UMLS:C0751781 - FACTA Search

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Falling infection rates in the developed world are being matched by a rapidly rising incidence of allergic and autoimmune diseases. This review explores the hypothesis that there is a causal link between these phenomena and that infections can prevent the onset of autoimmune disease. The hypothesis is discussed with particular reference to Type I diabetes in the NOD mouse and the ability of the helminth infection Schistosoma mansoni to prevent its onset. The article addresses the possible mechanisms that underly this protection. The effects of protective pathogen-derived agents on key cells of the innate immune system such as dendritic cells are distinct and include the production of anti-inflammatory cytokines such as IL-10. The most likely mechanisms by which these innate changes prevent the subsequent adaptive autoimmune destruction are: (1) the production of systemically high levels of cytokines that oppose the production of cytokines that drive the autoimmune process - possibly via the action of natural killer T (NKT) cells (2) the induction of regulatory T cells that inhibit the action of autoreactive cells and (3) the production of pathogen-specific T cells that are not autoreactive and compete with autoreactive cells for survival signals such as cytokines and T cell receptor ligation.
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PMID:The impact of infection on the incidence of autoimmune disease. 1496 3

The levels and types of immune responses are determined dependent on the extent of pathogen invasion, reactions to antigens mediated by macrophage-dendritic cells, T cells and antibodies. Recently, accumulating evidence suggests that B cells also play an important role in the regulation of immune responses. Here we have made a review to present a role of B cells in determining the level of immune responses and discussed about the clinical significance of B cell-targeted therapy in patients with autoimmune diseases. Type 1 diabetes is a T cell-mediated autoimmune disease characterized by the destruction of insulin-producing pancreatic beta cells. We and other groups have elucidated that B cells play a critical role in the development of insulitis and diabetes, as B-cell-deficient NOD mice are protected from developing type 1 diabetes. B cells are essential for the T cell receptor clonotype spreading of islet-infiltrating T cells, indicating that B cells may play a role in determining the level of immune responses by antigen presentation to antigen specific T cells. There are now numerous case reports and small series of clinical trials regarding rituximab therapy in autoimmune diseases, such as refractory autoimmune hemolytic anemia, IgM antibody-associated polyneuropathy, systemic lupus erythematosus and rheumatoid arthritis. Rituximab is a genetically engineered chimeric anti-CD 20 monoclonal antibody that is approved for the treatment of lymphoma. CD20 is a B-cell surface antigen that is expressed only on pre- B and mature B cells. Thus, rituximab causes a selective transient depletion of the CD20+ B -cell subpopulation. Rationale and strategy for targeting B cells in the treatment of autoimmune diseases consist of the inhibition of antigen-presentation and co-stimulation that induces T cell expansion and activation. Further careful mechanistic studies are required to develop therapies in patients with autoimmune diseases.
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PMID:[B cells as key contributors in determining the level of immune responses -B-cell-targeted therapy in patients with autoimmune diseases]. 1599 5

iNKT cells are a unique subset of CD1-restricted T lymphocytes that express T cell receptor (TCR) and some NK receptors. iNKT cells express an invariant TCRalpha chain composed of Valpha14-Jalpha18 segments in mice and Valpha24-Jalpha18 segments in humans associated with TCRbeta chains using a restricted set of Vbeta. iNKT cells recognize glycolipid antigens such as alpha-galactosylceramide (alpha-GC) presented by CD1d, non-pormorphic MHC class I-like molecule, and rapidly secrete large amounts of cytokines including IL-4 and IFN-gamma upon activation. Due to its potent ability to produce a variety of cytokines, iNKT cells are involved in a various kinds of immunoregulation. iNKT cells play a regulatory role in some disease models such as type I diabetes in NOD mice. In contrast, iNKT cells exaggerate the pathogenesis such as arthritis, allergic airway inflammation and atherosclerosis. In addition, iNKT cells are an attractive target for immunotherapy because several different synthetic glycolipid antigens to modify the function of iNKT cells are available. In this review, we examine the potential roles of NKT cells in the pathogenesis of a variety of diseases including autoimmunity , allergy, infection and cancer. Additionally, we discuss on the recent advances in glycolipid therapy for these disease models.
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PMID:[iNKT cells, a friend or a foe for autoimmune disease and allergy?]. 1650

Examination of the T cell receptor (TCR) gene repertoire is important in the analysis of the immune status of models, because clonal expansion of T cells permits the identification of specific antigen responses of T cells. Little is known about T-cell immunity in the humanized NOD/SCID mouse model. TCR Vbeta repertoire usage and clonality were analyzed to investigate the distribution and clonal expansion of TCR Vbeta subfamily T cells in NOD/SCID mice transplanted with human cord blood (CB) hematopoietic stem cells. The NOD/SCID mice were sublethally irradiated ((60)Co, 300cGy) to eliminate residual innate immunity in the host. The experimental mice were transplanted intravenously with CB CD34(+) cells sorted by MACS. After 6 weeks, RNA was obtained from peripheral blood, bone marrow and thymus of the study animals. The gene expression and clonality of the TCR Vbeta repertoire were determined by RT-PCR and GeneScan techniques. A restricted range of TCR Vbeta usage was exhibited in the bone marrow of mice, which included TCR Vbeta 1, 2, 9, 13 and 19. Further, oligoclonal expression of some TCR Vbeta subfamilies (Vbeta9, 13, 19) was identified by GeneScan technique. To investigate the reason for oligoclonal expansion of the TCR Vbeta subfamily T cells from CB in mouse models, the T-cell culture with tissue-antigen of NOD/SCID mouse was performed in vitro. The cells from peripheral blood mononuclear cells and bone marrow, spleen, thymus in NOD/SCID mice were frozen and thawed, and used as tissue-antigen. CB mononuclear cells were separately cultured with the component from those murine cells for 15-20 days. Oligoclonal expression or oligoclonal trend of some TCR Vbeta subfamilies (Vbeta10, 11 and Vbeta2, 15, 16, 19) was detected in T cells after stimulation with tissue-antigen of NOD/SCID mouse. Interestingly, a similar clonal expansion of the TCR Vbeta11 subfamily was found in T cells cultured with peripheral blood, bone marrow and spleen respectively. The TCR Vbeta subfamily T cells could be reconstituted in humanized NOD/SCID mouse transplanted with CD34(+) cells from CB. The restricted expression and clonal expansion of some CB T cell clones may be induced by tissue-antigens of NOD/SCID mice.
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PMID:Evaluation of TCR Vbeta subfamily T cell expansion in NOD/SCID mice transplanted with human cord blood hematopoietic stem cells. 1765 60

Foxp3-expressing regulatory T (T reg) cells derive primarily from selection in the thymus. Yet conversion of mature conventional CD4(+) T (T conv) cell lymphocytes can be achieved in several conditions, such as transforming growth factor beta treatment, homeostatic expansion, or chronic exposure to low-dose antigen. Such conversion might provide a means to generate peripheral tolerance by "converting" potentially damaging T cells that react to self-antigens. We tested this hypothesis in mice transgenic for the BDC2.5 T cell receptor (TCR), which is representative of a diabetogenic specificity that is naturally present in NOD mice and reactive against a pancreatic self-antigen. In the thymus, before any exposure to antigen, clonotype-positive T reg and T conv cells express a second TCRalpha chain derived from endogenous loci. High-throughput single-cell sequencing of secondary TCRs of the Valpha2 family showed their joining CDR3alpha regions to be very different in T reg and T conv cell thymocytes. These specific CDR3alpha motifs, thus, provided a "tag" with which to test the actual impact of T conv to T reg cell conversion in response to peripheral self-antigen; should the autoreactive clonotypic TCR induce T conv to T reg cell conversion upon encounter of cognate antigen in the pancreas or draining lymph node, one would expect to detect tag CDR3alpha motifs from T conv cells in the T reg cell populations. Sequencing large numbers of peripheral BDC(+)Valpha2(+) cells showed that little to no conversion occurs in response to this pancreatic autoantigen.
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PMID:TCR-based lineage tracing: no evidence for conversion of conventional into regulatory T cells in response to a natural self-antigen in pancreatic islets. 1772 31

Adoptive transfer of antigen-specific T lymphocytes is an attractive form of immunotherapy for haematological malignancies and cancer. The difficulty of isolating antigen-specific T lymphocytes for individual patients limits the more widespread use of adoptive T cell therapy. The demonstration that cloned T cell receptor (TCR) genes can be used to produce T lymphocyte populations of desired specificity offers new opportunities for antigen-specific T cell therapy. The first trial in humans demonstrated that TCR gene-modified T cells persisted for an extended time period and reduced tumor burden in some patients. The WT1 protein is an attractive target for immunotherapy of leukemia and solid cancer since elevated expression has been demonstrated in AML, CML, MDS and in breast, colon and ovarian cancer. In the past, we have isolated high avidity CTL specific for a WT1-derived peptide presented by HLA-A2 and cloned the TCR alpha and beta genes of a WT1-specific CTL line. The genes were inserted into retroviral vectors for transduction of human peripheral blood T lymphocytes of leukemia patients and normal donors. The treatment of leukemia-bearing NOD/SCID mice with T cells transduced with the WT1-specific TCR eliminated leukemia cells in the bone marrow of most mice, while treatment with T cells transduced with a TCR of irrelevant specificity did not diminish the leukemia burden. In order to improve the safety and efficacy of TCR gene therapy, we have developed lentiviral TCR gene transfer. In addition, we employed strategies to enhance TCR expression while avoiding TCR mis-pairing. It may be possible to generate dominant TCR constructs that can suppress the expression of the endogenous TCR on the surface of transduced T cells. The development of new TCR gene constructs holds great promise for the safe and effective delivery of TCR gene therapy for the treatment of malignancies.
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PMID:WT1-specific T cell receptor gene therapy: improving TCR function in transduced T cells. 1785 29

The Rip2 kinase contains a caspase recruitment domain and has been implicated in the activation of the transcriptional factor NF-kappaB downstream of Toll-like receptors, Nod-like receptors, and the T cell receptor. Although Rip2 has been linked to Nod signaling, how Nod-Rip2 proteins mediate NF-kappaB activation has remained unclear. We find Rip2 required for Nod2-mediated NF-kappaB activation and to a lesser extent mitogen-activated protein kinase activation. We demonstrate that Rip2 and IkappaB kinase-gamma become stably polyubiquitinated upon treatment of cells with the NOD2 ligand, muramyl dipeptide. We also demonstrate a requirement for the E2-conjugating enzyme Ubc13, the E3 ubiquitin ligase Traf6, and the ubiquitin-activated kinase Tak1 in Nod2-mediated NF-kappaB activation. Rip2 polyubiquitination is also stimulated when macrophages are infected with live Mycobacterium tuberculosis but not when infected with heat-killed bacteria. Consistent with our data linking Rip2 to NOD and not Toll-like receptor signaling, M. tuberculosis-induced Rip2 polyubiquitination appears MyD88-independent. Collectively, these data reveal that the NOD2 pathway is ubiquitin-regulated and that Rip2 employs a ubiquitin-dependent mechanism to achieve NF-kappaB activation.
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PMID:NOD2 pathway activation by MDP or Mycobacterium tuberculosis infection involves the stable polyubiquitination of Rip2. 1794 36

A fundamental question is what are the molecular determinants that lead to spontaneous preferential targeting of specific autoantigens in autoimmune diseases, such as the insulin B:9-23 peptide sequence in type 1 diabetes. Anti-insulin B:9-23 T cell clones isolated from prediabetic NOD islets have a conserved Valpha-segment/Jalpha-segment, but no conservation of the alpha-chain N region and no conservation of the Vbeta-chain. Here, we show that the conserved T cell receptor alpha-chain generates insulin autoantibodies when transgenically or retrogenically introduced into mice without its corresponding Vbeta. We suggest that a major part of the mystery as to why islet autoimmunity develops relates to recognition of a primary insulin peptide by a conserved alpha chain T cell receptor.
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PMID:Conserved T cell receptor alpha-chain induces insulin autoantibodies. 1862 21

CD8+ T cells are important contributors to the initiation and progression of type 1 diabetes (T1D). A very significant fraction of islet-associated CD8 T cells in NOD mice recognize epitopes of islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP), a non-essential endoplasmic reticulum-resident protein of unclear function. IGRP is also a target of CD8 T cell responses in human T1D patients. In NOD mice, most IGRP-reactive CD8 T cells target the IGRP(206-214) epitope and are diabetogenic. We have shown that the pathogenic activity of this T cell subset is controlled by genetic elements associated with diabetes susceptibility and resistance. One of these elements (Il2) has been recently implicated in susceptibility to several human autoimmune disorders, including TID. In mice, Il2 polymorphisms control a negative feedback mechanism initiated by activated, IL2-producing autoreactive T cells in the pancreatic lymph nodes that increases the regulatory activity of CD4+CD25+ T cells. Not all IGRP-reactive CD8 T cell clones are pathogenic, however, and we have evidence that some of these clonotypes are actually anti-diabetogenic. We had previously shown that administration of altered peptide ligands (APL) targeting IGRP(206-214)-reactive CD8 T cells resulted in diabetes protection only at doses that did not delete low-avidity clones, suggesting a protective role for these clonotypes. I discuss evidence showing that transgenic expression of a low-avidity IGRP(206-214)-reactive T cell receptor (TCR) efficiently prevents the development of insulitis and diabetes in NOD (non-obese diabetic) mice and that these cells do so by killing autoantigen-loaded antigen presenting cells in the pancreas-draining lymph nodes. These results illustrate a novel mechanism for regulation of immune responses to self-antigens and expose a new target for therapeutic intervention. Here I briefly summarize work done by us and others indicating that a prevalent subset of autoreactive CD8 T-cells in the NOD mouse are major (albeit likely dispensable) players in the pathogenesis of spontaneous autoimmune diabetes in the NOD mouse; that these T cells are targets of genetic elements affording autoimmune disease susceptibility and resistance; that they can either be diabetogenic or anti-diabetogenic according to their avidity for peptide/MHC; and that they can serve as useful targets for therapeutic intervention.
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PMID:Genetic and therapeutic control of diabetogenic CD8+ T cells. 1920 63

Type 1 diabetes, in human patients and NOD mice, results from an immune attack on insulin-producing beta-cells of the pancreas by autoreactive T lymphocytes. In NOD mice, genetically controlled perturbations in the signaling pathways downstream of the antigen-specific T cell receptor (TCR) may be instrumental in the altered responses of T cells, manifest as inefficient induction of apoptosis after recognition of self-antigens in the thymus or as perturbed reactivity of mature T cells in peripheral organs. To map this signaling difference(s), we have used mass spectrometry-based quantitative phosphoproteomics to compare the activation of primary CD4(+) T cells of diabetes-prone NOD and -resistant B6.H2g7 mice. Immunoprecipitation and IMAC purification of tyrosine-phosphorylated peptides, combined with a stable-isotope iTRAQ labeling, enabled us to identify and quantify over 77 phosphorylation events in 54 different proteins downstream of TCR stimulation of primary CD4(+) T cells. This analysis showed a generally higher level of phosphotyrosine in activated NOD cells, as well as several phosphorylation sites that appeared to be differentially regulated in these two strains (involving TXK, CD5, PAG1, and ZAP-70). These data highlight the differences in signaling between CD4(+) T cell compartments of NOD and B6g7 mice and may underlie the dysregulation of T cells in NOD mice.
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PMID:Quantitative phosphoproteomic analysis of T cell receptor signaling in diabetes prone and resistant mice. 2043 20

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