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Li TR, Liu FQ. β-Amyloid promotes platelet activation and activated platelets act as bridge between risk factors and Alzheimer's disease. Mech Ageing Dev 2022; 207:111725. [PMID: 35995275 DOI: 10.1016/j.mad.2022.111725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/07/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022]
Abstract
Alzheimer's disease (AD) is an evolving challenge that places an enormous burden on families and society. The presence of obvious brain β-amyloid (Aβ) deposition is a premise to diagnose AD, which induces the subsequent tau hyperphosphorylation and neurodegeneration. Platelets are the primary source of circulating amyloid precursor protein (APP). Upon activation, they can secrete significant amounts of Aβ into the blood, which can be actively transported to the brain across the blood-brain barrier and promote amyloid deposition. In this review, we summarized the changes in the platelet APP metabolic pathway in patients with AD and further comprehensively explored the targets and downstream events of Aβ-activated platelets. In addition, we attempted to clarify whether patients with AD are in a state of general platelet activation, with inconsistent results. Considering the increasingly evident bidirectional relationship between AD and vascular events, we speculate that the AD pathology alone seems to be insufficient to induce the general activation of platelets; however, the intervention of third-party factors, such as atherosclerosis, exposes the extracellular matrix and leads to platelet activation, further promoting AD progression. Therefore, we proposed a framework in which the relationship between platelets and AD is indirect and mediated by vascular factors. Therapies targeting platelets and interventions for vascular risk factors are likely to contribute to the prevention and treatment of AD.
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Affiliation(s)
- Tao-Ran Li
- Department of Neurology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
| | - Feng-Qi Liu
- Department of Hematology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
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2
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Platelet APP Processing: Is It a Tool to Explore the Pathophysiology of Alzheimer's Disease? A Systematic Review. Life (Basel) 2021; 11:life11080750. [PMID: 34440494 PMCID: PMC8401829 DOI: 10.3390/life11080750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022] Open
Abstract
The processing of the amyloid precursor protein (APP) is a critical event in the formation of amyloid plaques. Platelets contain most of the enzymatic machinery required for APP processing and correlates of intracerebral abnormalities have been demonstrated in platelets of patients with AD. The goal of the present paper was to analyze studies exploring platelet APP metabolism in Alzheimer's disease patients trying to assess potential reliable peripheral biomarkers, to offer new therapeutic solutions and to understand the pathophysiology of the AD. According to the PRISMA guidelines, we performed a systematic review through the PubMed database up to June 2020 with the search terms: "((((((APP) OR Amyloid Precursor Protein) OR AbetaPP) OR Beta Amyloid) OR Amyloid Beta) OR APP-processing) AND platelet". Thirty-two studies were included in this systematic review. The papers included are analytic observational studies, namely twenty-nine cross sectional studies and three longitudinal studies, specifically prospective cohort study. The studies converge in an almost unitary way in affirming that subjects with AD show changes in APP processing compared to healthy age-matched controls. However, the problem of the specificity and sensitivity of these biomarkers is still at issue and would deserve to be deepened in future studies.
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Guzman-Martinez L, Maccioni RB, Farías GA, Fuentes P, Navarrete LP. Biomarkers for Alzheimer’s Disease. Curr Alzheimer Res 2019; 16:518-528. [DOI: 10.2174/1567205016666190517121140] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/08/2019] [Accepted: 04/25/2019] [Indexed: 12/15/2022]
Abstract
Alzheimer´s disease (AD) and related forms of dementia are increasingly affecting the aging population throughout the world, at an alarming rate. The World Alzheimer´s Report indicates a prevalence of 46.8 million people affected by AD worldwide. As population ages, this number is projected to triple by 2050 unless effective interventions are developed and implemented. Urgent efforts are required for an early detection of this disease. The ultimate goal is the identification of viable targets for the development of molecular markers and validation of their use for early diagnosis of AD that may improve treatment and the disease outcome in patients. The diagnosis of AD has been difficult to resolve since approaches for early and accurate detection and follow-up of AD patients at the clinical level have been reported only recently. Some proposed AD biomarkers include the detection of pathophysiological processes in the brain in vivo with new imaging techniques and novel PET ligands, and the determination of pathogenic proteins in cerebrospinal fluid showing anomalous levels of hyperphosphorylated tau and low Aβ peptide. These biomarkers have been increasingly accepted by AD diagnostic criteria and are important tools for the design of clinical trials, but difficulties in accessibility to costly and invasive procedures have not been completely addressed in clinical settings. New biomarkers are currently being developed to allow determinations of multiple pathological processes including neuroinflammation, synaptic dysfunction, metabolic impairment, protein aggregation and neurodegeneration. Highly specific and sensitive blood biomarkers, using less-invasive procedures to detect AD, are derived from the discoveries of peripheric tau oligomers and amyloid variants in human plasma and platelets. We have also developed a blood tau biomarker that correlates with a cognitive decline and also with neuroimaging determinations of brain atrophy.
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The platelet amyloid precursor protein ratio as a diagnostic marker for Alzheimer’s disease in Thai patients. J Clin Neurosci 2013; 20:644-8. [DOI: 10.1016/j.jocn.2012.06.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 05/29/2012] [Accepted: 06/01/2012] [Indexed: 11/18/2022]
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5
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Evin G, Li QX. Platelets and Alzheimer’s disease: Potential of APP as a biomarker. World J Psychiatry 2012; 2:102-13. [PMID: 24175176 PMCID: PMC3782192 DOI: 10.5498/wjp.v2.i6.102] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 07/13/2012] [Accepted: 07/23/2012] [Indexed: 02/05/2023] Open
Abstract
Platelets are the first peripheral source of amyloid precursor protein (APP). They possess the proteolytic machinery to produce Aβ and fragments similar to those produced in neurons, and thus offer an ex-vivo model to study APP processing and changes associated with Alzheimer’s disease (AD). Platelet process APP mostly through the α-secretase pathway to release soluble APP (sAPP). They produce small amounts of Aβ, predominantly Aβ40 over Aβ42. sAPP and Aβ are stored in α-granules and are released upon platelet activation by thrombin and collagen, and agents inducing platelet degranulation. A small proportion of full-length APP is present at the platelet surface and this increases by 3-fold upon platelet activation. Immunoblotting of platelet lysates detects APP as isoforms of 130 kDa and 106-110 kDa. The ratio of these of APP isoforms is significantly lower in patients with AD and mild cognitive impairment (MCI) than in healthy controls. This ratio follows a decrease that parallels cognitive decline and can predict conversion from MCI to AD. Alterations in the levels of α-secretase ADAM10 and in the enzymatic activities of α- and β-secretase observed in platelets of patients with AD are consistent with increased processing through the amyloidogenic pathway. β-APP cleaving enzyme activity is increased by 24% in platelet membranes of patients with MCI and by 17% in those with AD. Reports of changes in platelet APP expression with MCI and AD have been promising so far and merit further investigation as the search for blood biomarkers in AD, in particular at the prodromal stage, remains a priority and a challenge.
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Affiliation(s)
- Geneviève Evin
- Geneviève Evin, Qiao-Xin Li, Department of Pathology and Mental Health Research Institute, The University of Melbourne, Parkville 3010, Australia
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6
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Blood-based protein biomarkers for diagnosis and classification of neurodegenerative diseases: current progress and clinical potential. Mol Diagn Ther 2011; 15:83-102. [PMID: 21623645 DOI: 10.1007/bf03256398] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
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.
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Vignini A, Sartini D, Morganti S, Nanetti L, Luzzi S, Provinciali L, Mazzanti L, Emanuelli M. Platelet amyloid precursor protein isoform expression in Alzheimer's disease: evidence for peripheral marker. Int J Immunopathol Pharmacol 2011; 24:529-34. [PMID: 21658330 DOI: 10.1177/039463201102400229] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by a progressive cognitive and memory decline. Among peripheral markers of AD, great interest has been focused on the amyloid precursor protein (APP). In this regard, platelets represent an important peripheral source of APP since it has been demonstrated that the three major isoforms, that are constituted of 770, 751 and 695 aa residues, are inserted in the membrane of resting platelets. APP 751 and APP 770 contain a Kunitz-type serine protease inhibitor domain (APP KPI) and APP 695 lacks this domain. To address this issue, we first examined the platelet APP isoform mRNAs prospectively as biomarker for the diagnosis of AD by means of real-time quantitative PCR, and then evaluated the correlation between APP mRNA expression levels and cognitive impairment of enrolled subjects. Differential gene expression measurements in the AD patient group (n=18) revealed a significant up-regulation of APP TOT (1.52-fold), APP KPI (1.32-fold), APP 770 (1.33-fold) and APP 751 (1.26-fold) compared to controls (n=22). Moreover, a statistically significant positive correlation was found between APP mRNA levels (TOT, KPI, 770 and 751) and cognitive impairment. Since AD definitive diagnosis still relies on pathological evaluation at autopsy, the present results are consistent with the hypothesis that platelet APP could be considered a potential reliable peripheral marker for studying AD and could contribute to define a signature for the presence of AD pathology.
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Schneider P, Hampel H, Buerger K. Biological marker candidates of Alzheimer's disease in blood, plasma, and serum. CNS Neurosci Ther 2009; 15:358-74. [PMID: 19840034 DOI: 10.1111/j.1755-5949.2009.00104.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
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.
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Affiliation(s)
- Philine Schneider
- Department of Psychiatry, Ludwig-Maximilian University, Alzheimer Memorial Center, Munich, Germany.
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9
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Smith CCT, Prichard BNC, Cooper MB. Platelet α- and β-secretase activities: A preliminary study in normal human subjects. Platelets 2009; 20:29-34. [DOI: 10.1080/09537100802334434] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Wang Q, Zengin A, Ying W, Newell KA, Wang P, Yeo W, Wong PTH, Yenari MA, Huang XF. Chronic treatment with simvastatin upregulates muscarinic M1/4 receptor binding in the rat brain. Neuroscience 2008; 154:1100-6. [PMID: 18501522 DOI: 10.1016/j.neuroscience.2008.04.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 04/10/2008] [Accepted: 04/10/2008] [Indexed: 10/22/2022]
Abstract
Statins are increasingly being used for the treatment of a variety of conditions beyond their original indication for cholesterol lowering. We previously reported that simvastatin affected the dopaminergic system in the rat brain. This study aims to investigate regional changes of muscarinic M1/4 receptors in the rat brain after 4-week administration of simvastatin (1 or 10 mg/kg/day). M1/4 receptor distribution and alterations in the post-mortem rat brain were detected by [(3)H]pirenzepine binding autoradiography. Simvastatin (1 mg/kg/day) increased [(3)H]pirenzepine binding, predominantly in the prefrontal cortex (171%, P<0.001), primary motor cortex (153%, P=0.001), cingulate cortex (109%, P<0.001), hippocampus (138%, P<0.001), caudate putamen (122%, P=0.002) and nucleus accumbens (170%, P<0.001) compared with controls; while lower but still significant increases of [(3)H]pirenzepine binding were observed in the examined regions following simvastatin (10 mg/kg/day) treatment. Our results also provide strong evidence that chronic simvastatin administration, especially at a low dosage, up-regulates M1/4 receptor binding, which is likely to be independent of its muscarinic agonist-like effect. Alterations in [(3)H]pirenzepine binding in the examined brain areas may represent the specific regions that mediate the clinical effects of simvastatin treatment on cognition and memory via the muscarinic cholinergic system. These findings contribute to a better understanding of the critical roles of simvastatin in treating neurodegenerative disorders, via muscarinic receptors.
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Affiliation(s)
- Q Wang
- Neurobiology Research Centre, School of Health Sciences and Graduate School of Medicine, University of Wollongong, Wollongong, NSW 2522, Australia.
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11
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12
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Affiliation(s)
- T Augy
- Service de Pharmacie, Hôpital de la Conception, Assistance Publique des Hôpitaux de Marseille, 13395 Marseille cedex 5
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Sparks DL, Sabbagh M, Connor D, Soares H, Lopez J, Stankovic G, Johnson-Traver S, Ziolkowski C, Browne P. Statin therapy in Alzheimer's disease. Acta Neurol Scand 2006; 185:78-86. [PMID: 16866915 DOI: 10.1111/j.1600-0404.2006.00689.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous studies have suggested that statin therapy may be of benefit in treating Alzheimer's disease (AD). We initiated a double-blind, placebo-controlled, randomized (1:1) trial with a 1-year exposure to once-daily atorvastatin calcium (80 mg; two 40 mg tablets) or placebo among individuals with mild-to-moderate AD [Mini-Mental State Examination (MMSE) score of 12-28]. Stable dose use of cholinesterase inhibitors, estrogen and vitamin E was allowed, as was the use of most other medications in the treatment of co-morbidities. We demonstrated that atorvastatin treatment produced significantly (P = 0.003) improved performance on cognition and memory after 6 months of treatment (ADAS-cog) among patients with mild-to-moderate AD. This superior effect persisted at 1 year (P = 0.055). This positive effect on the ADAS-cog performance after 6 months of treatment was more prominent among individuals entering the trial with higher MMSE scores (P = 0.054). Benefit on other clinical measures was identified in the atorvastatin-treated population compared with placebo. Accordingly, atorvastatin therapy may be of benefit in the treatment of mild-to-moderately affected AD patients, but the level of benefit produced may be predicated on earlier treatment. Evidence also suggests that atorvastatin may slow the progression of mild-to-moderate AD, thereby prolonging the quality of an afflicted individual's life.
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Affiliation(s)
- D L Sparks
- Robert Laboratory for Neurodegenerative Disease Research, Sun Health Research Institute, Sun City, AZ 85351, USA.
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Abstract
Cholesterol and the cholesterol oxide 24S-hydroxycholesterol (24S-HC) are highly enriched in the human CNS. Clinical, genetic, neurochemical and epidemiological evidence continue to support dysfunctional cholesterol metabolism as an important contributing factor driving the development and/or progression of Alzheimer's disease (AD) neuropathology. Cholesterol overabundance in the brain plasma membrane lipid- raft domains, appears to be fundamental to the generation of the more neurotoxic forms of amyloid-beta (Abeta) peptide from beta-amyloid holoprotein precursor. 24S-HC may have a pivotal role in promoting altered inflammatory signaling, apoptotic genetic responses and AD-type change. In clinical studies, cholesterol-lowering statins, nonsteroidal anti-inflammatory drugs, cholesterol absorption/transport inhibitors and related modulators of cholesterol trafficking have demonstrated some pharmacological benefit for the treatment of AD, but overall their efficacy at slowing the cognitive decline and the progression of AD remains controversial and open to question.
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Affiliation(s)
- Walter J Lukiw
- Louisiana State University Health Sciences Center, LSU Neuroscience Center and Department of Ophthalmology, 2020 Gravier Street, Suite 8B8, New Orleans, LA 70112-2272, USA.
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Xiu J, Nordberg A, Qi X, Guan ZZ. Influence of cholesterol and lovastatin on alpha-form of secreted amyloid precursor protein and expression of alpha7 nicotinic receptor on astrocytes. Neurochem Int 2006; 49:459-65. [PMID: 16675062 DOI: 10.1016/j.neuint.2006.03.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
The influence of cholesterol and the lovastatin (cholesterol-lowering drug) on secretion of alpha-secretase cleavage product of amyloid precursor protein (APP) and expression of nicotinic acetylcholine receptors (nAChRs) was investigated in human HTB-15 astrocytes. The results showed that exposure of cholesterol to astrocytes inhibited the secretion of alpha-form of secreted APP (alphaAPPs) and reduced cell viability, while lovastatin enhanced the alpha-secretase processing on astrocytes; cholesterol treatment decreased expression of alpha7 nAChR, whereas lovastatin induced an up-regulation of the receptor; the increase in alphaAPPs resulted from lovastatin was partially inhibited by the alpha7 nAChR antagonists, alpha-bungarotoxin or methyllycaconitine; cholesterol or lovastatin did not influence either whole APP level or expression of alpha4 nAChR. We suggest that high dose of cholesterol may inhibit both the activity of alpha-secretase in APP metabolic processing and the expression of alpha7 nAChR, while lovastatin may stimulate alpha-secretase cleavage processing that might be regulated by alpha7 nAChR.
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Affiliation(s)
- Jin Xiu
- Karolinska Institutet, Neurotec Department, Division of Molecular Neuropharmacology, 141 86 Stockholm, Sweden
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Solfrizzi V, D'Introno A, Colacicco AM, Capurso C, Todarello O, Pellicani V, Capurso SA, Pietrarossa G, Santamato V, Capurso A, Panza F. Circulating biomarkers of cognitive decline and dementia. Clin Chim Acta 2006; 364:91-112. [PMID: 16139826 DOI: 10.1016/j.cca.2005.06.015] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 06/16/2005] [Accepted: 06/17/2005] [Indexed: 11/24/2022]
Abstract
Plasma and serum biochemical markers proposed for cognitive decline of degenerative (Alzheimer's disease, AD) or vascular origin and predementia syndromes (mild cognitive impairment and other related entities) are based on pathophysiologic processes such as lipoprotein metabolism (total cholesterol, apolipoprotein E, 24S-hydroxy-cholesterol), and vascular disease (homocysteine, lipoprotein(a)); SP formation (amyloid beta(Abeta)-protein, Abeta autoantibodies, platelet APP isoforms), oxidative stress (isoprostanes, vitamin E), and inflammation (cytokines). This review will focus on the current knowledge on circulating serum and plasma biomarkers of cognitive decline and dementia that are linked to cholesterol homeostasis and lipoprotein abnormalities, senile plaque formation and amyloid precursor protein (APP) metabolism, oxidative stress, and inflammatory reactions. Special emphasis will, however, be placed on biomarkers related to lipoprotein metabolism and vascular disease. Analytically, most plasma and serum proteins or metabolites lack reproducibility, sensitivity, or specificity for the diagnosis, risk and progression assessment, or therapeutic monitoring of AD and other dementing disorders. Measures linked to lipoprotein metabolism and vascular disease, APP metabolism, oxidative stress, or inflammation appear altered in AD relative to controls, but lack sufficient discriminatory power. Measures combining several biomarkers or incorporating a range of proteins in plasma and small molecule metabolites are promising approaches for the development of plasma or serum-based diagnostic tests for AD and other dementing disorders, as well as for predementia syndromes.
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Affiliation(s)
- Vincenzo Solfrizzi
- Department of Geriatrics, Center for Aging Brain, Memory Unit, University of Bari, Policlinico, Piazza Giulio Cesare, 11-70124 Bari, Italy
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Rosenberg RN. Translational research on the way to effective therapy for Alzheimer disease. ARCHIVES OF GENERAL PSYCHIATRY 2005; 62:1186-92. [PMID: 16275806 PMCID: PMC1479851 DOI: 10.1001/archpsyc.62.11.1186] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CONTEXT Alzheimer disease (AD) is a major public health issue with a prediction of 12 million Americans being affected by 2025 from the present 4 million. Molecular and genetic findings have provided significant insights into the roles that amyloid, tau, and apolipoprotein E isoforms have in the causation of AD. A central issue in AD pathogenesis is the amyloid cascade hypothesis. It states that abnormal amyloid processing and accumulation is the primary causative factor of AD and other associated neuropathologic abnormalities are of secondary consequence. It is presented to provide the rationale for novel drug and vaccination therapeutic strategies. Future research directed at prediction and prevention of AD through a genomic and proteomic analysis with identification of multiple polymorphic genes that interact, resulting in increased risk for late-onset AD, are the realistic and ultimate goals. A new approach for drug development is required, one that will emphasize a genomic and proteomic analysis to identify at-risk gene sets whose genetic expression is sufficient to cause late onset, sporadic AD. Prediction and prevention of disease prior to clinical signs and symptoms are the goals. OBJECTIVE A review and analysis from electronic literature databases and subsequent reference searches of the molecular genetic data. including pertinent genetic mutations and abnormal biochemical findings causal of AD, are cited. The amyloid cascade hypothesis, the contributions of apolipoprotein E, and hyperphosphorylated tau are discussed as to their roles in pathogenesis. Molecular targets for potential drug and vaccination therapies are cited from a critical assessment of the molecular and biomedical data. These data form the basis for rational, target-specific drug and vaccination therapies currently employed and planned for the near future. Phase 2 and 3 clinical trial results of drug and vaccination therapies are cited. CONCLUSIONS A new approach is needed as current pharmacologic therapy directed at symptomatic relief has proved to be marginally effective. The genomic and proteomic basis of AD will be defined in the near future, and corresponding molecular therapeutic targets will be identified. Genomic neurology has arrived and its application to resolving AD is our best hope.
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Affiliation(s)
- Roger N Rosenberg
- Department of Neurology and the Alzheimer's Disease Center, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9036, USA.
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Expression and activity of β-site amyloid precursor protein cleaving enzyme in Alzheimer's disease. Biochem Soc Trans 2005. [DOI: 10.1042/bst0331096] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several lines of evidence indicate that the Aβ peptide is involved at some level in the pathological process that results in the clinical symptoms of AD (Alzheimer's disease). The N-terminus of Aβ is generated by cleavage of the Met-Asp bond at position 671–672 of APP (amyloid precursor protein), catalysed by a proteolytic activity called β-secretase. Two ‘β-secretase’ proteases have been identified: BACE (β-site APP-cleaving enzyme) and BACE2. The cause of sporadic AD is currently unknown, but some studies have reported elevated BACE/β-secretase activity in brain regions affected by the disease. We have demonstrated that robust β-secretase activity is also detectable in platelets that contain APP and release Aβ. This review considers the current evidence for alterations in β-secretase activity, and/or alterations in BACE expression, in post-mortem brain tissue and platelets from individuals with AD.
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Tang K, Hynan LS, Baskin F, Rosenberg RN. Platelet amyloid precursor protein processing: a bio-marker for Alzheimer's disease. J Neurol Sci 2005. [PMID: 16256140 DOI: 10.1016/j.jns.2005.09.002s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The amyloid precursor protein (APP) in brain is processed either by an amyloidogenic pathway by beta-secretase and gamma-secretase to yield Abeta (beta-amyloid 4 kDa) peptide or by alpha-secretase within the beta-amyloid domain to yield non-amyloidogenic products. We have studied blood platelet levels of a 22-kDa fragment containing the Abeta (beta-amyloid 4 kDa) peptide, beta-secretase (BACE1), alpha-secretase (ADAM10), and APP isoform ratios of the 120-130 kDa to 110 kDa peptides from 31 Alzheimer's disease (AD) patients and 10 age-matched healthy control subjects. We found increased levels of Abeta4, increased activation of beta-secretase (BACE1), decreased activation of alpha-secretase (ADAM10) and decreased APP ratios in AD patients compared to normal control subjects. These observations indicate that the blood platelet APP is processed by the same amyloidogenic and non-amyloidogenic pathways as utilized in brain and that APP processing in AD patients is altered compared to control subjects and may be a useful bio-marker for the diagnosis of AD, the progression of disease and for monitoring drug responses in clinical trials.
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Affiliation(s)
- Kun Tang
- Department of Neurology, University of Texas Southwestern Medical Center at Dallas, United States
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Tang K, Hynan LS, Baskin F, Rosenberg RN. Platelet amyloid precursor protein processing: a bio-marker for Alzheimer's disease. J Neurol Sci 2005; 240:53-8. [PMID: 16256140 PMCID: PMC1479090 DOI: 10.1016/j.jns.2005.09.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Revised: 09/06/2005] [Accepted: 09/08/2005] [Indexed: 01/09/2023]
Abstract
The amyloid precursor protein (APP) in brain is processed either by an amyloidogenic pathway by beta-secretase and gamma-secretase to yield Abeta (beta-amyloid 4 kDa) peptide or by alpha-secretase within the beta-amyloid domain to yield non-amyloidogenic products. We have studied blood platelet levels of a 22-kDa fragment containing the Abeta (beta-amyloid 4 kDa) peptide, beta-secretase (BACE1), alpha-secretase (ADAM10), and APP isoform ratios of the 120-130 kDa to 110 kDa peptides from 31 Alzheimer's disease (AD) patients and 10 age-matched healthy control subjects. We found increased levels of Abeta4, increased activation of beta-secretase (BACE1), decreased activation of alpha-secretase (ADAM10) and decreased APP ratios in AD patients compared to normal control subjects. These observations indicate that the blood platelet APP is processed by the same amyloidogenic and non-amyloidogenic pathways as utilized in brain and that APP processing in AD patients is altered compared to control subjects and may be a useful bio-marker for the diagnosis of AD, the progression of disease and for monitoring drug responses in clinical trials.
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Affiliation(s)
- Kun Tang
- Department of Neurology, University of Texas Southwestern Medical Center at Dallas, United States
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Lukiw WJ, Pappolla M, Pelaez RP, Bazan NG. Alzheimer's disease--a dysfunction in cholesterol and lipid metabolism. Cell Mol Neurobiol 2005; 25:475-83. [PMID: 16075376 DOI: 10.1007/s10571-005-4010-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 08/03/2004] [Indexed: 12/13/2022]
Abstract
1. Strong etiological association exists between dysfunctional metabolism of brain lipids, age-related changes in the cerebral vasculature and neurodegenerative features characteristic of Alzheimer's disease (AD) brain. 2. In this short review, recent experimental evidence for these associations is further discussed below.
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Affiliation(s)
- Walter J Lukiw
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 8D, New Orleans, Louisiana, 70112-2272, USA.
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Liu HC, Chi CW, Ko SY, Wang HC, Hong CJ, Lin KN, Wang PN, Liu TY. Cholinesterase inhibitor affects the amyloid precursor protein isoforms in patients with Alzheimer's disease. Dement Geriatr Cogn Disord 2005; 19:345-8. [PMID: 15785036 DOI: 10.1159/000084561] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/01/2004] [Indexed: 11/19/2022] Open
Abstract
An altered platelet ratio of amyloid precursor protein (APP) isoforms might be a diagnostic, predictive, or therapeutic marker for Alzheimer's disease (AD). Our purpose was to test the hypothesis that this ratio might serve as a therapeutic marker for AD patients treated with the cholinesterase inhibitor, galantamine. Thirty-nine patients (mean age 76.6 +/- 9.4 years) with AD were treated with galantamine for 12 weeks. Patients were evaluated at baseline, 4 and 12 weeks by cognitive testing along with a determination of their platelet APP isoform ratio. Western blotting was performed to calculate the APP isoform ratio. At the end of the treatment, cognitive scores significantly improved, and the ratio of the high-molecular-weight (130 kDa) isoform to the low-molecular-weight (110-106 kDa) isoforms increased. These results suggest that cholinesterase inhibition might be involved in APP processing.
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Affiliation(s)
- H C Liu
- Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan
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23
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Padovani A, Borroni B, Di Luca M. Advances on biological markers in early diagnosis of Alzheimer disease. Adv Clin Chem 2005; 39:107-29. [PMID: 16013669 DOI: 10.1016/s0065-2423(04)39004-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Alessandro Padovani
- Department of Neurological Sciences, University of Brescia, 25100 Brescia, Italy
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Xiu J, Nordberg A, Shan KR, Yu WF, Olsson JM, Nordman T, Mousavi M, Guan ZZ. Lovastatin stimulates up-regulation of α7 nicotinic receptors in cultured neurons without cholesterol dependency, a mechanism involving production of the α-form of secreted amyloid precursor protein. J Neurosci Res 2005; 82:531-41. [PMID: 16240392 DOI: 10.1002/jnr.20658] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cholesterol-lowering drug lovastatin enhances the secretion of the alpha-secretase cleavage product of amyloid precursor protein (APP). To investigate whether this effect is mediated via activation of alpha7 nicotinic acetylcholine receptors (nAChRs), we treated SH-SY5Y cells and PC12 cells with lovastatin and measured the levels of alpha7 nAChRs, the alpha-form of secreted APP (alphaAPPs), and lovastatin-related lipids, including cholesterol and ubiquinone. The results showed that low concentrations of lovastatin significantly induced up-regulation of alpha7 nAChRs. No effects of lovastatin were observed on alpha3-containing nAChRs, muscarinic receptors, or N-methyl-D-aspartate receptors. alphaAPPs levels increased in the culture medium of cells treated with lovastatin, whereas no change in whole APP was observed. The increase in alphaAPPs was inhibited by prior exposure of these cells to alpha-bungarotoxin, an antagonist of alpha7 nAChRs. The concentrations of lovastatin used in the study did not change the cholesterol content, but high doses can decrease the levels of ubiquinone and cell viability. These results indicate that lovastatin may play a neuronal role that is cholesterol independent. We also show that the up-regulation of alpha7 nAChRs stimulated by lovastatin is involved in a mechanism that enhances production of alphaAPPs during APP processing.
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MESH Headings
- Amyloid beta-Protein Precursor/biosynthesis
- Animals
- Blotting, Northern/methods
- Blotting, Western/methods
- Bridged Bicyclo Compounds, Heterocyclic/pharmacokinetics
- Bungarotoxins/pharmacology
- Cell Line, Tumor
- Cholesterol/metabolism
- Chromatography, High Pressure Liquid/methods
- Dose-Response Relationship, Drug
- Drug Interactions
- Humans
- Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology
- Isotopes/pharmacokinetics
- Lovastatin/pharmacology
- Neuroblastoma
- Neurons/drug effects
- Neurons/metabolism
- Nicotine/pharmacology
- Nicotinic Agonists/pharmacokinetics
- PC12 Cells
- Protein Binding/drug effects
- Pyridines/pharmacokinetics
- Quinuclidinyl Benzilate/pharmacokinetics
- RNA, Messenger/metabolism
- Radioligand Assay/methods
- Rats
- Receptors, N-Methyl-D-Aspartate/metabolism
- Receptors, Nicotinic/genetics
- Receptors, Nicotinic/metabolism
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Ubiquinone/metabolism
- Up-Regulation/drug effects
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Affiliation(s)
- Jin Xiu
- Neurotec Department, Division of Molecular Neuropharmacology, Karolinska Institutet, Stockholm, Sweden
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Wolozin B, Brown J, Theisler C, Silberman S. The cellular biochemistry of cholesterol and statins: insights into the pathophysiology and therapy of Alzheimer's disease. CNS DRUG REVIEWS 2004; 10:127-46. [PMID: 15179443 PMCID: PMC6741763 DOI: 10.1111/j.1527-3458.2004.tb00009.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The causes of late onset Alzheimer disease (AD) are poorly understood. Although beta-amyloid (Abeta) is thought to play a critical role in the pathophysiology of AD, no genetic evidence directly ties Abeta to late onset AD. This suggests that the accumulation of Abeta and neurodegeneration associated with AD might result from an abnormality that indirectly affects Abeta production or accumulation. Increasing evidence suggests that abnormalities in the metabolism of cholesterol and related molecules, such as cholseterol esters and 24(S) hydroxycholesterol might contribute to the pathophysiology of late onset AD by increasing production of Abeta. 24(S) Hydroxycholesterol is a member of a family of oxidized cholesterol catabolites, termed oxysterols, which function to regulate export of cholesterol from the cell and transcription of genes related to cholesterol metabolism. Cholesterol esters are cholesterol derivatives used for cholesterol storage. Levels of 24(S) hydroxycholesterol increase with AD. Polymorphisms in several different genes important for cholesterol physiology are associated with an increased load or level of Abeta in AD. These genes include apolipoprotein E, cholesterol 24 hydroxylase (Cyp46), acyl-CoA:cholesterol acetyltransferase (ACAT), and the cholesterol transporter ABCA1. Other studies show that levels of cholesterol, or its precursors, are elevated in subjects early in the course of AD. Finally, studies of the processing of amyloid precursor protein show that cholesterol and its catabolites modulate amyloid precursor protein processing and Abeta production. These lines of evidence raise the possibility that genetic abnormalities in cholesterol metabolism might contribute to the pathophysiology of AD.
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Affiliation(s)
- Benjamin Wolozin
- Department of Pharmacology, Loyola University Medical Center, Bldg. 102, Rm. 3634, 2160 South First Ave., Maywood, IL 60153, USA.
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26
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Biomarkers of Alzheimer disease in plasma. Neurotherapeutics 2004. [DOI: 10.1007/bf03206606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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27
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Abstract
Plasma and serum biochemical markers proposed for Alzheimer disease (AD) are based on pathophysiologic processes such as amyloid plaque formation [amyloid beta-protein (A beta), A beta autoantibodies, platelet amyloid precursor protein (APP) isoforms], inflammation (cytokines), oxidative stress (vitamin E, isoprostanes), lipid metabolism (apolipoprotein E, 24S-hydroxycholesterol), and vascular disease [homocysteine, lipoprotein (a)]. Most proteins or metabolites evaluated in plasma or serum thus far are, at best, biological correlates of AD: levels are statistically different in AD versus controls in some cohorts, but they lack sensitivity or specificity for diagnosis or for tracking response to therapy. Approaches combining panels of existing biomarkers or surveying the range of proteins in plasma (proteomics) show promise for discovering biomarker profiles that are characteristic of AD, yet distinct from nondemented patients or patients with other forms of dementia.
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Affiliation(s)
- Michael C Irizarry
- Alzheimer Disease Research Unit, Department of Neurology, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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