Animal Model Of Multiple Sclerosis Research Articles

NR4A1 agonist cytosporone B attenuates neuroinflammation in a mouse model of multiple sclerosis.

Nuclear receptor subfamily 4 group A1 (NR4A1) is an orphan nuclear receptor, which is expressed in the majority of cells. NR4A1 expression in peripheral blood mononuclear cells is low during the preclinical stage of multiple sclerosis. Knockout of the Nr4a1 gene in mice can aggravate the symptoms of experimental autoimmune encephalomyelitis (EAE), which is an animal model of multiple sclerosis. In this study, we intragastrically administered the NR4A1 agonist cytosporone B (Csn-B) to mice after inducing EAE. After treatment with Csn-B, the clinical symptoms in the EAE mice were substantially attenuated compared with that in PBS-treated control mice. The percentages of CD4+ T cells and F4/80+ cells in the central nervous system were decreased. In addition, interferon-γ and interleukin-17 production by proinflammatory Th1/Th17 cells in the central nervous system and interferon-γ levels in splenocytes were decreased after Csn-B treatment. These findings suggest that the NR4A1 agonist Csn-B can alleviate nerve injury after EAE induction, and, therefore, may be useful as a potential treatment for multiple sclerosis.

Encapsulation of bryostatin-1 by targeted exosomes enhances remyelination and neuroprotection effects in the cuprizone-induced demyelinating animal model of multiple sclerosis.

Demyelination is a critical neurological disease, and there is still a lack of effective treatment methods. In the past two decades, stem cells have emerged as a novel therapeutic effector for neural regeneration. However, owing to the existence of the blood-brain barrier (BBB) and the complex microenvironment, targeted therapy still faces multiple challenges. Targeted exosome carriers for drug delivery may be considered a promising therapeutic method. Exosomes were isolated from mice neural stem cells. To develop targeting exosomes, we generated a lentivirus armed PDGFRα ligand that could anchor the membrane. Exosome targeting tests were carried out in vitro and in vivo. The modified exosomes showed an apparent ability to target OPCs in the lesion area. Next, the exosomes were loaded with Bryostatin-1 (Bryo), and the cuprizone-fed mice were administered with the targeting exosomes. The data show that Bryo exhibits a powerful therapeutic effect compared with Bryo alone after exosome encapsulation. Specifically, this novel exosome-based targeting delivery of Bryo significantly improves the protection ability of the myelin sheath and promotes remyelination. Moreover, it blocks astrogliosis and axon damage, and also has an inhibitory effect on pro-inflammatory microglia. The results of this investigation provide a straightforward strategy to produce targeting exosomes and indicate a potential therapeutic approach for demyelinating disease.

The C-type lectin receptor Clec1A plays an important role in the development of experimental autoimmune encephalomyelitis by enhancing antigen presenting ability of dendritic cells and inducing inflammatory cytokine IL-17.

Clec1A, a member of C-type lectin receptor family, has a carbohydrate recognition domain in its extracellular region, but no known signaling motif in the cytoplasmic domain. Clec1a is highly expressed in endothelial cells and weakly in dendritic cells. Although this molecule was reported to play an important role in the host defense against Aspergillus fumigatus by recognizing 1,8-dihydroxynaphthalene-melanin on the fungal surface, the roles of this molecule in un-infected animals remain to be elucidated. In this study, we found that Clec1a−/− mice develop milder symptoms upon induction of experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. The maximum disease score was significantly lower, and demyelination and inflammation of the spinal cord were much milder in Clec1a−/− mice compared to wild-type mice. No abnormality was detected in the immune cell composition in the draining lymph nodes and spleen on day 10 and 16 after EAE induction. Recall memory T cell proliferation after restimulation with myelin oligodendrocyte glycoprotein peptide (MOG35–55) in vitro was decreased in Clec1a−/− mice, and antigen presenting ability of Clec1a−/− dendritic cells was impaired. Interestingly, RNA-Seq and RT-qPCR analyses clearly showed that the expression of inflammatory cytokines including Il17a, Il6 and Il1b was greatly decreased in Clec1a−/− mice after induction of EAE, suggesting that this reduced cytokine production is responsible for the amelioration of EAE in Clec1a−/− mice. These observations suggest a novel function of Clec1A in the immune system.

Evaluation of some blood parameters in the experimental autoimmune encephalomyelitis mouse model

Multiple sclerosis (MS) is a chronic neuroinflammatory demyelinating disorder of the central nervous system with unclear exact etiology. The experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice is the most common animal model for MS sharing many clinical and pathophysiological features to expand our knowledge on the pathophysiology of the disease and to develop novel treatment strategies. The current study was planned to evaluate the effect of EAE on hematologic and plasma total protein and albumin levels in C57BL/6 mice.
 EAE was induced with myelin oligodendrocyte glycoprotein (MOG35-55) peptide in the female C57BL/6 mice. The EAE clinically caused paralyzed tail, hind limb paresis, and uncoordinated movement in the mice. The EAE-induced mice hematologically had a mild increase in white blood cell count without altering neutrophil-lymphocyte ratio but no change in vital hematological parameters such as red blood cell count, packed cell volume, and hemoglobin level. Moreover, the EAE produced a rise in the plasma total protein level and an attenuation in plasma albumin level in the mice.
 In conclusion, our findings show that the EAE model in mice might not cause any significant change hematologically, except a slight increase in the white blood cell count, and might produce changes in the plasma protein level. The EAE-induced blood parameter effects, as the findings of the current study, could take consideration in terms of understanding the pathophysiology of the disease and developing a novel therapeutic approach for the disease.

Therapeutic Potentials of Poly (ADP-Ribose) Polymerase 1 (PARP1) Inhibition in Multiple Sclerosis and Animal Models: Concept Revisiting.

Poly (ADP‐ribose) polymerase 1 (PARP1) plays a fundamental role in DNA repair and gene expression. Excessive PARP1 hyperactivation, however, has been associated with cell death. PARP1 and/or its activity are dysregulated in the immune and central nervous system of multiple sclerosis (MS) patients and animal models. Pharmacological PARP1 inhibition is shown to be protective against immune activation and disease severity in MS animal models while genetic PARP1 deficiency studies reported discrepant results. The inconsistency suggests that the function of PARP1 and PARP1‐mediated PARylation may be complex and context‐dependent. The article reviews PARP1 functions, discusses experimental findings and possible interpretations of PARP1 in inflammation, neuronal/axonal degeneration, and oligodendrogliopathy, three major pathological components cooperatively determining MS disease course and neurological progression, and points out future research directions. Cell type specific PARP1 manipulations are necessary for revisiting the role of PARP1 in the three pathological components prior to moving PARP1 inhibition into clinical trials for MS therapy.

S100B Protein as a Therapeutic Target in Multiple Sclerosis: The S100B Inhibitor Arundic Acid Protects from Chronic Experimental Autoimmune Encephalomyelitis.

S100B is an astrocytic protein behaving at high concentration as a damage-associated molecular pattern molecule. A direct correlation between the increased amount of S100B and inflammatory processes has been demonstrated, and in particular, the inhibitor of S100B activity pentamidine has been shown to ameliorate clinical scores and neuropathologic-biomolecular parameters in the relapsing-remitting experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. This study investigates the effect of arundic acid (AA), a known inhibitor of astrocytic S100B synthesis, in the chronic experimental autoimmune encephalomyelitis, which is another mouse model of multiple sclerosis usually studied. By the daily evaluation of clinical scores and neuropathologic-molecular analysis performed in the spinal cord, we observed that the AA-treated group showed lower severity compared to the vehicle-treated mice, particularly in the early phase of disease onset. We also observed a significant reduction of astrocytosis, demyelination, immune infiltrates, proinflammatory cytokines expression and enzymatic oxidative reactivity in the AA-treated group. Overall, our results reinforce the involvement of S100B in the development of animal models of multiple sclerosis and propose AA targeting the S100B protein as a focused potential drug to be considered for multiple sclerosis treatment.

An optimized and validated protocol for inducing chronic experimental autoimmune encephalomyelitis in C57BL/6J mice

BackgroundMyelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis (EAE) is the most commonly used animal model of multiple sclerosis. However, variations in the induction protocol can affect EAE progression, and may reduce the comparability of data. Optimized methodIn the present study, we investigated the influence of the different components used for EAE induction in C57BL/6J mice on disease progression. MOG35–55-induced chronic EAE in C57BL/6J mice has been applied as a model to challenge optimal pertussis toxin (PTx) dosing, while considering variations in batch potency. ResultsWe demonstrate that the dosage of PTx, adjusted to its potency, influences EAE development in a dose-dependent manner. Our data show that with our protocol, which considers PTx potency, C57BL/6J mice consistently develop symptoms of EAE. The mice show a typical chronic course with symptom onset after 10.5 ± 1.08 days and maximum severity around day 16 postimmunization followed by a mild remission of symptoms. Comparison with existing methodsPreviously studies reveal that alterations in PTx dosing directly modify EAE progression. Our present study highlights that PTx batches differ in potency, resulting in inconsistent EAE induction. We also provide a clear protocol that allows a reduction in the number of mice used in EAE experiments, while maintaining consistent results. ConclusionHigher standards for comparability and reproducibility are needed to ensure and maximize the generation of reliable EAE data. Specifically, consideration of PTx potency. With our method of establishing consistent EAE pathogenesis, improved animal welfare standards and a reduction of mice used in experimentation can be achieved.

Neuroprotective Effect of Glatiramer Acetate on Neurofilament Light Chain Leakage and Glutamate Excess in an Animal Model of Multiple Sclerosis.

Axonal and neuronal pathologies are a central constituent of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), induced by the myelin oligodendrocyte glycoprotein (MOG) 35–55 peptide. In this study, we investigated neurodegenerative manifestations in chronic MOG 35–55 induced EAE and the effect of glatiramer acetate (GA) treatment on these manifestations. We report that the neuronal loss seen in this model is not attributed to apoptotic neuronal cell death. In EAE-affected mice, axonal damage prevails from the early disease phase, as revealed by analysis of neurofilament light (NFL) leakage into the sera along the disease duration, as well as by immunohistological examination. Elevation of interstitial glutamate concentrations measured in the cerebrospinal fluid (CSF) implies that glutamate excess plays a role in the damage processes inflicted by this disease. GA applied as a therapeutic regimen to mice with apparent clinical symptoms significantly reduces the pathological manifestations, namely apoptotic cell death, NFL leakage, histological tissue damage, and glutamate excess, thus corroborating the neuroprotective consequences of this treatment.

Novel Approaches in the Immunotherapy of Multiple Sclerosis: Cyclization of Myelin Epitope Peptides and Conjugation with Mannan.

Multiple Sclerosis (MS) is a serious autoimmune disease. The patient in an advanced state of the disease has restrained mobility and remains handicapped. It is therefore understandable that there is a great need for novel drugs and vaccines for the treatment of MS. Herein we summarise two major approaches applied for the treatment of the disease using peptide molecules alone or conjugated with mannan. The first approach focuses on selective myelin epitope peptide or peptide mimetic therapy alone or conjugated with mannan, and the second on immune-therapy by preventing or controlling disease through the release of appropriate cytokines. In both approaches the use of cyclic peptides offers the advantage of increased stability from proteolytic enzymes. In these approaches, the synthesis of myelin epitope peptides conjugated to mannan is of particular interest as this was found to protect mice against experimental autoimmune encephalomyelitis, an animal model of MS, in prophylactic and therapeutic protocols. Protection was peptide-specific and associated with reduced antigen-specific T cell proliferation. The aim of the studies of these peptide epitope analogs is to understand their molecular basis of interactions with human autoimmune T-cell receptor and a MS-associated human leucocyte antigen (HLA)-DR2b. This knowledge will lead the rational design to new beneficial non-peptide mimetic analogs for the treatment of MS. Some issues of the use of nanotechnology will also be addressed as a future trend to tackle the disease. We highlight novel immunomodulation and vaccine-based research against MS based on myelin epitope peptides and strategies developed in our laboratories.

Timing of treatment with an endogenous opioid alters immune response and spinal cord pathology in female mice with experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a progressive disease of the central nervous system (CNS) that primarily affects women during the second or third decade of life. The mechanism is hypothesized to involve unregulated peripheral inflammation resulting in blood-brain barrier damage, and eventual axonal damage and demyelination. Based on this understanding, the animal model of MS, experimental autoimmune encephalomyelitis (EAE), often is utilized to study lymphocyte activation. Therapeutic paradigms of exogenous opioid growth factor (OGF) or low-dose naltrexone (LDN) treatment can modulate EAE, but little is reported regarding OGF or LDN effects on peripheral inflammation, microglia activation, and/or macrophage proliferation. Moreover, little is known about differential responses to LDN or OGF relative to the duration and timing of treatment. Utilizing a female mouse model of EAE, two treatment regimens were established to investigate differences between prophylactic treatment and traditional therapy initiated at the time of disease presentation. Prophylactic OGF or LDN treatment delayed the onset of behavior, suppressed neutrophil replication, and curtailed lymphocyte proliferation which ultimately improved behavioral outcome. Traditional therapy with OGF or LDN reversed behavioral deficits, restored OGF and IL-17 serum levels, and inhibited microglial activation within 8days. Reduced serum OGF levels in untreated EAE mice correlated with increased microglia activation within lumbar spinal cords. Both treatment regimens of OGF or LDN reduced activated microglia, whereas only prophylactic treatment prevented CNS macrophage aggregation. These data demonstrate that the timing of LDN or OGF treatment initiation alters outcomes and can prevent or reverse behavioral deficits, cytokine activation, and spinal cord pathology.

Dimethyl fumarate treatment restrains the antioxidative capacity of T cells to control autoimmunity

Dimethyl fumarate, an approved treatment for relapsing-remitting multiple sclerosis, exerts pleiotropic effects on immune cells as well as CNS resident cells.Here, we show that dimethyl fumarate exerts a profound alteration of the metabolic profile of human CD4+ as well as CD8+ T cells and restricts their antioxidative capacities by decreasing intracellular levels of the reactive oxygen species scavenger glutathione. This causes an increase in mitochondrial reactive oxygen species levels accompanied by an enhanced mitochondrial stress response, ultimately leading to impaired mitochondrial function. Enhanced mitochondrial reactive oxygen species levels not only result in enhanced T-cell apoptosis in vitro as well as in dimethyl fumarate-treated patients, but are key for the well-known immunomodulatory effects of dimethyl fumarate both in vitro and in an animal model of multiple sclerosis, i.e. experimental autoimmune encephalomyelitis. Indeed, dimethyl fumarate immune-modulatory effects on T cells were completely abrogated by pharmacological interference of mitochondrial reactive oxygen species production.These data shed new light on dimethyl fumarate as bona fide immune-metabolic drug that targets the intracellular stress response in activated T cells, thereby restricting mitochondrial function and energetic capacity, providing novel insight into the role of oxidative stress in modulating cellular immune responses and T cell-mediated autoimmunity.

Methyl Butyrate Alleviates Experimental Autoimmune Encephalomyelitis and Regulates the Balance of Effector T Cells and Regulatory T Cells.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS), characterized by demyelinating neuropathy. The etiology of MS is not yet clear and its treatment remains a major medical challenge. While we search for drugs that can effectively treat experimental autoimmune encephalomyelitis (EAE), the animal model of MS, we also hope to further explore its possible pathogenesis. In the present study, we investigated whether methyl butyrate (MB) could alleviate EAE and its potential mechanisms. In EAE mice, we found that administration of MB was effective in alleviating their clinical signs and improving histopathological manifestations of the CNS. In the CNS and intestinal lamina propria, we observed fewer effector T cells, including Th1 and Th17, in the MB-treated group. MB also increased the proportion of regulatory T cells and the secretion of IL-10 in peripheral immune organs. In vitro, MB led to suppression of Th1 cells and promotion of regulatory T cells in their differentiation. Given that MB had no direct effect on Th17 cell differentiation in vitro, we hypothesized that MB suppressed Th17 cells indirectly by inhibiting the secretion of IL-6, which was later confirmed both in vitro and in vivo. In addition, we found that MB treatment upregulated Maf gene expression in mice, which explained its promotion of IL-10 secretion. The above findings suggest that MB may provide new ideas for the study of the mechanism of MS and have positive implications for new drug development.

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.

Target engagement of the first-in-class CXCR7 antagonist ACT-1004-1239 following multiple-dose administration in mice and humans

Antagonism of the chemokine receptor CXCR7 has shown promising effects in diverse disease areas through modulation of its ligands, CXCL11 and CXCL12. Preclinical data of the first-in-class CXCR7 antagonist, ACT-1004-1239, showed efficacy in animal models of multiple sclerosis and acute lung injury. In healthy humans, single-dose administration of ACT-1004-1239 revealed a favorable clinical profile. Here, we report the target engagement of ACT-1004-1239 in healthy mice and humans after multiple doses using CXCL11 and CXCL12 as biomarkers. In addition, safety/tolerability, concentration-QTc relationship, and pharmacokinetics (PK) were assessed in a randomized, double-blind, placebo-controlled Phase 1 clinical study. Multiple-dose ACT-1004-1239 dose-dependently increased CXCL12 plasma concentration across the investigated dose range in mice and humans (mice: 1–100 mg/kg b.i.d.; humans: 30–200 mg o.d.) when compared to vehicle/placebo demonstrating target engagement. Mouse and human PK/PD models predicted that CXCL12 concentration approached a plateau within these dose ranges. In humans, ACT-1004-1239 was rapidly absorbed (tmax: 1.75–3.01 h) and the terminal t1/2 was approximately 19 h. Steady-state conditions were reached by Day 3 with an accumulation index of 1.2. Female subjects had overall higher exposure compared to males. Multiple-dose ACT-1004-1239 was well tolerated up to 200 mg once daily in humans. There was no evidence of ACT-1004-1239-mediated QTc interval prolongation. Overall, multiple oral doses of ACT-1004-1239 showed target engagement with CXCR7 in healthy mice and humans, therefore, assessment of CXCL12 as translational tool for further investigations in patients is warranted. Favorable safety/tolerability and PK profiles allow for further clinical development.

Pentafluorosulfanyl (SF5) as a Superior 19F Magnetic Resonance Reporter Group: Signal Detection and Biological Activity of Teriflunomide Derivatives.

Fluorine (19F) magnetic resonance imaging (MRI) is severely limited by a low signal-to noise ratio (SNR), and tapping it for 19F drug detection in vivo still poses a significant challenge. However, it bears the potential for label-free theranostic imaging. Recently, we detected the fluorinated dihydroorotate dehydrogenase (DHODH) inhibitor teriflunomide (TF) noninvasively in an animal model of multiple sclerosis (MS) using 19F MR spectroscopy (MRS). In the present study, we probed distinct modifications to the CF3 group of TF to improve its SNR. This revealed SF5 as a superior alternative to the CF3 group. The value of the SF5 bioisostere as a 19F MRI reporter group within a biological or pharmacological context is by far underexplored. Here, we compared the biological and pharmacological activities of different TF derivatives and their 19F MR properties (chemical shift and relaxation times). The 19F MR SNR efficiency of three MRI methods revealed that SF5-substituted TF has the highest 19F MR SNR efficiency in combination with an ultrashort echo-time (UTE) MRI method. Chemical modifications did not reduce pharmacological or biological activity as shown in the in vitro dihydroorotate dehydrogenase enzyme and T cell proliferation assays. Instead, SF5-substituted TF showed an improved capacity to inhibit T cell proliferation, indicating better anti-inflammatory activity and its suitability as a viable bioisostere in this context. This study proposes SF5 as a novel superior 19F MR reporter group for the MS drug teriflunomide.

Tumor Necrosis Factor Alpha Blockade and Multiple Sclerosis: Exploring New Avenues.

Multiple sclerosis (MS) is the most common disabling disease of the central nervous system (CNS) with a progressive neurodegenerative pattern. It is characterized by demyelination of white matter in CNS and apoptosis of oligodendrocytes. Tumor necrosis factor (TNF) alpha is a major cytokine in the pathogenesis of MS. However, the failure of TNF alpha inhibitors in preclinical and clinical trials disapproved of their use in MS patients. Nevertheless, failures and misses sometimes open avenues for new hits. In the later years, it was discovered that TNF signaling is mediated via two different receptors, TNFR1 and TNFR2, both of which have paradoxical effects. TNFR1 mediates demyelination and apoptosis, while TNFR2 promotes remyelination and neuroprotection. This explained the cause of the failure of non-selective TNF alpha-blockers in MS. It also enlightened researchers that repurposing the previously formulated non-selective TNF alpha-blockers using a receptor-selective approach could lead to discovering novel biologic agents with a broader spectrum of indications and better safety profiles. This review focuses on a novel premier TNFR1 blocker, atrosab, which has been tested in animal models of MS, experimental autoimmune encephalomyelitis (EAE), where it demonstrated a reduction in symptom severity. The early promise shown by atrosab in preclinical studies has given us hope to find another revolutionary drug for MS in the future. Clinical trials, which will finally decide whether this drug can be used as a better therapeutic agent for MS or not, are still going on, but currently, there is no approved evidence regarding efficacy of these agents in treating MS.

Exosomes derived from bone marrow mesenchymal stromal cells promote remyelination and reduce neuroinflammation in the demyelinating central nervous system

Injury of oligodendrocytes (OLs) induces demyelination, and patients with neurodegenerative diseases exhibit demyelination concomitantly with neurological deficit and cognitive impairment. Oligodendrocyte progenitor cells (OPCs) are present in the adult central nervous system (CNS), and they can proliferate, differentiate, and remyelinate axons after damage. However, remyelination therapies are not in clinical use. Multiple sclerosis (MS) is a major demyelinating disease in the CNS. Mesenchymal stromal cells (MSCs) have demonstrated therapeutic promise in animal models and in clinical trials of MS. Exosomes are nanoparticles generated by nearly all cells and they mediate cell-cell communication by transferring cargo biomaterials. Here, we hypothesize that exosomes harvested from MSCs have a similar therapeutic effect on enhancement of remyelination as that of MSCs. In the present study we employed exosomes derived from rhesus monkey MSCs (MSC-Exo). Two mouse models of demyelination were employed: 1) experimental autoimmune encephalomyelitis (EAE), an animal model of MS; and 2) cuprizone (CPZ) diet model, a toxic demyelination model. MSC-Exo or PBS were intravenously injected twice a week for 4 weeks, starting on day 10 post immunization in EAE mice, or once a week for 2 weeks starting on the day of CPZ diet withdrawal. Neurological and cognitive function were tested, OPC differentiation and remyelination, neuroinflammation and the potential underlying mechanisms were investigated using immunofluorescent staining, transmission electron microscopy and Western blot. Data generated from the EAE model revealed that MSC-Exo cross the blood brain barrier (BBB) and target neural cells. Compared with the controls (p < 0.05), treatment with MSC-Exo: 1) significantly improved neurological outcome; 2) significantly increased the numbers of newly generated OLs (BrdU+/APC+) and mature OLs (APC+), and the level of myelin basic protein (MBP); 3) decreased amyloid-β precursor protein (APP)+ density; 4) decreased neuroinflammation by increasing the M2 phenotype and decreasing the M1 phenotype of microglia, as well as their related cytokines; 5) inhibited the TLR2/IRAK1/NFκB pathway. Furthermore, we confirmed that the MSC-Exo treatment significantly improved cognitive function, promoted remyelination, increased polarization of M2 phenotype and blocked TLR2 signaling in the CPZ model. Collectively, MSC-Exo treatment promotes remyelination by both directly acting on OPCs and indirectly by acting on microglia in the demyelinating CNS. This study provides the cellular and molecular basis for this cell-free exosome therapy on remyelination and modulation of neuroinflammation in the CNS, with great potential for treatment of demyelinating and neurodegenerative disorders.

Nanosystems and exosomes as future approaches in treating multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system which leads to neurological dysfunctions and severe disabilities. MS pathology is characterised by damage of the blood-brain barrier and infiltration of autoreactive T cells that overactivate glial cells, thereby initiating neuroinflammation accompanied by the formation of demyelinating plaques and neurodegeneration. Clinical deficits in this multifactorial disease depend on the progression of myelin loss, the stage of inflammation, the status of axons and the activity of oligodendrocyte precursor cells (OPCs). Despite significant progress in the treatment of MS, current therapies remain limited and new approaches are highly desirable. Nanosystems based on liposomes and nanoparticles are among some of the more noteworthy therapeutic strategies being investigated. Applications of nanosystems alone or as drug carriers in animal models of MS have been found to successfully alleviate the symptoms of the disease and exert anti-inflammatory potential. Exosomes are a specific type of nanosystem based on nanometre-sized extracellular vesicles released by different cells which exhibit important healing features. Exosomes contain an array of anti-inflammatory and neuroprotective agents which may contribute to modulation of the immune system as well as promoting remyelination and tissue repair. In this review, opportunities to use nanosystems against progression of MS will be discussed in context of cell-specific pathologies associated with MS.

Astrocytic YAP prevents the demyelination through promoting expression of cholesterol synthesis genes in experimental autoimmune encephalomyelitis

Cholesterols are the main components of myelin, and are mainly synthesized in astrocytes and transported to oligodendrocytes and neurons in the adult brain. It has been reported that Hippo/yes-associated protein (YAP) pathways are involved in cholesterol synthesis in the liver, however, it remains unknown whether YAP signaling can prevent the demyelination through promoting cholesterol synthesis in experimental autoimmune encephalomyelitis (EAE), a commonly used animal model of multiple sclerosis characterized by neuroinflammation and demyelination. Here, we found that YAP was upregulated and activated in astrocytes of spinal cords of EAE mice through suppression of the Hippo pathway. YAP deletion in astrocytes aggravated EAE with earlier onset, severer inflammatory infiltration, demyelination, and more loss of neurons. Furthermore, we found that the neuroinflammation was aggravated and the proliferation of astrocytes was decreased in YAPGFAP-CKO EAE mice. Mechanically, RNA-seq revealed that the expression of cholesterol-synthesis pathway genes such as HMGCS1 were decreased in YAP−/− astrocytes. qPCR, western blot, and immunostaining further confirmed the more significant reduction of HMGCS1 in spinal cord astrocytes of YAPGFAP-CKO EAE mice. Interestingly, upregulation of cholesterol-synthesis pathways by diarylpropionitrile (DPN) (an ERβ-ligand, to upregulate the expression of HMGCS1) treatment partially rescued the demyelination deficits in YAPGFAP-CKO EAE mice. Finally, activation of YAP by XMU-MP-1 treatment promoted the expression of HMGCS1 in astrocytes and partially rescued the demyelination and inflammatory infiltration deficits in EAE mice. These findings identify unrecognized functions of astrocytic YAP in the prevention of demyelination through promoting cholesterol synthesis in EAE, and reveal a novel pathway of YAP/HMGCS1 for cholesterol synthesis in EAE pathology.

PRMT5 Promotes Symmetric Dimethylation of RNA Processing Proteins and Modulates Activated T Cell Alternative Splicing and Ca2+/NFAT Signaling.

Protein arginine methyltransferase (PRMT) 5 is the type 2 methyltransferase catalyzing symmetric dimethylation of arginine. PRMT5 inhibition or deletion in CD4 Th cells reduces TCR engagement-induced IL-2 production and Th cell expansion and confers protection against experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis. However, the mechanisms by which PRMT5 modulates Th cell proliferation are still not completely understood, and neither are the methylation targets in T cells. In this manuscript, we uncover the role of PRMT5 on alternative splicing in activated mouse T cells and identify several targets of PRMT5 symmetric dimethylation involved in splicing. In addition, we find a possible link between PRMT5-mediated alternative splicing of transient receptor potential cation channel subfamily M member 4 (Trpm4) and TCR/NFAT signaling/IL-2 production. This understanding may guide development of drugs targeting these processes to benefit patients with T cell-mediated diseases.