Published papers

© The Author(s) 2020. Capsaicin is an agonist of transient receptor potential cation channel subfamily V member 1 (TRPV1). Strong TRPV1 stimulation with capsaicin causes mitochondrial damage in primary sensory neurons. However, the effect of repetitive and moderate exposure to capsaicin on the integrity of neuronal mitochondria remains largely unknown. Our electron microscopic analysis revealed that repetitive stimulation of the facial skin of mice with 10 mM capsaicin induced short-term damage to the mitochondria in small-sized trigeminal ganglion neurons. Further, capsaicin-treated mice exhibited decreased sensitivity to noxious heat stimulation, indicating TRPV1 dysfunction, in parallel with the mitochondrial damage in the trigeminal ganglion neurons. To analyze the capsaicin-induced mitochondrial damage and its relevant cellular events in detail, we performed cell-based assays using TRPV1-expressing PC12 cells. Dose-dependent capsaicin-mediated mitochondrial toxicity was observed. High doses of capsaicin caused rapid destruction of mitochondrial internal structure, while low doses induced mitochondrial swelling. Further, capsaicin induced a dose-dependent loss of mitochondria and autophagy-mediated degradation of mitochondria (mitophagy). Concomitantly, transcriptional upregulation of mitochondrial proteins, cytochrome c oxidase subunit IV, Mic60/Mitofilin, and voltage-dependent anion channel 1 was observed, which implied induction of mitochondrial biogenesis to compensate for the loss of mitochondria. Collectively, although trigeminal ganglion neurons transiently exhibit mitochondrial damage and TRPV1 dysfunction following moderate capsaicin exposure, they appear to be resilient to such a challenge. Our in vitro data show a dose–response relationship in capsaicin-mediated mitochondrial toxicity. We postulate that induction of mitophagy and mitochondrial biogenesis in response to capsaicin stimulation play important roles in repairing the damaged mitochondrial system.

© 2020 Lippincott Williams and Wilkins. All rights reserved. Background and Purpose: Cerebral microbleeds (CMB) are associated with stroke and cognitive impairment. We previously reported a high prevalence of CMB in people with Streptococcus mutans expressing Cnm, a collagen-binding protein in the oral cavity. S. mutans is a major pathogen responsible for dental caries. Repeated challenge with S. mutans harboring the cnm gene encoding Cnm induced cerebral bleeding in stroke-prone spontaneously hypertensive rats. The purpose of this longitudinal study is to examine the relationship of cnm-positive S. mutans to the development of CMB. Methods: We retrospectively investigated patients with stroke receiving oral microbiological examination and head 3T magnetic resonance imaging evaluations twice in the period 2014 to 2019, allowing >180-day interval. Patients with cnm-positive S. mutans were compared with those without. Quasi-Poisson regression models were used to explore associations between cnm-positive S. mutans and the increase in number of CMB between the 2 magnetic resonance imaging scans. Results: A total of 111 patients were identified; 21 (19%) with cnm-positive S. mutans and 90 (81%) without. Clinical history, including blood pressure and the use of antithrombotic agents, were comparable between the 2 groups. New CMB were more commonly observed in patients with cnm-positive S. mutans (52% versus 23%; P=0.008). The incidence of CMB was significantly higher in the group with cnm-positive S. mutans, especially in deep areas, (incidence rate ratios [95% CI], 5.1 [1.9-13.6] for CMB in any brain region; 15.0 [5.4-42.0] for deep CMB), which persisted after adjusting for age, sex, hypertension, and renal impairment (4.7 [1.8-11.9] for CMB in any brain region; 13.9 [4.3-44.5] for deep CMB). Conclusions: This study demonstrates that cnm-positive S. mutans is associated with an increased incidence of CMB. Treatment for cnm-positive S. mutans infection may be a novel microbiota-based therapeutic approach for stroke and cognitive impairment.

Our laboratory previously established spinal motor neurons (MN) from induced-pluripotent stem cells (iPSCs) prepared from both sporadic and familial ALS patients, and successfully recapitulated disease-specific pathophysiological processes. We next searched for effective drugs capable of slowing the progression of ALS using a drug library of 1232 existing compounds and discovered that ropinirole hydrochloride prevented MN death. In December 2018, we started an investigator-initiated clinical trial testing ropinirole hydrochloride extended-release tablets in ALS patients. This is an on-going phase I/IIa randomized, double-blind, placebo-controlled, single-center, open-label continuation clinical trial (UMIN000034954). The primary aim is to assess the safety and tolerability of ropinirole hydrochloride in patients with ALS. We will also perform an efficacy evaluation using patient-derived iPSCs/MN. Major inclusion criteria were as follows: 1) 'clinically possible and laboratory-supported ALS', 'clinically probable ALS' or 'clinically definite ALS', according to the criteria for the diagnosis of ALS (El Escorial revised) and within 60 months after disease onset; 2) change in ALSFRS-R score of -2 to -5 points during the 12-week run-in period. Finally, 15 patients will be assigned to the active drug and 5 patients to the placebo. Our trial will be a touchstone trial for iPSC-based drug development strategies.

Background: Various sensory impairments have been reported in patients with lateral medullary syndrome, also known as Wallenberg syndrome. The typical sensory impairments experienced by patients with this condition are ipsilateral facial and contralateral trunk and limb thermal hypesthesia and hypoalgesia. Tactile (light touch) sensation is not generally diminished. Here we report the case of a 35-year-old man with lateral medullary infarction who had atypical sensory impairment. Methods: We examined the results from the neurological examination of the patient as well as findings from computed tomography of the head and magnetic resonance imaging. Results: Magnetic resonance imaging showed left lateral medullary infarction caused by left posterior inferior cerebellar artery dissection. Neurological examination revealed both tactile and thermal/pain hypesthesia on the left side of the patient's face, and thermal/pain hypesthesia on his right upper and lower limbs. Conclusion: There are two types of tactile sensation: epicritic and protopathic. Facial tactile sensation is usually thought to be associated with epicritic tactile sensation, which travels through principal sensory nuclei of the trigeminal nerve. The protopathic pathway travels down through the spinal tract via the trigeminal nerve and is not considered a primary pathway. However, in this case the protopathic tactile sensation pathway might be involved, and it caused facial tactile hypesthesia. Because most of previous case reports and literature reviews focused only on thermal/pain hypesthesia, we believe that this case provides critical information on the brainstem neuroanatomy, especially for the protopathic tactile sensation pathway in patients with stroke.

Background: Anti-signal recognition particle (SRP) antibodies are used as serological markers of necrotizing myopathy, which is characterized by many necrotic and regenerative muscle fibers without or with minimal inflammatory cell infiltration. The clinical spectrum associated with anti-SRP antibodies seems to be broad. Objective: To describe the clinical characteristics, autoantibodies status, and neurological outcome associated with anti-SRP antibody. Methods: We studied clinical and laboratory findings of 100 patients with inflammatory myopathy and anti-SRP antibodies. Anti-SRP antibodies in serum were detected by the presence of 7S RNA using RNA immunoprecipitation. In addition, enzyme-linked immunosorbent assays (ELISAs) using a 54-kD protein of SRP (SRP54) and 3-hydroxyl-3-methylglutatyl-coenzyme A reductase (HMGCR) were also conducted. Results: The mean onset age of the 61 female and 39 male patients was 51 years (range 4-82 years); duration ≥ 12 months before diagnosis was seen in 23 cases. All patients presented limbs weakness; 63 had severe weakness, 70 neck weakness, 41 dysphagia, and 66 muscle atrophy. Extramuscular symptoms and associated disorders were infrequent. Creatine kinase levels were mostly more than 1000 IU/L. Histological diagnosis showed 84 patients had necrotizing myopathy, and apparent cell infiltration was observed in 16 patients. Anti-SRP54 antibodies were undetectable in 18 serum samples with autoantibodies to 7S RNA. Anti-HMGCR antibodies were positive in 3 patients without the statin treatment, however, were negative in 5 patients with statin-exposure at disease onset. All but 3 patients were treated by corticosteroids and 62 (77 %) of these 81 patients required additional immunotherapy. After 2-years treatment, 22 (27 %) of these 81 patients had poor neurological outcomes with modified Rankin scale scores of 3-5. Multivariate analysis revealed that pediatric disease onset was associated with the poor outcomes. Conclusion: Anti-SRP antibodies are associated with different clinical courses and histological presentations.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that affects millions of patients worldwide. The current disease-modifying therapies (DMTs) that are widely used to treat MS only show modest effects. Because MS is a chronic disease, it is important to develop treatments that have better long-term efficacy. Recently, several new-generation DMTs have been developed, most of which target specific immune molecules based on the assumption that MS is an autoimmune disease. These DMTs are designed to inhibit inflammation that is thought to directly cause demyelination. Preliminary studies suggest that these new therapies are likely to show a greater effect in reducing relapses in early MS patients, although their long-term efficacy is still unknown. In contrast, it was recently reported that the initial course of MS does not significantly influence long-term disability and that disability increases approximately at the same rate despite variable relapse frequencies. Furthermore, new neuropathological evidence now argues against the autoimmune hypothesis and suggests that MS is a primary oligodendrogliopathy disease in which the inflammatory response may be a mere epiphenomenon. So can we be optimistic about the unproven long-term outcomes of new DMTs or should we reconsider the pathogenesis of MS when developing more disease-specific treatments? © 2011 Springer Science+Business Media, LLC.

Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system (CNS); it affect millions of patients worldwide and the number of patients is on the rise. Current treatment options are fairly limited and there is a strong unmet need for disease-targeted therapies for MS. The most widely accepted hypothesis for the pathogenesis of MS is that it is a primary autoimmune disease in which myelin-specific T cells play a central role in the progression of demyelination. According to this hypothesis, a powerful immune suppression or a reconstruction of the immune system to abrogate disease-specific leukocytes early in the development of the disease is expected to halt or even reverse the disease, since remyelination is an exceptionally efficient regenerative process in the CNS. However, recent neuropathological studies have provided evidence of primary oligodendrogliopathy as a cause of demyelination, suggesting that immune reactions may be a mere secondary event in the course of MS. On the other hand, some recent clinical trial results of new immune-suppressive treatments showed a nearly complete blockade of relapses and significant, albeit incomplete, neurological improvement. Therefore, which hypothesis-autoimmunity or oligodendrogliopathy- lights the correct path to a "cure" for MS? © 2010 L. Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw, Poland.

In the CNS oligodendrocytes produce myelin and ensheath individual axons after birth. Demyelination disables saltatory conduction and leads to loss of neural functions. Oligodendrocyte precursor cells (OPCs) are immature and abundant reservoir cells in the adult brain that are capable of differentiating into myelinating oligodendrocytes. Upon demyelination insults, OPCs are spontaneously induced to differentiate in order to remyelinate denuded axons and promote functional recovery. While remyelination is an efficient regenerative process in the CNS, it often fails in the chronic phase of multiple sclerosis (MS). OPCs are nonetheless preserved in many MS lesions, suggesting that arrested OPC differentiation underlies remyelination failure in chronic MS. Understanding the molecular pathology of this arrested differentiation and remyelination failure in chronic MS is critical for developing remyelination medicines that will promote a full functional recovery in these patients. Recently, TIP30 was identified as an inhibitor of OPC differentiation in MS. TIP30 inhibits proper nucleocytoplasmic transport and thus disables nuclear import of transcription factors that are required for differentiation. TIP30 may also increase susceptibility of OPCs to cell death. In this review, we examine the pathophysiological nature of remyelination failure in chronic MS and discuss the role of TIP30 as a novel therapeutic target. © 2009 Informa UK Ltd.

Recent studies of adult neurogenesis of the mammalian central nervous system have suggested unexpected plasticity and complexity of neural cell ontogenesis. Redefinition and reconstitution of cell classification and lineage relationships, especially betweerr glial and neural precursors, are an urgent and crucial concern. In the present study, we describe a new monoclonal antibody, A3B10, which was produced by immunizing mice with the membrane fraction prepared from astrocyteenriched primary neural cell cultures. Immunohistochemistry of brain sections, including brains from glial fibrillary acidic protein (GFAP)-deficient mice and primary mixed neural cell cultures, as well as immunoblot analysis and immunoelectron microscopy, have revealed that 1) A3B10 recognizes a majority of cells in ependyma in neonatal and adult rats, 2) A3B10 stains almost all GFAP+ cells and some S100β+ cells in the corpus callosum, 3) A3B10 specifically stains astrocytes in vitro in primary cultures of rat embryonic cerebral hemispheres, 4) A3B10 equally stains ependymal cells of wild-type and GFAP-deficient mice, and 5) A3B10 antigen might construct intermediate filament bundles with GFAP and/or, vimentin. These data suggested that the antibody labels a wide array of astorcytic-lineage cells including astrocytes, astrocyte precursors, and neural stem cells. Screening a cDNA library derived from rat embryonic brain has revealed that the antibody recognizes calmodulin-regulated spectrin-associated protein 1 (Camsap1). Thus this antibody may provide not only a new marker to identify astrocyte-lineage cells but also a new target molecule to elucidate the ontogeny, development, and pathophysiological functions of astrocyte-lineage cells. © 2008 Wiley-Liss, Inc.

Oligodendrocyte precursor cells (OPCs) persist near the demyelinated axons arising in MS but inefficiently differentiate into oligodendrocytes and remyelinate these axons. The pathogenesis of differentiation failure remains elusive. We initially hypothesized that injured axons fail to present Contactin, a positive ligand for the oligodendroglial Notch1 receptor to induce myelination, and thus tracked axoglial Contactin/Notch1 signaling in situ, using immunohistochemistry in brain tissue from MS patients containing chronic demyelinated lesions. Instead, we found that Contactin was saturated on demyelinated axons, Notch1-positive OPCs accumulated in Contactin-positive lesions, and the receptor was engaged, as demonstrated by cleavage to Notch1-intracellular domain (NICD). However, nuclear translocalization of NICD, required for myelinogenesis, was virtually absent in these cells. NICD and related proteins carrying nuclear localization signals were associated with the nuclear transporter Importin but were trapped in the cytoplasm. Abnormal expression of TIP30, a direct inhibitor of Importin, was observed in these OPCs. Overexpression of TIP30 in a rat OPC cell line resulted in cytoplasmic entrapment of NICD and arrest of differentiation upon stimulation with Contactin-Fc. Our results suggest that extracellular inhibitory factors as well as an intrinsic nucleocytoplasmic transport blockade within OPCs may be involved in the pathogenesis of remyelination failure in MS.

Post-transplant lymphoproliferative disorder (PTLD) is a complication that can develop after either solid-organ or hematopoietic stem cell transplantation (HSCT). T-cell PTLD is a rare disorder, especially following autologous HSCT. Here we report a case of T-cell PTLD which occurred after autologous peripheral blood stem cell transplantation (PBSCT) for relapsed angioimmunoblastic T-cell lymphoma (AILT). Three months after the transplant, the patient developed fever with elevated plasma Epstein-Barr virus (EBV)-PCR values. The patient subsequently developed pneumonitis, hepatomegaly and marked pancytopenia due to hemophagocytosis. The patient died of multi-organ failure, despite antiviral and steroid pulse therapy. Our post-mortem study confirmed the marked proliferation of EBV-infected T-cells that differed from the original AILT clone and macrophages/histiocytes were observed in the marrow, liver, lymph nodes and lungs. Phagocytosis was most evident in the bone marrow. The patient's AILT remained in complete remission. To the best of our knowledge, this is the first case of fulminant EBV-associated T-cell lymphoproliferative disorder (LPD) following autologous HSCT. © 2005 Elsevier Ltd. All rights reserved.

The capacity for spontaneous remyelination in cases of multiple sclerosis (MS) is limited and lesions are not fully repaired. Recent evidence has shown that oligodendrocyte precursor cells and immature oligodendrocytes (OPC/iOligs) are preserved in MS lesions. Induced differentiation of these cells into myelinating cells may ultimately lead to a novel remyelination therapy. A previous study showed that the γ chain of immunoglobulin Fc receptors (FcRγ), expressed in OPC/iOligs, is essential for their differentiation. Whether FcRγ is expressed in preserved OPC/iOligs within MS lesions, however, remains uncertain. In the present study, we examined 10 autopsy cases of MS for the expression of FcRγ both in remyelinating areas and demyelinated plaques. The expression of FcRγ was confirmed in both OPC/iOligs and microglia in MS lesions. Statistical analysis showed that the density of FcRγ-positive OPC/iOligs was approximately 3 times greater in remyelinating areas compared with demyelinated plaques; the opposite was true of FcRγ-positive microglia. The distribution of FcRγ-negative OPC/iOligs did not differ between the 2 types of lesions. Thus, an increase in FcRγ-positive OPC/iOligs and a decrease in FcRγ-positive microglia, but not in FcRγ-negative OPC/iOligs, are associated with spontaneous remyelination in MS brains, suggesting a possible role for FcRγ in the induction of remyelination. Copyright © 2006 by the American Association of Neuropathologists, Inc.

Around a half of multiple sclerosis (MS) patients suffer from cognitive impairment such as attention deficit. A similar impairment is already observable in one third of patients with clinical isolated syndrome, suggesting that the symptom cannot be solely explained by the accumulation of demyelinated lesions. Recently, several studies indicated that demyelination and atrophy in specific regions of the brain are related to the cognitive impairment, although those patients with brain and cognitive reserves are resistant to the development of such symptom. Aging, male sex and smoking increases whereas certain disease-modifying therapy decreases the risk of cognitive impairment in MS. Together, the development of cognitive impairment in MS appears to be determined by the balance between specific aggravating and protective factors.