scholarly journals Significance of Oligomeric and Fibrillar Species in Amyloidosis: Insights into Pathophysiology and Treatment

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5091
Author(s):  
Haruki Koike ◽  
Yohei Iguchi ◽  
Kentaro Sahashi ◽  
Masahisa Katsuno
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tissue Damage ◽  
Amyloid Fibrils ◽  
Human Monoclonal Antibody ◽  
Nerve Biopsy ◽  
Systemic Amyloidosis ◽  
Aβ Oligomers ◽  
Clinical Scales

Amyloidosis is a term referring to a group of various protein-misfolding diseases wherein normally soluble proteins form aggregates as insoluble amyloid fibrils. How, or whether, amyloid fibrils contribute to tissue damage in amyloidosis has been the topic of debate. In vitro studies have demonstrated the appearance of small globular oligomeric species during the incubation of amyloid beta peptide (Aβ). Nerve biopsy specimens from patients with systemic amyloidosis have suggested that globular structures similar to Aβ oligomers were generated from amorphous electron-dense materials and later developed into mature amyloid fibrils. Schwann cells adjacent to amyloid fibrils become atrophic and degenerative, suggesting that the direct tissue damage induced by amyloid fibrils plays an important role in systemic amyloidosis. In contrast, there is increasing evidence that oligomers, rather than amyloid fibrils, are responsible for cell death in neurodegenerative diseases, particularly Alzheimer’s disease. Disease-modifying therapies based on the pathophysiology of amyloidosis have now become available. Aducanumab, a human monoclonal antibody against the aggregated form of Aβ, was recently approved for Alzheimer’s disease, and other monoclonal antibodies, including gantenerumab, solanezumab, and lecanemab, could also be up for approval. As many other agents for amyloidosis will be developed in the future, studies to develop sensitive clinical scales for identifying improvement and markers that can act as surrogates for clinical scales should be conducted.

scholarly journals APP Osaka Mutation in Familial Alzheimer’s Disease—Its Discovery, Phenotypes, and Mechanism of Recessive Inheritance

2020 ◽  
Vol 21 (4) ◽  
pp. 1413 ◽  
Author(s):  
Takami Tomiyama ◽  
Hiroyuki Shimada
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Fibrils ◽  
Synaptic Function ◽  
Recessive Inheritance ◽  
Familial Alzheimer’S Disease ◽  
Aβ Oligomers ◽  
Unique Character ◽  
Familial Alzheimer's Disease

Alzheimer’s disease is believed to begin with synaptic dysfunction caused by soluble Aβ oligomers. When this oligomer hypothesis was proposed in 2002, there was no direct evidence that Aβ oligomers actually disrupt synaptic function to cause cognitive impairment in humans. In patient brains, both soluble and insoluble Aβ species always coexist, and therefore it is difficult to determine which pathologies are caused by Aβ oligomers and which are caused by amyloid fibrils. Thus, no validity of the oligomer hypothesis was available until the Osaka mutation was discovered. This mutation, which was found in a Japanese pedigree of familial Alzheimer’s disease, is the deletion of codon 693 of APP gene, resulting in mutant Aβ lacking the 22nd glutamate. Only homozygous carriers suffer from dementia. In vitro studies revealed that this mutation has a very unique character that accelerates Aβ oligomerization but does not form amyloid fibrils. Model mice expressing this mutation demonstrated that all pathologies of Alzheimer’s disease can be induced by Aβ oligomers alone. In this review, we describe the story behind the discovery of the Osaka mutation, summarize the mutant’s phenotypes, and propose a mechanism of its recessive inheritance.

scholarly journals The inhibition of cellular toxicity of amyloid-β by dissociated transthyretin

2020 ◽  
Vol 295 (41) ◽  
pp. 14015-14024 ◽  
Author(s):  
Qin Cao ◽  
Daniel H. Anderson ◽  
Wilson Y. Liang ◽  
Joshua Chou ◽  
Lorena Saelices
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protective Effect ◽  
Amyloid Β ◽  
Inhibitory Effect ◽  
Aβ Oligomers ◽  
Cellular Toxicity ◽  
Computational Docking

The protective effect of transthyretin (TTR) on cellular toxicity of β-amyloid (Aβ) has been previously reported. TTR is a tetrameric carrier of thyroxine in blood and cerebrospinal fluid, the pathogenic aggregation of which causes systemic amyloidosis. However, studies have documented a protective effect of TTR against cellular toxicity of pathogenic Aβ, a protein associated with Alzheimer's disease. TTR binds Aβ, alters its aggregation, and inhibits its toxicity both in vitro and in vivo. In this study, we investigate whether the amyloidogenic ability of TTR and its antiamyloid inhibitory effect are associated. Using protein aggregation and cytotoxicity assays, we found that the dissociation of the TTR tetramer, required for its amyloid pathogenesis, is also necessary to prevent cellular toxicity from Aβ oligomers. These findings suggest that the Aβ-binding site of TTR may be hidden in its tetrameric form. Aided by computational docking and peptide screening, we identified a TTR segment that is capable of altering Aβ aggregation and toxicity, mimicking TTR cellular protection. EM, immune detection analysis, and assessment of aggregation and cytotoxicity revealed that the TTR segment inhibits Aβ oligomer formation and also promotes the formation of nontoxic, nonamyloid amorphous aggregates, which are more sensitive to protease digestion. Finally, this segment also inhibits seeding of Aβ catalyzed by Aβ fibrils extracted from the brain of an Alzheimer's patient. Together, these findings suggest that mimicking the inhibitory effect of TTR with peptide-based therapeutics represents an additional avenue to explore for the treatment of Alzheimer's disease.

Multi-site dynamic recording for Aβ oligomers-induced Alzheimer's disease in vitro based on neuronal network chip

2019 ◽  
Vol 133 ◽  
pp. 183-191 ◽  
Author(s):  
Fan Gao ◽  
Keqiang Gao ◽  
Chuanjiang He ◽  
Mengxue Liu ◽  
Hao Wan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neuronal Network ◽  
Aβ Oligomers

In vitro formation of amyloid fibrils from two synthetic peptides of different lengths homologous to alzheimer's disease β-protein

1986 ◽  
Vol 141 (2) ◽  
pp. 782-789 ◽  
Author(s):  
Eduardo M. Castaño ◽  
Jorge Ghiso ◽  
Frances Prelli ◽  
Peter D. Gorevic ◽  
Antonio Migheli ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synthetic Peptides ◽  
Amyloid Fibrils ◽  
Β Protein

scholarly journals CNI-1493 inhibits Aβ production, plaque formation, and cognitive deterioration in an animal model of Alzheimer's disease

2008 ◽  
Vol 205 (7) ◽  
pp. 1593-1599 ◽  
Author(s):  
Michael Bacher ◽  
Richard Dodel ◽  
Bayan Aljabari ◽  
Kathy Keyvani ◽  
Philippe Marambaud ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Memory Performance ◽  
Amyloid Β ◽  
Amyloid Plaque ◽  
Amyloid Β Protein ◽  
Aβ Oligomers ◽  
App Processing ◽  
Model Of Alzheimer’S Disease

Alzheimer's disease (AD) is characterized by neuronal atrophy caused by soluble amyloid β protein (Aβ) peptide “oligomers” and a microglial-mediated inflammatory response elicited by extensive amyloid deposition in the brain. We show that CNI-1493, a tetravalent guanylhydrazone with established antiinflammatory properties, interferes with Aβ assembly and protects neuronal cells from the toxic effect of soluble Aβ oligomers. Administration of CNI-1493 to TgCRND8 mice overexpressing human amyloid precursor protein (APP) for a treatment period of 8 wk significantly reduced Aβ deposition. CNI-1493 treatment resulted in 70% reduction of amyloid plaque area in the cortex and 87% reduction in the hippocampus of these animals. Administration of CNI-1493 significantly improved memory performance in a cognition task compared with vehicle-treated mice. In vitro analysis of CNI-1493 on APP processing in an APP-overexpressing cell line revealed a significant dose-dependent decrease of total Aβ accumulation. This study indicates that the antiinflammatory agent CNI-1493 can ameliorate the pathophysiology and cognitive defects in a murine model of AD.

scholarly journals Trichostatin A ameliorates Alzheimer’s disease-related pathology and cognitive deficits by increasing albumin expression and Aβ clearance in APP/PS1 mice

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Qiang Su ◽  
Tian Li ◽  
Pei-Feng He ◽  
Xue-Chun Lu ◽  
Qi Yu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Western Blotting ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Trichostatin A ◽  
Amyloid Β ◽  
Aβ Oligomers ◽  
Aβ Clearance

Abstract Background Alzheimer’s disease (AD) is an intractable neurodegenerative disorder in the elderly population, currently lacking a cure. Trichostatin A (TSA), a histone deacetylase inhibitor, showed some neuroprotective roles, but its pathology-improvement effects in AD are still uncertain, and the underlying mechanisms remain to be elucidated. The present study aims to examine the anti-AD effects of TSA, particularly investigating its underlying cellular and molecular mechanisms. Methods Novel object recognition and Morris water maze tests were used to evaluate the memory-ameliorating effects of TSA in APP/PS1 transgenic mice. Immunofluorescence, Western blotting, Simoa assay, and transmission electron microscopy were utilized to examine the pathology-improvement effects of TSA. Microglial activity was assessed by Western blotting and transwell migration assay. Protein-protein interactions were analyzed by co-immunoprecipitation and LC-MS/MS. Results TSA treatment not only reduced amyloid β (Aβ) plaques and soluble Aβ oligomers in the brain, but also effectively improved learning and memory behaviors of APP/PS1 mice. In vitro study suggested that the improvement of Aβ pathology by TSA was attributed to the enhancement of Aβ clearance, mainly by the phagocytosis of microglia, and the endocytosis and transport of microvascular endothelial cells. Notably, a meaningful discovery in the study was that TSA dramatically upregulated the expression level of albumin in cell culture, by which TSA inhibited Aβ aggregation and promoted the phagocytosis of Aβ oligomers. Conclusions These findings provide a new insight into the pathogenesis of AD and suggest TSA as a novel promising candidate for the AD treatment.

scholarly journals Conjugates of neuroprotective chaperone L-PGDS provide MRI contrast for detection of amyloid β-rich regions in live Alzheimer’s Disease mouse model brain

2020 ◽  
Author(s):  
Bhargy Sharma ◽  
Joanes Grandjean ◽  
Margaret Phillips ◽  
Ambrish Kumar ◽  
Francesca Mandino ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Mouse Brain ◽  
Amyloid Fibrils ◽  
Amyloid Β ◽  
Brain Regions ◽  
Mri Contrast ◽  
Neuroprotective Function

AbstractEndogenous brain proteins can recognize the toxic oligomers of amyloid-β (Aβ) peptides implicated in Alzheimer’s disease (AD) and interact with them to prevent their aggregation. Lipocalin-type Prostaglandin D Synthase (L-PGDS) is a major Aβ-chaperone protein in the human cerebrospinal fluid. Here we demonstrate that L-PGDS detects amyloids in diseased mouse brain. Conjugation of L-PGDS with magnetic nanoparticles enhanced the contrast for magnetic resonance imaging. We conjugated the L-PGDS protein with ferritin nanocages to detect amyloids in the AD mouse model brain. We show here that the conjugates administered through intraventricular injections co-localize with amyloids in the mouse brain. These conjugates can target the brain regions through non-invasive intranasal administration, as shown in healthy mice. These conjugates can inhibit the aggregation of amyloids in vitro and show potential neuroprotective function by breaking down the mature amyloid fibrils.

Abstract 282: Chemically Tailoring Cardiovascular Drugs for Alzheimer's Disease Drug Discovery

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Giulio Pasinetti ◽  
Lap Ho ◽  
Kenjiro Ono ◽  
Jun Wang
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cardiovascular Complications ◽  
Clinical Applications ◽  
Aβ Oligomers ◽  
Clinical Safety ◽  
Lead Compounds ◽  
Aβ Oligomerization

We previously reported that carvedilol, a brain bioavailable and bioactive antihypertensive agent, significantly reduces brain contents of Alzheimer’s disease (AD)-type β-amyloid (Aβ) oligomers experimentally. Currently, we are exploring clinical applications of carvedilol to prevent or attenuate the progression of AD dementia. However, the potential development of carvedilol for AD is complicated by its cardiovascular activities, including bradycardia and hypotension, particularly among patients already undergoing treatment with other cardiovascular medications. Based on this, using structure-activity relationship (SAR) medicinal chemistry we are developing novel modified carvedilol lead compounds with decreased cardiovascular features for treating AD. Testing commercially available compounds identified from a preliminary screening of a library of carvedilol analogs, we identified 6 bioactive small-molecule compounds that significantly reduce Aβ oligomerization in vitro. Anti-Aβ oligomerization activity was confirmed by circular diachroism and electron microscopy. One compound, (R)-(+)-4-hydroxyphenyl carvedilol, showed improved anti-oligomerization activity and reduced α-1 adrenergic receptor binding activity compared to carvedilol. Short-term proof-of-concept in vivo testing showed that treatment with 1.5 mg/kg/day (R)-(+)-4-hydroxyphenyl carvedilol significantly reduced levels of oligomeric Aβ and total Aβ in the brains of a transgenic mouse model of AD-type Aβ neuropathology without cardiovascular complications. We are currently evaluating the effects of (R)-(+)-4-hydroxyphenyl carvedilol on cardiovascular functions and the attenuation of Aβ-mediated cognitive dysfunction in experimental AD models. Our study provides the critical basis for exploring the bioavailability and pharmacokinetic characteristics of novel cardiovascular lead compounds with enhanced brain activities and reduced adverse events in IND-directed pre-clinical safety assessments and eventually Phase I clinical applications in AD.

scholarly journals Impaired adult neurogenesis is an early event in Alzheimer’s disease neurodegeneration, mediated by intracellular Aβ oligomers

2019 ◽  
Vol 27 (3) ◽  
pp. 934-948 ◽  
Author(s):  
Chiara Scopa ◽  
Francesco Marrocco ◽  
Valentina Latina ◽  
Federica Ruggeri ◽  
Valerio Corvaglia ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Adult Neurogenesis ◽  
Point Of View ◽  
Early Event ◽  
Aβ Oligomers ◽  
Promising Therapeutic Target ◽  
Presymptomatic Stage

Abstract Alterations of adult neurogenesis have been reported in several Alzheimer's disease (AD) animal models and human brains, while defects in this process at presymptomatic/early stages of AD have not been explored yet. To address this, we investigated potential neurogenesis defects in Tg2576 transgenic mice at 1.5 months of age, a prodromal asymptomatic age in terms of Aβ accumulation and neurodegeneration. We observe that Tg2576 resident and SVZ-derived adult neural stem cells (aNSCs) proliferate significantly less. Further, they fail to terminally differentiate into mature neurons due to pathological, tau-mediated, and microtubule hyperstabilization. Olfactory bulb neurogenesis is also strongly reduced, confirming the neurogenic defect in vivo. We find that this phenotype depends on the formation and accumulation of intracellular A-beta oligomers (AβOs) in aNSCs. Indeed, impaired neurogenesis of Tg2576 progenitors is remarkably rescued both in vitro and in vivo by the expression of a conformation-specific anti-AβOs intrabody (scFvA13-KDEL), which selectively interferes with the intracellular generation of AβOs in the endoplasmic reticulum (ER). Altogether, our results demonstrate that SVZ neurogenesis is impaired already at a presymptomatic stage of AD and is caused by endogenously generated intracellular AβOs in the ER of aNSCs. From a translational point of view, impaired SVZ neurogenesis may represent a novel biomarker for AD early diagnosis, in association to other biomarkers. Further, this study validates intracellular Aβ oligomers as a promising therapeutic target and prospects anti-AβOs scFvA13-KDEL intrabody as an effective tool for AD treatment.

scholarly journals Rational design of a conformation-specific antibody for the quantification of Aβ oligomers

2020 ◽  
Vol 117 (24) ◽  
pp. 13509-13518 ◽  
Author(s):  
Francesco A. Aprile ◽  
Pietro Sormanni ◽  
Marina Podpolny ◽  
Shianne Chhangur ◽  
Lisa-Maria Needham ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Misfolding ◽  
Rational Design ◽  
Design Method ◽  
Amyloid Β ◽  
In Vitro Assays ◽  
Aβ Oligomers ◽  
Detection And Quantification

Protein misfolding and aggregation is the hallmark of numerous human disorders, including Alzheimer’s disease. This process involves the formation of transient and heterogeneous soluble oligomers, some of which are highly cytotoxic. A major challenge for the development of effective diagnostic and therapeutic tools is thus the detection and quantification of these elusive oligomers. Here, to address this problem, we develop a two-step rational design method for the discovery of oligomer-specific antibodies. The first step consists of an “antigen scanning” phase in which an initial panel of antibodies is designed to bind different epitopes covering the entire sequence of a target protein. This procedure enables the determination through in vitro assays of the regions exposed in the oligomers but not in the fibrillar deposits. The second step involves an “epitope mining” phase, in which a second panel of antibodies is designed to specifically target the regions identified during the scanning step. We illustrate this method in the case of the amyloid β (Aβ) peptide, whose oligomers are associated with Alzheimer’s disease. Our results show that this approach enables the accurate detection and quantification of Aβ oligomers in vitro, and inCaenorhabditis elegansand mouse hippocampal tissues.

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