MOG-induced Experimental Autoimmune Encephalomyelitis Research Articles

Induced-tolerogenic Dendritic Cells promote tolerance and de novo differentiation of regulatory T cells (65.6)

Abstract Tolerance towards specific antigens is achieved by elimination of reactive T cells and/or their differentiation into regulatory T cells (Tregs). We screened several cell culture conditions known to confer potent tolerogenic capacity on Dendritic Cells (DC) in an attempt to obtain antigen-presenting cells that eliminate naïve CD4+ T cells (Tn) or induce Foxp3 expression, the master regulator of Treg differentiation and function. We identified Rapamycin and TGFβ as key factors that imprint DCs with strong tolerogenic function. TCR stimulation of Tn by these induced-tolerogenic DC (itDC) results in the selective reduction of antigen specific cells and the upregulation of Foxp3 expression in the remaining cells. The resulting adaptive regulatory T cells (aTregs) express high levels of CD25, GITR, CD152, CD62L and suppress T cell responses in vitro. Interestingly, aTreg differentiation induced by itDC was cell contact-dependent and occurred in absence of IL-10, TGFβ, IDO1 and FasL. In vivo injection of itDCs at the first clinical signs of MOG-induced Experimental Autoimmune Encephalomyelitis (EAE, Day 12) completely blocks the progress of the disease. Finally, monocyte-derived human itDC also induced sustained Foxp3 expression in human T cells that display suppressive function. These results suggest that itDCs may be a valuable tool to induce antigen-specific tolerance in vivo and represent a potential novel therapy for autoimmune disorders.

Laquinimod Add on Effect on Glatiramer Acetate as Well as INFb Treatments (P04.142)

Objective: Studying whether laquinimod treatment added on top of either GA (glatiramer acetate) or IFNb would result in an additive effect on disease severity in MOG-induced EAE. Background Laquinimod is an orally administered CNS-active immunomodulator. Phase III data in RRMS patients indicate clear effects of laquinimod 0.6mg on disease progression and on the accumulation of brain-tissue loss, as measured by MRI, coupled with a favorable safety and tolerability profile. Laquinimod has shown a significant effect in Experimental Autoimmune Encephalomyelitis (EAE), an animal model of MS. In the EAE model, laquinimod has been shown to significantly abrogate disease severity. It was suggested that Laquinimod exhibits its effect via NFkB signaling inhibition. It was shown to affect CNS residential cells as astrocytes and microglia resulting in reduction of proinflammatory cytokines. Glatiramer acetate (GA), a well-known disease modifying treatment for relapsing RRMS, is an immunomodulator that significantly inhibits disease activity in EAE. GA was shown to bind to various class II major histocompatibility complex (MHC) molecules and to create GA specific Th2 cells. These cells are migrating into the CNS and secreting anti inflammatory cytokines. INFb-which is also in use for RRMS treatment is effective in reducing inflammatory activity in EAE. Laquinimod has shown efficacy, using IFNb knock out mouse model, suggesting that laquinimod efficacy is IFNb independent. Design/Methods: MOG induced EAE C57BL/6 mice were treated with Laquinimod (5 and 25mg/kg) alone or together with suboptimal dose of GA (12.5mg/kg) or IFNb (500,000 and 50,000 IU/mouse). All treatments were started 1 day after immunization. Scoring of EAE clinical signs were carried out daily. Results: Both GA/laquinimod and IFNb/laquinimod adjunct treatment resulted in improved efficacy when compared to each treatment alone. Conclusions: These results suggesting the use of both treatment regimens together as a potential treatment for RRMS patients. Supported by: Teva Pharmaceutical industries. Disclosure: Dr. Hayardeny Nisimov has nothing to disclose. Dr. Birnberg has nothing to disclose. Dr. Raymond has received research support from TEVA Pharmaceutical. Dr. Fine has received research support from Teva Pharmaceutical. Dr. Kaye has received personal compensation for activities with Teva Neuroscience as an employee. Dr. Kaye has received research support from Teva Neuroscience.

Potently Immunosuppressive 5-Fluorouracil–Resistant Mesenchymal Stromal Cells Completely Remit an Experimental Autoimmune Disease

We treated mice with 5-fluorouracil (5-FU) to isolate a quiescent and undifferentiated mesenchymal stromal cell (MSC) population from the bone marrow. We examined these 5-FU-resistant MSCs (5-FU-MSCs) free from hematopoietic components for CFU fibroblasts (CFU-Fs) and assessed their immunosuppressive potential in vitro and in vivo. We differentiated fibroblastic CFU-Fs (Fibro-CFU-Fs) from mixed CFU-Fs, based on the absence of in situ expression of CD11b and CD45 hematopoietic markers, as well as on their differentiation capacity. Fibro-CFU-Fs were associated with increased numbers of large-sized Fibro-CFU-Fs (≥9 mm(2)) that displayed enhanced capacity for differentiation into adipogenic and osteogenic mesenchymal lineages. Administration of these 5-FU-resistant CD11b(-)CD45(-) MSCs 6 d after myelin oligodendrocyte glycoprotein (MOG) immunization completely remitted MOG-induced experimental autoimmune encephalomyelitis after initial development of mild disease. The remission was accompanied by reduced CNS cellular infiltration and demyelination, as well as a significant reduction in anti-MOG Ab and splenocyte proliferation to MOG. MOG-stimulated splenocytes from these mice showed elevated levels of Th2 cytokines (IL-4, IL-5, and IL-6) and decreased IL-17. Compared with untreated MSCs, 5-FU-MSCs demonstrated potent immunosuppression of Con A-stimulated splenocytes in vitro, even at a 1:320 MSC/splenocyte ratio. Immunosuppression was accompanied by elevated IL-1ra, IL-10, and PGE(2). Blocking IL-1ra, IL-10, and PGE(2), but not IL-6, heme oxygenase-1, and NO, attenuated 5-FU-MSC-induced immunosuppression. Together, our findings suggested that immunosuppression by 5-FU-MSC is mediated by a combination of elevated IL-1ra, IL-10, and PGE(2), anti-inflammatory Th2 cytokines, and decreased IL-17. Our findings suggested that 5-FU treatment identifies a population of potently immunosuppressive 5-FU-MSCs that have the potential to be exploited to remit autoimmune diseases.

Non-myeloablative transplantation of bone marrow expressing self-antigen establishes peripheral tolerance and completely prevents autoimmunity in mice

Myeloablative transplantation of bone marrow (BM) engineered to express myelin oligodendrocyte glycoprotein (MOG) establishes central intrathymic tolerance and completely prevents MOG-induced experimental autoimmune encephalomyelitis (EAE) in mice. Here we asked whether non-myeloablative transplantation of MOG expressing BM (pMOG-bone marrow transplantation (BMT)) can also provide the same protection. Using stepwise reduction of irradiation doses, 275 cGy irradiation with pMOG-BMT protected 100% of mice from EAE development even with two subsequent re-challenge with MOG. Irradiation doses <275 cGy produced dose-dependent partial protection with significant disease protection still evident at 50 cGy. Splenocytes from 275 cGy recipients proliferated to MOG stimulation in vitro, indicating that MOG-reactive cells are present in the periphery but failed to induce disease. MOG-stimulated splenocytes produced little or no interleukin-17, interferon-γ, granulocyte-monocyte colony stimulating factor and tumor necrosis factor-α compared with EAE control. Adoptive transfer of CD4 T cells from EAE-resistant mice into Rag2(-/-) mice devoid of MOG expression resulted in MOG-induced EAE in ~74% of mice. Treatment of EAE-resistant mice with anti-programmed death 1 (PD-1) monoclonal antibody-induced EAE in 67% of mice. We conclude that non-myeloablative transplantation of self-antigen expressing BM induces robust peripheral tolerance that completely prevented EAE development. Our findings implicate clonal anergy and the PD-1 pathway in the maintenance of peripheral tolerance.

N-Acetylglucosamine Inhibits T-helper 1 (Th1)/T-helper 17 (Th17) Cell Responses and Treats Experimental Autoimmune Encephalomyelitis

Current treatments and emerging oral therapies for multiple sclerosis (MS) are limited by effectiveness, cost, and/or toxicity. Genetic and environmental factors that alter the branching of Asn (N)-linked glycans result in T cell hyperactivity, promote spontaneous inflammatory demyelination and neurodegeneration in mice, and converge to regulate the risk of MS. The sugar N-acetylglucosamine (GlcNAc) enhances N-glycan branching and inhibits T cell activity and adoptive transfer experimental autoimmune encephalomyelitis (EAE). Here, we report that oral GlcNAc inhibits T-helper 1 (Th1) and T-helper 17 (Th17) responses and attenuates the clinical severity of myelin oligodendrocyte glycoprotein (MOG)-induced EAE when administered after disease onset. Oral GlcNAc increased expression of branched N-glycans in T cells in vivo as shown by high pH anion exchange chromatography, MALDI-TOF mass spectroscopy and FACS analysis with the plant lectin l-phytohemagglutinin. Initiating oral GlcNAc treatment on the second day of clinical disease inhibited MOG-induced EAE as well as secretion of interferon-γ, tumor necrosis factor-α, interleukin-17, and interleukin-22. In the more severe 2D2 T cell receptor transgenic EAE model, oral GlcNAc initiated after disease onset also inhibits clinical disease, except for those with rapid lethal progression. These data suggest that oral GlcNAc may provide an inexpensive and nontoxic oral therapeutic agent for MS that directly targets an underlying molecular mechanism causal of disease.

Ursolic Acid Suppresses Interleukin-17 (IL-17) Production by Selectively Antagonizing the Function of RORγt Protein

Th17 cells have recently emerged as a major player in inflammatory and autoimmune diseases via the production of pro-inflammatory cytokines IL-17, IL-17F, and IL-22. The differentiation of Th17 cells and the associated cytokine production is directly controlled by RORγt. Here we show that ursolic acid (UA), a small molecule present in herbal medicine, selectively and effectively inhibits the function of RORγt, resulting in greatly decreased IL-17 expression in both developing and differentiated Th17 cells. In addition, treatment with UA ameliorated experimental autoimmune encephalomyelitis. The results thus suggest UA as a valuable drug candidate or leading compound for developing treatments of Th17-mediated inflammatory diseases and cancer.

Myelin-specific B cell receptor transgenic mice reveal critical role for B cell accessory function independent of antibodies in pathogenesis of CNS autoimmune disease (148.2)

Abstract Human myelin oligodendrocyte glycoprotein (MOG) induces experimental autoimmune encephalomyelitis (EAE) in a B cell-dependent manner, and is associated with MOG-specific antibodies (Abs). Whether B cells serve as antigen presenting cells (APC) for activation of encephalitogenic MOG-specific T cells in EAE induced by MOG is unknown. To distinguish the role of APC function by MOG-specific B cells from MOG-specific Abs, we created MOG-specific B cell receptor (BCR) transgenic (Tg) mice containing B cells that express membrane MOG-specific Ig only (MOGmIg), but cannot secrete Abs. EAE was compared in MOGmIg mice, MOG-specific BCR knock-in (Th) mice that can secrete all isotypes, in B cell-deficient and wild-type (WT) mice. B cell-deficient mice were resistant, confirming the requirement for B cells in human MOG-induced EAE. MOG induced EAE in MOG BCR knock-in mice, WT mice and MOGmIg Tg mice, indicating that B cells provide an accessory (i.e. APC) function, independent of Ab secretion in MOG-induced EAE. To further evaluate B cell function, mixed bone marrow (bm) chimera mice were created that contained B cells that were selectively MHC II-deficient. Mixed bm chimera mice that contained MHC II+ B cells were susceptible to MOG-induced EAE, whereas mice containing MHC II- B cells were resistant, despite MHC II expression on other APC. Our results conclusively demonstrate that independent of their humoral role, B cells provide a critical cellular function in EAE pathogenesis.

Critical function of myeloid SOCS3 is in limiting the neuroinflammation of EAE (147.21)

Abstract Macrophages and microglia are central players in the pathogenesis of inflammatory diseases in the CNS, such as Multiple Sclerosis. SOCS proteins are critical feedback inhibitors of the JAK/STAT pathway, and negatively regulate innate and adaptive immune responses. Our Previous Studies indicated that SOCS3 is a negative regulator of macrophage and microglia activation. Experimental autoimmune encephalomyelitis (EAE), an animal model of MS, is used to study the function of SOCS3 in neuroinflammation. Mice with conditional SOCS3 deletion in myeloid lineage cells (LysMCreSOCS3fl/fl) were generated from SOCS3fl/fl mice. Our results indicated that LysMCreSOCS3fl/fl mice are remarkably vulnerable to MOG-induced EAE, with features characteristic of atypical EAE, an earlier onset and more severe of EAE than SOCS3fl/fl mice. The lack of SOCS3 in myeloid lineage cells led to enhanced infiltration of inflammatory cells and enhanced demyelination in the cerebellum, and expression of inflammatory cytokines and chemokines in the cerebellum, and an immune response dominated by Th1 cells. Furthermore, the adoptive transfer experiments demonstrated that macrophage with SOCS3 expression rescues LysMCreSOCS3fl/fl mice from atypical EAE by inhibition of IFN-γ, IL-6, CCL2 and CXCL10 expression. Our study suggests that SOCS3 is a critical negative regulator in EAE pathogenesis, specifically in the development of atypical EAE. SOCS3 may service as an approach to new therapeutics for MS patients.

Insight into the mechanism of laquinimod action

Laquinimod is a small, novel, orally active, well-tolerated molecule that significantly reduced gadolinium-enhancing lesions in patients with multiple sclerosis (MS). Orally administered laquinimod was found to be present within the central nervous system (CNS) in both healthy mice and mice with experimental autoimmune encephalomyelitis (EAE). Laquinimod inhibits development of both acute and chronic EAE. Furthermore, laquinimod minimizes inflammation, demyelination and axonal damage in MOG-induced EAE in mice treated at disease induction and following clinical disease onset. In vitro, laquinimod down-regulates secretion of pro-inflammatory cytokines and enhances production of anti-inflammatory cytokines from peripheral blood mononuclear cells (PBMCs) derived from healthy subjects and untreated relapsing remitting (RR) MS patients. Additionally, patients treated with laquinimod demonstrate up-regulation of brain-derived neurotrophic factor (BDNF) in the serum. In conclusion, treatment with laquinimod is effective in reducing inflammation, demyelination and axonal damage.

Fumaric acid and its esters: An emerging treatment for multiple sclerosis with antioxidative mechanism of action

Fumaric acid was originally therapeutically used in psoriasis. Several lines of evidence have demonstrated immunomodulatory but also neuroprotective effects for FAE. Clinical studies in psoriasis showed a reduction of peripheral CD4+ and CD8+ T-lymphocytes due to the ability of FAE to induce apoptosis. In vitro studies with the ester dimethylfumarate (DMF) described an inhibitory effect on nuclear factor kappa B (NF-κB)-dependent transcription of tumor necrosis factor-alpha (TNF-α) induced genes in human endothelial cells. Animal experiments in the mouse model of central nervous system demyelination, MOG-induced experimental autoimmune encephalomyelitis, revealed a clear preservation of myelin and axonal density in the plaque. Molecular studies showed that this is based on the antioxidative mechanism of action via induction of the transcription factor Nrf-2. A phase II clinical trial in relapsing-remitting multiple sclerosis (RRMS) patients with dimethylfumarate showed a significant reduction in the number of gadolinium enhancing lesions after 24weeks.

Sustained T cell Rap1 activation protects against Experimental Autoimmune Encephalomyelitis (EAE) via modulation of T cell responses

Rap1 is signalling molecule that modulates T lymphocyte trafficking and activation upon antigen stimulation. We demonstrated that transgenic mice with T cells expressing constitutively active Rap1 (RapV12) are protected from experimental arthritis. Here, we aimed to identify the mechanisms of protection by using a TCR transgenic model of MOG-induced EAE (2D2 mice).

Chronic immobilisation stress ameliorates clinical score and neuroinflammation in a MOG-induced EAE in Dark Agouti rats: mechanisms implicated

BackgroundMultiple sclerosis (MS) is the endpoint of a complex and still poorly understood process which results in inflammation, demyelination and axonal and neuronal degeneration. Since the first description of MS, psychological stress has been suggested to be one of the trigger factors in the onset and/or relapse of symptoms. However, data from animal models of MS, such as experimental autoimmune encephalomyelitis (EAE) are inconsistent and the effect of stress on EAE onset and severity depends on duration and time of application of the stress protocol and the underlying mechanisms.MethodsDark Agouti rats were inoculated with MOG/CFA to induce EAE, and an immobilisation stress protocol with two different durations (12 and 21 days, starting at the moment of MOG-inoculation) was applied in order to analyse the effect of stress on disease onset and neuroinflammation.ResultsTwelve days of stress exposure increased EAE clinical score in Dark Agouti rats. In addition, these animals presented higher levels of MMP-9 and proinflammatory PGE2 in spinal cord. In contrast, animals chronically exposed to stress (21 days) showed a significantly lower incidence of EAE clinical signs and reduced myelin loss, leukocyte infiltration and accumulation of inflammatory/oxidative mediators in spinal cord. Interestingly, chronically stressed animals showed a parallel increase in levels of the anti-inflammatory prostaglandin 15d-PGJ2, the main endogenous agonist of PPARγ.ConclusionsOur results demonstrate that, depending on duration, stress exposure elicits opposite effects on PGE2/15d-PGJ2 ratios in spinal cord of EAE-induced Dark Agouti rats. Further studies are needed to elucidate if these changes in prostaglandin balance are sufficient to mediate the differences in clinical score and inflammation here reported, and to establish the potential utility of pharmacological intervention in MS directed toward anti-inflammatory pathways.

The chemokine receptor antagonist, TAK‐779, decreased experimental autoimmune encephalomyelitis by reducing inflammatory cell migration into the central nervous system, without affecting T cell function

The C-C chemokine receptor CCR5, and the C-X-C chemokine receptor CXCR3 are involved in the regulation of T cell-mediated immune responses, and in the migration and activation of these cells. To determine whether blockade of these chemokine receptors modulated inflammatory responses in the central nervous sytem (CNS), we investigated the effect of a non-peptide chemokine receptor antagonist, TAK-779, in mice with experimental autoimmune encephalomyelitis (EAE). EAE was induced by immunization of C57BL/6 mice with myelin oligodendrocyte glycoprotein (MOG) 35-55. TAK-779 was injected s.c. once a day after immunization. Disease incidence and severity (over 3 weeks) were monitored by histopathological evaluation and FACS assay of inflammatory cells infiltrating into the spinal cord, polymerase chain reaction quantification of mRNA expression, assay of T cell proliferation, by [3H]-thymidine incorporation and cytokine production by enzyme-linked immunosorbent assay. Treatment with TAK-779 reduced incidence and severity of EAE. It strongly inhibited migration of CXCR3/CCR5 bearing CD4+, CD8+ and CD11b+ leukocytes to the CNS. TAK-779 did not reduce proliferation of anti-MOG T cells, the production of IFN-gamma by T cells or CXCR3 expression on T cells. In addition, TAK-779 did not affect production of IL-12 by antigen-presenting cells, CCR5 induction on T cells and the potential of MOG-specific T cells to transfer EAE. TAK-779 restricted the development of MOG-induced EAE. This effect involved reduced migration of inflammatory cells into the CNS without affecting responses of anti-MOG T cells or the ability of MOG-specific T cells to transfer EAE.

FTY720 ameliorates MOG‐induced experimental autoimmune encephalomyelitis by suppressing both cellular and humoral immune responses

FTY720, an oral sphingosine 1-phosphate (S1P) receptor modulator, has shown efficacy in phase II trials in patients with relapsing-remitting multiple sclerosis (MS). Although this molecule is thought to immunosuppress by inhibiting lymphocyte egress from the lymph nodes, the full spectrum of FTY720's actions has not yet been uncovered. In this study, we investigated the effects of FTY720 treatment on disease severity and histopathology of MOG-induced experimental autoimmune encephalomyelitis (EAE) in the dark agouti (DA) rat, a model that closely mimics several features of MS. The effects of FTY720 on T-cell subsets, anti-MOG antibody production, and mRNA expression of a number of cytokines and other genes were also examined. Commencement of treatment before disease onset prevented the appearance of clinical disease. Therapeutic treatment after established disease reduced clinical scores and substantially attenuated inflammation, demyelination, and axon loss. EAE suppression was associated with a reduction in all measured T-cell subsets in blood and spleen and a significant decrease in serum IgG(2a) levels. However, in the lymph nodes, all T-cell subsets except for naïve T cells and recent thymic emigrants remained unaffected. In addition, FTY720 treatment led to a significant inhibition in interferon-gamma, inducible nitric oxide synthase, and glial cell line-derived neurotrophic factor mRNA expression in the MOG-EAE spinal cord. In conclusion, our findings indicate that FTY720-mediated S1P receptor modulation ameliorates chronic relapsing MOG-EAE by suppressing both cellular and humoral immune responses.

Role of pathogenic T cells and autoantibodies in relapse and progression of myelin oligodendrocyte glycoprotein‐induced autoimmune encephalomyelitis in LEW.1AV1 rats

Accumulating evidence suggests that T cells and autoantibodies reactive with myelin oligodendrocyte glycoprotein (MOG) play a critical role in the pathogenesis of multiple sclerosis (MS). In the present study, we have tried to elucidate the pathomechanisms of development and progression of the disease by analysing T cells and autoantibodies in MOG-induced rat experimental autoimmune encephalomyelitis (EAE), which exhibits various clinical subtypes mimicking MS. Analysis using overlapping peptides revealed that encephalitogenic epitopes resided in peptide 7 (P7, residue 91-108) and P8 (residue 103-125) of MOG. Immunization with MOGP7 and MOGP8 induced relapsing-remitting or secondary progressive EAE. T cells taken from MOG-immunized and MOGP7-immunized rats responded to MOG and MOGP7 and sera from MOG-immunized rats reacted to MOG and MOGP1. Significant epitope spreading was not observed at either T-cell or antibody levels. Interestingly, sera from MOGP7-immunized rats with clinical signs did not react to MOG and MOG peptides throughout the observation period, suggesting that disease development and relapse in MOGP7-induced EAE occur without autoantibodies. However, MOGP7 immunization with adoptive transfer of anti-MOG antibodies aggravated the clinical course of EAE only slightly. Analysis of antibodies against conformational epitope (cme) suggests that anti-MOG(cme) may play a role in the pathogenicity of anti-MOG antibodies. Collectively, these findings demonstrated that relapse of a certain type of MOG-induced EAE occurs without autoantibodies but that autoantibodies may play a role in disease progression. Relapses and the progression of MS-mimicking EAE are differently immunoregulated so immunotherapy should be designed appropriately on the basis of precise information.

P57kip2 is dynamically regulated in experimental autoimmune encephalomyelitis and interferes with oligodendroglial maturation

The mechanisms preventing efficient remyelination in the adult mammalian central nervous system after demyelinating inflammatory diseases, such as multiple sclerosis, are largely unknown. Partial remyelination occurs in early disease stages, but repair capacity diminishes over time and with disease progression. We describe a potent candidate for the negative regulation of oligodendroglial differentiation that may underlie failure to remyelinate. The p57kip2 gene is dynamically regulated in the spinal cord during MOG-induced experimental autoimmune encephalomyelitis. Transient down-regulation indicated that it is a negative regulator of post-mitotic oligodendroglial differentiation. We then applied short hairpin RNA-mediated gene suppression to cultured oligodendroglial precursor cells and demonstrated that down-regulation of p57kip2 accelerates morphological maturation and promotes myelin expression. We also provide evidence that p57kip2 interacts with LIMK-1, implying that p57kip2 affects cytoskeletal dynamics during oligodendroglial maturation. These data suggest that sustained down-regulation of p57kip2 is important for oligodendroglial maturation and open perspectives for future therapeutic approaches to overcome the endogenous remyelination blockade in multiple sclerosis.

Characterization of Multiple Sclerosis candidate gene expression kinetics in rat experimental autoimmune encephalomyelitis

The immunological mechanisms underlying autoimmunity are being elucidated through genetic and functional analyses in both humans and rodent models. However, acceptance of models as valid equivalents of human disease is variable, and the validation of defined human candidate molecules in experimental models is hitherto limited. We thus aimed to determine the kinetic expression of several Multiple Sclerosis (MS) candidate genes in the myelin oligodendrocyte glycoprotein (MOG)-induced rat experimental autoimmune encephalomyelitis (EAE) model using susceptible DA and resistant PVG inbred strains. Increased expression of MS candidate genes IL2RA and IL7RA associated with disease susceptibility. Higher expression of these candidate genes and IL18R1 in susceptible rats may lead to enhancement of the disease-driving T H1 and T H17 pathways. Susceptible DA rats had augmented marker molecules of these pathways and upon restimulation with autoantigen produced increased effector molecules including IFN-γ, IL-17F and IL-22. The altered T helper cell differentiation pathways led to differences in a MOG-specific proliferative and autoantibody response, which ultimately results in infiltration in the central nervous system and EAE induction. Our results validate the MOG-induced EAE model as having similar mechanisms to human MS and determined the kinetics of several disease mechanisms in relevant tissues.

Fumaric Acid and its Esters: An Emerging Treatment for Multiple Sclerosis

Fumaric acid is an intermediate product of the citric acid cycle that is a source of intracellular energy in the form of adenosine triphosphate (ATP). It is generated by oxidation of adenylsuccinate by the enzyme succinate dehydrogenase and is then converted to maleate by the enzyme fumarase. At present, fumaric acid esters (FAE) are licensed for the treatment of psoriasis. Several lines of evidence have demonstrated immunomodulatory effects for FAE. Clinical studies in psoriasis showed a reduction of peripheral CD4+- and CD8+-T-lymphocytes due to the ability of FAE to induce apoptosis. In vitro studies with the ester dimethyl fumarate (DMF) described an inhibitory effect on nuclear factor kappa B (NF-κB)-dependent transcription of tumor necrosis factor-alpha (TNF-α) induced genes in human endothelial cells. Animal studies using a model of central nervous system demyelination, MOG-induced experimental autoimmune encephalomyelitis (EAE), revealed a reduction of microglia and macrophages in inflamed lesions. A phase II clinical study in relapsing-remitting multiple sclerosis (RRMS) patients with a modified fumaric acid ester, BG-12, showed as "proof of principle" a significant reduction in the number of gadolinium enhancing lesions after 24 weeks of treatment as compared to placebo. Further phase III studies have now started to explore the long-term efficacy of FAE.

Gene expression analysis of normal appearing brain tissue in an animal model for multiple sclerosis revealed grey matter alterations, but only minor white matter changes

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Recent studies suggest that, beside focal lesions, diffuse inflammatory and degenerative processes take place throughout the MS brain. Especially, molecular alterations in the so-called normal appearing white matter suggest the induction of neuroprotective mechanisms against oxidative stress preserving cellular homeostasis and function. In this study we investigated whether in an animal model for MS, namely in experimental autoimmune encephalomyelitis (EAE), similar changes occur. We isolated normal appearing white and grey matter from the corpus callosum and the above lying cerebral cortex from DA rats with rMOG-induced EAE and carried out a gene expression analysis. Examination of corpus callosum revealed only minor changes in EAE rats. In contrast, we identified a number of gene expression alterations in the cerebral cortex even though morphological and cellular alterations were not evident. One of the most striking observations was the downregulation of genes involved in mitochondrial function as well as a whole set of genes coding for different glutamate receptors. Our data imply that molecular alterations are present in neurons far distant to inflammatory demyelinating lesions. These alterations might reflect degenerative processes induced by lesion-mediated axonal injury in the spinal cord. Our results indicate that the MOG-induced EAE in DA rats is a valuable model to analyze neuronal alterations due to axonal impairment in an acute phase of a MS-like disease, and could be used for development of neuroprotective strategies.

Altered neuronal expression of TASK1 and TASK3 potassium channels in rodent and human autoimmune CNS inflammation

Multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) are characterized by T cell-mediated autoimmune inflammation of the central nervous system (CNS) leading to oligodendrocyte loss and demyelination accompanied by neuronal cell death. Neuronal TWIK-related acid-sensitive potassium (TASK) channels allow the regulated efflux of potassium ions. These channels might either protect neurons in the inflamed CNS by modulating electrical excitability or even contribute to inflammatory neurodegeneration mediating intracellular potassium depletion. Using a combination of in-situ-hybridisation and immunofluorescence staining, we found increased neuronal expression of TASK1 and TASK3 channels in the optic nerve and decreased expression in the spinal cord and thalamus of rats undergoing MOG-induced EAE. Inflammatory plaques of human MS patients displayed profoundly lowered expression of both TASK isoforms. Thus, regulated expression of TASK channels might contribute to a molecular switch between death and survival of neurons in autoimmune CNS inflammation.