Molecular Mechanisms of Oligodendrocyte Regeneration in White Matter-Related Diseases

DNA methylation patterns in the frontal lobe white matter of multiple system atrophy, Parkinson's disease, and progressive supranuclear palsy: a cross-comparative investigation

Multiple system atrophy (MSA) is a rare neurodegenerative disease characterized by neuronal loss and gliosis, with oligodendroglial cytoplasmic inclusions (GCIs) containing α-synuclein being the primary pathological hallmark. Clinical presentations of MSA overlap with other parkinsonian disorders, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and progressive supranuclear palsy (PSP), posing challenges in early diagnosis. Numerous studies have reported alterations in DNA methylation in neurodegenerative diseases, with candidate loci being identified in various parkinsonian disorders including MSA, PD, and PSP. Although MSA and PSP present with substantial white matter pathology, alterations in white matter have also been reported in PD. However, studies comparing the DNA methylation architectures of white matter in these diseases are lacking. We therefore aimed to investigate genome-wide DNA methylation patterns in the frontal lobe white matter of individuals with MSA (n = 17), PD (n = 17), and PSP (n = 16) along with controls (n = 15) using the Illumina EPIC array, to identify shared and disease-specific DNA methylation alterations. Genome-wide DNA methylation profiling of frontal lobe white matter in the three parkinsonian disorders revealed substantial commonalities in DNA methylation alterations in MSA, PD, and PSP. We further used weighted gene correlation network analysis to identify disease-associated co-methylation signatures and identified dysregulation in processes relating to Wnt signaling, signal transduction, endoplasmic reticulum stress, mitochondrial processes, RNA interference, and endosomal transport to be shared between these parkinsonian disorders. Our overall analysis points toward more similarities in DNA methylation patterns between MSA and PD, both synucleinopathies, compared to that between MSA and PD with PSP, which is a tauopathy. Our results also highlight several shared DNA methylation changes and pathways indicative of converging molecular mechanisms in the white matter contributing toward neurodegeneration in all three parkinsonian disorders.

IL-1β, the first piece to the puzzle of sepsis-related cognitive impairment?

Sepsis is a leading cause of death resulting from an uncontrolled inflammatory response to an infectious agent. Multiple organ injuries, including brain injuries, are common in sepsis. The underlying mechanism of sepsis-associated encephalopathy (SAE), which is associated with neuroinflammation, is not yet fully understood. Recent studies suggest that the release of interleukin-1β (IL-1β) following activation of microglial cells plays a crucial role in the development of long-lasting neuroinflammation after the initial sepsis episode. This review provides a comprehensive analysis of the recent literature on the molecular signaling pathways involved in microglial cell activation and interleukin-1β release. It also explores the physiological and pathophysiological role of IL-1β in cognitive function, with a particular focus on its contribution to long-lasting neuroinflammation after sepsis. The findings from this review may assist healthcare providers in developing novel interventions against SAE.

Distinctive whole-brain cell types predict tissue damage patterns in thirteen neurodegenerative conditions

For over a century, brain research narrative has mainly centered on neuron cells. Accordingly, most neurodegenerative studies focus on neuronal dysfunction and their selective vulnerability, while we lack comprehensive analyses of other major cell types' contribution. By unifying spatial gene expression, structural MRI, and cell deconvolution, here we describe how the human brain distribution of canonical cell types extensively predicts tissue damage in 13 neurodegenerative conditions, including early- and late-onset Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies, amyotrophic lateral sclerosis, mutations in presenilin-1, and 3 clinical variants of frontotemporal lobar degeneration (behavioral variant, semantic and non-fluent primary progressive aphasia) along with associated three-repeat and four-repeat tauopathies and TDP43 proteinopathies types A and C. We reconstructed comprehensive whole-brain reference maps of cellular abundance for six major cell types and identified characteristic axes of spatial overlapping with atrophy. Our results support the strong mediating role of non-neuronal cells, primarily microglia and astrocytes, in spatial vulnerability to tissue loss in neurodegeneration, with distinct and shared across-disorder pathomechanisms. These observations provide critical insights into the multicellular pathophysiology underlying spatiotemporal advance in neurodegeneration. Notably, they also emphasize the need to exceed the current neuro-centric view of brain diseases, supporting the imperative for cell-specific therapeutic targets in neurodegeneration.

Mapping human tissues with highly multiplexed RNA in situ hybridization

In situ transcriptomic techniques promise a holistic view of tissue organization and cell-cell interactions. There has been a surge of multiplexed RNA in situ mapping techniques but their application to human tissues has been limited due to their large size, general lower tissue quality and high autofluorescence. Here we report DART-FISH, a padlock probe-based technology capable of profiling hundreds to thousands of genes in centimeter-sized human tissue sections. We introduce an omni-cell type cytoplasmic stain that substantially improves the segmentation of cell bodies. Our enzyme-free isothermal decoding procedure allows us to image 121 genes in large sections from the human neocortex in <10 h. We successfully recapitulated the cytoarchitecture of 20 neuronal and non-neuronal subclasses. We further performed in situ mapping of 300 genes on a diseased human kidney, profiled >20 healthy and pathological cell states, and identified diseased niches enriched in transcriptionally altered epithelial cells and myofibroblasts.

Oligodendrocytes Play a Critical Role in White Matter Damage of Vascular Dementia

With the deepening of population aging, the treatment of cognitive impairment and dementia is facing increasing challenges. Vascular dementia (VaD) is a cognitive dysfunction caused by brain blood flow damage and one of the most common causes of dementia after Alzheimer's disease. White matter damage in patients with chronic ischemic dementia often occurs before cognitive impairment, and its pathological changes include leukoaraiosis, myelin destruction and oligodendrocyte death. The pathophysiology of vascular dementia is complex, involving a variety of neuronal and vascular lesions. The current proposed mechanisms include calcium overload, oxidative stress, nitrative stress and inflammatory damage, which can lead to hypoxia-ischemia and demyelination. Oligodendrocytes are the only myelinating cells in the central nervous system and closely associated with VaD. In this review article, we intend to further discuss the role of oligodendrocytes in white matter and myelin injury in VaD and the development of anti-myelin injury target drugs.

Mapping Human Tissues with Highly Multiplexed RNA in situ Hybridization

In situ transcriptomic techniques promise a holistic view of tissue organization and cell-cell interactions. Recently there has been a surge of multiplexed RNA in situ techniques but their application to human tissues and clinical biopsies has been limited due to their large size, general lower tissue quality and high background autofluorescence. Here we report DART-FISH, a versatile padlock probe-based technology capable of profiling hundreds to thousands of genes in centimeter-sized human tissue sections at cellular resolution. We introduced an omni-cell type cytoplasmic stain, dubbed RiboSoma that substantially improves the segmentation of cell bodies. We developed a computational decoding-by-deconvolution workflow to extract gene spots even in the presence of optical crowding. Our enzyme-free isothermal decoding procedure allowed us to image 121 genes in a large section from the human neocortex in less than 10 hours, where we successfully recapitulated the cytoarchitecture of 20 neuronal and non-neuronal subclasses. Additionally, we demonstrated the detection of transcripts as short as 461 nucleotides, including neuropeptides and discovered new cortical layer markers. We further performed in situ mapping of 300 genes on a diseased human kidney, profiled >20 healthy and pathological cell states, and identified diseased niches enriched in transcriptionally altered epithelial cells and myofibroblasts.

Galectin-3 administration drives remyelination after hypoxic-ischemic induced perinatal white matter injury

Hypoxic-ischemic (HI) induced perinatal white matter injury (PWMI) is a major cause of neurologic disabilities characterized by selective oligodendroglial death and myelin disruption. Galectin-3 (Gal-3) modulates postnatal subventricular zone gliogenesis and attenuates ischemic injury. However, the association between Gal-3 and myelin formation still remains unclear. In this study, we first perform Gal-3 knockdown (KD) to identify the importance of Gal-3 on myelin formation. Our results show impeded myelin formation, manifested by Olig2/CC1 (+) mature oligodendrocytes number, expression of oligodendroglial maturation-associated markers (MBP and CNPase), and myelin thickness and integrity. Then we perform recombinant Gal-3 (rGal-3) administration by intracerebroventricular injection. Notably, although rGal-3 administration shows no beneficial effect on oligodendrogenesis and myelin formation under normal condition, our results show that rGal-3 administration attenuates cognitive deficits and drives remyelination after PWMI, which are coupled to signs of enhanced myelin resiliency and cognition. Also, our results indicates that the significant increases in substrates for remyelination of rGal-3 administration are accompanied by enhanced Iba-1 (microglia marker)/ Mrc1 (M2 marker) (+) microglia and decreased Iba-1/ iNOS (M1 marker) (+) microglia. Altogether, our data in this research confirm the association between Gal-3 and myelin formation, underscore its position for the capacity for remyelination and restoration of function, and unveils the efficacy of rGal-3 administration with anti-inflammatory phenotype microglia (M2 microglia) activation. Thus, the findings suggest that Gal-3 plays a significant role in myelin formation and remyelination restoration.

Intellectual Structure and Emerging Trends of White Matter Hyperintensity Studies: A Bibliometric Analysis From 2012 to 2021

White matter hyperintensities (WMHs), which have a significant effect on human health, have received increasing attention since their number of publications has increased in the past 10 years. We aimed to explore the intellectual structure, hotspots, and emerging trends of publications on WMHs using bibliometric analysis from 2012 to 2021. Publications on WMHs from 2012 to 2021 were retrieved from the Web of Science Core Collection. CiteSpace 5.8.R3, VOSviewer 1.6.17, and an online bibliometric analysis platform (Bibliometric. com) were used to quantitatively analyze the trends of publications from multiple perspectives. A total of 29,707 publications on WMHs were obtained, and the number of annual publications generally increased from 2012 to 2021. Neurology had the most publications on WMHs. The top country and institution were the United States and Harvard University, respectively. Massimo Filippi and Stephen M. Smith were the most productive and co-cited authors, respectively. Thematic concentrations primarily included cerebral small vessel disease, diffusion magnetic resonance imaging (dMRI), schizophrenia, Alzheimer’s disease, multiple sclerosis, microglia, and oligodendrocyte. The hotspots were clustered into five groups: white matter and diffusion tensor imaging, inflammation and demyelination, small vessel disease and cognitive impairment, MRI and multiple sclerosis, and Alzheimer’s disease. Emerging trends mainly include deep learning, machine learning, perivascular space, convolutional neural network, neurovascular unit, and neurite orientation dispersion and density imaging. This study presents an overview of publications on WMHs and provides insights into the intellectual structure of WMH studies. Our study provides information to help researchers and clinicians quickly and comprehensively understand the hotspots and emerging trends within WMH studies as well as providing direction for future basic and clinical studies on WMHs.

High Mobility Group A1 Regulates Transcription Levels of Oligodendrocyte Marker Genes in Cultured Oligodendrocyte Precursor Cells

Oligodendrocyte precursor cells (OPCs) serve as progenitor cells of terminally differentiated oligodendrocytes. Past studies have confirmed the importance of epigenetic system in OPC differentiation to oligodendrocytes. High mobility group A1 (HMGA1) is a small non-histone nuclear protein that binds DNA and modifies the chromatin conformational state. However, it is still completely unknown about the roles of HMGA1 in the process of OPC differentiation. In this study, we prepared primary OPC cultures from the neonatal rat cortex and examined whether the loss- and gain-of-function of HMGA1 would change the mRNA levels of oligodendrocyte markers, such as Cnp, Mbp, Myrf, and Plp during the process of OPC differentiation. In our system, the mRNA levels of Cnp, Mbp, Myrf, and Plp increased depending on the oligodendrocyte maturation step, but the level of Hmga1 mRNA decreased. When HMGA1 was knocked down by a siRNA approach, the mRNA levels of Cnp, Mbp, Myrf, and Plp were smaller in OPCs with Hmga1 siRNA compared to the ones in the control OPCs. On the contrary, when HMGA1 expression was increased by transfection of the Hmga1 plasmid, the mRNA levels of Cnp, Mbp, Myrf, and Plp were slightly larger compared to the ones in the control OPCs. These data may suggest that HMGA1 participates in the process of OPC differentiation by regulating the mRNA expression level of myelin-related genes.

Molecular mechanisms of cognitive impairment associated with stroke

Stroke is the second leading cause of death after coronary heart disease in developed countries and is the greatest cause of disability and cognitive impairment. Risk factors for cognitive impairment and dementia after stroke are multifactorial including older age, family history, hypertension, arterial fibrillation, diabetes, genetic variants, low educational status, vascular comorbidities, prior transient ischaemic attack or recurrent stroke, depressive illness duration of a stroke, location, volume, intensity, and degree of neuronal degeneration, location and size of infarction after stroke, time interval after stroke other cerebral dysfunctions. The pathophysiology of stroke associated cognitive impairment is complex and recent molecular, cellular, and animal models studies have revealed that multiple cellular changes have been implicated, including altered redox state, mitochondrial dysfunction, disruption of the blood-brain barrier, perivascular spacing, glymphatic system impairment, microglia activation and amyloid-β deposition in the parenchyma of the brain. These studies have also evidenced the involvement of various transcription factors, intracellular adhesion molecules, and endogenous growth factors in the pathogenesis of cognitive impairment associated with stroke and providing scope for developing therapeutic strategies for treatment. This review summarizes the latest research findings on molecular mechanisms involved in cognitive impairment associated with stroke.

Melatonin Reduces Neuroinflammation and Improves Axonal Hypomyelination by Modulating M1/M2 Microglia Polarization via JAK2-STAT3-Telomerase Pathway in Postnatal Rats Exposed to Lipopolysaccharide

Microglia activation and associated inflammation are implicated in the periventricular white matter damage (PWMD) in septic postnatal rats. This study investigated whether melatonin would mitigate inflammation and alleviate the axonal hypomyelination in the corpus callosum in septic postnatal rats. We further explored if this might be related to the modulation of microglial polarization from M1 phenotype to M2 through the JAK2/STAT3/telomerase pathway. We reported here that indeed melatonin not only can it reduce the neurobehavioral disturbances in LPS-injected rats, but it can also dampen microglia-mediated inflammation. Thus, in LPS + melatonin group, the expression of proinflammatory mediators in M1 phenotype microglia was downregulated. As opposed to this, M2 microglia were increased which was accompanied by upregulated expression of anti-inflammatory mediators along with telomerase reverse transcriptase or melatonin receptor 1(MT1). In parallel to this was decreased NG2 expression but increased expression of myelin and neurofilament proteins. Melatonin can improve hypomyelination which was confirmed by electron microscopy. In vitro in primary microglia stimulated by LPS, melatonin decreased the expression of proinflammatory mediators significantly; but it increased the expression of anti-inflammatory mediators. Additionally, the expression levels of p-JAK2 and p-STAT3 were significantly elevated in microglia after melatonin treatment. Remarkably, the effect of melatonin on LPS-treated microglia was blocked by melatonin receptor, JAK2, STAT3 and telomerase reverse transcriptase inhibitors, respectively. Taken together, it is concluded that melatonin can attenuate PWMD through shifting M1 microglia towards M2 via MT1/JAK2/STAT3/telomerase pathway. The results suggest a new therapeutic strategy whereby melatonin may be adopted to convert microglial polarization from M1 to M2 phenotype that would ultimately contribute to the attenuation of PWMD.

Conditional Loss of BAF (mSWI/SNF) Scaffolding Subunits Affects Specification and Proliferation of Oligodendrocyte Precursors in Developing Mouse Forebrain

Oligodendrocytes are responsible for axon myelination in the brain and spinal cord. Generation of oligodendrocytes entails highly regulated multistage neurodevelopmental events, including proliferation, differentiation and maturation. The chromatin remodeling BAF (mSWI/SNF) complex is a notable regulator of neural development. In our previous studies, we determined the indispensability of the BAF complex scaffolding subunits BAF155 and BAF170 for neurogenesis, whereas their role in gliogenesis is unknown. Here, we show that the expression of BAF155 and BAF170 is essential for the genesis of oligodendrocytes during brain development. We report that the ablation of BAF155 and BAF170 in the dorsal telencephalic (dTel) neural progenitors or in oligodendrocyte-producing progenitors in the ventral telencephalon (vTel) in double-conditional knockout (dcKO) mouse mutants, perturbed the process of oligodendrogenesis. Molecular marker and cell cycle analyses revealed impairment of oligodendrocyte precursor specification and proliferation, as well as overt depletion of oligodendrocytes pool in dcKO mutants. Our findings unveil a central role of BAF155 and BAF170 in oligodendrogenesis, and thus substantiate the involvement of the BAF complex in the production of oligodendrocytes in the forebrain.

Protective effects of edaravone on white matter pathology in a novel mouse model of Alzheimer's disease with chronic cerebral hypoperfusion

White matter lesions (WMLs) caused by cerebral chronic hypoperfusion (CCH) may contribute to the pathophysiology of Alzheimer's disease (AD). However, the underlying mechanisms and therapeutic approaches have yet to be totally identified. In the present study, we investigated a potential therapeutic effect of the free radical scavenger edaravone (EDA) on WMLs in our previously reported novel mouse model of AD (APP23) plus CCH with motor and cognitive deficits. Relative to AD with CCH mice at 12 months (M) of age, EDA strongly improved CCH-induced WMLs in the corpus callosum of APP23 mice at 12 M by improving the disruption of white matter integrity, enhancing the proliferation of oligodendrocyte progenitor cells, attenuating endothelium/astrocyte unit dysfunction, and reducing neuroinflammation and oxidative stress. The present study demonstrates that the long-term administration of EDA may provide a promising therapeutic approach for WMLs in AD plus CCH disease with cognitive deficits.

Scutellaria barbata flavonoids improve the composited Aβ-induced abnormal changes of glial cells in rats' brain

AIM

It has been reported that glial cells are involved in Alzheimer's disease (AD). According to our previous research, Scutellaria barbata flavonoids (SBFs) can protect the neuronal disorder and memory impairment for AD-like rats, while the effect of SBFs on the glial cells disorder in AD-like rats has been less well studied. The effects of SBFs on astrocytes(ASs), microglial cells (MGs) and oligodendrocytes (Ols), as well as heat shock proteins 70 (Hsp70) and apolipoprotein E (ApoE) were investigated in the present study.

METHODS

The successful model rats, screened by Morris water maze, were daily orally administrated with 35, 70 and 140 mg/kg SBFs for 36 d. The numbers of brain's astrocytes (ASs), microglial cells (MGs) and oligodendrocytes (Ols) were examined by immunohistochemistry. The cortical glial fibrillary acidic protein (GFAP), leukocyte common antigen (LCA) (CD45), Claudin 11 and heat shock proteins 70 (Hsp70) protein expression were assayed by Western blotting, and apolipoprotein E (ApoE) mRNA expression was analyzed by real-time quantitative polymerase chain reaction (qPCR).

RESULTS

Compared with the sham-operated group, the numbers of ASs and MGs in the brain were significantly increased in the model group (P<0.05, P<0.01), and accompanied with increases of GFAP, CD45 and Hsp70 protein and ApoE mRNA expression (P<0.05, P<0.01). Both Ols number and Claudin 11 protein expression decreased in the brain in the model group (P<0.05, P<0.01). However, the above abnormal changes induced by composited Aβ were differently reversed by treatment of SBFs at three doses of 35, 70 and 140 mg/kg (P<0.05, P<0.01).

CONCLUSIONS

SBFs can dramatically improve the abnormal changes of glial cells in rats' brain induced by composited Aβ, which may be a helpful treatment of neurodegenerative diseases.

White matter and neurological disorders

The central nervous system is simply divided into two distinct anatomical regions based on the color of tissues, i.e. the gray and white matter. The gray matter is composed of neuronal cell bodies, glial cells, dendrites, immune cells, and the vascular system, while the white matter is composed of concentrated myelinated axonal fibers extending from neuronal soma and glial cells, such as oligodendrocyte precursor cells (OPCs), oligodendrocytes, astrocytes, and microglia. As neuronal cell bodies are located in the gray matter, great attention has been focused mainly on the gray matter regarding the understanding of the functions of the brain throughout the neurophysiological areas, leading to a scenario in which the function of the white matter is relatively underestimated or has not received much attention. However, increasing evidence shows that the white matter plays highly significant and pivotal functions in the brain based on the fact that its abnormalities are associated with numerous neurological diseases. In this review, we will broadly discuss the pathways and functions of myelination, which is one of the main processes that modulate the functions of the white matter, as well as the manner in which its abnormalities are related to neurological disorders.

Dysfunction of the neurovascular unit in diabetes-related neurodegeneration

In current aging societies, diabetes mellitus and neurodegenerative diseases represented by Alzheimer's disease are highly prevalent among adults, especially the elderly all over the world. It is worth noting that a substantial body of evidence suggests diabetes contributes to accelerated neurodegenerative processes and the decline of cognition. Over the last few years, some studies have indicated neurovascular uncoupling and disrupted functional connectivity in the early stages of many neurodegenerative diseases, and the concept of the neurovascular unit (NVU) has been highlighted to understand the initiation and progression of neurodegenerative diseases recently. Considering that some components of the NVU are also demonstrated to have abnormal morphology and function under the condition of diabetes, we propose the hypothesis that diabetes may promote the onset and development of neurodegenerative diseases by impairing the integrity of the NVU, named Diabetes-NVU-Neurodegeneration Hypothesis. The existing body of literature supporting the hypothesis and elucidating the underlying mechanisms will be summarized in this review.

Perinatal exposure to nonylphenol delayed myelination in offspring cerebellum

As a stable environmental contaminant, nonylphenol (NP) has been shown to induce some neurological deficits in the cerebellum, although the underlying mechanism is still unknown. In the present study, we aimed to investigate the effects of perinatal exposure to NP on myelination, an important process essential for the intact cerebellar function, in the offspring cerebellum. Exposure to NP delayed the myelination in the offspring cerebellum during perinatal period. The myelination recovered in the cerebellum of offspring exposed to NP over time, and returned to normal in adulthood. In addition, perinatal exposure to NP reduced mature oligodendrocytes (myelin-forming glial cells) and increased astrocytes in the offspring cerebellum. BMP signaling is believed to negatively regulate oligodendrogliogenesis and myelination. In the present study, BMP4, p-Smad1/5, and ID4, key members of BMP signaling, were increased in the cerebellum of offspring exposed to NP. Taken together, these lines of evidence suggest that the activation of BMP signaling may underlie the decreased oligodendrogliogenesis and increased astrogliogenesis, and the consequent delay of myelination in the cerebellum of offspring perinatally exposed to NP.

Sleep in multiple sclerosis patients treated with interferon beta: an actigraphic study

OBJECTIVE

Sleep disorders in multiple sclerosis (MS) patients are common and complex. Some evidences suggest that interferon beta (IFN-β), a first line disease modifying therapy can be involved in the induction of sleep architecture changes. The aim of this study was to evaluate and characterize actigraphic patterns in MS patients treated with IFN-β.

METHODS

Ten relapsing remitting MS patients with low to mild disability (Expanded Disability Status Scale<2.5), aged 20-50y treated with IFN-β for more than 6 months were enrolled. Actigraphy was used to study sleep pattern. Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI). Ten sex-and age-matched healthy subjects served as controls. In patients, a comparison between drug free nights and nights following drug administration was made.

RESULTS

Patients had significantly higher PSQI (p = 0.006), sleep onset latency (p = 0.029), sleep efficiency percentage (p = 0.001) and number of wake episodes (p = 0,0001) values, when compared with controls. When comparing the actigraphic results acquired in the nights after treatment with those acquired in the free-drug nights, the only significant difference (p = 0.038) was detected for time in bed that was higher after IFN-β administration.

CONCLUSIONS

Our results, besides confirming the presence of alterations in sleep patterns in MS patients, suggest that IFN-β may contribute to promote alteration in sleep architecture. Actigraphy is a simple diagnostic tool, able to support an objective measure of sleep parameters. The relative simplicity of application and low costs may allow considering its use for an adequate screening of sleep disorders in MS patients.

High fat diet consumption results in mitochondrial dysfunction, oxidative stress, and oligodendrocyte loss in the central nervous system

Metabolic syndrome is a key risk factor and co-morbidity in multiple sclerosis (MS) and other neurological conditions, such that a better understanding of how a high fat diet contributes to oligodendrocyte loss and the capacity for myelin regeneration has the potential to highlight new treatment targets. Results demonstrate that modeling metabolic dysfunction in mice with chronic high fat diet (HFD) consumption promotes loss of oligodendrocyte progenitors across the brain and spinal cord. A number of transcriptomic and metabolomic changes in ER stress, mitochondrial dysfunction, and oxidative stress pathways in HFD-fed mouse spinal cords were also identified. Moreover, deficits in TCA cycle intermediates and mitochondrial respiration were observed in the chronic HFD spinal cord tissue. Oligodendrocytes are known to be particularly vulnerable to oxidative damage, and we observed increased markers of oxidative stress in both the brain and spinal cord of HFD-fed mice. We additionally identified that increased apoptotic cell death signaling is underway in oligodendrocytes from mice chronically fed a HFD. When cultured under high saturated fat conditions, oligodendrocytes decreased both mitochondrial function and differentiation. Overall, our findings show that HFD-related changes in metabolic regulators, decreased mitochondrial function, and oxidative stress contribute to a loss of myelinating cells. These studies identify HFD consumption as a key modifiable lifestyle factor for improved myelin integrity in the adult central nervous system and in addition new tractable metabolic targets for myelin protection and repair strategies.

A Role of Microtubules in Oligodendrocyte Differentiation

Oligodendrocytes are specialized cells that myelinate axons in the central nervous system. Defects in oligodendrocyte function and failure to form or maintain myelin sheaths can cause a number of neurological disorders. Oligodendrocytes are differentiated from oligodendrocyte progenitor cells (OPCs), which extend several processes that contact, elaborate, and eventually wrap axonal segments to form multilayered myelin sheaths. These processes require extensive changes in the cytoarchitecture and must be regulated by reorganization of the cytoskeleton. Here, we established a simple protocol to isolate and differentiate mouse OPCs, and by using this method, we investigated a role of microtubules (MTs) in oligodendrocyte differentiation. Oligodendrocytes developed a complex network of MTs during differentiation, and treatment of differentiating oligodendrocytes with nanomolar concentrations of MT-targeting agents (MTAs) markedly affected oligodendrocyte survival and differentiation. We found that acute exposure to vincristine and nocodazole at early stages of oligodendrocyte differentiation markedly increased MT arborization and enhanced differentiation, whereas taxol and epothilone B treatment produced opposing outcomes. Furthermore, treatment of myelinating co-cultures of oligodendrocytes and neurons with nanomolar concentrations of MTAs at late stages of oligodendrocyte differentiation induced dysmyelination. Together, these results suggest that MTs play an important role in the survival, differentiation, and myelination of oligodendrocytes.

FAM19A5 Expression During Embryogenesis and in the Adult Traumatic Brain of FAM19A5-LacZ Knock-in Mice

FAM19A5 is a secretory protein that is predominantly expressed in the brain. Although the FAM19A5 gene has been found to be associated with neurological and/or psychiatric diseases, only limited information is available on its function in the brain. Using FAM19A5-LacZ knock-in mice, we determined the expression pattern of FAM19A5 in developing and adult brains and identified cell types that express FAM19A5 in naïve and traumatic brain injury (TBI)–induced brains. According to X-gal staining results, FAM19A5 is expressed in the ventricular zone and ganglionic eminence at a very early stage of brain development, suggesting its functions are related to the generation of neural stem cells and oligodendrocyte precursor cells (OPCs). In the later stages of developing embryos and in adult mice, FAM19A5 expression expanded broadly to particular regions of the brain, including layers 2/3 and 5 of the cortex, cornu amonis (CA) region of the hippocampus, and the corpus callosum. X-gal staining combined with immunostaining for a variety of cell-type markers revealed that FAM19A5 is expressed in many different cell types, including neurons, OPCs, astrocytes, and microglia; however, only some populations of these cell types produce FAM19A5. In a subpopulation of neuronal cells, TBI led to increased X-gal staining that extended to the nucleus, marked by slightly condensed content and increased heterochromatin formation along the nuclear border. Similarly, nuclear extension of X-gal staining occurred in a subpopulation of OPCs in the corpus callosum of the TBI-induced brain. Together, these results suggest that FAM19A5 plays a role in nervous system development from an early stage and increases its expression in response to pathological conditions in subsets of neurons and OPCs of the adult brain.

Potential Applications of Remote Limb Ischemic Conditioning for Chronic Cerebral Circulation Insufficiency

Chronic cerebral circulation insufficiency (CCCI) refers to a chronic decrease in cerebral blood perfusion, which may lead to cognitive impairment, psychiatric disorders such as depression, and acute ischemic stroke. Remote limb ischemic conditioning (RLIC), in which the limbs are subjected to a series of transient ischemic attacks, can activate multiple endogenous protective mechanisms to attenuate fatal ischemic injury to distant organs due to acute ischemia, such as ischemic stroke. Recent studies have also reported that RLIC can alleviate dysfunction in distant organs caused by chronic, non-fatal reductions in blood supply (e.g., CCCI). Indeed, research has indicated that RLIC may exert neuroprotective effects against CCCI through a variety of potential mechanisms, including attenuated glutamate excitotoxicity, improved endothelial function, increased cerebral blood flow, regulation of autophagy and immune responses, suppression of apoptosis, the production of protective humoral factors, and attenuated accumulation of amyloid-β. Verification of these findings is necessary to improve prognosis and reduce the incidence of acute ischemic stroke/cognitive impairment in patients with CCCI.

Sleep quality can influence the outcome of patients with multiple sclerosis

OBJECTIVE

Sleep plays a role in some oligodendrocyte processes, including myelination. This study aimed to analyze the possible correlations between sleep quality and Multiple Sclerosis (MS) course.

METHODS

Forty patients with Relapsing-Remitting MS were admitted. Based on the score obtained by the Pittsburgh Sleep Quality Index (PSQI), they were divided into good sleepers (<5) and bad sleepers (≥5). A set of data was collected retrospectively for each patient to investigate whether PSQI scores correlated with EDSS score changes, the number and the duration of each relapse and the cumulative day-number of MS reactivations over a three-year period.

RESULTS

In a multivariate model, a PSQI score ≥5 independently and significantly correlated with an increase in number and duration of relapses (p = 0.000) and number of days of MS activity (p = 0.000) during the three-year retrospective observation period.

CONCLUSIONS

The results of this study show that the course of MS may be influenced by sleep quality. Assessment of sleep quality could be used to obtain reliable prognostic information in patients with relapsing-remitting MS. Further investigations are necessary to evaluate whether the correction of sleep disorders may be effective in improving the prognosis of MS patients.