Hisae Sumi

Benefit of valproic acid in suppressing disease progression of ALS model mice.

Valproic acid (VPA) has long been used as an antiepileptic drug and recently as a mood stabilizer, and evidence is increasing that VPA exerts neuroprotective effects through changes in a variety of intracellular signalling pathways including upregulation of Bcl‐2 protein with an antiapoptotic property and inhibiting glycogen synthase kinase 3‐β, which is considered to promote cell survival. Although the neuroprotective effects of VPA have been demonstrated in a murine model of human immunodeficiency virus‐1 encephalitis, there have been no reports on the effect of VPA in chronic progressing neurodegenerative disease models including amyotrophic lateral sclerosis (ALS). ALS is a devastating disease selectively affecting motoneurons, and its disease model mice bear a close resemblance to ALS symptomatically and pathologically. First, we used an organotypic slice culture using mouse spinal cord, and showed that VPA protected spinal motoneurons against death from glutamate toxicity in vitro. Then, we treated ALS model mice with VPA at the dose effective level for epileptic model mice after 45 days of age (pre‐onset treatment) or the day of the disease onset (post‐onset treatment). We found a significant prolongation of the disease duration in ALS model mice in both methods of treatment. Considering the long usage of VPA for epileptic patients with good tolerance and safety, these data strongly support the clinical application of VPA for ALS treatment.

Neuroaxonal Dystrophy Caused by Group VIA Phospholipase A2 Deficiency in Mice: A Model of Human Neurodegenerative Disease

Calcium-independent group VIA phospholipase A2 (iPLA2β) is considered to play a role in signal transduction and maintenance of homeostasis or remodeling of membrane phospholipids. A role of iPLA2β has been suggested in various physiological and pathological processes, including immunity, chemotaxis, and cell death, but the details remain unclear. Accordingly, we investigated mice with targeted disruption of the iPLA2β gene. iPLA2β−/− mice developed normally and grew to maturity, but all showed evidence of severe motor dysfunction, including a hindlimb clasping reflex during tail suspension, abnormal gait, and poor performance in the hanging wire grip test. Neuropathological examination of the nervous system revealed widespread degeneration of axons and/or synapses, accompanied by the presence of numerous spheroids (swollen axons) and vacuoles. These findings provide evidence that impairment of iPLA2β causes neuroaxonal degeneration, and indicate that the iPLA2β−/− mouse is an appropriate animal model of human neurodegenerative diseases associated with mutations of the iPLA2β gene, such as infantile neuroaxonal dystrophy and neurodegeneration with brain iron accumulation.

Reduction of metallothioneins promotes the disease expression of familial amyotrophic lateral sclerosis mice in a dose-dependent manner.

We previously reported that abnormal copper release from mutated Cu, Zn‐superoxide dismutase (SOD1) proteins might be a common toxic gain‐of‐function in the pathogenesis of familial amyotrophic lateral sclerosis (FALS) [Ogawa et al. (1997) Biochem. Biophys. Res. Commun., 241, 251–257.]. In the present study, we first examined metallothioneins (MTs), known to bind copper ions and decrease oxidative toxicity, and found a twofold increase in MTs in the spinal cord of the SOD1 transgenic mice with a FALS‐linked mutation (G93A), but not in the spinal cord of wild‐type SOD1 transgenic mice. We then investigated whether the clinical course of FALS mice could be modified by the reduced expression of MTs, by crossing the FALS mice with MT‐I‐ and MT‐II‐deficient mice. FALS mice clearly reached the onset of clinical signs and death significantly earlier in response to the reduction of protein expression. These results indicated that the copper‐mediated free radical generation derived from mutant SOD1 might be related to the degeneration of motor neurons in FALS and that MTs might play a protective role against the expression of the disease.

Nuclear TAR DNA Binding Protein 43 Expression in Spinal Cord Neurons Correlates With the Clinical Course in Amyotrophic Lateral Sclerosis

TAR DNA binding protein 43 (TDP-43) has been considered a signature protein in frontotemporal dementia and amyotrophic lateral sclerosis (ALS), but not in ALS associated with the superoxide dismutase 1 (SOD1) gene mutations (ALS1). To clarify how TDP may be involved in ALS pathogenesis, clinical and pathological features in cases of sporadic ALS ([SALS] n = 18) and ALS1 (n = 6) were analyzed. In SALS patients with rapid clinical courses, TDP mislocalization (i.e. cytoplasmic staining and TDP-positive cytoplasmic inclusions) in anterior horn cells was frequent. In SALS patients with slow clinical courses, TDP-43 mislocalization was rare. In an ALS1 patient with the SOD1 gene mutation C111Y, there were numerous TDP-positive inclusions and colocalization of SOD1 and TDP. In mutant SOD1 transgenic (G93A) mice at the end stage (median, 256 days), TDP-positive inclusions and TDP colocalization with SOD1 were also observed; nuclear TDP-43 immunoreactivity was highly correlated with life span in these mice. In both humans and mice, nuclei that stained strongly for TDP were large and circular; weakly stained nuclei were atrophic or deformed. In conclusion, low levels of TDP expression in the nucleus cor relate with a rapid clinical course in SALS and in ALS1 model mice, suggesting that nuclear TDP may play a protective role against motor neuron death resulting from different underlying etiologies.

Loss of dopaminergic neurons by the induction of inducible nitric oxide synthase and cyclooxygenase-2 via CD40: Relevance to Parkinson's disease

A glial reaction associated with up‐regulation of inflammatory molecules has been suggested to play an important role in dopaminergic neuron loss in Parkinsons disease (PD). Among inflammatory molecules, inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 (COX‐2) have been focused upon as key factors in the pathogenesis. However, the mechanism of how these molecules are induced in PD brains is not clearly understood. We focused on CD40, which is expressed on neural cells and could be implicated in the neuroinflammation by inducing inflammatory molecules. We showed that both iNOS and COX‐2 were up‐regulated in microglia and astrocytes by CD40 stimulation in association with a low dose of interferon‐γ (IFN‐γ) in vitro. Selective loss of dopaminergic neurons was induced by costimulation with CD40 and IFN‐γ in mesencephalic cultures, which was protected by selective inhibitors of iNOS and/or COX‐2. We also found in CD40‐stimulated astrocytes an increase of a low‐affinity IgE receptor CD23, which is known to induce iNOS expression. Together these data suggest that up‐regulated iNOS and COX‐2 via the CD40 pathway may lead to dopaminergic neuron loss and may participate in the neuroinflammaory pathway of PD.

Synchrotron FTIR micro-spectroscopy for structural analysis of Lewy bodies in the brain of Parkinson’s disease patients

Lewy bodies (LBs), which mainly consist of α-synuclein (α-syn), are neuropathological hallmarks of patients with Parkinson’s disease (PD). The fine structure of LBs is unknown, and LBs cannot be made artificially. Nevertheless, many studies have described fibrillisation using recombinant α-syn purified from E. coli. An extremely fundamental problem is whether the structure of LBs is the same as that of recombinant amyloid fibrils. Thus, we used synchrotron Fourier transform infrared micro-spectroscopy (FTIRM) to analyse the fine structure of LBs in the brain of PD patients. Our results showed a shift in the infrared spectrum that indicates abundance of a β-sheet-rich structure in LBs. Also, 2D infrared mapping of LBs revealed that the content of the β-sheet structure is higher in the halo than in the core, and the core contains a large amount of proteins and lipids.

Pioglitazone promotes peripheral nerve remyelination after crush injury through CD36 upregulation

Abstract  In our previous study, we found that CD36‐deficient mice showed significant delays in peripheral nerve remyelination after sciatic nerve crush injury and suggested that CD36 played an important role in the restoration of injured peripheral nerves. The aim of this study was to investigate whether CD36 upregulation can promote peripheral nerve remyelination. We made crush injury that caused demyelination and mild axonal degeneration to sciatic nerves and investigated the effect of pioglitazone (PIO) on the remyelination post‐injury in C57Bl/6 wild‐type and CD36‐deficient mice. The immunohistochemistry with anti‐CD36 antibody showed that CD36 was upregulated in macrophages infiltrating peripheral nerves from the wild‐type mice by PIO administration at 1 week post‐injury. The lectin histochemistry represented that infiltrating macrophages lessened in the wild‐type mice at 3 weeks post‐injury by PIO administration. General histopathology and morphometry indicated that thinly myelinated fibers and naked axons diminished in PIO‐treated wild‐type mice compared with non‐treated wild‐type mice at 3 weeks post‐injury. No significant differences were observed in remyelination and number of infiltrating macrophages between PIO‐treated and non‐treated CD36‐deficient mice. These results indicate that PIO promotes peripheral nerve remyelination possibly through CD36. It may be possible to apply PIO to the remedy against demyelinating neuropathies.

Adult-onset multiple acyl CoA dehydrogenation deficiency associated with an abnormal isoenzyme pattern of serum lactate dehydrogenase.

We report a case of a 37 year-old male with multiple acyl-CoA dehydrogenation deficiency (MADD). The patient had suffered from exercise intolerance in his hip and thigh muscles for one year. Then, restriction of carbohydrates for a diet made his symptoms rapidly deteriorate. Blood test revealed compound heterozygosity for two novel missense mutations in the electron transfer flavoprotein dehydrogenase gene (ETFDH), and an abnormal LDH isoenzyme pattern: LDH-1 (60.0%) and LDH-2 (26.0%) predominated with abnormally elevated LDH-1/LDH-2 ratio (2.3), compared with muscle-derived LDH-5 (4.0%). Oral riboflavin treatment significantly improved his exercise intolerance and the LDH profile: LDH-1 (34.4%), LDH-2 (34.9%), LDH-5 (6.9%) and LDH-1/LDH-2 ratio (1.0). The abnormal LDH isoenzyme pattern may be one feature of adult-onset MADD selectively affecting type I muscle fibers with relatively high LDH-1 content.

Tumefactive brain lesion with rapid cavity formation associated with anti-aquaporin-4 antibody.

A 54-year-old woman with no medical history presented with left hemiparesis and hemianopsia. Brain MRI showed an extensive lesion without enhancement in the right parietal lobe, followed by rapid cavity formation (figure 1). Brain biopsy performed 55 days after disease onset revealed decreased glial fibrillary acidic protein and aquaporin-4 (AQP4) immunoreactivity, though we could not show the activated complement due to the paucity of the sample (figure 2).