Dementia, gliosis and expression of the small heat shock proteins hsp27 and alpha B-crystallin in Parkinson's disease.

Cognitive impairment and dementia are common in the later stages of Parkinson's disease (PD). Neuropathological examination of demented PD (PDD) patients often reveals changes that are typical of Alzheimer's disease (AD). In AD, there is a massive reactive gliosis and increased expression of the small heat shock proteins (hsp) hsp27 and alpha B-crystallin. Since these proteins are characteristic for reactive astrocytes in AD, we investigated their expression in the brains of PDD patients. The results were compared with those obtained in the brains of non-demented PD patients. We found (1) no detectable expression of hsp in PD without dementia, and low expression in PD with mild dementia; (2) reactive gliosis and increased expression of hsp in the cortex of PDD brains; (3) a strong association between hsp immunoreactivity and the severity of the AD-specific changes, especially with the number of tangles in the hippocampus; (4) a distinct immunoreaction of alpha B-crystallin in microglia in the substantia nigra and in the hippocampus in PDD. These results indicate that astrocytes react to the disease conditions in AD and in PDD in a similar way, namely by the increased expression of small heat shock proteins, and present additional evidence for the thesis that the pathology of the dementia in PD is related to that in AD.

The molecular chaperone alphaB-crystallin enhances amyloid beta neurotoxicity.

Amyloid beta (Abeta) is a 40- to 42-residue peptide that is implicated in the pathogenesis of Alzheimer's Disease (AD). As a result of conformational changes, Abeta assembles into neurotoxic fibrils deposited as 'plaques' in the diseased brain. In AD brains, the small heat shock proteins (sHsps) alphaB-crystallin and Hsp27 occur at increased levels and colocalize with these plaques. In vitro, sHsps act as molecular chaperones that recognize unfolding peptides and prevent their aggregation. The presence of sHsps in AD brains may thus reflect an attempt to prevent amyloid fibril formation and toxicity. Here we report that alphaB-crystallin does indeed prevent in vitro fibril formation of Abeta(1-40). However, rather than protecting cultured neurons against Abeta(1-40) toxicity, alphaB-crystallin actually increases the toxic effect. This indicates that the interaction of alphaB-crystallin with conformationally altering Abeta(1-40) may keep the latter in a nonfibrillar, yet highly toxic form.

Neuronal anion exchange proteins in Alzheimer's disease pathology.

Anion exchange (AE) proteins are present in human neurons in the brain. Immunohistochemical data indicate that their apparent expression level increases with age, and especially with degeneration in Alzheimer's disease-affected brain areas. The increase in immunoreactivity is probably caused by changes in AE structure that lead to an increased accessibility of hitherto hidden epitopes. These epitopes correspond to regions in the membrane domain that are involved in generation of senescent cell-specific antigen from AE1 in aging erythrocytes. Elucidation of the molecular nature of these changes and the underlying mechanisms will lead to insight in the processes that govern aging- and degeneration-associated perturbation of membrane integrity. The functional consequences of changes in AE structure may range from acidosis and disturbance of cytoskeleton integrity to untimely or impaired recognition of neurons by microglia.

Heat shock, but not the reactive state per se, induces increased expression of the small stress proteins hsp25 and alpha B-crystallin in glial cells in vitro.

The stress proteins hsp25 and alpha B-crystallin are found in increased concentrations in reactive astrocytes of brains undergoing neurodegeneration. In order to characterize this reaction, we investigated the expression of hsp25 and alpha B-crystallin during growth and after stress (heat shock) in glial cells in vitro. In primary rat brain cultures, hsp25 was present in actively dividing astrocytes that were positive for glial fibrillary acidic protein. alpha B-crystallin was found predominantly in oligodendrocytes. Heat shock resulted in increased concentrations of hsp25 and alpha B-crystallin in astrocytes, without any detectable changes in intracellular localization, as detectable with confocal laser microscopy. These results indicate that a neurodegeneration-related increase of the small stress proteins in astrocytes in independent of gliosis per se, and may be a disease-related event.

Involvement of neuronal anion exchange proteins in cell death in Alzheimer's disease.

Anion exchange (AE) proteins are present in human neurons in the brain. Immunohistochemical data indicate that their apparent expression level increases with age, and especially with degeneration in Alzheimer's disease-affected brain areas. The increase in immunoreactivity is probably caused by changes in AE structure that lead to an increased accessibility of hitherto hidden epitopes. These epitopes correspond to regions in the membrane domain that are involved in generation of senescent cell-specific antigen from AE1 in aging erythrocytes. Elucidation of the molecular nature of these changes and the underlying mechanisms, will lead to insight in the processes that govern aging- and degeneration-associated perturbation of membrane integrity. AE-mediated chloride/bicarbonate exchange is a major component in the regulation of intracellular pH. The functional consequences of changes in AE structure may range from acidosis, disturbance of cytoskeleton integrity, and untimely or impaired recognition of cells by components of the immune system, such as microglia. A molecular and physiological description of these changes will establish AE proteins as valuable tools in elucidating the processes of normal aging, and the disturbances in aging-related diseases such as Alzheimer's disease.

Anion exchange proteins and regulation of intracellular pH in cultured rat astrocytes and neurones.

We used primary cultures of rat hippocampal tissue to estimate the contribution of anion exchange (AE) proteins to the regulation of intracellular pH in neurones and astrocytes. After induction of acidosis, neonatal rat astrocytes were able to restore the intracellular pH in the absence of extracellular bicarbonate. Neonatal neurones, however, were able to recover from acidosis only when bicarbonate was present in the extracellular medium. This recovery was inhibited by inhibition of anion exchange and was independent of the presence of sodium ions. Antibodies against AE proteins reacted predominantly with neurones. These data suggest that neurones in particular are dependent on functional AE proteins for the maintenance of their intracellular pH.

Implications of aging- and degeneration-related changes in anion exchange proteins for the maintenance of neuronal homeostasis.

Fourier-transform infrared spectroscopy was applied to examine the nature and extent of changes in membrane composition and structure during the aging process of the human erythrocyte. Analysis of the Amide I region (1700-1600 cm-1) indicates an aging-related decrease in alpha-helical structure with a concomitant increase in beta-structure. These changes can be explained by structural changes in the erythrocyte anion exchanger (band 3 or AE1) molecules, that may be caused by fragmentation, but not by aggregation. Immunohistochemical analysis of human brain tissue shows an increase in neuronal AE protein expression with age and suggests an additional increase in Alzheimer's disease. Biochemical analyses indicate that the latter may be caused by conformational changes in the AE membrane domain that are similar to those observed in AE1 during erythrocyte aging. AE proteins provide a binding site for the cytoskeleton in neurons, and AE-catalyzed chloride/bicarbonate exchange plays a major role in maintenance of neuronal pH. Thus, changes in AE structure are likely to contribute to loss of neuron homeostasis during aging and in neurodegenerative diseases.

Anion exchange proteins are a component of corpora amylacea in Alzheimer disease brain.

Corpora amylacea (CAm) are amorphous structures that increase in number in the brains of patients with neurodegenerative diseases. We found abundant CAm in the brains of Alzheimer disease (AD) patients. We show here that proteins of the anion exchanger (AE) gene family, related to erythrocyte band 3, are present in CAm. The presence of AE epitopes in CAm may be related to the presence of AE proteins in membranes of neurones, and their altered expression level in degenerating neurones in AD brains. Whereas the distribution of immunoreactivity was uniform over the CAm in control brains, there was much more variation in staining of CAm core and peripheral structures in AD brains. Our data support the suggestion that accumulation of altered neuronal membrane proteins may be involved in the pathogenesis of CAm in AD.

Occurrence of lamellar bodies in the rat brain organotypic cultures in normal and pathological conditions.

Lamellar bodies (LB) represent an intracytoplasmic organelles of the cells of different origin and various organs. Their exact function is not known. It has been recently suggested that these organelles may play a role in the protein synthesis and regulation of gene expression. Increased number of LB has been demonstrated in differentiating and growing cells. It suggests their functional relation to enhanced metabolism of the cells. Such conditions for cells establish a tissue culture. We have examined organotypic rat brain cultures maintained under standard conditions, and subsequently exposed to anoxia and neurotoxins: kainic and quinolinic acid. In normal conditions LB were occasionally found in neurons. Their number significantly increased in damaged neurons in the experimental conditions. They have also appeared in some damaged astrocytes. We postulate that LB in the brain are connected with cell degeneration. Their origin from rough endoplasmic reticulum is demonstrated.

Congenital muscular dystrophy and severe central nervous system atrophy in two siblings.

Severe degenerative features of the nervous system of a hitherto unknown kind, associated with a neuromuscular disorder with histopathological features of congenital muscular dystrophy, are reported in two female siblings. The clinical profile was characterized by generalized hypotonia followed by spastic tetraplegia, contractures, polyneuropathy, lack of cognitive development and progressive microcephaly. There as no involvement of the eyes. Neuropathological examination of the brain of one sibling, who died at the age of 30 months, revealed subtotal loss of neurons in the cerebral and cerebellar cortex and in the ventral pons, and secondary loss of myelin in the cerebral and cerebellar subcortical white matter. Sural nerve biopsy in the other sibling, who had a similar neurological affection, showed a lack of large myelinated fibers.

Polyglucosan bodies in brain tissue: a systematic study.

The relation between age, sex and presence of polyglucosan bodies in the brain has been systematically studied in 64 patients who did not suffer from neurological brain disorders and in 2 cases with Lafora's disease. In the normal brain the number of polyglucosan bodies is related to increasing age. Under the age of 40, polyglucosan bodies can be found sporadically in cases without a neurological disorder, but in the cases of Lafora's disease their number is uncomparatively higher. A sex relation has not been found.

Expression of small heat-shock protein hsp 27 in reactive gliosis in Alzheimer disease and other types of dementia.

Immunohistochemical and immunoblotting analysis of brain tissue of Alzheimer's disease (AD) patients showed highly induced expression of the small heat-shock protein hsp 27 in affected cortex. Expression of hsp 27 was present in a large number of proliferating astrocytes. The highest expression was exhibited by degenerative astrocytes in the areas rich in senile plaques. Neurofibrillary tangles, Hirano bodies and some hippocampal neurons were also positive. Expression of hsp 27 increased with the severity of AD-specific morphological changes, and with the duration of dementia. In control brains immunoreaction was restricted to the vessels and to occasional astrocytes in the white matter. Similar patterns of immunoreactivity were present in cases without dementia (Parkinson disease, lacunar state, or focal ischemic necrosis). Patients suffering from other types of dementia (Parkinson/dementia complex, multi-infarct dementia, normal pressure hydrocephalus) showed less expression of hsp 27 in reactive astrocytes than AD, but more than controls. These results indicate that increased expression of hsp 27, especially in astrocytes showing klazmatodendrosis, is associated with AD pathology.

Expression of alpha B-crystallin in Alzheimer's disease.

alpha B-crystallin is a member of the small heat-shock protein family. Under pathological conditions, the expression of alpha B-crystallin increases in proliferating astrocytes, which suggests that this protein, in addition to glial fibrillary acidic protein (GFAP), can be a marker for gliosis in neurodegenerative diseases. Immunoblotting and immunohistochemical methods were used for the detection of alpha B-crystallin in the brains of Alzheimer's disease (AD) patients and nondemented controls. An increase in alpha B-crystallin expression was found in the brains of AD patients. Immunoreaction was present in reactive astrocytes, microglia, and oligodendrocytes, indicating that all types of glia respond to the stress associated with AD pathology. Colocalization of GFAP and alpha B-crystallin was found in fibrous astrocytes. However, the intensity and range of alpha B-crystallin expression appeared to be limited as compared with the large increase in the number of GFAP-positive astrocytes. This indicates that expression of alpha B-crystallin is not a marker for gliosis in AD. Immunoreactivity to alpha B-crystallin in both astrocytes and microglia was found mainly restricted to areas with senile plaques and neurofibrillary tangles, suggesting the association of alpha B-crystallin with amyloid deposition in AD.

The olfactory bulb in Alzheimer disease: a morphologic study of neuron loss, tangles, and senile plaques in relation to olfaction.

Complete pairs of olfactory bulbs of six Alzheimer disease (AD) patients and of six age- and sex-matched controls were morphologically investigated using a random systematic sampling procedure. The total number of cells and the number of mitral cells were the same for controls and patients, but the volume of the bulb and the number of neurons in the anterior olfactory nucleus (AON) were decreased in AD patients. The loss of AON neurons was limited to the younger AD patients and was very severe (75%). Neurofibrillary tangles (NFT) and senile plaques (SP) were found in controls, but they were more frequent in AD, especially in the younger cases. A new finding was the occurrence of very large numbers of so-called diffuse or "very primitive plaques" with the methenamine-silver stain (MS-SP). NFT and SP were limited to the AON but MS-SP also occurred in other parts of the bulb. The data are discussed in relation to olfaction, and it was concluded that odor identification is processed in central rather than in peripheral olfactory structures.

Increased expression of heat-shock protein 27 kDa in Alzheimer disease: a preliminary study.

Stress-response (heat shock) proteins (hsps) are induced in living cells under pathological conditions, including diseases of the central nervous system. Increased synthesis of hsps is suggested to play a role in preventing neuronal injury in Alzheimer disease (AD). Using a highly specific antibody we have studied the expression of heat shock protein 27 kDa (hsp 27), in the brains of AD and non-demented, age-matched control patients. Immunoblotting and immunohistochemical methods were used. We report here that in the human brain in the normal condition the expression of hsp 27 is low and limited to the vessels, subpial astrocytes and single astrocytes of the white matter. There is a significant increase in the expression of hsp 27 in the cortex of AD. In AD, the immunoreaction is mainly localized in proliferating astrocytes establishing a pattern of astrocytic gliosis. These findings are the first to show the presence of hsp 27 in human cerebral tissue in normal conditions and its induction in AD.

Congenital myotonic dystrophy; a report on thirteen cases and a review of the literature.

The congenital variant of myotonic dystrophy (CMD) is a severe disease with a high mortality. CMD is only seen in the offspring of mothers who themselves have myotonic dystrophy (MD). We present 13 patients with clinical symptoms of CMD and neuropathological findings of five of them. The most characteristic symptoms during pregnancy are reduced fetal movements and polyhydramnios. In the neonatal period generalized hypotonia, facial weakness, hyporeflexia, feeding and respiratory difficulties are present. Most of the children have a characteristic tented upper lip. The symptoms greatly diminish after a few weeks. All the children who survive the neonatal period are psychomotor retarded. On pathological examination no specific features were found in muscle tissue or in the brain. The pathogenesis and the cause of the maternal inheritance of CMD is not clear. A review of the literature is provided.

Erythrocyte band 3-like protein immunoreactivity in the human brain cortex.

The immunoreactivity of erythrocyte band 3 (B3-IR)-related protein was estimated on cortex biopsies from the brains of 33 patients varying in age from 14-week-old fetus until 67 years of life. B3-IR was not a feature of embryonic brains. A positive reaction was restricted to neurons. It appeared at early postnatal life, increased sharply until 9 years, and than stayed approximately stable between 17 and 67 years of age. The results indicate that there is a positive relation between the amount of neuronal band 3-like protein and the stage of human brain development.

Proteins immunologically related to erythrocyte anion transporter band 3 are altered in brain areas affected by Alzheimer's disease.

Proteins immunologically related to the human erythrocyte anion transporter band 3 are present in neurons of the human neocortex and hippocampus. Immunocytochemical studies show increased band 3 immunoreactivity in neurons in the brains of patients with Alzheimer's disease. Immunoblot studies show the presence of band 3-like molecules in brain membrane fractions, and suggest changes in expression and/or processing of band 3-like molecules in Alzheimer's disease-affected regions. We postulate that alterations in membrane-bound, band 3-like molecules may reflect termination of neuronal lifespan in Alzheimer's disease.

Congenital muscular dystrophy. A study on the variability of morphological changes and dystrophin distribution in muscle biopsies.

Histomorphological and histochemical variability was studied in muscle specimens from 30 patients with congenital muscular dystrophy (CMD). We found involvement of the central nervous system in 8 patients (Fukuyama CMD, F-CMD), involvement of the brain and the eyes in 5 patients (muscle, eye and brain disease, MEB-D) and hypodense white matter on the CT scans of 2 patients with (sub)normal intelligence (occidental-type cerebromuscular dystrophy, O-CMD). No morphological hallmarks were found to differentiate these subgroups. Only fat cell infiltration was found to be increased with increasing age in 'pure' CMD (pure-CMD). The morphological data did not appear to be correlated with the clinical severity or type of dystrophy (pure-CMD, F-CMD, MEB-D and O-CMD). Immunohistochemistry with dystrophin, vimentin and desmin antibodies in 14 patients (6 pure-CMD, 5 F-CMD, 2 MEB-D and 1 O-CMD) showed a normal expression pattern.

Striatonigral degeneration with neurofibrillary tangles.

An autopsy was performed on a 48-year-old woman with clinical features of parkinsonism-plus syndrome with dominating akinesia. Neuropathological examination revealed striato-nigral degeneration (SND) and neurofibrillary tangles (NFT) characterizing progressive supranuclear palsy. Such an unusual combination of pathological findings may constitute a distinct clinico-pathological entity, with akinesia as the main clinical symptom, and with a pathological substrate of SND and NFT. We suggest that such cases may establish a separate variant within multisystem atrophies syndromes.