Argyrophilic tau-positive twisted and non-twisted tubules in astrocytic processes in brains of Alzheimer-type dementia: an electron microscopical study

This report concerns pathological astrocytic tubular structures (astrocytic tubules, As-Tbs) that coexist with glial filaments in astrocytic processes in brains with presenile-onset Alzheimer-type dementia. The formation of As-Tbs appears to be related to the duration of disease and the intensity of Alzheimer histopathology. In three cases in which the disease was of extremely long duration, As-Tbs were found in the frontal and temporal neocortices, the temporal pole and the hippocampus using electron microscopy, whereas they were not found in two cases with a long, but not extremely long, illness duration. As-Tbs were almost exclusively found in the highly devastated neuropil, and we could not find them in regions of moderate neuronal degeneration despite intensive inspection. As reported previously, some As-Tbs was seen adjacent to extracellular neurofibrillary tangles (NFTs) and in perivascular astrocytes. Our novel finding is that they can exist independently from these, in the highly devastated neuropil. Two types of As-Tbs were observed, twisted tubules with periodic constrictions at 50- to 80-nm intervals and non-twisted tubules where no constrictions were seen but which had a 15-nm fuzzy outer contour. They were positively stained by anti-human tau antibody, an antibody that does not recognize extracellular NFTs. Thus, it is most likely that As-Tbs are not the sequestration of extracellular NFTs, and that they are of astrocytic origin. Moreover, As-Tbs showed argyrophilia. As-Tbs appear indistinguishable from dystrophic neurites under the light microscope. The present data suggest that they may be more widely distributed in the damaged cerebral neuropil than previously thought. Received: 20 June 1996 / Revised: 20 July 1997 / Accepted: 31 July 1997     

Substantia nigra in progressive supranuclear palsy, corticobasal degeneration, and parkinsonism-dementia complex of Guam: specific pathological features

Disease-specific findings in the substantia nigra were examined in cases of progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and parkinsonism-dementia complex of Guam (PDC); diseases in which the patients exhibit dementia and parkinsonism, with neurofibrillary tangles (NFTs) and glial tangles composed of hyperphosphorylated tau. Loss of pigmented neurons was extremely severe in these 3 diseases, and decrease of the nonpigmented neurons was severe in PSP and CBD. On the other hand, in PDC the decrease of the nonpigmented neurons was different in each patient. Topographically, in PSP the nonpigmented neurons were particularly depleted in the ventral part and relative preservation of the pigmented neurons was observed in the medial part at the level examined. Many NFTs were observed in PDC. Although the number of NFTs was small, many pretangles were seen in the neurons in CBD. Granular and hazy astrocytic inclusions were identified exclusively in PDC. Numerous argyrophilic neuropile threads were identified in CBD and PSP, but these were few in PDC. Many foamy spheroid bodies as well as coiled bodies were observed in PSP and CBD, but only a few were observed in PDC. In conclusion, PDC is a disease that is distinctly different from PSP and CBD. It is possible to differentiate between PSP and CBD by the occurrence of many pretangles in CBD, but some similarities between these 2 diseases indicate the existence of common pathological mechanisms.     

Amyotrophic lateral sclerosis with dementia: an autopsy case showing many Bunina bodies, tau-positive neuronal and astrocytic plaque-like pathologies, and pallido-nigral degeneration

We report the case of a 54-year-old woman with mental retardation who developed frontotemporal dementia and amyotrophic lateral sclerosis (ALS) in the presenium. She presented with dementia at age 48, and motor neuron signs developed at age 53. She had no family history of dementia or ALS. Postmortem examination disclosed histopathological features of ALS, including pyramidal tract degeneration, mild loss of motor neurons, and many Bunina bodies immunoreactive for cystatin C, but not ubiquitin-positive inclusions. Unusual features of this case included severe neuronal loss in the substantia nigra and medial globus pallidus. The subthalamic nucleus, limbic system, and cerebral cortex were well preserved. In addition, neurofibrillary tangles (NFTs) were found in the frontal, temporal, insular, and cingulate cortices, nucleus basalis of Meynert, and locus coeruleus, and to a lesser degree, in the dentate nucleus, cerebellum, hippocampus, and amygdala. No ballooned neurons, tufted astrocytes, or astrocytic plaques were found. Tau immunostaining demonstrated many pretangles rather than NFTs and glial lesions resembling astrocytic plaques in the frontal and temporal cortices. This glial tau pathology predominantly developed in the middle to deep layers in the primary motor cortex, and was frequently associated with the walls of blood vessels. NFTs were immunolabeled with 3-repeat and 4-repeat specific antibodies against tau, respectively. Although the pathophysiological relationship between tau pathology and the selective involvement of motor neurons, substantia nigra, and globus pallidus was unclear, we considered that it might be more than coincidental.     

An autopsy case of diffuse neurofibrillary tangles with calcification: Early stage pathologic findings

A 66‐year‐old man with no medically remarkable past or family history gradually showed personality changes, memory disturbance, sleeplessness and abnormal behavior. Neurologic examination showed no focal signs and neither parkinsonism nor cerebellar ataxia was recognized. He died 4 years after the onset of dementia due to chronic renal failure. Neuropathologic examination revealed neuronal loss and gliosis in the temporal cortex, particularly in the subiculum, parahippocampal gyrus and entorhinal cortex, and insular cortex. NFTs were observed to be widespread in the cerebral cortex, especially the temporal cortex and brainstem, while senile plaques were not observed. Gallyas‐Braak silver staining revealed the presence of numerous NFTs, glial inclusions and neuropil threads throughout the cerebral neocortex, limbic system, hippocampus and brainstem. The subiculum showed the most severe involvement; severe atrophy, severe neuron loss, and numerous ghost tangles (extracellular NFTs) were apparent. Although NFTs contained both monoclonal anti‐3repeat‐tau antibody (RD3) and RD4 immunoreactivity, this differed between the intracellular NFTs and ghost tangles. RD3 immunoreactivity was mainly observed in ghost tangles and neuropil threads, whereas RD4 immunoreactivity was mainly observed in intracellular NFTs and glial inclusions. Calcification was also found to be widespread in the cerebral cortex and white matter, basal ganglia, thalamus, cerebellar cortex, white matter and dentate nucleus. These characteristic neuropathologic findings lead to the pathologic diagnosis of diffuse neurofibrillary tangles with calcification (DNTC). It is argued that this patient showed early stage pathologic signs of DNTC due to a short disease duration, which may provide clues regarding the progression of this rare disease.     

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles in progressive supranuclear palsy

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles (NFTs) in progressive supranuclear palsy (PSP) were performed. The spinal cord NFTs reacted with antibodies to tau protein (tau-2), ubiquitin and Alzheimer neurofibrillary tangles (ANTs, Ab 39). Ultrastructurally, the NFTs consisted of bundles of straight fibrils. In longitudinal sections, the individual NFT fibrils appeared as straight fibrils with a diameter of approximately 15 nm. In cross sections, circular structures approximately 15 nm in diameter were seen, and some had a central density. Electron microscopic examination of specimens stained with the antibodies and by the modified Bielschowsky method revealed the products of the tau, ubiquitin and ANTs immunoreactions and silver deposits on the NFT fibrils. This is the first demonstration of the ultrastructure of spinal cord NFTs in PSP.     

Pick's disease immunohistochemistry: new alterations and Alzheimer's disease comparisons

Pick's disease (PD) brains were examined immunohistochemically for the expression of antigens known to be associated with Alzheimer's disease (AD) lesions. Most antibodies which label intracellular neurofibrillary tangles (NFTs) in AD were found to stain Pick bodies (PBs). Among them was the monoclonal antibody A2B5, which is known to recognize neuronal surface gangliosides. This result indicates that membrane proteins are probably incorporated into PBs as into NFTs. However, PBs, in contrast to NFTs, showed a paucity of staining for heparan sulfate glycosaminoglycan and basic fibroblast growth factor (bFGF). Staining for midline, seen in senile plaques in AD, was not seen in PD. The relative lack of staining for these two neurotrophic factors in PD brain may reflect underlying mechanisms which are distinct from those in AD. We also describe two glial abnormalities in PD: glial fibrillary tangles and clusters of granules positive for the complement protein C4d in the hippocampal dentate fascia. These are presumably related to complement-activated oligodendroglia, and both pathological structures are more abundant in advanced cases, suggesting that they may be hallmarks of the disease progression.     

Ganglioglioma with neurofibrillary tangles (NFTs): neoplastic NFTs share antigenic determinants with NFTs of Alzheimer's disease

A cerebral ganglioglioma contained abundant neurofibrillary tangles (NFTs) of the paired helical filament (PHF) type. The NFTs in the tumor were argyrophilic and Congo red and thioflavin-S positive. Immunohistochemically, the NFTs were reactive with antibodies to phosphorylated neurofilament protein, PHF/tau and abiquitin. The demonstration in the neoplasm of abnormally phosphorylated and ubiquitinated cytoskeletal components, similar in morphology and in immunoreactivity to those seen in NFTs of Alzheimer's disease, suggest that similar pathogenetic mechanisms may operate in both conditions.     

A COMPARATIVE STUDY OF MODIFIED BIELSCHOWSKY, BODIAN AND THIOFLAVIN S STAINS ON ALZHEIMER''S NEUROFIBRILLARY TANGLES

Serial sections of the brains of two cases with Alzheimer's disease were stained with the standard Bodian, modified Bielschowsky (reformed Gros-Schultze's modification) and thioflavin S methods. The numbers of demonstrated Alzheimer's neurofibrillary tangles (NFTs) were different between the two silver stains: from 15 to 75% more NFTs were shown and more distinctly with the modified Bielschowsky stain than with the Bodian stain. Many of the NFTs in both cases were of eosinophilic and less argentophilic type. Although the NFTs were not counted, the thioflavin S stain seemed to have no apparent advantage over the modified Bielschowsky stain in the demonstration of NFTs.     

Activation mechanism of brain microglia in patients with diffuse neurofibrillary tangles with calcification: a comparison with Alzheimer disease

Diffuse neurofibrillary tangles with calcification (DNTC) is an atypical dementia and is characterized pathologically by diffuse neurofibrillary tangles (NFTs) without senile plaques (SPs). In this study, we investigated the distribution of human leukocyte antigen (HLA)-DR-positive activated microglia in postmortem brain tissue of six patients with DNTC and six patients with Alzheimer disease (AD). HLA-DR-positive activated microglia were observed to associate with SPs in AD. In the DNTC brain, which lacks SPs, HLA-DR-positive microglia were mainly accumulated around weakly tau-positive NFTs, which were also positive for anti-amyloid-P and anti-C3d antibodies. The results of this study suggest that the complement pathway is also activated in the DNTC brain and that immune and inflammatory responses, including microglia activation, may occur around extracellular NFTs in DNTC patients.     

Neurofibrillary tangles in the neurons of spinal dorsal root ganglia of patients with progressive supranuclear palsy

Summary Neurofibrillary tangles (NFTs) occur in neurons of human central nervous system (CNS) both in aged subjects and patients with several degenerative diseases, with a certain topographical predilection. In surveying the NFT distribution in nervous tissue of patients with progressive supranuclear palsy (PSP), we found silver-positive fibrillary tangles in the neurons of dorsal root ganglia (DRG) in two of five patients. By immunohistochemistry, these tangles were stained with antibodies to human tau protein, paired helical filaments (PHFs) and ubiquitin. Electron microscopy revealed that they were mainly composed of PHFs that were morphologically indistinguishable from PHFs in the NFTs of CNS typically seen in Alzheimer's disease brains. Our data demonstrate for the first time that the neurons of DRG produce NFTs in PSP and suggest that the pathological process(es) leading to tangle formation can occur in the neurons of the peripheral nervous system in this disease condition.Supported in part by Grant-in-Aid for Scientific Research of the Ministry of Education, Science and Culture of Japan     

A comparative study of a silver stain and monoclonal antibody reactions on Alzheimer''s neurofibrillary tangles.

Serial sections of brains of eight cases with Alzheimer's disease were stained by methods utilising silver and three different monoclonal antibodies. The numbers of Alzheimer's neurofibrillary tangles (NFT) were counted in the silver stained sections and compared with the numbers detected by three monoclonal anti-NF antibodies: RT97, BF10 and 8D8. The monoclonal antibody (Mab) BF10 demonstrated NFTs more clearly than Mab 8D8, but neither detected as many tangles as the silver staining method. Mab RT97 reacted well with NFTs in freshly processed specimens but not following prolonged fixation.     

Tau pathology in diffuse neurofibrillary tangles with calcification (DNTC): biochemical and immunohistochemical investigation

Diffuse neurofibrillary tangles with calcification (DNTC) represents a primary and sporadic presenile dementia that is characterized by temporal or fronto-temporal atrophy with diffuse neurofibrillary tangles (NFTs), neuropil threads and Fahr-type calcification without senile plaques. We examined the tau pathology in five autopsy cases of DNTC by immunoblotting and immunohistochemistry using phosphorylation-dependent and -independent anti-tau antibodies. The pattern of staining for different epitopes of beta-amyloid (A beta) was also investigated. NFTs were immunopositive with all the anti-tau antibodies used in this study. On the immunoblots, sarkosyl-insoluble tau appeared as three major bands of 60, 64 and 68 kDa, and as a minor band at 72 kDa. The majority of extracellular NFTs were weakly immunopositive only with the antibody recognizing the 40 carboxyl-terminal of A beta in DNTC. These results suggest that Alzheimer's disease-like tau pathology could exist independently of A beta deposits in DNTC.     

Spinal cord neurofibrillary tangles of Guamanian amyotrophic lateral sclerosis and parkinsonism-dementia complex: an immunohistochemical study

We studied the topographic distribution and immunohistochemical characteristics of spinal cord neurofibrillary tangles (NFTs) in 6 patients with Guamanian amyotrophic lateral sclerosis (ALS) and 6 patients with parkinsonismdementia complex (PD) on Guam, using antibodies to tau protein and ubiquitin. The NFTs were immunoreactive with both antibodies, but staining for tau was more pronounced. As identified by this reactivity, all the Guamanian ALS and PD cases examined showed spinal cord NFTs. The posterior horn had the most and the anterior horn the least. In the posterior horn the NFTs were located mainly in the marginal areas. Large anterior horn cells showed few, if any, NFTs. In addition to perikaryal NFTs, we observed tau-reactive neurites. Our results provide evidence that spinal cord NFTs are not uncommon in Guamanian ALS and PD on Guam and that they are more numerous than previously found with conventional methods.     

Phosphorylated tau: toxic, protective, or none of the above

Identification of phosphorylated tau as the major protein component of neurofibrillary tangles (NFTs) led to the concept that phosphorylated tau was inherently toxic and, as such, intimately involved in Alzheimer's disease (AD) pathogenesis. While superficially logical, this construct ignores a number of key findings in AD, including i) that NFTs are encountered in viable neurons until late stage disease; ii) that NFTs persist within the neuronal cytoplasm for decades; iii) that NFTs are encountered, sometimes in significant numbers, in cognitively intact elderly; and iv) that neurons with NFTs contain normal content and structure of microtubules. Experimental data in transgenic animal models has further demonstrated that NFTs accumulate in neurons in spite of tau suppression and behavior normalization. These data call into question the inherent toxicity of phosphorylated tau, seemingly leaving the only viable hypothesis of the ad hoc "toxic intermediate" phosphorylated tau concept. However, since we also know that phosphorylated tau sequesters redox active heavy metals and protects against oxidative stress, here we suggest that phosphorylated tau serves a protective role against cellular toxicity.     

Early accumulation of p62 in neurofibrillary tangles in Alzheimer's disease: possible role in tangle formation

Neurofibrillary tangles (NFTs) and neuritic plaques (NPs) are two major histopathological lesions in Alzheimer's disease (AD). Although their aetiological relationship is unclear, both NFTs and dystrophic neurites of NPs display immunoreactivity for ubiquitin. This suggests that dysfunction in ubiquitin-mediated proteolysis and the resulting accumulation of ubiquitin-conjugated proteins may contribute to the origination of dystrophic neurites and NFTs. We recently discovered a novel constituent of neuropathological protein aggregates, ubiquitin-binding protein p62, with evidence that the accumulation of ubiquitin-conjugated proteins and p62 into cytoplasmic inclusions might be interconnected. In the present work we examined in detail the role of p62 in AD-type pathology, i.e. NFTs, NPs and neuropil threads. Using immunohistochemistry for p62, ubiquitin and hyperphosphorylated tau, we analysed parietal cortical samples of 15 clinicopathologically verified AD cases and nine nondemented aged subjects with abundant NPs. We found that p62 immunoreactivity appears early during neurofibrillary pathogenesis and is invariably and stably present in NFTs. In contrast, p62 was absent or barely detectable in neuropil threads. Furthermore, NP-associated dystrophic neurites were generally devoid of p62, regardless of their content of hyperphosphorylated tau and/or ubiquitin. The results suggest that early involvement of p62 might be critical in the aggregation of hyperphosphorylated tau into perikaryal aggregates, i.e. NFTs.     

The overlap of corticobasal degeneration and Alzheimer changes: An autopsy case

The aspects of various neurodegenerative diseases can be observed overlapping with each other during autopsy. Corticobasal degeneration (CBD) is a rare neurodegenerative disease, whereas Alzheimer disease (AD) is the most common cause of dementia. In this article, we present the combination of CBD and AD in an autopsy case. The patient, an 82‐year‐old right‐handed woman developed asymmetrical parkinsonism, visuospatial dysfunction and memory loss, as well as subsequent non‐influent aphasia over the past 10 years. The autopsy revealed characteristic CBD‐related pathology, ballooned neurons, globose tangles and astrocytic plaques, mainly in the frontal cortex and basal ganglia. The Alzheimer‐related pathology was also present concomitantly. Senile plagues deposited diffusively throughout the hippocampus and neocortices. Neurofibrillary tangles (NFTs) were more confined to the hippocampus. The autopsy demonstrated pathological overlap of CBD and AD, which therefore explained the clinical early development of dementia and parkinsonism. We should suspect the concurrence of various neurodegenerative disorders in any case with atypical or complex clinical manifestations. Tau pathology is a prominent feature in both CBD and AD. Such a combination would be a clue for the pathogenesis of various tauopathies.     

Alzheimer-type pathology in melanin-bleached sections of substantia nigra

Bleaching of melanin prior to Gallyas staining enabled us to detect an unexpectedly large number of neurofibrillary tangles (NFTs; 62 and 50 NFTs in the upper and the lower substantia nigra, respectively, mostly in the neuronal cytoplasm of the medial zona compacta) in brains of patients who had had Alzheimer's disease. Amyloid-like deposits were quite scarce. In Alzheimer's disease it has been commonly observed that other subcortical nuclei projecting widely to the cerebral cortex also contain a large number of NFTs, although they have few amyloid deposits. In these subcortical nuclei retrograde degeneration may initially affect intraneuronal processes, leading to the preferential development of NFTs in the neuronal cytoplasm.     

Intraneuronal and extracellular neurofibrillary tangles exhibit mutually exclusive cytoskeletal antigens

We examined the possibility that neurofibrillary tangles (NFTs) were heterogeneous in postmortem hippocampus from 22 patients with or without senile dementia of the Alzheimer type. Intraneuronal NFTs and extracellular, or "ghost," NFTs were recognized in situ by only one or the other of two monoclonal antibodies. The first monoclonal antibody, RMO87, stained only intraneuronal NFTs and is specific for phosphate-dependent epitopes in tau and the two high molecular weight neurofilament proteins. The second monoclonal antibody, 2.2B10, is specific for glial fibrillary acidic protein, and it stained only the RMO87-negative extracellular NFTs. Treatment of sections with alkaline phosphatase or sodium dodecyl sulfate, and the isolation of NFTs from hippocampus, did not expose RMO87 binding sites in extracellular NFTs. These observations indicate that neurofilament-like and tau-like epitopes can be lost from NFTs in situ, and that at least two populations of morphologically and immunochemically distinct NFTs exist.     

Influence of microglia and astrocyte activation in the neuroinflammatory pathogenesis of Alzheimer’s disease: Rational insights for the therapeutic approaches

Alzheimer's disease (AD), the most common progressive neurodegenerative disorder is characterized by the formation of extracellular amyloid plaques and intracellular neurofibrillary tangles (NFTs). Increasing evidences suggest a link between neuroinflammation and neuronal dysfunction in AD, orchestrated by the progressive activation of microglial cells and astrocytes with the consequent overproduction of proinflammatory molecules. The concomitant release of anti-inflammatory mediators antagonizes the inflammatory processes and leading to the severity of the AD pathology. The simultaneous detection of these inflammatory molecules in the pre-symptomatic stage may help in the early diagnosis of the AD. We have discussed the impact of microglia and astrocytic cells, the principal agents in the neuroinflammation process, in relation to the progression of the AD. Modulation of the risk factors and targeting of these immune mechanisms could lead to better therapeutic or preventive strategies for the AD. Further studies need to determine, how the inhibition of inflammatory factors could be used for the AD alternative therapies.     

Neurofibrillary tangles in human upper cervical ganglia

Summary Neurofibrillary tangles (NFTs) are one of the main pathological hallmarks of Alzheimer's disease or senile dementia, and are seen in the cerebral cortex and some other nuclei in the central nervous system (CNS). No NFTs have been reported in the human peripheral nervous system, although NFTs were recognized in the dorsal root ganglion of the aged rodents. We report here the presence of NFTs in the upper cervical ganglia (UCGs), but not in the stellate nor in the celiac ganglia, of an elderly patient, who was not demented and had only minimal senile changes in the CNS. Immunohistochemically the antibodies to microtubule-associated protein 2, paired helical filaments and ubiquitin stained positively the NFTs in the UCGs. On electron microscopic examination a periodical twisted pattern of the filaments was identified; these findings suggest that the NFTs of the UCGs have just the same properties as those of the cerebral cortex. This is the first report of the demonstration of NFTs in the peripheral ganglia and might contribute to the study of mechanism of NFT production.