Antibody-Mediated Depletion of Autoreactive T Lymphocytes through PD-1 Improves Disease Outcomes and Visualizes T Cell Activation in Experimental Autoimmune Encephalomyelitis.

Long-term therapeutic outcomes of multiple sclerosis (MS) remain hindered by the chronic nature of immune cell stimulation toward self-antigens. Development of novel methods to target and deplete autoreactive T lymphocytes remains an attractive target for therapeutics for MS. We developed a programmed cell death 1 (PD-1)-targeted radiolabeled mAb and assessed its ability to deplete activated PD-1+ T lymphocytes in vitro and its ability to reduce disease burden of the myelin oligodendrocyte glycoprotein 35-55 experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice. We also investigated the upregulation of PD-1 on infiltrating lymphocytes in an animal model of MS. Finally, we demonstrate the (to our knowledge) first reported positron-emission tomography/computed tomography imaging of activated PD-1+ cells in the EAE animal model of MS. We found that the 177Lu radioisotope-labeled anti-PD-1 mAb demonstrated significant in vitro cytotoxicity toward activated CD4+PD-1+ T lymphocytes and led to significant reduction in overall disease progression in the EAE animal model. Our results show high expression of PD-1 on infiltrating lymphocytes in the spinal cords of EAE diseased animals. Positron-emission tomography/computed tomography imaging of the anti-PD-1 mAb demonstrated significant uptake in the cervical draining lymph nodes highlighting accumulation of activated lymphocytes. Targeted depletion of T lymphocytes using T cell activation markers such as PD-1 may present a novel method to reduce autoimmune attack and inflammation in autoimmune diseases such as MS. Development of multimodal nuclear theranostic agents may present the opportunity to monitor T cell activation via imaging radioisotopes and simultaneously treat MS using therapeutic radioisotopes.

Regulation of stress granule formation in human oligodendrocytes.

Oligodendrocyte (OL) injury and subsequent loss is a pathologic hallmark of multiple sclerosis (MS). Stress granules (SGs) are membrane-less organelles containing mRNAs stalled in translation and considered as participants of the cellular response to stress. Here we show SGs in OLs in active and inactive areas of MS lesions as well as in normal-appearing white matter. In cultures of primary human adult brain derived OLs, metabolic stress conditions induce transient SG formation in these cells. Combining pro-inflammatory cytokines, which alone do not induce SG formation, with metabolic stress results in persistence of SGs. Unlike sodium arsenite, metabolic stress induced SG formation is not blocked by the integrated stress response inhibitor. Glycolytic inhibition also induces persistent SGs indicating the dependence of SG formation and disassembly on the energetic glycolytic properties of human OLs. We conclude that SG persistence in OLs in MS reflects their response to a combination of metabolic stress and pro-inflammatory conditions.

hnRNP A1 dysfunction alters RNA splicing and drives neurodegeneration in multiple sclerosis (MS).

Neurodegeneration is the primary driver of disease progression in multiple sclerosis (MS) resulting in permanent disability, creating an urgent need to discover its underlying mechanisms. Herein, we establish that dysfunction of the RNA binding protein heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) results in differential of binding to RNA targets causing alternative RNA splicing, which contributes to neurodegeneration in MS and its models. Using RNAseq of MS brains, we discovered differential expression and aberrant splicing of hnRNP A1 target RNAs involved in neuronal function and RNA homeostasis. We confirmed this in vivo in experimental autoimmune encephalomyelitis employing CLIPseq specific for hnRNP A1, where hnRNP A1 differentially binds and regulates RNA, including aberrantly spliced targets identified in human samples. Additionally, dysfunctional hnRNP A1 expression in neurons caused neurite loss and identical changes in splicing, corroborating hnRNP A1 dysfunction as a cause of neurodegeneration. Collectively, these data indicate hnRNP A1 dysfunction causes altered neuronal RNA splicing, resulting in neurodegeneration in MS.

Task-oriented exercise effects on walking and corticospinal excitability in multiple sclerosis: protocol for a randomized controlled trial.

BACKGROUND: Multiple sclerosis (MS) is a degenerative disease of the central nervous system (CNS) that disrupts walking function and results in other debilitating symptoms. This study compares the effects of 'task-oriented exercise' against 'generalized resistance and aerobic exercise' and a 'stretching control' on walking and CNS function in people with MS (PwMS). We hypothesize that task-oriented exercise will enhance walking speed and related neural changes to a greater extent than other exercise approaches. METHODS: This study is a single-blinded, three-arm randomized controlled trial conducted in Saskatchewan, Canada. Eligible participants are those older than 18 years of age with a diagnosis of MS and an expanded Patient-Determined Disease Steps (PDDS) score between 3 ('gait disability') and 6 ('bilateral support'). Exercise interventions are delivered for 12 weeks (3 × 60-min per week) in-person under the supervision of a qualified exercise professional. Interventions differ in exercise approach, such that task-oriented exercise involves weight-bearing, walking-specific activities, while generalized resistance and aerobic exercise uses seated machine-based resistance training of major upper and lower body muscle groups and recumbent cycling, and the stretching control exercise involves seated flexibility and relaxation activities. Participants are allocated to interventions using blocked randomization that stratifies by PDDS (mild: 3-4; moderate: 5-6). Assessments are conducted at baseline, post-intervention, and at a six-week retention time point. The primary and secondary outcome measures are the Timed 25-Foot Walk Test and corticospinal excitability for the tibialis anterior muscles determined using transcranial magnetic stimulation (TMS), respectively. Tertiary outcomes include assessments of balance, additional TMS measures, blood biomarkers of neural health and inflammation, and measures of cardiorespiratory and musculoskeletal fitness. DISCUSSION: A paradigm shift in MS healthcare towards the use of "exercise as medicine" was recently proposed to improve outcomes and alleviate the economic burden of MS. Findings will support this shift by informing the development of specialized exercise programming that targets walking and changes in corticospinal excitability in PwMS. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05496881, Registered August 11, 2022. https://classic. CLINICALTRIALS: gov/ct2/show/NCT05496881 . Protocol amendment number: 01; Issue date: August 1, 2023; Primary reason for amendment: Expand eligibility to include people with all forms of MS rather than progressive forms of MS only.

Sequence- and structure-specific RNA oligonucleotide binding attenuates heterogeneous nuclear ribonucleoprotein A1 dysfunction.

The RNA binding protein heterogeneous nuclear ribonucleoprotein A1 (A1) regulates RNA metabolism, which is crucial to maintaining cellular homeostasis. A1 dysfunction mechanistically contributes to reduced cell viability and loss, but molecular mechanisms of how A1 dysfunction affects cell viability and loss, and methodologies to attenuate its dysfunction, are lacking. Utilizing in silico molecular modeling and an in vitro optogenetic system, this study examined the consequences of RNA oligonucleotide (RNAO) treatment on attenuating A1 dysfunction and its downstream cellular effects. In silico and thermal shift experiments revealed that binding of RNAOs to the RNA Recognition Motif 1 of A1 is stabilized by sequence- and structure-specific RNAO-A1 interactions. Using optogenetics to model A1 cellular dysfunction, we show that sequence- and structure-specific RNAOs significantly attenuated abnormal cytoplasmic A1 self-association kinetics and A1 cytoplasmic clustering. Downstream of A1 dysfunction, we demonstrate that A1 clustering affects the formation of stress granules, activates cell stress, and inhibits protein translation. With RNAO treatment, we show that stress granule formation is attenuated, cell stress is inhibited, and protein translation is restored. This study provides evidence that sequence- and structure-specific RNAO treatment attenuates A1 dysfunction and its downstream effects, thus allowing for the development of A1-specific therapies that attenuate A1 dysfunction and restore cellular homeostasis.

Acute intermittent hypoxia alters disease course and promotes CNS repair including resolution of inflammation and remyelination in the experimental autoimmune encephalomyelitis model of MS.

Remyelination and neurodegeneration prevention mitigate disability in Multiple Sclerosis (MS). We have shown acute intermittent hypoxia (AIH) is a novel, non-invasive and effective therapy for peripheral nerve repair, including remyelination. Thus, we posited AIH would improve repair following CNS demyelination and address the paucity of MS repair treatments. AIH's capacity to enhance intrinsic repair, functional recovery and alter disease course in the experimental autoimmune encephalomyelitis (EAE) model of MS was assessed. EAE was induced by MOG35-55 immunization in C57BL/6 female mice. EAE mice received either AIH (10 cycles-5 min 11% oxygen alternating with 5 min 21% oxygen) or Normoxia (control; 21% oxygen for same duration) once daily for 7d beginning at near peak EAE disease score of 2.5. Mice were followed post-treatment for an additional 7d before assessing histopathology or 14d to examine maintenance of AIH effects. Alterations in histopathological correlates of multiple repair indices were analyzed quantitatively in focally demyelinated ventral lumbar spinal cord areas to assess AIH impacts. AIH begun at near peak disease significantly improved daily clinical scores/functional recovery and associated histopathology relative to Normoxia controls and the former were maintained for at least 14d post-treatment. AIH enhanced correlates of myelination, axon protection and oligodendrocyte precursor cell recruitment to demyelinated areas. AIH also effected a dramatic reduction in inflammation, while polarizing remaining macrophages/microglia toward a pro-repair state. Collectively, this supports a role for AIH as a novel non-invasive therapy to enhance CNS repair and alter disease course following demyelination and holds promise as a neuroregenerative MS strategy.

hnRNP A1 dysfunction in oligodendrocytes contributes to the pathogenesis of multiple sclerosis.

Oligodendrocyte (OL) damage and death are prominent features of multiple sclerosis (MS) pathology, yet mechanisms contributing to OL loss are incompletely understood. Dysfunctional RNA binding proteins (RBPs), hallmarked by nucleocytoplasmic mislocalization and altered expression, have been shown to result in cell loss in neurologic diseases, including in MS. Since we previously observed that the RBP heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) was dysfunctional in neurons in MS, we hypothesized that it might also contribute to OL pathology in MS and relevant models. We discovered that hnRNP A1 dysfunction is characteristic of OLs in MS brains. These findings were recapitulated in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS, where hnRNP A1 dysfunction was characteristic of OLs, including oligodendrocyte precursor cells and mature OLs in which hnRNP A1 dysfunction correlated with demyelination. We also found that hnRNP A1 dysfunction was induced by IFNγ, indicating that inflammation influences hnRNP A1 function. To fully understand the effects of hnRNP A1 dysfunction on OLs, we performed siRNA knockdown of hnRNP A1, followed by RNA sequencing. RNA sequencing detected over 4000 differentially expressed transcripts revealing alterations to RNA metabolism, cell morphology, and programmed cell death pathways. We confirmed that hnRNP A1 knockdown was detrimental to OLs and induced apoptosis and necroptosis. Together, these data demonstrate a critical role for hnRNP A1 in proper OL functioning and survival and suggest a potential mechanism of OL damage and death in MS that involves hnRNP A1 dysfunction.

Autoimmunity to a ribonucleoprotein drives neuron loss in multiple sclerosis models.

Neurodegeneration, the progressive loss or damage to neurons and axons, underlies permanent disability in multiple sclerosis (MS); yet its mechanisms are incompletely understood. Recent data indicates autoimmunity to several intraneuronal antigens, including the RNA binding protein (RBP) heterogenous nuclear ribonucleoprotein A1 (hnRNP A1), as contributors to neurodegeneration. We previously showed that addition of anti-hnRNP A1 antibodies, which target the same immunodominant domain of MS IgG, to mice with experimental autoimmune encephalomyelitis (EAE) worsened disease and resulted in an exacerbation of hnRNP A1 dysfunction including cytoplasmic mislocalization of hnRNP A1, stress granule (SG) formation and neurodegeneration in the chronic stages of disease. Because this previous study focused on a singular timepoint during EAE, it is unclear whether anti-hnRNP A1 antibody induced hnRNP A1 dysfunction caused neurodegeneration or was result of it. In the present study, we analyzed in vivo and in vitro models of anti-hnRNP A1 antibody-mediated autoimmunity for markers of hnRNP A1 dysfunction and neurodegeneration over a time course to gain a better understanding of the connection between hnRNP A1 dysfunction and neurodegeneration. Anti-hnRNP A1 antibody treatment resulted in increased neuronal hnRNP A1 mislocalization and nuclear depletion temporally followed by altered RNA expression and SG formation, and lastly an increase in necroptotic signalling and neuronal cell death. Treatment with necrostatin-1s inhibited necroptosis and partially rescued anti-hnRNP A1 antibody-mediated neurodegeneration while clathrin knockdown specifically inhibited anti-hnRNP A1 antibody uptake into neurons. This data identifies a novel antibody-mediated mechanism of neurodegeneration, which may be targeted to inhibit neurodegeneration and prevent permanent neurological decline in persons living with MS.

Pro-Inflammatory Cytokines and Antibodies Induce hnRNP A1 Dysfunction in Mouse Primary Cortical Neurons.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system with a significant neurodegenerative component. Dysfunctional RNA-binding proteins (RBPs) are causally linked to neuronal damage and are a feature of MS, including the mislocalization of the RBP heterogeneous nuclear ribonucleoprotein A1 (A1). Here, we show that primary neurons exposed to pro-inflammatory cytokines and anti-A1 antibodies, both characteristic of an MS autoimmune response, displayed increased A1 mislocalization, stress granule formation, and decreased neurite length, a marker of neurodegeneration. These findings illustrate a significant relationship between secreted immune factors, A1 dysfunction, and neuronal damage in a disease-relevant model system.

Knock-Down of Heterogeneous Nuclear Ribonucleoprotein A1 Results in Neurite Damage, Altered Stress Granule Biology, and Cellular Toxicity in Differentiated Neuronal Cells.

Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is an RNA binding protein (RBP) that is localized within neurons and plays crucial roles in RNA metabolism. Its importance in neuronal functioning is underscored from the study of its pathogenic features in many neurodegenerative diseases where neuronal hnRNP A1 is mislocalized from the nucleus to the cytoplasm resulting in loss of hnRNP A1 function. Here, we model hnRNP A1 loss-of-function by siRNA-mediated knock-down in differentiated Neuro-2a cells. Through RNA sequencing (RNA-seq) followed by gene ontology (GO) analyses, we show that hnRNP A1 is involved in important biological processes, including RNA metabolism, neuronal function, neuronal morphology, neuronal viability, and stress granule (SG) formation. We further confirmed several of these roles by showing that hnRNP A1 knock-down results in a reduction of neurite outgrowth, increase in cell cytotoxicity and changes in SG formation. In summary, these findings indicate that hnRNP A1 loss-of-function contributes to neuronal dysfunction and cell death and implicates hnRNP A1 dysfunction in the pathogenesis of neurodegenerative diseases.

hnRNP A/B Proteins: An Encyclopedic Assessment of Their Roles in Homeostasis and Disease.

The hnRNP A/B family of proteins is canonically central to cellular RNA metabolism, but due to their highly conserved nature, the functional differences between hnRNP A1, A2/B1, A0, and A3 are often overlooked. In this review, we explore and identify the shared and disparate homeostatic and disease-related functions of the hnRNP A/B family proteins, highlighting areas where the proteins have not been clearly differentiated. Herein, we provide a comprehensive assembly of the literature on these proteins. We find that there are critical gaps in our grasp of A/B proteins' alternative splice isoforms, structures, regulation, and tissue and cell-type-specific functions, and propose that future mechanistic research integrating multiple A/B proteins will significantly improve our understanding of how this essential protein family contributes to cell homeostasis and disease.

Diagnostic Dilemma: An Atypical Case of Astrocytoma in a Patient with Relapsing-Remitting Multiple Sclerosis.

Distinguishing between tumefactive demyelinating lesions (TDLs) and brain tumors in multiple sclerosis (MS) can be challenging. A progressive course is highly common with brain tumors in MS and no single neuroimaging technique is foolproof when distinguishing between the two. We report a case of a 41-year-old female with relapsing-remitting multiple sclerosis, who had a suspicious lesion within the left frontal hemisphere, without a progressive course. The patient experienced paresthesias primarily to her right hand but remained stable without any functional decline and new neurological symptoms over the four years she was followed. The lesion was followed with brain magnetic resonance imaging (MRI) scans, positron emission tomography-computed tomography scans, and magnetic resonance spectroscopy. Together, these scans favored the diagnosis of a TDL, but a low-grade tumor was difficult to rule out. Examination of serial brain MRI scans showed an enlarging lesion in the left middle frontal gyrus involving the deep white matter. Neurosurgery was consulted and an elective left frontal awake craniotomy was performed. Histopathology revealed a grade II astrocytoma. This case emphasizes the importance of thorough and continuous evaluation of atypical MRI lesions in MS and contributes important features to the literature for timely diagnosis and treatment of similar cases.

A Descriptive Correlational Study to Evaluate Three Measures of Assessing Upper Extremity Function in Individuals with Multiple Sclerosis.

BACKGROUND: Activities of daily living and quality of life (QOL) are hindered by upper extremity (UE) impairments experienced by individuals with multiple sclerosis (iMS). The Nine-Hole Peg Test (9-HPT) is most frequently used to measure UE function. However, it does not measure peoples' ability to perform routine tasks in daily life and may not be useful in iMS who cannot pick up the pegs utilized in the 9-HPT. Therefore, we evaluated three measures to explore a more comprehensive assessment of UE function: Upper Extremity Function Scale (UEFS), Action Research Arm Test (ARAT), and the 9-HPT. The objectives were to quantitatively assess the relationship between these measures of UE function, understand if the measures correlate with QOL as calculated by the MS Quality of Life-54 (MSQOL-54), and to determine differences in the measures based on employment status. METHODS: 112 (79 female) iMS were prospectively recruited for this descriptive correlational study. Inclusion criteria were as follows: confirmed diagnosis of MS or clinically isolated syndrome, age ≥ 18 years, and ability to self-consent. All statistical analyses including Spearman's correlation coefficient (r s ) and Kruskal-Wallis tests were performed using SPSS. RESULTS: A moderate correlation (r s = -0.51; p < 0.001) was found between the ARAT and 9-HPT scores for the more impaired hand. Likewise, a moderate correlation was found between UEFS and the physical health composite scores (PHCSs) of MSQOL-54 (r s = -0.59; p < 0.001). Finally, performances on ARAT, 9-HPT, and UEFS differed between the employed individuals and those on long-term disability (p = 0.007, p < 0.001, and p = 0.001). CONCLUSION: The UEFS moderately correlated with the QOL measure, and considering the UESF is a patient-reported outcome, it could be used to complement routinely captured measures of assessing UE function. Further study is warranted to determine which measure, or combination of measures, is more sensitive to changes in UE function over time.

A Tripartite Knowledge Translation Program: Innovative Patient-Centered Approach to Clinical Research Participation for Individuals with Multiple Sclerosis.

BACKGROUND: Knowledge translation (KT) models that represent an individual's perspective are a sign of effective KT. Some common challenges in KT include participant engagement, organization of the team, and time demands of the participants. We implemented a unique tripartite KT program to (1) share current research, (2) inform persons living with multiple sclerosis (pwMS) about the clinical research process, and (3) invite pwMS to immediately participate in clinical research. The primary aim was to determine participants' perspectives on the value and acceptability of an experiential research program offered at a patient and family educational conference. METHODS: A team of researchers identified factors that would impact the logistics of hosting an experiential research program at a conference and designed a unique tripartite KT program. The local multiple sclerosis (MS) society was engaged to select an appropriate location and invite stakeholders to the conference. A survey to determine participants' perspectives on the value and acceptability of the experiential research program was developed and analyzed. RESULTS: 65 pwMS attended the conference, and 44 (67.7%) participated in the on-site experiential research program. 72.7% of the participants completed the survey, of which 93.8% stated that they strongly agree or agree with the following statements: "Did you feel like participating in research today was a valuable experience to you?" and "Did you feel like you were contributing to MS research?" 100% of the participants agreed or strongly agreed when asked "would you like to see more research activities taking place at these kinds of events?" CONCLUSIONS: This paper describes the logistics and challenges of conducting an experiential KT program, which proved to be rewarding for pwMS. The majority of pwMS attending the conference agreed to participate in the on-site experiential research program and an overwhelming majority of participants felt the experience was valuable.

Magnetic Resonance Imaging of Spinal Cord Lesions in Patients with Multiple Sclerosis in Saskatchewan, Canada.

BACKGROUND: Spinal cord lesions (SCLs) contribute to disability in multiple sclerosis (MS). Data in Saskatchewan, Canada, concerning SCLs and their association with disability levels in patients with MS are lacking. The study objectives were to identify clinicodemographic profiles of patients with MS with respect to spinal cord magnetic resonance imaging (MRI) involvement; determine the frequency of individuals with MRI SCLs; and explore differences between patients with MS with and without SCLs with respect to disability and disease-modifying therapy status. METHODS: A monocentric, cross-sectional, retrospective review of prospectively collected data from 532 research-consented patients seen at Saskatoon MS Clinic was performed. Data were collected from a database and electronic medical records. RESULTS: Of the 356 patients (66.9%) with an SCL, 180 (50.6%) had only cervical cord lesions. Median Expanded Disability Status Scale (EDSS), ambulation, and pyramidal scores of patients with SCLs were higher than those of patients without SCLs. Of patients with EDSS scores of at least 6, those with SCLs were younger than those without SCLs (P = .01). Patients with SCLs were 55% less likely to have been on continuous disease-modifying therapy since diagnosis than patients without SCLs (adjusted odds ratio, 0.45; 95% CI, 0.25-0.81; P = .008). CONCLUSIONS: Prevalence and association with disability of SCLs in patients with MS are comparable with existing literature. Patients with MS with SCLs have higher levels of disability and attain EDSS scores of at least 6 at a younger age.

Multiple Sclerosis-Associated hnRNPA1 Mutations Alter hnRNPA1 Dynamics and Influence Stress Granule Formation.

Evidence indicates that dysfunctional heterogeneous ribonucleoprotein A1 (hnRNPA1; A1) contributes to the pathogenesis of neurodegeneration in multiple sclerosis. Understanding molecular mechanisms of neurodegeneration in multiple sclerosis may result in novel therapies that attenuate neurodegeneration, thereby improving the lives of MS patients with multiple sclerosis. Using an in vitro, blue light induced, optogenetic protein expression system containing the optogene Cryptochrome 2 and a fluorescent mCherry reporter, we examined the effects of multiple sclerosis-associated somatic A1 mutations (P275S and F281L) in A1 localization, cluster kinetics and stress granule formation in real-time. We show that A1 mutations caused cytoplasmic mislocalization, and significantly altered the kinetics of A1 cluster formation/dissociation, and the quantity and size of clusters. A1 mutations also caused stress granule formation to occur more quickly and frequently in response to blue light stimulation. This study establishes a live cell optogenetics imaging system to probe localization and association characteristics of A1. It also demonstrates that somatic mutations in A1 alter its function and promote stress granule formation, which supports the hypothesis that A1 dysfunction may exacerbate neurodegeneration in multiple sclerosis.

A Comprehensive Analysis of the Role of hnRNP A1 Function and Dysfunction in the Pathogenesis of Neurodegenerative Disease.

Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a member of the hnRNP family of conserved proteins that is involved in RNA transcription, pre-mRNA splicing, mRNA transport, protein translation, microRNA processing, telomere maintenance and the regulation of transcription factor activity. HnRNP A1 is ubiquitously, yet differentially, expressed in many cell types, and due to post-translational modifications, can vary in its molecular function. While a plethora of knowledge is known about the function and dysfunction of hnRNP A1 in diseases other than neurodegenerative disease (e.g., cancer), numerous studies in amyotrophic lateral sclerosis, frontotemporal lobar degeneration, multiple sclerosis, spinal muscular atrophy, Alzheimer's disease, and Huntington's disease have found that the dysregulation of hnRNP A1 may contribute to disease pathogenesis. How hnRNP A1 mechanistically contributes to these diseases, and whether mutations and/or altered post-translational modifications contribute to pathogenesis, however, is currently under investigation. The aim of this comprehensive review is to first describe the background of hnRNP A1, including its structure, biological functions in RNA metabolism and the post-translational modifications known to modify its function. With this knowledge, the review then describes the influence of hnRNP A1 in neurodegenerative disease, and how its dysfunction may contribute the pathogenesis.

The Potential Contribution of Dysfunctional RNA-Binding Proteins to the Pathogenesis of Neurodegeneration in Multiple Sclerosis and Relevant Models.

Neurodegeneration in multiple sclerosis (MS) is believed to underlie disease progression and permanent disability. Many mechanisms of neurodegeneration in MS have been proposed, such as mitochondrial dysfunction, oxidative stress, neuroinflammation, and RNA-binding protein dysfunction. The purpose of this review is to highlight mechanisms of neurodegeneration in MS and its models, with a focus on RNA-binding protein dysfunction. Studying RNA-binding protein dysfunction addresses a gap in our understanding of the pathogenesis of MS, which will allow for novel therapies to be generated to attenuate neurodegeneration before irreversible central nervous system damage occurs.

Neuronal RNA-binding protein dysfunction in multiple sclerosis cortex.

OBJECTIVE: Neurodegeneration is thought to be the primary cause of neurological disability in multiple sclerosis (MS). Dysfunctional RNA-binding proteins (RBPs) including their mislocalization from nucleus to cytoplasm, stress granule formation, and altered RNA metabolism have been found to underlie neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia. Yet, little is known about the role of dysfunctional RBPs in the pathogenesis of neurodegeneration in MS. As a follow-up to our seminal finding of altered RBP function in a single case of MS, we posited that there would be evidence of RBP dysfunction in cortical neurons in MS. METHODS: Cortical neurons from 12 MS and six control cases were analyzed by immunohistochemistry for heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) and TAR-DNA-binding protein-43 (TDP-43). Seven distinct neuronal phenotypes were identified based on the nucleocytoplasmic staining of these RBPs. Statistical analyses were performed by analyzing each phenotype in relation to MS versus controls. RESULTS: Analyses revealed a continuum of hnRNP A1 and TDP-43 nucleocytoplasmic staining was found in cortical neurons, from neurons with entirely nuclear staining with little cytoplasmic staining in contrast to those with complete nuclear depletion of RBPs concurrent with robust cytoplasmic staining. The neuronal phenotypes that showed the most nucleocytoplasmic mislocalization of hnRNP A1 and TDP-43 statistically distinguished MS from control cases (P < 0.01, P < 0.001, respectively). INTERPRETATION: The discovery of hnRNP A1 and TDP-43 nucleocytoplasmic mislocalization in neurons in MS brain demonstrate that dysfunctional RBPs may play a role in neurodegeneration in MS, as they do in other neurological diseases.

Treatment Optimization in Multiple Sclerosis: Canadian MS Working Group Recommendations.

The Canadian Multiple Sclerosis Working Group has updated its treatment optimization recommendations (TORs) on the optimal use of disease-modifying therapies for patients with all forms of multiple sclerosis (MS). Recommendations provide guidance on initiating effective treatment early in the course of disease, monitoring response to therapy, and modifying or switching therapies to optimize disease control. The current TORs also address the treatment of pediatric MS, progressive MS and the identification and treatment of aggressive forms of the disease. Newer therapies offer improved efficacy, but also have potential safety concerns that must be adequately balanced, notably when treatment sequencing is considered. There are added discussions regarding the management of pregnancy, the future potential of biomarkers and consideration as to when it may be prudent to stop therapy. These TORs are meant to be used and interpreted by all neurologists with a special interest in the management of MS.