Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0004364 (autoimmune disease)
24,845 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclosporin A (CsA) prevents most immature thymocytes from progressing to a mature phenotype and blocks the deletion of T cells that express self-specific TCR in the small population of cells that achieve maturity. The latter effect may explain the paradoxical observation that this immunosuppressive drug can induce autoimmunity in irradiated rodents and humans if administered while new T cells are developing in the thymus. This study shows that the repopulation of the periphery with mature T cells is delayed in irradiated CsA-treated mice, presumably because CsA blocks T cell development in the thymus. The peripheral repertoire of these mice contained self-reactive IL-2 producing T cells that could be detected in a sensitive limiting dilution assay. In addition, self-reactive T cell hybridomas were isolated from the IL-2 receptor+ population present in CsA-treated mice. One of these hybridomas expressed a TCR V beta chain that is normally expressed on thymocytes that are deleted via recognition of self-antigens. Despite the presence of self-reactive T cells that had escaped clonal deletion, CsA-treated mice rarely developed lethal autoimmune disease, implying that a peripheral mechanism of tolerance can prevent the onset of autoimmune disease.
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PMID:Self-reactive T cells are present in the peripheral lymphoid tissues of cyclosporin A-treated mice. 128 60

The restricted usage of particular T cell receptor beta chain genes in autoimmune disease was studied in LEW rats using T cell hybridomas specific for an immunodominant sequence of bovine retinal S-Ag, which induces experimental autoimmune uveoretinitis. T cell hybridomas from a pathogenic T cell line, R858, specific for residues 273-289 of bovine retinal S-Ag were analyzed in order to determine the contribution of their TCR V beta to self specificity as determined by recognition of the pathogenic epitope represented in the autologous rat S-Ag sequence. Six different, functional TCR rearrangements were expressed by the panel of hybridomas, including two distinct V beta 8.2 rearrangements and functional V beta 10, V beta 14, V beta 19 rearrangements, and an unidentified V beta gene. All hybridomas were Ag specific and reacted both to nonself-peptide derivatives as well as to self-peptide homologues. No unique pattern of peptide reactivity distinguished V beta 8.2+ hybridomas from V beta 8.2- hybridomas; all of the hybridomas were most reactive to the nonself sequences and reacted to self peptide with one to three orders of magnitude less sensitivity. However, all V beta 8.2+ hybridomas were much better responders overall and were activated by lower concentrations of all peptides than were V beta 8.2- hybridomas. Although V beta 8.2 gene usage is strongly associated with autoimmune pathology, these data show that in LEW rats several different TCR V beta genes are utilized in response to a short pathogenic sequence of this autoantigen and show that V beta 8.2 receptors are not uniquely self-reactive. However, the enhanced reactivity to Ag of V beta 8.2+ hybridomas relative to V beta 8.2- hybridomas specific for the same peptide may help explain the close association of V beta 8.2 TCR gene usage with pathogenicity found in autoimmune disease models.
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PMID:Multiple, autoreactive TCR V beta genes utilized in response to a small pathogenic peptide of an autoantigen in EAU. 132 Apr 62

The initiation of autoimmune B cell and T cell responses by self Ag or by foreign pathogens (molecular mimics) is not well understood. In the present study, cytochrome c (cyt c) was used as a model autoantigen to investigate how self-proteins are involved in the priming of autoimmune T cell responses. Immunization with foreign cyt c has been extensively analyzed in previous studies as a model for both humoral and cellular immune responses. Mice do not, however, make antibody or T cell responses to immunization with self (mouse) cyt c. In addition, T cell tolerance can be broken by autoreactive B cells that are readily elicited by immunization with cross-reactive foreign cyt c. These immune B cells presumably bind self cyt c and process and present the self Ag to stimulate an autoreactive T cell response. Autoreactive T cell clones derived by this mechanism are all specific for determinants within amino acids 1-80 of the cyt c protein presented by I-Ek. No T cell responses were observed to the carboxyl terminal 81-104 fragment that dominates the response to foreign cyt c. All clones derived in this study are stimulated by a polypeptide encompassing amino acids 54-68 and utilized the V beta 8.2 TCR gene. In contrast, T cells stimulated by foreign cyt c did indeed respond to fragment 81-104 and appear to utilize alternate TCR genes. Our data demonstrate that B cells specific for linear determinants distributed along the entire length of the foreign cyt c molecule can provide the stimulus required for breaking T cell tolerance to self cyt c. The applications of this work to understanding the mechanisms of autoimmune disease are discussed.
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PMID:Breaking T cell tolerance with foreign and self co-immunogens. A study of autoimmune B and T cell epitopes of cytochrome c. 132 51

T cell activation in the characteristic synovial lesions of rheumatoid arthritis may play a major role in the pathogenesis of this autoimmune disease. Analysis of T cell clonal diversity in these sites remains equivocal. Using the PCR and subsequent single-strand conformation polymorphism analysis it is possible to assess the degree of junctional diversity in the TCR with minimal selection bias. Concentrating on the beta-chain of the TCR, a paucity of clonotypic T cell expansion is demonstrated in the peripheral blood of healthy individuals. After polyclonal stimulation in vitro (with concanavalin A or phytohemagglutinin) this pattern does not change. In contrast, some T cell clonotypes appear following in vitro stimulation with purified protein derivative. Analysis of the peripheral blood, synovial fluid, and synovial tissue of patients with rheumatoid arthritis indicated many dominant T cell clonotypes. These data argue for a clonally diverse T cell response in the affected tissues of rheumatoid arthritic subjects.
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PMID:Accumulation of multiple T cell clonotypes in the synovial lesions of patients with rheumatoid arthritis revealed by a novel clonality analysis. 133 82

Subpathogenic doses of syngeneic autoreactive T cells protect experimental animals against associated autoimmune disease. Preferential use of the TCR of encephalitogenic T cells suggests that this molecule serves as the target for immunoregulation in experimental autoimmune encephalomyelitis (EAE). Whether peptides derived from the V beta 8 of the rat TCR elicit regulatory T cells and produce the same vaccinating effect against EAE as do whole T cells remains unknown. Here we show that immunization of Lewis rats with V beta 8(39-59), a peptide representing residues 39 to 59 of the rat V beta 8 TCR, does not induce the production of regulatory T cells reactive to the intact TCR V beta 8 containing this sequence. Moreover, animals that had recovered from both actively induced EAE and transferred EAE did not generate regulatory T cells that recognized the V beta 8(39-59) peptide. Further, transfusion of large doses of peptide-specific T cells did not protect the animals from EAE. Our results suggest that the V beta 8(39-59) peptide may comprise so-called cryptic epitopes, which function as immunogens only when dissociated from large protein complexes.
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PMID:Synthetic peptides representing sequence 39 to 59 of rat V beta 8 TCR fail to elicit regulatory T cells reactive with V beta 8 TCR on rat encephalitogenic T cells. 137 43

To determine whether there is predominance of T cells expressing a particular TCR V beta chain in the inflammatory lesions of an autoimmune disease model, TCR expression was analyzed in central nervous system (CNS) tissues of mice with experimental allergic encephalomyelitis (EAE). Acute EAE was induced in SJL/J mice either by sensitization with a synthetic peptide corresponding to myelin proteolipid protein residues 139-151 or by adoptive transfer of myelin proteolipid protein peptide 139-151-specific encephalitogenic T cell clones. Mice were killed when they showed clinical signs of EAE or by 40 days after sensitization or T cell transfer. Cryostat CNS and lymphoid tissue sections were immunostained with a panel of mAb to T cell markers and proportions of stained cells were counted in inflammatory foci. In mice with both actively induced and adoptively transferred EAE, infiltrates consisted of many CD3+, TCR alpha beta+, and CD4+ cells, fewer CD8+ cells, and small numbers of TCR gamma delta+ cells. Approximately 30% of CD45+ leukocytes in the inflammatory foci were T cells. Cells expressing TCR V beta 2, 3, 4, 6, 7 and 14 were detected in the infiltrates, whereas TCR V beta 8 and 11, which that are deleted in SJL mice, were absent. When EAE was induced by transfer of T cell clones that use either V beta 2, 6, 10, or 17, there was also a heterogeneous accumulation of T cells in the lesions. Similar proportions of TCR V beta+ and gamma delta+ cells were detected in EAE lesions and in the spleens of the mice. Thus, at the time that clinical signs are present in acute EAE, peripherally derived, heterogeneous TCR V beta+ cells are found in CNS lesions, even when the immune response is initiated to a short peptide Ag or by a T cell clone using a single TCR V beta.
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PMID:The immunopathology of acute experimental allergic encephalomyelitis induced with myelin proteolipid protein. T cell receptors in inflammatory lesions. 138 45

The dominant immune response to rat myelin basic protein in H-2u mice is directed against the acetylated, N-terminal peptide Ac1-11 (AcASQKR-PSQRHG). This peptide causes encephalomyelitis on injection into mice of the H-2u haplotype. Only two residues of the peptide are required for ligation of the TCR from an Ac1-11-specific T cell hybridoma. Proline at position 6 could not be substituted by any other L-amino acid, whereas glutamine at position 3 could be replaced by phenylalanine, histidine, methionine, or tyrosine. Cross-reactive recognition of these residues appears to be specific, because increasing the affinity of each analogue for its MHC restriction element, by replacing lysine with tyrosine at position 4, did not alter the pattern of cross-reactivity. For the majority of substitutions at this position, a lack of stimulation could not be explained by failure to bind to I-Au. However, competition binding studies showed that introduction of proline at position 3 reduced the efficacy of binding to I-Au. Cross-reactive analogues of Ac1-11 were injected into H-2u mice to test the extent to which cross-reactive T cell activation might lead to autoimmune disease in this model. An analogue containing methionine at position 3 caused clinical experimental autoimmune encephalomyelitis in a small percentage of H-2u mice.
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PMID:Cross-reactive antigen recognition by an encephalitogenic T cell receptor. Implications for T cell biology and autoimmunity. 138 32

Mice homozygous for the gld (generalized lymphoproliferative disease) mutation developed systemic autoimmune disease and severe lymphadenopathy due to an age-related accumulation in the peripheral lymphoid organs of polyclonal T cells bearing a unique phenotype (CD4-CD8-TCR alpha beta+B220+). These T cells overexpress T cell receptor (TcR) alpha beta chain RNA, proto-oncogenes c-myb and fyn, and proliferate poorly in response to TcR-mediated stimulation. The origin of these T cells is poorly understood. To study the influence of a functionally rearranged TcR beta chain on the T cell developmental abnormality of the gld mutation and autoimmunity, we have backcrossed TcR V beta 8.1-transgenic mice to C3H-gld/gld to homozygosity (transgenic gld mice). In transgenic gld mice, lymphadenopathy was markedly inhibited and the accumulation of CD4-CD8- T cells did not occur, although the remaining T cells overexpressed c-myb and proliferated poorly in response to TcR occupancy. These features indicate that the pattern of proto-oncogene expression and abnormal function persist in phenotypically normal T cells in transgenic gld mice, and that these characteristics can be dissociated from the accumulation of CD4-CD8- T cells. The hypergammaglobulinemia and anti-double-stranded DNA (anti-dsDNA) antibody production was partially improved in transgenic gld mice, supporting the critical role of T cells in abnormal B cell activation described in autoimmunity-prone mice. To investigate further the mechanisms underlying the inhibition of CD4-CD8- T cell accumulation in transgenic gld mice, the fetal ontogeny of T cells in transgenic mice was compared with that of non-transgenic mice. In transgenic thymus, development of TcR alpha beta+ cells was accelerated as detected by earlier expression of CD4, CD8 and TcR in fetal thymus. In contrast, the number of TcR gamma delta+ cells was reduced. We suggest that altered T cell development in transgenic mice directly or indirectly inhibits the accumulation of abnormal T cells in gld mice.
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PMID:Inhibition of abnormal T cell development and autoimmunity in gld mice by transgenic T cell receptor beta chain. 138 74

Current theories of the aetiology of RA point to a central role for the trimolecular complex comprising the MHC class II molecule on the surface of the APC, the antigenic peptide and the TCR on the disease-inducing T cell. Thus the arthritogenic T cell is an important target for new therapy. However, it cannot be directly identified because the causative antigen is unknown, so indirect techniques such as TCV and TCR peptide vaccination are required. In TCV, T cells thought to mediate the disease, in an activated and attenuated form, are injected into the patient, who then develops a specific immune response against these pathogenic T cells. TCV has been shown to be effective in protecting against and treating a variety of animal models of autoimmune disease, including AA, EAE and IDDM in NOD mice. The vaccines initially comprised clones and lines of T cells shown to be capable of transferring the disease, but later unseparated LN cells were also shown to be effective, paralleling more closely the human situation. Interestingly, it has become clear that TCV does not create its own regulatory network but amplifies a natural immunoregulatory network which forms as the disease develops. The major stimulating moiety on the vaccinating T cell is its receptor (anti-idiotypic response), although there is also an anti-ergotypic (anti-activated T cell) response. For this reason the technique of TCR peptide vaccination was developed, which utilizes only a short peptide from the TCR of the disease-causing cells to stimulate an immune response against them. This is effective in the prevention and treatment of EAE, where there is a preferential usage of TCR-V beta 8 by encephalitogenic T cells. The application of both these techniques to human autoimmune disease is in its infancy. Studies of TCV in MS and RA have not shown clear-cut clinical benefit, although immunological changes have been observed; comparison of methodology with the animal work and assessment of results are complex and further studies are in progress. Studies of TCR peptide vaccination in MS and RA are handicapped by the lack of a consensus on TCR usage in these conditions, but a limited study is underway in MS.
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PMID:Management of early inflammatory arthritis. Intervention with immunomodulatory agents: T cell vaccination. 152 47

The majority of human peripheral blood and lymphoid tissue T cells express the TCR alpha/beta heterodimer, while the TCR gamma/delta is expressed on only a small subset of T lymphocytes. However, the majority of murine intraepithelial lymphocytes and most Thy-1+ murine dendritic epidermal cells express the TCR gamma/delta. Selective homing of avian TCR gamma/delta bearing lymphocytes to the intestinal epithelium also has been shown. These findings have suggested that these cells play a role against transformation and infection. More recently, a role in autoimmunity also has been proposed. We examined normal human conjunctiva and inflamed conjunctiva from patients with ocular cicatricial pemphigoid (OCP), an autoimmune disorder, and atopic keratoconjunctivitis (AKC). The majority of T cells in the epithelium and substantia propria of normal conjunctiva expressed the TCR alpha/beta. Tropism of TCR gamma/delta-expressing lymphocytes to normal human conjunctiva was not present. However, in OCP, there was a statistically significant increase in the absolute number of TCR gamma/delta cells/mm2 (epithelium, 33.9 +/- 10.5 [mean +/- standard error of the mean] vs. 159.9 +/- 51.5, P = less than 0.0008; substantia propria, 4.1 +/- 0.9 vs. 240.1 +/- 191.3, P less than 0.002) and TCR gamma/delta cells as a percentage of CD3+ cells (epithelium, 0.18 +/- 0.06 vs. 0.39 +/- 0.07, P = less than 0.02; substantia propria, 0.10 +/- 0.05 vs 0.33 +/- 0.08, P = less than 0.03). This was not the case for AKC. These findings suggest that TCR gamma/delta lymphocytes play a specific but undefined role in certain conjunctival inflammatory conditions and may be important in autoimmunity.
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PMID:The T cell receptor in normal and inflamed human conjunctiva. 153 76


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