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Maxwell AM, Yuan P, Rivera BM, Schaaf W, Mladinov M, Prasher VP, Robinson AC, DeGrado WF, Condello C. Emergence of distinct and heterogeneous strains of amyloid beta with advanced Alzheimer's disease pathology in Down syndrome. Acta Neuropathol Commun 2021; 9:201. [PMID: 34961556 PMCID: PMC8711167 DOI: 10.1186/s40478-021-01298-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 12/30/2022] Open
Abstract
Amyloid beta (Aβ) is thought to play a critical role in the pathogenesis of Alzheimer's disease (AD). Prion-like Aβ polymorphs, or "strains", can have varying pathogenicity and may underlie the phenotypic heterogeneity of the disease. In order to develop effective AD therapies, it is critical to identify the strains of Aβ that might arise prior to the onset of clinical symptoms and understand how they may change with progressing disease. Down syndrome (DS), as the most common genetic cause of AD, presents promising opportunities to compare such features between early and advanced AD. In this work, we evaluate the neuropathology and Aβ strain profile in the post-mortem brain tissues of 210 DS, AD, and control individuals. We assayed the levels of various Aβ and tau species and used conformation-sensitive fluorescent probes to detect differences in Aβ strains among individuals and populations. We found that these cohorts have some common but also some distinct strains from one another, with the most heterogeneous populations of Aβ emerging in subjects with high levels of AD pathology. The emergence of distinct strains in DS at these later stages of disease suggests that the confluence of aging, pathology, and other DS-linked factors may favor conditions that generate strains that are unique from sporadic AD.
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van Oostveen WM, de Lange ECM. Imaging Techniques in Alzheimer's Disease: A Review of Applications in Early Diagnosis and Longitudinal Monitoring. Int J Mol Sci 2021; 22:ijms22042110. [PMID: 33672696 PMCID: PMC7924338 DOI: 10.3390/ijms22042110] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting many individuals worldwide with no effective treatment to date. AD is characterized by the formation of senile plaques and neurofibrillary tangles, followed by neurodegeneration, which leads to cognitive decline and eventually death. INTRODUCTION In AD, pathological changes occur many years before disease onset. Since disease-modifying therapies may be the most beneficial in the early stages of AD, biomarkers for the early diagnosis and longitudinal monitoring of disease progression are essential. Multiple imaging techniques with associated biomarkers are used to identify and monitor AD. AIM In this review, we discuss the contemporary early diagnosis and longitudinal monitoring of AD with imaging techniques regarding their diagnostic utility, benefits and limitations. Additionally, novel techniques, applications and biomarkers for AD research are assessed. FINDINGS Reduced hippocampal volume is a biomarker for neurodegeneration, but atrophy is not an AD-specific measure. Hypometabolism in temporoparietal regions is seen as a biomarker for AD. However, glucose uptake reflects astrocyte function rather than neuronal function. Amyloid-β (Aβ) is the earliest hallmark of AD and can be measured with positron emission tomography (PET), but Aβ accumulation stagnates as disease progresses. Therefore, Aβ may not be a suitable biomarker for monitoring disease progression. The measurement of tau accumulation with PET radiotracers exhibited promising results in both early diagnosis and longitudinal monitoring, but large-scale validation of these radiotracers is required. The implementation of new processing techniques, applications of other imaging techniques and novel biomarkers can contribute to understanding AD and finding a cure. CONCLUSIONS Several biomarkers are proposed for the early diagnosis and longitudinal monitoring of AD with imaging techniques, but all these biomarkers have their limitations regarding specificity, reliability and sensitivity. Future perspectives. Future research should focus on expanding the employment of imaging techniques and identifying novel biomarkers that reflect AD pathology in the earliest stages.
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Affiliation(s)
- Wieke M. van Oostveen
- Faculty of Science, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands;
| | - Elizabeth C. M. de Lange
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre of Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
- Correspondence: ; Tel.: +31-71-527-6330
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Thamban Chandrika N, Fosso MY, Tsodikov OV, LeVine H, Garneau-Tsodikova S. Combining Chalcones with Donepezil to Inhibit Both Cholinesterases and Aβ Fibril Assembly. Molecules 2019; 25:E77. [PMID: 31878304 PMCID: PMC6983213 DOI: 10.3390/molecules25010077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/18/2019] [Accepted: 12/21/2019] [Indexed: 02/08/2023] Open
Abstract
The fact that the number of people with Alzheimer's disease is increasing, combined with the limited availability of drugs for its treatment, emphasize the need for the development of novel effective therapeutics for treating this brain disorder. Herein, we focus on generating 12 chalcone-donepezil hybrids, with the goal of simultaneously targeting amyloid-β (Aβ) peptides as well as cholinesterases (i.e., acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)). We present the design, synthesis, and biochemical evaluation of these two series of novel 1,3-chalcone-donepezil (15a-15f) or 1,4-chalcone-donepezil (16a-16f) hybrids. We evaluate the relationship between their structures and their ability to inhibit AChE/BChE activity as well as their ability to bind Aβ peptides. We show that several of these novel chalcone-donepezil hybrids can successfully inhibit AChE/BChE as well as the assembly of N-biotinylated Aβ(1-42) oligomers. We also demonstrate that the Aβ binding site of these hybrids differs from that of Pittsburgh Compound B (PIB).
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Affiliation(s)
- Nishad Thamban Chandrika
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA; (N.T.C.); (M.Y.F.); (O.V.T.)
| | - Marina Y. Fosso
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA; (N.T.C.); (M.Y.F.); (O.V.T.)
| | - Oleg V. Tsodikov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA; (N.T.C.); (M.Y.F.); (O.V.T.)
| | - Harry LeVine
- Center on Aging, School of Medicine, University of Kentucky, Lexington, KY 40536-0230, USA;
- Department of Molecular and Cellular Biochemistry, School of Medicine, University of Kentucky, Lexington, KY 40536-0230, USA
| | - Sylvie Garneau-Tsodikova
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536-0596, USA; (N.T.C.); (M.Y.F.); (O.V.T.)
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Novel 99mTc-2-arylimidazo[2,1-b]benzothiazole derivatives as SPECT imaging agents for amyloid-β plaques. Eur J Med Chem 2019; 175:149-161. [DOI: 10.1016/j.ejmech.2019.04.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/09/2019] [Accepted: 04/27/2019] [Indexed: 01/11/2023]
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5
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Grasso G. Mass spectrometry is a multifaceted weapon to be used in the battle against Alzheimer's disease: Amyloid beta peptides and beyond. MASS SPECTROMETRY REVIEWS 2019; 38:34-48. [PMID: 29905953 DOI: 10.1002/mas.21566] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
Amyloid-β peptide (Aβ) accumulation and aggregation have been considered for many years the main cause of Alzheimer's disease (AD), and therefore have been the principal target of investigation as well as of the proposed therapeutic approaches (Grasso [2011] Mass Spectrom Rev. 30: 347-365). However, the amyloid cascade hypothesis, which considers Aβ accumulation the only causative agent of the disease, has proven to be incomplete if not wrong. In recent years, actors such as metal ions, oxidative stress, and other cofactors have been proposed as possible co-agents or, in some cases, main causative factors of AD. In this scenario, MS investigation has proven to be fundamental to design possible diagnostic strategies of this elusive disease, as well as to understand the biomolecular mechanisms involved, in the attempt to find a possible therapeutic solution. We review the current applications of MS in the search for possible Aβ biomarkers of AD to help the diagnosis of the disease. Recent examples of the important contributions that MS has given to prove or build theories on the molecular pathways involved with such terrible disease are also reviewed.
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Affiliation(s)
- Giuseppe Grasso
- Department of Chemical Sciences, University of Catania, Catania, Italy
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6
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Wildburger NC, Gyngard F, Guillermier C, Patterson BW, Elbert D, Mawuenyega KG, Schneider T, Green K, Roth R, Schmidt RE, Cairns NJ, Benzinger TLS, Steinhauser ML, Bateman RJ. Amyloid-β Plaques in Clinical Alzheimer's Disease Brain Incorporate Stable Isotope Tracer In Vivo and Exhibit Nanoscale Heterogeneity. Front Neurol 2018; 9:169. [PMID: 29623063 PMCID: PMC5874304 DOI: 10.3389/fneur.2018.00169] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 03/06/2018] [Indexed: 01/01/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder with clinical manifestations of progressive memory decline and loss of executive function and language. AD affects an estimated 5.3 million Americans alone and is the most common form of age-related dementia with a rapidly growing prevalence among the aging population-those 65 years of age or older. AD is characterized by accumulation of aggregated amyloid-beta (Aβ) in the brain, which leads to one of the pathological hallmarks of AD-Aβ plaques. As a result, Aβ plaques have been extensively studied after being first described over a century ago. Advances in brain imaging and quantitative measures of Aβ in biological fluids have yielded insight into the time course of plaque development decades before and after AD symptom onset. However, despite the fundamental role of Aβ plaques in AD, in vivo measures of individual plaque growth, growth distribution, and dynamics are still lacking. To address this question, we combined stable isotope labeling kinetics (SILK) and nanoscale secondary ion mass spectrometry (NanoSIMS) imaging in an approach termed SILK-SIMS to resolve plaque dynamics in three human AD brains. In human AD brain, plaques exhibit incorporation of a stable isotope tracer. Tracer enrichment was highly variable between plaques and the spatial distribution asymmetric with both quiescent and active nanometer sub-regions of tracer incorporation. These data reveal that Aβ plaques are dynamic structures with deposition rates over days indicating a highly active process. Here, we report the first, direct quantitative measures of in vivo deposition into plaques in human AD brain. Our SILK-SIMS studies will provide invaluable information on plaque dynamics in the normal and diseased brain and offer many new avenues for investigation into pathological mechanisms of the disease, with implications for therapeutic development.
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Affiliation(s)
- Norelle C Wildburger
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Frank Gyngard
- Department of Physics, Washington University in St. Louis, St. Louis, MO, United States
| | - Christelle Guillermier
- NanoImaging Center, Division of Genetics, Brigham and Women's Hospital, Cambridge, MA, United States.,Brigham and Women's Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States
| | - Bruce W Patterson
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Donald Elbert
- Department of Neurology, The University of Texas at Austin Dell Medical School, Austin, TX, United States
| | - Kwasi G Mawuenyega
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Theresa Schneider
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Karen Green
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, United States
| | - Robyn Roth
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States.,Washington University Center for Cellular Imaging, Washington University School of Medicine, St. Louis, MO, United States
| | - Robert E Schmidt
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, United States
| | - Nigel J Cairns
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, United States.,Knight Alzheimer's Disease Research Center, Department of Neurology, Washington University School of Medicine, St Louis, MO, United States.,Hope Center for Neurological Disorders, Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Tammie L S Benzinger
- Knight Alzheimer's Disease Research Center, Department of Neurology, Washington University School of Medicine, St Louis, MO, United States.,Department of Radiology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, United States
| | - Matthew L Steinhauser
- NanoImaging Center, Division of Genetics, Brigham and Women's Hospital, Cambridge, MA, United States.,Brigham and Women's Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States
| | - Randall J Bateman
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States.,Knight Alzheimer's Disease Research Center, Department of Neurology, Washington University School of Medicine, St Louis, MO, United States.,Hope Center for Neurological Disorders, Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
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7
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Condello C, Yuan P, Grutzendler J. Microglia-Mediated Neuroprotection, TREM2, and Alzheimer's Disease: Evidence From Optical Imaging. Biol Psychiatry 2018; 83:377-387. [PMID: 29169609 PMCID: PMC5767550 DOI: 10.1016/j.biopsych.2017.10.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 10/05/2017] [Accepted: 10/06/2017] [Indexed: 12/19/2022]
Abstract
Recent genetic studies have provided overwhelming evidence of the involvement of microglia-related molecular networks in the pathophysiology of Alzheimer's disease (AD). However, the precise mechanisms by which microglia alter the course of AD neuropathology remain poorly understood. Here we discuss current evidence of the neuroprotective functions of microglia with a focus on optical imaging studies that have revealed a role of these cells in the encapsulation of amyloid deposits ("microglia barrier"). This barrier modulates the degree of plaque compaction, amyloid fibril surface area, and insulation from adjacent axons thereby reducing neurotoxicity. We discuss findings implicating genetic variants of the microglia receptor, triggering receptor expressed on myeloid cells 2, in the increased risk of late onset AD. We provide evidence that increased AD risk may be at least partly mediated by deficient microglia polarization toward amyloid deposits, resulting in ineffective plaque encapsulation and reduced plaque compaction, which is associated with worsened axonal pathology. Finally, we propose possible avenues for therapeutic targeting of plaque-associated microglia with the goal of enhancing the microglia barrier and potentially reducing disease progression.
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Affiliation(s)
- Carlo Condello
- Institute for Neurodegenerative Diseases, Weill Institute for Neurosciences, University of California, San Francisco, CA 94158, USA,Department of Neurology, University of California, San Francisco, CA 94158, USA
| | - Peng Yuan
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Jaime Grutzendler
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut; Department of Neuroscience, Yale School of Medicine, New Haven, Connecticut.
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8
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Abstract
Senile plaques and neurofibrillary tangles are the principal histopathologic hallmarks of Alzheimer disease. The essential constituents of these lesions are structurally abnormal variants of normally generated proteins: Aβ protein in plaques and tau protein in tangles. At the molecular level, both proteins in a pathogenic state share key properties with classic prions, i.e., they consist of alternatively folded, β-sheet-rich forms of the proteins that autopropagate by the seeded corruption and self-assembly of like proteins. Other similarities with prions include the ability to manifest as polymorphic and polyfunctional strains, resistance to chemical and enzymatic destruction, and the ability to spread within the brain and from the periphery to the brain. In Alzheimer disease, current evidence indicates that the pathogenic cascade follows from the endogenous, sequential corruption of Aβ and then tau. Therapeutic options include reducing the production or multimerization of the proteins, uncoupling the Aβ-tauopathy connection, or promoting the inactivation or removal of anomalous assemblies from the brain. Although aberrant Aβ appears to be the prime mover of Alzheimer disease pathogenesis, once set in motion by Aβ, the prion-like propagation of tauopathy may proceed independently of Aβ; if so, Aβ might be solely targeted as an early preventive measure, but optimal treatment of Alzheimer disease at later stages of the cascade could require intervention in both pathways.
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Affiliation(s)
- Lary C Walker
- Department of Neurology and Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States.
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9
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Villemagne VL, Rowe CC, Barnham KJ, Cherny R, Woodward M, Bozinosvski S, Salvado O, Bourgeat P, Perez K, Fowler C, Rembach A, Maruff P, Ritchie C, Tanzi R, Masters CL. A randomized, exploratory molecular imaging study targeting amyloid β with a novel 8-OH quinoline in Alzheimer's disease: The PBT2-204 IMAGINE study. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2017; 3:622-635. [PMID: 29201996 PMCID: PMC5702880 DOI: 10.1016/j.trci.2017.10.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Introduction We are developing a second generation 8-OH quinoline (2-(dimethylamino) methyl-5, 7-dichloro-8-hydroxyquinoline [PBT2, Prana Biotechnology]) for targeting amyloid β (Aβ) in Alzheimer's disease (AD). In an earlier phase IIa, 3 month trial, PBT2 lowered cerebrospinal fluid Aβ by 13% and improved cognition (executive function) in a dose-related fashion in early AD. We, therefore, sought to learn whether PBT2 could alter the Aβ-PET signal in subjects with prodromal or mild AD, in an exploratory randomized study over a 12-month phase in a double-blind and a 12-month open label extension phase trial design. Methods For inclusion, the usual clinical criteria for prodromal or probable AD, Mini–Mental State Examination ≥20, and global Pittsburgh compound B (PiB)-PET standardized uptake volume ratio (SUVR) >1.7 were used. As this was an exploratory study, we included contemporaneous matched control data from the Australian Imaging Biomarker and Lifestyle Study (AIBL). Other measures included fluorodeoxyglucose-positron emission tomography, magnetic resonance imaging volumetrics, blood Aβ biomarkers, and cognition and function. Results Forty subjects completed the first 12-month double-blind phase (placebo = 15, PBT2 = 25), and 27 subjects completed the 12-month open label extension phase (placebo = 11, PBT2 = 16). Overall, PTB2 250 mg/day was safe and well tolerated. The mean PiB-PET SUVR at baseline was 2.51 ± 0.59. After adjusting for baseline SUVR, in the double-blind phase, the placebo group showed a nonsignificant decline in PiB-PET SUVR, whereas the PBT2 group declined significantly (P = .048). Subjects who did not enter or complete the extension study had a significantly higher 12-month Aβ-PET SUVR (2.68 ± 0.55) compared with those who completed (2.29 ± 0.48). Both groups differed significantly from the rate of change over 12 months in the AIBL control group. In the open label 12-month extension study, the PiB-SUVR stabilized. There were no significant differences between PBT2 and controls in fluorodeoxyglucose-positron emission tomography, magnetic resonance imaging volumetrics, blood Aβ biomarkers, or cognition/function over the course of the double-blind phase. Discussion There was no significant difference between PBT2 and controls at 12 months, likely due to the large individual variances over a relatively small number of subjects. PBT2 was associated with a significant 3% PiB-PET SUVR decline in the double-blind phase and a stabilization of SUVR in the open-label phase. From this exploratory study, we have learned that the entry criterion of SUVR should have been set at ≥ 1.5 and <2.0, where we know from the AIBL study that subjects in this band are accumulating Aβ in a linear fashion and that subjects who withdrew from this type of study have much higher SUVRs, which if not taken into account, could distort the final results. Because of large individual variations in SUVR, future studies of PBT2 will require larger numbers of subjects (n > 90 per arm) over a longer period (18 months or more). Further evaluation of higher doses of PBT2 in earlier stages of AD is warranted. Trial Registration ACTRN 12611001008910 and ACTRN 12613000777796. Exploratory randomized controlled trial for Alzheimer's disease using novel 8-OH quinoline. Use of Aβ positron emission tomography molecular imaging as intake criterion. Small numbers, large variances, and higher than expected mean baseline standardized uptake volume ratio may have contributed to lack of demonstrable efficacy.
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Affiliation(s)
- Victor L Villemagne
- Department of Molecular Imaging and Therapy (Research), Austin Health, Melbourne, Victoria, Australia.,The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher C Rowe
- Department of Molecular Imaging and Therapy (Research), Austin Health, Melbourne, Victoria, Australia.,The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Kevin J Barnham
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Robert Cherny
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia.,Prana Biotechnology, Melbourne, Victoria, Australia
| | - Michael Woodward
- Medical and Cognitive Research Unit, Aged Care and Residential Services, Austin Health, Melbourne, Victoria, Australia
| | - Svetlana Bozinosvski
- Department of Molecular Imaging and Therapy (Research), Austin Health, Melbourne, Victoria, Australia
| | - Olivier Salvado
- Health and Biosecurity, CSIRO, Brisbane, Queensland, Australia
| | | | - Keyla Perez
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher Fowler
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Alan Rembach
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul Maruff
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia.,Cogstate Ltd, Melbourne, Victoria, Australia
| | - Craig Ritchie
- Psychiatry, University of Edinburgh, Edinburgh, Scotland, UK
| | - Rudy Tanzi
- Genetics and Aging Research Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Colin L Masters
- The Florey Institute, The University of Melbourne, Melbourne, Victoria, Australia
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Roberts BR, Lind M, Wagen AZ, Rembach A, Frugier T, Li QX, Ryan TM, McLean CA, Doecke JD, Rowe CC, Villemagne VL, Masters CL. Biochemically-defined pools of amyloid-β in sporadic Alzheimer's disease: correlation with amyloid PET. Brain 2017; 140:1486-1498. [PMID: 28383676 DOI: 10.1093/brain/awx057] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/20/2017] [Indexed: 02/06/2023] Open
Abstract
We fractionated frontal cortical grey matter from human Alzheimer's disease and control subjects into four biochemically defined pools that represent four distinct compartments: soluble/cytosolic, peripheral membrane/vesicular cargo, integral lipid/membranous pools and aggregated/insoluble debris. Most of the readily extractable amyloid-β remains associated with a lipid/membranous compartment. There is an exchange of amyloid-β between the biochemical pools that was lost for the amyloid-β42 species in Alzheimer's disease, consistent with the peptide being irreversibly trapped in extracellular deposits. The quantitative amyloid-β data, combined with magnetic resonance imaging volumetric analysis of the amount of cortical grey matter in brain, allowed us to estimate the total mass of amyloid-β in Alzheimer's disease (6.5 mg) and control (1.7 mg) brains. The threshold positron emission tomography standard uptake value ratio of 1.4 equates to 5.0 μg amyloid-β/g of grey matter and the mean Alzheimer's disease dementia standard uptake value ratio level of 2.3 equates to 11.20 μg amyloid-β/g of grey matter. It takes 19 years to accumulate amyloid from the threshold positron emission tomography standard uptake value ratio to the mean value observed for Alzheimer's disease dementia. This accumulation time window combined with the difference of 4.8 mg of amyloid-β between Alzheimer's disease and control brain allows for a first approximation of amyloid-β accumulation of 28 ng/h. This equates to an estimated 2-5% of the total amyloid-β production being deposited as insoluble plaques. Understanding these rates of amyloid-β accumulation allows for a more quantitative approach in targeting the failure of amyloid-β clearance in sporadic Alzheimer's disease.
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Affiliation(s)
- Blaine R Roberts
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Monica Lind
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Aaron Z Wagen
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alan Rembach
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tony Frugier
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Qiao-Xin Li
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Timothy M Ryan
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Catriona A McLean
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.,Department of Anatomical Pathology, Alfred Hospital, Prahran, Victoria 3004, Australia
| | - James D Doecke
- CSIRO Health and Biosecurity/Australian e-Health Research Centre and Cooperative Research Centre of Mental Health, Brisbane, QLD, Australia
| | - Christopher C Rowe
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.,Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia
| | - Victor L Villemagne
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.,Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, Victoria, Australia
| | - Colin L Masters
- The Florey Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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11
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Diner I, Nguyen T, Seyfried NT. Enrichment of Detergent-insoluble Protein Aggregates from Human Postmortem Brain. J Vis Exp 2017. [PMID: 29155708 DOI: 10.3791/55835] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
In this study, we describe an abbreviated single-step fractionation protocol for the enrichment of detergent-insoluble protein aggregates from human postmortem brain. The ionic detergent N-lauryl-sarcosine (sarkosyl) effectively solubilizes natively folded proteins in brain tissue allowing the enrichment of detergent-insoluble protein aggregates from a wide range of neurodegenerative proteinopathies, such as Alzheimer's disease (AD), Parkinson's disease and amyotrophic lateral sclerosis, and prion diseases. Human control and AD postmortem brain tissues were homogenized and sedimented by ultracentrifugation in the presence of sarkosyl to enrich detergent-insoluble protein aggregates including pathologic phosphorylated tau, the core component of neurofibrillary tangles in AD. Western blotting demonstrated the differential solubility of aggregated phosphorylated-tau and the detergent-soluble protein, Early Endosome Antigen 1 (EEA1) in control and AD brain. Proteomic analysis also revealed enrichment of β-amyloid (Aβ), tau, snRNP70 (U1-70K), and apolipoprotein E (APOE) in the sarkosyl-insoluble fractions of AD brain compared to those of control, consistent with previous tissue fractionation strategies. Thus, this simple enrichment protocol is ideal for a wide range of experimental applications ranging from Western blotting and functional protein co-aggregation assays to mass spectrometry-based proteomics.
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Affiliation(s)
- Ian Diner
- Department of Biochemistry, Emory School of Medicine
| | - Tram Nguyen
- Department of Biochemistry, Emory School of Medicine
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12
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Diner I, Dooyema J, Gearing M, Walker LC, Seyfried NT. Generation of Clickable Pittsburgh Compound B for the Detection and Capture of β-Amyloid in Alzheimer's Disease Brain. Bioconjug Chem 2017; 28:2627-2637. [PMID: 28862836 DOI: 10.1021/acs.bioconjchem.7b00500] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The benzothiazole-aniline derivative Pittsburgh Compound B (PiB) is the prototypical amyloid affinity probe developed for the in vivo positron emission tomography (PET) detection of amyloid beta (Aβ) deposits in Alzheimer's disease (AD). Specific high-affinity binding sites for PiB have been found to vary among AD cases with comparable Aβ load, and they are virtually absent on human-sequence Aβ deposits in animal models, none of which develop the full phenotype of AD. PiB thus could be an informative probe for studying the pathobiology of Aβ, but little is known about the localization of PiB binding at the molecular or structural level. By functionalizing the 6-hydroxy position of PiB with a PEG3 spacer and a terminal alkyne (propargyl) moiety, we have developed a clickable PiB compound that was derivatized with commercially available azide-labeled fluorophores or affinity-tags using copper-catalyzed azide-alkyne cycloaddition reactions, commonly referred to as "click" chemistry. We have determined that both the clickable PiB derivative and its fluorescently labeled conjugate have low nanomolar binding affinities for synthetic Aβ aggregates. Furthermore, the fluorescent-PiB conjugate can effectively bind Aβ aggregates in human AD brain homogenates and tissue sections. By covalently coupling PiB to magnetic beads, Aβ aggregates were also affinity-captured from AD brain extracts. Thus, the clickable PiB derivative described herein can be used to generate a wide variety of covalent conjugates, with applications including the fluorescence detection of Aβ, the ultrastructural localization of PiB binding, and the affinity capture and structural characterization of Aβ and other cofactors from AD brains.
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Affiliation(s)
- Ian Diner
- Department of Biochemistry, ‡Yerkes National Primate Research Center, §Department of Pathology and Laboratory Medicine, and ∥Department of Neurology, Emory University , Atlanta, Georgia 30322, United States
| | - Jeromy Dooyema
- Department of Biochemistry, ‡Yerkes National Primate Research Center, §Department of Pathology and Laboratory Medicine, and ∥Department of Neurology, Emory University , Atlanta, Georgia 30322, United States
| | - Marla Gearing
- Department of Biochemistry, ‡Yerkes National Primate Research Center, §Department of Pathology and Laboratory Medicine, and ∥Department of Neurology, Emory University , Atlanta, Georgia 30322, United States
| | - Lary C Walker
- Department of Biochemistry, ‡Yerkes National Primate Research Center, §Department of Pathology and Laboratory Medicine, and ∥Department of Neurology, Emory University , Atlanta, Georgia 30322, United States
| | - Nicholas T Seyfried
- Department of Biochemistry, ‡Yerkes National Primate Research Center, §Department of Pathology and Laboratory Medicine, and ∥Department of Neurology, Emory University , Atlanta, Georgia 30322, United States
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13
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Condello C, Stöehr J. Aβ propagation and strains: Implications for the phenotypic diversity in Alzheimer's disease. Neurobiol Dis 2017; 109:191-200. [PMID: 28359847 DOI: 10.1016/j.nbd.2017.03.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/09/2017] [Accepted: 03/26/2017] [Indexed: 12/13/2022] Open
Abstract
The progressive nature of Alzheimer's disease (AD) is thought to occur, at least in part, by the self-replication and spreading of Aβ and Tau aggregates through a prion mechanism. Evidence now exists that structural variants of Aβ prions can propagate their distinct conformations through template-directed folding of naïve Aβ peptides. This notion implicates that the first self-propagating Aβ assembly to emerge in the brain dictates the conformation, anatomical spread and pace of subsequently formed deposits. It is hypothesized that a prion mechanism defines the molecular basis underlying the diverse clinicopathologic phenotypes observed across the spectrum of AD patients. Thus, distinct AD strains might require further sub-classification based on biochemical and structural characterization of aggregated Aβ. Here, we review the evidence for distinct, self-propagating Aβ strains, and discuss potential cellular mechanisms that might contribute to their manifestation. From this perspective, we also explore the implications of Aβ strains for current FDA-approved medical imaging probes and therapies for amyloid. Ultimately, the discovery of new molecular tools to differentiate Aβ strains and dissect the heterogeneity of AD may lead to the development of more informative diagnostics and strain-specific therapeutics.
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Affiliation(s)
- Carlo Condello
- Institute for Neurodegenerative Diseases, Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, United States
| | - Jan Stöehr
- Institute for Neurodegenerative Diseases, Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, United States.
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14
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LeVine H, Spielmann HP, Matveev S, Cauvi FM, Murphy MP, Beckett TL, McCarty K, Lott IT, Doran E, Schmitt F, Head E. Down syndrome: age-dependence of PiB binding in postmortem frontal cortex across the lifespan. Neurobiol Aging 2017; 54:163-169. [PMID: 28385551 DOI: 10.1016/j.neurobiolaging.2017.03.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 01/19/2023]
Abstract
Beta-amyloid (Aβ) deposition in brain accumulates as a function of age in people with Down syndrome (DS) with subsequent development into Alzheimer disease neuropathology, typically by 40 years of age. In vivo imaging using the Pittsburgh compound B (PiB) ligand has facilitated studies linking Aβ, cognition, and dementia in DS. However, there are no studies of PiB binding across the lifespan in DS. The current study describes in vitro 3H-PiB binding in the frontal cortex of autopsy cases with DS compared to non-DS controls. Tissue from 64 cases included controls (n = 25) and DS (n = 39). In DS, 3H-PiB binding was significantly associated with age. After age 40 years in DS, 3H-PiB binding rose dramatically along with increasing individual variability. 3H-PiB binding correlated with the amount of Aβ42. Using fixed frontal tissue and fluorescent 6-CN-PiB, neuritic and cored plaques along with extensive cerebral amyloid angiopathy showed 6-CN-PiB binding. These results suggest that cortical PiB binding as shown by positron emission tomography imaging reflects plaques and cerebral amyloid angiopathy in DS brain.
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Affiliation(s)
- Harry LeVine
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - H Peter Spielmann
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA; Department of Chemistry, University of Kentucky, Lexington, KY, USA; Center for Structural Biology, University of Kentucky, Lexington, KY, USA; Markey Cancer Center, University of Kentucky, Lexington, KY, USA
| | - Sergey Matveev
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | | | - M Paul Murphy
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Tina L Beckett
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Katie McCarty
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Ira T Lott
- Department of Pediatrics, University of California at Irvine, Irvine, CA, USA
| | - Eric Doran
- Department of Pediatrics, University of California at Irvine, Irvine, CA, USA
| | - Frederick Schmitt
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Neurology, University of Kentucky, Lexington, KY, USA
| | - Elizabeth Head
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Pharmacology & Nutritional Sciences, University of Kentucky, Lexington, KY, USA.
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15
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Bäck M, Appelqvist H, LeVine H, Nilsson KPR. Anionic Oligothiophenes Compete for Binding of X-34 but not PIB to Recombinant Aβ Amyloid Fibrils and Alzheimer's Disease Brain-Derived Aβ. Chemistry 2016; 22:18335-18338. [PMID: 27767229 PMCID: PMC5215536 DOI: 10.1002/chem.201604583] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Indexed: 02/02/2023]
Abstract
Deposits comprised of amyloid‐β (Aβ) are one of the pathological hallmarks of Alzheimer's disease (AD) and small hydrophobic ligands targeting these aggregated species are used clinically for the diagnosis of AD. Herein, we observed that anionic oligothiophenes efficiently displaced X‐34, a Congo Red analogue, but not Pittsburgh compound B (PIB) from recombinant Aβ amyloid fibrils and Alzheimer's disease brain‐derived Aβ. Overall, we foresee that the oligothiophene scaffold offers the possibility to develop novel high‐affinity ligands for Aβ pathology only found in human AD brain, targeting a different site than PIB.
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Affiliation(s)
- Marcus Bäck
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
| | - Hanna Appelqvist
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
| | - Harry LeVine
- Department Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536-0230, USA
| | - K Peter R Nilsson
- Division of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, 581 83, Linköping, Sweden
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16
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Hamlett ED, Goetzl EJ, Ledreux A, Vasilevko V, Boger HA, LaRosa A, Clark D, Carroll SL, Carmona-Iragui M, Fortea J, Mufson EJ, Sabbagh M, Mohammed AH, Hartley D, Doran E, Lott IT, Granholm AC. Neuronal exosomes reveal Alzheimer's disease biomarkers in Down syndrome. Alzheimers Dement 2016; 13:541-549. [PMID: 27755974 DOI: 10.1016/j.jalz.2016.08.012] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 07/18/2016] [Accepted: 08/26/2016] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Individuals with Down syndrome (DS) exhibit Alzheimer's disease (AD) neuropathology and dementia early in life. Blood biomarkers of AD neuropathology would be valuable, as non-AD intellectual disabilities of DS and AD dementia overlap clinically. We hypothesized that elevations of amyloid β (Aβ) peptides and phosphorylated-tau in neuronal exosomes may document preclinical AD. METHODS AD neuropathogenic proteins Aβ1-42, P-T181-tau, and P-S396-tau were quantified by enzyme-linked immunosorbent assays in extracts of neuronal exosomes purified from blood of individuals with DS and age-matched controls. RESULTS Neuronal exosome levels of Aβ1-42, P-T181-tau, and P-S396-tau were significantly elevated in individuals with DS compared with age-matched controls at all ages beginning in childhood. No significant gender differences were observed. DISCUSSION These early increases in Aβ1-42, P-T181-tau, and P-S396-tau in individuals with DS may provide a basis for early intervention as targeted treatments become available.
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Affiliation(s)
- Eric D Hamlett
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA; The Knoebel Institute for Healthy Aging, University of Denver, Denver, CO, USA
| | - Edward J Goetzl
- Geriatric Research Center of the Jewish Home of San Francisco, San Francisco, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA
| | - Aurélie Ledreux
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA; The Knoebel Institute for Healthy Aging, University of Denver, Denver, CO, USA
| | - Vitaly Vasilevko
- University of California, Irvine Institute for Memory Impairment and Neurological Disorders, Irvine, CA, USA
| | - Heather A Boger
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA; The Center on Aging, Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Angela LaRosa
- Department of Pediatrics, Medical University of South Carolina, Charleston, SC, USA
| | - David Clark
- Department of Neurology, Medical University of South Carolina, Charleston, SC, USA
| | - Steven L Carroll
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - María Carmona-Iragui
- Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau-Biomedical Research Institute Sant Pau, Barcelona, Spain; Down Medical Center, Fundacío Catalana Síndrome de Down, Barcelona, Spain
| | - Juan Fortea
- Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau-Biomedical Research Institute Sant Pau, Barcelona, Spain; Down Medical Center, Fundacío Catalana Síndrome de Down, Barcelona, Spain
| | - Elliott J Mufson
- Barrow Neurological Institute, Department of Neurobiology, Phoenix, AZ, USA
| | - Marwan Sabbagh
- Barrow Neurological Institute, Department of Neurobiology, Phoenix, AZ, USA
| | - Abdul H Mohammed
- Department of Psychology, Linnaeus University, Växjo, Sweden; Center for Alzheimer Research, Karolinska Institutet, Huddinge, Sweden
| | | | - Eric Doran
- Department of Pediatrics, School of Medicine, University of California, Irvine, Orange, CA, USA
| | - Ira T Lott
- Department of Pediatrics, School of Medicine, University of California, Irvine, Orange, CA, USA
| | - Ann-Charlotte Granholm
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA; The Knoebel Institute for Healthy Aging, University of Denver, Denver, CO, USA; The Center on Aging, Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA; Center for Alzheimer Research, Karolinska Institutet, Huddinge, Sweden.
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17
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Ni R, Gillberg PG, Bogdanovic N, Viitanen M, Myllykangas L, Nennesmo I, Långström B, Nordberg A. Amyloid tracers binding sites in autosomal dominant and sporadic Alzheimer's disease. Alzheimers Dement 2016; 13:419-430. [PMID: 27693181 DOI: 10.1016/j.jalz.2016.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/26/2016] [Indexed: 12/29/2022]
Abstract
INTRODUCTION Amyloid imaging has been integrated into diagnostic criteria for Alzheimer's disease (AD). How amyloid tracers binding differ for different tracer structures and amyloid-β aggregates in autosomal dominant AD (ADAD) and sporadic AD is unclear. METHODS Binding properties of different amyloid tracers were examined in brain homogenates from six ADAD with APPswe, PS1 M146V, and PS1 EΔ9 mutations, 13 sporadic AD, and 14 control cases. RESULTS 3H-PIB, 3H-florbetaben, 3H-AZD2184, and BTA-1 shared a high- and a varying low-affinity binding site in the frontal cortex of sporadic AD. AZD2184 detected another binding site (affinity 33 nM) in the frontal cortex of ADAD. The 3H-AZD2184 and 3H-PIB binding were significantly higher in the striatum of ADAD compared to sporadic AD and control. Polyphenol resveratrol showed strongest inhibition on 3H-AZD84 binding followed by 3H-florbetaben and minimal on 3H-PIB. DISCUSSION This study implies amyloid tracers of different structures detect different sites on amyloid-β fibrils or conformations.
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Affiliation(s)
- Ruiqing Ni
- Division of Translational Alzheimer Neurobiology, Department of Neurobiology Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
| | - Per-Göran Gillberg
- Division of Translational Alzheimer Neurobiology, Department of Neurobiology Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden
| | - Nenad Bogdanovic
- Division of Clinical Geriatrics, Department of Neurobiology Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden; Department of Geriatric Medicine, University of Oslo, Oslo, Norway
| | - Matti Viitanen
- Division of Clinical Geriatrics, Department of Neurobiology Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden; Department of Geriatric Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | | | - Inger Nennesmo
- Division of Pathology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Bengt Långström
- Department of Chemistry, Uppsala University, Uppsala, Sweden
| | - Agneta Nordberg
- Division of Translational Alzheimer Neurobiology, Department of Neurobiology Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden; Department of Geriatric Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden.
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18
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LeVine H, Walker LC. What amyloid ligands can tell us about molecular polymorphism and disease. Neurobiol Aging 2016; 42:205-12. [PMID: 27143437 DOI: 10.1016/j.neurobiolaging.2016.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/15/2016] [Accepted: 03/16/2016] [Indexed: 12/19/2022]
Abstract
Brain-penetrant positron emission tomography imaging ligands selective for amyloid pathology in living subjects have sparked a revolution in presymptomatic biomarkers for Alzheimer's disease progression. As additional chemical structures were investigated, the heterogeneity of ligand-binding sites became apparent, as did discrepancies in binding of some ligands between human disease and animal models. These differences and their implications have received little attention. This review discusses the impact of different ligand-binding sites and misfolded protein conformational polymorphism on the interpretation of imaging data acquired with different ligands. Investigation of the differences in binding in animal models may identify pathologic processes informing improvements to these models for more faithful recapitulation of this uniquely human disease. The differential selectivity for binding of particular ligands to different conformational states could potentially be harnessed to better define disease progression and improve the prediction of clinical outcomes.
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Affiliation(s)
- Harry LeVine
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA; Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA; Department of Molecular and Cellular Biochemistry, Center for Structural Biology, University of Kentucky, Lexington, KY, USA.
| | - Lary C Walker
- Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA; Department of Neurology, Emory University, Atlanta, GA, USA
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19
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Fosso MY, McCarty K, Head E, Garneau-Tsodikova S, LeVine H. Differential Effects of Structural Modifications on the Competition of Chalcones for the PIB Amyloid Imaging Ligand-Binding Site in Alzheimer's Disease Brain and Synthetic Aβ Fibrils. ACS Chem Neurosci 2016; 7:171-6. [PMID: 26682772 DOI: 10.1021/acschemneuro.5b00266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Alzheimer's disease (AD) is a complex brain disorder that still remains ill defined. In order to understand the significance of binding of different clinical in vivo imaging ligands to the polymorphic pathological features of AD brain, the molecular characteristics of the ligand interacting with its specific binding site need to be defined. Herein, we observed that tritiated Pittsburgh Compound B ((3)H-PIB) can be displaced from synthetic Aβ(1-40) and Aβ(1-42) fibrils and from the PIB binding complex purified from human AD brain (ADPBC) by molecules containing a chalcone structural scaffold. We evaluated how substitution on the chalcone scaffold alters its ability to displace (3)H-PIB from the synthetic fibrils and ADPBC. By comparing unsubstituted core chalcone scaffolds along with the effects of bromine and methyl substitution at various positions, we found that attaching a hydroxyl group on the ring adjacent to the carbonyl group (ring I) of the parent member of the chalcone family generally improved the binding affinity of chalcones toward ADPBC and synthetic fibrils F40 and F42. Furthermore, any substitution on ring I at the ortho-position of the carbonyl group greatly decreases the binding affinity of the chalcones, potentially as a result of steric hindrance. Together with the finding that neither our chalcones nor PIB interact with the Congo Red/X-34 binding site, these molecules provide new tools to selectively probe the PIB binding site that is found in human AD brain, but not in brains of AD pathology animal models. Our chalcone derivatives also provide important information on the effects of fibril polymorphism on ligand binding.
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Affiliation(s)
- Marina Y. Fosso
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
| | | | | | - Sylvie Garneau-Tsodikova
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536-0596, United States
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20
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Wiseman FK, Al-Janabi T, Hardy J, Karmiloff-Smith A, Nizetic D, Tybulewicz VLJ, Fisher EMC, Strydom A. A genetic cause of Alzheimer disease: mechanistic insights from Down syndrome. Nat Rev Neurosci 2015; 16:564-74. [PMID: 26243569 PMCID: PMC4678594 DOI: 10.1038/nrn3983] [Citation(s) in RCA: 337] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Down syndrome, which arises in individuals carrying an extra copy of chromosome 21, is associated with a greatly increased risk of early-onset Alzheimer disease. It is thought that this risk is conferred by the presence of three copies of the gene encoding amyloid precursor protein (APP)--an Alzheimer disease risk factor--although the possession of extra copies of other chromosome 21 genes may also play a part. Further study of the mechanisms underlying the development of Alzheimer disease in people with Down syndrome could provide insights into the mechanisms that cause dementia in the general population.
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Affiliation(s)
- Frances K Wiseman
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Tamara Al-Janabi
- Division of Psychiatry, University College London, Maple House, 149 Tottenham Court Road, London W1T 7NF, UK
| | - John Hardy
- Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Annette Karmiloff-Smith
- Centre for Brain and Cognitive Development, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Dean Nizetic
- Lee Kong Chian School of Medicine, Nanyang Technological University, Novena Campus, 11 Mandalay Road, Singapore 308232; and the Blizard Institute, Barts and the London School of Medicine, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | | | - Elizabeth M C Fisher
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - André Strydom
- Division of Psychiatry, University College London, Maple House, 149 Tottenham Court Road, London W1T 7NF, UK
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