Antibodies raised against different portions of A4 protein identify a subset of plaques in Down's syndrome

Analysis of beta-amyloid (Abeta) deposition in the temporal lobe in Alzheimer's disease using Fourier (spectral) analysis

AIM

To determine the spatial pattern of beta-amyloid (Abeta) deposition throughout the temporal lobe in Alzheimer's disease (AD).

METHODS

Sections of the complete temporal lobe from six cases of sporadic AD were immunolabelled with antibody against Abeta. Fourier (spectral) analysis was used to identify sinusoidal patterns in the fluctuation of Abeta deposition in a direction parallel to the pia mater or alveus.

RESULTS

Significant sinusoidal fluctuations in density were evident in 81/99 (82%) analyses. In 64% of analyses, two frequency components were present with density peaks of Abeta deposits repeating every 500-1000 microm and at distances greater than 1000 microm. In 25% of analyses, three or more frequency components were present. The estimated period or wavelength (number of sample units to complete one full cycle) of the first and second frequency components did not vary significantly between gyri of the temporal lobe, but there was evidence that the fluctuations of the classic deposits had longer periods than the diffuse and primitive deposits.

CONCLUSIONS

(i) Abeta deposits exhibit complex sinusoidal fluctuations in density in the temporal lobe in AD; (ii) fluctuations in Abeta deposition may reflect the formation of Abeta deposits in relation to the modular and vascular structure of the cortex; and (iii) Fourier analysis may be a useful statistical method for studying the patterns of Abeta deposition both in AD and in transgenic models of disease.

The spatial patterns of prion protein deposits in Creutzfeldt-Jakob disease: comparison with beta-amyloid deposits in Alzheimer's disease

Similar pathological processes may be involved in the deposition of extracellular proteins in the brains of patients with Creutzfeldt-Jakob disease (CJD) and Alzheimer's disease (AD). Hence, this study compared the spatial patterns of prion protein (PrP) deposits in the cerebral cortex and hippocampus in cases of sporadic CJD with those of beta-amyloid (Abeta) deposits in sporadic AD. PrP and Abeta deposits were aggregated into clusters and, in 90% of brain areas in CJD and 57% in AD, the clusters were regularly distributed parallel to the tissue boundary. In a significant proportion of cortical analyses, the mean diameter of the clusters of PrP and Abeta deposits were similar to those of the cells of origin of the cortico-cortical pathways. Abeta deposits in AD were distributed more frequently in larger-sized clusters than PrP deposits in CJD. In addition, in the hippocampus and dentate gyrus, clustering of Abeta deposits was observed in AD but PrP deposits were rare in these regions in CJD. The size, location and distribution of the extracellular protein deposits within the cortex of both disorders was consistent with the degeneration of the cortico-cortical pathways. Furthermore, spread of the pathology along these pathways may be a pathogenic feature common to CJD and AD.

Beta-amyloid deposition in the temporal lobe of patients with dementia with Lewy bodies: comparison with non-demented cases and Alzheimer's disease

beta-Amyloid (Abeta) deposition in regions of the temporal lobe in patients with dementia with Lewy bodies (DLB) was compared with elderly, non-demented (ND) cases and with Alzheimer's disease (AD). The distribution, density and clustering patterns of diffuse, primitive and classic Abeta deposits were similar in 'pure' DLB and ND cases. The distribution of Abeta deposits and the densities of the diffuse and primitive deposits were similar in 'mixed' DLB/AD cases compared with AD. However, the density of the classic deposits was significantly lower in DLB/AD compared with AD. In addition, the primitive Abeta deposits occurred more often in small, regularly spaced clusters in the tissue and less often in a single large cluster in DLB/AD compared with 'pure' AD. These results suggest that pure DLB and AD are distinct disorders which can coexist in some patients. However, the Abeta pathology of DLB/AD cases is not identical to that observed in patients with AD alone.

beta-Amyloid (A beta) deposition in the medial temporal lobe of patients with dementia with Lewy bodies

The distribution and density of diffuse, primitive and classic beta-amyloid (A beta) deposits in the medial temporal lobe (MTL) was studied in cases of dementia with Lewy bodies (DLB) with and without associated Alzheimer's disease (AD) and 15 cases of sporadic AD. In the 'pure' DLB cases, virtually no A beta deposits were observed in the CA regions of the hippocampus or dentate gyrus whereas deposits were distributed throughout the MTL in DLB/AD and AD cases. Densities of diffuse and primitive A beta deposits were similar in AD and DLB/AD cases but density was significantly reduced in the 'pure' DLB cases. The density of the classic deposits was significantly reduced in DLB cases with or without associated AD compared with AD cases. These results suggest that A beta deposition in the MTL in 'pure' DLB cases is similar to that of elderly non-demented patients while, with the exception of the classic deposits, A beta deposition in DLB/AD cases is similar to that in cases of AD alone.

Correlations between the morphology of diffuse and primitive beta-amyloid (A beta) deposits and the frequency of associated cells in Down's syndrome

Correlations between the morphology of beta-amyloid (A beta) deposits and the frequency with which they are associated with neurons and glial cells were studied in Down's syndrome. The diameter of diffuse deposits was positively correlated with the frequency of large (> 25 microns) neuronal cell bodies in the isocortex and with glial cells in the hippocampus. Diameters of primitive deposits were positively correlated with glial cells in the hippocampus and with glial cells and neurons in the isocortex. Staining intensity was positively correlated with glial cells especially in the hippocampus. The data suggest that: (i) diffuse deposits develop from neurons and primitive deposits from glia; (ii) the size of A beta deposits depends on the numbers of neurons and glia; (iii) glial cells are also involved in the conversion of A beta to amyloid; and (iv) the increased density of primitive deposits in the hippocampus is determined by the high density of glial cells.

Relationships between beta-amyloid (A beta) deposits and blood vessels in patients with sporadic and familial Alzheimer's disease

The density of diffuse, primitive and classic beta-amyloid (A beta) deposits was studied in relation to the incidence of blood vessels in the superior frontal gyrus of nine cases of sporadic Alzheimer's disease (SAD), two cases of familial Alzheimer's disease (FAD) with amyloid precursor protein (APP) mutations (APP717, Val --> Ile), and eight cases of FAD not linked to chromosomes 21, 14 or 1. Stepwise multiple regression was used to determine for each patient whether variations in the density of A beta deposits along the cortex were significantly correlated with the incidence of blood vessels. In the majority of FAD and SAD cases, the density of the diffuse and primitive type A beta deposits was not related to blood vessels. However, the incidence of the larger diameter (> 10 microns) blood vessels was positively correlated with the density of the classic A beta deposits in eight (89%) SAD and two (20%) FAD cases. The data suggest that the densities of vessels and deposits were not significantly correlated between cases but only within cases, suggesting a strictly local effect. In addition, the spatial association between classic A beta deposits and blood vessels may be more apparent in SAD compared with FAD cases.

Is the clustering of beta-amyloid (A beta) deposits in the frontal cortex of Alzheimer patients determined by blood vessels?

The clustering pattern of diffuse, primitive and classic beta-amyloid (A beta) deposits was studied in the upper laminae of the frontal cortex of 9 patients with sporadic Alzheimer's disease (AD). A beta stained tissue was counterstained with collagen type IV antiserum to determine whether the clusters of A beta deposits were related to blood vessels. In all patients, A beta deposits and blood vessels were clustered, with in many patients, a regular periodicity of clusters along the cortex parallel to the pia. The classic A beta deposit clusters coincided with those of the larger blood vessels in all patients and with clusters of smaller blood vessels in 4 patients. Diffuse deposit clusters were related to blood vessels in 3 patients. Primitive deposit clusters were either unrelated to or negatively correlated with the blood vessels in six patients. Hence, A beta deposit subtypes differ in their relationship to blood vessels. The data suggest a direct and specific role for the larger blood vessels in the formation of amyloid cores in AD.

What determines the size frequency distribution of beta-amyloid (A beta) deposits in Alzheimer's disease patients?

The factors determining the size of individual beta-amyloid (A beta) deposits and their size frequency distribution in tissue from Alzheimer's disease (AD) patients have not been established. In 23/25 cortical tissues from 10 AD patients, the frequency of A beta deposits declined exponentially with increasing size. In a random sample of 400 A beta deposits, 88% were closely associated with one or more neuronal cell bodies. The frequency distribution of A beta deposits which were associated with 0,1,2,...,n neuronal cell bodies deviated significantly from a Poisson distribution, suggesting a degree of clustering of the neuronal cell bodies. In addition, the frequency of A beta deposits declined exponentially as the number of associated neuronal cell bodies increased. A beta deposit area was positively correlated with the frequency of associated neuronal cell bodies, the degree of correlation being greater for pyramidal cells than smaller neurons. These data suggested: (1) the number of closely adjacent neuronal cell bodies which simultaneously secrete A beta was an important factor determining the size of an A beta deposit and (2) the exponential decline in larger A beta deposits reflects the low probability that larger numbers of adjacent neurons will secrete A beta simultaneously to form a deposit.

The spatial patterns of beta/A4 deposit subtypes in Down's syndrome

The spatial patterns of diffuse, primitive and classic beta/A4 deposits were studied in coronal sections of the hippocampus and adjacent gyri in 11 cases of Down's syndrome (DS) varying in age from 38 to 67 years. The objectives of the study were first, to compare the spatial patterns of beta/A4 deposits revealed in DS with those reported in cases of Alzheimer's disease (AD) and second, to study how the spatial patterns of beta/A4 deposits may develop in the tissue. The spatial patterns revealed in DS exhibited a number of similarities with those reported in AD: (1) the range and frequency of the different types of spatial pattern revealed were similar, (2) beta/A4 deposits occurred in clusters and in many cortical tissues, the clusters were distributed in a regular pattern parallel to the pia, (3) the clusters of diffuse and primitive beta/A4 deposits occurred in an alternating pattern along the cortex, and (4) the clusters of classic beta/A4 deposits were not correlated with the clusters of the diffuse and primitive deposits. Primitive deposits may develop from the diffuse deposits in regions of the cortex where extracellular paired helical filaments were formed. However, clusters of the classic beta/A4 deposits, which are formed in older cases, appear to develop independently of the diffuse and primitive deposits.

beta-Amyloid (A beta) deposition in elderly non-demented patients and patients with Alzheimer's disease

beta-amyloid (A beta) deposition in the medial temporal lobe (MTL) was studied in elderly non-demented (ND) cases and in patients with Alzheimer's disease (AD). In AD, A beta deposits were present throughout the MTL although density was less in the hippocampus than the adjacent cortical regions. In the ND cases, no A beta deposits were recorded in 6 cases and in the remaining 8 cases, A beta deposits were confined to the cortical regions adjacent to the hippocampus. The mean density of A beta deposits in the cortical regions examined was greater in AD than in the ND cases but there was a significant overlap between the two groups. The ratio of mature to diffuse A beta deposits was greater in the ND than the AD cases. In both patient groups, A beta deposits formed clusters in the cortex and many tissues exhibited a regular distribution of clusters along the cortex parallel to the pia. The mean dimension of the A beta clusters was greater in AD than in the ND cases. Hence, few aspects of A beta deposition appeared to consistently separate AD from ND cases. However, the spread of A beta pathology between modular units of the cortex and into regions of the hippocampus could be factors in the development of AD.

Differences in beta-amyloid (beta/A4) deposition in human patients with Down's syndrome and sporadic Alzheimer's disease

The density of diffuse, primitive, classic and compact beta-amyloid (beta/A4) deposits was estimated in the hippocampus and adjacent gyri in human patients with Down's syndrome (DS) and sporadic Alzheimer's disease (AD). The objective of the study was to determine whether there were differences in beta/A4 deposition in DS and sporadic AD and whether these differences could be attributed to overexpression of the amyloid precursor gene (APP) in DS. Total beta/A4 deposit density was greater in DS than AD in all brain regions studied but the DS/AD density ratios varied between brain regions. In the majority of brain regions, the ratio of primitive to diffuse beta/A4 deposits was greater in DS but the ratio of classic to diffuse deposits was greater in AD. The data were consistent with the hypothesis that overexpression of the APP gene in DS may lead to increased beta/A4 deposition. However, local brain factors also appear to be important in beta/A4 deposition in DS. Overexpression of the APP gene may also be responsible for increased production of paired helical filaments (PHF) and result in enhanced formation of primitive beta/A4 deposits in DS. In addition, increased formation of classic deposits in AD suggests that factors necessary for the production of a compact amyloid core are enhanced in AD compared with DS.

Analysis of staining methods for different cortical plaques in Alzheimer's disease

This study evaluated current methods for demonstrating and categorizing cortical plaques, with the aim of establishing objective methodology for future diagnostic evaluation. Analysis of four methods of tissue processing revealed that the highest numbers of plaques were identified in formalin-fixed, paraffin-embedded tissue regardless of the stain used. Analysis of three silver stains and four immunohistochemical dilutions of an antibody to beta A4 protein revealed that the recent silver method published by Garvey et al. [(1990) J Histotechnol 14: 39-42] was equivalent to beta A4 immunohistochemistry in demonstrating the highest number of plaques. Plaque differentiation was easier and more reliable in silver compared to beta A4-stained sections, although the number of identifiable small compact plaques was significantly reduced in silver-stained sections. These studies show that plaque differentiation may be compromised by tissue processing and staining protocols. The establishment of superior methods may provide better diagnostic resolution for patients with Alzheimer's disease.

The spatial patterns of beta/A4 deposit subtypes in Alzheimer's disease

The spatial patterns of diffuse, primitive, classic (cored) and compact (burnt-out) subtypes of beta/A4 deposits were studied in coronal sections of the frontal lobe and hippocampus, including the adjacent gyri, in nine cases of Alzheimer's disease (AD). If the more mature deposits were derived from the diffuse deposits then there should be a close association between their spatial patterns in a brain region. In the majority of tissues examined, all deposit subtypes occurred in clusters which varied in dimension from 200 to 6400 microns. In many tissues, the clusters appeared to be regularly spaced parallel to the pia or alveus. The mean dimension of the primitive deposit clusters was greater than those of the diffuse, classic and compact types. In about 60% of cortical tissues examined, the clusters of primitive and diffuse deposits were not in phase, i.e. they alternated along the cortical strip. Clusters of classic deposits appeared to be distributed independently of the diffuse deposit clusters. Cluster size of the primitive deposits was positively correlated with the density of the primitive deposits in a tissue but no such relationship could be detected for the diffuse deposits. This study suggested that there was a complex relationship between the clusters of the different subtypes of beta/A4 deposits. If the diffuse deposits do give rise to the primitive and classic varieties then factors unrelated to the initial deposition of beta/A4 in the form of diffuse plaques were important in the formation of the mature deposits.

Beta A4 deposition in the temporal cortex of adults with Down's syndrome

The deposition of beta A4 has been quantified in the temporal cortex of 9 adults (4 male, 5 female) with Down's syndrome (DS), mean age (+/- SD) 54.7 +/- 8.8 years (range 41-67 years) at the time of death. Immunostaining with antibodies, raised to different portions of the beta A4 protein, showed a greater number of deposits than were seen with traditional silver impregnation or amyloid stains. Antibody to beta A4(1-10) identified fewer plaques than the antibody to beta A4(12-28), the mean ratio of beta A4(1-10)/beta A4(12-28) plaques being 0.30 +/- 0.10 (mean +/- SD). Morphologically, 'diffuse' and 'neuritic' deposits could be distinguished but there was no significant difference in the beta A4(1-10)/beta A4(12-28) ratio according to plaque morphology, nor did the ratio change with age. Quantitatively, the beta A4(12-28) load in the temporal cortex of DS patients was high, occupying some 14% of the field area, and it was not related to the age of the subject over the range studied. Similarly, the total beta A4(12-28) plaque count was high and not age-related. The proportion of morphological plaque types visualised by the Glees and Marsland silver impregnation and by beta A4(12-28) immunostaining were compared. In both techniques 'diffuse' plaques (D) were predominant in the younger subjects and the proportion of 'neuritic' plaques (N) increased with age. The relative proportions of cored plaques (Cp) and plaque cores (C) did not change significantly with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Hippocampal and neocortical ubiquitin-immunoreactive inclusions in amyotrophic lateral sclerosis with dementia

Amyotrophic lateral sclerosis (ALS) patients with dementia were found to have ubiquitin-immunoreactive (IR) inclusions in the dentate granule cells of the hippocampus. These inclusions were also present in some patients with minor cognitive changes but otherwise typical ALS. Ubiquitin-IR inclusions were also found in neurons of superficial layers of the frontal and temporal cortex and in the entorhinal cortex in patients with ALS and dementia. These ubiquitin-IR inclusions were non-argyrophilic, and were not labelled by antibodies which identify Alzheimer's neurofibrillary tangles and Pick bodies, nor were they typical of cortical Lewy bodies. Our findings indicate that ubiquitin-IR inclusions in small neurons of the hippocampus, entorhinal area and neocortex are a characteristic feature of degeneration of non-motor cortex in ALS, and are particularly associated with cognitive impairment and dementia of frontal lobe type.

Familial Alzheimer's disease with the amyloid precursor protein position 717 mutation and sporadic Alzheimer's disease have the same cytoskeletal pathology

The cytoskeletal pathology of a patient with familial Alzheimer's disease (AD) associated with the probably causal amyloid precursor protein (APP) codon 717 Val----Ile mutation is described. In addition to moderately extensive beta A4 protein deposition within the substance of the brain and in blood vessel walls (congophilic angiopathy), there was abundant cytoskeletal pathology in the form of neurofibrillary tangles, plaque neurites and neuropil threads. Interestingly, plentiful cortical and subcortical Lewy bodies were also seen. In order to compare the cytoskeletal pathology in this case with that seen in sporadic cases of AD we (1) studied the immunohistochemical profile of the amyloid and cytoskeletal pathology with antibodies to beta A4 protein, tau, phosphorylated neurofilament epitopes and ubiquitin and (2) performed a biochemical fractionation and Western blot analysis for the abnormally phosphorylated form of tau (A68) characteristically seen in AD. No substantial difference between the familial case and sporadic cases could be found. We conclude that it is now reasonable to hypothesise that an abnormality in APP metabolism is responsible not only for the deposition of beta A4 protein, but also for the range of cytoskeletal pathology, typical of AD.

Deposition of amyloid beta protein in non-Alzheimer dementias: evidence for a neuronal origin of parenchymal deposits of beta protein in neurodegenerative disease

In two elderly patients with frontal lobe dementia and in two others with progressive aphasia an inverse relationship between the severity of beta protein deposition and the principal pathology of these disorders was noted. Deposition of beta protein occurred only in areas of cortex where functional (viable) neurones were still present and was absent where neuronal decimation had taken place. Such findings suggest that the presence of functional neurones is necessary for beta protein deposition to occur and, therefore, that neurones may be the source of the amyloid protein that is deposited within brain parenchyma not only in these disorders but also in other conditions, particularly Alzheimer's disease.

Alzheimer's disease: the relationship between the density of senile plaques, neurofibrillary tangles and A4 protein in human patients

The numerical density of senile plaques (SP) and neurofibrillary tangles (NFT) as revealed by the Glees silver method was compared with SP and NFT revealed by the Gallyas method and with amyloid (A4) deposits in immunostained sections in 6 elderly cases of Alzheimer's disease. The density of NFT was generally greater and A4 lower in tissue from hippocampus compared with the neocortex suggesting that A4 deposition was less important than the degree of paired helical filament (PHF) related damage in the hippocampus. The density of Glees SP was positively correlated Gallyas SP weakly correlated with A4 deposit number. A stepwise multiple regression analysis which included A4 deposit and Gallyas SP density and accounted for 54% of the variation in Glees SP density. Hence, different populations of SP were revealed by the different staining methods. The results suggested that the Glees method may stain a population of SP in a region of cortex where both amyloid deposition and neurofibrillary changes have occurred.

Synaptophysin and chromogranin A immunoreactivities in senile plaques of Alzheimer's disease

Immunolabelling for synaptophysin and chromogranin A, two polypeptides associated with small clear and large dense core synaptic vesicles respectively, has been performed on tissue sections of the temporal cortex in Alzheimer's disease in combination with anti-A4 amyloid labelling. The dystrophic neurites in many senile plaques were observed to be labelled by the anti-synaptophysin or anti-chromogranin A antibodies. Some diffuse amyloid deposits, demonstrated by antibodies against synthetic amyloid A4 peptides, were associated with a punctuate increase in synaptophysin or chromogranin A immunoreactivity. The labelling of dystrophic plaque neurites may reflect the accumulation in these processes of synaptic vesicles or material derived from them. We suggest also that the punctuate increase in synaptophysin and chromogranin A immunoreactivities associated with some A4 amyloid deposits may be an early event reflecting neuronal dysfunction.