Argyrophilic glial intracytoplasmic inclusions in multiple system atrophy: immunocytochemical and ultrastructural study

Neuropathology of Multiple System Atrophy, a Glioneuronal Degenerative Disease

Multiple system atrophy (MSA) is a fatal disease characterized pathologically by the widespread occurrence of aggregated α-synuclein in the oligodendrocytes referred to as glial cytoplasmic inclusions (GCIs). α-Synuclein aggregates are also found in the oligodendroglial nuclei and neuronal cytoplasm and nuclei. It is uncertain whether the primary source of α-synuclein in GCIs is originated from neurons or oligodendrocytes. Accumulating evidence suggests that there are two degenerative processes in this disease. One possibility is that numerous GCIs are associated with the impairment of oligo-myelin-axon-neuron complex, and the other is that neuronal inclusion pathology is also a primary event from the early stage. Both oligodendrocytes and neurons may be primarily affected in MSA, and the damage of one cell type contributes to the degeneration of the other. Vesicle-mediated transport plays a key role in the nuclear translocation of α-synuclein as well as in the formation of glial and neuronal α-synuclein inclusions. Recent studies have shown that impairment of autophagy can occur along with or as a result of α-synuclein accumulation in the brain of MSA and Lewy body disease. Activated autophagy may be implicated in the therapeutic approach for α-synucleinopathies.

Role of VAPB and vesicular profiles in α-synuclein aggregates in multiple system atrophy

The pathological hallmark of multiple system atrophy (MSA) is fibrillary aggregates of α‐synuclein (α‐Syn) in the cytoplasm and nucleus of both oligodendrocytes and neurons. In neurons, α‐Syn localizes to the cytosolic and membrane compartments, including the synaptic vesicles, mitochondria, and endoplasmic reticulum (ER). α‐Syn binds to vesicle‐associated membrane protein‐binding protein B (VAPB) in the ER membrane. Overexpression of wild‐type and familial Parkinson's disease mutant α‐Syn perturbs the association between the ER and mitochondria, leading to ER stress and ultimately neurodegeneration. We examined brains from MSA patients (n = 7) and control subjects (n = 5) using immunohistochemistry and immunoelectron microscopy with antibodies against VAPB and phosphorylated α‐Syn. In controls, the cytoplasm of neurons and glial cells was positive for VAPB, whereas in MSA lesions VAPB immunoreactivity was decreased. The proportion of VAPB‐negative neurons in the pontine nucleus was significantly higher in MSA (13.6%) than in controls (0.6%). The incidence of cytoplasmic inclusions in VAPB‐negative neurons was significantly higher (42.2%) than that in VAPB‐positive neurons (3.6%); 67.2% of inclusion‐bearing oligodendrocytes and 51.1% of inclusion‐containing neurons were negative for VAPB. Immunoelectron microscopy revealed that α‐Syn and VAPB were localized to granulofilamentous structures in the cytoplasm of oligodendrocytes and neurons. Many vesicular structures labeled with anti‐α‐Syn were also observed within the granulofilamentous structures in the cytoplasm and nucleus of both oligodendrocytes and neurons. These findings suggest that, in MSA, reduction of VAPB is involved in the disease process and that vesicular structures are associated with inclusion formation.

Insights into the pathogenesis of multiple system atrophy: focus on glial cytoplasmic inclusions

Multiple system atrophy (MSA) is a debilitating and fatal neurodegenerative disorder. The disease severity warrants urgent development of disease-modifying therapy, but the disease pathogenesis is still enigmatic. Neurodegeneration in MSA brains is preceded by the emergence of glial cytoplasmic inclusions (GCIs), which are insoluble α-synuclein accumulations within oligodendrocytes (OLGs). Thus, preventive strategies against GCI formation may suppress disease progression. However, although numerous studies have tried to elucidate the molecular pathogenesis of GCI formation, difficulty remains in understanding the pathological interaction between the two pivotal aspects of GCIs; α-synuclein and OLGs. The difficulty originates from several enigmas: 1) what triggers the initial generation and possible propagation of pathogenic α-synuclein species? 2) what contributes to OLG-specific accumulation of α-synuclein, which is abundantly expressed in neurons but not in OLGs? and 3) how are OLGs and other glial cells affected and contribute to neurodegeneration? The primary pathogenesis of GCIs may involve myelin dysfunction and dyshomeostasis of the oligodendroglial cellular environment such as autophagy and iron metabolism. We have previously reported that oligodendrocyte precursor cells are more prone to develop intracellular inclusions in the presence of extracellular fibrillary α-synuclein. This finding implies a possibility that the propagation of GCI pathology in MSA brains is mediated through the internalization of pathological α-synuclein into oligodendrocyte precursor cells. In this review, in order to discuss the pathogenesis of GCIs, we will focus on the composition of neuronal and oligodendroglial inclusions in synucleinopathies. Furthermore, we will introduce some hypotheses on how α-synuclein pathology spreads among OLGs in MSA brains, in the light of our data from the experiments with primary oligodendrocyte lineage cell culture. While various reports have focused on the mysterious source of α-synuclein in GCIs, insights into the mechanism which regulates the uptake of pathological α-synuclein into oligodendroglial cells may yield the development of the disease-modifying therapy for MSA. The interaction between glial cells and α-synuclein is also highlighted with previous studies of post-mortem human brains, cultured cells, and animal models, which provide comprehensive insight into GCIs and the MSA pathomechanisms.

Multiple system atrophy: genetic or epigenetic?

Multiple system atrophy (MSA) is a rare, late-onset and fatal neurodegenerative disease including multisystem neurodegeneration and the formation of α-synuclein containing oligodendroglial cytoplasmic inclusions (GCIs), which present the hallmark of the disease. MSA is considered to be a sporadic disease; however certain genetic aspects have been studied during the last years in order to shed light on the largely unknown etiology and pathogenesis of the disease. Epidemiological studies focused on the possible impact of environmental factors on MSA disease development. This article gives an overview on the findings from genetic and epigenetic studies on MSA and discusses the role of genetic or epigenetic factors in disease pathogenesis.

Towards translational therapies for multiple system atrophy

Multiple system atrophy (MSA) is a fatal adult-onset neurodegenerative disorder of uncertain etiopathogenesis manifesting with autonomic failure, parkinsonism, and ataxia in any combination. The underlying neuropathology affects central autonomic, striatonigral and olivopontocerebellar pathways and it is associated with distinctive glial cytoplasmic inclusions (GCIs, Papp-Lantos bodies) that contain aggregates of α-synuclein. Current treatment options are very limited and mainly focused on symptomatic relief, whereas disease modifying options are lacking. Despite extensive testing, no neuroprotective drug treatment has been identified up to now; however, a neurorestorative approach utilizing autologous mesenchymal stem cells has shown remarkable beneficial effects in the cerebellar variant of MSA. Here, we review the progress made over the last decade in defining pathogenic targets in MSA and summarize insights gained from candidate disease-modifying interventions that have utilized a variety of well-established preclinical MSA models. We also discuss the current limitations that our field faces and suggest solutions for possible approaches in cause-directed therapies of MSA.

Microtubule depolymerization suppresses alpha-synuclein accumulation in a mouse model of multiple system atrophy

Multiple system atrophy (MSA) is a neurodegenerative disease caused by an accumulation of alpha-synuclein (alpha-syn) in oligodendrocytes. Little is known about the cellular mechanisms by which alpha-syn accumulation causes neuronal degeneration in MSA. Our previous research, however, revealed that in a mouse model of MSA, oligodendrocytic inclusions of alpha-syn induced neuronal accumulation of alpha-syn, as well as progressive neuronal degeneration. Here we identify the mechanisms that underlie neuronal accumulation of alpha-syn in a mouse MSA model. We found that the alpha-syn protein binds to beta-III tubulin in microtubules to form an insoluble complex. The insoluble alpha-syn complex progressively accumulates in neurons and leads to neuronal dysfunction. Furthermore, we demonstrated that the neuronal accumulation of insoluble alpha-syn is suppressed by treatment with a microtubule depolymerizing agent. The underlying pathological process appeared to also be inhibited by this treatment, providing promise for future therapeutic approaches.

Multiple system atrophy: a primary oligodendrogliopathy

To this day, the cause of multiple system atrophy (MSA) remains stubbornly enigmatic. A growing body of observations regarding the clinical, morphological, and biochemical phenotypes of MSA has been published, but the interested student is still left without a clue as to its underlying cause. MSA has long been considered a rare cousin of Parkinson's disease and cerebellar degeneration; it is rich in acronyms but poor in genetic and environmental leads. Because of the worldwide research efforts conducted over the last two decades and the discovery of the alpha-synuclein-encoding SNCA gene as a cause of rare familial Parkinson's disease, the MSA field has seen advances on three fronts: the identification of its principal cellular target, that is, oligodendrocytes; the characterization of alpha-synuclein-rich glial cytoplasmic inclusions as a suitable marker at autopsy; and improved diagnostic accuracy in living patients resulting from detailed clinicopathological studies. The working model of MSA as a primary glial disorder was recently strengthened by the finding of dysregulation in the metabolism of myelin basic protein and p25alpha, a central nervous system-specific phosphoprotein (also called tubulin polymerization promoting protein, TPPP). Intriguingly, in early cases of MSA, the oligodendrocytic changes in myelin basic protein and p25alpha processing were recorded even before formation of glial cytoplasmic inclusions became detectable. Here, we review the evolving concept that MSA may not just be related to Parkinson's disease but also share traits with the family of demyelinating disorders. Although these syndromes vary in their respective cause of oligodendrogliopathy, they have in common myelin disruption that is often followed by axonal dysfunction.

Multiple system atrophy: alpha-synuclein and neuronal degeneration

Multiple system atrophy (MSA) is a sporadic neurodegenerative disorder that encompasses olivopontocerebellar atrophy (OPCA), striatonigral degeneration (SND) and Shy-Drager syndrome (SDS). The histopathological hallmark is the formation of alpha-synuclein-positive glial cytoplasmic inclusions (GCIs) in oligodendroglia. alpha-synuclein aggregation is also found in glial nuclear inclusions, neuronal cytoplasmic inclusions (NCIs), neuronal nuclear inclusions (NNIs) and dystrophic neurites. We evaluated the pathological features of 102 MSA cases, and presented the pathological spectrum of MSA and initial features of alpha-synuclein accumulation. We found that 39% of the 102 cases showed equivalent SND and OPCA pathologies, 33% showed OPCA- and 22% showed SND-predominant pathology, whereas 6% showed extremely mild changes. Our pathological analysis indicated that OPCA-type was relatively more frequent and SND-type was less frequent in Japanese MSA cases, compared to the relatively high frequency of SND-type in Western countries, suggesting that different phenotypic patterns of MSA may exist between races. In the early stage, in addition to GCIs, NNIs and diffuse homogenous alpha-synuclein staining in neuronal nuclei and cytoplasm were observed in lesions in the pontine nuclei, putamen, substantia nigra, locus ceruleus, inferior olivary nucleus, intermediolateral column of thoracic spinal cord, lower motor neurons and cortical pyramidal neurons. A subgroup of MSA cases with severe temporal atrophy showed numerous NCIs, particularly in the limbic system. These findings suggest that primary non-fibrillar and fibrillar alpha-synuclein aggregation also occur in neurons. The oligo-myelin-axon-neuron complex mechanism, along with the direct involvement of neurons themselves, may synergistically accelerate the degenerative process of MSA.

Glia cells in amyotrophic lateral sclerosis: New clues to understanding an old disease?

In classic neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), the pathogenic concept of a cell-autonomous disease of motor neurons has been challenged increasingly in recent years. Macro- and microglial cells have come to the forefront for their role in multistep degenerative processes in ALS and respective disease models. The activation of astroglial and microglial cells occurs early in the pathogenesis of the disease and seems to greatly influence disease onset and promotion. The role of oligodendrocytes and Schwann cells remains elusive. In this review we highlight the impact of nonneuronal cells in ALS pathology. We discuss diverse glial membrane proteins that are necessary to control neuronal activity and neuronal cell survival, and summarize the contribution of these proteins to motor neuron death in ALS. We also describe recently discovered glial mechanisms that promote motor neuron degeneration using state-of-the-art genetic mouse technology. Finally, we provide an outlook on the extent to which these new pathomechanistic insights may offer novel therapeutic approaches.

Cellular pathology in multiple system atrophy

Multiple system atrophy (MSA) is a sporadic, adult-onset neurodegenerative disease, which is characterized by striatonigral degeneration, olivopontocerebellar atrophy, and preganglionic autonomic lesions in any combination. The histological hallmark is the presence of argyrophilic fibrillary inclusions in the oligodendrocytes, referred to as glial cytoplasmic inclusions (GCIs). Fibrillary inclusions are also found in the neuronal somata, axons, and nucleus. Neuronal cytoplasmic inclusions are frequently found in the pontine and inferior olivary nuclei. Since the discovery of alpha-synuclein as a major component of glial and neuronal inclusions in MSA, two neurodegenerative processes have been considered in this disease: one is due to the widespread occurrence of GCIs associated with oligodendroglia-myelin degeneration (oligodendrogliopathy) in the central nervous system, and the other is due to the filamentous aggregation of alpha-synuclein in the neurons in several brain regions. These two degenerative processes might synergistically cause neuronal depletion in MSA.

The 2,6-disubstituted naphthalene derivative FDDNP labeling reliably predicts Congo red birefringence of protein deposits in brain sections of selected human neurodegenerative diseases

Deposition of conformationally altered proteins prominently characterizes pathogenesis and pathomorphology of a number of neurodegenerative disorders. 2-(1-{6-[(2-[F-18]fluoroethyl) (methyl)amino]-2-naphthyl} ethylidene) malononitrile ([F-18]FDDNP), a hydrophobic, viscosity-sensitive, solvent-sensitive, fluorescent imaging probe has been used with positron emission tomography to visualize brain pathology in the living brain of Alzheimer disease (AD) patients. Its non-radiofluorinated analog FDDNP was shown to label senile plaques and neurofibrillary tangles (NFTs) in brain tissue sections. This work aimed at evaluating FDDNP labeling of various protein deposits in fixed, paraffin-embedded brain tissue sections of selected neurodegenerative disorders: AD, cerebral amyloid angiopathy (CAA), transmissible spongiform encephalopathies, progressive supranuclear palsy (PSP), Pick disease (PiD), Parkinson disease, dementia with Lewy bodies, multiple system atrophy (MSA). Cerebral hypertensive vascular hyalinosis (HVH) was used as negative control. Significant agreement between amyloid histochemical properties and FDDNP labeling of the deposits was established. FDDNP labeling showed high positive predictive value for birefringence in senile plaques and NFTs in AD, prion plaques and amyloid deposits in CAA. No FDDNP labeled structures were observed in HVH, PSP, PiD or MSA tissue sections. Our findings may be of significant value for the detection of neuropathological aggregates with [F-18]FDDNP in some of these disorders in the living brain of human subjects.

Reversible conformational change of tau2 epitope on exposure to detergent in glial cytoplasmic inclusions of multiple system atrophy

Tau-like immunoreactivity (IR) on glial cytoplasmic inclusions (GCIs) of multiple system atrophy (MSA) was investigated with a panel of anti-tau antibodies and we found that tau2, one of the phosphorylation-independent antibodies, preferentially immunolabeled GCIs. Co-presence (0.03%) of polyethyleneglycol- p-isooctylphenyl ether (Triton X-100, TX) with tau2, however, abolished this IR on GCIs, but did not abolish tau2 IR on neurofibrillary tangles (NFTs). Tau2-immunoreactive bands on immunoblot of brain homogenates from MSA brains were retrieved mainly in a TRIS-saline-soluble fraction, as reported in normal brains. This was in contrast to SDS-soluble fractions from brain with Down's syndrome, which contained tau2-immunoreactive bands of higher molecular weight. It indicates that the appearance of tau2 IR on GCIs is not related to hyperphosphorylation of tau. These tau2-immunoreactive bands, except those from bovine brain, were similarly abolished in the presence of TX (0.06%), and repeated washing after exposure to TX restored the tau2 IR on immunohistochemistry and on immunoblot. These findings can be explained if the modified tau2 epitope undergoes a reversible conformational change on exposure to TX, which is reversible after washing. Because the conformation centered at Ser101 of bovine tau is crucial for its affinity to tau2, the Ser-like conformation mimicked by its human counterpart Pro may represent pathological modification of tau shared by GCIs and NFTs. The relative resistance of tau2 epitope on NFTs on exposure to TX suggests that tau woven into NFTs confers additional stability to the pathological conformation of tau2 epitope. The conformation of the tau2 epitope in GCIs is not as stable as in NFTs, suggesting that tau proteins are not the principal constituents of the fibrillary structures of GCIs, even though they were immunodecorated with tau2. The difference in the susceptibility of the tau2 epitope to TX may distinguish its conformational states, which are variously represented according to disease conditions.

Involvement of precerebellar nuclei in multiple system atrophy

In this semiquantitative study based on 26 post-mortem cases, we describe the involvement of precerebellar nuclei in multiple system atrophy (MSA), a progressive degenerative disorder of the human central nervous system characterized by abnormal, argyrophilic and alpha-synuclein immunopositive intracellular inclusions within selectively vulnerable oligodendrocytes and nerve cells. The Campbell-Switzer silver-pyridine technique with alpha-synuclein immunoreactions using 100-microm thick sections is recommended over more conventional methods, thereby permitting visualization of the pertinent lesions in greater detail and facilitating post-mortem diagnosis of MSA specimens. Affected oligodendrocytes occur in specific fibre tracts and grey matters, with most pathology being observed in projections from the precerebellar nuclei to the cerebellum (ponto-cerebellar, olivo-cerebellar, reticulo-cerebellar tracts) and in descending/ascending fibre tracts of the motor system (cortico-pontine, cortico-bulbar, cortico-spinal, spino-reticular, spino-olivary, spino-cerebellar tracts). Three types of abnormal intraneuronal aggregations occur: (i) a loosely woven network within the cell nucleus; (ii) a latticework accumulating in peripheral portions of the cell body; and (iii) irregularly outlined patches of compact, intensely argyrophilic material usually located within deposits of lipofuscin granules. Counter-staining for the presence of extraneuronal lipofuscin can aid neuropathologists in the recognition of lost existent neurones in MSA. Neurones with inclusion bodies occur in the inferior olivary nuclear complex, lateral reticular nucleus, external cuneate nucleus, conterminal nucleus, interfascicular nucleus, nucleus of Roller, dorsal paramedian reticular nucleus, subventricular nucleus, arcuate nucleus, pontobulbar body and pontine grey. The lateral reticular nucleus and accessory nuclei of the inferior olive sustain the most damage and reveal prominent neuronal loss, followed by the pontobulbar body and arcuate nucleus. The uniformly bilateral damage and, in some cases, even obliteration of the nuclei studied, supply additional evidence for the pathoanatomical substrata of the cerebellar dysfunction that reportedly emerges in the clinical course of MSA.

Asymmetrical temporal lobe atrophy with massive neuronal inclusions in multiple system atrophy

This report concerns a rare association of asymmetrical temporal lobe atrophy with multiple system atrophy (MSA). A 53-year-old Japanese woman developed cerebellar ataxia and parkinsonism and was diagnosed as olivopontocerebellar atrophy (OPCA). This patient showed forgetfulness and subsequent disorientation even in the early stage of the disease. She fell into a decorticate state at the age of 64, and died a year later. The autopsy showed MSA with asymmetrical atrophy of temporal lobes, intraneuronal globular inclusions mostly confined to the hippocampus, amygdaloid nucleus, and most abundant in the granule cells in the dentate fascia. These inclusions were intensely argyrophilic and expressed marked immunoreactivity to ubiquitin, but not to neurofilament (NF), tau and paired helical filaments (PHF). Ultrastructurally, they were composed of scattered short filamentous structures of 15 to 30 nm in diameter, ribosome-like granules, mitochondria and lipofuscin. The lack of immunoreactivity against tau, NF and PHF suggests that the inclusions are distinct from Pick bodies. To our knowledge, MSA in association with asymmetrical temporal lobe atrophy with the present neuronal inclusions has not been reported. This case is distinct from MSA combined with atypical Pick's disease in the distribution and immunohistochemical properties of neuronal inclusions, and may present a new variant of MSA since the neuronal inclusions are similar, in many respects, to those of neuronal inclusions reported in MSA. Globular inclusions are also discussed in variants of Pick's disease, amyotrophic lateral sclerosis and Alzheimer's disease.

Immunohistochemical and biochemical studies demonstrate a distinct profile of alpha-synuclein permutations in multiple system atrophy

Although alpha-synuclein (alpha-syn) has been implicated as a major component of the abnormal filaments that form glial cytoplasmic inclusions (GCIs) in multiple system atrophy (MSA), it is uncertain if GCIs are homogenous and contain full-length alpha-syn. Since this has implications for hypotheses about the pathogenesis of GCIs, we used a novel panel of antibodies to defined regions throughout alpha-syn in immunohistochemical epitope mapping studies of GCIs in MSA brains. Although the immunostaining profile of GCIs with these antibodies was similar for all MSA brains, there were significant differences in the immunoreactivity of the alpha-syn epitopes detected in GCIs. Notably, carboxy-terminal alpha-syn epitopes were immunodominant in GCIs, but the entire panel of antibodies immunostained cortical Lewy bodies (LBs) in dementia with LBs brain with similar intensity. While the distribution of alpha-syn labeled GCIs paralleled that previously reported using silver stains, antibodies to carboxy-terminal alpha-syn epitopes revealed a previously undescribed burden of GCIs in the MSA hippocampal formation. Finally, Western blots demonstrated detergent insoluble monomeric and high-molecular weight alpha-syn species in GCI rich MSA cerebellar white matter. Collectively, these data indicate that alpha-syn is a prominent component of GCIs in MSA, and that GCIs and LBs may result from cell type specific conformational or post-translational permutations in alpha-syn.

Mutant and wild type human alpha-synucleins assemble into elongated filaments with distinct morphologies in vitro

alpha-Synuclein is a soluble presynaptic protein which is pathologically redistributed within intracellular lesions characteristic of several neurodegenerative diseases. Here we demonstrate that wild type and two mutant forms of alpha-synuclein linked to familial Parkinson's disease (Ala30 --> Pro and Ala53 --> Thr) self-aggregate and assemble into 10-19-nm-wide filaments with distinct morphologies under defined in vitro conditions. Immunogold labeling demonstrates that the central region of all these filaments are more robustly labeled than the N-terminal or C-terminal regions, suggesting that the latter regions are buried within the filaments. Since in vitro generated alpha-synuclein filaments resemble the major ultrastructural elements of authentic Lewy bodies that are hallmark lesions of Parkinson's disease, we propose that self-aggregating alpha-synuclein is the major subunit protein of these filamentous lesions.

Multiple system atrophy with severe involvement of the motor cortical areas and cerebral white matter

We report multiple system atrophy (MSA) of 14 years' duration in a 75-year-old woman. Postmortem examination revealed pathological changes typical of MSA. Furthermore, neuronal loss with astrocytosis in the primary motor and premotor cortices, especially in the fifth and sixth layers, and extensive myelin and axonal loss in the frontal and parietal white matter were evident. There were numerous ubiquitin-positive oligodendroglial inclusions, which are characteristic of MSA, in these cortical and white matter lesions. These findings suggest that the motor cortical areas and cerebral white matter are sites of significant involvement in the MSA disease process and that inclusion-bearing oligodendroglial alterations contribute to the white matter degeneration.

Non-familial olivopontocerebellar atrophy combined with late onset Alzheimer's disease: a clinico-pathological case report

A 76-year-old woman with olivopontocerebellar atrophy (OPCA) presented with progressive intellectual deterioration. She showed cerebellar ataxia and muscle atrophy and weakness, and gradually developed generalized dementia with visuospatial disturbance. An autopsy revealed numerous senile plaques (SPs), neurofibrillary tangles (NFTs) and neuropil threads particularly in the CA1, subiculum and entorhinal cortex and to a lesser degree in the cerebral neocortex shown by immunostaining and specific silver impregnation techniques. The nucleus basalis of Meynert had numerous NFTs with fibrillary gliosis and neuronal cell loss. The basis pontis was markedly atrophied and the pontine nucleus had severe neuronal depopulation and gliosis. The pontine transverse fibers were demyelinated with their axons being fragmented. The cerebellar white matter was also severely degenerated. The striatum, Onuf's and intermediolateral nuclei of the spinal cord remained unchanged. Ubiquitin immunohistochemistry and Gallyas silver impregnation technique revealed oligodendroglial inclusions in the pontine nucleus, corticopontine tract, cerebral and cerebellar white matter. On double immunostaining of KP1 and ubiquitin, globular neurite SPs encircled by KP1-positive fibrous structures were found in the hippocampus and cerebral neocortex. The curly neurite SPs contained KP1-positive granules. The KP1-positive microglial cells were distributed widely in the cerebral white matter and HLA-DR-positive ones were found around the SPs. The present case showed generalized dementia compatible with Alzheimer's disease (AD) and had a pathologically limbic type of late onset AD. This is the first case where AD affected non-familial OPCA.

Tau immunoreactivity in glial cytoplasmic inclusions in multiple system atrophy

In order to clarify the manner and significance of tau expression in glial cytoplasmic inclusions (GCIs), ubiquitinated oligodendroglial abnormal structures in multiple system atrophy (MSA), an immunohistochemical study was carried out in the lesions of the pontine nuclei of 10 cases of MSA using antibodies against various epitope locations of tau protein. As a result, tau-2 was constantly but weakly positive in ubiquitinated GCIs in each case (from 28.6 to 66.7%). However, tau-2-immunoreactivity in GCIs was not correlated to the density of ubiquitin-positive GCIs or preserved pontine neurons. Antibodies against tau proteins of N-terminal or C-terminal failed to label GCIs, although a few number of GCIs were occasionally positive for tau-1 after dephosphorylation. In comparison with the knowledge on tau-immunoreactivity of coiled bodies (CBs) in oligodendroglia in progressive supranuclear palsy (PSP) or corticobasal degeneration, GCIs are quite different from CBs which have a wide range of epitope location of tau proteins, including N-terminal and C-terminal. This study suggests that expression of tau proteins in GCIs is not related to the essential neurodegenerative process in MSA but induced by non-specific stress in oligodendroglia, unlike CB in various 'tau diseases' such as PSP.

The acoustic startle response is normal in patients with multiple system atrophy

We investigated the acoustic startle response in eight patients with MSA and compared the results with those from a group of age matched healthy subjects. Onset latency and amplitude of the responses obtained in the orbicularis oculi, masseter and sternocleidomastoid muscles were not different in patients and control subjects. We conclude that, in spite of the pathological derangement described in brainstem reticular nuclei in MSA, the neuronal circuits mediating the auditory startle reflex are functionally preserved.

Tau protein in the glial cytoplasmic inclusions of multiple system atrophy can be distinguished from abnormal tau in Alzheimer's disease

The glial cytoplasmic inclusion (GCI) is a histological hallmark for multiple system atrophy (MSA). These inclusions are in oligodendrocytes, contain microtubular structures of 20-30 nm diameter, and can be labelled immunohistochemically with antibodies to ubiquitin, alphaB-crystallin, alpha- and beta-tubulin, and the microtubule-associated protein tau. GCIs have been compared with neuronal inclusions in other neurodegenerative disorders including the neurofibrillary tangles (NFTs) found in Alzheimer's disease (AD), which also contain tau protein. In order to determine whether the tau protein of GCIs in MSA is similar to that observed in AD we used a panel of antibodies to phosphorylation-independent (SMI51, TP007, TP70), dephosphorylation-dependent (Tau.1), and phosphorylation-dependent antibodies to tau and neurofilaments (AT8, AT180, AT270, SMI31, SMI34, RT97, BF10, 8D8). Immunohistochemistry was performed on paraffin wax-embedded brain tissue of the cerebellum, brainstem, and frontal lobes (Brodmann areas 4/6) of ten clinically and neuropathologically well-characterised cases of MSA, two cases of AD, and two normal controls. The NFTs of the AD cases were labelled with all the phosphorylation-dependent and phosphorylation-independent antibodies and with Tau.1 only after treatment with alkaline phosphatase. In contrast, GCIs were immunolabelled by the phosphorylation-independent antibodies and Tau.1, but not by the phosphorylation-dependent antibodies. These data demonstrate that the tau in GCIs is different from the abnormally phosphorylated tau found in AD and is similar to normal adult tau. The mechanism causing the abnormal accumulation of tau in GCIs remains to be elucidated.

Rapid alteration of tau in oligodendrocytes after focal ischemic injury in the rat: involvement of free radicals

Glial inclusions containing the microtubule-associated protein tau are present in a variety of chronic neurodegenerative conditions. We now report a rapid and time-dependent increase of tau immunoreactivity within oligodendrocytes after focal cerebral ischemia in the rat. The number of tau positive oligodendrocytes in the ipsilateral subcortical white matter increased six- to eightfold by 40 minutes after permanent middle cerebral artery occlusion (MCAO). Tau was detected using antibodies that label both the N- and C-terminal of the protein, suggesting accumulation of full-length protein within these cells. Pretreatment with the spin trap agent alpha-phenyl-tert-butyl-nitrone (PBN)(100mg/kg) reduced the number of tau-positive oligodendrocytes by 55% in the subcortical white matter of the ischemic hemisphere compared with untreated animals at 40 minutes after MCAO. In contrast, pretreatment with glutamate receptor antagonists MK-801 (0.5 mg/kg) or 2,3-dihydroxy-6-nitro-7-sulpfamoyl-benzo(f)quinoxaline (NBQX) (2 x 30 mg/kg), failed to reduce the number of tau-positive oligodendrocytes after 40 minutes of ischemia. The results indicate that oligodendrocytes respond rapidly to an ischemic challenge and that free radical-mediated mechanisms are involved in the cascade leading to increased tau immunoreactivity.

Neuronal inclusions in the dentate fascia in patients with multiple system atrophy

Ubiquitin-immunoreactive neuronal inclusions in the granular cells in the dentate fascia (UNIDs) of patients with multiple system atrophy (MSA) were examined for immunohistochemical and ultrastructural characterization especially in comparison with those which were recently reported for amyotrophic lateral sclerosis with dementia (ALS-D). Eight of 23 MSA patients had UNIDs which were also identified by Gallyas-Braak impregnation but immunonegative for other antibodies including against tau, neurofilaments, and alphaB crystallin. Ultrastructurally, loosely aggregated fibrils without limiting membrane located around the nucleus, which was confirmed by the results of ubiquitin-immunoelectron microscopy. The formation of UNIDs in MSA and ALS-D was suggested to be caused by different types of degeneration because UNIDs in MSA differ from these in ALS-D in terms of their stainability by Gallyas-Braak impregnation and ultrastructurally. In this study hippocampal involvement in MSA differing from ALS-D was clarified.

Clinicopathology of spinocerebellar degeneration: its correlation to the unstable CAG repeat of the affected gene

The recent advances in gene analysis have greatly facilitated the classification of autosomal dominant spinocerebellar ataxia (SCA). Analyses of linkage in large families with SCA have assigned gene foci to at least 8 chromosomes. One gene is located in the short arm of chromosome 6 (6p22-p23) and causes spinocerebellar ataxia type 1 (SCA1). A gene in the long arm of chromosome 14 (14q24.3-q32) underlies Machado-Joseph disease (MJD). A third gene locus is assigned to the short arm of chromosome 12 (12p2-pter) causing dentatorubropallidoluysian atrophy (DRPLA). The gene for spinocerebellar ataxia type 2 (SCA2) is located in the 12q23-24. Subsequently, a sporadic counterpart of hereditary olivopontocerebellar atrophy of the Menzel type is clearly defined, and all the syndromes (non-hereditary olivopontocerebellar atrophy, striatonigral degeneration and Shy-Drager syndrome) are now lumped under the term of multiple system atrophy (MSA). Oligodendroglial cytoplasmic inclusions appear to be specific for and diagnostic of MSA. As the clinical features in SCA are variable and often appear to overlap with one another, which makes accurate classification difficult if not possible, the genotype is required for their unequivocal classification. However, major neuropathological features clearly distinguish SCA1 from SCA3/ MJD cases; the medial segment of the globus pallidus and intermediolateral column lesions in SCA3/MJD, and inferior olive and cerebellar cortical degeneration in SCA1. It has been stated that neurodegeneration in SCA3/MJD is more homogeneous than in SCA1 or SCA2 and that degeneration of the pallidoluysian system is not present in the latter. The pertinent pathology in each of the three types of SCA is illustrated. The background of clinicopathology and genetic analysis of dentatorubropallidoluysian atrophy is also reviewed.

Increased tau immunoreactivity in oligodendrocytes following human stroke and head injury

Tau immunohistochemistry was performed on post-mortem brain tissue from patients who died following head injury or stroke and from neurologically normal controls. Tau-positive oligodendrocytes were detected with three different tau antibodies in head injured or stroke patients, but not in control cases. Tau-positive oligodendrocytes were detected 2 h following head injury indicating that accumulation of tau may be an acute response of these cells to brain injury. The mechanisms underlying accumulation of tau in oligodendrocytes after acute brain injury may be similar to those which occur in chronic neurodegenerative conditions such as progressive supranuclear palsy (PSP) and multi-system atrophy (MSA).

Neurodegenerative disorders with extensive tau pathology: a comparative study and review

Many neurodegenerative disorders with onset in mid to late adult life present diagnostic challenges to clinicians and pathologists alike. A distinguishing neuropathological feature has traditionally been the presence or absence of neurofibrillary tangles. Recent biochemical and molecular biological studies have identified the microtubule-binding protein tau as the predominant component of these and related inclusions, and have provided powerful new reagents for the study of neurodegenerative diseases. Several diseases previously considered distinct pathophysiological entities contain similar tau-immunoreactive lesions, but qualitative and regional anatomical differences in vulnerability can differentiate the disorders. Comparison of tau-immunoreactive lesions in three relatively uncommon neurodegenerative diseases-progressive supranuclear palsy, Pick's disease, and corticobasal degeneration-illustrates the types of analyses that demonstrate unexpected pathological similarities, but also fundamental differences between these disorders. These results have important implications for the differential diagnosis of disorders containing tau-immunoreactive lesions, including Alzheimer's disease.

Which drug for which orthostatic hypotension?

This review focuses on the actual limits of the clinical pharmacology of drugs used for the treatment of orthostatic hypotension. The evidences for heterogeneity of the pathophysiological mechanisms of primary orthostatic hypotension and autonomic failure are discussed. The available data on the efficacy of some drugs used in orthostatic hypotension are also discussed.

Spinocerebellar ataxia type 1 with multiple system degeneration and glial cytoplasmic inclusions

Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited progressive neurological disorder characterized by neuronal degeneration and reactive gliosis in the cerebellum, brainstem, spinocerebellar tracts, and dorsal columns. Multiple system atrophy is a sporadic progressive neurological disorder with degeneration and gliosis in the basal ganglia, cerebellum, brainstem, and spinal autonomic nuclei, and with argyrophilic glial cytoplasmic inclusions. We describe 4 members of a family with the SCA1 mutation and a dominantly inherited progressive ataxia in which autopsy examination of 1 member showed neuropathological changes typical of multiple system atrophy, including glial cytoplasmic inclusions. In this patient, magnetic resonance imaging revealed marked brainstem and cerebellar volume loss and mild supratentorial generalized volume loss. Positron emission tomography with [18F]fluorodeoxyglucose revealed widespread hypometabolism in a pattern found in sporadic multiple system atrophy and not in dominantly inherited olivopontocerebellar atrophy. Positron emission tomography with [11C]flumazenil revealed normal benzodiazepine receptor distribution volumes, similar to those seen in sporadic multiple system atrophy. Two other family members still living had similar changes in the imaging studies. The findings in this family suggest that the SCA1 gene mutation can result in a disorder similar to multiple system atrophy, both clinically and neuropathologically.

Cytoskeletal pathology in non-Alzheimer degenerative dementia: new lesions in diffuse Lewy body disease, Pick's disease, and corticobasal degeneration

Increasing use of immunocytochemistry for evaluation of dementia disorders has revealed histopathological alterations that were previously unknown, even with sensitive silver techniques. Disorders [Pick's disease (PD), diffuse Lewy body disease (DLBD) and corticobasal degeneration (CBD)] in which immunocytochemistry has revealed occult pathology are discussed. All three disorders have neurofilament (NF) immunoreactive neuronal alterations in the neocortex. In DLBD round, eosinophilic cytoplasmic inclusions referred to as cortical Lewy bodies are neurofilament-positive, while in both PD and CBD neurofilament epitopes are expressed in irregularly swollen neurons and their proximal cell processes, which are referred to as ballooned neurons. Interestingly, the cortical neuronal population that is vulnerable to Lewy bodies is similar to that which is vulnerable to ballooned neurons. Furthermore, Lewy bodies can occasionally be detected within the cytoplasm of ballooned neurons. Besides neurofilament-immunoreactivity, Lewy bodies are immunoreactive for ubiquitin, while ballooned neurons are inconsistently stained with antibodies to ubiquitin. Both Lewy bodies and ballooned neurons can be appreciated with routine histology, but they are much easier to detect with immunocytochemistry. In contrast, a new type of neuritic alteration in the hippocampal CA2/3 region has been recognized in DLBD. These dystrophic neurites cannot be appreciated with routine histology and are only optimally seen with immunocytochemistry for ubiquitin. Their presence is a certain indication of the presence of cortical Lewy bodies. The microtuble associated protein tau is the major constituent of neurofibrillary tangles in Alzheimer's disease (AD). Biochemical studies have shown that Pick bodies, argyrophilic neuronal inclusions that are highly characteristic of, if not pathognomonic for PD are also composed of abnormal tau protein. Along with Pick bodies, tau has recently been detected in glial cells in PD. Similar so-called "gliofibrillary tangles" are increasingly recognized in progressive supranuclear palsy. Previously, CBD was considered to be free of such lesions, but recent studies have revealed widespread tau-positive neuronal and glial cytoskeletal lesions in CBD. A distinctive type of tau-positive glial lesion in CBD is characterized by annular clusters of grain-like tau immunoreactivity reminiscent of a neuritic plaque in AD, except that the clusters are devoid of amyloid. The tau-positive profiles are consistently located around a central astrocyte cell body. Double labeling studies with glial fibrillary acidic protein, vimentin and CD44, which are markers for reactive astrocytes, demonstrates tau immunoreactivity within astrocytic processes; these "astrocytic plaques" appear to be specific for CBD. Although NF, ubiquitin and tau proteins are present in diverse neuronal and glial inclusions in these disorders, the morphology and distribution of these lesions differentiate non-AD dementias.

Tau protein is altered by focal cerebral ischaemia in the rat: an immunohistochemical and immunoblotting study

Breakdown of the cytoskeleton may be involved in the evolution of ischaemic brain damage and alterations in microtubule-associated proteins may play an important role in this process. In the present study, tau, a microtubule-associated protein predominantly located in axons, was examined after 2 or 6 h of focal cerebral ischaemia in the rat. Immunohistochemistry revealed increased Tau1 staining in the neuropil, some perikarya and in glial cells throughout the dorsolateral caudate nucleus and ventrolateral neocortex in the ipsilateral hemisphere at both 2 and 6 h after occlusion of the middle cerebral artery. Contrastingly, immunostaining of another tau antibody, TP70, was unchanged in the neuropil, but was increased specifically in glial cells in these regions. Immunoblotting revealed the presence of additional tau bands in tissue extracts of the caudate nucleus and ventrolateral neocortex ipsilateral to the occluded middle cerebral artery as detected by both tau antibodies after either 2 or 6 h. The results suggest that tau is dephosphorylated and/or degraded in axons and some neuronal perikarya in response to focal cerebral ischaemia. In contrast to the response in neurons, increased immunoreactivity of both tau antibodies in glial cells indicates a differential response of neuronal and glial tau to focal cerebral ischaemia.

Cellular pathology of multiple system atrophy: a review

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