SIRT1 decelerates morphological processing of oligodendrocyte cell lines and regulates the expression of cytoskeleton-related oligodendrocyte proteins.

SIRT1 is involved in the regulation of a variety of biological processes such as metabolism, stress response, autophagy and differentiation. Although progenitor cells of oligodendrocytes (OPCs) express high level of SIRT1, its function on differentiation is unknown. Because we have shown that SIRT1 plays a pivotal role in differentiation of neural precursor cells, we hypothesized that SIRT1 may also participate in the differentiation of oligodendrocytes (OLGs). We examined whether SIRT1 was expressed in two human oligodendrocyte cell lines: KG-1-C and MO 3.13 OLG. Transfection of cell lines with SIRT1-siRNA and SIRT2-siRNA promoted the extension of cellular processes. SIRT1-siRNA and SIRT2-siRNA increased acetyl-α-tubulin level, conversely, over expression of SIRTs resulted in decreased the ratio of acetyl-α-tubulin to α-tubulin. We also found knockdown of SIRT1 and SIRT2 induced overexpression of ßIV-tubulin and tubulin polymerization promoting protein (TPPP) (OLG-specific cytoskeleton-related molecules) that distributed widely in cell bodies. Taken together, SIRT1 may play a role in oligodenroglial differentiation and myelinogenesis.

A Case of Unilateral Brachial Plexus Injury Caused by First-Rib Stress Fractures Presenting With an Uncontrollable Involuntary Movement of the Neck.

Stress fracture of the first rib is a rare but an important cause of brachial plexopathy. Here, we describe a patient with a unilateral brachial plexus injury presenting with involuntary neck movements. A 22-year-old man with cervical involuntary movements for 10 months was diagnosed with tardive dyskinesia. After admission, he abruptly noticed that he could not lift his right arm. The electrophysiological study revealed weakness of the right deltoid and brachioradialis, but normal findings in the other muscles innervated by the right C5 segment. Chest computed tomography showed fractures of the first rib on both sides, with callus formation. Based on the involvement of muscles innervated by the right axillary and radial nerves and presence of callus at the first rib, a diagnosis of right posterior cord entrapment was made. In the present case, intermittent strong contraction of muscles due to dyskinesia may have caused the stress fractures.

[Clinical characteristics of seizure-predominant autoimmune encephalitis and utility of anti-neuronal antibody scores for early treatment].

We analyzed 20 patients diagnosed with autoimmune neurological diseases with seizure predominance. In these patients, we examined the usefulness of Antibody Prevalence in Epilepsy and Encephalopathy (APE2) score and Antibodies Contributing to Focal Epilepsy Signs and Symptoms (ACES) score in autoimmune encephalitis (AE) for facilitating early treatment. APE2 score was positive in 19 of 20 patients. ACES score was positive in 15 of 20 patients, and 4 of 5 of the patients with negative ACES score did not have AE. Comprehensive assessment including the use of the above scores is desirable in the early stage of AE.

Cerebral Tuberculoma Diagnosed by Nested Polymerase Chain Reaction of a Formalin-fixed Paraffin-embedded Brain Biopsy Sample.

A 38-year-old man was taken to hospital with generalized clonic seizure. Brain magnetic resonance imaging (MRI) showed multiple ring-enhancing lesions centered in the left frontoparietal lobe. A histopathological examination of a brain biopsy sample revealed granulomatous lesions with caseous necrosis. We extracted DNA from a formalin-fixed paraffin-embedded (FFPE) brain specimen, and nested polymerase chain reaction (PCR) of the DNA sample detected the Mycobacterium tuberculosis-specific insertion sequence IS6110. The lesions worsened after anti-tuberculosis drugs were administered, which we considered to be a paradoxical response and continued treatment. A genetic diagnosis of M. tuberculosis using FFPE specimens is useful for diagnosing tuberculoma.

Anti-signal Recognition Particle Antibody-positive Immune-mediated Myopathy after mRNA-1273 SARS-CoV-2 Vaccination.

A 26-year-old Japanese woman developed a fever, myalgia and gait disturbance one day after receiving the second dose of the mRNA-1273 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. A neurological examination revealed symmetrical weakness and myalgia in proximal lower limbs, and a blood examination showed prominent elevation of creatinine kinase. Magnetic resonance imaging (MRI) revealed a high signal intensity in the thigh muscles on short-tau inversion recovery images, and antibody testing revealed positive findings for anti-signal recognition particle (SRP) antibody. Thus, anti-SRP antibody-positive immune-mediated myopathy was diagnosed. We initiated immunotherapy, and she was ultimately able to walk stably.

Sporadic Amyotrophic Lateral Sclerosis Due to a FUS P525L Mutation with Asymmetric Muscle Weakness and Anti-ganglioside Antibodies.

Amyotrophic lateral sclerosis (ALS) due to a fused in sarcoma (FUS) P525L mutation is characterized by a rapidly progressive course. Multifocal motor neuropathy (MMN) may resemble ALS in early stage and is associated with anti-ganglioside antibodies. A 38-year-old woman was admitted to our hospital because of progressive muscle weakness in the right limbs. She had mild mental retardation and minor deformities. Initially, we suspected MMN given the asymmetric muscle weakness and detection of anti-ganglioside antibodies. However, physical and electrophysiological tests did not support MMN, instead suggesting ALS. We confirmed a heterozygous P525L mutation and finally diagnosed this case as ALS due to an FUS mutation.

CD14 and Toll-Like Receptor 4 Promote Fibrillar Aß42 Uptake by Microglia Through A Clathrin-Mediated Pathway.

We previously demonstrated that microglia play an essential role in clearance of amyloid-ß (Aß) in Alzheimer's disease (AD)-like pathology. Our prior work also showed that several receptors expressed on microglia participated in Aß phagocytosis. However, clathrin-mediated endocytosis (CME), which is associated with production and release of Aß in neurons, has received much less attention in the context of microglial Aß uptake. To elucidate the detailed mechanisms of microglial Aß uptake pathways, we focused on CD14 and Toll-like receptor 4 (TLR4), which have been shown to mediate fibrillar Aß1 - 42 (fAß42) phagocytosis in microglia. CD14 has also been known to control lipopolysaccharide-induced internalization of TLR4 in a clathrin-dependent manner. However, it remains unclear whether CD14 and TLR4 engage in CME in microglial fAß42 uptake, including whether CD14 interacts with TLR4 in the process. In the present study, we found that CD14-positive microglia increased in an age-dependent manner in the cortex of AD model mice. Immunostaining showed that CD14 interacted with TLR4 to internalize fAß42 in the mouse microglial cell line MG6. Knock-down of CD14 and TLR4 in MG6 cells significantly reduced intracellular fAß42, showing their involvement in fAß42 uptake. We also found that clathrin participated in fAß42 uptake by MG6 cells. Furthermore, CD14 and TLR4 mediated fAß42 uptake via clathrin-dependent mechanisms. These results indicate that CD14 and TLR4 participate not only in phagocytosis but also in clathrin-dependent fAß42 internalization in microglia. These findings provide novel molecular understanding of microglial fAß42 uptake, which could be of therapeutic relevance for AD.

Evaluation of Mitochondrial Oxidative Stress in the Brain of a Transgenic Mouse Model of Alzheimer's Disease by in vitro Electron Paramagnetic Resonance Spectroscopy.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases responsible for progressive dementia. Deposition of amyloid-ß (Aß) in the brain is the most important pathophysiological hallmark of AD. In addition, recent evidence indicates that reactive oxygen species (ROS) derived from mitochondria contribute to progression of AD pathology. We thus hypothesized that Aß accumulates and oxidative stress increases in the brain mitochondria of a transgenic mouse model of AD (APdE9). We measured the quantity of Aß and the activity of the antioxidant enzyme superoxide dismutase (SOD) in brain mitochondrial fractions prepared from APdE9 and wild-type (WT) mice aged 6, 9, 15, and 18 months. We also quantified the age-related changes in redox status in the mitochondrial fractions obtained from both APdE9 and WT mouse brains by electron paramagnetic resonance (EPR) spectrometry using a paramagnetic nitroxide "Mito-Tempo" [(2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride monohydrate] as a mitochondria-targeted redox-sensitive probe. In APdE9 mice, Aß accumulated in brain mitochondria earlier than in the non-mitochondrial fraction of the brain. Furthermore, increased oxidative stress was demonstrated in brain mitochondria of APdE9 mice by in vitro SOD assay as well as EPR spectroscopy. EPR combined with a mitochondria-targeted redox-sensitive nitroxide probe is a potentially powerful tool to elucidate the etiology of AD and facilitate the development of new therapeutic strategies for AD.

Early administration of galantamine from preplaque phase suppresses oxidative stress and improves cognitive behavior in APPswe/PS1dE9 mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a common neurodegenerative disease that progressively impairs memory and cognition. Deposition of amyloid-ß (Aß) peptides is the most important pathophysiological hallmark of AD. Oxidative stress induced by generation of reactive oxygen species (ROS) is a prominent phenomenon in AD and known to occur early in the course of AD. Several reports suggest a relationship between change in redox status and AD pathology including progressive Aß deposition, glial cell activation, and inflammation. Galantamine is an acetylcholinesterase inhibitor and has been reported to have an oxidative stress inhibitory function. In the present study, galantamine was administered orally to AD model mice from before the appearance of Aß plaques (preplaque phase), and in vivo change in redox status of the brain was measured using electron paramagnetic resonance (EPR) imaging. Administration of galantamine from the preplaque phase ameliorated memory decline in Morris water maze test and novel object recognition test. Monitoring of the redox status of the brain using EPR imaging showed that galantamine treatment improved the unbalanced redox state. Additionally, galantamine administration enhanced microglial function to promote Aß clearance, reducing the Aß-positive area in the cortex and amount of insoluble Aß in the brain. In contrast, galantamine treatment from the preplaque phase suppressed the production of proinflammatory cytokines through neurotoxic microglial activity. Therefore, galantamine administration from the preplaque phase may have the potential of clinical application for the prevention of AD. In addition, our results demonstrate the usefulness of EPR imaging for speedy and quantitative evaluation of the efficacy of disease-modifying drugs for AD.

Transplantation of Mesenchymal Stem Cells Improves Amyloid-ß Pathology by Modifying Microglial Function and Suppressing Oxidative Stress.

Mesenchymal stem cells (MSC) are increasingly being studied as a source of cell therapy for neurodegenerative diseases, and several groups have reported their beneficial effects on Alzheimer's disease (AD). In this study using AD model mice (APdE9), we found that transplantation of MSC via the tail vein improved spatial memory in the Morris water maze test. Using electron paramagnetic resonance imaging to evaluate the in vivo redox state of the brain, we found that MSC transplantation suppressed oxidative stress in AD model mice. To elucidate how MSC treatment ameliorates oxidative stress, we focused on amyloid-ß (Aß) pathology and microglial function. MSC transplantation reduced Aß deposition in the cortex and hippocampus. Transplantation of MSC also decreased Iba1-positive area in the cortex and reduced activated ameboid shaped microglia. On the other hand, MSC transplantation accelerated accumulation of microglia around Aß deposits and prompted microglial Aß uptake and clearance as shown by higher frequency of Aß-containing microglia. MSC transplantation also increased CD14-positive microglia in vivo, which play a critical role in Aß uptake. To confirm the effects of MSC on microglia, we co-cultured the mouse microglial cell line MG6 with MSC. Co-culture with MSC enhanced Aß uptake by MG6 cells accompanied by upregulation of CD14 expression. Additionally, co-culture of MG6 cells with MSC induced microglial phenotype switching from M1 to M2 and suppressed production of proinflammatory cytokines. These data indicate that MSC treatment has the potential to ameliorate oxidative stress through modification of microglial functions, thereby improving Aß pathology in AD model mice.

Role of Suppressor of Cytokine Signaling 3 (SOCS3) in Altering Activated Microglia Phenotype in APPswe/PS1dE9 Mice.

In response to changes of the central nervous system environment, microglia are capable of acquiring diverse phenotypes for cytotoxic or immune regulation and resolution of injury. Alzheimer's disease (AD) pathology also induces several microglial activations, resulting in production of pro-inflammatory cytokines and reactive oxygen species or clearance of amyloid-ß (Aß) through phagocytosis. We previously demonstrated that microglial activation and increase in oxidative stress started from the middle age in APPswe/PS1dE9 mice, and hypothesized that M1 activation occurs in middle-aged AD mice by Aß stimulation. In the present study, we analyzed in vivo expressions of pro-inflammatory cytokines (M1 microglial markers), M2 microglial markers, and suppressor of cytokine signaling (SOCS) family, and examined the microglial phenotypic profile in APPswe/PS1dE9 mice. Then we compared the in vitro gene expression patterns of Aß- and lipopolysaccharide (LPS)-stimulated primary-cultured microglia. Microglia in APPswe/PS1dE9 mice exhibited an M1-like phenotype, expressing tumor necrosis factor α (TNFα) but not interleukin 6 (IL6). Aß-stimulated primary-cultured microglia also expressed TNFα but not IL6, whereas LPS-stimulated primary-cultured microglia expressed both pro-inflammatory cytokines. Furthermore, both microglia in APPswe/PS1dE9 mice and Aß-stimulated primary-cultured microglia expressed SOCS3. Reduction of SOCS3 expression in Aß-challenged primary-cultured microglia resulted in upregulation of IL6 expression. Our findings indicate that SOCS3 suppresses complete polarization to M1 phenotype through blocking IL6 production, and Aß-challenged primary-cultured microglia replicate the in vivo gene expression pattern of microglia in APPswe/PS1dE9 mice. Aß may induce the M1-like phenotype through blocking of IL6 by SOCS3.

A case of neuromyelitis optica presenting marked pleocytosis and hypoglycorrhachia.

A 57-year-old man initially developed chest discomfort, nausea, vomiting, headache and low-grade fever, followed by paraplegia, sensory disturbance below level Th5 and bilateral visual loss. He was admitted to our hospital on the 15th day of illness. MRI short T1 inversion recovery image showed multiple longitudinal lesions in the spinal cord below C3, and T2-weighted image showed abnormal hyperintensity within the left optic nerve. Cerebrospinal fluid (CSF) analysis revealed marked pleocytosis (1,719/µl) and hypoglycorrhachia (CSF glucose; 20 mg/dl). Intensive immunosuppressive therapy combined with antibiotics and antiviral agent were started immediately, resulting in relatively good visual outcome but no improvement of paraplegia and sensory disturbance. The patient's serum sample on admission was subsequently reported to be positive for anti-aquaporin-4 antibody. With no evidence of infectious diseases, neuromyelitis optica (NMO) was diagnosed. It should be borne in mind that marked hypogylcorrhachia may also be seen in NMO.

[A case of dural arteriovenous fistula of right cavernous sinus presenting bilateral eye symptoms].

An 85-year-old woman was first admitted to our hospital because of right ptosis and diplopia. Examinations showed right oculomotor paralysis and reduced vision in the right eye. Serological and neuroradiological examinations failed to reveal the etiology. Oral prednisolone was started for a presumptive diagnosis of idiopathic oculomotor nerve palsy, which resulted in little improvement. Approximately ten months after the first admission, left ptosis appeared and she was re-admitted to our hospital. One day after admission, external ophthalmoplegia and conjunctival injection on the left side appeared. MRI revealed abnormal flow void in the right cavernous sinus. Based on cerebral angiographic findings, dural arteriovenous fistula of the right cavernous sinus was diagnosed. Symptoms on the left side were considered to result from increased perfusion pressure due to venous drainage via the intercavernous sinus to the contralateral cavernous sinus. After transvenous embolization, symptoms and signs improved gradually. In a case of external ophthalmoplegia with unknown etiology, detailed neuroradiologyical examinations such as cerebral angiogram are advisable.