Peripheral Nerve Myelin Research Articles

Elucidation of peripheral nerve myelination by bimodal waveform analysis

PurposeAs the myelin sheath of the peripheral nerves is immaturely developed in children, a bimodal waveform may be evoked when sensory nerve conduction studies are performed in them. However, there has been no study regarding the relationship between age and the frequency of appearance of the bimodal waveform or the inter-peak latency. Herein, we examined how the bimodal waveform changes with age. MethodsA total of 218 sensory nerves (109 median and 109 ulnar nerves) in 86 children (0 to 15 years old) were analyzed. The frequency of the bimodal waveform and the distance-corrected inter-peak latency were examined with antidromic sensory nerve conduction studies of the upper limbs on proximal stimulation. ResultsThe frequency of bimodal waveforms and distance-corrected inter-peak latency decreased with age. Analysis of the slope line of the scatter plot demonstrated that the bimodal waveform was present until the age of 15–16 years. ConclusionThe bimodal waveform of sensory nerves faded with growth. Given that development-associated temporal dispersion is considered to be the cause of the differences in the bimodal waveform, our findings suggest that the underlying cause of the bimodal waveform is an immature myelin sheath, which may not be fully developed until the age of 15–16 years.

The Effects of Lavendustin‐A on Peripheral Nerve Degeneration in Hyperglycemic Danio rerio

Diabetic peripheral neuropathy (DPN) results in degenerating peripheral nerves and affects over 50% of people with diabetes. Despite its high prevalence, DPN’s molecular pathways remain unknown, limiting treatment to pain management. The Clark lab has characterized two novel models of hyperglycemia in zebrafish in which DPN‐like phenotypes are recapitulated, including demyelination. In an attempt to elucidate the unknown molecular mechanisms of DPN, candidate small molecule drugs are currently being tested to accentuate or attenuate neurodegeneration. Lavendustin‐A, an EGFR tyrosine kinase inhibitor (TKI), was hypothesized to have a neuroprotective role, as overactivation of EGFR in hyperglycemic environments is associated with fibrosis and the inhibition of regeneration in various tissue types. Tg(mbp:gfpcaax) larval zebrafish were incubated in egg water (control 1) or 120mM glucose solution (control 2 and treatment) starting five days post‐fertilization (dpf) until 10dpf. From 10‐12dpf, control 1 remained in egg water + 1% DMSO, control 2 remained in glucose solution + 1% DMSO, and the treatment group remained in glucose solution + 1% DMSO + 65.5µM Lavendustin‐A. 12dpf, lateral images of myelinated (MBP+) peripheral motor nerves were taken on an EVOS imaging system. Fiji (NIH) software was used to measure the length and fluorescent intensity of the myelinated nerves. Both nerve length (*p=0.025) and MBP fluorescent intensity (**p=0.0013) were significantly greater in the treatment group compared to the hyperglycemic fish (control 2), and no significant difference was observed between the treatment group and control 1. To determine if function was impacted, a touch‐response assay was conducted before (10dpf) and after (12dpf) drug treatment. Escape response was significantly impaired in hyperglycemic fish (treatment and control 2) at 10dpf (***p=0.0007) and significantly improved in the treatment group by 12dpf (***p=0.0003), yet did not fully recover, as there was still a significant difference between the treatment group and control 1 (**p=0.0017). Our data suggests a possible role of EGFR in hyperglycemia‐induced neurodegeneration, getting us one step closer to identifying potential therapeutics for clinical application.

Zoonotic Transmission of Campylobacter jejuni to Caretakers From Sick Pen Calves Carrying a Mixed Population of Strains With and Without Guillain Barré Syndrome-Associated Lipooligosaccharide Loci.

Campylobacter jejuni causes foodborne gastroenteritis and may trigger acute autoimmune sequelae including Guillain Barré Syndrome. Onset of neuromuscular paralysis is associated with exposure to C. jejuni lipooligosaccharide (LOS) classes A, B, C, D, and E that mimic and evoke antibodies against gangliosides on myelin and axons of peripheral nerves. Family members managing a Michigan dairy operation reported recurring C. jejuni gastroenteritis. Because dairy cattle are known to shed C. jejuni, we hypothesized that calves in the sick pen were the source of human infections. Fecal samples obtained from twenty-five calves, one dog, and one asymptomatic family member were cultured for Campylobacter. C. jejuni isolates were obtained from thirteen calves and the family member: C. coli from two calves, and C. hyointestinalis from two calves. Some calves had diarrhea; most were clinically normal. Typing of lipooligosaccharide biosynthetic loci showed that eight calf C. jejuni isolates fell into classes A, B, and C. Two calf isolates and the human isolate possessed LOS class E, associated mainly with enteric disease and rarely with Guillain Barré Syndrome. Multi-locus sequence typing, porA and flaA typing, and whole genome comparisons of the thirteen C. jejuni isolates indicated that the three LOS class E strains that included the human isolate were closely related, indicating zoonotic transmission. Whole-genome comparisons revealed that isolates differed in virulence gene content, particularly in loci encoding biosynthesis of surface structures. Family members experienced diarrheal illness repeatedly over 2 years, yet none experienced GBS despite exposure to calves carrying invasive C. jejuni with LOS known to elicit antiganglioside autoantibodies.

Transcriptome Analysis of Schwann Cells at Various Stages of Myelination Implicates Chromatin Regulator Sin3A in Control of Myelination Identity.

Enhancing remyelination after injury is of utmost importance for optimizing the recovery of nerve function. While the formation of myelin by Schwann cells (SCs) is critical for the function of the peripheral nervous system, the temporal dynamics and regulatory mechanisms that control the progress of the SC lineage through myelination require further elucidation. Here, using in vitro co-culture models, gene expression profiling of laser capture-microdissected SCs at various stages of myelination, and multilevel bioinformatic analysis, we demonstrated that SCs exhibit three distinct transcriptional characteristics during myelination: the immature, promyelinating, and myelinating states. We showed that suppressor interacting 3a (Sin3A) and 16 other transcription factors and chromatin regulators play important roles in the progress of myelination. Sin3A knockdown in the sciatic nerve or specifically in SCs reduced or delayed the myelination of regenerating axons in a rat crushed sciatic nerve model, while overexpression of Sin3A greatly promoted the remyelination of axons. Further, in vitro experiments revealed that Sin3A silencing inhibited SC migration and differentiation at the promyelination stage and promoted SC proliferation at the immature stage. In addition, SC differentiation and maturation may be regulated by the Sin3A/histone deacetylase2 (HDAC2) complex functionally cooperating with Sox10, as demonstrated by rescue assays. Together, these results complement the recent genome and proteome analyses of SCs during peripheral nerve myelin formation. The results also reveal a key role of Sin3A-dependent chromatin organization in promoting myelinogenic programs and SC differentiation to control peripheral myelination and repair. These findings may inform new treatments for enhancing remyelination and nerve regeneration.

Rapid, automated nerve histomorphometry through open-source artificial intelligence

We aimed to develop and validate a deep learning model for automated segmentation and histomorphometry of myelinated peripheral nerve fibers from light microscopic images. A convolutional neural network integrated in the AxonDeepSeg framework was trained for automated axon/myelin segmentation using a dataset of light-microscopic cross-sectional images of osmium tetroxide-stained rat nerves including various axonal regeneration stages. In a second dataset, accuracy of automated segmentation was determined against manual axon/myelin labels. Automated morphometry results, including axon diameter, myelin sheath thickness and g-ratio were compared against manual straight-line measurements and morphometrics extracted from manual labels with AxonDeepSeg as a reference standard. The neural network achieved high pixel-wise accuracy for nerve fiber segmentations with a mean (± standard deviation) ground truth overlap of 0.93 (± 0.03) for axons and 0.99 (± 0.01) for myelin sheaths, respectively. Nerve fibers were identified with a sensitivity of 0.99 and a precision of 0.97. For each nerve fiber, the myelin thickness, axon diameter, g-ratio, solidity, eccentricity, orientation, and individual x -and y-coordinates were determined automatically. Compared to manual morphometry, automated histomorphometry showed superior agreement with the reference standard while reducing the analysis time to below 2.5% of the time needed for manual morphometry. This open-source convolutional neural network provides rapid and accurate morphometry of entire peripheral nerve cross-sections. Given its easy applicability, it could contribute to significant time savings in biomedical research while extracting unprecedented amounts of objective morphologic information from large image datasets.

Efficacy and Safety of a Krabbe Disease Gene Therapy.

Krabbe disease is a lysosomal storage disease caused by mutations in the gene that encodes galactosylceramidase, in which galactosylsphingosine (psychosine) accumulation drives demyelination in the central and peripheral nervous systems, ultimately progressing to death in early childhood. Gene therapy, alone or in combination with transplant, has been developed for almost two decades in mouse models, with increasing therapeutic benefit paralleling the improvement of next-generation adeno-associated virus (AAV) vectors. This effort has recently shown remarkable efficacy in the canine model of the disease by two different groups that used either systemic or cerebrospinal fluid (CSF) administration of AAVrh10 or AAV9. Building on our experience developing CSF-delivered, AAV-based drug products for a variety of neurodegenerative disorders, we conducted efficacy, pharmacology, and safety studies of AAVhu68 delivered to the CSF in two relevant natural Krabbe animal models, and in nonhuman primates. In newborn Twitcher mice, the highest dose (1 × 1011 genome copies [GC]) of AAVhu68.hGALC injected into the lateral ventricle led to a median survival of 130 days compared to 40.5 days in vehicle-treated mice. When this dose was administered intravenously, the median survival was 49 days. A single intracisterna magna injection of AAVhu68.cGALC at 3 × 1013 GC into presymptomatic Krabbe dogs increased survival for up to 85 weeks compared to 12 weeks in controls. It prevented psychosine accumulation in the CSF, preserved peripheral nerve myelination, ambulation, and decreased brain neuroinflammation and demyelination, although some regions remained abnormal. In a Good Laboratory Practice-compliant toxicology study, we administered the clinical candidate into the cisterna magna of 18 juvenile rhesus macaques at 3 doses that displayed efficacy in mice. We observed no dose-limiting toxicity and sporadic minimal degeneration of dorsal root ganglia (DRG) neurons. Our studies demonstrate the efficacy, scalability, and safety of a single cisterna magna AAVhu68 administration to treat Krabbe disease. ClinicalTrials.Gov ID: NCT04771416.

Initial experience with label-free stimulated Raman scattering microscopy for intraoperative assessment of peripheral nerves

BackgroundDuring nerve repair, an intraoperative assessment of the quality of the nerve stump is critically important for achieving a good outcome. Frozen section analysis of osmium-hematoxylin stained sections has not been adopted at many centers, including ours. This has left us with bread-loafing the nerve and visually assessing for healthy fascicles. A technique that would allow for rapid, safe, quantitative intraoperative assessment of nerve quality, including myelin quantity, would be beneficial. Stimulated Raman Scattering (SRS) microscopy is a rapid, label-free technique that images lipids well that may be uniquely suited for this purpose. ObjectiveTo describe our initial experience and lessons learned using SRS microscopy for evaluation of peripheral nerve tissue. MethodsWe present 6 cases during which SRS microscopy was used to evaluate peripheral nerve tissue, including standard histology and SRS microscopy images, where applicable. ResultsOur current technique involves OCT embedding the nerve tissue and then cutting 70 µm sections on a standard cryostat. The SRS microscope slide is modified to change the buffer depth from 100 µm to 50 µm. We analyzed the gray scale composite images, merged from the CH2 (lipid) channel and CH3 (protein) channel. This technique reliably produced cross-sectional images and showed good capability for imaging myelinated axons within fascicles. ConclusionsWe demonstrate here an innovative approach to quantifying myelin in peripheral nerve using Stimulated Raman Scattering microscopy. This should prove useful in the care and surgical treatment of patients with peripheral nerve injuries.

A genetic compensatory mechanism regulated by Jun and Mef2d modulates the expression of distinct class IIa Hdacs to ensure peripheral nerve myelination and repair.

The class IIa histone deacetylases (HDACs) have pivotal roles in the development of different tissues. Of this family, Schwann cells express Hdac4, 5, and 7 but not Hdac9. Here, we show that a transcription factor regulated genetic compensatory mechanism within this family of proteins, blocks negative regulators of myelination ensuring peripheral nerve developmental myelination and remyelination after injury. Thus, when Hdac4 and 5 are knocked-out from Schwann cells in mice, a JUN-dependent mechanism induces the compensatory overexpression of Hdac7 permitting, although with a delay, the formation of the myelin sheath. When Hdac4, 5, and 7 are simultaneously removed, the myocyte-specific enhancer-factor d (MEF2D) binds to the promoter and induces the de novo expression of Hdac9, and although several melanocytic lineage genes are misexpressed and Remak bundle structure is disrupted, myelination proceeds after a long delay. Thus, our data unveil a finely tuned compensatory mechanism within the class IIa Hdac family, coordinated by distinct transcription factors, that guarantees the ability of Schwann cells to myelinate during development and remyelinate after nerve injury.

Prion Protein: The Molecule of Many Forms and Faces.

Cellular prion protein (PrPC) is a glycosylphosphatidylinositol (GPI)-anchored protein most abundantly found in the outer membrane of neurons. Due to structural characteristics (a flexible tail and structured core), PrPC interacts with a wide range of partners. Although PrPC has been proposed to be involved in many physiological functions, only peripheral nerve myelination homeostasis has been confirmed as a bona fide function thus far. PrPC misfolding causes prion diseases and PrPC has been shown to mediate β-rich oligomer-induced neurotoxicity in Alzheimer’s and Parkinson’s disease as well as neuroprotection in ischemia. Upon proteolytic cleavage, PrPC is transformed into released and attached forms of PrP that can, depending on the contained structural characteristics of PrPC, display protective or toxic properties. In this review, we will outline prion protein and prion protein fragment properties as well as overview their involvement with interacting partners and signal pathways in myelination, neuroprotection and neurodegenerative diseases.

Genetic approaches and pathogenic pathways in the clinical management of Charcot-Marie-Tooth disease

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuromuscular disorder, affecting at least 1 in 2500 individuals. CMT refers to a heterogeneous group of inherited neuropathies from both phenotypic and genetic points of view. Over the last decades, there have been important advances not only in the identification of causative genes but also in understanding the molecular basis for many forms of CMT. In fact, to date, around 100 genes have been related to CMT disease, thanks to next generation sequencing techniques, and they have been proven to affect either the myelin or axon of peripheral nerves. Moreover, its genetic diagnosis has remarkedly improved, although there are still difficulties when it comes to treatment. In this review, we explore in depth the eight most prevalent genes associated with CMT: GDAP1, GJB1, HINT1, MFN2, MPZ, PMP22, SH3TC2, and SORD. We also address the disrupted cellular processes and pathophysiological mechanisms involved in the disease. A better understanding of the pathogenic mechanisms responsible for each type of CMT would be essential to identifying molecular targets and therapeutic strategies.

All-Atom Modeling of Complex Cellular Membranes.

Cell membranes are composed of a variety of lipids and proteins where they interact with each other to fulfill their roles. The first step in modeling these interactions in molecular simulations is to have reliable mimetics of the membrane's lipid environment. This Feature Article presents our recent efforts to model complex cellular membranes using all-atom force fields. A short review of the CHARMM36 (C36) lipid force field and its recent update to incorporate the long-range dispersion is presented. Key examples of model membranes mimicking various species and organelles are given. These include single-celled organisms such as bacteria (E. coli., chlamydia, and P. aeruginosa) and yeast (plasma membrane, endoplasmic reticulum, and trans-Golgi network) and more advanced ones such as plants (soybean and Arabidopsis thaliana) and mammals (ocular lens, stratum corneum, and peripheral nerve myelin). Leaflet asymmetry in composition has also been applied to some of these models. With the increased lipid diversity in the C36 lipid FF, these complex models can better reflect the structural, mechanical, and dynamic properties of realistic membranes and open an opportunity to study biological processes involving other molecules.

AAV1.NT-3 gene therapy in a CMT2D model: phenotypic improvements in GarsP278KY/+ mice.

Glycyl–tRNA synthetase mutations are associated to the Charcot–Marie–Tooth disease type-2D. The GarsP278KY/+ model for Charcot–Marie–Tooth disease type-2D is known best for its early onset severe neuropathic phenotype with findings including reduced axon size, slow conduction velocities and abnormal neuromuscular junction. Muscle involvement remains largely unexamined. We tested the efficacy of neurotrophin 3 gene transfer therapy in two Gars mutants with severe (GarsP278KY/+) and milder (GarsΔETAQ/+) phenotypes via intramuscular injection of adeno-associated virus setoype-1, triple tandem muscle creatine kinase promoter, neurotrophin 3 (AAV1.tMCK.NT-3) at 1 × 1011 vg dose. In the GarsP278KY/+ mice, the treatment efficacy was assessed at 12 weeks post-injection using rotarod test, electrophysiology and detailed quantitative histopathological studies of the peripheral nervous system including neuromuscular junction and muscle. Neurotrophin 3 gene transfer therapy in GarsP278KY/+ mice resulted in significant functional and electrophysiological improvements, supported with increases in myelin thickness and improvements in the denervated status of neuromuscular junctions as well as increases in muscle fibre size along with attenuation of myopathic changes. Improvements in the milder phenotype GarsΔETAQ/+ was less pronounced. Furthermore, oxidative enzyme histochemistry in muscles from Gars mutants revealed alterations in the content and distribution of oxidative enzymes with increased expression levels of Pgc1a. Cox1, Cox3 and Atp5d transcripts were significantly decreased suggesting that the muscle phenotype might be related to mitochondrial dysfunction. Neurotrophin 3 gene therapy attenuated these abnormalities in the muscle. This study shows that neurotrophin 3 gene transfer therapy has disease modifying effect in a mouse model for Charcot–Marie–Tooth disease type-2D, leading to meaningful improvements in peripheral nerve myelination and neuromuscular junction integrity as well as in a unique myopathic process, associated with mitochondria dysfunction, all in combination contributing to functional outcome. Based on the multiple biological effects of this versatile molecule, we predict neurotrophin 3 has the potential to be beneficial in other aminoacyl-tRNA synthetase-linked Charcot–Marie–Tooth disease subtypes.

Astragaloside IV alleviates Schwann cell injury in diabetic peripheral neuropathy by regulating microRNA-155-mediated autophagy

BackgroundMicroRNA-155(miR-155) is closely associated with diabetic peripheral neuropathy (DPN). Astragaloside IV (AST) is a significant extract of Astragalus membranaceus, which has been found to be effective in the treatment of DPN. However, whether astragaloside IV alleviate DPN via regulating miR-155-mediated autophagy remains unclear. PurposeThis study was designed to evaluate the effects of AST on DPN myelin Schwann cells injury and explore the mechanism of AST in treating DPN for the first time. MethodsGK rats fed with high-fat diet and RSC96 cells cultured in high glucose were used to establish DPN Schwann cells injury in vivo and in vitro model. The effects of AST on DPN were explored through blood glucose detection, nerve function detection, pathological detection and the expression of Neuritin detected by immunohistochemical. To study the effect of AST on the DPN Schwann cells autophagy and the upstream PI3K/Akt/mTOR pathway, the expressions of beclin-1 and LC3 were detected by western blot (WB) in sciatic nerves and by immunofluorescence (IFC) in RSC96 cells. The real-time polymerase chain reaction (RT-PCR) was applied to detect the expressions of miR-155, ATG5, ATG12 both in vivo and in vitro. The binding effect of miR-155 and target gene PI3KCA was verified by luciferase reporter gene assay. The expressions of PI3K, p-Akt/Akt, p-mTOR/mTOR were detected by WB and the expressions of PI3KCA were detected by RT-PCR in vitro. The apoptosis was detected by flow cytometry. Meanwhile, the influence of miR-155 overexpression and knocked down on the above indicators was also detected in RSC96 cells. At last, further mechanism experiments were conducted to verify the mechanism of AST regulating the autophagy and apoptosis of RSC96 cells. ResultsAST reduced blood glucose levels, alleviated peripheral nerve myelin sheath injury, and improved neurological function in DPN rats. In addition, AST enhanced the autophagy activity and alleviated the apoptosis in RSC96 cell. Mechanism study shown that AST promote autophagy via regulating miR-155-mediated PI3K/Akt/mTOR signaling pathways. AST reduced RSC96 cells apoptosis by promoting autophagy. ConclusionAST alleviate the myelin sheath injury of DPN caused by the apoptosis of Schwann cells via enhancing autophagy, which was attributed to inhibiting the activation of the PI3K/Akt/mTOR signaling pathway by upregulating miR-155 expression.

Wrestling and Wrapping: A Perspective on SUMO Proteins in Schwann Cells

Schwann cell development and peripheral nerve myelination are finely orchestrated multistep processes; some of the underlying mechanisms are well described and others remain unknown. Many posttranslational modifications (PTMs) like phosphorylation and ubiquitination have been reported to play a role during the normal development of the peripheral nervous system (PNS) and in demyelinating neuropathies. However, a relatively novel PTM, SUMOylation, has not been studied in these contexts. SUMOylation involves the covalent attachment of one or more small ubiquitin-like modifier (SUMO) proteins to a substrate, which affects the function, cellular localization, and further PTMs of the conjugated protein. SUMOylation also regulates other proteins indirectly by facilitating non-covalent protein–protein interaction via SUMO interaction motifs (SIM). This pathway has important consequences on diverse cellular processes, and dysregulation of this pathway has been reported in several diseases including neurological and degenerative conditions. In this article, we revise the scarce literature on SUMOylation in Schwann cells and the PNS, we propose putative substrate proteins, and we speculate on potential mechanisms underlying the possible involvement of this PTM in peripheral myelination and neuropathies.

Simulations of Diabetic and Non-Diabetic Peripheral Nerve Myelin Lipid Bilayers

The multilayered myelin sheath is a critical component of both central and peripheral nervous systems, forming a protective barrier against axonal damage and facilitating the movement of nervous impulses. It is primarily composed of cholesterol (CHL1), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), sphingomyelin (SM), and galactosylceramide (GalCer) lipids. For rat sciatic nerve myelin (part of the peripheral nervous system, PNS), it has been found that cholesterol and unsaturated fatty acid contents are significantly lower in diabetic than in non-diabetic conditions. In this study, lipid compositions from experimental data are used to create four model rat sciatic nerve myelin lipid bilayers: PI-containing (non-diabetic and diabetic) and PS-containing (non-diabetic and diabetic), which were then simulated using the all-atom CHARMM36 force field. Simulation results of diabetic membranes indicate less rigid, more laterally expansive, and thinner bilayers as well as potentially reduced interactions between GalCer on opposing myelin leaflets, supporting a direct role of the cholesterol content decrease in instigating myelin deterioration and diabetic peripheral neuropathy. Compared to PI-lipids, PS-lipids were found to cause higher inter-lipid spacing and decreased order within membranes as a result of their smaller headgroup size and higher inter-lipid hydrogen bonding potential, which allow them to more frequently reside deeper in the membrane plane and produce pushing effects on other lipids. GalCer deuterium order parameters and non-diabetic headgroup-to-headgroup bilayer thicknesses were compared to experimental data, exhibiting close alignment, supporting the future usage of these models to study the PNS myelin sheath.

AAV2/9-mediated silencing of PMP22 prevents the development of pathological features in a rat model of Charcot-Marie-Tooth disease 1\u2009A

Charcot-Marie-Tooth disease 1 A (CMT1A) results from a duplication of the PMP22 gene in Schwann cells and a deficit of myelination in peripheral nerves. Patients with CMT1A have reduced nerve conduction velocity, muscle wasting, hand and foot deformations and foot drop walking. Here, we evaluate the safety and efficacy of recombinant adeno-associated viral vector serotype 9 (AAV2/9) expressing GFP and shRNAs targeting Pmp22 mRNA in animal models of Charcot-Marie-Tooth disease 1 A. Intra-nerve delivery of AAV2/9 in the sciatic nerve allowed widespread transgene expression in resident myelinating Schwann cells in mice, rats and non-human primates. A bilateral treatment restore expression levels of PMP22 comparable to wild-type conditions, resulting in increased myelination and prevention of motor and sensory impairments over a twelve-months period in a rat model of CMT1A. We observed limited off-target transduction and immune response using the intra-nerve delivery route. A combination of previously characterized human skin biomarkers is able to discriminate between treated and untreated animals, indicating their potential use as part of outcome measures.

The therapeutic effects of ginkgolides in Guillain-Barré syndrome and experimental autoimmune neuritis

BackgroundGuillain-Barré syndrome (GBS) is an acquired immune-mediated inflammatory peripheral neuropathy. The immune regulation of ginkgolides have been revealed in recent years. We herein investigate the potential therapeutic effects of ginkgolides both on GBS and its animal model, experimental autoimmune neuritis (EAN). MethodsEAN in C57BL/6 mice induced by subcutaneous injection with peripheral nerve myelin P0 protein peptide 180–199 (P0 peptide) were treated with ginkgolides at three different doses. GBS patients were randomly divided into two groups, the experimental group and the control group. The experimental group were treated with ginkgolides as soon as diagnosed. ResultsOur data indicated that ginkgolides administration daily ameliorated the score of EAN and delayed the peak of disease in EAN mice. Ginkgolides also down-regulated the proportions of T helper (Th) 17 cells in EAN spleens. Furthermore, we also found that administration of ginkgolides significantly decreased the levels of interferon (IFN)-γ and interleukin-12 (IL)-12 in GBS patients. ConclusionsOur results suggested that ginkgolides ameliorated the clinical score of EAN through down-regulating the proportions of Th 17 cells. Ginkgolides also suppressed inflammation response by decreasing pro-inflammatory cytokines IFN-γ and IL-12, suggesting ginkgolides had potential therapeutic effects on GBS patients and EAN in the future.

Crystal and solution structure of NDRG1, a membrane-binding protein linked to myelination and tumour suppression.

N-myc downstream-regulated gene 1 (NDRG1) is a tumour suppressor involved in vesicular trafficking and stress response. NDRG1 participates in peripheral nerve myelination, and mutations in the NDRG1 gene lead to Charcot-Marie-Tooth neuropathy. The 43-kDa NDRG1 is considered as an inactive member of the α/β hydrolase superfamily. In addition to a central α/β hydrolase fold domain, NDRG1 consists of a short N terminus and a C-terminal region with three 10-residue repeats. We determined the crystal structure of the α/β hydrolase domain of human NDRG1 and characterised the structure and dynamics of full-length NDRG1. The structure of the α/β hydrolase domain resembles the canonical α/β hydrolase fold with a central β sheet surrounded by α helices. Small-angle X-ray scattering and CD spectroscopy indicated a variable conformation for the N- and C-terminal regions. NDRG1 binds to various types of lipid vesicles, and the conformation of the C-terminal region is modulated upon lipid interaction. Intriguingly, NDRG1 interacts with metal ions, such as nickel, but is prone to aggregation in their presence. Our results uncover the structural and dynamic features of NDRG1, as well as elucidate its interactions with metals and lipids, and encourage studies to identify a putative hydrolase activity of NDRG1. DATABASES: The coordinates and structure factors for the crystal structure of human NDRG1 were deposited to PDB (PDB ID: 6ZMM).

Associations of cells from both innate and adaptive immunity with lower nerve conduction velocity: the Maastricht Study

IntroductionDistal sensorimotor polyneuropathy (DSPN) is common in people with diabetes but is also found in pre-diabetes. Peripheral nerve myelin damage, which can be assessed by reduced nerve conduction velocity (NCV),...

HERC1 Ubiquitin Ligase Is Required for Hippocampal Learning and Memory.

Mutations in the human HERC1 E3 ubiquitin ligase protein develop intellectual disability. The tambaleante (tbl) mouse carries a HERC1 mutation characterized by cerebellar ataxia due of adult cerebellar Purkinje cells death by extensive autophagy. Our previous studies demonstrated that both the neuromuscular junction and the peripheral nerve myelin sheaths are also affected in this mutant. Moreover, there are signs of dysregulated autophagy in the central nervous system in the tbl mouse, affecting spinal cord motor neurons, and pyramidal neurons of the neocortex and the hippocampal CA3 region. The tbl mutation affects associative learning, with absence of short- and long-term potentiation in the lateral amygdala, altered spinogenesis in their neurons, and a dramatic decrease in their glutamatergic input. To assess whether other brain areas engaged in learning processes might be affected by the tbl mutation, we have studied the tbl hippocampus using behavioral tests, ex vivo electrophysiological recordings, immunohistochemistry, the Golgi-Cox method and transmission electron microscopy. The tbl mice performed poorly in the novel-object recognition, T-maze and Morris water maze tests. In addition, there was a decrease in glutamatergic input while the GABAergic one remains unaltered in the hippocampal CA1 region of tbl mice, accompanied by changes in the dendritic spines, and signs of cellular damage. Moreover, the proportions of immature and mature neurons in the dentate gyrus of the tbl hippocampus differ relative to the control mice. Together, these observations demonstrate the important role of HERC1 in regulating synaptic activity during learning.