Arsenic: toxicity, oxidative stress and human disease

Targeting the 'DNA methylation mark': Analysis of early epigenetic-alterations in children chronically exposed to arsenic

Chronic exposure to arsenic causes adverse health effects in children. Aberrant epigenetic modifications including altered DNA methylation pattern are one of the major steps towards malignant transformation of cells. Our group has previously identified significant alteration in DNA methylation mark in arsenic exposed adults, affecting major biological pathways. Till date, no information is available exploring the altered DNA methylation mark in telomere regulation and altered mitochondrial functionality in association with DNA damage in arsenic-exposed children. Our study aims in identifying signature epigenetic pattern associated with telomere lengthening, mitochondrial functionality and DNA damage repair in children with special emphasis on DNA methylation. Biological samples (blood and urine) and drinking water were collected from the children aged between 5 and 16 years of arsenic exposed areas (N = 52) of Murshidabad district and unexposed areas (N = 50) of East Midnapur districts, West Bengal, India. Methylation-specific PCR was performed to analyse subtelomeric methylation status and promoter methylation status of target genes. Results revealed altered DNA methylation profile in the exposed children compared to unexposed. Promoter hypermethylation was observed in MLH1 and MSH2 (p < 0.05 and p < 0.001) indicating inefficiency in DNA damage repair. Hypomethylation in mitochondrial D-loop (p < 0.05) and TFAM promoter region (p < 0.05) along with increased mitochondrial DNA copy number among exposed children was also observed. Significant increase in telomere length and region specific subtelomeric hypermethylation (XpYp, p < 0.05) was found. Analysis of S-Adenosyl Methionine (SAM) and 8-oxoDG level revealed significant depletion of SAM (p < 0.001) and elevated oxidative DNA damage (p < 0.001) respectively in arsenic toxicity. Our study identified key methylation patterns in arsenic-exposed children which may act as an early predictive biomarker in the near future. Further in-depth studies involving large sample size and transcriptomic analysis are required for understanding the mechanistic details.

Road dust exposure and human corneal damage in a plateau high geological background provincial capital city: Spatial distribution, sources, bioaccessibility, and cytotoxicity of dust heavy metals

Ocular surface diseases are common in the plateau city, Kunming China, the continued daily exposure to heavy metals in dust may be an important inducement. In this study, the 150 road dust samples from five functional areas in Kunming were collected. The concentrations, distribution, possible sources, and bioaccessibility of heavy metals were analyzed. The adverse effects of dust extracts on human corneal epithelial cells and the underlying mechanisms were also assessed. The concentrations (mg·kg-1) of As (19.1), Cd (2.67), Cr (90.5), Cu (123), Pb (78.4), and Zn (389) in road dust were higher than the soil background, with commercial and residential areas showing the highest pollution. Their bioaccessibility in artificial tears was As (6.59 %) > Cu (5.11 %) > Ni (1.47 %) > Cr (1.17 %) > Mn (0.84 %) > Cd (0.76 %) > Zn (0.50 %) > Pb (0.31 %). The two main sources of heavy metals included tire and mechanical abrasion (24.5 %) and traffic exhaust (21.6 %). All dust extracts induced cytotoxicity, evidenced by stronger inhibition of cell viability, higher production of ROS, and altered mRNA expression of antioxidant enzymes and cell cycle-related genes, with commercial- areas-2 (CA2)-dust extract showing the greatest oxidative damage and cell cycle arrest. Our data may provide new evidence that dust exposure in high geological background cities could trigger human cornea damage.

Progress of gaseous arsenic removal from flue gas by adsorption: Experimental and theoretical calculations

Because of its high mobility and difficult capture, gaseous arsenic pollution control has become the focus of arsenic pollution control. It mainly exists in the form of highly toxic As2O3 in the flue gas. Therefore, removing gaseous As2O3 from flue gas is of great practical significance for arsenic pollution control. Stabilizing gaseous As2O3 on the surface of adsorbents by physical or chemical adsorption is an effective way to reduce the content of arsenic in the flue gas and alleviate arsenic pollution. Over the past few decades, various adsorbents have been developed to capture gaseous As2O3 in the flue gas, and their adsorption mechanisms have been studied in detail. Thus, it is necessary to review the strategies of arsenic removal from flue gas by adsorption, which can inspire further research. Based on summarizing the morphological distribution of gaseous As2O3 in the flue gas, this review further summarizes the removal of gaseous As2O3 by several adsorbents and the effect of temperature and the main components of the flue gas on arsenic adsorption. In addition, the mechanism of arsenic removal based on adsorption in the flue gas is discussed in depth through theoretical calculations, which is the particular focus of this review. Finally, prospects based on the present research state of arsenic removal by adsorption are proposed to provide ideas for developing effective and stable adsorbents for arsenic removal from flue gas.

Understanding the mechanistic roles of microplastics combined with heavy metals in regulating ferroptosis: Adding new paradigms regarding the links with diseases

As a new type of pollutant, microplastics (MPs) commonly exist in today's ecosystems, causing damage to the ecological environment and the health of biological organisms, including human beings. MPs can function as carriers of heavy metals (HMs) to aggravate the enrichment of HMs in important organs of organisms, posing a great threat to health. Ferroptosis, a novel process for the regulation of nonapoptotic cell death, has been shown to be closely related to the occurrence and processes of MPs and HMs in diseases. In recent years, some HMs, such as cadmium (Cd), iron (Fe), arsenic (As) and copper (Cu), have been proven to induce ferroptosis. MPs can function as carriers of HMs to aggravate damage to the body. This damage involves oxidative stress, mitochondrial dysfunction, lipid peroxidation (LPO), inflammation, endoplasmic reticulum stress (ERS) and so on. Therefore, ferroptosis has great potential as a therapeutic target for diseases induced by MPs combined with HMs. This paper systematically reviews the potential effects and regulatory mechanisms of MPs and HMs in the process of ferroptosis, focusing on the mitochondrial damage, Fe accumulation, LPO, ERS and inflammation caused by MPs and HMs that affect the regulatory mechanism of ferroptosis, providing new insights for research on regulating drugs and for the development of ferroptosis-targeting therapy for Alzheimer's disease, Parkinson's disease, cancer and cardiovascular disease.

Does PM 2.5 and PM 10-associated heavy metals affect short-term and long-term survival after out-of-hospital cardiac arrest? Four-year study based on regional registry

BACKGROUND

This study aims to investigate the effect of arsenic (As), cadmium (Cd), nickel (Ni) and lead (Pb) suspended on particulate matters (PM) 2.5 and PM 10 taking into account clinical factors on 30-day and one-year survival after out-of-hospital cardiac arrest (OHCA).

METHODS

A retrospective 4-year study that involved patients hospitalized after OHCA. Patients' data were obtained from Emergency Medical Services dispatch cards and the National Health Fund. The concentration of air pollutants was measured by the Environmental Protection Inspectorate in Poland.

RESULTS

Among the 948 patients after OHCA, only 225 (23.7%) survived for 30 days, and 153 (16.1%) survived for 1 year. Survivors were more commonly affected by OHCA in urban areas (85 [55.6%] vs. 355 [44.7%]; P=0.013) and had slightly higher one-year mean concentration of As (0.78 vs. 0.77; P=0.01), Cd (0.34 vs. 0.34; P=0.012), and Pb (11.13 vs. 10.20; P=0.015) with no differences in daily mean concentration. Significant differences in mean concentrations of heavy metals and PM 2.5 and PM 10 were observed among different quarters. However, survival analysis revealed no differences in long-term survival between quarters. Heavy metals, PM 2.5, and PM 10 did not affect short-term and long-term survival in multivariable logistic regression.

CONCLUSIONS

The group of survivors showed slightly higher mean one-year concentrations of As, Cd and Pb, but they also experienced a higher incidence of OHCA in urban areas. There were no differences in long-term survival between patients who suffer OHCA in different quarters. Heavy metals did not independently affect survival.

Non-essential heavy metal effects in cardiovascular diseases: an overview of systematic reviews

Introduction

Cardiovascular diseases (CVDs) are the most important cause of premature death and disability worldwide. Environmental degradation and cardiovascular diseases are two keys to health challenges, characterized by a constant evolution in an industrialized world that exploits natural resources regardless of the consequences for health. The etiological risk factors of CVDs are widely known and include dyslipidemia, obesity, diabetes, and chronic cigarette consumption. However, one component that is often underestimated is exposure to heavy metals. The biological perspective explains that different metals play different roles. They are therefore classified into essential heavy metals, which are present in organisms where they perform important vital functions, especially in various physiological processes, or non-essential heavy metals, with a no biological role but, nonetheless, remain in the environment in which they are absorbed. Although both types of metal ions are many times chemically similar and can bind to the same biological ligands, the attention given today to nonessential metals in several eukaryotic species is starting to raise strong concerns due to an exponential increase in their concentrations. The aim of this systematic review was to assess possible correlations between exposure to nonessential heavy metals and increased incidence of cardiovascular disease, reporting the results of studies published in the last 5 years through March 2023.

Methods

The studies includes reviews retrieved from PubMed, Medline, Embase, and Web of Science databases, in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and following the PICO (Population Intervention Comparison Outcome Population) framework.

Results

Eight reviews, including a total of 153 studies, were identified. Seven of these review enlighted the association between CVDs and non-essential heavy metals chronic exposure.

Discussion

It is evident that exposure to heavy metals represent a risk factor for CVDs onset. However, further studies are needed to better understand the effects caused by these metals.

Race/ethnicity and sex differences in the association between area-level arsenic exposure concentration and hepatocellular carcinoma (HCC) incidence rates in Texas. An ecological study

INTRODUCTION

Texas has the highest rates of hepatocellular carcinoma (HCC) in the United States. Exposure to toxicants may play a role in liver disease. Several mechanisms of arsenic carcinogenesis have been proposed, however, the evidence in human populations is limited to associations between HCC and ingestion of arsenic-contaminated drinking water. Through an ecological study, we examined associations between ambient arsenic and HCC incidence rates.

METHODS

Primary outcome was HCC incidence rates based on Texas Cancer Registry (TCR) data. Primary exposure of interest was the simulated census-tract level estimate of arsenic exposure concentration (EC) from the U.S. Environmental Protection Agency 2011 National Air Toxics Assessment (NATA). We analyzed the association between the arsenic EC and HCC using the negative binomial Poisson regression model separately for six study groups that were based on race/ethnicity and sex. We adjusted the main analyses for selected characteristics.

RESULTS

Texas has 5265 census tracts and TCR reported 18,235 new ≥20 years old HCC diagnoses between 2007 and 2015. We observed significant differences along racial-ethnic and sex groups while accounting for socioeconomic deprivation, urban/rural residency, and senior residents' health insurance status. Census tracts with the highest arsenic EC had elevated rates of HCC among NH black men (Quintile 5 vs. Quintile 1: IRR = 2.18, 95% CI: 1.66-2.86), NH black women (Quintile 5 vs. Quintile 1: IRR = 1.72, 95% CI: 1.33-2.22) and NH white men (Quintile 5 vs. Quintile 1: IRR = 1.38, 95% CI: 1.24-1.54). The associations in the remaining study groups were either inconsistent or attenuated.

CONCLUSIONS

Our finding suggests a potential inhalation pathway for the Arsenic-HCC association; however, the ecological nature of our study precludes the interpretation of a causal link between exposure to aerial arsenic and HCC. This finding needs to be further examined in cohort studies.

The role of thioredoxin and glutathione systems in arsenic-induced liver injury in rats under glutathione depletion

Antioxidant systems like thioredoxin (Trx) and glutaredoxin (Grx) maintain oxidative stress balance. These systems have cross-talk supported by some in vitro studies. We investigated the underlying mechanisms of arsenic-induced liver injury in glutathione-deficient rats and whether there was any cross-talk between the Trx and Grx systems. The rats in arsenic-treated groups were administered with sodium arsenite (10, 20 mg/kg b w/d) for four weeks. In buthionine sulfoximine (BSO, an inhibitor of GSH) and 20 mg/kg arsenic combined groups, rats were injected with 2 mmol/kg BSO intraperitoneally twice per week. BSO exacerbated arsenic-induced liver injury by increasing arsenic accumulation in urine, serum, and liver while decreasing glutathione activity and resulting in upregulated mRNA expression of the Trx system and downregulation of Grx mRNA expression. The impact of Trx lasted longer than that of the Grx. The Trx system remained highly expressed, while GSH, Grx1, and Grx2 levels were decreased. The inhibitory effect of only BSO treatment on Grx1 and Grx2 was not pronounced. However, the combined impact of arsenic and BSO upregulated Trx expression, primarily related to further reduction of GSH. As a result, the suppressed Grxs were protected by the upregulated Trxs, which serve as a backup antioxidant defense system in the liver.

Heavy metals, oxidative stress, and the role of AhR signaling

The Aryl Hydrocarbon Receptor (AhR) is a ligand-activated transcriptional factor pivotal in responding to environmental stress and maintaining cellular homeostasis. Exposure to specific xenobiotics or industrial compounds in the environment activates AhR and its subsequent signaling, inducing oxidative stress and related toxicity. Past research has also identified and characterized several classes of endogenous ligands, particularly some tryptophan (Trp) metabolic/catabolic products, that act as AhR agonists, influencing a variety of physiological and pathological states, including the modulation of immune responses and cell death. Heavy metals, being non-essential elements in the human body, are generally perceived as toxic and hazardous, originating either naturally or from industrial activities. Emerging evidence indicates that heavy metals significantly influence AhR activation and its downstream signaling. This review consolidates current knowledge on the modulation of the AhR signaling pathway by heavy metals, explores the consequences of co-exposure to AhR ligands and heavy metals, and investigates the interplay between oxidative stress and AhR activation, focusing on the regulation of immune responses and ferroptosis.

Arsenic induced neurotoxicity in the brain of ducks: The potential involvement of the gut-brain axis

BACKGROUND

Arsenic is a widely distributed ecotoxic pollutant that has been found to cause neurotoxicity in a variety of species. Gut-brain axis is a two-way information network between the gut microbiome and the brain, which is closely related to organismal health. However, the role of the gut-brain axis in arsenic-induced neurotoxicity remains largely unknown.

METHODS

In order to explore whether there is a relationship between brain and gut microbiota of meat ducks, we performed molecular biological detection including RT-qPCR and Western blot, as well as morphological detection including, HE staining and immunohistochemistry. Meanwhile, intestinal contents were analyzed using 16 S ribosomal RNA gene sequencing and analysis RESULTS: In this study, we investigated whether arsenic trioxide (ATO) can activate the gut microbiome-brain axis to induce intestinal and brain injury. The results showed that ATO-exposure disrupted the diversity balance of intestinal microbiota and integrity and injured the intestinal structure. ATO-exposure also reduced the number of glycogen and goblet cells in the duodenum. In addition, exposure to ATO caused intestinal inflammatory injury by activating NF-κB signaling pathway and promoting the expression of its target genes. Meanwhile, the tight junction-related proteins (ZO-1, occludin) of gut and brain were reduced by ATO exposure. Furthermore, results also revealed that ATO-exposure induced brain injury, including neuronal cell vacuolization and reduced numbers of neuronal cells in the cortex and hippocampus. Remarkably, ATO-exposure also disrupted neurotransmitter levels. Additionally, our further molecular mechanism study revealed that ATO-exposure increased the expression of autophagy and apoptosis related mRNA and proteins levels in the brain tissues.

CONCLUSION

Altogether, these findings provide a new insight into that ATO-exposure induced intestinal injury and aggravated neurotoxicity via the gut-brain axis.

Overexpression of gamma-glutamyl cyclotransferase 2;1 (CsGGCT2;1) reduces arsenic toxicity and accumulation in Camelina sativa (L.)

KEY MESSAGE

Overexpressing CsGGCT2;1 in Camelina enhances arsenic tolerance, reducing arsenic accumulation by 40-60%. Genetically modified Camelina can potentially thrive on contaminated lands and help safeguard food quality and sustainable food and biofuel production. Environmental arsenic contamination is a serious global issue that adversely affects human health and diminishes the quality of harvested produce. Glutathione (GSH) is known to bind and detoxify arsenic and other toxic metals. A steady level of GSH is maintained within cells via the γ-glutamyl cycle. The γ-glutamyl cyclotransferases (GGCTs) have previously been shown to be involved in GSH degradation and increased tolerance to toxic metals in plants. In this study, we characterized the GGCT2;1 homolog from Camelina sativa for its role in arsenic tolerance and accumulation. Overexpression of CsGGCT2;1 in Camelina under CaMV35S constitutive promoter resulted in strong tolerance to arsenite (AsIII). The overexpression (OE) lines had 2.6-3.5-fold higher shoots and sevenfold to tenfold enhanced root biomass on media supplemented with AsIII, relative to wild-type plants. The CsGGCT2;1 OE lines accumulated 40-60% less arsenic in root and shoot tissues compared to wild-type plants. Further, the OE lines had ~ twofold higher chlorophyll content and 35% lesser levels of malondialdehyde (MDA), an indicator of membrane damage via lipid peroxidation. There was a slight but non-significant increase in 5-oxoproline (5-OP), a product of GSH degradation, in OE lines. However, the transcript levels of Oxoprolinase 1 (OXP1) were upregulated, indicating the accelerated conversion of 5-OP to glutamate, which is further utilized for the resynthesis of GSH to maintain GSH homeostasis. Overall, this research suggests that genetically modified Camelina may have the potential for cultivation on contaminated marginal lands to reduce As accumulation; thereby could help in addressing food safety issues as well as future food and biofuel needs.

Validation of the efficiency of arsenic mitigation strategies in southwestern region of Bangladesh and development of a cost-effective adsorbent to mitigate arsenic levels

World's highest arsenic (As) contamination is well-documented for the groundwater system of southwestern region (mainly Jashore district) of Bangladesh, where the majority of inhabitants are underprivileged. To mitigate As poisoning in southwestern Bangladesh, numerous steps have been taken so far by the government and non-governmental organizations (NGOs). Among them, digging deep tube wells and As removal by naturally deposited Fe(OH)3 species are being widely practiced in the contaminated areas. However, these actions have been left unmonitored for decades, making people unaware of this naturally occurring deadly poison in their drinking water. Hence, water samples (n = 63, both treated and untreated) and soil samples (n = 4) were collected from different spots in Jashore district to assess the safety level of drinking water and to understand the probable reasons for high As(III) contamination. About 93.7% of samples were found to contain As(III) above 10 μg/L; among them, 38% contained above 50 μg/L. The study shows that current As(III) removal strategies in the study area are ineffective. In this connection, a simple low-cost As(III) removal adsorbent is proposed that can be prepared with very cheap and locally available materials like iron sludge and charcoal. The adsorbent was characterized in terms of SEM, EDX, and XPS. The optimal dosage of the adsorbent was investigated for real-life application concerning several vital water quality parameters. The Fe-C adsorbent exhibited a maximum As(III) removal efficiency of 92% in real groundwater samples. The study will allow policymakers for informed decision-making regarding water body management as well as enable the local people to avail As-safe water in a way that aligns with their economic factors.

Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure

IMPORTANCE

In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.

Comparative analysis of the capability of the extended biotic ligand model and machine learning approaches to predict arsenate toxicity

Assessment of inorganic arsenate (As(V)) is critical for ensuring a sustainable environment because of its adverse effects on humans and ecosystems. This study is the first to attempt to predict As(V) toxicity to the bioluminescent bacterium Aliivibrio fischeri exposed to varying As(V) dosages and environmental factors (pH and phosphate concentration) using six machine learning (ML)-guided models. The predicted toxicity values were compared with those predicted using the extended biotic ligand model (BLM) we previously developed to evaluate the toxic effect of oxyanion (i.e., As(V)). The relationship between the variables (input features) and toxicity (output) was found to play an important role in the prediction accuracy of each ML-guided model. The results indicated that the extended BLM had the highest prediction accuracy, with a root mean square error (RMSE) of 12.997. However, with an RMSE of 14.361, the multilayer perceptron (MLP) model exhibited quasi-accurate prediction, despite having been trained with a relatively small dataset (n = 256). In view of simplicity, an MLP model is compatible with an extended BLM and does not require expert knowledge for the derivation of specific parameters, such as binding fraction and binding constant values. Furthermore, with the development and employment of reliable in-situ sensing techniques, monitoring data are expected to be augmented faster to provide sufficient training data for the improvement of prediction accuracy which may, thus, allow it to outperform the extended BLM after obtaining sufficient data.

Arsenic induces metabolome remodeling in mature human adipocytes

Human lifetime exposure to arsenic through drinking water, food supply or industrial pollution leads to its accumulation in many organs such as liver, kidneys, lungs or pancreas but also adipose tissue. Recently, population-based studies revealed the association between arsenic exposure and the development of metabolic diseases such as obesity and type 2 diabetes. To shed light on the molecular bases of such association, we determined the concentration that inhibited 17% of cell viability and investigated the effects of arsenic acute exposure on adipose-derived human mesenchymal stem cells differentiated in vitro into mature adipocytes and treated with sodium arsenite (NaAsO2, 10 nM to 10 µM). Untargeted metabolomics and gene expression analyses revealed a strong dose-dependent inhibition of lipogenesis and lipolysis induction, reducing the cellular ability to store lipids. These dysregulations were emphasized by the inhibition of the cellular response to insulin, as shown by the perturbation of several genes and metabolites involved in the mentioned biological pathways. Our study highlighted the activation of an adaptive oxidative stress response with the strong induction of metallothioneins and increased glutathione levels in response to arsenic accumulation that could exacerbate the decreased insulin sensitivity of the adipocytes. Arsenic exposure strongly affected the expression of arsenic transporters, responsible for arsenic influx and efflux, and induced a pro-inflammatory state in adipocytes by enhancing the expression of the inflammatory interleukin 6 (IL6). Collectively, our data showed that an acute exposure to low levels of arsenic concentrations alters key adipocyte functions, highlighting its contribution to the development of insulin resistance and the pathogenesis of metabolic disorders.

Scaling effects on arsenic release from excavated hydrothermally altered rocks in column experiments

The excavation of hydrothermally altered rocks from construction sites in Japan has raised concerns over environmental pollution due to the arsenic (As) release beyond the regulatory limit. An accurate assessment of As leaching from these rocks is imperative to understanding potential environmental implications and formulating efficient containment measures. However, the conduction of column leaching experiments to evaluate As leaching from these rocks encounters a lack of well-established protocols primarily due to the ambiguity surrounding scaling effects resulting from alterations in particle sizes and the corresponding column dimensions. Our study aimed to address this critical issue by conducting column percolation experiments on hydrothermally altered rocks of two distinct particle size ranges and rock layer thicknesses. The pH value was found to be proportional to the specific surface area (SSA) of rocks and the rock layer thickness in terms of H+ concentrations. Furthermore, the concentration and leachability of As showed a similar proportionality with the SSA. In contrast, the concentration of As remained relatively unaffected by the increased rock layer thickness, while the leachability of As was noticeably diminished in the column with a thicker rock layer. The absence of elevated As concentration and the decrease in leachability can be attributed to the enhanced As onto Fe/Al oxyhydroxides/oxides within the half-bottom part of the column with a thicker rock layer. Our findings underscore the importance of considering the SSA of rocks and rock layer thickness in the column experiments and help in the design of effective strategies to mitigate environmental contamination.

Hormonal Injustice: Environmental Toxicants as Drivers of Endocrine Health Disparities

The toll of multiple endocrine disorders has increased substantially in recent decades, and marginalized populations bear a disproportionate burden of disease. Because of the significant individual and societal impact of these conditions, it is essential to identify and address all modifiable risk factors contributing to these disparities. Abundant evidence now links endocrine dysfunction with exposure to endocrine-disrupting chemicals (EDCs), with greater exposures to multiple EDCs occurring among vulnerable groups, such as racial/ethnic minorities, those with low incomes, and others with high endocrine disease burdens. Identifying and eliminating EDC exposures is an essential step in achieving endocrine health equity.

Nephroprotective effect of diosmin against sodium arsenite-induced renal toxicity is mediated via attenuation of oxidative stress and inflammation in mice

Arsenic compounds, which are used in different industries like pesticide manufacturing, cause severe toxic effects in almost all organs, including the kidneys. Since the primary route of exposure to arsenic is through drinking water, and millions of people worldwide are exposed to unsafe levels of arsenic that can pose a threat to their health, this research was performed to investigate the nephroprotective effects of Diosmin (Dios), a flavonoid found in citrus fruits, against nephrotoxicity induced by sodium arsenite (SA). To induce nephrotoxicity, SA (10 mg/kg, oral gavage) was administered to mice for 30 days. Dios (25, 50, and 100 mg/kg, oral gavage) was given to mice for 30 days prior to SA administration. After the study was completed, animals were euthanized and blood and kidney samples were taken for biochemical and histopathological assessments. Results showed that SA-treated mice significantly increased the blood urea nitrogen and creatinine levels in the serum. This increase was associated with significant kidney tissue damage in SA-treated mice, which was confirmed by histopathological studies. Furthermore, SA enhanced the amounts of renal thiobarbituric acid reactive substances and decreased total thiol reserves, as well as the activity of antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase. Also, in the SA-exposed group, an increase in the levels of kidney inflammatory biomarkers, including nitric oxide and tumor necrosis factor-alpha was observed. The western blot analysis indicated an elevation in the protein expression of kidney injury molecule-1 and nuclear factor-kappa B in SA-treated mice. However, pretreatment with Dios ameliorated the SA-related renal damage in mice. Our findings suggest that Dios can protect the kidneys against the nephrotoxic effects of SA by its antioxidant and anti-inflammatory characteristics.

Tamarix articulata extract offers protection against toxicity induced by beauty products in Hs27 human skin fibroblasts

The current study evaluates the cytotoxicity, mode of cell death and chemical analysis of selected beauty products and evaluation of the protective effect of Tamarix articulata (TA) extract against toxicity induced by beauty products in skin fibroblasts (Hs27). MTT and Crystal violet (CV) assays were used to determine the dose-dependent cytotoxic effects of beauty products against Hs27 fibroblasts. DNA fragmentation assay and annexin-V staining were conducted to determine the mode of cell killing induced by evaluated beauty products. Quantification of reactive oxygen species (ROS) and antioxidant enzyme levels were used to evaluate the oxidative stress. Chemical analysis and heavy metals were evaluated to determine beauty products. Pre-treatment with TA extract for different time points followed by time-dependent exposure with beauty products to assess the protective effect of TA extract in Hs27 cells was analyzed by MTT and CV assays. Owing to the presence of various harmful heavy metals such as arsenic (As), chromium (Cr), cadmium (Cd), nickel (Ni), and lead (Pb) in beauty products, our results revealed that all beauty products induce significant cytotoxicity over time (1, 4 h) in a dose-dependent (125, 250, 500 μg/mL) manner. DNA fragmentation assay, quantification of apoptosis by annexin-V staining, determination of ROS and antioxidant enzymes (CAT, GSH-Px and SOD) revealed that the induced cytotoxicity was caused by oxidative stress-mediated apoptosis. However, pre-incubation with a safe dose (50 μg/mL) of TA for different times (24, 48 h) followed by exposure to various doses (62.5, 125, 250, 500 μg/mL) of beauty products for different times (1, 4 h) revealed significant (*p≤0.05, **p≤0.01) protection against beauty product-mediated cytotoxicity. The effect was more pronounced for 1 h exposure to beauty products compared to 4 h. Our study demonstrates that the due to the presence of heavy metals in synthetic beauty products exhibit marked toxicity to skin fibroblasts due to oxidative stress-mediated apoptosis. However, the presence of abundant bioactive polyphenols with promising antiscavenging activity in TA extracts significantly nullifies cytotoxicity promoted by examined beauty products in skin fibroblasts (Hs27).

Transcriptional responses of cancer cells to heat shock-inducing stimuli involve amplification of robust HSF1 binding

Responses of cells to stimuli are increasingly discovered to involve the binding of sequence-specific transcription factors outside of known target genes. We wanted to determine to what extent the genome-wide binding and function of a transcription factor are shaped by the cell type versus the stimulus. To do so, we induced the Heat Shock Response pathway in two different cancer cell lines with two different stimuli and related the binding of its master regulator HSF1 to nascent RNA and chromatin accessibility. Here, we show that HSF1 binding patterns retain their identity between basal conditions and under different magnitudes of activation, so that common HSF1 binding is globally associated with distinct transcription outcomes. HSF1-induced increase in DNA accessibility was modest in scale, but occurred predominantly at remote genomic sites. Apart from regulating transcription at existing elements including promoters and enhancers, HSF1 binding amplified during responses to stimuli may engage inactive chromatin.

Effect of arsenic and copper in kidney of mice: Crosstalk between Nrf2/ Keap1 pathway in apoptosis and pyroptosis

Arsenic (As) and copper (Cu) are two common contaminants in the environment. When organisms are exposed to As or/ and Cu in large quantities or for sustained periods, oxidative stress is induced, adversely affecting kidney function. However, the molecular mechanisms involved in As or/ and Cu-induced nephrotoxicity remain elusive. In this experiment, wild-type C57BL/6 and Nrf2-knockout mice (n = 24 each) were exposed to arsenic trioxide and copper chloride alone or in combination. Our research findings indicate that exposure to As or/ and Cu can activate the Nrf2 antioxidant pathway by upregulating the levels of Nrf2, HO-1, CAT, and downregulating the level of Keap1, thereby reducing As or/ and Cu-induced oxidative stress. Meanwhile, exposure induced kidney cell pyroptosis and apoptosis by promoting the expression of NLRP3 inflammasomes and Caspase-3, which peaked in mice co-treated with As and Cu. Subsequently, we investigated its role in As or/ and Cu-induced kidney injury by knocking out Nrf2. Our results show that after knocking out Nrf2, the expression of antioxidant factors CAT and HO-1 significantly decreased. Based on the low antioxidant capacity after Nrf2 knockout, the levels of NLRP3 inflammasome, GSDMD, and Caspase1 were significantly upregulated after exposure to As and Cu, indicating more severe cellular pyroptosis. In addition, the level of Caspase3-mediated apoptosis was also more severe. Taken together, there is crosstalk between Nrf2-mediated antioxidant capacity and apoptosis/ pyroptosis induced by exposure to As or/ and Cu. Depletion of Nrf2 alters its antioxidant capacity, ultimately leading to more severe apoptosis, pyroptosis, and nephrotoxicity.

Glutathione Might Attenuate Arsenic-Induced Liver Injury by Modulating the Foxa2-XIAP Axis to Reduce Oxidative Stress and Mitochondrial Apoptosis

Arsenic (AS) is a metalloid element that widely exists and can cause different degrees of liver damage. The molecular mechanism of arsenic-induced liver injury has yet to be fully elucidated. Clinically, glutathione (GSH) is often used as an antidote for heavy metal poisoning and hepatoprotective drugs. However, the hepatoprotective effect of glutathione remains unknown in arsenic-induced liver injury. The regulatory relationship between Foxa2 and XIAP may play an important role in mitochondrial survival and death. Therefore, we took Foxa2-XIAP as the axis to explore the protective mechanism of GSH. In this study, we first established a mouse model of chronic arsenic exposure and examined liver function as reflected by quantitative parameters such as aspartate aminotransferase and alanine aminotransferase. Also, redox parameters in the liver were measured, including malondialdehyde, superoxide dismutase, 8-hydroxy-2'-deoxyguanosin, and glutathione peroxidase. RT-qPCR and western-blotting were used to detect the levels of related genes and proteins, such as Foxa2, XIAP, Smac, Bax, Bcl2, Caspase9, and Caspase3. Subsequently, GSH was administered at the same time as high arsenic exposure, and changes in the above parameters were observed. After a comprehensive analysis of the above results, we demonstrate that GSH treatment alleviates arsenic-induced oxidative stress and inhibits the mitochondrial pathway of apoptosis, which can be regulated through the Foxa2 and XIAP axis. The present study would be helpful in elucidating the molecular mechanism of arsenic-induced liver injury and identifying a new potential therapeutic target. And we also provided new theoretical support for glutathione in the treatment of liver damage caused by arsenic.

Comparison of heavy metal pollution and ecological risk assessment in ballast tank sediments based on two applicable reference standards

The potential risks of ballast tank sediments have garnered global attention. This study collected sediment samples from ballast tanks of four transoceanic ships and determined 27 metal(loid) s by GB 5085.6-2007 and 9 metal(loid)s by GB 18668-2002. The pollution characteristics and ecological risk assessment of 8 typical heavy metals measured by both standards were analyzed and compared. Concentrations of Cd, Zn, and As were found to be high in the ballast tank sediments, and attention should also be directed toward Sn and Mn, which were rarely studied in ballast tank sediments. The concentration of Ni had significant differences between the two standards (P < 0.05). The results of ecological risk methods indicate that Cd, Zn, and As pose significant ecological risks. GB 5085.6-2007 demonstrated sensitivity in reflecting the ecological risks of heavy metals. Overall, this study provides valuable insights into establishing a unified standard for heavy metals for future ballast tank sediment management.

Connection between health risk and heavy metals in agricultural soils of China: a study based on current field investigations

Heavy metal pollution in agricultural soil is a threat to people's health and sustainable development. However, there is currently no nationwide health risk assessment in China. In this study, we performed a preliminary assessment of heavy metals in agricultural soils of the Chinese mainland, and found obvious carcinogenic risks (total lifetime carcinogenic risk (TLCR) > 1 × 10-5). A similar spatial distribution pattern was found in soil heavy metal and the mortality of esophagus and stomach cancers. Combining the potential carcinogenic risk assessed by LCR for individual heavy metal with Pearson correlation, Geographical Detector (q statistic > 0.75 for TLCR, p < 0.05), and redundancy analysis (RDA), it was found that long-term exposure and intake route of heavy metals exceeding the maximum safety threshold (Health Canada standard) may induce digestive system (esophagus, stomach, liver, and colorectum) cancers in rural populations. Through Partial Least Squares Path Model (PLS-PM), it was also revealed that the LCR of heavy metals was closely related to the soil environmental background (path coefficients = 0.82), which in turn was affected by factors such as economic development and pollution discharge. The current research results highlight the potential carcinogenic risk to the digestive system associated with low-dose and long-term exposure to heavy metals in agricultural soils, and policymakers should propose countermeasures and solutions according to the local conditions.

The disruption of blood-brain barrier induced by long-term arsenic exposure is associated with the increase of MMP-9 and MMP-2: The characteristics are similar to those caused by senescence

Accumulating evidence suggests that Matrix metalloproteinase-9 (MMP-9) and -2 (MMP-2) are involved in the neuropathological processes by contributing to breaking the extracellular matrix and the tight junctions that constitute the blood-brain barrier (BBB). However, the influences of arsenic (As) on these two MMPs were inconsistent. In the cross-sectional study of 500 adults, serum MMP-2 and MMP-9 positively correlated with urine arsenic. And the positive correlation between urine tAs and serum MMP-9/2 was found in people older than 59 years. In vivo studies, we found that arsenic exposure or senescence might decrease number of neurons and neuritic density and increase serum and cortical MMP-9/2 levels. Furthermore, arsenic exposure or senescence could disrupt the tight junction of BBB and elevate MMP-9 and MMP-2 expression in the cerebral microvascular endothelium. The MMP-9 and MMP-2 are of particular interest when researching the link between arsenic exposure and nerve damage.

Study on the correlation and interaction between metals and dyslipidemia: a case-control study in Chinese community-dwelling elderly

Previous studies on the association between metals and dyslipidemia are not completely consistent. There are few studies investigating the relationship between mixed metal exposure and dyslipidemia as well as the effects of metals on dyslipidemia in community-dwelling elderly. To evaluate the correlations and interaction effect between the urinary concentrations of metals and the risk of dyslipidemia in community-dwelling elderly. We designed a case-control study to assess the correlation between urine metals and dyslipidemia in elderly people in the Yinchuan. The urinary levels of 13 metals, including calcium, vanadium, iron, cobalt, zinc, copper, arsenic, selenium, molybdenum, cadmium, tellurium, and thallium, were measured by inductively coupled plasma-mass spectrometry (ICP-MS), and the blood biochemical analyzer was used to measure the blood lipid levels of 3384 senior individuals from four different areas of Yinchuan city. Logistic regression and restricted cubic splines (RCS) were used to explore the correlation and dose-response relationship between urinary metals and the risk of dyslipidemia. Least absolute shrinkage and selection operator (LASSO) regression was used to select metals, and then weighted quantile sum (WQS) regression was used to explore the weight of each metal in mixed metals. Bayesian kernel machine regression (BKMR) was used to explore the interactions between metals on dyslipidemia risk. (1) After selection by LASSO regression, in the multi-metal model, compared with the lowest quartile, the adjusted ORs (95%CI) of the highest quartiles were 0.47 (0.37-0.60) for Fe, 1.43 (1.13-1.83) for Zn, 1.46 (1.11-1.92) for As, 0.59 (0.44-0.80) for Se, 1.53 (1.18-2.00) for Mo, and 1.36 (1.07-1.73) for Te. (2) In the WQS regression model, Fe and Mo accounted for the largest weight in the negative and positive effects of dyslipidemia, respectively. (3) In the BKMR model, there may be a positive interaction between Te and Se on dyslipidemia. Among the mixed metals, Fe, As, Se, Mo, and Te were associated with the prevalence of dyslipidemia, with Fe and Mo contributing the most. There may be certain interactions between Te and Se.

Effects of Early Life Oral Arsenic Exposure on Intestinal Tract Development and Lipid Homeostasis in Neonatal Mice: Implications for NAFLD Development

BACKGROUND

Newborns can be exposed to inorganic arsenic (iAs) through contaminated drinking water, formula, and other infant foods. Epidemiological studies have demonstrated a positive association between urinary iAs levels and the risk of developing nonalcoholic fatty liver disease (NAFLD) among U.S. adolescents and adults.

OBJECTIVES

The present study examined how oral iAs administration to neonatal mice impacts the intestinal tract, which acts as an early mediator for NAFLD.

METHODS

Neonatal mice were treated with a single dose of iAs via oral gavage. Effects on the small intestine were determined by histological examination, RNA sequencing, and biochemical analysis. Serum lipid profiling was analyzed by fast protein liquid chromatography (FPLC), and hepatosteatosis was characterized histologically and biochemically. Liver X receptor-alpha (LXR α ) knockout (L x r α - / - ) mice and liver-specific activating transcription factor 4 (ATF4)-deficient (A t f 4 Δ H e p ) mice were used to define their roles in iAs-induced effects during the neonatal stage.

RESULTS

Neonatal mice exposed to iAs via oral gavage exhibited accumulation of dietary fat in enterocytes, with higher levels of enterocyte triglycerides and free fatty acids. These mice also showed accelerated enterocyte maturation and a longer small intestine. This was accompanied by higher levels of liver-derived very low-density lipoprotein and low-density lipoprotein triglycerides, and a lower level of high-density lipoprotein cholesterol in the serum. Mice exposed during the neonatal period to oral iAs also developed hepatosteatosis. Compared with the control group, iAs-induced fat accumulation in enterocytes became more significant in neonatal L x r α - / - mice, accompanied by accelerated intestinal growth, hypertriglyceridemia, and hepatosteatosis. In contrast, regardless of enterocyte fat accumulation, hepatosteatosis was largely reduced in iAs-treated neonatal A t f 4 Δ H e p mice.

CONCLUSION

Exposure to iAs in neonatal mice resulted in excessive accumulation of fat in enterocytes, disrupting lipid homeostasis in the serum and liver, revealing the importance of the gut-liver axis and endoplasmic reticulum stress in mediating iAs-induced NAFLD at an early age. https://doi.org/10.1289/EHP12381.

Alcohol consumption promotes arsenic absorption but reduces tissue arsenic accumulation in mice

Alcohol consumption alters gut microflora and damages intestinal tight junction barriers, which may affect arsenic (As) oral bioavailability. In this study, mice were exposed to arsenate in the diet (6 μg/g) over a 3-week period and gavaged daily with Chinese liquor (0.05 or 0.10 mL per mouse per day). Following ingestion, 78.0% and 72.9% of the total As intake was absorbed and excreted via urine when co-exposed with liquor at daily doses of 0.05 or 0.10 mL, significantly greater than when As was supplied alone (44.7%). Alcohol co-exposure significantly altered gut microbiota but did not significantly alter As biotransformation in the intestinal tract or tissue. Significantly lower relative mRNA expression was observed for genes encoding for tight junctions in the ileum of liquor co-exposed mice, contributing to greater As bioavailability attributable to enhanced As absorption via the intestinal paracellular pathway. However, As concentration in the liver, kidney, and intestinal tissue of liquor-treated mice was decreased by 24.4%-42.6%, 27.5%-38.1%, and 28.1%-48.9% compared to control mice. This was likely due to greater renal glomerular filtration rate induced by alcohol, as suggested by significantly lower expression of genes encoding for renal tight junctions. In addition, in mice gavaged daily with 0.05 mL liquor, the serum antidiuretic hormone level was significantly lower than control mice (2.83 ± 0.59 vs. 5.40 ± 1.10 pg/mL), suggesting the diuretic function of alcohol consumption, which may facilitate As elimination via urine. These results highlight that alcohol consumption has a significant impact on the bioavailability and accumulation of As.

Exposure to arsenic, polycyclic aromatic hydrocarbons, metals, and association with skin cancers in the US adults

Worldwide, skin cancer affects millions of people yearly and is broadly classified into melanoma and nonmelanoma types of skin cancer. The toxicity of metals to human health is a public and clinical health problem due to their widespread use in tools, machinery, and appliances as well as their widespread distribution in the air, water, and soil. Arsenic is a carcinogenic metalloid and available in the Earth's crust. Polycyclic aromatic hydrocarbons (PAHs) are toxic to humans, and incomplete combustion of fossil fuels is the main source of PAHs. Human populations exposed to metals from various sources can lead to various diseases including cancer. Limited studies are conducted to simultaneously assess the correlation of multiple arsenic, PAHs, metals with the occurrence of skin cancer. This study aimed to analyze the association between six PAHs compounds, seven types of arsenic, and fourteen metals from urine specimen with skin cancer in US adults. We performed a cross-sectional analysis using data from a total of 14,716 adults from the National Health Examination and Nutrition Survey (NHANES) database for three cycles ranging from 2011-2012 to 2015-2016. Specialized weighted complex survey logit regressions were conducted. Linear logit regression models using only main effects were performed first to identify the correlation between the selected demographic and lifestyle variables and melanoma, nonmelanoma, and unknown types of skin cancer. A second set of linear, main-effects logit regression models were constructed to examine the correlation between melanoma, nonmelanoma, and other types of skin cancers and seven types of arsenic (arsenous acid, arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid, monomethylacrsonic acid, and total arsenic), six PAHs (1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenathrene, and 1-hydroxypyrene), and fourteen metals (barium, cadmium, cobalt, cesium, molybdenum, manganese, lead, antimony, tin, strontium, thallium, tungsten, uranium, and mercury) when adjusted for the selected covariates. The statistical analysis was conducted using R software, version 4.0.4. A marginal positive significant correlation between total arsenic and nonmelanoma was observed. This study identified a significant positive association between barium, cadmium, cesium, mercury, tin, and melanoma development. Cesium showed a significant positive statistical association for nonmelanoma, and thallium showed a borderline significant statistical association for nonmelanoma. A statistically significant positive association was found between cadmium and an unknown type of skin cancer. The findings of this study indicated a statistically significant positive association between skin cancer and barium, cadmium, cesium, tin, mercury, and thallium. Further studies are recommended in humans to refute or confirm these findings.

Multifunctional Roles of Dihydrotetrazine-Decorated Zr-MOFs in Photoluminescence and Colorimetrism for Discrimination of Arsenate and Phosphate Ions in Water

The high chemical and structural stabilities of zirconium (Zr)-based metal-organic frameworks (MOFs) in aquatic media make them ideal candidates for wastewater treatment. Rational decoration or Zr-MOFs with functional groups can significantly extend their application in this area. In this work, two well-known Zr-MOFs, UiO-66 and MIL-140-A, were functionalized with dihydrotetrazine function to increase their capability in water treatment. Investigations reveal that these two dihydrotetrazine (DHTZ)-functionalized MOFs, namely UiO-66(Zr)-DHTZ and MIL-140(Zr)-DHTZ, can be applied as a two-component array for highly selective and sensitive discrimination of arsenate (AsO43-) and phosphate (PO43-) ions in water in the presence of other anions. Photoluminescence (PL) tests using UiO-66(Zr)-DHTZ show that this MOF can detect these two anions via a ratiometric response, 1.74 for arsenate and 1.84 for phosphate at 2 μM, with superior detection limits (7.2 × 10-8 M for AsO43- and 4.3 × 10-8 M for PO43-). The ratiometric PL response of UiO-66(Zr)-DHTZ toward arsenate and phosphate anions arises possibly from the arsenate-dihydrotetrazine hydrogen bonding. In the next step, colorimetric tests using MIL-140(Zr)-DHTZ were conducted to discriminate the arsenate from phosphate with a very low detection limit at nanomolar level. This MOF undergoes a yellow-to-pink color change in the presence of arsenate ions, while no color change is observed in the presence of phosphate. This color change is observed through conversion of dihydrotetrazine sites inside the pores of MIL-140(Zr)-DHTZ into tetrazine. Altogether, the PL response of UiO-66(Zr)-DHTZ is originated from the hydrogen bond-donating/accepting character of DHTZ function, while the colorimetric response of MIL-140(Zr)-DHTZ is based on the chemical conversion of DHTZ function. This work clearly shows that the decoration of Zr-based MOFs with multicharacter functional groups can develop their application in wastewater treatment as multipurpose platforms.

Fenugreek seed powder protects mice against arsenic-induced neurobehavioral changes

The current study was designed to evaluate the protective effect of fenugreek seed powder against As-induced neurobehavioral and biochemical perturbations using a mouse model. Mice exposed to arsenic at 10 mg/kg body weight showed development of anxiety-like behavior and memory impairment compared to control mice in elevated plus maze and Morris water maze tests, respectively. A significantly decreased acetyl and butyrylcholinesterase, superoxide dismutase and glutathione reductase activities and brain-derived neurotrophic factor levels were found in the brain of arsenic-exposed mice compared to control mice. Interestingly, supplementation of fenugreek seed powder to arsenic-treated mice significantly restored the activity of cholinesterase and antioxidant enzymes (e.g. superoxide dismutase, glutathione reductase) as well as brain-derived neurotrophic factor levels in the brain tissue of arsenic-exposed mice. Consequently, reduced anxiety-like behavior, improved learning and memory were observed in fenugreek supplemented arsenic treated mice compared to only arsenic-exposed mice group. Thus, this study suggests that fenugreek seed powder reduces arsenic-induced neurotoxicity in mice.

The Protective Effects of Trametes Versicolor on Arsenic-Induced Male Reproductive Toxicity through Regulation of Oxidative Stress: A Biochemical and Histopathological Survey

Exposure to arsenic is linked to a wide range of diseases, in particular male reproductive toxicities. Trametes versicolor is a traditional medicinal fungus with a remarkable potential for antioxidant activity. The purpose of this study was to examine the ameliorating effects of water and methanol extracts of T. versicolor on arsenic-induced male reproductive toxicities via the abrogation of oxidative stress. The mice were divided as follows: control: normal saline, As: arsenic (15 mg/kg), WE: water extract (400 mg/kg), ME: methanol extract (400 mg/kg), As + WE: arsenic (15 mg/kg) + water extract (100, 200, 400 mg/kg), As + ME: arsenic (15 mg/kg) + methanol extract (100, 200, 400 mg/kg), and positive control: arsenic (15 mg/kg) + vitamin C (500 mg/kg). Animals were treated via the intraperitoneal route. About 24 hr later, the mice were euthanized, and oxidative stress parameters (reactive oxygen species [ROS], lipid peroxidation, glutathione concentration, protein carbonylation, glutathione peroxidase, and superoxide dismutase activity), histopathological changes and sperm parameters (count, motility, and morphology) were examined in the testicular tissue. Arsenic caused significant pathological changes in the testicular tissue and sperm morphology and significantly reduced sperm count and motility. Moreover, arsenic mediated oxidative stress via significant increases in ROS generation, lipid peroxidation, and protein carbonyl content, as well as significant depletion in glutathione concentration and superoxide dismutase and glutathione peroxidase activities. Although, coadministration of water and methanol extracts of T. versicolor at 200 and 400 mg/kg counteracted arsenic-induced oxidative and histopathological damages and improved sperm parameters. Our study indicated that T. versicolor ameliorated arsenic-induced testis toxicity and sperm dysfunction via attenuation of oxidative damage.

Organoiridium Complexes Enhance Cellular Defense Against Reactive Aldehydes Species

Although reactive aldehyde species (RASP) are associated with the pathogenesis of many major diseases, there are currently no clinically approved treatments for RASP overload. Conventional aldehyde detox agents are stoichiometric reactants that get consumed upon reacting with their biological targets, which limits their therapeutic efficiency. To achieve longer-lasting detoxification effects, small-molecule intracellular metal catalysts (SIMCats) were used to protect cells by converting RASP into non-toxic alcohols. It was shown that SIMCats were significantly more effective in lowering cell death from the treatment with 4-hydroxynon-2-enal than aldehyde scavengers over a 72 h period. Studies revealed that SIMCats reduced the aldehyde accumulation in cells exposed to the known RASP inducer arsenic trioxide. This work demonstrates that SIMCats offer unique benefits over stochiometric agents, potentially providing new ways to combat diseases with greater selectivity and efficiency than existing approaches.

Four cases of fatal acute arsenic poisoning: histopathology, toxicology, and new trends

Arsenic is a valuable component in tumor treatment and traditional Chinese medicine and has seen widespread use in processing, manufacturing, and agriculture. Although rare, arsenic poisoning can occur in forensic practice. Elusive pathological changes, as well as obscure clinical signs, may cause arsenic poisoning to go unrecognized. Here, we report four cases of fatal acute arsenic poisoning, with careful observation of pathological changes and collection of postmortem specimens for arsenic concentration analysis. Additionally, we reviewed six cases of fatal arsenic poisoning in the past 20 years. In the present study, microvesicular steatosis in the peripheral areas of the hepatic lobules and acute splenitis were observed, which are rare findings in acute arsenic poisoning. This study summarizes the histopathological features of arsenic poisoning and presents data on arsenic distribution. Arsenic concentrations in the liver and kidneys can increase the reliability of identifying arsenic poisoning. Furthermore, in traditional Chinese medicine-related deaths, arsenic poisoning needs more attention.

Increased hypertension risk for the elderly with high blood levels of strontium and lead

Hypertension has long been recognized as the global health burden. Heavy metal pollution may be one of the environmental risk factors of hypertension. However, the association remains unclear. We studied the levels of aluminum (Al), vanadium (V), manganese (Mn), arsenic (As), selenium (Se), strontium (Sr), barium (Ba), titanium (Ti), lead (Pb) and cobalt (Co) in whole blood, and the relationship between trace element exposure and hypertension in the elderly community-based Chinese population. A total of 1013 participants from the west of Anhui Province in China were consecutively enrolled in this study in 2016. The general sociodemographic characteristics, lifestyles, disease history and physical examination information were collected by face-to-face survey and physical examination. The levels of ten trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). Multivariable logistic regression model was used to assess the association of trace element exposure with the risk of hypertension. Results showed that the odds ratio of hypertension in the highest quartile was 1.811 (95% CI 1.175-2.790, P trend = 0.005) and 1.772 (95% CI 1.121-2.800, P trend = 0.022), respectively, after adjusting for potential confounders, as compared with the lowest quartile of blood Pb and Sr levels.

Effects of Non-Essential "Toxic" Trace Elements on Pregnancy Outcomes: A Narrative Overview of Recent Literature Syntheses

Adverse pregnancy outcomes and their complications cause increased maternal and neonatal morbidity and mortality and contribute considerably to the global burden of disease. In the last two decades, numerous narrative and systematic reviews have emerged assessing non-essential, potentially harmful, trace element exposure as a potential risk factor. This narrative review summarizes the recent literature covering associations between exposure to cadmium, lead, arsenic, and mercury and pregnancy outcomes and highlights common limitations of existing evidence that may hinder decision-making within public health. Several initial scoping searches informed our review, and we searched PubMed (latest date July 2022) for the literature published within the last five years reporting on cadmium, lead, arsenic, or mercury and pre-eclampsia, preterm birth, or prenatal growth. Pre-eclampsia may be associated with cadmium and strongly associated with lead exposure, and exposure to these metals may increase risk of preterm birth. Many reviews have observed cadmium to be negatively associated with birth weight. Additionally, lead and arsenic exposure may be negatively associated with birth weight, with arsenic exposure also adversely affecting birth length and head circumference. These findings should be interpreted with caution due to the limitations of the reviews summarized in this paper, including high heterogeneity due to different exposure assessment methods, study designs, and timing of sampling. Other common limitations were the low quality of the included studies, differences in confounding variables, the low number of studies, and small sample sizes.

Individual, Independent, and Joint Associations of Toxic Metals and Manganese on Hypertensive Disorders of Pregnancy: Results from the MIREC Canadian Pregnancy Cohort

BACKGROUND

Toxic metals, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg), may be associated with a higher risk of gestational hypertension and preeclampsia, whereas manganese (Mn) is an essential metal that may be protective.

OBJECTIVES

We estimated the individual, independent, and joint associations of Pb, Cd, As, Hg, and Mn on the risk of developing gestational hypertension and preeclampsia in a cohort of Canadian women.

METHODS

Metal concentrations were analyzed in first and third trimester maternal blood (n=1,560). We measured blood pressure after 20 wk gestation to diagnose gestational hypertension, whereas proteinuria and other complications defined preeclampsia. We estimated individual and independent (adjusted for coexposure) relative risks (RRs) for each doubling of metal concentrations and examined interactions between toxic metals and Mn. We used quantile g-computation to estimate the joint effect of trimester-specific exposures.

RESULTS

Each doubling of third trimester Pb (RR=1.54; 95% CI: 1.06, 2.22) and first trimester blood As (RR=1.25; 95% CI: 1.01, 1.58) was independently associated with a higher risk of developing preeclampsia. First trimester blood As (RR=3.40; 95% CI: 1.40, 8.28) and Mn (RR=0.63; 95% CI: 0.42, 0.94) concentrations were associated with a higher and lower risk, respectively, of developing gestational hypertension. Mn modified the association with As such that the deleterious association with As was stronger at lower concentrations of Mn. First trimester urinary dimethylarsinic acid concentrations were not associated with gestational hypertension (RR=1.31; 95% CI: 0.60, 2.85) or preeclampsia (RR=0.92; 95% CI: 0.68, 1.24). We did not observe overall joint effects for blood metals.

DISCUSSION

Our results confirm that even low blood Pb concentrations are a risk factor for preeclampsia. Women with higher blood As concentrations combined with lower Mn in early pregnancy were more likely to develop gestational hypertension. These pregnancy complications impact maternal and neonatal health. Understanding the contribution of toxic metals and Mn is of public health importance. https://doi.org/10.1289/EHP10825.

The role of hypoxia-inducible factor 1 alpha (HIF-1α) modulation in heavy metal toxicity

Hypoxia-inducible factor 1 (HIF-1) is an oxygen-sensing transcriptional regulator orchestrating a complex of adaptive cellular responses to hypoxia. Several studies have demonstrated that toxic metal exposure may also modulate HIF-1α signal transduction pathway, although the existing data are scarce. Therefore, the present review aims to summarize the existing data on the effects of toxic metals on HIF-1 signaling and the potential underlying mechanisms with a special focus on prooxidant effect of the metals. The particular effect of metals was shown to be dependent on cell type, varying from down- to up-regulation of HIF-1 pathway. Inhibition of HIF-1 signaling may contribute to impaired hypoxic tolerance and adaptation, thus promoting hypoxic damage in the cells. In contrast, its metal-induced activation may result in increased tolerance to hypoxia through increased angiogenesis, thus promoting tumor growth and contributing to carcinogenic effect of heavy metals. Up-regulation of HIF-1 signaling is mainly observed upon Cr, As, and Ni exposure, whereas Cd and Hg may both stimulate and inhibit HIF-1 pathway. The mechanisms underlying the influence of toxic metal exposure on HIF-1 signaling involve modulation of prolyl hydroxylases (PHD2) activity, as well as interference with other tightly related pathways including Nrf2, PI3K/Akt, NF-κB, and MAPK signaling. These effects are at least partially mediated by metal-induced ROS generation. Hypothetically, maintenance of adequate HIF-1 signaling upon toxic metal exposure through direct (PHD2 modulation) or indirect (antioxidant) mechanisms may provide an additional strategy for prevention of adverse effects of metal toxicity.

Arsenic Trioxide Triggers Mitochondrial Dysfunction, Oxidative Stress, and Apoptosis via Nrf 2/Caspase 3 Signaling Pathway in Heart of Ducks

Arsenic is a common environmental pollutant and poses a serious threat to human and animal health. In this study, we used the ducks to mimic arsenic trioxide (ATO) exposure and investigated the mechanism of cardiac toxicity. The results indicated that ATO inhibited the body and organ growth of ducks, led to an increase in LDH content, and caused obvious deformity, ischemia infarction. It is found that ATO exacerbated the swell of mitochondrial and the contraction of cell nuclei in the heart of ducks through transmission electron microscopy (TEM). ATO also induced an increase in MDA content; inhibited the activation of the Nrf 2 pathway; downregulated the expression of mRNA and protein of Nrf 2, HO-1, and SOD-1; and upregulated the expression of mRNA and protein of Keap 1. At the same time, ATO induced apoptosis which not only upregulated the expression levels of mRNA and proteins (Caspase 3, Cyt-C, P53, Bax) but also decreased the mRNA and protein expression level of Bcl-2. These results indicated that ATO can lead to oxidative stress and apoptosis in the heart of ducks. In general, our research shows that ATO triggers mitochondrial dysfunction, oxidative stress, and apoptosis via Nrf 2/Caspase 3 signaling pathway in the heart of ducks.

The possible protective role of vitamin C versus melatonin on potassium dichromate induced changes in rat thyroid gland: light and electron microscopic study

Potassium dichromate is widely used in various laboratory and industrial applications. Vitamin C and melatonin are well-known antioxidants. Study the microscopic and morphometric alterations in the thyroid gland in adult male albino rats after the administration of potassium dichromate for successive 2 months and also to assess the possible protective effect of vitamin C versus melatonin on these changes. Sixty adult male albino rats were randomly divided into four main groups. Group I (The control group). Group II received potassium dichromate (25 mg/kg/day) dissolved in distilled water by intraperitoneal (i.p) injection for 2 months. Group III received the same dose of potassium dichromate with vitamin C (120 mg/kg/day) orally through an intragastric intubation. Group IV received the same dose of potassium dichromate and melatonin (10 mg/kg/day) as an i.p injection. Thyroid gland samples were prepared for light and electron microscopic studies. Potassium dichromate group demonstrated congested blood vessels, follicular hyperplasia, follicular enlargement with degenerated lining cells that were exfoliated in the lumen. The parafollicular cells appeared with darkly stained nuclei. PAS reaction showed weak reaction in the colloid with an abnormal pattern of vacuolization. A highly significant increase in the percentage area of fibrosis was detected in Mallory trichrome sections. Ultrastructurally, follicular cells and parafollicular cells appeared irregular in shape with dark, small heterochromatic nuclei. Small, electron-dense granules in the parafollicular cells were found. Potassium dichromate and vitamin C-treated group III showed partial improvement of the thyroid gland. The PAS reaction showed that nearly all the follicles were more or less similar to those of the control group. A significant decrease in the percentage area of fibrosis in group III was found as compared to those in group II. Potassium dichromate and melatonin-treated group showed that the thyroid gland was nearly similar to that of the control group. Vitamin C and melatonin could partially protect against potassium dichromate induced changes in the thyroid gland and the protective effect of melatonin was better than that of vitamin C.

Arsenic-Loaded Biomimetic Iron Oxide Nanoparticles for Enhanced Ferroptosis-Inducing Therapy of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has a poor response to most available systemic therapies due to intrinsic or acquired resistance to apoptosis. Ferroptosis-based therapy is expected to circumvent those limitations. Therefore, the rational design of ferroptosis-based therapies with targeted delivery of ferroptosis inducers for HCC is in need. In this study, we found that arsenic trioxide (ATO) can efficiently induce ferroptosis in HCC cells, and this effect could be reversed by the iron chelator deferoxamine. On this basis, a drug delivery system was constructed to enhance the therapeutic efficacy of ATO by camouflaging ATO-loaded magnetic nanoparticles (Fe3O4) with HCC cell membranes, termed AFN@CM. After AFN@CM treatment, glutathione peroxidase 4 was strongly inhibited and intracellular lipid peroxide species were significantly increased in HCC cells. In addition, enhanced ferroptosis and tumor suppression were observed both in vitro and in vivo. The bio-safety of AFN@CM was also demonstrated by the in vivo toxicity evaluation. In addition, benefiting from the cell membrane coating, AFN@CM showed enhanced accumulation at tumor sites and achieved continuous tumor elimination in the mouse model. In conclusion, AFN@CM exhibited satisfactory therapeutic efficacy in the treatment of HCC and provided a desirable ferroptosis-based strategy for safe and reliable HCC therapeutics.

Supplementation with sesame oil suppresses genotoxicity, hepatotoxicity and enterotoxicity induced by sodium arsenite in rats

BACKGROUND

Sesame oil, an edible essential oil, is known to be rich in unsaturated fatty acids, vitamins and lignans with several reported health-promoting benefits. Acute arsenic poisoning produces toxic hepatitis, bone marrow depression and adverse gastrointestinal responses. In this study, we investigated the protective effect of sesame seed oil (SSO) against genotoxicity, hepatotoxicity and colonic toxicity induced by sodium arsenite (SA) in Wistar rats.

METHODS

Twenty-eight male Wistar albino rats were randomly allocated into four groups: control, SA only (2.5 mg/kg), SA + SSO (4 ml/kg) and SSO alone for eight consecutive days. Liver function and morphology, bone marrow micronuclei induction, colonic histopathology, mucus production and immune expression of Bcl-2, carcinoembryonic antigen (CEA), MUC1 and cytokeratins AE1/AE3 were evaluated.

RESULTS

SA provoked increased serum activities of liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and caused severely altered morphology of hepatic and colonic tissues with increased frequency of micronucleated polychromatic erythrocytes (MnPCEs/1000PCE) in the bone marrow. In addition, SA triggered increased expression of colonic CEA and MUC1 but weak Bcl-2 immunoexpression. However, cotreatment with SSO demonstrated protective activities against SA-induced damage, as indicated by significantly reduced serum ALT and AST, fewer micronucleated bone marrow erythrocytes and well-preserved hepatic and colonic morphologies compared to the SA-treated rats. Furthermore, SSO protected the colonic mucosa by boosting mucus production, elevating anti-apoptotic Bcl-2 expression and reducing CEA expression. GC-MS analysis of SSO revealed that it was predominated by linoleic acid, an omega-3 fatty acid, and tocopherols.

CONCLUSIONS

Our data indicated that SSO protected the liver, colon and bone marrow potentially via anti-inflammatory and anti-apoptotic activities. The data suggest that sesame oil has potential therapeutic applications against chemical toxicities induced by arsenic.

Telomeres susceptibility to environmental arsenic exposure: Shortening or lengthening?

Maintaining telomere length plays a crucial role in regulating cellular life span. Telomere lengthening or shortening is one of the important biomarkers which could predict the preceding or present diseases. Meanwhile, the impact of environmental arsenic exposure on telomere length has increasingly concerned. Although previous studies demonstrated the effects of arsenic on telomere length, the findings were unclear on whether telomere shortens or lengthens by arsenic exposure. Thus, this manuscript summarized and discussed the telomere length alteration following arsenic exposure and the possible does-response effect of arsenic on telomere length. The present review suggested that different age groups may respond differently to arsenic exposure, and the dose-response effect of arsenic could be a critical factor in its effect on telomere length. Moreover, speciation analysis of arsenic could be more informative in identifying the effect of arsenic on telomere length.

Endogenous humoral determinants of vascular endothelial dysfunction as triggers of acute poisoning complications

The vascular endothelium is not only the semipermeable membrane that separates tissue from blood but also an organ that regulates inflammation, vascular tone, blood clotting, angiogenesis and synthesis of connective tissue proteins. It is susceptible to the direct cytotoxic action of numerous xenobiotics and to the acute hypoxia that accompanies acute poisoning. This damage is superimposed on the preformed state of the vascular endothelium, which, in turn, depends on many humoral factors. The probability that an exogenous toxicant will cause life-threatening dysfunction of the vascular endothelium, thereby complicating the course of acute poisoning, increases with an increase in the content of endogenous substances in the blood that disrupt endothelial function. These include ammonia, bacterial endotoxin, indoxyl sulfate, para-cresyl sulfate, trimethylamine N-oxide, asymmetric dimethylarginine, glucose, homocysteine, low-density and very-low-density lipoproteins, free fatty acids and products of intravascular haemolysis. Some other endogenous substances (albumin, haptoglobin, haemopexin, biliverdin, bilirubin, tetrahydrobiopterin) or food-derived compounds (ascorbic acid, rutin, omega-3 polyunsaturated fatty acids, etc.) reduce the risk of lethal vascular endothelial dysfunction. The individual variability of the content of these substances in the blood contributes to the stochasticity of the complications of acute poisoning and is a promising target for the risk reduction measures. Another feasible option may be the repositioning of drugs that affect the function of the vascular endothelium while being currently used for other indications.

Gene expression analysis of antioxidant and DNA methylation on the rat liver after 4-week wood preservative chromated copper arsenate exposure

Our previous 4-week repeated dose toxicity study showed that wood preservative chromated copper arsenate (CCA) induced hepatocellular hypertrophy accompanied by biochemical hepatic dysfunction and an increase in oxidative stress marker, 8-hydroxydeoxyguanosine, in female rats. To further explore the molecular mechanisms of CCA hepatotoxicity, we analyzed 10%-buffered formalin-fixed liver samples from female rats for cell proliferation, apoptosis, and protein glutathionylation and conducted microarray analysis on frozen liver samples from female rats treated with 0 or 80 mg/kg/day of CCA. Chemical analysis revealed that dimethylated arsenical was the major metabolite in liver tissues of male and female rats. CCA increase labeling indices of proliferating cell nuclear antigen and decrease terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling accompanied with increased expression of protein glutathionylation, indicating a decrease in glutathione (GSH) in hepatocytes of female rats. Microarray analysis revealed that CCA altered gene expression of antioxidants, glutathione-S-transferase (GST), heat shock proteins and ubiquitin-proteasome pathway, cell proliferation, apoptosis, DNA methylation, cytochrome P450, and glucose and lipid metabolism in female rats. Increased expression of GSTs, including Gsta2, Gsta3, Mgst1, and Cdkn1b (p27), and decreased expression of the antioxidant Mt1, and DNA methylation Dnmt1, Dnmt3a, and Ctcf were confirmed in the liver of female rats in a dose-dependent manner. Methylation status of the promoter region of the Mt1 was not evidently changed between control and treatment groups. The results suggested that CCA decreased GSH and altered the expression of several genes, including antioxidants, GST, and DNA methylation, followed by impaired cell proliferation in the liver of female rats.

Development and application of an evidence-based directed acyclic graph to evaluate the associations between metal mixtures and cardiometabolic outcomes

Objectives

Specifying causal models to assess relationships among metal mixtures and cardiometabolic outcomes requires evidence-based models of the causal structures; however, such models have not been previously published. The objective of this study was to develop and evaluate a directed acyclic graph (DAG) diagraming metal mixture exposure and cardiometabolic outcomes.

Methods

We conducted a literature search to develop the DAG of metal mixtures and cardiometabolic outcomes. To evaluate consistency of the DAG, we tested the suggested conditional independence statements using linear and logistic regression analyses with data from the San Luis Valley Diabetes Study (SLVDS; n=1795). We calculated the proportion of statements supported by the data and compared this to the proportion of conditional independence statements supported by 1,000 DAGs with the same structure but randomly permuted nodes. Next, we used our DAG to identify minimally sufficient adjustment sets needed to estimate the association between metal mixtures and cardiometabolic outcomes (i.e., cardiovascular disease, fasting glucose, and systolic blood pressure). We applied them to the SLVDS using Bayesian kernel machine regression, linear mixed effects, and Cox proportional hazards models.

Results

From the 42 articles included in the review, we developed an evidence-based DAG with 74 testable conditional independence statements (43 % supported by SLVDS data). We observed evidence for an association between As and Mn and fasting glucose.

Conclusions

We developed, tested, and applied an evidence-based approach to analyze associations between metal mixtures and cardiometabolic health.

Influence of differential arsenic exposure on cellular redox homeostasis of exposed rural women of West Bengal

The metalloid arsenic (As) induces oxidative stress is a well-known fact. However, the extent of variation of oxidative stress according to different exposure levels of As in groundwater and the mechanism responsible for As mediated oxidative stress is yet to be elucidated in a human population of West Bengal. In the present study, we have investigated the impact of low level (> 10 ≤ 50 µg/L) and high-level groundwater As (> 50 µg/L) on cellular redox status, DNA damage, and repair mechanisms in chronically exposed rural women of West Bengal. Prediction models of ordinary least square regression of nail As, forced vital capacity (FVC) %, and that of forced expiratory volume during the first one second (FEV1) % deciphered that accumulation of As in nails may predict hemoglobin deficiency. Moreover, consumption of As-laced water tends to decrease FEV1% and FVC%. A strong positive correlation was observed between water and nail As level and reactive oxygen species (ROS) generation. ROS, perturbed nuclear factor erythroid 2-related factor 2(Nrf2)/ Kelch-like ECH-associated protein 1 (Keap1) redox regulation, compromised antioxidant defense machinery-superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione transferase (GST), induced DNA damage, and suppressed DNA repair proteins-poly ADP ribose polymerase1(PARP1)/ X-ray repair cross-complementing protein 1(XRCC1)/ 8-oxoguanine glycosylase (OGG1) in a dose-dependent manner. All the low and high As areas had very high cancer risk values for the exposed population. It has been predicted that if the As level in the drinking water of a 40-year adult increases by 2 ug/L, the likelihood of the cancer risk will increase by 10%, keeping the body weight and amount of water intake constant. Thus, long-term exposure to either low or high As is seriously affecting the lives of asymptomatic women who are vulnerable to developing carcinogenic changes after a period of latency.

Mechanisms of Arsenic Exposure-Induced Hypertension and Atherosclerosis: an Updated Overview

Arsenic is an abundant element in the earth's crust. In the environment and within the human body, this toxic element can be found in both organic and inorganic forms. Chronic exposure to arsenic can predispose humans to cardiovascular diseases including hypertension, stroke, atherosclerosis, and blackfoot disease. Oxidative damage induced by reactive oxygen species is a major player in arsenic-induced toxicity, and it can affect genes expression, inflammatory responses, and/or nitric oxide homeostasis. Exposure to arsenic in drinking water can lead to vascular endothelial dysfunction which is reflected by an imbalance between vascular relaxation and contraction. Arsenic has been shown to inactivate endothelial nitric oxide synthase leading to a reduction of the generation and bioavailability of nitric oxide. Ultimately, these effects increase the risk of vascular diseases such as hypertension and atherosclerosis. The present article reviews how arsenic exposure contributes to hypertension and atherosclerosis development.

Breast Cancer and Arsenic Anticancer Effects: Systematic Review of the Experimental Data from In Vitro Studies

Arsenic is a known environmental carcinogenic agent. However, under certain circumstances, it may exert anticancer effects. In this systematic review, we aim to provide information on recent developments in studies on arsenic antitumor effects in breast cancer. Research included in the review refers to experimental data from in vitro studies. The data was collected using search terms "breast cancer," "arsenic," and "anticancer" (25.05.2021). Only studies in English and published in the last 10 years were included. The search identified 123 studies from the EBSCOhost, PubMed, and Scopus databases. In the selection process, thirty full-texts were evaluated as eligible for the review. The literature of the last decade provides a lot of information on mechanisms behind anticancer effects of arsenic on breast cancer. Similar to arsenic-induced carcinogenesis, these mechanisms include the activation of the redox system and the increased production of free radicals. Targets of arsenic action are systems of cell membranes, mitochondria, pathways of intracellular transmission, and the genetic apparatus of the cell. Beneficial effects of arsenic use are possible due to significant metabolic differences between cancer and healthy cells. Further efforts are needed in order to establish modes and doses of treatment with arsenic that would provide anticancer activity with minimal toxicity.