RESUMEN
Multiple sclerosis (MS) is a neurological disorder characterized by immune dysregulation. It begins with a first clinical manifestation, a clinically isolated syndrome (CIS), which evolves to definite MS in case of further clinical and/or neuroradiological episodes. Here we evaluated the diagnostic value of transcriptional alterations in MS and CIS blood by machine learning (ML). Deep sequencing of more than 200 blood RNA samples comprising CIS, MS and healthy subjects, generated transcriptomes that were analyzed by the binary classification workflow to distinguish MS from healthy subjects and the Time-To-Event pipeline to predict CIS conversion to MS along time. To identify optimal classifiers, we performed algorithm benchmarking by nested cross-validation with the train set in both pipelines and then tested models generated with the train set on an independent dataset for final validation. The binary classification model identified a blood transcriptional signature classifying definite MS from healthy subjects with 97% accuracy, indicating that MS is associated with a clear predictive transcriptional signature in blood cells. When analyzing CIS data with ML survival models, prediction power of CIS conversion to MS was about 72% when using paraclinical data and 74.3% when using blood transcriptomes, indicating that blood-based classifiers obtained at the first clinical event can efficiently predict risk of developing MS. Coupling blood transcriptomics with ML approaches enables retrieval of predictive signatures of CIS conversion and MS state, thus introducing early non-invasive approaches to MS diagnosis.
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Aprendizaje Automático , Esclerosis Múltiple , Transcriptoma , Humanos , Esclerosis Múltiple/sangre , Esclerosis Múltiple/genética , Esclerosis Múltiple/diagnóstico , Transcriptoma/genética , Masculino , Femenino , Adulto , Persona de Mediana Edad , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/sangre , Enfermedades Desmielinizantes/diagnóstico , Algoritmos , Perfilación de la Expresión Génica/métodosRESUMEN
Hyponatremia is the most common clinical electrolyte disorder. Chronic hyponatremia has been recently reported to be associated with falls, fracture, osteoporosis, neurocognitive impairment, and mental manifestations. In the treatment of chronic hyponatremia, overly rapid correction of hyponatremia can cause osmotic demyelination syndrome (ODS), a central demyelinating disease that is also associated with neurological morbidity and mortality. Using a rat model, we have previously shown that microglia play a critical role in the pathogenesis of ODS. However, the direct effect of rapid correction of hyponatremia on microglia is unknown. Furthermore, the effect of chronic hyponatremia on microglia remains elusive. Using microglial cell lines BV-2 and 6-3, we show here that low extracellular sodium concentrations (36 mmol/L decrease; LS) suppress Nos2 mRNA expression and nitric oxide (NO) production of microglia. On rapid correction of low sodium concentrations, NO production was significantly increased in both cells, suggesting that acute correction of hyponatremia partly directly contributes to increased Nos2 mRNA expression and NO release in ODS pathophysiology. LS also suppressed expression and nuclear translocation of nuclear factor of activated T cells-5 (NFAT5), a transcription factor that regulates the expression of genes involved in osmotic stress. Furthermore, overexpression of NFAT5 significantly increased Nos2 mRNA expression and NO production in BV-2 cells. Expressions of Nos2 and Nfat5 mRNA were also modulated in microglia isolated from cerebral cortex in chronic hyponatremia model mice. These data indicate that LS modulates microglial NO production dependent on NFAT5 and suggest that microglia contribute to hyponatremia-induced neuronal dysfunctions.
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Hiponatremia , Microglía , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico , Factores de Transcripción , Microglía/metabolismo , Microglía/patología , Animales , Óxido Nítrico/metabolismo , Hiponatremia/metabolismo , Hiponatremia/patología , Hiponatremia/genética , Ratones , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Óxido Nítrico Sintasa de Tipo II/genética , Sodio/metabolismo , Línea Celular , Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/patología , Enfermedades Desmielinizantes/genética , Ratas , Regulación de la Expresión GénicaRESUMEN
We report unusual cases of combined central and peripheral demyelination in two siblings related to pregnancy, each presenting with progressive tetraparesis and cranial nerve palsies. The elder sister had a relapsing-remitting course with optic nerve dysfunction and died during a relapse from respiratory insufficiency. The younger sister presented with disorientation and acute-onset limb and facial weakness. She responded well to corticosteroid therapy. Their clinical presentation, response to immunomodulatory therapy, nerve conduction studies, cerebrospinal fluid and histology supported an acquired demyelinating cause. Whole-exome sequencing identified variants in two genes not previously linked to this clinical phenotype. Serological tests for antibody-mediated demyelination were negative. Despite the undefined pathogenesis, these cases provide a platform to explore the confluence of genetic, immune and environmental factors in the context of acquired demyelination. We discuss the differential diagnosis and a diagnostic approach to such cases from the perspectives of neuroimmunology and neurogenetics.
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Enfermedades Desmielinizantes , Hermanos , Humanos , Femenino , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/diagnóstico , AdultoRESUMEN
Strategies for treating progressive multiple sclerosis (MS) remain limited. Here, we found that miR-145-5p is overabundant uniquely in chronic lesion tissues from secondary progressive MS patients. We induced both acute and chronic demyelination in miR-145 knockout mice to determine its contributions to remyelination failure. Following acute demyelination, no advantage to miR-145 loss could be detected. However, after chronic demyelination, animals with miR-145 loss demonstrated increased remyelination and functional recovery, coincident with altered presence of astrocytes and microglia within the corpus callosum relative to wild-type animals. This improved response in miR-145 knockout animals coincided with a pathological upregulation of miR-145-5p in wild-type animals with chronic cuprizone exposure, paralleling human chronic lesions. Furthermore, miR-145 overexpression specifically in oligodendrocytes (OLs) severely stunted differentiation and negatively impacted survival. RNAseq analysis showed altered transcriptome in these cells with downregulated major pathways involved in myelination. Our data suggest that pathological accumulation of miR-145-5p is a distinctive feature of chronic demyelination and is strongly implicated in the failure of remyelination, possibly due to the inhibition of OL differentiation together with alterations in other glial cells. This is mirrored in chronic MS lesions, and thus miR-145-5p serves as a potential relevant therapeutic target in progressive forms of MS.
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Enfermedades Desmielinizantes , Modelos Animales de Enfermedad , Ratones Noqueados , MicroARNs , Remielinización , MicroARNs/genética , MicroARNs/metabolismo , Animales , Remielinización/genética , Ratones , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/patología , Humanos , Oligodendroglía/metabolismo , Oligodendroglía/patología , Recuperación de la Función , Masculino , Ratones Endogámicos C57BL , Cuprizona/toxicidad , Femenino , Enfermedad Crónica , Vaina de Mielina/metabolismoRESUMEN
BACKGROUND: Lipid droplet (LD)-laden microglia is a key pathological hallmark of multiple sclerosis. The recent discovery of this novel microglial subtype, lipid-droplet-accumulating microglia (LDAM), is notable for increased inflammatory factor secretion and diminished phagocytic capability. Lipophagy, the autophagy-mediated selective degradation of LDs, plays a critical role in this context. This study investigated the involvement of microRNAs (miRNAs) in lipophagy during demyelinating diseases, assessed their capacity to modulate LDAM subtypes, and elucidated the potential underlying mechanisms involved. METHODS: C57BL/6 mice were used for in vivo experiments. Two weeks post demyelination induction at cervical level 4 (C4), histological assessments and confocal imaging were performed to examine LD accumulation in microglia within the lesion site. Autophagic changes were observed using transmission electron microscopy. miRNA and mRNA multi-omics analyses identified differentially expressed miRNAs and mRNAs under demyelinating conditions and the related autophagy target genes. The role of miR-223 in lipophagy under these conditions was specifically explored. In vitro studies, including miR-223 upregulation in BV2 cells via lentiviral infection, validated the bioinformatics findings. Immunofluorescence staining was used to measure LD accumulation, autophagy levels, target gene expression, and inflammatory mediator levels to elucidate the mechanisms of action of miR-223 in LDAM. RESULTS: Oil Red O staining and confocal imaging revealed substantial LD accumulation in the demyelinated spinal cord. Transmission electron microscopy revealed increased numbers of autophagic vacuoles at the injury site. Multi-omics analysis revealed miR-223 as a crucial regulatory gene in lipophagy during demyelination. It was identified that cathepsin B (CTSB) targets miR-223 in autophagy to integrate miRNA, mRNA, and autophagy gene databases. In vitro, miR-223 upregulation suppressed CTSB expression in BV2 cells, augmented autophagy, alleviated LD accumulation, and decreased the expression of the inflammatory mediator IL-1ß. CONCLUSION: These findings indicate that miR-223 plays a pivotal role in lipophagy under demyelinating conditions. By inhibiting CTSB, miR-223 promotes selective LD degradation, thereby reducing the lipid burden and inflammatory phenotype in LDAM. This study broadens the understanding of the molecular mechanisms of lipophagy and proposes lipophagy induction as a potential therapeutic approach to mitigate inflammatory responses in demyelinating diseases.
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Autofagia , Catepsina B , Enfermedades Desmielinizantes , Gotas Lipídicas , Lisofosfatidilcolinas , Ratones Endogámicos C57BL , MicroARNs , Microglía , Animales , MicroARNs/genética , MicroARNs/metabolismo , Microglía/metabolismo , Microglía/patología , Ratones , Gotas Lipídicas/metabolismo , Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/inducido químicamente , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/patología , Catepsina B/metabolismo , Catepsina B/genética , Lisofosfatidilcolinas/metabolismo , Modelos Animales de Enfermedad , Masculino , Regulación de la Expresión Génica , Línea CelularRESUMEN
Stroke is a significant public health issue, and research has consistently focused on studying the mechanisms of injury and identifying new targets. As a CDK5 activator, p39 plays a crucial role in various diseases. In this article, we will explore the role and mechanism of p39 in cerebral ischemic injury. We measured the level of p39 using western blot and QPCR at various time points following cerebral ischemia-reperfusion (I/R) injury. The results indicated a significant reduction in the level of p39. TTC staining and behavioral results indicate that the knockout of p39 (p39KO) provides neuroprotection in the short-term. Interestingly, the behavioral dysfunction in p39KO mice was exacerbated after the repair phase of I/R. Further study revealed that this deterioration may be due to demyelination induced by elevated p35 levels. In summary, our study offers profound insights into the significance of p39 in both the acute and repair stages of ischemic injury recovery and a theoretical foundation for future therapeutic drug exploration.
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Ratones Endogámicos C57BL , Ratones Noqueados , Vaina de Mielina , Daño por Reperfusión , Animales , Masculino , Ratones , Isquemia Encefálica/genética , Isquemia Encefálica/metabolismo , Enfermedades Desmielinizantes/patología , Enfermedades Desmielinizantes/genética , Infarto de la Arteria Cerebral Media/patología , Fosfotransferasas , Daño por Reperfusión/metabolismo , Daño por Reperfusión/patologíaRESUMEN
Remyelination failure in diseases like multiple sclerosis (MS) was thought to involve suppressed maturation of oligodendrocyte precursors; however, oligodendrocytes are present in MS lesions yet lack myelin production. We found that oligodendrocytes in the lesions are epigenetically silenced. Developing a transgenic reporter labeling differentiated oligodendrocytes for phenotypic screening, we identified a small-molecule epigenetic-silencing-inhibitor (ESI1) that enhances myelin production and ensheathment. ESI1 promotes remyelination in animal models of demyelination and enables de novo myelinogenesis on regenerated CNS axons. ESI1 treatment lengthened myelin sheaths in human iPSC-derived organoids and augmented (re)myelination in aged mice while reversing age-related cognitive decline. Multi-omics revealed that ESI1 induces an active chromatin landscape that activates myelinogenic pathways and reprograms metabolism. Notably, ESI1 triggered nuclear condensate formation of master lipid-metabolic regulators SREBP1/2, concentrating transcriptional co-activators to drive lipid/cholesterol biosynthesis. Our study highlights the potential of targeting epigenetic silencing to enable CNS myelin regeneration in demyelinating diseases and aging.
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Epigénesis Genética , Vaina de Mielina , Oligodendroglía , Remielinización , Animales , Vaina de Mielina/metabolismo , Humanos , Ratones , Remielinización/efectos de los fármacos , Oligodendroglía/metabolismo , Sistema Nervioso Central/metabolismo , Ratones Endogámicos C57BL , Rejuvenecimiento , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Organoides/metabolismo , Organoides/efectos de los fármacos , Enfermedades Desmielinizantes/metabolismo , Enfermedades Desmielinizantes/genética , Diferenciación Celular/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/farmacología , Masculino , Regeneración/efectos de los fármacos , Esclerosis Múltiple/metabolismo , Esclerosis Múltiple/genética , Esclerosis Múltiple/tratamiento farmacológico , Esclerosis Múltiple/patologíaRESUMEN
Recent single-cell RNA sequencing studies have revealed distinct microglial states in development and disease. These include proliferative-region-associated microglia (PAMs) in developing white matter and disease-associated microglia (DAMs) prevalent in various neurodegenerative conditions. PAMs and DAMs share a similar core gene signature. However, the extent of the dynamism and plasticity of these microglial states, as well as their functional significance, remains elusive, partly due to the lack of specific tools. Here, we generated an inducible Cre driver line, Clec7a-CreERT2, that targets PAMs and DAMs in the brain parenchyma. Utilizing this tool, we profiled labeled cells during development and in several disease models, uncovering convergence and context-dependent differences in PAM and DAM gene expression. Through long-term tracking, we demonstrated microglial state plasticity. Lastly, we specifically depleted DAMs in demyelination, revealing their roles in disease recovery. Together, we provide a versatile genetic tool to characterize microglial states in CNS development and disease.
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Plasticidad de la Célula , Microglía , Remielinización , Microglía/fisiología , Animales , Ratones , Plasticidad de la Célula/genética , Enfermedades Desmielinizantes/genética , Ratones Endogámicos C57BL , Ratones Transgénicos , Modelos Animales de Enfermedad , Encéfalo , Vaina de Mielina/metabolismo , Sustancia Blanca/patologíaRESUMEN
The taiep rat is a tubulin mutant with an early hypomyelination followed by progressive demyelination of the central nervous system due to a point mutation in the Tubb4a gene. It shows clinical, radiological, and pathological signs like those of the human leukodystrophy hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). Taiep rats had tremor, ataxia, immobility episodes, epilepsy, and paralysis; the acronym of these signs given the name to this autosomal recessive trait. The aim of this study was to analyze the characteristics of somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) in adult taiep rats and in a patient suffering from H-ABC. Additionally, we evaluated the effects of 4-aminopyridine (4-AP) on sensory responses and locomotion and finally, we compared myelin loss in the spinal cord of adult taiep and wild type (WT) rats using immunostaining. Our results showed delayed SSEPs in the upper and the absence of them in the lower extremities in a human patient. In taiep rats SSEPs had a delayed second negative evoked responses and were more susceptible to delayed responses with iterative stimulation with respect to WT. MEPs were produced by bipolar stimulation of the primary motor cortex generating a direct wave in WT rats followed by several indirect waves, but taiep rats had fused MEPs. Importantly, taiep SSEPs improved after systemic administration of 4-AP, a potassium channel blocker, and this drug induced an increase in the horizontal displacement measured in a novelty-induced locomotor test. In taiep subjects have a significant decrease in the immunostaining of myelin in the anterior and ventral funiculi of the lumbar spinal cord with respect to WT rats. In conclusion, evoked potentials are useful to evaluate myelin alterations in a leukodystrophy, which improved after systemic administration of 4-AP. Our results have a translational value because our findings have implications in future medical trials for H-ABC patients or with other leukodystrophies.
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Enfermedades Desmielinizantes , Enfermedades Desmielinizantes del Sistema Nervioso Central Hereditarias , Sustancia Blanca , Ratas , Humanos , Animales , Ratas Mutantes , 4-Aminopiridina/farmacología , Enfermedades Desmielinizantes/tratamiento farmacológico , Enfermedades Desmielinizantes/genética , Cerebelo , Ganglios Basales , Potenciales Evocados , Caminata , AtrofiaRESUMEN
GJB2 gene mutations are the most common causes of autosomal recessive non-syndromic hereditary deafness. For individuals suffering from severe to profound GJB2-related deafness, cochlear implants have emerged as the sole remedy for auditory improvement. Some previous studies have highlighted the crucial role of preserving cochlear neural components in achieving favorable outcomes after cochlear implantation. Thus, we generated a conditional knockout mouse model (Cx26-CKO) in which Cx26 was completely deleted in the cochlear supporting cells driven by the Sox2 promoter. The Cx26-CKO mice showed severe hearing loss and massive loss of hair cells and Deiter's cells, which represented the extreme form of human deafness caused by GJB2 gene mutations. In addition, multiple pathological changes in the peripheral auditory nervous system were found, including abnormal innervation, demyelination, and degeneration of spiral ganglion neurons as well as disruption of heminodes in Cx26-CKO mice. These findings provide invaluable insights into the deafness mechanism and the treatment for severe deafness in Cx26-null mice.
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Conexina 26 , Conexinas , Sordera , Ratones Noqueados , Ganglio Espiral de la Cóclea , Animales , Ganglio Espiral de la Cóclea/patología , Sordera/genética , Sordera/patología , Conexinas/genética , Conexinas/deficiencia , Enfermedades Desmielinizantes/patología , Enfermedades Desmielinizantes/genética , Ratones , Neuronas/patología , Neuronas/metabolismo , Modelos Animales de Enfermedad , Degeneración Nerviosa/patología , Degeneración Nerviosa/genética , Cóclea/patologíaAsunto(s)
Albuterol , Mutación , Síndromes Miasténicos Congénitos , Fenotipo , Humanos , Síndromes Miasténicos Congénitos/tratamiento farmacológico , Síndromes Miasténicos Congénitos/genética , Albuterol/uso terapéutico , Enfermedades Desmielinizantes/tratamiento farmacológico , Enfermedades Desmielinizantes/genética , Masculino , Femenino , Receptores Colinérgicos/genética , Agonistas de Receptores Adrenérgicos beta 2/uso terapéuticoRESUMEN
Although Multiple Sclerosis (MS) is primarily thought to be an autoimmune condition, its possible viral etiology must be taken into consideration. When mice are administered neurotropic viruses like mouse hepatitis virus MHV-A59, a murine coronavirus, or its isogenic recombinant strain RSA59, neuroinflammation along with demyelination are observed, which are some of the significant manifestations of MS. MHV-A59/RSA59 induced neuroinflammation is one of the best-studied experimental animal models to understand the viral-induced demyelination concurrent with axonal loss. In this experimental animal model, one of the major immune checkpoint regulators is the CD40-CD40L dyad, which helps in mediating both acute-innate, innate-adaptive, and chronic-adaptive immune responses. Hence, they are essential in reducing acute neuroinflammation and chronic progressive adaptive demyelination. While CD40 is expressed on antigen-presenting cells and endothelial cells, CD40L is expressed primarily on activated T cells and during severe inflammation on NK cells and mast cells. Experimental evidences revealed that genetic deficiency of both these proteins can lead to deleterious effects in an individual. On the other hand, interferon-stimulated genes (ISGs) possess potent antiviral properties and directly or indirectly alter acute neuroinflammation. In this review, we will discuss the role of an ISG, ISG54, and its tetratricopeptide repeat protein Ifit2; the genetic and experimental studies on the role of CD40 and CD40L in a virus-induced neuroinflammatory demyelination model.
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Antígenos CD40 , Ligando de CD40 , Enfermedades Desmielinizantes , Virus de la Hepatitis Murina , Enfermedades Neuroinflamatorias , Animales , Ligando de CD40/metabolismo , Ligando de CD40/genética , Ligando de CD40/inmunología , Enfermedades Neuroinflamatorias/patología , Enfermedades Neuroinflamatorias/inmunología , Enfermedades Neuroinflamatorias/virología , Enfermedades Desmielinizantes/virología , Enfermedades Desmielinizantes/patología , Enfermedades Desmielinizantes/inmunología , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/metabolismo , Humanos , Antígenos CD40/metabolismo , Antígenos CD40/genética , Antígenos CD40/inmunología , Virus de la Hepatitis Murina/patogenicidad , Virus de la Hepatitis Murina/inmunología , Ratones , Esclerosis Múltiple/inmunología , Esclerosis Múltiple/virología , Esclerosis Múltiple/patología , Esclerosis Múltiple/genética , Esclerosis Múltiple/metabolismo , Modelos Animales de EnfermedadRESUMEN
Genome-wide association studies identified a single nucleotide polymorphism (SNP) downstream of the transcription factor Sox8, associated with an increased risk of multiple sclerosis (MS). Sox8 is known to influence oligodendrocyte terminal differentiation and is involved in myelin maintenance by mature oligodendrocytes. The possible link of a Sox8 related SNP and MS risk, along with the role of Sox8 in oligodendrocyte physiology prompted us to investigate its relevance during de- and remyelination using the cuprizone model. Sox8-/- mice and wildtype littermates received a cuprizone diet for 5 weeks (wk). Sox8-/- mice showed reduced motor performance and weight compared to wildtype controls. Brains were histologically analysed at the maximum of demyelination (wk 5) and on two time points during remyelination (wk 5.5 and wk 6) for oligodendroglial, astroglial, microglial and myelin markers. We identified reduced proliferation of oligodendrocyte precursor cells at wk 5 as well as reduced numbers of mature oligodendrocytes in Sox8-/- mice at wk 6. Moreover, analysis of myelin markers revealed a delay in remyelination in the Sox8-/- group, demonstrating the potential importance of Sox8 in remyelination processes. Our findings present, for the first time, compelling evidence of a significant role of Sox8 in the context of a disease model.
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Enfermedades Desmielinizantes , Esclerosis Múltiple , Remielinización , Ratones , Animales , Cuprizona/toxicidad , Enfermedades Desmielinizantes/inducido químicamente , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/patología , Diferenciación Celular , Estudio de Asociación del Genoma Completo , Oligodendroglía , Vaina de Mielina/patología , Esclerosis Múltiple/inducido químicamente , Esclerosis Múltiple/genética , Esclerosis Múltiple/patología , Ratones Endogámicos C57BL , Modelos Animales de Enfermedad , Factores de Transcripción SOXE/genéticaRESUMEN
BACKGROUND AND AIMS: POLR3B gene encodes a subunit of RNA polymerase III (Pol III). Biallelic mutations in POLR3B are associated with leukodystrophies, but recently de novo heterozygous mutations have been described in early onset peripheral demyelinating neuropathies with or without central involvement. Here, we report the first Italian case carrying a de novo variant in POLR3B with a pure neuropathy phenotype and primary axonal involvement of the largest nerve fibers. METHODS: Nerve conduction studies, sympathetic skin response, dynamic sweat test, tactile and thermal quantitative sensory testing and brain magnetic resonance imaging were performed according to standard procedures. Histopathological examination was performed on skin and sural nerve biopsies. Molecular analysis of the proband and his relatives was performed with Next Generation Sequencing. The impact of the identified variant on the overall protein structure was evaluated through rotamers method. RESULTS: Since his early adolescence, the patient presented with signs of polyneuropathy with severe distal weakness, atrophy, and reduced sensation. Neurophysiological studies showed a sensory-motor axonal polyneuropathy, with confirmed small fiber involvement. In addition, skin biopsy and sural nerve biopsy showed predominant large fibers involvement. A trio's whole exome sequencing revealed a novel de novo variant p.(Arg1046Cys) in POLR3B, which was classified as Probably Pathogenic. Molecular modeling data confirmed a deleterious effect of the variant on protein structure. INTERPRETATION: Neurophysiological and morphological findings suggest a primary axonal involvement of the largest nerve fibers in POLR3B-related neuropathies. A partial loss of function mechanism is proposed for both neuropathy and leukodystrophy phenotypes.
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Enfermedades Desmielinizantes , Enfermedades del Sistema Nervioso Periférico , Polineuropatías , ARN Polimerasa III , Adolescente , Humanos , Axones , Enfermedades Desmielinizantes/genética , Mutación , Fibras Nerviosas/metabolismo , Enfermedades del Sistema Nervioso Periférico/genética , Polineuropatías/genética , Proteínas/genética , ARN Polimerasa III/genética , ARN Polimerasa III/metabolismoRESUMEN
INTRODUCTION: Epileptic encephalopathies (EEs) are a group of heterogeneous epileptic syndromes characterized by early-onset refractory seizures, specific EEG abnormalities, developmental delay or regression and intellectual disability. The genetic spectrum of EE is very wide with mutations in a number of genes having various functions, such as those encoding AMPA ionotropic and glutamate receptors as well as voltage-gated ion channels. However, the list of EE-responsible genes could certainly be enlarged by next-generation sequencing. PATIENTS AND METHODS: The present study reports a clinical investigation and a molecular analysis by the whole exome sequencing (WES) and pyrosequencing of a patient's family affected by epileptic spasms and severe psychomotor delay. RESULTS: Clinical and radiological investigations revealed that the patient presented clinical features of severe and drug-resistant EE-type infantile epileptic spasm syndrome that evolved to Lennox Gastaut syndrome with radiological findings of hypomyelinated leukodystrophy. The results of WES revealed the presence of a novel heterozygous c.466C>T mutation in exon 4 of the TUBB4A gene in the patient. This transition led to the replacement of arginine by cysteine at position 156 (p.R156C) of the conserved helix 4 among the N-terminal domain of the TUBB4A protein. Bioinformatic tools predicted its deleterious effects on the structural arrangement and stability of the protein. The presence of the mutation in the asymptomatic father suggested the hypothesis of somatic mosaicism that was tested by pyrosequencing of DNA from two tissues of the patient and her father. The obtained results showed a lower rate of mutated alleles in the asymptomatic father compared with the affected daughter in both lymphocytes and buccal mucosa cells, confirming the occurrence of paternal mosaicism. The phenotypic features of the patient were also compared with those of previously described patients presenting TUBB4A mutations. CONCLUSIONS: Our study is the first to report a disease-causing variant in the TUBB4A gene in a patient with EE associated with hypomyelinated leucodystrophy. In addition, we expanded the phenotypic spectrum associated with the TUBB4A gene.
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Enfermedades Desmielinizantes , Espasmos Infantiles , Tubulina (Proteína) , Femenino , Humanos , Enfermedades Desmielinizantes/genética , Mosaicismo , Mutación/genética , Espasmos Infantiles/complicaciones , Espasmos Infantiles/diagnóstico por imagen , Espasmos Infantiles/genética , Tubulina (Proteína)/genéticaRESUMEN
TMEM106B, a lysosomal transmembrane protein, has been closely associated with brain health. Recently, an intriguing link between TMEM106B and brain inflammation has been discovered, but how TMEM106B regulates inflammation is unknown. Here, we report that TMEM106B deficiency in mice leads to reduced microglia proliferation and activation and increased microglial apoptosis in response to demyelination. We also found an increase in lysosomal pH and a decrease in lysosomal enzyme activities in TMEM106B-deficient microglia. Furthermore, TMEM106B loss results in a significant decrease in the protein levels of TREM2, an innate immune receptor essential for microglia survival and activation. Specific ablation of TMEM106B in microglia results in similar microglial phenotypes and myelination defects in mice, supporting the idea that microglial TMEM106B is critical for proper microglial activities and myelination. Moreover, the TMEM106B risk allele is associated with myelin loss and decreased microglial numbers in humans. Collectively, our study unveils a previously unknown role of TMEM106B in promoting microglial functionality during demyelination.
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Enfermedades Desmielinizantes , Microglía , Humanos , Ratones , Animales , Microglía/metabolismo , Ratones Noqueados , Encéfalo/metabolismo , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/metabolismo , Proliferación Celular , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Inmunológicos/metabolismoRESUMEN
Astrocytes are the most abundant glial cell type in the brain, where they participate in various homeostatic functions. Transcriptomically, diverse astrocyte subpopulations play distinct roles during development and disease progression. However, the biochemical identification of astrocyte subtypes, especially by membrane surface protein glycosylation, remains poorly investigated. Protein tyrosine phosphatase receptor type zeta (PTPRZ) is a highly expressed membrane protein in CNS glia cells that can be modified with diverse glycosylation, including the unique HNK-1 capped O-mannosyl (O-Man) core M2 glycan mediated by brain-specific branching enzyme GnT-IX. Although PTPRZ modified with HNK-1 capped O-Man glycans (HNK-1-O-Man+ PTPRZ) is increased in reactive astrocytes of demyelination model mice, whether such astrocytes emerge in a broad range of disease-associated conditions or are limited to conditions associated with demyelination remains unclear. Here, we show that HNK-1-O-Man+ PTPRZ localizes in hypertrophic astrocytes of damaged brain areas in patients with multiple sclerosis. Furthermore, we show that astrocytes expressing HNK-1-O-Man+ PTPRZ are present in two demyelination mouse models (cuprizone-fed mice and a vanishing white matter disease model), while traumatic brain injury does not induce glycosylation. Administration of cuprizone to Aldh1l1-eGFP and Olig2KICreER/+ ;Rosa26eGFP mice revealed that cells expressing HNK-1-O-Man+ PTPRZ are derived from cells in the astrocyte lineage. Notably, GnT-IX but not PTPRZ mRNA was up-regulated in astrocytes isolated from the corpus callosum of cuprizone model mice. These results suggest that the unique PTPRZ glycosylation plays a key role in the patterning of demyelination-associated astrocytes.
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Astrocitos , Enfermedades Desmielinizantes , Animales , Ratones , Astrocitos/metabolismo , Encéfalo/metabolismo , Cuprizona/toxicidad , Cuprizona/metabolismo , Enfermedades Desmielinizantes/inducido químicamente , Enfermedades Desmielinizantes/genética , Modelos Animales de Enfermedad , Glicosilación , Ratones Endogámicos C57BL , Polisacáridos/metabolismo , Proteínas Tirosina Fosfatasas/metabolismoRESUMEN
Cuprizone causes consistent demyelination and oligodendrocyte damage in the mouse brain. Cu,Zn-superoxide dismutase 1 (SOD1) has neuroprotective potential against various neurological disorders, such as transient cerebral ischemia and traumatic brain injury. In this study, we investigated whether SOD1 has neuroprotective effects against cuprizone-induced demyelination and adult hippocampal neurogenesis in C57BL/6 mice, using the PEP-1-SOD1 fusion protein to facilitate the delivery of SOD1 protein into hippocampal neurons. Eight weeks feeding of cuprizone-supplemented (0.2%) diets caused a significant decrease in myelin basic protein (MBP) expression in the stratum lacunosum-moleculare of the CA1 region, the polymorphic layer of the dentate gyrus, and the corpus callosum, while ionized calcium-binding adapter molecule 1 (Iba-1)-immunoreactive microglia showed activated and phagocytic phenotypes. In addition, cuprizone treatment reduced proliferating cells and neuroblasts as shown using Ki67 and doublecortin immunostaining. Treatment with PEP-1-SOD1 to normal mice did not show any significant changes in MBP expression and Iba-1-immunoreactive microglia. However, Ki67-positive proliferating cells and doublecortin-immunoreactive neuroblasts were significantly decreased. Simultaneous treatment with PEP-1-SOD1 and cuprizone-supplemented diets did not ameliorate the MBP reduction in these regions, but mitigated the increase of Iba-1 immunoreactivity in the corpus callosum and alleviated the reduction of MBP in corpus callosum and proliferating cells, not neuroblasts, in the dentate gyrus. In conclusion, PEP-1-SOD1 treatment only has partial effects to reduce cuprizone-induced demyelination and microglial activation in the hippocampus and corpus callosum and has minimal effects on proliferating cells in the dentate gyrus.
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Cuprizona , Enfermedades Desmielinizantes , Animales , Ratones , Cuprizona/toxicidad , Superóxido Dismutasa-1/metabolismo , Microglía/metabolismo , Antígeno Ki-67/metabolismo , Enfermedades Desmielinizantes/inducido químicamente , Enfermedades Desmielinizantes/tratamiento farmacológico , Enfermedades Desmielinizantes/genética , Ratones Endogámicos C57BL , Hipocampo/metabolismo , Neurogénesis , Cuerpo Calloso , Proteínas de Dominio Doblecortina , Zinc/metabolismo , Modelos Animales de EnfermedadRESUMEN
Leukodystrophies are a group of rare neurodegenerative disorders, usually presenting in infancy with a variable combination of cognitive, motor, and coordination impairment. Adult-onset cases are even more rare, often representing a diagnostic challenge even for experienced neurologists. Here, we present a case of a 44-year-old man with subacute and rapidly progressive spastic paraplegia, whose brain MRI revealed white matter abnormalities compatible with a diagnosis of leukodystrophy. We discuss how to apply a simplified diagnostic algorithm to distinguish acquired leukoencephalopathies from leukodystrophies and how to delve into the maze of genetic testing for white matter diseases. In our patient, we reached the diagnosis of a treatable disorder, whose early recognition is essential to prevent severe neurologic deterioration.
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Enfermedades Desmielinizantes , Leucoencefalopatías , Enfermedades por Almacenamiento Lisosomal , Paraparesia Espástica , Adulto , Masculino , Humanos , Paraparesia Espástica/etiología , Paraparesia Espástica/genética , Leucoencefalopatías/genética , Imagen por Resonancia Magnética , Pruebas Genéticas , Enfermedades por Almacenamiento Lisosomal/genética , Enfermedades Desmielinizantes/genética , Razonamiento ClínicoRESUMEN
INTRODUCTION: The C1236T, G2677T/A, and C3435T variants of the ABCB1 gene alter the functioning of P-glycoprotein and the transport of endogenous and exogenous substances across the blood-brain barrier, and act as risk factors for some neurodegenerative diseases. This study aimed to determine the association between demyelinating disease and the C1236T, G2677T/A, and C3435T variants of ABCB1 and its haplotypes and combinations of genotypes. METHODS: Polymerase chain reaction with restriction fragment length polymorphism analysis (PCR-RFLP) and Sanger sequencing were used to genotype 199 patients with demyelinating disease and 200 controls, all Mexicans of mixed race; frequencies of alleles, genotypes, haplotypes, and genotype combinations were compared between patients and controls. We conducted a logistic regression analysis and calculated chi-square values and 95% confidence intervals (CI); odds ratios (OR) were calculated to evaluate the association with demyelinating disease. RESULTS: The TTT and CGC haplotypes were most frequent in both patients and controls. The G2677 allele was associated with demyelinating disease (OR: 1.79; 95% CI, 1.12-2.86; Pâ¯=⯠.015), as were the genotypes GG2677 (OR: 2.72; 95% CI, 1.11-6.68; Pâ¯=⯠.025) and CC3435 (OR: 1.82; 95% CI, 1.15-2.90; Pâ¯=⯠.010), the combination GG2677/CC3435 (OR: 2.02; 95% CI, 1.17-3.48; Pâ¯=⯠.010), and the CAT haplotype (OR: 0.21; 95% CI, 0.05-0.66; Pâ¯=⯠.001). TTTTTT carriers presented the earliest age of onset (23.0⯱â¯7.7 years, vs 31.6⯱â¯10.7; Pâ¯=⯠.0001). CONCLUSIONS: The GG2677/CC3435 genotype combination is associated with demyelinating disease in this sample, particularly among men, who may present toxic accumulation of P-glycoprotein substrates. In our study, the G2677 allele of ABCB1 may differentially modulate age of onset of demyelinating disease in men and women.