Anti- and pro-inflammatory milieu differentially regulate differentiation and immune functions of oligodendrocyte progenitor cells.

Oligodendrocyte progenitor cells (OPCs) were regarded for years solely for their regenerative role; however, their immune-modulatory roles have gained much attention recently, particularly in the context of multiple sclerosis (MS). Despite extensive studies on OPCs, there are limited data elucidating the interactions between their intrinsic regenerative and immune functions, as well as their relationship with the inflamed central nervous system (CNS) environment, a key factor in MS pathology. We examined the effects of pro-inflammatory cytokines, represented by interferon (IFN)-γ and tumour necrosis factor (TNF)-α, as well as anti-inflammatory cytokines, represented by interleukin (IL)-4 and IL-10, on OPC differentiation and immune characteristics. Using primary cultures, enzyme-linked immunosorbent assay and immunofluorescence stainings, we assessed differentiation capacity, phagocytic activity, major histocompatibility complex (MHC)-II expression, and cytokine secretion. We observed that the anti-inflammatory milieu (IL4 and IL10) reduced both OPC differentiation and immune functions. Conversely, exposure to TNF-α led to intact differentiation, increased phagocytic activity, high levels of MHC-II expression, and cytokines secretion. Those effects were attributed to signalling via TNF-receptor-2 and counteracted the detrimental effects of IFN-γ on OPC differentiation. Our findings suggest that a pro-regenerative, permissive inflammatory environment is needed for OPCs to execute both regenerative and immune-modulatory functions.

Oligodendrocyte progenitor cells differentiation induction with MAPK/ERK inhibitor fails to support repair processes in the chronically demyelinated CNS.

Remyelination failure is considered a major obstacle in treating chronic-progressive multiple sclerosis (MS). Studies have shown blockage in the differentiation of resident oligodendrocyte progenitor cells (OPC) into myelin-forming cells, suggesting that pushing OPC into a differentiation program might be sufficient to overcome remyelination failure. Others stressed the need for a permissive environment to allow proper activation, migration, and differentiation of OPC. PD0325901, a MAPK/ERK inhibitor, was previously shown to induce OPC differentiation, non-specific immunosuppression, and a significant therapeutic effect in acute demyelinating MS models. We examined PD0325901 effects in the chronically inflamed central nervous system. Treatment with PD0325901 induced OPC differentiation into mature oligodendrocytes with high morphological complexity. However, treatment of Biozzi mice with chronic-progressive experimental autoimmune encephalomyelitis with PD0325901 showed no clinical improvement in comparison to the control group, no reduction in demyelination, nor induction of OPC migration into foci of demyelination. PD0325901 induced a direct general immunosuppressive effect on various cell populations, leading to a diminished phagocytic capability of microglia and less activation of lymph-node cells. It also significantly impaired the immune-modulatory functions of OPC. Our findings suggest OPC regenerative function depends on a permissive environment, which may include pro-regenerative inflammatory elements. Furthermore, they indicate that maintaining a delicate balance between the pro-myelinating and immune functions of OPC is of importance. Thus, the highly complex mission of creating a pro-regenerative environment depends upon an appropriate immune response controlled in time, place, and intensity. We suggest the need to employ a multi-systematic therapeutic approach, which cannot be achieved through a single molecule-based therapy.

Severe Acute Respiratory Syndrome Coronavirus 2 Third Vaccine Immune Response in Multiple Sclerosis Patients Treated with Ocrelizumab.

The introduction of a third-dose vaccination along with new variants of concern raises questions regarding serology and T-cell responses in patients with multiple sclerosis (pwMS) treated with B-cell depletion who develop attenuated humoral response to vaccines. The aim of this study was to longitudinally evaluate humoral and cellular response to SARS-CoV-2 mRNA vaccine in ocrelizumab-treated pwMS before and following a third vaccine dose. Following the third vaccine dose, patients who are low or nonresponders following initial vaccination did not increase antibody titers. In healthy controls and ocrelizumab-treated pwMS, cellular response decreased 6 months after initial vaccination and increased significantly after the third dose. ANN NEUROL 2022;91:796-800.

Brain MRI activity during the year before pregnancy can predict long-term clinical worsening in patients with Multiple Sclerosis.

BACKGROUND: Pregnancy has been observed to reduce the frequency of relapses in Multiple Sclerosis (MS) patients, but the relapse risk tends to increase during the early post-partum period. Increased pre- and post-partum disease activity may predict a poor long-term prognosis. This study aimed to evaluate the correlation between magnetic resonance imaging (MRI) activity during the year before pregnancy and long-term clinically meaningful worsening in Expanded Disability Status Scale (EDSS). METHODS: This observational, retrospective, case-control study included 141 pregnancies in 99 females with MS. Statistical analyses were used to evaluate the correlation between MRI activity during the year pre-pregnancy and post-partum clinical worsening during a 5-year follow-up. Clustered logistic regression was used to investigate the predictors of 5-year clinically meaningful worsening in EDSS (lt-EDSS). RESULTS: We found a significant correlation between an active MRI pre-pregnancy and lt-EDSS (p = 0.0006). EDSS pre-pregnancy and lt-EDSS were also significantly correlated (p = 0.043). Using a multivariate model, we predicted which females would not experience long-term clinical deterioration by a stable MRI pre-pregnancy (92.7% specificity; p = 0.004). CONCLUSIONS: An active MRI pre-conception is a strong predictor of lt-EDSS and a higher annual relapse rate during the follow-up period, regardless of whether the female had clinical evidence of disease activity prior to conception and delivery. Optimizing disease control and achieving imaging stability prior to conception may reduce the risk of long-term clinical deterioration.

Cerebrospinal fluid of progressive multiple sclerosis patients reduces differentiation and immune functions of oligodendrocyte progenitor cells.

Oligodendrocyte progenitor cells (OPCs) are responsible for remyelination in the central nervous system (CNS) in health and disease. For patients with multiple sclerosis (MS), remyelination is not always successful, and the mechanisms differentiating successful from failed remyelination are not well-known. Growing evidence suggests an immune role for OPCs, in addition to their regenerative role; however, it is not clear if this helps or hinders the regenerative process. We studied the effect of cerebrospinal fluid (CSF) from relapsing MS (rMS) and progressive MS (pMS) patients on primary OPC differentiation and immune gene expression and function. We observed that CSF from either rMS or pMS patients has a differential effect on the ability of mice OPCs to differentiate into mature oligodendrocytes and to express immune functions. CSF of pMS patients impaired differentiation into mature oligodendrocytes. In addition, it led to decreased major histocompatibility complex class (MHC)-II expression, tumor necrosis factor (TNF)-α secretion, nuclear factor kappa-B (NFκB) activation, and less activation and proliferation of T cells. Our findings suggest that OPCs are not only responsible for remyelination, but they may also play an active role as innate immune cells in the CNS.

The risk of infections for multiple sclerosis and neuromyelitis optica spectrum disorder disease-modifying treatments: Eighth European Committee for Treatment and Research in Multiple Sclerosis Focused Workshop Review. April 2021.

Over the recent years, the treatment of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) has evolved very rapidly and a large number of disease-modifying treatments (DMTs) are now available. However, most DMTs are associated with adverse events, the most frequent of which being infections. Consideration of all DMT-associated risks facilitates development of risk mitigation strategies. An international focused workshop with expert-led discussions was sponsored by the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and was held in April 2021 to review our current knowledge about the risk of infections associated with the use of DMTs for people with MS and NMOSD and corresponding risk mitigation strategies. The workshop addressed DMT-associated infections in specific populations, such as children and pregnant women with MS, or people with MS who have other comorbidities or live in regions with an exceptionally high infection burden. Finally, we reviewed the topic of DMT-associated infectious risks in the context of the current SARS-CoV-2 pandemic. Herein, we summarize available evidence and identify gaps in knowledge which justify further research.

Sera of Neuromyelitis Optica Patients Increase BID-Mediated Apoptosis in Astrocytes.

Neuromyelitis optica (NMO) is a rare disease usually presenting with bilateral or unilateral optic neuritis with simultaneous or sequential transverse myelitis. Autoantibodies directed against aquaporin-4 (AQP4-IgG) are found in most patients. They are believed to cross the blood−brain barrier, target astrocytes, activate complement, and eventually lead to astrocyte destruction, demyelination, and axonal damage. However, it is still not clear what the primary pathological event is. We hypothesize that the interaction of AQP4-IgG and astrocytes leads to DNA damage and apoptosis. We studied the effect of sera from seropositive NMO patients and healthy controls (HCs) on astrocytes' immune gene expression and viability. We found that sera from seropositive NMO patients led to higher expression of apoptosis-related genes, including BH3-interacting domain death agonist (BID), which is the most significant differentiating gene (p < 0.0001), and triggered more apoptosis in astrocytes compared to sera from HCs. Furthermore, NMO sera increased DNA damage and led to a higher expression of immunological genes that interact with BID (TLR4 and NOD-1). Our findings suggest that sera of seropositive NMO patients might cause astrocytic DNA damage and apoptosis. It may be one of the mechanisms implicated in the primary pathological event in NMO and provide new avenues for therapeutic intervention.

Suppression of neuroinflammation by an allosteric agonist and positive allosteric modulator of the α7 nicotinic acetylcholine receptor GAT107.

BACKGROUND: The α7 nicotinic acetylcholine receptor (α7 nAChR) negatively regulates the synthesis and release of pro-inflammatory cytokines by immune cells. Our previous studies showed that in encephalitogenic T cells, α7 nAChR expression is upregulated and that activation of the cholinergic system can attenuate experimental autoimmune encephalomyelitis (EAE). GAT107 is an allosteric agonist and positive allosteric modulator (ago-PAM) of α7 nAChR that can produce persistent activation of this receptor. Therefore, in the present study, we investigated the effect of GAT107 on neuroinflammation in EAE, the animal model used for the study of multiple sclerosis (MS) via α7 nAChR, and the inflammatory pathways involved. METHODS: EAE was induced by administration of myelin oligodendrocyte glycoprotein (MOG35-55) in C57BL/6 mice. EAE mice were treated with the ago-PAM GAT107 or a placebo for 9 days, starting from the day of EAE induction. Clinical assessment and immunological evaluation of immune cells and cytokine production was performed. RESULTS: Following activation of the α7 nAChR by GAT107 during EAE, disease severity was significantly reduced by 70% and was correlated with a reduction in the extent of neuroinflammation in the CNS. The treatment reduced encephalitogenic T cell proliferation and the production of pro-inflammatory cytokines, as well as increased the production of the anti-inflammatory cytokine IL-10. Furthermore, the expression of immune cell markers was altered by GAT107 treatment, which induced a significant reduction in macrophages, dendritic cells, and B cells, as well as a reduction in anti-MOG35-55 antibodies. Additionally, GAT107 was found to directly activate α7 nAChR in murine macrophage RAW264.7 cells and in human PBMCs derived from MS patients and healthy donors. CONCLUSIONS: Our results show that GAT107 can be a useful molecule for harnessing the cholinergic anti-inflammatory pathway for long-lasting and wide-ranging modulation and downregulation of neuroinflammation in EAE.

Brain MRI activity during the year before pregnancy can predict post-partum clinical relapses.

BACKGROUND: There are fewer multiple sclerosis (MS) relapses during pregnancy, although relapse risk increases in the early post-partum period, as has been predicted by pre-pregnancy or pregnancy disease activity in some studies. OBJECTIVE: The aim of this study was to evaluate the correlation between magnetic resonance imaging (MRI) changes in the year before pregnancy and the relapse rate in the year post-partum. METHODS: An observational retrospective case-control study included 172 pregnancies in 118 females with MS. Statistical analyses were used to evaluate the correlation between MRI and post-partum relapses. Clustered logistic regression was used to investigate the predictors of early post-partum relapses. RESULTS: We found a significant correlation for an active-MRI pre-pregnancy and relapses in the first 3 months post-partum (p < 0.001). Expanded Disability Status Scale (EDSS) pre-pregnancy and relapses in the first 3 months post-partum were also significantly correlated (p = 0.009). Using a multivariate model, we predicted which women will not experience post-partum relapse by EDSS and by an active-MRI pre-pregnancy (96.7% specificity; p < 0.001). CONCLUSION: An active-MRI pre-pregnancy is a strong and sensitive predictor of early post-partum relapse, regardless of whether the woman had clinical evidence of disease activity prior to conception and delivery. This finding could provide clinicians with a strategy to minimize post-partum relapse risk in women with MS planning pregnancy.

Neuroinflammation Modulation via α7 Nicotinic Acetylcholine Receptor and Its Chaperone, RIC-3.

Nicotinic acetylcholine receptors (nAChRs) are widely expressed in or on various cell types and have diverse functions. In immune cells nAChRs regulate proliferation, differentiation and cytokine release. Specifically, activation of the α7 nAChR reduces inflammation as part of the cholinergic anti-inflammatory pathway. Here we review numerous effects of α7 nAChR activation on immune cell function and differentiation. Further, we also describe evidence implicating this receptor and its chaperone RIC-3 in diseases of the central nervous system and in neuroinflammation, focusing on multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Deregulated neuroinflammation due to dysfunction of α7 nAChR provides one explanation for involvement of this receptor and of RIC-3 in neurodegenerative diseases. In this review, we also provide evidence implicating α7 nAChRs and RIC-3 in neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) involving neuroinflammation. Besides, we will describe the therapeutic implications of activating the cholinergic anti-inflammatory pathway for diseases involving neuroinflammation.

Lack of association between unipolar or bipolar depression and serum aquaporin-4 autoantibodies.

Aquaporin-4 (AQP4), an astrocyte water channel protein, is the target antigen of serum immunoglobulin G (IgG) autoantibody in neuromyelitis optica spectrum disorders (NMOsd), a group of inflammatory, demyelinating diseases of the central nervous system. Recently, a reduction in blood vessels coverage by AQP4-immunoreactive astrocytes was demonstrated in depressed patients, indicating a role for AQP4 in mood disorders. Moreover, a possible association between depression and serum AQP4-IgG was suggested in a case report of a treatment resistant depression (TRD) patient diagnosed with NMOsd with positive serum AQP4 autoantibodies. We investigated, for the first time, the presence of serum AQP4-IgG in patients with unipolar and bipolar depression and healthy controls (HCs). In this multicenter study, 25 major depressive disorder (MDD) and 25 bipolar disorder (BD) patients, during an acute major depressive episode (MDE), and 30 matched HCs were screened for the presence of serum AQP4-IgG, using a cell-based assay. The MDE patients underwent a repeated AQP4-IgG assessment at a 3-month follow-up visit. The MDE group (N = 50) had illness duration of 12.7 years (SD = 10.5), 12% of them were psychotropic medication-free and 26% were defined as TRD. All MDE patients and HCs, including three BD patients who experienced a manic switch, were seronegative for AQP4-IgG at baseline and follow-up assessments. In conclusion, contrary to our hypothesis, AQP4 autoantibodies were not detected in serum of unipolar and bipolar depressed patients. However, AQP4 may still play a role in the pathogenesis of mood disorders through different mechanisms of action such as altered brain AQP4 expression.

MicroRNA signature associated with treatment response in myasthenia gravis: A further step towards precision medicine.

Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular transmission currently treated with chronic immunosuppression. Inter-subject variation in treatment response and side effects highlight the need for personalized therapies by identification of biomarkers predictive of drug efficacy in individual patients, still lacking in MG. MicroRNAs (miRNAs) play a key role in immune response and drug metabolism modulation. This study, part of an Italian-Israeli collaborative project, aimed to identify specific miRNAs as biomarkers associated with immunosuppressive treatment response in MG patients. Whole miRNome sequencing, followed by miRNA validation by real-time PCR, was performed in peripheral blood from Italian MG patients (n = 40) classified as responder and non-responder to immunosuppressive therapies. MiRNA sequencing identified 41 miRNAs differentially expressed in non-responder compared to responder Italian MG patients. Validation phase pointed out three miRNAs, miR-323b-3p, -409-3p, and -485-3p, clustered on chromosome 14q32.31, the levels of which were significantly decreased in non-responder versus responder patients, whereas miR-181d-5p and -340-3p showed an opposite trend. ROC curve analysis showed sensitivity and specificity performance results indicative of miR-323b-3p, -409-3p, and -485-3p predictive value for responsiveness to immunosuppressive drugs in MG. Validated miRNAs were further analyzed in blood from responder and non-responder MG patients of the Israeli population (n = 33), confirming a role for miR-323b-3p, -409-3p, -485-3p, -181d-5p and -340-3p as biomarkers of drug efficacy. Gene Ontology enrichment analysis, mRNA target prediction, and in silico modeling for function of the identified miRNAs disclosed functional involvement of the five miRNAs, and their putative target genes, in both immune (i.e. neurotrophin TRK and Fc-epsilon receptor signaling pathways) and drug metabolism processes. Our overall findings thus revealed a blood "miR-323b-3p, -409-3p, -485-3p, -181d-5p, and -340-3p" signature associated with drug responsiveness in MG patients. Its identification sets the basis for precision medicine approaches based on "pharmacomiRs" as biomarkers of drug responsiveness in MG, promising to improve therapeutic success in a cost/effective manner.

Identification of tissue-specific cell death using methylation patterns of circulating DNA.

Minimally invasive detection of cell death could prove an invaluable resource in many physiologic and pathologic situations. Cell-free circulating DNA (cfDNA) released from dying cells is emerging as a diagnostic tool for monitoring cancer dynamics and graft failure. However, existing methods rely on differences in DNA sequences in source tissues, so that cell death cannot be identified in tissues with a normal genome. We developed a method of detecting tissue-specific cell death in humans based on tissue-specific methylation patterns in cfDNA. We interrogated tissue-specific methylome databases to identify cell type-specific DNA methylation signatures and developed a method to detect these signatures in mixed DNA samples. We isolated cfDNA from plasma or serum of donors, treated the cfDNA with bisulfite, PCR-amplified the cfDNA, and sequenced it to quantify cfDNA carrying the methylation markers of the cell type of interest. Pancreatic ß-cell DNA was identified in the circulation of patients with recently diagnosed type-1 diabetes and islet-graft recipients; oligodendrocyte DNA was identified in patients with relapsing multiple sclerosis; neuronal/glial DNA was identified in patients after traumatic brain injury or cardiac arrest; and exocrine pancreas DNA was identified in patients with pancreatic cancer or pancreatitis. This proof-of-concept study demonstrates that the tissue origins of cfDNA and thus the rate of death of specific cell types can be determined in humans. The approach can be adapted to identify cfDNA derived from any cell type in the body, offering a minimally invasive window for diagnosing and monitoring a broad spectrum of human pathologies as well as providing a better understanding of normal tissue dynamics.

[AUTOIMMUNE ENCEPHALITIS: A BRIDGE BETWEEN NEUROLOGY AND PSYCHIATRY].

INTRODUCTION: Autoimmune encephalitis (AIE) usually manifests as an acute illness with psychosis, seizures and an amnestic disorder, although the clinical spectrum extends beyond this triad. The discovery of novel cell surface antibodies and antibodies directed at ion channels has revolutionized our understanding of the pathophysiology of the disease and the diagnostic tools at hand. Early diagnosis is crucial to initiation of treatment early in the disease course, which ameliorates the neurological outcome. OBJECTIVES: To delineate the clinical, imaging and laboratory characteristics of patients with AIE, as reflected in the cohort of limbic encephalitis patients treated in our department. METHODS: Patients diagnosed with AIE in our department in 2008-2018 were included in this retrospective study. All patients met the criteria for clinically probable or definite AIE, based on their clinical, laboratory and imaging findings, and the identification of causative autoantibodies. RESULTS: A total of 27 patients with a diagnosis of AIE were diagnosed and treated in our department in 2008-2018; 74% had an amnestic disorder and 70% developed seizures. Psychosis was observed in 37%, though 63% showed behavioral changes; 59% had clinically relevant autoantibodies in their cerebrospinal fluid (CSF). Approximately half had pathologic brain imaging (59%) and only 33% had CSF pleocytosis. Despite immunosuppressive treatment, residual neurologic deficits were seen in the majority of the patients. DISCUSSION: The diagnosis of AIE relies mainly on the clinical presentation, with normal ancillary studies in many cases. Thus, high clinical suspicion and prompt initiation of treatment despite lack of objective evidence of the diagnosis are necessary to limit the neurological sequela. Moreover, high awareness of AIE may allow appropriate workup and diagnosis in atypical cases.

Circulating microRNAs as biomarkers for rituximab therapy, in neuromyelitis optica (NMO).

BACKGROUND: Neuromyelitis optica (NMO) is a chronic autoimmune disease of the central nervous system (CNS). The main immunological feature of the disease is the presence of autoantibodies to Aquaporin 4 (AQP4+), identified in about 82 % of cases. Currently, there are no reliable biomarkers for monitoring treatment response in patients with NMO. In an effort to identify biomarkers, we analyzed microRNAs (miRNAs) in the blood of rituximab-treated NMO patients before and after therapy. METHODS: Total RNA extracted from whole blood of nine rituximab-responsive NMO patients before and 6 months following treatment was subjected to small RNAseq analysis. The study included an additional group of seven untreated AQP4+ seropositive NMO patients and 15 healthy controls (HCs). RESULTS: Fourteen miRNAs were up regulated and 32 were downregulated significantly in the blood of NMO patients following effective therapy with rituximab (all p < 0.05). Furthermore, we show that expression of 17 miRNAs was significantly higher and of 25 miRNAs was significantly lower in untreated NMO patients compared with HCs (all p < 0.05). Following rituximab treatment, the expression levels of 10 of the 17 miRNAs that show increased expression in NMO reverted to the levels seen in HCs. Six of these "normalized" miRNAs are known as brain-specific/enriched miRNAs. CONCLUSIONS: Specific miRNA signatures in whole blood of patients with NMO might serve as biomarkers for therapy response. Furthermore, monitoring the levels of brain-specific/enriched miRNAs in the blood might reflect the degree of disease activity in the CNS of inflammatory demyelinating disorders.

Increased anti-KIR4.1 antibodies in multiple sclerosis: could it be a marker of disease relapse?

BACKGROUND: Screening of putative autoimmune targets in multiple sclerosis (MS) revealed a proportion of patients carrying antibodies (Abs) against KIR4.1, a potassium channel that shares functional properties with AQP4. Both are localized at the perivascular astrocytic processes. AIMS: To measure anti-KIR4.1 Abs in the serum of MS and neuromyelitis optica (NMO) patients, and to identify the clinical and laboratory characteristics of patients harboring anti-KIR4.1 Abs. METHODS: We measured anti-KIR4.1 Abs in serum, using the peptide KIR4.1 (83-120) enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum levels of anti-KIR4.1 Abs were significantly higher in MS and NMO patients than in healthy controls (HCs); with Abs detected in 21 of 80, 10 of 45, and 2 of 32 individuals, respectively (MS versus HC, p < 0.05). The level of anti-KIR4.1 Abs was significantly higher during MS relapse, versus remission (p = 0.04). The clinical characteristics of our study patients did not vary based on KIR4.1 positivity. CONCLUSIONS: Anti-KIR4.1 Abs were found in similar proportions of patients with MS and NMO, at a significantly higher level than observed in HCs; consequently, the presence of Abs does not discriminate between these demyelinating diseases. However, anti-KIR4.1 Ab levels differed in MS patients during relapse and remission; as such, they may represent a marker of disease exacerbation.

NMO spectrum of disorders: a paradigm for astrocyte-targeting autoimmunity and its implications for MS and other CNS inflammatory diseases.

When studying a rare or orphan disease, we hope to shed light on more prevalent syndromes. Neuromyelitis optica (NMO), also known as Devic's disease, is a rare disease with a prevalence of about 4 in 100,000. Since 2005 when the anti-Aquaporin 4 (AQP4) NMO autoantibody was discovered by Lennon's group at the Mayo clinic, an enormous amount of data have been acquired on the pathogenesis of the disease. A review of the literature showed 47 relevant publications in 2004, compared with 353 in 2013. The auto-antigen AQP4 is expressed on the astrocytic foot processes suggesting a role for astrocytes in the pathogenesis of the disease. However, the astrocytes might play a more active role than has previously been suggested in the immune cascade of NMO pathology. Here we will review epidemiological, clinical diagnostic and therapeutic aspects of NMO and highlight the possible role of astrocytes as major direct and indirect players in the pathogenesis of NMO and related CNS inflammatory diseases.

The interplay of inflammation and remyelination: rethinking MS treatment with a focus on oligodendrocyte progenitor cells.

BACKGROUND: Multiple sclerosis (MS) therapeutic goals have traditionally been dichotomized into two distinct avenues: immune-modulatory-centric interventions and pro-regenerative strategies. Oligodendrocyte progenitor cells (OPCs) were regarded for many years solely in concern to their potential to generate oligodendrocytes and myelin in the central nervous system (CNS). However, accumulating data elucidate the multifaceted roles of OPCs, including their immunomodulatory functions, positioning them as cardinal constituents of the CNS's immune landscape. MAIN BODY: In this review, we will discuss how the two therapeutic approaches converge. We present a model by which (1) an inflammation is required for the appropriate pro-myelinating immune function of OPCs in the chronically inflamed CNS, and (2) the immune function of OPCs is crucial for their ability to differentiate and promote remyelination. This model highlights the reciprocal interactions between OPCs' pro-myelinating and immune-modulating functions. Additionally, we review the specific effects of anti- and pro-inflammatory interventions on OPCs, suggesting that immunosuppression adversely affects OPCs' differentiation and immune functions. CONCLUSION: We suggest a multi-systemic therapeutic approach, which necessitates not a unidimensional focus but a harmonious balance between OPCs' pro-myelinating and immune-modulatory functions.

Thyroid hormone dysfunction in MOGAD and other demyelinating diseases.

BACKGROUND: Thyroid hormones play a critical role in both neuronal and glial cell functions. Multiple sclerosis (MS) has increased co-occurrence with autoimmune thyroid diseases, and recent studies have suggested a potential link between neuromyelitis optica spectrum disorder (NMOSD) and thyroid hormones. However, no previous studies have examined the relationship between thyroid hormones and myelin oligodendrocyte glycoprotein-associated demyelination (MOGAD). METHODS: We investigated the role of thyroid hormones in central nervous system (CNS) autoimmune demyelinating diseases in 26 MOGAD patients, 52 NMOSD patients, 167 patients with MS, and 16 patients with other noninflammatory neurological disorders. Thyroid hormone levels and clinical data (Expanded Disability Status Scale [EDSS]) were analyzed. Volumetric brain information was determined in brain magnetic resonance imaging (MRI) using the MDbrain platform. RESULTS: MOGAD patients had significantly higher levels of free triiodothyronine (FT3) compared to NMOSD patients. No correlation was found between FT3 levels and disease severity or brain volume. Thyroid-stimulating hormone (TSH) levels did not differ significantly between the groups, but in NMOSD patients, higher TSH levels were associated with lower disability scores and increased brain volume. No significant differences in free thyroxine (FT4) levels were observed between the different groups, however, FT4 levels were significantly higher in relapsing versus monophasic MOGAD patients and increased FT4 levels were associated with a higher EDSS and lower brain volume in NMOSD patients. CONCLUSION: Our findings highlight the potential involvement of thyroid hormones specifically in MOGAD patients and other demyelinating CNS disorders. Understanding the role of thyroid hormones in relapsing vs monophasic MOGAD patients and in comparison to other demyelinating disorder could lead to the development of therapeutic interventions. Further studies are needed to explore the precise mechanisms and potential interventions targeting the thyroid axis as a treatment strategy.