Grey matter damage in multiple sclerosis: a pathology perspective

Capacity of fullerenols to modulate neurodegeneration induced by ferroptosis: Focus on multiple sclerosis

Multiple sclerosis is an inflammatory disease of the central nervous system (CNS), characterized by oligodendrocyte loss and demyelination of axons leading to neurodegeneration and severe neurological disability. Despite the existing drugs that have immunomodulatory effects an adequate therapy that slow down or stop neuronal death has not yet been found. Oxidative stress accompanied by excessive release of iron into the extracellular space, mitochondrial damage and lipid peroxidation are important factors in the controlled cell death named ferroptosis, latterly recognized in MS. As the fullerenols exhibit potent antioxidant activity, recent results imply that they could have protective effects by suppressing ferroptosis. Based on the current knowledge we addressed the main mechanisms of the protective effects of fullerenols in the CNS in relation to ferroptosis. Inhibition of inflammation, iron overload and lipid peroxidation through the signal transduction mechanism of Nuclear Factor Erythroid 2-Related Factor 2 (NRF2), chelation of heavy metals and free radical scavenging using fullerenols are proposed as benefitial strategy preventing MS progression. Current review connects ferroptosis molecular targets and important factors of MS progression, with biomedical properties and mechanisms of fullerenols' actions, to propose new treatment strategies that could be addaptobale in other neurodegenerative diseases.

Exploring Differences in the Lateralized Readiness Potential in Persons With Multiple Sclerosis Compared to Healthy Controls

Multiple sclerosis (MS) is a neurodegenerative disease often leading to cognitive and motor impairment. Little research has examined motor preparation and initiation outcomes in the brain among persons with MS. The lateralized readiness potential is an ERP component that indexes pre-motor activity evaluating the stimulus (LRP-S) and motor activation for the response (LRP-R). We examined the LRP-S and LRP-R in MS and healthy controls (HC) to understand impairments in neural activity associated with response activation and selection. Persons with MS (n = 53) and HC (n = 53) completed a flanker task with concurrent EEG for LRP extraction. Paired t-tests were conducted to determine differences for accuracy, reaction time (RT), LRP-S, and LRP-R. Within-group Pearson correlations were conducted to investigate the relationship between LRP indices and behavioral performance. Participants with MS had delayed LRP-S latency and reduced LRP-R amplitudes compared to HC for both trial types. In the HC group, LRP-S amplitude and latency were positively related to RT. In the MS group, LRP-S latency was positively related to RT. In both MS and HC, incongruent LRP-R latency was negatively related to RT, suggesting that individuals with a shorter time interval between activation and response had faster reaction times. Persons with MS had delayed response selection, and less neural response activation compared to HC. Impairment in MS is evident for both pre-motor and motor response initiation during a selective attention task. Our study also provided evidence the relationship between action-based components and task performance differ in persons with MS and HC.

Machine learning for refining interpretation of magnetic resonance imaging scans in the management of multiple sclerosis: a narrative review

Multiple sclerosis (MS) is an autoimmune disease of the brain and spinal cord with both inflammatory and neurodegenerative features. Although advances in imaging techniques, particularly magnetic resonance imaging (MRI), have improved the process of diagnosis, its cause is unknown, a cure remains elusive and the evidence base to guide treatment is lacking. Computational techniques like machine learning (ML) have started to be used to understand MS. Published MS MRI-based computational studies can be divided into five categories: automated diagnosis; differentiation between lesion types and/or MS stages; differential diagnosis; monitoring and predicting disease progression; and synthetic MRI dataset generation. Collectively, these approaches show promise in assisting with MS diagnosis, monitoring of disease activity and prediction of future progression, all potentially contributing to disease management. Analysis quality using ML is highly dependent on the dataset size and variability used for training. Wider public access would mean larger datasets for experimentation, resulting in higher-quality analysis, permitting for more conclusive research. This narrative review provides an outline of the fundamentals of MS pathology and pathogenesis, diagnostic techniques and data types in computational analysis, as well as collating literature pertaining to the application of computational techniques to MRI towards developing a better understanding of MS.

[Cognitive impairment in patients with multiple sclerosis]

Cognitive impairment (CI), along with physical disability, is the most important clinical manifestation of multiple sclerosis MS and is detected in 40-70% of patients. Present in all types and forms of MS, it has a significant negative impact on social adaptation, ability to work and daily activity. Most often, CI includes problems with information processing speed, memory, visual-spatial perception and regulatory functions. At the moment, there is no single theory explaining the pathogenesis of CI. It is believed to be associated with lesions in white and gray matter, which are not visible on MRI, as well as neuroimmunological processes that disrupt synaptic transmission and plasticity. Therapeutic strategies in the treatment of CI are also ambiguous: there is evidence of minimal to moderate efficacy of drugs that alter the course of MS (PITMS), especially PITMS 2 lines, and symptomatic therapy. However, the greatest effect was noted in cognitive training. Screening for CI during routine examination of patients with MS becomes more convenient thanks to short scales and tools, which in turn allows specialists to carry out timely therapeutic and preventive measures. In our review, we tried to analyze updated data on the prevalence, structure, pathogenesis and therapy of CI in MS patients.

Distinct virtual histology of grey matter atrophy in four neuroinflammatory diseases

Grey matter (GM) atrophies are observed in multiple sclerosis, neuromyelitis optica spectrum disorders [NMOSD; both anti-aquaporin-4 antibody-positive (AQP4+) and -negative (AQP4-) subtypes] and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Revealing the pathogenesis of brain atrophy in these disorders would help their differential diagnosis and guide therapeutic strategies. To determine the neurobiological underpinnings of GM atrophies in multiple sclerosis, AQP4+ NMOSD, AQP4- NMOSD and MOGAD, we conducted a virtual histology analysis that links T1-weighted image derived GM atrophy and gene expression using a multicentre cohort of 324 patients with multiple sclerosis, 197 patients with AQP4+ NMOSD, 75 patients with AQP4- NMOSD, 47 patients with MOGAD and 2169 healthy control subjects. First, interregional GM atrophy profiles across the cortical and subcortical regions were determined using Cohen's d between patients with multiple sclerosis, AQP4+ NMOSD, AQP4- NMOSD or MOGAD and healthy controls. The GM atrophy profiles were then spatially correlated with the gene expression levels extracted from the Allen Human Brain Atlas, respectively. Finally, we explored the virtual histology of clinical-feature relevant GM atrophy using a subgroup analysis that stratified by physical disability, disease duration, number of relapses, lesion burden and cognitive function. Multiple sclerosis showed a severe widespread GM atrophy pattern, mainly involving subcortical nuclei and brainstem. AQP4+ NMOSD showed an obvious widespread pattern of GM atrophy, predominately located in occipital cortex as well as cerebellum. AQP4- NMOSD showed a mild widespread GM atrophy pattern, mainly located in frontal and parietal cortices. MOGAD showed GM atrophy mainly involving the frontal and temporal cortices. High expression of genes specific to microglia, astrocytes, oligodendrocytes and endothelial cells in multiple sclerosis, S1 pyramidal cells in AQP4+ NMOSD, as well as S1 and CA1 pyramidal cells in MOGAD, had spatial correlations with GM atrophy profile, while no atrophy profile-related gene expression was found in AQP4- NMOSD. Virtual histology of clinical feature-relevant GM atrophy pointed mainly to the shared neuronal and endothelial cells, among the four neuroinflammatory diseases. The unique underlying virtual histology patterns were microglia, astrocytes and oligodendrocytes for multiple sclerosis; astrocytes for AQP4+ NMOSD; and oligodendrocytes for MOGAD. Neuronal and endothelial cells were shared potential targets across these neuroinflammatory diseases. These findings may help the differential diagnoses of these diseases and promote the use of optimal therapeutic strategies.

Quantitative Analysis of Early White Matter Damage in Cuprizone Mouse Model of Demyelination Using 7.0 T MRI Multiparametric Approach

Magnetic Resonance Imaging (MRI) is commonly used to follow the progression of neurodegenerative conditions, including multiple sclerosis (MS). MRI is limited by a lack of correlation between imaging results and clinical presentations, referred to as the clinico-radiological paradox. Animal models are commonly used to mimic the progression of human neurodegeneration and as a tool to help resolve the paradox. Most studies focus on later stages of white matter (WM) damage whereas few focus on early stages when oligodendrocyte apoptosis has just begun. The current project focused on these time points, namely weeks 2 and 3 of cuprizone (CPZ) administration, a toxin which induces pathophysiology similar to MS. In vivo T2-weighted (T2W) and Magnetization Transfer Ratio (MTR) maps and ex vivo Diffusion Tensor Imaging (DTI), Magnetization Transfer Imaging (MTI), and relaxometry (T1 and T2) values were obtained at 7 T. Significant changes in T2W signal intensity and non-significant changes in MTR were observed to correspond to early WM damage, whereas significant changes in both corresponded with full demyelination. Some DTI metrics decrease with simultaneous increase in others, indicating acute demyelination. MTI metrics T2A, T2B, f and R were observed to have contradictory changes across CPZ administration. T1 relaxation times were observed to have stronger correlations to disease states during later stages of CPZ treatment, whereas T2 had weak correlations to early WM damage. These results all suggest the need for multiple metrics and further studies at early and late time points of demyelination. Further research is required to continue investigating the interplay between various MR metrics during all weeks of CPZ administration.

Predicting multiple sclerosis disease progression and outcomes with machine learning and MRI-based biomarkers: a review

Multiple sclerosis (MS) is a demyelinating neurological disorder with a highly heterogeneous clinical presentation and course of progression. Disease-modifying therapies are the only available treatment, as there is no known cure for the disease. Careful selection of suitable therapies is necessary, as they can be accompanied by serious risks and adverse effects such as infection. Magnetic resonance imaging (MRI) plays a central role in the diagnosis and management of MS, though MRI lesions have displayed only moderate associations with MS clinical outcomes, known as the clinico-radiological paradox. With the advent of machine learning (ML) in healthcare, the predictive power of MRI can be improved by leveraging both traditional and advanced ML algorithms capable of analyzing increasingly complex patterns within neuroimaging data. The purpose of this review was to examine the application of MRI-based ML for prediction of MS disease progression. Studies were divided into five main categories: predicting the conversion of clinically isolated syndrome to MS, cognitive outcome, EDSS-related disability, motor disability and disease activity. The performance of ML models is discussed along with highlighting the influential MRI-derived biomarkers. Overall, MRI-based ML presents a promising avenue for MS prognosis. However, integration of imaging biomarkers with other multimodal patient data shows great potential for advancing personalized healthcare approaches in MS.

Magnetic resonance metrics for identification of cuprizone-induced demyelination in the mouse model of neurodegeneration: a review

Neurodegenerative disorders, including Multiple Sclerosis (MS), are heterogenous disorders which affect the myelin sheath of the central nervous system (CNS). Magnetic Resonance Imaging (MRI) provides a non-invasive method for studying, diagnosing, and monitoring disease progression. As an emerging research area, many studies have attempted to connect MR metrics to underlying pathophysiological presentations of heterogenous neurodegeneration. Most commonly, small animal models are used, including Experimental Autoimmune Encephalomyelitis (EAE), Theiler's Murine Encephalomyelitis (TMEV), and toxin models including cuprizone (CPZ), lysolecithin, and ethidium bromide (EtBr). A contrast and comparison of these models is presented, with focus on the cuprizone model, followed by a review of literature studying neurodegeneration using MRI and the cuprizone model. Conventional MRI methods including T1 Weighted (T1W) and T2 Weighted (T2W) Imaging are mentioned. Quantitative MRI methods which are sensitive to diffusion, magnetization transfer, susceptibility, relaxation, and chemical composition are discussed in relation to studying the CPZ model. Overall, additional studies are needed to improve both the sensitivity and specificity of MRI metrics for underlying pathophysiology of neurodegeneration and the relationships in attempts to clear the clinico-radiological paradox. We therefore propose a multiparametric approach for the investigation of MR metrics for underlying pathophysiology.

Novel Insights into Psychosis and Antipsychotic Interventions: From Managing Symptoms to Improving Outcomes

For the past 70 years, the dopamine hypothesis has been the key working model in schizophrenia. This has contributed to the development of numerous inhibitors of dopaminergic signaling and antipsychotic drugs, which led to rapid symptom resolution but only marginal outcome improvement. Over the past decades, there has been limited research on the quantifiable pathological changes in schizophrenia, including premature cellular/neuronal senescence, brain volume loss, the attenuation of gamma oscillations in electroencephalograms, and the oxidation of lipids in the plasma and mitochondrial membranes. We surmise that the aberrant activation of the aryl hydrocarbon receptor by toxins derived from gut microbes or the environment drives premature cellular and neuronal senescence, a hallmark of schizophrenia. Early brain aging promotes secondary changes, including the impairment and loss of mitochondria, gray matter depletion, decreased gamma oscillations, and a compensatory metabolic shift to lactate and lactylation. The aim of this narrative review is twofold: (1) to summarize what is known about premature cellular/neuronal senescence in schizophrenia or schizophrenia-like disorders, and (2) to discuss novel strategies for improving long-term outcomes in severe mental illness with natural senotherapeutics, membrane lipid replacement, mitochondrial transplantation, microbial phenazines, novel antioxidant phenothiazines, inhibitors of glycogen synthase kinase-3 beta, and aryl hydrocarbon receptor antagonists.

Association Between Disease-Modifying Therapy and Information Processing Speed in Multiple Sclerosis

BACKGROUND

Cognitive impairment (CI) is common in multiple sclerosis (MS). Processing speed (PS) is often affected, making it an ideal target for monitoring CI. This study aims to evaluate the association between disease-modifying therapy (DMT) use and intensity and longitudinal changes in Processing Speed Test (PST) scores for individuals with MS.

METHODS

A retrospective analysis of individual PST scores at a single MS center was conducted. Individuals with 2 or more PST assessments were included. Scores on the PST were compared longitudinally between those who had been on a DMT for 2 or more years and those who had been off a DMT for 2 or more years and between those on high-efficacy DMTs and those on low-/moderate-efficacy DMTs. A linear regression model was approximated to evaluate the rate of cognitive change over time. A propensity score adjustment was conducted using a multivariable logistic regression.

RESULTS

The cohort was 642 individuals, 539 on DMT and 103 off DMT. Median age and disease duration was 49.7 (IQR 42.4-57.9) and 16.6 years (IQR 9.3-23.0) in the DMT group, and 58.9 (IQR 52.2-65.3) and 20.0 years (IQR 14.1-31.4) in the non-DMT group. Both cohorts were predominantly female (75% DMT, 79.6% non-DMT), with a mean of 4 assessments (IQR 3-5), and an average monitoring duration of 1.9 years (1.2-2.4) in the DMT group, and 1.8 years (1.4-2.4) in the non-DMT group. After adjusting for multiple factors, DMT status and intensity were not found to be significant predictors of longitudinal PST change.

CONCLUSIONS

Neither DMT status nor intensity was a significant predictor of cognitive processing speed over a period of approximately 2 years. Future prospective studies are needed to further support these findings.

An update on the role of magnetic resonance imaging in predicting and monitoring multiple sclerosis progression

INTRODUCTION

While magnetic resonance imaging (MRI) is established in diagnosing and monitoring disease activity in multiple sclerosis (MS), its utility in predicting and monitoring disease progression is less clear.

AREAS COVERED

The authors consider changing concepts in the phenotypic classification of MS, including progression independent of relapses; pathological processes underpinning progression; advances in MRI measures to assess them; how well MRI features explain and predict clinical outcomes, including models that assess disease effects on neural networks, and the potential role for machine learning.

EXPERT OPINION

Relapsing-remitting and progressive MS have evolved from being viewed as mutually exclusive to having considerable overlap. Progression is likely the consequence of several pathological elements, each important in building more holistic prognostic models beyond conventional phenotypes. MRI is well placed to assess pathogenic processes underpinning progression, but we need to bridge the gap between MRI measures and clinical outcomes. Mapping pathological effects on specific neural networks may help and machine learning methods may be able to optimize predictive markers while identifying new, or previously overlooked, clinically relevant features. The ever-increasing ability to measure features on MRI raises the dilemma of what to measure and when, and the challenge of translating research methods into clinically useable tools.

Predicting multiple sclerosis severity with multimodal deep neural networks

Multiple Sclerosis (MS) is a chronic disease developed in the human brain and spinal cord, which can cause permanent damage or deterioration of the nerves. The severity of MS disease is monitored by the Expanded Disability Status Scale, composed of several functional sub-scores. Early and accurate classification of MS disease severity is critical for slowing down or preventing disease progression via applying early therapeutic intervention strategies. Recent advances in deep learning and the wide use of Electronic Health Records (EHR) create opportunities to apply data-driven and predictive modeling tools for this goal. Previous studies focusing on using single-modal machine learning and deep learning algorithms were limited in terms of prediction accuracy due to data insufficiency or model simplicity. In this paper, we proposed the idea of using patients' multimodal longitudinal and longitudinal EHR data to predict multiple sclerosis disease severity in the future. Our contribution has two main facets. First, we describe a pioneering effort to integrate structured EHR data, neuroimaging data and clinical notes to build a multi-modal deep learning framework to predict patient's MS severity. The proposed pipeline demonstrates up to 19% increase in terms of the area under the Area Under the Receiver Operating Characteristic curve (AUROC) compared to models using single-modal data. Second, the study also provides valuable insights regarding the amount useful signal embedded in each data modality with respect to MS disease prediction, which may improve data collection processes.

Fibroblast growth factor 9 (FGF9)-mediated neurodegeneration: Implications for progressive multiple sclerosis?

AIMS

Fibroblast growth factor (FGF) signalling is dysregulated in multiple sclerosis (MS) and other neurological and psychiatric conditions, but there is little or no consensus as to how individual FGF family members contribute to disease pathogenesis. Lesion development in MS is associated with increased expression of FGF1, FGF2 and FGF9, all of which modulate remyelination in a variety of experimental settings. However, FGF9 is also selectively upregulated in major depressive disorder (MDD), prompting us to speculate it may also have a direct effect on neuronal function and survival.

METHODS

Transcriptional profiling of myelinating cultures treated with FGF1, FGF2 or FGF9 was performed, and the effects of FGF9 on cortical neurons investigated using a combination of transcriptional, electrophysiological and immunofluorescence microscopic techniques. The in vivo effects of FGF9 were explored by stereotactic injection of adeno-associated viral (AAV) vectors encoding either FGF9 or EGFP into the rat motor cortex.

RESULTS

Transcriptional profiling of myelinating cultures after FGF9 treatment revealed a distinct neuronal response with a pronounced downregulation of gene networks associated with axonal transport and synaptic function. In cortical neuronal cultures, FGF9 also rapidly downregulated expression of genes associated with synaptic function. This was associated with a complete block in the development of photo-inducible spiking activity, as demonstrated using multi-electrode recordings of channel rhodopsin-transfected rat cortical neurons in vitro and, ultimately, neuronal cell death. Overexpression of FGF9 in vivo resulted in rapid loss of neurons and subsequent development of chronic grey matter lesions with neuroaxonal reduction and ensuing myelin loss.

CONCLUSIONS

These observations identify overexpression of FGF9 as a mechanism by which neuroaxonal pathology could develop independently of immune-mediated demyelination in MS. We suggest targeting neuronal FGF9-dependent pathways may provide a novel strategy to slow if not halt neuroaxonal atrophy and loss in MS, MDD and potentially other neurodegenerative diseases.

Cortical morphological changes in multiple sclerosis patients: a study of cortical thickness, sulcal depth, and local gyrification index

PURPOSE

Multiple sclerosis (MS) is a disease that progresses not only with demyelination but also with neurodegeneration. One of the goals of drug treatment in MS is to prevent neurodegeneration. Cortical thickness (CT), sulcal depth (SD), and local gyrification index (LGI) are indicators related to neurodegeneration. The aim of this study is to investigate changes in CT, SD, and LGI in patients with relapsing-remitting MS (RRMS).

METHODS

T1 images of 74 RRMS patients and 65 healthy controls were used. T1 hypointense areas in RRMS patients were corrected using fully automated methods. CT, SD, and LGI were calculated for each patient.

RESULTS

RRMS patients showed widespread cortical thinning, especially in bilateral temporoparietal areas, decreased SD in bilateral supramarginal gyrus, superior temporal gyrus, postcentral gyrus, and transverse temporal gyrus, and decreased LGI, especially in the left posterior cingulate gyrus and insula. The decrease in cortical thickness was associated with the number of attacks and lesion volume. EDSS was related to CT in the right lingual, inferior temporal, and fusiform gyrus. The LGI was correlated with T2 lesion volume in bilateral insula, with EDSS in the right insula and transverse and superior temporal gyri, and with the number of attacks in the right paracentral gyrus and pre-cuneus. However, SD did not show any correlation with EDSS, T2 lesion volume, or the number of attacks.

CONCLUSION

Our results demonstrate widespread cortical thinning, decreased sulcal depth in local areas, and decreased gyrification in folds in RRMS patients, which are related to clinical parameters.

Estimation of white matter hyperintensities with synthetic MRI myelin volume fraction in patients with multiple sclerosis and non-multiple-sclerosis white matter hyperintensities: A pilot study among the Indian population

AIM

Synthetic MRI (SyMRI) works on the MDME sequence, which acquires the relaxation properties of the brain and helps to measure the accurate tissue properties in 6 minutes. The aim of this study was to evaluate the synthetic MRI (SyMRI)-generated myelin (MyC) to white matter (WM) ratio, the WM fraction (WMF), MyC partial maps performing normative brain volumetry to investigate MyC loss in multiple sclerosis (MS) patients with white-matter hyperintensites (WMHs) and non-MS patients with WMHs in a clinical setting.

MATERIALS and METHODS

Synthetic MRI images were acquired from 15 patients with MS, and from 15 non-MS patients on a 3T MRI scanner (Discovery MR750w; GE Healthcare; Milwaukee, USA) using MAGiC, a customized version of SyntheticMR's SyMRI® IMAGE software marketed by GE Healthcare under a license agreement. Fast multi-delay multi-echo acquisition was performed with a 2D axial pulse sequence with different combinations of echo time (TEs) and saturation delay times. The total image acquisition time was 6 minutes. SyMRI image analysis was done using SyMRI software (SyMRI Version: 11.3.6; Synthetic MR, Linköping, Sweden). SyMRI data were used to generate the MyC partial maps and WMFs to quantify the signal intensities of test group and control group, andcontrol group , and their mean values were recorded. All patients also underwent conventional diffusion-weighted imaging, i.e., T1w and T2w imaging.

RESULTS

The results showed that the WMF was significantly lower in the test group than in the control group (38.8% vs 33.2%, p < 0.001). The Mann-Whitney U nonparametric t-test revealed a significant difference in the mean myelin volume between the test group and the control group (158.66 ± 32.31 vs. 138.29 ± 29.28, p = 0.044). Also, there were no significant differences in the gray matter fraction and intracranial volume between the test group and the control group.

CONCLUSIONS

We observed MyC loss in test group using quantitative SyMRI. Thus, myelin loss in MS patients can be quantitatively evaluated using SyMRI.

Three-dimensional multi-parameter brain mapping using MR fingerprinting

The purpose of this study was to develop and test a 3D multi-parameter MR fingerprinting (MRF) method for brain imaging applications. The subject cohort included 5 healthy volunteers, repeatability tests done on 2 healthy volunteers and tested on two multiple sclerosis (MS) patients. A 3D-MRF imaging technique capable of quantifying T1, T2 and T1ρ was used. The imaging sequence was tested in standardized phantoms and 3D-MRF brain imaging with multiple shots (1, 2 and 4) in healthy human volunteers and MS patients. Quantitative parametric maps for T1, T2, T1ρ, were generated. Mean gray matter (GM) and white matter (WM) ROIs were compared for each mapping technique, Bland-Altman plots and intra-class correlation coefficient (ICC) were used to assess repeatability and Student T-tests were used to compare results in MS patients. Standardized phantom studies demonstrated excellent agreement with reference T1/T2/T1ρ mapping techniques. This study demonstrates that the 3D-MRF technique is able to simultaneously quantify T1, T2 and T1ρ for tissue property characterization in a clinically feasible scan time. This multi-parametric approach offers increased potential to detect and differentiate brain lesions and to better test imaging biomarker hypotheses for several neurological diseases, including MS.

Association between multiple sclerosis and epilepsy: A systematic review and meta-analysis

BACKGROUND

Seizures in people with multiple sclerosis (MS) are reported; however, the risk of epilepsy in adults with MS remains poorly defined.

METHODS

We performed a systematic review and meta-analysis to evaluate the incidence and prevalence of epilepsy in adults (≥ 18 years) with MS compared to those without. We searched MEDLINE and EMBASE from inception to July 1, 2022 to include observational studies that reported the prevalence or incidence of epilepsy in adults with MS and a comparator group, consisting of adults without MS or the general population. We used the Newcastle Ottawa Scale to evaluate quality of the included studies. We performed random-effects meta-analyses to determine the prevalence and incidence of epilepsy in adults with MS compared to the non-MS group.

RESULTS

We identified 17 studies consisting of 192,850 adults with MS, across nine countries. Most studies were of moderate quality as they did not specify the MS type or type of seizures. Compared to a comparison group, both the prevalence (pooled OR 2.04; 95% confidence interval 1.59-2.63, I² = 95.4, n = 12) and the incidence of epilepsy (pooled RR 3.34; 3.17-3.52, I² = 4.6%, n = 6) was higher in people with MS. Heterogeneity in estimates was not explained by additional analyses.

CONCLUSIONS

MS is an independent risk factor for both incident and prevalent epilepsy, suggesting variation in grey matter involvement over the disease course. Longitudinal studies are required to help identify patient and disease characteristics associated with epilepsy.

Multisensory integration and white matter pathology: Contributions to cognitive dysfunction

The ability to simultaneously process and integrate multiple sensory stimuli is paramount to effective daily function and essential for normal cognition. Multisensory management depends critically on the interplay between bottom-up and top-down processing of sensory information, with white matter (WM) tracts acting as the conduit between cortical and subcortical gray matter (GM) regions. White matter tracts and GM structures operate in concert to manage both multisensory signals and cognition. Altered sensory processing leads to difficulties in reweighting and modulating multisensory input during various routine environmental challenges, and thus contributes to cognitive dysfunction. To examine the specific role of WM in altered sensory processing and cognitive dysfunction, this review focuses on two neurologic disorders with diffuse WM pathology, multiple sclerosis and mild traumatic brain injury, in which persistently altered sensory processing and cognitive impairment are common. In these disorders, cognitive dysfunction in association with altered sensory processing may develop initially from slowed signaling in WM tracts and, in some cases, GM pathology secondary to WM disruption, but also because of interference with cognitive function by the added burden of managing concurrent multimodal primary sensory signals. These insights promise to inform research in the neuroimaging, clinical assessment, and treatment of WM disorders, and the investigation of WM-behavior relationships.

Tripartite Crosstalk between Cytokine IL-1β, NMDA-R and Misplaced Mitochondrial Anchor in Neuronal Dendrites Is a Novel Pathway for Neurodegeneration in Inflammatory Diseases

The mitochondrial anchor syntaphilin (SNPH) is a key mitochondrial protein normally expressed in axons to maintain neuronal health by positioning mitochondria along axons for metabolic needs. However, in 2019 we discovered a novel form of excitotoxicity that results when SNPH is misplaced into neuronal dendrites in disease models. A key unanswered question about this SNPH excitotoxicity is the pathologic molecules that trigger misplacement or intrusion of SNPH into dendrites. Here, we identified two different classes of pathologic molecules that interact to trigger dendritic SNPH intrusion. Using primary hippocampal neuronal cultures from mice of either sex, we demonstrated that the pro-inflammatory cytokine IL-1β interacts with NMDA to trigger SNPH intrusion into dendrites. First, IL-1β and NMDA each individually triggers dendritic SNPH intrusion. Second, IL-1β and NMDA do not act independently but interact. Thus, blocking NMDAR by the antagonist MK-801 blocks IL-1β from triggering dendritic SNPH intrusion. Further, decoupling the known interaction between IL-1β and NMDAR by tyrosine inhibitors prevents either IL-1β or NMDA from triggering dendritic SNPH intrusion. Third, neuronal toxicity caused by IL-1β or NMDA is strongly ameliorated in SNPH-/- neurons. Together, we hypothesize that the known bipartite IL-1β/NMDAR crosstalk converges to trigger misplacement of SNPH in dendrites as a final common pathway to cause neurodegeneration. Targeting dendritic SNPH in this novel tripartite IL-1β/NMDAR/SNPH interaction could be a strategic downstream locus for ameliorating neurotoxicity in inflammatory diseases.SIGNIFICANCE STATEMENT SNPH is a key mitochondrial protein normally expressed specifically in healthy axons to help position mitochondria along axons to match metabolic needs. In 2019 we discovered that misplacement of SNPH into neuronal dendrites causes a novel form of excitotoxicity in rodent models of multiple sclerosis. A key unanswered question about this new form of dendritic SNPH toxicity concerns pathologic molecules that trigger toxic misplacement of SNPH into dendrites. Here, we identified two major categories of pathologic molecules, the pro-inflammatory cytokines and NMDA, that interact and converge to trigger toxic misplacement of SNPH into dendrites. We propose that a dendritic mitochondrial anchor provides a novel, single common target for ameliorating diverse inflammatory and excitatory injuries in neurodegenerative diseases.

The Effect of Smoking on Long-term Gray Matter Atrophy and Clinical Disability in Patients with Relapsing-Remitting Multiple Sclerosis

Background and Objectives

The relationship between smoking, long-term brain atrophy, and clinical disability in patients with multiple sclerosis (MS) is unclear. Here, we assessed long-term effects of smoking by evaluating MRI and clinical outcome measures after 10 years in smoking and nonsmoking patients with relapsing-remitting MS (RRMS).

Methods

We included 85 treatment-naive patients with RRMS with recent inflammatory disease activity who participated in a 10-year follow-up visit after a multicenter clinical trial of 24 months. Smoking status was decided for each patient by 2 separate definitions: by serum cotinine levels measured regularly for the first 2 years of the follow-up (during the clinical trial) and by retrospective patient self-reporting. At the 10-year follow-up visit, clinical tests were repeated, and brain atrophy measures were obtained from MRI using FreeSurfer. Differences in clinical and MRI measurements at the 10-year follow-up between smokers and nonsmokers were investigated by 2-sample t tests or Mann-Whitney tests and linear mixed-effect regression models. All analyses were conducted separately for each definition of smoking status.

Results

After 10 years, smoking (defined by serum cotinine levels) was associated with lower total white matter volume (β = −21.74, p = 0.039) and higher logT2 lesion volume (β = 0.22, p = 0.011). When defining smoking status by patient self-reporting, the repeated analyses found an additional association with lower deep gray matter volume (β = −2.35, p = 0.049), and smoking was also associated with a higher score (higher walking impairment) on the log timed 25-foot walk test (β = 0.050, p = 0.039) after 10 years and a larger decrease in paced auditory serial addition test (attention) scores (β = −3.58, p = 0.029).

Discussion

Smoking was associated with brain atrophy and disability progression 10 years later in patients with RRMS. The findings imply that patients should be advised and offered aid in smoking cessation shortly after diagnosis, to prevent long-term disability progression.

Copolymer-1 as a potential therapy for mild cognitive impairment

Mild cognitive impairment (MCI) is a prodromal stage of memory impairment that may precede dementia. MCI is classified by the presence or absence of memory impairment into amnestic or non-amnestic MCI, respectively. More than 90% of patients with amnestic MCI who progress towards dementia meet criteria for Alzheimer's disease (AD). A combination of mechanisms promotes MCI, including intracellular neurofibrillary tangle formation, extracellular amyloid deposition, oxidative stress, neuronal loss, synaptodegeneration, cholinergic dysfunction, cerebrovascular disease, and neuroinflammation. However, emerging evidence indicates that neuroinflammation plays an important role in the pathogenesis of cognitive impairment. Unfortunately, there are currently no Food and Drug Administration (FDA)-approved drugs for MCI. Copolymer-1 (Cop-1), also known as glatiramer acetate, is a synthetic polypeptide of four amino acids approved by the FDA for the treatment of relapsing-remitting multiple sclerosis. Cop-1 therapeutic effect is attributed to immunomodulation, promoting a switch from proinflammatory to anti-inflammatory phenotype. In addition to its anti-inflammatory properties, it stimulates brain-derived neurotrophic factor (BDNF) secretion, a neurotrophin involved in neurogenesis and the generation of hippocampal long-term potentials. Moreover, BDNF levels are significantly decreased in patients with cognitive impairment. Therefore, Cop-1 immunization might promote synaptic plasticity and memory consolidation by increasing BDNF production in patients with MCI.

MicroRNAs as T Lymphocyte Regulators in Multiple Sclerosis

MicroRNA (miRNA) is a class of endogenous non-coding small RNA with regulatory activities, which generally regulates the expression of target genes at the post-transcriptional level. Multiple Sclerosis (MS) is thought to be an autoimmune-mediated chronic inflammatory demyelinating disease of the central nervous system (CNS) that typically affect young adults. T lymphocytes play an important role in the pathogenesis of MS, and studies have suggested that miRNAs are involved in regulating the proliferation, differentiation, and functional maintenance of T lymphocytes in MS. Dysregulated expression of miRNAs may lead to the differentiation balance and dysfunction of T lymphocytes, and they are thus involved in the occurrence and development of MS. In addition, some specific miRNAs, such as miR-155 and miR-326, may have potential diagnostic values for MS or be useful for discriminating subtypes of MS. Moreover, miRNAs may be a promising therapeutic strategy for MS by regulating T lymphocyte function. By summarizing the recent literature, we reviewed the involvement of T lymphocytes in the pathogenesis of MS, the role of miRNAs in the pathogenesis and disease progression of MS by regulating T lymphocytes, the possibility of differentially expressed miRNAs to function as biomarkers for MS diagnosis, and the therapeutic potential of miRNAs in MS by regulating T lymphocytes.

Multimodal magnetic resonance imaging quantification of gray matter alterations in relapsing-remitting multiple sclerosis and neuromyelitis optica spectrum disorder

Herein, we combined neurite orientation dispersion and density imaging (NODDI) and synthetic magnetic resonance imaging (SyMRI) to evaluate the spatial distribution and extent of gray matter (GM) microstructural alterations in patients with relapsing-remitting multiple sclerosis (RRMS) and neuromyelitis optica spectrum disorder (NMOSD). The NODDI (neurite density index [NDI], orientation dispersion index [ODI], and isotropic volume fraction [ISOVF]) and SyMRI (myelin volume fraction [MVF]) measures were compared between age- and sex-matched groups of 30 patients with RRMS (6 males and 24 females; mean age, 51.43 ± 8.02 years), 18 patients with anti-aquaporin-4 antibody-positive NMOSD (2 males and 16 females; mean age, 52.67 ± 16.07 years), and 19 healthy controls (6 males and 13 females; mean age, 51.47 ± 9.25 years) using GM-based spatial statistical analysis. Patients with RRMS showed reduced NDI and MVF and increased ODI and ISOVF, predominantly in the limbic and paralimbic regions, when compared with healthy controls, while only increases in ODI and ISOVF were observed when compared with NMOSD. Compared to NDI and MVF, the changes in ODI and ISOVF were observed more widely, including in the cerebellar cortex. These abnormalities were associated with disease progression and disability. In contrast, patients with NMOSD only showed reduced NDI mainly in the cerebellar, limbic, and paralimbic cortices when compared with healthy controls and patients with RRMS. Taken together, our study supports the notion that GM pathologies in RRMS are distinct from those of NMOSD. However, owing to the limitations of the study, the results should be cautiously interpreted.

Relationship Between White Matter Lesions and Gray Matter Atrophy in Multiple Sclerosis: A Systematic Review

Background and Objectives

There is currently no consensus about the extent of gray matter (GM) atrophy that can be attributed to secondary changes after white matter (WM) lesions or the temporal and spatial relationships between the 2 phenomena. Elucidating this interplay will broaden the understanding of the combined inflammatory and neurodegenerative pathophysiology of multiple sclerosis (MS), and separating atrophic changes due to primary and secondary neurodegenerative mechanisms will then be pivotal to properly evaluate treatment effects, especially if these treatments target the different processes individually. To untangle these complex pathologic mechanisms, this systematic review provides an essential first step: an objective and comprehensive overview of the existing in vivo knowledge of the relationship between brain WM lesions and GM atrophy in patients diagnosed with MS. The overall aim was to clarify the extent to which WM lesions are associated with both global and regional GM atrophy and how this may differ in the different disease subtypes.

Methods

We searched MEDLINE (through PubMed) and Embase for reports containing direct associations between brain GM and WM lesion measures obtained by conventional MRI sequences in patients with clinically isolated syndrome and MS. No restriction was applied for publication date. The quality and risk of bias in included studies were evaluated with the Quality Assessment Tool for observational cohort and cross-sectional studies (NIH, Bethesda, MA). Qualitative and descriptive analyses were performed.

Results

A total of 90 articles were included. WM lesion volumes were related mostly to global, cortical and deep GM volumes, and those significant associations were almost without exception negative, indicating that higher WM lesion volumes were associated with lower GM volumes or lower cortical thicknesses. The most consistent relationship between WM lesions and GM atrophy was seen in early (relapsing) disease and less so in progressive MS.

Discussion

The findings suggest that GM neurodegeneration is mostly secondary to damage in the WM during early disease stages while becoming more detached and dominated by other, possibly primary neurodegenerative disease mechanisms in progressive MS.

Longitudinal changes of deep gray matter shape in multiple sclerosis

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Specific shape changes over time occur at the bilateral ventrolateral pallidal and the left posterolateral striatal surface in relapse-onset multiple sclerosis.

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These shape changes over time were not associated with disease progression.

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The average shape of deep gray matter structures was associated with the patients’ average disease severity as well as white matter lesion-load.

Objective

This study aimed to investigate longitudinal deep gray matter (DGM) shape changes and their relationship with measures of clinical disability and white matter lesion-load in a large multiple sclerosis (MS) cohort.

Materials and Methods

A total of 230 MS patients (179 relapsing-remitting, 51 secondary progressive; baseline age 44.5 ± 11.3 years; baseline disease duration 12.99 ± 9.18) underwent annual clinical and MRI examinations over a maximum of 6 years (mean 4.32 ± 2.07 years). The DGM structures were segmented on the T1-weighted images using the “Multiple Automatically Generated Templates” brain algorithm. White matter lesion-load was measured on T2-weighted MRI. Clinical examination included the expanded disability status scale, 9-hole peg test, timed 25-foot walk test, symbol digit modalities test and paced auditory serial addition test. Vertex‐wise longitudinal analysis of DGM shapes was performed using linear mixed effect models and evaluated the association between average/temporal changes of DGM shapes with average/temporal changes of clinical measurements, respectively.

Results

A significant shrinkage over time of the bilateral ventrolateral pallidal and the left posterolateral striatal surface was observed, whereas no significant shape changes over time were observed at the bilateral thalamic and right striatal surfaces. Higher average lesion-load was associated with an average inwards displacement of the global thalamic surface with relative sparing on the posterior side (slight left-side predominance), the antero-dorso-lateral striatal surfaces bilaterally (symmetric on both sides) and the antero-lateral pallidal surface (left-side predominance). There was also an association between shrinkage of large lateral DGM surfaces with higher clinical motor and cognitive disease severity. However, there was no correlation between any DGM shape changes over time and measurements of clinical progression or lesion-load changes over time.

Conclusions

This study showed specific shape change of DGM structures occurring over time in relapse-onset MS. Although these shape changes over time were not associated with disease progression, we demonstrated a link between DGM shape and the patients’ average disease severity as well as white matter lesion-load.

Myelin Quantification in White Matter Pathology of Progressive Multiple Sclerosis Post-Mortem Brain Samples: A New Approach for Quantifying Remyelination

Multiple sclerosis (MS) is a demyelinating and neurodegenerative disease of the central nervous system (CNS). Repair through remyelination can be extensive, but quantification of remyelination remains challenging. To date, no method for standardized digital quantification of remyelination of MS lesions exists. This methodological study aims to present and validate a novel standardized method for myelin quantification in progressive MS brains to study myelin content more precisely. Fifty-five MS lesions in 32 tissue blocks from 14 progressive MS cases and five tissue blocks from 5 non-neurological controls were sampled. MS lesions were selected by macroscopic investigation of WM by standard histopathological methods. Tissue sections were stained for myelin with luxol fast blue (LFB) and histological assessment of de- or remyelination was performed by light microscopy. The myelin quantity was estimated with a novel myelin quantification method (MQM) in ImageJ. Three independent raters applied the MQM and the inter-rater reliability was calculated. We extended the method to diffusely appearing white matter (DAWM) and encephalitis to test potential wider applicability of the method. Inter-rater agreement was excellent (ICC = 0.96) and there was a high reliability with a lower- and upper limit of agreement up to −5.93% to 18.43% variation in myelin quantity. This study builds on the established concepts of histopathological semi-quantitative assessment of myelin and adds a novel, reliable and accurate quantitative measurement tool for the assessment of myelination in human post-mortem samples.

Single-cell Transcriptional Changes in Neurodegenerative Diseases

In recent decades, our understanding of the molecular changes involved in neurodegenerative diseases has been transformed. Single-cell RNA sequencing and single-nucleus RNA sequencing technologies have been applied to provide cellular and molecular details of the brain at the single-cell level. This has expanded our knowledge of the central nervous system and provided insights into the molecular vulnerability of brain cell types and underlying mechanisms in neurodegenerative diseases. In this review, we highlight the recent advances and findings related to neurodegenerative diseases using these cutting-edge technologies.

Deficits in Early Sensory and Cognitive Processing Are Related to Phase and Nonphase EEG Activity in Multiple Sclerosis Patients

Currently, there is scarce knowledge about the relation between spectral bands modulations and the basis of cognitive impairment in multiple sclerosis (MS). In this sense, analyzing the evoked or phase activity can confirm results from traditional event-related potential (ERP) studies. However, studying the induced or nonphase activity may be necessary to elucidate hidden compensatory or affected cognitive mechanisms. In this study, 30 remitting-relapsing multiple sclerosis patients and 30 healthy controls (HCs) matched in sociodemographic variables performed a visual oddball task. The main goal was to analyze phase and nonphase alpha and gamma bands by applying temporal spectral evolution (TSE) and its potential relation with cognitive impairment in these patients. The behavioural results showed slower reaction time and poorer accuracy in MS patients compared to controls. In contrast, the time-frequency analysis of electroencephalography (EEG) revealed a delay in latency and lower amplitude in MS patients in evoked and induced alpha compared to controls. With respect to the gamma band, there were no differences between the groups. In summary, MS patients showed deficits in early sensorial (evoked alpha activity) and cognitive processing (induced alpha activity in longer latencies), whereas the induced gamma band supported the hypothesis of its role in translation of attentional focus (induced activity) and did not show strong activity in this paradigm (visual oddball).

Histopathology-validated recommendations for cortical lesion imaging in multiple sclerosis

Cortical demyelinating lesions are clinically important in multiple sclerosis, but notoriously difficult to visualize with MRI. At clinical field strengths, double inversion recovery MRI is most sensitive, but still only detects 18% of all histopathologically validated cortical lesions. More recently, phase-sensitive inversion recovery was suggested to have a higher sensitivity than double inversion recovery, although this claim was not histopathologically validated. Therefore, this retrospective study aimed to provide clarity on this matter by identifying which MRI sequence best detects histopathologically-validated cortical lesions at clinical field strength, by comparing sensitivity and specificity of the thus far most commonly used MRI sequences, which are T₂, fluid-attenuated inversion recovery (FLAIR), double inversion recovery and phase-sensitive inversion recovery. Post-mortem MRI was performed on non-fixed coronal hemispheric brain slices of 23 patients with progressive multiple sclerosis directly after autopsy, at 3 T, using T₁ and proton-density/T₂-weighted, as well as FLAIR, double inversion recovery and phase-sensitive inversion recovery sequences. A total of 93 cortical tissue blocks were sampled from these slices. Blinded to histopathology, all MRI sequences were consensus scored for cortical lesions. Subsequently, tissue samples were stained for proteolipid protein (myelin) and scored for cortical lesion types I–IV (mixed grey matter/white matter, intracortical, subpial and cortex-spanning lesions, respectively). MRI scores were compared to histopathological scores to calculate sensitivity and specificity per sequence. Next, a retrospective (unblinded) scoring was performed to explore maximum scoring potential per sequence. Histopathologically, 224 cortical lesions were detected, of which the majority were subpial. In a mixed model, sensitivity of T₁, proton-density/T₂, FLAIR, double inversion recovery and phase-sensitive inversion recovery was 8.9%, 5.4%, 5.4%, 22.8% and 23.7%, respectively (20, 12, 12, 51 and 53 cortical lesions). Specificity of the prospective scoring was 80.0%, 75.0%, 80.0%, 91.1% and 88.3%. Sensitivity and specificity did not significantly differ between double inversion recovery and phase-sensitive inversion recovery, while phase-sensitive inversion recovery identified more lesions than double inversion recovery upon retrospective analysis (126 versus 95; P < 0.001). We conclude that, at 3 T, double inversion recovery and phase-sensitive inversion recovery sequences outperform conventional sequences T₁, proton-density/T₂ and FLAIR. While their overall sensitivity does not exceed 25%, double inversion recovery and phase-sensitive inversion recovery are highly pathologically specific when using existing scoring criteria and their use is recommended for optimal cortical lesion assessment in multiple sclerosis.

Engine Failure in Axo-Myelinic Signaling: A Potential Key Player in the Pathogenesis of Multiple Sclerosis

Multiple Sclerosis (MS) is a complex and chronic disease of the central nervous system (CNS), characterized by both degenerative and inflammatory processes leading to axonal damage, demyelination, and neuronal loss. In the last decade, the traditional outside-in standpoint on MS pathogenesis, which identifies a primary autoimmune inflammatory etiology, has been challenged by a complementary inside-out theory. By focusing on the degenerative processes of MS, the axo-myelinic system may reveal new insights into the disease triggering mechanisms. Oxidative stress (OS) has been widely described as one of the means driving tissue injury in neurodegenerative disorders, including MS. Axonal mitochondria constitute the main energy source for electrically active axons and neurons and are largely vulnerable to oxidative injury. Consequently, axonal mitochondrial dysfunction might impair efficient axo-glial communication, which could, in turn, affect axonal integrity and the maintenance of axonal, neuronal, and synaptic signaling. In this review article, we argue that OS-derived mitochondrial impairment may underline the dysfunctional relationship between axons and their supportive glia cells, specifically oligodendrocytes and that this mechanism is implicated in the development of a primary cytodegeneration and a secondary pro-inflammatory response (inside-out), which in turn, together with a variably primed host's immune system, may lead to the onset of MS and its different subtypes.

Association of serum levels and receptor genes BsmI, TaqI and FokI polymorphisms of vitamin D with the severity of multiple sclerosis

PURPOSE

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease. Vitamin D has a major role in preventing inflammatory disorders. Therefore, any alteration in vitamin D receptor (VDR) might be a genetic risk factor for MS development. This study aimed to evaluate the effect of serum levels and VDR FokI, BsmI, and TaqI gene polymorphisms on the severity of MS.

METHODS

This case-control study recruited 160 MS patients (71.9% females, mean age of 34.3 ± 8.3 years) and 162 (66.7% females, mean age 35.4 ± 7.9 year) age, sex, and ethnicity matched healthy controls. FokI (rs2228570), BsmI (rs1544410), and TaqI (rs731236) polymorphisms were carried out using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Demographic, clinical parameters, and the levels of vitamin D were compared between groups.

RESULTS

We found that the frequency of FokI and TaqI polymorphisms significantly differed between the patients and the controls (p = 0.0127 and p = 0.0236, respectively). The MS patients had low levels of vitamin D compared to the controls (p = 0.011). In addition, TaqI T/C polymorphism significantly decreased the levels of vitamin D in the MS patients (p = 0.002). However, there was no significant association between FokI or BsmI SNPs and the levels of vitamin D in MS patients (p > 0.5).

CONCLUSION

Our results suggest that FokI and TaqI polymorphisms of VDR are associated with MS risk and TaqI polymorphism is associated with Vitamin D levels in MS patients. Meanwhile, no difference was observed between VDR gene polymorphisms and any types of MS.

mGlu3 receptor regulates microglial cell reactivity in neonatal rats

BACKGROUND

Perinatal inflammation is a key factor of brain vulnerability in neonates born preterm or with intra-uterine growth restriction (IUGR), two leading conditions associated with brain injury and responsible for neurocognitive and behavioral disorders. Systemic inflammation is recognized to activate microglia, known to be the critical modulators of brain vulnerability. Although some evidence supports a role for metabotropic glutamate receptor 3 (mGlu3 receptor) in modulation of neuroinflammation, its functions are still unknown in the developing microglia.

METHODS

We used a double-hit rat model of perinatal brain injury induced by a gestational low-protein diet combined with interleukin-1β injections (LPD/IL-1β), mimicking both IUGR and prematurity-related inflammation. The effect of LPD/IL-1β on mGlu3 receptor expression and the effect of mGlu3 receptor modulation on microglial reactivity were investigated using a combination of pharmacological, histological, and molecular and genetic approaches.

RESULTS

Exposure to LPD/IL-1β significantly downregulated Grm3 gene expression in the developing microglia. Both transcriptomic analyses and pharmacological modulation of mGlu3 receptor demonstrated its central role in the control of inflammation in resting and activated microglia. Microglia reactivity to inflammatory challenge induced by LPD/IL-1β exposure was reduced by an mGlu3 receptor agonist. Conversely, both specific pharmacological blockade, siRNA knock-down, and genetic knock-out of mGlu3 receptors mimicked the pro-inflammatory phenotype observed in microglial cells exposed to LPD/IL-1β.

CONCLUSIONS

Overall, these data show that Grm3 plays a central role in the regulation of microglial reactivity in the immature brain. Selective pharmacological activation of mGlu3 receptors may prevent inflammatory-induced perinatal brain injury.

Three-dimensional whole-brain simultaneous T1, T2, and T1ρ quantification using MR Multitasking: Method and initial clinical experience in tissue characterization of multiple sclerosis

PURPOSE

To develop a 3D whole-brain simultaneous T1/T2/T1ρ quantification method with MR Multitasking that provides high quality, co-registered multiparametric maps in 9 min.

METHODS

MR Multitasking conceptualizes T1/T2/T1ρ relaxations as different time dimensions, simultaneously resolving all three dimensions with a low-rank tensor image model. The proposed method was validated on a phantom and in healthy volunteers, comparing quantitative measurements against corresponding reference methods and evaluating the scan-rescan repeatability. Initial clinical validation was performed in age-matched relapsing-remitting multiple sclerosis (RRMS) patients to examine the feasibility of quantitative tissue characterization and to compare with the healthy control cohort. The feasibility of synthesizing six contrast-weighted images was also examined.

RESULTS

Our framework produced high quality, co-registered T1/T2/T1ρ maps that closely resemble the reference maps. Multitasking T1/T2/T1ρ measurements showed substantial agreement with reference measurements on the phantom and in healthy controls. Bland-Altman analysis indicated good in vivo repeatability of all three parameters. In RRMS patients, lesions were conspicuously delineated on all three maps and on four synthetic weighted images (T2-weighted, T2-FLAIR, double inversion recovery, and a novel "T1ρ-FLAIR" contrast). T1 and T2 showed significant differences for normal appearing white matter between patients and controls, while T1ρ showed significant differences for normal appearing white matter, cortical gray matter, and deep gray matter. The combination of three parameters significantly improved the differentiation between RRMS patients and healthy controls, compared to using any single parameter alone.

CONCLUSION

MR Multitasking simultaneously quantifies whole-brain T1/T2/T1ρ and is clinically promising for quantitative tissue characterization of neurological diseases, such as MS.

Lesion load assessment among multiple sclerosis patient using DIR, FLAIR, and T2WI sequences

Background

Magnetic resonance imaging (MRI) is one of the diagnostic imaging modalities employing in lesion detection in neurological disorders such as multiple sclerosis (MS). Advances in MRI techniques such as double inversion recovery (DIR) made it more sensitive to distinguish lesions in the brain. To investigate the lesion load on different anatomical regions of the brain with MS using DIR, fluid attenuated inversion recovery (FLAIR) and T2-weighted imaging (T2WI) sequences. A total of 97 MS patients were included in our retrospective study, confirmed by neurologist. The patients were randomly selected from the major hospital in Saudi Arabia. All images were obtained using 3T Scanner (Siemens Skyra). The images from the DIR, FLAIR, and T2WI sequence were compared on axial planes with identical anatomic position and the number of lesions was assigned to their anatomical region.

Results

Comparing the lesion load measurement at various brain anatomical regions showed a significant difference among those three methods (p < 0.05).

Conclusion

DIR is a valuable MRI sequence for better delineation, greater contrast measurements and the increasing total number of MS lesions in MRI, compared with FLAIR, and T2WI and DIR revealed more intracortical lesions as well; therefore, in MS patients, it is recommended to add DIR sequence in daily routine imaging sequences.

Current Methods of Magnetic Resonance for Noninvasive Assessment of Molecular Aspects of Pathoetiology in Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease with expanding axonal and neuronal degeneration in the central nervous system leading to motoric dysfunctions, psychical disability, and cognitive impairment during MS progression. The exact cascade of pathological processes (inflammation, demyelination, excitotoxicity, diffuse neuro-axonal degeneration, oxidative and metabolic stress, etc.) causing MS onset is still not fully understood, although several accompanying biomarkers are particularly suitable for the detection of early subclinical changes. Magnetic resonance (MR) methods are generally considered to be the most sensitive diagnostic tools. Their advantages include their noninvasive nature and their ability to image tissue in vivo. In particular, MR spectroscopy (proton 1H and phosphorus 31P MRS) is a powerful analytical tool for the detection and analysis of biomedically relevant metabolites, amino acids, and bioelements, and thus for providing information about neuro-axonal degradation, demyelination, reactive gliosis, mitochondrial and neurotransmitter failure, cellular energetic and membrane alternation, and the imbalance of magnesium homeostasis in specific tissues. Furthermore, the MR relaxometry-based detection of accumulated biogenic iron in the brain tissue is useful in disease evaluation. The early description and understanding of the developing pathological process might be critical for establishing clinically effective MS-modifying therapies.

Can Operant Conditioning of EMG-Evoked Responses Help to Target Corticospinal Plasticity for Improving Motor Function in People With Multiple Sclerosis?

Corticospinal pathway and its function are essential in motor control and motor rehabilitation. Multiple sclerosis (MS) causes damage to the brain and descending connections, and often diminishes corticospinal function. In people with MS, neural plasticity is available, although it does not necessarily remain stable over the course of disease progress. Thus, inducing plasticity to the corticospinal pathway so as to improve its function may lead to motor control improvements, which impact one's mobility, health, and wellness. In order to harness plasticity in people with MS, over the past two decades, non-invasive brain stimulation techniques have been examined for addressing common symptoms, such as cognitive deficits, fatigue, and spasticity. While these methods appear promising, when it comes to motor rehabilitation, just inducing plasticity or having a capacity for it does not guarantee generation of better motor functions. Targeting plasticity to a key pathway, such as the corticospinal pathway, could change what limits one's motor control and improve function. One of such neural training methods is operant conditioning of the motor-evoked potential that aims to train the behavior of the corticospinal-motoneuron pathway. Through up-conditioning training, the person learns to produce the rewarded neuronal behavior/state of increased corticospinal excitability, and through iterative training, the rewarded behavior/state becomes one's habitual, daily motor behavior. This minireview introduces operant conditioning approach for people with MS. Guiding beneficial CNS plasticity on top of continuous disease progress may help to prolong the duration of maintained motor function and quality of life in people living with MS.

Myelination- and immune-mediated MR-based brain network correlates

Background

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS), characterized by inflammatory and neurodegenerative processes. Despite demyelination being a hallmark of the disease, how it relates to neurodegeneration has still not been completely unraveled, and research is still ongoing into how these processes can be tracked non-invasively. Magnetic resonance imaging (MRI) derived brain network characteristics, which closely mirror disease processes and relate to functional impairment, recently became important variables for characterizing immune-mediated neurodegeneration; however, their histopathological basis remains unclear.

Methods

In order to determine the MRI-derived correlates of myelin dynamics and to test if brain network characteristics derived from diffusion tensor imaging reflect microstructural tissue reorganization, we took advantage of the cuprizone model of general demyelination in mice and performed longitudinal histological and imaging analyses with behavioral tests. By introducing cuprizone into the diet, we induced targeted and consistent demyelination of oligodendrocytes, over a period of 5 weeks. Subsequent myelin synthesis was enabled by reintroduction of normal food.

Results

Using specific immune-histological markers, we demonstrated that 2 weeks of cuprizone diet induced a 52% reduction of myelin content in the corpus callosum (CC) and a 35% reduction in the neocortex. An extended cuprizone diet increased myelin loss in the CC, while remyelination commenced in the neocortex. These histologically determined dynamics were reflected by MRI measurements from diffusion tensor imaging. Demyelination was associated with decreased fractional anisotropy (FA) values and increased modularity and clustering at the network level. MRI-derived modularization of the brain network and FA reduction in key anatomical regions, including the hippocampus, thalamus, and analyzed cortical areas, were closely related to impaired memory function and anxiety-like behavior.

Conclusion

Network-specific remyelination, shown by histology and MRI metrics, determined amelioration of functional performance and neuropsychiatric symptoms. Taken together, we illustrate the histological basis for the MRI-driven network responses to demyelination, where increased modularity leads to evolving damage and abnormal behavior in MS. Quantitative information about in vivo myelination processes is mirrored by diffusion-based imaging of microstructural integrity and network characteristics.

Recent advances in understanding multiple sclerosis

Emerging data point to important contributions of both autoimmune inflammation and progressive degeneration in the pathophysiology of multiple sclerosis (MS). Unfortunately, after decades of intensive investigation, the fundamental cause remains unknown. A large body of research on the immunobiology of MS has resulted in a variety of anti-inflammatory therapies that are highly effective at reducing brain inflammation and clinical/radiological relapses. However, despite potent suppression of inflammation, benefit in the more important and disabling progressive phase is extremely limited; thus, progressive MS has emerged as the greatest challenge for the MS research and clinical communities. Data obtained over the years point to a complex interplay between environment (e.g., the near-absolute requirement of Epstein-Barr virus exposure), immunogenetics (strong associations with a large number of immune genes), and an ever more convincing role of an underlying degenerative process resulting in demyelination (in both white and grey matter regions), axonal and neuro-synaptic injury, and a persistent innate inflammatory response with a seemingly diminishing role of T cell-mediated autoimmunity as the disease progresses. Together, these observations point toward a primary degenerative process, one whose cause remains unknown but one that entrains a nearly ubiquitous secondary autoimmune response, as a likely sequence of events underpinning this disease. Here, we briefly review what is known about the potential pathophysiological mechanisms, focus on progressive MS, and discuss the two main hypotheses of MS pathogenesis that are the topic of vigorous debate in the field: whether primary autoimmunity or degeneration lies at the foundation. Unravelling this controversy will be critically important for developing effective new therapies for the most disabling later phases of this disease.

Localised grey matter atrophy in multiple sclerosis is network-based: a coordinate-based meta-analysis

AIM

To test the network degeneration hypothesis in multiple sclerosis (MS) with a two-stage coordinate-based meta-analysis by: (1) characterising regional selectivity of grey matter (GM) atrophy and (2) testing for functional connectivity involving these regions.

MATERIALS AND METHODS

Meta-analytic sources included 33 journal articles (1,666 MS patients and 1,269 healthy controls) with coordinate-based results from voxel-based morphometry analysis demonstrating GM atrophy. Mass univariate and multivariate coordinate-based meta-analyses were performed to identify a convergent pattern of GM atrophy and determine inter-regional co-activation (as a surrogate of functional connectivity), with anatomical likelihood estimation and functional meta-analytic connectivity modelling, respectively.

RESULTS

Localised GM atrophy was demonstrated in the thalamus, putamen, caudate, sensorimotor cortex, insula, superior temporal gyrus, and cingulate gyrus. This convergent pattern of atrophy displayed significant inter-regional functional co-activations.

CONCLUSION

In MS, GM atrophy was regionally selective, and these regions were functionally connected. The meta-analytic model-based results of this study are intended to guide future development of quantitative neuroimaging markers for diagnosis, evaluating disease progression, and monitoring treatment response.

Multiple brain networks support processing speed abilities of patients with multiple sclerosis

Objectives: Many people affected by multiple sclerosis (MS) experience cognitive impairment, especially decreases in information processing speed (PS). Neural disconnection is thought to represent the neural marker of this symptom, although the role played by alterations of specific functional brain networks still remains unclear. The aim is to investigate and compare patterns of association between PS-demanding cognitive performance and functional connectivity across two MS phenotypes. Methods: Forty patients with relapsing-remitting MS (RRMS) and 25 with secondary progressive MS (SPMS) had neuropsychological and MRI assessments. Multiple regression models were used to investigate the relationship between performance on tests of visuomotor and verbal PS, and on the verbal fluency tests, and functional connectivity of four cognitive networks, i.e. left and right frontoparietal, salience and default-mode, and two control networks, i.e. visual and sensorimotor. Results: Patients with SPMS were older and had longer disease history than patients with RRMS and presented with worse overall clinical conditions: higher disease severity, total lesion volume, and cognitive impairment rates. However, in both patient samples, cognitive performance across tests was negatively correlated with functional connectivity of the salience and default-mode networks, and positively with connectivity of the left frontoparietal network. Only the visuomotor PS scores of the RRMS group were also associated with connectivity of the sensorimotor network. Conclusions: PS-demanding cognitive performance in patients with MS appears mainly associated with strength of functional connectivity of frontal networks involved in the evaluation and manipulation of information, as well as the default mode network. These results are in line with the hypothesis that multiple neural networks are needed to support normal cognitive performance across MS phenotypes. However, different PS measures showed partially different patterns of association with functional connectivity. Therefore, further investigations are needed to clarify the contribution of inter-network communication to specific cognitive deficits due to MS.

Optimizing 3D FLAIR to detect MS lesions: pushing past factory settings for precise results

BACKGROUND

To assess the diagnostic value of three 3D FLAIR sequences with differing repetition-times (TR) at 3-Tesla when detecting multiple sclerosis (MS) lesions.

METHODS

In this prospective study, approved by the institutional review board, 27 patients with confirmed MS were prospectively included. One radiologist performed manual segmentations of all high-signal intensity lesions using three 3D FLAIR data sets with different TR of 4800 ms ("FLAIR₄₈₀₀"), 8000 ms ("FLAIR₈₀₀₀") and 10,000 ms ("FLAIR_10,000") and two radiologists double-checked it. The main judgment criterion was the overall number of lesions; secondary objectives were the assessment of lesion location, as well as measuring contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). A non-parametric Wilcoxon's test was used to compare the differing FLAIR.

RESULTS

The FLAIR₈₀₀₀ and FLAIR_10,000 detected significantly more overall lesions per patient as compared with the FLAIR₄₈₀₀ [116.1 (± 61.7) (p = 0.02) and 115.8 (± 56.3) (p = 0.03) versus 99.2 (± 66.9), respectively]. The FLAIR₈₀₀₀ and FLAIR_10,000 detected four and eight times more cortical or juxta-cortical lesions per patient as compared with FLAIR₄₈₀₀ [1.6 (± 2.2) (p = 0.001) and 4.1 (± 5.9) (p = 6 × 10^-5) versus 0.4 (± 1.1), respectively]. CNR was significantly correlated to the TR value. It was significantly higher with FLAIR_10,000 than it was with FLAIR₈₀₀₀ and FLAIR₄₈₀₀ [16.3 (± 3.5) versus 15 (± 2.4) (p = 0.01) and 12 (± 2.2) (p = 2 × 10^-6), respectively] CONCLUSION: An optimized 3D FLAIR with a long TR significantly improved both overall lesion detection and CNR in MS patients as compared to a 3D FLAIR with factory settings.

Improving Detection of Multiple Sclerosis Lesions in the Posterior Fossa Using an Optimized 3D-FLAIR Sequence at 3T

BACKGROUND AND PURPOSE

There is no consensus regarding the best MR imaging sequence for detecting MS lesions. The aim of our study was to assess the diagnostic value of optimized 3D-FLAIR in the detection of infratentorial MS lesions compared with an axial T2-weighted imaging, a 3D-FLAIR with factory settings, and a 3D double inversion recovery sequence.

MATERIALS AND METHODS

In this prospective study, 27 patients with confirmed MS were included. Two radiologists blinded to clinical data independently read the following sequences: axial T2WI, 3D double inversion recovery, standard 3D-FLAIR with factory settings, and optimized 3D-FLAIR. The main judgment criterion was the overall number of high-signal-intensity lesions in the posterior fossa; secondary objectives were the assessment of the reading confidence and the measurement of the contrast. A nonparametric Wilcoxon test was used to compare the MR images.

RESULTS

Twenty-two patients had at least 1 lesion in the posterior fossa. The optimized FLAIR sequence detected significantly more posterior fossa lesions than any other sequence: 7.5 versus 5.8, 4.8, and 4.1 (P values of .04, .03, and .03) with the T2WI, the double inversion recovery, and the standard FLAIR, respectively. The reading confidence index was significantly higher with the optimized FLAIR, and the contrast was significantly higher with the optimized FLAIR than with the standard FLAIR and the double inversion recovery.

CONCLUSIONS

An optimized 3D-FLAIR sequence improved posterior fossa lesion detection in patients with MS.

Aging and Brain Atrophy in Multiple Sclerosis

BACKGROUND AND PURPOSE

Brain atrophy accelerates at the age of 60 in healthy individuals (HI) and at disease onset in multiple sclerosis (MS) patients. Whether there is an exacerbating effect of aging superimposed on MS-related brain atrophy is unknown. We estimated the aging effect on lateral ventricular volume (LVV) and whole brain volume (WBV) changes in MS patients.

METHODS

1,982 MS patients (mean follow-up: 4.8 years) and 351 HI (mean follow-up: of 3.1 years), aged from 20 to 79 years old (yo), were collected retrospectively. Percent LVV change (PLVVC) and percent brain volume change (PBVC) on 1.5T and 3T MRI scanners (median of 3.9 scans per subject) were calculated. These were determined between all-time points and subjects were divided in six-decade age groups. MRI differences between age groups were calculated using analysis of covariance (ANCOVA).

RESULTS

Compared to HI, at first MRI, MS patients had significantly increased LVV in the age groups: 30-39 yo, 40-49 yo, 50-59 yo, 60-69 yo (all P < .0001), and 70-79 yo (P = .029), and decreased WBV in the age groups: 20-29 yo (P = .024), 30-39 yo (P = .031), 40-49 yo, and 50-59 yo (all P < .0001). Annualized PLVVC was significantly different between the age groups 20-59 and 60-79 yo in MS patients (P = .005) and HI (P < .0001), as was for PBVC in MS patients (P = .001), but not for HI (P = .521). There was a significant aging interaction effect in the annualized PLVVC (P = .001) between HI and MS patients, which was not observed for the annualized PBVC (P = .380).

CONCLUSIONS

Development of brain atrophy manifests progressively in MS patients, and occurs with a different pattern, as compared to aging HI. PLVVC increased across age in HI as compared to MS, while PBVC decreased across ages in both HI and MS.

Cognitive impairment in an animal model of multiple sclerosis and its amelioration by glatiramer acetate

The severe motor impairment in the MS animal model experimental autoimmune encephalomyelitis (EAE) obstructs the assessment of cognitive functions. We developed an experimental system that evaluates memory faculties in EAE-affected mice, irrespective of their motor performance, enabling the assessment of cognitive impairments along the disease duration, the associated brain damage, and the consequences of glatiramer acetate (GA) treatment on these manifestations. The delayed-non-matching to sample (DNMS) T-maze task, testing working and long term memory was adapted and utilized. Following the appearance of clinical manifestations task performances of the EAE-untreated mice drastically declined. Cognitive impairments were associated with disease severity, as indicated by a significant correlation between the T-maze performance and the clinical symptoms in EAE-untreated mice. GA-treatment conserved cognitive functions, so that despite their exhibited mild motor impairments, the treated mice performed similarly to naïve controls. The cognitive deficit of EAE-mice coincided with inflammatory and neurodegenerative damage to the frontal cortex and the hippocampus; these damages were alleviated by GA-treatment. These combined findings indicate that in addition to motor impairment, EAE leads to substantial impairment of cognitive functions, starting at the early stages and increasing with disease aggravation. GA-treatment, conserves cognitive capacities and prevents its disease related deterioration.

Personalized pathology maps to quantify diffuse and focal brain damage

Background and objectives

Quantitative MRI (qMRI) permits the quantification of brain changes compatible with inflammation, degeneration and repair in multiple sclerosis (MS) patients. In this study, we propose a new method to provide personalized maps of tissue alterations and longitudinal brain changes based on different qMRI metrics, which provide complementary information about brain pathology.

Methods

We performed baseline and two-years follow-up on (i) 13 relapsing-remitting MS patients and (ii) four healthy controls. A group consisting of up to 65 healthy controls was used to compute the reference distribution of qMRI metrics in healthy tissue. All subjects underwent 3T MRI examinations including T1, T2, T2* relaxation and Magnetization Transfer Ratio (MTR) imaging. We used a recent partial volume estimation algorithm to estimate the concentration of different brain tissue types on T1 maps; then, we computed a deviation map (z-score map) for each contrast at both time-points. Finally, we subtracted those deviation maps only for voxels showing a significant difference with healthy tissue in one of the time points, to obtain a difference map for each subject.

Results and conclusion

Control subjects did not show any significant z-score deviations or longitudinal z-score changes. On the other hand, MS patients showed brain regions with cross-sectional and longitudinal concomitant increase in T1, T2, T2* z-scores and decrease of MTR z-scores, suggesting brain tissue degeneration/loss. In the lesion periphery, we observed areas with cross-sectional and longitudinal decreased T1/T2 and slight decrease in T2* most likely related to iron accumulation. Moreover, we measured longitudinal decrease in T1, T2 - and to a lesser extent in T2* - as well as a concomitant increase in MTR, suggesting remyelination/repair.

In summary, we have developed a method that provides whole-brain personalized maps of cross-sectional and longitudinal changes in MS patients, which are computed in patient space. These maps may open new perspectives to complement and support radiological evaluation of brain damage for a given patient.

Metabotropic Glutamate Receptors in Glial Cells: A New Potential Target for Neuroprotection?

Neurodegenerative disorders are characterized by excitotoxicity and neuroinflammation that finally lead to slow neuronal degeneration and death. Although neurons are the principal target, glial cells are important players as they contribute by either exacerbating or dampening the events that lead to neuroinflammation and neuronal damage. A dysfunction of the glutamatergic system is a common event in the pathophysiology of these diseases. Metabotropic glutamate (mGlu) receptors belong to a large family of G protein-coupled receptors largely expressed in neurons as well as in glial cells. They often appear overexpressed in areas involved in neurodegeneration, where they can modulate glutamatergic transmission. Of note, mGlu receptor upregulation may involve microglia or, even more frequently, astrocytes, where their activation causes release of factors potentially able to influence neuronal death. The expression of mGlu receptors has been also reported on oligodendrocytes, a glial cell type specifically involved in the development of multiple sclerosis. Here we will provide a general overview on the possible involvement of mGlu receptors expressed on glial cells in the pathogenesis of different neurodegenerative disorders and the potential use of subtype-selective mGlu receptor ligands as candidate drugs for the treatment of neurodegenerative disorders. Negative allosteric modulators (NAM) of mGlu5 receptors might represent a relevant pharmacological tool to develop new neuroprotective strategies in these diseases. Recent evidence suggests that targeting astrocytes and microglia with positive allosteric modulators (PAM) of mGlu3 receptor or oligodendrocytes with mGlu4 PAMS might represent novel pharmacological approaches for the treatment of neurodegenerative disorders.

Multiple sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system in young adults. This disorder is a heterogeneous, multifactorial, immune-mediated disease that is influenced by both genetic and environmental factors. In most patients, reversible episodes of neurological dysfunction lasting several days or weeks characterize the initial stages of the disease (that is, clinically isolated syndrome and relapsing-remitting MS). Over time, irreversible clinical and cognitive deficits develop. A minority of patients have a progressive disease course from the onset. The pathological hallmark of MS is the formation of demyelinating lesions in the brain and spinal cord, which can be associated with neuro-axonal damage. Focal lesions are thought to be caused by the infiltration of immune cells, including T cells, B cells and myeloid cells, into the central nervous system parenchyma, with associated injury. MS is associated with a substantial burden on society owing to the high cost of the available treatments and poorer employment prospects and job retention for patients and their caregivers.