Experimental Autoimmune Encephalomyelitis in Mice

Wnt-Activated Immunoregulatory Myeloid Cells Prevent Relapse in Experimental Autoimmune Encephalomyelitis and Offer a Potential Therapeutic Strategy for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by recurrent inflammatory relapses and neurodegeneration. Myeloid cells play a critical role in shaping the inflammatory environment and influencing disease progression. Here, we demonstrate that activation of the Wnt signaling pathway reprograms myeloid cells into an immunoregulatory phenotype, leading to reduced neuroinflammation and disease severity. Using both experimental autoimmune encephalomyelitis (EAE) and human-derived myeloid cells, we show that Wnt agonist treatment promotes the expression of inhibitory molecules such as PD-L1 and PD-L2, suppressing pro-inflammatory responses. In the chronic and relapsing-remitting EAE models, Wnt activation significantly reduced disease severity, immune cell infiltration into the CNS, and pathogenic T cell responses. Notably, in relapsing-remitting EAE, Wnt treatment prevented new relapses in a PD-L1-dependent manner, highlighting the crucial role of myeloid cell-mediated immune regulation. These findings reveal a previously unrecognized role for Wnt signaling in myeloid cell immunoregulation and suggest that targeting this pathway could provide a novel therapeutic strategy for MS and other autoimmune diseases.

AAV1.NT3 gene therapy mitigates the severity of autoimmune encephalomyelitis in the mouse model for multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated chronic inflammatory and neurodegenerative disease of the central nervous system (CNS) affecting more than 2.5 million patients worldwide. Chronic demyelination in the CNS has an important role in perpetuating axonal loss and increases difficulty in promoting remyelination. Therefore, regenerative, and neuroprotective strategies are essential to overcome this impediment to rescue axonal integrity and function. Neurotrophin 3 (NT-3) has immunomodulatory and anti-inflammatory properties, in addition to its well-recognized function in nervous system development, myelination, neuroprotection, and regeneration. For this study, scAAV1.tMCK.NT-3 was delivered to the gastrocnemius muscle of experimental autoimmune encephalomyelitis (EAE) mice, the chronic relapsing mouse model of MS, at 3 weeks post EAE induction. Measurable NT-3 levels were found in serum at 7-weeks post gene delivery. The treated cohort showed improved clinical scores and performed significantly better in rotarod, and grip strength tests compared to their untreated counterparts. Histopathologic studies showed improved remyelination and axon protection. These data correlated with reduced expression of the pro-inflammatory cytokines in brain and spinal cord, and increased percentage of regulatory T cells in the spleens and lymph nodes. Collectively, these findings demonstrate the translational potential of AAV-delivered NT-3 for chronic progressive MS.

Dosage and organic acid residue of myelin oligodendrocyte glycoprotein35-55 peptide influences immunopathology and development of Bacillus Calmette-Guérin induced experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) serves as a model for studying multiple sclerosis, with immunization strategies utilizing myelin oligodendrocyte glycoprotein (MOG)35-55 peptide, emulsified in adjuvant enriched with Mycobacterium tuberculosis (Mtb). This study examined the effects of Bacillus Calmette-Guérin (BCG) as an adjuvant, alongside the impact of MOG35-55 peptide doses and their residual counter ions on EAE development. We found that BCG can be effectively used to induce EAE with similar incidence and severity as heat-killed H37Ra, contingent upon the appropriate MOG35-55 peptide dose. Different immunization doses of MOG35-55 peptide significantly affect EAE development, with higher doses leading to a paradoxical reduction in disease activity, probably due to peripheral tolerance mechanisms. Furthermore, doses of MOG35-55 peptides with acetate showed a more pronounced effect on disease development compared to those containing trifluoroacetic acid (TFA), suggesting the potential influence of residual counter ions on EAE activity. We highlighted the feasibility of applying BCG to the establishment of EAE for the first time. Our findings emphasized the importance of MOG35-55 peptide dosage and composition in modulating EAE development, offering insights into the mechanisms of autoimmunity and tolerance. This could have implications for autoimmune disease research and the design of therapeutic strategies.

A diet-dependent host metabolite shapes the gut microbiota to protect from autoimmunity

Diet can protect from autoimmune disease; however, whether diet acts via the host and/or microbiome remains unclear. Here, we use a ketogenic diet (KD) as a model to dissect these complex interactions. A KD rescued the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis in a microbiota-dependent fashion. Dietary supplementation with a single KD-dependent host metabolite (β-hydroxybutyrate [βHB]) rescued EAE, whereas transgenic mice unable to produce βHB in the intestine developed more severe disease. Transplantation of the βHB-shaped gut microbiota was protective. Lactobacillus sequence variants were associated with decreased T helper 17 cell activation in vitro. Finally, we isolated an L. murinus strain that protected from EAE, which was phenocopied by a Lactobacillus metabolite enriched by βHB supplementation, indole lactate. Thus, diet alters the immunomodulatory potential of the gut microbiota by shifting host metabolism, emphasizing the utility of taking a more integrative approach to study diet-host-microbiome interactions.

The Smoothened agonist SAG Modulates the Male and Female Peripheral Immune Systems Differently in an Immune Model of Central Nervous System Demyelination

Both Hedgehog and androgen signaling pathways are known to promote myelin regeneration in the central nervous system. Remarkably, the combined administration of agonists of each pathway revealed their functional cooperation towards higher regeneration in demyelination models in males. Since multiple sclerosis, the most common demyelinating disease, predominates in women, and androgen effects were reported to diverge according to sex, it seemed essential to assess the existence of such cooperation in females. Here, we developed an intranasal formulation containing the Hedgehog signaling agonist SAG, either alone or in combination with testosterone. We show that SAG promotes myelin regeneration and presumably a pro-regenerative phenotype of microglia, thus mimicking the effects previously observed in males. However, unlike in males, the combined molecules failed to cooperate in the demyelinated females, as shown by the level of functional improvement observed. Consistent with this observation, SAG administered in the absence of testosterone amplified peripheral inflammation by presumably activating NK cells and thus counteracting a testosterone-induced reduction in Th17 cells when the molecules were combined. Altogether, the data uncover a sex-dependent effect of the Hedgehog signaling agonist SAG on the peripheral innate immune system that conditions its ability to cooperate or not with androgens in the context of demyelination.

Active Induction of a Multiple Sclerosis-Like Disease in Common Laboratory Mouse Strains

Experimental autoimmune encephalomyelitis (EAE) is a neuroinflammatory disease with facets in common with multiple sclerosis (MS). It is induced in susceptible mammalian species, with rodents as the preferred hosts, and has been used for decades as a model to investigate the immunopathogenesis of MS as well as for preclinical evaluation of candidate MS therapeutics. Most commonly, EAE is generated by active immunization with central nervous system (CNS) antigens, such as whole CNS homogenate, myelin proteins, or peptides derived from these proteins. However, EAE actually represents a spectrum of diseases in which specific combinations of host/CNS antigen exhibit defined clinical profiles, each associated with unique immunological and pathological features. Similar to MS, EAE is a complex disease where development and progression are also modulated by environmental factors; therefore, the establishment of any given EAE variant can be challenging and requires careful optimization. Here, we describe protocols for three EAE variants, successfully generated in our laboratory, and provide additional information as to how to maintain their unique features and reproducibility.

Effects of Five Coumarins and Standardized Extracts from Tagetes lucida Cav. on Motor Impairment and Neuroinflammation Induced with Cuprizone

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) with no curative treatment, and the available therapies aim to modify the course of the disease. It has been demonstrated that extracts of Tagetes lucida have immunomodulatory and neuroprotective effects. This work induced motor damage and neuroinflammation in male BALB/c mice by oral administration of cuprizone (CPZ) (40 mg/kg) for five weeks. In addition, the extracts and coumarins of Tagetes lucida (25 mg/kg) were used to control these damage variables; during the experiment, animals were subject to behavioral tests, and at the end of 5 weeks, mice from each group were used to measure the integrity of biological barriers (brain, kidneys, and spleen) through the extravasation test with blue Evans dye. In another group of animals, the ELISA method measured the brain concentrations of IL-1β, IL-4, IL-10, and TNF-α. The results presented here allow us to conclude that the extracts and coumarins IC, HN, PE, DF, and SC of Tagetes lucida exert a neuroprotective effect by controlling the motor damage and neuroinflammation by increasing the expression of IL-4 and IL-10 and decreasing IL-1β and TNF-α; notably, these treatments also protect organs from vascular permeability increase, mainly the BBB, in mice with CPZ-induced experimental encephalomyelitis (VEH * p < 0.05). However, more studies must be carried out to elucidate the molecular mechanisms of the pharmacological effects of this Mexican medicinal plant.

Proteolipid Protein-Induced Mouse Model of Multiple Sclerosis Requires B Cell-Mediated Antigen Presentation

The pathogenic role B cells play in multiple sclerosis is underscored by the success of B cell depletion therapies. Yet, it remains unclear how B cells contribute to disease, although it is increasingly accepted that mechanisms beyond Ab production are involved. Better understanding of pathogenic interactions between B cells and autoreactive CD4 T cells will be critical for novel therapeutics. To focus the investigation on B cell:CD4 T cell interactions in vivo and in vitro, we previously developed a B cell-dependent, Ab-independent experimental autoimmune encephalomyelitis (EAE) mouse model driven by a peptide encompassing the extracellular domains of myelin proteolipid protein (PLPECD). In this study, we demonstrate that B cell depletion significantly inhibited PLPECD-induced EAE disease, blunted PLPECD-elicited delayed-type hypersensitivity reactions in vivo, and reduced CD4 T cell activation, proliferation, and proinflammatory cytokine production. Further, PLPECD-reactive CD4 T cells sourced from B cell-depleted donor mice failed to transfer EAE to naive recipients. Importantly, we identified B cell-mediated Ag presentation as the critical mechanism explaining B cell dependence in PLPECD-induced EAE, where bone marrow chimeric mice harboring a B cell-restricted MHC class II deficiency failed to develop EAE. B cells were ultimately observed to restimulate significantly higher Ag-specific proliferation from PLP178-191-reactive CD4 T cells compared with dendritic cells when provided PLPECD peptide in head-to-head cultures. We therefore conclude that PLPECD-induced EAE features a required pathogenic B cell-mediated Ag presentation function, providing for investigable B cell:CD4 T cell interactions in the context of autoimmune demyelinating disease.

Anti-Glycolipid Antibody Examination in Five EAE Models and Theiler's Virus Model of Multiple Sclerosis: Detection of Anti-GM1, GM3, GM4, and Sulfatide Antibodies in Relapsing-Remitting EAE

Anti-glycolipid antibodies have been reported to play pathogenic roles in peripheral inflammatory neuropathies, such as Guillain-Barré syndrome. On the other hand, the role in multiple sclerosis (MS), inflammatory demyelinating disease in the central nervous system (CNS), is largely unknown, although the presence of anti-glycolipid antibodies was reported to differ among MS patients with relapsing-remitting (RR), primary progressive (PP), and secondary progressive (SP) disease courses. We investigated whether the induction of anti-glycolipid antibodies could differ among experimental MS models with distinct clinical courses, depending on induction methods. Using three mouse strains, SJL/J, C57BL/6, and A.SW mice, we induced five distinct experimental autoimmune encephalomyelitis (EAE) models with myelin oligodendrocyte glycoprotein (MOG)35-55, MOG92-106, or myelin proteolipid protein (PLP)139-151, with or without an additional adjuvant curdlan injection. We also induced a viral model of MS, using Theiler's murine encephalomyelitis virus (TMEV). Each MS model had an RR, SP, PP, hyperacute, or chronic clinical course. Using the sera from the MS models, we quantified antibodies against 11 glycolipids: GM1, GM2, GM3, GM4, GD3, galactocerebroside, GD1a, GD1b, GT1b, GQ1b, and sulfatide. Among the MS models, we detected significant increases in four anti-glycolipid antibodies, GM1, GM3, GM4, and sulfatide, in PLP139-151-induced EAE with an RR disease course. We also tested cellular immune responses to the glycolipids and found CD1d-independent lymphoproliferative responses only to sulfatide with decreased interleukin (IL)-10 production. Although these results implied that anti-glycolipid antibodies might play a role in remissions or relapses in RR-EAE, their functional roles need to be determined by mechanistic experiments, such as injections of monoclonal anti-glycolipid antibodies.

Role of the CXCR6/CXCL16 axis in autoimmune diseases

The C-X-C motif ligand 16, or CXCL16, is a chemokine that belongs to the ELR - CXC subfamily. Its function is to bind to the chemokine receptor CXCR6, which is a G protein-coupled receptor with 7 transmembrane domains. The CXCR6/CXCL16 axis has been linked to the development of numerous autoimmune diseases and is connected to clinical parameters that reflect disease severity, activity, and prognosis in conditions such as multiple sclerosis, autoimmune hepatitis, rheumatoid arthritis, Crohn's disease, and psoriasis. CXCL16 is expressed in various immune cells, such as dendritic cells, monocytes, macrophages, and B cells. During autoimmune diseases, CXCL16 can facilitate the adhesion of immune cells like monocytes, T cells, NKT cells, and others to endothelial cells and dendritic cells. Additionally, sCXCL16 can regulate the migration of CXCR6-expressing leukocytes, which includes CD8⁺ T cells, CD4⁺ T cells, NK cells, constant natural killer T cells, plasma cells, and monocytes. Further investigation is required to comprehend the intricate interactions between chemokines and the pathogenesis of autoimmune diseases. It remains to be seen whether the CXCR6/CXCL16 axis represents a new target for the treatment of these conditions.

Androgens show sex-dependent differences in myelination in immune and non-immune murine models of CNS demyelination

Neuroprotective, anti-inflammatory, and remyelinating properties of androgens are well-characterized in demyelinated male mice and men suffering from multiple sclerosis. However, androgen effects mediated by the androgen receptor (AR), have been only poorly studied in females who make low androgen levels. Here, we show a predominant microglial AR expression in demyelinated lesions from female mice and women with multiple sclerosis, but virtually undetectable AR expression in lesions from male animals and men with multiple sclerosis. In female mice, androgens and estrogens act in a synergistic way while androgens drive microglia response towards regeneration. Transcriptomic comparisons of demyelinated mouse spinal cords indicate that, regardless of the sex, androgens up-regulate genes related to neuronal function integrity and myelin production. Depending on the sex, androgens down-regulate genes related to the immune system in females and lipid catabolism in males. Thus, androgens are required for proper myelin regeneration in females and therapeutic approaches of demyelinating diseases need to consider male-female differences.

Suppression of MAPK/NF-kB and activation of Nrf2 signaling by Ajugarin-I in EAE model of multiple sclerosis

Multiple sclerosis (MS) is a debilitating neurodegenerative autoimmune disease of the central nervous system (CNS). The current study aimed to investigate the neuroprotective properties of Ajugarin-I (Aju-I) against the experimental autoimmune encephalomyelitis (EAE) model of MS and explored the underlying mechanism involved. The protective potential of Aju-I was first confirmed against glutamate-induced HT22 cells and hydrogen peroxide (H₂ O₂ )-induced BV2 cells. Next, an EAE model has been established to investigate the mechanisms of MS and identify potential candidates for MS treatment. The behavioral results demonstrated that Aju-I post-immunization treatment markedly reduced the EAE-associated clinical score, motor impairment, and neuropathic pain. Evans blue and fluorescein isothiocyanate extravasation in the brain were markedly reduced by Aju-I. It effectively restored the EAE-associated histopathological changes in the brain and spinal cord. It markedly attenuated EAE-induced inflammation in the CNS by reducing the expression levels of p-38/JNK/NF-κB but increased the expression of IkB-α. It suppressed oxidative stress by increasing the expression of Nrf2 but decreasing the expression of keap-1. It suppressed EAE-induced apoptosis in the CNS by regulating Bax/Bcl-2 and Caspase-3 expression. Taken together, this study suggests that Aju-I treatment exhibits neuroprotective properties in the EAE model of MS via regulation of MAPK/NF-κB, Nrf2/Keap-1, and Bcl2/Bax signaling.

T-cell infiltration in the central nervous system and their association with brain calcification in Slc20a2-deficient mice

Primary familial brain calcification (PFBC) is a rare neurodegenerative and neuropsychiatric disorder characterized by bilateral symmetric intracranial calcification along the microvessels or inside neuronal cells in the basal ganglia, thalamus, and cerebellum. Slc20a2 homozygous (HO) knockout mice are the most commonly used model to simulate the brain calcification phenotype observed in human patients. However, the cellular and molecular mechanisms related to brain calcification, particularly at the early stage much prior to the emergence of brain calcification, remain largely unknown. In this study, we quantified the central nervous system (CNS)-infiltrating T-cells of different age groups of Slc20a2-HO and matched wild type mice and found CD45⁺CD3⁺ T-cells to be significantly increased in the brain parenchyma, even in the pre-calcification stage of 1-month-old -HO mice. The accumulation of the CD3⁺ T-cells appeared to be associated with the severity of brain calcification. Further immunophenotyping revealed that the two main subtypes that had increased in the brain were CD3⁺ CD4^- CD8^- and CD3⁺ CD4⁺ T-cells. The expression of endothelial cell (EC) adhesion molecules increased, while that of tight and adherents junction proteins decreased, providing the molecular precondition for T-cell recruitment to ECs and paracellular migration into the brain. The fusion of lymphocytes and EC membranes and transcellular migration of CD3-related gold particles were captured, suggesting enhancement of transcytosis in the brain ECs. Exogenous fluorescent tracers and endogenous IgG and albumin leakage also revealed an impairment of transcellular pathway in the ECs. FTY720 significantly alleviated brain calcification, probably by reducing T-cell infiltration, modulating neuroinflammation and ossification process, and enhancing the autophagy and phagocytosis of CNS-resident immune cells. This study clearly demonstrated CNS-infiltrating T-cells to be associated with the progression of brain calcification. Impairment of blood-brain barrier (BBB) permeability, which was closely related to T-cell invasion into the CNS, could be explained by the BBB alterations of an increase in the paracellular and transcellular pathways of brain ECs. FTY720 was found to be a potential drug to protect patients from PFBC-related lesions in the future.

Repurposing the cardiac glycoside digoxin to stimulate myelin regeneration in chemically-induced and immune-mediated mouse models of multiple sclerosis

Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune disease characterized by inflammation, demyelination, and neurodegeneration. The ideal MS therapy would both specifically inhibit the underlying autoimmune response and promote repair/regeneration of myelin as well as maintenance of axonal integrity. Currently approved MS therapies consist of non-specific immunosuppressive molecules/antibodies which block activation or CNS homing of autoreactive T cells, but there are no approved therapies for stimulation of remyelination nor maintenance of axonal integrity. In an effort to repurpose an FDA-approved medication for myelin repair, we chose to examine the effectiveness of digoxin, a cardiac glycoside (Na+ /K+ ATPase inhibitor), originally identified as pro-myelinating in an in vitro screen. We found that digoxin regulated multiple genes in oligodendrocyte progenitor cells (OPCs) essential for oligodendrocyte (OL) differentiation in vitro, promoted OL differentiation both in vitro and in vivo in female naïve C57BL/6J (B6) mice, and stimulated recovery of myelinated axons in B6 mice following demyelination in the corpus callosum induced by cuprizone and spinal cord demyelination induced by lysophosphatidylcholine (LPC), respectively. More relevant to treatment of MS, we show that digoxin treatment of mice with established MOG35-55 -induced Th1/Th17-mediated chronic EAE combined with tolerance induced by the i.v. infusion of biodegradable poly(lactide-co-glycolide) nanoparticles coupled with MOG35-55 (PLG-MOG35-55 ) completely ameliorated clinical disease symptoms and stimulated recovery of OL lineage cell numbers. These findings provide critical pre-clinical evidence supporting future clinical trials of myelin-specific tolerance with myelin repair/regeneration drugs, such as digoxin, in MS patients.

Whole Exome Sequencing in Multi-Incident Families Identifies Novel Candidate Genes for Multiple Sclerosis

Multiple sclerosis (MS) is a degenerative disease of the central nervous system in which auto-immunity-induced demyelination occurs. MS is thought to be caused by a complex interplay of environmental and genetic risk factors. While most genetic studies have focused on identifying common genetic variants for MS through genome-wide association studies, the objective of the present study was to identify rare genetic variants contributing to MS susceptibility. We used whole exome sequencing (WES) followed by co-segregation analyses in nine multi-incident families with two to four affected individuals. WES was performed in 31 family members with and without MS. After applying a suite of selection criteria, co-segregation analyses for a number of rare variants selected from the WES results were performed, adding 24 family members. This approach resulted in 12 exonic rare variants that showed acceptable co-segregation with MS within the nine families, implicating the genes MBP, PLK1, MECP2, MTMR7, TOX3, CPT1A, SORCS1, TRIM66, ITPR3, TTC28, CACNA1F, and PRAM1. Of these, three genes (MBP, MECP2, and CPT1A) have been previously reported as carrying MS-related rare variants. Six additional genes (MTMR7, TOX3, SORCS1, ITPR3, TTC28, and PRAM1) have also been implicated in MS through common genetic variants. The proteins encoded by all twelve genes containing rare variants interact in a molecular framework that points to biological processes involved in (de-/re-)myelination and auto-immunity. Our approach provides clues to possible molecular mechanisms underlying MS that should be studied further in cellular and/or animal models.

Nanoformulated Recombinant Human Myelin Basic Protein and Rituximab Modulate Neuronal Perturbations in Experimental Autoimmune Encephalomyelitis in Mice

Introduction

Rituximab (RTX) and recombinant human myelin basic protein (rhMBP) were proven to be effective in ameliorating the symptoms of multiple sclerosis (MS). In this study, a nanoformulation containing rhMBP with RTX on its surface (Nano-rhMBP-RTX) was prepared and investigated in comparison with other treatment groups to determine its potential neuro-protective effects on C57BL/6 mice after inducing experimental autoimmune encephalomyelitis (EAE).

Methods

EAE was induced in the corresponding mice by injecting 100 μL of an emulsion containing complete Freund's adjuvant (CFA) and myelin oligodendrocyte glycoprotein (MOG). The subjects were weighed, scored and subjected to behavioural tests. After reaching a clinical score of 3, various treatments were given to corresponding EAE-induced and non-induced groups including rhMBP, RTX, empty nanoparticle prepared by poly (lactide-co-glycolide) (PLGA) or the prepared nanoformulation (Nano-rhMBP-RTX). At the end of the study, biochemical parameters were also determined as interferon-γ (IFN-γ), myeloperoxidase (MPO), interleukin-10 (IL-10), interleukin-4 (IL-4), tumor necrosis factor alpha (TNF-α), nuclear factor kappa B (NF-kB), brain derived neurotrophic factor (BDNF), 2', 3' cyclic nucleotide 3' phosphodiesterase (CNP) and transforming growth factor beta (TGF-β) along with some histopathological analyses.

Results

The results of the Nano-rhMBP-RTX group showed promising outcomes in terms of reducing the clinical scores, improving the behavioural responses associated with improved histopathological findings. Elevation in the levels of IL-4, CNP and TGF-β was also noticed along with marked decline in the levels of NF-kB and TNF-α.

Conclusion

Nano-rhMBP-RTX treated group ameliorated the adverse effects induced in the EAE model. The effectiveness of this formulation was demonstrated by the normalization of EAE-induced behavioral changes and aberrant levels of specific biochemical markers as well as reduced damage of hippocampal tissues and retaining higher levels of myelination.

Neurodegenerative Disorders of Alzheimer, Parkinsonism, Amyotrophic Lateral Sclerosis and Multiple Sclerosis: An Early Diagnostic Approach for Precision Treatment

Neurodegenerative diseases (NDs) are characterised by progressive dysfunction of synapses, neurons, glial cells and their networks. Neurodegenerative diseases can be classified according to primary clinical features (e.g., dementia, parkinsonism, or motor neuron disease), anatomic distribution of neurodegeneration (e.g., frontotemporal degenerations, extrapyramidal disorders, or spinocerebellar degenerations), or principal molecular abnormalities. The most common neurodegenerative disorders are amyloidosis, tauopathies, a-synucleinopathy, and TAR DNA-binding protein 43 (TDP-43) proteopathy. The protein abnormalities in these disorders have abnormal conformational properties along with altered cellular mechanisms, and they exhibit motor deficit, mitochondrial malfunction, dysfunctions in autophagic-lysosomal pathways, synaptic toxicity, and more emerging mechanisms such as the roles of stress granule pathways and liquid-phase transitions. Finally, for each ND, microglial cells have been reported to be implicated in neurodegeneration, in particular, because the microglial responses can shift from neuroprotective to a deleterious role. Growing experimental evidence suggests that abnormal protein conformers act as seed material for oligomerization, spreading from cell to cell through anatomically connected neuronal pathways, which may in part explain the specific anatomical patterns observed in brain autopsy sample. In this review, we mention the human pathology of select neurodegenerative disorders, focusing on how neurodegenerative disorders (i.e., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis) represent a great healthcare problem worldwide and are becoming prevalent because of the increasing aged population. Despite many studies have focused on their etiopathology, the exact cause of these diseases is still largely unknown and until now with the only available option of symptomatic treatments. In this review, we aim to report the systematic and clinically correlated potential biomarker candidates. Although future studies are necessary for their use in early detection and progression in humans affected by NDs, the promising results obtained by several groups leads us to this idea that biomarkers could be used to design a potential therapeutic approach and preclinical clinical trials for the treatments of NDs.

Mouse Homologue of Human HLA-DO Does Not Preempt Autoimmunity but Controls Murine Gammaherpesvirus MHV68

H2-O (human HLA-DO) is a relatively conserved nonclassical MHC class II (MHCII)-like molecule. H2-O interaction with human HLA-DM edits the repertoire of peptides presented to TCRs by MHCII. It was long hypothesized that human HLA-DM inhibition by H2-O provides protection from autoimmunity by preventing binding of the high-affinity self-peptides to MHCII. The available evidence supporting this hypothesis, however, was inconclusive. A possibility still remained that the effect of H2-O deficiency on autoimmunity could be better revealed by using H2-O-deficient mice that were already genetically predisposed to autoimmunity. In this study, we generated and used autoimmunity-prone mouse models for systemic lupus erythematosus and organ-specific autoimmunity (type 1 diabetes and multiple sclerosis) to definitively test whether H2-O prevents autoimmune pathology. Whereas our data failed to support any significance of H2-O in protection from autoimmunity, we found that it was critical for controlling a γ-herpesvirus, MHV68. Thus, we propose that H2-O editing of the MHCII peptide repertoire may have evolved as a safeguard against specific highly prevalent viral pathogens.

Withametelin, a novel phytosterol, alleviates neurological symptoms in EAE mouse model of multiple sclerosis via modulation of Nrf2/HO-1 and TLR4/NF-κB signaling

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disorder of the central nervous system (CNS) that remains incurable. Withametelin (WMT), a phytosterol, showed diverse biological activities isolated from the leaves of Datura innoxa. In the present study, we used an in vitro model of HT22 and BV-2 cell lines and an in vivo murine model of MS, experimental autoimmune encephalomyelitis (EAE), to explore the antioxidant and anti neuroinflammatory potential of WMT. The results showed that pretreatment with WMT markedly inhibited H2O2-induced cytotoxicity and oxidative stress in a dose-dependent manner. Correspondingly, WMT post-immunization treatment significantly attenuated EAE-induced clinical score, weight loss, neuropathic pain behaviors, and motor dysfunction. It markedly lowers EAE-induced elevated circulating leucocytes, spinal deformity, and splenomegaly. It strikingly inhibited the Evans blue and FITC extravasation in the brain. It remarkably reversed the EAE-induced histopathological alteration of the brain, spinal cord, eye, and optic nerve. It significantly intensified the antioxidant defense mechanism by improving the expression level of nuclear factor-erythroid-related factor-2 (Nrf2), heme-oxygenase-1 (HO-1) but reducing the expression level of the Kelch-like-ECH-associated-protein-1 (keap-1), inducible-nitric-oxide-synthase (iNOS) in the CNS. Likewise, it markedly suppressed neuroinflammation by reducing the expression level of toll-like-receptor 4 (TLR4), nuclear-factor-kappa-B (NF-κB), activator-protein-1 (AP-1) but increased the expression level IkB-α in the CNS. Furthermore, molecular dynamics simulations and MMPBSA binding free energies were determined to validate the dynamic stability of complexes and shed light on the atomic level intermolecular interaction energies. Taken together, this study showed that WMT has significant neuroprotective potential in EAE via modulation of Nrf2 mediated-oxidative stress and NF-κB mediated inflammation.

A novel fatty acid-binding protein 5 and 7 inhibitor ameliorates oligodendrocyte injury in multiple sclerosis mouse models

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease characterised by the demyelination of mature oligodendrocytes in the central nervous system. Recently, several studies have indicated the vital roles of fatty acid-binding proteins (FABPs) 5 and 7 in regulating the immune response.

METHODS

We assessed a novel FABP5/FABP7 inhibitor, FABP ligand 6 (MF 6), as a potential therapeutic for MS therapy. In vivo, we established MOG_35-55-administered experimental autoimmune encephalomyelitis (EAE) mice as an MS mouse model, followed by prophylactic and symptomatic treatment with MF 6. The therapeutic effect of MF 6 was determined using behavioural and biochemical analyses. In vitro, MF 6 effects on astrocytes and oligodendrocytes were examined using both astrocyte primary culture and KG-1C cell lines.

FINDINGS

Prophylactic and symptomatic MF 6 therapy reduced myelin loss and clinical EAE symptoms. Furthermore, oxidative stress levels and GFAP-positive and ionised calcium-binding adaptor protein-1-positive cells were reduced in the spinal cord of MF 6-treated mice. In addition, MF 6 attenuated lipopolysaccharide-stimulated interleukin-1β and tumour necrosis factor-α accumulation in primary astrocyte culture. Moreover, MF 6 indicated a powerful protective function for the mitochondria in the oligodendrocytes of EAE mice via FABP5 inhibition.

INTERPRETATIONS

MF 6 is a potent inhibitor of FABP5 and FABP7; targeted inhibition of the two proteins may confer potential therapeutic effects in MS via immune inhibition and oligodendrocyte protection.

FUNDING

This work was supported by the Strategic Research Program for Brain Sciences from the Japan Agency for Medical Research and Development (JP17dm0107071, JP18dm0107071, JP19dm0107071, and JP20dm0107071).

Pericytes regulate vascular immune homeostasis in the CNS

The CNS vasculature tightly regulates the passage of circulating molecules and leukocytes into the CNS. In the neuroinflammatory disease multiple sclerosis (MS), these regulatory mechanisms fail, and autoreactive T cells invade the CNS via blood vessels, leading to neurological deficits depending on where the lesions are located. The region-specific mechanisms directing the development of such lesions are not well understood. In this study, we investigated whether pericytes regulate CNS endothelial cell permissiveness toward leukocyte trafficking into the brain parenchyma. By using a pericyte-deficient mouse model, we show that intrinsic changes in the brain vasculature due to absence of pericytes facilitate the neuroinflammatory cascade and can influence the localization of the neuroinflammatory lesions.

Pericytes regulate the development of organ-specific characteristics of the brain vasculature such as the blood–brain barrier (BBB) and astrocytic end-feet. Whether pericytes are involved in the control of leukocyte trafficking in the adult central nervous system (CNS), a process tightly regulated by CNS vasculature, remains elusive. Using adult pericyte-deficient mice (Pdgfb^ret/ret), we show that pericytes limit leukocyte infiltration into the CNS during homeostasis and autoimmune neuroinflammation. The permissiveness of the vasculature toward leukocyte trafficking in Pdgfb^ret/ret mice inversely correlates with vessel pericyte coverage. Upon induction of experimental autoimmune encephalomyelitis (EAE), pericyte-deficient mice die of severe atypical EAE, which can be reversed with fingolimod, indicating that the mortality is due to the massive influx of immune cells into the brain. Additionally, administration of anti-VCAM-1 and anti–ICAM-1 antibodies reduces leukocyte infiltration and diminishes the severity of atypical EAE symptoms of Pdgfb^ret/ret mice, indicating that the proinflammatory endothelium due to absence of pericytes facilitates exaggerated neuroinflammation. Furthermore, we show that the presence of myelin peptide-specific peripheral T cells in Pdgfb^ret/ret;2D2^tg mice leads to the development of spontaneous neurological symptoms paralleled by the massive influx of leukocytes into the brain. These findings indicate that intrinsic changes within brain vasculature can promote the development of a neuroinflammatory disorder.

Activation of Transcription Factor 4 in Dendritic Cells Controls Th1/Th17 Responses and Autoimmune Neuroinflammation

Dendritic cells (DCs) are professional APCs that play a crucial role in initiating robust immune responses against invading pathogens while inducing regulatory responses to the body's tissues and commensal microorganisms. A breakdown of DC-mediated immunological tolerance leads to chronic inflammation and autoimmune disorders. However, cell-intrinsic molecular regulators that are critical for programming DCs to a regulatory state rather than to an inflammatory state are not known. In this study, we show that the activation of the TCF4 transcription factor in DCs is critical for controlling the magnitude of inflammatory responses and limiting neuroinflammation. DC-specific deletion of TCF4 in mice increased Th1/Th17 responses and exacerbated experimental autoimmune encephalomyelitis pathology. Mechanistically, loss of TCF4 in DCs led to heightened activation of p38 MAPK and increased levels of proinflammatory cytokines IL-6, IL-23, IL-1β, TNF-α, and IL-12p40. Consistent with these findings, pharmacological blocking of p38 MAPK activation delayed experimental autoimmune encephalomyelitis onset and diminished CNS pathology in TCF4^ΔDC mice. Thus, manipulation of the TCF4 pathway in DCs could provide novel opportunities for regulating chronic inflammation and represents a potential therapeutic approach to control autoimmune neuroinflammation.

Strain and sex differences in somatosensation and sociability during experimental autoimmune encephalomyelitis

Multiple Sclerosis (MS) is an immune-mediated disease that results in major locomotor deficits. However, recent studies have revealed that fatigue, slow processing speed, and memory impairment are the top variables impacting employment status for MS patients. These suggest that cognitive effects may have a greater impact on productivity, lifestyle, and quality of life than do disease-related motor deficits. However, these debilitating non-locomotive effects have been largely overlooked in rodent models of the disease, such as experimental autoimmune encephalomyelitis (EAE). We hypothesized that murine EAE can also be used to assess non-locomotive dysfunctions (mood, sociability, muscle strength, and balance), as well as potential biases in these dysfunctions due to sex and/or strain. We actively immunized male and female C57BL/6 (B6) and SJL mice for EAE and evaluated their performance on the Deacon's weight grip test, Kondziela's inverted screen test, Hall's rope grip test, manual von Frey test for somatic nociception, and a three-chamber social preference paradigm. We hypothesized that EAE progression is associated with changes in muscle strength, balance, pain, and sociability and that these variations are linked to sex and/or strain. Our results indicate that strain but not sex influenced differences in muscle strength and balance during EAE, and both sex and strain have an impact on mechanical nociception, regardless of EAE disease status. Furthermore, both sex and strain had complex effects on differences in sociability. In conclusion, testing these additional modalities during EAE helps to unveil other signs and symptoms that could be used to determine the efficacy of a drug or treatment in the modulation of a MS-like behavior.

Meningeal B Cell Clusters Correlate with Submeningeal Pathology in a Natural Model of Multiple Sclerosis

Multiple sclerosis (MS) is an idiopathic demyelinating disease in which meningeal inflammation correlates with accelerated disease progression. The study of meningeal inflammation in MS has been limited because of constrained access to MS brain/spinal cord specimens and the lack of experimental models recapitulating progressive MS. Unlike induced models, a spontaneously occurring model would offer a unique opportunity to understand MS immunopathogenesis and provide a compelling framework for translational research. We propose granulomatous meningoencephalomyelitis (GME) as a natural model to study neuropathological aspects of MS. GME is an idiopathic, progressive neuroinflammatory disease of young dogs with a female bias. In the GME cases examined in this study, the meninges displayed focal and disseminated leptomeningeal enhancement on magnetic resonance imaging, which correlated with heavy leptomeningeal lymphocytic infiltration. These leptomeningeal infiltrates resembled tertiary lymphoid organs containing large B cell clusters that included few proliferating Ki67+ cells, plasma cells, follicular dendritic/reticular cells, and germinal center B cell-like cells. These B cell collections were confined in a specialized network of collagen fibers associated with the expression of the lympho-organogenic chemokines CXCL13 and CCL21. Although neuroparenchymal perivascular infiltrates contained B cells, they lacked the immune signature of aggregates in the meningeal compartment. Finally, meningeal B cell accumulation correlated significantly with cortical demyelination reflecting neuropathological similarities to MS. Hence, during chronic neuroinflammation, the meningeal microenvironment sustains B cell accumulation that is accompanied by underlying neuroparenchymal injury, indicating GME as a novel, naturally occurring model to study compartmentalized neuroinflammation and the associated pathology thought to contribute to progressive MS.

Functional cooperation of the hedgehog and androgen signaling pathways during developmental and repairing myelination

Hedgehog morphogens control fundamental cellular processes during tissue development and regeneration. In the central nervous system (CNS), Hedgehog signaling has been implicated in oligodendrocyte and myelin production, where it functions in a concerted manner with other pathways. Since androgen receptor (AR) plays a key role in establishing the sexual phenotype of myelin during development and is required for spontaneous myelin regeneration in the adult CNS, we hypothesized the existence of a possible coordination between Hedgehog and androgen signals in oligodendrocyte and myelin production. Here, we report complementary activities of both pathways during early postnatal oligodendrogenesis further revealing that persistent Hedgehog signaling activation impedes myelin production. The data also uncover prominent pro-myelinating activity of testosterone and involvement of AR in the control of neural stem cell commitment toward the oligodendroglial lineage. In the context of CNS demyelination, we provide evidence for the functional cooperation of the pathways leading to acceleration of myelin regeneration that might be related to their respective role on microglial and astroglial responses, higher preservation of axonal integrity, lower neuroinflammation, and functional improvement of animals in an immune model of CNS demyelination. Strong decreases of deleterious cytokines in the CNS (GM-CSF, TNF-α, IL-17A) and spleen (IL-2, IFN-γ) stand as unique features of the combined drugs while the potent therapeutic activity of testosterone on peripheral immune cells contributes to increase tolerogenic CD11c⁺ dendritic cells, reduce the clonal expansion of conventional CD4⁺ T cells and increase CD4⁺ Foxp3⁺ regulatory T cells. Altogether, these data might open promising perspectives for demyelinating diseases.

Genomic, proteomic, and systems biology approaches in biomarker discovery for multiple sclerosis

Multiple sclerosis (MS) is a neuroinflammatory disorder characterized by autoimmune-mediated inflammatory lesions in CNS leading to myelin damage and axonal loss. MS is a heterogenous disease with variable and unpredictable disease course. Due to its complex nature, MS is difficult to diagnose and responses to specific treatments may vary between individuals. Therefore, there is an indisputable need for biomarkers for early diagnosis, prediction of disease exacerbations, monitoring the progression of disease, and for measuring responses to therapy. Genomic and proteomic studies have sought to understand the molecular basis of MS and find biomarker candidates. Advances in next-generation sequencing and mass-spectrometry techniques have yielded an unprecedented amount of genomic and proteomic data; yet, translation of the results into the clinic has been underwhelming. This has prompted the development of novel data science techniques for exploring these large datasets to identify biologically relevant relationships and ultimately point towards useful biomarkers. Herein we discuss optimization of omics study designs, advances in the generation of omics data, and systems biology approaches aimed at improving biomarker discovery and translation to the clinic for MS.

Should mast cells be considered therapeutic targets in multiple sclerosis?

Mast cells are immune cells of the myeloid lineage that are found throughout the body, including the central nervous system. They perform many functions associated with innate and specific immunity, angiogenesis, and vascular homeostasis. Moreover, they have been implicated in a series of pathologies (e.g., hypersensitivity reactions, tumors, and inflammatory disorders). In this review, we propose that this cell could be a relevant therapeutic target in multiple sclerosis, which is a central nervous system degenerative disease. To support this proposition, we describe the general biological properties of mast cells, their contribution to innate and specific immunity, and the participation of mast cells in the various stages of multiple sclerosis and experimental autoimmune encephalomyelitis development. The final part of this review is dedicated to an overview of the available mast cells immunomodulatory drugs and their activity on multiple sclerosis and experimental autoimmune encephalomyelitis, including our own experience related to the effect of ketotifen fumarate on experimental autoimmune encephalomyelitis evolution.

Pre-clinical and Clinical Implications of "Inside-Out" vs. "Outside-In" Paradigms in Multiple Sclerosis Etiopathogenesis

Multiple Sclerosis (MS) is an immune-mediated neurological disorder, characterized by central nervous system (CNS) inflammation, oligodendrocyte loss, demyelination, and axonal degeneration. Although autoimmunity, inflammatory demyelination and neurodegeneration underlie MS, the initiating event has yet to be clarified. Effective disease modifying therapies need to both regulate the immune system and promote restoration of neuronal function, including remyelination. The challenge in developing an effective long-lived therapy for MS requires that three disease-associated targets be addressed: (1) self-tolerance must be re-established to specifically inhibit the underlying myelin-directed autoimmune pathogenic mechanisms; (2) neurons must be protected from inflammatory injury and degeneration; (3) myelin repair must be engendered by stimulating oligodendrocyte progenitors to remyelinate CNS neuronal axons. The combined use of chronic and relapsing remitting experimental autoimmune encephalomyelitis (C-EAE, R-EAE) (“outside-in”) as well as progressive diphtheria toxin A chain (DTA) and cuprizone autoimmune encephalitis (CAE) (“inside-out”) mouse models allow for the investigation and specific targeting of all three of these MS-associated disease parameters. The “outside-in” EAE models initiated by myelin-specific autoreactive CD4⁺ T cells allow for the evaluation of both myelin-specific tolerance in the absence or presence of neuroprotective and/or remyelinating agents. The “inside-out” mouse models of secondary inflammatory demyelination are triggered by toxin-induced oligodendrocyte loss or subtle myelin damage, which allows evaluation of novel therapeutics that could promote remyelination and neuroprotection in the CNS. Overall, utilizing these complementary pre-clinical MS models will open new avenues for developing therapeutic interventions, tackling MS from the “outside-in” and/or “inside-out”.

Genomic, microbial and environmental standardization in animal experimentation limiting immunological discovery

Background

The use of inbred mice housed under standardized environmental conditions has been critical in identifying immuno-pathological mechanisms in different infectious and inflammatory diseases as well as revealing new therapeutic targets for clinical trials. Unfortunately, only a small percentage of preclinical intervention studies using well-defined mouse models of disease have progressed to clinically-effective treatments in patients. The reasons for this lack of bench-to-bedside transition are not completely understood; however, emerging data suggest that genetic diversity and housing environment may greatly influence muring immunity and inflammation.

Results

Accumulating evidence suggests that certain immune responses and/or disease phenotypes observed in inbred mice may be quite different than those observed in their outbred counterparts. These differences have been thought to contribute to differing immune responses to foreign and/or auto-antigens in mice vs. humans. There is also a growing literature demonstrating that mice housed under specific pathogen free conditions possess an immature immune system that remarkably affects their ability to respond to pathogens and/or inflammation when compared with mice exposed to a more diverse spectrum of microorganisms. Furthermore, recent studies demonstrate that mice develop chronic cold stress when housed at standard animal care facility temperatures (i.e. 22–24 °C). These temperatures have been shown alter immune responses to foreign and auto-antigens when compared with mice housed at their thermo-neutral body temperature of 30–32 °C.

Conclusions

Exposure of genetically diverse mice to a spectrum of environmentally-relevant microorganisms at housing temperatures that approximate their thermo-neutral zone may improve the chances of identifying new and more potent therapeutics to treat infectious and inflammatory diseases.

Stem Cell Therapy for Neurogenic Bladder Dysfunction in Rodent Models: A Systematic Review

PURPOSE

Neurogenic bladder dysfunction (NGB) has an impact on the quality of life, which made it an important research subject in preclinical studies. The present review investigates the effect of stem cell (SC) therapy on bladder functional recovery after the onset of spinal cord injury (SCI), multiple sclerosis (MS), Parkinson disease (PD), and stroke in rodent models.

METHODS

All experiments evaluated the regenerative potential of SC on the management of NGB in rodent models up to June 2019, were included. From 1,189 relevant publications, 20 studies met our inclusion criteria of which 15 were conducted on SCI, 2 on PD, 2 on stroke, and 1 on MS in the rodent models. We conducted a meta-analysis on SCI experiments and for other neurological diseases, detailed urodynamic findings were reported.

RESULTS

The common SC sources used for therapeutical purposes were neural progenitor cells, bone marrow mesenchymal SCs, human amniotic fluid SCs, and human umbilical cord blood SCs. There was a significant improvement of micturition pressure in both contusion and transaction SCI models 4 and 8 weeks post-SC transplantation. Residual urine volume, micturition volume, and bladder capacity were improved 28 days after SC transplantation only in the transaction model of SCI. Nonvoiding contraction recovered only in 56 days post-cell transplantation in the contusion model.

CONCLUSION

Partial bladder recovery has been evident after SC therapy in SCI models. Due to limitations in the number of studies in other neurological diseases, additional studies are necessary to confirm the detailed mechanism for bladder recovery.

Mast cells and angiogenesis in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease, characterized by multiple demyelination of axons in both white and gray matter in the Central Nervous System (CNS). There is increasing evidence to support the notion that angiogenesis and chronic inflammation are mutually related. Different immune cells, including monocytes-macrophages, lymphocytes, neutrophils, mast cells (MCs) and dendritic cells are able to secrete an array of angiogenic cytokines, which promote growth, migration, and activation of endothelial cells. MCs play various roles in MS pathogenesis, influencing the innate immune response in peripheral tissues and in CNS. The aim of this review article is to discuss the role of MCs in MS pathogenesis with particular reference to the involvement of these inflammatory cells in the angiogenic processes occurring during MS.

Phenotypic characteristics of commonly used inbred mouse strains

The laboratory mouse is the most commonly used mammalian model for biomedical research. An enormous number of mouse models, such as gene knockout, knockin, and overexpression transgenic mice, have been created over the years. A common practice to maintain a genetically modified mouse line is backcrossing with standard inbred mice over several generations. However, the choice of inbred mouse for backcrossing is critical to phenotypic characterization because phenotypic variabilities are often observed between mice with different genetic backgrounds. In this review, the major features of commonly used inbred mouse lines are discussed. The aim is to provide information for appropriate selection of inbred mouse lines for genetic and behavioral studies.

Promising Nanotechnology Approaches in Treatment of Autoimmune Diseases of Central Nervous System

Multiple sclerosis (MS) is a chronic, autoimmune, neurodegenerative disease of the central nervous system (CNS) that yields to neuronal axon damage, demyelization, and paralysis. Although several drugs were designed for the treatment of MS, with some of them being approved in the last few decades, the complete remission and the treatment of progressive forms still remain a matter of debate and a medical challenge. Nanotechnology provides a variety of promising therapeutic tools that can be applied for the treatment of MS, overcoming the barriers and the limitations of the already existing immunosuppressive and biological therapies. In the present review, we explore literature case studies on the development of drug delivery nanosystems for the targeted delivery of MS drugs in the pathological tissues of the CNS, providing high bioavailability and enhanced therapeutic efficiency, as well as nanosystems for the delivery of agents to facilitate efficient remyelination. Moreover, we present examples of tolerance-inducing nanocarriers, being used as promising vaccines for antigen-specific immunotherapy of MS. We emphasize on liposomes, as well as lipid- and polymer-based nanoparticles. Finally, we highlight the future perspectives given by the nanotechnology field toward the improvement of the current treatment of MS and its animal model, experimental autoimmune encephalomyelitis (EAE).

Novel B cell-dependent multiple sclerosis model using extracellular domains of myelin proteolipid protein

Therapeutic success of B cell-targeting approaches in multiple sclerosis (MS) has intensified research into the pathogenic and regulatory roles these cells play in demyelinating disease. Dissecting the function of B cells in the MS mouse model experimental autoimmune encephalomyelitis (EAE) is largely confined to induction with either the myelin oligodendrocyte glycoprotein epitope MOG_35-55 or the full-length recombinant human MOG protein, the latter representing the most-used B cell-dependent EAE model. There is a clear need to investigate B cell function in additional myelin antigen contexts. Unlike MOG_35-55, where lack of B cells yields more severe disease, we show here that the immunodominant myelin proteolipid protein epitope (PLP_178-191) elicited identical EAE in WT and μMT mice, suggesting an absence of B cell engagement by this peptide. We hypothesized that a longer PLP antigen may better engage B cells and designed a peptide encompassing the extracellular domains (ECD) of PLP. We demonstrate here that PLP_ECD-immunized B cell-deficient mice failed to exhibit EAE. In contrast, PLP_ECD induced EAE not only in WT mice, but in B cell-sufficient mice incapable of secreting antibodies, suggesting a predominant antigen presentation role. These results establish a novel, efficient B cell-dependent EAE model.

Cnp Promoter-Driven Sustained ERK1/2 Activation Increases B-Cell Activation and Suppresses Experimental Autoimmune Encephalomyelitis

The ERK1/2 signaling pathway promotes myelin wrapping during development and remyelination, and sustained ERK1/2 activation in the oligodendrocyte (OL) lineage results in hypermyelination of the CNS. We therefore hypothesized that increased ERK1/2 signaling in the OL lineage would 1) protect against immune-mediated demyelination due to increased baseline myelin thickness and/or 2) promote enhanced remyelination and thus functional recovery after experimental autoimmune encephalomyelitis (EAE) induction. Cnp-Cre;Mek1DD-eGFP/+ mice that express a constitutively active form of MEK1 (the upstream activator of ERK1/2) in the OL lineage, exhibited a significant decrease in EAE clinical severity compared to controls. However, experiments using tamoxifen-inducible Plp-CreERT;Mek1DD-eGFP/+ or Pdgfrα-CreERT;Mek1DD-eGFP mice revealed this was not solely due to a protective or reparative effect resulting from MEK1DD expression specifically in the OL lineage. Because EAE is an immune-mediated disease, we examined Cnp-Cre;Mek1DD-eGFP/+ splenic immune cells for recombination. Surprisingly, GFP+ recombined CD19+ B-cells, CD11b+ monocytes, and CD3+ T-cells were noted when Cre expression was driven by the Cnp promoter. While ERK1/2 signaling in monocytes and T-cells is associated with proinflammatory activation, fewer studies have examined ERK1/2 signaling in B-cell populations. After in vitro stimulation, MEK1DD-expressing B-cells exhibited a 3-fold increase in CD138+ plasmablasts and a 5-fold increase in CD5+CD1dhi B-cells compared to controls. Stimulated MEK1DD-expressing B-cells also exhibited an upregulation of IL-10, known to suppress the initiation of EAE when produced by CD5+CD1dhi regulatory B-cells. Taken together, our data support the conclusion that sustained ERK1/2 activation in B-cells suppresses immune-mediated demyelination via increasing activation of regulatory B10 cells.

Promotion of microglial phagocytosis by tuftsin stimulates remyelination in experimental autoimmune encephalomyelitis

Microglia were once thought to serve a pathogenic role in demyelinating diseases, particularly in multiple sclerosis (MS). However, it has recently been shown that in the experimental autoimmune encephalomyelitis (EAE) model of MS, microglia could serve a protective role by promoting remyelination via the efficient removal of apoptotic cells, the phagocytosis of debris and the support of myelinating oligodendrocytes. The aim of the present study was to determine if the effect of microglia could promote the recovery of EAE and attenuate symptoms in EAE. The severity of EAE was assessed by clinical scores, pathologic changes revealed by luxol fast blue staining and immunohistochemical techniques. The results suggested that microglia reduced clinical scores in mice, suppressed ongoing severe EAE and promoted remyelination and recovery in EAE mice. In addition, following induction with tuftsin, the M1/M2 cytokine balance was shifted, downregulating the proinflammatory M1 response and upregulating the anti-inflammatory M2 response. Generally, microglia can stimulate remyelination, which serves a protective role in different phases of EAE and may represent a potential therapeutic strategy for the treatment of MS.

Genetic background and immunological status influence B cell repertoire diversity in mice

The relationship between the immune repertoire and the physiopathological status of individuals is essential to apprehend the genesis and the evolution of numerous pathologies. Nevertheless, the methodological approaches to understand these complex interactions are challenging. We performed a study evaluating the diversity harbored by different immune repertoires as a function of their physiopathological status. In this study, we base our analysis on a murine scFv library previously described and representing four different immune repertoires: i) healthy and naïve, ii) healthy and immunized, iii) autoimmune prone and naïve, and iv) autoimmune prone and immunized. This library, 2.6 × 109 in size, is submitted to high throughput sequencing (Next Generation Sequencing, NGS) in order to analyze the gene subgroups encoding for immunoglobulins. A comparative study of the distribution of immunoglobulin gene subgroups present in the four libraries has revealed shifts in the B cell repertoire originating from differences in genetic background and immunological status of mice.

Behavioural phenotypes in the cuprizone model of central nervous system demyelination

The feeding of cuprizone (CPZ) to animals has been extensively used to model the processes of demyelination and remyelination, with many papers adopting a narrative linked to demyelinating conditions like multiple sclerosis (MS), the aetiology of which is unknown. However, no current animal model faithfully replicates the myriad of symptoms seen in the clinical condition of MS. CPZ ingestion causes mitochondrial and endoplasmic reticulum stress and subsequent apoptosis of oligodendrocytes leads to central nervous system demyelination and glial cell activation. Although there are a wide variety of behavioural tests available for characterizing the functional deficits in animal models of disease, including that of CPZ-induced deficits, they have focused on a narrow subset of outcomes such as motor performance, cognition, and anxiety. The literature has not been systematically reviewed in relation to these or other symptoms associated with clinical MS. This paper reviews these tests and makes recommendations as to which are the most important in order to better understand the role of this model in examining aspects of demyelinating diseases like MS.

Imaging in mice and men: Pathophysiological insights into multiple sclerosis from conventional and advanced MRI techniques

Magnetic resonance imaging (MRI) is the most important tool for diagnosing multiple sclerosis (MS). However, MRI is still unable to precisely quantify the specific pathophysiological processes that underlie imaging findings in MS. Because autopsy and biopsy samples of MS patients are rare and biased towards a chronic burnt-out end or fulminant acute early stage, the only available methods to identify human disease pathology are to apply MRI techniques in combination with subsequent histopathological examination to small animal models of MS and to transfer these insights to MS patients. This review summarizes the existing combined imaging and histopathological studies performed in MS mouse models and humans with MS (in vivo and ex vivo), to promote a better understanding of the pathophysiology that underlies conventional MRI, diffusion tensor and magnetization transfer imaging findings in MS patients. Moreover, it provides a critical view on imaging capabilities and results in MS patients and mouse models and for future studies recommends how to combine those particular MR sequences and parameters whose underlying pathophysiological basis could be partly clarified. Further combined longitudinal in vivo imaging and histopathological studies on rationally selected, appropriate mouse models are required.

Early auto-immune targeting of photoreceptor ribbon synapses in mouse models of multiple sclerosis

Optic neuritis is one of the first manifestations of multiple sclerosis. Its pathogenesis is incompletely understood, but considered to be initiated by an auto‐immune response directed against myelin sheaths of the optic nerve. Here, we demonstrate in two frequently used and well‐validated mouse models of optic neuritis that ribbon synapses in the myelin‐free retina are targeted by an auto‐reactive immune system even before alterations in the optic nerve have developed. The auto‐immune response is directed against two adhesion proteins (CASPR1/CNTN1) that are present both in the paranodal region of myelinated nerves as well as at retinal ribbon synapses. This occurs in parallel with altered synaptic vesicle cycling in retinal ribbon synapses and altered visual behavior before the onset of optic nerve demyelination. These findings indicate that early synaptic dysfunctions in the retina contribute to the pathology of optic neuritis in multiple sclerosis.

Nanomodulation of Macrophages in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic demyelinating autoimmune disease primarily affecting young adults. Despite an unclear causal factor, symptoms and pathology arise from the infiltration of peripheral immune cells across the blood brain barrier. Accounting for the largest fraction of this infiltrate, macrophages are functionally heterogeneous innate immune cells capable of adopting either a pro or an anti-inflammatory phenotype, a phenomenon dependent upon cytokine milieu in the CNS. This functional plasticity is of key relevance in MS, where the pro-inflammatory state dominates the early stage, instructing demyelination and axonal loss while the later anti-inflammatory state holds a key role in promoting tissue repair and regeneration in later remission. This review highlights a potential therapeutic benefit of modulating macrophage polarisation to harness the anti-inflammatory and reparative state in MS. Here, we outline the role of macrophages in MS and look at the role of current FDA approved therapeutics in macrophage polarisation. Moreover, we explore the potential of particulate carriers as a novel strategy to manipulate polarisation states in macrophages, whilst examining how optimising macrophage uptake via nanoparticle size and functionalisation could offer a novel therapeutic approach for MS.

Hectd3 promotes pathogenic Th17 lineage through Stat3 activation and Malt1 signaling in neuroinflammation

Polyubiquitination promotes proteasomal degradation, or signaling and localization, of targeted proteins. Here we show that the E3 ubiquitin ligase Hectd3 is necessary for pathogenic Th17 cell generation in experimental autoimmune encephalomyelitis (EAE), a mouse model for human multiple sclerosis. Hectd3-deficient mice have lower EAE severity, reduced Th17 program and inefficient Th17 cell differentiation. However, Stat3, but not RORγt, has decreased polyubiquitination, as well as diminished tyrosine-705 activating phosphorylation. Additionally, non-degradative polyubiquitination of Malt1, critical for NF-κB activation and Th17 cell function, is reduced. Mechanistically, Hectd3 promotes K27-linked and K29-linked polyubiquitin chains on Malt1, and K27-linked polyubiquitin chains on Stat3. Moreover, Stat3 K180 and Malt1 K648 are targeted by Hectd3 for non-degradative polyubiquitination to mediate robust generation of RORγt⁺IL-17A^hi effector CD4⁺ T cells. Thus, our studies delineate a mechanism connecting signaling related polyubiquitination of Malt1 and Stat3, leading to NF-kB activation and RORγt expression, to pathogenic Th17 cell function in EAE.

Ubiquitination may control protein stability or function. Here the authors show that an ubiquitination enzyme, Hectd3, ubiquitinates Stat3 and Malt1 to modulate their function but not degradation in T cells, and thereby promoting the differentiation of pathogenic Th17 cells and susceptibility to a mouse model of multiple sclerosis.

Systematic Understanding of Bioactive Lipids in Neuro-Immune Interactions: Lessons from an Animal Model of Multiple Sclerosis

Bioactive lipids, or lipid mediators, are utilized for intercellular communications. They are rapidly produced in response to various stimuli and exported to extracellular spaces followed by binding to cell surface G protein-coupled receptors (GPCRs) or nuclear receptors. Many drugs targeting lipid signaling such as non-steroidal anti-inflammatory drugs (NSAIDs), prostaglandins, and antagonists for lipid GPCRs are in use. For example, the sphingolipid analog, fingolimod (also known as FTY720), was the first oral disease-modifying therapy (DMT) for relapsing-remitting multiple sclerosis (MS), whose mechanisms of action (MOA) includes sequestration of pathogenic lymphocytes into secondary lymphoid organs, as well as astrocytic modulation, via down-regulation of the sphingosine 1-phosphate (S1P) receptor, S1P₁, by in vivo-phosphorylated fingolimod. Though the cause of MS is still under debate, MS is considered to be an autoimmune demyelinating and neurodegenerative disease. This review summarizes the involvement of bioactive lipids (prostaglandins, leukotrienes, platelet-activating factors, lysophosphatidic acid, and S1P) in MS and the animal model, experimental autoimmune encephalomyelitis (EAE). Genetic ablation, along with pharmacological inhibition, of lipid metabolic enzymes and lipid GPCRs revealed that each bioactive lipid has a unique role in regulating immune and neural functions, including helper T cell (T_H1 and T_H17) differentiation and proliferation, immune cell migration, astrocyte responses, endothelium function, and microglial phagocytosis. A systematic understanding of bioactive lipids in MS and EAE dredges up information about understudied lipid signaling pathways, which should be clarified in the near future to better understand MS pathology and to develop novel DMTs.

Regulation of Lymphatic GM-CSF Expression by the E3 Ubiquitin Ligase Cbl-b

Genome-wide association studies as well as lymphatic expression analyses have linked both Cbl-b and GM-CSF to human multiple sclerosis as well as other autoimmune diseases. Both Cbl-b and GM-CSF have been shown to play a prominent role in the development of murine encephalomyelitis; however, no functional connection between the two has yet been established. In this study, we show that Cblb knockout mice demonstrated significantly exacerbated severity of experimental autoimmune encephalomyelitis (EAE), augmented T cell infiltration into the central nervous system (CNS) and strongly increased production of GM-CSF in T cells in vitro and in vivo.GM-CSF neutralization demonstrated that the increased susceptibility of Cblb^−/− mice to EAE was dependent on GM-CSF. Mechanistically, p50 binding to the GM-CSF promoter and the IL-3/GM-CSF enhancer element “CNSa” was strongly increased in nuclear extracts from Cbl-b-deficient T cells. This study suggests that Cbl-b limits autoimmunity by preventing the pathogenic effects of GM-CSF overproduction in T cells.

Animal models of multiple sclerosis: Focus on experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic, progressive disorder of the central nervous system (CNS) that affects more than two million people worldwide. Several animal models resemble MS pathology; the most employed are experimental autoimmune encephalomyelitis (EAE) and toxin- and/or virus-induced demyelination. In this review we will summarize our knowledge on the utility of different animal models in MS research. Although animal models cannot replicate the complexity and heterogeneity of the MS pathology, they have proved to be useful for the development of several drugs approved for treatment of MS patients. This review focuses on EAE because it represents both clinical and pathological features of MS. During the past decades, EAE has been effective in illuminating various pathological processes that occur during MS, including inflammation, CNS penetration, demyelination, axonopathy, and neuron loss mediated by immune cells.

Intravenous immune-modifying nanoparticles as a therapy for spinal cord injury in mice

Intravenously infused synthetic 500nm nanoparticles composed of poly(lactide-co-glycolide) are taken up by blood-borne inflammatory monocytes via a macrophage scavenger receptor (macrophage receptor with collagenous structure), and the monocytes no longer traffic to sites of inflammation. Intravenous administration of the nanoparticles after experimental spinal cord injury in mice safely and selectively limited infiltration of hematogenous monocytes into the injury site. The nanoparticles did not bind to resident microglia, and did not change the number of microglia in the injured spinal cord. Nanoparticle administration reduced M1 macrophage polarization and microglia activation, reduced levels of inflammatory cytokines, and markedly reduced fibrotic scar formation without altering glial scarring. These findings thus implicate early-infiltrating hematogenous monocytes as highly selective contributors to fibrosis that do not play an indispensable role in gliosis after SCI. Further, the nanoparticle treatment reduced accumulation of chondroitin sulfate proteoglycans, increased axon density inside and caudal to the lesion site, and significantly improved functional recovery after both moderate and severe injuries to the spinal cord. These data provide further evidence that hematogenous monocytes contribute to inflammatory damage and fibrotic scar formation after spinal cord injury in mice. Further, since the nanoparticles are simple to administer intravenously, immunologically inert, stable at room temperature, composed of an FDA-approved material, and have no known toxicity, these findings suggest that the nanoparticles potentially offer a practical treatment for human spinal cord injury.