Copper: effects of deficiency and overload

Subcellular Localization of Copper-Cellular Bioimaging with Focus on Neurological Disorders

As an essential trace element, copper plays a pivotal role in physiological body functions. In fact, dysregulated copper homeostasis has been clearly linked to neurological disorders including Wilson and Alzheimer’s disease. Such neurodegenerative diseases are associated with progressive loss of neurons and thus impaired brain functions. However, the underlying mechanisms are not fully understood. Characterization of the element species and their subcellular localization is of great importance to uncover cellular mechanisms. Recent research activities focus on the question of how copper contributes to the pathological findings. Cellular bioimaging of copper is an essential key to accomplish this objective. Besides information on the spatial distribution and chemical properties of copper, other essential trace elements can be localized in parallel. Highly sensitive and high spatial resolution techniques such as LA-ICP-MS, TEM-EDS, S-XRF and NanoSIMS are required for elemental mapping on subcellular level. This review summarizes state-of-the-art techniques in the field of bioimaging. Their strengths and limitations will be discussed with particular focus on potential applications for the elucidation of copper-related diseases. Based on such investigations, further information on cellular processes and mechanisms can be derived under physiological and pathological conditions. Bioimaging studies might enable the clarification of the role of copper in the context of neurodegenerative diseases and provide an important basis to develop therapeutic strategies for reduction or even prevention of copper-related disorders and their pathological consequences.

Copper sulfate-induced endoplasmic reticulum stress promotes hepatic apoptosis by activating CHOP, JNK and caspase-12 signaling pathways

Copper (Cu), a transition metal, is an essential trace element in human and animal nutrition at low concentration, but Cu has toxic effects on tissues and organs at high concentration. Endoplasmic reticulum (ER) is a toxicological target in Cu poison. Thus far, no studies have focused on the relationship among copper, endoplasmic reticulum (ER) stress and apoptosis in animal and human livers. In the present study, mice treated with copper sulfate (CuSO₄) were used to assess the impacts of copper on ER stress and hepatic apoptosis. A total of 240 mice were orally administered with 0 (control), 10, 20 and 40 mg/kg of CuSO₄ for 42 days. The results indicated that CuSO₄ at 10 mg/kg markedly induced hepatocyte apoptosis and ER stress. In addition, ER stress was characterized by the increased mRNA and protein levels of glucose-regulated protein 78 (GRP78) and 94 (GRP94). Furthermore, ER stress-triggered 3 apoptotic pathways were also activated by the increased intracellular calcium and up-regulated expression levels of genes involved in growth arrest- and DNA damage-inducible gene 153 (Gadd153/CHOP), c-Jun N-terminal kinase (JNK) and cysteine aspartate-specific protease 12 (caspase-12) signaling pathways in CuSO₄-treated mice. In conclusion, CuSO₄-induced ER stress can promote hepatic apoptosis in mice by activating CHOP, JNK and caspase-12 signaling pathways.

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

Electrochemically assisted synthesis of poly(3,4-dihydroxyphenylalanine) fluorescent organic nanoparticles for sensing applications

Facile preparation of polyDOPA-FONs is achieved via the electrochemical oxidation method.

Advances in the mechanism of high copper diets in restraining pigs growth

High copper feed has been widely used as an inexpensive and highly effective feed additive to promote growth performance of pigs. However, long-term feeding of high copper feed may reduce the growth-promoting effects of copper, time-dependent accumulation of copper in animal tissues and organs, and copper toxicity thereby reducing the growth performance of pigs. Due to the widespread effects of high copper supplementation in animals' diets, the benefits and drawbacks of high copper feeding in pigs have been reported in several studies. Meanwhile, few of these studies have systematically described the mechanism by which high copper diets restrain pig growth. Therefore, to address the concerns and give a better understanding of the mechanism of high copper diet in restraining pig growth in different systems, this paper reviews the research progress of long-term supplementation of high copper on the growth of pigs and provides some suggestions and further research directions.

Serum, erythrocyte and urinary concentrations of iron, copper, selenium and zinc do not change during an incremental test to exhaustion in either normothermic or hyperthermic conditions

AIM

The aim of this study was to evaluate the effect of the performance of an incremental exercise test until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urine concentrations of Iron (Fe), Copper (Cu), Selenium (Se) and Zinc (Zn).

METHODS

Nineteen adult males (age: 22.58 ± 1.06 years) performed two maximum incremental exercise tests on a cycloergometer in normothermia (22 ± 2 °C) and hyperthermia (42±2 °C) separated by 48 h. Urine, serum and erythrocyte samples were collected before and after each test.

RESULTS

Serum Se (p < 0.01) and Cu (p < 0.05) levels were altered after each test, but the significance disappeared with the correction for haematocrit. The rest of the values did not undergo alterations in either condition.

CONCLUSIONS

It seems that a higher stimulus is necessary to obtain changes in these minerals. The study reveals the need to correct serum concentrations concerning possible changes in these volumes after an acute effort.

Evaluation of Whole Blood Trace Element Levels in Chinese Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, which has increased markedly during the last decades. Essential trace elements play an important role in neurological function and their imbalances are common in children with ASD. The objective of the present study was to investigate whole blood levels of trace elements including zinc (Zn), copper (Cu), iron (Fe), and magnesium (Mg) in Chinese children with ASD. In total, 113 children diagnosed with ASD and 141 age-matched and gender-matched neurotypical children, divided into two gender and age groups of preschool age (2-5 years old) and school (6-10 years old) age, were examined. The quantitative analyses of whole blood trace element contents were performed by using flame atomic absorption spectroscopy. In the present study, the children with ASD generally had lower whole blood levels of Zn than the neurotypical controls. No significant differences in the whole blood Cu, Zn/Cu ratio, Fe, or Mg was detected between the ASD group and the control group. It is notable that whole blood Fe level in boys with ASD was significantly higher than in girls with ASD, and was nearly significant when compared with the control level of boys. After stratification for age, a significant 6% decrease in whole blood Zn levels was detected in preschool-aged children with ASD as compared to the control values. However, this significant ASD-related change was not detected in school-aged children. The whole blood Zn level and Zn/Cu ratio were significantly increased in school-aged children than in preschool-aged children in both ASD and control group. In addition, school-aged children with ASD had a significantly higher level of whole blood Fe than preschool-aged children with ASD. The results of the present study suggest an association between whole blood levels of Zn in Chinese children with ASD.

The copper(II) binding centres of carbonic anhydrase are differently affected by reductants that ensure the redox intracellular environment

Copper is involved in several biological processes. The static and labile copper pools are controlled by means of a network of influx and efflux transporters, storage proteins, chaperones, transcription factors and small molecules as glutathione (GSH), which contributes to the cell reducing environment. To follow the fate of intracellular copper labile pool, a variant of human apocarbonic anhydrase has been proposed as fluorescent probe to monitor cytoplasmic Cu²⁺. Aware that in this cellular compartment copper ion is present as Cu⁺, electron spin resonance technique (ESR) was used to ascertain whether (bovine or human) carbonic anhydrase (CA) was able to accommodate Cu⁺ in the same sites occupied by Cu²⁺, in the presence of naturally occurring reducing agents such as ascorbate and GSH. Our ESR results on Cu²⁺ complexes with CA allow for a complete characterization of the two metal binding sites of the protein in solution. The use of the reported affinity constants of zinc in the catalytic site and of Cu²⁺ in the peripheral and catalytic site, allow us to obtain the speciation of copper species mimicking the spectroscopic study conditions. The different Cu²⁺ coordination features in the catalytic and the peripheral (the N-terminus cleft mouth) binding sites influence the chemical reduction effect of the two main naturally occurring reductants. Ascorbate reversibly reduces the Cu²⁺ complex with CA, while glutathione irreversibly induces the formation of Cu²⁺ complex with its oxidized form (GSSG). Our results questioned the use of CA as intracellular Cu²⁺ sensor. Furthermore, translating these findings to intracellular environment, the conversion of GSH in GSSG can significantly alter the metallostasis.

The bio-relevant metals of the periodic table of the elements

The bio-relevant metals (and derived compounds) of the Periodic Table of the Elements (PTE) are in the focus. The bulk elements sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) from the s-block, which are essential for all kingdoms of life, and some of their bio-activities are discussed. The trace elements of the d-block of the PTE as far as they are essential for humans (Mn, Fe, Co, Cu, Zn, Mo) are emphasized, but V, Ni, Cd, and W, which are essential only for some forms of life, are also considered. Chromium is no longer classified as being essential. From the p-block metals only the metalloid (half-metal) selenium (Se) is essential for all forms of life. Two other metalloids, silicon and arsenic, are briefly mentioned, but they have not been proven as being essential for humans. All metals of the PTE and a plethora of their compounds are used in industry and many of them are highly toxic, like lead (Pb), which is discussed as a prime example. Several metals of the PTE, that is, their ions and complexes, are employed in medicine and we discuss the role of lithium, gallium, strontium, technetium, silver, gadolinium (the only f-block element), platinum, and gold.

Five Decades of Cuprizone, an Updated Model to Replicate Demyelinating Diseases

INTRODUCTION

Demyelinating diseases of the central nervous system (CNS) comprise a group of neurological disorders characterized by progressive (and eventually irreversible) loss of oligodendrocytes and myelin sheaths in the white matter tracts. Some of myelin disorders include: Multiple sclerosis, Guillain-Barré syndrome, peripheral nerve polyneuropathy and others. To date, the etiology of these disorders is not well known and no effective treatments are currently available against them. Therefore, further research is needed to gain a better understand and treat these patients. To accomplish this goal, it is necessary to have appropriate animal models that closely resemble the pathophysiology and clinical signs of these diseases. Herein, we describe the model of toxic demyelination induced by cuprizone (CPZ), a copper chelator that reduces the cytochrome and monoamine oxidase activity into the brain, produces mitochondrial stress and triggers the local immune response. These biochemical and cellular responses ultimately result in selective loss of oligodendrocytes and microglia accumulation, which conveys to extensive areas of demyelination and gliosis in corpus callosum, superior cerebellar peduncles and cerebral cortex. Remarkably, some aspects of the histological pattern induced by CPZ are similar to those found in multiple sclerosis. CPZ exposure provokes behavioral changes, impairs motor skills and affects mood as that observed in several demyelinating diseases. Upon CPZ removal, the pathological and histological changes gradually revert. Therefore, some authors have postulated that the CPZ model allows to partially mimic the disease relapses observed in some demyelinating diseases.

CONCLUSION

for five decades, the model of CPZ-induced demyelination is a good experimental approach to study demyelinating diseases that has maintained its validity, and is a suitable pharmacological model for reproducing some key features of demyelinating diseases, including multiple sclerosis.

Metal cofactors trafficking and assembly in the cell: a molecular view

Metal ions are essential cofactors required by the proteome of organisms from any kingdom of life to correctly exert their functions. Dedicated cellular import, transport and homeostasis systems assure that the needed metal ion is correctly delivered and inserted into the target proteins and avoid the presence of free metal ions in the cell, preventing oxidative damaging. Among metal ions, in eukaryotic organisms copper and iron are required by proteins involved in absolutely essential functions, such as respiration, oxidative stress protection, catalysis, gene expression regulation. Copper and iron binding proteins are localized in essentially all cellular compartments. Copper is physiologically present mainly as individual metal ion. Iron can be present both as individual metal ion or as part of cofactors, such as hemes and iron-sulfur (Fe-S) clusters. Both metal ions are characterized by the ability to cycle between different oxidation states, which enable them to catalyze redox reactions and to participate in electron transfer processes. Here we describe in detail the main processes responsible for the trafficking of copper and iron sulfur clusters, with particular interest for the structural aspects of the maturation of copper and iron-sulfur-binding proteins.

Accuracy of the radioactive copper incorporation test in the diagnosis of Wilson disease

BACKGROUND & AIMS

In Wilson disease (WD), copper accumulates in the liver and other tissues because of mutations in the ATP7B copper transporter gene. Early and effective anticopper treatment is crucial. However, routine diagnostic methods based on clinical findings, copper metabolism tests, liver biopsies and DNA analyses do not always provide a conclusive diagnosis. The aim was to evaluate radioactive copper incorporation as a diagnostic test.

METHODS

We included cases with a diagnosis of WD supported by radiocopper testing and later, when available, confirmed by DNA analysis. Incorporation of ⁶⁴ Cu was measured at 2, 24 and 48 hours following intravenous injection. Diagnostic accuracy (area under the receiver operating characteristic curve [AUC]), sensitivity, specificity and predictive value were assessed for 24 hours/2 hours and 48 hours/2 hours ⁶⁴ Cu ratios and compared with serum measurements of ceruloplasmin, copper, non-ceruloplasmin-bound copper and urinary 24-hours copper excretion.

RESULTS

Patients having two pathogenic ATP7B mutations (homozygotes/compound heterozygotes) (n = 74) had significantly lower 24 hours/2 hours and 48 hours/2 hours ⁶⁴ Cu ratios than heterozygote controls (n = 21) (mean 0.14 and 0.12 vs 0.49 and 0.63, respectively; both P < .001). Of note, 24 hours/2 hours and 48 hours/2 hours ⁶⁴ Cu ratios had excellent diagnostic accuracy, with AUCs approaching 1, and only 24-hours urinary copper excretion displayed similar positive features. Other copper metabolism tests studied had lower accuracy, specificity and sensitivity.

CONCLUSIONS

The radioactive copper test had excellent diagnostic accuracy and may be useful in the evaluation of new therapies aimed at restoring ATP7B function.

Dietary Flavonoids, Copper Intake, and Risk of Metabolic Syndrome in Chinese Adults

The effects of flavonoids and copper (Cu) on metabolic syndrome (MetS) have been investigated separately, but no information exists about the joint associations between flavonoids and Cu on the risk of MetS in population studies. In this cross-sectional study, a total of 9108 people aged 20⁻75 years from the Harbin Cohort Study on Diet, Nutrition, and Chronic Non-Communicable Diseases (HDNNCDS) were included. Flavonoid intakes were calculated based on the flavonoid database created in our laboratory. Cu and other nutrient intakes were estimated using the Chinese Food Composition Table. Among all study subjects, a total of 2635 subjects (28.9%) met the diagnostic criteria for inclusion in the MetS group. Total flavonoids (fourth vs. first quartile, odds ratio (OR): 0.77, 95% confidence interval (CI) 0.66⁻0.90, P_trend = 0.002) and Cu (OR 0.81, 90% CI: 0.70⁻0.94, P_trend = 0.020) were inversely associated with the risk of MetS after adjusting for potential confounders. Higher flavonoid intake was more strongly associated with a lower risk of MetS with high levels of Cu intake (P_interaction = 0.008). Dose⁻response effects showed an L-shaped curve between the total intake of five flavonoids and the risk of MetS. These results suggest that higher flavonoid intake is associated with a lower risk of MetS, especially under high levels of Cu intake.

Arsenic and/or copper caused inflammatory response via activation of inducible nitric oxide synthase pathway and triggered heat shock protein responses in testis tissues of chicken

The aim of this study is to investigate the effects of arsenic (As) and copper (Cu) on the inflammatory response, and the protective roles of heat shock proteins (Hsps) in chicken testes. Seventy-two 1-day-old male Hy-line chickens were treated with 30 mg/kg feed of arsenic trioxide (As₂O₃) and/or 300 mg/kg feed of copper sulfate (CuSO₄) for 4, 8, and 12 weeks. The histological changes, inducible nitric oxide synthase (iNOS) activity, and the expressions of Hsps and inflammatory cytokines were detected. The results showed that slight histology changes were obvious in the testis tissue exposure to treatment groups. The activity and the protein level of iNOS were increased compared to the control group. The mRNA levels of proinflammatory cytokines and inflammatory factors were increased as a whole. However, anti-inflammatory cytokines were inhibited. The mRNA and protein levels of Hsp60, Hsp70, and Hsp90 were upregulated. These results suggested that sub-chronic exposure to As and/or Cu induced testicular poisoning in chickens. Increased Hsps tried to protect chicken testis tissues from tissues damage caused by inflammation. In conclusion, testicular poisoning induced by As and/or Cu caused inflammatory response and heat shock protein response in chicken testis tissues.

Progressive Increases in Dietary Iron Are Associated with the Emergence of Pathologic Disturbances of Copper Homeostasis in Growing Rats

Background

Consumption of a high-iron diet causes copper deficiency in weanling rodents; however, the minimum amount of dietary iron that disrupts copper homeostasis has not been established.

Objective

We tested the hypothesis that dietary iron at only several-fold above physiologic requirements would cause copper depletion.

Methods

Weanling male Sprague-Dawley rats (n = 6/group) were fed AIN-93G-based diets with adequate (88 µg Fe/g = 1×), or excessive (4×, 9.5×, 18.5×, 38×, or 110×) iron content for 7 wk (110× group, due to notable morbidity) or 8 wk (all other groups). Copper-related physiologic parameters were then assessed.

Results

A hierarchy of copper-related, pathologic symptoms was noted as dietary iron concentrations increased. All statistical comparisons reported here refer to differences from the 1× (i.e., control) group. The highest iron concentration (110×) impaired growth (final body weights decreased ∼40%; P < 0.0001), and caused anemia (blood hemoglobin and hematocrit decreased ∼65%; P < 0.0001) and hepatic copper depletion (>85% reduction; P < 0.01). Cardiac hypertrophy occurred in the 110× (∼130% increase in mass; P < 0.0001) and 38× (∼25% increase; P < 0.05) groups, whereas cardiac copper content was lower in the 110× (P < 0.01), 38× (P < 0.01), and 18.5× (P < 0.05) groups (∼70% reductions). Splenic copper was also depleted in the 110× (>90% reduction; P < 0.0001), and in the 38× (P < 0.001) and 18.5× (P < 0.01) groups (∼70% reductions). Moreover, serum ceruloplasmin activity was decreased in the 110× and 38× (>90% reductions; P < 0.0001), and 18.5× (P < 0.001) and 9.5× (P < 0.05) (∼50% reductions) groups, typifying moderate to severe copper deficiency.

Conclusions

Increasing dietary iron intakes to ∼9.5-fold above dietary recommendations caused copper deficiency. Importantly, human iron supplementation is common, and recommended intakes for at-risk individuals may be ≤10-fold above the RDA. Whether these iron intakes perturb copper metabolism is worth considering, especially since copper defi-ciency can impair iron utilization (e.g., by decreasing the ferroxidase activity of ceruloplasmin).

Serum trace elements in insulin-dependent and non-insulin-dependent diabetes: a comparative study

BACKGROUND

Diabetes mellitus is associated with imbalance in body trace elements. The aim of the current investigation was to compare the levels of trace elements (Zn, Mg, Mn, Cu, Na, K, Fe, Ca, Cr, and Se) in insulin dependent (IDDM) and non-insulin dependent (NIDDM) diabetes.

METHODS

A total of 100 patients with diabetes (40 IDDM and 60 NIDDM) and 50 healthy subjects were recruited in the study from both genders. Biochemical measures include glucose, lipids, and HbA1C.

RESULTS

The results showed that Zn, Mg, Cu and Cr were significant lower in patients with diabetes compared to the control group (P<0.01). In addition, Zn and Cr were significantly lower in IDDM than NIDDM (P<0.05). Moreover, Zn and Mg levels were inversely correlated with HbA1c in IDDM and NIDDM (P<0.05). Zn was inversely correlated with fasting blood glucose in IDDM (P<0.05). Finally, no correlation between trace element levels with BMI was found (P>0.05).

CONCLUSION

Disturbance in trace element profile among IDDM and NIDDM is similar.

Zinc Oxide-Supported Copper Clusters with High Biocidal Efficacy for Escherichia coli and Bacillus cereus

Cu clusters on ZnO have been prepared by a simple low-temperature solid-state reaction from their respective acetate precursors. The formation of metallic Cu along with a small quantity of CuO was influenced by the presence of the zinc acetate precursor. Although there is a lack of formation of any metallic Cu in the absence of zinc acetate, increase in the heating duration helps in the formation of increased metallic Cu. A mechanism for formation of the Cu@ZnO nanocomposite has been suggested. The prepared Cu@ZnO nanocomposite, with metallic Cu, was identified by X-ray diffraction studies followed by confirmation of clusters of the kind Cu9 and Cu18 by transmission electron microscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The photoelectron spectroscopy is able to clearly distinguish the Cu from CuO, which is very well complimented by electron spin resonance analysis. The morphological feature of ZnO changes from flakes to rods on increasing the duration of heating, as shown by scanning electron microscopy (SEM) analysis. The observed Cu plasmonic band in UV-vis diffuse reflectance gets blue-shifted to 463 nm from its normally observed position of 550-580 nm possibly due to cluster formation and interaction with ZnO, the band gap of the latter getting red-shifted to 3.2-3.0 eV. The antibacterial activity of the synthesized Cu cluster-ZnO nanocomposites was investigated against Escherichia coli ATCC-25922 for Gram-negative and Bacillus cereus ATCC-10876 for Gram-positive bacteria. Tests were performed on a nutrient agar medium and liquid broth supplemented with different concentrations of nanoparticles. SEM analysis of the native and treated Gram-positive and Gram-negative bacteria established a high efficacy of biocide activity in 24 h, with 200 μg/mL of Cu@ZnO nanocomposites.

Fundamental Role of Methylenetetrahydrofolate Reductase 677 C → T Genotype and Flavin Compounds in Biochemical Phenotypes for Schizophrenia and Schizoaffective Psychosis

The Mental Health Biomarker Project (2010-2016) explored variables for psychosis in schizophrenia and schizoaffective disorder. Blood samples from 67, highly characterized symptomatic cases and 67 gender and age matched control participants were analyzed for methyl tetrahydrofolate reductase (MTHFR) 677C → T gene variants and for vitamin B6, B12 and D, folate, unbound copper, zinc cofactors for enzymes in the methylation cycle, and related catecholamine pathways. Urine samples were analyzed for indole-catecholamines, their metabolites, and oxidative-stress marker, hydroxylpyrolline-2-one (HPL). Rating scales were Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale, Global Assessment of Function scale, Clinical Global Impression (CGI) score, and Social and Occupational Functioning Assessment Scale (SOFAS). Analysis used Spearman's correlates, receiver operating characteristics and structural equation modeling (SEM). The correlative pattern of variables in the overall participant sample strongly implicated monoamine oxidase (MAO) enzyme inactivity so the significant role of MAO's cofactor flavin adenine nucleotide and its precursor flavin adenine mononucleotide (FMN) within the biochemical pathways was investigated and confirmed as 71% on SEM of the total sample. Splitting the data sets for MTHFR 677C → T polymorphism variants coding for the MTHFR enzyme, discovered that biochemistry variables relating to the wild-type enzyme differed markedly in pattern from those coded by the homozygous variant and that the hereozygous-variant pattern resembled the wild-type-coded pattern. The MTHFR 677C → T-wild and -heterozygous gene variants have a pattern of depleted vitamin cofactors characteristic of flavin insufficiency with under-methylation and severe oxidative stress. The second homozygous MTHFR 677TT pattern related to elevated copper:zinc ratio and a vitamin pattern related to flavin sufficiency and risk of over-methylation. The two gene variants and their different biochemical phenotypes govern findings in relationship to case-identification, illness severity, duration of illness, and functional disability in schizophrenia and schizoaffective psychosis, and establish a basis for trials of gene-guided precision treatment for the management of psychosis.

The Yin and Yang of copper during infection

Copper is an essential micronutrient for both pathogens and the animal hosts they infect. However, copper can also be toxic in cells due to its redox properties and ability to disrupt active sites of metalloproteins, such as Fe-S enzymes. Through these toxic properties, copper is an effective antimicrobial agent and an emerging concept in innate immunity is that the animal host intentionally exploits copper toxicity in antimicrobial weaponry. In particular, macrophages can attack invading microbes with high copper and this metal is also elevated at sites of lung infection. In addition, copper levels in serum rise during infection with a wide array of pathogens. To defend against this toxic copper, the microbial intruder is equipped with a battery of copper detoxification defenses that promote survival in the host, including copper exporting ATPases and copper binding metallothioneins. However, it is important to remember that copper is also an essential nutrient for microbial pathogens and serves as important cofactor for enzymes such as cytochrome c oxidase for respiration, superoxide dismutase for anti-oxidant defense and multi-copper oxidases that act on metals and organic substrates. We therefore posit that the animal host can also thwart pathogen growth by limiting their copper nutrients, similar to the well-documented nutritional immunity effects for starving microbes of essential zinc, manganese and iron micronutrients. This review provides both sides of the copper story and evaluates how the host can exploit either copper-the-toxin or copper-the-nutrient in antimicrobial tactics at the host-pathogen battleground.

Copper toxicology, oxidative stress and inflammation using zebrafish as experimental model

Copper is an essential micronutrient and a key catalytic cofactor in a wide range of enzymes. As a trace element, copper levels are tightly regulated and both its deficit and excess are deleterious to the organism. Under inflammatory conditions, serum copper levels are increased and trigger oxidative stress responses that activate inflammatory responses. Interestingly, copper dyshomeostasis, oxidative stress and inflammation are commonly present in several chronic diseases. Copper exposure can be easily modeled in zebrafish; a consolidated model in toxicology with increasing interest in immunity-related research. As a result of developmental, economical and genetic advantages, this freshwater teleost is uniquely suitable for chemical and genetic large-scale screenings, representing a powerful experimental tool for a whole-organism approach, mechanistic studies, disease modeling and beyond. Copper toxicological and more recently pro-inflammatory effects have been investigated in both larval and adult zebrafish with breakthrough findings. Here, we provide an overview of copper metabolism in health and disease and its effects on oxidative stress and inflammation responses in zebrafish models. Copper-induced inflammation is highlighted owing to its potential to easily mimic pro-oxidative and pro-inflammatory features that combined with zebrafish genetic tractability could help further in the understanding of copper metabolism, inflammatory responses and related diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Curcumin is a biologically active copper chelator with antitumor activity

BACKGROUND

Curcumin is a natural product with antitumor activity. The compound targets multiple cell signaling pathways, including cell survival and proliferation, caspase activation and oncogene expression. As a β-diketone, curcumin also exists as a keto-enol tautomer that chelates transition metal ions with high affinity.

PURPOSE

Copper has an integral role in promoting tumor growth and angiogenesis. This study aims to investigate whether curcumin exerts its antitumor activity through copper chelation.

METHODS

Copper chelation ability of curcumin was validated by measuring US/VIS spectrum. The antitumor activity and in vivo copper removal ability of curcumin was determined in a murine xenograft model. The effect of curcumin on copper-induced MAPK activation and cell proliferation was determined in cell culture system.

RESULTS

Administration of curcumin to tumor-bearing animals resulted in suppression of A549 xenograft growth, an effect that was also observed in animals treated with ammonium tetrathiomolybdate (TM), a metal chelator used for copper storage disorders clinically. The inhibition on tumor growth was associated with reduction of copper concentrations in the serum of treated groups. In cell culture studies, we showed that copper promoted cell proliferation through Erk/MAPK activation. Treatment with curcumin or U0126, a specific MAPK inhibitor, or suppression of cellular uptake of copper by siRNA knockdown of copper transporter protein 1 (CTR1) blocked copper-induced cell proliferation.

CONCLUSIONS

This study therefore demonstrates curcumin antitumor effect to its copper chelation capability. These results also implicate copper chelation as a general mechanism for their action of some biologically active polyphenols like flavonoids.

Subchronic exposure to leachate activates key markers linked with neurological disorder in Wistar male rat

The linking of various environmental chemicals exposure to neurodegenerative disorders is current. This study was undertaken to elucidate the toxic effects and the underlying biochemical mechanism of leachate obtained from Elewi Odo municipal battery recycling site (EOMABRL) using key markers of neuronal damage in rat via an oral route. Analysis of the concentrations of heavy metals showed that lead, cadmium, nickel, chromium, manganese, and iron were higher than the acceptable limits set by the regulatory authority-the World Health Organization. Whereas, copper, zinc, and cobalt were lower than permissible limits. EOMABRL was administered at 0, 20, 40, 60, 80, and 100% concentrations to adult male rats for 60 days. An in vitro study was also carried out in the cerebellum to assess cholinesterase biochemistry assays. Following exposure, brain was collected to determine the antioxidant status. EOMABRL administration significantly increased superoxide dismutase (SOD) and catalase (CAT) activities, and a sequential decrease in reduced glutathione (GSH) level with a concomitant increase in the accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) level was observed, when compared with the control. The treated rat had a significant (P < 0.05) increase in the activities of acetycholinesterase (AChE) and butyrylcholinesterase (BuChE). Taken together, these findings conclude that some possible mechanisms by which EOMABRL elicits neuronal disorder in male rat could be through the activation of AChE and BuChE and induction of oxidative stress with necrosis of neuronal cells.

Core domain mutant Y220C of p53 protein has a key role in copper homeostasis in case of free fatty acids overload

Nonalcoholic fatty liver disease (NAFLD) is a pathology that includes a wide variety of clinical conditions ranging from simple steatosis to end-stage liver diseases. Despite the huge amount of researches, the molecular basis of NAFLD are still not fully understood. Recently, it was suggested a role for p53 in NAFLD pathogenesis. Among its targets there is Synthesis of Cytochrome c Oxidase 2 (SCO2), a copper chaperone, involved in both aerobic respiration and metal cellular excretion. Copper seems to play a role in NAFLD. It was demonstrated a low hepatic copper content in NAFLD patients, which correlates with metabolic syndrome parameters. Copper homeostasis deregulation, in fact, seems to be related to lipid metabolism alteration and insulin resistance. Here we provide evidence on the role of p53 in the modulation of copper homeostasis, in an experimental model of NAFLD. We used two different hepatoma cell lines, HepG2 and Huh 7.5.1, characterized by the presence of wt p53 and its Y220C mutant, respectively, treated with a free fatty acids (FFAs) solution. Interestingly, p53 activation correlated with the intracellular copper level maintenance. We demonstrated that, in hepatoma cell lines, core domain mutant Y220C of p53 affects the modulation of SCO2 and Copper transporter 1 (CTR1), influencing, in this way, intracellular copper homeostasis in presence of FFAs accumulation, and that the 220 residue of the protein is crucial for such control. The role of p53 we highlighted may have deep implications in clinical conditions where copper homeostasis is deregulated.

The Potential Role of Iron and Copper in Pediatric Obesity and Nonalcoholic Fatty Liver Disease

Obesity is a rapidly growing health problem and is paralleled by a multitude of comorbidities, including nonalcoholic fatty liver disease (NAFLD). NAFLD has become the most common chronic liver disease in both adults and children. The current understanding of NAFLD is still fragmentary. While simple steatosis is characterized by the interplay between excessive free fatty acid accumulation and hepatic insulin resistance, the progression to NASH has been related to oxidative stress and a proinflammatory state with dysbalanced adipokine, cytokine levels, and endotoxin-mediated immune response. In addition, oxidative stress has been suggested to play a central role for the sequelae leading to NASH. Trace elements are critical in regulatory, immunologic, and antioxidant functions resulting in protection against inflammation and peroxidation and consequently against the known comorbidities of obesity. Disruptions of the metal detoxification processes located in the liver are plausibly related to NAFLD development via oxidative stress. Perturbations of iron and copper (Cu) homeostasis have been shown to contribute to the pathogenesis of NAFLD. This review presents current data from pediatric studies. In addition, data from adult studies are summarized where clinical relevance may be extrapolated to pediatric obesity and NAFLD.

Effect of 6-month caloric restriction on Cu bound to ceruloplasmin in adult overweight subjects

In a randomized clinical trial of calorie restriction (CR), we demonstrated that important cardiovascular disease (CVD) biomarkers were favorably influenced by CR alone and in conjunction with physical exercise. The aim of this study was to examine the effects of CR with or without exercise on copper bound to ceruloplasmin (CuCp), a well-known biomarker for CVD, in overweight men and women enrolled in the CALERIE phase 1 study. Forty-six individuals were randomized to one of four groups for 6 months: control, healthy weight maintenance; CR, 25% CR from baseline energy requirements; CR+exercise, 12.5% CR and 12.5% through aerobic exercise; and low-calorie diet, low-calorie diet until 15% reduction in body weight followed by weight maintenance diet. CuCp was determined in fasting blood samples by a high-performance liquid chromatography-inductively coupled plasma mass spectrometry methodology and compared with changes in body composition and markers of CVD. After 6 months, CR combined with exercise induced a decrease in plasma concentration of CuCp. CuCp was inversely correlated with insulin sensitivity at baseline and after 6 months of intervention. A cluster analysis showed that the percent change of weight after 6 months of intervention was the most important variable that could discriminate the intervention groups. The percent change of CuCp was the only other variable selected by the analysis. Decreased CuCp in overweight subjects by CR combined with exercise suggests a positive effect of this intervention on metabolic health. Further studies to explain the relationship between weight loss and CuCp and its relevance for cardiovascular health are needed.

The elements of life and medicines

Which elements are essential for human life? Here we make an element-by-element journey through the periodic table and attempt to assess whether elements are essential or not, and if they are, whether there is a relevant code for them in the human genome. There are many difficulties such as the human biochemistry of several so-called essential elements is not well understood, and it is not clear how we should classify elements that are involved in the destruction of invading microorganisms, or elements which are essential for microorganisms with which we live in symbiosis. In general, genes do not code for the elements themselves, but for specific chemical species, i.e. for the element, its oxidation state, type and number of coordinated ligands, and the coordination geometry. Today, the biological periodic table is in a position somewhat similar to Mendeleev's chemical periodic table of 1869: there are gaps and we need to do more research to fill them. The periodic table also offers potential for novel therapeutic and diagnostic agents, based on not only essential elements, but also non-essential elements, and on radionuclides. Although the potential for inorganic chemistry in medicine was realized more than 2000 years ago, this area of research is still in its infancy. Future advances in the design of inorganic drugs require more knowledge of their mechanism of action, including target sites and metabolism. Temporal speciation of elements in their biological environments at the atomic level is a major challenge, for which new methods are urgently needed.

Highly sensitive and selective chemosensors for Cu2+and Al3+based on photoinduced electron transfer (PET) mechanism

Two new fluorescent PET chemosensors were synthesised from an acridine core. The sensors can be used to monitor Cu²⁺and Al³⁺in CH₃CN. The detection limits for7a–Cu²⁺and7b–Al³⁺were calculated to be 2.8 × 10⁻⁷M and 5.8 × 10⁻⁷M, respectively.

Copper directs ATP7B to the apical domain of hepatic cells via basolateral endosomes

Physiologic Cu levels regulate the intracellular location of the Cu ATPase ATP7B. Here, we determined the routes of Cu-directed trafficking of endogenous ATP7B in the polarized hepatic cell line WIF-B and in the liver in vivo. Copper (10 µm) caused ATP7B to exit the trans-Golgi network (TGN) in vesicles, which trafficked via large basolateral endosomes to the apical domain within 1 h. Although perturbants of luminal acidification had little effect on the TGN localization of ATP7B in low Cu, they blocked delivery to the apical membrane in elevated Cu. If the vesicular proton-pump inhibitor bafilomycin-A1 (Baf) was present with Cu, ATP7B still exited the TGN, but accumulated in large endosomes located near the coverslip, in the basolateral region. Baf washout restored ATP7B trafficking to the apical domain. If ATP7B was staged apically in high Cu, Baf addition promoted the accumulation of ATP7B in subapical endosomes, indicating a blockade of apical recycling, with concomitant loss of ATP7B at the apical membrane. The retrograde pathway to the TGN, induced by Cu removal, was far less affected by Baf than the anterograde (Cu-stimulated) case. Overall, loss of acidification-impaired Cu-regulated trafficking of ATP7B at two main sites: (i) sorting and exit from large basolateral endosomes and (ii) recycling via endosomes near the apical membrane.