protection is mediated by immune deviation of the anti-myelin basic protein (MBP) response and is dependent upon the secretion of IL-4. The modulatory effect of alpha-GalCer requires the CD1d antigen presentation pathway and is dependent upon the nature of the NK T cell response in B10.PL or C57BL/6 mice. Because CD1 molecules are nonpolymorphic and remarkably conserved among different species, modulation of NK T cell activation represents a target for intervention in T cell-mediated autoimmune diseases.

T-cell vaccination for autoimmune disease: a panorama

T-cell vaccination refers to a form of cell therapy, usually autologous, aimed at curing or ameliorating autoimmune diseases. This review considers five questions: What is TCV? How is it done? How does it work? Why does it work? And what is its future?

Induction of TCR Vbeta-specific CD8+ CTLs by TCR Vbeta-derived peptides bound to HLA-E

Previous studies have identified murine and human regulatory CD8+ T cells specific for TCR-Vbeta families expressed on autologous activated CD4+ T cells. In the mouse, these regulatory CD8+ T cells were shown to be restricted by the MHC class Ib molecule, Qa-1. In the present study, we asked whether HLA-E, the human functional equivalent of Qa-1, binds Vbeta peptides and whether the HLA-E/Vbeta-peptide complex induces and restricts human CD8+ CTLs. We first created stable HLA-E gene transfectants of the C1R cell line (C1R-E). Two putative HLA-E binding nonapeptides identified in human TCR Vbeta1 and Vbeta2 chains (SLELGDSAL and LLLGPGSGL, respectively) were shown to bind to HLA-E. CD8+ T cells could be primed in vitro by C1R-E cells loaded with the Vbeta1 (C1R-E/V1) or Vbeta2 (C1R-E/V2) peptide to preferentially kill C1R-E cells loaded with the respective inducing Vbeta peptide, compared with targets loaded with the other peptides. Priming CD8+ T cells with untreated C1R-E cells did not induce Vbeta-specific CTLs. Of perhaps more physiological relevance was the finding that the CD8+ CTLs primed by C1R-E/V1 also preferentially killed activated autologous TCR Vbeta1+. Similar results were observed in reciprocal experiments using C1R-E/V2 for priming. Furthermore, anti-CD8 and anti-MHC class I mAbs inhibited this Vbeta-specific killing of C1R-E and CD4+ T cell targets. Taken together, the data provide evidence that certain TCR-Vbeta peptides can be presented by HLA-E to further induce Vbeta-specific CD8+ CTLs.

Immunogene therapy of tumors with vaccine based on Xenopus homologous vascular endothelial growth factor as a model antigen

Overcoming immune tolerance of the growth factors associated with tumor growth should be a useful approach to cancer therapy by active immunity. We used vascular endothelial growth factor (VEGF) as a model antigen to explore the feasibility of the immunogene tumor therapy with a vaccine based on a single xenogeneic homologous gene, targeting the growth factors associated with angiogenesis. To test this concept, we constructed a plasmid DNA encoding Xenopus homologous VEGF (XVEGF-p) and control vectors. We found that immunogene tumor therapy with a vaccine based on XVEGF was effective at both protective and therapeutic antitumor immunity in several tumor models in mice. VEGF-specific autoantibodies in sera of mice immunized with XVEGF-p could be found in Western blotting analysis and ELISA assay. The purified immunoglobulins were effective at the inhibition of VEGF-mediated endothelial cell proliferation in vitro, and at antitumor activity and the inhibition of angiogenesis by adoptive transfer in vivo. The elevation of VEGF in the sera of the tumor-bearing mice could be abrogated with XVEGF-p immunization. The antitumor activity and production of VEGF-specific autoantibodies, significantly elevated IgG1 and IgG2b, could be abrogated by the depletion of CD4(+) T lymphocytes. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factors associated with tumor growth in a cross reaction with single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Evidence of T cell clonality in the infectious tolerance pathway: implications toward identification of regulatory T cells

We have shown that a rare population of regulatory CD4+ T cells plays a key role in the acquisition of infectious tolerance in rat sensitized recipients of cardiac allografts pretreated with nondepleting anti-CD4 mAb. This study was designed to analyze the TCR Vbeta expression patterns in this transplantation model. First, we used Vbeta-specific RT-PCR to show that there was no differential usage of TCR Vbeta genes by T cells mediating rejection or tolerance. Indeed, graft-infiltrating lymphocytes expressed most of the 22 known rat TCR Vbeta genes in both recipient groups, suggesting unrestricted TCR Vbeta repertoire in alloreactive T cells. Then, we applied CDR3 spectrotyping of TCR beta-chain to assess the clonality of T cells at different anatomic sites. CDR3 size restriction, indicative of the presence of T cell clones, was observed in graft-infiltrating lymphocytes but not in draining lymph nodes or spleen of tolerant hosts. Consisent with the clonal expansion, T cells in tolerated grafts exhibited the memory phenotype at a much higher percentage as compared with peripheral lymphoid organs. Moreover, in tolerated graft-infiltrating lymphocytes, the CD3 size restriction occurred in limited Vbeta gene families, with Vbeta8.1 and Vbeta18 most frequently detected. Hence, T cells at the graft site of tolerant recipients contain T cell clones expressing selective Vbeta genes. This phenotypic characteristics of the tolerogenic GILs may potentially be used as a novel marker to identify operational regulatory T cells in organ allograft recipients.