Amyloid Against Amyloid: Dimeric Amyloid Fragment Ameliorates Cognitive Impairments by Direct Clearance of Oligomers and Plaques.

Amyloid-ß (Aß) in the form of neurotoxic aggregates is regarded as the main pathological initiator and key therapeutic target of Alzheimer's disease. However, anti-Aß drug development has been impeded by the lack of a target needed for structure-based drug design and low permeability of the blood-brain barrier (BBB). An attractive therapeutic strategy is the development of amyloid-based anti-Aß peptidomimetics that exploit the self-assembling nature of Aß and penetrate the BBB. Herein, we designed a dimeric peptide drug candidate based on the N-terminal fragment of Aß, DAB, found to cross the BBB and solubilize Aß oligomers and fibrils. Administration of DAB reduced amyloid burden in 5XFAD mice, and downregulated neuroinflammation and prevented memory impairment in the Y-maze test. Peptide mapping assays and molecular docking studies were utilized to elucidate DAB-Aß interaction. To further understand the active regions of DAB, we assessed the dissociative activity of DAB with sequence modifications.

Rhizolutin, a Novel 7/10/6-Tricyclic Dilactone, Dissociates Misfolded Protein Aggregates and Reduces Apoptosis/Inflammation Associated with Alzheimer's Disease.

Rhizolutin (1) was discovered as a natural product of ginseng-rhizospheric Streptomyces sp. WON17. Its structure features an unprecedented 7/10/6-tricyclic dilactone carbon skeleton composed of dimethylcyclodecatriene flanked by a 7-membered and a 6-membered lactone ring based on spectroscopic analysis. During an unbiased screening of natural product libraries, this novel compound was found to dissociate amyloid-ß (Aß) plaques and tau tangles, which are key pathological hallmarks of Alzheimer's disease (AD). Rhizolutin treatment of APP/PS1 double transgenic mice with AD significantly dissociated hippocampal plaques. In vitro, rhizolutin substantially decreased Aß-induced apoptosis and inflammation in neuronal and glial cells. Our findings introduce a unique chemical entity that targets Aß and tau concurrently by mimicking misfolded protein clearance mechanisms of immunotherapy, which is prominently investigated in clinical trials.

Discovery of Chemicals to Either Clear or Indicate Amyloid Aggregates by Targeting Memory-Impairing Anti-Parallel Aß Dimers.

Amyloid-ß (Aß) oligomers are implicated in Alzheimer disease (AD). However, their unstable nature and heterogeneous state disrupts elucidation of their explicit role in AD progression, impeding the development of tools targeting soluble Aß oligomers. Herein parallel and anti-parallel variants of Aß(1-40) dimers were designed and synthesized, and their pathogenic properties in AD models characterized. Anti-parallel dimers induced cognitive impairments with increased amyloidogenesis and cytotoxicity, and this dimer was then used in a screening platform. Through screening, two FDA-approved drugs, Oxytetracycline and Sunitinib, were identified to dissociate Aß oligomers and plaques to monomers in 5XFAD transgenic mice. In addition, fluorescent Astrophloxine was shown to detect aggregated Aß in brain tissue and cerebrospinal fluid samples of AD mice. This screening platform provides a stable and homogeneous environment for observing Aß interactions with dimer-specific molecules.

Early onset diagnosis in Alzheimer's disease patients via amyloid-ß oligomers-sensing probe in cerebrospinal fluid.

Amyloid-ß (Aß) oligomers are implicated in the onset of Alzheimer's disease (AD). Herein, quinoline-derived half-curcumin-dioxaborine (Q-OB) fluorescent probe was designed for detecting Aß oligomers by finely tailoring the hydrophobicity of the biannulate donor motifs in donor-π-acceptor structure. Q-OB shows a great sensing potency in dynamically monitoring oligomerization of Aß during amyloid fibrillogenesis in vitro. In addition, we applied this strategy to fluorometrically analyze Aß self-assembly kinetics in the cerebrospinal fluids (CSF) of AD patients. The fluorescence intensity of Q-OB in AD patients' CSF revealed a marked change of log (I/I0) value of 0.34 ± 0.13 (cognitive normal), 0.15 ± 0.12 (mild cognitive impairment), and 0.14 ± 0.10 (AD dementia), guiding to distinguish a state of AD continuum for early diagnosis of AD. These studies demonstrate the potential of our approach can expand the currently available preclinical diagnostic platform for the early stages of AD, aiding in the disruption of pathological progression and the development of appropriate treatment strategies.

Benzo[d]imidazole-pyrrolo[1,2-a]pyrazine Hybrids Ameliorate Amyloid Aggregates in the Brain of Alzheimer Transgenic Mice.

Abnormal assembly of amyloid ß (Aß) in the brain is implicated in Alzheimer's disease (AD) and is associated with cognitive impairments. Since Aß accumulation occurs in advance of the onset of clinical symptoms, identifying preventable drug candidates regulating Aß accumulation is regarded as a promising approach in AD therapeutic. Herein, we synthesized eight Yonsei Institute of pharmaceutical sciences Alzheimer's Drug (YIAD) compounds based on 5-benzyl-6-phenylbenzo[4,5]imidazo[1,2-a]pyrrolo[2,1-c]pyrazine structures. Subsequently, YIAD-0203 and YIAD-0205 were selected as effective candidates via thioflavin T assays and gel electrophoresis. The potential therapeutic effect of YIAD-0203 and YIAD-0205 on Aß aggregates was investigated through an AD transgenic mouse model with five familial AD mutations (5XFAD) by oral gavage. Significant amounts of Aß plaque and oligomer reduction were observed in the hippocampus region of both 4.3-month-old (early stage of AD) and 6.0-month-old (mid stage of AD) YIAD-0205-treated 5XFAD mice brains when compared to the nontreated brains. The ability of YIAD-0205 to ameliorate Aß aggregates in the early and mid stages of AD progression supports the notion that YIAD-0205 could be utilized as a reliable scaffold for the development of preventive AD drug candidates.

4-Acyl-3,4-dihydropyrrolo[1,2-a]pyrazine Derivative Rescued the Hippocampal-Dependent Cognitive Decline of 5XFAD Transgenic Mice by Dissociating Soluble and Insoluble Aß Aggregates.

Cerebral amyloid-ß (Aß) deposition is a representative hallmark of Alzheimer's disease (AD). Development of Aß-clearing small molecules could be an advantageous therapeutic strategy for Aß clearance considering the advantages in terms of side effects, cost-effectiveness, stability, and oral bioavailability. Here, we report an Aß-dissociating small molecule, YIAD-0121, a derivative of 4-acyl-3,4-dihydropyrrolo[1,2-a]pyrazine. Through a series of anti-Aß screening assays, YIAD-0121 was identified to inhibit Aß aggregation and dissociate preformed Aß fibrils in vitro. Furthermore, the administration of YIAD-0121 in 5XFAD transgenic AD mice inhibited the increase of cerebral Aß aggregation and progression of hippocampus-dependent cognitive decline, with ameliorated neuroinflammation.

Engineered Surface Halide Defects by Two-Dimensional Perovskite Passivation for Deformable Intelligent Photodetectors.

As attractive photoactive materials, metal halide perovskites demonstrate outstanding performance in a wide range of optoelectronic applications. Among the various compositions studied, mixed-halide perovskites have a finely tunable band gap that renders them desirable for targeted applications. Despite their advantages, photoinduced halide segregation often deters the photoelectric stability of the materials. Herein, we adopt a strategy of post-treating the perovskite surface with an organic spacer to generate a two-dimensional (2D) perovskite passivating layer. Trap-assisted recombination pathways can be selectively modulated by passivating the surface halide defects that cause photoinduced halide segregation. Fluorescence lifetime imaging of flat and bent surfaces of perovskites reveals that the perovskite lattice tolerates mechanical strain via the neutralizing passivation of ionic halide defects. Upon bending, the photocurrent response of the flexible photodetector is maintained over 83% for 2D passivated perovskite and drops to 23% for pristine perovskite. A flexible photodetector array built with 2D passivated perovskite, in combination with a deep learning algorithm, demonstrates excellent accuracy in determining letters of the alphabet for both flat (>96%) and bent (>93%) states. The connection of chemically modified charge carrier dynamics and mechanical properties revealed in this study offers valuable guidance for developing next-generation optoelectronic applications.

Aryloxypropanolamine targets amyloid aggregates and reverses Alzheimer-like phenotypes in Alzheimer mouse models.

BACKGROUND: Aggregated amyloid-ß (Aß) is considered a pathogenic initiator of Alzheimer's disease (AD), in strong association with tau hyperphosphorylation, neuroinflammation, synaptic dysfunction, and cognitive decline. As the removal of amyloid burden from AD patient brains by antibodies has shown therapeutic potential, the development of small molecule drugs inducing chemical dissociation and clearance of Aß is compelling as a therapeutic strategy. In this study, we synthesized and screened aryloxypropanolamine derivatives and identified 1-(3-(2,4-di-tert-pentylphenoxy)-2-hydroxypropyl)pyrrolidin-1-ium chloride, YIAD002, as a strong dissociator of Aß aggregates. METHODS: The dissociative activity of aryloxypropanolamine derivatives against Aß aggregates were evaluated through in vitro assays. Immunohistochemical staining, immunoblot assays, and the Morris water maze were used to assess the anti-Alzheimer potential in YIAD002-treated 5XFAD and transgenic APP/PS1 mice. Target-ligand interaction mechanism was characterized via a combination of peptide mapping, fluorescence dissociation assays, and constrained docking simulations. RESULTS: Among 11 aryloxypropanolamine derivatives, YIAD002 exerted strongest dissociative activity against ß-sheet-rich Aß aggregates. Upon oral administration, YIAD002 substantially reduced amyloid burden and accordingly, improved cognitive performance in the Morris water maze and attenuated major pathological hallmarks of AD including tauopathy, neuroinflammation, and synaptic protein loss. Mechanism studies suggest that YIAD002 interferes with intermolecular ß-sheet fibrillation by directly interacting with KLVFFA and IGLMVG domains of Aß. In addition, YIAD002 was found to possess dissociative activity against aggregates of pyroglutamate-modified Aß and tau. CONCLUSIONS: Collectively, our results evince the potential of chemical-driven dissociation of Aß aggregates by aryloxypropanolamines as a therapeutic modality of the amyloid clearance approach.

Orally Administered Benzofuran Derivative Disaggregated Aß Plaques and Oligomers in the Brain of 5XFAD Alzheimer Transgenic Mouse.

Amyloid-ß (Aß) aggregated forms are highly associated with the onset of Alzheimer's disease (AD). Aß abnormally accumulates in the brain and induces neuronal damages and symptoms of AD such as cognitive impairment and memory loss. Since an antibody drug, aducanumab, reduces Aß aggregates and delays clinical decline, clearance of accumulated Aß in the brain is accounted as a therapeutic approach to treat AD. In this study, we synthesized 17 benzofuran derivatives that may disaggregate Aß oligomers and plaques into inert monomers. By a series of Aß aggregation inhibition and aggregates' disaggregation assays utilizing thioflavin T assays and gel electrophoresis, YB-9, 2-((5-methoxy-3-(4-methoxyphenyl)benzofuran-6-yl)oxy)acetic acid, was selected as the final Aß-disaggregator candidate. When it was orally administered to the 8-month-old male transgenic mouse model with five familial AD mutations (5XFAD) via drinking water daily for two months, Aß oligomers and plaques in hippocampus were reduced. Consequently, decreased astrogliosis and rescued synaptic dysfunction were observed in the hippocampus of YB-9-treated 5XFAD mice compared with the untreated transgenic control group.

Anti-amyloidogenic indolizino[3,2-c]quinolines as imaging probes differentiating dense-core, diffuse, and coronal plaques of amyloid-ß.

Abnormal deposition of amyloid-ß (Aß) is a major biomarker that is often used to diagnose Alzheimer's disease (AD). The Aß plaque levels in the cortex and hippocampus are measured by either brain histology or positron emission tomography. Although cerebral plaques are found in several phenotypes, such as dense-core, diffuse, and coronal, imaging probes differentiating these plaques are currently unavailable. Here, we report that fluorescent indolizino[3,2-c]quinoline derivatives (YIQ) distinguish Aß plaque phenotypes in brains of 5XFAD Alzheimer transgenic mice. We synthesized and screened 64 YIQ compounds through a series of in vitro and ex vivo Aß staining assays. We found 20 compounds that could stain the Aß phenotypes, 10 for dense-core plaques, eight for both dense-core and diffuse plaques, and two for solely visualizing only the coronal plaques while leaving the centric core unstained. Among the 20 imaging candidates, five YIQs displaying anti-Aß aggregation efficacy were confirmed by thioflavin T assays and electrophoretic analyses.

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

[This corrects the article DOI: 10.1371/journal.pone.0243041.].

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

Alzheimer disease (AD) is a neurodegenerative disorder characterized by the aberrant production and accumulation of amyloid-ß (Aß) peptides in the brain. Accumulated Aß 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 Aß-indicator YI-13, 5-(4-fluorobenzoyl)-7,8-dihydropyrrolo[1,2-b]isoquinolin-9(6H)-one, which detects Aß 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 Aß as a target and YI-13 was selected as the final imaging candidate. YI-13 was found to stain and visualize insoluble Aß plaques in the brain tissue, of a transgenic mouse model with five familial AD mutations (5XFAD), by a histochemical approach and to label soluble Aß 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 Aß.

Alterations of aqueous humor Aß levels in Aß-infused and transgenic mouse models of Alzheimer disease.

Alzheimer's disease (AD) is an ageing-related neurodegenerative disease characterized and diagnosed by deposition of insoluble amyloid-ß (Aß) plaques in the brain. The plaque accumulation in the brain directly affects reduced levels of Aß in cerebrospinal fluid (CSF) and blood, as Aß can freely transport the blood-brain barrier, and clinical investigations have suggested these two biofluids as promising samples for in vitro diagnosis. Given that the human eye structurally resembles the brain and Aß accumulation often observed in the ocular region of AD patients, in this study, we examined aqueous humor Aß as another possible surrogate biomarker. First, using the acute Aß-infused AD mouse model by injecting Aß to the CSF in intracerebroventricular region of normal ICR mice, we investigated whether Aß concentration in the aqueous humor in AD models is positively correlated with the concentration in the CSF. Then, we examined the correlation of aqueous humor Aß levels with increased plaque deposition in the brain and reduced Aß levels in both CSF and blood in adult and aged 5XFAD Alzheimer transgenic mice. Collectively, the synthetic Aß injected into CSF immediately migrate to the aqueous humor, however, the age-dependently reducing pattern of Aß levels in CSF and blood was not observed in the aqueous humor.

A small molecule Nec-1 directly induces amyloid clearance in the brains of aged APP/PS1 mice.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the formation of toxic amyloid-ß (Aß) oligomers and plaques. Considering that Aß misfolding and aggregation precedes the progressive development of cognitive impairment in AD, investigating a therapeutic means by clearance of pre-existing Aß aggregates shows promise as a viable disease-modifying treatment. Here, we report that a small molecule, necrostatin-1 (Nec-1), reduces Aß aggregates back to non-toxic monomers in vitro and in vivo. Intravenous administration of Nec-1 reduced the levels of Aß plaques in the brains of aged APP/PS1 double transgenic mice. In addition, Nec-1 exhibited therapeutic effects against Aß aggregates by inhibiting Aß-induced brain cell death in neuronal and microglial cell lines. Nec-1 also showed anti-apoptotic and anti-necroptotic effects in the cortex of aged APP/PS1 mice by reducing levels of phosphorylated-RIPK3 and Bax and increasing the levels of Bcl-2. According to our data in vitro and in silico, the methyl group of the amine in the 2-thioxo-4-imidazolidinone is the key moiety of Nec-1 that directs its activity against aggregated Aß. Given that the accumulation of Aß aggregates is an important hallmark of AD, our studies provide strong evidence that Nec-1 may serve a key role in the development of AD treatment.

Comparative analyses of plasma amyloid-ß levels in heterogeneous and monomerized states by interdigitated microelectrode sensor system.

Detection of amyloid-ß (Aß) aggregates contributes to the diagnosis of Alzheimer disease (AD). Plasma Aß is deemed a less invasive and more accessible hallmark of AD, as Aß can penetrate blood-brain barriers. However, correlations between biofluidic Aß concentrations and AD progression has been tenuous. Here, we introduce a diagnostic technique that compares the heterogeneous and the monomerized states of Aß in plasma. We used a small molecule, EPPS [4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid], to dissociate aggregated Aß into monomers to enhance quantification accuracy. Subsequently, Aß levels of EPPS-treated plasma were compared to those of untreated samples to minimize inter- and intraindividual variations. The interdigitated microelectrode sensor system was used to measure plasma Aß levels on a scale of 0.1 pg/ml. The implementation of this self-standard blood test resulted in substantial distinctions between patients with AD and individuals with normal cognition (NC), with selectivity and sensitivity over 90%.