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: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel peripheral T cell subset characterized by the expression of a NK marker and invariant TCR encoded by V alpha 14 J alpha 281 gene segments with a 1-base N-region was investigated in relation to autoimmune disease development. First, we observed that invariant V alpha 14+ NK T cells are specifically reduced with aging in C57BL/6 lpr/lpr or MRL lpr/lpr mice, whereas no change was observed in age-matched control C57BL/6 or MRL +/+ mice as determined by FACS analysis and RNase protection assay. This reduction precedes the disease development and could also be detected in other autoimmune disease-prone mice, such as C3H gld/gld and (NZB x NZW)F1 mice. These results suggest that the specific decrease in invariant V alpha 14+ NK T cells correlates strongly with the development of autoimmunity. Second, injection of MRL lpr/lpr mice with anti-V alpha 14 mAb resulted in the early onset and exacerbation of lymphosplenomegaly due to the accumulation of abnormal CD3+ B220+ CD4-CD8- T cells as well as an increase in the titers of anti-dsDNA autoantibodies. These results indicate that V alpha 14+ NK T cells regulate autoimmune responses and play a crucial role in controlling the development of autoimmune diseases.
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PMID:Selective reduction of V alpha 14+ NK T cells associated with disease development in autoimmune-prone mice. 862 46

Obliterative bronchiolitis (OB) is the most serious late complication of lung transplantation, but the pathogenesis of this disorder has not been elucidated. We sought evidence that OB is mediated by a cellular immunologic response by characterizing T cell antigen receptor beta-chain variable gene (TCRBV) repertoires in lung allograft recipients. Expression levels of 27 TCRBV among recipients were determined by multiprobe RNase protection assay after PCR amplification. In comparison to recipients with no evidence of rejection (n = 9), the PBL TCRBV repertoires of OB subjects (n = 16) exhibited more frequent expansions (16 vs. 9% of all measured TCRBV, P < 0.02), and the magnitudes of these abnormalities were greater (8.2 +/- 0.8 vs. 4.5 +/- 0.3 SD from mean normal values, P < 0.01). TCRBV sequencing showed these expansions were composed of clonal or oligoclonal populations. Thus, T cell responses in the recipients are marked by highly selective clonal expansions, presumably driven by indirect recognition of a limited number of immunodominant alloantigens. These processes are exaggerated among allograft recipients with OB, implying that cognate immune mechanisms are important in the pathogenesis of the disorder. Furthermore, the prominence of finite, distinct TCR phenotypes raise possibilities for development of novel diagnostic modalities and targeted immunotherapies for OB and other manifestations of chronic allograft rejection.
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PMID:T cell receptor biases and clonal proliferations among lung transplant recipients with obliterative bronchiolitis. 864 59

Following allotransplantation, determinants encoded within the donor MHC are recognized by recipient T lymphocytes through their Ag receptor. In this study, we investigated the TCR Vbeta chain diversity of T cells infiltrating rejected and tolerated heart allografts in a model of donor-specific blood transfusion-induced tolerance in MHC-mismatched congeneic rats. The PCR-based method that we used allows the diversity of Vbeta chains at the complementarity-determining region 3 level to be analyzed quantitatively. Our results show that the Vbeta repertoire usage in graft-infiltrating T cells was characteristic and different in tolerated compared with rejected grafts, and differed in both cases from the normal distribution of the Vbeta repertoire. An expansion of lymphocytes showing a conserved Vbeta18-Dbetal-Jbeta2.7 gene rearrangement was found, from the first day after grafting onward, in graft-infiltrating cells from all tolerant animals. This clone accounted for as much as 5% of the whole Vbeta repertoire in tolerated hearts, as evidenced by RNase protection assay. In contrast, we demonstrated that, of lymphocytes infiltrating rejected grafts, those with a Vbeta18 chain were diverse, and that even though by day 5 the conserved Vbeta18-Dbeta1-Jbeta2.7 rearrangement was detectable, lymphocytes harboring this rearrangement represented less than 0.6% of the whole TCR-alphabeta+ T cell repertoire. Kinetics analysis revealed that the expansion of lymphocytes bearing this conserved rearrangement was elicited specifically by donor blood transfusion. Indeed, Vbeta18-Dbeta1-Jbeta2.7 transcripts were detected in PBL from transfused animals as early as 7 days after donor-specific blood transfusion. Finally, we provided evidence that this T cell clone belongs to the CD8+ subset. The putative role in inducing and maintaining the allograft tolerance of the CD8+ T cell clone harboring this public Vbeta18-Dbeta1-Jbeta2.7 rearrangement is discussed.
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PMID:Donor-specific blood transfusion-induced tolerance in adult rats with a dominant TCR-Vbeta rearrangement in heart allografts. 875 33

Administration of subtoxic doses of HgCl2 affects differentially the immune system depending on the strain of rats tested. Susceptible Brown-Norway (BN) rats exhibit a CD4+ T cell-dependent polyclonal activation of B cells; in contrast, Lewis (LEW) rats are resistant and develop an immunosuppression mediated by CD8+ T cells recruited by CD4+ T cells. The mechanisms by which mercury induces immune disorders are poorly understood. We were interested in analyzing the diversity and mercury-mediated changes of the TCR Vbeta repertoire in the BN and LEW strains of rats at different times of HgCl2 exposure. Our results obtained after analysis of lymph node T cells by RNase protection assay, flow cytometry or immunoscope assay (i) were not consistent with a superantigen-like stimulus since we observed neither a V beta-selective expansion nor deletion that would have been expected and (ii) showed that in BN rats, as well as in LEW rats, an increase in the number of T cells was associated with the heterogeneous TCR V beta repertoire, thus supporting a polyclonal T cell activation. However, in BN rats the total number of T cells increased very rapidly, whereas in LEW rats only CD8+ T cells accumulated.
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PMID:Evidence for heterogeneous TCR V beta repertoire expression in mercury-induced immune disorders in rats. 904 8

When naive T lymphocytes are activated and differentiate into memory/effector cells, they down-regulate receptors for constitutive chemokines such as CXCR4 and CCR7 and acquire receptors for inflammatory chemokines such as CCR3, CCR5 and CXCR3, depending on the Th1/Th2 polarization. This switch in chemokine receptor usage leads to the acquisition of the capacity to migrate into inflamed tissues. Using RNase protection assays, staining with specific antibodies, and response to recombinant chemokines, we now show that following TCR stimulation, memory/effector T cells undergo a further and transient switch in receptor expression. CCR1, CCR2, CCR3, CCR5, CCR6 and CXCR3 are down-regulated within 6 h, while CCR7, CCR4, CCR8 and CXCR5 are up-regulated for 2 to 3 days. Up-regulation of CCR7 following TCR stimulation was observed also among resting peripheral blood T cells and required neither co-stimulation nor exogenous IL-2. On the other hand IL-2 down-regulated CXCR5, up-regulated CCR8 and facilitated the recovery of CCR3 and CCR5. Upon TCR stimulation, Th1 and Th2 cells produced comparable sets of chemokines, including RANTES, macrophage inflammatory protein-1beta, I-309, IL-8 and macrophage-derived chemokine, which may modulate surface chemokine receptors and contribute to cell recruitment at sites of antigenic recognition. Altogether these results show that following TCR stimulation effector/memory T cells transiently acquire responsiveness to constitutive chemokines. As a result, T cells that are activated in tissues may either recirculate to draining lymph nodes or migrate to nearby sites of organized ectopic lymphoid tissues.
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PMID:Switch in chemokine receptor expression upon TCR stimulation reveals novel homing potential for recently activated T cells. 1038 67

To investigate the role that translation plays in the stabilization of the IL-2 mRNA, we inhibited protein synthesis in both cis and trans. To block translation in trans, we utilized the inhibitors puromycin (PUR) and cycloheximide (CHX), which differentially effect polysome structure. We found that CHX enhances the stability of IL-2 mRNA in cells stimulated with anti-TCR Ab alone, but it inhibits CD28-induced message stabilization in costimulated cells. In contrast, PUR had a minimal effect on IL-2 mRNA stability in either the presence or absence of costimulation. The differential effects of these two inhibitors suggest that: 1) CHX is unlikely to stabilize the IL-2 mRNA by inhibiting the expression of a labile RNase; 2) CD28-mediated IL-2 mRNA stabilization does not require translation; and 3) IL-2 mRNA decay is not coupled to translation. To block translation in cis, we generated sequence-tagged IL-2 genomic reporters that contain a premature termination codon (PTC). In both the presence and absence of costimulation, these PTC-containing mRNAs exhibit drastically diminished stability. Interestingly, the addition of CHX but not PUR completely restored CD28-mediated stabilization, suggesting that CHX can block the enhanced decay induced by a PTC. Finally, CHX was able to superinduce IL-2 mRNA levels in anti-TCR Ab-stimulated cells but not in CD28-costimulated cells, suggesting that CHX may also act by other mechanisms.
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PMID:The destabilization of IL-2 mRNA by a premature stop codon and its differential stabilization by trans-acting inhibitors of protein synthesis do not support a role for active translation in mRNA stability. 1047 2

The perivascular transmigration and accumulation of macrophages and T lymphocytes in the CNS of mice with experimental autoimmune encephalomyelitis (EAE) may be partly regulated by low m.w. chemotactic cytokines. Using the RNase protection assay and ELISA, we quantified expression of chemokines and chemokine receptors in the spinal cord (SC), brain, and lymph nodes of BV8S2 transgenic mice that developed or were protected from EAE by vaccination with BV8S2 protein. In paralyzed control mice, the SC had increased cellular infiltration and strong expression of the chemokines RANTES, IFN-inducible 10-kDa protein, and monocyte chemoattractant protein-1 and the cognate chemokine receptors CCR1, CCR2, and CCR5, with lower expression of macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, and MIP-2; whereas brain had less infiltration and a lower expression of a different pattern of chemokines and receptors. In TCR-protected mice, there was a decrease in the number of inflammatory cells in both SC and brain. In SC, the reduced cellular infiltrate afforded by TCR vaccination was commensurate with profoundly reduced expression of chemokines and their cognate chemokine receptors. In brain, however, TCR vaccination did not produce significant changes in chemokine expression but resulted in an increased expression of CCR3 and CCR4 usually associated with Th2 cells. In contrast to CNS, lymph nodes of protected mice had a significant increase in expression of MIP-2 and MIP-1beta but no change in expression of chemokine receptors. These results demonstrate that TCR vaccination results in selective reduction of inflammatory chemokines and chemokine receptors in SC, the target organ most affected during EAE.
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PMID:Reduced chemokine and chemokine receptor expression in spinal cords of TCR BV8S2 transgenic mice protected against experimental autoimmune encephalomyelitis with BV8S2 protein. 1072 56

KRN TCR transgenic T cells recognize two self-MHC molecules: a foreign peptide, bovine RNase 42-56, on I-Ak and an autoantigen, glucose-6-phosphate isomerase 282-294, on I-Ag7. Because the latter recognition event initiates a disease closely resembling human rheumatoid arthritis, we investigated the structural basis of this pathogenic TCR's dual specificity. While peptide recognition is altered to a minor degree between the MHC molecules, we show that the receptor's cross-reactivity critically depends upon a TCR contact residue completely conserved in the foreign and self peptides. Further, the altered recognition of peptide derives from discrete differences on the MHC recognition surfaces and not the disparate binding grooves. This work provides a detailed structural comparison of an autoreactive TCR's interactions with naturally occurring peptides on distinct MHC molecules. The capacity to interact with multiple self-MHCs in this manner increases the number of potentially pathogenic self-interactions available to a T cell.
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PMID:Molecular basis for recognition of an arthritic peptide and a foreign epitope on distinct MHC molecules by a single TCR. 1082 Feb 57

NO is a potent cellular mediator which has been shown to modulate several immune mechanisms. Using human T lymphocytes as responder cells in a primary mixed lymphocyte reaction, we demonstrated that, at the initiation of the culture, exogenously provided NO via sodium nitroprusside, in non-toxic concentrations, inhibited both allogeneic proliferative and primary cytotoxic responses in a dose-dependent manner. In contrast, it had no effect on the cytotoxic activity of established human TCR (alpha)beta and TCR (gamma)delta cytotoxic T lymphocyte (CTL) clones. The NO inhibitory effect on primary cytotoxic T cell response correlates with inhibition of T cell blastogenesis. Furthermore, under our stimulation conditions, NO induced an inhibition of IL-2 production, an alteration of IL-2R(alpha) expression, and a down-regulation of NF-AT translocation in CD4(+) and CD8(+)allostimulated T cells. Furthermore, we demonstrate that the inhibition of allospecific CTL activity by the NO donor was at least in part related to an inhibition of granzyme B and Fas ligand transcription as revealed respectively by RNase protection and RT-PCR analysis. These results suggest that NO may function to fine tune human CD3(+) T cell activation and subsequent CTL generation.
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PMID:Analysis of the mechanisms of human cytotoxic T lymphocyte response inhibition by NO. 1235 82

In Lewis rats infected intracerebrally with the highly neurotropic Borna disease virus (BDV), the retina is one of the most severely affected central nervous system (CNS) structures. While BDV-induced damage in the brain has been previously shown to be caused by a T-cell-dependent process, the immunopathological mechanisms leading to BDV-induced retinitis remain to be elucidated. RNA samples from retinae were subjected to RNase protection assays to detect transcripts of proinflammatory cytokines and chemokines known to be involved in the recruitment of T-cells and macrophages in the CNS. The observed expression profile of proinflammatory cytokines and chemokines, as well as the immunohistochemical detection of alpha beta TCR-positive, CD4- and CD8-positive T-cells in the BDV-infected retinae, is reminiscent of the situation observed in the brains of Lewis rats during the acute phase of Borna disease (BD). This suggests that similar immunopathological mechanisms are operating in retinae and brains of infected rats.
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PMID:Characterization of the acute immune response in the retina of Borna disease virus infected Lewis rats. 1266 49


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