Macrophage-Derived Extracellular Succinate Licenses Neural Stem Cells to Suppress Chronic Neuroinflammation

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Cytokine Control of Inflammation and Repair in the Pathology of Multiple Sclerosis

Cytokines are secreted signaling proteins that play an essential role in propagating and regulating immune responses during experimental autoimmune encephalomyelitis (EAE), the mouse model of the neurodegenerative, autoimmune disease multiple sclerosis (MS). EAE pathology is driven by a myelin-specific T cell response that is activated in the periphery and mediates the destruction of myelin upon T cell infiltration into the central nervous system (CNS). Cytokines provide cell signals both in the immune and CNS compartment, but interestingly, some have detrimental effects in the immune compartment while having beneficial effects in the CNS compartment. The complex nature of these signals will be reviewed.     

Intermittent Fasting Confers Protection in CNS Autoimmunity by Altering the Gut Microbiota

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An Overview of Models,Methods, and Reagents Developed for Translational Autoimmunity Research in the Common Marmoset (Callithrix jacchus)

The common marmoset (Callithrix jacchus) is a small-bodied Neotropical primate and a useful preclinical animal model for translational research into autoimmune-mediated inflammatory diseases (AIMID), such as rheumatoid arthritis (RA) and multiple sclerosis (MS). The animal model for MS established in marmosets has proven their value for exploratory research into (etio) pathogenic mechanisms and for the evaluation of new therapies that cannot be tested in lower species because of their specificity for humans. Effective usage of the marmoset in preclinical immunological research has been hampered by the limited availability of blood for immunological studies and of reagents for profiling of cellular and humoral immune reactions. In this paper, we give a concise overview of the procedures and reagents that were developed over the years in our laboratory in marmoset models of the above-mentioned diseases.     

G protein-coupled receptors as therapeutic targets for multiple sclerosis

G protein-coupled receptors (GPCRs) mediate most of our physiological responses to hormones, neurotransmitters and environmental stimulants. They are considered as the most successful therapeutic targets for a broad spectrum of diseases. Multiple sclerosis (MS) is an inflammatory disease that is characterized by immune-mediated demyelination and degeneration of the central nervous system (CNS). It is the leading cause of non-traumatic disability in young adults. Great progress has been made over the past few decades in understanding the pathogenesis of MS. Numerous data from animal and clinical studies indicate that many GPCRs are critically involved in various aspects of MS pathogenesis, including antigen presentation, cytokine production, T-cell differentiation, T-cell proliferation, T-cell invasion, etc. In this review, we summarize the recent findings regarding the expression or functional changes of GPCRs in MS patients or animal models, and the influences of GPCRs on disease severity upon genetic or pharmacological manipulations. Hopefully some of these findings will lead to the development of novel therapies for MS in the near future.     

Exacerbation of experimental autoimmune encephalomyelitis in mice deficient for DCIR,an inhibitory C-type lectin receptor

Dendritic cell immunoreceptor (DCIR) is a C-type lectin receptor containing a carbohydrate recognition domain in its extracellular portion and an immunoreceptor tyrosine–based inhibitory motif, which transduces negative signals into cells, in its cytoplasmic portion. Previously, we showed that Dcir^–/– mice spontaneously develop autoimmune diseases such as enthesitis and sialadenitis due to excess expansion of dendritic cells (DCs), suggesting that DCIR is critically important for the homeostasis of the immune system. In this report, we analyzed the role of DCIR in the development of experimental autoimmune encephalomyelitis (EAE), an autoimmune disease model for multiple sclerosis. We found that EAE was exacerbated in Dcir^–/– mice associated with severe demyelination of the spinal cords. The number of infiltrated CD11c⁺ DCs and CD4⁺ T cells into spinal cords was increased in Dcir^–/– mice. Recall proliferative response of lymph node cells was higher in Dcir^–/– mice compared with wild-type mice. These observations suggest that DCIR is an important negative regulator of the immune system, and Dcir^–/– mice should be useful for analyzing the roles of DCIR in an array of autoimmune diseases.     

CD8+T细胞在多发性硬化中的致病性作用

多发性硬化是T细胞介导的自身免疫性疾病。先前对它的研究大多集中在CD4 T细胞的致病和调节性作用上,但是,近几年来越来越多的证据表明CD8 T细胞也参与多发性硬化的病理损伤过程。 CD8 T细胞存在于MS病灶部位,髓鞘抗原特异性CD8 T细胞也从MS患者的血液和脑脊液中分离得到,CD8 T细胞通过直接杀伤或释放细胞因子和趋化因子等间接参与MS的病理过程。本文就近几年关于CD8 T细胞在多发性硬化中的致病性作用的研究进展予以介绍。     

Multiple sclerosis: a battle between destruction and repair

Multiple sclerosis (MS) is a chronic neurodegenerative disease of the CNS in which an unrelenting attack from the innate and adaptive arms of the immune system results in extensive demyelination, loss of oligodendrocytes and axonal degeneration. This review summarizes advances in the understanding of the cellular and molecular pathways involved in neurodegeneration following autoimmune-mediated inflammation in the CNS. The mechanisms underlying myelin and axonal destruction and the equally important interaction between degenerative and repair mechanisms are discussed. Recent studies have revealed that the failure of CNS regeneration may be in part a result of the presence of myelin-associated growth inhibitory molecules in MS lesions. Successful therapeutic intervention in MS is likely to require suppression of the inflammatory response, in concert with blockade of growth inhibitory molecules and possibly the mobilization or transplantation of stem cells for regeneration.     

Regulation of oligodendrocyte progenitor cell maturation by PPARδ: effects on bone morphogenetic proteins

In EAE (experimental autoimmune encephalomyelitis), agonists of PPARs (peroxisome proliferator-activated receptors) provide clinical benefit and reduce damage. In contrast with PPARγ, agonists of PPARδ are more effective when given at later stages of EAE and increase myelin gene expression, suggesting effects on OL (oligodendrocyte) maturation. In the present study we examined effects of the PPARδ agonist GW0742 on OPCs (OL progenitor cells), and tested whether the effects involve modulation of BMPs (bone morphogenetic proteins). We show that effects of GW0742 are mediated through PPARδ since no amelioration of EAE clinical scores was observed in PPARδ-null mice. In OPCs derived from E13 mice (where E is embryonic day), GW0742, but not the PPARγ agonist pioglitazone, increased the number of myelin-producing OLs. This was due to activation of PPARδ since process formation was reduced in PPARδ-null compared with wild-type OPCs. In both OPCs and enriched astrocyte cultures, GW0742 increased noggin protein expression; however, noggin mRNA was only increased in astrocytes. In contrast, GW0742 reduced BMP2 and BMP4 mRNA levels in OPCs, with lesser effects in astrocytes. These findings demonstrate that PPARδ plays a role in OPC maturation, mediated, in part, by regulation of BMP and BMP antagonists.     

Human amniotic epithelial cells suppress relapse of corticosteroid-remitted experimental autoimmune disease

Background aimsMultiple sclerosis (MS) is considered to be a T-cell–mediated disease. Although MS remits with corticosteroid treatment, the disease relapses on discontinuation of therapy. Human amniotic epithelial cells (hAEC) from the placenta are readily accessible in large quantities and have anti-inflammatory properties. Previously we reported that hAEC given near disease onset ameliorated clinical signs and decreased myelin oligodendrocyte glycoprotein (MOG)-specific immune responses in MOG-induced experimental autoimmune encephalomyelitis (EAE), an experimental MS model.MethodsTo examine the therapeutic effect of hAEC in a clinically relevant setting, we first treated MOG peptide–induced EAE mice with a corticosteroid, prednisolone, in drinking water to induce remission. hAEC were then infused intravenously into the remitted mice. Anti-MOG antibodies in serum were detected by enzyme-linked immunoassay. Splenocyte proliferation was assessed by ³H-thymidine incorporation. Immune cell subpopulations in spleens and lymph nodes and secreted cytokines in splenocyte culture were quantified by flow cytometry. Central nervous system histology was examined with the use of hematoxylin and eosin, Luxol fast blue and immunostaining.ResultsWith cessation of prednisolone treatment, hAEC delayed EAE relapse for 7 days, and, after another 7 days, largely remitted disease in six of eight responder mice. Splenocyte proliferation was suppressed, anti-MOG_35–55 antibodies in serum were decreased and interleukin-2 and interleukin-5 production by splenocytes were elevated after hAEC treatment. In the central nervous system, hAEC-treated mice had decreased demyelination and fewer macrophages in the inflammatory infiltrates. hAEC treatment also increased CD4⁺CD25⁺FoxP3⁺ regulatory T cells in inguinal lymph nodes.ConclusionsThese data demonstrate that the therapeutic effects of hAEC after corticosteroid treatment in an MS model probably are the consequence of peripheral immunoregulation. We suggest that hAEC may have potential as a cell therapy for remitted MS.     

Identification of N-benzyltetrahydroisoquinolines as novel anti-neuroinflammatory agents

A series of simplified berberine analogs was designed, synthesized, and evaluated for anti-inflammatory activity. SAR studies identified N-benzyltetrahydroisoquinoline 7d as a potent berberine analog. 7d suppressed LPS-induced inflammatory cytokine levels in both BV2 cells and primary microglia. Taken together, our results suggest that simplified BB analogs have therapeutic potential as a novel class of anti-neuroinflammatory agents.     

It is still not for the old iron: adjuvant effects of carbonyl iron in experimental autoimmune encephalomyelitis induction

Experimental autoimmune encephalomyelitis (EAE) is a model of multiple sclerosis. Dark Agouti rats immunized with spinal cord homogenate (SCH) and carbonyl iron (CI), as an adjuvant, develop severe hyperacute form of EAE. They succumb to EAE earlier and have higher clinical scores and lethality rate in comparison to counterparts immunized with SCH + complete Freund's adjuvant. There is no difference in the number of cells or in histological presentation of the CNS infiltrates of rats immunized with the two adjuvants. However, there are more granulocytes, NK and NKT cells, and less CD4(+) T cells in the spinal cord infiltrates of SCH + CI-immunized animals. Nitric oxide (NO)-generating enzyme inducible NO synthase have higher expression in spinal cord of SCH + CI-immunized rats, and this corresponds to more intensive nitrotyrosine formation in the CNS tissue of these rats. Abundant infiltration of granulocytes and NK cells into the CNS and excessive generation of peroxynitrite within the CNS of SCH + CI-immunized rats might account for the severe neurological deficits induced by immunization with CI. These factors should be closely examined in the fulminant forms of multiple sclerosis and acute disseminated encephalomyelitis, as they could represent a promising targets for therapy.     

Modulation of the cannabinoid CB2 receptor in microglial cells in response to inflammatory stimuli

The cannabinoid system is known to be important in neuronal regulation, but is also capable of modulating immune function. Although the CNS resident microglial cells have been shown to express the CB2 subtype of cannabinoid receptor during non-immune-mediated pathological conditions, little is known about the expression of the cannabinoid system during immune-mediated CNS pathology. To examine this question, we measured CB2 receptor mRNA expression in the CNS of mice with experimental autoimmune encephalomyelitis (EAE) and, by real-time PCR, found a 100-fold increase in CB2 receptor mRNA expression during EAE onset. We next determined whether microglial cells specifically express the CB2 receptor during EAE, and found that activated microglial cells expressed 10-fold more CB2 receptor than microglia in the resting state. To determine the signals required for the up-regulation of the CB2 receptor, we cultured microglial cells with combinations of gamma-interferon (IFN-gamma) and granulocyte) macrophage-colony stimulating factor (GM-CSF), which both promote microglial cell activation and are expressed in the CNS during EAE, and found that they synergized, resulting in an eight to 10-fold increase in the CB2 receptor. We found no difference in the amount of the CB2 receptor ligand, 2-arachidonylglycerol (2-AG), in the spinal cord during EAE. These data demonstrate that microglial cell activation is accompanied by CB2 receptor up-regulation, suggesting that this receptor plays an important role in microglial cell function in the CNS during autoimmune-induced inflammation.     

Myelin Oligodendrocyte Glycoprotein (MOG35-55) Induced Experimental Autoimmune Encephalomyelitis (EAE) in C57BL/6 Mice

Multiple sclerosis is a chronic neuroinflammatory demyelinating disorder of the central nervous system with a strong neurodegenerative component. While the exact etiology of the disease is yet unclear, autoreactive T lymphocytes are thought to play a central role in its pathophysiology. MS therapy is only partially effective so far and research efforts continue to expand our knowledge on the pathophysiology of the disease and to develop novel treatment strategies. Experimental autoimmune encephalomyelitis (EAE) is the most common animal model for MS sharing many clinical and pathophysiological features. There is a broad diversity of EAE models which reflect different clinical, immunological and histological aspects of human MS. Actively-induced EAE in mice is the easiest inducible model with robust and replicable results. It is especially suited for investigating the effects of drugs or of particular genes by using transgenic mice challenged by autoimmune neuroinflammation. Therefore, mice are immunized with CNS homogenates or peptides of myelin proteins. Due to the low immunogenic potential of these peptides, strong adjuvants are used. EAE susceptibility and phenotype depends on the chosen antigen and rodent strain. C57BL/6 mice are the commonly used strain for transgenic mouse construction and respond among others to myelin oligodendrocyte glycoprotein (MOG). The immunogenic epitope MOG_35-55 is suspended in complete Freund''s adjuvant (CFA) prior to immunization and pertussis toxin is applied on the day of immunization and two days later. Mice develop a "classic" self-limited monophasic EAE with ascending flaccid paralysis within 9-14 days after immunization. Mice are evaluated daily using a clinical scoring system for 25-50 days. Special considerations for care taking of animals with EAE as well as potential applications and limitations of this model are discussed.     

Experimental Allergic Encephalomyelitis in Connexin 43-Heterozygous Mice

Alterations in the expression of gap junction proteins (connexins) have previously been observed in experimental allergic encephalomyelitis (EAE). Demyelinating lesions have significantly decreased Cx43, while recovering lesions have greatly increased Cx43 and increased glial fibrillary acidic protein-expressing astrocytes. This suggests an important role for gap-junctional intercellular communication in astrocytes in the recovery from CNS inflammation. To study the effects of decreased Cx43 expression during acute disease (21 days post-immunization) and in recovering spinal cord tissue (55 days post-immunization) we induced EAE in Cx43 heterozygous and wild-type mice. Mice showed signs of disease by day 10, and signs of recovery by day 25. There were no clinical or pathological differences between heterozygous and wild-type mice in the acute disease stage, except that wild-type male mice had fewer clinical signs of disease. Male mice that were heterozygous for Cx43, and therefore had decreased expression of Cx43, had increased EAE disease severity. All demyelinating lesions had reduced numbers of reactive astrocytes and a significant decrease in Cx43 expression. In the 55-day study, all heterozygous and wild-type mice were clinically improved, showed decreased pathological signs, and showed increased laminin expression, indicative of CNS recovery. Furthermore, all heterozygous mice showed a striking increase in Cx43 expression during recovery, suggesting that the regulatory factors affecting Cx43 expression are still present in mice that have only one wild-type Cx43 allele.     

A comparative study of cells in inflammation,EAE and MS using biomedical literature data mining

Summary Biomedical literature and database annotations, available in electronic forms, contain a vast amount of knowledge resulting from global research. Users, attempting to utilize the current state-of-the-art research results are frequently overwhelmed by the volume of such information, making it difficult and time-consuming to locate the relevant knowledge. Literature mining, data mining, and domain specific knowledge integration techniques can be effectively used to provide a user-centric view of the information in a real-world biological problem setting. Bioinformatics tools that are based on real-world problems can provide varying levels of information content, bridging the gap between biomedical and bioinformatics research. We have developed a user-centric bioinformatics research tool, called BioMap, that can provide a customized, adaptive view of the information and knowledge space. BioMap was validated by using inflammatory diseases as a problem domain to identify and elucidate the associations among cells and cellular components involved in multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE). The BioMap system was able to demonstrate the associations between cells directly excavated from biomedical literature for inflammation, EAE and MS. These association graphs followed the scale-free network behavior (average γ = 2.1) that are commonly found in biological networks.     

Genetic inactivation of the adenosine A(2A) receptor exacerbates brain damage in mice with experimental autoimmune encephalomyelitis

Studies with multiple sclerosis patients and animal models of experimental autoimmune encephalomyelitis (EAE) implicate adenosine and adenosine receptors in modulation of neuroinflammation and brain injury. Although the involvement of the A(1) receptor has been recently demonstrated, the role of the adenosine A(2A) receptor (A(2A) R) in development of EAE pathology is largely unknown. Using mice with genetic inactivation of the A(2A) receptor, we provide direct evidence that loss of the A(2A) R exacerbates EAE pathology in mice. Compared with wild-type mice, A(2A) R knockout mice injected with myelin oligodendroglia glycoprotein peptide had a higher incidence of EAE and exhibited higher neurological deficit scores and greater decrease in body weight. A(2A) R knockout mice displayed increased inflammatory cell infiltration and enhanced microglial cell activation in cortex, brainstem, and spinal cord. In addition, demyelination and axonal damage in brainstem were exacerbated, levels of Th1 cytokines increased, and Th2 cytokines decreased. Collectively, these findings suggest that extracellular adenosine acting at A(2A) Rs triggers an important neuroprotective mechanism. Thus, the A(2A) receptor is a potential target for therapeutic approaches to multiple sclerosis.