Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system (CNS). This disease is characterized by so-called "multiplicity in time and space in the CNS". Although the pathomechanisms of MS have been extensively studied for a long time, the etiology is still unknown. It has been pointed out that the prevalence rate of MS is very low, and that the optic spinal form of MS (OSMS), which mainly affects the optic nerves and spinal cord, is common in Japan. There has been a long controversy as to the differences between OSMS and neuromyelitis optica (NMO), and whether NMO or OSMS is a subtype of multiple sclerosis (MS) or a distinct disease. Recently, a highly disease specific autoantibody, NMO-IgG, was found in the sera of patients with NMO as well as OSMS. However, this antibody was not detected in the sera of MS patients. Therefore, we conclude that OSMS is the same as NMO, and speculate that NMO/OSMS may be a distinct disease from MS. Many investigations have revealed several differences clinically and pathologically between MS and NMO/OSMS. The following features such as female predominance, no brain lesions and longitudinally extended spinal cord lesions by MRI study and neuropathologically necrotic or cavitary lesions are commonly seen in NMO/OSMS. The most recent and important discovery that NMO-IgG reacts specifically with aquaporin 4 (AQP4), which is a water channel localized in astrocytes, opened new avenues for understanding the pathogenesis of NMO/OSMS. We immunocytochemically studied the expression of AQP4 in lesions of postmortem NMO/OSMS, and found that AQP4 was completely lost in the acute lesions. In addition, an astrocytic marker, GFAP, was also lost in the NMO/OSMS lesions. However, the myelin basic protein-stained fibers were relatively preserved. These immunocytochemical features are in contrast to those of MS. In MS, there was no loss of either AQP4 or GFAP expression in the lesions. Moreover, the values of GFAP were markedly increased in CSF from patients with NMO/OSMS in the acute phase but were never increased in patients with MS. These results strongly suggest that astrocytic impairment associated with AQP4 antibody may be mainly involved in NMO, and that the pathogenesis of NMO is distinct from MS, which is primarily a demyelinating disease.
Therapeutic options for patients with progressive multiple sclerosis are currently limited. This is in part due to lack of knowledge regarding the pathophysiology of the disease in this stage. This review summarizes recent findings, showing profound differences in the pathology between relapsing and progressive MS. Pathological hallmarks in progressive MS are slow expansion of pre-existing white matter lesions, massive cortical demyelination and extensive diffuse injury of the normal appearing white matter. As in relapsing MS also in progressive MS active tissue injury is invariably associated with inflammation, but inflammation seems to be trapped behind a closed blood brain barrier. Different immunological mechanisms are involved in tissue destruction in progressive MS, but inflammation induced mitochondrial injury appears to be a dominant pathway. Future therapeutic interventions will have to target inflammation, which is compartmentalized in the central nervous system. In addition, however, neuroprotective therapies may be necessary.
Neurons and glia are characterized by their well formed processes and by cell-to-cell relationships. Neurons show cylindrical processes, which form synaptic junctions. On the other hand, the peripheral parts of the glial cells are sheet-like in nature. Thus, the oligodendroglial cells form shovel-shaped myelin sheets around axons. The astrocytes also form delicate sheet-like processes, which separate the central nervous system from the mesodermal tissue and surround neuronal soma, dendrites and synapses. Fine structural studies in neuropathological material provide many interesting new findings on neuronal and glial processes. This communication highlights my exciting experience studying neuropathology for over 50 years.
In the last nineteenth century, Japan produced two pioneers in the neurological field. Perhaps Prof. Hiroshi Kawahara's most monumental contribution was the first publication of the textbook of neurology in Japan. He first reported the two-brother cases of bulbar and spinal muscular atrophy of X-linked recessive trait. Kinnosuke Miura, the professor of the University of Tokyo, described the endemic disease of the "kubisagari" (head-dropping). He published a paper of clinical and pathological study on amyotrophic lateral sclerosis. In 1902, Miura founded the "Japanese Society of Neurology" together with Shuzo Kure, the professor of Psychiatry of the University of Tokyo. This Society underwent a metamorphosis to an organization mainly composed of psychiatrists, because of a steady increase in membership of psychiatrists. In the mid-nineteenth century, neurological activities were restricted within the departments of internal medicine, psychiatry or neurosurgery. After the end of World War II, neurology came to receive recognition of the identity. In 1960, Seizo Katsunuma, the professor of Nagoya University, and Shigeo Okinaka, the professor of the University of Tokyo, started anew "the Japanese Society of Neurology", which was independent of the former Society founded in 1902. In this paper, the outlines of the history and development of the former and the present Japanese Societies of Neurology for these one hundred years are presented.
The Japanese Society of Neurology, founded in 1960, suffered an initial set back internationally primarily because of the language barrier. It gained a quick, and justifiable recognition after the 12th World Congress of Neurology held in Kyoto (1981), and now enjoys an indisputable reputation in the field of neuroscience. Clinical neurophysiology lead the world from the inception with the early formation of study group in 1951 as the predecessor of the current Japanese Society of Clinical Neurophysiology. In both fields, however, clinical training has fallen behind research achievements with limited resources and a shortage of teaching staff. On the occasion of 50th anniversary of our society, we must seek the sovereignty of neurology as an independent discipline as advocated by the World Federation of Neurology. We must also participate in global affairs with confidence despite a perceived language barrier to promote neurology world wide.
Japanese Society of Neurology (JSN) was established in 1960 with 643 members, and in 2009 it has grown up to a big society having more than 8,000 members including 3,600 neurology board specialists. JSN has greatly contributed in elucidating and resolving many socio-medical problems. I will take three topics including SMON (subacute myelo-optico-neuropathy), infectious Creutzfeldt-Jakob disease (CJD) and Minamata disease. SMON was a new epidemic disease characterized by subacute optic neuritis and myeloneuropathy associated with diarrhea and abdominal symptoms. The research committee clarified that it was a neurological complication of chinoform, a drug for gastroenteritis. CJD surveillance started in 1996 for variant CJD, and uncovered many patients who developed CJD after human dura draft. The government prohibited to use non-inactivated human dura. Minamata disease is an organic mercury poisoning of people who took fish contaminated by mercury in Minamata bay in Kumamoto or in Aganogawa river in Niigata. The factories discharged water contaminated with mercury which was accumulated in fish and shellfish. Still many victims claim for compensation to the companies and government. Neurologists in Kumamoto and Niigata greatly contributed to diagnose and treat the victims and to clarify the cause of the disease.
In accordance with recent ever increasing numbers in elder population in Japan, number of patients of age-related neurological diseases such as stroke, dementia and neurodegenerative diseases, etc., also remarkably increasing. Naturally, social needs for medical intervention in neurological fields inevitably become indispensable. The role of the neurologists, especially specialists of neurology, must be substantially important in the near future. The Japanese Society of Neurology has already launched the system for quality-certified specialists for neurology in 1970's. The aim of the system to educate and certify specialists for neurology has been announced as follows; the specialist of neurology must widely experienced and practiced in clinical fields, and must properly diagnose and judge the neurological illness even they are so complicate and difficult to manage (Rinsho Shinkeigaku (Clinical Neurology) 38 (6): 593-619, 1998). However, in future, the specialists for neurology must cultivate and keep the minds of "Professionalism" of physicians as well as their skills for clinical neurology. The Professionalism consists of altruism, accountability, excellence, duty, honor and integrity, respect and a personal commitment to life-long learning (ABIM: American Board of Internal Medicine, Project Professionalism, 1990-). The specialists of neurology with recent privilege in clinical insurance system for their special ability and techniques for neurological examination, should not only share their clinical specialty but also provide their opinion based upon Professionalism to all over the world.
Neurodegenerative diseases have been construed as incurable disorders. However, therapeutic development for these diseases is now facing a turning point: analyses of cellular and animal models have provided insights into pathogenesis of neurodegenerative diseases, and have indicated rational therapeutic approaches to them. Therefore, how to realize molecular targeted therapy for neurodegenerative diseases is becoming one of the most challenging issues in the clinical neurology. Primarily, pathophysiological understanding of the disease from basic science is the first step. For the successful clinical trials, effective trial design, sufficient economic and social support, and education are indispensable. The development of androgen deprivation therapy for spinal and bulbar muscular atrophy (SBMA) is a representative study in this field. SBMA is a hereditary neurodegenerative disease caused by expansion of a trinucleotide CAG repeat in the first exon of the androgen receptor (AR) gene. There is increasing evidence that testosterone, the ligand of AR, plays a pivotal role in the neurodegeneration in SBMA. The striking success of androgen deprivation therapy in SBMA mouse models has been translated into phase 2, and then phase 3, clinical trials.
Recent advance of molecular biology reveals that quality control of intracellular environment takes an important role for maintaining the neuronal function. One is a quality control of protein and another is a quality control of nucleotide. Polyglutamine disease is a disease which caused by a failure of quality control of protein. Expanded polyglutamine repeats result in neurodegenerative disorders, but their cytotoxic structures remain to be elucidated. About the quality control of nucleotide in neuron, DNA single-strand breaks (SSBs) were continually produced by endogenous reactive oxygen species or exogenous genotoxic agents. These damaged ends posses damaged 3'-ends including 3'-phosphate, 3'-phosphoglycolate, or 3'-α, β-unsaturated aldehyde ends, and should be restored to 3'-hydroxyl ends for subsequent repair processes. We have demonstrated by in vitro assay that aprataxin, the causative gene product for early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia type 1 (EAOH/AOA1), specifically removes 3'-phosphoglycolate and 3'-phosphate ends at DNA 3'-ends, but not 3'-α, β-unsaturated aldehyde ends. The findings indicate that aprataxin removes blocking molecules from 3'-ends, and that the accumulation of unrepaired SSBs with damaged 3'-ends underlies the pathogenesis of EAOH/AOA1. The findings will provide new insight into the mechanism underlying degeneration and DNA repair in neurons.
Currently, four Phase I clinical trials are underway utilizing recombinant adeno-associated viral (rAAV) vectors for the treatment of Parkinson's disease. The vehicle used mainly for gene delivery to the human brain is rAAV vector, which is non-pathogenic and non-self-amplifying. At present, the gene therapy approach is not the best way for the treatment of PD patients, but we believe that the further progress is anticipated toward making this strategy a therapeutic option for PD in the future. This article will review currently ongoing clinical trials of PD gene therapy and then introduce our studies about the gene therapy for PD.
Advancements in medical genetics have increased access to genetic diagnosis in clinical neurology and accompanying genetic counseling. However, its use has not yet spread and the frequency of general biochemistry inspection in medical treatment and by patients remains low. Many problems remain for doctors, though socio-cultural and other various causes exist. Thus, a network of care specialists for inherited and incurable neurological diseases has been established, consisting of multi-occupational categories in medical treatment, health, and welfare such as clinical inheritance specialists, psychiatrists, public health nurses, and medical social workers, to meet the rise in availability of such methods. Businesses in areas such as training, consultation, and field research have arisen. An educational campaign for neurologists who have taken a central role in treatment of inherited and incurable neurological diseases, and related information have been disseminated to those working in fields related to regional welfare of neurological medicine, and patients are now supported totally by team and regional counseling. These new developments in support systems for inherited and incurable neurological diseases, have steadily achieved the respective goals. We aim to promote its evolution to a more advanced network to promote the independence of individual patients in the future.
The task force of the international league against epilepsy (ILAE) proposed the "Diagnostic scheme for people with epileptic seizures and epilepsy" in 2001. The 2001 diagnostic scheme was updated in 2006. The ILAE Core Group recommended the new classification to replace the previous one (ILAE, 1981, 1989). However, the new classification is too complex to use for clinicians except expert epileptologists. About 10 new antiepileptic drugs are launched recently. Among them, gabapentine, topiramate, and lamotrigine have been approved in Japan as adjunctive therapy for medically intractable seizures. The advantage of the new antiepileptic drugs includes newer mechanism of action, broad spectrum of anti-seizure effects, fewer side effects, and lesser drug interactions. The rational polytherapy is necessary for refractory epilepsy. The majority of elderly patients with new onset epilepsy become seizure free on antiepileptic monotherapy, often with modest dose. We are now in the new era of epilepsy treatment.
Recently a new category of treatment-responsive encephalitis has been proposed associated with antibodies against neuronal cell membrane antigens, including VGKC, NMDA receptor (NMDAR) and AMPA receptor. Anti-NMDAR encephalitis is caused by the antibodies, which bind to extracellular conformal epitope in the NR1/NR2 heteromers of the NMDAR. The antibodies are usually detected in CSF/serum of young women with ovarian teratoma (OT), who typically developed schizophrenia-like psychiatric symptoms. Most patients developed seizures, followed by unresponsive/catatonic state, central hypoventilation, and bizarre orofacial-limb dyskinesias. Based on symptomatology and current NMDAR hypofunction hypothesis in schizophrenia, we speculated that the antibodies might cause inhibition of NMDAR in presynaptic GABAergic interneurons, causing a reduction of release of GABA. This results in disinhibition of postsynaptic glutamatergic transmission, excessive release of glutamate in the prefrontal/subcortical structures, and glutamate/dopamine dysregulation. Recent studies demonstrated that the antibodies cause reversible reduction in the numbers of cell-surface NMDAR and NMDAR clusters in postsynaptic dendrites, suggesting antibodies-mediated decreased function of NMDAR. Early tumor resection with immunotherapy is recommended in OT-positive cases but not in OT-negative cases. However, exploratory laparotomy may increase the chance to identify microscopic teratoma and improve the outcome if patients who were refractory to immunotherapy had anti-NMDAR antibodies and ovarian cyst.
Neuropathic pain is a debilitating pain that occurs after nerve injury and is generally resistant to currently available treatments including morphine. Such pain involves aberrant excitability in dorsal horn neurons after nerve injury. Emerging evidence indicate that the enhanced activity of dorsal horn neurons requires a communication with microglia. Results of our laboratory have shown that activating P2X4R upregulated in spinal microglia after nerve injury contributes to neuropathic pain through a release of BDNF from microglia, which is a crucial factor to signal to dorsal horn neurons to cause neuronal hyperexcitability. Activated spinal microglia also express P2Y12R, and P2Y12R-KO mice display impaired neuropathic pain. The mechanisms of microglia activation are unknown, but our recent study shows that interferon-γ (IFN-γ) can be an important factor that causes spinal microglia activation after nerve injury. IFN-γ upregulates P2X4R in microglia and causes P2X4R-dependent allodynia. These findings suggest that purinoceptors in spinal microglia is crucial for pathological intractable pain.
The TDP-43 proteinopathies: Toward understanding of the molecular pathogenesis. TAR DNA binding protein of 43kDa(TDP-43), a heterogeneous nuclear ribonucleoprotein was identified as a major component of ubiquitin-positive inclusions in FTLD and ALS, and the concept of TDP-43 proteinopathies was proposed. Immunoblot and immunohistochemical analyses using multiple anti-phosphorylated TDP-43 antibodies revealed that hyperphosphorylated 18-26kDa C-terminal fragments in addition to the full-length TDP-43 are major constituents of inclusions in FTLD-U and ALS. Recent discovery of mutations in the TDP-43 gene in familial and sporadic ALS, indicating that abnormality of TDP-43 protein cause neurodegeneration. It also strongly suggests that aggregation of TDP-43 or the process is responsible for neurodegeneration in FTLD-U and ALS. To investigate the molecular mechanisms of aggregation of TDP-43, we have established two cellular models for intracellular aggregates of TDP-43 similar to those in brains of TDP-43 proteinopathies patients. The first consists of SH-SY5Y cells expressing mutant TDP-43 that lacks both the nuclear localization signal (NLS) and residues 187-192 (ΔNLS & 187-192). The second model consists of SH-SY5Y cells expressing an aggregation-prone TDP-43 C-terminal fragment as a green fluorescent protein (GFP)-fusion. In these cells, round structures positive for both anti-pS409/410 and anti-Ub are observed. These results suggest that intracellular localization of TDP-43, truncation of TDP-43 and proteasomal dysfunction of cells may be involved in the pathological process of TDP-43 proteinopathies. We also found that two small compounds that have been reported to be beneficial in phase II clinical trials of Alzheimer's disease, inhibited the formation of TDP-43 aggregates in these two cellular models, suggesting that these compounds may be effective for the treatment of ALS and FTLD-U.
Discovery of aquaporin water channel proteins has provided insight into the molecular mechanism of membrane water permeability. In mammalian brain, Aquaporin-4 (AQP4) is the main water channel and is distributed with highest density in the perivascular and subpial astrocyte end-feet. AQP4 is a critical component of an integrated water and potassium homeostasis. Indeed, AQP4 has been implicated in several neurologic conditions, such as brain edema, seizure and even mood disorders. Expression and regulation of AQP4 have been studied to understand the roles of AQP4 in physiological and pathological conditions. Here we discuss about the mechanisms how AQP4 is dynamically regulated at different levels; channel gating, subcellular distribution, phosphorylation, protein-protein interactions and orthogonal array formation. Interestingly, AQP4 has been identified as a target antigen of autoimmune attack in neuromyelitis optica (NMO). We have evaluated putative epitopes on AQP4 for NMO-IgG binding. We have also studied Drosophila Big Brain (Bib), since Bib has high sequence homology to AQP-4, and play an important role for Drosophila neurogenesis. AQP4 may be a potential therapeutic target in several neurologic conditions. Further studies from different aspects are required to develop new drugs against AQP4.
Autoantibodies impair acetylcholine receptor (AChR) in myasthenia gravis (MG) and P/Q-type voltage-gated calcium channel (VGCC) in Lambert-Eaton myasthenic syndrome (LEMS). (1) Some of MG and LEMS patients are "seronegative" for respective antibodies or modified by antibodies that recognize other proteins than AChR and VGCC such as MuSK, AChR allosteric site, membrane Na+ channel and ryanodine receptor-1 (RyR1) in MG, and synaptotagmin-1 in LEMS. (2) Autoimmune responses affect the proteins participating in the mechanisms to compensate for synaptic disorders on the basis of presynaptic Ca2+ homeostasis provided by VGCC and non-VGCC (receptor-operated TRPCs); they act as enhancers of Ca2+-mediated ACh release via phospholipase C signaling pathways including M1-type presynaptic muscarinic AChR, neurotrophin receptor (TrkB), and fast-mode of synaptic vesicle recycling. (3) The pathophysiology contributive to contractile fatigue in MG includes RyR1 and also TRPC3. The TRPC3 also forms a complex with STIM1 and Orai1 to make up for Ca2+ after sarcoplasmic Ca2+ release. The prevalent detection of anti-TRPC3 antibodies in MG with thymoma could affect muscle contractile machineries in addition to anti-RyR1-induced affection. (4) When one faces "seronegative" MG, one should be cautious to conformation-specific antibodies and also congenital myasthenic syndromes.
Conscious awareness is the state in which external and internal stimuli are perceived and can be intentionally acted on. Although various investigations have provided new insights into the neural mechanisms of conscious awareness, its whole network in human remains to be solved. Anosognosia for visual dysfunction and unconscious processing of visual stimuli are good examples of dissociation between cognitive processes and conscious awareness. Anton syndrome, anosognosia for blind or deaf, could be observed in blindness caused by cerebral as well as ophthalmological diseases, when general cognitive function or attention is impaired. Unawareness of hemianopia is not an exception but a common phenomenon, which seems to be related to a completion phenomenon and macular sparing. Patients with visual agnosia are not consciously aware of the nature of their visual dysfunction but have a vague feeling of visual impairment. Blindsight, unconscious visual processing in the blind field, might be partly related to the dorso-dorsal visual stream that takes roles in the control of actions "on line" without awareness of spatial perception. In patients with unilateral spatial neglect, unconscious processing of visual stimuli on the neglected space was also observed. Better understanding of neural mechanisms of conscious awareness would provide insights into various neurological disorders and therapeutic approaches.
For thrombus formation, three important factors, blood flow, blood component and blood vessels, have been recognized as Virchow's triad. In cardiogenic embolism with atrial fibrillation, stagnation of blood in the left atrium causes fibrin-rich thrombus. Anticoagulation is the only effective drug for prevention of this type of thrombus. In atherothrombotic and lacunar infarction, injury of endothelium and arterial vessels and platelet play a crucial role of formation of platelet-rich thrombus. Antiplatelet drugs such as aspirin, clopidogrel and cilostazole are effective for prevention of arterial thrombus and stroke recurrence, but other drugs such as statin for plaque stabilization and improvement of endothelial function could be used to reduce the recurrence of ischemic stroke.
After the success of the 1995 National Institutes of Neurological Disorders and Stroke (NINDS) study using intravenous (IV) recombinant tissue plasminogen activator (rt-PA, alteplase) within 3 hours in acute stroke, this therapy was approved worldwide and has been a standard therapy for acute stroke patients. In Japan, IV alteplase at a dose of 0.6mg/kg was approved in 2005 after a multicenter study using this low dose of alteplase (Japan Alteplase Clinical Trial [J-ACT]). IV rt-PA can drastically improve stroke outcomes. However, more than half of treated patients are not independent in the chronic stage. In addition, the therapeutic time window was so limited that many stroke patients do not have a chance to receive the therapy. In 2008, European Cooperative Acute Stroke Study III showed that IV rt-PA administered between 3 and 4.5 hours after stroke onset significantly improved clinical outcomes in stroke patients; the success resulted in the renewal of recommendation in guidelines in Europe, Canada, and the United States. Several therapeutic strategies, including endovascular therapy, sonothrombolysis, and neuroprotective therapy, may improve the efficacy of IV rt-PA.
Transcranial ultrasonic diagnostic equipment has been approved to enhance the thrombolytic effect of IVrt-PA. Moreover, transcranial sonothrombolysis with low frequency ultrasound has a great advantage in lytic effect of IVrt-PA. It is remarkable to choose a optimal ultrasonic condition for transcranial sonothrombolysis. We are developing a new transcranial targeting Low Frequency Ultrasonic Thrombolysis system (TCT-LoFUT). This system is anticipated to be a useful therapeutic equipment to realize a early recanalization in the acute ischemic stroke treatment.
The mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) remain poorly understood even now 140 years after the first description of the disease in 1869 by Jean-Martin Charcot. Exploration of pathogenesis of ALS has long been dependent on transgenic animal models with mutations in the copper/zinc superoxide dismutase 1 (SOD1) gene. However, the lack of therapeutic concordance between these animal models and human sporadic ALS patients is troubling. The reasons include that there might exist the differences of pathogenesis between sporadic and familial ALS and/or the disease models for sporadic ALS have not bee established. We have been working on screening motor neuron-specific genes critical for pathogenesis of sporadic ALS using cDNA microarray and laser capture microdissection techniques. Many of the resultant genes are of intense interest and may provide a powerful tool for determining the molecular mechanisms of sporadic ALS. In particular, dynactin-1, a major component of dynein/dynactin complex and several cell cycle-related genes are the targets of our research. Development and analysis of new disease models for sporadic ALS based on these genes will open an avenue for novel therapeutics.
Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disorder characterized by the death of upper and lower motor neurons. Approximately 20% of familial ALS cases are caused by mutations in the superoxide dismutase 1 (SOD1) gene. Mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene have been recently discovered to be associated with familial ALS. We found FUS/TLS mutations in familial ALS cases in Japan. Even in Asian races, ALS with FUS/TLS mutations may have common characteristics of early onset, rapid progress, high penerence trait. We developed rats that express a human SOD1 transgene with two different ALS-associated mutations (G93A and H46R) develop striking motor neuron degeneration and paralysis. The larger size of this rat model as compared with the ALS mice will facilitate studies involving manipulations of spinal fluid (implantation of intrathecal catheters for chronic therapeutic studies; CSF sampling) and spinal cord (e.g., direct administration of viral- and cell-mediated therapies). Hepatocyte growth factor (HGF) is one of the most potent survival-promoting factors for motor neurons. To examine its both protective effect on motor neurons and therapeutic potential, we administered human recombinant HGF (hrHGF) by continuous intrathecal delivery to G93A transgenic rats at onset of paralysis for 4 weeks. Intrathecal administration of hrHGF attenuates motor neuron degeneration and prolonged the duration of the disease by 63%. Our results indicated the therapeutic efficacy of continuous intrathecal administration of hrHGF in ALS rats. In addition, HGF is capable of reducing astrocytosis and microglial accumulation, and thus supports the attention of a glial-dependent mechanism of ALS progression. These results should prompt further clinical trials in ALS using continuous intrathecal administration of hrHGF.
Emerging evidence suggests that misfolded proteins in the various neurodegenerative diseases can be targets for immunotherapy including vaccination antibody therapy. To date, vaccination strategies have been shown to be effective in Alzheimer's disease, Parkinson's disease, Huntington's disease and Prion disease. Interestingly, the subcellular localization of the target proteins varies, including cytosol, synaptosomes and extracellular spaces. We have documented that mutant SOD1 is secreted together with a neurosecretory protein chromogranin, and that vaccination against the SOD1 mutant is beneficial in delaying the onset and prolonging the lifespan. However, the mechanism of vaccination on the mutant SOD1 mice remains unclear. Moreover, vaccination induces diverse inflammatory reactions, which are reported to modify both the onset and the progression of ALS. Therefore, it is important to clarify the role of innate or acquired immunity in the pathogenesis of ALS to avoid the adverse reactions of the vaccination, and rather to apply it for amelioration. Passive immunization is also promising since only aberrant proteins can be targeted using a specific monoclonal antibody. The development of the current immunization techniques is very important for the future application, since key molecules for the sporadic ALS have emerged and are intensively investigated such as TDP-43.
RNA interference (RNAi) is the process of sequence-specific, post-tanscriptional gene silencing, initiated by double-stranded RNA (dsRNA). The gene therapy for familial ALS with siRNA had been started and showed promising results in the model mouse. There is a recent progress in the delivery of siRNA to the central nervous system. There are still important problems for application of gene therapy including off-target effect and gene delivery of siRNA, but a rapid progress can be expected because of the extremely high efficiency of siRNA.
Induced pluripotent stem (iPS) cells are pluripotent stem cells directly reprogrammed from cultured mouse fibroblast by introducing Oct3/4, Sox2, c-Myc, and Klf4. Cells obtained using this technology, which allows the ethical issues and immunological rejection associated with embryonic stem (ES) cells to be avoided, might be a clinically useful source for cell replacement therapies. We found that secondary neurospheres (SNSs) generated from various mouse iPS cell showed their neural differentiation capacity and teratoma formation after transplantation into the brain of immunodeficient NOD/SCID mice. We found that origin (source of somatic cells) of the iPS cells are the crucial determinant for the potential tumorigenicity of iPS-derived neural stem/progenitor cells and that their tumorigenicity results from the persistent presence of undifferentiated cells within the SNSs. Surprisingly, SNSs derived from c-Myc minus iPS cells generated without drug selection showed robust tumorigenesis, in spite of their potential to contribute adult chimeric mice without tumor formation. Furthermore, we examined whether the transplantation of non-tumorigenic Nanog-iPS-derived SNSs into mouse spinal cord injury (SCI) model could promote locomotor function recovery. As a result, we found that properly pre-evaluated iPS clone-derived neural stem/progenitor cells may be a promising cell source for future transplantation therapy of SCI.
The central nervous system (CNS) injury causes severe loss of functions, and the development of therapies to recover the functions can be an important target. The present study highlighted the preservation-oriented therapy by transferring genes to the injured neurons. To identify therapeutic targets for the preservative therapies of injured CNS, we focused on clarifying the mechanism underlying the degeneration and regeneration of neurons after injuries using nerve injury models of animals. We have identified several genes, some of which were the survive-promoting and others were death-promoting molecules. In addition another subset of genes were assumed to be associated with promoting nerve regeneration. The single expression of variety of molecules by a viral vector was proved to have the potential to rescue and recover, and this was also confirmed in CNS injury model. We assumed that the most important issue was the balance of levels between the pro-survive and pro-death molecules, which expressed in response to nerve injury. Those suggest that variety of molecules could be a therapeutic target for neurodegenerative disease as well as the neuron protection after traumatic injury. Combining both the transplantation-oriented and the preservation-oriented strategies would give us more potent therapeutic possibilities.
Most of neurons are generated by neural stem cells in the developing brain at the embryonic or neonatal stages. However, recent studies indicate that adult brain also contains neural stem cells that continuously generate new neurons. Neurogenesis can be observed in the adult subventricular zone (SVZ) at the lateral wall of the lateral ventricles of various animal species including primates. Young neurons generated in the SVZ migrate over long distances and mature after they reach their final destinations where they function. In this talk, I will present our recent studies using animal models on the mechanisms of neuronal production, migration and maturation in the adult brain under physiological and pathological conditions, and discuss the possibility of their application into regeneration therapies for ischemic brain diseases.
Embryonic stem (ES) cells are expected as promising donor cells for cell transplantation therapy. For example, mouse or monkey ES cell-derived dopamine (DA) neurons can survive in the brain and relieve Parkinson's disease (PD) symptoms in rat or monkey models. In 2001 and 2003, the results of a double-blind trial of the transplantation of human embryonic DA neurons into patients with PD were reported. These results teach us two things. First, cell transplantation has been clinically proven to be effective as a treatment for PD, although the effects are still far from optimal. Second, several problems remain to be solved, including patient selection, optimal donor cell volume, targeting of injection, immunosuppression, and control of dyskinesia. DA neurons have also been generated from several human ES cell lines. Furthermore, functional recovery of rat PD models after transplantation was observed. One of the major problems in ES cell transplantation is tumor formation, which is caused by a small fraction of undifferentiated ES cells in the graft. So, it is essential for undifferentiated ES cells to be eliminated from the graft for clinical application. These efforts will lead to clinical application of ES cell transplantation to the patients with PD.
The clinical diagnosis of Alzheimer's disease (AD) is occasionally imprecise using consensus criteria for probable AD. Therefore, there is a great need for simple biomarkers that substantially aid early diagnosis and tract disease progression of AD and mild cognitive impairment. Of currently available biomarkers for AD, imaging markers are of particular importance based on their low invasiveness and reproducibility. In vivo detection of brain amyloid burden using positron emission tomography either by PIB or BF-227 would be quite attractive. In Japan, Alzheimer's disease neuroimaging initiatives (ADNI) has been launched in 2008 in accordance with US- and World-Wide ADNI. The paradigm of AD diagnosis and treatment would be shifted from "cognitive-based" to "biomarker-based" framework. The use of ideal biomarkers can remarkably speed up AD drug discovery by providing earliest signals of drug efficacy.
Alzheimer's disease is thought to be "common disease". It is expected that new biological diagnostic marker will be discovered for Alzheimer's disease. There are two roles in diagnostic biomarker for AD.; one is a screening and the other one is to help definite diagnosis for AD. Simple screening method using touch panel type computer (Forgetfulness consultation program) is most useful of screening tools and phosphorylated tau protein in cerebrospinal fluid is highly appreciated as a diagnostic biomarker to help definite diagnosis. Serum WGA binding transferrin in AD is significantly higher than that in controls and high levels of it proceed increased levels of amyloid beta protein. Serum WGA binding transferrin may be useful for early diagnostic biomarker in serum.
Several lines of evidence indicate that the production and deposition of amyloid-β peptides (Aβ) contribute to the etiology of Alzheimer's disease. Inhibition or modulation of γ-secretase, that is a responsible enzyme for the Aβ production, is one of the plausible therapeutics for Alzheimer's disease. However, the γ-secretase is an unusual aspartic protease that cleaves the scissile bond within the transmembrane domain of several membrane protein including APP and Notch receptor. Thus, development of drugs that regulate the production of Aβ without affecting the Notch signaling is now demanding. Extensive drug screening and development allow that some secretase inhibitors and modulators have advanced into late-phase clinical trials, whereas the molecular mechanisms of Notch-sparing effect by these compounds effect still remain unknown. Identification of the molecular targets and mechanisms of these compounds using chemical biological approaches is currently underway. This review focuses on the recent development of inhibitors/modulators and provides a direction for the effective treatment of AD through inhibition/modulation of the γ-secretase activity.
Since AN-1792 vaccine induced autoimmune encephalitis, several pharmaceutical companies are now concentrated in developing antibody therapy in Alzheimer's disease (AD). Each antibody has own characteristics. Thus, it is unpredictable at present which antibody is the most beneficial until we see the result of clinical trials. If disease modifying antibodies were found, they will be widely used for treatment of AD in near future. As a candidate of such antibodies, we have developed TAPIR-like antibody with much higher affinity to Aβ42 than Aβ40, and it effectively deleted senile plaque amyloid and Aβ oligomers without increasing microhemorrhages. Although passive immunization can avoid autoimmune encephalitis, it is expensive and it is not suitable for prevention. Thus, safe vaccines by active immunization would be better. Vaccines that induce Th2 type immune responses such as oral vaccine or per-nasal vaccine would be promising.
Distal myopathy with rimmed vacuoles (DMRV), also called hereditary inclusion body myopathy, is an autosomal recessive disorder caused by homozygous or compound heterozygous missense mutations in GNE which encodes a protein with two enzymatic activities in sialic acid biosynthesis: UDP-GlcNAc 2-epimerase and ManNAc kinase. The disease starts from 15-40 years and is slowly progressive. DMRV preferentially affects tibialis anterior and hamstrings muscles, and has characteristic findings in muscle pathology which include rimmed vacuoles, tubulofilamentous inclusions, deposition of amyloid, and phosphorylated tau. We generated DMRV mice (Gne-/-hGNE D176V-Tg) by crossmating Gne knock-out heterozygous mouse and human GNE p.D176V transgenic mouse. This model mouse recapitulates DMRV clinically, pathologically, and biochemically by developing muscle weakness and atrophy from 21 weeks, amyloid deposition from 31 weeks, and rimmed vacuoles and phosphorylated tau from 41 weeks while having lifelong hyposialylation. We gave three types of GNE metabolites, ManNAc, NeuAc and sialyllactose, to DMRV mice orally from 15 weeks until 55 weeks of age. Sialic acid supplementation almost completely precluded the disease and virtually no sign of DMRV was seen even at 55 weeks of age, indicating that decreased sialic acid is the cause of myopathic phenotype and sialic acid supplementation can prevent the disease process.
Duchenne muscular dystrophy (DMD) is caused by the lack of dystrophin protein at the sarcolemma. Exon skipping by antisense oligonucleotides is a novel method to restore the reading frame of the mutated DMD gene, and rescue dystrophin production. We recently reported that systemic delivery of Morpholino antisense oligonucleotides targeting exon 6 and 8 of the canine DMD gene, efficiently recovered functional dystrophin proteins at the sarcolamma of dystrophic dogs, and improved performance of affected dogs without serious side effects (Yokota et al., Ann Neurol. 65 (6): 667-676, 2009). To optimize therapeutic antisense Morpholinos for more frequent mutations of the DMD gene, we designed antisense Morpholinos targeting exon 51 of the mouse DMD gene, and injected them separately or in combination into the muscles of mdx52 mice, in which exon 52 has been deleted by a gene targeting technique (Araki et al., 1997). We also tried systemic delivery of antisense Morpholino to skip exon 51 in mdx52 mice. It is important to verify the effectiveness and side effects of antisense Morpholino in experimental animal models such as dystrophic dogs or mdx52 mice, before clinical trials in DMD patients.
Hypoglycosylation and reduced laminin-binding activity of α-dystroglycan are common characteristics of dystroglycanopathy, which is a group of congenital and limb-girdle muscular dystrophies. We previously identified the genes for Fukuyama congenital muscular dystrophy (FCMD) and muscle-eye-brain disease (MEB). FCMD, caused by a mutation in the fukutin gene, is a severe form of dystroglycanopathy. Knock-in mice carrying the founder retrotransposal insertion exhibited hypoglycosylated α-dystroglycan; however, no signs of muscular dystrophy were observed. More sensitive methods detected minor levels of intact α-dystroglycan, and solid-phase assays determined laminin binding levels to be approximately 50% of normal. In contrast, intact α-dystroglycan is undetectable in the dystrophic Large mouse, and laminin-binding activity is markedly reduced. These data indicate that a small amount of intact α-dystroglycan is sufficient to maintain muscle cell integrity in knock-in mice, suggesting that the treatment of dystroglycanopathies might not require the full recovery of glycosylation. Transfer of fukutin into knock-in mice restored glycosylation of α-dystroglycan. Transfer of LARGE produced laminin-binding forms of α-dystroglycan in both knock-in mice and the POMGnT1 mutant mouse. These data suggest that even partial restoration of α-dystroglycan glycosylation and laminin-binding activity by replacing or augmenting glycosylation-related genes might effectively deter dystroglycanopathy progression and thus provide therapeutic benefits.
About 20 years have passed since the discovery of the causative protein of Duchenne muscular dystrophy, in 1987, and treatments targeting causative factors such as exon skipping, read-through of stop codons, and the upregulation of utrophin are approaching practical levels. In Japan, also, clinical trials are planned as the final stage of treatment development. In this field, an appropriate outcome measure has not been established due to the lack of experience in clinical trials. Treatments for muscular dystrophy are deemed effective only when increases in the muscle mass and muscle strength and improvements in the ADL and QOL as well as biological marker levels at target points have been demonstrated. The Muscular Dystrophy Clinical Study Group has addressed the development of these evaluation methods since 2002. Also, as treatments for muscular dystrophy being developed today are so-called tailor-made treatments aimed at specific mutations, a system that facilitates identification of the type and site of mutation in each individual must be prepared. The Gene Analysis Center was only just established in the National Center of Neurology and Psychiatry in 2009. Also, it is expected to be difficult to secure a sufficient number of subjects to start a clinical trial in a short period. Therefore, the Registry of Muscular Dystrophy (REMUDY), a system for the registration of patients with muscular dystrophy including their clinical and genetic information was implemented. This system, which provides information concerning the number of patients required by the protocol to researchers and pharmaceutical companies and the latest information regarding the development of treatments to patients, is expected to serve as a prototype for the establishment of the basis of clinical trials against rare diseases.
It is the case of the great difficulties for patients living with neurological intractable diseases to visit outpatient when the diseases are in the progressive stage. The national nursing care insurance was matured and the revised medical insurance system led to open the local supportive clinic for home care in 2006. It has set easier access to medical care at home. This is encouraging for patients who wish to continue to live with their families at their long time home. The medical care at home is where the attending physician has to demonstrate the expertise of how to assemble in- and out- interdisciplinary medical team. Moving a hospital room simply into at home does not made a medical care at home. You have to begin recognizing what gaps needed to fill in between a hospital room and at home. This is the area beyond what a family doctor single-handedly deals with due to the nature of the diseases. The dual attending physician set-up is desirable including a family doctor and a specialist.