The Calcium-free form of Atorvastatin inhibits amyloid-β(1-42) aggregation in vitro

Mechanistic Insights into the Antibiofilm Activity of Simvastatin and Lovastatin against Bacillus subtilis

Statins have been reported for diverse pleiotropic activities, including antimicrobial and antibiofilm. However, due to the limited understanding of their mode of action, none of the statins have gained approval for antimicrobial or antibiofilm applications. In a recent drug repurposing study, we observed that two statins (i.e., Simvastatin and Lovastatin) interact stably with TasA(28-261), the principal extracellular matrix protein of Bacillus subtilis, and also induce inhibition of biofilm formation. Nevertheless, the underlying mechanism remained elusive. In the present study, we examined the impact of these statins on the physiological activity of TasA(28-261), specifically its interaction with TapA(33-253) and aggregation into the amyloid-like structure using purified recombinant TasA(28-261) and TapA(33-253) in amyloid detection-specific in vitro assays (i.e., CR binding and ThT staining assays). Results revealed that both statins interfered with amyloid formation by the TasA(28-261)-TapA(33-253) complex, while neither statin inhibited amyloid formation by lysozyme, a model amyloid-forming protein. Moreover, neither statin significantly altered the expressions of terminal regulatory genes (viz, sinR, sinI) and terminal effector genes (viz, tasA, tapA, and bslA) involved in biofilm formation by B. subtilis. While the intricate interplay between Simvastatin and Lovastatin with the diverse molecular constituents of B. subtilis biofilm remains to be elucidated conclusively, the findings obtained during the present study suggest that the underlying mechanism for Simvastatin- and Lovastatin-mediated inhibition of B. subtilis biofilm formation is manifested by interfering with the aggregation and amyloid formation by TasA(28-261)-TapA(33-253). These results represent one of the first experimental evidence for the underlying mechanism of antibiofilm activity of statins and offer valuable directions for future research to harness statins as antibiofilm therapeutics.

Delineating the tryptophan-galactosylamine conjugate mediated structural distortions in Aβ42 protofibrils

Amyloid-β (Aβ) fibrillation into neurotoxic soluble oligomers and mature fibrils is mainly responsible for the etiology of Alzheimer's disease (AD). A recent study revealed 61% disaggregation of the pre-formed Aβ42 fibrils upon incubating with a highly soluble tryptophan-galactosylamine conjugate, WGalNAc. WGalNAc displayed no toxicity and increased the viability of SH-SY5Y cells up to 62.9 ± 2% with an EC50 value of 2.3 μM against Aβ42 pre-formed fibrils. However, the key interactions and disruptive mechanism of WGalNAc against Aβ fibrils remain elusive. Thus, mechanistic insights into the disruptive potential of WGalNAc against Aβ42 protofibrils (PDB: 5OQV) were examined using molecular dynamics (MD) simulations. The molecular docking depicted a favourable binding energy (-6.60 kcal mol-1) and interaction of WGalNAc with the central hydrophobic core (CHC) region of chain A of the 5OQV protofibril. The MD simulations depicted that WGalNAc disrupted the contacts among Ala2, Phe4, Leu34, and Val36 in the hydrophobic core 1 of the 5OQV protofibril responsible for maintaining the stability of the LS-shaped 5OQV protofibril. WGalNAc binds favourably to the 5OQV protofibril (ΔGbinding = -21.76 ± 2.40 kcal mol-1) with a significant contribution from the van der Waals interaction term. Notably, the binding affinity between the neighbouring chains of the 5OQV protofibril was significantly reduced from -134.31 ± 11.12 to -121.88 ± 1.95 kcal mol-1 upon the incorporation of WGalNAc, which is consistent with the ThT kinetic results that revealed disaggregation of the pre-formed Aβ42 fibrils upon incubating with WGalNAc. The in silico ADMET properties of WGalNAc showed its ability as a promising therapeutic candidate due to its blood-brain barrier (BBB) permeability, extended half-life, and non-toxic profile. The MD simulations illuminated the binding interactions of WGalNAc with the 5OQV protofibril and provided mechanistic insights into the WGalNAc-mediated structural distortions in the 5OQV protofibril.

Application of metallic nanoparticles-amyloid protein supramolecular materials in tissue engineering and drug delivery: Recent progress and perspectives

Supramolecular medicine refers to the formulation of therapeutic and diagnostic agents through supramolecular techniques, amid treating, diagnosing, and preventing disease. Recently, there has been growing interest in developing metal nanoparticles (MNPs)-amyloid hybrid materials, which have the potential to revolutionize medical applications. Furthermore, the development of MNPs-amyloid hydrogel/scaffold supramolecules represents a promising new direction in amyloid nanotechnology, with potential applications in tissue engineering and biomedicine. This review first provides a brief introduction to the formation process of protein amyloid aggregates and their unique nanostructures. Subsequently, we focused on recent investigations into the use of MNPs-amyloid hybrid materials in tissue engineering and biomedicine. We anticipate that MNPs-amyloid supramolecular materials will pave the way for new functional materials in medical science, particularly in the field of tissue engineering.

NMR studies of amyloid interactions

Amyloid fibrils are insoluble, fibrous nanostructures that accumulate extracellularly in biological tissue during the progression of several human disorders, including Alzheimer's disease (AD) and type 2 diabetes. Fibrils are assembled from protein monomers via the transient formation of soluble, cytotoxic oligomers, and have a common molecular architecture consisting of a spinal core of hydrogen-bonded protein β-strands. For the past 25 years, NMR spectroscopy has been at the forefront of research into the structure and assembly mechanisms of amyloid aggregates. Until the recent boom in fibril structure analysis by cryo-electron microscopy, solid-state NMR was unrivalled in its ability to provide atomic-level models of amyloid fibril architecture. Solution-state NMR has also provided complementary information on the early stages in the amyloid assembly mechanism. Now, both NMR modalities are proving to be valuable in unravelling the complex interactions between amyloid species and a diverse range of physiological metal ions, molecules and surfaces that influence the assembly pathway, kinetics, morphology and clearance in vivo. Here, an overview is presented of the main applications of solid-state and solution-state NMR for studying the interactions between amyloid proteins and biomembranes, glycosaminoglycan polysaccharides, metal ions, polyphenols, synthetic therapeutics and diagnostics. Key NMR methodology is reviewed along with examples of how to overcome the challenges of detecting interactions with aggregating proteins. The review heralds this new role for NMR in providing a comprehensive and pathologically-relevant view of the interactions between protein and non-protein components of amyloid. Coverage of both solid- and solution-state NMR methods and applications herein will be informative and valuable to the broad communities that are interested in amyloid proteins.

Reverse engineering of feedforward cortical-Hippocampal microcircuits for modelling neural network function and dysfunction

Engineered biological neural networks are indispensable models for investigation of neural function and dysfunction from the subcellular to the network level. Notably, advanced neuroengineering approaches are of significant interest for their potential to replicate the topological and functional organization of brain networks. In this study, we reverse engineered feedforward neural networks of primary cortical and hippocampal neurons, using a custom-designed multinodal microfluidic device with Tesla valve inspired microtunnels. By interfacing this device with nanoporous microelectrodes, we show that the reverse engineered multinodal neural networks exhibit capacity for both segregated and integrated functional activity, mimicking brain network dynamics. To advocate the broader applicability of our model system, we induced localized perturbations with amyloid beta to study the impact of pathology on network functionality. Additionally, we demonstrate long-term culturing of subregion- and layer specific neurons extracted from the entorhinal cortex and hippocampus of adult Alzheimer's-model mice and rats. Our results thus highlight the potential of our approach for reverse engineering of anatomically relevant multinodal neural networks to study dynamic structure-function relationships in both healthy and pathological conditions.

Structural Reorganization Mechanism of the Aβ42 Fibril Mediated by N-Substituted Oligopyrrolamide ADH-353

The inhibition of amyloid-β (Aβ) fibrillation and clearance of Aβ aggregates have emerged as a potential pharmacological strategy to alleviate Aβ aggregate-induced neurotoxicity in Alzheimer's disease (AD). Maity et al. shortlisted ADH-353 from a small library of positively charged N-substituted oligopyrrolamides for its notable ability to inhibit Aβ fibrillation, disintegrate intracellular cytotoxic Aβ oligomers, and alleviate Aβ-induced cytotoxicity in the SH-SY5Y and N2a cells. However, the molecular mechanism through which ADH-353 interacts with the Aβ42 fibrils, leading to their disruption and subsequent clearance, remains unclear. Thus, a detailed molecular mechanism underlying the disruption of neurotoxic Aβ42 fibrils (PDB ID 2NAO) by ADH-353 has been illuminated in this work using molecular dynamics simulations. Interestingly, conformational snapshots during simulation depicted the shortening and disappearance of β-strands and the emergence of a helix conformation, indicating a loss of the well-organized β-sheet-rich structure of the disease-relevant Aβ42 fibril on the incorporation of ADH-353. ADH-353 binds strongly to the Aβ42 fibril (ΔGbinding= -142.91 ± 1.61 kcal/mol) with a notable contribution from the electrostatic interactions between positively charged N-propylamine side chains of ADH-353 with the glutamic (Glu3, Glu11, and Glu22) and aspartic (Asp7 and Asp23) acid residues of the Aβ42 fibril. This aligns well with heteronuclear single quantum coherence NMR studies, which depict that the binding of ADH-353 with the Aβ peptide is driven by electrostatic and hydrophobic contacts. Furthermore, a noteworthy decrease in the binding affinity of Aβ42 fibril chains on the incorporation of ADH-353 indicates the weakening of interchain interactions leading to the disruption of the double-horseshoe conformation of the Aβ42 fibril. The illumination of key interactions responsible for the destabilization of the Aβ42 fibril by ADH-353 in this work will greatly aid in designing new chemical scaffolds with enhanced efficacy for the clearance of Aβ aggregates in AD.

Cell-Penetrating Peptides: Promising Therapeutics and Drug-Delivery Systems for Neurodegenerative Diseases

Currently, one of the most significant and rapidly growing unmet medical challenges is the treatment of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). This challenge encompasses the imperative development of efficacious therapeutic agents and overcoming the intricacies of the blood-brain barrier for successful drug delivery. Here we focus on the delivery aspect with particular emphasis on cell-penetrating peptides (CPPs), widely used in basic and translational research as they enhance drug delivery to challenging targets such as tissue and cellular compartments and thus increase therapeutic efficacy. The combination of CPPs with nanomaterials such as nanoparticles (NPs) improves the performance, accuracy, and stability of drug delivery and enables higher drug loads. Our review presents and discusses research that utilizes CPPs, either alone or in conjugation with NPs, to mitigate the pathogenic effects of neurodegenerative diseases with particular reference to AD and PD.

A Comparative Study between Lycorine and Galantamine Abilities to Interact with AMYLOID β and Reduce In Vitro Neurotoxicity

Galantamine is a natural alkaloid extracted from the Amaryllidaceae plants and is used as the active ingredient of a drug approved for the treatment of the early stages of Alzheimer's disease. It mainly acts as an acetylcholinesterase (AChE) inhibitor, increasing concentrations of the acetylcholine neurotransmitter. Recent cellular studies have also shown the ability of galantamine to protect SH-SY5Y cell lines against amyloid-β (Aβ)-induced toxicity. Such investigations have supported and validated further in-depth studies for understanding the chemical and molecular features associated with galantamine-protective abilities. In addition to galantamine, other natural alkaloids are known to possess AChE inhibitory activity; among them lycorine has been extensively investigated for its antibacterial, anti-inflammatory and antitumoral activities as well. Despite its interesting biological properties, lycorine's neuroprotective functions against Aβ-induced damages have not been explored so far. In this research study, the ability of galantamine and lycorine to suppress Aβ-induced in vitro neuronal toxicity was evaluated by investigating the chemical interactions of the two alkaloids with Aβ peptide. A multi-technique spectroscopic analysis and cellular cytotoxicity assays were applied to obtain new insights on these molecular associations. The comparison between the behaviors exhibited by the two alkaloids indicates that both compounds possess analogue abilities to interact with the amyloidogenic peptide and protect cells.

Proteostasis Response to Protein Misfolding in Controlled Hypertension

Hypertension is the most determinant risk factor for cardiovascular diseases. Early intervention and future therapies targeting hypertension mechanisms may improve the quality of life and clinical outcomes. Hypertension has a complex multifactorial aetiology and was recently associated with protein homeostasis (proteostasis). This work aimed to characterize proteostasis in easy-to-access plasma samples from 40 individuals, 20 with controlled hypertension and 20 age- and gender-matched normotensive individuals. Proteostasis was evaluated by quantifying the levels of protein aggregates through different techniques, including fluorescent probes, slot blot immunoassays and Fourier-transform infrared spectroscopy (FTIR). No significant between-group differences were observed in the absolute levels of various protein aggregates (Proteostat or Thioflavin T-stained aggregates; prefibrillar oligomers and fibrils) or total levels of proteostasis-related proteins (Ubiquitin and Clusterin). However, significant positive associations between Endothelin 1 and protein aggregation or proteostasis biomarkers (such as fibrils and ubiquitin) were only observed in the hypertension group. The same is true for the association between the proteins involved in quality control and protein aggregates. These results suggest that proteostasis mechanisms are actively engaged in hypertension as a coping mechanism to counteract its pathological effects in proteome stability, even when individuals are chronically medicated and presenting controlled blood pressure levels.