Early Phase Of Experimental Autoimmune Encephalomyelitis Research Articles

Changes in structural plasticity of hippocampal neurons in an animal model of multiple sclerosis.

Structural plasticity is critical for the functional diversity of neurons in the brain. Experimental autoimmune encephalomyelitis (EAE) is the most commonly used model for multiple sclerosis (MS), successfully mimicking its key pathological features (inflammation, demyelination, axonal loss, and gliosis) and clinical symptoms (motor and non-motor dysfunctions). Recent studies have demonstrated the importance of synaptic plasticity in EAE pathogenesis. In the present study, we investigated the features of behavioral alteration and hippocampal structural plasticity in EAE-affected mice in the early phase (11 days post-immunization, DPI) and chronic phase (28 DPI). EAE-affected mice exhibited hippocampus-related behavioral dysfunction in the open field test during both early and chronic phases. Dendritic complexity was largely affected in the cornu ammonis 1 (CA1) and CA3 apical and dentate gyrus (DG) subregions of the hippocampus during the chronic phase, while this effect was only noted in the CA1 apical subregion in the early phase. Moreover, dendritic spine density was reduced in the hippocampal CA1 and CA3 apical/basal and DG subregions in the early phase of EAE, but only reduced in the DG subregion during the chronic phase. Furthermore, mRNA levels of proinflammatory cytokines ( Il1β, Tnfα, and Ifnγ) and glial cell markers ( Gfap and Cd68) were significantly increased, whereas the expression of activity-regulated cytoskeleton-associated protein (ARC) was reduced during the chronic phase. Similarly, exposure to the aforementioned cytokines in primary cultures of hippocampal neurons reduced dendritic complexity and ARC expression. Primary cultures of hippocampal neurons also showed significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation upon treatment with proinflammatory cytokines. Collectively, these results suggest that autoimmune neuroinflammation alters structural plasticity in the hippocampus, possibly through the ERK-ARC pathway, indicating that this alteration may be associated with hippocampal dysfunctions in EAE.

CD47 antibody blockade suppresses microglia-dependent phagocytosis and monocyte transition to macrophages, impairing recovery in EAE.

Experimental autoimmune encephalomyelitis (EAE) is a well-characterized animal model of multiple sclerosis. During the early phase of EAE, infiltrating monocytes and monocyte-derived macrophages contribute to T cell recruitment, especially CD4+ T cells, into the CNS, resulting in neuronal demyelination; however, in later stages, they promote remyelination and recovery by removal of myelin debris by phagocytosis. Signal regulatory protein α and CD47 are abundantly expressed in the CNS, and deletion of either molecule is protective in myelin oligodendrocyte glycoprotein–induced EAE because of failed effector T cell expansion and trafficking. Here we report that treatment with the function blocking CD47 Ab Miap410 substantially reduced the infiltration of pathogenic immune cells but impaired recovery from paresis. The underlying mechanism was by blocking the emergence of CD11chiMHCIIhi microglia at peak disease that expressed receptors for phagocytosis, scavenging, and lipid catabolism, which mediated clearance of myelin debris and the transition of monocytes to macrophages in the CNS. In the recovery phase of EAE, Miap410 Ab–treated mice had worsening paresis with sustained inflammation and limited remyelination as compared with control Ab–treated mice. In summary, Ab blockade of CD47 impaired resolution of CNS inflammation, thus worsening EAE.

Role of SOCS2 in the Regulation of Immune Response and Development of the Experimental Autoimmune Encephalomyelitis.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). Experimental Autoimmune Encephalomyelitis (EAE) is the most widely used animal model for the study of MS. The Suppressor of Cytokine Signaling (SOCS) 2 protein plays a critical role in regulating the immune responses. The role of SOCS2 during EAE has not been explored. EAE was induced in WT and SOCS2−/− mice using myelin oligodendrocyte glycoprotein (MOG35-55) peptide. Brain and spinal cord were examined during the peak (day 14) and recovery phase (day 28) of the disease. SOCS2 was upregulated in the brain of WT mice at the peak and recovery phase of EAE. The development of the acute phase was slower in onset in SOCS2−/− mice and was associated with reduced number of Th1 (CD3+CD4+IFN-γ+) cells in the spinal cord and brain. However, while in WT mice, maximal clinical EAE score was followed by a progressive recovery; the SOCS2−/− mice were unable to recover from locomotor impairment that occurred during the acute phase. There was a prolonged inflammatory response (increased Th1 and decreased Th2 and T regulatory cells) in the late phase of EAE in the CNS of SOCS2−/− mice. Transplantation of bone marrow cells from SOCS2−/− into irradiated WT mice resulted in higher lethality at the early phase of EAE. Altogether, these results suggest that SOCS2 plays a dual role in the immune response during EAE. It is necessary for damage during the acute phase damage but plays a beneficial role in the recovery stage of the disease.

Critical role of STAT5 tetramerization in the pathogenesis of experimental autoimmune encephalomyelitis, a murine model of multiple sclerosis

Abstract Multiple sclerosis (MS) is an immune mediated disease that predominantly impacts the central nervous system (CNS). Current MS treatments have demonstrated the ability to reduce the rate of MS relapses; however, they are not effective at preventing disease progression. Elucidating the pathways that govern the pathogenesis of MS may identify molecular mediators, which can act as novel therapeutic targets to treat MS progression. STAT5 is a transcription factor critical for the generation, activation, and function of different immune cell types. Upon activation, STAT5 can form dimers or tetramers, which have distinct functions. Using a Stat5a-Stat5b double knock-in N-domain mutant mouse strain (DKI mice), in which STAT5 dimers are functional, but STAT5 tetramers cannot be formed, we demonstrated that DKI mice developed less severe experimental autoimmune encephalomyelitis (EAE), a model of MS, compared to WT littermates. Moreover, a portion of DKI mice did not develop EAE symptoms. Flow cytometric analysis of peripheral blood revealed that during the early phase of EAE, WT and DKI mice exhibited similar levels of immune cell expansion in the periphery. However, at the peak of EAE, DKI mice had fewer immune cells in the CNS. This suggests that STAT5 tetramers promote immune cell egress to the CNS or/and immune cell expansion within the CNS. In addition, multiplex protein assays established that the expression of a pro-inflammatory cytokine and several chemokines, including IL-1α, CCL3, CCL17, and CCL22, are reduced in DKI mice compared to WT mice, which may account for the reduced disease severity observed in DKI mice. Taken together, the data suggest that STAT5 tetramers plays a multifaceted role in promoting inflammation resulting in EAE.

The role of fatty acid binding protein 7 in spinal cord astrocytes in a mouse model of experimental autoimmune encephalomyelitis

Fatty acid binding protein 7 (FABP7) is expressed in astrocytes of the developing and mature central nervous system, and modulates astrocyte function by controlling intracellular fatty acid homeostasis. Astrocytes in the spinal cord have an important role in the process of myelin degeneration and regeneration. In the present study, the authors examined the role of FABP7 in astrocytes in a mouse model of experimental autoimmune encephalomyelitis (EAE), which is an established model of multiple sclerosis (MS). FABP7 was expressed in the white matter astrocytes and increased after EAE onset; particularly strong expression was observed in demyelinating regions. In FABP7-knockout (KO) mice, the onset of EAE symptoms occurred earlier than in wild type (WT) mice, and mRNA expression levels of inflammatory cytokines (IL-17 and TNF-α) were higher in FABP7-KO lumbar spinal cord than in WT lumbar spinal cord at early stage of EAE. Interestingly, however, the clinical score was significantly reduced in FABP7-KO mice compared with WT mice in the late phase of EAE. Moreover, the area exhibiting expression of fibronectin, which is an extracellular matrix protein mainly produced by astrocytes and inhibits remyelination of oligodendrocytes, was significantly decreased in FABP7-KO compared with WT mice. Collectively, FABP7 in astrocyte may have a role to protect from the induction of inflammation leading to demyelination in CNS at early phase of EAE. Moreover, FABP7 may be involved in the regulation of fibronectin production through the modification of astrocyte activation at late phase of EAE.

The Renin-Angiotensin System Regulates Neurodegeneration in a Mouse Model of Optic Neuritis

The major role of the renin-angiotensin system (RAS), including that of angiotensin II (Ang II), the principal effector molecule, in the cardiovascular system is well known. Increasing evidence suggests that the RAS also plays a role in the development of autoimmune diseases. Optic neuritis (ie, inflammation of the optic nerve, with retinal ganglion cell loss) is strongly associated with multiple sclerosis. We investigated the effects of candesartan, an Ang II receptor antagonist, on optic neuritis in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. The Ang II concentration was increased in the early phase of EAE. Oral administration of candesartan markedly attenuated demyelination of the optic nerve and spinal cord and reduced retinal ganglion cell loss and visual impairment in mice with EAE. Invitro analyses revealed that Ang II up-regulated the expression of Toll-like receptor (TLR)-4 in astrocytes via the NF-κB pathway. In addition, Ang II treatment enhanced lipopolysaccharide-induced production of monocyte chemoattractant protein 1 in astrocytes, and pretreatment with candesartan or SN50, an NF-κB inhibitor, suppressed the effects of Ang II. The novel pathway of RAS-NF-κB-TLR4 in glial cells identified in the present study may be a valid therapeutic target for neurodegeneration in neuroinflammatory diseases.

Your nose knows how to target brain inflammation

Your nose knows how to target brain inflammation

P170 The immunomodulatory effect of type I interferon signaling in T cells during the onset of experimental autoimmune encephalomyelitis (EAE)

Introduction Interferon beta (IFN β ) is used widely as first-line treatment for multiple sclerosis (MS). However, the role of endogenous versus exogenous IFN β remains enigmatic with often contradictory results. During experimental autoimmune encephalomyelitis (EAE), an induced animal model of MS, neuroantigen-specific T cells exist in the periphery before the clinical signs of the disease. Our objective is to study how IFN β signaling in peripheral T cells affects the outcome of EAE. Methods To investigate the effect of type I IFNs on T cells during EAE, transgenic mice, that express functional type I IFN receptor (IFNAR1) exclusively on T lymphocytes, were generated. Wild-type (WT), IFNAR1 knockout (IFNAR1 −/− ) and transgenic (TgIFNAR1 −/− T +/− ) mice were immunized with MOG 35-55 peptide, to induce EAE. Clinical score was monitored and cytokine production by T cells in the periphery and the CNS was measured using flow cytometry in early phase of EAE. Additionally, spinal cord sections were assessed for inflammation, demyelination and axonal damage. To determine significant differences in clinical scores between study groups, the Mann–Whitney U test was performed. Results Transgenic mice exhibited a delayed onset and a milder progression of acute phase of EAE, as compared to WT and IFNAR1 −/− mice. No significant differences were detected in the proliferative capacity and the frequency of IL-17, IFN γ - or IL-10 producing T cells in spleen and draining lymph nodes, in either case of mice on day 17 of EAE. Moreover, no cells were detected within the CNS of TgIFNAR1 −/− T +/− mice, which was in accordance with their clinical score. However, IL-17 and IFN γ producing CD4+ cells were present in the spinal cord of WT and IFNAR1 −/− mice. Spinal cord sections from all groups showed lesions characteristic of EAE, although TgIFNAR1 −/− T +/− mice showed lower extent of pathology compared to IFNAR1 −/− , but similar to that of WT mice, with a lower degree of inflammation and neuronal degeneration. Conclusion These results indicate a protective role of endogenously produced type I IFNs in EAE, when signaling is T cell restricted. This role cannot be attributed either to pro- or anti-inflammatory cytokine profile of T cells in the periphery. To explore this phenomenon, we study the immunological response in the periphery, at the pre-onset of EAE, when T effector cells are already present, highly inflammatory. Our future goal is to investigate the effect of IFN β treatment both on clinical outcome of EAE and activation of T cells in our transgenic mice and the correlation with the observed beneficial effect of endogenous IFN β .

Identification of Cellular Infiltrates during Early Stages of Brain Inflammation with Magnetic Resonance Microscopy

A comprehensive view of brain inflammation during the pathogenesis of autoimmune encephalomyelitis can be achieved with the aid of high resolution non-invasive imaging techniques such as microscopic magnetic resonance imaging (μMRI). In this study we demonstrate the benefits of cryogenically-cooled RF coils to produce μMRI in vivo, with sufficient detail to reveal brain pathology in the experimental autoimmune encephalomyelitis (EAE) model. We could visualize inflammatory infiltrates in detail within various regions of the brain, already at an early phase of EAE. Importantly, this pathology could be seen clearly even without the use of contrast agents, and showed excellent correspondence with conventional histology. The cryogenically-cooled coil enabled the acquisition of high resolution images within short scan times: an important practical consideration in conducting animal experiments. The detail of the cellular infiltrates visualized by in vivo μMRI allows the opportunity to follow neuroinflammatory processes even during the early stages of disease progression. Thus μMRI will not only complement conventional histological examination but will also enable longitudinal studies on the kinetics and dynamics of immune cell infiltration.

The link between inflammation, synaptic transmission and neurodegeneration in multiple sclerosis

Multiple sclerosis (MS) has been classically regarded as a disorder of the white matter of the central nervous system (CNS). However, early alterations of the neuronal compartment occurring in this disorder are partially independent of demyelination. Soluble inflammatory cytokines and glutamate have been proposed as major determinants of neurodegeneration in MS as well as in its experimental animal model, namely experimental autoimmune encephalomyelitis (EAE). The relationship between these two major determinants has been largely elusive. In recent years, unexpected connections have emerged between immune cells and soluble cytokines on the one hand, and synaptic transmission and neurodegeneration on the other. Neurophysiological recordings have recently shown that glutamate-mediated excitatory postsynaptic currents are enhanced during the early phase of EAE, because of altered expression and phosphorylation of AMPA receptors and the downregulation of the immediate early gene Arc/Arg3.1. The synaptic alterations occurring during neuroinflammatory diseases are largely mediated by inflammatory cytokines released from infiltrating T cells and from activated microglia, and are responsible, at least in part, for irreversible dendritic pathology. Collectively, the data covered in this review article suggest that CNS-confined inflammation in MS is associated with the release of soluble molecules, which are capable of altering excitatory synaptic transmission and, finally, of stimulating secondary neurodegenerative gray matter pathology.

Chronological Changes of CD4+ and CD8+ T Cell Subsets in the Experimental Autoimmune Encephalomyelitis, a Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS). The etiology of MS remains unclear, but T cells specific for myelin components, such as myelin oligodendrocyte glycoprotein (MOG), are thought to play a critical role in the onset of MS. Experimental autoimmune encephalomyelitis (EAE) has been used as an animal model of MS, and T helper type 1 (Th1) cells play an essential role for the pathogenesis of EAE through the production of Th1 cytokines, interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). We examined CD4(+) and CD8(+) T cell responses in the spleen and CNS of EAE mice, generated by immunization with a peptide (35-55 amino acid residues) of MOG. The number of both CD4(+) and CD8(+) T cells and their MOG-reactivity in the CNS were associated with increasing disease severity but not those in the spleen, suggesting that the MOG-specific CD4(+) and CD8(+) T cells in the CNS are involved in the development of EAE. Polymerase chain reaction analysis suggested that both CD4(+) and CD8(+) T cells produced IFN-gamma and TNF-alpha, while CD4(+) T cells also produced interleukin-17 (IL-17), an important factor in the development of EAE. Thus, CD4(+) T cells may contribute to the induction of EAE by producing IL-17. Furthermore, CD8(+) T cells express higher levels of a suppressive cytokine, IL-10. Taking together, our data suggest that CD4(+) T cells are involved in the early phase of EAE, whereas CD8(+) T cells have a regulatory role in the later stage of EAE.