Neuropathology and Applied Neurobiology
Wiley Online Library : Neuropathology and Applied Neurobiology

  • Brain haemosiderin in older people: pathological evidence for an ischaemic origin of MRI microbleeds
    Introduction Magnetic Resonance Imaging (MRI) cerebral microbleeds (CMB) arise from ferromagnetic haemosiderin iron assumed to derive from extravasation of erythrocytes. Light microscopy of ageing brain frequently reveals foci of haemosiderin from single crystalloids to larger, predominantly perivascular, aggregates. The pathological and radiological relationship between these findings is not resolved. Methods Haemosiderin deposition and vascular pathology in the putamen were quantified in 200 brains donated to the population-representative MRC Cognitive Function and Ageing Study. Molecular markers of gliosis and tissue integrity were assessed by immunohistochemistry in brains with highest (n=20) and lowest (n=20) levels of putamen haemosiderin. The association between haemosiderin counts and degenerative and vascular brain pathology, clinical data, and the Haemochromatosis (HFE) gene H63D genotype were analysed. The frequency of MR CMB in 10 cases with highest and lowest burden of putamen haemosiderin, was compared using post-mortem 3T MRI. Results Greater putamen haemosiderin was significantly associated with putaminal indices of small vessel ischaemia (microinfarcts, p<0.05; arteriolosclerosis, p<0.05; perivascular attenuation, p<0.001) and with lacunes in any brain region (p<0.023) but not large vessel disease, or whole brain measures of neurodegenerative pathology. Higher levels of putamen haemosiderin correlated with more CMB (p<0.003). Conclusions The MRI-CMB concept should take account of brain iron homeostasis, and small vessel ischaemic change in later life, rather than only as a marker for minor episodes of cerebrovascular extravasation. These data are of clinical relevance, suggesting that basal ganglia MRI-microbleeds may be a surrogate for ischaemic small vessel disease rather than exclusively a haemorrhagic diathesis.

  • Intranasal exposure to uranium results in direct transfer to the brain along olfactory nerve bundles
    AIMS Uranium olfactory uptake after intranasal exposure raises some concerns for people potentially exposed to airborne radionuclide contamination as the brain could be a direct target for these contaminants. A model of nasal instillation was used to elucidate the transport mechanisms of uranium to the brain and to map its localisation. METHODS Increasing concentrations of depleted uranium containing solutions were instilled in the nasal cavity of adult male rats. Uranium concentrations were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) 4 hours after instillation. Olfactory neuroepithelium cytoarchitecture was studied using immunohistochemistry experiments. Secondary Ion Mass Spectrometry (SIMS) microscopy was performed to localise uranium in the olfactory system. RESULTS ICP-MS analyses showed a frontal accumulation of uranium in the olfactory bulbs associated with a smaller increase in more caudal brain regions (frontal cortex, hippocampus and cerebellum). Uranium concentrations in the olfactory bulbs do not reach a saturation point. Olfactory nerve bundle integrity is not affected by uranium as revealed by immunohistochemistry. SIMS microscopy allowed us to show that uranium localisation is mainly restricted to the olfactory neuroepithelium and around olfactory nerve bundles. It is subsequently detected in the olfactory nerve layer of the olfactory bulb. DISCUSSION These results suggest the existence of a transcellular passage from the mucosa to the perineural space around axon bundles. Uranium bypasses the blood brain barrier and is conveyed to the brain via the cerebrospinal fluid along the olfactory nerve. Future studies might need to integrate this new contamination route to assess uranium neurotoxicity after nasal exposure.

  • Clinic-pathological description of three paediatric medulloblastoma cases with MLL2/3 gene mutations
  • Axonal expression of sodium channels and neuropathology of the plaques in multiple sclerosis
    AIMS Although demyelination is an important cause of neurological deficits in Multiple Sclerosis (MS), recently axonal pathology and concomitant involvement of sodium channels (Nav) have become a focus of major interest. Studies in experimental autoimmune encephalomyelitis and MS have shown a diffuse distribution of the expression of two channels, Nav1.6 and Nav1.2, along the demyelinated axons. However, the relationship between the expression of these channels by the axon and its environment are not yet known. The aim of this study was to identify the stage and the neuropathological characteristics of the plaque associated with the changes in sodium channel axonal expression. METHODS We analysed the expression of Nav1.6 and Nav1.2 along demyelinated axons in 64 plaques from 12 MS cases (compared to 6 control cases) characterized according to the Vienna consensus. We used Bodian silver impregnation combined with Luxol fast blue stain and immunohistochemistry for myelin basic protein, microglia/macrophages, B and T cells, neurofilaments and glial fibrillary acidic protein performed on sections of formalin fixed, paraffin embedded tissue. RESULTS The presence of axonal diffuse expression of Nav1.6 was more frequent in inflammatory plaques with no active demyelination, and particularly within plaques with T cells and activated microglia. On the other hand, Nav1.2 expression seemed to be independent of the stage and the neuropathological environment of the plaque. CONCLUSIONS The cellular environment of the axon influences the differential expression of Nav channels. A better understanding on the influence of inflammation on the sodium channels mediated axonal degeneration could offer therapeutic perspectives.

  • Cerebrotendinous xanthomatosis with the c.379C>T (p.R127W) mutation in the CYP27A1 gene associated with premature age-associated limbic tauopathy
  • Progressive myoclonus epilepsy: extraneuronal brown pigment deposition and system neurodegeneration in the brains of Japanese patients with novel SCARB2 mutations
    Aims Mutations in the SCABR2 gene cause a rare autosomal recessive disease, progressive myoclonus epilepsy (PME) with or without renal failure, the former also being designated action myoclonus-renal failure syndrome. Although reported cases have been accumulating, only a few have described its neuropathology. We studied two Japanese patients with PME without renal failure, in whom the ages at onset and disease durations were 45 and 20 years, and 14 and 8.5 years, respectively. Methods Sequencing and restriction analysis of the SCARB2 gene and neuropathological examination with immunohistochemistry were performed. Results Gene analyses revealed novel homozygous frame-shift and nonsense mutations in the SCARB2 gene. Both cases exhibited deposition of brown pigment in the brain, especially the cerebellar and cerebral cortices. Ultrastructurally, the pigment granules were localized in astrocytes. Neuronal loss and gliosis were also evident in the brain, including the pallido-luysian and cerebello-olivary systems. The spinal cord was also affected. Such changes were less severe in one patient with late-onset disease than in the other patient with early-onset disease. In brain and kidney sections, immunostaining with an antibody against the C-terminus of human SCARB2 revealed decreased levels and no expression of the protein, respectively. Conclusions The frame-shift mutation detected in the patient with late-onset disease is a hitherto undescribed, unique type of SCABR2 gene mutation. The present two patients are the first reported to have clearly demonstrated both extraneuronal brown pigment deposition and system neurodegeneration as neuropathologic features of PME with SCABR2 mutations.

  • Phosphatidylinositol-4,5-bisphosphate is enriched in granulovacuolar degeneration bodies and neurofibrillary tangles
    Aims Among the pathological findings in Alzheimer's disease (AD), the temporal and spatial profiles of granulovacuolar degeneration (GVD) bodies are characteristic in that they seem to be related to those of neurofibrillary tangles (NFTs), suggesting a common mechanism underlying the pathogenesis of these structures. Flotillin-1, a marker of lipid rafts, accumulates in lysosomes of tangle-bearing neurons in AD patients. In addition, recent reports have shown that GVD bodies accumulate at the nexus of the autophagic and endocytic pathways. The aim of this study was to elucidate the distribution of the lipid component of lipid rafts, phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2], in AD and other neurodegenerative disorders. Methods We compared PtdIns(4,5)P2 immunoreactivity in the hippocampus, entorhinal cortex and neocortex of five AD cases, 17 cases of other neurodegenerative disorders and four controls. In addition, we performed double staining using markers of GVD, NFTs and lipid rafts for further characterization. Results Immunohistochemical analysis revealed that PtdIns(4,5)P2 was selectively enriched in GVD bodies and NFTs. Although immunoreactivity for PtdIns(4,5)P2 was also evident in NFTs composed of hyperphosphorylated tau, PtdIns(4,5)P2 was segregated from phosphorylated tau within NFTs by double immunofluorescence staining. In contrast, PtdIns(4,5)P2 colocalized with the lipid raft markers flotillin-1 and annexin 2, within GVD bodies and NFTs. Conclusions These results suggest that lipid raft components including PtdIns(4,5)P2 play a role in the formation of both GVD bodies and NFTs.

  • Schwann cell involvement in the peripheral neuropathy of spinocerebellar ataxia type 3
    Aims Spinocerebellar ataxia type 3 (SCA3) is an inherited spinocerebellar ataxia caused by the expansion of trinucleotide CAG repeats in the gene encoding ataxin-3. The clinical manifestations of SCA3 include peripheral neuropathy, which is an important cause of disability in a subset of patients. Although the loss of neurons in the dorsal root ganglion (DRG) has been postulated to be the cause of this neuropathy, the precise mechanism remains to be elucidated. Methods To clarify the clinicopathological characteristics of SCA3-associated peripheral neuropathy, we performed nerve conduction studies and histopathological analyses. Nerve conduction studies were carried out in 18 SCA3 patients. Immunohistochemical analyses of the anterior and posterior roots of the spinal cord and peripheral nerves were performed in five SCA3 patients. We also employed immunohistochemistry and immunoelectron microscopy analyses with an anti-polyglutamine antibody. Results The mean sensory nerve action potentials of the SCA3 patients were half of the normal values. The motor conduction velocities were decreased, and the distal latencies were also significantly prolonged in the nerves studied relative to the those in normal controls. Histopathological analyses detected axonal sprouting and myelin thinning in all cases. Ataxin-3 aggregates were found in the cytoplasm of Schwann cells in all of the SCA3 patients examined but not in control subjects. Conclusions In addition to the previously reported neuronopathy, the results of the present study indicate that Schwann cells are involved in the formation of the pathogenic intracytoplasmic ataxin-3 protein aggregates in patients with SCA3-associated neuropathy.

  • Expression pattern of synaptic vesicle protein 2 (SV2) isoforms in patients with temporal lobe epilepsy and hippocampal sclerosis
    Aims Synaptic vesicle proteins 2 (SV2) are neuronal vesicles membrane glycoproteins that appear as important targets in the treatment of partial and generalized epilepsies. Therefore, we analyzed the expression of SV2 isoforms in the hippocampus of patients with temporal lobe epilepsy (TLE). Methods SV2A, SV2B and SV2C immunostaining and QuantiGene branched DNA assay were performed on biopsies from 31 consecutive TLE patients with mesial temporal sclerosis (MTS) and compared with 10 autopsy controls. SV2 expression was further compared with Timm's staining, and synaptophysin, Zinc transporter 3 (ZnT3), dynorphin, vesicular glutamate transporter 1 (VGLUT1), and vesicular GABA transporter (VGAT) expression. Results In TLE patients, SV2A and SV2B expression was decreased in areas of synaptic loss. SV2C, which is weakly expressed or absent in the hippocampus of controls, was overexpressed in 10/11 cases with classical MTS1A and mossy fibre sprouting but not in cases with other types of MTS. SV2C staining was located in the inner molecular layer of the dentate gyrus and co-localized with dynorphin, ZnT3 and VGLUT1, suggesting selective expression in presynaptic glutamatergic Zn2+-rich terminals of abnormal sprouting fibres. SV2 expression patterns correlated with histological subtypes of MTS, but not with clinical features or therapeutic regimens in this patient cohort. Conclusion In classical MTS1A, the expression of SV2 isoforms is altered with a marked decrease of SV2A and SV2B paralleling synaptic loss and a selective increase of SV2C in sprouting mossy fibres. These findings suggest a different physiology of sprouting synapses and the possibility to target them with SV2C-specific strategies.

  • Optineurin is potentially associated with TDP-43 and involved in the pathogenesis of inclusion body myositis
    S. Yamashita, E. Kimura, N. Tawara, H. Sakaguchi, T. Nakama, Y. Maeda, T. Hirano, M. Uchino and Y. Ando (2013) Neuropathology and Applied Neurobiology39, 406–416 Optineurin is potentially associated with TDP-43 and involved in the pathogenesis of inclusion body myositis Aims: Increasing evidences suggest a similarity in the pathophysiological mechanisms of neuronal cell death in amyotrophic lateral sclerosis (ALS) and myofibre degeneration in sporadic inclusion body myositis (sIBM). The aim of this study is to elucidate the involvement of ALS-causing proteins in the pathophysiological mechanisms in sIBM. Methods: Skeletal muscle biopsy specimens of five patients with sIBM, two with oculopharyngeal muscular dystrophy (OPMD), three with polymyositis (PM), three with dermatomyositis (DM), three with neurogenic muscular atrophy, and three healthy control subjects were examined. We analysed the expression and localization of familial ALS-causing proteins, including transactive response DNA binding protein-43 (TDP-43), fused in sarcoma/translocated in liposarcoma (FUS/TLS), Cu/Zn superoxide dismutase (SOD1) and optineurin (OPTN) by immunohistochemistry. Results: TDP-43, OPTN and, to a lesser extent, FUS/TLS were more frequently accumulated in the cytoplasm in patients with sIBM and OPMD than in patients with PM, DM, neurogenic muscular atrophy, or healthy control subjects. SOD1 was accumulated in a small percentage of myofibres in patients with sIBM and OPMD, and to a very small extent in patients with PM and DM. Confocal microscopy imaging showed that TDP-43 proteins more often colocalized with OPTN than with FUS/TLS, p62 and phosphorylated Tau. Conclusions: These findings suggest that OPTN in cooperation with TDP-43 might be involved in the pathophysiological mechanisms of skeletal muscular degeneration in myopathy with rimmed vacuoles. Further investigation into these mechanisms is therefore warranted.

  • Dendritic spine density is altered in a mouse model of Cockayne syndrome
  • Altered expression and splicing of Ca2+ metabolism genes in myotonic dystrophies DM1 and DM2
    A. Vihola, M. Sirito, L. L. Bachinski, O. Raheem, M. Screen, T. Suominen, R. Krahe and B. Udd (2013) Neuropathology and Applied Neurobiology39, 390–405 Altered expression and splicing of Ca2+ metabolism genes in myotonic dystrophies DM1 and DM2 Aims: Myotonic dystrophy types 1 and 2 (DM1 and DM2) are multisystem disorders caused by similar repeat expansion mutations, with similar yet distinct clinical features. Aberrant splicing of multiple effector genes, as well as dysregulation of transcription and translation, has been suggested to underlie different aspects of the complex phenotypes in DM1 and DM2. Ca2+ plays a central role in both muscle contraction and control of gene expression, and recent expression profiling studies have indicated major perturbations of the Ca2+ signalling pathways in DM. Here we have further investigated the expression of genes and proteins involved in Ca2+ metabolism in DM patients, including Ca2+ channels and Ca2+ binding proteins. Methods: We used patient muscle biopsies to analyse mRNA expression and splicing of genes by microarray expression profiling and RT-PCR. We studied protein expression by immunohistochemistry and immunoblotting. Results: Most of the genes studied showed mRNA up-regulation in expression profiling. When analysed by immunohistochemistry the Ca2+ release channel ryanodine receptor was reduced in DM1 and DM2, as was calsequestrin 2, a sarcoplasmic reticulum lumen Ca2+ storage protein. Abnormal splicing of ATP2A1 was more pronounced in DM2 than DM1. Conclusions: We observed abnormal mRNA and protein expression in DM affecting several proteins involved in Ca2+ metabolism, with some differences between DM1 and DM2. Our protein expression studies are suggestive of a post-transcriptional defect(s) in the myotonic dystrophies.

  • Juvenile autophagic vacuolar myopathy – a new entity or variant?
  • Mitochondrial DNA deletions and depletion within paraspinal muscles
    G. R. Campbell, A. Reeve, I. Ziabreva, T. M. Polvikoski, R. W. Taylor, R. Reynolds, D. M. Turnbull and D. J. Mahad (2013) Neuropathology and Applied Neurobiology39, 377–389 Mitochondrial DNA deletions and depletion within paraspinal muscles Aims: Although mitochondrial abnormalities have been reported within paraspinal muscles in patients with axial weakness and neuromuscular disease as well as with ageing, the basis of respiratory deficiency in paraspinal muscles is not known. This study aimed to determine the extent and basis of respiratory deficiency in paraspinal muscles from cases undergoing surgery for degenerative spinal disease and post mortem cases without a history of spinal disease, where age-related histopathological changes were previously reported. Methods: Cervical and lumbar paraspinal muscles were obtained peri-operatively from 13 patients and from six post mortem control cases (age range 18–82 years) without a neurological disease. Sequential COX/SDH (mitochondrial respiratory chain complex IV/complex II) histochemistry was performed to identify respiratory-deficient muscle fibres (lacking complex IV with intact complex II activity). Real-time polymerase chain reaction, long-range polymerase chain reaction and sequencing were used to identify and characterize mitochondrial DNA (mtDNA) deletions and determine mtDNA copy number status. Mitochondrial respiratory chain complex subunits were detected by immunohistochemistry. Results: The density of respiratory-deficient fibres increased with age. On average, 3.96% of fibres in paraspinal muscles were respiratory-deficient (range 0–10.26). Respiratory deficiency in 36.8% of paraspinal muscle fibres was due to clonally expanded mtDNA deletions. MtDNA depletion accounted for further 13.5% of respiratory deficiency. The profile of immunohistochemically detected subunits of complexes was similar in respiratory-deficient fibres with and without mtDNA deletions or mtDNA depletion. Conclusions: Paraspinal muscles appeared to be particularly susceptible to age-related mitochondrial respiratory chain defects. Clonally expanded mtDNA deletions and focal mtDNA depletion may contribute towards the development of age-related postural abnormalities.

  • GNA11 and N-RAS mutations: alternatives for MAPK pathway activating GNAQ mutations in primary melanocytic tumours of the central nervous system
    M. Gessi, J. Hammes, L. Lauriola, E. Dörner, J. Kirfel, G. Kristiansen, A. zur Muehlen, D. Denkhaus, A. Waha and T. Pietsch (2013) Neuropathology and Applied Neurobiology39, 417–425 GNA11 and N-RAS mutations: alternatives for MAPK pathway activating GNAQ mutations in primary melanocytic tumours of the central nervous system Aim: Primary melanocytic tumours are uncommon neoplasms of the central nervous system. Although similarities with uveal melanomas have been hypothesized, data on their molecular features are limited. Methods: In this study, we investigated the mutational status of BRAFV600E, KIT, GNAQ, GNA11, N-RAS and H-RAS in a series of 19 primary melanocytic tumours of the central nervous system (CNS). Results: We identified six cases harbouring mutations in the hotspot codon 209 of the GNAQ gene and two cases with mutations in the hotspot codon 209 of the GNA11 gene. Two mutations in codon 61 of N-RAS were also found. In the single strand conformation polymorphism (SSCP) analysis, no shifts corresponding to BRAFV600E mutations or suggesting activating mutations in the KIT gene were observed. Conclusions: In primary melanocytic tumours of the CNS, GNA11 and N-RAS mutations represent a mechanism of MAPK pathway activation alternative to the common GNAQ mutations. On the other hand, BRAFV600E mutations and activating KIT mutations seem to be absent or very rare in these tumours.

  • Implementation of a multi-institutional diffuse intrinsic pontine glioma autopsy protocol and characterization of a primary cell culture
    V. Caretti, M. H. A. Jansen, D. G. van Vuurden, T. Lagerweij, M. Bugiani, I. Horsman, H. Wessels, P. van der Valk, J. Cloos, D. P. Noske, W. P. Vandertop, P. Wesseling, T. Wurdinger, E. Hulleman and G. J. L. Kaspers (2013) Neuropathology and Applied Neurobiology39, 426–436 Implementation of a multi-institutional diffuse intrinsic pontine glioma autopsy protocol and characterization of a primary cell culture Aims: Diffuse intrinsic pontine glioma (DIPG) is a fatal paediatric malignancy. Tumour resection is not possible without serious morbidity and biopsies are rarely performed. The resulting lack of primary DIPG material has made preclinical research practically impossible and has hindered the development of new therapies for this disease. The aim of the current study was to address the lack of primary DIPG material and preclinical models by developing a multi-institutional autopsy protocol. Methods: An autopsy protocol was implemented in the Netherlands to obtain tumour material within a brief post mortem interval. A team of neuropathologists and researchers was available at any time to perform the autopsy and process the material harvested. Whole brain autopsy was performed and primary DIPG material and healthy tissue were collected from all affected brain areas. Finally, the study included systematic evaluation by parents. Results: Five autopsies were performed. The mean time interval between death and time of autopsy was 3 h (range 2–4). All tumours were graded as glioblastoma. None of the parents regretted their choice to participate, and they all derived comfort in donating tissue of their child in the hope to help future DIPG patients. In addition, we developed and characterized one of the first DIPG cell cultures from post mortem material. Conclusion: Here we show that obtaining post mortem DIPG tumour tissue for research purposes is feasible with short delay, and that the autopsy procedure is satisfying for participating parents and can be suitable for the development of preclinical DIPG models.

  • Two distinct types of dying back axonal degeneration in vitro
    G. Öztürk, N. Cengiz, E. Erdoğan, A. Him, E. K. Oğuz, E. Yenidünya and N. Ayşit (2013) Neuropathology and Applied Neurobiology39, 362–376 Two distinct types of dying back axonal degeneration in vitro Aims: In many neurodegenerative diseases and following traumas, dying back degeneration is a common phenomenon that aggravates the pathology and may eventually lead to death of the affected neurone. We aimed to investigate the mechanism of dying back degeneration with an in vitro axonal injury model. Methods: We cultured adult mouse dorsal root ganglion neurones and with a precise laser beam, cut the axons they extended. Preparations were imaged continuously and images were analysed to describe and quantify ensuing events. Potential contributions of calpains and caspases to the degeneration were explored using specific inhibitors and immunohistochemistry. In vivo implications of the results were sought in nerve sections after sciatic nerve cut. Results: The proximal part of the transected axons went under basically two types of dying back degeneration, fragmentation and retraction. In fragmentation the cytoplasm became condensed and with concomitant axial collapse the axon disintegrated into small pieces. In retraction, the severed axon was pulled back to the soma in an organized manner. We demonstrated that fragmentation was associated with a high risk of cell death, while survival rate with retraction was as high as those of uninjured neurones. Regeneration of transected axon was more likely after retraction than following fragmentation. Activities of caspase-3 and calpains but not of caspase-6 were found linked with retraction and regeneration but not with the fragmentation. Conclusions: This study describes two quite distinct types of dying back degeneration that lead an injured neurone to quite different fates.

  • Stereological assessment of the dorsal anterior cingulate cortex in schizophrenia: absence of changes in neuronal and glial densities
    M. Höistad, H. Heinsen, B. Wicinski, C. Schmitz and P. R. Hof (2013) Neuropathology and Applied Neurobiology39, 348–361 Stereological assessment of the dorsal anterior cingulate cortex in schizophrenia: absence of changes in neuronal and glial densities Aims: The prefrontal and anterior cingulate cortices are implicated in schizophrenia, and many studies have assessed volume, cortical thickness, and neuronal densities or numbers in these regions. Available data, however, are rather conflicting and no clear cortical alteration pattern has been established. Changes in oligodendrocytes and white matter have been observed in schizophrenia, introducing a hypothesis about a myelin deficit as a key event in disease development. Methods: We investigated the dorsal anterior cingulate cortex (dACC) in 13 men with schizophrenia and 13 age- and gender-matched controls. We assessed stereologically the dACC volume, neuronal and glial densities, total neurone and glial numbers, and glia/neurone index (GNI) in both layers II–III and V–VI. Results: We observed no differences in neuronal or glial densities. No changes were observed in dACC cortical volume, total neurone numbers, and total glial numbers in schizophrenia. This contrasts with previous findings and suggests that the dACC may not undergo as severe changes in schizophrenia as is generally believed. However, we observed higher glial densities in layers V–VI than in layers II–III in both controls and patients with schizophrenia, pointing to possible layer-specific effects on oligodendrocyte distribution during development. Conclusions: Using rigorous stereological methods, we demonstrate a seemingly normal cortical organization in an important neocortical area for schizophrenia, emphasizing the importance of such morphometric approaches in quantitative neuropathology. We discuss the significance of subregion- and layer-specific alterations in the development of schizophrenia, and the discrepancies between post mortem histopathological studies and in vivo brain imaging findings in patients.

  • Hypoplasia of the spinal cord in a case of foetal akinesia/arthrogryposis sequences
  • A rapidly expanding immature teratoma originating from a neurohypophyseal germinoma
  • In this issue
  • Mechanisms underlying synaptic vulnerability and degeneration in neurodegenerative disease
    Recent developments in our understanding of events underlying neurodegeneration across the central and peripheral nervous systems have highlighted the critical role that synapses play in the initiation and progression of neuronal loss. With the development of increasingly accurate and versatile animal models of neurodegenerative disease it has become apparent that disruption of synaptic form and function occurs comparatively early, preceding the onset of degenerative changes in the neuronal cell body. Yet, despite our increasing awareness of the importance of synapses in neurodegeneration, the mechanisms governing the particular susceptibility of distal neuronal processes are only now becoming clear. In this review we bring together recent developments in our understanding of cellular and molecular mechanisms regulating synaptic vulnerability. We have placed a particular focus on three major areas of research that have gained significant interest over the last few years: (i) the contribution of synaptic mitochondria to neurodegeneration; (ii) the contribution of pathways that modulate synaptic function; and (iii) regulation of synaptic degeneration by local posttranslational modifications such as ubiquitination. We suggest that targeting these organelles and pathways may be a productive way to develop synaptoprotective strategies applicable to a range of neurodegenerative conditions.

  • Laminar distribution of the pathological changes in sporadic frontotemporal lobar degeneration with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy: a quantitative study using polynomial curve fitting
    R. A. Armstrong, R. L. Hamilton, I. R. A. Mackenzie, J. Hedreen and N. J. Cairns (2013) Neuropathology and Applied Neurobiology39, 335–347 Laminar distribution of the pathological changes in sporadic frontotemporal lobar degeneration with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy: a quantitative study using polynomial curve fitting Aims: Previous data suggest heterogeneity in laminar distribution of the pathology in the molecular disorder frontotemporal lobar degeneration (FTLD) with transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) proteinopathy (FTLD-TDP). To study this heterogeneity, we quantified the changes in density across the cortical laminae of neuronal cytoplasmic inclusions, glial inclusions, neuronal intranuclear inclusions, dystrophic neurites, surviving neurones, abnormally enlarged neurones, and vacuoles in regions of the frontal and temporal lobe. Methods: Changes in density of histological features across cortical gyri were studied in 10 sporadic cases of FTLD-TDP using quantitative methods and polynomial curve fitting. Results: Our data suggest that laminar neuropathology in sporadic FTLD-TDP is highly variable. Most commonly, neuronal cytoplasmic inclusions, dystrophic neurites and vacuolation were abundant in the upper laminae and glial inclusions, neuronal intranuclear inclusions, abnormally enlarged neurones, and glial cell nuclei in the lower laminae. TDP-43-immunoreactive inclusions affected more of the cortical profile in longer duration cases; their distribution varied with disease subtype, but was unrelated to Braak tangle score. Different TDP-43-immunoreactive inclusions were not spatially correlated. Conclusions: Laminar distribution of pathological features in 10 sporadic cases of FTLD-TDP is heterogeneous and may be accounted for, in part, by disease subtype and disease duration. In addition, the feedforward and feedback cortico-cortical connections may be compromised in FTLD-TDP.

  • Pathology of SSLOW, a transmissible and fatal synthetic prion protein disorder and comparison with naturally occurring classical Transmissible Spongiform Encephalopathies.
    Aims Naturally occurring transmissible spongiform encephalopathies (TSEs) accumulate disease specific forms of prion protein on cell membranes in association with pathognomonic lesions. We wished to determine whether synthetic prion protein disorders recapitulated these and other sub-cellular TSE specific changes. Methods SSLOW is a TSE initiated with refolded synthetic prion protein. Five terminally sick hamsters previously intra-cerebrally inoculated with 3rd passage SSLOW were examined using light and immunogold electron microscopy. Results SSLOW affected hamsters showed widespread abnormal prion protein (PrPSSLOW) and amyloid plaques. PrPSSLOW accumulated on plasma-lemmas of neurites and glia without pathological changes. PrPSSLOW also co-localised with increased coated vesicles and pits, coated spiral membrane invaginations and membrane microfolding. PrPSSLOW was additionally observed in lysosomes of microglial cells but not of neurons or astrocytes. Conclusions PrPSSLOW is propagated by cell membrane conversion of normal PrP and lethal disease may be linked to the progressive growth of amyloid plaques. Cell membrane changes present in SSLOW are indistinguishable from those of naturally occurring TSEs. However, some lesions found in SSLOW are absent in natural animal TSEs and vice versa. SSLOW may not entirely recapitulate neuropathological features previously described for natural disease. End–stage neuropathology in SSLOW, particularly the nature and distribution of amyloid plaques may be significantly influenced by the early re-distribution of seeds within the inoculum and its recirculation following interstitial, perivascular and other drainage pathways. The way in which seeds are distributed and aggregate into plaques in SSLOW has significant overlap with murine APP overexpressing mice challenged with Aβ.

  • Immunolesion-induced loss of cholinergic projection neurons promotes β-amyloidosis and tau hyperphosphorylation in the hippocampus of triple-transgenic mice
    Aims Currently available animal models incompletely capture the complex pathophysiology of Alzheimer's disease (AD), typically involving β-amyloidosis, neurofibrillary tangle formation and loss of basal forebrain cholinergic projection neurons (CPN). While age-dependent β-amyloidosis and tau hyperphosphorylation are mimicked in triple-transgenic mice (3xTg), experimental induction of CPN loss in these mice is still lacking. Here, we introduce a more-complex animal model of AD by inducing cellular loss of CPN in an already existing transgenic background aiming to elucidate subsequent changes of hippocampal β-amyloid (Aβ) and tau pathology. Methods Twelve-month-old 3xTg mice intracerebroventricularly received the rabbit-anti-low affinity neurotrophin receptor p75-saporin, an immunotoxin specifically targeting forebrain CPN. After histochemical verification of immunolesion in immersion-fixed forebrains, markers of Aβ and tau metabolism were analysed using quantitative Western blot analyses of hippocampi from these mice. In parallel, these markers and glial activation were investigated by multiple immunofluorescence labelling of perfusion-fixed hippocampi and confocal laser-scanning microscopy. Results Four months after immunolesion, the selective lesion of CPN was verified by disappearance of choline acetyltransferase and p75 immunolabelling. Biochemical analysis of hippocampi from immunolesioned mice revealed enhanced levels of Aβ, amyloid precursor protein (APP) and its fragment C99. Furthermore, immunolesion-induced increase in levels of phospho-tau and tau with AD-like conformation were seen in 16-month-old mice. Immunofluorescence staining confirmed an age-dependent occurrence of hippocampal Aβ-deposits and phospho-tau, and demonstrated drastic gliosis around Aβ-plaques after immunolesion. Conclusion Overall, this extended model promises further insights into the complexity of AD and contributes to novel treatment strategies also targeting the cholinergic system.

  • Immunohistochemical detection of sphingosine-1-phosphate receptor 1 and 5 in human multiple sclerosis lesions
    Aims Sphingosine-1-phosphate receptor (S1PR) modulating therapies are currently in the clinic or undergoing investigation for multiple sclerosis (MS) treatment. However, the expression of S1PRs is still unclear in the central nervous system under normal conditions and during neuroinflammation. Methods Using immunohistochemistry we examined tissues from both grey and white matter MS lesions for S1P1 and S1P5 receptor expression. Tissues from Alzheimer's disease (AD) cases were also examined. Results S1P1 expression was restricted to astrocytes and endothelial cells in control tissues and a decrease in endothelial cell expression was found in white matter MS lesions. In grey matter MS lesions, astrocyte expression was lost in active lesions, whilst in quiescent lesions it was restored to normal expression levels. CNPase co-localisation studies demonstrated S1P5 expression on myelin and both were reduced in demyelinated lesions. In AD tissues we found no difference in S1P1 expression. Conclusion These data demonstrate a differential modulation of S1PRs in MS lesions, which may have an impact on S1PR directed therapies.

  • Microsphere formation in a subtype of Creutzfeldt-Jakob disease with a V180I mutation and codon 129 MM polymorphism
    Creutzfeldt-Jakob disease (CJD) with a point mutation of valine to isoleucine at codon 180 in the gene for PrP (V180I CJD) is genetic form of CJD found most frequently in Japan [1]. There are several reports of autopsied V180I CJD cases [2, 3], in which the examples with methionine and valine heterozygosity at the polymorphic codon 129 were found at a higher rate compared to the normal population in Japan [4]. Here, we report a patient with numerous amyloid microsphere formations in an unusual subtype of CJD with a V180I MM mutation who underwent a continuous intraventricular infusion of pentosan polysulfate (PPS). Western blot analysis for protease-resistant PrP (PrPres) revealed the characteristic two bands devoid of a diglycoform. Size exclusion gel chromatography showed that diglycoform PrPs were present mainly in a monomeric state, and less in an oligomeric state, and that the diglycoform PrPs were completely degraded by proteinase K (PK) treatment. These PrP-positive structures and PrP molecular species were unique to genetic CJD with V180I and 129MM.

  • A clinicopathological and genetic study of sporadic diffuse leukoencephalopathy with spheroids: A report of two cases
    Diffuse leukoencephalopathy with spheroids (DLS) is a white matter neurodegenerative disease characterized by progressive cognitive decline and motor symptoms [1-6], and histologically, by axonal swellings (‘spheroids’) and loss of axons and myelin [1-3, 5, 7-11]. It was originally described as a rare, hereditary, autosomal dominant disorder (hereditary DLS: HDLS) [2], but there have been reports on DLS without family history as well (sporadic DLS: SDLS) [6, 12-22]. In 2012, Rademakers et al. [9] identified 14 different mutations in the colony stimulating factor 1 receptor (CSF1R) gene, which are located in exons 12-22 and affect the tyrosine kinase domain of the protein, in 14 families with HDLS. Interestingly, this gene shares the same signaling pathway as TYROBP (DAP12) and TREM2, whose mutations are implicated in polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL, also known as Nasu-Hakola disease) [23-25]. PLOSL shares similar clinicopathological profiles with DLS, such as a progressive neuropsychiatric decline and leukoencephalopathy with spheroids [26, 27]. In this paper we describe the clinicopathological features of two cases of SDLS. In one of them, genetic analyses of CSF1R, TYROBP, and TREM2 were conducted, and no mutations in these genes were identified.

  • Analysis of CIC-associated CpG-island methylation in oligoastrocytoma
    Aims Combined deletion of the whole chromosomal arms 1p and 19q is a frequent event in oligodendroglial tumours. Recent identification of recurrent mutations in CIC on 19q and FUBP1 on 1p and their mutational patterns suggest a loss of function of the respective proteins. Surprisingly, oligoastrocytomas harbouring identical genetic characteristics regarding 1p/19q co-deletion and frequent IDH1/2 mutations have been shown to carry CIC mutations in a significantly lower number of cases. The present study investigates whether epigenetic modification may result in silencing of CIC. Methods Since IDH1/2 mutation mediated DNA hypermethylation is a prominent feature of these tumours, we analyzed a set of CIC wild-type oligoastrocytomas and other diffuse gliomas with regard to 1p/19q status for presence of CIC-associated CpG-island methylation by methylation-specific PCR. Results Both methylation specific PCR and subsequent bisulfite-sequencing of selected cases revealed an unmethylated status in all samples. Conclusion Despite the hypermethylator- phenotype in IDH1/2 mutant tumours and recent detection of gene silencing particularly on retained alleles in oligodendendroglial tumours, hypermethylation of CIC-associated CpG-islands does not provide an alternative mechanism of functional CIC protein abrogation.

  • Fungal encephalitis in human autopsy cases is associated with extensive neuronal damage but only minimal repair
    Aims The present study aimed at examining neuronal injury and repair in post mortem brain sections of humans who died from fungal CNS infections. Methods Histological and immunohistochemical abnormalities in 15 autopsy cases with fungal CNS infections from 1990 to 2008 were compared to findings in 10 age- und sex-matched control cases that died from acute non-neurological causes. The fungal pathogens were identified by culture or PCR and morphology in post mortem tissue. Seven patients with fungal encephalitis had either an organ transplantation or a malignant haematological disorder; 5 out of 15 did not have a classical pre-disposing illness but suffered from severe septic infections as the principal cause of immunosuppression, and 3 from alcoholism. Results Fungal organisms detected were Aspergillus spp. and other moulds, Candida spp. and black yeast-like fungi including Cladosporium spp.. Histological analyses identified microglial activation, astrocytosis and axonal injury in the white matter without additional demyelination as characteristic features of this infectious disease. An increased rate of hippocampal neuronal apoptosis was detected in fungal encephalitis, while the number of recently generated TUC-4 and calretinin-expressing neurons in the dentate gyrus did not differ between patients and controls. Conclusions Unlike in other infectious diseases of the nervous system where a co-existence of damage and repair was observed, fungal encephalitis is characterized by strong damage and minimal neuronal regeneration.

Copyright 2011 British Neuropathological Society
HomeSearchContact Us