Allergic Encephalomyelitis In Lewis Rats Research Articles

Angiopoietin-1 and C16 Peptide Attenuate Vascular and Inflammatory Responses in Experimental Allergic Encephalomyelitis.

Breakdown of normal blood-brain barrier function and accompanying vascular leakage are fundamental stages in the onset of multiple sclerosis and its animal counterpart, experimental allergic encephalomyelitis. In the present study, angiopoietin-1, an endothelial growth factor well known for its role in establishing and maintaining vascular integrity, and C16, a peptide that competitively binds to integrin αvβ3 expressed on endothelial cells, were used to treat acute experimental allergic encephalomyelitis in Lewis rats. Angiopoietin-1 was more effective than C16 for reducing inflammation-induced vascular leakage. Moreover, treatment with a combination of angiopoietin-1 and C16 resulted in greater effects, not only in alleviating inflammation and reducing axonal loss/demyelination but also in down-regulating pro-inflammatory cytokine expression and improving electrophysiological dysfunction, than treatment with either angiopoietin-1 or C16 alone. Different protective effects were observed with angiopoietin-1 and C16 treatment suggesting that these proteins target specific receptors to act through different pathways. Furthermore, angiopoietin-1 and C16 may form the basis of a promising therapeutic strategy for experimental allergic encephalomyelitis and multiple sclerosis.

Applications of Weak, Complex Magnetic Fields that Attenuate EAE in Rats to a Human Subject with Moderately Severe Multiple Sclerosis

Background: A middle-aged woman who displayed moderately severe chronic multiple sclerosis for more than a decade and whose symptoms did not respond to conventional treatments volunteered to whole-body exposures of computer generated, 7 Hz weak magnetic fields during her sleep cycle for about four months. Method: The magnetic fields were generated by custom-constructed software that generated current through two large coils that were placed at the head and foot of the bed and extended the width of the bed. To simulate the procedure that had markedly ameliorated experimental allergic encephalomyelitis in Lewis rats, the 7 Hz fields were presented for 6 min once per hour, between midnight and 08 hr. The generated maximum (peak-to-peak) intensities were either 40 nT, 10 nT or 0 nT during different 30 to 40 day blocks. Results: Only the somatic symptoms but not the ambulatory complications were significantly reduced during the nocturnal presentations of 40 nT exposures compared to the other conditions. Conclusions: These results suggest that this particular configuration of magnetic fields, which were shown to reduce the clinical severity of experimental allergic encephalomyelitis in rats, may help reduce the somatic components of patients with chronic multiple sclerosis.

Effects of amphetamine and cocaine on the development of acute experimental allergic encephalomyelitis in Lewis rats

The present experiment deals with the effects of amphetamine and cocaine on the development and course of experimental allergic encephalomyelitis (EAE) induced in Lewis rats. Rats were immunized at the age of eight weeks with purified myelin basic protein isolated from guinea pig brain in complete Freund's adjuvant. Drug administration and recording of EAE clinical signs was performed daily since day 1 post-immunization (PI). On day 14 and 28 PI, six rats per group were bled and sacrificed. Spinal cord was examined histologically for EAE lesions. In vivo administration of 0.5 and 1 mg/Kg of amphetamine or cocaine resulted in a dose-related enhancement of neurological and histological signs of acute EAE in comparison with control rats. Both drugs caused a reduction of latent period together with a delayed regression of neurological signs along with an increase in inflammation in the central nervous system in comparison with placebo. Human & Experimental Toxicology (2007) 26, 637-643.

A Tumor Necrosis Factor Receptor 1-Dependent Conversation between Central Nervous System-Specific T Cells and the Central Nervous System Is Required for Inflammatory Infiltration of the Spinal Cord

We examined the role of tumor necrosis factor receptor 1 (TNFR1) in inflammation initiated by the adoptive transfer of central nervous system (CNS)-specific Th1 cells in experimental autoimmune encephalomyelitis, a murine model of multiple sclerosis. This adoptive transfer paradigm eliminates the confounding effects of bacterial adjuvants in the analysis of inflammation. We found that although T cells could reach the meninges and perivascular space in the absence of TNFR1, recruitment of other inflammatory cells from the blood was dramatically reduced. The reduction in the recruitment of CD11b(hi) cells correlated with a dramatic reduction in the production of the chemokines CCL2 (MCP-1) and CXLC2 (MIP-2) in TNFR1-deficient hosts. Bone marrow chimera experiments demonstrated that TNF can be effectively supplied by either the hematopoietic system or the CNS, but the essential TNFR1-responsive cells reside in the CNS. Previous work has demonstrated that microglia produce CCL2, and here we demonstrate that astrocytes and endothelial cells produced CXCL2 in the early stages of inflammation. Therefore, productive inflammation results from a conversation, or mutually responding signals, between the initiating T cells and cells in the parenchyma of the spinal cord.

Photopheresis affects the course of experimental allergic encephalomyelitis in Lewis rat.

The mechanism responsible for the beneficial effects of extracorporeal photochemotherapy (ECP) remains unknown. In the rat model of experimental allergic encephalomyelitis (EAE), the transfer of encephalitogenic cells (EAE cells) induces transient passive EAE, followed by resistance to subsequent disease induction through immunization with central nervous system antigens (active EAE). We tested whether ECP exerts its therapeutic effect by inducing an immune response targeted on circulating pathogenic T-lymphocytes, which results from their increased immunogenicity. We compared the potential of untreated versus ECP-treated encephalitogenic cells to transfer passive EAE and protect against active induction of the disease. The UVA irradiation conditions were derived from intensive ECP protocols used in human clinical studies. Animals receiving untreated cells showed clinical symptoms following cell transfer but not after subsequent immunisation, whereas those receiving ECP-treated cells remained healthy following cell transfer but experienced clinical symptoms after subsequent immunisation. However, these symptoms were less marked than in control naive rats. Under these ECP protocol conditions, ECP-treated cells have no greater active stimulatory potential for the recipient immune system than untreated cells, since they are less effective at triggering the response that causes the resistant state to active EAE. We suggest that intensive ECP protocol may have deleterious effects with a risk of relapses after treatment discontinuation. The search for the irradiation threshold that would inhibit the T-cell pathogenic properties, but retain their ability to educate the immune system, remains a major research challenge.

Beneficial effect of modified peptide inhibitor of alpha4 integrins on experimental allergic encephalomyelitis in Lewis rats.

An important event in the pathogenesis of the autoimmune disease multiple sclerosis (MS) is the recruitment of lymphocytes and inflammatory macrophages to the central nervous system (CNS). Recruitment requires adhesive interactions between the leukocytes and the microvascular endothelium, perivascular cells, and astrocytes in the CNS parenchyma. Previous studies using an animal model of MS, experimental allergic encephalomyelitis (EAE), have shown the involvement of the alpha4 integrin VLA-4 (beta4beta1). In the present study, the effect of a modified peptide inhibitor of alpha4 integrins on the clinical course and leukocyte infiltration during EAE is investigated. EAE was either induced actively, by immunizing Lewis rats with whole guinea pig MBP, or passively, by transfer of an MBP-specific T cell line. Treatment with the inhibitor (CS1 ligand mimic) completely prevented both clinical signs and cellular infiltration in passively induced EAE. Peptide treatment of actively induced EAE, which has a more severe disease course than the transfer model, significantly reduced clinical signs although the recruitment of inflammatory cells and induction of MHC class II expression was not prevented. The alpha4 inhibitor did inhibit the adhesion of lymphocytes to primary astrocytes in vitro suggesting a role for astrocyte-leukocyte interactions in the pathogenesis of induced EAE. Astrocytes were found to express an extracellular matrix protein distinct from fibronectin, which shows immune cross-reactivity with the CS1 domain of fibronectin. Our results show that small-molecule inhibitors of alpha4 integrins act therapeutically in EAE possibly by interfering with cell adhesion events involved in this autoimmune disease.

Modulation of Experimental Allergic Encephalomyelitis in Lewis Rats by Administration of a Peptide of Fas Ligand

The effects of modulation of apoptosis in experimental allergic encephalomyelitis (EAE) in Lewis rats have been investigated using a peptide of the Fas-Ligand protein (FasL-p). The peptide was administered both subcutaneously and intra-cerebro-ventricularly (i.c.v.) after EAE induction. Rats treated subcutaneously with FasL-p showed a worse clinical score as compared to saline treated animals, while i.c.v. treatment with FasL-p did not modify significantly the severity of EAE. Apoptotic lymphomonocytes (identified by TUNEL) infiltrating the brain and the spinal cord were decreased in rats treated i.c.v. with FasL-p. The data suggest that the Fas/Fas-ligand pathway may be modulated by treatments with peptides of Fas-Ligand and that it may be at work within the central nervous system in EAE.

SIN-1, a nitric oxide donor, ameliorates experimental allergic encephalomyelitis in Lewis rats in the incipient phase: the importance of the time window.

NO is involved in the regulation of immune responses. The role of NO in the pathogenesis of experimental allergic encephalomyelitis (EAE) is controversial. In this study, 3-morpholinosydnonimine (SIN-1), an NO donor, was administered to Lewis rats on days 5-7 postimmunization, i.e., during the incipient phase of EAE. SIN-1 reduced clinical signs of EAE compared with those in PBS-treated control rats and was accompanied by reduced ED1(+) macrophages and CD4(+) T cell infiltration within the CNS. Blood mononuclear cells (MNC) obtained on day 14 postimmunization revealed that SIN-1 administration enhanced NO and IFN-gamma production by blood MNC and suppressed Ag- and mitogen-induced proliferative responses. MHC class II, B7-1 and B7-2 were down-regulated in SIN-1-treated EAE rats. Simultaneously, frequencies of apoptotic cells among blood MNC were increased. In vivo, SIN-1 is likely to behave as an NO donor. Administration of SIN-1 induced NO production, but did not affect superoxide and peroxynitrite formation. Enhanced NO production during the priming phase of EAE thus promotes apoptosis, down-regulates disease-promoting immune reactivities, and ameliorates clinical EAE, mainly through SIN-1-derived NO, without depending on NO synthase.

Combined nasal administration of encephalitogenic myelin basic protein peptide 68-86 and IL-10 suppressed incipient experimental allergic encephalomyelitis in Lewis rats.

Mucosal administration of low doses of myelin basic protein (MBP) peptide 68-86 (MBP 68-86) or anti-inflammatory cytokine IL-10 effectively prevented experimental allergic encephalomyelitis (EAE), but failed to suppress the disease if given after 7 days postimmunization (p.i.), i.e., after T cell priming had occurred. We anticipated that combined administration of autoantigen and IL-10 can treat incipient EAE. Lewis rats with EAE actively induced with MBP 68-86 and complete Freund's adjuvant received 120 microg MBP 68-86 + 200 ng IL-10 per rat per day from day 7 p.i. and for 5 consecutive days. These rats showed later onset, lower clinical scores, less body weight loss, and shorter duration of EAE than rats receiving MBP 68-86 or IL-10 only or PBS. EAE amelioration was associated with decreased infiltration of ED1(+) macrophages and CD4(+) T cells within the central nervous system and with decreased proliferative responses of lymph node cells, indicating that combined administration of MBP 68-86 and IL-10 induced immune hyporesponsiveness. IFN-gamma secretion as well as IFN-gamma, TNF-alpha, IL-4, and IL-10 mRNA expression by lymph node MNC was down-regulated in the treated rats. Immune hyporesponsiveness, rather than immune deviation or regulatory mechanisms, seems to be responsible for the protection of EAE after autoantigen + IL-10 administration by the nasal route.

Amelioration of experimental allergic encephalomyelitis in Lewis rats by lovastatin

Proinflammatory cytokines and inducible nitric oxide synthase (iNOS) are involved in the pathogenesis of experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). We have previously reported that lovastatin (Pahan, K., Sheikh., F.G., Namboodiri, A. and Singh, I., Lovastatin and Phenylacetate inhibit the induction of nitric oxide synthase and cytokines in rat primary astrocytes, microglia and macrophages. J. Clin. Invest., 100 (1997) 2671–2679.), an inhibitor of the mevalonate pathway, inhibits the expression of iNOS and proinflammatory cytokines in rat primary glial cells (astroglia and microglia) and macrophages. The present study underlines the therapeutic importance of lovastatin in ameliorating the neuroinflammatory disease process in the central nervous system of EAE rats. Immunohistochemical results show a higher degree of expression of iNOS, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ ) in brains of rats with acute monophasic EAE relative to the control animals. Administration of lovastatin inhibited the expression of iNOS, TNF-α and IFN-γ in the CNS of EAE rats and improved the clinical signs of EAE suggesting that this compound may have therapeutic potential in the treatment of neuroinflammatory diseases like MS.

Chronic remitting experimental allergic encephalomyelitis in Lewis rats as a model of multiple sclerosis.

Chronic remitting experimental allergic encephalomyelitis in Lewis rats as a model of multiple sclerosis.

Magnetic resonance imaging of PLP-induced experimental allergic encephalomyelitis in Lewis rats

An in vivo magnetic resonance (MR) imaging study was performed on experimental allergic encephalomyelitis (EAE) induced in Lewis rats through proteolipid protein (PLP). PLP was solubilized in water or in an aqueous solution of 1% 10-tridecyl ether (TDE), a non-ionic detergent used in membrane protein research. All 16 rats immunized with 500 μg of TDE-solubilized PLP developed clinical signs and MR abnormalities fully comparable to those observed in MBP-induced EAE. Total paraplegia was observed in 12.5% of rats, mild or moderate paraparesis in 68.8% of rats and tail paralysis in the remaining 18.7% of rats. Whereas only 37.5% of the eight rats immunized with 500 μg of water-solubilized PLP developed minor clinical signs (tail weakness or paralysis). Our observations confirm that the difficulties encountered when trying to induce EAE by means of PLP arise from the highly hydrophobic nature of this protein. Accordingly, if a reproducible model is to be developed, it seems more judicious to use non-ionic detergents in both the extraction and solubilization phases of PLP preparation, this would allow maximal solubilization of the protein while avoiding aggregates, which may otherwise form during either of the PLP preparation.

Changes of NGF presence in nonneuronal cells in response to experimental allergic encephalomyelitis in Lewis rats.

We recently reported that the cerebrospinal fluid (CSF) of patients affected by multiple sclerosis (MS) and the brain tissues of rats with experimental allergic encephalomyelitis (EAE) contain elevated levels of nerve growth factor (NGF). In the present study, we demonstrate that astrocytes and oligodendrocytes particularly localized in the white matter, including corpus callosum, overexpress NGFmRNA and produce NGF protein in the CNS of EAE affected rats. These findings indicate that the increased NGF found in the brain of EAE rats and most probably also in the CSF of patients affected by MS is produced by activated glial cells. It is hypothesized that the enhanced production of NGF by glial cells is necessary to compensate for the effect of axonal and/or neuronal cell body injury occurring in EAE. The possible functional significance of these findings in demyelinating diseases is discussed.

Anti-CD3 therapy suppresses induction and reverses experimental allergic encephalomyelitis in Lewis rats

Anti-CD3 therapy suppresses induction and reverses experimental allergic encephalomyelitis in Lewis rats

Magnetic resonance imaging of PLP-induced experimental allergic encephalomyelitis in Lewis rat

Magnetic resonance imaging of PLP-induced experimental allergic encephalomyelitis in Lewis rat

Time-course changes of nerve growth factor, corticotropin-releasing hormone, and nitric oxide synthase isoforms and their possible role in the development of inflammatory response in experimental allergic encephalomyelitis.

In this paper we report a time-course study of development of experimental allergic encephalomyelitis in Lewis rats, by monitoring neuroendocrine regulation of the hypothalamus-pituitary-adrenal axis through corticotropin-releasing hormone mRNA expression, inflammatory cellular infiltrate, macrophagic and neuronal nitric oxide synthase, nerve growth factor (NGF), and NGF p75 and trkA receptors in the brain and spinal cord. We analyzed animals during 20 days after immunization, a time interval that corresponds to the acute immunological phase. We have described a severe, early fall of corticotropin-releasing hormone mRNA expression, which could account for the decreased response of the hypothalamus-pituitary-adrenal axis to inflammatory stress. During this period, an increase of neuronal nitric oxide synthase was observed in the cerebral cortex and spinal cord, and macrophagic nitric oxide synthase positive cells were found in the inflammatory cellular infiltrate, which was abundant in perivascular and submeningeal areas 20 days after immunization. Concomitantly, we found a dramatic up-regulation of NGF receptors on the wall of blood vessels and adjacent neurons in perivascular areas. NGF content also had increased in some brain areas, such as the thalamus, while it had decreased in others, like the spinal cord and medulla oblongata, at time points in which the most serious cellular infiltrate was found.

Suppression of acute experimental allergic encephalomyelitis in Lewis rats with a mycophenolic acid derivative.

Oral administration of ethyl O-[N-(p-carboxyphenyl-carbamoyl]-mycophenolate (CAM), a derivative of mycophenolic acid (MPA) and an inosine monophosphate dehydrogenase inhibitor, dose-dependently suppressed acute experimental allergic encephalomyelitis in Lewis rats without exerting any serious adverse effects. A daily dose of 50 mg/kg of CAM almost completely abolished both the clinical disease and the inflammation in the CNS. In the CAM-treated rats, a weight loss and fluctuations of peripheral lymphocyte subsets were minimized. The CAM treatment was effective when started at the time of sensitization but ineffective when deferred till day 10. Furthermore, CAM reduced the percentage of CD4+CD45RC- cells in the peripheral blood. The only detectable adverse effect was moderate anemia but it was rapidly improved after withdrawal of the drug. This drug could be a useful adjunct for the long-term immunosuppressive therapy for inflammatory diseases of the CNS.

Myelin-induced experimental allergic encephalomyelitis in Lewis rats: tumor necrosis factor α levels in serum and cerebrospinal fluid Immunohistochemical expression in glial cells and macrophages of optic nerve and spinal cord

Tumor necrosis factor a (TNFa) activity was measured in serum and cerebrospinal fluid (CSF) of Lewis rats after experimental allergic encephalomyelitis (EAE) induction and during the clinical course of acute disease. TNFa bioactivity expression preceded the clinical symptoms and paralleled the severity of disease. We further investigated the identity of the central nervous system (CNS) cells involved in TNFa expression and their regional localization during EAE. Tissue sections of brain, cerebellum, dorsal spinal cord and optic nerve were studied by indirect double labelling immunofluorescence. Spinal cord white matter and optic nerve showed a widespread TNFa immunoreactivity at critical stages of EAE in macrophages/microglia and astrocytes. We have shown changes in CSF/serum albumin ratio and immunoglobulin G index during EAE. Our results confirm the very important role of TNFa in EAE.

Reactive oxygen species are involved in the pathogenesis of experimental allergic encephalomyelitis in Lewis rats

During experimental allergic encephalomyelitis (EAE), both blood-borne macrophages as well as activated, resident microglial cells are considered to be involved in inflammatory reactions in the central nervous system (CNS), resulting in the neurological deficits common to EAE. Both cell types can produce multiple mediators of tissue damage, among which are the reactive oxygen species (ROS). In this study we show that macrophages and microglial cells, isolated from the CNS of Lewis rats with clinical signs of EAE, exhibited significantly elevated spontaneous and phorbol myristate acetate (PMA)-inducible levels of ROS compired to similar cells isolated from healthy controls, sham (complete Freund's adjuvant, CFA)-immunized rats as well as rats sacrificed before the manifestation of clinical signs of EAE. However, during clinical EAE, peripheral blood mononuclear cells (PBMC) did not show increased spontaneous nor PMA-inducible ROS production compared to controls. In vivo treatment of EAE with catalase, which scavenges the ROS H 2O 2, markedly suppressed the severity of the disease as compared to sham (albumin)-treated controls. In contrast, Superoxide dismutase had no effect on clinical signs. Our studies point at a putative functional role for ROS, and in particular H 2O 2, in the pathogenesis of EAE.

Suppression of Experimental Allergic Encephalomyelitis in Lewis Rats by Administration of Gangliosides

Gangliosides (GA) are known to suppress T cell responses to mitogens and alloantigens. GA treatment (more than 50 mg/kg/rat subcutaneously every 12 hr) significantly suppressed clinical signs and histologic lesions of both actively induced and cell-transferred experimental allergic encephalomyelitis (EAE) in Lewis rats in a dose-dependent manner: P < 0.01, in actively induced EAE; P < 0.001 (100 mg/kg) or P < 0.005 (50 mg/kg), in cell-transferred EAE. Lymph node cells from guinea pig myelin basic protein (GPMBP)-sensitized rats were stimulated in vitro with the specific sensitizing antigen, GPMBP, or with Con A. Purified bovine brain GA significantly suppressed GPMBP-induced proliferation in a dose-dependent manner ( P < 0.01). GA treatment during sensitization phase (from Day—5 to Day 4) did not suppress actively induced EAE. There were no significant differences in T cell subsets of peripheral blood or spleen cells between GA-treated rats and controls by flow cytometry analysis. Taken together, these findings indicate that GA primarily act on the immune effector phase of EAE.