Characterization of copper interactions with alzheimer amyloid beta peptides: identification of an attomolar-affinity copper binding site on amyloid beta1-42

The Binding of Cu2+ to Lipid Membranes Is Not Substantially Influenced by Electrostatic Screening

Gouy-Chapman theory predicts that salt screening and modulating the interfacial charge density should strongly influence the apparent dissociation constant, Kd,app, between Cu2+ and negatively charged phosphatidylserine (PS) lipids in supported lipid bilayers (SLBs). Specifically, Kd,app would be expected to increase (weaken binding) by a factor of 40 when 100 mM NaCl is introduced into the solution because of electrostatic screening between the membrane and Cu2+ cations. Surprisingly, however, fluorescence quenching measurements demonstrate that Kd,app increases by less than a factor of 2 when increasing the salt concentration in the presence of standard buffers, such as tris(hydroxymethyl)aminomethane (Tris). Moreover, increasing the negative surface charge density by a factor of 4 would be predicted to decrease (strengthen binding) Kd,app by 3 orders of magnitude. Instead, Kd,app increases slightly when 15 mol % phosphatidylglycerol (PG), a negatively charged lipid, is introduced into SLBs already containing 5 mol % PS. Such findings indicate that electrostatic double layer theory is not a useful approach for predicting the binding behavior of transition metal cations to negatively charged interfaces. The problem lies with the fact that standard buffers, such as Tris, form a wide variety of coordination complexes in bulk solution with transition metal cations like Cu2+. Typically, dozens of complexes are present simultaneously at any given pH value and the net charge on them ranges from positive to neutral to negative. Such variations in charge on the complexes result in electrostatic screening and interfacial potential effects that are substantially diminished or nonexistent. These results should generally apply to the binding behavior of first row transition metal ions, when the cations predominantly reside in complexes rather than as free ions. This includes in vivo conditions, where the concentration of free transition metal ions is often very low.

The J bs-5YP peptide can alleviate dementia in senile mice by restoring the transcription of Slc40a1 to secrete the excessive iron from brain

INTRODUCTION

With age and ATP decrease in the body, the transcription factors hypophosphorylation weakens the transcription of Slc40a1 and hinders the expression of the iron discharger ferroportin. This may lead to iron accumulation in the brain and the catalysis of free radicals that damage cerebral neurons and eventually lead to Alzheimer's disease (AD).

OBJECTIVES

To prevent AD caused by brain iron excretion disorders and reveal the mechanism of J bs-5YP peptide restoring ferroportin.

METHODS

We prepared J bs-YP peptide and administered it to the senile mice with dementia. Then, the intelligence of the mice was tested using a Morris Water Maze. The ATP content in the body was detected using the ATP hydrophysis and Phosphate precipitation method. The activation of Slc40a1 transcription was assayed with ATAC seq and the ferroportin, as well as the phosphorylation levels of Ets1 in brain were detected by Western Blot.

RESULTS

The phosphorylation level of Ets1in brain was enhanced, and subsequently, the transcription of Slc40a1 was activated and ferroportin was increased in the brain, the levels of iron and free radicals were reduced, with the neurons protection, and the dementia was ultimately alleviated in the senile mice.

CONCLUSION

J bs-5YP can recover the expression of ferroportin to excrete excessive iron in the brain of senile mice with dementia by enhancing the transcription of Slc40a1 via phosphorylating Ets1, revealing the potential of J bs-5YP as a drug to alleviate senile dementia.

A novel prognostic scoring model based on cuproptosis identifies COMMD1 as a novel therapy target for liver hepatocellular carcinoma

Background

Primary liver cancer poses a significant global health burden, with projections indicating a surpassing of one million cases by 2025. Cuproptosis, a copper-dependent mechanism of cell death, plays a crucial role in the pathogenesis, progression, and prognosis of various cancers, including hepatocellular carcinoma (HCC).

Purpose

This study aimed to develop a prognostic model for HCC based on cuproptosis-related genes, utilizing clinical data and gene expression profiles from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases.

Materials and Methods

Clinical features and gene expression data of HCC patients were collected from publicly available databases. Patients from TCGA were randomly divided into training and testing sets, and Lasso Cox regression was applied to develop a predictive model using cuproptosis-related genes.

Results

The analysis identified Copper Metabolism Domain Containing 1 (COMMD1) as a potential prognostic marker for HCC, with deletion of this gene impacting disease progression. Cellular functional experiments validated the role of COMMD1 in HCC.

Conclusions

COMMD1 emerges as a promising candidate for HCC treatment, with implications for prognosis prediction and therapeutic targeting.

Inflammatory signaling pathways in Alzheimer's disease: Mechanistic insights and possible therapeutic interventions

The complex pathophysiology of Alzheimer's disease (AD) poses challenges for the development of therapies. Recently, neuroinflammation has been identified as a key pathogenic mechanism underlying AD, while inflammation has emerged as a possible target for the management and prevention of AD. Several prior studies have demonstrated that medications modulating neuroinflammation might lessen AD symptoms, mostly by controlling neuroinflammatory signaling pathways such as the NF-κB, MAPK, NLRP3, etc, and their respective signaling cascade. Moreover, targeting these inflammatory modalities with inhibitors, natural products, and metabolites has been the subject of intensive research because of their anti-inflammatory characteristics, with many studies demonstrating noteworthy pharmacological capabilities and potential clinical applications. Therefore, targeting inflammation is considered a promising strategy for treating AD. This review comprehensively elucidates the neuroinflammatory mechanisms underlying AD progression and the beneficial effects of inhibitors, natural products, and metabolites in AD treatment.

Factors Affecting Pathological Amyloid Protein Transformation: From Post-Translational Modifications to Chaperones

The review discusses the influence of various factors (e.g., post-translational modifications and chaperones) on the pathological transformation of amyloidogenic proteins involved in the onset and development of neurodegenerative diseases (Alzheimer's and Parkinson's diseases) and spongiform encephalopathies of various origin with special focus on the role of α-synuclein, prion protein, and, to a lesser extent, beta-amyloid peptide. The factors investigated by the authors of this review are discussed in more detail, including posttranslational modifications (glycation and S-nitrosylation), cinnamic acid derivatives and dendrimers, and chaperonins (eukaryotic, bacterial, and phage). A special section is devoted to the role of the gastrointestinal microbiota in the pathogenesis of amyloid neurodegenerative diseases, in particular, its involvement in the transformation of infectious prions and possibly other proteins capable of prion-like transmission of amyloidogenic diseases.

Neuroprotective Potential of Indole-Based Compounds: A Biochemical Study on Antioxidant Properties and Amyloid Disaggregation in Neuroblastoma Cells

Based on the established neuroprotective properties of indole-based compounds and their significant potential as multi-targeted therapeutic agents, a series of synthetic indole-phenolic compounds was evaluated as multifunctional neuroprotectors. Each compound demonstrated metal-chelating properties, particularly in sequestering copper ions, with quantitative analysis revealing approximately 40% chelating activity across all the compounds. In cellular models, these hybrid compounds exhibited strong antioxidant and cytoprotective effects, countering reactive oxygen species (ROS) generated by the Aβ(25-35) peptide and its oxidative byproduct, hydrogen peroxide, as demonstrated by quantitative analysis showing on average a 25% increase in cell viability and a reduction in ROS levels to basal states. Further analysis using thioflavin T fluorescence assays, circular dichroism, and computational studies indicated that the synthesized derivatives effectively promoted the self-disaggregation of the Aβ(25-35) fragment. Taken together, these findings suggest a unique profile of neuroprotective actions for indole-phenolic derivatives, combining chelating, antioxidant, and anti-aggregation properties, which position them as promising compounds for the development of multifunctional agents in Alzheimer's disease therapy. The methods used provide reliable in vitro data, although further in vivo validation and assessment of blood-brain barrier penetration are needed to confirm therapeutic efficacy and safety.

Alterations in zinc, copper, and iron levels in the retina and brain of Alzheimer's disease patients and the APP/PS1 mouse model

Transition metals like copper (Cu), iron (Fe), and zinc (Zn) are vital for normal central nervous system function and are also linked to neurodegeneration, particularly in the onset and progression of Alzheimer's disease (AD). Their alterations in AD, identified prior to amyloid plaque aggregation, offer a unique target for staging pre-amyloid AD. However, analysing their levels in the brain is extremely challenging, necessitating the development of alternative approaches. Here, we utilized laser ablation-inductively coupled plasma-mass spectrometry and solution nebulization-inductively coupled plasma-mass spectrometry to quantitatively measure Cu, Fe, and Zn concentrations in the retina and hippocampus samples obtained from human donors (i.e. AD and healthy controls), and in the amyloid precursor protein/presenilin 1 (APP/PS1) mouse model of AD and wild-type (WT) controls, aged 9 and 18 months. Our findings revealed significantly elevated Cu, Fe, and Zn levels in the retina (*P < .05, P < .01, and P < .001) and hippocampus (*P < .05, *P < .05, and *P < .05) of human AD samples compared to healthy controls. Conversely, APP/PS1 mouse models exhibited notably lower metal levels in the same regions compared to WT mice-Cu, Fe, and Zn levels in the retina (**P < .01, *P < .05, and *P < .05) and hippocampus (**P < .01, **P < .01, and *P < .05). The contrasting metal profiles in human and mouse samples, yet similar patterns within each species' retina and brain, suggest the retina mirrors cerebral metal dyshomoeostasis in AD. Our findings lay the groundwork for staging pre-AD pathophysiology through assessment of transition metal levels in the retina.

Bifunctional Copper Chelators Capable of Reducing Aβ Aggregation and Aβ-Induced Oxidative Stress

Five bifunctional copper chelating agents, Alz-(1-5), designed to prevent beta-amyloid (Aβ) aggregation, were synthesized, and the leader compound (Alz-5) was chosen. Alz-5 acts as a bifunctional chelator that can interact with various Aβ aggregates and reduce their neurotoxicity. Reactive oxygen species measurements provided by the Pt-nanoelectrode technique in single Aβ42-affected human neuroblastoma SH-SY5Y cells revealed significant antioxidant activity of Alz-5. AFM data obtained on Aβ42 fibrils clearly indicate the antiaggregating property of Alz-5. To gain insights into the changes in the physiomechanical properties of Aβ42-affected cells, as well as in order to evaluate the antiaggregating ability of Alz-5, Young's modulus mapping on living SH-SY5Y cells affected consequently by Aβ42 and Alz-5 was conducted, and the ability of Alz-5 to decrease cell rigidity induced by Aβ42 was indisputably proven. Low cell toxicity and antioxidating properties, in conjunction with AFM and SICM-based biophysical provided on Aβ42-affected SH-SY5Y cells, support Alz-5 as a potential inhibitor of Aβ aggregation.

Mass spectrometry reflects key aspects of copper-amyloid β chemistry

Mass spectrometry is a powerful method to study protein complexes; however, biochemical reactions are typically beyond the scope of MS studies. Here, we have studied the gas-phase redox chemistry of the [copper(II) - amyloid β] complex and show that the sequence-dependence of this chemistry reflects key aspects of the known in vitro behaviour of different variants of the peptide.

Fluorescent Peptides Sequester Redox Copper to Mitigate Oxidative Stress, Amyloid Toxicity, and Neuroinflammation

Alzheimer's disease is a progressive neurodegenerative disorder that significantly contributes to dementia. The lack of effective therapeutic interventions presents a significant challenge to global health. We have developed a set of short peptides (PNGln) conjugated with a dual-functional fluorophoric amino acid (NGln). The lead peptide, P2NGln, displays a high affinity for Cu2+, maintaining the metal ion in a redox-inactive state. This mitigates the cytotoxicity generated by reactive oxygen species (ROS), which are produced by Cu2+ under the reductive conditions of Asc and Aβ16 or Aβ42. Furthermore, P2NGln inhibits both Cu-dependent and -independent fibrillation of Aβ42, along with the subsequent toxicity induced by Aβ42. In addition, P2NGln exhibits inhibitory effects on the production of lipopolysaccharide (LPS)-induced ROS and reactive nitrogen species (RNS) in microglial cells. In vitro and cellular studies indicate that P2NGln could significantly reduce Aβ-Cu2+-induced ROS production, amyloid toxicity, and neuroinflammation, offering an innovative strategy against Alzheimer's disease.

Glyceraldehyde-3-phosphate dehydrogenase is involved in the pathogenesis of Alzheimer's disease

One of important characteristics of Alzheimer's disease is a persistent oxidative/nitrosative stress caused by pro-oxidant properties of amyloid-beta peptide (Aβ) and chronic inflammation in the brain. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is easily oxidized under oxidative stress. Numerous data indicate that oxidative modifications of GAPDH in vitro and in cell cultures stimulate GAPDH denaturation and aggregation, and the catalytic cysteine residue Cys152 is important for these processes. Both intracellular and extracellular GAPDH aggregates are toxic for the cells. Interaction of denatured GAPDH with soluble Aβ results in mixed insoluble aggregates with increased toxicity. The above-described properties of GAPDH (sensitivity to oxidation and propensity to form aggregates, including mixed aggregates with Aβ) determine its role in the pathogenesis of Alzheimer's disease.

Preparation and Characterization of Zn(II)-Stabilized Aβ42 Oligomers

Aβ oligomers are being investigated as cytotoxic agents in Alzheimer's disease (AD). Because of their transient nature and conformational heterogeneity, the relationship between the structure and activity of these oligomers is still poorly understood. Hence, methods for stabilizing Aβ oligomeric species relevant to AD are needed to uncover the structural determinants of their cytotoxicity. Here, we build on the observation that metal ions and metabolites have been shown to interact with Aβ, influencing its aggregation and stabilizing its oligomeric species. We thus developed a method that uses zinc ions, Zn(II), to stabilize oligomers produced by the 42-residue form of Aβ (Aβ42), which is dysregulated in AD. These Aβ42-Zn(II) oligomers are small in size, spanning the 10-30 nm range, stable at physiological temperature, and with a broad toxic profile in human neuroblastoma cells. These oligomers offer a tool to study the mechanisms of toxicity of Aβ oligomers in cellular and animal AD models.

Current biomarkers and treatment strategies in Alzheimer disease: An overview and future perspectives

Alzheimer's disease (AD), a progressive degenerative disorder first identified by Alois Alzheimer in 1907, poses a significant public health challenge. Despite its prevalence and impact, there is currently no definitive ante mortem diagnosis for AD pathogenesis. By 2050, the United States may face a staggering 13.8 million AD patients. This review provides a concise summary of current AD biomarkers, available treatments, and potential future therapeutic approaches. The review begins by outlining existing drug targets and mechanisms in AD, along with a discussion of current treatment options. We explore various approaches targeting Amyloid β (Aβ), Tau Protein aggregation, Tau Kinases, Glycogen Synthase kinase-3β, CDK-5 inhibitors, Heat Shock Proteins (HSP), oxidative stress, inflammation, metals, Apolipoprotein E (ApoE) modulators, and Notch signaling. Additionally, we examine the historical use of Estradiol (E2) as an AD therapy, as well as the outcomes of Randomized Controlled Trials (RCTs) that evaluated antioxidants (e.g., vitamin E) and omega-3 polyunsaturated fatty acids as alternative treatment options. Notably, positive effects of docosahexaenoic acid nutriment in older adults with cognitive impairment or AD are highlighted. Furthermore, this review offers insights into ongoing clinical trials and potential therapies, shedding light on the dynamic research landscape in AD treatment.

Impact of aging on copper isotopic composition in the murine brain

Aging is the main risk factor for Alzheimer's disease (AD). AD is linked to alterations in metal homeostasis and changes in stable metal isotopic composition can occur, possibly allowing the latter to serve as relevant biomarkers for potential AD diagnosis. Copper stable isotopes are used to investigate changes in Cu homeostasis associated with various diseases. Prior work has shown that in AD mouse models, the accumulation of 63Cu in the brain is associated with the disease's progression. However, our understanding of how the normal aging process influences the brain's isotopic composition of copper remains limited. In order to determine the utility and predictive power of Cu isotopes in AD diagnostics, we aim-in this study-to develop a baseline trajectory of Cu isotopic composition in the normally aging mouse brain. We determined the copper concentration and isotopic composition in brains of 30 healthy mice (WT) ranging in age from 6 to 12 mo, and further incorporate prior data obtained for 3-mo-old healthy mice; this range approximately equates to 20-50 yr in human equivalency. A significant 65Cu enrichment has been observed in the 12-mo-old mice compared to the youngest group, concomitant with an increase in Cu concentration with age. Meanwhile, literature data for brains of AD mice display an enrichment in 63Cu isotope compared to WT. It is acutely important that this baseline enrichment in 65Cu is fully constrained and normalized against if any coherent diagnostic observations regarding 63Cu enrichment as a biomarker for AD are to be developed.

Copper Metabolism and Cuproptosis: Molecular Mechanisms and Therapeutic Perspectives in Neurodegenerative Diseases

Copper is an essential trace element, and plays a vital role in numerous physiological processes within the human body. During normal metabolism, the human body maintains copper homeostasis. Copper deficiency or excess can adversely affect cellular function. Therefore, copper homeostasis is stringently regulated. Recent studies suggest that copper can trigger a specific form of cell death, namely, cuproptosis, which is triggered by excessive levels of intracellular copper. Cuproptosis induces the aggregation of mitochondrial lipoylated proteins, and the loss of iron-sulfur cluster proteins. In neurodegenerative diseases, the pathogenesis and progression of neurological disorders are linked to copper homeostasis. This review summarizes the advances in copper homeostasis and cuproptosis in the nervous system and neurodegenerative diseases. This offers research perspectives that provide new insights into the targeted treatment of neurodegenerative diseases based on cuproptosis.

Unravelling the complex interplay of cuproptosis, lncRNAs, and immune infiltration in Alzheimer's disease: a step towards novel therapeutic targets

BACKGROUND

Cuproptosis, a type of cell death involving copper ion accumulation and oxidative stress, has been implicated in the development of Alzheimer's disease (AD).

AIM

This study aimed to explore the potential mechanisms and roles of cuproptosis-related genes (CRGs), long non-coding RNAs (lncRNAs), and immune cells in the development of cuproptosis in AD.

SUBJECTS AND METHODS

Gene expression profiles of AD were acquired from the Gene Expression Omnibus (GEO) database, and differential analysis was conducted to identify CRGs. Random Forest (RF) modelling was employed to select the most crucial CRGs, which were subsequently validated in the test set. A nomogram model was created to predict AD risk and categorise AD subtypes based on the identified CRGs. A lncRNA-related ceRNA network was built, and immune cell infiltration analysis was conducted.

RESULTS

Twelve differentially expressed CRGs were identified in the AD dataset. The RF model pinpointed the five most critical CRGs, which were validated in the test set with an AUC of 0.90. A lncRNA-related ceRNA network was developed, and immune cell infiltration analysis revealed high levels of M1 macrophages and mast cells, along with low levels of memory B cells in AD samples. Correlation analysis unveiled associations between CRGs, lncRNAs, and differentially infiltrating immune cells.

CONCLUSION

This research offers insights into the potential mechanisms and roles of CRGs, lncRNAs, and immune cells in the development of cuproptosis in AD. The identified CRGs and lncRNAs may serve as potential therapeutic targets for AD, and the nomogram model may assist in early AD diagnosis and subtyping.

Potential Role of Oxidative Stress in the Pathophysiology of Neurodegenerative Disorders

Neurodegeneration causes premature death in the peripheral and central nervous system. Neurodegeneration leads to the accumulation of oxidative stress, inflammatory responses, and the generation of free radicals responsible for nervous disorders like amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and Huntington's disorders. Therefore, focus must be diverted towards treating and managing these disorders, as it is very challenging. Furthermore, effective therapies are also lacking, so the growing interest of the global market must be inclined towards developing newer therapeutic approaches that can intercept the progression of neurodegeneration. Emerging evidences of research findings suggest that antioxidant therapy has significant potential in modulating disease phenotypes. This makes them promising candidates for further investigation. This review focuses on the role of oxidative stress and reactive oxygen species in the pathological mechanisms of various neurodegenerative diseases, amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and Huntington's disorders and their neuroprotection. Additionally, it highlights the potential of antioxidant-based therapeutics in mitigating disease severity in humans and improving patient compliance. Ongoing extensive global research further sheds light on exploring new therapeutic targets for a deeper understanding of disease mechanisms in the field of medicine and biology targeting neurogenerative disorders.

Exercise combined with postbiotics treatment results in synergistic improvement of mitochondrial function in the brain of male transgenic mice for Alzheimer's disease

BACKGROUND

It has been suggested that exercise training and postbiotic supplement could decelerate the progress of functional and biochemical deterioration in double transgenic mice overexpresses mutated forms of the genes for human amyloid precursor protein (APPsw) and presenilin 1 (m146L) (APP/PS1TG). Our earlier published data indicated that the mice performed better than controls on the Morris Maze Test parallel with decreased occurrence of amyloid-β plaques in the hippocampus. We investigated the neuroprotective and therapeutic effects of high-intensity training and postbiotic supplementation.

METHODS

Thirty-two adult APP/PS1TG mice were randomly divided into four groups: (1) control, (2) high-intensity training (3) postbiotic, (4) combined (training and postbiotic) treatment for 20 weeks. In this study, the whole hemibrain without hippocampus was used to find molecular traits explaining improved brain function. We applied qualitative RT-PCR for gene expression, Western blot for protein level, and Zymography for LONP1 activity. Disaggregation analysis of Aβ-40 was performed in the presence of Lactobacillus acidophilus and Bifidobacterium longum lysate.

RESULTS

We found that exercise training decreased Alzheimer's Disease (AD)-related gene expression (NF-kB) that was not affected by postbiotic treatment. The preparation used for postbiotic treatment is composed of tyndallized Bifidobacterium longum and Lactobacillus acidophilus. Both of the postbiotics effectively disaggregated amyloid-β/Aβ-40 aggregates by chelating Zn2+ and Cu2+ ions. The postbiotic treatment decreased endogenous human APPTG protein expression and mouse APP gene expression in the hemibrains. In addition, the postbiotic treatment elevated mitochondrial LONP1 activity as well.

CONCLUSION

Our findings revealed distinct mechanisms behind improved memory performance in the whole brain: while exercise training modulates NF-kB signaling pathway regulating immune response until postbiotic diminishes APP gene expression, disaggregates pre-existing amyloid-β plaques and activates mitochondrial protein quality control in the region of brain out of hippocampus. Using the above treatments complements and efficiently slows down the development of AD.

Pincer Ligands as Multifunctional Agents for Alzheimer's Copper Dysregulation and Oxidative Stress: A Computational Evaluation

Alzheimer's disease (AD) is the most common form of dementia worldwide, affecting millions of people around the globe. AD is characterized by different pathologies being beta-amyloid (Aβ) plaque formation, metal ion dysregulation, and oxidative stress (OS) central topics under investigation. Copper-Aβ complexes have been shown to induce catalytic hydrogen peroxide formation and increase OS in the brain leading to neuronal death. Pincer-type compounds are tridentate ligands that coordinate metals in a planar fashion whose properties can be tuned via group substitutions, giving rise to many possibilities in catalysis and drug discovery. In this work we evaluated the potential pharmaceutical activity of 26 pincer compounds in AD's copper ion-related oxidative stress framework. In this sense, four key aspects were considered: 1) Lipinski's rule of five, 2) blood-brain barrier permeation, 3) standard reduction potential (SRP) of the formed copper complexes, and 4) the ligand's affinity towards copper cations. The evaluation of these criteria was performed by means of bioinformatic tools and electronic structure calculations at the DFT level of theory. Our results suggest that two compounds from this set are potential antioxidant agents, whereas five of them are promissory distributor-like compounds in the context of AD.

Hexa-Histidine, a Peptide with Versatile Applications in the Study of Amyloid-β(1-42) Molecular Mechanisms of Action

Amyloid β (Aβ) oligomers are the most neurotoxic forms of Aβ, and Aβ(1-42) is the prevalent Aβ peptide found in the amyloid plaques of Alzheimer's disease patients. Aβ(25-35) is the shortest peptide that retains the toxicity of Aβ(1-42). Aβ oligomers bind to calmodulin (CaM) and calbindin-D28k with dissociation constants in the nanomolar Aβ(1-42) concentration range. Aβ and histidine-rich proteins have a high affinity for transition metal ions Cu2+, Fe3+ and Zn2+. In this work, we show that the fluorescence of Aβ(1-42) HiLyteTM-Fluor555 can be used to monitor hexa-histidine peptide (His6) interaction with Aβ(1-42). The formation of His6/Aβ(1-42) complexes is also supported by docking results yielded by the MDockPeP Server. Also, we found that micromolar concentrations of His6 block the increase in the fluorescence of Aβ(1-42) HiLyteTM-Fluor555 produced by its interaction with the proteins CaM and calbindin-D28k. In addition, we found that the His6-tag provides a high-affinity site for the binding of Aβ(1-42) and Aβ(25-35) peptides to the human recombinant cytochrome b5 reductase, and sensitizes this enzyme to inhibition by these peptides. In conclusion, our results suggest that a His6-tag could provide a valuable new tool to experimentally direct the action of neurotoxic Aβ peptides toward selected cellular targets.

Impact of human serum albumin on CuII and ZnII complexation by ATSM (diacetyl-bis(N4-methylthiosemicarbazone)) and a water soluble analogue

The chelator diacetyl-bis(N4-methylthiosemicarbazone) (ATSM) and its complexes with CuII and ZnII are becoming increasingly investigated for medical applications such as PET imaging for anti-tumour therapy and the treatment of amyotrophic lateral sclerosis. However, the solubility in water of both the ligand and the complexes presents certain limitations for in vitro studies. Moreover, the stability of the CuII and ZnII complexes and their metal exchange reaction against the potential biological competitor human serum albumin (HSA) has not been studied in depth. In this work it was observed that the ATSM with an added carboxylic group into the structure increases its solubility in aqueous solutions without altering the coordination mode and the conjugated system of the ligand. The poorly water-soluble CuII- and ZnII-ATSM complexes were prevented from precipitating due to the binding to HSA. Both HSA and ATSM show a similar thermodynamic affinity for ZnII. Finally, the CuII-competition experiments with EDTA and the water-soluble ATSM ligands yielded an apparent log Kd at pH 7.4 of about -19. When ATSM was added to CuII- and ZnII-loaded HSA, withdrawing of ZnII was kinetically favoured, but this metal is slowly substituted by the CuII afterwards taken from HSA so that this protein could be considered as a source of CuII for ATSM.

Oxidative Stress Occurs Prior to Amyloid Aβ Plaque Formation and Tau Phosphorylation in Alzheimer's Disease: Role of Glutathione and Metal Ions

Alzheimer's disease (AD) is an insidious and progressive neurodegenerative disorder that affects millions of people worldwide. Although the pathogenesis remains obscure, there are two dominant causal hypotheses. Since last three decades, amyloid beta (Aβ) deposition was the most prominent hypothesis, and the other is the tau hyperphosphorylation hypothesis. The confirmed diagnostic criterion for AD is the presence of neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau and the deposition of toxic oligomeric Aβ in the autopsied brain. Consistent with these hypotheses, oxidative stress (OS) is garnering major attention in AD research. OS results from an imbalance of pro-oxidants and antioxidants. There is a considerable debate in the scientific community on which process occurs first, OS or plaque deposition/tau hyperphosphorylation. Based on recent scientific observations of various laboratories including ours along with critical analysis of those information, we believe that OS is the early event that leads to oligomeric Aβ deposition as well as dimerization of tau protein and its subsequent hyperphosphorylation. This OS hypothesis immediately suggests the consideration of novel therapeutic approaches to include antioxidants involving glutathione enrichment in the brain by supplementation with or without an iron chelator.

A bibliometric analysis of cerebral microbleeds and cognitive impairment

BACKGROUND AND OBJECTIVES

Cerebral microbleeds (CMBs) are imaging markers for small cerebral vascular diseases, which can accumulate and impact the corresponding brain networks. CMBs can affect cognitive function, including executive function, information processing speed, and visuospatial memory. Bibliometrics is a scientific and innovative method that can analyze and visualize the scientific field quantitatively. In this study, we aimed to use bibliometric analysis to demonstrate the relationship and mechanisms between CMBs and cognitive impairment. Furthermore, we reviewed the relationship between CMBs and different cognitive disorders. The use of bibliometrics can help further clarify this relationship.

METHODS

We retrieved articles on CMBs and cognitive impairment from the Web of Science Core Collection. The keywords (such as stroke, dementia, and cerebral amyloid angiopathy), authors, countries, institutions and journals, in the field were visually analyzed using VOSviewer software and bibliometric websites.

RESULTS

This bibliometric analysis reveals the related trends of CMBs in the field of cognitive impairment. CMBs, along with other small vascular lesions, constitute the basis of cognitive impairment, and studying CMBs is essential to understand the mechanisms underlying cognitive impairment.

CONCLUSION

This bibliometric analysis reveals a strong link between CMBs and cognitive impairment-related diseases and that specific brain networks were affected by CMBs. This provides further insights into the possible mechanisms and causes of CMBs and cognitive impairment. The direct and indirect damage (such as oxidative stress and neuroinflammation) to the brain caused by CMBs, destruction of the frontal-subcortical circuits, elevated Cystatin C levels, and iron deposition are involved in the occurrence and development of cognitive impairment. CMBs may be a potential marker for detecting, quantifying, and predicting cognitive impairment.

An Electrochemistry and Computational Study at an Electrified Liquid-Liquid Interface for Studying Beta-Amyloid Aggregation

Amphiphilic peptides, such as Aß amyloids, can adsorb at an interface between two immiscible electrolyte solutions (ITIES). Based on previous work (vide infra), a hydrophilic/hydrophobic interface is used as a simple biomimetic system for studying drug interactions. The ITIES provides a 2D interface to study ion-transfer processes associated with aggregation, as a function of Galvani potential difference. Here, the aggregation/complexation behaviour of Aβ_(1-42) is studied in the presence of Cu (II) ions, together with the effect of a multifunctional peptidomimetic inhibitor (P6). Cyclic and differential pulse voltammetry proved to be particularly sensitive to the detection of the complexation and aggregation of Aβ_(1-42), enabling estimations of changes in lipophilicity upon binding to Cu (II) and P6. At a 1:1 ratio of Cu (II):Aβ_(1-42), fresh samples showed a single DPV (Differential Pulse Voltammetry) peak half wave transfer potential (E1/2) at 0.40 V. Upon increasing the ratio of Cu (II) two-fold, fluctuations were observed in the DPVs, indicating aggregation. The approximate stoichiometry and binding properties of Aβ_(1-42) during complexation with Cu (II) were determined by performing a differential pulse voltammetry (DPV) standard addition method, which showed two binding regimes. A pKa of 8.1 was estimated, with a Cu:Aβ_1-42 ratio~1:1.7. Studies using molecular dynamics simulations of peptides at the ITIES show that Aβ_(1-42) strands interact through the formation of β-sheet stabilised structures. In the absence of copper, binding/unbinding is dynamic, and interactions are relatively weak, leading to the observation of parallel and anti-parallel arrangements of β-sheet stabilised aggregates. In the presence of copper ions, strong binding occurs between a copper ion and histidine residues on two peptides. This provides a convenient geometry for inducing favourable interactions between folded β-sheet structures. Circular Dichroism spectroscopy (CD spectroscopy) was used to support the aggregation behaviour of the Aβ_(1-42) peptides following the addition of Cu (II) and P6 to the aqueous phase.

Anti-Aβ42 Aggregative Polyketides from the Antarctic Psychrophilic Fungus Pseudogymnoascus sp. OUCMDZ-3578

Seven new polyketides, diphenyl ketone (1), diphenyl ketone glycosides (2-4), diphenyl ketone-diphenyl ether dimer (6), and anthraquinone-diphenyl ketone dimers (7 and 8), together with compound 5, were isolated from the psychrophilic fungus Pseudogymnoascus sp. OUCMDZ-3578 fermented at 16 °C and identified by spectroscopic analysis. The absolute configurations of 2-4 were determined by acid hydrolysis and 1-phenyl-3-methyl-5-pyrazolone precolumn derivatization. The configuration of 5 was first determined by X-ray diffraction analysis. Compounds 6 and 8 showed the highest activity against amyloid beta (Aβ₄₂) aggregation with half-maximal inhibitory concentrations (IC₅₀) of 0.10 and 0.18 μM, respectively. They also showed strong abilities to chelate with metal ions, especially iron, were sensitive to Aβ₄₂ aggregation induced by metal ions, and displayed depolymerizing activity. Compounds 6 and 8 show potential as leads for the treatment of Alzheimer's disease to prevent Aβ₄₂ aggregation.

The Role of Heme and Copper in Alzheimer's Disease and Type 2 Diabetes Mellitus

Beyond the well-explored proposition of protein aggregation or amyloidosis as the central event in amyloidogenic diseases like Alzheimer's Disease (AD), and Type 2 Diabetes Mellitus (T2Dm); there are alternative hypotheses, now becoming increasingly evident, which suggest that the small biomolecules like redox noninnocent metals (Fe, Cu, Zn, etc.) and cofactors (Heme) have a definite influence in the onset and extent of such degenerative maladies. Dyshomeostasis of these components remains as one of the common features in both AD and T2Dm etiology. Recent advances in this course reveal that the metal/cofactor-peptide interactions and covalent binding can alarmingly enhance and modify the toxic reactivities, oxidize vital biomolecules, significantly contribute to the oxidative stress leading to cell apoptosis, and may precede the amyloid fibrils formation by altering their native folds. This perspective highlights this aspect of amyloidogenic pathology which revolves around the impact of the metals and cofactors in the pathogenic courses of AD and T2Dm including the active site environments, altered reactivities, and the probable mechanisms involving some highly reactive intermediates as well. It also discusses some in vitro metal chelation or heme sequestration strategies which might serve as a possible remedy. These findings might open up a new paradigm in our conventional understanding of amyloidogenic diseases. Moreover, the interaction of the active sites with small molecules elucidates potential biochemical reactivities that can inspire designing of drug candidates for such pathologies.

Regulation of beta-amyloid for the treatment of Alzheimer's disease: Research progress of therapeutic strategies and bioactive compounds

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is difficult to treat. Extracellular amyloid is the principal pathological criterion for the diagnosis of AD. Amyloid β (Aβ) interacts with various receptor molecules on the plasma membrane and mediates a series of signaling pathways that play a vital role in the occurrence and development of AD. Research on receptors that interact with Aβ is currently ongoing. Overall, there are no effective medications to treat AD. In this review, we first discuss the importance of Aβ in the pathogenesis of AD, then summarize the latest progress of Aβ-related targets and compounds. Finally, we put forward the challenges and opportunities in the development of effective AD therapies.

Concentration Effect, Structural Properties, and Driving Force on Aβ28 Dimerization with and without Zn2+ Cooperation: Learning from Replica Exchange Sampling

Zn²⁺ is a very important factor in promoting the formation of amyloid beta (Aβ) aggregates and amyloid plaques. The Zn²⁺ -bound Aβ species generate amorphous or low molecular-weight oligomers. However, it is a lack of studies to approach the starting structural features (dimerization) in Aβ nucleation processes with and without Zn²⁺ , which is the key point in understanding Zn²⁺ -induced nucleation mechanisms. To better understand the effect of concentration, structural properties, and the driving force, 14 independent replica exchange molecular dynamics simulations were performed in Aβ₂₈ dimerization with and without Zn²⁺ (zAβ₂₈ ) cooperation. Our scanning results show that the aggregation propensity is easier in Aβ₂₈ -Aβ₂₈ and Aβ₂₈ -zAβ₂₈ systems than zAβ₂₈ -zAβ₂₈ system. In binding property, the Aβ₂₈ -Aβ₂₈ model (-61.5 kcal mol^-1 ) is stronger than zAβ₂₈ -zAβ₂₈ (-26.6 kcal mol^-1 ) and Aβ₂₈ -zAβ₂₈ (-7.24 kcal mol^-1 ) models. Further analysis confirmed that H13 and H14 residues play specific roles in the three systems. The key point is the orientation of N atom of the imidazole ring in histidine residues. Furthermore, we discovered different driving forces for each system. Our current study contributes to the understanding of how the Aβ₂₈ dimer interacts with Zn²⁺ , which could lead to new insights into Zn²⁺ -induced nucleation mechanisms.

Alleviating the unwanted effects of oxidative stress on Aβ clearance: a review of related concepts and strategies for the development of computational modelling

Treatment for Alzheimer's disease (AD) can be more effective in the early stages. Although we do not completely understand the aetiology of the early stages of AD, potential pathological factors (amyloid beta [Aβ] and tau) and other co-factors have been identified as causes of AD, which may indicate some of the mechanism at work in the early stages of AD. Today, one of the primary techniques used to help delay or prevent AD in the early stages involves alleviating the unwanted effects of oxidative stress on Aβ clearance. 4-Hydroxynonenal (HNE), a product of lipid peroxidation caused by oxidative stress, plays a key role in the adduction of the degrading proteases. This HNE employs a mechanism which decreases catalytic activity. This process ultimately impairs Aβ clearance. The degradation of HNE-modified proteins helps to alleviate the unwanted effects of oxidative stress. Having a clear understanding of the mechanisms associated with the degradation of the HNE-modified proteins is essential for the development of strategies and for alleviating the unwanted effects of oxidative stress. The strategies which could be employed to decrease the effects of oxidative stress include enhancing antioxidant activity, as well as the use of nanozymes and/or specific inhibitors. One area which shows promise in reducing oxidative stress is protein design. However, more research is needed to improve the effectiveness and accuracy of this technique. This paper discusses the interplay of potential pathological factors and AD. In particular, it focuses on the effect of oxidative stress on the expression of the Aβ-degrading proteases through adduction of the degrading proteases caused by HNE. The paper also elucidates other strategies that can be used to alleviate the unwanted effects of oxidative stress on Aβ clearance. To improve the effectiveness and accuracy of protein design, we explain the application of quantum mechanical/molecular mechanical approach.

The Neuroprotective Activities of the Novel Multi-Target Iron-Chelators in Models of Alzheimer's Disease, Amyotrophic Lateral Sclerosis and Aging

The concept of chelation therapy as a valuable therapeutic approach in neurological disorders led us to develop multi-target, non-toxic, lipophilic, brain-permeable compounds with iron chelation and anti-apoptotic properties for neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD), age-related dementia and amyotrophic lateral sclerosis (ALS). Herein, we reviewed our two most effective such compounds, M30 and HLA20, based on a multimodal drug design paradigm. The compounds have been tested for their mechanisms of action using animal and cellular models such as APP/PS1 AD transgenic (Tg) mice, G93A-SOD1 mutant ALS Tg mice, C57BL/6 mice, Neuroblastoma × Spinal Cord-34 (NSC-34) hybrid cells, a battery of behavior tests, and various immunohistochemical and biochemical techniques. These novel iron chelators exhibit neuroprotective activities by attenuating relevant neurodegenerative pathology, promoting positive behavior changes, and up-regulating neuroprotective signaling pathways. Taken together, these results suggest that our multifunctional iron-chelating compounds can upregulate several neuroprotective-adaptive mechanisms and pro-survival signaling pathways in the brain and might function as ideal drugs for neurodegenerative disorders, such as PD, AD, ALS, and aging-related cognitive decline, in which oxidative stress and iron-mediated toxicity and dysregulation of iron homeostasis have been implicated.

How Can Insulin Resistance Cause Alzheimer's Disease?

Alzheimer's disease (AD) is a neurodegenerative disorder associated with cognitive decline. Despite worldwide efforts to find a cure, no proper treatment has been developed yet, and the only effective countermeasure is to prevent the disease progression by early diagnosis. The reason why new drug candidates fail to show therapeutic effects in clinical studies may be due to misunderstanding the cause of AD. Regarding the cause of AD, the most widely known is the amyloid cascade hypothesis, in which the deposition of amyloid beta and hyperphosphorylated tau is the cause. However, many new hypotheses were suggested. Among them, based on preclinical and clinical evidence supporting a connection between AD and diabetes, insulin resistance has been pointed out as an important factor in the development of AD. Therefore, by reviewing the pathophysiological background of brain metabolic insufficiency and insulin insufficiency leading to AD pathology, we will discuss how can insulin resistance cause AD.

Revisiting the Role of Vitamins and Minerals in Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of dementia that affects millions of individuals worldwide. It is an irreversible neurodegenerative disorder that is characterized by memory loss, impaired learning and thinking, and difficulty in performing regular daily activities. Despite nearly two decades of collective efforts to develop novel medications that can prevent or halt the disease progression, we remain faced with only a few options with limited effectiveness. There has been a recent growth of interest in the role of nutrition in brain health as we begin to gain a better understanding of what and how nutrients affect hormonal and neural actions that not only can lead to typical cardiovascular or metabolic diseases but also an array of neurological and psychiatric disorders. Vitamins and minerals, also known as micronutrients, are elements that are indispensable for functions including nutrient metabolism, immune surveillance, cell development, neurotransmission, and antioxidant and anti-inflammatory properties. In this review, we provide an overview on some of the most common vitamins and minerals and discuss what current studies have revealed on the link between these essential micronutrients and cognitive performance or AD.

Current understanding of metal-dependent amyloid-β aggregation and toxicity

The discovery of effective therapeutics targeting amyloid-β (Aβ) aggregates for Alzheimer's disease (AD) has been very challenging, which suggests its complicated etiology associated with multiple pathogenic elements. In AD-affected brains, highly concentrated metals, such as copper and zinc, are found in senile plaques mainly composed of Aβ aggregates. These metal ions are coordinated to Aβ and affect its aggregation and toxicity profiles. In this review, we illustrate the current view on molecular insights into the assembly of Aβ peptides in the absence and presence of metal ions as well as the effect of metal ions on their toxicity.

Evaluation of Copper Chelation Therapy in a Transgenic Rat Model of Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is characterized by the accumulation of the amyloid β (Aβ) protein in blood vessels and leads to hemorrhages, strokes, and dementia in elderly individuals. Recent reports have shown elevated copper levels colocalized with vascular amyloid in human CAA and Alzheimer's disease patients, which have been suggested to contribute to cytotoxicity through the formation of reactive oxygen species. Here, we treated a transgenic rat model of CAA (rTg-DI) with the copper-specific chelator, tetrathiomolybdate (TTM), via intraperitoneal (IP) administration for 6 months to determine if it could lower copper content in vascular amyloid deposits and modify CAA pathology. Results showed that TTM treatment led to elevated Aβ load in the hippocampus of the rTg-DI rats and increased microbleeds in the wild type (WT) animals. X-ray fluorescence microscopy was performed to image the distribution of copper and revealed a surprising increase in copper colocalized with Aβ aggregates in TTM-treated rTg-DI rats. Unexpectedly, we also found an increase in the copper content in unaffected vessels of both rTg-DI and WT animals. These results show that IP administration of TTM was ineffective in removing copper from vascular Aβ aggregates in vivo and increased the development of disease pathology in CAA.

Synthetic, Cell-Derived, Brain-Derived, and Recombinant β-Amyloid: Modelling Alzheimer's Disease for Research and Drug Development

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, characterised by the accumulation of senile plaques and tau tangles, neurodegeneration, and neuroinflammation in the brain. The development of AD is a pathological cascade starting according to the amyloid hypothesis with the accumulation and aggregation of the β-amyloid peptide (Aβ), which induces hyperphosphorylation of tau and promotes the pro-inflammatory activation of microglia leading to synaptic loss and, ultimately, neuronal death. Modelling AD-related processes is important for both studying the molecular basis of the disease and the development of novel therapeutics. The replication of these processes is often achieved with the use of a purified Aβ peptide. However, Aβ preparations obtained from different sources can have strikingly different properties. This review aims to compare the structure and biological effects of Aβ oligomers and aggregates of a higher order: synthetic, recombinant, purified from cell culture, or extracted from brain tissue. The authors summarise the applicability of Aβ preparations for modelling Aβ aggregation, neurotoxicity, cytoskeleton damage, receptor toxicity in vitro and cerebral amyloidosis, synaptic plasticity disruption, and cognitive impairment in vivo and ex vivo. Further, the paper discusses the causes of the reported differences in the effect of Aβ obtained from the sources mentioned above. This review points to the importance of the source of Aβ for AD modelling and could help researchers to choose the optimal way to model the Aβ-induced abnormalities.

Brain copper may protect from cognitive decline and Alzheimer's disease pathology: a community-based study

Copper is an essential micronutrient for brain health and dyshomeostasis of copper could have a pathophysiological role in Alzheimer's disease (AD), however, there are limited data from community-based samples. In this study, we investigate the association of brain copper (assessed using ICP-MS in four regions -inferior temporal, mid-frontal, anterior cingulate, and cerebellum) and dietary copper with cognitive decline and AD pathology burden (a quantitative summary of neurofibrillary tangles, diffuse and neuritic plaques in multiple brain regions) at autopsy examination among deceased participants (N = 657; age of death: 90.2(±6.2)years, 70% women, 25% APOE-ɛ4 carriers) in the Rush Memory and Aging Project. During annual visits, these participants completed cognitive assessments using a 19-test battery and dietary assessments (using a food frequency questionnaire). Regression, linear mixed-effects, and logistic models adjusted for age at death, sex, education, and APOE-ε4 status were used. Higher composite brain copper levels were associated with slower cognitive decline (β(SE) = 0.028(0.01), p = 0.001) and less global AD pathology (β(SE) = -0.069(0.02), p = 0.0004). Participants in the middle and highest tertile of dietary copper had slower cognitive decline (T2vs.T1: β = 0.038, p = 0.0008; T3vs.T1: β = 0.028, p = 0.01) than those in the lowest tertile. Dietary copper intake was not associated with brain copper levels or AD pathology. Associations of higher brain copper levels with slower cognitive decline and with less AD pathology support a role for copper dyshomeostasis in AD pathogenesis and suggest that lower brain copper may exacerbate or indicate disease severity. Dietary and brain copper are unrelated but dietary copper is associated with slower cognitive decline via an unknown mechanism.

Alzheimer's Drug PBT2 Interacts with the Amyloid β 1-42 Peptide Differently than Other 8-Hydroxyquinoline Chelating Drugs

Although Alzheimer's disease (AD) was first described over a century ago, it remains the leading cause of age-related dementia. Innumerable changes have been linked to the pathology of AD; however, there remains much discord regarding which might be the initial cause of the disease. The "amyloid cascade hypothesis" proposes that the amyloid β (Aβ) peptide is central to disease pathology, which is supported by elevated Aβ levels in the brain before the development of symptoms and correlations of amyloid burden with cognitive impairment. The "metals hypothesis" proposes a role for metal ions such as iron, copper, and zinc in the pathology of AD, which is supported by the accumulation of these metals within amyloid plaques in the brain. Metals have been shown to induce aggregation of Aβ, and metal ion chelators have been shown to reverse this reaction in vitro. 8-Hydroxyquinoline-based chelators showed early promise as anti-Alzheimer's drugs. Both 5-chloro-7-iodo-8-hydroxyquinoline (CQ) and 5,7-dichloro-2-[(dimethylamino)methyl]-8-hydroxyquinoline (PBT2) underwent unsuccessful clinical trials for the treatment of AD. To gain insight into the mechanism of action of 8HQs, we have investigated the potential interaction of CQ, PBT2, and 5,7-dibromo-8-hydroxyquinoline (B2Q) with Cu(II)-bound Aβ(1-42) using X-ray absorption spectroscopy (XAS), high energy resolution fluorescence detected (HERFD) XAS, and electron paramagnetic resonance (EPR). By XAS, we found CQ and B2Q sequestered ∼83% of the Cu(II) from Aβ(1-42), whereas PBT2 sequestered only ∼59% of the Cu(II) from Aβ(1-42), suggesting that CQ and B2Q have a higher relative Cu(II) affinity than PBT2. From our EPR, it became clear that PBT2 sequestered Cu(II) from a heterogeneous mixture of Cu(II)Aβ(1-42) species in solution, leaving a single Cu(II)Aβ(1-42) species. It follows that the Cu(II) site in this Cu(II)Aβ(1-42) species is inaccessible to PBT2 and may be less solvent-exposed than in other Cu(II)Aβ(1-42) species. We found no evidence to suggest that these 8HQs form ternary complexes with Cu(II)Aβ(1-42).

Novel Anti-Neuroinflammatory Properties of a Thiosemicarbazone–Pyridylhydrazone Copper(II) Complex

Neuroinflammation has a major role in several brain disorders including Alzheimer’s disease (AD), yet at present there are no effective anti-neuroinflammatory therapeutics available. Copper(II) complexes of bis(thiosemicarbazones) (Cu^II(gtsm) and Cu^II(atsm)) have broad therapeutic actions in preclinical models of neurodegeneration, with Cu^II(atsm) demonstrating beneficial outcomes on neuroinflammatory markers in vitro and in vivo. These findings suggest that copper(II) complexes could be harnessed as a new approach to modulate immune function in neurodegenerative diseases. In this study, we examined the anti-neuroinflammatory action of several low-molecular-weight, charge-neutral and lipophilic copper(II) complexes. Our analysis revealed that one compound, a thiosemicarbazone–pyridylhydrazone copper(II) complex (CuL⁵), delivered copper into cells in vitro and increased the concentration of copper in the brain in vivo. In a primary murine microglia culture, CuL⁵ was shown to decrease secretion of pro-inflammatory cytokine macrophage chemoattractant protein 1 (MCP-1) and expression of tumor necrosis factor alpha (Tnf), increase expression of metallothionein (Mt1), and modulate expression of Alzheimer’s disease-associated risk genes, Trem2 and Cd33. CuL⁵ also improved the phagocytic function of microglia in vitro. In 5xFAD model AD mice, treatment with CuL⁵ led to an improved performance in a spatial working memory test, while, interestingly, increased accumulation of amyloid plaques in treated mice. These findings demonstrate that CuL⁵ can induce anti-neuroinflammatory effects in vitro and provide selective benefit in vivo. The outcomes provide further support for the development of copper-based compounds to modulate neuroinflammation in brain diseases.

Aβ and Tau Interact with Metal Ions, Lipid Membranes and Peptide-Based Amyloid Inhibitors: Are These Common Features Relevant in Alzheimer’s Disease?

In the last two decades, the amyloid hypothesis, i.e., the abnormal accumulation of toxic Aβ assemblies in the brain, has been considered the mainstream concept sustaining research in Alzheimer’s Disease (AD). However, the course of cognitive decline and AD development better correlates with tau accumulation rather than amyloid peptide deposition. Moreover, all clinical trials of amyloid-targeting drug candidates have been unsuccessful, implicitly suggesting that the amyloid hypothesis needs significant amendments. Accumulating evidence supports the existence of a series of potentially dangerous relationships between Aβ oligomeric species and tau protein in AD. However, the molecular determinants underlying pathogenic Aβ/tau cross interactions are not fully understood. Here, we discuss the common features of Aβ and tau molecules, with special emphasis on: (i) the critical role played by metal dyshomeostasis in promoting both Aβ and tau aggregation and oxidative stress, in AD; (ii) the effects of lipid membranes on Aβ and tau (co)-aggregation at the membrane interface; (iii) the potential of small peptide-based inhibitors of Aβ and tau misfolding as therapeutic tools in AD. Although the molecular mechanism underlying the direct Aβ/tau interaction remains largely unknown, the arguments discussed in this review may help reinforcing the current view of a synergistic Aβ/tau molecular crosstalk in AD and stimulate further research to mechanism elucidation and next-generation AD therapeutics.

Copper ions, prion protein and Aβ modulate Ca levels in central nervous system myelin in an NMDA receptor-dependent manner

As in neurons, CNS myelin expresses N-Methyl-D-Aspartate Receptors (NMDARs) that subserve physiological roles, but have the potential to induce injury to this vital element. Using 2-photon imaging of myelinic Ca in live ex vivo mouse optic nerves, we show that Cu ions potently modulate Ca levels in an NMDAR-dependent manner. Chelating Cu in the perfusate induced a substantial increase in Ca levels, and also caused significant axo-myelinic injury. Myelinic NMDARs are shown to be regulated by cellular prion protein; only in prion protein KO optic nerves does application of NMDA + D-serine induce a large Ca increase, consistent with strong desensitization of these receptors in the presence of prion protein limiting Ca overload. Aβ_1-42 peptide induced a large Ca increase that was also Cu-dependent, and was blocked by NMDAR antagonism. Our results indicate that like in neurons, myelinic NMDARs permeate potentially injurious amounts of Ca, and are also potently regulated by micromolar Cu and activated by Aβ_1-42 peptides. These findings shed mechanistic light on the important primary white matter injury frequently observed in Alzheimer's brain.

Alzheimer's Disease Association with Metals and Metalloids Concentration in Blood and Urine

As there is some evidence that the risk for Alzheimer’s disease (AD) is partially attributable to environmental exposure to some metals and metalloids, we examined an association between AD and arsenic, chromium, and selenium in 53 AD patients and 217 controls. Urinary arsenic, blood chromium, and selenium were determined by inductively coupled plasma mass spectrometry. Logistic regression models calculating odds ratios (ORs) and 95% confidence intervals (CI) were used to estimate AD association with arsenic, chromium, and selenium. In AD patients, urinary arsenic and blood chromium were significantly higher, while blood selenium was significantly lower compared to controls. Increased blood selenium was related to a significant decrease in the odds of AD after adjustment for risk factors. Blood selenium per 1 kg × 10⁻⁹/m³ × 10⁻⁴ increment was associated with 1.4 times lower risk of AD (OR = 0.71; 95% CI 0.58–0.87). A significant increase in the odds of AD associated with increased blood chromium was also seen in the adjusted model: the OR per 1 kg × 10⁻⁹/m³ × 10⁻³ chromium increment was 2.39 (95% CI 1.32–4.31). The association of urinary arsenic with the risk of AD was not significant. The data obtained provide evidence that selenium reduces the risk of Alzheimer’s disease, while chromium increases it.

Estropause, Sex Hormones and Metal Homeostasis in the Mouse Brain

Alterations in brain metal ion homeostasis have been reported with aging and are implicated in the pathogenesis of neurodegenerative diseases. To assess whether age-related changes in hypothalamic-pituitary-gonadal (HPG) hormones might be involved in modulating brain metal ion homeostasis, we treated 7.5-month intact, sham-ovariecomized and ovariectomized C57B6SJL mice with vehicle or leuprolide acetate (for 9-months) to differentiate between whether sex steroids or gonadotropins might modulate brain metal ion concentrations. Unlike other aging mammals, there was no increase in plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations following estropause in mice, suggesting there was sufficient residual production by the follicle depleted ovary, of sex steroids like estrogens and protein hormones like the inhibins, in order to suppress pituitary LH/FSH production. Castration on the other hand induced significant increases in circulating LH and FSH. Modulation of plasma sex steroid and gonadotropin levels did not significantly alter the concentrations of brain metals tested (Fe, Zn, Cu, Mn, Co, Ni, Al, Li), although there was a tendency for a decrease in all brain metals following ovariectomy (low estrogens and progesterone, high gonadotropins), a response that was reversed with leuprolide acetate treatment (low sex steroids, low gonadotropins). Brain Cu concentration was the only metal correlated with plasma LH (−0.37, n = 30, p < 0.05) and FSH (−0.42, n = 29, p < 0.01). This study demonstrates that sex hormones do not markedly alter brain metal ion homeostasis, unlike previously reported studies of circulating metal ion homeostasis. The role of gonadotropins in regulating metal ion homeostasis does however warrant further study.

Nutrient-sensing amyloid metastasis

Amyloids are organized suprastructural polypeptide arrangements. The prevalence of amyloid-related processes of pathophysiological relevance has been linked to aging-related degenerative diseases. Besides the role of genetic polymorphisms on the relative risk of amyloid diseases, the contributions of nongenetic ontogenic cluster of factors remain elusive. In recent decades, mounting evidences have been suggesting the role of essential micronutrients, in particular transition metals, in the regulation of amyloidogenic processes, both directly (such as binding to amyloid proteins) or indirectly (such as regulating regulatory partners, processing enzymes, and membrane transporters). The features of transition metals as regulatory cofactors of amyloid proteins and the consequences of metal dyshomeostasis in triggering amyloidogenic processes, as well as the evidences showing amelioration of symptoms by dietary supplementation, suggest an exaptative role of metals in regulating amyloid pathways. The self- and cross-talk replicative nature of these amyloid processes along with their systemic distribution support the concept of their metastatic nature. The role of amyloidosis as nutrient sensors would act as intra- and transgenerational epigenetic metabolic programming factors determining health span and life span, viability, which could participate as an evolutive selective pressure.

Second Sphere Interactions in Amyloidogenic Diseases

Amyloids are protein aggregates bearing a highly ordered cross β structural motif, which may be functional but are mostly pathogenic. Their formation, deposition in tissues and consequent organ dysfunction is the central event in amyloidogenic diseases. Such protein aggregation may be brought about by conformational changes, and much attention has been directed toward factors like metal binding, post-translational modifications, mutations of protein etc., which eventually affect the reactivity and cytotoxicity of the associated proteins. Over the past decade, a global effort from different groups working on these misfolded/unfolded proteins/peptides has revealed that the amino acid residues in the second coordination sphere of the active sites of amyloidogenic proteins/peptides cause changes in H-bonding pattern or protein-protein interactions, which dramatically alter the structure and reactivity of these proteins/peptides. These second sphere effects not only determine the binding of transition metals and cofactors, which define the pathology of some of these diseases, but also change the mechanism of redox reactions catalyzed by these proteins/peptides and form the basis of oxidative damage associated with these amyloidogenic diseases. The present review seeks to discuss such second sphere modifications and their ramifications in the etiopathology of some representative amyloidogenic diseases like Alzheimer's disease (AD), type 2 diabetes mellitus (T2Dm), Parkinson's disease (PD), Huntington's disease (HD), and prion diseases.

Copper-Mediated β-Amyloid Toxicity and its Chelation Therapy in Alzheimer's Disease

The link between bio-metals, Alzheimer's disease (AD), and its associated protein, amyloid-β (Aβ) is very complex and one of the most studied aspects currently. Alzheimer's disease, a progressive neurodegenerative disease, is proposed to occurs due to the misfolding and aggregation of Aβ. Dyshomeostasis of metal ions and their interaction with Aβ has largely been implicated in AD. Copper plays a crucial role in amyloid-β toxicity and AD development potentially occurs through direct interaction with the copper-binding motif of APP and different amino acid residues of Aβ. Previous reports suggest that high levels of copper accumulation in the AD brain result in modulation of toxic Aβ peptide levels, implicating the role of copper in the pathophysiology of AD. In this review, we explore the possible mode of copper ion interaction with Aβ which accelerates the kinetics of fibril formation and promote amyloid-β mediated cell toxicity in Alzheimer's disease and the potential use of various copper chelators in the prevention of copper-mediated Aβ toxicity.

Physical Exercise, a Potential Non-Pharmacological Intervention for Attenuating Neuroinflammation and Cognitive Decline in Alzheimer's Disease Patients

This narrative review summarises the evidence for considering physical exercise (PE) as a non-pharmacological intervention for delaying cognitive decline in patients with Alzheimer’s disease (AD) not only by improving cardiovascular fitness but also by attenuating neuroinflammation. Ageing is the most important risk factor for AD. A hallmark of the ageing process is a systemic low-grade chronic inflammation that also contributes to neuroinflammation. Neuroinflammation is associated with AD, Parkinson’s disease, late-onset epilepsy, amyotrophic lateral sclerosis and anxiety disorders. Pharmacological treatment of AD is currently limited to mitigating the symptoms and attenuating progression of the disease. AD animal model studies and human studies on patients with a clinical diagnosis of different stages of AD have concluded that PE attenuates cognitive decline not only by improving cardiovascular fitness but possibly also by attenuating neuroinflammation. Therefore, low-grade chronic inflammation and neuroinflammation should be considered potential modifiable risk factors for AD that can be attenuated by PE. This opens the possibility for personalised attenuation of neuroinflammation that could also have important health benefits for patients with other inflammation associated brain disorders (i.e., Parkinson’s disease, late-onset epilepsy, amyotrophic lateral sclerosis and anxiety disorders). In summary, life-long, regular, structured PE should be considered as a supplemental intervention for attenuating the progression of AD in human. Further studies in human are necessary to develop optimal, personalised protocols, adapted to the progression of AD and the individual’s mental and physical limitations, to take full advantage of the beneficial effects of PE that include improved cardiovascular fitness, attenuated systemic inflammation and neuroinflammation, stimulated brain Aβ peptides brain catabolism and brain clearance.