Alpha 1-antichymotrypsin as a possible biochemical marker for Alzheimer-type dementia

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Novel Exosome Biomarker Candidates for Alzheimer's Disease Unravelled Through Mass Spectrometry Analysis

Exosomes are small extracellular vesicles (EVs) present in human biofluids that can transport specific disease-associated molecules. Consequently blood-derived exosomes have emerged as important peripheral biomarker sources for a wide range of diseases, among them Alzheimer’s disease (AD). Although there is no effective cure for AD, an accurate diagnosis, relying on easily accessible peripheral biofluids, is still necessary to discriminate this disease from other dementias, test potential therapies and even monitor rate of disease progression. The ultimate goal is to produce a cost-effective and widely available alternative, which can also be employed as a first clinical screen. In this study, EVs with exosome-like characteristics were isolated from serum of Controls and AD cases through precipitation- and column-based methods, followed by mass spectrometry analysis. The resulting proteomes were characterized by Gene Ontology (GO) and multivariate analyses. Although GO terms were similar for exosomes’ proteomes of Controls and ADs, using both methodologies, a clear segregation of disease cases was obtained when using the precipitation-based method. Nine significantly different abundant proteins were identified between Controls and AD cases, representing putative biomarker candidate targets. Among them are AACT and C4BPα, two Aβ-binding proteins, whose exosome levels were further validated in individuals from independent cohorts using antibody-based approaches. The findings discussed represent an important contribution to the identification of novel exosomal biomarker candidates useful as potential blood-based tools for AD diagnosis.

Exosomal Aβ-Binding Proteins Identified by "In Silico" Analysis Represent Putative Blood-Derived Biomarker Candidates for Alzheimer´s Disease

The potential of exosomes as biomarker resources for diagnostics and even for therapeutics has intensified research in the field, including in the context of Alzheimer´s disease (AD). The search for disease biomarkers in peripheral biofluids is advancing mainly due to the easy access it offers. In the study presented here, emphasis was given to the bioinformatic identification of putative exosomal candidates for AD. The exosomal proteomes of cerebrospinal fluid (CSF), serum and plasma, were obtained from three databases (ExoCarta, EVpedia and Vesiclepedia), and complemented with additional exosomal proteins already associated with AD but not found in the databases. The final biofluids’ proteomes were submitted to gene ontology (GO) enrichment analysis and the exosomal Aβ-binding proteins that can constitute putative candidates were identified. Among these candidates, gelsolin, a protein known to be involved in inhibiting Abeta fibril formation, was identified, and it was tested in human samples. The levels of this Aβ-binding protein, with anti-amyloidogenic properties, were assessed in serum-derived exosomes isolated from controls and individuals with dementia, including AD cases, and revealed altered expression patterns. Identification of potential peripheral biomarker candidates for AD may be useful, not only for early disease diagnosis but also in drug trials and to monitor disease progression, allowing for a timely therapeutic intervention, which will positively impact the patient’s quality of life.

Cerebrospinal fluid from Alzheimer patients affects cell-mediated nerve growth factor production and cell survival in vitro

Alzheimer's disease (AD) is characterized by early degeneration of cholinergic neurons and decreased levels of nerve growth factor (NGF). Thus, increasing the NGF levels by for instance encapsulated cell bio-delivery (ECB) is a potential treatment strategy. The results from our previous first-in-human studies on ECB of NGF to the basal forebrain cholinergic neurons were promising, but indicated some variability of long-term viability of the encapsulated cells and associated reduced NGF-release. Here we studied the effect of amyloid beta-peptides (Aβ), interleukin 1-beta (IL-1β), and CSF from AD, Lewy body dementia (LBD) or subjective cognitive impairment (SCI) patients on the NGF overproducing cell line NGC-0295. At physiological concentrations, neither Aβ₄₀ nor Aβ₄₂ had any major impact on cell viability or NGF-production. In contrast, IL-1β dose-dependently affected NGF-production over time. Exposure of NGF-producing cells to CSF from AD patients showed significantly reduced NGF-release as compared to CSF from LBD or SCI patients. By mass spectrometry we found 3 proteins involved in inflammatory pathways to have an altered expression in AD CSF compared to LBD and SCI. Cell survival and NGF-release were not affected by Aβ. NGF-release was affected by IL-1β, suggesting that inflammation has a negative effect on ECB cells.

Proteomics Analysis of Blood Serums from Alzheimer's Disease Patients Using iTRAQ Labeling Technology

Alzheimer' disease (AD) is the most common form of dementia affecting up to 6% of the population over the age of 65. In order to discover differentially expressed proteins that might serve as potential biomarkers, the serums from AD patients and healthy controls were compared and analyzed using the proteomics approach of isobaric tagging for relative and absolute quantitation (iTRAQ). For the first time, AD biomarkers in serums are investigated in the Han Chinese population using iTRAQ labeled proteomics strategy. Twenty-two differentially expressed proteins were identified and out of which nine proteins were further validated with more sample test. Another three proteins that have been reported in the literature to be potentially associated with AD were also investigated for alteration in expression level. Functions of those proteins were mainly related to the following processes: amyloid-β (Aβ) metabolism, cholesterol transport, complement and coagulation cascades, immune response, inflammation, hemostasis, hyaluronan metabolism, and oxidative stress. These results support current views on the molecular mechanism of AD. For the first time, differential expression of zinc-alpha-2-glycoprotein (AZGP1), fibulin-1 (FBLN1), platelet basic protein (PPBP), thrombospondin-1 (THBS1), S100 calcium-binding protein A8 (S100A8), and S100 calcium-binding protein A9 (S100A9) were detected in the serums of AD patients compared with healthy controls. These proteins might play a role in AD pathophysiology and serve as potential biomarkers for AD diagnosis. Specifically, our results strengthened the crucial role of Aβ metabolism and blood coagulation in AD pathogenesis and proteins related to these two processes may be used as peripheral blood biomarkers for AD.

Circulating inflammatory biomarkers in relation to brain structural measurements in a non-demented elderly population

The aim of this investigation was to determine whether circulating inflammatory biomarkers c-reactive protein (CRP), interleukin-6 (IL6), and alpha 1-antichymotrypsin (ACT) were related to structural brain measures assessed by magnetic resonance imaging (MRI). High-resolution structural MRI was collected on 680 non-demented elderly (mean age 80.1years) participants of a community-based, multiethnic cohort. Approximately three quarters of these participants also had peripheral inflammatory biomarkers (CRP, IL6, and ACT) measured using ELISA. Structural measures including brain volumes and cortical thickness (with both global and regional measures) were derived from MRI scans, and repeated MRI measures were obtained after 4.5years. Mean fractional anisotropy was used as the indicator of white matter integrity assessed with diffusion tensor imaging. We examined the association of inflammatory biomarkers with brain volume, cortical thickness, and white matter integrity using regression models adjusted for age, gender, ethnicity, education, APOE genotype, and intracranial volume. A doubling in CRP (b=-2.48, p=0.002) was associated with a smaller total gray matter volume, equivalent to approximately 1.5years of aging. A doubling in IL6 was associated with smaller total brain volume (b=-14.96, p<0.0001), equivalent to approximately 9years of aging. Higher IL6 was also associated with smaller gray matter (b=-6.52, p=0.002) and white matter volumes (b=-7.47, p=0.004). The volumes of most cortical regions including frontal, occipital, parietal, temporal, as well as subcortical regions including pallidum and thalamus were associated with IL6. In a model additionally adjusted for depression, vascular factors, BMI, and smoking status, the association between IL6 and brain volumes remained, and a doubling in ACT was marginally associated with 0.054 (p=0.001) millimeter thinner mean cortical thickness, equivalent to that of approximately 2.7years of aging. None of the biomarkers was associated with mean fractional anisotropy or longitudinal change of brain volumes and thickness. Among older adults, increased circulating inflammatory biomarkers were associated with smaller brain volume and cortical thickness but not the white matter tract integrity. Our preliminary findings suggest that peripheral inflammatory processes may be involved in the brain atrophy in the elderly.

Increased plasma TACE activity in subjects with mild cognitive impairment and patients with Alzheimer's disease

Evidence suggests that the tumor necrosis factor receptor (TNFR)-signaling pathway contributes to the pathogenesis of Alzheimer's disease (AD). TNF-α converting enzyme (TACE/ADAM-17) can cleave both pro-TNF-α and TNF receptors. Recently, we have shown that TACE activity in the cerebrospinal fluid (CSF) of subjects with mild cognitive impairment (MCI) and AD patients is significantly higher than that of cognitively healthy controls (HC). To date, it is not clear whether TACE activity could be detected in the human plasma and whether TACE activity in MCI and AD patients is different from that in HC. We analyzed TACE expression and activity in a large clinical sample of 64 patients with AD, 88 subjects with MCI, and 50 age-matched HC recruited from two distinct academic centers. Plasma TACE protein levels did not differ significantly in the three study groups (AD, MCI, and HC). However, plasma TACE activity in subjects with MCI and AD patients was significantly higher than that in HC. Moreover, in MCI and AD groups, we found a significant correlation between plasma TACE activity and CSF t-tau and Aβ42 levels and CSF Aβ42/tau ratios. In AD patients, the levels of plasma TACE activity correlated significantly and negatively with cognition. These findings further support the role of the TNF-α receptor complex in AD-related neuroinflammation and propose TACE plasma activity as a promising hypothesis-driven biomarker candidate for detection, diagnosis, and prognosis of prodromal and clinical AD.

Alzheimer's disease biomarker discovery using SOMAscan multiplexed protein technology

Blood proteins and their complexes have become the focus of a great deal of interest in the context of their potential as biomarkers of Alzheimer's disease (AD). We used a SOMAscan assay for quantifying 1001 proteins in blood samples from 331 AD, 211 controls, and 149 mild cognitive impaired (MCI) subjects. The strongest associations of protein levels with AD outcomes were prostate-specific antigen complexed to α1-antichymotrypsin (AD diagnosis), pancreatic prohormone (AD diagnosis, left entorhinal cortex atrophy, and left hippocampus atrophy), clusterin (rate of cognitive decline), and fetuin B (left entorhinal atrophy). Multivariate analysis found that a subset of 13 proteins predicted AD with an accuracy of area under the curve of 0.70. Our replication of previous findings provides further evidence that levels of these proteins in plasma are truly associated with AD. The newly identified proteins could be potential biomarkers and are worthy of further investigation.

Gene expression profiling of brains from bovine spongiform encephalopathy (BSE)-infected cynomolgus macaques

BACKGROUND

Prion diseases are fatal neurodegenerative disorders whose pathogenesis mechanisms are not fully understood. In this context, the analysis of gene expression alterations occurring in prion-infected animals represents a powerful tool that may contribute to unravel the molecular basis of prion diseases and therefore discover novel potential targets for diagnosis and therapeutics. Here we present the first large-scale transcriptional profiling of brains from BSE-infected cynomolgus macaques, which are an excellent model for human prion disorders.

RESULTS

The study was conducted using the GeneChip® Rhesus Macaque Genome Array and revealed 300 transcripts with expression changes greater than twofold. Among these, the bioinformatics analysis identified 86 genes with known functions, most of which are involved in cellular development, cell death and survival, lipid homeostasis, and acute phase response signaling. RT-qPCR was performed on selected gene transcripts in order to validate the differential expression in infected animals versus controls. The results obtained with the microarray technology were confirmed and a gene signature was identified. In brief, HBB and HBA2 were down-regulated in infected macaques, whereas TTR, APOC1 and SERPINA3 were up-regulated.

CONCLUSIONS

Some genes involved in oxygen or lipid transport and in innate immunity were found to be dysregulated in prion infected macaques. These genes are known to be involved in other neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Our results may facilitate the identification of potential disease biomarkers for many neurodegenerative diseases.

Assessing candidate serum biomarkers for Alzheimer's disease: a longitudinal study

Because of the growing impact of late onset cognitive loss, considerable effort has been directed toward the development of improved diagnostic techniques for Alzheimer's disease (AD) that may pave the way for earlier (and more effective) therapeutic efforts. Serum-based biomarkers are the least expensive and invasive modality for screening and routine monitoring. We systematically reviewed the literature to assemble a list of serum biomarkers relevant to AD. In parallel, we conducted a proteomic LC-MS/MS analysis of serum collected from neurologically normal subjects and subjects with mild cognitive impairment (MCI) and early AD (n = 6 in all). Complement C3 and alpha-2-macroglobulin were identified from both the literature review and our proteomic screen for further validation. For these two candidates, ELISA was performed on serum collected from a small independent cohort of subjects for longitudinal analysis. Serum was serially collected from neurologically normal subjects (n = 5) and subjects with MCI who were subsequently followed for a period of two years (n = 5) and regrouped into stable MCI and progressive MCI or AD (n = 6). The ability of each marker to predict which subjects with MCI would progress to dementia and which would remain cognitively stable was assessed. Patients with probable cerebral amyloid angiopathy were also identified (n = 3). This preliminary analysis tested the most-promising serum protein biomarkers for AD and we concluded that none are yet ready for use in the clinical diagnosis and management of dementia. However, a more thorough assessment in longitudinal studies with higher statistical power is warranted.

Proinflammatory actions of glucocorticoids: glucocorticoids and TNFα coregulate gene expression in vitro and in vivo

Synthetic glucocorticoids are widely used for treatment of many inflammatory diseases. However, long-term glucocorticoid treatment can cause a variety of negative side effects. A genome-wide microarray analysis was performed in human lung A549 cells to identify genes regulated by both the antiinflammatory steroid dexamethasone (Dex) and the proinflammatory cytokine TNFα. Unexpectedly, we discovered that numerous genes were coregulated by treatment with both Dex and TNFα. We evaluated the mechanism of coregulation of one of these genes, serpinA3 (α-1 antichymotrypsin), a secreted, acute phase protein strongly associated with numerous inflammatory diseases. Up-regulation of serpinA3 requires the presence of both the glucocorticoid receptor and TNFα soluble receptor 1. Treatment with Dex or TNFα resulted in a 10- to 25-fold increase of serpinA3 mRNA, whereas coadministration of Dex and TNFα led to a synergistic increase in serpinA3 mRNA. The naturally occurring glucocorticoid, cortisol, also resulted in a synergistic increase in serpinA3 mRNA levels in A549 cells. Furthermore, in vivo treatment of C57BL/6 mice with Dex and TNFα resulted in coregulation of serpinA3 mRNA levels in both lung and liver tissues. Finally, chromatin immunoprecipitation analyses suggest that glucocorticoid receptor binding to the serpinA3 transcriptional start site can be enhanced by the combination of Dex plus TNFα treatment of A549 cells. These studies demonstrate that glucocorticoids and proinflammatory compounds can coregulate genes associated with human disease. This discovery may underlie the basis of some of the adverse effects associated with long-term glucocorticoid therapy.

Blood-based protein biomarkers for diagnosis and classification of neurodegenerative diseases: current progress and clinical potential

Biomarker research is a rapidly advancing field in medicine. Recent advances in genomic, genetic, epigenetic, neuroscientific, proteomic, and metabolomic knowledge and technologies have opened the way to thriving research. In the most general sense, a biomarker refers to any useful characteristic that can be measured and used as an indicator of a normal biologic process, a pathogenic process, or a pharmacologic response to a therapeutic agent. Despite the extensive resources concentrated on this area, there are very few biomarkers currently available that qualify and are satisfactorily validated for mental disorders, and there is still a major lack of biomarkers for typifying neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. This article provides an overview of this field of research and focuses on recent advances in biomarker research in Alzheimer's disease and Parkinson's disease.

Biomarkers in Alzheimer's disease drug development

Developing new therapies for Alzheimer's disease (AD) is critically important to avoid the impending public health disaster imposed by this common disorder. Means must be found to prevent, delay the onset, or slow the progression of AD. These goals will be achieved by identifying disease-modifying therapies and testing them in clinical trials. Biomarkers play an increasingly important role in AD drug development. In preclinical testing, they assist in decisions to develop an agent. Biomarkers in phase I provide insights into toxic responses and drug metabolism and in Phase II proof-of-concept trials they facilitate go/no-go decisions and dose finding. Biomarkers can play a role in identifying presymptomatic patients or specific patient subgroups. They can provide evidence of target engagement before clinical changes can be expected. Brain imaging can serve as a primary outcome in Phase II trials and as a key secondary outcome in Phase III trials. Magnetic resonance imaging is currently best positioned for use in large multicenter clinical trials. Cerebrospinal fluid (CSF) measures of amyloid beta protein (Aβ), tau protein, and hyperphosphorylated tau (p-tau) protein are sensitive and specific to the diagnosis of AD and may serve as inclusion criteria and possibly as outcomes in clinical trials targeting relevant pathways. Plasma measures of Aβ are of limited diagnostic value but may provide important information as a measure of treatment response. A wide variety of measures of detectable products of cellular processes are being developed as possible biomarkers accessible in the cerebrospinal fluid and plasma or serum. Surrogate markers that can function as outcomes in pivotal trials and reliably predict clinical outcomes are needed to facilitate primary prevention trials of asymptomatic persons where clinical measures may be of limited value. Fit-for-purpose biomarkers are increasingly available to guide AD drug development decisions.

Change in plasma Aß peptides and onset of dementia in adults with Down syndrome

OBJECTIVE

To examine changes in levels of plasma amyloid-β (Aβ) peptides, Aβ42 and Aβ40, in relation to onset of Alzheimer disease (AD) in adults with Down syndrome (DS).

METHODS

Plasma Aβ42 and Aβ40 were measured at initial examination and at follow-up in a community-based cohort of 225 adults with DS who did not have dementia at baseline and were assessed for cognitive/functional abilities and health status and followed at 14- to 20-month intervals. We used Cox proportional hazards modeling to estimate the cumulative incidence of AD by Aβ peptide change group (increasing, no change, or decreasing), adjusting for covariates.

RESULTS

Sixty-one (27.1%) of the participants developed AD. At follow-up, a decrease in Aβ42 levels, a decrease in the Aβ42/Aβ40 ratio, and an increase in Aβ40 levels were related to conversion to AD. Compared with the group with increasing levels of Aβ42, the likelihood of developing AD was 5 times higher for those whose plasma Aβ42 levels decreased over follow-up (hazard ratio [HR] = 4.9, 95% confidence interval [CI] 2.1-11.4). Decreasing Aβ42/Aβ40 was also strongly related to AD risk (HR = 4.9, 95% CI 1.8-13.2), while decreasing Aβ40 was associated with lower risk (HR = 0.4, 95% CI 0.2-0.9).

CONCLUSIONS

Among adults with DS, decreasing levels of plasma Aβ42, a decline in the Aβ42/Aβ40 ratio, or increasing levels of Aβ40 may be sensitive indicators of conversion to AD, possibly reflecting compartmentalization of Aβ peptides in the brain.

CSF Biomarkers for Alzheimer's Disease Diagnosis

Alzheimer's disease (AD) is the most common form of dementia that affects several million people worldwide. The major neuropathological hallmarks of AD are the presence of extracellular amyloid plaques that are composed of Aβ40 and Aβ42 and intracellular neurofibrillary tangles (NFT), which is composed of hyperphosphorylated protein Tau. While the amyloid plaques and NFT could define the disease progression involving neuronal loss and dysfunction, significant cognitive decline occurs before their appearance. Although significant advances in neuroimaging techniques provide the structure and physiology of brain of AD cases, the biomarker studies based on cerebrospinal fluid (CSF) and plasma represent the most direct and convenient means to study the disease progression. Biomarkers are useful in detecting the preclinical as well as symptomatic stages of AD. In this paper, we discuss the recent advancements of various biomarkers with particular emphasis on CSF biomarkers for monitoring the early development of AD before significant cognitive dysfunction.

Current treatment and recent clinical research in Alzheimer's disease

The transition from either epidemiological observation or the bench to rigorously tested clinical trials in patients with Alzheimer's disease is crucial in understanding which treatments are beneficial to patients. The amyloid hypothesis has undergone scrutiny recently, as many trials aimed at reducing amyloid and plaque have been completed or are in the testing phase. Examples include modulation of the secretases involved in beta amyloid formation, anti-aggregation agents, and immunotherapeutic trials. Other therapies targeting hyperphosphorylated tau and novel targets such as enhancement of mitochondrial function, serotonin receptors, receptor for advanced glycation end products, and nerve growth factor, as well as other strategies, are discussed. A brief review of the current Food and Drug Administration-approved treatments is included.

Biological marker candidates of Alzheimer's disease in blood, plasma, and serum

At the earliest clinical stages of Alzheimer's disease (AD), when first symptoms are mild, making a reliable and accurate diagnosis is difficult. AD related brain pathology and underlying molecular mechanisms precede symptoms. Biological markers can serve as supportive early screening and diagnostic tools as well as indicators of presymptomatic biochemical change. Moreover, biomarkers cover a variety of roles and functions such as disease prediction, indicating disease acuity and progression, and may ensure biological mapping of treatment outcome. Early screening, detection, and diagnosis of AD would permit earlier disease modifying intervention at potentially reversible stages. To date, most established biological markers from both cerebrospinal fluid neurochemistry and structural and functional neuroimaging have not reached widespread clinical application. Crucial remaining problems, such as easy acceptance and application of a test, cost-effectiveness, and noninvasiveness, need to be resolved. The development and validation of precise, reliable, and robust tests and biomarkers in blood, plasma, or serum has therefore been for a long time the ultimate focus of many research groups worldwide. Blood-based testing will most likely be the prerequisite to future sensitive screening of large populations at risk of AD and the baseline in a diagnostic flow approach to AD. The status and emerging perspectives on hypothesis and exploratory-based candidate biomarkers derived from blood, plasma, and serum are reviewed and discussed.

CSF levels of PSA and PSA-ACT complexes in Alzheimer's disease

BACKGROUND

Prostate-specific antigen (PSA) is a serine protease that in serum, is predominantly found complexed to the serine protease inhibitor alpha1-antichymotrypsin (ACT). ACT co-localizes with amyloid plaques in Alzheimer's disease (AD) brain and both PSA and ACT are detectable in cerebrospinal fluid (CSF). Therefore, we aimed to determine whether PSA is produced in the brain and whether PSA and PSA-ACT complex levels in CSF can be used as a biomarker for AD.

METHODS

Levels of ACT and PSA-ACT were determined by sandwich enzyme-linked immunosorbent assay in CSF and serum samples of AD (n = 16), frontotemporal lobe dementia (FTLD) (n = 19), mild cognitively impaired (MCI) patients (n = 19) and controls (n = 12). Total PSA was determined in a non-competitive immunoassay. Reverse transcriptase-polymerase chain reaction (RT-PCR) for PSA was performed on postmortem hippocampus and temporal cortex specimens from control and AD cases.

RESULTS

PSA is expressed in the brain, as detected by RT-PCR. PSA and PSA-ACT complexes were detectable in CSF of almost all male and only very few female subjects. The levels of PSA and PSA-ACT complexes in CSF did not differ between AD, FTLD, MCI and control groups. PSA CSF/serum quotients highly correlated with albumin CSF/serum quotients. Furthermore, the hydrodynamic radius of PSA was found to be 3 nm and the theoretical PSA quotient, derived from the Felgenhauer plot, corresponded well with the measured PSA quotient.

CONCLUSIONS

PSA is locally produced in the human brain; however, brain PSA hardly contributes to the CSF levels of PSA. PSA and PSA-ACT levels in CSF are not suitable as a biomarker for AD.

Neurochemical approaches in the laboratory diagnosis of Parkinson and Parkinson dementia syndromes: a review

The diagnosis of Parkinson disease (PD) is rendered on the basis of clinical parameters, whereby laboratory chemical tests or morphological imaging is only called upon to exclude other neurodegenerative diseases. The differentiation between PD and other diseases of the basal ganglia, especially the postsynaptic Parkinson syndromes multisystem atrophy (MSA) and progressive supranuclear palsy (PSP), is of decisive importance, on the one hand, for the response to an appropriate therapy, and on the other hand, for the respective prognosis of the disease. However, particularly at the onset of symptoms, it is difficult to precisely distinguish these diseases from each other, presenting with an akinetic-rigid syndrome. It is not yet possible to conduct a neurochemical differentiation of Parkinson syndromes. Therefore, a reliable biomarker is still to be found that might predict the development of Parkinson dementia. Since this situation is currently the subject of various different studies, the following synopsis is intended to provide a brief summary of the investigations addressing the field of the early neurochemical differential diagnosis of Parkinson syndromes and the early diagnosis of Parkinson dementia, from direct alpha-synuclein detection to proteomic approaches. In addition, an overview of the tested biomarkers will be given with regard to their possible introduction as a screening method.

Biomarkers of Alzheimer's disease

Although a battery of neuropsychological tests is often used in making a clinical diagnosis of Alzheimer's disease (AD), definitive diagnosis still relies on pathological evaluation at autopsy. The identification of AD biomarkers may allow for a less invasive and more accurate diagnosis as well as serve as a predictor of future disease progression and treatment response. Importantly, biomarkers may also allow for the identification of individuals who are already developing the underlying pathology of AD such as plaques and tangles yet who are not yet demented, i.e. "preclinical" AD. Attempts to identify biomarkers have included fluid and imaging studies, with a number of candidate markers showing significant potential. More recently, better reagent availability and novel methods of assessment have further spurred the search for biomarkers of AD. This review will discuss promising fluid and imaging markers to date.

Biomarkers for cognitive impairment and dementia in elderly people

The threat of a looming pandemic of dementia in elderly people highlights the compelling need for the development and validation of biomarkers that can be used to identify pre-clinical and prodromal stages of disease in addition to fully symptomatic dementia. Although predictive risk factors and correlative neuroimaging measures will have important roles in these efforts, this Review describes recent progress in the discovery, validation, and standardisation of molecular biomarkers--small molecules and macromolecules whose concentration in the brain or biological fluids can aid diagnosis at different stages of the more common dementing diseases and in the assessment of disease progression and response to therapeutics. An approach that efficiently combines independent information from risk-factor assessment, neuroimaging measures, and biomarkers might soon guide clinicians in the early diagnosis and management of cognitive impairment in elderly people.

Peptides and proteins in plasma and cerebrospinal fluid as biomarkers for the prediction, diagnosis, and monitoring of therapeutic efficacy of Alzheimer's disease

Alzheimer's disease (AD) affects millions of persons worldwide. Earlier detection and/or diagnosis of AD would permit earlier intervention, which conceivably could delay progression of this dementing disorder. In order to accomplish this goal, reliable and specific biomarkers are needed. Biomarkers are multidimensional and have the potential to aid in various facets of AD such as diagnostic prediction, assessment of disease stage, discrimination from normally cognitive controls as well as other forms of dementia, and therapeutic efficacy of AD drugs. To date, biomarker research has focused on plasma and cerebrospinal fluid (CSF), two bodily fluids believed to contain the richest source of biomarkers for AD. CSF is the fluid surrounding the central nervous system (CNS), and is the most indicative obtainable fluid of brain pathology. Blood plasma contains proteins that affect brain processes from the periphery, as well as proteins/peptides exported from the brain; this fluid would be ideal for biomarker discovery due to the ease and non-invasive process of sample collection. However, it seems reasonable that biomarker discovery will result in combinations of CSF, plasma, and other fluids such as urine, to serve the aforementioned purposes. This review focuses on proteins and peptides identified from CSF, plasma, and urine that may serve as biomarkers in AD.

Biological markers in Alzheimer's disease

Biomarkers are required to improve our diagnostic sensitivity and specificity and to monitor the biological activity of the Alzheimer's disease (AD) in terms of the burden of neural involvement and the tempo of disease progression. Biomarkers will initially supplement our more traditional neuropsychological and imaging markers but may eventually evolve into useful surrogate endpoints in AD research. These markers may also provide important mechanistic clues to the pharmacological action of anti-dementia compounds. At this point, the combination of elevated cerebrospinal fluid phosphorylated TAU (CSF p-TAU) proteins and low CSF ABeta(1-42) are the only biomarkers with the sensitivity and specificity to serve as useful diagnostic biomarkers capable of distinguishing AD from other dementias in the early stages. Advances in non CSF tests is urgently required. Markers assessing the progression of disease do not necessarily require the same high disease specificity as diagnostic markers, but need to be sensitive to changes in disease state. At present, candidate markers fall under four main biological rationales: (1) Specific markers of AD neuropathology; (2) Non-specific markers of neural degeneration; (3) Markers of oxidative stress; (4) Markers of neural inflammation. It is foreseeable that a panel of such markers might prove advantageous. It will be important to develop "non-invasive" markers utilizing readily obtainable tissue samples such as serum or urine to monitor disease progression (or hopefully regression). Repeated sampling would allow for comparison with traditional neuropsychological and imaging measures. The assays themselves will need to be reproducible, reliable and relatively inexpensive. Unfortunately, these biomarkers are in the formative stages of testing and results at present are inconclusive. To facilitate biomarker development in the future it would be highly advantageous to begin to collect and store biological specimens as an adjunct to current research in AD.

Blood-borne factors inhibit Alzheimer's β-amyloid fibril formation in vitro

Soluble amyloid beta-protein (Abeta) does not aggregate to beta-amyloid fibrils (fAbeta) in the brain of normal humans. We recently found that the cerebrospinal fluid (CSF) from non-Alzheimer's disease (AD) subjects inhibited the formation of fAbeta(1-40) and fAbeta(1-42) more strongly than that from AD subjects, although the CSF obtained from both groups inhibited the fAbetas formation in vitro. Here, we examined the influence of plasma obtained from AD, non-AD and healthy control (CTL) subjects on the formation of fAbeta(1-40) and fAbeta(1-42) in vitro. Although the plasma obtained from all groups inhibited the formation of fAbeta(1-40) and fAbeta(1-42), the plasma from non-AD and CTL subjects inhibited the formation of fAbetas more strongly than that from AD subjects. These results indicate that the plasma as well as CSF in AD would provide a molecular environment favorable for fAbeta formation, suggesting a decrease of specific inhibitory factors and/or increase of specific accelerating factors.

Ibuprofen suppresses interleukin-1beta induction of pro-amyloidogenic alpha1-antichymotrypsin to ameliorate beta-amyloid (Abeta) pathology in Alzheimer's models

Epidemiological and basic research suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) should protect against the most common forms of Alzheimer's disease (AD). Ibuprofen reduces amyloid (Abeta) pathology in some transgenic models, but the precise mechanisms remain unclear. Although some reports show select NSAIDs inhibit amyloid production in vitro, the possibility that in vivo suppression of amyloid pathology occurs independent of Abeta production has not been ruled out. We show that ibuprofen reduced Abeta brain levels in rats from exogenously infused Abeta in the absence of altered Abeta production. To determine whether ibuprofen inhibits pro-amyloidogenic factors, APPsw (Tg2576) mice were treated with ibuprofen for 6 months, and expression levels of the Abeta and inflammation-related molecules alpha1 antichymotrypsin (ACT), apoE, BACE1, and peroxisome proliferator-activated receptor gamma) (PPARgamma) were measured. Among these, ACT, a factor whose overexpression accelerates amyloid pathology, was reduced by ibuprofen both in vivo and in vitro. IL-1beta, which was reduced in our animals by ibuprofen, induced mouse ACT in vitro. While some NSAIDs may inhibit Abeta42 production, these observations suggest that ibuprofen reduction of Abeta pathology may not be mediated by altered Abeta42 production. We present evidence supporting the hypothesis that ibuprofen-dependent amyloid reduction is mediated by inhibition of an alternate pathway (IL-1beta and its downstream target ACT).

The potential application of cyclo-oxygenase type 2 inhibitors to Alzheimer’s disease

In recent years, dramatic progress has been made in the understanding of the neurogenetics and neurobiology of Alzheimer's disease (AD). A great deal of experimental evidence has accumulated to support the hypothesis that inflammatory mechanisms are involved in the pathophysiology of AD. In addition, epidemiological studies have revealed that anti-inflammatory medications reduce the risk of developing AD. However, long-term use of conventional anti-inflammatory drugs is associated with significant toxicity which limits their potential application to the treatment or prevention of AD. It is believed that the inhibition of cyclo-oxygenase type-1 (COX-1) causes much of this toxicity, while inhibition of COX type-2 (COX-2), which is induced by inflammatory stimuli, may confer the anti-inflammatory effect. COX-2 is also constitutively expressed in brain regions preferentially affected in Alzheimer's disease and may be directly involved in neuronal cell death. Therefore, selective COX-2 inhibitors represent a promising class of drugs for the treatment of AD.

The homozygote AA genotype of the α1-antichymotrypsin gene may confer protection against early-onset Parkinson's disease in women

There has been increasing evidence suggesting that inflammatory response maybe involved in the pathogenesis of Parkinson's disease (PD). Alpha1-antichymotrypsin gene (ACT) has been regarded as a susceptibility factor for PD in the past, but the evidence remains controversial. This case-control study was designed to investigate the association of alpha1-antichymotrypsin gene (ACT) polymorphism between 210 Taiwanese patients with clinical definite sporadic PD and 260 controls, matched by age and sex. There were no differences of allelic frequency (A and T) and genotype polymorphism (AA, AT and TT) of the ACT in PD patients from the controls. However, there were significantly fewer early-onset PD (onset age younger than 60 years) or PD women carrying the homozygote AA genotype (ACT-AA) than in controls (p=0.046 and 0.044, respectively). Further analysis revealed that the reduced risk of ACT-AA was particularly significant among PD women with the onset age younger than 60 years (OR=0.796, 95% CI=0.749-0.847, p<0.0001). This study shows that ACT-AA may confer a modest protection against developing early-onset PD in women.

Causative and susceptibility genes for Alzheimer's disease: a review

Alzheimer's disease (AD) is the most common type of dementia in the elderly population. Three genes have been identified as responsible for the rare early-onset familial form of the disease: the amyloid precursor protein (APP) gene, the presenilin 1 (PSEN1) gene and the presenilin 2 (PSEN2) gene. Mutations in these genes, however, account for less than 5% of the total number of AD cases. The remaining 95% of AD patients are mostly sporadic late-onset cases, with a complex aetiology due to interactions between environmental conditions and genetic features of the individual. In this paper, we review the most important genes supposed to be involved in the pathogenesis of AD, known as susceptibility genes, in an attempt to provide a comprehensive picture of what is known about the genetic mechanisms underlying the onset and progression of AD. Hypotheses about the role of each gene in the pathogenic pathway are discussed, taking into account the functions and molecular features, if known, of the coded protein. A major susceptibility gene, the apolipoprotein E (APOE) gene, found to be associated with sporadic late-onset AD cases and the only one, whose role in AD has been confirmed in numerous studies, will be included in a specific chapter. As the results reported by association studies are conflicting, we conclude that a better understanding of the complex aetiology that underlies AD may be achieved likely through a multidisciplinary approach that combines clinical and neurophysiological characterization of AD subtypes and in vivo functional brain imaging studies with molecular investigations of genetic components.

Plasma and cerebrospinal fluid alpha1-antichymotrypsin levels in Alzheimer's disease: correlation with cognitive impairment

alpha-1-Antichymotrypsin (ACT) is present in neuritic plaques in which it participates in the inflammatory cascade of Alzheimer's disease (AD). Reports of blood ACT levels in AD, and its usefulness as a disease biomarker, have been conflicting. In an effort to clarify this, we measured plasma ACT levels in 516 white subjects including 359 subjects with probable or possible AD, 44 subjects with other late-life dementias, and 113 nondemented people. Subjects with systemic inflammatory diseases or who were taking antiinflammatory medications were excluded. All patients underwent extensive medical and detailed neuropsychological examinations at the time their blood was drawn. We found that plasma ACT levels were elevated in AD patients compared with the control group (p = 0.01) and were associated with severity of AD dementia; there was a negative association with the Mattis Dementia Rating Scale (a global measure of cognition) and a positive association with the Clinical Dementia Rating Scale (a global functional assessment). These relationships remained significant after controlling for demographic and genetic variables. When AD subjects were stratified into subgroups by dementia severity, matched by age, education, and gender, increased serum ACT correlated with Clinical Dementia Rating Scale (p = 0.0041) or Mattis Dementia Rating Scale (p = 0.0031) scores. ACT measurements in cerebrospinal fluid from an additional 34 AD cases and 16 controls showed elevated levels (p = 0.02) in AD. There was a negative correlation (p = 0.037) between cerebrospinal fluid ACT levels and clinical severity as measured by the Mini-Mental State Examination. Our results demonstrate that peripheral ACT levels are elevated in AD, but not in dementias other than AD, and they increase with progression of AD dementia. Although not useful as a diagnostic biomarker, ACT may reflect disease severity and may be helpful as a within subject biomarker in interventions (particularly with antiinflammatory agents) directed at slowing or halting progression of disease.

Immunological mechanisms and the spectrum of psychiatric syndromes in Alzheimer's disease

Pathological, genetic and epidemiological studies support the opinion that inflammatory mechanisms are involved in the pathogenesis of Alzheimer's disease (AD). Recent pathological and neuroradiological (PET) data show that activation of microglia is an early pathogenic event that precedes the process of severe neuropil destruction in AD brains. In this paper we review the evidence that inflammatory mediators can play a pathogenic role in some behavioural disorders frequently encountered during the clinical course in AD patients. Motivational disturbances are the most striking of the depressive symptoms in AD and can be present in a preclinical stage of the disease. Experimental animal studies and clinical trials in humans have shown that cytokines can induce similar symptoms which were described as 'sickness behaviour' or 'depressive-like' state. Delirious states are frequently observed in more advanced stages of dementia. Delirium is generally considered the result of an imbalance in neurotransmitter systems with severe deficits of the cholinergic systems. Animal studies show that pro-inflammatory cytokines, such as interleukin-1, induce a reduced activity of the cholinergic system. In AD, the release of cytokines would exacerbate any already existing disturbances in the cholinergic neurotransmission. This could explain the susceptibility of demented patients to delirium provoked by a wide variety of trivial incidents that are accompanied by an acute phase response. The data reviewed in this paper suggest that it could be worthwhile employing a neuroimmunological approach to study at molecular level the pathogenesis of a broad spectrum of behavioural disturbances common in the clinical course of AD patients.

Biochemical markers related to Alzheimer's dementia in serum and cerebrospinal fluid

The diagnosis of Alzheimer's disease (AD) is currently based on clinical and neuropsychological examination. To date there is no blood test available that can discriminate dementia patients from healthy individuals. In the present paper, an overview of the current state of knowledge on biologic markers in serum (plasma) and CSF is presented. The combination of characteristic plaque markers tau and amyloid bèta may constitute a specific and sensitive CSF marker for AD. Glial fibrillary acidic protein and antibodies in CSF may be a marker for severe neurodegeneration. CSF concentrations of the oxidative stress markers 3-nitrotyrosine, 8-hydroxy-2'-deoxyguanosine and isoprostanes are increased in AD patients. Serum 24S-OH-cholesterol may be an early whereas glial fibrillary acidic protein autoantibody level may be a late marker for neurodegeneration. To date, serum alpha(1)-Antichymotripsin concentration is the most convincing marker for CNS inflammation. Increased serum homocysteine concentrations have also been consistently reported in AD. In summary, a large overlap in mean concentrations has been observed in studies comparing AD patients with healthy controls for single markers. These studies together support the theory of testing several serum markers in combination for the diagnosis of AD.

Alpha2-macroglobulin deletion polymorphism and plasma levels in late onset Alzheimer's disease

The acute-phase "panproteinase" inhibitor alpha2-macroglobulin (alpha2M), a protein involved in inflammatory reactions, has been identified in amyloid plaques in Alzheimer's disease (AD). In addition, alpha2M is involved in AD susceptibility at the genetic level, and a deletion polymorphism at the a2M gene has been found to be associated with sporadic AD. We analyzed the deletion polymorphism and alpha2M plasma levels in 93 ultraoctuagenarian patients with late-onset sporadic AD and in controls (n=157). alpha2M allele frequencies did not differ between AD patients (alpha2M*2=0.169) and controls (alpha2M*2=0.146). The mean plasma concentrations of alpha2M were similar in patients (271.8+/-79 mg/dl) and controls (269.5+/-81.2 mg/dl). No difference was found in the alpha2M mean plasma levels associated with the three alpha2M genotypes, indicating that the deletion has no effect on alpha2M protein level. However, in AD patients alpha2M mean plasma values differed significantly according to apolipoprotein E genotypes (p=0.03), with E3/E3 homozygotes showing the highest levels. Since in a previous work E3/E3 were found to be associated with the highest plasma levels of alpha1-antichymotrypsin, another acute-phase protein, the present findings seem to support the hypothesis that inflammation may be a relevant factor in AD pathogenesis peculiar to E3/E3 subjects.

The tau protein of oral epithelium increases in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is an important problem that should be solved in the 21st century. Prior to treatment, a simple and easy diagnostic method using biological markers should be available. As a method to attain this goal, we detected and determined tau protein in oral mucosal epithelium.

METHODS

Oral epithelium was exfoliated from 34 patients with AD or 29 patients with vascular dementia, and 33 young and 34 age-matched controls. Western blot was performed for determining the molecular weight of oral tau protein. The tau protein level was determined with an enzyme-linked immunosorbent assay (ELISA) kit for cerebrospinal fluid (CSF). CSF tau was also measured and compared with oral tau.

RESULTS

Western blot analysis using an anti-non-phosphorylated tau-protein antibody showed two bands, one at 65 Kd and the other at 110 Kd. The tau-protein level in oral epithelia showed a significant positive correlation with those in the CSF (p <.05). The patients with AD had significantly higher levels of tau protein than the patients with vascular dementia and the controls (p <.01). AD patients with a younger age at onset of the study showed a higher level of the tau protein than the patients with later age at onset (p <.05).

CONCLUSIONS

Like other nonneural tissues, oral epithelium contains small tau and big tau. The tau protein in oral epithelium reflects the pathological changes, as does the CSF tau. Individuals who develop AD may have had high levels of the tau protein in oral mucosal epithelium since early childhood. The tau-protein level in oral epithelia could be helpful in diagnosing AD.

Effect of cytokines, dexamethasone and the A/T-signal peptide polymorphism on the expression of alpha(1)-antichymotrypsin in astrocytes: significance for Alzheimer's disease

Proinflammatory cytokines and acute phase proteins, such as alpha(1)-antichymotrypsin, are over expressed in microglia and astrocytes in brain regions with abundant mature amyloid plaques, suggesting a glial cell-led brain acute phase response in the Alzheimer neuropathology. In this paper, we show that alpha(1)-antichymotrypsin gene expression in human astrocytes is elevated by interleukin-1 and interleukin-6, and further enhanced by glucocorticoid, while the homologous contrapsin gene in rat astrocytes is unaffected by these cytokines. These distinct gene regulation mechanisms might help to explain the differential susceptibility of humans and rodents to amyloid formation of the Alzheimer's type. In addition, we demonstrate that the alpha(1)-antichymotrypsin A-allele that encodes a different signal peptide and is a suggested risk factor for Alzheimer's disease gives rise to a reduced level of immature alpha(1)-antichymotrypsin in transfected cells. The physiological result would be an enhanced ability of the A-encoded alpha(1)-antichymotrypsin protein to become secreted and promote extracellular amyloid formation. We discuss our findings in terms of a model in which cytokine-induced alpha(1)-antichymotrypsin synthesis in astrocytes constitutes a specific inflammatory pathway that accelerates the development of Alzheimer's disease and could at least partly underlie the regional specificity and species restriction of the neuropathology.

Potential genetic markers of sporadic Alzheimer's dementia

Polymorphisms within the genes encoding apolipoprotein E (ApoE), apolipoprotein CI (ApoCI), alpha1-antichymotrypsin (ACT), the low-density lipoprotein (LDL) receptor and lipoprotein lipase were investigated in patients suffering from Alzheimer's dementia and non-demented psychiatric patients as control subjects. The ApoE allele 4, well known as a risk factor in Alzheimer's disease, and the ApoCI allele A2, which is closely linked to the ApoE allele 4, were found elevated in the index group. Concerning the polymorphism within exon 8 of the LDL receptor (alanin/threonin), there was also a predominance of the allele carrying threonin in the index group, which barely missed significance. Distribution of the polymorphisms of ACT and lipoprotein lipase were similar in both groups investigated. We conclude that, apart from the ApoE allele 4, other genetically regulated factors like ApoCI and the LDL receptor modulate the individual risk for Alzheimer's disease.

Amyloid beta protein 1-40 and 1-42 levels in matched cerebrospinal fluid and plasma from patients with Alzheimer disease

We quantitated amyloid beta proteins 1-40 (Abeta40) and 1-42 (Abeta42), and alpha1- antichymotrypsin (ACT) in matched cerebrospinal fluid (CSF) and plasma of 50 patients with probable Alzheimer disease, and analyzed the relationships with age, sex, Mini-Mental State Examination (MMSE), and apolipoprotein E phenotype. There was no relation between CSF Abeta40 and Abeta42 levels with those of plasma. CSF and plasma Abeta40 and Abeta42 levels showed no association with age, sex, and MMSE score. There was a significant correlation between CSF ACT and plasma ACT levels. The data suggest that plasma ACT crosses the blood-brain barrier. However, a lack of correlation between CSF Abeta40 and Abeta42 levels with those of plasma suggests that Abeta in CSF and plasma originates from different sources.

Plasma α1-antichymotrypsin in Alzheimer’s disease; relationships with APOE genotypes

Inflammatory processes are thought to be important contributors to the pathogenesis of Alzheimer's disease (AD). alpha1-antichymotrypsin (ACT) is a proteinase inhibitor characteristic of acute-phase inflammation and has been identified in amyloid plaques. We analyzed the plasma ACT levels in a sample of subjects with late-onset AD and correspondent controls. Plasma ACT was higher in AD patients (62.8 +/- 20.2 mg/dl) than in controls (58.8 +/- 18.1 mg/dl), but not significantly (P = 0.13). In the AD patients regression analysis showed a positive linear relationship between ACT levels and duration of the disease (P = 0.037). Increased ACT concentrations (64.6 +/- 21.2 mg/dl) were also found in patients with greater cognitive impairment (MMSE scores < 20), but since this factor depends on the duration of the disease as well, our present data seem to indicate a complex relationship involving elevated ACT levels, disease duration and cognitive impairment. Plasma ACT was found to differ significantly according to APOE genotypes (P = 0.017), the highest levels being associated to E3-E3 homozygotes (66.1 +/- 17.8 mg/dl) and the lowest to E4-E3 subjects (53.1 +/- 18.2 mg/dl). In patients not carrying APOE*4 allele the ACT levels were higher than in controls (P = 0.014), and the relationship between ACT and disease duration was stronger than that observed in the total AD sample (P = 0.003), but it was absent in those carrying APOE*4 (P = 0.67). Taken together our results seem to suggest that inflammation is a relevant factor in AD pathogenesis for subjects with E3-E3 and E3-E2 genotypes but less important for APOE*4 carrying subjects.

Central beta-amyloid peptide-induced peripheral interleukin-6 responses in mice

beta-Amyloid peptides (Abetas) share with lipopolysaccharide, a potent pro-inflammatory agent, the property of stimulating glial cells or macrophages to induce various inflammatory mediators. We recently reported that central administration of lipopolysaccharide induces peripheral interleukin-6 responses via both the central and peripheral norepinephrine system. In this study, the effect of intracerebroventricular injection of various synthetic Abetas on plasma interleukin-6 levels was examined in mice. Abeta(1-42) dose-dependently increased plasma interleukin-6 levels: 'aged' Abeta(1-42) was more effective than fresh, whereas Abeta(42-1) had no effect. 'Aged' Abeta(1-42) (205 pmol/mouse i.c.v.)-induced plasma interleukin-6 peaked at 2 h post injection, which is earlier than the peak time of the Abeta(1-42)-induced brain interleukin-6, tumor necrosis factor-alpha and interleukin-1beta levels, which was 4, 4 and 24 h, respectively. Among various peripheral organs, Abeta(1-42) (205 pmol/mouse i.c.v.) significantly increased interleukin-6 mRNA expression in lymph nodes and liver. Abeta(1-42) (205 pmol/mouse i.c.v.) significantly increased norepinephrine turnover in both hypothalamus and spleen. Either central or peripheral norepinephrine depletion effectively inhibited the Abeta(1-42)-induced peripheral interleukin-6 response. Pretreatment with prazosin (alpha(1)-adrenergic antagonist), yohimbine (alpha(2)-adrenergic antagonist), and ICI-118,551 (beta(2)-adrenergic antagonist), but not with betaxolol (beta(1)-adrenergic antagonist), inhibited Abeta(1-42)-induced plasma interleukin-6 levels. These results demonstrate that centrally administered Abeta(1-42) effectively induces the systemic interleukin-6 response which is mediated, in part, by central Abeta(1-42)-induced activation of the central and the peripheral norepinephrine systems.

Elevated plasma neopterin levels in Alzheimer disease

We assessed plasma neopterin level as a marker of inflammation in Alzheimer disease (AD). Plasma neopterin levels were higher in 51 patients with AD (9.3 +/- 5.9 ng/mL) than in 38 age-matched control subjects (6.3 +/- 2.6 ng/ml, p = 0.002). There was no correlation between neopterin levels and Mini-Mental State Examination score or duration of disease; there was a weak association between neopterin level and age (r = 0.26, p = 0.02). Although measurement of plasma neopterin levels is not useful for diagnosis, this assay may provide guidance for the development of anti-inflammatory treatment strategies for AD.

Increased frequency of the alpha-1-antichymotrypsin T allele in cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a process of unknown etiology characterized by amyloid deposition in the wall of small cerebral and meningeal blood vessels. CAA is also a feature of Alzheimer's disease (AD) and of a subgroup of elderly people. Alpha-1-Antichymotrypsin (ACT) is a serum glycoprotein frequently associated with vascular and senile plaque amyloid. The ACT gene is known to have a bi-allele polymorphism that causes a simple amino acid substitution. In an attempt to clarify the possible role of ACT polymorphism in AD and in cases of CAA, the ACT genotype was investigated in AD, CAA, and intellectually intact controls. Representative brain areas (cerebral cortex, hippocampus, putamen, white matter, and gyrus cinguli) from all cases were studied using classical histologic staining techniques (hematoxylin-eosin (HE), Mallory's thrichromic or alkaline congo red stain), and immunohistochemistry for tau and beta-amyloid proteins. There was a significantly increased T allele and TT genotype frequency in the CAA group, but not in the AD group, suggesting a role for the ACT genotype in the development of vascular lesions. The presence of the apolipoprotein E4 allele (ApoE4) did not correlate with the ACT-A allele, as previously reported, and appeared to be independent of the risk for developing AD.

Association of serum AACT levels and AACT signal polymorphism with late-onset Alzheimer's disease in Northern Ireland

alpha1-antichymotrypsin (AACT) is a serine protease inhibitor that has been associated with amyloid plaques in the brains of patients with Alzheimer's disease (AD). It has been reported that AACT serum levels are higher in AD patients than in age and sex matched controls. In addition, polymorphisms in the signal peptide and 5' of the AACT gene have been reported to increase the risk of developing AD. Serum AACT has also been suggested to be associated with cognitive decline in elderly subjects. Our objective was to investigate whether a relationship existed between serum AACT levels, AACT genotypes and risk for AD in a case control association study using 108 clinically well defined late onset AD cases and 108 age and sex matched controls from Northern Ireland. We also wished to determine whether higher serum AACT affected levels of cognition as had been previously reported. Serum AACT levels were found to be significantly raised in cases compared to controls (t=3.8, df=209, p<0.001). However, we detected no relationship between serum AACT levels and cognitive decline. We report allelic association of the AACT signal polymorphism with AD (chi(2)=3.70, df=1, p=0.04) but we failed to show any correlation between AACT serum levels and genotype.

The importance of inflammatory mechanisms for the development of Alzheimer's disease

A variety of inflammatory proteins has been identified in brains of patients with Alzheimer's disease. The current data suggest that the inflammatory processes are intimately involved in several crucial events in the pathological cascade. Immunohistochemical studies reveal that those parts of the brain wherein the amyloid-beta deposits are closely associated with a chronic inflammatory response are strongly related to the characteristic symptoms. An inflammation-based approach could also provide a valuable theoretical framework to study the influence of extracerebral factors (such as acute phase reactants) on the clinical course of Alzheimer's disease.

Recent advances in dementia research in Japan: Alzheimer-type dementia

In a previous article, recent reports by Japanese researchers on non-Alzheimer-type degenerative dementias were reviewed. In the present article, recent Japanese reports on Alzheimer-type dementia (ATD) are reviewed. Alzheimer-type dementia has received great attention and has been studied from various viewpoints in Japan as well as in Europe and the Americas. In Japan, although it was believed that vascular dementia was the most frequent dementia in the elderly, ATD has recently been shown to be the most predominant type of dementia. Such a great number of papers on ATD have been reported in Japan that mainly the clinical, neuropathological, biochemical and molecular biological research papers alone are reviewed here.

Nonsteroidal anti-inflammatory drugs and cognitive function: do they have a beneficial or deleterious effect?

Studies suggest that high dose NSAID use may be associated with a reversible impairment of cognition in the elderly. Prolonged NSAID use, on the other hand, may prevent the decline in cognition associated with aging. However, it has yet to be to be definitively determined whether this protection arises from an anti-inflammatory effect that modifies pathways involved in Alzheimer's dementia, or is mediated by a platelet effect that decreases the risk of cerebrovascular disease. Further large-scale, randomised, controlled trials using NSAIDs are needed before patients can be advised that the known risks of NSAIDs are outweighed by their potential long term benefits on cognition. While clinicians await the results of such studies, they should continue to be alert to the possibility of acute CNS adverse effects in their elderly patients who are receiving NSAIDs and to prescribe the minimum dose that is necessary to control pain and inflammation.

Inflammation and Alzheimer's disease: relationships between pathogenic mechanisms and clinical expression

During the past 15 years a variety of inflammatory proteins has been identified in the brains of patients with Alzheimer's disease (AD) postmortem. There is now considerable evidence that in AD the deposition of amyloid-beta (A beta) protein precedes a cascade of events that ultimately leads to a local "brain inflammatory response." Here we reviewed the evidence (i) that inflammatory mechanisms can be a part of the relevant etiological factors for AD in patients with head trauma, ischemia, and Down's syndrome; (ii) that in cerebral A beta disorders the clinical symptoms are determined to a great extent by the site of inflammation; and (iii) that a brain inflammatory response can explain some poorly understood characteristics of the clinical picture, among others the susceptibility of AD patients to delirium. The present data indicate that inflammatory processes in the brain contribute to the etiology, the pathogenesis, and the clinical expression of AD.

Perspectives in clinical Alzheimer's disease research and the development of antidementia drugs

Current treatment approaches in Alzheimer's disease are primarily symptomatic, with the major therapeutic strategy based on acetylcholinesterase inhibition. Alzheimer's disease research should advance over ensuing decade(s) to yield better symptomatic therapies, drugs designed to slow the rate of progression, and disease preventing agents. The next generation of cholinergic agents will include long acting cholinesterase inhibitors with a good safety profile and brain specific muscarinic agonists. The most critical advances in Alzheimer's disease treatment, however, will target slowing of disease progression and prevention of dementia. Therapeutic agents are being developed that interfere with the synthesis, deposition and aggregation of beta-amyloid protein. Clinical trials are presently being conducted with small molecules having nerve growth factor like activity (e.g. AIT-082, cerebrolysin). In addition, estrogen, anti-inflammatory agents (e.g. cyclooxygenase inhibitors) and antioxidant approaches (e.g. vitamin E) are currently being proposed or utilized in disease prevention trials.