Neuritic Senile Plaques Research Articles

APOE , vascular pathology, and the AD brain

To use neuropathologic data to examine the association between APOE genotype and cerebrovascular lesions commonly found in Alzheimer disease (AD), as well as neuritic senile plaque (SP) and neurofibrillary tangle (NFT) burden. The sample comprised brains from 96 men and 3 women who fulfilled NIA-Reagan criteria for intermediate to high likelihood of AD. Region-specific and global measures of gross cerebrovascular disease, arteriolosclerosis, white matter lesions, microinfarcts, amyloid angiopathy, neuritic SP, and NFT burden were compared among those who had at least one APOE-epsilon4 vs those who did not. Pairwise rank-order correlations between measures were calculated. The association between APOE epsilon4 status and measures of vascular and AD pathology, adjusting for age at death, sex, brain weight, and Braak stage, were evaluated. APOE-epsilon4 was not associated with gross cerebrovascular pathology. Compared to those who were negative, brains from epsilon4 individuals had a greater degree of small vessel arteriolosclerosis (p = 0.04) and perivascular macrophage infiltration (p = 0.06), but not other markers of small vessel disease or white matter myelin loss. Microinfarcts in the deep nuclei were associated with epsilon4 (p = 0.009), whereas cortical and subcortical microinfarcts were not. There was a trend toward association between APOE genotype and amyloid angiopathy (p = 0.08), and epsilon4 was associated with neuritic SP burden, but not NFT. APOE-epsilon4 is associated with small vessel arteriolosclerosis, microinfarcts of the deep nuclei, neuritic senile plaque density, and amyloid angiopathy in patients with autopsy-proven Alzheimer disease (AD). These results suggest a role for epsilon4 in some of the microvascular changes commonly found in AD and are consistent with a potential amyloidogenic role for epsilon4.

Current Advances on Different Kinases Involved in Tau Phosphorylation, and Implications in Alzheimers Disease and Tauopathies

Hyperphosphorylation and accumulation of tau in neurons (and glial cells) is one the main pathologic hallmarks in Alzheimer's disease (AD) and other tauopathies, including Pick's disease (PiD), progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease and familial frontotemporal dementia and parkinsonism linked to chromosome 17 due to mutations in the tau gene (FTDP-17-tau). Hyperphosphorylation of tau is regulated by several kinases that phosphorylate specific sites of tau in vitro. GSK-3-immunoprecipitated sarcosyl-insoluble fractions in AD have the capacity to phosphorylate recombinant tau. In addition, GSK-3 phosphorylated at Ser9, that inactivates GSK-3, is found in the majority of neurons with neurofibrillary tangles and dystrophic neurites of senile plaques in AD, and in Pick bodies and other phospho-tau-containing neurons and glial cells in other tauopathies. Increased expression of active kinases, including stress-activated kinase, c-Jun N-terminal kinase (SAPK/JNK) and kinase p38 has been found in brain homogenates in all the tauopathies. Strong active SAPK/JNK and p38 immunoreactivity has been observed restricted to neurons and glial cells containing hyperphosphorylated tau, as well as in dystrophic neurites of senile plaques in AD. Moreover, SAPK/JNK- and p38-immunoprecipitated sub-cellular fractions enriched in abnormal hyperphosphorylated tau have the capacity to phosphorylate recombinant tau and c-Jun and ATF-2 which are specific substrates of SAPK/JNK and p38 in AD and PiD. Interestingly, increased expression of phosphorylated (active) SAPK/JNK and p38 and hyperphosphorylated tau containing neurites have been observed around betaA4 amyloid deposits in the brain of transgenic mice (Tg 2576) carrying the double APP Swedish mutation. These findings suggest that betaA4 amyloid has the capacity to trigger the activation of stress kinases which, in turn, phosphorylate tau in neurites surrounding amyloid deposits. Complementary findings have been reported from the autopsy of two AD patients who participated in an amyloid-beta immunization trial and died during the course of immunization-induced encephalitis. The neuropathological examination of the brain showed massive focal reduction of amyloid plaques but not of neurofibrillary degeneration. Activation of SAPK/JNK and p38 were reduced together with decreased tau hyperphosphorylation of aberrant neurites in association with decreased amyloid plaques in both Tg2576 mice and human brains. These findings support the amyloid cascade hypothesis of tau phosphorylation mediated by stress kinases in dystrophic neurites of senile plaques but not that of neurofibrillary tangles and neuropil threads in AD.

Neuropathologic Criteria for Diagnosing Alzheimer Disease in Persons with Pure Dementia of Alzheimer Type

Universally accepted neuropathologic criteria for differentiating Alzheimer disease (AD) from healthy brain aging do not exist. We tested the hypothesis that Bielschowsky silver stained total, cored, and neuritic senile plaques (TSPs, CSPs, and NSPs, respectively), rather than neurofibrillary tangles (NFTs), best discriminate between the 2 conditions using rigorously defined nondemented (n = 7) and AD (n = 35) subjects with no known co-morbidities. We compared lesions in 3 neocortical regions, in hippocampal CA1, and in entorhinal cortex in 19 men and 13 women between 74 and 86 years at death. The Clinical Dementia Rating (CDR) was used to assess degree of cognitive impairment within a year of demise. Neocortical TSP measures provided the highest correlation with expiration CDR: area under the curve (AUC) = 0.986 with 97.8% sensitivity at 90% specificity with an estimated cut-point of 6.0 TSP/ mm2. All SP measures yielded higher estimated AUC and sensitivity for 90% specificity compared to NFTs. Derived TSP cut-points applied to 149 persons with clinical AD regardless of their neuropathologic diagnosis yielded a sensitivity of 97% and specificity of 84% for TSPs in the 3 neocortical areas. Thus cut-points based on both diffuse and neuritic SP in neocortical regions distinguished nondemented and AD subjects with high sensitivity and specificity.

Isolated Executive Impairment and Associated Frontal Neuropathology

Cognitive impairment in the absence of dementia is common in elderly individuals and is most often studied in the context of an isolated impairment in memory. In the current study, we report the neuropsychological and neuropathological features of a nondemented elderly individual with isolated impairment on a test of executive function (i.e., Trail Making Test) and preserved memory, language, and visuospatial function. Postmortem studies indicated that cortical neurofibrillary tangles (NFT) varied considerably, and some regions contained large numbers of neuritic senile plaques. Semiquantitative immunohistochemistry showed higher NFT and amyloid-beta (Aβ) loads in the frontal cortex relative to the temporal, entorhinal, occipital, and parietal cortices. A survey of the entire cingulate gyrus showed a wide dispersion of Aβ42 with the highest concentration in the perigenual part of the anterior cingulate cortex; Aβ appeared to be linked with neuron loss and did not overlap with the heaviest neuritic degeneration. The current case may represent a nonmemory presentation of mild cognitive impairment (executive mild cognitive impairment) that is associated with frontal and anterior cingulate pathology and may be an early stage of the frontal variant of Alzheimer disease.

Selective PrP-like protein, doppel immunoreactivity in dystrophic neurites of senile plaques in Alzheimer's disease.

Doppel (Dpl) is a prion-like protein encoded by the gene PRND, which has been found downstream of the prion gene PRNP in several species. The present study examines by immunohistochemistry Dpl expression in brain samples from 10 patients with Alzheimer's disease (AD), three patients with Pick's disease, four patients with Parkinson's disease, eight patients with diffuse Lewy body disease (DLBD), six patients with sporadic Creutzfeldt-Jakob disease (CJD) methionine/methionine at the codon 129, two patients with sporadic CJD methionine/valine at the codon 129 and numerous kuru plaques in the cerebellum, one patient with fatal familial insomnia (FFI), and 10 age-matched controls. In the adult human brain, Dpl immunoreactivity was restricted to scattered granule cells of the cerebellum and scattered small granules in the cerebral cortex. Dpl immunoreactivity was seen around betaA4 amyloid deposits in neuritic plaques, but not in diffuse plaques, AD and the common form of DLBD. Neurofibrillary tangles, Pick bodies and Lewy bodies were not stained with anti-Dpl antibodies. No modifications in Dpl immunoreactivity were observed in CJD excepting those associated with accompanying senile plaques. No Dpl-positive deposits were seen in FFI. Whether Dpl in neuritic plaques may attenuate amyloid-induced oxidative stress and participate in the glial response around amyloid cores is discussed in light of the few available data on Dpl functions.

Stress kinases involved in tau phosphorylation in Alzheimer's disease, tauopathies and APP transgenic mice.

Hyperphosphorylation and accumulation of tau in neurons (and glial cells) is one of the main pathologic hallmarks in Alzheimer's disease (AD) and other tauopathies, including Pick's disease (PiD), progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease and familial frontotemporal dementia and parkinsonism linked to chromosome 17 due to mutations in the tau gene (FTDP-17-tau). Recent studies have shown increased expression of select active kinases, including stress-activated kinase, c-Jun N-terminal kinase (SAPK/JNK) and kinase p38 in brain homogenates in all the tauopathies. Strong active SAPK/JNK and p38 immunoreactivity has been observed restricted to neurons and glial cells containing hyperphosphorylated tau, as well as in dystrophic neurites of senile plaques in AD. Moreover, SAPK/JNK- and p38-immunoprecipitated sub-cellular fractions enriched in abnormal hyperphosphorylated tau have the capacity to phosphorylate recombinat tau and c-Jun and ATF-2 which are specific substrates of SAPK/JNK and p38 in AD and PiD. Interestingly, increased expression of phosphorylated SAPK/JNK and p38 in association with hyperphosphorylated tau containing neurites have been observed around betaA4 amyloid deposits in the brain of transgenic mice (Tg2576)carrying the double APP Swedish mutation. These findings suggest that betaA4 amyloid has the capacity to trigger the activation of stress kinases which, in turn, phosphorylate tau in neurites surrounding amyloid deposits. Reduction in the amyloid burden and decreased numbers of amyloid plaques but not of neurofibrillary degeneration has been observed in the brain of two AD patients who participated in an amyloid-beta immunization trial. Activation of stress kinases SAPK/JNK and p38 were reduced together with decreased tau hyperphosphorylation of aberrant neurites in association with decreased amyloid plaques. These findings support the amyloid cascade hypothesis of tau phosphorylation mediated by stress kinases in dystrophic neurites of senile plaques but not that of neurofibrillary tangles and neuropil threads in AD.

Novel Cadherin-related Membrane Proteins, Alcadeins, Enhance the X11-like Protein-mediated Stabilization of Amyloid β-Protein Precursor Metabolism

Previously we found that X11-like protein (X11L) associates with amyloid beta-protein precursor (APP). X11L stabilizes APP metabolism and suppresses the secretion of the amyloid beta-protein (Abeta) that are the pathogenic agents of Alzheimer's disease (AD). Here we found that Alcadein (Alc), a novel membrane protein family that contains cadherin motifs and originally reported as calsyntenins, also interacted with X11L. Alc was abundant in the brain and occurred in the same areas of the brain as X11L. X11L could simultaneously associate with APP and Alc, resulting in the formation of a tripartite complex in brain. The tripartite complex stabilized intracellular APP metabolism and enhanced the X11L-mediated suppression of Abeta secretion that is due to the retardation of intracellular APP maturation. X11L and Alc also formed another complex with C99, a carboxyl-terminal fragment of APP cleaved at the beta-site (CTFbeta). The formation of the Alc.X11L.C99 complex inhibited the interaction of C99 with presenilin, which strongly suppressed the gamma-cleavage of C99. In AD patient brains, Alc and APP were particularly colocalized in dystrophic neurites in senile plaques. Deficiencies in the X11L-mediated interaction between Alc and APP and/or CTFbeta enhanced the production of Abeta, which may be related to the development or progression of AD.

In vivo labeling of amyloid with BF-108

Detection of aggregated amyloid-beta (Aβ) with a non-invasive imaging modality such as positron emission tomography (PET) was suggested to be ideal for the diagnosis of Alzheimer’s disease (AD) prior to the onset of clinical symptoms. We have been searching for imaging probe candidates with a high affinity for aggregated Aβ in vitro and in vivo and high lipophilicity, a characteristic that allows for the permeation of the blood–brain barrier (BBB). As analyzed by Thioflavin T (ThT) assay and octanol/water partition coefficient test ( P C), 3-diethylamino-6-(2-fluoroethyl)ethylaminoacridine (BF-108) were found to have high affinity for Aβ aggregates in vitro and high lipophilicity. Intravenously administrated BF-108 labeled Aβ aggregates injected into the amygdala as observed under a fluorescence microscope, showing this compound’s permeability of BBB and an ability to label Aβ in vivo. BF-108 also labeled neuritic senile plaques (SPs), neurofibrillary tangles, and amyloid-laden vessels in temporal and hippocampal sections from AD patients. Following intravenous administration of BF-108 to an APP23 transgenic (TG) mouse, in vivo labeling of endogenous plaques was seen in brain sections by fluorescence microscopy. These properties suggest the potential utility of BF-108 for in vivo imaging of AD pathology.

Expression of BRI, the normal precursor of the amyloid protein of familial British dementia, in human brain.

Familial British dementia (FBD) is characterized neuropathologically by deposition of a unique amyloid-forming protein, ABri. It is a fragment of an abnormal form of a precursor protein, BRI. In FBD, BRI is elongated by 11 amino acids due to a point mutation that prevents recognition of the normal stop codon. We have investigated the expression of normal BRI in non-FBD cases. Three antibodies were raised against sequences of BRI and were used for immunoblotting and immunohistochemistry. Each of these antibodies detected a band at approximately 35 kDa by Western blotting. In postmortem human brain tissues, BRI was detected as fine granules in the neuronal cytoplasm. Pyramidal neurons in CA3 and CA4 of the hippocampus as well as Purkinje cells in the cerebellar cortex were most intensely stained for BRI. Such a distribution of neurons strongly expressing BRI parallels the reported occurrence of ABri deposits in patients with FBD. In pathological cases, BRI was detected in dystrophic neurites in senile plaques, around lesions in ischemic cases, in torpedo and glumose changes in the cerebellum, Lewy neurites, ballooned neurons, and neurons generally in hypoxic cases. These results suggest that BRI is transported in neuronal processes and is possibly involved in some role in nerve terminals. While a physiological role of BRI in brain remains to be determined, the behavior of BRI in diverse brain lesions appears to be somewhat analogous to that of amyloid precursor protein, which is the source of the beta-amyloid protein of Alzheimer's disease.

A1 Adenosine Receptors Accumulate in Neurodegenerative Structures in Alzheimer's Disease and Mediate Both Amyloid Precursor Protein Processing and Tau Phosphorylation and Translocation

Immunostaining of adenosine receptors in the hippocampus and cerebral cortex from necropsies of Alzheimer disease (AD) patients shows that there is a change in the pattern of expression and a redistribution of receptors in these brain areas when compared with samples from controls. Adenosine A1 receptor (A1R) immunoreactivity was found in degenerating neurons with neurofibrillary tangles and in dystrophic neurites of senile plaques. A high degree of colocalization for A1R and betaA4 amyloid in senile plaques and for A1R and tau in neurons with tau deposition, but without tangles, was seen. Additionally, adenosine A2A receptors, located mainly in striatal neurons in controls, appeared in glial cells in the hippocampus and cerebral cortex of patients. On comparing similar samples from controls and patients, no significant change was evident for metabotropic glutamate receptors. In the human neuroblastoma SH-SY5Y cell line, agonists for A1R led to a dose-dependent increase in the production of soluble forms of amyloid precursor protein in a process mediated by PKC. A1R agonist induced p21 Ras activation and ERK1/2 phosphorylation. Furthermore, activation of A1R led to and ERK-dependent increase of tau phosphorylation and translocation towards the cytoskeleton. These results indicate that adenosine receptors are potential targets for AD.

JKK1, an upstream activator of JNK/SAPK, is activated in Alzheimer's disease.

JNK/SAPK has been implicated in the pathogenesis of Alzheimer's disease, but the upstream cascade leading to JNK/SAPK activation has not been elucidated in the disease. In this study, we focused on one of the physiological activators of JNK/SAPK, JNK kinase 1 (JKK1). Although there was no significant difference in the level and distribution of total JKK1 between Alzheimer's disease (AD) and age-matched control cases, increased levels of activated phospho-JKK1 were specifically localized to neurofibrillary pathology including neurofibrillary tangles, senile plaque neurites, granulovaualar degenerations and neuropil threads in severe AD (Braak stage V-VI), considerably overlapping with its downstream effector, phospho-JNK/SAPK, suggesting both a functional and mechanistic link. Nuclear localization of phospho-JKK1 was also found in mild (Braak stage III-IV) but not in severe AD cases (Braak stage V-VI), suggesting a possible re-distribution correlating with the progress of the disease. By immunoblot analyses, phospho-JKK1 was significantly increased in AD over control cases. Together, these findings lend further credence to the notion that the JNK/SAPK pathway is dysregulated in AD and also indicate an active role for this pathway in disease pathogenesis.

From Lewy body disease to Alzheimer's disease: hypothesis and evidence.

The mechanisms underlying Alzheimer's disease and Lewy body disease have long been a controversial subject among neurologists and neuropathologists. Here, we hypothesize that three most common histopathological structures, Lewy body (LB), neurofibrillary tangle (NFT) and neuritic senile plaque (NP) found in neurodegenerative diseases are different stages of the same lesion. Lewy body disease (LBD) and Alzheimer's disease (AD) are based on a similar or the same pathogenic mechanism. Different clinical manifestations and pathological features found in postmortem brains between LBD and AD is due to the different intensities of initial insults, rate of the disease progression and temporal involvement of different brain regions during the AD development.

Anti-tau phospho-specific Ser262 antibody recognizes a variety of abnormal hyper-phosphorylated tau deposits in tauopathies including Pick bodies and argyrophilic grains.

The rabbit polyclonal anti-tau phospho-specific Ser262 antibody (577814 Calbiochem) recognizes disease-specific band patterns on Western blots of sarkosyl-insoluble fractions in Alzheimer's disease (AD), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), argyrophilic grain disease (AGD) and Pick's disease (PiD): four bands of 74/72, 68, 64 and 60 kDa in AD, two bands of 68 and 64 kDa in PSP, CBD and AGD, and two bands of 64 and 60 kDa in PiD. Moreover, anti-tau phospho-specific Ser262 decorates neurons with neurofibrillary tangles, neurons with pre-tangles, dystrophic neurites of senile plaques, neuropil threads, Pick bodies, argyrophilic grains, and coiled bodies. Achromatic neurons in CBD, ballooned neurons in AGD, tufted astrocytes in PSP, astrocytic plaques in CBD and tau-containing astrocytes in AGD are not immunostained with the anti-tau phospho-specific Ser262 antibody. The lack of phospho-specific Ser262 immunoreactivity in tau-containing inclusions in astrocytes suggests different kinase equipment and activation in comparing neurons and astrocytes in tauopathies. Pick bodies in PiD and grains in AGD are weakly, or not all, immunostained in tissue samples with long post-mortem delays, although Ser262 is preserved in brain homogenates corresponding to the same time points processed for Western blot. This indicates postmortem modifications of tau in Pick bodies and argyrophilic grains, but not in other tau-containing inclusions, including paired helical filaments and coiled bodies, and suggests differences in tau conformation, particularly that involving phospho-tau Ser262 among tauopathies. However, it is important to note that phosphorylation of tau at Ser262 does occur in Pick bodies and argyrophilic grains, and this may have important consequences in reducing the capacity of binding phospho-tau to microtubules in these inclusions.

Dense-Core Senile Plaques in the Flemish Variant of Alzheimer's Disease Are Vasocentric

Alzheimer's disease (AD) is characterized by deposition of beta-amyloid (Abeta) in diffuse and senile plaques, and variably in vessels. Mutations in the Abeta-encoding region of the amyloid precursor protein (APP) gene are frequently associated with very severe forms of vascular Abeta deposition, sometimes also accompanied by AD pathology. We earlier described a Flemish APP (A692G) mutation causing a form of early-onset AD with a prominent cerebral amyloid angiopathy and unusually large senile plaque cores. The pathogenic basis of Flemish AD is unknown. By image and mass spectrometric Abeta analyses, we demonstrated that in contrast to other familial AD cases with predominant brain Abeta42, Flemish AD patients predominantly deposit Abeta40. On serial histological section analysis we further showed that the neuritic senile plaques in APP692 brains were centered on vessels. Of a total of 2400 senile plaque cores studied from various brain regions from three patients, 68% enclosed a vessel, whereas the remainder were associated with vascular walls. These observations were confirmed by electron microscopy coupled with examination of serial semi-thin plastic sections, as well as three-dimensional observations by confocal microscopy. Diffuse plaques did not associate with vessels, or with neuritic or inflammatory pathology. Together with earlier in vitro data on APP692, our analyses suggest that the altered biological properties of the Flemish APP and Abeta facilitate progressive Abeta deposition in vascular walls that in addition to causing strokes, initiates formation of dense-core senile plaques in the Flemish variant of AD.

Glycogen synthase kinase-3 is associated with neuronal and glial hyperphosphorylated tau deposits in Alzheimer's disease, Pick's disease, progressive supranuclear palsy and corticobasal degeneration.

Tau phosphorylation was examined in Alzheimer's disease (AD), Pick's disease (PiD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) using phospho-specific tau antibodies recognizing the phosphorylated form of Ser202, Ser214 and Ser 396, and antibodies to non-phosphorylated glycogen synthase kinase-3alpha/beta (GSK-3alpha/beta), which regulates phosphorylation at these specific sites on tau and phosphorylated GSK-3betaSer9 (GSK-3beta-P); this antibody is directed to the inactive form of GSK-3beta. Phospho-specific tau antibodies recognized disease-specific band patterns on Western blots of sarcosyl-insoluble fractions: four bands of 73, 68, 64 and 60 kDa in AD, two bands of 68 and 64 kDa in PSP and CBD, and two bands of 64 and 60 kDa in PiD. Moreover, anti-phospho-tau Ser202, Ser214 and Ser369 decorated neurons with neurofibrillary tangles, dystrophic neurites of senile plaques, neuropil threads, Pick bodies, astrocytes and oligodendrocytes with coiled bodies. No differences in the expression of GSK-3alpha/beta were seen between neurons with and without neurofibrillary tangles. GSK-3alpha/beta was enriched in sarcosyl-insoluble fractions, suggesting association of this kinase with tau hyperphosphorylation. In addition, strong expression of the phosphorylated form of GSK-3beta was found in a subpopulation of neurons with neurofibrillary tangles, and in dystrophic neurites of senile plaques, neuropil threads, Pick bodies, tau-containing astrocytes and coiled bodies in AD, PiD, PSP and CBD. This was not due to cross-reactivity between GSK-3 and phospho-tau. Specific bands differing from those of phospho-tau were seen on Western blots of sarcosyl-insoluble fractions processed for GSK-3alpha/beta and GSK-3beta-P. Double-labeling immunohistochemistry discloses that GSK-3beta-P co-localizes with abnormal tau in about 50% of neurons with neurofibrillary tangles, and in neuronal processes, astrocytes and oligodendrocytes in various tauopathies. The present results support a pivotal role for GSK-3 in tau phosphorylation in neurons and glial cells. Moreover, the elevated number of tau-containing cells stained with anti-GSK-3beta-P antibodies suggests a partial inactivation of the kinase, or sequestration of the phosphorylated form, which may contribute to the regulation of the cascade of tau hyperphosphorylation in tauopathies, and to protect tau-containing cells from apoptosis.

Active, phosphorylation-dependent mitogen-activated protein kinase (MAPK/ERK), stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and p38 kinase expression in Parkinson's disease and Dementia with Lewy bodies.

The expression of mitogen-activated protein kinases, extracellular signal-regulated kinases (MAPK/ERK), stress-activated protein kinases, c-Jun N-terminal kinases (SAPK/JNK), and p38 kinases is examined in Parkinson disease (PD), in Dementia with Lewy bodies (DLB), covering common and pure forms, and in age-matched controls. The study is geared to gaining understanding about the involvement of these kinases in the pathogenesis of Lewy bodies (LBs) and associated tau deposits in Alzheimer changes in the common form of DLB. Active, phosphorylation dependent MAPK (MAPK-P) is found as granular cytoplasmic inclusions in a subset of cortical neurons bearing abnormal tau deposits in common forms of DLB. Phosphorylated p-38 (p-38-P) decorates neurons with neurofibrillary tangles and dystrophic neurites of senile plaques in common forms of DLB. Phosphorylated SAPK/JNK (SAPK/JNK-P) expression occurs in cortical neurons with neurofibrillary tangles in the common form of DLB. Lewy bodies (LBs) in the brain stem of PD and DLB are stained with anti-ERK-2 antibodies, but they are not recognized by MAPK-P, SAPK/JNK-P and p-38-P. Yet MAPK-P, p-38-P and SAPK/JNK-P immunoreactivity is found in cytoplasmic granules in the vicinity of LBs or in association with irregular-shaped or diffuse alpha-synuclein deposits in a small percentage of neurons, not containing phosphorylated tau, of the brain stem in PD and DLB. MAPK-P, p-38-P and SAPK-P are not expressed in cortical LBs or in cortical neurons with alpha-synuclein-only inclusions in DLB. MAPK-P, p-38-P and SAPK/JNK-P are not expressed in alpha-synuclein-positive neurites (Lewy neurites) in PD and DLB as revealed by double-labeling immunohistochemistry. These results show that MAPKs are differentially regulated in neurons with alpha-synuclein-related inclusions and in neurons with abnormal tau deposits in DLB. Moreover, different kinase expression in brain stem and cortical LBs suggest a pathogenesis of brain stem and cortical LBs in LB diseases. Finally, no relationship has been observed between MAPK-P, p-38-P and SAPK/JNK-P expression and increased nuclear DNA vulnerability, as revealed with the method of in situ end-labeling of nuclear DNA fragmentation, and active, cleaved caspase-3 expression in neurons and glial cells in the substantia nigra in PD and DLB.

Phosphorylated mitogen-activated protein kinase (MAPK/ERK-P), protein kinase of 38 kDa (p38-P), stress-activated protein kinase (SAPK/JNK-P), and calcium/calmodulin-dependent kinase II (CaM kinase II) are differentially expressed in tau deposits in neurons and glial cells in tauopathies.

Calcium/calmodulin-dependent kinase II (alpha- and beta-CaM kinase II), and phosphorylated mitogen-activated extracellular signal-regulated protein kinase (MAPK/ERK-P), phosphorylated protein kinase of 38 kDa (p38-P) and phosphorylated stress-activated protein kinase (SAPK/JNK-P) expression have been examined in Alzheimer disease (AD), Pick's disease (PiD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). The study was carried out to increase understanding of the signals that may regulate tau phosphorylation in tauopathies. MAPK/ERK-P was found in a subset of neurons and glial cells bearing abnormal tau deposition, but rarely in neurofibrillary tangles. Strong p38-P immunoreactivity was observed in about 50-70% of neurons with neurofibrillary tangles and in dystrophic neurites of senile plaques in AD. Strong p38-P immunoreactivity was seen in practically all Pick bodies in PiD, and in most neurons with neurofibrillary degeneration or with tau deposits (pre-tangle neurons) in PSP and CBD, as revealed with single and double-labeling immunohistochemistry to p38-P and tau. In addition, strong p38-P immunoreactivity was present in tau-positive astrocytes and in coiled bodies in PSP and CBD. Single and double-labeling immunohistochemistry to MAPK/ERK-P and p38-P disclosed that MAPK/ERK-P appeared at early stages of tau phosphorylation in neurons and glial cells in tauopathies, and that MAPK/ERK-P and p38-P co-localize only in a subset of neurons and glial cells with phosphorylated tau deposits. SAPK/JNK-P immunoreactivity was seen in a subset of neurons, including many neurons with neurofibrillary degeneration, and in glial cells accumulating abnormal tau, in AD, PiD, PSP and CBD. Double-labeling immunohistochemistry disclosed partial co-localization of SAPK/JNK-P and either MAPK/ERK-P or p-38-P immunoreactivity. These findings indicate that MAPK/ERK-P, SAPK/JNK-P and p-38-P are differentially expressed in association with tau deposits in tauopathies. Finally, CaM kinase II is present in neurons but not in glial cells, thus suggesting no role of CaM kinase II in tau phosphorylation of glial cells. These observations, together with previous results of in vitro studies, support the idea that several MAPK/ERK, SAPK/JNK, p38 and CaM kinase II may participate in tau phosphorylation in tauopathies. Lack of co-localization between MAPK/ERK-P, SAPK/JNK-P and p-38-P over-expression, and staining with the method of in situ end-labeling of nuclear DNA fragmentation in individual cells indicate that over-expression of these kinases is not linked with increased nuclear DNA vulnerability in AD, PiD, PSP and CBD.

Age-related changes in the localization of presenilin-1 in cynomolgus monkey brain

Age-related changes in PS-1 localization were examined in the brains of 22 cynomolgus monkeys ranging in age from embryonic day 87 to 35 years. In embryonic monkey brains, anti-PS-1 antibody N12, which recognizes the PS-1 N-terminal fragment (Ntf) and holo protein, stained immature neuronal cells. In juvenile monkeys, N12 stained large pyramidal neurons, cerebral neocortical neurons, and cerebellar Purkinje’s cells. Cytoplasmic staining of these cells was granular in appearance. In aged monkeys, N12 stained neurons in all layers of the neocortex. In contrast, regardless of the age of the animals examined, M5, an anti-PS-1 antibody that specifically recognizes only the PS-1 C-terminal fragment (Ctf), stained neurons in all layers of the neocortex and neurons in the cerebellum. M5 also stained neuropil and white matter, and in aged monkeys, M5 stained swollen neurites of mature senile plaques. Age-related changes in PS-1 expression were further examined using Western blot analysis of mitochondrial, myelin, microsomal, nuclear, synaptosomal, and cytosol fractions isolated from 10 monkey brains ranging in age from embryonic day 87 to 32 years. In all brains, Ntf and Ctf were expressed most abundantly in the microsome fraction. The amount of PS-1 in the nuclear fraction dramatically increased with age. We conclude that the transport of PS-1 diminished with age and that PS-1 fragments accumulated in endoplasmic reticulum (ER) associated with the nuclear membrane.

Fas and Fas ligand expression in Alzheimer's disease.

The Fas/Fas ligand (L) signaling system has been implicated in the control of cell death and cell survival of T and B lymphocytes and in a variety of cell types under particular pathological conditions. In the present study we examined the expression of Fas and Fas-L, by Western blotting and immunohistochemistry, in the human frontal cortex and hippocampus of individuals with advanced Alzheimer's disease (AD) and age-matched controls. Expression levels of Fas and Fas-L, as seen in Western blots, are preserved in the frontal cortex but decreased in the hippocampus in AD when compared with age-matched controls. Yet Fas and Fas-L immunoreactivity is found in remaining AD neurons in the frontal cortex and hippocampus. Moreover, Fas and Fas-L are expressed equally in tangle-bearing and non-tangle-bearing neurons, as revealed with double-labeling immunohistochemistry to Fas or Fas-L and tau or phosphorylated neurofilament epitopes. Dystrophic neurites of senile plaques are not stained with Fas and Fas-L antibodies. A moderate increase in Fas and a strong increase in Fas-L immunoreactivity occur in reactive astrocytes in AD. Yet there is no relationship between Fas or Fas-L expression and increased nuclear DNA vulnerability as revealed with double-labeling immunohistochemstry and in situ end-labeling of nuclear DNA fragmentation. Although the Fas/Fas-L system may have some effect in the control of reactive astrocytosis in AD, the present results show no evidence that Fas/Fas-L signals participate in specific processes of the disease, including neurofibrillary degeneration, dystrophic neurite formation, and cell death.

Aβ amyloidosis induces the initial stage of tau accumulation in APP Sw mice

To clarify how Aβ deposits induce secondary tauopathy, the presence of phosphorylated tau, glycogen synthase kinase 3α (GSK3α), GSK3β, cyclin-dependent kinase 5 (CDK5), mitogen-activated protein kinase (MAPK) and fyn were examined in the Tg2576 brain showing substantial brain Aβ amyloidosis and behavioral abnormalities. Phosphorylated tau at Ser199, Thr231/Ser235, Ser396 and Ser413 accumulated in the dystrophic neurites of senile plaques. The major kinase for tau phosphorylation was GSK3β. Smaller contributions of GSK3α, CDK5 and MAPK were suggested. Thus, brain Aβ amyloidosis has a potential role in the induction of tauopathy leading to the mental disturbances of Alzheimer's disease.