Metallothionein: an intracellular protein to protect against cadmium toxicity

Distinct Stress Regulators in the CRL Family: Emerging Roles of F-Box Proteins: Cullin-RING Ligases and Stress-Sensing

Cullin-RING ligases (CRLs) are central regulators of environmental and cellular stress responses, orchestrating diverse processes through the ubiquitination of substrate proteins. As modular complexes, CRLs employ substrate-specific adaptors to target proteins for degradation and other ubiquitin-mediated processes, enabling dynamic adaptation to environmental cues. Recent advances have highlighted the largest CRL subfamily SCF (Skp1-cullin-F-box) in environmental sensing, a role historically underappreciated for SCF ubiquitin ligases. Notably, emerging evidence suggests that the F-box domain, a 50-amino acid motif traditionally recognized for mediating protein-protein interactions, can act as a direct environmental sensor due to its ability to bind heavy metals. Despite these advances, the roles of many CRL components in environmental sensing remain poorly understood. This review provides an overview of CRLs in stress response regulation and emphasizes the emerging functions of F-box proteins in environmental adaptation.

Oral Supplementation with Modified Natural Clinoptilolite Protects Against Cadmium Toxicity in ICR (CD-1) Mice

For the first time, this study investigates in vivo the potential of Na-modified natural clinoptilolite to mitigate cadmium toxicity in ICR mice, a model relevant to human health. We enhanced natural clinoptilolite to improve its cadmium (Cd) exchange capacity. Mice were exposed to environmentally realistic cadmium nitrate Cd(NO3)2 doses in their drinking water. The detoxification efficacy of the mineral was evaluated over 45 days in four groups: control (no supplementation), Cd(NO3)2 only, clinoptilolite only, and a combination of Cd(NO3)2 and clinoptilolite. We assessed Cd bioaccumulation in the liver and kidneys, genotoxicity (micronucleus assay), hematological parameters, and oxidative stress markers. Cd exposure resulted in significant bioaccumulation, reduced growth, changes in erythrograms, DNA damage, and oxidative stress. Mice receiving clinoptilolite alone showed a significant increase in body mass. Modified clinoptilolite led to a nearly 48% reduction in Cd accumulation and a 30% increase in Cd excretion in the Cd-plus-clinoptilolite group compared to the Cd-only group. Erythrogram and leukogram parameters returned to near-normal levels, with reductions in malondialdehyde (MDA) and increases in glutathione (GSH) observed by the end of the experiment. No elevated levels of micronuclei were found following clinoptilolite supplementation. These results suggest that modified clinoptilolite may be a cost-effective detoxifier in Cd-polluted regions.

Cadmium-Induced Kidney Apoptosis Based on the IRE1α-XBP1 Signaling Pathway and the Protective Effect of Quercetin

Cadmium (Cd) is an important environmental pollutant that can enter the body and inflict kidney damage. Quercetin (Que) is a natural flavonoid compound that can alleviate kidney damage in Cd-treated rats, but the specific mechanism is unclear. Herein, 24 male Sprague-Dawley rats were divided into four groups, namely the control, Cd, Cd + Que, and Que groups. Four weeks later, the rats were anesthetized with ether and were euthanized; then, their blood was collected and their kidneys were removed. Renal function markers were measured. Kidney tissue structure was observed by HE staining, cell apoptosis was detected by the TUNEL method, and mRNA and protein expression levels in the IRE1α-XBP1 apoptosis signaling pathway were analyzed by RT-PCR and Western blotting. Results showed that the Cd treatment group exhibited decreased renal dysfunction and pathologic injury. Cd-induced tissue damage and cell apoptosis and significantly increased the mRNA and protein expression levels (p < 0.01) related to the IRE1α-XBP1 signaling pathway. Compared with the Cd group, the Cd + Que group exhibited increased renal dysfunction. Conversely, kidney tissue damage and renal cell apoptosis decreased, and the mRNA and protein expression levels of IRE1α and XBP1 significantly decreased (p < 0.01). Cd treatment inflicted renal damage. Therefore, Que can restore the kidney tissue damage and alleviate the cell apoptosis caused by Cd through the inhibition of the IRE1α-XBP1 signaling pathway.

Screening Methods to Discover the FDA-Approved Cancer Drug Encorafenib as Optimally Selective for Metallothionein Gene Loss Ovarian Cancer

BACKGROUND/OBJECTIVES

All 11 metallothionein protein-coding genes are located on human chromosome 16q13. It is unique among human genetics to have an entire pathway's genes clustered in a short chromosomal region. Since solid tumors, particularly high-grade serous ovarian cancer (HGSC), exhibit high rates of monoallelic aneuploidy, this region is commonly lost. Studies have not yet been performed to determine what vulnerability may be created in cancer cells with low metallothionein expression. Here, a screen of FDA-approved cancer small molecule drugs for those best targeting low metallothionein ovarian cancer was completed.

METHODS

Screening methods were tested and compared using vehicle-treated negative controls and cadmium chloride, a positive control for cell loss selective for low metallothionein cells. CAOV3 cells, which are unique in their expression of only two metallothionein isoforms, were used, with or without shRNA knockdown of the predominantly expressed MT2A gene. A library of FDA-approved molecules was then screened.

RESULTS

The optimal assay utilized Hoechst 33342 nuclear staining and mechanized fluorescent microscope counting of cell content. Encorafenib, an RAF inhibitor, was identified as the most selective for enhanced cytotoxicity in MT2A knockdown cells compared to scrambled controls.

CONCLUSIONS

The nuclear stain Hoechst 33342, assessed by fluorescence microscopy, provides a low variance, moderate throughput platform for cancer cell loss screens. Low metallothionein ovarian cancer cells exhibit a vulnerability to the RAF inhibitor encorafenib.

Metallothioneins: an unraveling insight into remediation strategies of plant defense mechanisms

Phytoremediation is an eco-friendly, sustainable way to clean up the environment using green plants that effectively remove and degrade pollutants from soil, water, or air. Certain hyperaccumulator plants can effectively mitigate heavy metals, organic compounds, and radioactive substances through absorption, adsorption, and transformation. This method offers a cost-effective and esthetically pleasing alternative to traditional remediation techniques, contributing to the restoration of contaminated ecosystems. Nanophytoremediation entails combining nanotechnology with phytoremediation techniques to improve plant-based environmental cleanup efficiency. Nanoparticles (NPs) or engineered NPs are applied to improve plants' absorption and transport of contaminants. This approach addresses limitations in traditional phytoremediation, offering increased remediation rates and effectiveness, particularly in removing pollutants like heavy metals. This review paper compares traditional phytoremediation and emerging nanophytoremediation, emphasizing their impact on metallothionein proteins in plants. The work reveals how plants get rid of unwanted foreign substances that build up on their bodies and keep homeostasis by using metallothionein proteins. These proteins effectively reduce the effects of these substances without affecting the plant's normal growth. The efficiency, cost-effectiveness, and ecological implications of the phytoremediation technologies in the light of the metallothionein protein action provide insights into optimizing contaminant detoxification strategies for polluted environments.

E-waste in the environment: Unveiling the sources, carcinogenic links, and sustainable management strategies

E-waste refers to the electrical and electronic equipment discarded without the intent of reuse or at the end of its functional lifespan. In 2022, approximately 62 billion kg of e-waste, equivalent to 7.8 kg per capita, was generated globally. With an alarming annual growth of approximately 2 million metric tonnes, e-waste production may exceed 82 billion kg by 2030. Improper disposal of e-waste can be detrimental to human health and the entire biosphere. E-waste encompasses a wide range of materials, including heavy metals, Polychlorinated Biphenyls (PCBs), Per- and Polyfluoroalkyl Substances (PFAS), Polycyclic Aromatic Hydrocarbons (PAHs), Polychlorinated Dibenzo-dioxins and -furans (PCDD/Fs), Polybrominated Diphenyl Ethers (PBDEs), and radioactive elements. E-waste, when disposed inappropriately can directly contaminate the aquatic and terrestrial environment, leading to human exposure through ingestion, inhalation, dermal absorption, and trans-placental transfer. These detrimental contaminants can directly enter the human body from the environment and may fuel carcinogenesis by modulating cell cycle proteins, redox homeostasis, and mutations. Heavy metals such as cadmium, mercury, arsenic, lead, chromium, and nickel, along with organic pollutants like PAHs, PCBs, PBDEs, PFAS, and radioactive elements, play a crucial role in inducing malignancy. Effective collection, sorting, proper recycling, and appropriate disposal techniques are essential to reduce environmental contamination with e-waste-derived chemicals. Hence, this comprehensive review aims to unravel the global environmental burden of e-waste and its links to carcinogenesis in humans. Furthermore, it provides an inclusive discussion on potential treatment approaches to minimize environmental e-waste contamination.

Exploring protein natural diversity in environmental microbiomes with DeepMetagenome

Protein natural diversity offers a vast sequence space for protein engineering, and deep learning enables its detection from metagenomes/proteomes without prior assumptions. DeepMetagenome, a Python-based method, explores protein diversity through modules for training and analyzing sequence datasets. The deep learning model includes Embedding, Conv1D, LSTM, and Dense layers, with sequence feature analysis for data cleaning. Applied to metallothioneins from a database of over 146 million coding features, DeepMetagenome identified over 500 high-confidence metallothionein sequences, outperforming DIAMOND and CNN-based models. It showed stable performance compared to a Transformer-based model over 25 epochs. Among 23 synthesized sequences, 20 exhibited metal resistance. The tool also successfully explored the diversity of three additional protein families and is freely available on GitHub with detailed instructions.

Factors affecting the concentration of metals and metalloids in the kidneys of a top predator, the Eurasian Buzzard (Buteo buteo) wintering in farmland in Poland

During late autumn and winter, raptors in the western Palearctic face challenges due to food scarcity and dropping temperatures. That time they can be exposed to various elements including toxic ones ingested with food. Kidney samples from 22 females and 19 males of a medium-sized raptor, the Common Buzzard Buteo buteo found dead in farmland of Eastern Poland in winter were analyzed for a concentration of 21 elements. Elemental concentrations were analyzed regarding the age and sex of birds. Results revealed that only 4.9% of individuals had kidney lead levels exceeding 8.0 mg, while 9.8% showed cadmium levels above 8.0 mg/kg, indicating potential poisoning. The study also highlighted the limited entry of arsenic into agricultural ecosystems exploited by Common Buzzards. Sex differences were noted, with females accumulating more lead and vanadium than males which can be associated with foraging niche partitioning between sexes driven by body size dimorphism. Sulfur showed complex interactions with cadmium, mercury, and zinc, with a positive correlation between sulfur and zinc levels in the kidneys, emphasizing dietary needs during food scarcity. A positive correlation was found between zinc and lead concentrations, indicating zinc's role in mitigating lead's impact. The study also revealed positive correlations between selenium and highly toxic elements like mercury (Spearman correlation, rs = 0.41) and cadmium (rs = 0.51), suggesting a mitigating effect of selenium on exposure to heavy metals. This study enhances understanding of year-round environmental contamination exposure for raptors and sheds light on bioaccumulation in a top predator.

Positions of cysteine residues reveal local clusters and hidden relationships to Sequons and Transmembrane domains in Human proteins

Membrane proteins often possess critical structural features, such as transmembrane domains (TMs), N-glycosylation, and disulfide bonds (SS bonds), which are essential to their structure and function. Here, we extend the study of the motifs carrying N-glycosylation, i.e. the sequons, and the Cys residues supporting the SS bonds, to the whole human proteome with a particular focus on the Cys positions in human proteins with respect to those of sequons and TMs. As the least abundant amino acid residue in protein sequences, the positions of Cys residues in proteins are not random but rather selected through evolution. We discovered that the frequency of Cys residues in proteins is length dependent, and the frequency of CC gaps formed between adjacent Cys residues can be used as a classifier to distinguish proteins with special structures and functions, such as keratin-associated proteins (KAPs), extracellular proteins with EGF-like domains, and nuclear proteins with zinc finger C2H2 domains. Most importantly, by comparing the positions of Cys residues to those of sequons and TMs, we discovered that these structural features can form dense clusters in highly repeated and mutually exclusive modalities in protein sequences. The evolutionary advantages of such complementarity among the three structural features are discussed, particularly in light of structural dynamics in proteins that are lacking from computational predictions. The discoveries made here highlight the sequence-structure-function axis in biological organisms that can be utilized in future protein engineering toward synthetic biology.

A multi-domain snail metallothionein increases cadmium resistance and fitness in Caenorhabditis elegans

Metallothioneins (MTs) are a family of mostly low-molecular weight, cysteine-rich proteins capable of specific metal-ion binding that are involved in metal detoxification and homeostasis, as well as in stress response. In contrast to most other animal species which possess two-domain (bidominial) MTs, some gastropod species have evolved Cd2+-selective multidomain MTs (md-MTs) consisting of several concatenated β3 domains and a single C-terminal β1 domain. Each domain contains three-metal ion clusters and binds three metal ions. The terrestrial snail Alinda biplicata possesses, among other MT isoforms, an md-MT with nine β3 domains and a C-terminal β1 domain (termed 10md-MT), capable of binding up to 30 Cd2+ ions per protein molecule. In the present study, the Alinda biplicata 10md-MT gene and a truncated version consisting of one β3 domain and a single C-terminal β1 domain (2d-MT) were introduced into a Caenorhabditis elegans knock-out strain lacking a native MT gene (mtl-1). The two snail MT constructs consistently increased Cd2+ resistance, and partially improved morphological, life history and physiological fitness traits in the nematode model host Caenorhabditis elegans. This highlights how the engineering of transgenic Caenorhabditis elegans strains expressing snail MTs provides an enhancement of the innate metal detoxification mechanism and in doing so provides a platform for enhanced mechanistic toxicology.

Epigenetic alterations in bioaccumulators of cadmium: Lessons from mammalian kidneys and plants

Faced with unpredictable changes in global weather patterns, release and redistribution of metals through land erosion and water movements add to the increasing use of metals in industrial activities causing high levels of environmental pollution and concern to the health of all living organisms. Cadmium is released into the environment by smelting and mining, entering the food chain via contaminated soils, water, and phosphate fertilizers. Bioaccumulation of cadmium in plants represents the first major step into the human food chain and contributes to toxicity of several organs, especially the kidneys, where biomagnification of cadmium occurs over decades of exposure. Even in small amounts, cadmium brings about alterations at the molecular and cellular levels in eukaryotes through mutagenicity, molecular mimicry at metal binding sites and oxidative stress. The epigenome dictates expression of a gene's output through a number of regulatory steps involving chromatin remodeling, nucleosome unwinding, DNA accessibility, or nucleic acid modifications that ultimately impact the transcriptional and translational machinery. Several epigenetic enzymes exhibit zinc-dependence as zinc metalloenzymes and zinc finger proteins thus making them susceptible to deregulation through displacement by cadmium. In this review, we summarize the literature on cadmium-induced epigenetic mechanisms in mammalian kidneys and plants, compare similarities in the epigenetic defense between these bioaccumulators, and explore how future studies could advance our understanding of the cadmium-induced stress response and disruption to biological health.

Insight into the mechanisms of combined toxicity of cadmium and flotation agents in luminescent bacteria: Role of micro/nano particles

Currently, risk assessment and pollution management in mines primarily focus on toxic metals, with the flotation agents being overlooked. However, the combined effects of metals and flotation agents in mines remain largely unknown. Therefore, this study aimed to evaluate the combined effects of Cd and two organic flotation agents (ethyl xanthate (EX) and diethyldithiocarbamate (DDTC)), and the associated mechanisms. The results showed that Cd + EX and Cd + DDTC exhibited synergistic toxicity. The EC50 values for luminescent bacteria were 1.6 mg/L and 1.0 mg/L at toxicity unit ratios of 0.3 and 1, respectively. The synergistic effects were closely related with the formation of Cd(EX)2 and Cd(DDTC)2 micro/nano particles, with nano-particles exhibiting higher toxicity. We observed severe cell membrane damage and cell shrinkage of the luminescent bacteria, which were probably caused by secondary harm to cells through the released CS2 during their decomposition inside cells. In addition, these particles induced toxicity by altering cellular levels of biochemical markers and the transcriptional levels of transport proteins and lipoproteins, leading to cell membrane impairment and DNA damage. This study has demonstrated that particulates formed by Cd and flotation agents contribute to the majority of the toxicity of the binary mixture. This study helps to better understand the complex ecological risk of inorganic metals and organic flotation agents in realistic mining environments.

HIF1 activation safeguards cortical bone formation against impaired oxidative phosphorylation

Energy metabolism, through pathways such as oxidative phosphorylation (OxPhos) and glycolysis, plays a pivotal role in cellular differentiation and function. Our study investigates the impact of OxPhos disruption in cortical bone development by deleting mitochondrial transcription factor A (TFAM). TFAM controls OxPhos by regulating the transcription of mitochondrial genes. The cortical bone, constituting the long bones' rigid shell, is sheathed by the periosteum, a connective tissue layer populated with skeletal progenitors that spawn osteoblasts, the bone-forming cells. TFAM-deficient mice presented with thinner cortical bone, spontaneous midshaft fractures, and compromised periosteal cell bioenergetics, characterized by reduced ATP levels. Additionally, they exhibited an enlarged periosteal progenitor cell pool with impaired osteoblast differentiation. Increasing hypoxia-inducible factor 1a (HIF1) activity within periosteal cells substantially mitigated the detrimental effects induced by TFAM deletion. HIF1 is known to promote glycolysis in all cell types. Our findings underscore the indispensability of OxPhos for the proper accrual of cortical bone mass and indicate a compensatory mechanism between OxPhos and glycolysis in periosteal cells. The study opens new avenues for understanding the relationship between energy metabolism and skeletal health and suggests that modulating bioenergetic pathways may provide a therapeutic avenue for conditions characterized by bone fragility.

Vitamin D and Toxic Metals in Pregnancy - a Biological Perspective

Purpose of Review

To discuss the potential biological mechanisms between vitamin D and toxic metals and summarize epidemiological studies examining this association in pregnant women.

Recent Findings

We identified four plausible mechanisms whereby vitamin D and toxic metals may interact: nephrotoxicity, intestinal absorption of metals, endocrine disruption, and oxidative stress. Few studies have examined the association between vitamin D and toxic metals in pregnant women. North American studies suggest that higher vitamin D status early in pregnancy are associated with lower blood metals later in pregnancy. However, a trial of vitamin D supplementation in a pregnant population, with higher metal exposures and lower overall nutritional status, does not corroborate these findings.

Summary

Given ubiquitous exposure to many toxic metals, nutritional intervention could be a means for prevention of adverse outcomes. Future prospective studies are needed to establish a causal relationship and clarify the directionality of vitamin D and metals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40471-024-00348-0.

Immunogenetic and Environmental Factors in Age-Related Macular Disease

Age-related macular degeneration (AMD) is a chronic disease, which often develops in older people, but this is not the rule. AMD pathogenesis changes include the anatomical and functional complex. As a result of damage, it occurs, in the retina and macula, among other areas. These changes may lead to partial or total loss of vision. This disease can occur in two clinical forms, i.e., dry (progression is slowly and gradually) and exudative (wet, progression is acute and severe), which usually started as dry form. A coexistence of both forms is possible. AMD etiology is not fully understood. Extensive genetic studies have shown that this disease is multifactorial and that genetic determinants, along with environmental and metabolic-functional factors, are important risk factors. This article reviews the impact of heavy metals, macro- and microelements, and genetic factors on the development of AMD. We present the current state of knowledge about the influence of environmental factors and genetic determinants on the progression of AMD in the confrontation with our own research conducted on the Polish population from Kuyavian-Pomeranian and Lubusz Regions. Our research is concentrated on showing how polluted environments of large agglomerations affects the development of AMD. In addition to confirming heavy metal accumulation, the growth of risk of acute phase factors and polymorphism in the genetic material in AMD development, it will also help in the detection of new markers of this disease. This will lead to a better understanding of the etiology of AMD and will help to establish prevention and early treatment.

Metals and metallothionein evolution in snails: a contribution to the concept of metal-specific functionality from an animal model group

This is a critical review of what we know so far about the evolution of metallothioneins (MTs) in Gastropoda (snails, whelks, limpets and slugs), an important class of molluscs with over 90,000 known species. Particular attention will be paid to the evolution of snail MTs in relation to the role of some metallic trace elements (cadmium, zinc and copper) and their interaction with MTs, also compared to MTs from other animal phyla. The article also highlights the important distinction, yet close relationship, between the structural and metal-selective binding properties of gastropod MTs and their physiological functionality in the living organism. It appears that in the course of the evolution of Gastropoda, the trace metal cadmium (Cd) must have played an essential role in the development of Cd-selective MT variants. It is shown how the structures and Cd-selective binding properties in the basal gastropod clades have evolved by testing and optimizing different combinations of ancestral and novel MT domains, and how some of these domains have become established in modern and recent gastropod clades. In this context, the question of how adaptation to new habitats and lifestyles has affected the original MT traits in different gastropod lineages will also be addressed. The 3D structures and their metal binding preferences will be highlighted exemplarily in MTs of modern littorinid and helicid snails. Finally, the importance of the different metal requirements and pathways in snail tissues and cells for the shaping and functionality of the respective MT isoforms will be shown.

A Potential Involvement of Metallothionein in the Zinc Tolerance of Trichoderma harzianum: Experimental Findings

Metallothioneins are a group of cysteine-rich proteins that play an important role in the homeostasis and detoxification of heavy metals. The objective of this research was to explore the significance of metallothionein in Trichoderma harzianum tolerance to zinc. At the inhibitory concentration of 1000 ppm, the fungus adsorbed 16.7 ± 0.4 mg/g of metal. The HPLC and SDS-PAGE electrophoresis data suggested that the fungus production of metallothionein was twice as high in the presence of zinc as in the control group. The examination of the genes; metallothionein expression activator (MEA) and Cu fist revealed that the MEA, with a C2H2 zinc finger domain, increased significantly in the presence of zinc. It was observed that in T. harzianum, the enhanced expression of the metallothionein gene was managed by the metallothionein activator under zinc overload conditions. According to our knowledge, this is the first report on the role of metallothionein in the resistance of T. harzianum to zinc.

Cadmium toxicity and autophagy: a review

Cadmium (Cd) is an important environmental pollutant that poses a threat to human health and represents a critical component of air pollutants, food sources, and cigarette smoke. Cd is a known carcinogen and has toxic effects on the environment and various organs in humans. Heavy metals within an organism are difficult to biodegrade, and those that enter the respiratory tract are difficult to remove. Autophagy is a key mechanism for counteracting extracellular (microorganisms and foreign bodies) or intracellular (damaged organelles and proteins that cannot be degraded by the proteasome) stress and represents a self-protective mechanism for eukaryotes against heavy metal toxicity. Autophagy maintains cellular homeostasis by isolating and gathering information about foreign chemicals associated with other molecular events. However, autophagy may trigger cell death under certain pathological conditions, including cancer. Autophagy dysfunction is one of the main mechanisms underlying Cd-induced cytotoxicity. In this review, the toxic effects of Cd-induced autophagy on different human organ systems were evaluated, with a focus on hepatotoxicity, nephrotoxicity, respiratory toxicity, and neurotoxicity. This review also highlighted the classical molecular pathways of Cd-induced autophagy, including the ROS-dependent signaling pathways, endoplasmic reticulum (ER) stress pathway, Mammalian target of rapamycin (mTOR) pathway, Beclin-1 and Bcl-2 family, and recently identified molecules associated with Cd. Moreover, research directions for Cd toxicity regarding autophagic function were proposed. This review presents the latest theories to comprehensively reveal autophagy behavior in response to Cd toxicity and proposes novel potential autophagy-targeted prevention and treatment strategies for Cd toxicity and Cd-associated diseases in humans.

Overexpression of Lias Gene Alleviates Cadmium-Induced Kidney Injury in Mice Involving Multiple Effects: Metabolism, Oxidative Stress, and Inflammation

Oxidative stress is an important mechanism underlying toxicity induced by cadmium (Cd) exposure. However, there are significant differences of the antioxidant baseline in different populations. This means that different human has different intensity of oxidative stress in vivo after exposure to toxicants. LiasH/H mouse is a specific model which is created by genetically modifying the Lias 3'-untranslated region (3'-UTR). LiasH/H mice express high levels of LA and have high endogenous antioxidant capacity which is approximately 150% higher than wild-type C57BL/6 J mice (WT, Lias+/+). But more importantly, they have dual roles of metal chelator and antioxidant. Here, we applied this mouse model to evaluate the effect of endogenous antioxidant levels in the body on alleviating Cd-induced renal injury including Cd metabolism, oxidative stress, and inflammation. In the experiment, mice drank water containing Cd (50 mg/L), for 12 weeks. Many biomarkers of Cd metabolism, oxidative stress, inflammation, and major pathological changes in the kidney were examined. The results showed overexpression of the Lias gene decreased Cd burden in the body of mice, mitigated oxidative stress, attenuated the inflammatory response, and subsequent alleviated cadmium-induced kidney injury in mice.

Reversal Effects of Royal Jelly and Propolis Against Cadmium-Induced Hepatorenal Toxicity in Rats

Heavy metal toxicity is an exponentially growing health problem. In this study, we aimed to assess the protective properties of propolis and royal jelly against cadmium adverse effects. Thirty-two adult male rats were included in our study; kidney and liver functions, histopathological changes, and the level of oxidative stress were evaluated in rats exposed to a daily dose of 4.5 mg cadmium per kilogram of body weight for 1 month and those cotreated simultaneously with either propolis (50 mg/kg/day) or royal jelly (200 mg/kg/day) with cadmium compared to control animals. Cadmium-mediated hepatorenal toxicity was manifested as per the increased oxidative stress, function deterioration, and characteristic histopathological aberrations. The supplementation of royal jelly or propolis restores most of the affected parameters to a level similar to the control group. However, the parameters describing the grade of DNA damage and the interleukin-1β expression in the liver, as well as the levels of malondialdehyde and metallothionein, were slightly elevated compared to controls, despite the regular use of royal jelly or propolis. It is worth noting that better results were found in the case of royal jelly compared to propolis administration. Most likely, the ability of both products to chelate cadmium and contribute in reducing oxidative stress is of great importance. However, further investigations are needed to complement the knowledge about the expected nutritional and medicinal values.

Protective effect of quercetin on cadmium-induced kidney apoptosis in rats based on PERK signaling pathway

BACKGROUND

Cadmium (Cd) is a highly toxic environmental pollutant that can enter the body through bioaccumulation. The kidney is an important target organ for Cd poisoning. Quercetin (Que) is a natural flavonoid compound with free radical scavenging and antioxidant properties. Previous studies showed that Que can alleviate kidney damage caused by Cd poisoning in rats, but the specific mechanism is still unclear.

METHODS

Twenty-four male Sprague-Dawley (SD) rats were divided into four groups: normal saline-treated control group, Cd group treated by intraperitoneal injection of 2 mg/kg b.w. CdCl2, Cd + Que group treated by intraperitoneal injection of 2 mg/kg b.w. CdCl2 and 100 mg/kg b.w. Que, and Que group treated by 100 mg/kg b.w. Que. Four weeks later, the rats were anesthetized with diethyl ether, and blood was taken intravenously. The rats were executed with their necks cut off, and the kidneys were removed. Body weight, kidney organ weight, and glutathione (GSH) and malondialdehyde (MDA) levels were measured. The structure of kidney tissue was observed by hematoxylin and eosin staining, kidney cell apoptosis was detected by TUNEL assay, and the mRNA expression levels of genes related to the PERK signaling pathway were analyzed by RT-PCR.

RESULTS

Compared with the control group, the Cd-treated group exhibited a significant decrease in body weight (P < 0.01). Their kidneys showed a significant increase in the relative organ weight (P < 0.01). Moreover, the MDA and GSH levels increased. Kidney tissue damage and renal cell apoptosis were observed, and the mRNA expression levels of genes related to the PERK signaling pathway significantly increased (P < 0.01). Compared with the Cd-treated group, the Cd + Que group exhibited a significant increase in body weight (P < 0.01) and significant decreases in the relative organ weight, MDA and GSH levels, and mRNA expression levels of genes related to the PERK signaling pathway (P < 0.01). Furthermore, kidney tissue damage and renal cell apoptosis were observed.

CONCLUSION

Cd treatment resulted in rat weight loss, renal edema, and oxidative stress and caused renal tissue damage and cell apoptosis by activating the PERK signaling pathway. Que was able to restore the body weight and renal coefficient of rats. It also alleviated the oxidative stress and kidney tissue damage caused by Cd and the cell apoptosis caused by Cd through inhibiting the PERK signaling pathway. Thus, Que could be considered for the treatment of kidney diseases caused by Cd poisoning.

Juggling cadmium detoxification and zinc homeostasis: A division of labour between the two C. elegans metallothioneins

The chemical properties of toxic cadmium and essential zinc are very similar, and organisms require intricate mechanisms that drive selective handling of metals. Previously regarded as unspecific "metal sponges", metallothioneins (MTLs) are emerging as metal selectivity filters. By utilizing C. elegans mtl-1 and mtl-2 knockout strains, metal accumulation in single worms, single copy fluorescent-tagged transgenes, isoform specific qPCR and lifespan studies it was possible to demonstrate that the handling of cadmium and zinc by the two C. elegans metallothioneins differs fundamentally: the MTL-2 protein can handle both zinc and cadmium, but when it becomes unavailable, either via a knockout or by elevated cadmium exposure, MTL-1 takes over zinc handling, leaving MTL-2 to sequester cadmium. This division of labour is reflected in the folding behaviour of the proteins: MTL-1 folded well in presence of zinc but not cadmium, the reverse was the case for MTL-2. These differences are in part mediated by a zinc-specific mononuclear His3Cys site in the C-terminal insertion of MTL-1; its removal affected the entire C-terminal domain and may shift its metal selectivity towards zinc. Overall, we uncover how metallothionein isoform-specific responses and protein properties allow C. elegans to differentiate between toxic cadmium and essential zinc.

Multixenobiotic response of Collembola to soil contamination, the phisiological basis for bioindicative environmental monitoring

Collembola are well-established models in ecotoxicological research, extensively employed to investigate the effects of various contaminants, including heavy metals. The Multixenobiotic Resistance Mechanism (MXR) is a physiological response based on transmembrane efflux proteins that play a pivotal role in pumping xenobiotics and conferring resistance. This mechanism is firmly established as a biomarker of aquatic contamination and has recently shown promise as a soil biomonitoring tool. In this study, we aimed to assess the feasibility of utilizing the MXR mechanism as a biomonitoring tool, specifically by investigating the response of two Collembola species exposed to soil contaminated in a real-life situation. Soil samples were obtained from the site of Brazil's largest mine disaster, a dam rupture in Brumadinho-MG. We explored MXR activity in the model species Folsomia candida and a tropical native species, Cyphoderus sp. Our findings reveal efflux activity in both species, confirmed by model MXR protein inhibitors. Moreover, we observed distinct MXR activity levels corresponding to the degree of heavy metal contamination in the soil samples. Consequently, our results underscore the potential of combining an established soil bioindicator, such as Collembola, with the physiological response of a molecular biomarker like MXR. This approach may represent a valuable strategy for biomonitoring terrestrial ecosystems.

Copper in Cancer: from transition metal to potential target

In recent years, with the continuous in-depth exploration of the molecular mechanisms of tumorigenesis, numerous potential new targets for cancer treatment have been identified, some of which have been further developed in clinical practice and have produced positive outcomes. Notably, researchers' initial motivation for studying copper metabolism in cancer stems from the fact that copper is a necessary trace element for organisms and is closely connected to body growth and metabolism. Moreover, over the past few decades, considerable progress has been made in understanding the molecular processes and correlations between copper and cancer. Certain achievements have been made in the development and use of relevant clinical medications. The concept of "cuproptosis," a novel concept that differs from previous forms of cell death, was first proposed by a group of scientists last year, offering fresh perspectives on the targeting capabilities of copper in the treatment of cancer. In this review, we introduced the fundamental physiological functions of copper, the key components of copper metabolism, and a summary of the current research contributions on the connection between copper and cancer. In addition, the development of new copper-based nanomaterials and their associated mechanisms of action are discussed. Finally, we described how the susceptibility of cancer cells to this metallic nutrition could be leveraged to further improve the existing cancer treatment paradigm in the new setting.

Meta-analysis of single-cell RNA-sequencing data for depicting the transcriptomic landscape of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by airflow limitation and chronic inflammation of the lungs that is a leading cause of death worldwide. Since the complete pathological mechanisms at the single-cell level are not fully understood yet, an integrative approach to characterizing the single-cell-resolution landscape of COPD is required. To identify the cell types and mechanisms associated with the development of COPD, we conducted a meta-analysis using three single-cell RNA-sequencing datasets of COPD. Among the 154,011 cells from 16 COPD patients and 18 healthy subjects, 17 distinct cell types were observed. Of the 17 cell types, monocytes, mast cells, and alveolar type 2 cells (AT2 cells) were found to be etiologically implicated in COPD based on genetic and transcriptomic features. The most transcriptomically diversified states of the three etiological cell types showed significant enrichment in immune/inflammatory responses (monocytes and mast cells) and/or mitochondrial dysfunction (monocytes and AT2 cells). We then identified three chemical candidates that may potentially induce COPD by modulating gene expression patterns in the three etiological cell types. Overall, our study suggests the single-cell level mechanisms underlying the pathogenesis of COPD and may provide information on toxic compounds that could be potential risk factors for COPD.

Interactive effects of cadmium and titanium dioxide nanoparticles on hepatic tissue in rats: Ameliorative role of coenzyme 10 via modulation of the NF-κB and TNFα pathway

This study investigated the effect of oral dosing of titanium dioxide nanoparticles (TNPs) and cadmium (Cd2+) on rat liver and the potential protective role of coenzyme Q10 (CQ10) against TNPs and Cd2+-induced hepatic injury. Seventy male Sprague Dawley rats were divided into seven groups and orally given distilled water, corn oil, CQ10 (10 mg/kg b.wt), TNPs (50 mg/kg b.wt), Cd2+ (5 mg/kg b.wt), TNPs + Cd2+, or TNPs + Cd2++CQ10 by gastric gavage for 60 successive days. The results showed that individual or mutual exposure to TNPs and Cd2+ significantly increased the serum levels of various hepatic enzymes and lipids, depleted the hepatic content of antioxidant enzymes, and increased malondialdehyde. Moreover, the hepatic titanium and Cd2+ content were increased considerably in TNPs and/or Cd2+-exposed rats. Furthermore, marked histopathological perturbations with increased immunoexpression of tumor necrosis factor-alpha and nuclear factor kappa B were evident in TNPs and/or Cd2+-exposed rats. However, CQ10 significantly counteracted the damaging effect of combined exposure of TNPs and Cd2+ on the liver. The study concluded that TNPs and Cd2+ exposure harm hepatic function and its architecture, particularly at their mutual exposure, but CQ10 could be a candidate protective agent against TNPs and Cd2+ hepatotoxic impacts.

Macrophage metallothioneins participate in the antileishmanial activity of antimonials

Host cell functions that participate in the pharmacokinetics and pharmacodynamics (PK/PD) of drugs against intracellular pathogen infections are critical for drug efficacy. In this study, we investigated whether macrophage mechanisms of xenobiotic detoxification contribute to the elimination of intracellular Leishmania upon exposure to pentavalent antimonials (SbV). Primary macrophages from patients with cutaneous leishmaniasis (CL) (n=6) were exposed ex vivo to L. V. panamensis infection and SbV, and transcriptomes were generated. Seven metallothionein (MT) genes, potent scavengers of heavy metals and central elements of the mammalian cell machinery for xenobiotic detoxification, were within the top 20 up-regulated genes. To functionally validate the participation of MTs in drug-mediated killing of intracellular Leishmania, tandem knockdown (KD) of MT2-A and MT1-E, MT1-F, and MT1-X was performed using a pan-MT shRNA approach in THP-1 cells. Parasite survival was unaffected in tandem-KD cells, as a consequence of strong transcriptional upregulation of MTs by infection and SbV, overcoming the KD effect. Gene silencing of the metal transcription factor-1 (MTF-1) abrogated expression of MT1 and MT2-A genes, but not ZnT-1. Upon exposure to SbV, intracellular survival of Leishmania in MTF-1KD cells was significantly enhanced. Results from this study highlight the participation of macrophage MTs in Sb-dependent parasite killing.

Distribution, bioaccumulation, and trace element transfer among trophic levels in the southeastern Gulf of California

Our understanding of the trophic transfer of pollutants in marine subtropical ecosystems remains limited due to the complexity of their food webs. Thus, we aimed to evaluate Cd, Cu, Mn, Pb, and Zn sources, incorporation, and trophodynamics throughout the food web of the southeastern Gulf of California by stomach content analysis, stable isotope analysis, isotope mixing models, and trace element analysis in biological and environmental matrices. The food web comprised three main trophic guilds (TG1, TG2, and TG3). The bioaccumulation of Cd and Zn from seawater was efficient (> 1000) in TG2 and TG3. Bioaccumulation factor from sediment (BSAF >1) evidenced of Cd in all trophic guilds. In addition, non-trophic Cd relationships were identified in the food web. Based on the trophic magnification factor (TMF), Mn and Pb showed biodilution (TMFMn = 0.38; TMFPb = 0.16), while Cu and Zn exhibited biomagnification (TMFCu = 2.08; TMFZn = 3.31).

Xenobiotic Bi3+ Coordination by Cysteine-Rich Metallothionein-3 Reveals a Cooperatively Formed Thiolate-Sharing Bi2S5 Cluster

The field of designing artificial metalloproteins has yet to effectively tackle the incorporation of multimetal clusters, which is a key component of natural metalloproteins, such as metallothioneins (MTs) and calmodulin. MT is a physiological, essential, cysteine-rich metalloprotein that binds to a variety of metals but is only known to form metal-thiolate clusters with Cd2+, Zn2+, and Cu+. Bismuth is a xenobiotic metal and a component of metallodrugs used to treat gastric ulcers and cancer, as well as an emerging metal used in industrial practices. Electrospray ionization mass spectrometry, UV-visible spectroscopy, and extended X-ray absorption fine structure spectroscopy were used to probe the Bi3+ binding site structures in apo-MT3 (brain-located MT) at pH 7.4 and 2 and provide the complete set of binding affinities. We discovered the highly cooperative formation of a novel Bi3+ species, Bi2MT3, under physiological conditions, where each Bi3+ ion is coordinated by three cysteinyl thiolates, with one of the thiolates bridging between the two Bi3+ ions. This cluster structure was associated with a strong visible region absorption band, which was disrupted by the addition of Zn2+ and reversibly disrupted by acidification and increased temperature. This is the first reported presence of bridging cysteines for a xenobiotic metal in MT3 and the Bi2MT structure is the first Bi cluster found in a metalloprotein.

The environment and male reproductive system: the potential role and underlying mechanisms of cadmium in testis cancer

Cadmium is a known human carcinogen, and has been shown to profoundly affect male reproductive function, at multiple levels, by exerting both endocrine and non-endocrine actions. Nevertheless, the potential role of cadmium in the etiology of testis cancer has been scantly investigated in humans, and, currently, available epidemiological observational studies are insufficient to draw definitive conclusions in this regard. On the contrary, experimental studies in laboratory animals demonstrated that cadmium is a strong inducer of testis tumors, mostly represented by benign Leydig cell adenoma; moreover, malignant transformation was also reported in few animals, following cadmium treatment. Early experimental studies in animals proposed an endocrine-dependent mechanism of cadmium-induced testis tumorigenesis; however, more recent findings from cell-free assays, in vitro studies, and short-term in vivo studies, highlighted that cadmium might also contribute to testis tumor development by early occurring endocrine-independent mechanisms, which include aberrant gene expression within the testis, and genotoxic effects, and take place well before the timing of testis tumorigenesis. These endocrine-independent mechanisms, however, have not been directly investigated on testis tumor samples retrieved from affected, cadmium-treated animals so far. The present review focuses on the relationship between cadmium exposure and testis cancer, by reporting the few epidemiological observational human studies available, and by providing animal-based experimental evidences of cadmium implication in the pathogenesis and progression of testis tumor. Moreover, the relevance of experimental animal studies to human cadmium exposure and the translational potential of experimental findings will be extensively discussed, by critically addressing strengths and weaknesses of available data.

Arsenic binding to human metallothionein-3

Arsenic poisoning is of great concern with respect to its neurological toxicity, which is especially significant for young children. Human exposure to arsenic occurs worldwide from contaminated drinking water. In human physiology, one response to toxic metals is through coordination with the metallochaperone metallothionein (MT). Central nervous system expression of MT isoform 3 (MT3) is thought to be neuroprotective. We report for the first time on the metalation pathways of As3+ binding to apo-MT3 under physiological conditions, yielding the absolute binding constants (log Kn, n = 1-6) for each sequential As3+ binding event: 10.20, 10.02, 9.79, 9.48, 9.06, and 8.31 M-1. We report on the rate of the reaction of As3+ with apo-MT3 at pH 3.5 with rate constants (kn, n = 1-6) determined for each sequential As3+ binding event: 116.9, 101.2, 85.6, 64.0, 43.9, and 21.0 M-1 s-1. We further characterize the As3+ binding pathway to fully metalated Zn7MT3 and partially metalated Zn-MT3. As3+ binds rapidly with high binding constants under physiological conditions in a noncooperative manner, but is unable to replace the Zn2+ in fully-metalated Zn-MT3. As3+ binding to partially metalated Zn-MT3 takes place with a rearrangement of the Zn-binding profile. Our work shows that As 3+ rapidly and efficiently binds to both apo-MT3 and partially metalated Zn-MT3 at physiological pH.

Overexpression of LSU1 and LSU2 confers cadmium tolerance by manipulating sulfur metabolism in Arabidopsis

Phytoremediation using plants is an environmentally friendly and cost-effective strategy for removing cadmium (Cd) from soil. Plants used for phytoremediation must have a high Cd accumulation capacity and strong Cd tolerance. Therefore, understanding the molecular mechanism of Cd tolerance and accumulation in plants is of great interest. In response to Cd exposure, plants produce various thio-rich compounds, such as glutathione, phytochelatins, and metallothioneins, which play important roles in Cd immobilization, sequestration, and detoxification. Therefore, sulfur (S) metabolism is crucial for Cd tolerance and accumulation. In this study, we report that the overexpression of low-S responsive genes, LSU1 and LSU2, confers Cd tolerance in Arabidopsis. First, LSU1 and LSU2 promoted S assimilation under Cd stress. Second, LSU1 and LSU2 inhibited the biosynthesis and promoted the degradation of aliphatic glucosinolates, which could limit the consumption and enhance the release of S, thus, facilitating the production of the S-rich metabolites, glutathione, phytochelatins, and metallothioneins. We further demonstrated that the Cd tolerance mediated by LSU1 and LSU2 was dependent on the myrosinases BGLU28 and BGLU30, which catalyze the degradation of aliphatic glucosinolates. In addition, the overexpression of LSU1 and LSU2 improved Cd accumulation, which has great potential for the phytoremediation of Cd-contaminated soil.

Metal and trace element concentrations in cetaceans worldwide: A review

This bibliographical review is a compilation of different scientific publications that reported data on metal concentrations in the muscle tissue of different species of cetaceans from seas and oceans around the world. Forty-nine scientific articles were selected, published over a fifteen-year period (2006-2021) with data on heavy metals and trace elements. The different groups of cetaceans considered in this study generally presented low concentrations of Cd and Pb. The same cannot be said of Hg. The highest concentrations of Hg were found in the groups of false killer whales. Similarly, the use of these groups of cetaceans as bioindicators of metal contamination shows that the Mediterranean Sea is one of the most metallically contaminated areas in the world. This may be due to the closed nature of the Mediterranean Sea and to the fact that it is also a highly populated and industrialized area.

Current Levels of Environmental Exposure to Cadmium in Industrialized Countries as a Risk Factor for Kidney Damage in the General Population: A Comprehensive Review of Available Data

The growing number of reports indicating unfavorable outcomes for human health upon environmental exposure to cadmium (Cd) have focused attention on the threat to the general population posed by this heavy metal. The kidney is a target organ during chronic Cd intoxication. The aim of this article was to critically review the available literature on the impact of the current levels of environmental exposure to this xenobiotic in industrialized countries on the kidney, and to evaluate the associated risk of organ damage, including chronic kidney disease (CKD). Based on a comprehensive review of the available data, we recognized that the observed adverse effect levels (NOAELs) of Cd concentration in the blood and urine for clinically relevant kidney damage (glomerular dysfunction) are 0.18 μg/L and 0.27 μg/g creatinine, respectively, whereas the lowest observed adverse effect levels (LOAELs) are >0.18 μg/L and >0.27 μg/g creatinine, respectively, which are within the lower range of concentrations noted in inhabitants of industrialized countries. In conclusion, the current levels of environmental exposure to Cd may increase the risk of clinically relevant kidney damage, resulting in, or at least contributing to, the development of CKD.

Cadmium accumulation and isotope fractionation in typical protozoa Tetrahymena: A new perspective on remediation of Cd pollution in wastewater

Cadmium (Cd) pollution threatens water safety and human health, which has raised serious public concern. Tetrahymena is a model protozoan, possessing the potential to remediate Cd contaminated water given the rapid expression of thiols. However, the mechanism of Cd accumulation in Tetrahymena has not been well understood, which hinders its application in environmental remediation. This study elucidated the pathway of Cd accumulation in Tetrahymena using Cd isotope fractionation. Our results showed that Tetrahymena preferentially absorb light Cd isotopes, with Δ^114/110Cd_{Tetrahymena-solution} = -0.20 ± 0.02‰ ∼ - 0.29 ± 0.02‰, which implies that the intracellular Cd is probably in the form of Cd-S. The fractionation generated by Cd complexation with thiols is constant (Δ^114/110Cd_{Tetrahymena-remaining solution} ∼ -0.28 ± 0.02‰), which is not affected by the concentrations of Cd in intracellular and culture medium, nor by the physiological changes in cells. Furthermore, the detoxification process of Tetrahymena results in an increase in cellular Cd accumulation from 11.7% to 23.3% with the elevated Cd concentrations in batch Cd stress culture experiments. This study highlights the promising application of Cd isotope fractionation in Tetrahymena for the remediation of heavy metal pollution in water.

Multifunctional Metallothioneins as a Target for Neuroprotection in Parkinson's Disease

Parkinson's disease (PD) is characterized by motor symptoms based on a loss of nigrostriatal dopaminergic neurons and by non-motor symptoms which precede motor symptoms. Neurodegeneration accompanied by an accumulation of α-synuclein is thought to propagate from the enteric nervous system to the central nervous system. The pathogenesis in sporadic PD remains unknown. However, many reports indicate various etiological factors, such as oxidative stress, inflammation, α-synuclein toxicity and mitochondrial impairment, drive neurodegeneration. Exposure to heavy metals contributes to these etiopathogenesis and increases the risk of developing PD. Metallothioneins (MTs) are cysteine-rich metal-binding proteins; MTs chelate metals and inhibit metal-induced oxidative stress, inflammation and mitochondrial dysfunction. In addition, MTs possess antioxidative properties by scavenging free radicals and exert anti-inflammatory effects by suppression of microglial activation. Furthermore, MTs recently received attention as a potential target for attenuating metal-induced α-synuclein aggregation. In this article, we summarize MTs expression in the central and enteric nervous system, and review protective functions of MTs against etiopathogenesis in PD. We also discuss neuroprotective strategies for the prevention of central dopaminergic and enteric neurodegeneration by targeting MTs. This review highlights multifunctional MTs as a target for the development of disease-modifying drugs for PD.

Adaptive plastic responses to metal contamination in a multistress context: a field experiment in fish

Wild populations often differ in their tolerance to environmental stressors, but intraspecific variability is rarely taken into account in ecotoxicology. In addition, plastic responses to multiple stressors have rarely been investigated in realistic field conditions. In this study, we compared the responses to metal contamination of gudgeon populations (Gobio occitaniae) differing in their past chronic exposure to metal contamination, using a reciprocal transplant experiment and an immune challenge mimicking a parasite attack to test for potential effects of multiple stressors across biological levels. We measured fish survival and traits involved in metal bioaccumulation, oxidative stress, immunity, cell apoptosis, and energy management to decipher underpinning physiological mechanisms across biological levels (i.e., gene expression, cell, organism). Fish from the two replicate High Contamination sites had higher survival when transferred into contaminated sites, suggesting a local adaptation to the contaminated site, possibly explained by higher levels of detoxification and antioxidant capacity but with potential higher apoptosis costs compared to their naïve counterparts. We found no evidence of co- or maladaptation to the immune stressor, suggesting no specific costs to face pathogens. In the emerging field of evolutionary ecotoxicology, this study underlines the need to consider intraspecific variability to better understand the effects of pollution in heterogeneous populations.

Nano‑zinc enhances gene regulation of non‑specific immunity and antioxidative status to mitigate multiple stresses in fish

The toxicity of ammonia surged with arsenic pollution and high temperature (34 °C). As climate change enhances the pollution in water bodies, however, the aquatic animals are drastically affected and extinct from nature. The present investigation aims to mitigate arsenic and ammonia toxicity and high-temperature stress (As + NH₃ + T) using zinc nanoparticles (Zn-NPs) in Pangasianodon hypophthalmus. Zn-NPs were synthesized using fisheries waste to developing Zn-NPs diets. The four isonitrogenous and isocaloric diets were formulated and prepared. The diets containing Zn-NPs at 0 (control), 2, 4 and 6 mg kg^-1 diets were included. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-s-transferase (GST) were noticeably improved using Zn-NPs diets in fish reared under with or without stressors. Interestingly, lipid peroxidation was significantly reduced, whereas vitamin C and acetylcholine esterase were enhanced with supplementation of Zn-NPs diets. Immune-related attributes such as total protein, globulin, albumin, myeloperoxidase (MPO), A:G ratio, and NBT were also improved with Zn-NPs at 4 mg kg^-1 diet. The immune-related genes such as immunoglobulin (Ig), tumor necrosis factor (TNFα), and interleukin (IL1b) were strengthening in the fish using Zn-NPs diets. Indeed, the gene regulations of growth hormone (GH), growth hormone regulator (GHR1), myostatin (MYST) and somatostatin (SMT) were significantly improved with Zn-NPs diets. Blood glucose, cortisol and HSP 70 gene expressions were significantly upregulated by stressors, whereas the dietary Zn-NPs downregulated the gene expression. Blood profiling (RBC, WBC and Hb) was reduced considerably with stressors (As + NH₃ + T), whereas Zn-NPs enhanced the RBC, WBC, and Hb count in fish reread in control or stress conditions. DNA damage-inducible protein gene and DNA damage were significantly reduced using Zn-NPs at 4 mg kg^-1 diet. Moreover, the Zn-NPs also enhanced the arsenic detoxification in different fish tissues. The present investigation revealed that Zn-NPs diets mitigate ammonia and arsenic toxicity, and high-temperature stress in P. hypophthalmus.

Placental Barrier on Cadmium Transfer from Mother to Fetus in Related to Pregnancy Complications

Purpose

As two of the most severe and common medical disorders during pregnancy, gestational diabetes mellitus (GDM) and hypertensive disorder complicating pregnancy (HDCP) cause adverse effects on placental barrier function and thus may lead to a high risk of intrauterine exposure to toxic metals from mother to fetus. This study investigates the impact of the placental barrier on the transfer of cadmium (Cd) from mother to fetus and the relationship between pregnancy complications.

Methods

A total of 107 pairs of samples were collected in Kunming, China; 29 were from healthy pregnant women, and 78 were from patients with pregnancy complications. Cd was measured in each mother's placenta and maternal and umbilical cord blood. The expressions of MT and Cd-MT complex in blood and placental tissue samples were determined by enzyme-linked immunosorbent assay (ELISA).

Results

The cesarean section rate in the whole pathological group (60.7%) was higher than that in the normal group (20.7%), and the ratio of the effective barrier (ratio of maternal blood to umbilical cord blood>1) in the pathological group (74%) was lower than that in the normal group (79%). In addition, the proportion of practical placental barriers in women aged 20-25 years was 83.3%, 76.3% in women aged 26-30 years, 74.3% in women aged 31-35 years, 70% in women aged 36-40 years, and 71% in women aged 40-45 years. The Cd content in the placenta of the three pathological groups was significantly higher than that in maternal and umbilical cord blood (P<0.05), and the distribution of Cd was the same as that in the normal group. However, there was no significant difference between maternal and umbilical cord blood Cd concentrations in the pathological group. The Cd concentration in the normal group's maternal blood was significantly higher than that in cord blood (P<0.05). In addition, the expression levels of both metallothionein (MT) and Cd-MT complex in placenta is much higher than in maternal and umbilical blood, and which in normal group are significantly higher than those in pathological group.

Conclusion

Both mothers and fetuses are at increased health risk for pregnancy disorders when maternal age, BMI, or body weight increases. Increased maternal age increases the likelihood of Cd transfer from the mother to the fetus. Pregnancy complications may induce lower expression of MT, thus reducing the Cd-MT complex in the placenta, weakening the placental barrier, and increasing the risk of Cd transfer and exposure to the fetus.

Heavy Metal Contamination in Leafy Vegetables Grown in Jazan Region of Saudi Arabia: Assessment of Possible Human Health Hazards

The food chain, through vegetable consumption, is considered to be an important route of heavy metal exposure. Therefore, in this study, heavy metal concentrations in leafy vegetables grown in the Jazan region of Saudi Arabia were assessed using an ICP-MS. Lettuce, radish, mint, parsley and jarjir (Arugula) were selected for study and subjected to digestion using HCl. The results indicated that the Fe level was highest in all vegetables, while jarjir was the most contaminated vegetable. However, no tested metal exceeded the maximum permissible limits set by the FAO/WHO and European Committee. The possible health hazards associated with the exposure to metal contaminants via vegetable consumption were evaluated by estimating target hazard quotient (THQ) values, and the results revealed that the vegetables grown in close proximity of Jazan city were the most contaminated and those in Darb the least. However, the daily intakes of all the tested metals were well below the corresponding oral reference doses (RfDs), and the THQ values were less than unity, suggesting that the vegetables grown in the studied region were safe and the heavy metal exposure via vegetable consumption was unlikely to cause adverse effects to the local inhabitants of the region.

Combined Protective Effects of Quercetin, Rutin, and Gallic Acid against Cadmium-Induced Testicular Damages in Young-Adult Rats

Cadmium (Cd) is a toxic metal that damages several tissues of animals and humans including the testis. The ameliorative effects of quercetin (QUE), rutin (RUT), and gallic acid (GAL) at 20 mg kg-1 body weight alone or in combination against testicular injury induced by Cd (24 mg kg-1 body weight) in male Wistar rats were evaluated in this study. Forty-two (42) rats were randomly grouped into six (6) groups: (1) vehicle control group, (2) Cd group, (3) RUT+Cd group, (4) GAL+Cd group, (5) QUE+Cd group, and (6) RUT+GAL+QUE+Cd group. At the end of the oral gavage of the tested chemicals, the rats were sacrificed, blood samples were collected, and testes were harvested and processed for biochemical assays. Cd exposure damaged the testis (smaller epithelium thickness and spermatogenesis index and sloughing of the epithelium); increased lipid peroxidation, glutathione S-transferase activity, and DNA fragmentation; and diminished glutathione reductase activity and serum testosterone level 40 days posttreatment. Treatment with the phenolics separately or in combination attenuated the effect of Cd on serum testosterone, glutathione reductase and glutathione S-transferase activities, lipid peroxidation, and percent fragmented DNA. The increased nitric oxide concentration in the QUE+Cd group was attenuated to control values in the combined (RUT+GAL+QUE+Cd) exposure group. Coadministration of the phenolics appears to have more substantial protective effects than their single effects against Cd-induced testicular DNA damage, glutathione S-transferase activity, and the recovery of testosterone levels and spermatogenesis index. Overall, the tested phenolics can reduce testicular damage more efficiently in their combined form than individual administration.

Gold nanoparticles capped with L-glycine, L-cystine, and L-tyrosine: toxicity profiling and antioxidant potential

Biomolecules-based surface modifications of nanomaterials may yield effective and biocompatible nanoconjugates. This study was designed to evaluate gold nanoconjugates (AuNCs) for their altered antioxidant potential. Gold nanoparticles (AuNPs) and their conjugates gave SPR peaks in the ranges of 512-525 nm, with red or blueshift for different conjugates. Cys-AuNCs demonstrated enhanced (p < 0.05) and Gly-AuNCs (p > 0.05) displayed reduced DPPH activity. Gly-AuNCs and Tyr-AuNCs displayed enhanced ferric-reducing power and hydrogen peroxide scavenging activity, respectively. Cadmium-intoxicated mice were exposed to gold nanomaterials, and the level of various endogenous parameters, i.e., CAT, GST, SOD, GSH, and MTs, was evaluated. GSH and MTs in liver tissues of the cadmium-exposed group (G2) were elevated (p < 0.05), while other groups showed nonsignificance deviations than the control group. It is concluded that these nanoconjugates might provide effective nanomaterials for biomedical applications. However, more detailed studies for their safety profiling are needed before their practical applications.

Protective effect of dendropanoxide against cadmium-induced hepatotoxicity via anti-inflammatory activities in Sprague-Dawley rats

Cadmium (Cd) accumulates in the body through contaminated foods or water and causes pathological damage to the liver via oxidative stress and inflammatory reactions. This study was conducted to explore the effects of dendropanoxide (DPx) on Cd-induced hepatotoxicity in rats. Sprague-Dawley (SD) rats were injected with CdCl2 (7 mg/kg body weight) intraperitoneally for 14 days for the induction of liver dysfunction. The CdCl2-exposed rats were subjected to DPx (10 mg/kg) or silymarin (50 mg/kg). The animals were euthanized after 24 h of the last CdCl2 injection and the serum biochemical parameters, lipid content, pro-inflammatory cytokine levels, apoptotic cell death and histopathology of the tissues were analyzed. Additionally, the activity of antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), was measured. Compared to controls, Cd-injected rats showed significantly elevated serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglycerides (TG), total cholesterol, and pro-inflammatory cytokines, and a remarkable decrease in SOD and CAT activities. Importantly, Cd-induced liver damage was drastically ameliorated by treatment with DPx or silymarin. Treatment with DPx protected the Cd-induced histopathological hepatic injury, as confirmed by the evaluation of TUNEL assay. DPx treatment significantly reduced Bax and caspase-3 expression in Cd-injected rats. Additionally, HO-1 and NRF2 expressions were significantly increased after DPx administration in the liver of Cd-injected rats. Our data indicate that DPx successfully prevents Cd-induced hepatotoxicity by emphasizing the antioxidant and anti-inflammatory effect.

Profiling protein targets of cellular toxicant exposure

Environmental agents of exposure can damage proteins, affecting protein function and cellular protein homeostasis. Specific residues are inherently chemically susceptible to damage from individual types of exposure. Amino acid content is not completely predictive of protein susceptibility, as secondary, tertiary, and quaternary structures of proteins strongly influence the reactivity of the proteome to individual exposures. Because we cannot readily predict which proteins will be affected by which chemical exposures, mass spectrometry-based proteomic strategies are necessary to determine the protein targets of environmental toxins and toxicants. This review describes the mechanisms by which environmental exposure to toxins and toxicants can damage proteins and affect their function, and emerging omic methodologies that can be used to identify the protein targets of a given agent. These methods include target identification strategies that have recently revolutionized the drug discovery field, such as activity-based protein profiling, protein footprinting, and protein stability profiling technologies. In particular, we highlight the necessity of multiple, complementary approaches to fully interrogate how protein integrity is challenged by individual exposures.

Trace Element Uptake by Willows Used for the Phytoremediation of Biosolids

The land application of biosolids can result in the unacceptable accumulation of Trace Elements (TEs) in agricultural soil and potentially introduce xenobiotics and pathogens into the food chain. Phytoremediation of biosolids aims to minimize this risk, while producing valuable biomass. Willows, well known to accumulate zinc (Zn), are used extensively in farming systems for soil conservation, shelter and as feed supplements with demonstrable health benefits. Potentially, biosolids phytoremediation could occur on marginal lands adjacent to farmlands where willows are grown for supplementary fodder. We aimed to determine the uptake and distribution of Zn and other TEs in willows grown on soils amended with biosolids and biosolids blended with biochar, with a view to their use as stock fodder. In the Canterbury Region, New Zealand, we grew Salix 'tangaio' (S. matsudana X S. alba) in a greenhouse trial and field study. The biomass production of the willows was unaffected by biosolids and increased by the biosolids+biochar mixture. The addition of 4% biosolids (w/w) to the soil resulted in a foliar Zn concentration of 600-1000 mg kg^-1, some 25 times higher than the average New Zealand pasture. Zinc concentrations were highest in the bottom leaves and increased throughout the season. Biosolids addition doubled the copper (Cu) concentration to 10 mg kg^-1. Adding biochar to the system reduced the plant uptake of Cu and to a lesser extent Zn, while cadmium (Cd) uptake was unaffected. For Cd, Cu, and Zn, plant uptake was a function of the Ca(NO₃)₂-extractable concentration, both in greenhouse experiments and the field trial. Future work should determine the changes in plant TE uptake over several growing seasons.

Toxic Effects of Cadmium on the Female Reproductive Organs a Review

Cadmium (Cd) is a common environmental pollutant present in soil and associated with many modern industrial processes. Cadmium may adversely influence the health of experimental animals and humans and exert significant effects on the reproductive tract morphology and physiology. During embryonic development, cadmium suppresses the normal growth and development of the ovaries, and in adults it disrupts the morphology and function of the ovaries and uterus. The exposure to cadmium has adverse effects on the oocyte meiotic maturation affecting the structure of ovarian tissue. The distribution of follicles and corpus luteum in the ovarian tissues has been shown to be disrupted, affecting the normal growth and development of the follicles. In the ovarian cortex, the number of follicles at different stages of maturation decreased, and the number of atretic follicles increased. In the medulla, oedema and ovarian haemorrhage and necrosis appears at higher doses. Granulosa cells exposed to cadmium exhibited morphological alterations. Oocyte development was inhibited and the amount of oocyte apoptosis was higher. Cadmium exposure also caused changes in the structure of the ovarian blood vessels with reduction in the vascular area. Cadmium effects included increased uterine weight, hyperplasia and hypertrophy of the endometrial lining. Exposure to cadmium had specific effects on gonadal steroidogenesis by suppressing steroid biosynthesis of the ovarian granulosa cells and luteal cells. Progesterone, follicle stimulating hormone, and luteinizing hormone decreased significantly after CdCl2 administration. Cadmium can suppress the female’s ovulation process and cause temporary infertility.

The role of inflammation in cadmium nephrotoxicity: NF-κB comes into view

Kidney diseases are major health problem and understanding the underlined mechanisms that lead to kidney diseases are critical research points with a marked potential impact on health. Cadmium (Cd) is a heavy metal that occurs naturally and can be found in contaminated food. Kidneys are the most susceptible organ to heavy metal intoxication as it is the main route of waste excretion. The harmful effects of Cd were previously well proved. Cd induces inflammatory responses, oxidative injury, mitochondrial dysfunction and disturbs Ca²⁺ homeostasis. The nuclear factor-kappa B (NF-κB) is a cellular transcription factor that regulates inflammation and controls the expression of many inflammatory cytokines. Therefore, great therapeutic benefits can be attained from NF-κB inhibition. In this review we focused on certain compounds including cytochalasin D, mangiferin, N-acetylcysteine, pyrrolidine dithiocarbamate, roflumilast, rosmarinic acid, sildenafil, sinapic acid, telmisartan and wogonin and certain plants as Astragalus Polysaccharide, Ginkgo Biloba and Thymus serrulatus that potently inhibit NF-κB and effectively counteracted Cd-associated renal intoxication. In conclusion, the proposed NF-κB involvement in Cd-renal intoxication clarified the underlined inflammation associated with Cd-nephropathy and the beneficial effects of NF-κB inhibitors that make them the potential to substantially optimize treatment protocols for Cd-renal intoxication.

Bioaccumulation of selected trace elements in some aquatic organisms from the proximity of Qeshm Island ecosystems: Human health perspective

In this study selected marine species from north Persian Gulf ecosystems were collected to investigate the concentration of 15 trace elements (Al, As, Co, Cr, Cu, Fe, Li, Mo, Ni, Pb, Se, Sr, V, Zn and Hg) in muscle and liver tissues for the purpose of evaluating potential health risks for human consumers. The results indicated that Fe, Zn, Sr, Cu and As are the most abundant TEs in the tissues of the species. The concentration of Cu in P. semisulcatus and As in most investigated species pose the highest risk of exposure. The carcinogenic risk values indicate that As and Ni concentrations in the species are above the acceptable lifetime risk for adults and children in most of the species. The margin of exposure risk approach indicated that the risk of detrimental effects due to dietary Pb intake for age groups is low, except for consumers of T. tonggol.

Blood metals and vitamin D status in a pregnancy cohort: A bidirectional biomarker analysis

Low 25-hydroxyvitamin D (25OHD), a biomarker of vitamin D status, is associated with reduced immune function and adverse pregnancy outcomes, such as preterm birth. Observational studies indicate that long-term, high level exposure to metals such as cadmium (Cd) and lead (Pb) can impact a person's vitamin D status. However, the directionality of the association is uncertain, particularly for low-level exposures. We used three distinct longitudinal data analysis methods to investigate cross-sectional, longitudinal and bidirectional relationships of Cd and Pb biomarkers with 25-hydroxyvitamin D (25OHD) in a Canadian pregnancy cohort. Maternal whole blood Cd and Pb and plasma 25OHD concentrations were measured in the 1st (n = 1905) and 3rd (n = 1649) trimester and at delivery (25OHD only, n = 1542). Our multivariable linear regression analysis showed weak inverse associations between Cd and 25OHD concentrations cross-sectionally and longitudinally while the latent growth curve models showed weak associations with Pb on the 25OHD intercept. In the bidirectional analysis, using cross lagged panel models, we found no association between 1st trimester metals and 3rd trimester 25OHD. Instead, 1st trimester 25OHD was associated with 9% (-15%, -3%) lower 3rd trimester Cd and 3% (-7, 0.1%) lower Pb. These findings suggest the 25OHD may modify metal concentrations in pregnancy and demonstrates the value of controlling for contemporaneous effects and the persistence of a biomarker over time, in order to rule out reverse causation.