Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at site...Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at sites of injury greatly impedes nerve regeneration,making the clearance of debris within these microenvironments crucial for effective post-spinal cord injury repair.In this review,we comprehensively outline the mechanisms that promote the clearance of myelin debris and myelin metabolism and summarize their roles in spinal cord injury.First,we describe the composition and characteristics of myelin debris and explain its effects on the injury site.Next,we introduce the phagocytic cells involved in myelin debris clearance,including professional phagocytes(macrophages and microglia)and non-professional phagocytes(astrocytes and microvascular endothelial cells),as well as other cells that are also proposed to participate in phagocytosis.Finally,we focus on the pathways and associated targets that enhance myelin debris clearance by phagocytes and promote lipid metabolism following spinal cord injury.Our analysis indicates that myelin debris phagocytosis is not limited to monocyte-derived macrophages,but also involves microglia,astrocytes,and microvascular endothelial cells.By modulating the expression of genes related to phagocytosis and lipid metabolism,it is possible to modulate lipid metabolism disorders and influence inflammatory phenotypes,ultimately affecting the recovery of motor function following spinal cord injury.Additionally,therapies such as targeted mitochondrial transplantation in phagocytic cells,exosome therapy,and repeated trans-spinal magnetic stimulation can effectively enhance the removal of myelin debris,presenting promising potential for future applications.展开更多
The rapidly aging population directly contributes to the increasing cases of neurological disorders.Due to the chronic progressive nature of neurodegeneration,numerous neurological conditions are considered“multifact...The rapidly aging population directly contributes to the increasing cases of neurological disorders.Due to the chronic progressive nature of neurodegeneration,numerous neurological conditions are considered“multifactorial”with systemic metabolic alterations.Even so,treatments for neurological disorders have remained unchanged for the past decades.Recently,metabolic drugs such as metformin and glucagon-like peptide 1 agonists have demonstrated promising health outcomes for neurodegeneration.展开更多
Microglia are the macrophages that populate the brain parenchyma.Research in the past decades has identified them as both essential guardians of the brain and significant contributors to various neurological diseases....Microglia are the macrophages that populate the brain parenchyma.Research in the past decades has identified them as both essential guardians of the brain and significant contributors to various neurological diseases.A highly versatile cell type,microglia have been shown to fulfill a multitude of critical roles in the central nervous system,including facilitating neurogenesis and myelination,pruning synapses,removing debris and waste,modulating neuronal activity,supporting the blood-brain barrier,repairing tissue damage,and surveilling against microbial invasions under physiological conditions(Prinz et al.,2021;Paolicelli et al.,2022).展开更多
Chronic cerebral hypoperfusion can lead to neuronal necrosis,trigger inflammatory responses,promote white matter damage,and ultimately result in cognitive impairment.Consequently,chronic cerebral hypoperfusion is an i...Chronic cerebral hypoperfusion can lead to neuronal necrosis,trigger inflammatory responses,promote white matter damage,and ultimately result in cognitive impairment.Consequently,chronic cerebral hypoperfusion is an important factor influencing the onset and progression of vascular dementia.The myelin sheath is a critical component of white matter,and damage and repair of the white matter are closely linked to myelin sheath integrity.This article reviews the role of microglia in vascular dementia,focusing on their effects on myelin sheaths and the potential therapeutic implications.The findings suggest that ischemia and hypoxia cause disruption of the blood-brain barrier and activate microglia,which may worsen blood-brain barrier damage through the release of matrix-degrading enzymes.Microglia-mediated metabolic reprogramming is recognized as an important driver of inflammation.Damage to the blood-brain barrier and subsequent inflammation can lead to myelin injury and accelerate the progression of vascular dementia.Early activation of microglia is a protective response that contributes to the maintenance of blood-brain barrier integrity through sensing,debris-clearing,and defensive mechanisms.However,prolonged activation can trigger a shift in microglia toward the pro-inflammatory M1 phenotype,resulting in myelin damage and cognitive impairment.Triggering receptor expressed on myeloid cells 2 and triggering receptor expressed on myeloid cells 1 have been identified as potential biomarkers for vascular dementia,as both are closely linked to cognitive decline.Although effective clinical treatments for myelin damage in the central nervous system are currently lacking,researchers are actively working to develop targeted therapies.Several drugs,including nimodipine,dopaminergic agents,simvastatin,biotin,and quetiapine,have been evaluated for clinical use in treating microglial and myelin damage.Future research will face challenges in developing targeted therapeutic strategies for vascular dementia,requiring further investigation into the timing,duration,and specific mechanisms of microglial activation,as well as the exploration of new drug combinations and additional therapeutic targets.展开更多
Germinal matrix hemorrhage in preterm neonates often leads to white matter injury,contributing to long-term neurodevelopmental impairments.As resident brain immune cells,microglia play a complex role in injury respons...Germinal matrix hemorrhage in preterm neonates often leads to white matter injury,contributing to long-term neurodevelopmental impairments.As resident brain immune cells,microglia play a complex role in injury response,including inflammation and repair.Although colony-stimulating factor 1 receptor inhibitors such as PLX5622 enable the selective depletion of microglia,their therapeutic potential in neonatal germinal matrix hemorrhage remains underexplored.Here,we used a collagenase-induced germinal matrix hemorrhage model in postnatal day 5 mice,and intraperitoneally administered PLX562272 hours post-germinal matrix hemorrhage to achieve targeted,temporary microglial depletion during the peak injury response.We then assessed the effects of this delayed intervention on oligodendrocyte lineage cell maturation,white matter integrity,and neurobehavioral outcomes.Additionally,RNA sequencing data from a germinal matrix hemorrhage rat model were analyzed using weighted gene co-expression network analysis to identify the critical phases for interventions.RNA sequencing data revealed a critical period in which key synaptic functions declined while immune responses intensified post-germinal matrix hemorrhage,thus pinpointing the critical response phases for potential interventions.Delayed PLX5622 treatment effectively depleted activated microglia,protecting against white matter injury and enhancing oligodendrocyte lineage cell maturation and myelination in subcortical white matter regions.Moreover,magnetic resonance imaging analysis revealed reduced brain lesion volumes in treated mice.Behaviorally,PLX5622-treated mice exhibited significant improvements in motor coordination and reduced hyperactivity compared with vehicle-treated germinal matrix hemorrhage model mice.These findings suggest that,when timed to avoid interference with initial oligodendrocyte lineage cell proliferation,targeted microglial depletion with PLX5622 significantly mitigates white matter damage and improves neurobehavioral outcomes in neonatal germinal matrix hemorrhage.The present study highlights the therapeutic potential of selectively modulating microglial reactivity to support neurodevelopment in preterm infants with brain injury.展开更多
Myelination,the continuous ensheathment of neuronal axons,is a lifelong process in the nervous system that is essential for the precise,temporospatial conduction of action potentials between neurons.Myelin also provid...Myelination,the continuous ensheathment of neuronal axons,is a lifelong process in the nervous system that is essential for the precise,temporospatial conduction of action potentials between neurons.Myelin also provides intercellular metabolic support to axons.Even minor disruptions in the integrity of myelin can impair neural performance and increase susceptibility to neurological diseases.In fact,myelin degeneration is a well-known neuropathological condition that is associated with normal aging and several neurodegenerative diseases,including multiple sclerosis and Alzheimer’s disease.In the central nervous system,compact myelin sheaths are formed by fully mature oligodendrocytes.However,the entire oligodendrocyte lineage is susceptible to changes in the biological microenvironment and other risk factors that arise as the brain ages.In addition to their well-known role in action potential propagation,oligodendrocytes also provide intercellular metabolic support to axons by transferring energy metabolites and delivering exosomes.Therefore,myelin degeneration in the aging central nervous system is a significant contributor to the development of neurodegenerative diseases.Interventions that mitigate age-related myelin degeneration can improve neurological function in aging individuals.In this review,we investigate the changes in myelin that are associated with aging and their underlying mechanisms.We also discuss recent advances in understanding how myelin degeneration in the aging brain contributes to neurodegenerative diseases and explore the factors that can prevent,slow down,or even reverse age-related myelin degeneration.Future research will enhance our understanding of how reducing age-related myelin degeneration can be used as a therapeutic target for delaying or preventing neurodegenerative diseases.展开更多
Myelin,made by oligodendrocytes(OLs)in the central nervous system(CNS),is essential for neural transmission.In particular,myelin facilitates communication across the long connections between different brain regions th...Myelin,made by oligodendrocytes(OLs)in the central nervous system(CNS),is essential for neural transmission.In particular,myelin facilitates communication across the long connections between different brain regions that form the white matter.Myelinated segments also provide metabolic intermediates to axons,supporting their demanding energetic needs.Genetic disorders that disrupt myelin formation result in progressive neurologic degeneration.展开更多
Adult-born oligodendrocytes are continuously produced in the brains of rodents.The functional role of these cells has been linked to the motor-related activities of healthy animals and is vital for acquiring new motor...Adult-born oligodendrocytes are continuously produced in the brains of rodents.The functional role of these cells has been linked to the motor-related activities of healthy animals and is vital for acquiring new motor skills.However,the relationship between these cells and the control of motor-related activities has not been investigated in pathological conditions.Therefore,the aim of this study is to investigate the role of oligodendrocytes in depression-related motor deficits and the effects of training.Psychomotor retardation is a key symptom of depression.Consistent with the impairments observed in rodent motor performance,the proliferation and activation of adult-born oligodendrocytes are altered in a corticosterone-induced stress paradigm.Therapeutic rotarod training can alleviate these symptoms by reversing the aforementioned changes.Notably,these alterations are particularly pronounced in layer I of the motor cortex.Thus,this study provides evidence of the potential functional involvement of adult-born oligodendrocytes in the motor impairments observed in the depressed animals.Additionally,it offers preliminary results for further investigation into layer I of the motor cortex in relation to these pathological conditions.展开更多
Neurodevelopmental processes represent a finely tuned interplay between genetic and environmental factors,shaping the dynamic landscape of the developing brain.A major component of the developing brain that enables th...Neurodevelopmental processes represent a finely tuned interplay between genetic and environmental factors,shaping the dynamic landscape of the developing brain.A major component of the developing brain that enables this dynamic is the white matter(WM),known to be affected in neurodevelopmental disorders(NDDs)(Rokach et al.,2024).WM formation is mediated by myelination,a multifactorial process driven by neuro-glia interactions dependent on proper neuronal functionality(Simons and Trajkovic,2006).Another key aspect of neurodevelopmental abnormalities involves neuronal dynamics and function,with recent advances significantly enhancing our understanding of both neuronal and glial mitochondrial function(Devine and Kittler,2018;Rojas-Charry et al.,2021).Energy homeostasis in neurons,attributed largely to mitochondrial function,is critical for proper functionality and interactions with oligodendrocytes(OLs),the cells forming myelin in the brain’s WM.We herein discuss the interplay between these processes and speculate on potential dysfunction in NDDs.展开更多
Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a...Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a lipid-rich myelin sheath,which enables the saltatory conduction of action potentials.During development,oligodendrocyte progenitor cells(OPCs)emerge from neural stem cells in the ventricular zone.They then proliferate,increase their number,and migrate to their final destination where they encounter unmyelinated neuronal axons and differentiate in a stepwise fashion into myelinating oligodendrocytes(mOLs)under the influence of environmental stimuli.展开更多
OBJECTIVE: To investigate the growth and development of myelin of sheath fetal brain. METHODS: Forty-four cases of pregnant women were imaged with magnetic resonance (MR) at 0.35 T (tesla). The signal changes of the m...OBJECTIVE: To investigate the growth and development of myelin of sheath fetal brain. METHODS: Forty-four cases of pregnant women were imaged with magnetic resonance (MR) at 0.35 T (tesla). The signal changes of the main structures of fetal brain were analysed. RESULTS: The signal intensity of cerebral (except basal ganglia) and cerebellar matter was hypo-signal on the T1WI (T1 weighted spin-echo image), iso-signal of the PDWI (Proton density weighted image) and hyper-signal on the T2WI (T2 weighted spin-echo image). As to the brain stem and basal ganglia, their signal intensities showed difference in different gestational weeks on T1WI. The intensities were of slight hypo-signal before and iso-signal after the 29th week. However, their signal intensities on PDWI and T2WI were the same as those of the cerebral and cerebellar matter. CONCLUSIONS: There was no myelinization of fetal cerebral (except basal ganglia) and cerebellar matter during pregnant period. The myelin sheath was formed in the brain stem and basal ganglia after 29 gestational weeks. The process of myelinization began from brain stem to basal ganglia.展开更多
Cholesterol is an important component of plasma membranes and participates in many basic life functions,such as the maintenance of cell membrane stability,the synthesis of steroid hormones,and myelination.Cholesterol ...Cholesterol is an important component of plasma membranes and participates in many basic life functions,such as the maintenance of cell membrane stability,the synthesis of steroid hormones,and myelination.Cholesterol plays a key role in the establishment and maintenance of the central nervous system.The brain contains 20%of the whole body’s cholesterol,80%of which is located within myelin.A huge number of processes(e.g.,the sterol regulatory element-binding protein pathway and liver X receptor pathway)participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis,intracellular transport,and efflux.Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences.Therefore,we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases.Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype,with high mortality and morbidity.Historical cholesterol levels are associated with the risk of intracerebral hemorrhage.Moreover,secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation,such as neuroinflammation,demyelination,and multiple types of programmed cell death.Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage.In this paper,we review normal cholesterol metabolism in the central nervous system,the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage,and the links between cholesterol metabolism and cell death.We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.展开更多
Differentiation of oligodendrocyte progenitor cells into mature myelin-forming oligodendrocytes contributes to remyelination.Failure of remyelination due to oligodendrocyte progenitor cell death can result in severe n...Differentiation of oligodendrocyte progenitor cells into mature myelin-forming oligodendrocytes contributes to remyelination.Failure of remyelination due to oligodendrocyte progenitor cell death can result in severe nerve damage.Ferroptosis is an iron-dependent form of regulated cell death caused by membrane rupture induced by lipid peroxidation,and plays an important role in the pathological process of ischemic stroke.However,there are few studies on oligodendrocyte progenitor cell ferroptosis.We analyzed transcriptome sequencing data from GEO databases and identified a role of ferroptosis in oligodendrocyte progenitor cell death and myelin injury after cerebral ischemia.Bioinformatics analysis suggested that perilipin-2(PLIN2)was involved in oligodendrocyte progenitor cell ferroptosis.PLIN2 is a lipid storage protein and a marker of hypoxia-sensitive lipid droplet accumulation.For further investigation,we established a mouse model of cerebral ischemia/reperfusion.We found significant myelin damage after cerebral ischemia,as well as oligodendrocyte progenitor cell death and increased lipid peroxidation levels around the infarct area.The ferroptosis inhibitor,ferrostatin-1,rescued oligodendrocyte progenitor cell death and subsequent myelin injury.We also found increased PLIN2 levels in the peri-infarct area that co-localized with oligodendrocyte progenitor cells.Plin2 knockdown rescued demyelination and improved neurological deficits.Our findings suggest that targeting PLIN2 to regulate oligodendrocyte progenitor cell ferroptosis may be a potential therapeutic strategy for rescuing myelin damage after cerebral ischemia.展开更多
Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central ne...Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central nervous system.Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B,Menkes disease and Wilson’s disease,respectively,and also in multifactorial neurological disorders such as Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and multiple sclerosis.This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology,reports about unbalances in copper levels and/or distribution under disease,describes relevant animal models for human disorders where copper metabolism genes are dysregulated,and discusses relevant therapeutic approaches modulating copper availability.Overall,alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.展开更多
Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulat...Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration.However,recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration,particularly in the context of traumatic injuries.Consequently,autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration.Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths,thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation.These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration.A range of autophagyinducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries.This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration,summarizing the potential drugs and interventions that can be harnessed to promote this process.We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.展开更多
BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic im...BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic implications and longterm management strategies.Vascular and metabolic factors are being thought to play a role in such autoimmune neuro-inflammatory disorders,apart from the obvious immune mediated damage.With the advent of optical coherence tomography angiography(OCTA),it is easy to pick up on these subclinical macular microvascular and structural changes.AIM To study the macular microvascular and structural changes on OCTA in atypical optic neuritis.METHODS This observational cross-sectional study involved 8 NMOSD and 17 MOGAD patients,diagnosed serologically,as well as 10 healthy controls.Macular vascular density(MVD)and ganglion cell+inner plexiform layer thickness(GCIPL)were studied using OCTA.RESULTS There was a significant reduction in MVD in NMOSD and MOGAD affected as well as unaffected eyes when compared with healthy controls.NMOSD and MOGAD affected eyes had significant GCIPL thinning compared with healthy controls.NMOSD unaffected eyes did not show significant GCIPL thinning compared to healthy controls in contrast to MOGAD unaffected eyes.On comparing NMOSD with MOGAD,there was no significant difference in terms of MVD or GCIPL in the affected or unaffected eyes.CONCLUSION Although significant microvascular and structural changes are present on OCTA between atypical optic neuritis and normal patients,they could not help in differentiating between NMOSD and MOGAD cases.展开更多
Decades of research asserted that the oligodendroglial lineage comprises two cell types:oligodendrocyte precursor cells and oligodendrocytes.However,recent studies employing single-cell RNA sequencing techniques have ...Decades of research asserted that the oligodendroglial lineage comprises two cell types:oligodendrocyte precursor cells and oligodendrocytes.However,recent studies employing single-cell RNA sequencing techniques have uncovered novel cell states,prompting a revision of the existing terminology.Going forward,the oligodendroglial lineage should be delineated into five distinct cell states:oligodendrocyte precursor cells,committed oligodendrocyte precursor cells,newly formed oligodendrocytes,myelin-forming oligodendrocytes,and mature oligodendrocytes.This new classification system enables a deeper understanding of the oligodendroglia in both physiological and pathological contexts.Adopting this uniform terminology will facilitate comparison and integration of data across studies.This,including the consolidation of findings from various demyelinating models,is essential to better understand the pathogenesis of demyelinating diseases.Additionally,comparing injury models across species with varying regenerative capacities can provide insights that may lead to new therapeutic strategies to overcome remyelination failure.Thus,by standardizing terminology and synthesizing data from diverse studies across different animal models,we can enhance our understanding of myelin pathology in central nervous system disorders such as multiple sclerosis,Alzheimer's disease,and amyotrophic lateral sclerosis,all of which involve oligodendroglial and myelin dysfunction.展开更多
Myelin is the protective sheath surrounding nerve fibers, and its damage(demyelination) occurs in many central nervous system(CNS) diseases, including multiple sclerosis(MS), traumatic injury, neurodegenerative diseas...Myelin is the protective sheath surrounding nerve fibers, and its damage(demyelination) occurs in many central nervous system(CNS) diseases, including multiple sclerosis(MS), traumatic injury, neurodegenerative diseases such as Alzheimer's disease, and mental disorders such as schizophrenia(Barateiro et al., 2016). Repair of damaged myelin sheaths(remyelination) often fails in MS, leading to neuronal loss and irreversible functional deficits.展开更多
Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripher...Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.展开更多
Demyelination and remyelination have been major focal points in the study of peripheral nerve regeneration following peripheral nerve injury.Notably,the gene regulatory network of regenerated myelin differs from that ...Demyelination and remyelination have been major focal points in the study of peripheral nerve regeneration following peripheral nerve injury.Notably,the gene regulatory network of regenerated myelin differs from that of native myelin.Silencing of enhancer of zeste homolog 2(EZH2)hinders the differentiation,maturation,and myelination of Schwann cells in vitro.To further determine the role of EZH2 in myelination and recovery post-peripheral nerve injury,conditional knockout mice lacking Ezh2 in Schwann cells(Ezh2^(fl/fl);Dhh-Cre and Ezh2^(fl/fl);Mpz-Cre)were generated.Our results show that a significant proportion of axons in the sciatic nerve of Ezh2-depleted mice remain unmyelinated.This highlights the crucial role of Ezh2 in initiating Schwann cell myelination.Furthermore,we observed that 21 days after inducing a sciatic nerve crush injury in these mice,most axons had remyelinated at the injury site in the control nerve,while Ezh2^(fl/fl);Mpz-Cre mice had significantly fewer remyelinated axons compared with their wild-type littermates.This suggests that the absence of Ezh2 in Schwann cells impairs myelin formation and remyelination.In conclusion,EZH2 has emerged as a pivotal regulatory factor in the process of demyelination and myelin regeneration following peripheral nerve injury.Modulating EZH2 activity during these processes may offer a promising therapeutic target for the treatment of peripheral nerve injuries.展开更多
基金supported by the National Natural Science Foundation of China,Nos.82271411(to RG),51803072(to WL)the International Cooperative Project of Talent Cultivation“Xinghai Project”at the China-Japan Union Hospital of Jilin University,No.XHLH202404(to WL)+1 种基金the Science and Technology Development Plan of Jilin Province,No.YDZJ202201ZYTS038(to WL)Jilin Provincial Finance Program,No.2022SCZ10(to WL)。
文摘Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at sites of injury greatly impedes nerve regeneration,making the clearance of debris within these microenvironments crucial for effective post-spinal cord injury repair.In this review,we comprehensively outline the mechanisms that promote the clearance of myelin debris and myelin metabolism and summarize their roles in spinal cord injury.First,we describe the composition and characteristics of myelin debris and explain its effects on the injury site.Next,we introduce the phagocytic cells involved in myelin debris clearance,including professional phagocytes(macrophages and microglia)and non-professional phagocytes(astrocytes and microvascular endothelial cells),as well as other cells that are also proposed to participate in phagocytosis.Finally,we focus on the pathways and associated targets that enhance myelin debris clearance by phagocytes and promote lipid metabolism following spinal cord injury.Our analysis indicates that myelin debris phagocytosis is not limited to monocyte-derived macrophages,but also involves microglia,astrocytes,and microvascular endothelial cells.By modulating the expression of genes related to phagocytosis and lipid metabolism,it is possible to modulate lipid metabolism disorders and influence inflammatory phenotypes,ultimately affecting the recovery of motor function following spinal cord injury.Additionally,therapies such as targeted mitochondrial transplantation in phagocytic cells,exosome therapy,and repeated trans-spinal magnetic stimulation can effectively enhance the removal of myelin debris,presenting promising potential for future applications.
文摘The rapidly aging population directly contributes to the increasing cases of neurological disorders.Due to the chronic progressive nature of neurodegeneration,numerous neurological conditions are considered“multifactorial”with systemic metabolic alterations.Even so,treatments for neurological disorders have remained unchanged for the past decades.Recently,metabolic drugs such as metformin and glucagon-like peptide 1 agonists have demonstrated promising health outcomes for neurodegeneration.
基金funded by NIH grants HL154720-03S1, AG057587, AG074283, DK122708-03S1, BrightFocus ADR A20183775Brown Foundation 2020 Healthy Aging Initiative (to WC)
文摘Microglia are the macrophages that populate the brain parenchyma.Research in the past decades has identified them as both essential guardians of the brain and significant contributors to various neurological diseases.A highly versatile cell type,microglia have been shown to fulfill a multitude of critical roles in the central nervous system,including facilitating neurogenesis and myelination,pruning synapses,removing debris and waste,modulating neuronal activity,supporting the blood-brain barrier,repairing tissue damage,and surveilling against microbial invasions under physiological conditions(Prinz et al.,2021;Paolicelli et al.,2022).
基金supported by the Natural Science Foundation of Beijing,No.7232279(to XW)the National Natural Science Foundation of China,No.U21A20400(to QW)Key Project of Beijing University of Chinese Medicine,Nos.2022-JYB-JBZR-004(to XW),2024-JYB-JBZD-043(to CL).
文摘Chronic cerebral hypoperfusion can lead to neuronal necrosis,trigger inflammatory responses,promote white matter damage,and ultimately result in cognitive impairment.Consequently,chronic cerebral hypoperfusion is an important factor influencing the onset and progression of vascular dementia.The myelin sheath is a critical component of white matter,and damage and repair of the white matter are closely linked to myelin sheath integrity.This article reviews the role of microglia in vascular dementia,focusing on their effects on myelin sheaths and the potential therapeutic implications.The findings suggest that ischemia and hypoxia cause disruption of the blood-brain barrier and activate microglia,which may worsen blood-brain barrier damage through the release of matrix-degrading enzymes.Microglia-mediated metabolic reprogramming is recognized as an important driver of inflammation.Damage to the blood-brain barrier and subsequent inflammation can lead to myelin injury and accelerate the progression of vascular dementia.Early activation of microglia is a protective response that contributes to the maintenance of blood-brain barrier integrity through sensing,debris-clearing,and defensive mechanisms.However,prolonged activation can trigger a shift in microglia toward the pro-inflammatory M1 phenotype,resulting in myelin damage and cognitive impairment.Triggering receptor expressed on myeloid cells 2 and triggering receptor expressed on myeloid cells 1 have been identified as potential biomarkers for vascular dementia,as both are closely linked to cognitive decline.Although effective clinical treatments for myelin damage in the central nervous system are currently lacking,researchers are actively working to develop targeted therapies.Several drugs,including nimodipine,dopaminergic agents,simvastatin,biotin,and quetiapine,have been evaluated for clinical use in treating microglial and myelin damage.Future research will face challenges in developing targeted therapeutic strategies for vascular dementia,requiring further investigation into the timing,duration,and specific mechanisms of microglial activation,as well as the exploration of new drug combinations and additional therapeutic targets.
基金supported by the National Key Research and Development Program of China,No.2022YFC2704801(to CZhu)the National Natural Science Foundation of China,Nos.U21A20347(to CZhu),82203969(to YX),82371472(to XZ)+3 种基金Health Commission of Henan Province,Nos.SBGJ202303039(to XZ),SBGJ202301009(to CZhu),YQRC2024018(to XZ),YQRC2024019(to YX)Henan Science and Technology Department,Nos.242102311054(to XZ),241111521300(to CZhu),GZS2023003(to XW)Swedish Research Council,Nos.2022-01019(to CZhu),2021-01950(to XW)Swedish Governmental Grants to Scientists Working in Healthcare,Nos.ALFGBG-1005209(to CZhu),ALFBG-1005257(to XW),ALFGBG-965197(to CZhu).
文摘Germinal matrix hemorrhage in preterm neonates often leads to white matter injury,contributing to long-term neurodevelopmental impairments.As resident brain immune cells,microglia play a complex role in injury response,including inflammation and repair.Although colony-stimulating factor 1 receptor inhibitors such as PLX5622 enable the selective depletion of microglia,their therapeutic potential in neonatal germinal matrix hemorrhage remains underexplored.Here,we used a collagenase-induced germinal matrix hemorrhage model in postnatal day 5 mice,and intraperitoneally administered PLX562272 hours post-germinal matrix hemorrhage to achieve targeted,temporary microglial depletion during the peak injury response.We then assessed the effects of this delayed intervention on oligodendrocyte lineage cell maturation,white matter integrity,and neurobehavioral outcomes.Additionally,RNA sequencing data from a germinal matrix hemorrhage rat model were analyzed using weighted gene co-expression network analysis to identify the critical phases for interventions.RNA sequencing data revealed a critical period in which key synaptic functions declined while immune responses intensified post-germinal matrix hemorrhage,thus pinpointing the critical response phases for potential interventions.Delayed PLX5622 treatment effectively depleted activated microglia,protecting against white matter injury and enhancing oligodendrocyte lineage cell maturation and myelination in subcortical white matter regions.Moreover,magnetic resonance imaging analysis revealed reduced brain lesion volumes in treated mice.Behaviorally,PLX5622-treated mice exhibited significant improvements in motor coordination and reduced hyperactivity compared with vehicle-treated germinal matrix hemorrhage model mice.These findings suggest that,when timed to avoid interference with initial oligodendrocyte lineage cell proliferation,targeted microglial depletion with PLX5622 significantly mitigates white matter damage and improves neurobehavioral outcomes in neonatal germinal matrix hemorrhage.The present study highlights the therapeutic potential of selectively modulating microglial reactivity to support neurodevelopment in preterm infants with brain injury.
基金supported by grants from Guangdong Basic and Applied Basic Research Foundation,No.2021A1515110801(to SW)the National Natural Science Foundation of China,No.82301511(to SW)+1 种基金“Double First-Class”Construction Project of NPU,Nos.0515023GH0202320(to JC),0515023SH0201320(to JC)973 Program,No.2011CB504100(to JC).
文摘Myelination,the continuous ensheathment of neuronal axons,is a lifelong process in the nervous system that is essential for the precise,temporospatial conduction of action potentials between neurons.Myelin also provides intercellular metabolic support to axons.Even minor disruptions in the integrity of myelin can impair neural performance and increase susceptibility to neurological diseases.In fact,myelin degeneration is a well-known neuropathological condition that is associated with normal aging and several neurodegenerative diseases,including multiple sclerosis and Alzheimer’s disease.In the central nervous system,compact myelin sheaths are formed by fully mature oligodendrocytes.However,the entire oligodendrocyte lineage is susceptible to changes in the biological microenvironment and other risk factors that arise as the brain ages.In addition to their well-known role in action potential propagation,oligodendrocytes also provide intercellular metabolic support to axons by transferring energy metabolites and delivering exosomes.Therefore,myelin degeneration in the aging central nervous system is a significant contributor to the development of neurodegenerative diseases.Interventions that mitigate age-related myelin degeneration can improve neurological function in aging individuals.In this review,we investigate the changes in myelin that are associated with aging and their underlying mechanisms.We also discuss recent advances in understanding how myelin degeneration in the aging brain contributes to neurodegenerative diseases and explore the factors that can prevent,slow down,or even reverse age-related myelin degeneration.Future research will enhance our understanding of how reducing age-related myelin degeneration can be used as a therapeutic target for delaying or preventing neurodegenerative diseases.
基金support held by JPA,Collaborative Network Award BRAVEinMS,Grant/Award Number:PA-1604-08492(MG)from the Multiple Sclerosis Society of Canada,Grant/Award Number:1038154(to TEK).
文摘Myelin,made by oligodendrocytes(OLs)in the central nervous system(CNS),is essential for neural transmission.In particular,myelin facilitates communication across the long connections between different brain regions that form the white matter.Myelinated segments also provide metabolic intermediates to axons,supporting their demanding energetic needs.Genetic disorders that disrupt myelin formation result in progressive neurologic degeneration.
基金supported by Hong Kong Health and Medical Research Fund,No.02133206(to KFS).
文摘Adult-born oligodendrocytes are continuously produced in the brains of rodents.The functional role of these cells has been linked to the motor-related activities of healthy animals and is vital for acquiring new motor skills.However,the relationship between these cells and the control of motor-related activities has not been investigated in pathological conditions.Therefore,the aim of this study is to investigate the role of oligodendrocytes in depression-related motor deficits and the effects of training.Psychomotor retardation is a key symptom of depression.Consistent with the impairments observed in rodent motor performance,the proliferation and activation of adult-born oligodendrocytes are altered in a corticosterone-induced stress paradigm.Therapeutic rotarod training can alleviate these symptoms by reversing the aforementioned changes.Notably,these alterations are particularly pronounced in layer I of the motor cortex.Thus,this study provides evidence of the potential functional involvement of adult-born oligodendrocytes in the motor impairments observed in the depressed animals.Additionally,it offers preliminary results for further investigation into layer I of the motor cortex in relation to these pathological conditions.
文摘Neurodevelopmental processes represent a finely tuned interplay between genetic and environmental factors,shaping the dynamic landscape of the developing brain.A major component of the developing brain that enables this dynamic is the white matter(WM),known to be affected in neurodevelopmental disorders(NDDs)(Rokach et al.,2024).WM formation is mediated by myelination,a multifactorial process driven by neuro-glia interactions dependent on proper neuronal functionality(Simons and Trajkovic,2006).Another key aspect of neurodevelopmental abnormalities involves neuronal dynamics and function,with recent advances significantly enhancing our understanding of both neuronal and glial mitochondrial function(Devine and Kittler,2018;Rojas-Charry et al.,2021).Energy homeostasis in neurons,attributed largely to mitochondrial function,is critical for proper functionality and interactions with oligodendrocytes(OLs),the cells forming myelin in the brain’s WM.We herein discuss the interplay between these processes and speculate on potential dysfunction in NDDs.
基金supported by grants from the Deutsche Forschungsgemeinschaft(DFG)to MW.
文摘Oligodendrocytes and their cell-intrinsic gene regulatory network:Oligodendrocytes(OLs)are the myelinating glial cells of the vertebrate central nervous system.They are responsible for insulating neuronal axons with a lipid-rich myelin sheath,which enables the saltatory conduction of action potentials.During development,oligodendrocyte progenitor cells(OPCs)emerge from neural stem cells in the ventricular zone.They then proliferate,increase their number,and migrate to their final destination where they encounter unmyelinated neuronal axons and differentiate in a stepwise fashion into myelinating oligodendrocytes(mOLs)under the influence of environmental stimuli.
文摘OBJECTIVE: To investigate the growth and development of myelin of sheath fetal brain. METHODS: Forty-four cases of pregnant women were imaged with magnetic resonance (MR) at 0.35 T (tesla). The signal changes of the main structures of fetal brain were analysed. RESULTS: The signal intensity of cerebral (except basal ganglia) and cerebellar matter was hypo-signal on the T1WI (T1 weighted spin-echo image), iso-signal of the PDWI (Proton density weighted image) and hyper-signal on the T2WI (T2 weighted spin-echo image). As to the brain stem and basal ganglia, their signal intensities showed difference in different gestational weeks on T1WI. The intensities were of slight hypo-signal before and iso-signal after the 29th week. However, their signal intensities on PDWI and T2WI were the same as those of the cerebral and cerebellar matter. CONCLUSIONS: There was no myelinization of fetal cerebral (except basal ganglia) and cerebellar matter during pregnant period. The myelin sheath was formed in the brain stem and basal ganglia after 29 gestational weeks. The process of myelinization began from brain stem to basal ganglia.
基金supported by the National Natural Science Foundation of China,No.82072110Suzhou Municipal Science and Technology Bureau,No.SKJY2021046+1 种基金Shanghai Key Lab of Forensic Medicine&Key Lab of Forensic Science,Ministry of Justice,China(Academy of Forensic Science),No.KF202201a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)(all to TW).
文摘Cholesterol is an important component of plasma membranes and participates in many basic life functions,such as the maintenance of cell membrane stability,the synthesis of steroid hormones,and myelination.Cholesterol plays a key role in the establishment and maintenance of the central nervous system.The brain contains 20%of the whole body’s cholesterol,80%of which is located within myelin.A huge number of processes(e.g.,the sterol regulatory element-binding protein pathway and liver X receptor pathway)participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis,intracellular transport,and efflux.Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences.Therefore,we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases.Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype,with high mortality and morbidity.Historical cholesterol levels are associated with the risk of intracerebral hemorrhage.Moreover,secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation,such as neuroinflammation,demyelination,and multiple types of programmed cell death.Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage.In this paper,we review normal cholesterol metabolism in the central nervous system,the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage,and the links between cholesterol metabolism and cell death.We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.
基金supported by the National Natural Science Foundation of China,Nos.82071307(to HL),82271362(to HL),82171294(to JW),82371303(to JW),and 82301460(to PX)the Natural Science Foundation of Jiangsu Province,No.BK20211552(to HL)+1 种基金Suzhou Medical Technology Innovation Project-Clinical Frontier,No.SKY2022002(to ZY)the Science and Education Foundation for Health of Suzhou for Youth,No.KJXW2023001(to XL)。
文摘Differentiation of oligodendrocyte progenitor cells into mature myelin-forming oligodendrocytes contributes to remyelination.Failure of remyelination due to oligodendrocyte progenitor cell death can result in severe nerve damage.Ferroptosis is an iron-dependent form of regulated cell death caused by membrane rupture induced by lipid peroxidation,and plays an important role in the pathological process of ischemic stroke.However,there are few studies on oligodendrocyte progenitor cell ferroptosis.We analyzed transcriptome sequencing data from GEO databases and identified a role of ferroptosis in oligodendrocyte progenitor cell death and myelin injury after cerebral ischemia.Bioinformatics analysis suggested that perilipin-2(PLIN2)was involved in oligodendrocyte progenitor cell ferroptosis.PLIN2 is a lipid storage protein and a marker of hypoxia-sensitive lipid droplet accumulation.For further investigation,we established a mouse model of cerebral ischemia/reperfusion.We found significant myelin damage after cerebral ischemia,as well as oligodendrocyte progenitor cell death and increased lipid peroxidation levels around the infarct area.The ferroptosis inhibitor,ferrostatin-1,rescued oligodendrocyte progenitor cell death and subsequent myelin injury.We also found increased PLIN2 levels in the peri-infarct area that co-localized with oligodendrocyte progenitor cells.Plin2 knockdown rescued demyelination and improved neurological deficits.Our findings suggest that targeting PLIN2 to regulate oligodendrocyte progenitor cell ferroptosis may be a potential therapeutic strategy for rescuing myelin damage after cerebral ischemia.
文摘Copper is a transition metal and an essential element for the organism,as alterations in its homeostasis leading to metal accumulation or deficiency have pathological effects in several organs,including the central nervous system.Central copper dysregulations have been evidenced in two genetic disorders characterized by mutations in the copper-ATPases ATP7A and ATP7B,Menkes disease and Wilson’s disease,respectively,and also in multifactorial neurological disorders such as Alzheimer’s disease,Parkinson’s disease,amyotrophic lateral sclerosis,and multiple sclerosis.This review summarizes current knowledge about the role of copper in central nervous system physiology and pathology,reports about unbalances in copper levels and/or distribution under disease,describes relevant animal models for human disorders where copper metabolism genes are dysregulated,and discusses relevant therapeutic approaches modulating copper availability.Overall,alterations in copper metabolism may contribute to the etiology of central nervous system disorders and represent relevant therapeutic targets to restore tissue homeostasis.
基金supported by the National Natural Science Foundation of China,Nos.82271411(to RG),51803072(to WLiu)grants from the Department of Finance of Jilin Province,Nos.2022SCZ25(to RG),2022SCZ10(to WLiu),2021SCZ07(to RG)+2 种基金Jilin Provincial Science and Technology Program,No.YDZJ202201ZYTS038(to WLiu)The Youth Support Programmed Project of China-Japan Union Hospital of Jilin University,No.2022qnpy11(to WLuo)The Project of China-Japan Union Hospital of Jilin University,No.XHQMX20233(to RG)。
文摘Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms.Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration.However,recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration,particularly in the context of traumatic injuries.Consequently,autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration.Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths,thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation.These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration.A range of autophagyinducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries.This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration,summarizing the potential drugs and interventions that can be harnessed to promote this process.We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.
文摘BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NMOSD)or myelin oligodendrocyte glycoprotein antibody disease(MOGAD),has a very similar presentation but different prognostic implications and longterm management strategies.Vascular and metabolic factors are being thought to play a role in such autoimmune neuro-inflammatory disorders,apart from the obvious immune mediated damage.With the advent of optical coherence tomography angiography(OCTA),it is easy to pick up on these subclinical macular microvascular and structural changes.AIM To study the macular microvascular and structural changes on OCTA in atypical optic neuritis.METHODS This observational cross-sectional study involved 8 NMOSD and 17 MOGAD patients,diagnosed serologically,as well as 10 healthy controls.Macular vascular density(MVD)and ganglion cell+inner plexiform layer thickness(GCIPL)were studied using OCTA.RESULTS There was a significant reduction in MVD in NMOSD and MOGAD affected as well as unaffected eyes when compared with healthy controls.NMOSD and MOGAD affected eyes had significant GCIPL thinning compared with healthy controls.NMOSD unaffected eyes did not show significant GCIPL thinning compared to healthy controls in contrast to MOGAD unaffected eyes.On comparing NMOSD with MOGAD,there was no significant difference in terms of MVD or GCIPL in the affected or unaffected eyes.CONCLUSION Although significant microvascular and structural changes are present on OCTA between atypical optic neuritis and normal patients,they could not help in differentiating between NMOSD and MOGAD cases.
基金supported by KU Leuven Internal Funding(C3/21/012)the Research Foundation Flanders(FWO G092222N)(to LM)。
文摘Decades of research asserted that the oligodendroglial lineage comprises two cell types:oligodendrocyte precursor cells and oligodendrocytes.However,recent studies employing single-cell RNA sequencing techniques have uncovered novel cell states,prompting a revision of the existing terminology.Going forward,the oligodendroglial lineage should be delineated into five distinct cell states:oligodendrocyte precursor cells,committed oligodendrocyte precursor cells,newly formed oligodendrocytes,myelin-forming oligodendrocytes,and mature oligodendrocytes.This new classification system enables a deeper understanding of the oligodendroglia in both physiological and pathological contexts.Adopting this uniform terminology will facilitate comparison and integration of data across studies.This,including the consolidation of findings from various demyelinating models,is essential to better understand the pathogenesis of demyelinating diseases.Additionally,comparing injury models across species with varying regenerative capacities can provide insights that may lead to new therapeutic strategies to overcome remyelination failure.Thus,by standardizing terminology and synthesizing data from diverse studies across different animal models,we can enhance our understanding of myelin pathology in central nervous system disorders such as multiple sclerosis,Alzheimer's disease,and amyotrophic lateral sclerosis,all of which involve oligodendroglial and myelin dysfunction.
基金supported by a grant from Aston University,Birmingham,UK (to DM)。
文摘Myelin is the protective sheath surrounding nerve fibers, and its damage(demyelination) occurs in many central nervous system(CNS) diseases, including multiple sclerosis(MS), traumatic injury, neurodegenerative diseases such as Alzheimer's disease, and mental disorders such as schizophrenia(Barateiro et al., 2016). Repair of damaged myelin sheaths(remyelination) often fails in MS, leading to neuronal loss and irreversible functional deficits.
基金supported by grants from the Lone Star Paralysis Foundation,NIH R01NS081063Department of Defense award W81XWH-19-2-0054 to GDB+2 种基金supported by University of Wyoming Startup funds,Department of Defense grant W81XWH-17-1-0402the University of Wyoming Sensory Biology COBRE under National Institutes of Health(NIH)award number 5P20GM121310-02the National Institute of General Medical Sciences of the NIH under award number P20GM103432 to JSB。
文摘Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.
基金financially supported by the National Natural Science Foundation of China,Nos.82172104(to CX),81873767(to HZ)a grant from Jiangsu Provincial Research Hospital,Nos.YJXYY202204(to HZ),YJXYY202204-ZD04(to HZ)+5 种基金a grant from Jiangsu Provincial Key Medical CenterJiangsu Provincial Medical Innovation Center,No.CXZX202212Jiangsu Provincial Medical Key Discipline,No.ZDXK202240the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Technology Project of Nantong,No.MS22022008(to HZ)Postgraduate Research&Practice Innovation Program of Jiangsu Province,No.SJCX21_1457(to WW)。
文摘Demyelination and remyelination have been major focal points in the study of peripheral nerve regeneration following peripheral nerve injury.Notably,the gene regulatory network of regenerated myelin differs from that of native myelin.Silencing of enhancer of zeste homolog 2(EZH2)hinders the differentiation,maturation,and myelination of Schwann cells in vitro.To further determine the role of EZH2 in myelination and recovery post-peripheral nerve injury,conditional knockout mice lacking Ezh2 in Schwann cells(Ezh2^(fl/fl);Dhh-Cre and Ezh2^(fl/fl);Mpz-Cre)were generated.Our results show that a significant proportion of axons in the sciatic nerve of Ezh2-depleted mice remain unmyelinated.This highlights the crucial role of Ezh2 in initiating Schwann cell myelination.Furthermore,we observed that 21 days after inducing a sciatic nerve crush injury in these mice,most axons had remyelinated at the injury site in the control nerve,while Ezh2^(fl/fl);Mpz-Cre mice had significantly fewer remyelinated axons compared with their wild-type littermates.This suggests that the absence of Ezh2 in Schwann cells impairs myelin formation and remyelination.In conclusion,EZH2 has emerged as a pivotal regulatory factor in the process of demyelination and myelin regeneration following peripheral nerve injury.Modulating EZH2 activity during these processes may offer a promising therapeutic target for the treatment of peripheral nerve injuries.
