Emodin attenuates inflammation and demyelination in experimental autoimmune encephalomyelitis

Emodin,a substance extracted from herbs such as rhubarb,has a protective effect on the central nervous system.However,the potential therapeutic effect of emodin in the context of multiple sclerosis remains unknown.In this study,a rat model of experimental autoimmune encephalomyelitis was established by immune induction to simulate multiple sclerosis,and the rats were intraperitoneally injected with emodin(20 mg/kg/d)from the day of immune induction until they were sacrificed.In this model,the nucleotide-binding domain-like receptor family pyrin domain containing 3(NLRP3)inflammasome and the microglia exacerbated neuroinflammation,playing an important role in the development of multiple sclerosis.In addition,silent information regulator of transcription 1(SIRT1)/peroxisome proliferator-activated receptor-alpha coactivator(PGC-1α)was found to inhibit activation of the NLRP3 inflammasome,and SIRT1 activation reduced disease severity in experimental autoimmune encephalomyelitis.Furthermore,treatment with emodin decreased body weight loss and neurobehavioral deficits,alleviated inflammatory cell infiltration and demyelination,reduced the expression of inflammatory cytokines,inhibited microglial aggregation and activation,decreased the levels of NLRP3 signaling pathway molecules,and increased the expression of SIRT1 and PGC-1α.These findings suggest that emodin improves the symptoms of experimental autoimmune encephalomyelitis,possibly through regulating the SIRT1/PGC-1α/NLRP3 signaling pathway and inhibiting microglial inflammation.These findings provide experimental evidence for treatment of multiple sclerosis with emodin,enlarging the scope of clinical application for emodin.

Association between Alzheimer's disease pathogenesis and early demyelination and oligodendrocyte dysfunction

The APPSwe/PSEN1 dE9（APP/PS1） transgenic mouse model is an Alzheimer＇s disease mouse model exhibiting symptoms of dementia, and is commonly used to explore pathological changes in the development of Alzheimer＇s disease. Previous clinical autopsy and imaging studies suggest that Alzheimer＇s disease patients have white matter and oligodendrocyte damage, but the underlying mechanisms of these have not been revealed. Therefore, the present study used APP/PS1 mice to assess cognitive change, myelin loss, and corresponding changes in oligodendrocytes, and to explore the underlying mechanisms. Morris water maze tests were performed to evaluate cognitive change in APP/PS1 mice and normal C57 BL/6 mice aged 3 and 6 months. Luxol fast blue staining of the corpus callosum and quantitative reverse transcription-polymerase chain reaction（q RT-PCR） for myelin basic protein（MBP） mRNA were carried out to quantify myelin damage. Immunohistochemistry staining for NG2 and qRT-PCR for monocarboxylic acid transporter 1（MCT1） mRNA were conducted to assess corresponding changes in oligodendrocytes. Our results demonstrate that compared with C57 BL/6 mice, there was a downregulation of MBP mRNA in APP/PS1 mice aged 3 months. This became more obvious in APP/PS1 mice aged 6 months accompanied by other abnormalities such as prolonged escape latency in the Morris water maze test, shrinkage of the corpus callosum, upregulation of NG2-immunoreactive cells, and downregulation of MCT1 mRNA. These findings indicate that the involvement of early demyelination at 3 months and the oligodendrocyte dysfunction at 6 months in APP/PS1 mice are in association with Alzheimer＇s disease pathogenesis.

Intravenous transplantation of mouse embryonic stem cells attenuates demyelination in an ICR outbred mouse model of demyelinating diseases

Induction of demyelination in the central nervous system （CNS） of experimental mice using cuprizone is widely used as an animal model for studying the pathogenesis and treatment of demyelination. How- ever, different mouse strains used result in different pathological outcomes. Moreover, because current medicinal treatments are not always effective in multiple sclerosis patients, so the study of exogenous cell transplantation in an animal model is of great importance. The aims of the present study were to establish an alternative ICR outbred mouse model for studying demyelination and to evaluate the effects of intrave- nous cell transplantation in the present developed mouse model. Two sets of experiments were conducted. Firstly, ICR outbred and BALB/c inbred mice were fed with 0.2% cuprizone for 6 consecutive weeks; then demyelinating scores determined by luxol fast blue stain or immunolabeling with CNPase were evaluated. Secondly, attenuation of demyelination in ICR mice by intravenous injection of mES cells was studied. Scores for demyelination in the brains of ICR mice receiving cell injection （mES cells-injected group） and vehicle （sham-inoculated group） were assessed and compared. The results showed that cuprizone signifi- cantly induced demyelination in the cerebral cortex and corpus callosum of both ICR and BALB/c mice. Additionally, intravenous transplantation of mES cells potentially attenuated demyelination in ICR mice compared with sham-inoculated groups. The present study is among the earliest reports to describe the cuprizone-induced demyelination in ICR outbred mice. Although it remains unclear whether mES cells or trophic effects from mES cells are the cause of enhanced remyelination, the results of the present study may shed some light on exogenous cell therapy in central nervous system demyelinating diseases.

Dynamic glial response and crosstalk in demyelination-remyelination and neurodegeneration processes

Multiple sclerosis is an autoimmune disease in which the immune system attacks the myelin sheath in the central nervous system.It is characterized by blood-brain barrier dysfunction throughout the course of multiple sclerosis, followed by the entry of immune cells and activation of local microglia and astrocytes.Glial cells(microglia, astrocytes, and oligodendrocyte lineage cells) are known as the important mediators of neuroinflammation, all of which play major roles in the pathogenesis of multiple sclerosis.Network communications between glial cells affect the activities of oligodendrocyte lineage cells and influence the demyelination-remyelination process.A finely balanced glial response may create a favorable lesion environment for efficient remyelination and neuroregeneration.This review focuses on glial response and neurodegeneration based on the findings from multiple sclerosis and major rodent demyelination models.In particular, glial interaction and molecular crosstalk are discussed to provide insights into the potential cell-and molecule-specific therapeutic targets to improve remyelination and neuroregeneration.

New insights into the immunologic role of oligodendrocyte lineage cells in demyelination diseases

Oligodendrocyte lineage cells(OL-lineage cells)are a cell population that are crucial for mammalian central nervous system(CNS)myelination.OL-lineage cells go through developmental stages,initially differentiating into oligodendrocyte precursor cells(OPCs),before becoming immature oligodendrocytes,then mature oligodendrocytes(OLs).While the main function of cell lineage is in myelin formation,and increasing number of studies have turned to explore the immunological characteristics of these cells.Initially,these studies focused on discovering how OPCs and OLs are affected by the immune system,and then,how these immunological changes influence the myelination process.However,recent studies have uncovered another feature of OL-lineage cells in our immune systems.It would appear that OL-lineage cells also express immunological factors such as cytokines and chemokines in response to immune activation,and the expression of these factors changes under various pathologic conditions.Evidence suggests that OL-lineage cells actually modulate immune functions.Indeed,OL-lineage cells appear to play both"victim"and"agent"in the CNS which raises a number of questions.Here,we summarize immunologic changes in OL-lineage cells and their effects,as well as consider OL-lineage cell changes which influence immune cells under pathological conditions.We also describe some of the underlying mechanisms of these changes and their effects.Finally,we describe several studies which use OL-lineage cells as immunotherapeutic targets for demyelination diseases.

S4B-5 Effect of Fasudil on Remyelination Following the Cuprizone-Induced Demyelination in Male C57BL/6 Mice

Background Multiple sclerosis(MS)is an autoimmune,inflammatory demyelinating disease of the central nervous system(CNS)characterized by de-/remyelination,neuroinflammation and oligodendrocyte loss.Although a greater understanding of MS have increased acquaintance of the pathogenesis and pathophysiology,the exploration of treatment is still challenging.Fasudil,one of the most thoroughly studied Rho kinase(ROCK)inhibitors,has been shown to have effects in neurodegenerative diseases.However,the effect of Fasudil on preventing the progression of the demyelination in MS has not been evaluated.Cuprizone(CPZ)-induced demyelination is a model used to study de-/remyelination in the CNS.Some aspects of the histological pattern induced by CPZ are similar to MS.The aim of the study is to investigate the effect of Fasudil on CPZ-induced demyelination,and to explore the mechanisms for the possible remyelination.Materials and Methods Male C57 BL/6 mice(10-12 weeks old)were assigned into normal group,fed a normal diet;CPZ group,fed CPZ and intraperitoneally(i.p.)injected with normal saline after 4 weeks for consecutive 2 weeks;Fasudil-treated CPZ group,which were i.p.injected with Fasudil(40 mg/kg/day)after 4 weeks for consecutive 2 weeks.All groups were assessed by Elevated plus-maze(EPM)test and Pole test at the end of the experiment.For examing the extent of demyelination,Luxol Fast Blue(LFB)staining,Black GoldⅡand myelin basic protein(MBP)immunohistochemistry staining were used for slides of brains.Splenic MNCs were fixed and stained with the following antibodies:Alexa Fluor B220,FITCCD4/PE-IFN-γ,FITC-CD4/PE-IL-17.At least 10,000 events were collected using flow cytometer.Results Following CPZ-exposure,mice presented a lower density of LFB,Black GoldⅡand MBP expression,loss of mature oligodendrocytes.Spleen atrophy was observed in CPZ-group compared to normal mice,and we firstly found that CPZ feeding induced the formation of MOG antibody.Fasudil treatment improved behavioral abnormality,promoted remyelination,inhibited spleen atrophy and production of MOG antibodies,prevented the infiltration of peripheral T cells,B cells,macrophages,and declined the neuroinflammation by inhibiting Iba1+iNOS+,Iba1+NF-κB+microglia.Fasudil treatment also reduced the levels of IL-1β,IL-6 and TNF-α.Discussion In this study,we demonstrated that demyelinating model was successfully established.Then we tested whether Fasudil plays a remyelinating role in this model.Spleen atrophy was observed after CPZ-feeding compared to normal mice.Previous studies have shown that splenic atrophy in experimental stroke may contribute to brain injury possibly through the release of inflammatory mediators and spleen-derived inflammatory cells to the circulation and migration into the brain,which aggravate the brain inflammatory response and led to secondary injure.At present,we lack direct evidence to elucidate the mechanisms for spleen atrophy in CPZ-induced demyelination.We firstly found that CPZ-feeding induced the formation of MOG antibody.Recent study indicated that BBB hyperpermeability precedes demyelination in CPZ-demyelinating model.Another study suggested that debris of damaged cells in the CNS may present as antigens after penetrating the BBB,giving rise to autoantibodies.Therefore,it is possible that the myelin debris produced the destruction of myelin sheath can enter the blood circulation and stimulate the immune response of T and B cells.We found that MOG antibody was elevated in the supernatant of cultured plenocytes,indicating that the MOG antibodies were derived from peripheral immune cells.Our results showed that the level of MOG antibody in the brain homogenate of CPZ-treated mice was higher than that of normal mice,suggesting that antibodies can enter brain tissue and anti a-synuclein antibody was negative,which indicate that anti MOG antibody is a specific antibody.In our study,MOG antibody was capable of being detected in the brain of CPZ-treated mice,providing a possibility for specific MOG antibody-mediated oligodendrocyte damage.CPZ induced a wide range of Iba-1+microglia,which was inhibited by Fasudil.These results suggest that the suppression of inflammatory microenvironment may contribute to the remyelination.In conclusion,the administration of Fasudil promoted remyelination by multiple mechanisms.

Grape Seed Extract Attenuates Demyelination in Experimental Autoimmune Encephalomyelitis Mice by Inhibiting Inflammatory Response of Immune Cells

Objective: To examine the anti-inflammatory effect of grape seed extract(GSE) in animal and cellular models and explore its mechanism of action. Methods: This study determined the inhibitory effect of GSE on macrophage inflammation and Th1 and Th17 polarization in vitro. Based on the in vitro results, the effects and mechanisms of GSE on multiple sclerosis(MS)-experimental autoimmune encephalomyelitis(EAE) mice model were further explored. The C57BL/6 mice were intragastrically administered with 50 mg/kg of GSE once a day from the 3rd day to the 27th day after immunization. The activation of microglia, the polarization of Th1 and Th17and the inflammatory factors such as tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), IL-6, IL-12, IL-17and interferon-γ(IFN-γ) secreted by them were detected in vitro and in vivo by flow cytometry, enzyme linked immunosorbent assay(ELISA), immunofluorescence staining and Western blot, respectively. Results: GSE reduced the secretion of TNF-α, IL-1β and IL-6 in bone marrow-derived macrophages stimulated by lipopolysaccharide(P<0.01), inhibited the secretion of TNF-α, IL-1β, IL-6, IL-12, IL-17 and IFN-γ in spleen cells of EAE mice immunized for 9 days(P<0.05 or P<0.01), and reduced the differentiation of Th1 and Th17 mediated by CD3 and CD28 factors(P<0.01). GSE significantly improved the clinical symptoms of EAE mice, and inhibited spinal cord demyelination and inflammatory cell infiltration. Peripherally, GSE downregulated the expression of toll-like-receptor 4(TLR4) and Rho-associated kinase(ROCKⅡ, P<0.05 or P<0.01), and inhibited the secretion of inflammatory factors(P<0.01 or P<0.05). In the central nervous system, GSE inhibited the infiltration of CD45+CD11b+and CD45+CD4+cells, and weakened the differentiation of Th1 and Th17(P<0.05). Moreover, it reduced the secretion of inflammatory factors(P<0.01), and prevented the activation of microglia(P<0.05). Conclusion: GSE had a beneficial effect on the pathogenesis and progression of EAE by inhibiting inflammatory response as a potential drug and strategy for the treatment of MS.

Star power: harnessing the reactive astrocyte response to promote remyelination in multiple sclerosis

Astrocytes are indispensable for central nervous system development and homeostasis.In response to injury and disease,astrocytes are integral to the immunological-and the,albeit limited,repair response.In this review,we will examine some of the functions reactive astrocytes play in the context of multiple sclerosis and related animal models.We will consider the heterogeneity or plasticity of astrocytes and the mechanisms by which they promote or mitigate demyelination.Finally,we will discuss a set of biomedical strategies that can stimulate astrocytes in their promyelinating response.

Polarization of macrophages and microglia in inflammatory demyelination

Multiple sclerosis （MS） is an autoimmune demyelinating disease of the central nervous system, and microglia and macrophages play important roles in its pathogenesis. The activation of microglia and macrophages ac- companies disease development, whereas depletion of these cells significantly decreases disease severity. Microglia and macrophages usually have diverse and plastic phenotypes. Both pro-inflammatory and anti- inflammatory microglia and macrophages exist in MS and its animal model, experimental autoimmune enceph- alomyelitis. The polarization of microglia and macrophages may underlie the differing functional properties that have been reported. In this review, we discuss the responses and polarization of microglia and macrophages in MS, and their effects on its pathogenesis and repair. Harnessing their beneficial effects by modulating their polarization states holds great promise for the treatment of inflammatory demyelinating diseases.

Myt1L Promotes Differentiation of Oligodendrocyte Precursor Cells and is Necessary for Remyelination After Lysolecithin-Induced Demyelination

The differentiation and maturation of oligodendrocyte precursor cells(OPCs) is essential for myelination and remyelination in the CNS. The failure of OPCs to achieve terminal differentiation in demyelinating lesions often results in unsuccessful remyelination in a variety of human demyelinating diseases. However, the molecular mechanisms controlling OPC differentiation under pathological conditions remain largely unknown. Myt1 L(myelin transcription factor 1-like), mainly expressed in neurons,has been associated with intellectual disability, schizophrenia, and depression. In the present study, we found that Myt1 L was expressed in oligodendrocyte lineage cells during myelination and remyelination. The expression level of Myt1 L in neuron/glia antigen 2-positive(NG2+)OPCs was significantly higher than that in mature CC1+oligodendrocytes. In primary cultured OPCs,overexpression of Myt1 L promoted, while knockdown inhibited OPC differentiation. Moreover, Myt1 L was potently involved in promoting remyelination after lysolecithin-induced demyelination in vivo. Ch IP assays showed that Myt1 L bound to the promoter of Olig1 and transcriptionally regulated Olig1 expression. Taken together, our findings demonstrate that Myt1 L is an essential regulator of OPC differentiation, thereby supporting Myt1 L as a potential therapeutic target for demyelinating diseases.

Different distributions of nerve demyelination in chronic acquired multifocal polyneuropathies

Background:Multifocal motor neuropathy(MMN),Lewis-Sumner syndrome(LSS),and many chronic inflammatory demyelinating polyradiculoneuropathies(CIDPs)are representative of acquired multifocal polyneuropathy and are characterized by conduction block(CB).This retrospective study aimed to investigate the demyelinating distribution and the selective vulnerability of MMN,LSS,and CIDP with CB(CIDP-CB)in nerves.Methods:Fifteen LSS subjects(107 nerves),24 MMN subjects(176 nerves),and 17 CIDP-CB subjects(110 nerves)were included.Their clinical information was recorded,blood and cerebrospinal fluid tests were conducted,and nerve conductions of the median,ulnar,radial,peroneal,and tibial nerves were evaluated.CB,temporal dispersion,distal motor latency(DML),and F-wave latency were recorded,and nerve conduction velocity,terminal latency index,and modified F-wave ratio were calculated.Results:CB was more likely to occur around the elbow in CIDP-CB than in MMN(78.6%vs.6.8%,P<0.01)but less likely to occur between the wrist and the elbow than in LSS(10.7%vs.39.3%,P<0.05).Tibial nerve CB was most frequently observed in MMN(47.4%,P<0.05).CIDP-CB was characterized by a prolonged DML in all nerves,and slow motor nerve velocity of the upper limb was significant when CB nerves were excluded(P<0.05).Conclusions:We report the different distributions of segmental and diffuse demyelination of the ulnar and tibial nerves in LSS,MMN,and CIDP-CB.These distinct distributions could help in differentiating among these conditions.

Clemastine rescues behavioral changes and enhances remyelination in the cuprizone mouse model of demyelination

Increasing evidence suggests that white matter disorders based on myelin sheath impairment may underlie the neuropathological changes in schizophrenia.But it is unknown whether enhancing remyelination is a beneficial approach to schizophrenia.To investigate this hypothesis,we used clemastine,an FDA-approved drug with high potency in promoting oligodendroglial differentiation and myelination,on a cuprizone-induced mouse model of demyelination.The mice exposed to cuprizone（0.2%in chow） for 6 weeks displayed schizophrenia-like behavioral changes,including decreased exploration of the center in the open field test and increased entries into the arms of the Y-maze,as well as evident demyelination in the cortex and corpus callosum.Clemastine treatment was initiated upon cuprizone withdrawal at 10 mg/kg per day for3 weeks.As expected,myelin repair was greatly enhanced in the demyelinated regions with increased mature oligodendrocytes（APC-positive） and myelin basic protein.More importantly,the clemastine treatment rescued the schizophrenia-like behavioral changes in the open field test and the Y-maze compared to vehicle,suggesting a beneficial effect via promoting myelin repair.Our findings indicate that enhancing remyelination may be a potential therapy for schizophrenia.

Demyelinating neuropathy in patients with hepatitis B virus: A case report

BACKGROUND Hepatitis B rarely leads to demyelinating neuropathy,despite peripheral neuropathy being the first symptom of hepatitis B infection.CASE SUMMARY A 64-year-old man presented with sensorimotor symptoms in multiple peripheral nerves.Serological testing showed that these symptoms were due to hepatitis B.After undergoing treatment involving intravenous immunoglobulin and an antiviral agent,there was a notable improvement in his symptoms.CONCLUSION Although hepatitis B virus(HBV)infection is known to affect hepatocytes,it is crucial to recognize the range of additional manifestations linked to this infection.The connection between long-term HBV infection and demyelinating neuropathy has seldom been documented;hence,prompt diagnostic and treatment are essential.The patient's positive reaction to immunoglobulin seems to be associated with production of the antigen-antibody immune complex.

Conditional Deletion of Foxg1 Alleviates Demyelination and Facilitates Remyelination via the Wnt Signaling Pathway in Cuprizone-Induced Demyelinated Mice

The massive loss of oligodendrocytes caused by various pathological factors is a basic feature of many demyelinating diseases of the central nervous system(CNS). Based on a variety of studies, it is now well established that impairment of oligodendrocyte precursor cells(OPCs) to differentiate and remyelinate axons is a vital event in the failed treatment of demyelinating diseases. Recent evidence suggests that Foxg1 is essential for the proliferation of certain precursors and inhibits premature neurogenesis during brain development. To date, very little attention has been paid to the role of Foxg1 in the proliferation and differentiation of OPCs in demyelinating diseases of the CNS. Here, for the first time, we examined the effects of Foxg1 on demyelination and remyelination in the brain using a cuprizone(CPZ)-induced mouse model. In this work, 7-week-old Foxg1 conditional knockout and wild-type(WT) mice were fed a diet containing 0.2% CPZ w/w for 5 weeks, after which CPZ was withdrawn to enable remyelination. Our results demonstrated that, compared with WT mice, Foxg1-knockout mice exhibited not only alleviated demyelination but also accelerated remyelination of the demyelinated corpus callosum. Furthermore, we found that Foxg1 knockout decreased the proliferation of OPCs and accelerated their differentiation into mature oligodendrocytes both in vivo and in vitro. Wnt signaling plays a critical role in development and in a variety of diseases. GSK-3 b, a key regulatory kinase in the Wnt pathway, regulates the ability of b-catenin to enter nuclei, where it activates the expression of Wnt target genes. We then used SB216763,a selective inhibitor of GSK-3 b activity, to further demonstrate the regulatory mechanism by which Foxg1 affects OPCs in vitro. The results showed that SB216763 clearly inhibited the expression of GSK-3 b, which abolished the effect of the proliferation and differentiation of OPCs caused by the knockdown of Foxg1. These results suggest that Foxg1 is involved in the proliferation and differentiation of OPCs through the Wnt signaling pathway. The present experimental results are some of the first to suggest that Foxg1 is a new therapeutic target for the treatment of demyelinating diseases of the CNS.

The circ_0002538/miR-138-5p/plasmolipin axis regulates Schwann cell migration and myelination in diabetic peripheral neuropathy

Circular RNAs(circRNAs)play a vital role in diabetic peripheral neuropathy.However,their expression and function in Schwann cells in individuals with diabetic peripheral neuropathy remain poorly understood.Here,we performed protein profiling and circRNA sequencing of sural nerves in patients with diabetic peripheral neuropathy and controls.Protein profiling revealed 265 differentially expressed proteins in the diabetic peripheral neuropathy group.Gene Ontology indicated that differentially expressed proteins were mainly enriched in myelination and mitochondrial oxidative phosphorylation.A real-time polymerase chain reaction assay performed to validate the circRNA sequencing results yielded 11 differentially expressed circRNAs.circ_0002538 was markedly downregulated in patients with diabetic peripheral neuropathy.Further in vitro experiments showed that overexpression of circ_0002538 promoted the migration of Schwann cells by upregulating plasmolipin(PLLP)expression.Moreover,overexpression of circ_0002538 in the sciatic nerve in a streptozotocin-induced mouse model of diabetic peripheral neuropathy alleviated demyelination and improved sciatic nerve function.The results of a mechanistic experiment showed that circ_0002538 promotes PLLP expression by sponging miR-138-5p,while a lack of circ_0002538 led to a PLLP deficiency that further suppressed Schwann cell migration.These findings suggest that the circ_0002538/miR-138-5p/PLLP axis can promote the migration of Schwann cells in diabetic peripheral neuropathy patients,improving myelin sheath structure and nerve function.Thus,this axis is a potential target for therapeutic treatment of diabetic peripheral neuropathy.

Poly-L-ornithine blocks the inhibitory effects of fibronectin on oligodendrocyte differentiation and promotes myelin repair

The extracellular matrix surrounding oligodendrocytes plays an important role during myelination and remyelination in the brain.In many cases,the microenvironment surrounding demyelination lesions contains inhibitory molecules,which lead to repair failure.Accordingly,blocking the activity of these inhibitory factors in the extracellular matrix should lead to more successful remyelination.In the central nervous system,oligodendrocytes form the myelin sheath.We performed primary cell culture and found that a natural increase in fibronectin promoted the proliferation of oligodendrocyte progenitors during the initial stage of remyelination while inhibiting oligodendrocyte differentiation.Poly-L-ornithine blocked these inhibitory effects without compromising fibronectin’s pro-proliferation function.Experiments showed that poly-L-ornithine activated the Erk1/2 signaling pathway that is necessary in the early stages of differentiation,as well as PI3K signaling pathways that are needed in the mid-late stages.When poly-L-ornithine was tested in a lysolecithin-induced animal model of focal demyelination,it enhanced myelin regeneration and promoted motor function recovery.These findings suggest that poly-L-ornithine has the potential to be a treatment option for clinical myelin sheath injury.

Mechanisms and treatment strategies of demyelinating and dysmyelinating Charcot-Marie-Tooth disease

Schwann cells,the myelinating glia of the peripheral nervous system,wrap axons multiple times to build their myelin sheath.Myelin is of paramount importance for axonal integrity and fast axon potential propagation.However,myelin is lacking or dysfunctional in several neuropathies including demyelinating and dysmyelinating Charcot-M arie-To oth disease.Charcot-Marie-To oth disease represents the most prevalent inherited neuropathy in humans and is classified either as axonal,demyelinating or dysmyelinating,or as intermediate.The demyelinating or dysmyelinating forms of Charcot-Marie-Tooth disease constitute the majority of the disease cases and are most frequently due to mutations in the three following myelin genes:peripheral myelin protein 22,myelin protein ze ro and gap junction beta 1(coding for Connexin 32) causing Charcot-M arie-Tooth disease type 1A,Charcot-Marie-Tooth disease type 1B,and X-linked Charcot-M arie-Tooth disease type 1,respectively.The resulting perturbation of myelin structure and function leads to axonal demyelination or dysmyelination and causes severe disabilities in affected patients.No treatment to cure or slow down the disease progression is currently available on the market,howeve r,scientific discoveries led to a better understanding of the pathomechanisms of the disease and to potential treatment strategies.In this review,we describe the features and molecular mechanisms of the three main demyelinating or dysmyelinating forms of Charcot-Marie-Tooth disease,the rodent models used in research,and the emerging therapeutic approaches to cure or counteract the progression of the disease.

X-linked Charcot-Marie-Tooth disease after SARS-CoV-2 vaccination mimicked stroke-like episodes: A case report

BACKGROUND Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) vaccinations have been administered worldwide, with occasional reports of associated neurological complications. Specifically, the impact of vaccinations on individuals with Xlinked Charcot-Marie-Tooth disease type 1(CMTX1) is unclear. Patients with CMTX1 can have stroke-like episodes with posterior reversible encephalopathy syndrome on magnetic resonance imaging(MRI), although this is rare.CASE SUMMARY A 39-year-old man was admitted with episodic aphasia and dysphagia for 2 d. He received SARS-CoV-2 vaccination 39 d before admission. Physical examination showed pes cavus and reduced tendon reflexes. Brain MRI showed bilateral, symmetrical, restricted diffusion with T2 hyperintensities in the cerebral hemispheres. Nerve conduction studies revealed peripheral nerve damage. He was diagnosed with Charcot-Marie-Tooth disease, and a hemizygous mutation in the GJB1 gene on the X chromosome, known to be pathogenic for CMTX1, was identified. Initially, we suspected transient ischemic attack or demyelinating leukoencephalopathy. We initiated treatment with antithrombotic therapy and immunotherapy. At 1.5 mo after discharge, brain MRI showed complete resolution of lesions, with no recurrence.CONCLUSION SARS-CoV-2 vaccination could be a predisposing factor for CMTX1 and trigger a sudden presentation.

CHARACTERIZATION OF SIGNAL CONDUCTIONALONG DEMYELINATED AXONS BY ACTION-POTENTIAL-ENCODED SECOND HARMONICGENERATION

Action-potential encoded optical second harmonic generation(SHG)has been recently proposedfor use in det ecting the axonal damage in patients with demnyelinat ing diseases.In this study,thecharact erization of signal conduction along axons of two different levels of denyelination wasstudied via a modified Hodgkin Huxley model,because some types of demyelinating disease,i.e.primary progressive and secondary progesive multiple scleross,are dificult to be distinguishedby magnetic resonance imaging(MRI),we focused on the diferences in signal conduction between two diferent demyelinated axons,such as the first-level demyelination and the second.level demyelination.The spatio-temporal distribution of action potentials along denyelinatedaxons and conduction properties including the refractory period and frequency encoding in theset wo patterns were investigated.The results showed that denyelination could induce the decreaseboth in the amplitude of action potentials and the ability of frequency coding,Furthermore,t hesignal conduction velocity in the second-level dernyelination was about 21%slower than that inthe first-level demyelination.The refractory period in the second-level demyelination was about32%longer t han the first-level.Thus,detecting the signal conduction in demnyelinat ed axons byaction-potential encoded optical SHG could greatly improve the assessment of demyelinatingdisorders to classify the patients.This technique also offers a potential fast and noninvasiveoptical approach for monitoring membrane potential.

Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury （SCI） is a devastating type of neurological trauma with limited therapeutic op- portunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contrib- utor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of mi- croglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.