Nanoscopic Portrait of an Amyloidogenic Pathway Visualized through Tip-Enhanced Raman Spectroscopy

Strategies for measuring concentrations and forms of amyloid-β peptides

Alzheimer's disease (AD) is affecting more and more people worldwide without the effective treatment, while the existed pathological mechanism has been confirmed barely useful in the treatment. Amyloid-β peptide (Aβ), a main component of senile plaque, is regarded as the most promising target in AD treatment. Aβ clearance from AD brain seems to be a reliably therapeutic strategy, as the two exited drugs, GV-971 and aducanumab, are both developed based on it. However, doubt still exists. To exhaustive expound on the pathological mechanism of Aβ, rigorous analyses on the concentrations and aggregation forms are essential. Thus, it is attracting broad attention these years. However, most of the sensors have not been used in pathological studies, as the lack of the bridge between analytical chemist and pathologists. In this review, we made a brief introduce on Aβ-related pathological mechanism included in β-amyloid hypothesis to elucidate the detection conditions of sensor methods. Furthermore, a summary of the sensor methods was made, which were based on Aβ concentrations and form detections that have been developed in the past 10 years. As the greatest number of the sensors were built on fluorescent spectroscopy, electrochemistry, and Roman spectroscopy, detailed elucidation on them was made. Notably, the aggregation process is another important factor in revealing the progress of AD and developing the treatment methods, so the sensors on monitoring Aβ aggregation processes were also summarized.

Screening Carbon Nano Materials for Preventing Amyloid Protein Aggregation by Adopting a Facile Method

The soluble-to-toxic transformation of intrinsically disordered amyloidogenic proteins such as amyloid beta (Aβ), α-synuclein, mutant Huntingtin Protein (mHTT) and islet amyloid polypeptide (IAPP) among others are associated with disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and Type 2 Diabetes (T2D), respectively. The dissolution of mature fibrils and toxic amyloidogenic intermediates, including oligomers, continues to be the pinnacle in the treatment of neurodegenerative disorders. Yet, methods to effectively and quantitatively report on the interconversion between amyloid monomers, oligomers and mature fibrils fall short. Here we describe a simplified method that implements the use of gel electrophoresis to address the transformation between soluble monomeric amyloid proteins and mature amyloid fibrils. The technique implements an optimized but well-known, simple, inexpensive, and quantitative assessment previously used to assess the oligomerization of amyloid monomers and subsequent amyloid fibrils. This method facilitates the screening of small molecules that disintegrate oligomers and fibrils into monomers, dimers, and trimers and/or retain amyloid proteins in their monomeric forms. Most importantly, our optimized method diminishes existing barriers associated with existing (alternative) techniques to evaluate fibril formation and intervention.

Screening Carbon Nano Materials for preventing amyloid protein aggregation by adopting a facile method

The soluble-to-toxic transformation of intrinsically disordered amyloidogenic proteins such as amyloid beta (Aβ), α-synuclein, mutant Huntingtin Protein (mHTT) and islet amyloid polypeptide (IAPP) among others is associated with disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and Type 2 Diabetes (T2D), respectively. The dissolution of mature fibrils and toxic amyloidogenic intermediates including oligomers continues to be the pinnacle in the treatment of neurodegenerative disorders. Yet, methods to effectively, and quantitatively, report on the interconversion between amyloid monomers, oligomers and mature fibrils fall short. Here we describe a simplified method that implements the use of gel electrophoresis to address the transformation between soluble monomeric amyloid proteins and mature amyloid fibrils. The technique implements an optimized but well-known, simple, inexpensive and quantitative assessment previously used to assess the oligomerization of amyloid monomers and subsequent amyloid fibrils. This method facilitates the screening of small molecules that disintegrate oligomers and fibrils into monomers, dimers, and trimers and/or retain amyloid proteins in their monomeric forms. Most importantly, our optimized method diminishes existing barriers associated with existing (alternative) techniques to evaluate fibril formation and intervention.

Brain Virome in Neurodegenerative Disorders: Insights from Transcriptomic Data Analysis

Neurodegenerative disorders (NDs) are chronic ailments of the central nervous system that gradually deteriorate the structures and functions of neurons. The etiologies of NDs include genetic factors, aging, infections, starvation, brain trauma, and spinal cord injury, among others. However, it is unclear whether viral infections impact the prognosis of NDs or contribute to their development. Hence, we investigated the prevalence of neurotropic viruses in brain samples by using transcriptomic data. A total of 1635 viral isolates with complete genomic information was used to investigate the incidence of 18 distinct viruses across 129 data sets from healthy and ND subjects. Our findings support the evidence pointing to the existence of a brain virome where certain viruses co-occur. We further hypothesize that distinct virome profiles are linked to different forms of NDs.

Resolving the soluble-to-toxic transformation of amyloidogenic proteins: A method to assess intervention by small-molecules

The soluble-to-toxic transformation of intrinsically disordered amyloidogenic proteins such as amyloid beta (Aβ), α-synuclein, mutant Huntingtin Protein (mHTT) and islet amyloid polypeptide (IAPP) among others is associated with disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and Type 2 Diabetes (T2D), respectively. Conversely, the dissolution of mature fibrils and toxic amyloidogenic intermediates including oligomers remains the holy grail in the treatment of neurodegenerative disorders. Yet, methods to effectively, and quantitatively, report on the interconversion between amyloid monomers, oligomers and mature fibrils fall short. For the first time, we describe the use of gel electrophoresis to address the transformation between soluble monomeric amyloid proteins and mature amyloid fibrils. The technique permits rapid, inexpensive and quantitative assessment of the fraction of amyloid monomers that form intermediates and mature fibrils. In addition, the method facilitates the screening of small molecules that disintegrate oligomers and fibrils into monomers or retain amyloid proteins in their monomeric forms. Importantly, our methodological advance diminishes major existing barriers associated with existing (alternative) techniques to evaluate fibril formation and intervention.

Citric Acid-Derived Carbon Quantum Dots Attenuate Paraquat-Induced Neuronal Compromise In Vitro and In Vivo

The potent environmental herbicide and weedicide paraquat is linked to neuromotor defects and Parkinson's disease (PD). We have evaluated the neuroprotective role of citric acid-sourced carbon quantum dots (Cit-CQDs) on paraquat-insulted human neuroblastoma-derived SH-SY5Y cell lines and on a paraquat-exposed nematode (Caenorhabditis elegans). Our data reveal that Cit-CQDs are able to scavenge free radicals in test tube assays and mitigate paraquat-elevated reactive oxygen species (ROS) levels in SH-SY5Y cells. Furthermore, Cit-CQDs protect the cell line from paraquat, which otherwise elicits cell death. Cit-CQDs-challenged nematodes demonstrate enhanced survival rates 72 h post-paraquat exposure compared to controls. Paraquat ablates dopamine (DA) neurons, which results in compromised locomotor function in nematodes. However, the neurons remained intact when the nematodes were incubated with Cit-CQDs prior to neurotoxicant exposure. The collective data suggest Cit-CQDs offer neuroprotection for cell lines and organisms from xenotoxicant-associated neuronal injury and death. The study suggests Cit-CQDs as a potentially viable green chemistry-synthesized, biobased nanomaterial for intervention in neurodegenerative disorders.

Carbon Quantum Dots for Treatment of Amyloid Disorders

Prion-like amyloids self-template and form toxic oligomers, protofibrils, and fibrils from their soluble monomers; a phenomenon that has been implicated in the onset and progress of neurodegenerative disorders such as Alzheimer's (AD), Parkinson's (PD), Huntington's, and systemic lysozyme amyloidosis. Carbon quantum dots (CQDs), sourced from Na-citrate as a carbon precursor were synthesized and characterized before being tested for their ability to intervene in amyloidogenic (fibril-forming) trajectories. Hen-egg white lysozyme (HEWL) served as a model amyloidogenic protein. A pulse-chase lysozyme fibril-forming assay developed to examine the impact of CQDs on the HEWL amyloid-fibril-forming trajectory used ThT fluorescence as a reporter of mature fibril presence. The results revealed that the Na-citrate-derived CQDs were able to intervene at multiple points along the fibril-forming trajectory by preventing the conversion of both monomeric and oligomeric HEWL intermediates into mature fibrils. In addition, and importantly, the carbon nano material (CNM) was able to dissolve oligomeric HEWL into monomeric HEWL and provoke the disaggregation of mature HEWL fibrils. These results suggest that Na-citrate CQD's intervene in amyloidogenesis by multiple mechanisms. The gathered data, coupled with cell-line results demonstrating the relatively low cytotoxicity of Na-citrate CQDs, suggest that this emerging CNM has the potential to intervene both prophylactically and therapeutically in protein misfolding diseases. The aforementioned findings are likely to enable Na-citrate CQDs to eventually transition to both cell-line and preclinical models of protein-misfolding-related disorders. Importantly, the study outcomes positions Na-citrate CQDs as an important class of chemical, nanotechnological, and biobased interventional tools in neuroscience.

Neuroprotective Effect of Brazilin on Amyloid β (25-35)-Induced Pathology in a Human Neuroblastoma Model

Until the recent past, the sole exemplar of proteins as infectious agents leading to neurodegenerative disorders remained the prion protein. Since then, the self-seeding mechanism characteristic of the prion protein has also been attributed to other neurodegenerative-disease-associated proteins, including amyloid-β (Aβ), tau, and α-synuclein (α-Syn). In model cell line studies, truncated Aβ, viz. amyloid beta (25-35), has been found to influence cellular homeostasis through its interactions with, and via, the disruption of key housekeeping machinery. Here, we demonstrate that the incubation of human neuroblastoma (SH-SY5Y) cell line with Brazilin ((6aS,11bR)-7,11b-dihydro-6H-indeno[2,1-c]chromene-3,6a,9,10-tetrol) prior to Aβ (25-35)-insult protected the cells from oxidative stress and apoptotic cell death. Furthermore, Brazilin mitigated Aβ-induced alterations in protein disulfide isomerase (PDI) and α-synuclein status, both of which are important biomarkers that report on Parkinson's pathogenesis. The results obtained in this study suggest that the tetrol is neuroprotective and helps resist Aβ-induced cross-pathology and amyloidogenic onset.