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T Kobata

Publications and source records attributed to T Kobata.

At least 37 records · Page 2Linked to original sources
PubMed2000

Synovial hyperplasia in HTLV-I associated arthropathy is induced by tumor necrosis factor-alpha produced by HTLV-I infected CD68+ cells.

OBJECTIVE: To investigate the pathogenic role of macrophage lineage (CD68+) cells in synovial proliferation in patients with human T cell leukemia virus I (HTLV-I) associated arthropathy (HAAP). METHODS: Synovial tissues obtained from 3 patients with HAAP and 3 patients with osteoarthritis (OA) were examined for the expression of tumor necrosis factor-alpha (TNF-alpha) mRNA, HTLV-I tax/rex mRNA, and number of CD68 by in situ reverse transcription assay and immunohistochemistry. Western blot and flow cytometric analyses were used to determine TNF-alpha production in HTLV-I infected synoviocytes. Changes in CD68+ cell population were examined by flow cytometric analysis. Proliferative effects of supernatants of HTLV-I infected synoviocytes on normal synoviocytes were also determined. RESULTS: TNF-alpha and HTLV-I tax/rex mRNA were preferentially expressed in CD68+ cells in HAAP synovia. Infection of OA synoviocytes by HTLV-I resulted in preferential expression in CD68+ cells, and these cells produced TNF-alpha. Supernatants of HTLV-I infected synoviocytes significantly enhanced the proliferation of normal synoviocytes through a TNF-alpha dependent pathway. CONCLUSION: Our results suggest HTLV-I viral tropism for CD68+ cells, and that HTLV-I infected synoviocytes were induced to produce TNF-alpha, which enhances synovial proliferation in HAAP.

Aged↗
PubMed2000

Role of costimulatory molecules in autoimmunity.

The precise mechanisms by which self-reactive T cells are activated and tolerance to self-antigens is broken are still not fully understood. It is widely accepted that dysregulation of costimulation contributes to the initiation and maintenance of autoimmunity due to activation of self-reactive T cells. Many of the costimulatory molecules thought to be essential for T cell activation have been identified. The CD28/CD152 (CTLA-4)-CD80/CD86 and CD40-CD154 (CD40 ligand) interactions are such receptor/ligand pairs that have been shown to be important in interactions between antigen-presenting cells and T cells. In vivo studies using costimulatory molecule-specific antibodies and fusion proteins and genetically manipulated animals have greatly increased our understanding of the role of these costimulatory molecules in the regulation of cellular processes that lead to autoimmunity and resultant autoimmune diseases.

Animals↗
PubMed1999

Targeted disruption of Traf5 gene causes defects in CD40- and CD27-mediated lymphocyte activation.

TRAF5 [tumor necrosis factor (TNF) receptor-associated factor 5] is implicated in NF-kappaB and c-Jun NH(2)-terminal kinase/stress-activated protein kinase activation by members of the TNF receptor superfamily, including CD27, CD30, CD40, and lymphotoxin-beta receptor. To investigate the functional role of TRAF5 in vivo, we generated TRAF5-deficient mice by gene targeting. Activation of either NF-kappaB or c-Jun NH(2)-terminal kinase/stress-activated protein kinase by tumor necrosis factor, CD27, and CD40 was not abrogated in traf5(-/-) mice. However, traf5(-/-) B cells showed defects in proliferation and up-regulation of various surface molecules, including CD23, CD54, CD80, CD86, and Fas in response to CD40 stimulation. Moreover, in vitro Ig production of traf5(-/-) B cells stimulated with anti-CD40 plus IL-4 was reduced substantially. CD27-mediated costimulatory signal also was impaired in traf5(-/-) T cells. Collectively, these results demonstrate that TRAF5 is involved in CD40- and CD27-mediated signaling.

Animals↗
PubMed1999

Graft-versus-leukemia effect and graft-versus-host disease can be differentiated by cytotoxic mechanisms in a murine model of allogeneic bone marrow transplantation.

Allogeneic bone marrow transplantation (allo-BMT) is associated with both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effect. In the present study, we examined the contribution of cytotoxic effector mechanisms, which are mediated by tumor necrosis factor-alpha (TNF-alpha), Fas ligand (FasL), or perforin, to GVHD and GVL effect in a murine BMT model. Bone marrow cells plus spleen cells (BMS) from wild-type, FasL-defective, or perforin-deficient donors were transferred into lethally irradiated recipients in the parent (C57BL/6) to F1 (C57BL/6 x DBA/2) BMT model with or without prior inoculation of DBA/2 leukemia L1210 or P815 mast cytoma cells. The effect of anti-TNF-alpha antibody administration was also examined. Whereas the defect or blockade of each cytotoxic pathway could ameliorate lethal acute GVHD, the GVL effect was differentially affected. The wild-type BMS recipients died of acute GVHD within 50 days without residual leukemia cells. The FasL-defective BMS recipients showed 60%< survival over 80 days without acute GVHD or residual leukemia cells. Administration of anti-TNF-alpha antibody resulted in early leukemia relapse and the recipients died within 25 days with massive leukemia infiltration in the liver. The perforin-deficient BMS recipients died within 60 days with residual leukemia cells. These results suggest that blockade of the Fas/FasL pathway could be used for ameliorating GVHD without impairing GVL effect in allo-BMT.

Animals↗
PubMed1999

Autoantibodies to T cell costimulatory molecules in systemic autoimmune diseases.

To determine whether antilymphocyte Abs to T cell costimulatory molecules are generated in patients with autoimmune diseases and, if they exist, to clarify the mechanism of their production and pathological roles, we investigated the presence of autoantibodies to CTLA-4 (CD152), CD28, B7-1 (CD80), and B7-2 (CD86) in serum samples obtained from patients with various autoimmune diseases and from normal subjects using recombinant fusion proteins. In ELISAs, anti-CD28, anti-B7-1, and anti-B7-2 Abs were rarely seen, whereas anti-CTLA-4 Abs were detected in 8.2% of the patients with systemic lupus erythematosus, 18.8% of those with rheumatoid arthritis, 3.1% of those with systemic sclerosis, 31.8% of those with Behçet's disease, 13.3% of those with Sjögren's syndrome, and 0% of healthy donors. This reactivity was confirmed by immunoblotting. More importantly, the purified anti-CTLA-4 Abs reacted with CTLA-4 expressed on P815 cells by flow cytometry. In addition, we found at least three epitopes on the CTLA-4 molecule. Furthermore, among the patients with Behçet's disease, uveitis was seen significantly less frequently in the anti-CTLA-4 Ab-positive patients. Taken collectively, these data indicate that anti-CTLA-4 autoantibodies are generated in systemic autoimmune diseases by an Ag-driven mechanism and may modulate the immune response in vivo by binding to CTLA-4 on T cells.

Abatacept↗
PubMed1999

Expression of tumour necrosis factor (TNF) receptor/ligand superfamily co-stimulatory molecules CD40, CD30L, CD27L, and OX40L in murine hearts with chronic ongoing myocarditis caused by coxsackie virus B3.

T-cell-mediated myocardial damage has been shown to be involved in acute myocarditis and dilated cardiomyopathy. It is necessary for T-cells to receive a co-stimulatory signal as well as the main signal through the T-cell receptor for antigen-specific T-cell activation to occur. To investigate the roles of the co-stimulatory molecules CD40/CD40L, CD30/CD30L, CD27/CD27L, and OX40/OX40L, which belong to the tumour necrosis factor (TNF) receptor/ligand superfamily, in the development of chronic ongoing myocarditis, the expression of CD40, CD30L, CD27L, and OX40L was analysed in the hearts of A/J mice with myocarditis induced by Coxsackie virus B3 (CVB3). The expression of CD40L, CD30, CD27, and OX40 was also examined on the infiltrating cells. Furthermore, the induction of CD40, CD30L, CD27L, and OX40L was evaluated on cultured cardiac myocytes treated with interferon (IFN)-gamma. CVB3-induced myocarditis resulted in the induction of CD40 and CD30L on the surface of cardiac myocytes. Induction of CD40 and CD30L on cardiac myocytes was confirmed by treatment with IFN-gamma in vitro. CD27L and OX40L were expressed on cardiac myocytes in vivo and in vitro. The expression of CD27L and OX40L on cardiac myocytes was increased, at least partly, by CVB3-induced myocarditis in vivo. Many infiltrating cells expressed CD27 and OX40, whereas much smaller numbers expressed CD40L and CD30. The induction of these molecules, especially CD40 and CD30L, on cardiac myocytes strongly suggests that cardiac myocytes may co-stimulate T-cells and induce cytokine production by T-cells and humoral immune responses. This may play an important role in the pathogenesis of the resulting myocardial damage.

Animals↗
PubMed1999

Tumor necrosis factor alpha regulation of the FAS-mediated apoptosis-signaling pathway in synovial cells.

OBJECTIVE: Fas-mediated apoptosis is observed in synoviocytes of patients with rheumatoid arthritis (RA), but not in those of patients with osteoarthritis (OA). The present study was conducted to elucidate the mechanisms that initiate induction of Fas-mediated apoptosis in RA synoviocytes. METHODS: Cultured OA synoviocytes, which are insensitive to Fas-mediated apoptosis in spite of Fas antigen expression, were used in these experiments. Synovial cell proliferation and cytotoxicity studies were performed using MTS and lactate dehydrogenase release assays. Surface expression of Fas antigen was analyzed by flow cytometry. The expression and function of apoptosis-signaling molecules, such as caspase 8 and caspase 3, were examined by immunoblot analysis. RESULTS: Tumor necrosis factor alpha (TNFalpha) induced proliferation of cultured OA synoviocytes. Fas ligation with anti-Fas monoclonal antibody (mAb) resulted in cytotoxic activity against cultured OA synoviocytes that had been pretreated with TNFalpha for 5 days, but not those pretreated for 2 days. In contrast, anti-Fas mAb did not show a cytotoxic effect against untreated cultured OA synoviocytes. A gradual up-regulation of caspase 8 and caspase 3, which played a role in the caspase cascade for Fas-mediated apoptosis, was observed in TNFalpha-treated cultured OA synoviocytes. In addition, Fas ligation to TNFalpha-treated cultured OA synoviocytes induced activation of caspase 8 and caspase 3, with subsequent cleavage of poly(ADP-ribose) polymerase (PARP), a substrate of activated caspase 3. More importantly, Z-IETD-FMK, a caspase 8 inhibitor, and Ac-DEVD-CHO, a caspase 3 inhibitor, almost completely inhibited Fas-mediated apoptosis of TNFalpha-treated cultured OA synoviocytes, whereas Ac-YVAD-CHO, a caspase 1 inhibitor, did not. CONCLUSION: Our results clearly demonstrate that TNFalpha stimulates synovial cells to proliferate as well as sensitizes the cells for Fas-mediated apoptosis, at least in part by up-regulation and activation of caspase 8 and caspase 3. These findings suggest that TNFalpha may be one of the factors providing sensitization of synovial cells to Fas-mediated apoptosis in RA.

Apoptosis↗
PubMed1999

Expression of murine HOXD9 during embryonic joint patterning and in human T lymphotropic virus type I tax transgenic mice with arthropathy resembling rheumatoid arthritis.

OBJECTIVE: To characterize the expression of murine HOXD9 during normal joint development and in arthritic joints of human T lymphotropic virus type I (HTLV-I) tax transgenic mice and the role of HTLV-I tax in HOXD9 expression. METHODS: Expression of HOXD9, HOXD1O, HOXD11, HOXD12, and HOXD13 genes in joint tissues at the ankle/foot regions of mouse embryos at day 10 to day 18 of gestation (E10-E18) and neonates within 10 days after birth was determined by reverse transcriptase-polymerase chain reaction and in situ reverse transcription methods. Adult synovial tissues from 5 HTLV-I tax transgenic mice with chronic polyarthritis and 4 nontransgenic (normal) mice were also examined for expression of these HOXD genes. The effect of HTLV-I on HOXD9 expression in cultured synoviocytes was studied by in vitro infection and transfection experiments. RESULTS: Expression of HOXD9 was detected in embryonic joints, preferentially on articular cartilage, only during the early stages of joint development (up to E15), whereas other HOXD genes were expressed throughout the embryonic and neonatal stages. In adult mice, transcripts of HOXD9 were specifically detected in synovial tissues from 4 of 5 arthritic mice, especially in the lining and sublining synovial cells, but not in synovial tissues of normal mice. Activation of HOXD9 was observed in cultured synoviocytes infected with HTLV-I in vitro as well as in those transfected with HTLV-I tax. CONCLUSION: Our findings suggest that HOXD9 is involved not only in the early stages of normal joint development, but may also be involved in the pathologic process of arthritis. HTLV-I tax appeared as an activator of this HOX gene in cultured synoviocytes.

Animals↗
PubMed1999

Apomodulation as a novel therapeutic concept for the regulation of apoptosis in rheumatoid synoviocytes.

Fas-mediated apoptosis is observed in synoviocytes of patients with rheumatoid arthritis (RA). This process may be involved in the pathophysiology of RA. We have recently found that Fas-mediated apoptosis of RA synoviocytes is associated with activation of two signaling pathways, the c-Jun amino-terminal kinase (JNK)/activator protein-1 (AP-1) pathway, and the FADD (Fas-associated death domain protein)/Caspase-8/Caspase-3/PARP (poly(ADP-ribose)polymerase) pathway. The latter appears to be one of the major signaling pathways required for Fas-mediated apoptosis in RA synoviocytes. Interestingly, Fas-mediated apoptosis in synoviocytes may be induced at least in part by tumor necrosis factor-alpha. Paradoxically, tumor necrosis factor-alpha also causes proliferation of synoviocytes. Employing these molecular processes in the treatment of RA, we have recently shown that ex vivo gene transfer of human Fas ligand (hFasL) induced apoptosis of synoviocytes and infiltrated mononuclear cells of RA synovial tissue through cell-to-cell interaction via the Fas/FasL system. We believe that further understanding of the complex regulatory mechanisms of apoptosis in RA synoviocytes would uncover further aspects of the pathophysiologic mechanisms of RA and contribute to the development of new and effective therapies for RA.

Apoptosis↗
PubMed1999

Characterisation of T cell clonotypes that accumulated in multiple joints of patients with rheumatoid arthritis.

OBJECTIVE: To investigate whether identical T cell clonotypes accumulate in multiple rheumatoid joints, the clonality of T cells that had infiltrated into synovial tissue (ST) samples simultaneously obtained from multiple joints of patients with rheumatoid arthritis (RA) was analysed. METHODS: T cell receptor (TCR) beta gene transcripts, amplified by reverse transcription-polymerase chain reaction from ST and peripheral blood lymphocytes of five RA patients, were subjected to single strand conformation polymorphism analysis and DNA sequencing. RESULTS: Approximately 40% of accumulated T cell clonotypes found in one joint of a patient were found in multiple joints in the same patient. Furthermore, identical amino acid sequences were found in TCR beta junctional regions of these clonotypes from different patients with at least one HLA molecule match. CONCLUSIONS: The T cell clonotypes accumulating in multiple rheumatoid joints may be involved in the perpetuation of polyarthritis by reacting to antigens common to these multiple joints.

Amino Acid Sequence↗
PubMed1999

[T cell receptor and its related molecules in signal transduction].

Engagement of the T cell receptor (TCR) by peptide antigen bound to the major histocompatibility complex molecules initiates a biochemical cascade involving protein tyrosine kinases (PTKs) such as Lck, ZAP70 and Csk, and protein tyrosine phosphatases (PTPases) such as CD45, SHP-1 and SHP-2. In the process of T cell activation, immune tyrosine-based activation motifs (ITAMs) and immune tyrosine-based inhibitory motifs(ITIMs) within the cytoplasmic region of CD3 and CD152 molecules play a key role in the activation of PTKs and PTPases. Consequently, Ras/MAP kinase and PLC gamma 1 pathways are activated to induce IL-2 gene transcription through AP-1 and NF-AT generation. Recent biochemical and genetic evidence has suggested that dysfunction in these TCR-related molecules resulted in immuno-deficiency, breakdown of tolerance and abnormal T cell development.

Animals↗
PubMed1998

CD27, a member of the tumor necrosis factor receptor superfamily, activates NF-kappaB and stress-activated protein kinase/c-Jun N-terminal kinase via TRAF2, TRAF5, and NF-kappaB-inducing kinase.

CD27 is a member of the tumor necrosis factor (TNF) receptor superfamily and is expressed on T, B, and NK cells. The signal via CD27 plays pivotal roles in T-T and T-B cell interactions. Here we demonstrate that overexpression of CD27 activates NF-kappaB and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). Deletion analysis of the cytoplasmic domain of CD27 revealed that the C-terminal PIQEDYR motif was indispensable for both NF-kappaB and SAPK/JNK activation and was also required for the interaction with TNF receptor-associated factor (TRAF) 2 and TRAF5, both of which have been implicated in NF-kappaB activation by members of the TNF-R superfamily. Co-transfection of a dominant negative TRAF2 or TRAF5 blocked NF-kappaB and SAPK/JNK activation induced by CD27. Recently, a TRAF2-interacting kinase has been identified, termed NF-kappaB-inducing kinase (NIK). A kinase-inactive mutant NIK blocked CD27-, TRAF2-, and TRAF5-mediated NF-kappaB and SAPK/JNK activation. These results indicate that TRAF2 and TRAF5 are involved in NF-kappaB and SAPK/JNK activation by CD27, and NIK is a common downstream kinase of TRAF2 and TRAF5 for NF-kappaB and SAPK/JNK activation.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Generation of plasma cells from peripheral blood memory B cells: synergistic effect of interleukin-10 and CD27/CD70 interaction.

B cells can differentiate into the antibody-secreting cells, plasma cells, whereas the crucial signals that positively control the entry into the pathway to plasma cells have been unclear. Triggering via CD27 by CD27 ligand (CD70) on purified peripheral blood B cells yielded an increase in the number of plasma cells in the presence of interleukin-10 (IL-10). Differentiation into plasma cells by a combination of IL-10 and CD70 transfectants occurred in CD27+ B cells but not in CD27- B cells. Moreover, addition of IL-2 to the IL-10 and CD70-transfect activation system greatly induced differentiation into plasma cells. In the presence of only IL-2, IL-4, or IL-6, CD70 transfectants did not promote differentiation into plasma cells. On the other hand, CD40 signaling increased the expansion of a B-cell pool from peripheral blood B cells primarily activated by IL-2, IL-10, and anti-CD40 monoclonal antibody (MoAb). Finally, CD27 signaling also rescued B cells from IL-10-mediated apoptosis. These data demonstrate that CD27 ligand (CD70) is a key molecule to prevent the IL-10-mediated promotion of apoptosis and to direct the differentiation of CD27+ memory B cells toward plasma cells in cooperation with IL-10.

Adult↗
PubMed1998

Evidence for autoantigens of Env/Tax proteins in human T cell leukemia virus type I Env-pX transgenic mice.

OBJECTIVE: To examine T cell clonotypes infiltrating into arthritic joints and to investigate whether human T cell leukemia virus type I (HTLV-I) env-pX gene products act as autoantigens in HTLV-I env-pX transgenic mice. METHODS: Complementary DNA (cDNA) encoding the V-D-J (third complementarity-determining region [CDR3]) region of T cell receptor beta chain was amplified by Vbeta family polymerase chain reaction. T cell clonotypes were detected by a single-strand conformational polymorphism method, and sequence analysis of the CDR3 region was performed. RESULTS: Distinct oligoclonal T cell expansion was observed in arthritic joints, and a conserved amino acid motif in the CDR3 region was found in T cells infiltrating joints. Moreover, several intraarticular T cells recognized HTLV-I Env and Tax proteins. CONCLUSION: Our results suggest that HTLV-I Env and Tax proteins act as autoantigens that are recognized by autoreactive T cells in inflamed arthritic lesions in the HTLV-I env-pX transgenic mouse. Thus, some T cells infiltrating the joint recognize Env or Tax protein. These cells may trigger chronic arthritis in HTLV-I env-pX transgenic mice.

Amino Acid Sequence↗
PubMed1998

Amelioration of lymphoid hyperplasia and hypergammaglobulinemia in lupus-prone mice (gld) by Fas-ligand gene transfer.

We recently demonstrated that the transplantation of wild-type bone marrow cells into lupus-prone mice (gld), resulted in the normalization of autoimmune syndromes due to induction of direct elimination of pathogenic cells by apoptosis via Fas/Fas ligand (L) interactions. This finding supports the beneficial therapeutic effect of Fas-mediated apoptosis on autoimmunity in gld mice. To further establish the therapeutic effect of Fas-mediated apoptosis on autoimmunity, we investigated the effect of cells transfected with the FasL gene on autoimmune symptoms in gld mice. The FasL transfectants exhibited cytotoxic activity against gld splenocytes via the Fas/FasL system in vitro. In vivo administration of irradiated-FasL transfectants induced a reduction in hypergammaglobulinemia, the disappearance of lymphoid hyperplasia and of the accumulation of gld cells (B220+ T-cells). Furthermore, in situ nick end labelling analysis revealed that cells in the spleen and lymph nodes frequently underwent apoptosis. These results clearly indicate that FasL transfectants induce the apoptosis of the pathogenic cells responsible for hypergammaglobulinemia and lymphoid hyperplasia in gld mice by cell/cell interaction via the Fas/FasL system. Thus, ex vivo gene transfer of FasL may represent a new therapeutic strategy for autoimmunity caused by the FasL dysfunction.

Animals↗
PubMed1998

Contribution of the T cell receptor BJ gene to recognition of the P91A tumor antigen in DBA/2 mice.

To understand specific immune responses against a tumor, it is important to characterize T cells that recognize the tumor antigen. The mouse P91A antigen is one of the well-defined tumor antigens that is expressed on the P911 cell line, and T cells responding to the antigen in DBA/2 mice were reported to be restricted to BV8S2/S3 families in their T cell receptor (TCR) BV gene usage. We have further characterized the P91A-responding T cells in DBA/2 mice, focusing on TCR BJ gene usage and using the polymerase chain reaction/enzyme-linked immunosorbent assay and DNA sequencing studies of their third complementarity-determining (CDR3) regions. As a result, T cells with cytotoxic activity to the P91A antigen, induced from murine spleen cells both in vivo and in vitro, showed predominant use of the BJ2S1 gene segment in both BV8S2 and BV8S3 T cells compared to unmanipulated murine spleen cells. Sequencing studies of the CDR3 regions in the BV8S3 T cells revealed clonal expansion of T cells with the BV8S3-BJ2S1 combination in two of three DBA/2 mice tested. In the remaining mouse, clonal expansion was not detected despite predominant use of the BJ2S1 segment by these T cells. These data suggest that P91A-recognizing T cells would predominantly use the BV8S2/S3-BJ2S1 combination. Analysis of T cells with these TCR BV-BJ gene combinations may contribute to the evaluation, monitoring and development of a T-cell-mediated immunotherapeutic strategy.

Animals↗