Long-term dietary exposure to copper in the population in Germany – Results from the BfR MEAL study

Sp4/HD11 and Sp1/HAT-p300 complexes induce apoptotic cell death in CuCl2-treated neurons by modulating histone acetylation on BCL-W and BAX promoters

Copper is a metal physiologically present in the brain that becomes neurotoxic at high concentrations; on the other hand, pharmacological inhibition of Histone Deacetylases (HDs) or of Histone Acetyltransferases (HATs) reduce neuronal death caused by several neurotoxicants. Herein, we found that CuCl2 (300 μM in SH-SY5Y cells or 100 μM in cortical neurons) determined apoptotic cell death, that was counteracted by the class IV HDs inhibitor Mocetinostat (MOCE) and by the HAT-p300 inhibitor C646, but not by the class I and II HDs inhibitors. Interestingly, HD11 and HAT-p300 protein levels increased after both 12 and 24 h of CuCl2 exposure and their silencing partially limited CuCl2-neurodetrimental effect. Furthermore, in CuCl2-treated cells the transcriptional factor Sp4 co-localized with HD11 on the promoter of anti-apoptotic gene BCL-W, determining histone H3 hypo-acetylation, a marker of gene repression. Contrarily, Sp1 co-localized with HAT-p300 on the pro-apoptotic gene BAX, determining histone H4 hyper-acetylation, a hallmark of transcriptional activation. In addition, siRNA against Sp4 prevented HD11 binding on BCL-W promoter and its consequent down-regulation, whereas Sp1 knocking-down, by reducing HAT-p300 interaction on BAX gene promoter counteracted its up-regulation. Importantly, while the single knocking-down of Sp1, Sp4, HD11 and HAT-p300 partially mitigated CuCl2-induced cell death, the double-transfection of siRNAs for Sp1 and Sp4, or for HD11 and HAT-p300, completely reverted the neurotoxic effect of CuCl2. Collectively, we found that CuCl2-induced neuronal apoptosis is determined by the binding of Sp1/HAT-p300 and of Sp4/HD11 transcriptional complexes on the BAX and BCL-W gene, respectively, unraveling a new pathway involved in Copper-induced neurotoxicity.

Levels of naturally occurring radionuclides in foods from the first German total diet study

Although natural radionuclides are always present in foods, information about the levels is scarce. The diet-related exposure to radiation is, however, dependent on the radionuclide content of respective food items. In this study, the levels of the naturally occurring radionuclides lead-210 (Pb-210), uranium-234 (U-234), uranium-238 (U-238), radium-226 (Ra-226) and radium-228 (Ra-228) were investigated in over 200 foods as part of the first German total diet study. Radioanalytical techniques and measurements were applied for determination. The natural radionuclide activity concentrations obtained were generally low compared to international data compilations. Together, Ra-228 and Ra-226 mostly dominated the levels of activity concentrations. Of all Ra-226, Ra-228 and Pb-210 results, between 1 % and 19 % exceeded the International Atomic Energy Agency (IAEA) guidance level for food products of 0.1 Bq/kg or 1 Bq/kg. The received activity levels for both U-234 and U-238 were found to be below the suggested IAEA guidance level of 10 Bq/kg. The radionuclide activity ratios of Ra-226/Ra-228, U-234/U-238 and Pb-210/Ra-226 of the foods were examined as well. In particular, it was found that the average Ra-226/Ra-228 ratio in all main food groups was substantially lower than the average Ra-226/Ra-228 ratio in soils. An isotope dependent transfer of Ra-226 and Ra-228 from soil to plants and foods is suggested to explain the difference. The obtained data set will be a valuable contribution to international data collections and thus help to a better understanding of the public exposure to natural radionuclides from the food consumption in the future.

Cu(II) detection by a fluorometric probe based on thiazoline-amidoquinoline derivative and its application to water and food samples

Two novel fluorescent probes for Cu2+ detection have been developed based on thiazoline-quinoline conjugates bearing a 4-ethynyl-N,N-dimethylaniline unit (QT1 and QT2). QT2 exhibits instantaneous fluorescence quenching of Cu2+ with an emissive change from bright orange to arctic blue under UV light irradiation (365 nm). The plots of I0/I against Cu2+ concentrations show a good linear relationship that ranges from 0 to 50 µM with a coefficient of determination (R2) = 0.9906 and a limit of detection (LOD) of 76 nM, which is considered low (4.84 ppb). A 1:1 complexation between QT2 and Cu2+ was confirmed by UV-Vis titration, ESI-MS, and SC-XRD. The QT2·Cu2+ complex was dissociated by the addition of EDTA. The fluorescence quenching mechanism involves the ligand-to-metal charge transfer (LMCT) of a paramagnetic Cu2+ complex. The QT2 probe on a paper-based strip was used to determine the amount of Cu2+ in water and food samples (shiitake mushrooms and oysters).

Determination of copper status by five biomarkers in serum of healthy women

BACKGROUND

The essential trace element copper is relevant for many important physiological processes. Changes in copper homeostasis can result from disease and affect human health. A reliable assessment of copper status by suitable biomarkers may enable fast detection of subtle changes in copper metabolism. To this end, additional biomarkers besides serum copper and ceruloplasmin (CP) concentrations are required.

OBJECTIVES

The aim of this study was to investigate the emerging copper biomarkers CP oxidase (CPO) activity, exchangeable copper (CuEXC) and labile copper in serum of healthy women and compare them with the conventional biomarkers total serum copper and CP.

METHOD AND MAIN FINDINGS

This observational study determined CPO activity, the non CP-bound copper species CuEXC and labile copper, total serum copper and CP in sera of 110 healthy women. Samples were collected at four time points over a period of 24 weeks. The concentrations of total serum copper and CP were within the reference ranges. The comparison of all five biomarkers provided insight into their relationship, the intra- and inter-individual variability as well as the age dependence. The correlation and Principal Component Analyses (PCA) indicated that CP, CPO activity and total copper correlated well, followed by CuEXC, while the labile copper pool was unrelated to the other parameters.

CONCLUSIONS

This study suggests that the non-CP-bound copper species represent copper pools that are differently regulated from total copper or CP-bound copper, making them interesting complementary biomarkers to enable a more complete assessment of body copper status with potential relevance for clinical application.

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

Wilson Disease: Copper-Mediated Cuproptosis, Iron-Related Ferroptosis, and Clinical Highlights, with Comprehensive and Critical Analysis Update

Wilson disease is a genetic disorder of the liver characterized by excess accumulation of copper, which is found ubiquitously on earth and normally enters the human body in small amounts via the food chain. Many interesting disease details were published on the mechanistic steps, such as the generation of reactive oxygen species (ROS) and cuproptosis causing a copper dependent cell death. In the liver of patients with Wilson disease, also, increased iron deposits were found that may lead to iron-related ferroptosis responsible for phospholipid peroxidation within membranes of subcellular organelles. All topics are covered in this review article, in addition to the diagnostic and therapeutic issues of Wilson disease. Excess Cu2+ primarily leads to the generation of reactive oxygen species (ROS), as evidenced by early experimental studies exemplified with the detection of hydroxyl radical formation using the electron spin resonance (ESR) spin-trapping method. The generation of ROS products follows the principles of the Haber-Weiss reaction and the subsequent Fenton reaction leading to copper-related cuproptosis, and is thereby closely connected with ROS. Copper accumulation in the liver is due to impaired biliary excretion of copper caused by the inheritable malfunctioning or missing ATP7B protein. As a result, disturbed cellular homeostasis of copper prevails within the liver. Released from the liver cells due to limited storage capacity, the toxic copper enters the circulation and arrives at other organs, causing local accumulation and cell injury. This explains why copper injures not only the liver, but also the brain, kidneys, eyes, heart, muscles, and bones, explaining the multifaceted clinical features of Wilson disease. Among these are depression, psychosis, dysarthria, ataxia, writing problems, dysphagia, renal tubular dysfunction, Kayser-Fleischer corneal rings, cardiomyopathy, cardiac arrhythmias, rhabdomyolysis, osteoporosis, osteomalacia, arthritis, and arthralgia. In addition, Coombs-negative hemolytic anemia is a key feature of Wilson disease with undetectable serum haptoglobin. The modified Leipzig Scoring System helps diagnose Wilson disease. Patients with Wilson disease are well-treated first-line with copper chelators like D-penicillamine that facilitate the removal of circulating copper bound to albumin and increase in urinary copper excretion. Early chelation therapy improves prognosis. Liver transplantation is an option viewed as ultima ratio in end-stage liver disease with untreatable complications or acute liver failure. Liver transplantation finally may thus be a life-saving approach and curative treatment of the disease by replacing the hepatic gene mutation. In conclusion, Wilson disease is a multifaceted genetic disease representing a molecular and clinical challenge.

Insights Into the Role of Copper in Neurodegenerative Diseases and the Therapeutic Potential of Natural Compounds

Neurodegenerative diseases encompass a collection of neurological disorders originating from the progressive degeneration of neurons, resulting in the dysfunction of neurons. Unfortunately, effective therapeutic interventions for these diseases are presently lacking. Copper (Cu), a crucial trace element within the human body, assumes a pivotal role in various biological metabolic processes, including energy metabolism, antioxidant defense, and neurotransmission. These processes are vital for the sustenance, growth, and development of organisms. Mounting evidence suggests that disrupted copper homeostasis contributes to numerous age-related neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), Wilson's disease (WD), Menkes disease (MD), prion diseases, and multiple sclerosis (MS). This comprehensive review investigates the connection between the imbalance of copper homeostasis and neurodegenerative diseases, summarizing pertinent drugs and therapies that ameliorate neuropathological changes, motor deficits, and cognitive impairments in these conditions through the modulation of copper metabolism. These interventions include Metal-Protein Attenuating Compounds (MPACs), copper chelators, copper supplements, and zinc salts. Moreover, this review highlights the potential of active compounds derived from natural plant medicines to enhance neurodegenerative disease outcomes by regulating copper homeostasis. Among these compounds, polyphenols are particularly abundant. Consequently, this review holds significant implications for the future development of innovative drugs targeting the treatment of neurodegenerative diseases.