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WIREs Mechanisms of Disease Jan 2023Axonal loss in multiple sclerosis (MS) is a key component of disease progression and permanent neurologic disability. MS is a heterogeneous demyelinating and... (Review)
Review
Axonal loss in multiple sclerosis (MS) is a key component of disease progression and permanent neurologic disability. MS is a heterogeneous demyelinating and neurodegenerative disease of the central nervous system (CNS) with varying presentation, disease courses, and prognosis. Immunomodulatory therapies reduce the frequency and severity of inflammatory demyelinating events that are a hallmark of MS, but there is minimal therapy to treat progressive disease and there is no cure. Data from patients with MS, post-mortem histological analysis, and animal models of demyelinating disease have elucidated patterns of MS pathogenesis and underlying mechanisms of neurodegeneration. MRI and molecular biomarkers have been proposed to identify predictors of neurodegeneration and risk factors for disease progression. Early signs of axonal dysfunction have come to light including impaired mitochondrial trafficking, structural axonal changes, and synaptic alterations. With sustained inflammation as well as impaired remyelination, axons succumb to degeneration contributing to CNS atrophy and worsening of disease. These studies highlight the role of chronic demyelination in the CNS in perpetuating axonal loss, and the difficulty in promoting remyelination and repair amidst persistent inflammatory insult. Regenerative and neuroprotective strategies are essential to overcome this barrier, with early intervention being critical to rescue axonal integrity and function. The clinical and basic research studies discussed in this review have set the stage for identifying key propagators of neurodegeneration in MS, leading the way for neuroprotective therapeutic development. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.
Topics: Animals; Multiple Sclerosis; Neurodegenerative Diseases; Central Nervous System; Axons; Disease Progression
PubMed: 35948371
DOI: 10.1002/wsbm.1583 -
Der Radiologe Apr 2022Acute disseminated encephalomyelitis (ADEM) is a rare demyelinating disease that occurs predominantly in children. According to the guidelines, ADEM belongs to the... (Review)
Review
BACKGROUND
Acute disseminated encephalomyelitis (ADEM) is a rare demyelinating disease that occurs predominantly in children. According to the guidelines, ADEM belongs to the myelin oligodendrocyte glycoprotein (MOG)-associated diseases and usually manifests after febrile infections (also after SARS-CoV-2) or postvaccinally.
OBJECTIVES
Incidence, course and clinical, and as well, as radiological features and new developments and treatment of ADEM.
METHODS
Analysis and review of the literature on ADEM and of notable cases and guidelines.
RESULTS
The first signs of ADEM include fever, nausea and vomiting, headache and meningism as well as, by definition, encephalopathy, which usually manifests as drowsiness and confusion. The radiological diagnosis is made by magnetic resonance imaging (MRI). Here, the asymmetrically distributed, diffuse and tumefactive lesions can be located supra- and infratentorially. In the acute phase, the lesions usually show contrast enhancement and restricted diffusion. Spinal involvement of the gray matter with the typical H‑pattern with myelitis transversa is not uncommon. ADEM has mostly a monophasic course, with a recurrent form ("relapsing ADEM") in 1-20% of cases. For treatment, steroids and in severe cases immunosuppressive drugs are used.
CONCLUSIONS
ADEM is generally a monophasic disease whose symptoms usually last for a few weeks or months. It is crucial to differentiate ADEM from other demyelinating diseases, like for example multiple sclerosis, in order not to delay the proper treatment.
Topics: Encephalomyelitis, Acute Disseminated; Humans; Magnetic Resonance Imaging; Myelin-Oligodendrocyte Glycoprotein
PubMed: 35290492
DOI: 10.1007/s00117-022-00982-z -
Cell Reports Aug 2022Oligodendrocyte dysfunction has been implicated in the pathogenesis of neurodegenerative diseases, so understanding oligodendrocyte activation states would shed light on... (Meta-Analysis)
Meta-Analysis
Oligodendrocyte dysfunction has been implicated in the pathogenesis of neurodegenerative diseases, so understanding oligodendrocyte activation states would shed light on disease processes. We identify three distinct activation states of oligodendrocytes from single-cell RNA sequencing (RNA-seq) of mouse models of Alzheimer's disease (AD) and multiple sclerosis (MS): DA1 (disease-associated1, associated with immunogenic genes), DA2 (disease-associated2, associated with genes influencing survival), and IFN (associated with interferon response genes). Spatial analysis of disease-associated oligodendrocytes (DAOs) in the cuprizone model reveals that DA1 and DA2 are established outside of the lesion area during demyelination and that DA1 repopulates the lesion during remyelination. Independent meta-analysis of human single-nucleus RNA-seq datasets reveals that the transcriptional responses of MS oligodendrocytes share features with mouse models. In contrast, the oligodendrocyte activation signature observed in human AD is largely distinct from those observed in mice. This catalog of oligodendrocyte activation states (http://research-pub.gene.com/OligoLandscape/) will be important to understand disease progression and develop therapeutic interventions.
Topics: Animals; Cuprizone; Demyelinating Diseases; Disease Models, Animal; Humans; Mice; Mice, Inbred C57BL; Multiple Sclerosis; Neurodegenerative Diseases; Oligodendroglia
PubMed: 36001972
DOI: 10.1016/j.celrep.2022.111189 -
Neurologia 2020Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no... (Review)
Review
INTRODUCTION
Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no such specific model able to provide an overview of the disease; multiple models covering the different pathophysiological features of the disease are therefore necessary.
DEVELOPMENT
We reviewed the different in vitro and in vivo experimental models used in multiple sclerosis research. Concerning in vitro models, we analysed cell cultures and slice models. As for in vivo models, we examined such models of autoimmunity and inflammation as experimental allergic encephalitis in different animals and virus-induced demyelinating diseases. Furthermore, we analysed models of demyelination and remyelination, including chemical lesions caused by cuprizone, lysolecithin, and ethidium bromide; zebrafish; and transgenic models.
CONCLUSIONS
Experimental models provide a deeper understanding of the different pathogenic mechanisms involved in multiple sclerosis. Choosing one model or another depends on the specific aims of the study.
Topics: Animals; Cuprizone; Demyelinating Diseases; Humans; In Vitro Techniques; Multiple Sclerosis; Myelin Sheath; Remyelination
PubMed: 28863829
DOI: 10.1016/j.nrl.2017.07.002 -
Nature Reviews. Drug Discovery Dec 2019Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that involves demyelination and axonal degeneration. Although substantial... (Review)
Review
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that involves demyelination and axonal degeneration. Although substantial progress has been made in drug development for relapsing-remitting MS, treatment of the progressive forms of the disease, which are characterized clinically by the accumulation of disability in the absence of relapses, remains unsatisfactory. This unmet clinical need is related to the complexity of the pathophysiological mechanisms involved in MS progression. Chronic inflammation, which occurs behind a closed blood-brain barrier with activation of microglia and continued involvement of T cells and B cells, is a hallmark pathophysiological feature. Inflammation can enhance mitochondrial damage in neurons, which, consequently, develop an energy deficit, further reducing axonal health. The growth-inhibitory and inflammatory environment of lesions also impairs remyelination, a repair process that might protect axons from degeneration. Moreover, neurodegeneration is accelerated by the altered expression of ion channels on denuded axons. In this Review, we discuss the current understanding of these disease mechanisms and highlight emerging therapeutic strategies based on these insights, including those targeting the neuroinflammatory and degenerative aspects as well as remyelination-promoting approaches.
Topics: Animals; Demyelinating Diseases; Disease Progression; Drug Development; Humans; Inflammation; Multiple Sclerosis; Neurodegenerative Diseases
PubMed: 31399729
DOI: 10.1038/s41573-019-0035-2 -
Frontiers in Immunology 2020Microglia originate from myeloid progenitors in the embryonic yolk sac and play an integral role in central nervous system (CNS) development, immune surveillance and... (Review)
Review
Microglia originate from myeloid progenitors in the embryonic yolk sac and play an integral role in central nervous system (CNS) development, immune surveillance and repair. The role of microglia in multiple sclerosis (MS) has been complex and controversial, with evidence suggesting that these cells play key roles in both active inflammation and remyelination. Here we will review the most recent histological classification of MS lesions as well as the evidence supporting both inflammatory and reparative functions of these cells. We will also review how microglia may yield new biomarkers for MS activity and serve as a potential target for therapy.
Topics: Antirheumatic Agents; Biomarkers; Demyelinating Diseases; Genetic Diseases, Inborn; Humans; Immunologic Surveillance; Macrophages; Microglia; Multiple Sclerosis; Neurodegenerative Diseases; Neuroimaging; T-Lymphocyte Subsets
PubMed: 32265902
DOI: 10.3389/fimmu.2020.00374 -
The Lancet. Neurology Nov 2023Individuals can be deemed to have radiologically isolated syndrome (RIS) if they have incidental demyelinating-appearing lesions in their brain or spinal cord that are... (Review)
Review
Individuals can be deemed to have radiologically isolated syndrome (RIS) if they have incidental demyelinating-appearing lesions in their brain or spinal cord that are highly suggestive of multiple sclerosis but their clinical history does not include symptoms consistent with multiple sclerosis. Data from international longitudinal cohorts indicate that around half of people with RIS will develop relapsing or progressive symptoms of multiple sclerosis within 10 years, suggesting that in some individuals, RIS is a presymptomatic stage of multiple sclerosis. Risk factors for progression from RIS to clinical multiple sclerosis include younger age (ie, <35 years), male sex, CSF-restricted oligoclonal bands, spinal cord or infratentorial lesions, and gadolinium-enhancing lesions. Other imaging, biological, genetic, and digital biomarkers that might be of value in identifying individuals who are at the highest risk of developing multiple sclerosis need further investigation. Two 2-year randomised clinical trials showed the efficacy of approved multiple sclerosis immunomodulatory medications in preventing the clinical conversion to multiple sclerosis in some individuals with RIS. If substantiated in longer-term studies, these data have the potential to transform our approach to care for the people with RIS who are at the greatest risk of diagnosis with multiple sclerosis.
Topics: Humans; Male; Adult; Magnetic Resonance Imaging; Disease Progression; Demyelinating Diseases; Multiple Sclerosis; Spinal Cord
PubMed: 37839432
DOI: 10.1016/S1474-4422(23)00281-8 -
Expert Review of Neurotherapeutics Jan 2020: Leukodystrophies constitute heterogenous group of rare heritable disorders primarily affecting the white matter of central nervous system. These conditions are often... (Review)
Review
: Leukodystrophies constitute heterogenous group of rare heritable disorders primarily affecting the white matter of central nervous system. These conditions are often under-appreciated among physicians. The first clinical manifestations of leukodystrophies are often nonspecific and can occur in different ages from neonatal to late adulthood periods. The diagnosis is, therefore, challenging in most cases.: Herein, the authors discuss different aspects of leukodystrophies. The authors used MEDLINE, EMBASE, and GOOGLE SCHOLAR to provide an extensive update about epidemiology, classifications, pathology, clinical findings, diagnostic tools, and treatments of leukodystrophies. Comprehensive evaluation of clinical findings, brain magnetic resonance imaging, and genetic studies play the key roles in the early diagnosis of individuals with leukodystrophies. No cure is available for most heritable white matter disorders but symptomatic treatments can significantly decrease the burden of events. New genetic methods and stem cell transplantation are also under investigation to further increase the quality and duration of life in affected population.: The improvements in molecular diagnostic tools allow us to identify the meticulous underlying etiology of leukodystrophies and result in higher diagnostic rates, new classifications of leukodystrophies based on genetic information, and replacement of symptomatic managements with more specific targeted therapies. 4H: Hypomyelination, hypogonadotropic hypogonadism and hypodontia; AAV: Adeno-associated virus; AD: autosomal dominant; AGS: Aicardi-Goutieres syndrome; ALSP: Axonal spheroids and pigmented glia; APGBD: Adult polyglucosan body disease; AR: autosomal recessive; ASO: Antisense oligonucleotide therapy; AxD: Alexander disease; BAEP: Brainstem auditory evoked potentials; CAA: Cerebral amyloid angiopathy; CADASIL: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; CARASAL: Cathepsin A-related arteriopathy with strokes and leukoencephalopathy; CARASIL: Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy; CGH: Comparative genomic hybridization; ClC2: Chloride Ion Channel 2; CMTX: Charcot-Marie-Tooth disease, X-linked; CMV: Cytomegalovirus; CNS: central nervous system; CRISP/Cas9: Clustered regularly interspaced short palindromic repeat/CRISPR-associated 9; gRNA: Guide RNA; CTX: Cerebrotendinous xanthomatosis; DNA: Deoxyribonucleic acid; DSB: Double strand breaks; DTI: Diffusion tensor imaging; FLAIR: Fluid attenuated inversion recovery; GAN: Giant axonal neuropathy; H-ABC: Hypomyelination with atrophy of basal ganglia and cerebellum; HBSL: Hypomyelination with brainstem and spinal cord involvement and leg spasticity; HCC: Hypomyelination with congenital cataracts; HEMS: Hypomyelination of early myelinated structures; HMG CoA: Hydroxy methylglutaryl CoA; HSCT: Hematopoietic stem cell transplant; iPSC: Induced pluripotent stem cells; KSS: Kearns-Sayre syndrome; L-2-HGA: L-2-hydroxy glutaric aciduria; LBSL: Leukoencephalopathy with brainstem and spinal cord involvement and elevated lactate; LCC: Leukoencephalopathy with calcifications and cysts; LTBL: Leukoencephalopathy with thalamus and brainstem involvement and high lactate; MELAS: Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke; MERRF: Myoclonic epilepsy with ragged red fibers; MLC: Megalencephalic leukoencephalopathy with subcortical cysts; MLD: metachromatic leukodystrophy; MRI: magnetic resonance imaging; NCL: Neuronal ceroid lipofuscinosis; NGS: Next generation sequencing; ODDD: Oculodentodigital dysplasia; PCWH: Peripheral demyelinating neuropathy-central-dysmyelinating leukodystrophy-Waardenburg syndrome-Hirschprung disease; PMD: Pelizaeus-Merzbacher disease; PMDL: Pelizaeus-Merzbacher-like disease; RNA: Ribonucleic acid; TW: T-weighted; VWM: Vanishing white matter; WES: whole exome sequencing; WGS: whole genome sequencing; X-ALD: X-linked adrenoleukodystrophy; XLD: X-linked dominant; XLR: X-linked recessive.
Topics: Child; Hereditary Central Nervous System Demyelinating Diseases; Humans; Leukoencephalopathies
PubMed: 31829048
DOI: 10.1080/14737175.2020.1699060 -
Neurologia I Neurochirurgia Polska 2020Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system that mostly affects younger adults. However, the first symptoms... (Review)
Review
Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system that mostly affects younger adults. However, the first symptoms of MS can appear in children and adolescents before the age of 18, and we call this paediatric MS (PMS). It is estimated that paediatric MS accounts for 3-5% of the general population of patients with MS. Despite the fundamental si-milarities to adult MS, PMS has many distinctive features. Paediatric MS has a milder course compared to adults, but leads to sig-nificant disability at an early age. PMS is relapsing-remitting in 95-98% of cases; the primary progressive manifestation is much less common than in adults. The differential diagnosis of MS in children should include other childhood demyelinating diseases, mitochondrial and metabolic diseases, connective tissue diseases, and neuroborreliosis. Differentiating acute disseminated en-cephalomyelitis (ADEM) from the first onset of MS remains the biggest challenge. Over the past 10 years, understanding of the epidemiology, pathophysiology, diagnosis, and treatment of MS in children has significantly expanded. The diagnostic criteria leading to earlier diagnosis and initiation of disease-modifying therapy (DMT) have changed, and the number of drugs used in children has increased. However, many important issues require further research. This review discusses the current state of knowledge regarding the epidemiology, diagnosis, and treatment of multiple sclerosis in children.
Topics: Adolescent; Adult; Central Nervous System; Child; Diagnosis, Differential; Humans; Multiple Sclerosis
PubMed: 32940341
DOI: 10.5603/PJNNS.a2020.0069 -
The Journal of Clinical Investigation Apr 2022Proper myelination of axons is crucial for normal sensory, motor, and cognitive function. Abnormal myelination is seen in brain disorders such as major depressive...
Proper myelination of axons is crucial for normal sensory, motor, and cognitive function. Abnormal myelination is seen in brain disorders such as major depressive disorder (MDD), but the molecular mechanisms connecting demyelination with the pathobiology remain largely unknown. We observed demyelination and synaptic deficits in mice exposed to either chronic, unpredictable mild stress (CUMS) or LPS, 2 paradigms for inducing depression-like states. Pharmacological restoration of myelination normalized both synaptic deficits and depression-related behaviors. Furthermore, we found increased ephrin A4 receptor (EphA4) expression in the excitatory neurons of mice subjected to CUMS, and shRNA knockdown of EphA4 prevented demyelination and depression-like behaviors. These animal data are consistent with the decrease in myelin basic protein and the increase in EphA4 levels we observed in postmortem brain samples from patients with MDD. Our results provide insights into the etiology of depressive symptoms in some patients and suggest that inhibition of EphA4 or the promotion of myelination could be a promising strategy for treating depression.
Topics: Animals; Axons; Behavior, Animal; Demyelinating Diseases; Depression; Depressive Disorder, Major; Disease Models, Animal; Hippocampus; Humans; Mice; Receptor, EphA4; Stress, Psychological
PubMed: 35271507
DOI: 10.1172/JCI152187