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Alzheimer disease (AD) is a progressive neurodegenerative disease causing cognitive decline in the aging population. To develop disease-modifying treatments, understanding the mechanisms behind the pathology is important, which should include observations using human brain samples. We reported previously on the association of lysosomal proteins progranulin (PGRN) and prosaposin (PSAP) with amyloid plaques in non-demented aged control and AD brains. In this study, we investigated the possible involvement of PGRN and PSAP in tangle formation using human brain tissue sections of non-demented aged control subjects and AD cases and compared with cases of frontotemporal dementia with granulin (GRN) mutations. The study revealed that decreased amounts of PGRN and PSAP proteins were detected even in immature neurofibrillary tangles, while colocalization was still evident in adjacent neurons in all cases. Results suggest that neuronal loss of PGRN preceded loss of PSAP as tangles developed and matured. The GRNmutation cases exhibited almost complete absence of PGRN in most neurons, while PSAP signal was preserved. Although based on correlative data, we suggest that reduced levels of PGRN and PSAP and their interaction in neurons might predispose to accumulation of p-Tau protein.

Snorkelling deaths in Australia, 1987-1996, are discussed based on a retrospective case extraction study. The ongoing diving fatality survey and coroners' reports showed 60 snorkeling deaths with the divers have an average age of 44.7 years. Hyperventilation to increase breath-holding time among young spearfishers was seen to be a dangerous practice. Safety measures, among them use of flippers for propulsion and using the buddy system should be encouraged and in commercial operations made mandatory. Many who drowned were inexperienced, or medically unfit and many were tourists, often along, often unable to speak English.

This study investigates salivary gland biopsies in living patients with Parkinson disease (PD).

Dementia is a frequent complication of Parkinson's disease (PD). About half of PD dementia (PDD) is hypothesized to be due to progression of the underlying Lewy body pathology into limbic regions and the cerebral cortex while the other half is thought to be due to coexistent Alzheimer's disease (AD). Clinically, however, these are indistinguishable. The spread of amyloid plaques to the striatum has been reported to be a sensitive and specific indicator of dementia due to AD. The purpose of the present study was to determine if the presence of striatal plaques might also be a useful indicator of the presence of diagnostic levels of AD pathology within PD subjects. We analyzed neuropathologically-confirmed cases of PD without dementia (PDND, N = 31), PDD without AD (PDD, N = 31) and PD with dementia meeting clinicopathological criteria for AD (PDAD, N = 40). The minimum diagnostic criterion for AD was defined as including a clinical history of dementia, moderate or frequent CERAD cortical neuritic plaque density and Braak neurofibrillary stage III-VI. Striatal amyloid plaque densities were determined using Campbell-Switzer and Thioflavine S stains. Striatal plaque densities were significantly higher in PDAD compared to PDD (p < 0.001). The presence of striatal plaques was approximately 80% sensitive and 80% specific for predicting AD. In comparison, the presence of cerebral cortex plaques alone was highly sensitive (100%) but had poor specificity (48% to 55%). The results suggest that striatal amyloid imaging may be clinically useful for making the distinction between PDD and PDAD.

Alzheimer's disease (AD) is characterized by the accumulation of extracellular insoluble amyloid, primarily derived from polymerized amyloid-β (Aβ) peptides. We characterized the chemical composition of the Aβ peptides deposited in the brain parenchyma and cerebrovascular walls of triple transgenic Tg-SwDI mice that produce a rapid and profuse Aβ accumulation. The processing of the N- and C-terminal regions of mutant AβPP differs substantially from humans because the brain parenchyma accumulates numerous, diffuse, nonfibrillar plaques, whereas the thalamic microvessels harbor overwhelming amounts of compact, fibrillar, thioflavine-S- and apolipoprotein E-positive amyloid deposits. The abundant accretion of vascular amyloid, despite low AβPPtransgene expression levels, suggests that inefficient Aβ proteolysis because of conformational changes and dimerization may be key pathogenic factors in this animal model. The disruption of amyloid plaque cores by immunotherapy is accompanied by increased perivascular deposition in both humans and transgenic mice. This analogous susceptibility and response to the disruption of amyloid deposits suggests that Tg-SwDI mice provide an excellent model in which to study the functional aftermath of immunotherapeutic interventions. These mice might also reveal new avenues to promote amyloidogenic AβPP processing and fundamental insights into the faulty degradation and clearance of Aβ in AD, pivotal issues in understanding AD pathophysiology and the assessment of new therapeutic agents.

This review focuses on the current findings regarding interaction between amyloid β peptide (Aβ) and receptor for advanced glycation endproducts (RAGE) and its roles in the pathogenesis of Alzheimer's disease (AD). As a ubiquitously expressed cell surface receptor, RAGE mediates the effects of Aβ on microglia, blood-brain barrier (BBB) and neurons through activating different signaling pathways. Data from autopsy brain tissues, in vitro cell cultures and transgenic mouse models suggest that Aβ-RAGE interaction exaggerates neuronal stress, accumulation of Aβ, impaired learning memory, and neuroinflammation. Blockade of RAGE protects against Aβ-mediated cellular perturbation. These findings may have an important therapeutic implication for neurodegenerative disorders relevant to AD.

A central feature of the inflammatory pathology in Alzheimer’s disease is activated microglia clustered around aggregated amyloid β (Aβ) peptide‐containing plaques. In vitro‐cultured microglia can be activated to an inflammatory state by aggregated Aβ with the induction of a range of different neurotoxic factors and provide a model system for studying microglia Aβ interactions. Gene expression responses of human postmortem brain‐derived microglia to aggregated Aβ were measured using whole genome microarrays to address the hypothesis that Aβ interactions with human microglia primarily induce proinflammatory genes and not activation of genes involved in Aβ phagocytosis and removal. The results demonstrated that Aβ activation of microglia induced a large alteration in gene transcription including activation of many proinflammatory cytokines and chemokines, most notably, interleukin (IL)‐1β, IL‐8, and matrix metalloproteinases (MMP), including MMP1, MMP3, MMP9, MMP10, and MMP12. All of these genes could amplify ongoing inflammation, resulting in further neuronal loss. Changes in expression of receptors associated with Aβ phagocytosis did not match the changes in proinflammatory gene expression. Time‐course gene expression profiling, along with real‐time polymerase chain reaction validation of expression changes, demonstrated an acute phase of gene induction for many proinflammatory genes but also chronic activation for many other potentially toxic products. These chronically activated genes included indoleamine 2,3‐dioxygenase and kynureninase, which are involved in formation of the neurotoxin quinolinic acid, and S100A8, a potential proinflammatory chemokine. These studies show that activation of microglia by Aβ induces multiple genes that could be involved in inflammatory responses contributing to neurodegenerative processes.

Overproduction of the peptide amyloid β (Aβ) is thought to be a critical pathogenic event in Alzheimer's disease (AD), leading to the formation of senile (amyloid) plaques, which in turn lead to neurofibrillary tangles, neuronal and synaptic loss, and dementia. Mendelian inheritance of AD, which occurs in a very small proportion of cases, is caused by mutations in the genes for β‐amyloid precursor protein (β‐APP), presenilin 1 or presenilin 2; the mutations are thought to be pathogenic because they result in increased Aβ production. The majority of AD is not inherited in a Mendelian fashion, and is therefore termed sporadic. The cause or causes of this common form of AD is unknown, although it is assumed that overproduction of Aβ is also the critical event. Recent animal experiments suggest that Aβ overproduction in aging and sporadic AD may be the result of cortical cholinergic deafferentation, which occurs as part of normal human aging. Decreasing Aβ production may therefore slow or halt the progression of AD, and cholinergic agents may be particularly suitable for this role. In vitro work has indicated that cholinergic muscarinic M1 receptor agonists may reduce the cellular production of Aβ. In vivo experiments have shown that both muscarinic agonists and acetylcholinesterase inhibitors lower central nervous system (CNS) Aβ concentrations. These results suggest that cholinergic agents may be particularly well suited to a preventative role in AD therapy by limiting the initial accumulation of Aβ. Drug Dev. Res. 56:242–247, 2002. © 2002 Wiley‐Liss, Inc.

Receptor-mediated interactions with amyloid β-peptide (Aβ) could be important in the evolution of the inflammatory processes and cellular dysfunction that are prominent in Alzheimer's disease (AD) pathology. One candidate receptor is the receptor for advanced glycation endproducts (RAGE), which can bind Aβ and transduce signals leading to cellular activation. Data are presented showing a potential mechanism for Aβ activation of microglia that could be mediated by RAGE and macrophage colony-stimulating factor (M-CSF). Using brain tissue from AD and nondemented (ND) individuals, RAGE expression was shown to be present on microglia and neurons of the hippocampus, entorhinal cortex, and superior frontal gyrus. The presence of increased numbers of RAGE-immunoreactive microglia in AD led us to further analyze RAGE-related properties of these cells cultured from AD and ND brains. Direct addition of Aβ(1–42) to the microglia increased their expression of M-CSF. This effect was significantly greater in microglia derived from AD brains compared to those from ND brains. Increased M-CSF secretion was also demonstrated using a cell culture model of plaques whereby microglia were cultured in wells containing focal deposits of immobilized Aβ(1–42). In each case, the Aβ stimulation of M-CSF secretion was significantly blocked by treatment of cultures with anti-RAGE F(ab′)2. Treatment of microglia with anti-RAGE F(ab′)2also inhibited the chemotactic response of microglia toward Aβ(1–42). Finally, incubation of microglia with M-CSF and Aβ increased expression of RAGE mRNA. These microglia also expressed M-CSF receptor mRNA. These data suggest a positive feedback loop in which Aβ–RAGE-mediated microglial activation enhances expression of M-CSF and RAGE, possibly initiating an ascending spiral of cellular activation.

We compared the expression level of C1q mRNA and the number of C1q-positive plaques in adjacent or nearby brain sections from Alzheimer disease (AD) and control cases. Small blocks of temporal cortex were fixed with 4% paraformaldehyde for 2 days at 4°C. After cryoprotection with solutions containing 10–20% glycerol and 2% dimethylsulfoxide, 40-µm sections were cut from the tissue blocks. A section from each case was stained by immunohistochemistry using a C1q antibody, while RNA was purified from adjacent or nearby sections using a combination of proteinase K pretreatment followed by extraction using Trizol reagent. The expression of C1q B chain mRNA was analyzed in these samples by the reverse-transcription polymerase chain reaction (RT-PCR). The intensities of the PCR products were measured by an image analyzer. The expression of C1q B chain mRNA was significantly more abundant in AD than in control cases (p < 0.05). Immunohistochemical analysis showed that C1q protein was localized in senile plaques in the AD brain. The number of C1q-positive plaques correlated with the expression level of C1q gene (p < 0.05). The present results suggest that C1q protein in senile plaques originates is endogenously produced in the AD brain.

Selective destruction of the cholinergic nucleus basalis magnocellularis (nbm) in the rabbit by the p75 neurotrophin receptor (NTR) immunoglobulin G (IgG) complexed to the toxin saporin leads to the deposition of amyloid-beta (A?) in and around cerebral blood vessels. In some instances, the perivascular A? resemble the diffuse deposits observed in Alzheimer's disease (AD). We propose that cortical cholinergic deprivation results, among other perturbations, in the loss of vasodilation mediated by acetylcholine. In addition to a dysfunctional cerebral blood flow, alterations in vascular chemistry affecting endothelial and smooth muscle cells may result in cerebral hypoperfusion and a breached blood-brain barrier (BBB). The selective removal of the rabbit nbm and A? accumulation may serve as an important nontransgenic, and more physiological, model for the testing of pharmacological and immunological agents designed to control the deposition and the deleterious effects of A? in AD.

INTERLEUKIN-15 (IL-15) is a novel cytokine that has recently been cloned and expressed. IL-15 interacts with components of the IL-2 receptor and exhibits T-cell stimulating activity similar to that of IL-2. In the present study, we investigated the expression of IL-15 in enriched cultures of human fetal astrocytes and microglia using reverse transcription-polymerase chain reaction (RT-PCR) and immunodetection analysis. Low levels of IL-15 were expressed by unstimulated human fetal astrocytes and microglia, and treatment of astrocytes with interleukin-1β (IL-1β), interferon-γ (IFN-γ), or tumor necrosis factor-α (TNF-α) increased the expression of IL-15 at both the mRNA and protein level. Treatment of microglia with IFN-γ and lipopolysaccharide (LPS) similarly increased IL-15 expression in microglia. These findings suggest that IL-15 produced by human fetal astrocytes and microglia may have a role in T cell-mediated immune responses in the human CNS.

The regulation of C1q expression was examined in the human monocytic cell line THP-1. Since these cells can be differentiated into cells with macrophage properties and induced to express C1q, they were used as models for mature human monocyte/macrophages and indirectly microglia. Interferon-γ (IFN-γ) and the anti-inflammatory steroid agents dexamethasone and prednisone were powerful stimulators of C1q production, alone or in combination. Interleukin-6 (IL-6) and lipopolysaccharide (LPS) also had significant stimulatory activity. Phorbol myristate acetate, a protein kinase C activator, reduced C1q expression. Four additional classes of pharmacological agents were tested for their effect on C1q secretion. Tacrine, but not indomethacin, cimetidine, or propentofylline, showed activity in inhibiting C1q secretion by IFN-γ treated THP-1-derived macrophages.

Abstract: The immunohistochemical localization of interleukin-1 receptor antagonist protein (Il-1ra) was examined in brain tissues of neurologically normal controls as well as in cases of Alzheimer’s disease (AD) and Pick’s disease. In all control cases, immunoreactivity was observed in some normal-appearing neurons in the neocortex and hippocampus. In AD, there appeared to be increased numbers of positively staining neurons, and the staining of individual neurons was somewhat more intense. Il-1ra was additionally expressed in globular deposits in senile plaques and, weakly, in some extracellular neurofibrillary tangles. In Pick’s disease, there was similar staining of normal-appearing neurons and intense staining in some degenerating neurons. Using reverse transcriptase-polymerase chain reaction techniques, the mRNA for IL-1ra was detected in cultured IMR-32 human neuroblastoma cells following differentiation with dibutyryl cAMP and bromodeoxyuridine. Taken together, these data suggest that IL-1ra is a product of normal neurons which may be upregulated in some pathological circumstances.

The expression and modulation of mRNA for glial-cell-line-derived neurotrophic factor (GDNF) in human glial cells was investigated. Astrocyte cell cultures were isolated from human fetal brains, characterized by immunocytochemistry and maintained in vitro in conditions of high purity; sister cultures were exposed to protein kinase C (PKC) inhibitors for 20 min. Total RNA was extracted from the cell pellets, reverse-transcribed into cDNA and amplified by the polymerase chain reaction (PCR) with primers specific for GDNF. A reverse-transcription/PCR procedure was also performed on mRNA extracted from human fibroblast and lymphocyte cell lines. Human astrocytes grown in the absence of neurons expressed detectable amounts of mRNA for GDNF but no amplification products were observed in fibroblasts and lymphocytes, thus confirming that GDNF production was cell-type specific. After exposure to PKC inhibitors, a dramatic down-regulation of GDNF mRNA was observed in astrocyte cell cultures. Thus, human astrocytes are constitutively capable of producing GDNF, such trophic activity is restricted to neural cells, and PKC plays key roles in signal pathways that regulate the gene activation and production of GDNF.

The expression of the purinergic receptor subtype P2X7R, a nonselective cationic channel activated by high levels of adenosine triphosphate (ATP), has been studied in adult microglia obtained from Alzheimer disease (AD) and nondemented (ND) brains, in fetal human microglia exposed to Aβ1-42 peptide and in vivo in Aβ1-42-injected rat hippocampus. Semiquantitative reverse transcriptase-polymerase chain reaction showed enhanced expression (increase of 70%) of P2X7R in AD microglia compared with ND cells (analysis of 6 AD and 8 ND cases). Immunohistochemical analysis showed prominent P2X7R expression in association with Aβ plaques and localized to HLA-DR-immunoreactive microglia. In cultured fetal human microglia, cells exposed to Aβ1-42 (5 μM for 18 hours) had significantly elevated levels of P2X7R (by 106%) compared with untreated cells. Amplitudes of Ca2+ responses in these cells, induced by the selective P2X7R agonist BzATP, were increased by 145% with Aβ1-42 pretreatment relative to control (no peptide pretreatment) and were largely blocked if the P2X7R inhibitor-oxidized ATP (oxATP) was added with peptide in pretreatment solution. In vivo, double immunostaining analysis showed considerable P2X7R colocalized with microglia after injection of Aβ1-42 (1 nmol) into rat hippocampus. The overall results suggest roles of P2X7R in mediating microglial purinergic inflammatory responses in AD brain.

Marinesco bodies are nuclear inclusions found in pigmented neurons of the substantia nigra and locus ceruleus of humans and monkeys. It has long been known that the frequency of these inclusions increases with advancing age, but no pathologic associations have ever been established. We quantified Marinesco body frequency in human autopsy subjects, classified as young normal controls, elderly controls, dementia with Lewy bodies (DLB), Alzheimer disease (AD), and Parkinson disease (PD). Elderly controls, AD cases, and DLB cases had significantly increased Marinesco body frequencies relative to young controls and DLB cases had significantly increased frequencies relative to elderly controls, while PD cases did not differ from young controls; cases with AD did not differ from elderly controls. Lewy body-containing neurons had significantly higher Marinesco body frequencies than non-Lewy body-containing neurons. Marinesco body frequency in elderly control cases correlated significantly, in inverse fashion, with striatal concentrations of the dopaminergic neuron markers dopamine transporter and tyrosine hydroxylase. These statistical associations suggest that Marinesco bodies constitute or mark a pathologic process that may be related to, or contribute to, age-related motor dysfunction and/or Lewy body disorders. Further studies are needed to ascertain the molecular basis of Marinesco body formation; preliminary studies indicate that proteasome dysfunction can lead to similar abnormalities in cultured cells.

Enriched populations of neurons and astrocytes of 93–99% purity were obtained from mixed cultures of four human fetal brains. Total cellular RNA was extracted from cell pellets and reverse transcribed into cDNA. Five µ1 of cDNA were subjected to PCR amplification using primers specific for sequences of NGF, BDNF, NT-3 and CNTF. PCR products were separated through 5% acrylamide gel and identified by DNA sequencing. Results showed that neurons expressed detectable levels of mRNA for NGF in all four cultures; BDNF and NT-3 mRNA was seen only in two cultures; CNTF mRNA was not detected in all four cultures. Astrocytes expressed mRNA for NGF, BDNF, and NT-3 but not for CNTF in all cultures examined. Astrocytic expression of mRNA for NGF, BDNF and NT-3 was found during the active cell proliferation as well as at a phase of mitotic quiescence. This study provides evidence that dissociated cell cultures of human neurons produce NGF, BDNF and NT-3 in early stages of their development and that astrocytes are constitutively committed to synthesize neurotrophic factors, NGF, BDNF and NT-3. The active synthesis of selected neurotrophic factors by neurons and astrocytes is relevant in supporting migration, survival and differentiation of developing neurons in vivo.