Analysis of anticoagulants for blood-based quantitation of amyloid β oligomers in the sFIDA assay

The amyloid-β (Aβ) peptides are associated with two prominent diseases in the brain, Alzheimer’s disease (AD) and cerebral amyloid angiopathy (CAA). Aβ42 is the dominant component of cored parenchymal plaques associated with AD, while Aβ40 is the predominant component of vascular amyloid associated with CAA. There are familial CAA mutations at positions Glu22 and Asp23 that lead to aggressive Aβ aggregation, drive vascular amyloid deposition and result in degradation of vascular membranes. In this study, we compared the transition of the monomeric Aβ40-WT peptide into soluble oligomers and fibrils with the corresponding transitions of the Aβ40-Dutch (E22Q), Aβ40-Iowa (D23N) and Aβ40-Dutch, Iowa (E22Q, D23N) mutants. FTIR measurements show that in a fashion similar to Aβ40-WT, the familial CAA mutants form transient intermediates with anti-parallel β-structure. This structure appears before the formation of cross-β-sheet fibrils as determined by thioflavin T fluorescence and circular dichroism spectroscopy and occurs when AFM images reveal the presence of soluble oligomers and protofibrils. Although the anti-parallel β-hairpin is a common intermediate on the pathway to Aβ fibrils for the four peptides studied, the rate of conversion to cross-β-sheet fibril structure differs for each.

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6-gingerol interferes with amyloid-beta (Aβ) peptide aggregation

10.1101/2021.01.03.425159 ◽

2021 ◽

Author(s):

Elina Berntsson ◽

Suman Paul ◽

Sabrina B. Sholts ◽

Jüri Jarvet ◽

Andreas Barth ◽

...

Keyword(s):

Animal Studies ◽

Amyloid Fibrils ◽

Amyloid Β ◽

Nutritional Supplement ◽

Aβ Oligomers ◽

Microscopy Imaging ◽

Positive Effects ◽

Age Related ◽

Soluble Aβ Oligomers

AbstractAlzheimer’s disease (AD) is the most prevalent age-related cause of dementia. AD affects millions of people worldwide, and to date there is no cure. The pathological hallmark of AD brains is deposition of amyloid plaques, which mainly consist of amyloid-β (Aβ) peptides, commonly 40 or 42 residues long, that have aggregated into amyloid fibrils. Intermediate aggregates in the form of soluble Aβ oligomers appear to be highly neurotoxic. Cell and animal studies have previously demonstrated positive effects of the molecule 6-gingerol on AD pathology. Gingerols are the main active constituents of the ginger root, which in many cultures is a traditional nutritional supplement for memory enhancement. Here, we use biophysical experiments to characterize in vitro interactions between 6-gingerol and Aβ40 peptides. Our experiments with atomic force microscopy imaging, and nuclear magnetic resonance and Thioflavin-T fluorescence spectroscopy, show that the hydrophobic 6-gingerol molecule interferes with formation of Aβ40 aggregates, but does not interact with Aβ40 monomers. Thus, together with its favourable toxicity profile, 6-gingerol appears to display many of the desired properties of an anti-AD compound.

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Amphiphilic Distyrylbenzene Derivatives as Potential Therapeutic and Imaging Agents for the Soluble Amyloid-β Oligomers in Alzheimer’s Disease

10.26434/chemrxiv.13605998.v1 ◽

2021 ◽

Author(s):

Liang Sun ◽

Hong-Jun Cho ◽

Soumyo Sen ◽

Andres S. Arango ◽

Truc T. Huynh ◽

...

Keyword(s):

Binding Affinity ◽

Electrostatic Interactions ◽

Amyloid Fibril ◽

Amyloid Β ◽

Amyloid Plaques ◽

Aβ Peptide ◽

Aβ Oligomers ◽

5Xfad Mice ◽

Soluble Aβ Oligomers

Alzheimer’s Diseases (AD) is the most common neurodegenerative disease, but efficient therapeutic and early diagnosis agents for this neurological disorder are still lacking. <a>Herein, we report the development of a novel amphiphilic compound, LS-4, generated linking a hydrophobic amyloid fibril-binding fragment with a hydrophilic azamacrocycle that can dramatically increase the binding affinity towards various amyloid β (Aβ) peptide aggregates. The developed compound exhibits uncommon fluorescence turn-on and high binding affinity for Aβ aggregates, especially for soluble Aβ oligomers. Moreover, upon the administration of LS-4 to 5xFAD mice, fluorescence imaging of the LS-4-treated brain sections reveals that LS-4 can readily penetrate the blood-brain-barrier (BBB) and bind to the Aβ oligomers in vivo, as confirmed by immunostaining with an Aβ oligomer-specific antibody. In addition, the treatment of 5xFAD mice with LS-4 significantly reduces the amount of both amyloid plaques and associated phosphorylated tau (p-tau) aggregates vs. the vehicle-treated 5xFAD mice, while microglia activation is also reduced. Furthermore, molecular dynamics simulations corroborate the observation that introducing a hydrophilic moiety into the molecular structure can significantly enhance the electrostatic interactions with the polar residues of the Aβ peptide species. Finally, taking advantage of the strong Cu-chelating property of the azamacrocycle, we performed a series of radioimaging and biodistribution studies that show the 64Cu-LS-4 complex binds to the amyloid plaques and can accumulate a significantly larger extent in the 5xFAD mice brains vs. the WT controls. Overall, these in vitro and in vivo studies illustrate that the novel strategy to employ an amphiphilic molecule containing a hydrophilic fragment attached to a hydrophobic amyloid fibril-binding fragment </a><a>can increase the binding affinity of these compounds for the soluble Aβ oligomers and can thus be used </a>to detect and regulate the soluble Aβ species in AD.

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Fluorescent indolizine derivative YI-13 detects amyloid-β monomers, dimers, and plaques in the brain of 5XFAD Alzheimer transgenic mouse model

PLoS ONE ◽

10.1371/journal.pone.0243041 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0243041

Author(s):

DaWon Kim ◽

Jeong Hwa Lee ◽

Hye Yun Kim ◽

Jisu Shin ◽

Kyeonghwan Kim ◽

...

Keyword(s):

Mouse Model ◽

Transgenic Mouse ◽

Neurodegenerative Disorder ◽

Amyloid Β ◽

Transgenic Mouse Model ◽

Aβ Oligomers ◽

Aβ Peptides ◽

Soluble Aβ Oligomers ◽

The Brain

Alzheimer disease (AD) is a neurodegenerative disorder characterized by the aberrant production and accumulation of amyloid-β (Aβ) peptides in the brain. Accumulated Aβ in soluble oligomer and insoluble plaque forms are considered to be a pathological culprit and biomarker of the disorder. Here, we report a fluorescent universal Aβ-indicator YI-13, 5-(4-fluorobenzoyl)-7,8-dihydropyrrolo[1,2-b]isoquinolin-9(6H)-one, which detects Aβ monomers, dimers, and plaques. We synthesized a library of 26 fluorescence chemicals with the indolizine core and screen them through a series of in vitro tests utilizing Aβ as a target and YI-13 was selected as the final imaging candidate. YI-13 was found to stain and visualize insoluble Aβ plaques in the brain tissue, of a transgenic mouse model with five familial AD mutations (5XFAD), by a histochemical approach and to label soluble Aβ oligomers within brain lysates of the mouse model under a fluorescence plate reader. Among oligomers aggregated from monomers and synthetic dimers from chemically conjugated monomers, YI-13 preferred the dimeric Aβ.

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Sialylated glycosylphosphatidylinositols suppress the production of toxic amyloid-β oligomers

Biochemical Journal ◽

10.1042/bcj20170239 ◽

2017 ◽

Vol 474 (17) ◽

pp. 3045-3058 ◽

Cited By ~ 2

Author(s):

William Nolan ◽

Harriet McHale-Owen ◽

Clive Bate

Keyword(s):

Cell Model ◽

Amyloid Β ◽

Critical Factor ◽

Cellular Prion Protein ◽

Progressive Dementia ◽

Aβ Oligomers ◽

Key Factor ◽

A Cell ◽

Synapse Degeneration ◽

Soluble Aβ Oligomers

The production of amyloid-β (Aβ) is a key factor driving pathogenesis in Alzheimer's disease (AD). Increasing concentrations of soluble Aβ oligomers within the brain lead to synapse degeneration and the progressive dementia characteristic of AD. Since Aβ exists in both disease-relevant (toxic) and non-toxic forms, the factors that affected the release of toxic Aβ were studied in a cell model. 7PA2 cells expressing the human amyloid precursor protein released Aβ oligomers that caused synapse damage when incubated with cultured neurones. These Aβ oligomers had similar potency to soluble Aβ oligomers derived from the brains of Alzheimer's patients. Although the conditioned media from 7PA2 cells treated with the cellular prion protein (PrPC) contained Aβ, it did not cause synapse damage. The loss of toxicity was associated with a reduction in Aβ oligomers and an increase in Aβ monomers. The suppression of toxic Aβ release was dependent on the glycosylphosphatidylinositol (GPI) anchor attached to PrPC, and treatment of cells with specific GPIs alone reduced the production of toxic Aβ. The efficacy of GPIs was structure-dependent and the presence of sialic acid was critical. The conditioned medium from GPI-treated cells protected neurones against Aβ oligomer-induced synapse damage; neuroprotection was mediated by Aβ monomers. These studies support the hypothesis that the ratio of Aβ monomers to Aβ oligomers is a critical factor that regulates synapse damage.

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Cu and Zn interactions with Aβ peptides: consequence of coordination on aggregation and formation of neurotoxic soluble Aβ oligomers

Metallomics ◽

10.1039/c8mt00203g ◽

2019 ◽

Vol 11 (1) ◽

pp. 64-84 ◽

Cited By ~ 23

Author(s):

Monika Rana ◽

Anuj Kumar Sharma

Keyword(s):

Alzheimer’S Disease ◽

Coordination Chemistry ◽

Transition Metal ◽

Metal Ions ◽

Amyloid Β ◽

Transition Metal Ions ◽

Aβ Oligomers ◽

Aβ Peptides ◽

Soluble Aβ Oligomers ◽

Cu And Zn

The coordination chemistry of transition metal ions (Fe, Cu, Zn) with the amyloid-β (Aβ) peptides has attracted a lot of attention in recent years due to its repercussions in Alzheimer's disease (AD).

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Au23(CR)14 nanocluster restores fibril Aβ’s unfolded state with abolished cytotoxicity and dissolves endogenous Aβ plaques

National Science Review ◽

10.1093/nsr/nwz215 ◽

2019 ◽

Vol 7 (4) ◽

pp. 763-774 ◽

Cited By ~ 1

Author(s):

Wenkang Zhang ◽

Guanbin Gao ◽

Zhongjie Ma ◽

Zhuoying Luo ◽

Meng He ◽

...

Keyword(s):

Brain Slices ◽

Amyloid Β ◽

Aβ Oligomers ◽

Aβ Peptides ◽

Unfolded State ◽

Good Biocompatibility ◽

Aβ Fibrils ◽

Soluble Aβ Oligomers ◽

Β Sheet

Abstract The misfolding of amyloid-β (Aβ) peptides from the natural unfolded state to β-sheet structure is a critical step, leading to abnormal fibrillation and formation of endogenous Aβ plaques in Alzheimer's disease (AD). Previous studies have reported inhibition of Aβ fibrillation or disassembly of exogenous Aβ fibrils in vitro. However, soluble Aβ oligomers have been reported with increased cytotoxicity; this might partly explain why current clinical trials targeting disassembly of Aβ fibrils by anti-Aβ antibodies have failed so far. Here we show that Au23(CR)14 (a new Au nanocluster modified by Cys-Arg (CR) dipeptide) is able to completely dissolve exogenous mature Aβ fibrils into monomers and restore the natural unfolded state of Aβ peptides from misfolded β-sheets. Furthermore, the cytotoxicity of Aβ40 fibrils when dissolved by Au23(CR)14 is fully abolished. More importantly, Au23(CR)14 is able to completely dissolve endogenous Aβ plaques in brain slices from transgenic AD model mice. In addition, Au23(CR)14 has good biocompatibility and infiltration ability across the blood–brain barrier. Taken together, this work presents a promising therapeutics candidate for AD treatment, and manifests the potential of nanotechnological approaches in the development of nanomedicines.

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Amphiphilic Distyrylbenzene Derivatives as Potential Therapeutic and Imaging Agents for the Soluble Amyloid-β Oligomers in Alzheimer’s Disease

10.26434/chemrxiv.13605998 ◽

2021 ◽

Author(s):

Liang Sun ◽

Hong-Jun Cho ◽

Soumyo Sen ◽

Andres S. Arango ◽

Truc T. Huynh ◽

...

Keyword(s):

Binding Affinity ◽

Electrostatic Interactions ◽

Amyloid Fibril ◽

Amyloid Β ◽

Amyloid Plaques ◽

Aβ Peptide ◽

Aβ Oligomers ◽

5Xfad Mice ◽

Soluble Aβ Oligomers

Alzheimer’s Diseases (AD) is the most common neurodegenerative disease, but efficient therapeutic and early diagnosis agents for this neurological disorder are still lacking. <a>Herein, we report the development of a novel amphiphilic compound, LS-4, generated linking a hydrophobic amyloid fibril-binding fragment with a hydrophilic azamacrocycle that can dramatically increase the binding affinity towards various amyloid β (Aβ) peptide aggregates. The developed compound exhibits uncommon fluorescence turn-on and high binding affinity for Aβ aggregates, especially for soluble Aβ oligomers. Moreover, upon the administration of LS-4 to 5xFAD mice, fluorescence imaging of the LS-4-treated brain sections reveals that LS-4 can readily penetrate the blood-brain-barrier (BBB) and bind to the Aβ oligomers in vivo, as confirmed by immunostaining with an Aβ oligomer-specific antibody. In addition, the treatment of 5xFAD mice with LS-4 significantly reduces the amount of both amyloid plaques and associated phosphorylated tau (p-tau) aggregates vs. the vehicle-treated 5xFAD mice, while microglia activation is also reduced. Furthermore, molecular dynamics simulations corroborate the observation that introducing a hydrophilic moiety into the molecular structure can significantly enhance the electrostatic interactions with the polar residues of the Aβ peptide species. Finally, taking advantage of the strong Cu-chelating property of the azamacrocycle, we performed a series of radioimaging and biodistribution studies that show the 64Cu-LS-4 complex binds to the amyloid plaques and can accumulate a significantly larger extent in the 5xFAD mice brains vs. the WT controls. Overall, these in vitro and in vivo studies illustrate that the novel strategy to employ an amphiphilic molecule containing a hydrophilic fragment attached to a hydrophobic amyloid fibril-binding fragment </a><a>can increase the binding affinity of these compounds for the soluble Aβ oligomers and can thus be used </a>to detect and regulate the soluble Aβ species in AD.

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Is it All Said for NSAIDs in Alzheimer’s Disease? Role of Mitochondrial Calcium Uptake

Current Alzheimer Research ◽

10.2174/1567205015666171227154016 ◽

2018 ◽

Vol 15 (6) ◽

pp. 504-510 ◽

Cited By ~ 9

Author(s):

Sara Sanz-Blasco ◽

Maria Calvo-Rodríguez ◽

Erica Caballero ◽

Monica Garcia-Durillo ◽

Lucia Nunez ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cell Death ◽

Amyloid Β ◽

Epidemiological Data ◽

Amyloid Β Peptide ◽

Aβ Oligomers ◽

Mitochondrial Potential ◽

Disease Modifying Drugs ◽

Definitive Evidence

Objectives: Epidemiological data suggest that non-steroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer's disease (AD). Unfortunately, recent trials have failed in providing compelling evidence of neuroprotection. Discussion as to why NSAIDs effectivity is uncertain is ongoing. Possible explanations include the view that NSAIDs and other possible disease-modifying drugs should be provided before the patients develop symptoms of AD or cognitive decline. In addition, NSAID targets for neuroprotection are unclear. Both COX-dependent and independent mechanisms have been proposed, including γ-secretase that cleaves the amyloid precursor protein (APP) and yields amyloid β peptide (Aβ). Methods: We have proposed a neuroprotection mechanism for NSAIDs based on inhibition of mitochondrial Ca2+ overload. Aβ oligomers promote Ca2+ influx and mitochondrial Ca2+ overload leading to neuron cell death. Several non-specific NSAIDs including ibuprofen, sulindac, indomethacin and Rflurbiprofen depolarize mitochondria in the low µM range and prevent mitochondrial Ca2+ overload induced by Aβ oligomers and/or N-methyl-D-aspartate (NMDA). However, at larger concentrations, NSAIDs may collapse mitochondrial potential (ΔΨ) leading to cell death. Results: Accordingly, this mechanism may explain neuroprotection at low concentrations and damage at larger doses, thus providing clues on the failure of promising trials. Perhaps lower NSAID concentrations and/or alternative compounds with larger dynamic ranges should be considered for future trials to provide definitive evidence of neuroprotection against AD.

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Detectability of Plasma Proteins in SRM Measurements

Current Proteomics ◽

10.2174/1570164615666180718151135 ◽

2018 ◽

Vol 16 (1) ◽

pp. 74-81 ◽

Cited By ~ 1

Author(s):

Olga I. Kiseleva ◽

Elena A. Ponomarenko ◽

Yulia A. Romashova ◽

Ekaterina V. Poverennaya ◽

Andrey V. Lisitsa

Keyword(s):

Blood Plasma ◽

Human Plasma ◽

Limit Of Detection ◽

Human Blood Plasma ◽

Analytical Sensitivity ◽

Plasma Proteome ◽

Protein Targets ◽

Blood Plasma Sample ◽

Specificity And Sensitivity ◽

Human Plasma Proteome

Background: Liquid chromatography coupled with targeted mass spectrometry underwent rapid technical evolution during last years and has become widely used technology in clinical laboratories. It offers confident specificity and sensitivity superior to those of traditional immunoassays. However, due to controversial reports on reproducibility of SRM measurements, the prospects of clinical appliance of the method are worth discussing. Objective: The study was aimed at assessment of capabilities of SRM to achieve a thorough assembly of the human plasma proteome. Method: We examined set of 19 human blood plasma samples to measure 100 proteins, including FDA-approved biomarkers, via SRM-assay. Results: Out of 100 target proteins 43 proteins were confidently detected in at least two blood plasma sample runs, 36 and 21 proteins were either not detected in any run or inconsistently detected, respectively. Empiric dependences on protein detectability were derived to predict the number of biological samples required to detect with certainty a diagnostically relevant quantum of the human plasma proteome. Conclusion: The number of samples exponentially increases with an increase in the number of protein targets, while proportionally decreasing to the logarithm of the limit of detection. Analytical sensitivity and enormous proteome heterogeneity are major bottlenecks of the human proteome exploration.

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