~curo~'cicm'c l,cH,~,, 14~ (I
126
~) 12¢1
, 1992 Elsevier Scientific Publishers Ireland Ltd. All rights reserved 1~304-3940,'92/$ )5.(~ r
NSL 09174
Coexistence of paired helical filaments and glial filaments in astrocytic processes within ghost tangles Kenji Ikeda a, Chie H a g a a, H a r u h i k o A k i y a m a a, Koichi Kase b and Syuji Iritani b "Tokyo Institute of Psychiatry, Tokyo (Japan) and bTokyo Metropolitan Matsuzawa Hospital, Tokyo ( Japan j (Received 18 August 1992: Revised version received 22 September 1992; Accepted 24 September 1992)
Key words." Alzheimer's disease; Astrocyte; Ghost tangle; Paired helical filament Ultrastructural examination of ghost tangles in an autopsy case of long-term Alzheirner's disease revealed, in addition to degenerate neurites containing paired helical filaments (PHF), astrocytic processes which included PHF. This finding suggests either that astrocytes in ghost tangles possess the capacity to produce PHF or that PHF are incorporated into astrocytes by endocytosis.
Prominent astrocytic invasion [4, 7, 10] as well as microglial association [2, 5] have been noted in neurofibrillary tangles (NFT) which have entered the extracellular space and become ghost tangles. This glial association with NFT is thought to precipitate morphological and immunocytochemical modification of NFT [2, 5, 10]. We briefly report our observation of ghost tangles in an autopsy case of Alzheimer's disease, in which we noted the coexistence of paired helical filaments (PHF) and glial filaments within the same astrocytic processes. A female patient who presented the clinical features of Alzheimer's disease died at the age of 70 years after 8 years in the apallic state. The total duration of illness had been 17 years, and the patient had required considerable care. The brain weight at autopsy was 690 g. Microscopic findings were compatible with those of extremely advanced Alzheimer's disease. Paraffin-embedded, 5/.tm-thick sections of the temporal cortex including the hippocampal region were stained with antibodies of antitau-N (polyclonal antibody to human tau, which recognizes epitopes on the N-terminus of tau, was provided by Dr. Ihara) and anti-ubiquitin (mouse monoclonal, Chemicon) for immunocytochemical study. The ghost tangles were negative to anti-tau-N and anti-ubiquitin except for small granules (Fig. 1A,B). Such small granules have been reported to be degenerated neurites associated with ghost tangles [4, 10]. In contrast, the intra-
Correspondence." K. lkeda, Tokyo Institute of Psychiatry, 2-1-8, Kamikitazawa, Setagaya-ku, Tokyo 156. Japan.
neuronal NFT were stained with anti-tau-N and antiubiquitin. For electron microscopic study of ghost tangles, small tissue blocks from the subicular region, where all pyramidal cells had been changed into NFT-!aden neurons or ghost tangles, were cut at autopsy and fixed in 2% buffered glutaraldehyde and embedded in araldite. Electron microscopic observation revealed that the ghost tangles were incorporated of loosely arranged low electron-density straight tubules and numerous bundles of glial filaments (Fig. 2A). Sometimes, periodically constricted tubules, the structure of which coincided with that of PHF, coexisted with glial filaments within the same processes.
Fig. 1. Ghost tangles are visualized as negative silhouettes except for the area containing anti-tau-N-immunoreactive granules (A) and antiubiquitin immunopositive granules (B). These granules are thought to represent PHF-containing astrocytic processes in addition to degenerated neurites. A,B: ×500.
127
Fig. 2. A: a part of a ghost tangle is penetrated by numerous astrocytic processes, x12,000. B: at higher magnification, one of them is observed to contain both paired helical filaments and glial filaments, its limiting membrane contains a gap junction (arrowhead). Fragments of low electron density straight tubules (arrows) are scattered outside the glial processes, x42,500.
The surrounding limiting membrane of these processes occasionally h~ld a gap junction, and the processes were identified to be astrocytic. Constricted tubules seen in the astrocytic processes were more thick and electron density than the straight tubules of ghost tangles (Fig. 2B). Except for the ghost tangles, there were no astrocytic elements which contained PHF. Ghost tangles are frequently reported to be associated
with anti-tau or anti-ubiquitin immunopositive granules, and they had been ultrastructurally confirmed to be degenerated neurites containing P H F [10]. Our observation reveals, however, that at least a part of these granules is astrocytic. The coexistence of PHF and glial filaments in the same astrocytic process indicate either the endocytosis of tubules of ghost tangles or a de novo production of P H F by the astrocyte itself. Tubules in ghost tangles are
128 t h o u g h t to u n d e r g o some modification process by the glial system [2, 5, 10], and it is possible that astrocytic processes p h a g o c y t o s e extracellular tubules as foreign substances. However, such substances engulfed by a cell should be contained within vesicles [3], and it is therefore a q u a n d a r y that there is no limiting m e m b r a n e a r o u n d glial tubules. The glial tubules presented periodic constriction and differed m o r p h o l o g i c a l l y from the tow electron-density straight tubules observed outside the glial processes in the same ghost tangles. The second alternative, that P H F originate from the astrocytic process itself, is supported by recent reports o f tau i m m u n o r e a c tivity in astrocytes in Alzheimer-type dementia [8] and progressive supranuclear palsy, although the fine structure o f tau-immunoreactive tubules is straight and never shows periodic constriction [1, 9]. While, N a k a n o et al. [6] presented ultrastructural evidence o f astrocytic production o f P H F in the subicular region in severely advanced atypical Alzheimer's disease. These tau-immunoreactive astrocytes and P H F in astrocytes reportedly exist without any relation to ghost tangles. In our case, the Alzheimer's disease, t h o u g h clinically and pathologically typical, was extremely advanced. Astrocytes m a y have the capacity to p r o d u c e P H F under certain conditions, such as those in extremely advanced Alzheimer's disease, or in a distinctive structure such as a ghost tangle, in which both degenerative and proliferative processes transpire. It is necessary to examine ghost tangles in other cases to determine whether the presence o f P H F - c o n t a i n i n g astrocytic processes is a ubiquitous finding.
1 Amano, N., personal communication. 2 Cras, P., Kawai, M., Siedlak, S. and Perry, G., Microglia are associ.. ated with extracellular neurofibrillary tangles of Alzheimer disease, Brain Res., 558 (1991) 312-314. 3 Ghadially, F.N., Ultrastructural Pathology of the Cell and Matrix. A Text and Atlas of Physiological and Pathological Alterations in the Fine Structure of Cellular and Extracellular Components, 2nd edn., Butterworths, London, 1982, pp. 824. 4 Ikeda, K., Haga, C., Oyanagi, S., Iritani, S. and Kosaka, K., Ultrastructural and immunohistochemical study of degenerate neuritebearing ghost tangles, J. Neurol., 239 (1992) 191 194. 5 Ikeda, K., Akiyama, H., Haga, C. and Haga, S., Evidence that neurofibrillary tangles undergo glial modification, Acta Neuropathol., in press. 6 Nakano, 1., Iwatsubo, T., Otsuka, N., Kamei, M., Matsumura, K. and Mannen, T., Paired helical filaments in astrocytes: electron microscopy and immunohistochemistr), in a case of atypical Alzheimer's disease, Acta Neuropathol., 83 (1992) 228-232. 7 Okamoto, K., Hirano, A., Yamaguchi, H. and Hirai, S., The fine structure of eosinophilic stage of Alzheimer's neurofibrillary tangles, J. Clin. Electron Microsc., 16 (1983) 77 82. 8 Papasozomenos, S.C., Tau protein immunoreactivity in dementia of Alzheimer type: II. Electron microscopy and pathogenic implications. Effects of fixation on morphology of the Alzheimer's abnormal filaments, Lab. Invest., 60 (1989) 375 389. 9 Yamada, T., McGeer, P.L. and McGeer, E.G., Appearance of paired nucleated, Tau-positive glia in patients with progressive supranuclear palsy brain tissue, Neurosci. lett., 135 (1992) 99- 102. 10 Yamaguchi, H., Nakazato, Y., Kawarabayashi, T., lshiguro, K., Ihara, Y., Morimatsu, M. and Hirai, S., Extracellular neurofihrillary tangles associated with degenerating neurites and neuropil threads in Alzheimer-type dementia, Aeta Neuropathol., 81 (1991) 603-609.
126
~) 12¢1
, 1992 Elsevier Scientific Publishers Ireland Ltd. All rights reserved 1~304-3940,'92/$ )5.(~ r
NSL 09174
Coexistence of paired helical filaments and glial filaments in astrocytic processes within ghost tangles Kenji Ikeda a, Chie H a g a a, H a r u h i k o A k i y a m a a, Koichi Kase b and Syuji Iritani b "Tokyo Institute of Psychiatry, Tokyo (Japan) and bTokyo Metropolitan Matsuzawa Hospital, Tokyo ( Japan j (Received 18 August 1992: Revised version received 22 September 1992; Accepted 24 September 1992)
Key words." Alzheimer's disease; Astrocyte; Ghost tangle; Paired helical filament Ultrastructural examination of ghost tangles in an autopsy case of long-term Alzheirner's disease revealed, in addition to degenerate neurites containing paired helical filaments (PHF), astrocytic processes which included PHF. This finding suggests either that astrocytes in ghost tangles possess the capacity to produce PHF or that PHF are incorporated into astrocytes by endocytosis.
Prominent astrocytic invasion [4, 7, 10] as well as microglial association [2, 5] have been noted in neurofibrillary tangles (NFT) which have entered the extracellular space and become ghost tangles. This glial association with NFT is thought to precipitate morphological and immunocytochemical modification of NFT [2, 5, 10]. We briefly report our observation of ghost tangles in an autopsy case of Alzheimer's disease, in which we noted the coexistence of paired helical filaments (PHF) and glial filaments within the same astrocytic processes. A female patient who presented the clinical features of Alzheimer's disease died at the age of 70 years after 8 years in the apallic state. The total duration of illness had been 17 years, and the patient had required considerable care. The brain weight at autopsy was 690 g. Microscopic findings were compatible with those of extremely advanced Alzheimer's disease. Paraffin-embedded, 5/.tm-thick sections of the temporal cortex including the hippocampal region were stained with antibodies of antitau-N (polyclonal antibody to human tau, which recognizes epitopes on the N-terminus of tau, was provided by Dr. Ihara) and anti-ubiquitin (mouse monoclonal, Chemicon) for immunocytochemical study. The ghost tangles were negative to anti-tau-N and anti-ubiquitin except for small granules (Fig. 1A,B). Such small granules have been reported to be degenerated neurites associated with ghost tangles [4, 10]. In contrast, the intra-
Correspondence." K. lkeda, Tokyo Institute of Psychiatry, 2-1-8, Kamikitazawa, Setagaya-ku, Tokyo 156. Japan.
neuronal NFT were stained with anti-tau-N and antiubiquitin. For electron microscopic study of ghost tangles, small tissue blocks from the subicular region, where all pyramidal cells had been changed into NFT-!aden neurons or ghost tangles, were cut at autopsy and fixed in 2% buffered glutaraldehyde and embedded in araldite. Electron microscopic observation revealed that the ghost tangles were incorporated of loosely arranged low electron-density straight tubules and numerous bundles of glial filaments (Fig. 2A). Sometimes, periodically constricted tubules, the structure of which coincided with that of PHF, coexisted with glial filaments within the same processes.
Fig. 1. Ghost tangles are visualized as negative silhouettes except for the area containing anti-tau-N-immunoreactive granules (A) and antiubiquitin immunopositive granules (B). These granules are thought to represent PHF-containing astrocytic processes in addition to degenerated neurites. A,B: ×500.
127
Fig. 2. A: a part of a ghost tangle is penetrated by numerous astrocytic processes, x12,000. B: at higher magnification, one of them is observed to contain both paired helical filaments and glial filaments, its limiting membrane contains a gap junction (arrowhead). Fragments of low electron density straight tubules (arrows) are scattered outside the glial processes, x42,500.
The surrounding limiting membrane of these processes occasionally h~ld a gap junction, and the processes were identified to be astrocytic. Constricted tubules seen in the astrocytic processes were more thick and electron density than the straight tubules of ghost tangles (Fig. 2B). Except for the ghost tangles, there were no astrocytic elements which contained PHF. Ghost tangles are frequently reported to be associated
with anti-tau or anti-ubiquitin immunopositive granules, and they had been ultrastructurally confirmed to be degenerated neurites containing P H F [10]. Our observation reveals, however, that at least a part of these granules is astrocytic. The coexistence of PHF and glial filaments in the same astrocytic process indicate either the endocytosis of tubules of ghost tangles or a de novo production of P H F by the astrocyte itself. Tubules in ghost tangles are
128 t h o u g h t to u n d e r g o some modification process by the glial system [2, 5, 10], and it is possible that astrocytic processes p h a g o c y t o s e extracellular tubules as foreign substances. However, such substances engulfed by a cell should be contained within vesicles [3], and it is therefore a q u a n d a r y that there is no limiting m e m b r a n e a r o u n d glial tubules. The glial tubules presented periodic constriction and differed m o r p h o l o g i c a l l y from the tow electron-density straight tubules observed outside the glial processes in the same ghost tangles. The second alternative, that P H F originate from the astrocytic process itself, is supported by recent reports o f tau i m m u n o r e a c tivity in astrocytes in Alzheimer-type dementia [8] and progressive supranuclear palsy, although the fine structure o f tau-immunoreactive tubules is straight and never shows periodic constriction [1, 9]. While, N a k a n o et al. [6] presented ultrastructural evidence o f astrocytic production o f P H F in the subicular region in severely advanced atypical Alzheimer's disease. These tau-immunoreactive astrocytes and P H F in astrocytes reportedly exist without any relation to ghost tangles. In our case, the Alzheimer's disease, t h o u g h clinically and pathologically typical, was extremely advanced. Astrocytes m a y have the capacity to p r o d u c e P H F under certain conditions, such as those in extremely advanced Alzheimer's disease, or in a distinctive structure such as a ghost tangle, in which both degenerative and proliferative processes transpire. It is necessary to examine ghost tangles in other cases to determine whether the presence o f P H F - c o n t a i n i n g astrocytic processes is a ubiquitous finding.
1 Amano, N., personal communication. 2 Cras, P., Kawai, M., Siedlak, S. and Perry, G., Microglia are associ.. ated with extracellular neurofibrillary tangles of Alzheimer disease, Brain Res., 558 (1991) 312-314. 3 Ghadially, F.N., Ultrastructural Pathology of the Cell and Matrix. A Text and Atlas of Physiological and Pathological Alterations in the Fine Structure of Cellular and Extracellular Components, 2nd edn., Butterworths, London, 1982, pp. 824. 4 Ikeda, K., Haga, C., Oyanagi, S., Iritani, S. and Kosaka, K., Ultrastructural and immunohistochemical study of degenerate neuritebearing ghost tangles, J. Neurol., 239 (1992) 191 194. 5 Ikeda, K., Akiyama, H., Haga, C. and Haga, S., Evidence that neurofibrillary tangles undergo glial modification, Acta Neuropathol., in press. 6 Nakano, 1., Iwatsubo, T., Otsuka, N., Kamei, M., Matsumura, K. and Mannen, T., Paired helical filaments in astrocytes: electron microscopy and immunohistochemistr), in a case of atypical Alzheimer's disease, Acta Neuropathol., 83 (1992) 228-232. 7 Okamoto, K., Hirano, A., Yamaguchi, H. and Hirai, S., The fine structure of eosinophilic stage of Alzheimer's neurofibrillary tangles, J. Clin. Electron Microsc., 16 (1983) 77 82. 8 Papasozomenos, S.C., Tau protein immunoreactivity in dementia of Alzheimer type: II. Electron microscopy and pathogenic implications. Effects of fixation on morphology of the Alzheimer's abnormal filaments, Lab. Invest., 60 (1989) 375 389. 9 Yamada, T., McGeer, P.L. and McGeer, E.G., Appearance of paired nucleated, Tau-positive glia in patients with progressive supranuclear palsy brain tissue, Neurosci. lett., 135 (1992) 99- 102. 10 Yamaguchi, H., Nakazato, Y., Kawarabayashi, T., lshiguro, K., Ihara, Y., Morimatsu, M. and Hirai, S., Extracellular neurofihrillary tangles associated with degenerating neurites and neuropil threads in Alzheimer-type dementia, Aeta Neuropathol., 81 (1991) 603-609.
