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:C0014070 (encephalomyelitis)
13,017 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory neurological disease initiated by activated T cells specific for the autoantigen, myelin basic protein (MBP). The ability of Lewis rat splenic T cells to transfer EAE after in vitro incubation with MBP-pulsed dendritic cells (DC) was used as an index of MBP-specific T cell activation. OVA, previously processed by macrophages, was incubated with MBP and DC at the pulsing stage to determine whether it could inhibit presentation of the autoantigen. At molar equivalents of 2.5:1 and 20:1 relative to MBP, processed OVA increasingly inhibited the ability of DC to activate MBP-specific T cells for EAE transfer. Unprocessed OVA, which cannot be presented immunogenically by Lewis rat DC, was much less effective. However, processed OVA added to DC after they had been pulsed with MBP could not compete. OVA also blocked appearance of EAE when mixed with MBP/CFA in the inoculum used for active induction of the disease. Splenic T cells from MBP + OVA/CFA-immunized rats transferred EAE with a substantially delayed onset, suggesting that a reduced number of MBP-specific T cells was generated by immunizing with the OVA + MBP mixture compared with MBP alone. Overall, the data indicate that fragments of a foreign protein, OVA, which can be bound by APC, can also inhibit presentation of encephalitogenic determinants of MBP to T cells.
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PMID:Competition between foreign and self proteins in antigen presentation. Ovalbumin can inhibit activation of myelin basic protein-specific T cells. 168 45

Experimentally induced and naturally occurring inflammatory diseases of the central nervous system (CNS) are often associated with a breakdown of the blood-brain barrier and edema within the CNS itself. CD4+ T cells are now clearly implicated in the pathogenesis of the induced CNS disease, experimental autoimmune encephalomyelitis, and previous in vivo experiments had indicated that these cells may be capable of directly damaging the CNS vasculature. To assess the capacity of CD4+ T cells to damage brain vascular endothelial cells (EC) in vitro, two lines with specificity for myelin basic protein and OVA were prepared and added to cultures of EC. We show here that both lines, when added in a resting state, severely disrupt the EC monolayers in an Ag-specific manner. The interaction is dependent on the recognition of Ag in the context of MHC class II and is blocked in the presence of mAb specific for CD4. Addition of T cell lines preactivated on irradiated thymocyte APC caused a high level of Ag nonspecific damage to the EC, which was not blocked by the addition of anti-CD4 mAb. Supernatants derived from these latter cells did not alone damage the EC monolayers despite the presence of TNF activity suggesting that T cell-EC contact may be required for these cell lines to mediate their effector function. Both resting and preactivated lines adhered strongly to the EC in the absence of Ag. The capacity of CD4+ T cells to strongly adhere to, and disrupt the integrity of, brain vascular EC may be important in the early stages of CNS disease mediated by this cell type.
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PMID:Antigen-specific damage to brain vascular endothelial cells mediated by encephalitogenic and nonencephalitogenic CD4+ T cell lines in vitro. 169 55

To determine if the Ag that induces an autoimmune disease influences parental MHC haplotype molecule expression in situ in MHC heterozygotes, acute experimental allergic encephalomyelitis (EAE) was induced with different encephalitogenic peptides in (SJL/J x SWR)F1 mice. The mice were sensitized with either a synthetic peptide corresponding to mouse myelin proteolipid protein (PLP) residues 103-116 YKTTICGKGLSATV which induces EAE in SWR (H-2q), but not SJL/J (H-2s) mice or a synthetic peptide corresponding to PLP residues 139-151 HCLGKWLGHPDKF which is encephalitogenic in SJL/J but not SWR mice. Mice were killed when they were moribund or at 30 days after sensitization. Twelve of 18 F1 mice given PLP peptide 103-116 and 12 of 17 mice given PLP peptide 139-151 developed EAE within 2 to 3 wk after sensitization. Cryostat sections of brain samples from F1 and parental mice were immunostained with a panel of mAb identifying H-2s and H-2q class I and II MHC molecules. In brains of controls, class I MHC molecules were expressed on choroid plexus, endothelial cells, and microglia whereas class II MHC molecules were absent. In EAE lesions, class I and II MHC molecules were present on inflammatory and parenchymal cells, but the degree of parental haplotype molecule expression did not vary with the different peptide Ag tested. Thus, in (SJL/J x SWR)F1 mice, myelin PLP peptides 103-116 and 139-151 are co-dominant Ag with respect to clinical and histologic disease and parental haplotype MHC molecule expression. We propose a unifying hypothesis consistent with these results and previous observations of differential Ia expression in (responder x non-responder)F1 guinea pigs. We suggest that MHC molecules may bind locally derived peptide Ag in inflammatory sites and that these interactions influence levels of MHC haplotype molecules on APC.
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PMID:Parental MHC molecule haplotype expression in (SJL/J x SWR)F1 mice with acute experimental allergic encephalomyelitis induced with two different synthetic peptides of myelin proteolipid protein. 170 6

Two monoclonal antibodies, OX-6 and OX-17, were used to evaluate respectively the roles of I-A and I-E major histocompatibility complex Class II gene products in the in vitro activation and subsequent function in recipient rats of encephalitogenic T-cell lines. Activation of the T-cell lines with guinea pig myelin basic protein (GP-BP) presented by accessory cells (APC) resulted in an increase in the number of blast cells in culture and was reflected by increased uptake of [3H]thymidine [( 3H]Tdy). The number of blasts recovered and [3H]Tdy uptake during activation was reduced drastically in the presence of OX-6, but to a much lesser extent in the presence of OX-17. OX-6 but not OX-17 appeared to block T-cell activation primarily by inhibiting APC function, since preincubation of APC but not T cells with OX-6 before stimulation resulted in complete inhibition of the cultures. After activation, the BP-1 T-cell line or D-9 clone transferred severe paralysis to normal recipient rats. Recipients of OX-6-treated BP-1 or D-9 T cells exhibited very mild or no signs, whereas recipients of OX-17-treated cells developed only slightly less severe experimental autoimmune encephalomyelitis (EAE) than recipients of untreated encephalitogenic control cultures. In contrast, treatment with OX-17 but not OX-6 reduced the ability of BP-reactive T cells to transfer delayed-type hypersensitivity reactions. Dermal testing with GP-BP in the ears of recipient rats just prior to onset of clinical signs decreased significantly the clinical intensity of EAE induced by activated BP-reactive T cells, but increased the clinical scores in rats which received unstimulated or OX-6-treated T cells. This potentiating effect of GP-BP was due most likely to the presentation of processed antigen to circulating BP-reactive T cells by APC in the ear. These results suggest that both the I-A and I-E gene products may contribute to the activation and subsequent function of encephalitogenic T cells, perhaps through separate mechanisms.
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PMID:Antibodies against I-A and I-E determinants inhibit the activation and function of encephalitogenic T-lymphocyte lines. 242 9

Experimental allergic encephalomyelitis (EAE)-susceptible Lew and EAE-resistant Brown Norway (BN) rats and the corresponding MHC congenic strains were examined for their ability to develop clinical and histologic EAE. The ability of T cells from these animals to proliferate in vitro in response to whole guinea pig (GP) myelin basic protein (MBP), rat MBP, and to the major encephalitogenic peptide of GP MBP 66-88 (GP 68-88) was also assessed. We found that Lewis (Lew) was highly susceptible and showed good T cell responses to GP, MBP, rat MBP, and GP 68-88. Lew.1N (BN MHC on Lew background) and BN were not susceptible and T cells from these strains showed significant responses to GP MBP, but not to rat MBP or GP 68-88. Although BN.B1 (Lew MHC on BN background) was not susceptible to actively induced EAE, MBP-specific Lew T cells could transfer severe disease to BN.B1. BN.B1 T cells showed responses to GP-MBP, rat MBP, and GP 68-88 and, when transferred to naive BN.B1 or Lew, induced only mild clinical EAE in both strains. Increasing the number of T cells from BN.B1 had no effect on the severity of clinical symptoms in either recipient, suggesting some deficiency in the T cell repertoire that is necessary for induction of severe EAE. These results suggest that 1) the T cell response to rat MBP and GP68-88 (but not to sites other than 68-88 in GP MBP) is necessary for susceptibility to EAE; 2) the ability to respond to both rat MBP and GP 68-88 is determined by the MHC gene products on APC; and 3) given a permissive MHC, the T cell response that results in EAE is influenced by non-MHC genes.
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PMID:Genetic control of the development of experimental allergic encephalomyelitis in rats. Separation of MHC and non-MHC gene effects. 245 18

The encephalitogenic potential of a segment of myelin basic protein in experimental autoimmune encephalomyelitis is not always mirrored by the ability of the peptide to mediate in vitro activation of encephalitogenic T cells. Recent studies from our laboratory have demonstrated that the responsiveness of Ag-specific T cells in experimental autoimmune encephalomyelitis is determined not exclusively by Ag but also by the nature of the APC. By varying APC during the in vitro selection of T cells, we could generate distinct sets of rat encephalitogenic T cells, as evidenced by the diversity of TCR usage. Here we establish the importance of APC in the activation of rat encephalitogenic T cells by myelin basic protein peptides. Peptides 69-84-Gly and (P80)68-86, which lacked stimulatory activity toward many encephalitogenic T cells in our proliferation assay when standard APC were used, become strongly stimulatory in the presence of less commonly used APC, i.e., an Ia+ T cell clone (LOA) or an Ia-inducible rat glial cell clone (F10). Nonstimulatory APC failed to activate encephalitogenic T cells even when major cytokines were added, suggesting that these cytokines are not among the factors limiting the activating potential of the APC. Thus, whether or not an immunocompetent T cell can be activated by a given Ag in an autoimmune response may be determined by the properties of APC. This finding has implications for current research efforts to identify pathogenic self proteins.
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PMID:Major role of antigen-presenting cells in the response of rat encephalitogenic T cells to myelin basic proteins. 768 28

A fundamental issue in the etiology of autoimmune diseases of the central nervous system such as multiple sclerosis and its animal counterpart experimental autoimmune encephalomyelitis (EAE) concerns the identity of cells capable of presenting autoantigen to the T cells that mediate these diseases. The prevailing dogma is that only bone marrow-derived cells function as APC during EAE induction. We have addressed this issue by studying EAE induction in mouse bone marrow chimeras, and have found that although bone marrow-derived APC such as macrophages and brain microglial cells are more efficient at presenting autoantigen, brain parenchymal cells such as astrocytes and endothelial cells are also capable of inducing disease. EAE was induced in these chimeras by the adoptive transfer of encephalitogenic T cell lines designed to be MHC-histocompatible with APC contained either within the hematopoietic system of the chimera or with APC resident to the brain of the chimera. The subsequent development of EAE in these chimeras then indicated which population of cells served as in vivo APC during EAE pathogenesis. Possible effects of alloreactivity between the host chimera and the adoptively transferred T cells were eliminated by using encephalitogenic T cell lines made tolerant to the haplotype(s) of the recipient chimera.
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PMID:In vivo antigen presentation by both brain parenchymal cells and hematopoietically derived cells during the induction of experimental autoimmune encephalomyelitis. 768 95

Ramified microglia in the adult central nervous system (CNS) are the principal glial element up-regulating MHC class I and II expression in response to inflammatory events or neuronal damage. A proportion of these cells also express MHC class II constitutively in the normal CNS. The role of microglia as APCs for CD4+ T cells extravasating into the CNS remains undefined. In this study, using irradiation bone marrow chimeras in CD45-congenic rats, the phenotype CD45lowCD11b/c+ is shown to identify microglial cells specifically within the CNS. Highly purified populations of microglia and nonmicroglial but CNS-associated macrophages (CD45highCD11b/c+) have been obtained directly from the adult CNS, by using flow cytometric sorting. Morphologically, freshly isolated microglia vs other CNS macrophages are quite distinct. Of the two populations recovered from the normal CNS, it is the minority CD45highCD11b/c+ transitional macrophage population, and not microglia, that is the effective APC for experimental autoimmune encephalomyelitis-inducing CD4+ myelin basic protein (MBP)-reactive T cells. CD45highCD11b/c+ CNS macrophages also stimulate MBP-reactive T cells without addition of MBP to culture, suggesting presentation of endogenous Ag. This is the first study in which microglia vs other CNS macrophages have been analyzed for APC ability directly from the CNS, with substantial cross-contamination between the two populations eliminated. The heterogeneity of these populations in terms of APC function is clearly demonstrated. Evidence is still lacking that adult CNS microglia have the capacity to interact with and stimulate CD4+ T cells to proliferate or secrete IL-2.
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PMID:Normal adult ramified microglia separated from other central nervous system macrophages by flow cytometric sorting. Phenotypic differences defined and direct ex vivo antigen presentation to myelin basic protein-reactive CD4+ T cells compared. 772 89

Severe combined immunodeficient (SCID) C.B-17-scid/scid (H-2d) strain mice are deficient for T and B lymphocytes and lack all of the immune functions associated with these cell types. Experimental autoimmune encephalomyelitis (EAE) was induced in chimeric SCID mice that had been previously reconstituted with allogeneic mouse or xenogeneic rat hematopoietic stem cells from EAE-susceptible donor strains. Encephalitogenic, myelin Ag-specific, T lymphocytes selected from SJL mice, Lewis rats, or Buffalo rats transferred passive EAE into chimeric SCID mice reconstituted with SJL mouse, Lewis rat, or Buffalo rat hematopoietic cells, respectively. SCID mice reconstituted with Lewis rat hematopoietic tissue and thymus were also susceptible to EAE induced by active immunization with the myelin proteolipid protein synthetic peptide PLP S139-151. T lymphocytes recovered from the spleens of SCID mouse-rat chimeras with EAE proliferated upon in vitro stimulation with myelin Ag presented by APC syngeneic to the transplant donor, and rat T lymphocytes selected in vitro from SCID mouse-rat chimeras with EAE transferred EAE back into naive recipient rats. Thus, the immunodeficiency present in SCID mice can be overcome at least partially by hematopoietic tissue transplantation from allogeneic or xenogeneic donors. Furthermore, allogeneic SJL mouse and xenogeneic Lewis or Buffalo rat myelin Ag-specific T cells can transfer EAE between strains and species, respectively, into recipient SCID mouse chimeras.
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PMID:Induction of experimental autoimmune encephalomyelitis in severe combined immunodeficient mice reconstituted with allogeneic or xenogeneic hematopoietic cells. 809 58

CD4+ T cells promote immune responses against foreign Ags while actively suppressing responses against self Ags. To address how CD4+ T cells ensure self-tolerance, we focused on two CD4+ T helper cells specific for myelin basic protein (MBP). GP2.E5/R1 T cells recognized rat MBP (RMBP) as a partial agonist and mediated mild experimental autoimmune encephalomyelitis (EAE), whereas R2 T cells recognized RMBP with full efficacy and mediated severe EAE. GP2.E5/R1 T cells were more susceptible to anergy induction than R2 T cells. Anergic GP2.E5/R1 T cells lacked proliferative reactivity, but expressed both I-A glycoproteins and high levels of radioresistant APC activity. During induction of anergy, these T cells acquired the ability to present MBP. In a separate subsequent culture without further addition of Ag, anergic GP2.E5/R1 T cells elicited full proliferative and IL-2 production responses by R2 T cells. Unlike activations induced via irradiated splenocytes, irradiated anergic T cells elicited anergy in R2 T cells in the form of a postactivational phase of nonresponsiveness. Anergic GP2.E5/R1 T cells not only transferred anergy to pathogenic R2 T cells in vitro, but these anergic T cells also transferred resistance to EAE in Lewis rats subsequently challenged with guinea pig MBP in CFA. Antagonistic signaling by autologous RMBP was more tolerogenic than that of guinea pig MBP in both in vitro and in vivo models of infectious anergy. We conclude that in the presence of tolerogenic mAb, antagonistic signaling by a self protein elicited the coordinate expression of anergy and T cell-mediated APC activity as a mechanism for the genesis and spread of infectious tolerance.
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PMID:Anergy-associated T cell antigen presentation. A mechanism of infectious tolerance in experimental autoimmune encephalomyelitis. 875 10


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