Toshio Kawamata

Distribution of clusterin in Alzheimer brain tissue

The immunohistochemical distribution of clusterin (SP40,40, SGP-2) was determined in Alzheimer disease (AD) and normal human brain tissue and compared with the distributions of vitronectin, protectin and the complement membrane attack complex (MAC). Antibodies to all four proteins showed staining of dystrophic neurites and neuropil threads in AD tissue, and residual serum in normal tissue, but only antibodies to clusterin and vitronectin strongly stained amyloid deposits in senile plaques. The clusterin antibody also showed punctate staining of some normal appearing AD pyramidal neurons, and very scattered staining of intracellular neurofibrillary tangles. Clusterin, vitronectin and protectin are all believed to inhibit membrane insertion by the MAC, and these data are consistent with upregulation of all three proteins in response to MAC formation in AD, and with a neuronal origin of clusterin.

Expression of monoamine oxidase B activity in astrocytes of senile plaques

SummaryMonoamine oxidase (MAO) histochemistry has been performed in brains from patients with dementia of Alzheimer type (DAT) and aged controls. Conspicuous MAO-positive cell clusters were frequently observed in the amygdala, hippocampus, and insular cortex in the brains of DAT. Double staining with glial fibrillary acidic protein immunohistochemistry revealed that the clusterforming MAO-positive cells were astrocytes. Using Bielschowskys method, Congo red and thioflavin S counterstaining, this astrocytic mass was shown to be associated with senile plaques. By the enzyme inhibition experiment, MAO activity in senile plaques was revealed to be of type B. The present results clearly indicate that MAO-B activity is expressed in fibrillary astrocytes in or around senile plaques, suggesting that these astrocytes metabolize exogenous amines in senile plaques.

Loss of basic fibroblast growth factor in substantia nigra neurons in Parkinson's disease.

Basic fibroblast growth factor (bFGF) has a neurotrophic effect on mesencephalic dopaminergic neurons in vitro and in vivo. To explore whether an abnormality in bFGF expression occurs in Parkinsons disease (PD), we examined the substantia nigra (SN) of six PD and eight control cases immunohistochemically using a monoclonal antibody to bFGF. The mean number of melanin-positive neurons in sections of PD SN was 30.3% of the control mean, but the number of bFGF-immunopositive neurons was only 4.7% of the control mean. bFGF-immunorcactivity was present in only 8.2% of PD, but in 93.7% of control melanin-positive neurons. These results suggest a profound depletion of bFGF in surviving dopaminergic neurons of the SN in PD, and this depletion may be related to the disease process.

Immunohistochemical localization of vitronectin, its receptor and beta-3 integrin in Alzheimer brain tissue

The vitronectin receptor (VNR) is an integrin which consists of an alpha-subunit which can associate with multiple beta-subunits. A polyclonal antibody to this integrin weakly stained resting microglia in white matter of control brain and strongly stained reactive microglia in both gray and white matter of Alzheimer brain. This antibody, as well as a monoclonal antibody to beta 3, stained some platelets in capillaries of both control and Alzheimer tissue. When the antiserum was immunoabsorbed with a preparation enriched in the alpha-chain of the vitronectin receptor, it failed to stain microglial cells, but continued to stain platelets. When it was immunoabsorbed with a peripheral blood platelet preparation, all immunostaining was abolished. These results indicate that the vitronectin receptor of microglia is associated with a beta-chain different from beta 3, but that beta 3 is expressed by some platelets in brain capillaries. An antibody to vitronectin itself stained senile plaques and neurofibrillary tangles in Alzheimer entorhinal cortex, but only residual plasma in control tissue. Senile plaques positive for vitronectin had microglial cores strongly positive for the vitronectin receptor. The high levels of vitronectin receptor on reactive microglia in areas containing extracellular vitronectin suggest the possibility that vitronectin is serving an opsonizing function for microglial phagocytosis.

Detection of the membrane inhibitor of reactive lysis (CD59) in diseased neurons of Alzheimer brain

The membrane inhibitor of reactive lysis (MIRL) protects host cells from complement-mediated lysis. It was detected immunohistochemically in tangled neurons and dystrophic neurites of Alzheimer disease (AD) tissue in a pattern highly similar to that observed for the membrane attack complex of complement, C5b-9. MIRL was also detected in cultured IMR-32 neuroblastoma cells. The mRNA for MIRL was detected in RNA extracts of both AD and normal brain. These data provide the first evidence of brain neuronal expression of MIRL and its upregulation in neurons exposed to complement attack. They are consistent with the previously advanced hypothesis that complement-mediated neuronal injury may play a role in AD.

Vimentin immunoreactivity in normal and pathological human brain tissue

SummaryVimentin immunoreactivity was examined in brain tissues from non-neurological and various human central nervous system disease cases. In all brain tissues examined, vimentin immunoreactivity was intensely positive in ependymal cells and subpial tissues, and weakly positive in some capillaries and some white matter astrocytes. In affected areas of Alzheimers disease (AD), Picks disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and cerebral infarction cases, numerous intensely vimentin-immunopositive astrocytes of both protoplasmic and fibrous morphology were demonstrated. A few such astrocytes were also observed in Parkinsons disease and progressive supranuclear palsy. ALS, MS and infarction brains also had numerous, strongly vimentin-positive, round and fat-laden microglia/macrophages. In AD and ALS, a few reactive microglia with irregularly enlarged shapes were vimentin positive. In AD, they were almost exclusively related to senile plaques.

Periodic acid-Schiff (PAS)-positive, granular structures increase in the brain of senescence accelerated mouse (SAM)

SummaryAbnormal granular structures, which stained positively with periodic acid-Schiff (PAS-positive granular structures; PGS), were observed in the brain of senescence accelerated mouse (SAM). They were small, round to ovoid, homogenous structures measuring up to 5 μm in diameter and usually grouped in clusters. PGS were localized in the hippocampus, piriform cortices, olfactory tubercle, nucleus of the trapezoid body, and cerebellar cortices. Quantitative analysis revealed that PGS remarkably increased in the hippocampus of SAM-P/8, a substrain of SAM, with advancing age, although a few PGS also appeared in the aged control mice, SAM-R/1 and DDD. Their histochemical nature, morphological features and distribution pattern were different from those of corpora amylacea and other similar bodies. A close anatomical relationship between PGS and glial fibrillary acidic protein-positive astrocytes was inferred from immunohistochemical studies. PGS is considered to be one of the morphological manifestations of senescence in mice brains, and are found to occur more numerously in the brains of learning or memory deficit mice, SAM-P/8.

Immunohistochemical study of α2 Macroglobulin receptor in Alzheimer and control postmortem human brain

Localization of the alpha 2 macroglobulin receptor (alpha 2MR) was studied in postmortem human brain tissue of Alzheimer disease (AD) and age-matched control cases with a monoclonal antibody (A2MR alpha 2) to the receptor. In control cases alpha 2MR was detected in neurons, glia, and some capillaries. Neuronal staining was most conspicuous in the hippocampus and entorhinal cortex. In AD, alpha 2MR immunoreactivity was enhanced. The staining intensity of some neurons was increased, as was the number of positive glial cells. In addition, senile plaques, tangles, and dystrophic neurites were strongly stained. These results suggest that alpha 2MR is involved in AD pathology.

Morphological diversities of CD44 positive astrocytes in the cerebral cortex of normal subjects and patients with Alzheimer's disease.

The localization of CD44 was investigated immunohistochemically in postmortem human brain tissue of control subjects and patients with Alzheimers disease. CD44 is a multifunctional cell surface glycoprotein that serves as a receptor for hyaluronic acid, collagen types I and VI, and mucosal vascular addressin. In gray matter, it was found to be associated with some astrocytes of both protoplasmic and fibrous morphology. These positively stained astrocytes were most frequently observed in association with blood vessels, and had morphologies that were highly comparable to those described with the Golgi technique. Double immunostaining for CD44 and glial fibrillary acidic protein (GFAP) revealed that a significant number of these astrocytes were positive for both antigens. However, GFAP staining was mostly confined to the cell somata and proximal processes, while CD44 staining extended to a rich and extensive array of processes. Occasional CD44 positive cells of spherical morphology with a few thin varicose processes were observed. Their processes formed thick terminations on blood vessels, suggesting that these cells are a special class of astrocyte. In Alzheimers disease brain, the number of CD44 positive astrocytes increased dramatically. These data suggest that astrocytes have very extensive branching patterns, which are reflected by CD44 staining patterns. CD44 may be an important adhesion molecule for these astrocytic processes.

NEUROPATHOLOGICAL STUDIES ON STRAINS OF SENESCENCE-ACCELERATED MICE (SAM) WITH AGE-RELATED DEFICITS IN LEARNING AND MEMORY

In a series of inbred Senescence-Accelerated mice (SAM) strains, accelerated-senescence prone SAMP substrains show early onset and rapid advancement of senescence. SAMP8 and SAMP10, in particular, exhibit a significant age-related deterioration in memory and learning for passive and active avoidance tasks with, respectively, a low and high incidence of systemic senile amyloidosis. In the brains of both SAMP8 and SAMP10 strains, we have found numerous morphological alterations. Here we review the changes seen in both neuronal or glial components in SAMP8/P10 brains. They may serve as markers of the neuronal degeneration leading to the deficits in learning and memory.