Copper-2 Hypothesis for Causation of the Current Alzheimer's Disease Epidemic Together with Dietary Changes That Enhance the Epidemic

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.

Dietary Trace Elements and the Pathogenesis of Neurodegenerative Diseases

Trace elements such as iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) are absorbed from food via the gastrointestinal tract, transported into the brain, and play central roles in normal brain functions. An excess of these trace elements often produces reactive oxygen species and damages the brain. Moreover, increasing evidence suggests that the dyshomeostasis of these metals is involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, prion diseases, and Lewy body diseases. The disease-related amyloidogenic proteins can regulate metal homeostasis at the synapses, and thus loss of the protective functions of these amyloidogenic proteins causes neurodegeneration. Meanwhile, metal-induced conformational changes of the amyloidogenic proteins contribute to enhancing their neurotoxicity. Moreover, excess Zn and Cu play central roles in the pathogenesis of vascular-type senile dementia. Here, we present an overview of the intake, absorption, and transport of four essential elements (Fe, Zn, Cu, Mn) and one non-essential element (aluminum: Al) in food and their connections with the pathogenesis of neurodegenerative diseases based on metal-protein, and metal-metal cross-talk.

Correlation between copper speciation and transport pathway in Caco-2 cells

BACKGROUND

Previous studies have demonstrated that, in contrast to the properties of food-derived copper, water-derived copper exerts neurotoxic effects and exhibits different speciation during digestion. The cellular uptake efficiencies of different speciation of copper are distinct. However, it is unclear whether these different speciation share the same transport pathway in intestinal epithelial cells. In the present study, the intracellular accumulation of copper derived from copper ion and copper complex solutions was investigated in Caco-2 cells.

RESULTS

The cellular accumulation of copper derived from copper ions was higher than that of copper derived from the copper complex. Treatment with carboplatin and Ag⁺ , which are copper transporter receptor 1 (Ctr1, LC31A1) inhibitors, did not inhibit copper accumulation in Caco-2 cells, but inhibited copper accumulation in HepG2 cells. Zinc ion significantly decreased the intracellular copper content from 114 ± 7 μg g^-1 protein to 88 ± 4 μg g^-1 protein in the copper ion-treated Caco-2 cells, but not in the copper complex-treated Caco-2 cells (84.6 ± 14 μg g^-1 protein versus 87.7 ± 20 μg g^-1 protein, P > 0.05). Additionally, copper accumulation in Caco-2 and HepG2 cells significantly differed depending on different solvents (Hanks' balanced salt solution and NaNO₃ , P < 0.05).

CONCLUSION

These results indicate that the intracellular accumulation of copper derived from copper ion and copper complex is mediated by distinct copper transport pathways. Copper speciation may be an important factor that affects copper absorption and toxicity. © 2022 Society of Chemical Industry.

D-ribose-L-cysteine reduces oxidative stress and inflammatory cytokines to mitigate liver damage, and memory decline induced by copper sulfate in mice

BACKGROUND

Current evidences have implicated copper in amyloid aggregation that trigger the downstream oxidative stress-mediated neuroinflammation that characterized memory deterioration in patients with Alzheimer's disease (AD). Thus, this study was designed to evaluate the effect of D-Ribose-L-Cysteine (DRLC), a potent antioxidant agent, on copper sulfate (CuSO₄)-induced memory deterioration and the biochemical mechanisms underpinning its action in mice.

METHODS

Male Swiss mice were randomly distributed into 5 groups (n = 10/group). Mice in group 1 were given distilled water (control), group 2 CuSO₄ (100 mg/kg) while groups 3-5 were pretreated with CuSO₄ (100 mg/kg) 30 min before administration of DRLC (10, 25 and 50 mg/kg). Treatments were given through oral gavage, daily for 28 days. Memory function was evaluated on day 28 using Y-maze test. The isolated liver and brain tissues were then processed for oxidative stress biomarkers, and proinflammatory cytokines [tumor necrosis factor- α (TNF-α) and interleukin-6)] assays. Brian acetylcholinesterase (AChE) and liver enzymes [aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were also determined.

RESULTS

DRLC reversed memory impairment and dysregulated levels of malondialdehyde, glutathione, nitrite and glutathione S-transferase in the liver and brain tissues of mice pretreated with CuSO₄. The increased proinflammatory cytokines concentrations in the liver and brain tissues of mice pretreated with CuSO₄ were reduced by DRLC. The elevated brain AChE and liver enzymes activities induced by CuSO₄ were also reduced by DRLC.

CONCLUSION

Taken together, these findings suggest that DRLC attenuates CuSO₄-induced memory dysfunctions in mice through enhancement of antioxidative pathway, inhibition of pro-inflammatory cytokines and augmentation of liver function.

Is There a Connection between the Metabolism of Copper, Sulfur, and Molybdenum in Alzheimer’s Disease? New Insights on Disease Etiology

Alzheimer’s disease (AD) and other forms of dementia was ranked 3rd in both the Americas and Europe in 2019 in a World Health Organization (WHO) publication listing the leading causes of death and disability worldwide. Copper (Cu) imbalance has been reported in AD and increasing evidence suggests metal imbalance, including molybdenum (Mo), as a potential link with AD occurrence.We conducted an extensive literature review of the last 60 years of research on AD and its relationship with Cu, sulfur (S), and Mo at out of range levels.Weanalyzed the interactions among metallic elements’ metabolisms;Cu and Mo are biological antagonists, Mo is a sulfite oxidase and xanthine oxidase co-factor, and their low activities impair S metabolism and reduce uric acid, respectively. We found significant evidence in the literature of a new potential mechanism linking Cu imbalance to Mo and S abnormalities in AD etiology: under certain circumstances, the accumulation of Cu not bound to ceruloplasmin might affect the transport of Mo outside the blood vessels, causing a mild Mo deficiency that might lowerthe activity of Mo and S enzymes essential for neuronal activity. The current review provides an updated discussion of the plausible mechanisms combining Cu, S, and Mo alterations in AD.

Development of lab-on-chip biosensor for the detection of toxic heavy metals: A review

Recently, a decrease in water availability and quality has been raised due to rapid industrialization, unsustainable agricultural activities and anthropogenic activities. Heavy metals are considered significant pollutants in the water environment, cause environmental hazards and health effects to humans. For monitoring water contaminants utilized different conventional techniques. Still, they have some drawbacks, such as cost expensive, ecological issues, and processing time, requiring technicians and researchers to operate them effectively. Biosensors have become reasonable devices for screening and identifying environmental contaminants because of their different benefits contrasted with other detecting techniques. This review summarizes the toxic effect of heavy metal and their source, occurrence. A detailed discussion is provided on the heavy metal recognition materials for detecting heavy metals in wastewater. Lab on chip (LOC) is an emerging micro-electrical mechanical system (MEMS) device that intakes liquid and makes it move through the micro-channels, to accomplish fast, cost-effective and profoundly sensitive analysis with significant yield. LOC also provided a discussion on numerous laboratory functions on a single platform. This article attempts to discuss the detection of heavy metals using lab on a chip by suitable recognition materials. Further, the design and fabrication mechanism and their recognition abilities of LOC were also reviewed. The review mainly focuses on the application of LOC biosensors, pros, and cons, and suggests a roadmap towards future development to enhance the practical use in pollutant monitoring.

Blood copper excess is associated with mild cognitive impairment in elderly Chinese

BACKGROUND

Copper is associated with mild cognitive impairment (MCI). However, there is a lack of relevant population studies with large sample sizes.

AIMS

This study used baseline data from a cohort study to determine the distribution characteristics of MCI in the elderly and to estimate the association between whole blood copper concentrations and MCI.

METHODS

MCI status was screened by the Mini-Mental State Examination (MMSE) scale and Activities of Daily Living (ADL) scale. The concentration of copper in whole blood was determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS).

RESULTS

A total of 1057 subjects with an average age of 71.82 ± 6.45 years were included in this study. There were 215 patients with MCI, and the prevalence of MCI was 20.34%. After adjusting for general demographic variables, logistic regression analysis showed that the risk of MCI in the elderly with high copper level was 1.354 times higher than that in the elderly with low copper level (OR 1.354, 95% CI 1.047-1.983, P = 0.034).

CONCLUSION

In this study, it was found that the prevalence of MCI was different in gender, age, education level and other aspects, and a higher copper level in the elderly was significantly related to the occurrence of MCI. The association was stronger in older adults and men.

Do glutathione and copper interact to modify Alzheimer's disease pathogenesis?

Alzheimer's disease (AD) is a progressive neurodegenerative disorder first described in 1906 that is currently estimated to impact ∼40 million people worldwide. Extensive research activities have led to a wealth of information on the pathogenesis, hallmarks, and risk factors of AD; however, therapeutic options remain extremely limited. The large number of pathogenic factors that have been reported to potentially contribute to AD include copper dyshomeostasis as well as increased oxidative stress, which is related to alterations to molecular antioxidants like glutathione (GSH). While the individual roles of GSH and copper in AD have been studied by many research groups, their interactions have received relatively little attention, although they appear to interact and affect each other's regulation. Existing knowledge on how GSH-copper interactions may affect AD is sparse and lacks focus. This review first highlights the most relevant individual roles that GSH and copper play in physiology and AD, and then collects and assesses research concerning their interactions, in an effort to provide a more accessible and understandable picture of the role of GSH, copper, and their interactions in AD.

Metallobiology and therapeutic chelation of biometals (copper, zinc and iron) in Alzheimer's disease: Limitations, and current and future perspectives

BACKGROUND

Alzheimer's disease (AD) is the most prevalent cause of cognitive impairment and dementia worldwide. The pathobiology of the disease has been studied in the form of several hypotheses, ranging from oxidative stress, amyloid-beta (Aβ) aggregation, accumulation of tau forming neurofibrillary tangles (NFT) through metal dysregulation and homeostasis, dysfunction of the cholinergic system, and to inflammatory and autophagic mechanism. However, none of these hypotheses has led to confirmed diagnostics or approved cure for the disease.

OBJECTIVE

This review is aimed as a basic and an encyclopedic short course into metals in AD and discusses the advances in chelation strategies and developments adopted in the treatment of the disease. Since there is accumulating evidence of the role of both biometal dyshomeostasis (iron (Fe), copper (Cu), and zinc (Zn)) and metal-amyloid interactions that lead to the pathogenesis of AD, this review focuses on unraveling therapeutic chelation strategies that have been considered in the treatment of the disease, aiming to sequester free and protein-bound metal ions and reducing cerebral metal burden. Promising compounds possessing chemically modified moieties evolving as multi-target ligands used as anti-AD drug candidates are also covered.

RESULTS AND CONCLUSION

Several multidirectional and multifaceted studies on metal chelation therapeutics show the need for improved synthesis, screening, and analysis of compounds to be able to effectively present chelating anti-AD drugs. Most drug candidates studied have limitations in their physicochemical properties; some enhance redistribution of metal ions, while others indirectly activate signaling pathways in AD. The metal chelation process in vivo still needs to be established and the design of potential anti-AD compounds that bi-functionally sequester metal ions as well as inhibit the Aβ aggregation by competing with the metal ions and reducing metal-induced oxidative damage and neurotoxicity may signal a bright end in chelation-based therapeutics of AD.

Copper Imbalance in Alzheimer's Disease and Its Link with the Amyloid Hypothesis: Towards a Combined Clinical, Chemical, and Genetic Etiology

The cause of Alzheimer's disease (AD) is incompletely defined. To date, no mono-causal treatment has so far reached its primary clinical endpoints, probably due to the complexity and diverse neuropathology contributing to the neurodegenerative process. In the present paper, we describe the plausible etiological role of copper (Cu) imbalance in the disease. Cu imbalance is strongly associated with neurodegeneration in dementia, but a complete biochemical etiology consistent with the clinical, chemical, and genetic data is required to support a causative association, rather than just correlation with disease. We hypothesize that a Cu imbalance in the aging human brain evolves as a gradual shift from bound metal ion pools, associated with both loss of energy production and antioxidant function, to pools of loosely bound metal ions, involved in gain-of-function oxidative stress, a shift that may be aggravated by chemical aging. We explain how this may cause mitochondrial deficits, energy depletion of high-energy demanding neurons, and aggravated protein misfolding/oligomerization to produce different clinical consequences shaped by the severity of risk factors, additional comorbidities, and combinations with other types of pathology. Cu imbalance should be viewed and integrated with concomitant genetic risk factors, aging, metabolic abnormalities, energetic deficits, neuroinflammation, and the relation to tau, prion proteins, α-synuclein, TAR DNA binding protein-43 (TDP-43) as well as systemic comorbidity. Specifically, the Amyloid Hypothesis is strongly intertwined with Cu imbalance because amyloid-β protein precursor (AβPP)/Aβ are probable Cu/Zn binding proteins with a potential role as natural Cu/Zn buffering proteins (loss of function), and via the plausible pathogenic role of Cu-Aβ.

Chronic copper exposure directs microglia towards degenerative expression signatures in wild-type and J20 mouse model of Alzheimer's disease

BACKGROUND

Copper (Cu) is an essential metal mediating a variety of vital biological reactions with its redox property. Its dyshomeostasis has been associated with accelerated cognitive decline and neurodegenerative disorders, such as Alzheimer's disease (AD). However, underlying neurotoxic mechanisms elicited by dysregulated Cu remain largely elusive. We and others previously demonstrated that exposure to Cu in drinking water significantly exacerbated pathological hallmarks of AD and pro-inflammatory activation of microglia, coupled with impaired phagocytic capacity, in mouse models of AD.

METHODS

In the present study, we extended our investigation to evaluate whether chronic Cu exposure to wild-type (WT) and J20 mouse model of AD perturbs homeostatic dynamics of microglia and contributes to accelerated transformation of microglia towards degenerative phenotypes that are closely associated with neurodegeneration. We further looked for evidence of alterations in the microglial morphology and spatial memory of the Cu-exposed mice to assess the extent of the Cu toxicity.

RESULTS

We find that chronic Cu exposure to pre-pathological J20 mice upregulates the translation of degenerative genes and represses homeostatic genes within microglia even in the absence amyloid-beta plaques. We also observe similar expression signatures in Cu-exposed WT mice, suggesting that excess Cu exposure alone could lead to perturbed microglial homeostatic phenotypes and contribute to accelerated cognitive decline.

CONCLUSION

Our findings highlight the risk of chronic Cu exposure on cognitive decline and altered microglia activation towards degenerative phenotypes. These changes may represent one of the key mechanisms linking Cu exposure or its dyshomeostasis to an increased risk for AD.

Agricultural Use of Copper and Its Link to Alzheimer's Disease

Copper is an essential nutrient for plants, animals, and humans because it is an indispensable component of several essential proteins and either lack or excess are harmful to human health. Recent studies revealed that the breakdown of the regulation of copper homeostasis could be associated with Alzheimer's disease (AD), the most common form of dementia. Copper accumulation occurs in human aging and is thought to increase the risk of AD for individuals with a susceptibility to copper exposure. This review reports that one of the leading causes of copper accumulation in the environment and the human food chain is its use in agriculture as a plant protection product against numerous diseases, especially in organic production. In the past two decades, some countries and the EU have invested in research to reduce the reliance on copper. However, no single alternative able to replace copper has been identified. We suggest that agroecological approaches are urgently needed to design crop protection strategies based on the complementary actions of the wide variety of crop protection tools for disease control.

A Preliminary Study of Cu Exposure Effects upon Alzheimer's Amyloid Pathology

A large body of evidence indicates that dysregulation of cerebral biometals (Fe, Cu, Zn) and their interactions with amyloid precursor protein (APP) and Aβ amyloid may contribute to the Alzheimer's disease (AD) Aβ amyloid pathology. However, the molecular underpinnings associated with the interactions are still not fully understood. Herein we have further validated the exacerbation of Aβ oligomerization by Cu and H2O2 in vitro. We have also reported that Cu enhanced APP translations via its 5' untranslated region (5'UTR) of mRNA in SH-SY5Y cells, and increased Aβ amyloidosis and expression of associated pro-inflammatory cytokines such as MCP-5 in Alzheimer's APP/PS1 doubly transgenic mice. This preliminary study may further unravel the pathogenic role of Cu in Alzheimer's Aβ amyloid pathogenesis, warranting further investigation.

Low copper-2 intake in Switzerland does not result in lower incidence of Alzheimer's disease and contradicts the Copper-2 Hypothesis

In recent years, the “Copper-2 Hypothesis” has been put forth in an attempt to explain the epidemic of Alzheimer’s disease (AD) in the Western world. According to this hypothesis, “free” copper (copper-2) in drinking water, dietary supplements, and meat is the chief cause of the increased incidence of AD in recent decades. In contrast to the US, copper plumbing for drinking water is not used in Switzerland and tap water is very low in copper. Other “risk” factors including dietary supplements and meat consumption are also lower in Switzerland than in the US. Yet, the incidence of AD is closely similar in the two countries. This contradicts the Copper-2 Hypothesis.

Impact statement

The Western world is faced with an Alzheimer’s epidemic. Identifying the life style and anthropogenic factors involved has become a priority. This is a formidable challenge due to the complexity and the slow progression of the disease. A hypothesis put forth by George Brewer postulates divalent copper (copper-2), chiefly present in drinking water from copper pipes, to be a major risk factor for Alzheimer’s disease. In Switzerland, copper pipes are not used for drinking water, but the frequency of Alzheimer’s disease is similar to that of other Western countries. This contradicts Brewer’s hypothesis and suggests that other factors are responsible for today’s Alzheimer’s epidemic.

Highlights of ASS234: a novel and promising therapeutic agent for Alzheimer's disease therapy

There is no effective treatment to face Alzheimer’s disease complexity. Multitarget molecules are a good approach against the multiple physiopathological events associated with its development and progression. In this context, N-((5-(3-(1-benzylpiperidin-4-yl) propoxy)-1- methyl-1H-indol-2-yl)methyl)-N-methylprop-2-yn-1-amine (ASS234) has been tested achieving promising results. ASS234 has demonstrated to cross the blood-brain barrier in vivo, and a good in silico safety profile being less toxic than donepezil. Besides, ASS234 reversibly inhibits human acetyl- and butyryl-cholinesterase, and irreversibly inhibits human monoamine oxidase A and B. Moreover, this multitarget molecule has antioxidant and neuroprotective properties, and inhibits Αβ_1–42 and Αβ_1–40 self-aggregation. Inquiring about the mechanism of action, several signaling pathways related to Alzheimer’s disease had been explored showing that ASS234 induces the wingless-type MMTV integration site (Wnt) family and several members of the heat shock proteins family and moreover counteracts neuroinflammatory and oxidative stress-related genes promoting the induction of several key antioxidant genes. Finally, in vivo experiments with ASS234 in C57BL/6J mice displayed its ability to reduce amyloid plaque burden and gliosis in the cortex and hippocampus, ameliorating scopolamine-induced learning deficits. Here we gather the information regarding ASS234 evaluated so far, showing its ability to face different targets, necessary to counteract a neurodegenerative disease as complex as the Alzheimer’s disease.

Innovative Biomarkers for Alzheimer's Disease: Focus on the Hidden Disease Biomarkers

The criteria for the clinical diagnosis of AD include the analysis of biomarkers of the underlying brain disease pathology; a set of cerebrospinal fluid (CSF) tests, amyloid-β1-42 (Aβ42), total-tau (t-tau), and phosphorylated tau (p-tau), are available and their performance in a clinical setting has been assessed in several studies. Thus, in dementia research, great advances have been made in the discovery of putative biomarkers; however, disappointingly, few of them have been translated into clinically applicable assays. To find biomarkers able to reliably detect AD pathology already at prodromal stages and in blood is even more important. Recent technical breakthroughs have provided ultrasensitive methods that allow the detection of brain-specific proteins in blood. In the present review, we will focus on the usefulness of ultrasensitive technologies for biomarker discovery and trace elements detection; moreover, we will review studies on circulating nano-compartments, a promising novel source of material for molecular diagnostics.

Avoiding Alzheimer's disease: The important causative role of divalent copper ingestion

IMPACT STATEMENT

The work described in this review is very important to scientists working on Alzheimer's disease (AD) because it reveals a cause for the explosive epidemic of this disease. It is also important to the public because it provides a method to avoid this newly revealed cause, and thereby avoid AD. The field is advanced because this review reveals new information about the mechanism of AD pathogenesis, namely copper, and specifically divalent copper, toxicity is important. New information about divalent copper toxicity in the brain affecting cognition is revealed. The field is impacted strongly because, in view of the frustrations that have occurred in treatment developed, now most AD can be prevented. This means the suffering of the patient, the prolonged and difficult care required by caregivers, and the enormous expenditures for this one disease, can now be avoided.

A new fluorene derived Schiff-base as a dual selective fluorescent probe for Cu2+ and CN. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019;207:6-15. [PMID: 30195186 DOI: 10.1016/j.saa.2018.08.058]

A new fluorene based fluorogenic chemosensor, 2-[(9H-Fluoren-2-ylmethylene)-amino]-phenol (L), has been designed, synthesized, and characterized by CHN analyses and different spectroscopic methods. This turn-on fluorogenic chemosensor shows high selectivity and sensitivity toward Cu²⁺ and CN^- with low detection limits of 1.54 × 10^-9 M and 1.83 × 10^-7 M, respectively. The stoichiometry ratio of L-Cu²⁺ in solution is 1:1, by the method of Job's plot and ESI-MS. The microcrystalline solid product of the chemosensor reaction with copper is characterized as CuL₂. The χT value for CuL₂ is temperature independent at a value of 0.403 cm³ K mol^-1, which is in agreement with a mononuclear copper(II) complex with an isotropic g-value of 2.075. The fluorescence turn-on recognition process for detection of Cu²⁺ is attributed to the restricted imine isomerization and blocking of intramolecular charge transfer (ICT) quenching process in the analyte-bound sensor. The selectivity of L for Cu²⁺ is based on the chelation-enhanced fluorescence effect (CHEF) mechanism. Other interfering ions such as Na⁺, K⁺, Ca²⁺, Mg²⁺, Ag⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Mn²⁺, Pb²⁺ and Al³⁺, show no change in the fluorescence intensity of L in the presence of Cu²⁺. Furthermore, the compound L can be used as a fluorescence and colorimetric sensor for selective detection of CN^- over a number of other anions based on the nucleophilic addition to the imine CN bond, with consequent hydrogen bond formation and electrostatic interaction of the resulting product with K⁺. The sensing mechanism for CN^- was theoretically supported by DFT calculations.

Proteomic alterations of brain subcellular organelles caused by low-dose copper exposure: implication for Alzheimer's disease

Excessive copper intake can lead to neurotoxicity, but there is a lack of comprehensive understanding on the potential impact of copper exposure especially at a low-dose on brain. We used 3xTg-AD mice to explore the potential neurotoxicity of chronic, low-dose copper treatment (0.13 ppm copper chloride in drinking water) on behavior and the brain hippocampal mitochondrial and nuclear proteome. Low-dose copper increased the spatial memory impairment of these animals, increased accumulation of intracellular amyloid 1-42 (Aβ_1-42), decreased ATP content, increased the positive staining of 8-hydroxyguanosine (8-OHdG), a marker of DNA oxidative damage, and caused apoptosis and a decrease in synaptic proteins. Mitochondrial proteomic analysis by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) revealed modulation of 24 hippocampal mitochondrial proteins (14 increased and 10 decreased) in copper-treated vs. untreated 3xTg-AD mice. Nuclear proteomic analysis revealed 43 modulated hippocampal nuclear proteins (25 increased and 18 decreased) in copper-treated 3xTg-AD vs. untreated mice. Classification of modulated mitochondrial and nuclear proteins included functional categories such as energy metabolism, synaptic-related proteins, DNA damage and apoptosis-related proteins, and oxidative stress-related proteins. Among these differentially expressed mitochondrial and nuclear proteins, nine proteins were abnormally expressed in both hippocampus mitochondria and nuclei, including electron transport chain-related proteins NADH dehydrogenase 1 alpha subcomplex subunit 10 (NDUAA), cytochrome b-c1 complex subunit Rieske (UCRI), cytochrome c oxidase subunit 5B (COX5B), and ATP synthase subunit d (ATP5H), glycolytic-related pyruvate kinase PKM (KPYM) and pyruvate dehydrogenase E1 component subunit alpha (ODPA). Furthermore, we found coenzyme Q10 (CoQ10), an endogenous mitochondrial protective factor/antioxidant, modulated the expression of 12 differentially expressed hippocampal proteins (4 increased and 8 decreased), which could be classified in functional categories such as glycolysis and synaptic-related proteins, oxidative stress-related proteins, implying that CoQ10 improved synaptic function, suppress oxidative stress, and regulate glycolysis. For the proteomics study, we validated the expression of several proteins related to synapses, DNA and apoptosis. The data confirmed that synapsin-2, a synaptic-related protein, was significantly decreased in both mitochondria and nuclei of copper-exposed 3xTg-AD mice. In mitochondria, dynamin-1 (DYN1), an apoptosis-related proteins, was significantly decreased. In the cellular nuclei, paraspeckle protein 1 (PSPC1) and purin-rich element-binding protein alpha (Purα), two DNA damage-related proteins, were significantly decreased and increased, respectively. We conclude that low-dose copper exposure exacerbates the spatial memory impairment of 3xTg-AD mice and perturbs multiple biological/pathogenic processes by dysregulating the mitochondrial and nuclear proteome. Exposure to copper might therefore contribute to the evolution of AD.

Copper dyshomeostasis in Wilson disease and Alzheimer's disease as shown by serum and urine copper indicators

Abnormal handling of copper is the cause of Wilson disease (WD), a rare disorder typified by increased levels in plasma copper not-bound to ceruloplasmin (nCp-Cu, also known as 'free' copper). In Alzheimer's disease (AD), meta-analyses show that copper decreases in brain but increases in serum, due to the nCp Cu component increase. Despite the similarities, a direct comparison of copper biological status in the two diseases has never been carried out. To fill this gap, we evaluated serum copper, ceruloplasmin, nCp-Cu and Cu:Cp in 385 CE and 336 healthy controls previously investigated that were compared with 9 newly diagnosed WD patients. We then assessed 24h copper urinary excretion in 24 WD patients under D-penicillamine (D-pen) treatment and in 35 healthy controls, and compared results with those of AD patients participating to a D-pen phase II clinical trial previously published. After adjusting for sex and age, serum nCp-Cu and Cu:Cp resulted higher in AD and in WD than in healthy controls (both p<0.001). While nCp-Cu was similar between AD and WD, Cu:Cp was higher in WD (p<0.016). 24h urinary copper excretion in AD patients (12.05μg/day) was higher than in healthy controls (4.82μg/day; p<0.001). 77.8% of the AD patients under D-pen treatment had a 24h urinary excretion higher than 200μg/day, suggestive of a failure of copper control. This study provides new insight into the pathophysiology of copper homeostasis in AD, showing a failure of copper control and the Cu:Cp ratio as an eligible marker.

The Metal Neurotoxins: An Important Role in Current Human Neural Epidemics?

Many published studies have illustrated that several of the present day neurological epidemics (autism, attention deficit disorder, Alzheimer's) cannot be correlated to any single neurotoxicant. However, the present scientific examination of the numerous global blood monitoring databases for adults that include the concentrations of the neurotoxic elements, aluminum (Al), arsenic (As), lead (Pb), manganese (Mn), mercury (Hg), and selenium (Se) clearly indicate that, when considered in combination, for some, the human body may become easily over-burdened. This can be explained by changes in modern lifestyles. Similar data, solely for pregnant women, have been examined confirming this. All these elements are seen to be present in the human body and at not insignificant magnitudes. Currently suggested minimum risk levels (MRL) for humans are discussed and listed together with averages of the reported distributions, together with their spread and maximum values. One observation is that many distributions for pregnant women are not too dissimilar from those of general populations. Women obviously have their individual baseline of neurotoxin values before pregnancy and any efforts to modify this to any significant degree is not yet clearly apparent. For any element, distribution shapes are reasonably similar showing broad distributions with extended tails with numerous outlier values. There are a certain fraction of people that lie well above the MRL values and may be at risk, especially if genetically susceptible. Additionally, synergistic effects between neurotoxins and with other trace metals are now also being reported. It appears prudent for women of child-bearing age to establish their baseline values well before pregnancy. Those at risk then can be better identified. Adequate instrumental testing now is commercially available for this. In addition, directives are necessary for vaccination programs to use only non-neurotoxic adjuvants, especially for young children and all women of child-bearing ages. Additionally, clearer directives concerning fish consumption must now be reappraised.

Alzheimer's Disease as the Product of a Progressive Energy Deficiency Syndrome in the Central Nervous System: The Neuroenergetic Hypothesis

The decreased availability of metabolizable energy resources in the central nervous system is hypothesized to be a key factor in the pathogenesis of Alzheimer's disease. More specifically, the age-related decline in the ability of glucose to cross the blood-brain barrier creates a metabolic stress that shifts the normal, benign processing of amyloid-β protein precursor toward pathways associated with the production of amyloid-β plaques and tau-containing neurofibrillary tangles that are characteristic of the disease. The neuroenergetic hypothesis provides insight into the etiology of Alzheimer's disease and illuminates new approaches for diagnosis, monitoring, and treatment.