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Comparison of the amelioration effects of two enzyme inducers on the inflammatory process of experimental allergic encephalitis (EAE) using immunohistochemical technique.

Experimental Allergic Encephalitis (EAE) is a T-cell mediated autoimmune disease, which resembles the human disease Multiple Sclerosis (MS) in rodents. The infiltration of inflammatory cells and the induction of astrocyte proliferation correlate with EAE severity. Oxidative stress is postulated to have a role in the onset and progression of MS. Therefore, by reducing oxidative stress via phase II enzymes inducers; namely the butylhydroxyanisole (BHA) and Thymoquinone (glutathione inducer), the inflammation could be ameliorated. EAE was induced in Lewis rats using Myelin Basic Protein (MBP) and complete Freund's adjuvant (CFA). Animals were placed into 1. those on normal rat chow, 2. those on rat chow containing BHA, 3. those receiving concomitant five day injection of thymoquinone days 1-5 post-EAE induction, 4. those receiving five doses of thymoquinone injected at day 12-17 post-EAE induction. Twenty-nine days later, animals from each group were sacrificed and tissues collected for immunohistochemistry using the anti-glial fibrillary acid (GFAP) antibody to examine the amelioration effect these two agents have on the inflammatory process occurring in EAE by examining the astrocyte proliferation in the Central Nervous System (CNS).

Animals↗

Association between the effacing (eae) gene and the Shiga-like toxin-encoding genes in Escherichia coli isolates from cattle.

Two hundred ninety-six Escherichia coli isolates from feces or intestines of calves with diarrhea were hybridized with 7 gene probes. One probe (the eae probe) was derived from the eae gene coding for a protein involved in the effacement of the enterocyte microvilli by the group of bacteria called attaching and effacing E coli (AEEC), and 2 probes were derived from genes coding for the Shiga-like toxins (SLT) 1 and 2 produced by the verocytotoxic E coli (VTEC). The other 4 probes were derived from DNA sequences associated with the adhesive properties of enteroadherent E coli (EAEC) to cultured cells (the EAF probe for the localized adherence pattern, probes F1845 and AIDA-1 for the diffuse adherence pattern, and the Agg probe for the aggregative adherence pattern). Hybridization results for the eae probe were in agreement, for all but 1 of the 8 isolates, with previously published phenotypic results of microvilli effacement. The latter was previously reported as effacing the microvilli of calf enterocytes, but was eae probe-negative. Two classes of isolates hybridized with the eae probe. Members of a first class (60 isolates) additionally produced a positive signal with 1 or both of the SLT probes (VTEC-AEEC isolates). Isolates hybridizing with the eae and the SLT1 probes were the most frequent: 56 isolates (ie, 93% of all VTEC-AEEC). Members of the second class (10 isolates) failed to hybridize with either SLT probe (non-VTEC-AEEC isolates).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Therapeutic activity of malononitrilamides (MNA 279 and MNA 715) on acute and chronic, relapsing, experimental, allergic encephalomyelitis (EAE).

Due to their immunosuppressive mode of action, we examined the therapeutic effects of the malononitrilamides MNA 279 and MNA 715 in acute EAE, and two models of chronic relapsing EAE in Lewis rats and Biozzi mice. In the first model, sensitization of adult Lewis rats with guinea pig spinal cords results in an acute clinical episode of severe EAE, and by day 15 all animals had died. Treatment of these sensitized rats with the MNAs was most effective in delaying and reducing the onset of clinical symptoms, and mortality of acute EAE was prevented in a dose-dependent manner. The protection afforded by the two MNAs was long-lasting and no subsequent relapse was observed. Similarly, in the chronic relapsing disease, aged Lewis rats were immunized with rabbit myelin basic protein, and all untreated animals developed a disease with up to three relapses. The second and third episodes were both milder and shorter in duration than the first. All animals treated with the MNAs survived the first attack, which also was delayed. Pathological signs were reduced and relapses did not occur. Inhibition of chronic relapsing EAE in aged Lewis rats was observed, even when the MNA-treatment was started after the first appearance of clinical symptoms. All treated animals recovered completely and mortality was prevented. Also in the second model of chronic relapsing EAE in Biozzi AB/H mice, MNA treated animals showed only one acute and delayed episode and no further relapses. All these results qualify both MNA 279 and MNA 715 as powerful immunosuppressants with therapeutic potential in human multiple sclerosis (MS).

Acute Disease↗

Sodium channels contribute to microglia/macrophage activation and function in EAE and MS.

Loss of axons is a major contributor to nonremitting deficits in the inflammatory demyelinating disease multiple sclerosis (MS). Based on biophysical studies showing that activity of axonal sodium channels can trigger axonal degeneration, recent studies have tested sodium channel-blocking drugs in experimental autoimmune encephalomyelitis (EAE), an animal model of MS, and have demonstrated a protective effect on axons. However, it is possible that, in addition to a direct effect on axons, sodium channel blockers may also interfere with inflammatory mechanisms. We therefore examined the novel hypothesis that sodium channels contribute to activation of microglia and macrophages in EAE and acute MS lesions. In this study, we demonstrate a robust increase of sodium channel Nav1.6 expression in activated microglia and macrophages in EAE and MS. We further demonstrate that treatment with the sodium channel blocker phenytoin ameliorates the inflammatory cell infiltrate in EAE by 75%. Supporting a role for sodium channels in microglial activation, we show that tetrodotoxin, a specific sodium channel blocker, reduces the phagocytic function of activated rat microglia by 40%. To further confirm a role of Nav1.6 in microglial activation, we examined the phagocytic capacity of microglia from med mice, which lack Nav1.6 channels, and show a 65% reduction in phagocytic capacity compared with microglia from wildtype mice. Our findings indicate that sodium channels are important for activation and phagocytosis of microglia and macrophages in EAE and MS and suggest that, in addition to a direct neuroprotective effect on axons, sodium channel blockade may ameliorate neuroinflammatory disorders via anti-inflammatory mechanisms.

Animals↗

Estrogen inhibition of EAE involves effects on dendritic cell function.

Estrogen has been found to have suppressive effects on the induction of experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. We have investigated the effects of 17beta-estradiol (E2) treatment on dendritic cells (DCs) in two different mouse models of EAE. The frequency of CD11b(+)/CD11c(+) DCs was significantly decreased in the brain of mice protected from EAE induction by E2 treatment. In addition, the frequency of CD11c(+)/CD8alpha(+) DCs producing tumor necrosis factor (TNF)alpha and interferon (IFN)gamma in the spleen of E2-treated mice was dramatically decreased compared to that in control mice with EAE, demonstrating an effect of E2 on DC function. In order to examine E2 effects on DCs in more detail, splenic DCs were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 to promote maturation. E2 pretreatment was found to suppress the ability of cultured DCs bearing a mature phenotype to present Ag to myelin basic protein (MBP)-specific T cells. Analysis of cytokine production demonstrated that E2 decreased TNFalpha, IFNgamma and IL-12 production in mature DCs. In addition, MBP-specific T cells cocultured with E2-pretreated mature DCs in the presence of antigen demonstrated a shift towards production of Th2 cytokines IL-4 and IL-10 and a concomitant decrease in the production of Th1 cytokines TNFalpha and IFNgamma. Thus, E2 treatment appears to have multiple effects on the DC population, which may contribute to a down-regulation or block in the activation of Th1 cells involved in the induction of EAE.

Animals↗

Distribution in ocular structures and optic pathways of immunocompetent and glial cells in an experimental allergic encephalomyelitis (EAE) relapsing model.

Relapsing experimental allergic encephalomyelitis (EAE) was induced in DA rats and the ocular pathologic events were examined at the various phases of the illness. About 80% of EAE rats presented anterior uveitis (AU), even after complete EAE recovery. We studied the phenotype and localization of immunocompetent cells, the major histocompatibility complex (MHC) class I and II antigen expression, as well as the chemokine monocyte chemoattractant protein-1 (MCP-1) appearance. In control animals, there were many glial fibrillary acidic protein (GFAP)(+) cells and OX42(+) cells in the ciliary body, retina, optic nerve and chiasma. Except in retina, we observed constitutive MHC class I and II expression. During the EAE acute phase, there was up-regulation of MHC class II and GFAP antigens in iris, ciliary body, limbus, and optic pathways. MHC class I and ED2 antigens were expressed in meninges and in the prechiasmatic cisterna, by cells which could have a role in immune surveillance. MCP-1 mRNA was highly expressed in optic pathways during the acute phase and the protein was expressed by astrocytes, macrophages, and lymphocytes. During the relapsing phase, MCP-1 was weakly expressed to disappear almost completely during the final recovery phase. The expression of MHC class II on astrocytes was increased during the relapsing and final recovery phase in which the inflammatory lesions persisted. These findings suggest that ocular areas and optic pathways, mainly optic chiasma, are important targets in the relapsing EAE.

Animals↗

Adoptively transferred EAE in gamma delta T cell-knockout mice.

Recently there has been evidence suggesting that gamma delta receptor-bearing T cells may play a role in both multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE). We have recently described approaches for the generation of encephalitogenic T-cell populations from EAE-resistant strains of mice. Using encephalitogenic T-cell lines and clones generated from wild-type C57BL/6 mice we have studied adoptively transferred EAE in C57BL/6-TCR delta-knockout mice. We now report that the adoptive transfer of encephalitogenic T cells into TCR delta T-knockout mice leads to clinical EAE that is not significantly different in severity or time course than that seen after transfer into wild-type C57BL/6 mice. We conclude that gamma delta T cells do not play an integral role in the mediation or regulation of the effector-phase mechanisms in EAE.

Adoptive Transfer↗

Diversity of the B cell repertoire to myelin basic protein in rat strains susceptible and resistant to EAE.

Myelin basic protein (MBP) is a major protein of central nervous system myelin which can induce experimental autoimmune encephalomyelitis (EAE) in susceptible laboratory animals. The role of T cells in the induction of EAE has been extensively studied, but the antibody response to MBP has not been well characterized. In the present work, we immunized rats with encephalitogenic guinea-pig MBP and mapped autoreactive antibodies binding to peptides in the rat MBP sequence. We studied the responses of the Lewis rat strain, susceptible to EAE, and the responses of the Fischer and Brown-Norway (BN) rats, resistant to EAE. We found that Lewis rats immunized to guinea-pig MBP develop antibodies to a diversity of MBP epitopes with a dominance of MBP peptide p11-30 and peptides in the 71-140 region. Fischer rats showed a similar pattern of antibody specificities, but with higher titers than the Lewis rats. BN rats, in contrast, developed a very low titer of antibodies and lacked a response to p11-30. Thus, there is no clear correlation between the nature of the anti-MBP antibody response and the state of susceptibility or resistance to EAE induction in the different rat strains.

Amino Acid Sequence↗

Effect of the leukotriene B4 receptor antagonist, SC-41930, on experimental allergic encephalomyelitis (EAE) in the guinea pig.

The accepted model for the human demyelinating disease, multiple sclerosis (MS), is experimental allergic encephalomyelitis (EAE). We assessed the ability of SC-41930(7-[3(4-acetyl-3-methoxy-2-propyl-phenoxy)-propoxy]- 3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxyl acid), to modulate the symptoms of acute EAE generated in guinea pigs. Animals were pretreated with SC-41930 (20 mg/kg, i.p.) for two days followed by thrice-weekly maintenance. At day 52, a significant number of the SC-41930-treated animals were alive as compared to EAE alone. Control animals had an increase in body weight while EAE animals lost over 20% (p less than 0.5) of their body weight by day 18. SC-41930-treatment significantly reduced, but did not completely inhibit the cachectic response. The results indirectly implicate LTB4 in the pathogenesis of EAE. Agents that modify this model be useful in the treatment of human MS.

Animals↗

Genetic control of resistance to clinical EAE accompanied by histological symptoms.

The susceptibility of rats to experimental allergic encephalomyelitis (EAE) induced by myelin basic protein (MBP) was studied in a variety of genetic crosses. Rats were evaluated according to weight loss, neurological symptoms, and histological criteria. The results demonstrate that three different types of genes are involved in susceptibility. An RT1-linked gene is necessary but not sufficient for full expression of EAE induced by MBP in complete Freund's adjuvant (CFA). Additional genes are required for the occurrence of histological EAE, but a full-blown inflammatory reaction is not sufficient for the expression of clinical EAE. A third type of gene, which can be demonstrated in appropriate crosses, is required for the consistent expression of clinical symptoms. Dominant genes for resistance to clinical symptoms were transferred to the Lewis (LEW) background from the BN.B1 strain through two generations of backcrossing. Thus, there are genetically controlled mechanisms involved in the neurological expression of EAE which are independent of the inflammatory reaction as observed in central nervous system (CNS) histology.

Animals↗

Inflammation in EAE: role of chemokine/cytokine expression by resident and infiltrating cells.

Experimental allergic encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) which has many clinical and pathological features in common with multiple sclerosis (MS). Comparison of the histopathology of EAE and MS reveals a close similarity suggesting that these two diseases share common pathogenetic mechanisms. Immunologic processes are widely accepted to contribute to the initiation and continuation of the diseases and recent studies have indicated that microglia, astrocytes and the infiltrating immune cells have separate roles in the pathogenesis of the MS lesion. The role of cytokines as important regulatory elements in these immune processes has been well established in EAE and the presence of cytokines in cells at the edge of MS lesions has also been observed. However, the role of chemokines in the initial inflammatory process as well as in the unique demyelinating event associated with MS and EAE has only recently been examined. A few studies have detected the transient presence of selected chemokines at the earliest sign of leukocyte infiltration of CNS tissue and have suggested astrocytes as their cellular source. Based on these studies, chemokines have been postulated as a promising target for future therapy of CNS inflammation. This review summarized the events that occur during the inflammatory process in EAE and discusses the roles of cytokine and chemokine expression by the resident and infiltrating cells participating in the process.

Animals↗

The role of myelin lipids in experimental allergic encephalomyelitis. III. Transfer of suppression from guinea pigs recovering from EAE, induced by myelin basic protein--galactocerebroside complexes.

Juvenile strain 13 guinea pigs were immunized with myelin basic protein (MBP) combined with galactocerebrosides (MBP + GC) or with total myelin lipids without GC [MBP + (TL-GC)] in CFA. Control animals received dinitrophenylated-ovalbumin (DNP-OA) in CFA, CFA or IFA alone. The animals injected with MBP + GC showed a higher rate of recovery from the first EAE episode (83%) than those treated with MBP + (TL-GC) (50%). With the exception of the group treated with IFA alone, all animals were refractory to EAE following rechallenge with MBP in CFA 90 days after the first exposure. The in vitro proliferative response to MBP, of peripheral blood lymphocytes (PBLs) derived from guinea pigs freshly sensitized to MBP in CFA, was drastically suppressed in the presence of PBLs from animals injected with MBP + GC. Upon transfer to normal syngeneic recipients, spleen cells from MBP + GC-treated animals completely suppressed the clinical and histological manifestations of EAE following recipient challenge with MBP in CFA. Cell-free supernatants from PBLs and spleen cells of strain 13 guinea pigs treated with MBP + GC inhibited lymphocyte proliferation to MBP, of allogeneic responder cells, and spleen cell supernatants completely suppressed the induction of EAE upon transfer to allogeneic recipients. Suppression could not be transferred with cells from other treated groups. These results suggest that animals immunized with MBP + galactocerebrosides in CFA develop suppressor cells that may be in part responsible for the recovery from the first EAE episode and for protection against rechallenge with MBP in CFA. Their cell-free supernatants act in an MHC-nonrestricted fashion. These results do not rule out an additional protective mechanism since all animals exposed to CFA were refractory to rechallenge despite lack of demonstrable suppressor cell activity.

Animals↗

Encephalitogenic T cells in the B10.PL model of experimental allergic encephalomyelitis (EAE) are of the Th-1 lymphokine subtype.

T helper cells reactive to myelin basic protein are clearly implicated in the pathogenesis of murine EAE. We have developed a T cell line, BML-1 that (1) is reactive to the encephalitogenic amino terminal nonapeptide (1-9NAC) of MBP, (2) is I-Au restricted, and (3) induces relapsing EAE in B10.PL (H-2u) mice. Measurement of the lymphokine profile of BML-1 revealed secretion of IL-2, interferon-gamma and lymphotoxin but not IL-4. This profile is consistent with the Th1/DTH subtype. Coculture of BML-1 with MBP-primed B cells shows that BML-1 does not provide significant helper function in vitro. In addition, BML-1 secretion of interferon-gamma was found to inhibit LPS-induced anti-MBP antibody responses. This suggested that anti-MBP antibodies may not be necessary for induction of EAE. Sera from mice, in which severe disease was induced with the 1-9NAC peptide and Bordetella pertussis, showed no development of serum antibodies to MBP. These data show that MBP-reactive Th cells of the Th-1/DTH subtype can induce EAE and do not provide Th function for anti-MBP responses and that serum anti-MBP antibodies are not found in peptide 1-9NAC-induced disease. T cell lines specific for encephalitogenic epitopes and characterized for lymphokine secretion will provide a useful tool for understanding the role of T cells in the induction of EAE.

Animals↗

Effect of treatment with Copolymer 1 (Cop-1) on the in vivo and in vitro manifestations of experimental allergic encephalomyelitis (EAE).

Injections of Copolymer 1 (Cop-1), a synthetic cathodic polymer, have been reported to prevent and treat successfully acute and recurrent EAE and has been employed in patients with multiple sclerosis (MS). It has been suggested that the therapeutic effect is due to cell-mediated immune (CMI) cross-reactivity between Cop-1 and myelin basic protein (MBP), the antigen that induces EAE. We found that Cop-1 treatment of guinea pigs (GP) sensitized with MBP in adjuvant (20 micrograms/animal): (a) lowers the incidence of clinical disease (8/20 vs 14/15); (b) decreases severity of disease in affected GP; (c) has little effect on pathologic lesions (mean pathology index +/- SEM: 1.2 +/- 0.2 vs 1.6 +/- 0.3; P greater than 0.1). Lymphocytes of MBP-sensitized GP treated with Cop-1 exhibited in vitro proliferative responses to MBP equivalent to lymphocytes of untreated EAE-GP (14,134 +/- 6,532 vs 11,821 +/- 3,874; mean cpm +/- SEM). GP sensitized to MBP or Cop-1 (100 micrograms/animal) showed reactivity to the sensitizing antigen but little in vitro reactivity to the other antigen. There was no correlation between the in vitro lymphocytes response to MBP and Cop-1 in individual GP. Treatment of MBP sensitized GP with calf-thymus histone (CTH) also resulted in a lower incidence of clinical EAE with less severe disease in affected GP. There was little effect on the pathologic index and no evidence of either inhibition of MBP-induced lymphocyte proliferative responses or cross-reactivity between MBP and CTH. Thus, treatment with Cop-1 or CTH inhibits clinical manifestations of acute EAE without suppressing inflammatory cell infiltrates or sensitization to MBP.

Animals↗

Fluctuations of T- and B-cell subsets in basic protein-induced experimental allergic encephalomyelitis (EAE) in long-tailed macaques.

Experimental allergic encephalomyelitis (EAE) was induced in long-tailed macaques (Macaca fascicularis) by inoculation of autologous myelin basic protein (BP) in complete Freund's adjuvant. Natural killer (NK) cell activity and lymphocyte subsets detected by one- and two-color immunofluorescence were monitored longitudinally in these animals. A decrease in NK cell activity was detected at the onset of clinically defined disease. During the preclinical phase of EAE (5-7 days before the onset of clinical signs) the absolute number of T helper (CD4+) and T suppressor (CD8+) cells in the peripheral blood decreased significantly. Analysis of peripheral blood B cells revealed a selective depletion of IgD+ B cells and a corresponding increase in the number of IgD- B cells prior to and during the onset of clinical signs. Total B-cell numbers were not significantly different between EAE and normal groups. The increased proportion of IgD- B cells in BP-sensitized animals corresponded with the appearance of high titers of circulating anti-BP antibodies. Thus two-color analysis of B-cell subsets may be a sensitive indicator of B-cell activation and of abnormal immune status in EAE. Changes in lymphocyte subsets in macaques with EAE are compared with those in humans with multiple sclerosis.

Animals↗

In vivo depletion of Lyt-2 cells fails to alter acute and relapsing EAE.

The cellular mechanisms of recovery and relapses in experimental allergic encephalomyelitis (EAE) are not known. In order to determine the role of the suppressor/cytotoxic T lymphocytes (Lyt-2+) in EAE we studied the effect of in vivo depletion of this subset using monoclonal antibodies. Intraperitoneal injection of 1 mg of monoclonal antibody 2.43 resulted in rapid depletion of Lyt-2+ cells from lymph node, spleen and blood. Depletion of this subset had no effect on the kinetics of development, severity, and duration of acute EAE. Furthermore, following recovery from acute EAE administration of 2.43 did not result in development of relapses that were different in onset or severity from control animals. These results suggest that T cells of the Lyt-2 phenotype do not play a significant role in the immunoregulation of EAE.

Acute Disease↗

Neurotropin inhibits experimental allergic encephalomyelitis (EAE) in Lewis rats.

The effects of Neurotropin, a substance extracted from the inflammatory dermis of rabbits inoculated with Vaccinia virus, for experimental allergic encephalomyelitis (EAE) in Lewis rats, a model for human multiple sclerosis (MS), was studied. The peptide defined by residues 68-84 (MB 68-84) which corresponds to the encephalitogenic portion of the guinea pig myelin basic protein (MBP) in complete adjuvant H37Ra (CFA) was injected into the hind foot pad of each rat. Neurotropin significantly suppressed the clinical and histological expression of actively induced EAE when administered i.p. daily from day 0 to day 6 after immunization. In addition, passive EAE induced by precultured spleen cells from rats immunized with MB 68-84 in CFA was also suppressed by daily administration of Neurotropin after cell transfer. Neurotropin treatment significantly suppressed the delayed-type hypersensitivity (DTH) response to MB 68-84. Furthermore, the ability of spleen cells from Neurotropin-treated rats to transfer EAE was significantly lower than that of saline-treated rats. It seemed that the suppression may be due to the inhibition of the activation by MB 68-84 of sensitized spleen cells, as demonstrated by proliferative response to MB 68-84. However, no difference was observed in Con A-induced proliferative response of the spleen cells between Neurotropin- and saline-treated rats. These findings indicate that Neurotropin inhibits EAE by suppressing the immune responses to encephalitogenic MBP with little non-specific suppression.

Animals↗

Cloning and nucleotide sequence of the eae gene homologue from enterohemorrhagic Escherichia coli serotype O157:H7.

The eae gene has recently been shown to be necessary for the attaching and effacing (AE) activity of enteropathogenic Escherichia coli (EPEC) on intestinal epithelial cells. In this paper we report the cloning and nucleotide sequence of a similar gene from a strain of enterohemorrhagic E. coli (EHEC) serotype O157:H7. An EHEC eae sequence was identified which was 97% homologous to the EPEC eae gene for the first 2200 bp and 59% homologous over the last 800 bp. Both eae sequences show 50% homology to the central region of the Yersinia pseudotuberculosis inv gene. The receptor-binding domain of the inv gene product lies near the carboxyl terminus. This suggests that the predicted amino acid sequence divergence in the carboxyl termini of the eae gene products might result in different antigenic and receptor specificity of these putative adhesins.

Adhesins, Bacterial↗