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1.
Nat Chem Biol ; 18(9): 925-933, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35995862

RESUMO

Remyelination, or the restoration of myelin sheaths around axons in the central nervous system, is a multi-stage repair process that remains a major need for millions of patients with multiple sclerosis and other diseases of myelin. Even into adulthood, rodents and humans can generate new myelin-producing oligodendrocytes, leading to the therapeutic hypothesis that enhancing remyelination could lessen disease burden in multiple sclerosis. Multiple labs have used phenotypic screening to identify dozens of drugs that enhance oligodendrocyte formation, and several hit molecules have now advanced to clinical evaluation. Target identification studies have revealed that a large majority of these hits share the ability to inhibit a narrow range of cholesterol pathway enzymes and thereby induce cellular accumulation of specific sterol precursors to cholesterol. This Perspective surveys the recent fruitful intersection of chemical biology and remyelination and suggests multiple approaches toward new targets and lead molecules to promote remyelination.


Assuntos
Esclerose Múltipla , Remielinização , Adulto , Colesterol/metabolismo , Humanos , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/metabolismo , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Remielinização/fisiologia
2.
Proc Natl Acad Sci U S A ; 118(8)2021 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-33593907

RESUMO

The molecular composition of myelin membranes determines their structure and function. Even minute changes to the biochemical balance can have profound consequences for axonal conduction and the synchronicity of neural networks. Hypothesizing that the earliest indication of myelin injury involves changes in the composition and/or polarity of its constituent lipids, we developed a sensitive spectroscopic technique for defining the chemical polarity of myelin lipids in fixed frozen tissue sections from rodent and human. The method uses a simple staining procedure involving the lipophilic dye Nile Red, whose fluorescence spectrum varies according to the chemical polarity of the microenvironment into which the dye embeds. Nile Red spectroscopy identified histologically intact yet biochemically altered myelin in prelesioned tissues, including mouse white matter following subdemyelinating cuprizone intoxication, as well as normal-appearing white matter in multiple sclerosis brain. Nile Red spectroscopy offers a relatively simple yet highly sensitive technique for detecting subtle myelin changes.


Assuntos
Esclerose Múltipla/patologia , Bainha de Mielina/química , Oligodendroglia/patologia , Oxazinas/química , Espectrometria de Fluorescência/métodos , Idoso , Animais , Estudos de Casos e Controles , Linhagem Celular , Cuprizona/toxicidade , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/patologia , Corantes Fluorescentes , Substância Cinzenta/química , Substância Cinzenta/citologia , Humanos , Lipídeos/química , Masculino , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Oligodendroglia/química , Substância Branca/química , Substância Branca/citologia
3.
Nat Rev Neurosci ; 19(1): 49-58, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29118449

RESUMO

It is widely recognized that myelination of axons greatly enhances the speed of signal transmission. An exciting new finding is the dynamic communication between axons and their myelin-forming oligodendrocytes, including activity-dependent signalling from axon to myelin. The oligodendrocyte-myelin complex may in turn respond by providing metabolic support or alter subtle myelin properties to modulate action potential propagation. In this Opinion, we discuss what is known regarding the molecular physiology of this novel, synapse-like communication and speculate on potential roles in disease states including multiple sclerosis, schizophrenia and Alzheimer disease. An emerging appreciation of the contribution of white-matter perturbations to neurological dysfunction identifies the axo-myelinic synapse as a potential novel therapeutic target.


Assuntos
Axônios/fisiologia , Encefalopatias/fisiopatologia , Bainha de Mielina/fisiologia , Oligodendroglia/fisiologia , Transmissão Sináptica/fisiologia , Animais , Sistema Nervoso Central/fisiologia , Humanos , Modelos Neurológicos
4.
Nat Rev Neurosci ; 19(1): 58, 2017 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-29238086

RESUMO

This corrects the article DOI: 10.1038/nrn.2017.128.

5.
Mult Scler ; 27(7): 1046-1056, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-32779553

RESUMO

BACKGROUND: The balance of tissue injury and repair ultimately determines outcomes of chronic neurological disorders, such as progressive multiple sclerosis (MS). However, the extent of pathology can be difficult to detect, particularly when it is insidious and/or offset by tissue regeneration. OBJECTIVES: The objective of this research is to evaluate whether tissue autofluorescence-typically a source of contamination-provides a surrogate marker of white matter injury. METHODS: Tissue autofluorescence in autopsied specimens both experimental and clinical was characterized by spectral confocal microscopy and correlated to severity and chronicity as determined by standard histopathology. RESULTS: Months after cuprizone (CPZ)-induced demyelination, despite robust remyelination, autofluorescent deposits progressively accumulated in regions of prior pathology. Autofluorescent deposits (likely reflecting myelin debris remnants) were conspicuously localized to white matter, proportional to lesion severity, and displayed differential fluorescence over time. Strikingly, similar features were apparent also in autopsied MS tissue. CONCLUSION: Autofluorescence spectroscopy illuminates prior and ongoing white matter injury. The accumulation of autofluorescence in proportion to the extent of progressive atrophy, despite robust remyelination in the CPZ brain, provides important proof-of-concept of a phenomenon (insidious ongoing damage masked by mechanisms of tissue repair) that we hypothesize is highly relevant to the progressive phase of MS.


Assuntos
Doenças Desmielinizantes , Substância Branca , Animais , Cuprizona , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Bainha de Mielina , Análise Espectral , Substância Branca/diagnóstico por imagem
6.
Proc Natl Acad Sci U S A ; 115(21): 5528-5533, 2018 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-29728463

RESUMO

Although immune attack against central nervous system (CNS) myelin is a central feature of multiple sclerosis (MS), its root cause is unresolved. In this report, we provide direct evidence that subtle biochemical modifications to brain myelin elicit pathological immune responses with radiological and histological properties similar to MS lesions. A subtle myelinopathy induced by abbreviated cuprizone treatment, coupled with subsequent immune stimulation, resulted in lesions of inflammatory demyelination. The degree of myelin injury dictated the resulting immune response; biochemical damage that was too limited or too extensive failed to trigger overt pathology. An inhibitor of peptidyl arginine deiminases (PADs), enzymes that alter myelin structure and correlate with MS lesion severity, mitigated pathology even when administered only during the myelin-altering phase. Moreover, cultured splenocytes were reactive against donor myelin isolates, a response that was substantially muted when splenocytes were exposed to myelin from donors treated with PAD inhibitors. By showing that a primary biochemical myelinopathy can trigger secondary pathological inflammation, "cuprizone autoimmune encephalitis" potentially reconciles conflicting theories about MS pathogenesis and provides a strong rationale for investigating myelin as a primary target for early, preventative therapy.


Assuntos
Doenças Desmielinizantes/etiologia , Modelos Animais de Doenças , Encefalite/patologia , Doença de Hashimoto/patologia , Inflamação/patologia , Esclerose Múltipla/etiologia , Bainha de Mielina/patologia , Animais , Cuprizona/toxicidade , Doenças Desmielinizantes/patologia , Encefalite/induzido quimicamente , Encefalite/imunologia , Doença de Hashimoto/induzido quimicamente , Doença de Hashimoto/imunologia , Humanos , Hidrolases/genética , Hidrolases/metabolismo , Inflamação/induzido quimicamente , Inflamação/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Inibidores da Monoaminoxidase/toxicidade , Esclerose Múltipla/patologia , Bainha de Mielina/imunologia , Bainha de Mielina/metabolismo
7.
Glia ; 66(2): 327-347, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29068088

RESUMO

For decades lysophosphatidylcholine (LPC, lysolecithin) has been used to induce demyelination, without a clear understanding of its mechanisms. LPC is an endogenous lysophospholipid so it may cause demyelination in certain diseases. We investigated whether known receptor systems, inflammation or nonspecific lipid disruption mediates LPC-demyelination in mice. We found that LPC nonspecifically disrupted myelin lipids. LPC integrated into cellular membranes and rapidly induced cell membrane permeability; in mice, LPC injury was phenocopied by other lipid disrupting agents. Interestingly, following its injection into white matter, LPC was cleared within 24 hr but by five days there was an elevation of endogenous LPC that was not associated with damage. This elevation of LPC in the absence of injury raises the possibility that the brain has mechanisms to buffer LPC. In support, LPC injury in culture was significantly ameliorated by albumin buffering. These results shed light on the mechanisms of LPC injury and homeostasis.


Assuntos
Doenças Desmielinizantes/metabolismo , Lisofosfatidilcolinas/metabolismo , Lisofosfatidilcolinas/toxicidade , Lipídeos de Membrana/metabolismo , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/metabolismo , Animais , Células Cultivadas , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/patologia , Feminino , Injeções Intraventriculares , Lisofosfatidilcolinas/administração & dosagem , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Bainha de Mielina/patologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
8.
Bioorg Med Chem ; 25(9): 2643-2656, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28341402

RESUMO

Protein arginine deiminases (PAD) are implicated in a variety of inflammatory and neurodegenerative diseases including multiple sclerosis (MS). Following the discovery of an in silico hit containing hydantoin and a piperidine moiety, we hypothesized that a 2-carbon linker on the hydantoin would be necessary for a 5-membered heterocycle for optimal PAD inhibitory activity. We designed thirteen compounds as potential inhibitors of PAD2 and PAD4 enzymes-two important PAD enzymes implicated in MS. Two compounds, one with an imidazole moiety (22) and the other with a tetrazole moiety (24) showed good inhibition of PAD isozymes in vitro and in the EAE mouse model of MS in vivo. Further experiments suggested that compound 22, a non-covalent inhibitor of PAD2 and PAD4, exhibits dose-dependent efficacy in the EAE mouse model and in the cuprizone-mediated demyelination model.


Assuntos
Inibidores Enzimáticos/uso terapêutico , Hidantoínas/uso terapêutico , Hidrolases/antagonistas & inibidores , Imidazóis/uso terapêutico , Esclerose Múltipla/tratamento farmacológico , Tetrazóis/uso terapêutico , Animais , Encéfalo/patologia , Domínio Catalítico , Cuprizona , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/tratamento farmacológico , Encefalite/induzido quimicamente , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Feminino , Meia-Vida , Humanos , Hidantoínas/administração & dosagem , Hidantoínas/química , Hidantoínas/farmacocinética , Imidazóis/administração & dosagem , Imidazóis/química , Imidazóis/farmacocinética , Isoenzimas/antagonistas & inibidores , Masculino , Camundongos Endogâmicos C57BL , Simulação de Acoplamento Molecular , Mielite/induzido quimicamente , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/farmacocinética , Fármacos Neuroprotetores/uso terapêutico , Medula Espinal/patologia , Tetrazóis/administração & dosagem , Tetrazóis/química , Tetrazóis/farmacocinética
9.
J Neurosci ; 35(41): 14031-41, 2015 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-26468203

RESUMO

During mammalian development, myelin-forming oligodendrocytes are generated and axons ensheathed according to a tightly regulated sequence of events. Excess premyelinating oligodendrocytes are eliminated by apoptosis and the timing of the onset of myelination in any specific CNS region is highly reproducible. Although the developing CNS recovers more effectively than the adult CNS from similar insults, it is unknown whether early loss of oligodendrocyte lineage cells leads to long-term functional deficits. To directly assess whether the loss of oligodendrocytes during early postnatal spinal cord development impacted oligodendrogenesis, myelination, and remyelination, transgenic mouse lines were generated in which a modified caspase-9 molecule allowed spatial and temporal control of the apoptotic pathway specifically in mature, myelin basic protein expressing oligodendrocytes (MBP-iCP9). Activating apoptosis in MBP(+) cells of the developing spinal cord during the first postnatal week inhibited myelination. This inhibition was transient, and the levels of myelination largely returned to normal after 2 weeks. Despite robust developmental plasticity, MBP-iCP9-induced oligodendrocyte apoptosis compromised the rate and extent of adult remyelination. Remyelination failure correlated with a truncated proliferative response of oligodendrocyte progenitor cells, suggesting that depleting the oligodendrocyte pool during critical developmental periods compromises the regenerative response to subsequent demyelinating lesions. SIGNIFICANCE STATEMENT: This manuscript demonstrates that early insults leading to oligodendrocyte apoptosis result in the impairment of recovery from demyelinating diseases in the adult. These studies begin to provide an initial understanding of the potential failure of recovery in insults, such as periventricular leukomalacia and multiple sclerosis.


Assuntos
Apoptose/genética , Doenças Desmielinizantes , Oligodendroglia/patologia , Medula Espinal/crescimento & desenvolvimento , Medula Espinal/patologia , Fatores Etários , Animais , Animais Recém-Nascidos , Caspase 9/genética , Caspase 9/metabolismo , Células Cultivadas , Doenças Desmielinizantes/genética , Doenças Desmielinizantes/patologia , Doenças Desmielinizantes/fisiopatologia , Dimerização , Modelos Animais de Doenças , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Lisofosfatidilcolinas/farmacologia , Masculino , Camundongos , Camundongos Transgênicos , Proteína Básica da Mielina/genética , Oligodendroglia/ultraestrutura , Fator de Crescimento Derivado de Plaquetas/metabolismo , Tubulina (Proteína)/metabolismo
10.
Nat Methods ; 8(11): 957-62, 2011 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-21946668

RESUMO

Myelin-related disorders such as multiple sclerosis and leukodystrophies, for which restoration of oligodendrocyte function would be an effective treatment, are poised to benefit greatly from stem cell biology. Progress in myelin repair has been constrained by difficulties in generating pure populations of oligodendrocyte progenitor cells (OPCs) in sufficient quantities. Pluripotent stem cells theoretically provide an unlimited source of OPCs, but current differentiation strategies are poorly reproducible and generate heterogenous populations of cells. Here we provide a platform for the directed differentiation of pluripotent mouse epiblast stem cells (EpiSCs) through defined developmental transitions into a pure population of highly expandable OPCs in 10 d. These OPCs robustly differentiate into myelinating oligodendrocytes in vitro and in vivo. Our results demonstrate that mouse pluripotent stem cells provide a pure population of myelinogenic oligodendrocytes and offer a tractable platform for defining the molecular regulation of oligodendrocyte development and drug screening.


Assuntos
Oligodendroglia/citologia , Células-Tronco/citologia , Animais , Diferenciação Celular , Humanos
11.
Ann Neurol ; 72(3): 395-405, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23034912

RESUMO

OBJECTIVE: Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that presents with variable pathologies that may reflect different disease-causing mechanisms. Existing animal models of MS induce pathology using either local injection of gliotoxins or stimulation of the immune system with myelin-related peptides. In none of these models is the primary cellular target well characterized, and although demyelination is a hallmark pathological feature in MS, it is unclear to what extent this reflects local oligodendrocyte loss. To unambiguously identify the effects of oligodendrocyte death in the absence of inflammatory stimulation, we developed a method for experimentally inducing programmed cell death selectively in mature oligodendrocytes and assessed the effects on demyelination, immunological stimulation, and gliosis. The resulting pathology is discussed relative to observed MS pathologies. METHODS: Oligodendrocyte apoptosis was induced in the adult rat brain using a lentivirus to express experimentally inducible caspase 9 (iCP9) cDNA under transcriptional control of the promoter for myelin basic protein, which is oligodendrocyte-specific. Activation of iCP9 was achieved by distal injection of a small molecule dimerizer into the lateral ventricle resulting in localized, acute oligodendrocyte apoptosis. RESULTS: Induced oligodendrocyte apoptosis resulted in rapid demyelination and robust, localized microglial activation in the absence of peripheral immune cell infiltration. Lesion borders showed layers of preserved and degraded myelin, whereas lesion cores were demyelinated but only partially cleared of myelin debris. This resulted in local proliferation and mobilization of the oligodendrocyte progenitor pool. INTERPRETATION: This approach provides a novel model to understand the pathological changes that follow from localized apoptosis of myelinating oligodendrocytes. It provides the first direct proof that initiation of apoptosis in oligodendrocytes is sufficient to cause rapid demyelination, gliosis, and a microglial response that result in lesions sharing some pathological characteristics with a subset of MS lesions.


Assuntos
Apoptose/fisiologia , Encéfalo/metabolismo , Encéfalo/patologia , Doenças Desmielinizantes/patologia , Oligodendroglia/fisiologia , Animais , Apoptose/genética , Fator Apoptótico 1 Ativador de Proteases/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Caspase 9/genética , Caspase 9/metabolismo , Contagem de Células , Células Cultivadas , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/metabolismo , Modelos Animais de Doenças , Ativação Enzimática , Gangliosídeos/metabolismo , Proteína Glial Fibrilar Ácida , Gliotoxina/farmacologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Imunossupressores/farmacologia , Proteína Básica da Mielina , Proteínas do Tecido Nervoso/metabolismo , Antígenos O/metabolismo , Fator de Transcrição 2 de Oligodendrócitos , Multimerização Proteica/efeitos dos fármacos , Ratos , Tacrolimo/farmacologia , Transdução Genética/métodos , Transfecção/métodos
12.
Cell Rep ; 42(12): 113574, 2023 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-38100356

RESUMO

Multiple sclerosis (MS) is an inflammatory disease characterized by myelin loss. While therapies exist to slow MS progression, no treatment currently exists for remyelination. Remyelination, linked to reduced disability in MS, relies on microglia and monocyte-derived macrophages (MDMs). This study aims to understand the role of microglia during remyelination by lineage tracing and depleting them. Microglial lineage tracing reveals that both microglia and MDMs initially accumulate, but microglia later dominate the lesion. Microglia and MDMs engulf equal amounts of inhibitory myelin debris, but after microglial depletion, MDMs compensate by engulfing more myelin debris. Microglial depletion does, however, reduce the recruitment and proliferation of oligodendrocyte progenitor cells (OPCs) and impairs their subsequent differentiation and remyelination. These findings underscore the essential role of microglia during remyelination and offer insights for enhancing this process by understanding microglial regulation of remyelination.


Assuntos
Doenças Desmielinizantes , Esclerose Múltipla , Remielinização , Humanos , Bainha de Mielina/patologia , Microglia/patologia , Doenças Desmielinizantes/patologia , Macrófagos/patologia , Esclerose Múltipla/patologia
13.
Mol Neurodegener ; 17(1): 34, 2022 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-35526004

RESUMO

BACKGROUND: The dietary consumption of cuprizone - a copper chelator - has long been known to induce demyelination of specific brain structures and is widely used as model of multiple sclerosis. Despite the extensive use of cuprizone, the mechanism by which it induces demyelination are still unknown. With this review we provide an updated understanding of this model, by showcasing two distinct yet overlapping modes of action for cuprizone-induced demyelination; 1) damage originating from within the oligodendrocyte, caused by mitochondrial dysfunction or reduced myelin protein synthesis. We term this mode of action 'intrinsic cell damage'. And 2) damage to the oligodendrocyte exerted by inflammatory molecules, brain resident cells, such as oligodendrocytes, astrocytes, and microglia or peripheral immune cells - neutrophils or T-cells. We term this mode of action 'extrinsic cellular damage'. Lastly, we summarize recent developments in research on different forms of cell death induced by cuprizone, which could add valuable insights into the mechanisms of cuprizone toxicity. With this review we hope to provide a modern understanding of cuprizone-induced demyelination to understand the causes behind the demyelination in MS.


Assuntos
Cuprizona , Doenças Desmielinizantes , Animais , Astrócitos/metabolismo , Cuprizona/metabolismo , Cuprizona/toxicidade , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/metabolismo , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Bainha de Mielina , Oligodendroglia/metabolismo
14.
Mol Neurodegener ; 17(1): 82, 2022 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-36514132

RESUMO

BACKGROUND: Microglia regulate the response to injury and disease in the brain and spinal cord. In white matter diseases microglia may cause demyelination. However, how microglia respond and regulate demyelination is not fully understood. METHODS: To understand how microglia respond during demyelination, we fed mice cuprizone-a potent demyelinating agent-and assessed the dynamics of genetically fate-mapped microglia. We then used single-cell RNA sequencing to identify and track the microglial subpopulations that arise during demyelination. To understand how microglia contribute to the clearance of dead oligodendrocytes, we ablated microglia starting at the peak of cuprizone-induced cell death and used the viability dye acridine orange to monitor apoptotic and lytic cell morphologies after microglial ablation. Lastly, we treated serum-free primary microglial cultures to model distinct aspects of cuprizone-induced demyelination and assessed the response. RESULTS: The cuprizone diet generated a robust microglial response by week 4 of the diet. Single-cell RNA sequencing at this time point revealed the presence of several cuprizone-associated microglia (CAM) clusters. These clusters expressed a transcriptomic signature indicative of cytokine regulation and reactive oxygen species production with altered lysosomal and metabolic changes consistent with ongoing phagocytosis. Using acridine orange to monitor apoptotic and lytic cell death after microglial ablation, we found that microglia preferentially phagocytose lytic carcasses. In culture, microglia exposed to lytic carcasses partially recapitulated the CAM state, suggesting that phagocytosis contributes to this distinct microglial state during cuprizone demyelination. CONCLUSIONS: Microglia serve multiple roles during demyelination, yet their transcriptomic state resembles other neurodegenerative conditions. The phagocytosis of cellular debris is likely a universal cause for a common neurodegenerative microglial state.


Assuntos
Cuprizona , Doenças Desmielinizantes , Animais , Camundongos , Cuprizona/toxicidade , Cuprizona/metabolismo , Microglia/metabolismo , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/metabolismo , Transcriptoma , Laranja de Acridina/efeitos adversos , Laranja de Acridina/metabolismo , Camundongos Endogâmicos C57BL , Modelos Animais de Doenças
15.
J Neurosci ; 29(46): 14663-9, 2009 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-19923299

RESUMO

Destruction or changes associated with myelin membranes in the CNS play a key role in the pathogenesis of multiple sclerosis and other related neurodegenerative disorders. A long-standing goal has been to detect and quantify myelin content in vivo. For this reason, we have developed a myelin-imaging technique based on positron emission tomography (PET). PET is a quantitative imaging modality that has been widely used in clinical settings for direct assessment of biological processes at the molecular level. However, lack of myelin-imaging probes has hampered the use of PET for imaging of myelination in the CNS. Here, we report a myelin-imaging agent, termed Case Imaging Compound (CIC) that readily penetrates the blood-brain barrier and preferentially localizes to myelinated regions of the brain. After radiolabeling with positron-emitting carbon-11, [(11)C]CIC-PET was conducted in longitudinal studies using a lysolethicin-induced rat model of focal demyelination and subsequent remyelination. Quantitative analysis showed that the retention of [(11)C]CIC correlates with the level of demyelination/remyelination. These studies indicate that, for the first time, [(11)C]CIC-PET can be used as an imaging marker of myelination, which has the potential to be translated into clinical studies in multiple sclerosis and other myelin-related diseases for early diagnosis, subtyping, and efficacy evaluation of therapeutic treatments aimed at myelin repair.


Assuntos
Sistema Nervoso Central/química , Sistema Nervoso Central/fisiologia , Bainha de Mielina/química , Bainha de Mielina/fisiologia , Tomografia por Emissão de Pósitrons , Animais , Sistema Nervoso Central/diagnóstico por imagem , Corpo Caloso/diagnóstico por imagem , Corpo Caloso/fisiologia , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/prevenção & controle , Modelos Animais de Doenças , Feminino , Estudos Longitudinais , Camundongos , Modelos Neurológicos , Bainha de Mielina/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/normas , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes
16.
Sci Adv ; 6(3): eaay6324, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31998844

RESUMO

Microglia and infiltrating macrophages are thought to orchestrate the central nervous system (CNS) response to injury; however, the similarities between these cells make it challenging to distinguish their relative contributions. We genetically labeled microglia and CNS-associated macrophages to distinguish them from infiltrating macrophages. Using single-cell RNA sequencing, we describe multiple microglia activation states, one of which was enriched for interferon associated signaling. Although blood-derived macrophages acutely infiltrated the demyelinated lesion, microglia progressively monopolized the lesion environment where they surrounded infiltrating macrophages. In the microglia-devoid sciatic nerve, the infiltrating macrophage response was sustained. In the CNS, the preferential proliferation of microglia and sparse microglia death contributed to microglia dominating the lesion. Microglia ablation reversed the spatial restriction of macrophages with the demyelinated spinal cord, highlighting an unrealized macrophages-microglia interaction. The restriction of peripheral inflammation by microglia may be a previously unidentified mechanism by which the CNS maintains its "immune privileged" status.


Assuntos
Doenças Desmielinizantes/etiologia , Doenças Desmielinizantes/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Microglia/imunologia , Microglia/metabolismo , Apoptose/genética , Biomarcadores , Proliferação de Células , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/patologia , Biologia Computacional/métodos , Doenças Desmielinizantes/patologia , Imunofluorescência , Perfilação da Expressão Gênica , Ativação de Macrófagos/genética , Ativação de Macrófagos/imunologia , Macrófagos/patologia , Transcriptoma
17.
DNA Cell Biol ; 38(3): 219-222, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30461299

RESUMO

The earliest and most proximal triggers of inflammatory demyelination in multiple sclerosis (MS) remain an open question. In this DNACB review we address experimental and clinical evidence consistent with subtle perturbations of the axo-myelinic compartment of central nervous system white matter as initiation sites of secondary autoimmune demyelination in MS. Strengthened by experimental evidence that by inhibiting myelinopathy one can prevent inflammatory demyelination, myelin-protective therapies may represent a new class of anti-inflammatory medications for combating myelin autoimmunity.


Assuntos
Autoimunidade/imunologia , Esclerose Múltipla/imunologia , Bainha de Mielina/imunologia , Animais , Anti-Inflamatórios/uso terapêutico , Sistema Nervoso Central , Doenças Desmielinizantes/imunologia , Humanos
18.
Sci Rep ; 8(1): 607, 2018 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-29330383

RESUMO

Central nervous system (CNS) demyelination represents the pathological hallmark of multiple sclerosis (MS) and contributes to other neurological conditions. Quantitative and specific imaging of demyelination would thus provide critical clinical insight. Here, we investigated the possibility of targeting axonal potassium channels to image demyelination by positron emission tomography (PET). These channels, which normally reside beneath the myelin sheath, become exposed upon demyelination and are the target of the MS drug, 4-aminopyridine (4-AP). We demonstrate using autoradiography that 4-AP has higher binding in non-myelinated and demyelinated versus well-myelinated CNS regions, and describe a fluorine-containing derivative, 3-F-4-AP, that has similar pharmacological properties and can be labeled with 18F for PET imaging. Additionally, we demonstrate that [18F]3-F-4-AP can be used to detect demyelination in rodents by PET. Further evaluation in Rhesus macaques shows higher binding in non-myelinated versus myelinated areas and excellent properties for brain imaging. Together, these data indicate that [18F]3-F-4-AP may be a valuable PET tracer for detecting CNS demyelination noninvasively.


Assuntos
4-Aminopiridina/administração & dosagem , Doenças Desmielinizantes/diagnóstico por imagem , Radioisótopos de Flúor/química , Tomografia por Emissão de Pósitrons/métodos , Canais de Potássio/metabolismo , 4-Aminopiridina/química , 4-Aminopiridina/farmacologia , Animais , Doenças Desmielinizantes/metabolismo , Feminino , Humanos , Macaca mulatta , Masculino , Camundongos , Traçadores Radioativos , Ratos
19.
J Cell Biol ; 216(4): 1163-1181, 2017 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-28264914

RESUMO

Cellular injury and death are ubiquitous features of disease, yet tools to detect them are limited and insensitive to subtle pathological changes. Acridine orange (AO), a nucleic acid dye with unique spectral properties, enables real-time measurement of RNA and DNA as proxies for cell viability during exposure to various noxious stimuli. This tool illuminates spectral signatures unique to various modes of cell death, such as cells undergoing apoptosis versus necrosis/necroptosis. This new approach also shows that cellular RNA decreases during necrotic, necroptotic, and apoptotic cell death caused by demyelinating, ischemic, and traumatic injuries, implying its involvement in a wide spectrum of tissue pathologies. Furthermore, cells with pathologically low levels of cytoplasmic RNA are detected earlier and in higher numbers than with standard markers including TdT-mediated dUTP biotin nick-end labeling and cleaved caspase 3 immunofluorescence. Our technique highlights AO-labeled cytoplasmic RNA as an important early marker of cellular injury and a sensitive indicator of various modes of cell death in a range of experimental models.


Assuntos
Laranja de Acridina/metabolismo , Apoptose/fisiologia , Morte Celular/fisiologia , Necrose/patologia , Ácidos Nucleicos/metabolismo , Animais , Caspase 3/metabolismo , Linhagem Celular , Nucleotídeos de Desoxiuracil/metabolismo , Humanos , Marcação In Situ das Extremidades Cortadas/métodos , Camundongos Endogâmicos C57BL , Necrose/metabolismo , RNA/metabolismo
20.
Dev Cell ; 34(2): 152-67, 2015 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-26166300

RESUMO

Myelin is essential in vertebrates for the rapid propagation of action potentials, but the molecular mechanisms driving its formation remain largely unknown. Here we show that the initial stage of process extension and axon ensheathment by oligodendrocytes requires dynamic actin filament assembly by the Arp2/3 complex. Unexpectedly, subsequent myelin wrapping coincides with the upregulation of actin disassembly proteins and rapid disassembly of the oligodendrocyte actin cytoskeleton and does not require Arp2/3. Inducing loss of actin filaments drives oligodendrocyte membrane spreading and myelin wrapping in vivo, and the actin disassembly factor gelsolin is required for normal wrapping. We show that myelin basic protein, a protein essential for CNS myelin wrapping whose role has been unclear, is required for actin disassembly, and its loss phenocopies loss of actin disassembly proteins. Together, these findings provide insight into the molecular mechanism of myelin wrapping and identify it as an actin-independent form of mammalian cell motility.


Assuntos
Citoesqueleto de Actina/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/metabolismo , Sistema Nervoso Central/crescimento & desenvolvimento , Bainha de Mielina/fisiologia , Oligodendroglia/fisiologia , Complexo 2-3 de Proteínas Relacionadas à Actina/genética , Actinas/metabolismo , Animais , Axônios/fisiologia , Membrana Celular/fisiologia , Movimento Celular/fisiologia , Células Cultivadas , Sistema Nervoso Central/embriologia , Cofilina 1/genética , Gelsolina/genética , Gelsolina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Básica da Mielina/genética , Proteína Básica da Mielina/metabolismo , Nervo Óptico/metabolismo , Nervo Óptico/fisiologia , Interferência de RNA , RNA Interferente Pequeno , Ratos , Ratos Sprague-Dawley
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