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Exosomal microRNAs (miRNAs) are emerging diagnostic biomarkers for neurodegenerative diseases. In this study, we aimed to detect relapsing-remitting multiple sclerosis (RRMS)-specific miRNAs in cerebrospinal fluid (CSF) and serum exosomes with diagnostic potential. One ml of CSF and serum sample were collected from each of the 30 untreated RRMS patients and healthy controls (HCs). A panel of 18 miRNAs affecting inflammatory responses was applied, and qRT-PCR was conducted to detect differentially expressed exosomal miRNAs in CSF and serum of RRMS patients. We identified that 17 out of 18 miRNAs displayed different patterns in RRMS patients compared to HCs. Let-7 g-5p, miR-18a-5p, miR-145-5p, and miR-374a-5p with dual pro-inflammatory and anti-inflammatory actions and miR-150-5p and miR-342-3p with anti-inflammatory action were significantly upregulated in both CSF and serum-derived exosomes of RRMS patients compared to corresponding HCs. Additionally, anti-inflammatory miR-132-5p and pro-inflammatory miR-320a-5p were significantly downregulated in both CSF and serum-derived exosomes of RRMS patients compared to HCs. Ten of 18 miRNAs were differentially expressed in CSF and serum exosomes of the patients. Furthermore, miR-15a-5p, miR-19b-3p, and miR-432-5p were upregulated, and miR-17-5p was downregulated only in CSF exosomes. Interestingly, U6 housekeeping gene was differentially expressed in CSF and serum exosomes, in both RRMS and HCs. As the first report describing CSF exosomal miRNAs expression profile compared to that of serum exosomes in untreated RRMS patients, we showed that CSF and serum exosomes are not identical in terms of biological compounds and display different patterns in miRNAs and U6 expression., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Axonal injury and demyelination occur in demyelinating diseases, such as multiple sclerosis, and the detachment of myelin from axons precedes its degradation. Paranodes are the areas at which each layer of the myelin sheath adheres tightly to axons. The destruction of nodal and paranodal structures during inflammation is an important pathophysiology of various neurological disorders. However, the underlying pathological changes in these structures remain unclear. Kallikrein 6 (KLK6), a serine protease produced by oligodendrocytes, is involved in demyelinating diseases. In the present study, we intraperitoneally injected mice with LPS for several days and examined changes in the localization of KLK6. Transient changes in the intracellular localization of KLK6 to paranodes in the spinal cord were observed during LPS-induced systemic inflammation. However, these changes were not detected in the upper part of brain white matter. LPS-induced changes were suppressed by minocycline, suggesting the involvement of microglia. Moreover, nodal lengths were elongated in LPS-treated wild-type mice, but not in LPS-treated KLK6-KO mice. These results demonstrate the potential involvement of KLK6 in the process of demyelination., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Mesenchymal stem cell-neural progenitors (MSC-NP) are a neural derivative of MSCs that are being investigated in clinical trials as an autologous intrathecal cell therapy to treat patients with secondary progressive (SP) or primary progressive (PP) multiple sclerosis (MS). MSC-NPs promote tissue repair through paracrine mechanisms, however which secreted factors mediate the therapeutic potential of MSC-NPs and how this cell population differs from MSCs remain poorly understood. The objective of this study was to define the transcriptional profile of MSCs and MSC-NPs from MS and non-MS donors to better characterize each cell population. MSCs derived from SPMS, PPMS, or non-MS bone marrow donors demonstrated minimal differential gene expression, despite differences in disease status. MSC-NPs from both MS and non-MS-donors exhibited significant differential gene expression compared to MSCs, with 2,156 and 1,467 genes upregulated and downregulated, respectively. Gene ontology analysis demonstrated pronounced downregulation of cell cycle genes in MSC-NPs compared to MSC consistent with reduced proliferation of MSC-NPs in vitro. In addition, MSC-NPs demonstrated significant enrichment of genes involved in cell signaling, cell communication, neuronal differentiation, chemotaxis, migration, and complement activation. These findings suggest that increased cell signaling and chemotactic capability of MSC-NPs may support their therapeutic potential in MS., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Authors Violaine Harris and Saud Sadiq are listed as inventors on US patent #US 8,642,331, which is related to the study presented in the manuscript. The patent is issued to the Tisch MS Research Center of New York and is considered a non-financial competing interest. This does not alter our adherence to PLOS ONE policies on sharing data or materials. Furthermore, Violaine Harris and Saud Sadiq have no other relevant declarations related to employment, consultancy, products in development, etc. The remaining authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright: © 2023 Harris et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Because of the wide use of Fingolimod for the treatment of multiple sclerosis (MS) and its cardiovascular side effects such as bradycardia, second-generation sphingosine 1-phosphate receptor 1 (S1P1) agonist drugs for MS have been developed and approved by FDA. The issue of bradycardia is still present with the new drugs, however, which necessitates further exploration of S1P1 agonists with improved safety profiles for next-generation MS drugs. Herein, we report a tetrahydroisoquinoline or a benzo[ c ]azepine core-based S1P1 agonists such as 32 and 60 after systematic examination of hydrophilic groups and cores. We investigated the binding modes of our representative compounds and their molecular interactions with S1P1 employing recent S1P1 cryo-EM structures. Also, favorable ADME properties of our compounds were shown. Furthermore, in vivo efficacy of our compounds was clearly demonstrated with PLC and EAE studies. Also, the preliminary in vitro cardiovascular safety of our compound was verified with human iPSC-derived cardiomyocytes.

The neuroinflammatory process characterizing multiple sclerosis (MS) is associated with changes in excitatory synaptic transmission and altered central concentrations of the primary excitatory amino acid, L-glutamate (L-Glu). Recent findings report that cerebrospinal fluid (CSF) levels of L-Glu positively correlate with pro-inflammatory cytokines in MS patients. However, to date, there is no evidence about the relationship between the other primary excitatory amino acid, L-aspartate (L-Asp), its derivative D-enantiomer, D-aspartate, and the levels of pro-inflammatory and anti-inflammatory cytokines in the CSF of MS. In the present study, we measured by HPLC the levels of these amino acids in the cortex, hippocampus, cerebellum, and spinal cord of mice affected by experimental autoimmune encephalomyelitis (EAE). Interestingly, in support of glutamatergic neurotransmission abnormalities in neuroinflammatory conditions, we showed reduced L-Asp levels in the cortex and spinal cord of EAE mice and increased D-aspartate/total aspartate ratio within the cerebellum and spinal cord of these animals. Additionally, we found significantly decreased CSF levels of L-Asp in both relapsing-remitting (n = 157) MS (RR-MS) and secondary progressive/primary progressive (n = 22) (SP/PP-MS) patients, compared to control subjects with other neurological diseases (n = 40). Importantly, in RR-MS patients, L-Asp levels were correlated with the CSF concentrations of the inflammatory biomarkers G-CSF, IL-1ra, MIP-1β, and Eotaxin, indicating that the central content of this excitatory amino acid, as previously reported for L-Glu, reflects a neuroinflammatory environment in MS. In keeping with this, we revealed that CSF L-Asp levels were positively correlated with those of L-Glu, highlighting the convergent variation of these two excitatory amino acids under inflammatory synaptopathy occurring in MS., (© 2023 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of International Society for Neurochemistry.)

Background and Purpose: The aim was to study brain innate immune cell activation in teriflunomide-treated patients with relapsing-remitting multiple sclerosis., Methods: Imaging with 18-kDa translocator protein positron emission tomography (TSPO-PET) using the [ 11 C]PK11195 radioligand was employed to assess microglial activity in the white matter, thalamus and areas surrounding chronic white matter lesions in 12 patients with relapsing-remitting multiple sclerosis who had been treated with teriflunomide for at least 6 months before inclusion. Magnetic resonance imaging (MRI) was used to measure lesion load and brain volume, and quantitative susceptibility mapping (QSM) was used to detect iron rim lesions. These evaluations were repeated after 1 year of inclusion. Twelve age- and gender-matched healthy control subjects were imaged for comparison., Results: Half of the patients had iron rim lesions. In TSPO-PET, the proportion of active voxels indicating innate immune cell activation was slightly greater amongst patients compared with healthy individuals (7.7% vs. 5.4%, p = 0.033). The mean distribution volume ratio of [ 11 C]PK11195 was not significantly different in the normal-appearing white matter or thalamus amongst patients versus controls. Amongst the treated patients, no significant alteration was observed in positron emission tomography distribution volume ratio, the proportion of active voxels, the number of iron-rim-positive lesions, lesion load or brain volume during follow-up., Conclusions: Compared to controls, treated patients exhibited modest signs of diffuse innate immune cell activity, which was unaltered during follow-up. Lesion-associated smoldering inflammation was negligible at both timepoints. To our knowledge, this is the first study applying both TSPO-PET and QSM-MRI to longitudinally evaluate smoldering inflammation., (© 2023 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Background: Multiple sclerosis (MS) is an incurable autoimmune inflammatory demyelinating disease of the central nervous system. Several MS medications can modify disease course through effects on adaptive immune cells, while drugs targeting innate immunity are under investigation. Myeloid-derived suppressor cells (MDSCs) which arise during chronic inflammation, are defined by their T-cell immunosuppressive functions. MiR-223 modulates myeloid cell maturation and expansion, including MDSCs., Methods: MDSCs isolated from healthy controls (HC) and people with MS (pwMS) were co-cultured with CD4+ T-cells to study their immunosuppressive activities in vitro. Cytokines and chemokines concentration were evaluated by Luminex assay in the serum of HC, pwMS, and other neuroinflammatory diseases and correlated with MDSC activities., Results: MDSC suppressive functions are dysregulated in pwMS compared to HC, which was reversed by glucocorticoids (GC). GC specifically downregulated miR-223 levels in MDSCs and increased the expression of STAT3. In vitro assay showed that miR-223 inhibition enhanced MDSC suppressive activity, STAT3 dependently. By multiple linear regression analysis, we demonstrated that MDSC phosphorylated STAT3 was correlated with serum GM-CSF in HC and pwMS., Conclusions: These results suggest that miR-223 could be a therapeutic target for enhancing MDSC's suppressive activities as an alternative to GC., Competing Interests: Declaration of Competing Interest Dr. Cross has done paid consulting for: Biogen, Celgene, EMD Serono, Genentech/Roche, Greenwich Biosciences, Janssen and Novartis, and has contracted research funded by EMD Serono and Genentech., (Copyright © 2023. Published by Elsevier B.V.)

In multiple sclerosis (MS), demyelination occurs in the cerebral cortex, and cerebral cortex atrophy correlates with clinical disabilities. Treatments are needed in MS to induce remyelination. Pregnancy is protective in MS. Estriol is made by the fetoplacental unit, and maternal serum estriol levels temporally align with fetal myelination. Here, we determined the effect of estriol treatment on the cerebral cortex in the preclinical model of MS, experimental autoimmune encephalomyelitis (EAE). Estriol treatment initiated after disease onset decreased cerebral cortex atrophy. Neuropathology of the cerebral cortex showed increased cholesterol synthesis proteins in oligodendrocytes, more newly formed remyelinating oligodendrocytes, and increased myelin in estriol-treated EAE mice. Estriol treatment also decreased the loss of cortical layer V pyramidal neurons and their apical dendrites and preserved synapses. Together, estriol treatment after EAE onset reduced atrophy and was neuroprotective in the cerebral cortex., (Copyright © 2023 THE AUTHORS. Published by Elsevier Inc. All rights reserved.)

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE) are characterized by three main histopathological parameters: inflammation, demyelination and axonal damage. In this study, these parameters were assessed in spinal cords of mice in the successive phases of EAE by quantitative histology and immunohistochemistry. The number of inflammatory lesions, the intensity of inflammation and expression of CD45 corresponded with the severity of clinical symptoms: they increased from the onset phase to the peak phase of the disease and subsided in the chronic phase. Demyelination increased in the peak phase and did not change in the chronic phase of EAE, although axonal damage gradually increased from the onset phase to the chronic phase, suggesting compensatory hypermyelination in that phase. The markers of myelin and axonal injury: myelin basic protein (MBP) and beta amyloid precursor protein (β-APP) showed changes (decrease and increase, respectively) of expression parallel to changes in demyelination and axonal damage. Results of this study indicate that although inflammation intensity subsides in the chronic phase of EAE, the neurodestructive processes: demyelination and axonal damage continue in that phase.

The high-mobility-group domain-containing transcription factor Sox9 confers glial competence to neuroepithelial precursors in the developing central nervous system and is an important determinant of astroglial and oligodendroglial specification. In oligodendroglial cells, it remains expressed in oligodendrocyte progenitor cells (OPCs) of the developing nervous system, but is shut off in differentiating oligodendrocytes as well as in OPCs that persist in the adult nervous system. To better understand the role of Sox9 in OPCs, we generated mouse models that allowed oligodendroglial expression of a Sox9 transgene during development or in the adult. With transgene expression beginning in the last trimester of pregnancy, the number of OPCs increased dramatically, followed by comparable gains in the number of pre-myelinating and myelinating oligodendrocytes as assessed by marker gene expression. This argues that Sox9 boosts oligodendrogenesis during ontogenetic development at all stages, including terminal oligodendrocyte differentiation. When Sox9 transgene expression started in the adult, many transgene-expressing OPCs failed to maintain their progenitor cell identity and instead converted into myelinating oligodendrocytes. As infrequent and inefficient differentiation of adult OPCs is one of the main obstacles to effective remyelination in demyelinating diseases such as Multiple Sclerosis, increased Sox9 levels in adult OPCs may substantially increase their remyelination capacity., (© 2023 The Authors. GLIA published by Wiley Periodicals LLC.)

Background: Chronic active lesions (CAL) in multiple sclerosis (MS) have been observed even in patients taking high-efficacy disease-modifying therapy, including B-cell depletion. Given that CAL are a major determinant of clinical progression, including progression independent of relapse activity (PIRA), understanding the predicted activity and real-world effects of targeting specific lymphocyte populations is critical for designing next-generation treatments to mitigate chronic inflammation in MS., Methods: We analyzed published lymphocyte single-cell transcriptomes from MS lesions and bioinformatically predicted the effects of depleting lymphocyte subpopulations (including CD20 B-cells) from CAL via gene-regulatory-network machine-learning analysis. Motivated by the results, we performed in vivo MRI assessment of PRL changes in 72 adults with MS, 46 treated with anti-CD20 antibodies and 26 untreated, over ∼2 years., Findings: Although only 4.3% of lymphocytes in CAL were CD20 B-cells, their depletion is predicted to affect microglial genes involved in iron/heme metabolism, hypoxia, and antigen presentation. In vivo, tracking 202 PRL (150 treated) and 175 non-PRL (124 treated), none of the treated paramagnetic rims disappeared at follow-up, nor was there a treatment effect on PRL for lesion volume, magnetic susceptibility, or T1 time. PIRA occurred in 20% of treated patients, more frequently in those with ≥4 PRL (p = 0.027)., Interpretation: Despite predicted effects on microglia-mediated inflammatory networks in CAL and iron metabolism, anti-CD20 therapies do not fully resolve PRL after 2-year MRI follow up. Limited tissue turnover of B-cells, inefficient passage of anti-CD20 antibodies across the blood-brain-barrier, and a paucity of B-cells in CAL could explain our findings., Funding: Intramural Research Program of NINDS, NIH; NINDS grants R01NS082347 and R01NS082347; Dr. Miriam and Sheldon G. Adelson Medical Research Foundation; Cariplo Foundation (grant #1677), FRRB Early Career Award (grant #1750327); Fund for Scientific Research (FNRS)., Competing Interests: Declaration of interests PM received consultancy honoraria from Sanofi and Biogen and, research funding from Biogen. VVP received support for attending meetings and/or travel, support for participating in Advisory Board and consulting fees (the latters payed to the institution Cliniques Universitaires Saint-Luc) from Roche, Biogen, Sanofi, Merck Healthcare KGaA (Darmstadt, Germany), Bristol Meyer Squibb, Janssen, Almirall, Alexion and Novartis Pharma. PAC Is PI on grants to JHU from Genentech and previously Principia; he has received consulting honoraria for serving on SABs for Nervgen, Idorsia, Biogen, Vaccitech, and Lilly. DSR has received research funding from Abata Therapeutics, Sanofi-Genzyme, and Vertex Pharmaceuticals. MA received consultancy honoraria from Abata Therapeutics, Biogen, Sanofi-Genzyme and GSK., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Clostridium perfringens epsilon toxin is associated with enterotoxaemia in livestock. More recently, it is proposed to play a role in multiple sclerosis (MS) in humans. Compared to matched controls, strains of C. perfringens which produce epsilon toxin are significantly more likely to be isolated from the gut of MS patients and at significantly higher levels; similarly, sera from MS patients are significantly more likely to contain antibodies to epsilon toxin. Epsilon toxin recognises the myelin and lymphocyte (MAL) protein receptor, damaging the blood-brain barrier and brain cells expressing MAL. In the experimental autoimmune encephalomyelitis model of MS, the toxin enables infiltration of immune cells into the central nervous system, inducing an MS-like disease. These studies provide evidence that epsilon toxin plays a role in MS, but do not yet fulfil Koch's postulates in proving a causal role.

This study aimed to investigate the association between dietary acid load (DAL) and multiple sclerosis (MS), through the potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. In a hospital-based case-control study of 109 patients with MS and 130 healthy individuals, a validated 168-item semi-quantitative food frequency questionnaire and a logistic regression model were used to evaluate the association between the DAL and MS. After adjusting for age (years), gender (male/female), body mass index (Kg/m 2 ), and total calories (Kcal), the MS odds were 92% lower for those in the highest tertile of total plant-based protein (OR: 0.08, 95%CI: 0.03, 0.23; p -value < 0.001) and about four times higher for those in the highest tertile of the PRAL (OR: 4.16, 95%CI: 1.94, 8.91; p -value < 0.001) and NEAP scores (OR: 3.57, 95%CI: 1.69, 7.53; p -value < 0.001), compared to those in the lowest tertile. After further adjusting for sodium, saturated fatty acid, and fiber intake, the results remained significant for total plant-based protein intake (OR: 0.07, 95%CI: 0.01, 0.38; p -value = 0.002). In conclusion, a higher NEAP or PRAL score may be associated with increased odds of MS, while a higher intake of plant-based protein instead of animal-based protein may be protective.

Introduction: Little is known about the molecular profiling associated with the effect of cladribine in patients with multiple sclerosis (MS). Here, we aimed first to characterize the transcriptomic and proteomic profiles induced by cladribine in blood cells, and second to identify potential treatment response biomarkers to cladribine in patients with MS., Methods: Gene, protein and microRNA (miRNA) expression profiles were determined by microarrays (genes, miRNAs) and mass spectrometry (proteins) in peripheral blood mononuclear cells (PBMCs) from MS patients after in vitro treatment with cladribine in its active and inactive forms. Two bioinformatics approaches to integrate the three obtained datasets were applied: (i) a multiomics discriminant analysis (DIABLO - Data Integration Analysis for Biomarker discovery using Latent variable approaches for Omics studies); and (ii) a multi-stage integration of features selected in differential expression analysis on each dataset and then merged. Selected molecules from the in vitro study were quantified by qPCR ex vivo in PBMCs from MS patients receiving cladribine., Results: PBMCs treated in vitro with cladribine were characterized by a major downregulation of gene, protein, and miRNA expression compared with the untreated cells. An intermediate pattern between the cladribine-treated and untreated conditions was observed in PBMCs treated with cladribine in its inactive form. The differential expression analysis of each dataset led to the identification of four genes and their encoded proteins, and twenty-two miRNAs regulating their expression, that were associated with cladribine treatment. Two of these genes (PPIF and NHLRC2), and three miRNAs (miR-21-5p, miR-30b-5p, and miR-30e-5p) were validated ex vivo in MS patients treated with cladribine., Discussion: By using a combination of omics data and bioinformatics approaches we were able to identify a multiomics molecular profile induced by cladribine in vitro in PBMCs. We also identified a number of biomarkers that were validated ex vivo in PBMCs from patients with MS treated with cladribine that have the potential to become treatment response biomarkers to this drug., Competing Interests: UB is an employee of Ares Trading SA, Eysins, Switzerland, an affiliate of Merck KGaA, Darmstadt, Germany. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Fissolo, Calvo-Barreiro, Eixarch, Boschert, Villar, Costa-Frossard, Ferrer, Sanchez, Borràs, Sabidó, Espejo, Montalban and Comabella.)

Multiple sclerosis (MS) is the most common chronic central nervous system inflammatory disease. Individual courses are highly variable, with complete remission in some patients and relentless progression in others. We generated induced pluripotent stem cells (iPSCs) to investigate possible mechanisms in benign MS (BMS), compared with progressive MS (PMS). We differentiated neurons and astrocytes that were then stressed with inflammatory cytokines typically associated with MS phenotypes. TNF-α/IL-17A treatment increased neurite damage in MS neurons from both clinical phenotypes. In contrast, TNF-α/IL-17A-reactive BMS astrocytes cultured with healthy control neurons exhibited less axonal damage compared with PMS astrocytes. Accordingly, single-cell transcriptomic BMS astrocyte analysis of cocultured neurons revealed upregulated neuronal resilience pathways; these astrocytes showed differential growth factor expression. Furthermore, supernatants from BMS astrocyte/neuronal cocultures rescued TNF-α/IL-17-induced neurite damage. This process was associated with a unique LIF and TGF-β1 growth factor expression, as induced by TNF-α/IL-17 and JAK-STAT activation. Our findings highlight a potential therapeutic role of modulation of astrocyte phenotypes, generating a neuroprotective milieu. Such effects could prevent permanent neuronal damage.

Recent evidence suggests that the glucagon-like peptide-1 receptor (GLP-1R) agonists have neuroprotective activities in the CNS in animal models of Parkinson's disease, Alzheimer's disease, and multiple sclerosis (MS). This study aimed to investigate whether a novel long-acting GLP-1R agonist, NLY01, could limit demyelination or improve remyelination as occurs in MS using the cuprizone (CPZ) mouse model. Herein, we assessed the expression of GLP-1R on oligodendrocytes in vitro and found that mature oligodendrocytes (Olig2 + PDGFRa - ) express GLP-1R. We further confirmed this observation in the brain by immunohistochemistry and found that Olig2 + CC1 + cells express GLP-1R. We next administered NLY01 twice per week to C57B6 mice while on CPZ chow diet and found that NLY01 significantly reduced demyelination with greater weight loss than vehicle-treated controls. Because GLP-1R agonists are known to have anorexigenic effect, we then administered CPZ by oral gavage and treated the mice with NLY01 or vehicle to ensure the dose consistency of CPZ ingestion among mice. Using this modified approach, NLY01 was no longer effective in reducing demyelination of the corpus callosum (CC). We next sought to examine the effects of NLY01 treatment on remyelination after CPZ intoxication and during the recovery period using an adoptive transfer-CPZ (AT-CPZ) model. We found no significant differences between the NLY01 and vehicle groups in the amount of myelin or the number of mature oligodendrocytes in the CC. In summary, despite the promising anti-inflammatory and neuroprotective effects of GLP-1R agonists that have been previously described, our experiments provided no evidence to support a beneficial effect of NLY01 on limiting demyelination or enhancing remyelination. This information may be useful in selecting proper outcome measures in clinical trials of this promising class of drugs in MS., (© 2023. The American Society for Experimental Neurotherapeutics, Inc.)

Oligodendrocytes are responsible for myelinating central nervous system (CNS) axons and rapid electrical transmission through saltatory conduction of action potentials. Myelination and myelin repair rely partially on oligodendrogenesis, which comprises oligodendrocyte precursor cell (OPC) migration, maturation, and differentiation into oligodendrocytes (OL). In multiple sclerosis (MS), demyelination occurs due to an inflammatory cascade with auto-reactive T-cells. When oligodendrogenesis fails, remyelination becomes aberrant and conduction impairments are no longer restored. Although current disease modifying therapies have achieved results in modulating the faulty immune response, disease progression continues because of chronic inflammation, neurodegeneration, and failure of remyelination. Therapies have been tried to promote remyelination. Modulation of neuronal activity seems to be a very promising strategy in preclinical studies. Additionally, studies in people with MS (pwMS) have shown symptom improvement following non-invasive brain stimulation. (NIBS) techniques. The aforementioned mechanisms are yet unknown and probably involve both the activation of neurons and glial cells. Noting neuronal activity contributes to myelin plasticity and that NIBS modulates neuronal activity; we argue that NIBS is a promising research horizon for demyelinating diseases. We review the hypothesized pathways through which NIBS may affect both neuronal activity in the CNS and how the resulting activity can affect oligodendrogenesis and myelination., Competing Interests: Declaration of Competing Interest The authors report no financial interests or potential conflict of interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Positron emission tomography (PET) imaging of the myelin sheath is a powerful tool to investigate multiple sclerosis, monitor its evolution, and support drug development. Radiotracers based on N,N -dimethylaminostilbene (MeDAS) fluorinated analogs have been designed for myelin PET imaging but were never translated to humans. We have synthesized three original fluorinated analogs of MeDAS with low metabolic rates for which binding to myelin in a healthy rat brain was demonstrated by fluorescence microscopy. A tosyl precursor was synthesized for the lead compound PEGMeDAS and automated fluorine-18 radiolabeling afforded [ 18 F]PEGMeDAS in 25 ± 5% radiochemical yield and 102 ± 15 GBq/μmol molar activity. Biodistribution in healthy rats demonstrated the brain penetration with low penetration of radiometabolites. However, E to Z isomerization observed in plasma hampers further investigations of this family of molecules and requires complementary data on the in vivo behavior of the Z isomer.

Background: CD4 + T cells play an important role in body development and homeostasis. Quantitative and functional changes in CD4 + T cells result in abnormal immune responses, which lead to inflammation, cancer, or autoimmune diseases, such as multiple sclerosis (MS). Ubiquitination plays an essential role in the differentiation and functioning of CD4 + T cells. However, the function of several E3 ubiquitin ligases in CD4 + T cell differentiation and T cell-mediated pathological diseases remains unclear. Methods: RNA sequencing data were analyzed to identify the E3 ubiquitin ligases that participate in the pathogenesis of MS. Furthermore, conditional knockout mice were generated. Specifically, flow cytometry, qPCR, western blot, CO-IP and cell transfer adoptive experiments were performed. Results: In this study, we identified The RING finger 157 (RNF157) as a vital regulator of CD4 + T cell differentiation; it promoted Th1 differentiation but attenuated Th17 differentiation and CCR4 and CXCR3 expressions in CD4 + T cells, thereby limiting experimental autoimmune encephalomyelitis development. Mechanistically, RNF157 in CD4 + T cells targeted HDAC1 for K48-linked ubiquitination and degradation. Notably, RNF157 expression was significantly decreased and showed a significant negative correlation with RORγt expression in patients with MS. Conclusions: Our study highlights the critical role of RNF157 in regulating CD4 + T cell functions in autoimmune diseases and suggests RNF157 as a potential target in adaptive immune responses against MS and other autoimmune disorders., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: With millions of victims worldwide, multiple sclerosis is the second most common cause of disability among young adults. Although formidable advancements have been made in understanding the disease, the neurodegeneration associated with multiple sclerosis is only partially counteracted by current treatments, and effective therapy for progressive multiple sclerosis remains an unmet need. Therefore, new approaches are required to delay demyelination and the resulting disability and to restore neural function by promoting remyelination and neuronal repair., Aims: The article reviews the latest literature in this field., Materials and Methods: The fibroblast growth factor (FGF) signaling pathway is a promising target in progressive multiple sclerosis., Discussion: FGF signal transduction contributes to establishing the oligodendrocyte lineage, neural stem cell proliferation and differentiation, and myelination of the central nervous system. Furthermore, FGF signaling is implicated in the control of neuroinflammation. In recent years, interventions targeting FGF, and its receptor (FGFR) have been shown to ameliorate autoimmune encephalomyelitis symptoms in multiple sclerosis animal models moderately., Conclusion: Here, we summarize the recent findings and investigate the role of FGF/FGFR signaling in the onset and progression, discuss the potential therapeutic advances, and offer fresh insights into managing multiple sclerosis., (© 2023 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Oligodendrocytes are a type of glial cells that produce a lipid-rich membrane called myelin. Myelin assembles into a sheath and lines neuronal axons in the brain and spinal cord to insulate them. This not only increases the speed and efficiency of nerve signal transduction but also protects the axons from damage and degradation, which could trigger neuronal cell death. Demyelination, which is caused by a loss of myelin and oligodendrocytes, is a prominent feature of many neurological conditions, including Multiple sclerosis (MS), spinal cord injuries (SCI), and leukodystrophies. Demyelination is followed by a time of remyelination mediated by the recruitment of endogenous oligodendrocyte precursor cells, their migration to the injury site, and differentiation into myelin-producing oligodendrocytes. Unfortunately, endogenous remyelination is not sufficient to overcome demyelination, which explains why there are to date no regenerative-based treatments for MS, SCI, or leukodystrophies. To better understand the role of oligodendrocytes and develop cell-based remyelination therapies, human oligodendrocytes have been derived from somatic cells using cell reprogramming. This review will detail the different cell reprogramming methods that have been developed to generate human oligodendrocytes and their applications to disease modeling and cell-based remyelination therapies. Recent developments in the field have seen the derivation of brain organoids from pluripotent stem cells, and protocols have been devised to incorporate oligodendrocytes within the organoids, which will also be reviewed., (© 2023 The Authors. Journal of Neuroscience Research published by Wiley Periodicals LLC.)

Maladjusted immune responses to the coronavirus disease 2019 (COVID-19), for example, cytokine release syndrome, may result in immunopathology and acute respiratory distress syndrome. Sphingosine-1-phosphate (S1P), a bioactive lipid mediator, and its S1P receptor (S1PR) are crucial in maintaining endothelial cell chemotaxis and barrier integrity. Apart from the S1P1 receptor-mediated mechanisms of sequestration of cytotoxic lymphocytes, including Th-17 and S1P1/2/3-mediated endothelial barrier functions, S1PR modulators may also attenuate cytokine release via activation of serine/threonine protein phosphatase 2A and enhance the pulmonary endothelial barrier via the c-Abl tyrosine kinase pathway. Chronic treatment with fingolimod (S1PR1,3,4,5 modulator) and siponimod (S1PR1,5 modulator) has demonstrated efficacy in reducing inflammatory disease activity and slowing down disease progression in multiple sclerosis. The decision to selectively suppress the immunity of a critically ill patient with COVID-19 remains a difficult choice. It has been suggested that treatment with fingolimod or siponimod may be appropriate to attenuate severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-induced hyperinflammation in patients with COVID-19 since these patients are already monitored in an intensive care setting. Here, we review the use of S1PR modulators, fingolimod and siponimod, in regulating the inflammatory response to SARS-CoV-2 with the aim of understanding their potential rationale use in patients with COVID-19.

Background : Transient receptor potential ankyrin 1 (TRPA1) activation is implicated in neuropathic pain-like symptoms. However, whether TRPA1 is solely implicated in pain-signaling or contributes to neuroinflammation in multiple sclerosis (MS) is unknown. Here, we evaluated the TRPA1 role in neuroinflammation underlying pain-like symptoms using two different models of MS. Methods : Using a myelin antigen, Trpa1 + / + or Trpa1 - / - female mice developed relapsing-remitting experimental autoimmune encephalomyelitis (RR-EAE) (Quil A as adjuvant) or progressive experimental autoimmune encephalomyelitis (PMS)-EAE (complete Freund's adjuvant). The locomotor performance, clinical scores, mechanical/cold allodynia, and neuroinflammatory MS markers were evaluated. Results : Mechanical and cold allodynia detected in RR-EAE, or PMS-EAE Trpa1 + / + mice, were not observed in Trpa1 - / - mice. The increased number of cells labeled for ionized calcium-binding adapter molecule 1 (Iba1) or glial fibrillary acidic protein (GFAP), two neuroinflammatory markers in the spinal cord observed in both RR-EAE or PMS-EAE Trpa1 + / + mice, was reduced in Trpa1 - / - mice. By Olig2 marker and luxol fast blue staining, prevention of the demyelinating process in Trpa1 - / - induced mice was also detected. Conclusions : Present results indicate that the proalgesic role of TRPA1 in EAE mouse models is primarily mediated by its ability to promote spinal neuroinflammation and further strengthen the channel inhibition to treat neuropathic pain in MS.

Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system (CNS) whose aetiology is only partly understood. Investigating the intricate transcriptional changes occurring in MS brains is critical to unravel novel pathogenic mechanisms and therapeutic targets. Unfortunately, this process is often hindered by the difficulty in retrieving an adequate number of samples. However, by merging data from publicly available datasets, it is possible to identify alterations in gene expression profiles and regulatory pathways that were previously overlooked. Here, we merged microarray gene expression profiles obtained from CNS white matter samples taken from MS donors to identify novel differentially expressed genes (DEGs) linked with MS. Data from three independent datasets (GSE38010, GSE32915, and GSE108000) were combined and used to detect novel DEGs using the Stouffer's Z-score method. Corresponding regulatory pathways were analysed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway databases. Finally, top up- and down-regulated transcripts were validated by real-time quantitative PCR (qPCR) using an independent set of white matter tissue samples obtained from MS donors with different disease subtypes. There were a total of 1446 DEGs, of which 742 were up-regulated and 704 genes were down-regulated. DEGs were associated with several myelin-related pathways and protein metabolism pathways. Validation studies of selected top up- or down-regulated genes highlighted MS subtype-specific differences in the expression of some of the identified genes, underlining a more complex scenario of white matter pathology amongst people afflicted by this devastating disease.

Inflammatory demyelinating diseases (IDDs) are among the main causes of inflammatory and neurodegenerative injury of the central nervous system (CNS) in young adult patients. Of these, multiple sclerosis (MS) is the most frequent and studied, as it affects about a million people in the USA alone. The understanding of the mechanisms underlying their pathology has been advancing, although there are still no highly effective disease-modifying treatments for the progressive symptoms and disability in the late stages of disease. Among these mechanisms, the action of glial cells upon lesion and regeneration has become a prominent research topic, helped not only by the discovery of glia as targets of autoantibodies, but also by their role on CNS homeostasis and neuroinflammation. In the present article, we discuss the participation of glial cells in IDDs, as well as their association with demyelination and synaptic dysfunction throughout the course of the disease and in experimental models, with a focus on MS phenotypes. Further, we discuss the involvement of microglia and astrocytes in lesion formation and organization, remyelination, synaptic induction and pruning through different signaling pathways. We argue that evidence of the several glia-mediated mechanisms in the course of CNS demyelinating diseases supports glial cells as viable targets for therapy development., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Coutinho Costa, Araújo, Alves-Leon and Gomes.)

TNF signaling is an essential regulator of cellular homeostasis. Through its two receptors TNFR1 and TNFR2, soluble versus membrane-bound TNF enable cell death or survival in a variety of cell types. TNF-TNFRs signaling orchestrates important biological functions such as inflammation, neuronal activity as well as tissue de- and regeneration. TNF-TNFRs signaling is a therapeutic target for neurodegenerative diseases such as multiple sclerosis (MS) and Alzheimer's disease (AD), but animal and clinical studies yielded conflicting findings. Here, we ask whether a sequential modulation of TNFR1 and TNFR2 signaling is beneficial in experimental autoimmune encephalomyelitis (EAE), an experimental mouse model that recapitulates inflammatory and demyelinating aspects of MS. To this end, human TNFR1 antagonist and TNFR2 agonist were administered peripherally at different stages of disease development in TNFR-humanized mice. We found that stimulating TNFR2 before onset of symptoms leads to improved response to anti-TNFR1 therapeutic treatment. This sequential treatment was more effective in decreasing paralysis symptoms and demyelination, when compared to single treatments. Interestingly, the frequency of the different immune cell subsets is unaffected by TNFR modulation. Nevertheless, treatment with only a TNFR1 antagonist increases T-cell infiltration in the central nervous system (CNS) and B-cell cuffing at the perivascular sites, whereas a TNFR2 agonist promotes Treg CNS accumulation. Our findings highlight the complicated nature of TNF signaling which requires a timely balance of selective activation and inhibition of TNFRs in order to exert therapeutic effects in the context of CNS autoimmunity., (© 2023. The Author(s).)

Background: Neurodegenerative diseases are among the most prevalent and devastating neurological disorders, with few effective prevention and treatment strategies. We aimed to integrate genetic and proteomic data to prioritize drug targets for neurodegenerative diseases., Methods: We screened human proteomes through Mendelian randomization to identify causal mediators of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, frontotemporal dementia, and Lewy body dementia. For instruments, we used brain and blood protein quantitative trait loci identified from one genome-wide association study with 376 participants and another with 3301 participants, respectively. Causal associations were subsequently validated by sensitivity analyses and colocalization. The safety and druggability of identified targets were also evaluated., Results: Our analyses showed targeting BIN1, GRN, and RET levels in blood as well as ACE, ICA1L, MAP1S, SLC20A2, and TOM1L2 levels in brain might reduce Alzheimer's disease risk, while ICA1L, SLC20A2, and TOM1L2 were not recommended as prioritized drugs due to the identified potential side effects. Brain CD38, DGKQ, GPNMB, and SEC23IP were candidate targets for Parkinson's disease. Among them, GPNMB was the most promising target for Parkinson's disease with their causal relationship evidenced by studies on both brain and blood tissues. Interventions targeting FCRL3, LMAN2, and MAPK3 in blood and DHRS11, FAM120B, SHMT1, and TSFM in brain might affect multiple sclerosis risk. The risk of amyotrophic lateral sclerosis might be reduced by medications targeting DHRS11, PSMB3, SARM1, and SCFD1 in brain., Conclusions: Our study prioritized 22 proteins as targets for neurodegenerative diseases and provided preliminary evidence for drug development. Further studies are warranted to validate these targets., (Copyright © 2022 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

CD4 +  T cells, specifically Th cells (Th1 and Th17) and regulatory T cells (Tregs), play a pivotal role in the pathogenesis of multiple sclerosis (MS), a demyelinating autoimmune disease of the CNS. STAT3 inhibitors are potential therapeutic targets for several immune disorders. In this study, we investigated the role of a well-known STAT3 inhibitor, S3I-201, in experimental autoimmune encephalomyelitis (EAE), a model of MS. Following induction of EAE, mice were intraperitoneally administered S3I-201 (10 mg/kg) each day, beginning on day 14 and continuing till day 35 and were evaluated for clinical signs. Flow cytometry was used to investigate further the effect of S3I-201 on Th1 (IFN-γ, STAT1, pSTAT1, and T-bet), Th17 (IL-17A, STAT3, pSTAT3, and RORγt), and regulatory T cells (Treg, IL-10, TGF-β1, and FoxP3) expressed in splenic CD4 + T cells. Moreover, we analyzed the effects of S3I-201 on mRNA and protein expression of IFN-γ, T-bet, IL-17A, STAT1, STAT3, pSTAT1, pSTAT3, RORγ, IL-10, TGF-β1, and FoxP3 in the brains of EAE mice. The severity of clinical scores decreased in S3I-201-treated EAE mice compared to vehicle-treated EAE mice. S3I-201 treatment significantly decreased CD4 + IFN-γ + , CD4 + STAT1 + , CD4 + pSTAT1 + , CD4 + T-bet + , CD4 + IL-17A + , CD4 + STAT3 + , CD4 + pSTAT3 + , and CD4 + RORγt + and increased CD4 + IL-10 + , CD4 + TGF-β1 + , and CD4 + FoxP3 + in the spleens of EAE mice. Additionally, S3I-201 administration in EAE mice significantly decreased the mRNA and protein expression of Th1 and Th17 and increased those of Treg. These results suggest that S3I-201 may have novel therapeutic potential against MS., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The purpose of this study was to examine whether myeloid dendritic cells (mDCs) from patients with multiple sclerosis (MS) and healthy controls (HCs) become similarly tolerogenic when exposed to IL-27 as this may represent a potential mechanism of autoimmune dysregulation. Our study focused on natural mDCs that were isolated from HCs and MS patient peripheral blood mononuclear cells (PBMCs). After a 24-h treatment with IL-27 ± lipopolysaccharide (LPS), the mDCs were either harvested to identify IL-27-regulated gene expression or co-cultured with naive T-cells to measure how the treated DC affected T-cell proliferation and cytokine secretion. mDCs isolated from HCs but not untreated MS patients became functionally tolerogenic after IL-27 treatment. Although IL-27 induced both HC and untreated MS mDCs to produce similar amounts of IL-10, the tolerogenic HC mDCs expressed PD-L2, IDO1, and SOCS1, while the non-tolerogenic untreated MS mDCs expressed IDO1 and IL-6R. Cytokine and RNA analyses identified two signature blocks: the first identified genes associated with mDC tolerizing responses to IL-27, while the second was associated with the presence of MS. In contrast to mDCs from untreated MS patients, mDCs from HCs and IFNb-treated MS patients became tolerogenic in response to IL-27. The genes differentially expressed in the different donor IL-27-treated mDCs may contain targets that regulate mDC tolerogenic responses.

Astrocytes, the most abundant group of glia cells in the brain, provide support for neurons and indicate multiple various functions in the central nervous system (CNS). Growing data additionally describe their role in the regulation of immune system activity. They exert their function not only by direct contact with other cell types, but also through an indirect method, e.g., by secreting various molecules. One such structure is extracellular vesicles, which are important mediators of crosstalk between cells. In our study, we observed that the impact of exosomes derived from astrocytes with various functional phenotype differently affect the immune response of CD4+ T cells, both from healthy individuals and from patients with multiple sclerosis (MS). Astrocytes, by modulating exosome cargo, impacts the release of IFN-γ, IL-17A and CCL2 in our experimental conditions. Considering the proteins concentration in cell culture supernatants and the cellular percentage of Th phenotypes, it could be stated that human astrocytes, by the release of exosomes, are able to modify the activity of human T cells.

Oligodendrocytes and their progenitors upregulate MHC pathways in response to inflammation, but the frequency of this phenotypic change is unknown and the features of these immune oligodendroglia are poorly defined. We generated MHC class I and II transgenic reporter mice to define their dynamics in response to inflammatory demyelination, providing a means to monitor MHC activation in diverse cell types in living mice and define their roles in aging, injury, and disease., Competing Interests: EH, RC, MS, DH, CM, KM, JG, DB, PC No competing interests declared, (© 2023, Harrington, Catenacci et al.)

Multiple sclerosis (MS) is a progressive inflammatory demyelinating disease of the CNS. Increasing evidence suggests that vulnerable neurons in MS exhibit fatal metabolic exhaustion over time, a phenomenon hypothesized to be caused by chronic hyperexcitability. Axonal Kv7 (outward-rectifying) and oligodendroglial Kir4.1 (inward-rectifying) potassium channels have important roles in regulating neuronal excitability at and around the nodes of Ranvier. Here, we studied the spatial and functional relationship between neuronal Kv7 and oligodendroglial Kir4.1 channels and assessed the transcriptional and functional signatures of cortical and retinal projection neurons under physiological and inflammatory demyelinating conditions. We found that both channels became dysregulated in MS and experimental autoimmune encephalomyelitis (EAE), with Kir4.1 channels being chronically downregulated and Kv7 channel subunits being transiently upregulated during inflammatory demyelination. Further, we observed that pharmacological Kv7 channel opening with retigabine reduced neuronal hyperexcitability in human and EAE neurons, improved clinical EAE signs, and rescued neuronal pathology in oligodendrocyte-Kir4.1-deficient (OL-Kir4.1-deficient) mice. In summary, our findings indicate that neuron-OL compensatory interactions promoted resilience through Kv7 and Kir4.1 channels and identify pharmacological activation of nodal Kv7 channels as a neuroprotective strategy against inflammatory demyelination.

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammatory infiltration and demyelination in the central nervous system (CNS). IFN-gamma (IFN-γ), a critically important immunomodulator, has been widely studied in MS pathology. The confusing and complex effects of IFN-γ in MS patients and rodent models, however, cause us to look more closely at its exact role in MS. In this study, we identified the role of the IFN-γ signaling in the choroid plexus (CP) in the experimental autoimmune encephalomyelitis (EAE) model. We found that the IFN-γ signal was rapidly amplified when CNS immune cell infiltration occurred in the CP during the progressive stage. Furthermore, using two CP-specific knockdown strategies, we demonstrated that blocking the IFN-γ signal via knockdown of IFN-γR1 in the CP could protect mice against EAE pathology, as evidenced by improvements in clinical scores and infiltration. Notably, knocking down IFN-γR1 in the CP reduced the local expression of adhesion molecules and chemokines. This finding suggests that IFN-γ signaling in the CP may participate in the pathological process of EAE by preventing pathological T helper (Th) 17 + cells from infiltrating into the CNS. Finally, we showed that the unbalanced state of IFN-γ signaling between peripheral lymphocytes and the choroid plexus may determine whether IFN-γ has a protective or aggravating effect on EAE pathology. Above all, we discovered that IFN-γR1-mediated IFN-γ signaling in the CP was a vital pathway in the pathological process of EAE., (© 2023 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Multiple sclerosis (MS) is a focal inflammatory and demyelinating disease. The inflammatory infiltrates consist of macrophages/microglia, T and B cells. Remyelination (RM) is an endogenous repair process which frequently fails in MS patients. In earlier studies, T cells either promoted or impaired RM. Here, we used the combined cuprizone/MOG-EAE model to further dissect the functional role of T cells for RM. The combination of MOG immunization with cuprizone feeding targeted T cells to the corpus callosum and increased the extent of axonal injury. Global gene expression analyses demonstrated significant changes in the inflammatory environment; however, additional MOG immunization did not alter the course of RM. Our results suggest that the inflammatory environment in the combined model affects axons and oligodendrocytes differently and that oligodendroglial lineage cells might be less susceptible to T cell mediated injury., (© 2022 The Authors. GLIA published by Wiley Periodicals LLC.)

The peptide spanning residues 35 to 55 of the protein myelin oligodendrocyte glycoprotein (MOG) has been studied extensively in its role as a key autoantigen in the neuroinflammatory autoimmune disease multiple sclerosis. Rodents and nonhuman primate species immunized with this peptide develop a neuroinflammatory condition called experimental autoimmune encephalomyelitis, often used as a model for multiple sclerosis. Over the last decade, the role of citrullination of this antigen in the disease onset and progression has come under increased scrutiny. We recently reported on the ability of these citrullinated MOG35-55 peptides to aggregate in an amyloid-like fashion, suggesting a new potential pathogenic mechanism underlying this disease. The immunodominant region of MOG is highly conserved between species, with the only difference between the murine and human protein, a polymorphism on position 42, which is serine in mice and proline for humans. Here, we show that the biophysical and biochemical behavior we previously observed for citrullinated murine MOG35-55 is fundamentally different for human and mouse MOG35-55. The citrullinated human peptides do not show amyloid-like behavior under the conditions where the murine peptides do. Moreover, we tested the ability of these peptides to stimulate lymphocytes derived from MOG immunized marmoset monkeys. While the citrullinated murine peptides did not produce a proliferative response, one of the citrullinated human peptides did. We postulate that this unexpected difference is caused by disparate antigen processing. Taken together, our results suggest that further study on the role of citrullination in MOG-induced experimental autoimmune encephalomyelitis is necessary., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Multiple sclerosis (MS) is an inflammatory-demyelinating disease of the central nervous system (CNS) mediated by aberrant auto-reactive immune responses. The current immune-modulatory therapies are unable to protect and repair immune-mediated neural tissue damage. One of the therapeutic targets in MS is the sphingosine-1-phosphate (S1P) pathway which signals via sphingosine-1-phosphate receptors 1-5 (S1P 1-5 ). S1P receptors are expressed predominantly on immune and CNS cells. Considering the potential neuroprotective properties of S1P signaling, we utilized S1P 1 -GFP (Green fluorescent protein) reporter mice in the cuprizone-induced demyelination model to investigate in vivo S1P - S1P 1 signaling in the CNS. We observed S1P 1 signaling in a subset of neural stem cells in the subventricular zone (SVZ) during demyelination. During remyelination, S1P 1 signaling is expressed in oligodendrocyte progenitor cells in the SVZ and mature oligodendrocytes in the medial corpus callosum (MCC). In the cuprizone model, we did not observe S1P 1 signaling in neurons and astrocytes. We also observed β-arrestin-dependent S1P 1 signaling in lymphocytes during demyelination and CNS inflammation. Our findings reveal β-arrestin-dependent S1P 1 signaling in oligodendrocyte lineage cells implying a role of S1P 1 signaling in remyelination., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel that is activated by capsaicin (CAP), the main component of chili pepper. Despite studies in several neurological diseases, the role of TRPV1 in demyelinating diseases remains unknown. Herein, we reported that TRPV1 expression was increased within the corpus callosum during demyelination in a cuprizone (CPZ)-induced demyelination mouse model. TRPV1 deficiency exacerbated motor coordinative dysfunction and demyelination in CPZ-treated mice, whereas the TRPV1 agonist CAP improved the behavioral performance and facilitated remyelination. TRPV1 was predominantly expressed in Iba1 + microglia/macrophages in human brain sections of multiple sclerosis patients and mouse corpus callosum under demyelinating conditions. TRPV1 deficiency decreased microglial recruitment to the corpus callosum, with an associated increase in the accumulation of myelin debris. Conversely, the activation of TRPV1 by CAP enhanced the recruitment of microglia to the corpus callosum and potentiated myelin debris clearance. Using real-time live imaging we confirmed an increased phagocytic function of microglia following CAP treatment. In addition, the expression of the scavenger receptor CD36 was increased, and that of the glycolysis regulators Hif1a and Hk2 was decreased. We conclude that TRPV1 is an important regulator of microglial function in the context of demyelination and may serve as a promising therapeutic target for demyelinating diseases such as multiple sclerosis., (© 2022. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.)

Multiple sclerosis is a chronic neuroinflammatory demyelinating disease of the central nervous system (CNS) of unknown etiology and still incompletely clarified pathogenesis. The disease is generally considered a disorder resulting from a complex interplay between environmental risk factors and predisposing causal genetic variants. To examine the etiopathogenesis of the disease, two complementary pre-clinical models are currently discussed: the "outside-in" model proposing a peripherally elicited inflammatory/autoimmune attack against degraded myelin as the cause of the disease, and the "inside-out" paradigm implying a primary cytodegenerative process of cells in the CNS that triggers secondary reactive inflammatory/autoimmune responses against myelin debris. In this review, the integrating pathogenetic role of damage-associated molecular patterns (DAMPs) in these two scenario models is examined by focusing on the origin and sources of these molecules, which are known to promote neuroinflammation and, via activation of pattern recognition receptor-bearing antigen-presenting cells, drive and shape autoimmune responses. In particular, environmental factors are discussed that are conceptually defined as agents which produce endogenous DAMPs via induction of regulated cell death (RCD) or act themselves as exogenous DAMPs. Indeed, in the field of autoimmune diseases, including multiple sclerosis, recent research has focused on environmental triggers that cause secondary events in terms of subroutines of RCD, which have been identified as prolific sources of DAMPs. Finally, a model of a DAMP-driven positive feed-forward loop of chronic inflammatory demyelinating processes is proposed, aimed at reconciling the competing "inside-out" and "outside-in" paradigms., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Multiple sclerosis (MS) is a systemic inflammatory illness of the central nervous system that involves demyelinating lesions in the myelin-rich white matter and pathology in the grey matter. Despite significant advancements in drug research for MS, the disease's complex pathophysiology makes it difficult to treat the progressive forms of the disease. In this study, we identified a natural flavonoid compound icariin (ICA) as a potent effective agent for MS in ameliorating the deterioration of symptoms including the neurological deficit score and the body weight in a murine experimental autoimmune encephalomyelitis (EAE) model. These improvements were associated with decreased demyelination in the corpus callosum and neuron loss in the hippocampus and cortex confirmed by immunohistochemistry analysis. Meanwhile, it was observed that the activation of microglia in cerebral cortex and hippocampus were inhibited followed by the neuroinflammatory cytokines downregulation such as IL-1β, IL-6 and TNF-α after ICA treatment, which was probably attributable to the suppression of microglial NLRP3 inflammasome activation. Additionally, molecular docking also revealed the binding force of ICA to NLRP3 inflammasome protein complexes in vitro. Taken together, our findings have demonstrated that ICA, as pleiotropic agent, prevents EAE-induced MS by improving demyelination and neuron loss, which interferes with the neuroinflammation via microglial NLRP3 inflammasome activation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

All currently licensed medications for multiple sclerosis (MS) target the immune system. Albeit promising preclinical results demonstrated disease amelioration and remyelination enhancement via modulating oligodendrocyte lineage cells, most drug candidates showed only modest or no effects in human clinical trials. This might be due to the fact that remyelination is a sophistically orchestrated process that calls for the interplay between oligodendrocyte lineage cells, neurons, central nervous system (CNS) resident innate immune cells, and peripheral immune infiltrates and that this process may somewhat differ in humans and rodent models used in research. To ensure successful remyelination, the recruitment and activation/repression of each cell type should be regulated in a highly organized spatio-temporal manner. As a result, drug candidates targeting one single pathway or a single cell population have difficulty restoring the optimal microenvironment at lesion sites for remyelination. Therefore, when exploring new drug candidates for MS, it is instrumental to consider not only the effects on all CNS cell populations but also the optimal time of administration during disease progression. In this review, we describe the dysregulated mechanisms in each relevant cell type and the disruption of their coordination as causes of remyelination failure, providing an overview of the complex cell interplay in CNS lesion sites.

RNA oxidation has been implicated in neurodegeneration, but the underlying mechanism for such effects is unclear. Extensive RNA oxidation occurs within the neurons in multiple sclerosis (MS) brains. Here, we identified selectively oxidized mRNAs in neuronal cells that pertained to neuropathological pathways. N-acetyl aspartate transferase 8 like (NAT8L) is one such transcript, whose translation product enzymatically synthesizes N-acetyl aspartic acid (NAA), a neuronal metabolite important for myelin synthesis. We reasoned that impediment of translation of an oxidized NAT8L mRNA will result in a reduction in its cognate protein, thus lowering the NAA level. This hypothesis is supported by our studies on cells, an animal model, and postmortem human MS brain. Reduced brain NAA level hampers myelin integrity making neuronal axons more susceptible to damage, which contributes to MS neurodegeneration. Overall, this work provides a framework for a mechanistic understanding of the link between RNA oxidation and neurodegeneration., Competing Interests: Declaration of interests The authors declare no competing interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Multiple sclerosis (MS) is a CNS inflammatory demyelinating disease. Recent investigations highlight the gut-brain axis as a communication network with crucial implications in neurological diseases. Thus, disrupted intestinal integrity allows the translocation of luminal molecules into systemic circulation, promoting systemic/brain immune-inflammatory responses. In both, MS and its preclinical model, the experimental autoimmune encephalomyelitis (EAE) gastrointestinal symptoms including "leaky gut" have been reported. Oleacein (OLE), a phenolic compound from extra virgin olive oil or olive leaves, harbors a wide range of therapeutic properties. Previously, we showed OLE effectiveness preventing motor defects and inflammatory damage of CNS tissues on EAE mice. The current studies examine its potential protective effects on intestinal barrier dysfunction using MOG 35-55 -induced EAE in C57BL/6 mice. OLE decreased EAE-induced inflammation and oxidative stress in the intestine, preventing tissue injury and permeability alterations. OLE protected from EAE-induced superoxide anion and accumulation of protein and lipid oxidation products in colon, also enhancing its antioxidant capacity. These effects were accompanied by reduced colonic IL-1β and TNFα levels in OLE-treated EAE mice, whereas the immunoregulatory cytokines IL-25 and IL-33 remained unchanged. Moreover, OLE protected the mucin-containing goblet cells in colon and the serum levels of iFABP and sCD14, markers that reflect loss of intestinal epithelial barrier integrity and low-grade systemic inflammation, were significantly reduced. These effects on intestinal permeability did not draw significant differences on the abundance and diversity of gut microbiota. However, OLE induced an EAE-independent raise in the abundance of Akkermansiaceae family. Consistently, using Caco-2 cells as an in vitro model, we confirmed that OLE protected against intestinal barrier dysfunction induced by harmful mediators present in both EAE and MS. This study proves that the protective effect of OLE in EAE also involves normalizing the gut alterations associated to the disease.

Background: Although distinct brain-homing B cells have been identified in multiple sclerosis (MS), it is unknown how these further evolve to contribute to local pathology. We explored B-cell maturation in the central nervous system (CNS) of MS patients and determined their association with immunoglobulin (Ig) production, T-cell presence, and lesion formation., Methods: Ex vivo flow cytometry was performed on post-mortem blood, cerebrospinal fluid (CSF), meninges and white matter from 28 MS and 10 control brain donors to characterize B cells and antibody-secreting cells (ASCs). MS brain tissue sections were analysed with immunostainings and microarrays. IgG index and CSF oligoclonal bands were measured with nephelometry, isoelectric focusing, and immunoblotting. Blood-derived B cells were cocultured under T follicular helper-like conditions to evaluate their ASC-differentiating capacity in vitro., Findings: ASC versus B-cell ratios were increased in post-mortem CNS compartments of MS but not control donors. Local presence of ASCs associated with a mature CD45 low phenotype, focal MS lesional activity, lesional Ig gene expression, and CSF IgG levels as well as clonality. In vitro B-cell maturation into ASCs did not differ between MS and control donors. Notably, lesional CD4 + memory T cells positively correlated with ASC presence, reflected by local interplay with T cells., Interpretation: These findings provide evidence that local B cells at least in late-stage MS preferentially mature into ASCs, which are largely responsible for intrathecal and local Ig production. This is especially seen in active MS white matter lesions and likely depends on the interaction with CD4 + memory T cells., Funding: Stichting MS Research (19-1057 MS; 20-490f MS), National MS Fonds (OZ2018-003)., Competing Interests: Declaration of interests M.M.v.L. received research support from EMD Serono, Merck, GSK and Idorsia Pharmaceutical Ltd. J.S. received lecture and/or consultancy fees from Biogen, Merck, Novartis and Sanofi-Genzyme. The remaining authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Multiple sclerosis (MS) is a demyelinating disease caused by auto-antigen recognizing CD4 + T cells. However, IL-17A-producing CD4 + T cells that are bystander-activated by IL-1β and IL-23, and T cell receptors independently, could contribute to experimental autoimmune encephalomyelitis. Here, we studied the differences in the frequency and function of bystander-activated CD4 + T cells in patients with MS. A significantly higher frequency of CD4 + IL-1Rl + T cells was found in memory than in naïve CD4 + T cells and in Th17/Th17.1 than in Th1/Th2 subtypes in both MS and healthy controls (HC). Following IL-1β and IL-23 stimulation, IL-1Rl expression was markedly increased in both memory and Th17/Th17.1 cells, and their IL-17A-production was increased after bystander-activation, which was significantly higher in MS compared with HC. Our study suggests a potential role of IL-17A-producing bystander-activated CD4 + IL-1Rl + T cells in MS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.)

Extracellular vesicles (EVs) are a heterogeneous family of extracellular structures bounded by a phospholipid bilayer, released by all cell types in various biological fluids, such as blood and cerebrospinal fluid (CSF), playing important roles in intercellular communication, both locally and systemically. EVs carry and deliver a variety of bioactive molecules (proteins, nucleic acids, lipids and metabolites), conferring epigenetic and phenotypic changes to the recipient cells and thus resulting as important mediators of both homeostasis and pathogenesis. In neurological diseases, such as multiple sclerosis (MS), the EV ability to cross Blood-Brain Barrier (BBB), moving from central nervous system (CNS) to the peripheral circulation and vice versa, has increased the interest in EV study in the neurological field. In the present review, we will provide an overview of the recent advances made in understanding the pathogenic role of EVs regarding the immune response, the BBB dysfunction and the CNS inflammatory processes., Competing Interests: Declaration of Competing Interest “The authors declare no conflict of interest.”, (Copyright © 2023 Elsevier B.V. All rights reserved.)

Hormonal imbalance may be an important factor in the severity of multiple sclerosis (MS) disease. In this context, hormone therapy has been shown to have immunoregulatory potential in various experimental approaches. There is increasing evidence of potentially beneficial effects of thyroid, melatonin, and sex hormones in MS models. These hormones may ameliorate the neurological impairment through immunoregulatory and neuroprotective effects, as well as by reducing oxidative stress. Expanding our knowledge of hormone therapy may be an effective step toward identifying additional molecular/cellular pathways in MS disease. In this review, we discuss the role of several important hormones in MS pathogenesis in terms of their effects on immunoregulatory aspects and neuroprotection., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

There is vast evidence for the effect of NOD-like receptor protein-3 (NLRP3) inflammasome on multiple sclerosis (MS) pathogenesis. Clemastine (CLM) targets NLRP3 in hypoxic brain injury and promotes oligodendrocyte differentiation. However, no previous study pointed to the link of CLM with inflammasome components in MS. Herein, the study aimed to verify the action of CLM on NLRP3 signaling in experimental autoimmune encephalomyelitis (EAE) as an MS rat model. Homogenate of spinal cord with complete Freund's adjuvant was administered on days 0 and 7 to induce EAE. Rats received either CLM (5 mg/kg/day; p.o.) or MCC950 (2.5 mg/kg/day; i.p) for 15 days starting from the first immunization day. In EAEs' brains, NLRP3 pathway components; total and phosphorylated p38 mitogen-activated protein kinase (MAPK), apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, interleukins 1β and -18 along with pyroptotic marker; gasdermin D (GSDMD) were upregulated. These were accompanied with diminished nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and total antioxidant capacity levels. CLM improved these perturbations as well as signs of MS; weight loss, clinical scores, and motor disorders observed in the open field, hanging wire and rotarod tests. Histopathological examinations revealed improvement in H&E abnormalities and axonal demyelination as shown by luxol fast blue stain in lumbar sections of spinal cord. These CLM's actions were studied in comparison to MCC950 as a well-established selective blocker of the NLRP3 inflammasome. Conclusively, CLM has a protective role against neuroinflammation and demyelination in EAE via its anti-inflammatory and anti-pyroptotic actions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Multiple sclerosis (MS) is an aggressive disease characterized by central nervous system (CNS) inflammatory and demyelinating lesions. Tolerance failure is implicated in the development of several autoimmune disorders, including MS. Due to their involvement in maintaining environmental tolerance, regulatory T cells (Tregs) are regarded as efficient immune cells. We examined the frequency of Tregs in this study using CD4/CD25/forkhead box protein P3 (FOXP3)/Helios markers., Methods: Fifty participants, including 25 patients with secondary progressive MS (SPMS) and 25 healthy controls (HCs), were enrolled in this study, and their demographic characteristics were recorded. Peripheral blood samples ranging from 5 to 6 mL were obtained, and the Ficoll technique was used to extract peripheral blood mononuclear cells (PBMCs). Then, the percentage of CD4 + CD25 + FOXP3 + Helios + regulatory T lymphocytes was examined by flow cytometry in the study groups. Real-time polymerase chain reaction (PCR) was also used to assess the Helios gene expression level., Results: This study showed that the percentage of Tregs with CD4 and CD25 markers did not reveal a significant difference compared with HCs despite the decrease in SPMS patients (P = 0.6). However, lymphocytes with CD4/CD25/FOXP3/Helios markers were significantly reduced in the patients (P = 0.01). Additionally, SPMS patients had statistically significantly lower Helios gene expression levels (P = 0.002)., Conclusion: In SPMS patients, a decrease in the frequency of the CD4 + CD25 + FOXP3 + Helios + Treg population can result in an imbalanced immune system. In other words, one of the immunological mechanisms involved in this disease may be a deficiency in Tregs. Helios gene expression was also decreased in these patients, which may exacerbate functional defects in Tregs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by focal inflammatory lesions and prominent demyelination. Even though the currently available therapies are effective in treating the initial stages of disease, they are unable to halt or reverse disease progression into the chronic progressive stage. Thus far, no repair-inducing treatments are available for progressive MS patients. Hence, there is an urgent need for the development of new therapeutic strategies either targeting the destructive immunological demyelination or boosting endogenous repair mechanisms. Using in vitro, ex vivo, and in vivo models, we demonstrate that selective inhibition of phosphodiesterase 4 (PDE4), a family of enzymes that hydrolyzes and inactivates cyclic adenosine monophosphate (cAMP), reduces inflammation and promotes myelin repair. More specifically, we segregated the myelination-promoting and anti-inflammatory effects into a PDE4D- and PDE4B-dependent process respectively. We show that inhibition of PDE4D boosts oligodendrocyte progenitor cells (OPC) differentiation and enhances (re)myelination of both murine OPCs and human iPSC-derived OPCs. In addition, PDE4D inhibition promotes in vivo remyelination in the cuprizone model, which is accompanied by improved spatial memory and reduced visual evoked potential latency times. We further identified that PDE4B-specific inhibition exerts anti-inflammatory effects since it lowers in vitro monocytic nitric oxide (NO) production and improves in vivo neurological scores during the early phase of experimental autoimmune encephalomyelitis (EAE). In contrast to the pan PDE4 inhibitor roflumilast, the therapeutic dose of both the PDE4B-specific inhibitor A33 and the PDE4D-specific inhibitor Gebr32a did not trigger emesis-like side effects in rodents. Finally, we report distinct PDE4D isoform expression patterns in human area postrema neurons and human oligodendroglia lineage cells. Using the CRISPR-Cas9 system, we confirmed that pde4d1/2 and pde4d6 are the key targets to induce OPC differentiation. Collectively, these data demonstrate that gene specific PDE4 inhibitors have potential as novel therapeutic agents for targeting the distinct disease processes of MS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Multiple sclerosis is a chronic demyelinating autoimmune disease accompanied by inflammation and loss of axons and neurons. Toll-like receptors play crucial roles in the innate immune system and inflammation. However, few studies have explored the specific effects of toll-like receptor 7 signaling pathway in multiple sclerosis. To explore underlying effects to develop a new therapeutic target, we use Vesatolimod, a safe and well-tolerated agonist of toll-like receptor 7, to assess the possible effects in Experimental autoimmune encephalomyelitis (EAE) animal model., Methods: EAE animal model was induced by injection of MOG35-55 and monitored daily for clinical symptoms, and the treatment group was given Vesatolimod at the onset of illness. The therapeutic effects of Vesatolimod on EAE inflammation, demyelination, CD107b cells and T cells infiltration, and microglia activation was evaluated. Autophagy within the spinal cords of EAE mice was also preliminarily assessed., Results: Treatment with Vesatolimod significantly alleviated clinical symptoms of EAE from day 18 post-immunization and decreased the expression levels of inflammatory cytokines, particularly Eotaxin and IL-12 (P40), in peripheral blood. It also inhibited demyelination in spinal cords. Moreover, VES treatment reduced activation of microglia, infiltration of CD3 + T cells and CD107b + cells, as well as inhibited the autophagy-related proteins expression in the spinal cords of EAE mice., Conclusion: Our results indicate that Vesatolimod exhibits protective effects on EAE mice and is promising for treatment of MS., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)