Arsenic cardiotoxicity: An overview

Roles of serum uric acid on the association between arsenic exposure and incident metabolic syndrome in an older Chinese population

Growing evidences showed that heavy metals exposure may be associated with metabolic diseases. Nevertheless, the mechanism underlying arsenic (As) exposure and metabolic syndrome (MetS) risk has not been fully elucidated. So we aimed to prospectively investigate the role of serum uric acid (SUA) on the association between blood As exposure and incident MetS. A sample of 1045 older participants in a community in China was analyzed. We determined As at baseline and SUA concentration at follow-up in the Yiwu Elderly Cohort. MetS events were defined according to the criteria of the International Diabetes Federation (IDF). Generalized linear model with log-binominal regression model was applied to estimate the association of As with incident MetS. To investigate the role of SUA in the association between As and MetS, a mediation analysis was conducted. In the fully adjusted log-binominal model, per interquartile range increment of As, the risk of MetS increased 1.25-fold. Compared with the lowest quartile of As, the adjusted relative risk (RR) of MetS in the highest quartile was 1.42 (95% confidence interval, CI: 1.03, 2.00). Additionally, blood As was positively associated with SUA, while SUA had significant association with MetS risk. Further mediation analysis demonstrated that the association of As and MetS risk was mediated by SUA, with the proportion of 15.7%. Our study found higher As was remarkably associated with the elevated risk of MetS in the Chinese older adults population. Mediation analysis indicated that SUA might be a mediator in the association between As exposure and MetS.

Arsenic induced cardiotoxicity: An approach for molecular markers, epigenetic predictors and targets

Arsenic, a ubiquitous environmental toxicant, has been acknowledged as a significant issue for public health due to its widespread pollution of drinking water and food supplies. The present review aimed to study the toxicity associated with the cardiac system. Prolonged exposure to arsenic has been associated with several harmful health outcomes, especially cardiotoxicity. Arsenic-induced cardiotoxicity encompasses a range of cardiovascular abnormalities, including cardiac arrhythmias, ischemic heart disease, and cardiomyopathy. To tackle this toxicity, understanding the molecular markers, epigenetic predictors, and targets involved in arsenic-induced cardiotoxicity is essential for creating preventative and therapeutic approaches. For preventive measures against this heavy metal poisoning of groundwater, it is crucial to regularly monitor water quality, re-evaluate scientific findings, and educate the public about the possible risks. This review thoroughly summarised what is currently known in this field, highlighting the key molecular markers, epigenetic modifications, and potential therapeutic targets associated with arsenic-induced cardiotoxicity.

Ionic and nano calcium to reduce cadmium and arsenic toxicity in plants: Review of mechanisms and potentials

Contamination of agricultural soils with heavy metal(loid)s like arsenic (As) and cadmium (Cd) is an ever increasing concern for crop production, quality, and global food security. Numerous in-situ and ex-situ remediation approaches have been developed to reduce As and Cd contamination in soils. However, field-scale applications of conventional remediation techniques are limited due to the associated environmental risks, low efficacy, and large capital investments. Recently, calcium (Ca) and Ca-based nano-formulations have emerged as promising solutions with the large potential to mitigate As and Cd toxicity in soil for plants. This review provides comprehensive insights into the phytotoxic effects of As and Cd stress/toxicity and discusses the applications of Ca-based ionic and nano-agrochemicals to alleviate As and Cd toxicity in important crops such as rice, wheat, maize, and barley. Further, various molecular and physiological mechanisms induced by ionic and nano Ca to mitigate As and Cd stress/toxicity in plants are discussed. This review also critically analyzes the efficiency of these emerging Ca-based approaches, both ionic and nano-formulations, in mitigating As and Cd toxicity in comparison to conventional remediation techniques. Additionally, future perspectives and ecological concerns of the remediation approaches encompassing ionic and nano Ca have been discussed. Overall, the review provides an updated and in-depth knowledge for developing sustainable and effective strategies to address the challenges posed by As and Cd contamination in agricultural crops.

Metal-contaminated sediment toxicity in a highly impacted Neotropical river: Insights from zebrafish embryo toxicity assays

The Fundão dam collapse was one of the largest mining-related disasters globally. It resulted in the release of mining tailings containing heavy metals, which contaminated the Doce River in southeastern Brazil. This study assessed the effects of acute exposure of Danio rerio embryos to sediments contaminated by mine tailings six years after the Fundão dam collapse. The study sites included P2, P3, and P4 in the upper Doce River, as well as site P1 on the Piranga River, an uncontaminated river. Sediment samples were analyzed for 10 metals/metalloid by atomic absorption spectrometry. In the assays, embryos were exposed to sediment from P1-P4 sites, and uncontaminated quartz was used as control sediment. Various biomarkers were applied to assess biological responses, and the integrated biomarker response (IBR) index was calculated for each site. Sediment samples revealed elevated levels of As, Cr, Cu, Hg, and Ni beyond Brazilian legislation limits. At 96-h exposure, embryo mortality rates exceeded 20% in P1, P2, and P3, higher than the control and P4 (p < 0.0001). Hatching rates ranged from 60 to 80% in P1, P2, and P3, lower than the control and P4 (p < 0.001). Larvae exposed to P2 sediment (closest to the Fundão dam) exhibited skeletal, physiological, and sensory malformations. Neurotoxicity was indicated by increased acetylcholinesterase activity and reduced spontaneous movements in embryos exposed to Doce River sediment. Contamination also increased metallothionein and heat shock protein 70 levels, along with changes in cell proliferation and apoptosis. Principal component analysis showed a good correlation between metals/metalloid in the sediment and larval morphometric endpoints. The IBR index highlighted suitable biomarkers for monitoring metal contamination in fish embryos. Overall, our findings suggest that sediment toxicity following the Fundão dam failure may compromise the sustainability of fish communities in the Doce River.

Betaine Protects Mice from Cardiotoxicity Triggered by Sodium Arsenite Through Antioxidative and Anti-inflammatory Pathways

NaAsO2 is known as a harmful pollutant all over the world, and many chronic heart diseases can be attributed to its prolonged exposure in NaAsO2-contaminated water. Therefore, considering the anti-inflammatory and antioxidant effects of betaine (BET), in this study, our team investigated the cardioprotective effects of this phytochemical agent on sodium arsenite (NaAsO2)-induced cardiotoxicity. Forty male mice were randomly divided into 4 groups: (I) Control; (II) BET (500 mg/kg); (III) NaAsO2 (50 ppm); and (IV) NaAsO2 + BET. NaAsO2 was given to the animals for 8 weeks, but BET was given in the last two weeks. After decapitation, inflammatory factors and biochemical parameters were measured, and Western blot analyses were performed. BET decrease the activity level of alanine aspartate aminotransferase, creatine kinase MB, thiobarbituric acid reactive substances level, inflammatory factors (tumor necrosis factor-α) content, and nuclear factor kappa B expression. Furthermore, BET increased cardiac total thiol and activity levels of catalase, superoxide dismutase, and glutathione peroxidase and nuclear factor erythroid-2 expression. Hence, the administration of BET ameliorated the deleterious effects stemming from the imbalance of oxidative and antioxidant pathways and histopathological alterations observed in NaAsO2-intoxicated mice, thereby attenuating oxidative stress-induced damage and inflammation.

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.

The Impact of Environmental Toxins on Cardiovascular Diseases

Environmental toxins pose significant risks to human health and are considered major contributors to chronic diseases, particularly cardiovascular diseases (CVDs). Numerous studies have highlighted the detrimental impact of environmental toxicity on cardiovascular health. The primary sources of environmental toxins include pollutants containing particulate matter and organic substances, such as sulfate, nitrates, ammonium, elemental carbon, crystal elements, arsenic (As), mercury (Hg), cadmium (Cd), and Bisphenol A (BPA). Epidemiological research has closely monitored the link between environmental toxins and CVDs. Notably, aerosols and particulate matter, including PM10 and PM2.5, prevalent in ambient air pollution, have been implicated in various CVDs like ischemic heart disease, myocardial infarction, and dysrhythmia. Additionally, heavy metals such as lead and pesticides from environmental toxins are known to contribute to CVDs, even at low levels of exposure over extended periods. Mercury exposure, even at low concentrations, can adversely affect multiple organs, including the heart, kidneys, nervous system, and immune system. With Pb2+ ions exhibiting Ca2+-like properties, lead disrupts various pathways and can lead to cardiac and vascular lesions and functional impairments when blood lead concentrations exceed 100 µg% in adults and 60 µg% in children. Furthermore, cadmium exposure is higher in smokers, primarily due to tobacco use, and is associated with peripheral artery disease. Arsenic toxicity is well-documented, particularly its cardiotoxic effects, which can result in fatal and irreversible myocardial damage. Bisphenol A (BPA) has also been found in urine samples, underscoring its presence as an environmental toxin impacting human health.

Subchronic pulmonary toxicity of ambient particles containing cement production-related elements

Chronic respiratory disease is among the most common non-communicable diseases, and particulate materials (PM) are a major risk factor. Meanwhile, evidence of the relationship between the physicochemical characteristics of PM and pulmonary toxicity mechanism is still limited. Here, we collected particles (CPM) from the air of a port city adjacent to a cement factory, and we found that the CPM contained various elements, including heavy metals (such as arsenic, thallium, barium, and zirconium) which are predicted to have originated from a cement plant adjacent to the sampling site. We also delivered the CPM intratracheally to mice for 13 weeks to investigate the pulmonary toxicity of inhaled CPM. CPM-induced chronic inflammatory lesions with an increased total number of cells in the lung of mice. Meanwhile, among inflammatory mediators measured in this study, levels of IL-1β, TNF-α, CXCL-1, and IFN-γ were elevated in the treated group compared with the controls. Considering that the alveolar macrophage (known as dust cell) is a professional phagocyte that is responsible for the clearance of PM from the respiratory surfaces, we also investigated cellular responses following exposure to CPM in MH-S cells, a mouse alveolar macrophage cell line. CPM inhibited cell proliferation and formed autophagosome-like vacuoles. Intracellular calcium accumulation and oxidative stress, and altered expression of pyrimidine metabolism- and olfactory transduction-related genes were observed in CPM-treated cells. More interestingly, type I-LC3B and full-length PARP proteins were not replenished in CPM-treated cells, and cell cycle changes, apoptotic and necrotic cell death, and caspase-3 cleavage were not significantly detected in cells exposed to CPM. Taken together, we conclude that dysfunction of alveolar macrophages may contribute to CPM-induced pulmonary inflammation. In addition, given the possible transformation of heart tissue observed in CPM-treated mice, we suggest that further study is needed to clarify the systemic pathological changes and the molecular mechanisms following chronic exposure to CPM.

Low-intensity ultrasound combined with arsenic trioxide induced apoptosis of glioma via EGFR/AKT/mTOR

AIMS

This study aimed to explore whether low-intensity ultrasound (LIUS) combined with low-concentration arsenic trioxide (ATO) could inhibit the proliferation of glioma and, if so, to clarify the potential mechanism.

MAIN METHODS

The effects of ATO and LIUS alone or in combination on glioma were examined by CCK8, EdU, and flow cytometry assays. Western blot analysis was used to detect changes in expression of apoptosis-related proteins and their effects on the EGFR/AKT/mTOR pathway. The effects of ATO and LIUS were verified in vivo in orthotopic xenograft models, and tumor size, arsenic content in brain tissue, survival, and immunohistochemical changes were observed.

KEY FINDINGS

LIUS enhanced the inhibitory effect of ATO on the proliferation of glioma, and EGF reversed the proliferation inhibition and protein changes induced by ATO and LIUS. The anti-glioma effect of ATO combined with LIUS was related to downstream AKT/mTOR pathway changes caused by inhibition of EGFR activation, which enhanced apoptosis of U87MG and U373 cells. In vivo experiments showed significant increases in arsenic content in brain tissue, as well as decreased tumor sizes and longer survival times in the combined treatment group compared with other groups. The trends of immunohistochemical protein changes were consistent with the in vitro results.

SIGNIFICANCE

This study showed that LIUS enables ATO to exert anti-glioma effects at a safe dose by inhibiting the activation of EGFR and the downstream AKT/mTOR pathway to regulate apoptosis. LIUS in combination with ATO is a promising novel method for treating glioma and could improve patient prognosis.

Arsenic disrupts extracellular vesicle-mediated signaling in regenerating myofibers

Chronic exposure to environmental arsenic is a public health crisis affecting hundreds of millions of individuals worldwide. Though arsenic is known to contribute to many pathologies and diseases, including cancers, cardiovascular and pulmonary diseases, and neurological impairment, the mechanisms for arsenic-promoted disease remain unresolved. This is especially true for arsenic impacts on skeletal muscle function and metabolism, despite the crucial role that skeletal muscle health plays in maintaining cardiovascular health, systemic homeostasis, and cognition. A barrier to researching this area is the challenge of interrogating muscle cell-specific effects in biologically relevant models. Ex vivo studies investigating mechanisms for muscle-specific responses to arsenic or other environmental contaminants primarily utilize traditional 2-dimensional culture models that cannot elucidate effects on muscle physiology or function. Therefore, we developed a contractile 3-dimensional muscle construct model-composed of primary mouse muscle progenitor cells differentiated in a hydrogel matrix-to study arsenic exposure impacts on skeletal muscle regeneration. Muscle constructs exposed to low-dose (50 nM) arsenic exhibited reduced strength and myofiber diameter following recovery from muscle injury. These effects were attributable to dysfunctional paracrine signaling mediated by extracellular vesicles (EVs) released from muscle cells. Specifically, we found that EVs collected from arsenic-exposed muscle constructs recapitulated the inhibitory effects of direct arsenic exposure on myofiber regeneration. In addition, muscle constructs treated with EVs isolated from muscles of arsenic-exposed mice displayed significantly decreased strength. Our findings highlight a novel model for muscle toxicity research and uncover a mechanism of arsenic-induced muscle dysfunction by the disruption of EV-mediated intercellular communication.

Particulate matter induces arrhythmia-like cardiotoxicity in zebrafish embryos by altering the expression levels of cardiac development- and ion channel-related genes

Air pollution is a risk factor that increases cardiovascular morbidity and mortality. In this study, we investigated the cardiotoxicity of particulate matter (PM) exposure using a zebrafish embryo model. We found that PM exposure induced cardiotoxicity, such as arrhythmia, during cardiac development. PM exposure caused cardiotoxicity by altering the expression levels of cardiac development (T-box transcription factor 20, natriuretic peptide A, and GATA-binding protein 4)- and ion-channel (scn5lab, kcnq1, kcnh2a/b, and kcnh6a/b)-related genes. In conclusion, this study showed that PM induces the aberrant expression of cardiac development- and ion channel-related genes, leading to arrhythmia-like cardiotoxicity in zebrafish embryos. Our study provides a foundation for further research on the molecular and genetic mechanisms of cardiotoxicity induced by PM exposure.

Racial Disparity in Anthracycline-induced Cardiotoxicity in Breast Cancer Patients

Breast cancer has become the most common cancer in the US and worldwide. While advances in early detection and treatment have resulted in a 40% reduction in breast cancer mortality, this reduction has not been achieved uniformly among racial groups. A large percentage of non-metastatic breast cancer mortality is related to the cardiovascular effects of breast cancer therapies. These effects appear to be more prevalent among patients from historically marginalized racial/ethnic backgrounds, such as African American and Hispanic individuals. Anthracyclines, particularly doxorubicin and daunorubicin, are the first-line treatments for breast cancer patients. However, their use is limited by their dose-dependent and cumulative cardiotoxicity, manifested by cardiomyopathy, ischemic heart disease, arrhythmias, hypertension, thromboembolic disorders, and heart failure. Cardiotoxicity risk factors, such as genetic predisposition and preexisting obesity, diabetes, hypertension, and heart diseases, are more prevalent in racial/ethnic minorities and undoubtedly contribute to the risk. Yet, beyond these risk factors, racial/ethnic minorities also face unique challenges that contribute to disparities in the emerging field of cardio-oncology, including socioeconomic factors, food insecurity, and the inability to access healthcare providers, among others. The current review will address genetic, clinical, and social determinants that potentially contribute to this disparity.

Living Anisotropic Structural Color Hydrogels for Cardiotoxicity Screening

Environmental toxins can result in serious and fatal damage in the human heart, while the development of a viable stratagem for assessing the effects of environmental toxins on human cardiac tissue is still a challenge. Herein, we present a heart-on-a-chip based on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) cultured living anisotropic structural color hydrogels for cardiotoxicity screening. Such anisotropic structural color hydrogels with a conductive parallel carbon nanotube (CNT) upper layer, gelatin methacryloyl (GelMA) interlayer, and inverse opal bottom layer were fabricated by a sandwich replicating approach. The inverse opal structure endowed the anisotropic hydrogels with stable structural color property, while the parallel and conductive CNTs could induce the hiPSC-CMs to grow in a directional manner with consistent autonomous beating. Notably, the resultant hiPSC-CM-cultured hydrogel exhibited synchronous shifts in structural color, responding to contraction and relaxation of hiPSC-CMs, offering a visual platform for monitoring cell activity. Given these features, the hiPSC-CM-cultured living anisotropic structural color hydrogels were integrated into a heart-on-a-chip, which provided a superior cardiotoxicity screening platform for environmental toxins.

Cardiotoxicity in children with cancer treated with anthracyclines: A position statement on dexrazoxane

Cardiovascular disease is the leading cause of non-malignant morbidity and mortality in childhood cancer survivors (CCSs). Anthracyclines are included in many treatment regimens for paediatric cancer, but unfortunately, these compounds are cardiotoxic. One in 10 CCSs who has received an anthracycline will develop a symptomatic cardiac event over time. Given the crucial need to mitigate anthracycline-related cardiotoxicity (ARC), the authors critically examined published data to identify effective cardioprotective strategies. Based on their expert analysis of contemporary literature data, it was concluded that consideration should be given for routine use of dexrazoxane in children with cancer who are at risk of ARC.

Exposure to Arsenic and Subclinical Cardiovascular Disease in 9- to 11-Year-Old Children, Syracuse, New York

Importance

Studies in adults have demonstrated associations between arsenic exposure and clinical and subclinical cardiovascular disease (CVD). No studies to date have considered potential associations in children.

Objective

To examine the association between total urinary arsenic levels in children and subclinical indicators of CVD.

Design, Setting, and Participants

This cross-sectional study considered 245 children, a subset from the Environmental Exposures and Child Health Outcomes (EECHO) cohort. Children from the Syracuse, New York, metropolitan area were recruited from August 1, 2013, until November 30, 2017, with enrollment throughout the year. Statistical analysis was performed from January 1, 2022, to February 28, 2023.

Exposures

Total urinary arsenic was measured using inductively coupled plasma mass spectrometry. Creatinine concentration was used to adjust for urinary dilution. In addition, potential exposure routes (eg, diet) were measured.

Main Outcomes and Measures

Three indicators of subclinical CVD were assessed: carotid-femoral pulse wave velocity, carotid intima media thickness, and echocardiographic measures of cardiac remodeling.

Results

The study sample included 245 children aged 9 to 11 years (mean [SD] age, 10.52 [0.93] years; 133 [54.3%] female). The geometric mean of the creatinine-adjusted total arsenic level in the population was 7.76 μg/g creatinine. After adjustment for covariates, elevated total arsenic levels were associated with significantly greater carotid intima media thickness (β = 0.21; 95% CI, 0.08-0.33; P = .001). In addition, echocardiography revealed that elevated total arsenic was significantly higher for children with concentric hypertrophy (indicated by greater left ventricular mass and greater relative wall thickness; geometric mean, 16.77 μg/g creatinine; 95% CI, 9.87-28.79 μg/g) relative to the reference group (geometric mean, 7.39 μg/g creatinine; 95% CI, 6.36-8.58 μg/g). With respect to exposure source, significant geographic clustering of total arsenic was found in 1 urban area of Syracuse, New York.

Conclusions and Relevance

These findings suggest a significant association between arsenic exposure and subclinical CVD in children. Elevated total arsenic levels were found in an area of Syracuse with known elevations of toxic metals from industrial waste, suggesting historical pollution as a possible source. Given the novelty and potential importance of this association, further research is needed to confirm our findings. Any potential effect of urinary arsenic exposure in childhood on actual clinical CVD outcomes in adulthood remains to be determined.

Long-term exposure to arsenic in drinking water leads to myocardial damage by oxidative stress and reduction in NO

Chronic arsenic exposure causes myocardial damage. The aim of this study is to investigate if oxidative stress and reduction in NO is involved in the myocardial damage induced by arsenic in drinking water. Rats were divided into a control group and different doses of sodium arsenite. With increasing sodium arsenite concentrations in drinking water, localised inflammatory foci and necrotic myocardial tissues were gradually observed. Compared to the control group, the activities and gene expression of antioxidant enzymes in arsenic-exposed rats decreased. NO content and the NOS activity as well as the expression of NOS mRNA in the myocardial tissue of exposed rats, decreased, and the extracellular NO content of cardiomyocytes treated with sodium arsenite also decreased. The rate of cell apoptosis induced by sodium arsenite decreased after treatment with sodium nitroprusside (an NO donor). In conclusion, arsenic exposure in drinking water can lead to myocardial injury and cardiomyocyte apoptosis through oxidative stress and a reduction in NO content.

Tocotrienols-enriched Self-nanoemulsifying Drug Delivery System Enhances the Antileukemic Activity of All-trans Retinoic Acid but not Electrocardiogram Alterations Evoked by Its Combination with Arsenic Trioxide

All-trans retinoic acid and arsenic trioxide are the leading choices for the treatment of acute promyelocytic leukemia. Notwithstanding the impressive differentiative properties of all-trans retinoic acid and the apoptotic properties of arsenic trioxide, some problems still occur in acute promyelocytic leukemia treatment. These problems are due to patients' relapses, mainly related to changes in the ligand-binding domain of RARα (retinoic acid receptor α) and the cardiotoxic effects caused by arsenic trioxide. We previously developed a self-nanoemulsifying drug delivery system enriched with tocotrienols to deliver all-trans retinoic acid (SNEDDS-TRF-ATRA). Herein, we have evaluated if tocotrienols can help revert ATRA resistance in an APL cell line (NB4-R2 compared to sensitive NB4 cells) and mitigate the cardiotoxic effects of arsenic trioxide in a murine model. SNEDDS-TRF-ATRA enhanced all-trans retinoic acid cytotoxicity in NB4-R2 (resistant) cells but not in NB4 (sensitive) cells. Moreover, SNEDDS-TRF-ATRA did not significantly change the differentiative properties of all-trans retinoic acid in both NB4 and NB4-R2 cells. Combined administration of SNEDDS-TRF-ATRA and arsenic trioxide could revert QTc interval prolongation caused by ATO but evoked other electrocardiogram alterations in mice, such as T wave flattening. Therefore, SNEDDS-TRF-ATRA may enhance the antileukemic properties of all-trans retinoic acid but may influence ECG changes caused by arsenic trioxide administration. SNEDDS-TRF-ATRA presents cytotoxicity in resistant APL cells (NB4-R2). Combined administration of ATO and SNEDDS-TRF-ATRA in mice prevented the prolongation of the QTc interval caused by ATO but evoked ECG abnormalities such as T wave flattening.

Melatonin ameliorates arsenic-induced cardiotoxicity through the regulation of the Sirt1/Nrf2 pathway in rats

Chronic arsenic (As) exposure, mainly as a result of drinking contaminated water, is associated with cardiovascular diseases. Mitochondrial dysfunction, oxidative stress, inflammation, apoptosis, and autophagy have been suggested as the molecular etiology of As cardiotoxicity. Melatonin (Mel) is a powerful antioxidant. Mel improves diabetic cardiomyopathy, cardiac remodeling, and heart failure. Following pre-treatment with Mel (10, 20, or 30 mg/kg/day i.p.), rats were orally gavaged with As (15 mg/kg/day) for 28 days. Electrocardiographic findings showed that Mel decreased the As-mediated QT interval prolongation. The effects of As on cardiac levels of glutathione (GSH) and malondialdehyde (MDA) were reversed by Mel pretreatment. Mel also modulated the Sirt1 and Nrf2 expressions promoted by As. Mel down-regulated autophagy markers such as Beclin-1 expression and the LC3-II/I ratio. Moreover, the cardiac expression of cleaved-caspase-3 and Bax/Bcl-2 ratio was decreased by Mel pretreatment. Reduced expression of miR-34a and miR-144 by As were reversed by Mel. The histopathological changes of cardiac injury associated with As exposure was moderated by Mel. Mel may improve As-induced cardiac dysfunction through anti-oxidative, anti-apoptotic, and anti-autophagic mechanisms.

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.

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.

Arsenic exposure promotes the emergence of cardiovascular diseases

A large number of studies conducted in the past decade 2010-2020 refer to the impact of arsenic (As) exposure on cardiovascular risk factors. The arsenic effect on humans is complex and mainly depends on the varying individual susceptibilities, its numerous toxic expressions and the variation in arsenic metabolism between individuals. In this review we present relevant data from studies which document the association of arsenic exposure with various biomarkers, the effect of several genome polymorphisms on arsenic methylation and the underling molecular mechanisms influencing the cardiovascular pathology. The corresponding results provide strong evidence that high and moderate-high As intake induce oxidative stress, inflammation and vessel endothelial dysfunction that are associated with increased risk for cardiovascular diseases (CVDs) and in particular hypertension, myocardial infarction, carotid intima-media thickness and stroke, ventricular arrhythmias and peripheral arterial disease. In addition, As exposure during pregnancy implies risks for blood pressure abnormalities among infants and increased mortality rates from acute myocardial infarction during early adulthood. Low water As concentrations are associated with increased systolic, diastolic and pulse pressure, coronary heart disease and incident stroke. For very low As concentrations the relevant studies are few. They predict a risk for myocardial infarction, stroke and ischemic stroke and incident CVD, but they are not in agreement regarding the risk magnitude.

Poison With a Purpose: A Case Report on Arsenic Cardiotoxicity and Obesity

Acute promyelocytic leukemia (APL) is a form of leukemia in which there is an arrest of the maturation of the myeloid lineage at the promyelocyte stage. Although there is high early mortality due to coagulopathy, APL is now a curable disease with the use of arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA). Arsenic is weight-based for the treatment of APL, and many toxicities are dose-dependent, although there are no guidelines regarding dosing adjustments for obese patients. We present a case of a 34-year-old male with obesity and APL who developed arsenic-induced QTc prolongation and symptomatic sinus tachycardia while receiving treatment. Further research is needed to guide appropriate dosing for obese patients to determine if ideal body weight dosing is able to provide similar cure rates with fewer adverse events.

Selenium Supplementation Protects Against Arsenic-Trioxide-Induced Cardiotoxicity Via Reducing Oxidative Stress and Inflammation Through Increasing NAD+ Pool

Arsenic is an environmental contaminant, and accumulating evidence has indicated that exposure to arsenic can cause various diseases, especially cardiotoxicity. Selenium (Se) exerts a vital role in the regulation of multiple physiological activities. Recently, several studies highlighted that Se treatment can effectively antagonize the toxic effects induced by arsenic. However, the exact underlying effect and mechanism of Se on Arsenic-induced cardiotoxicity has not been explored. In the current study, the arsenic trioxide (ATO)-triggered heart damage mice model was used to explore whether Se exerts protective roles in ATO-related cardiotoxicity and its potential mechanism. Our data showed that Se treatment significantly alleviated ATO-mediated cardiotoxicity evidenced by increased weight, decreased myocardial damage markers, and improved heart functions in mice. Furthermore, we demonstrated that Se remarkably inhibited ATO-mediated oxidative stress and inflammatory responses in heart tissues. Mechanistically, we showed that Se upregulated the levels of NAD⁺ in cardiomyocytes of the mice challenged by ATO, and this effect involved in the activation of the NAD⁺ biosynthesis through the salvage pathway. Collectively, our findings demonstrated that Se protected against ATO-mediated cardiotoxicity by antioxidant and anti-inflammatory effects via increasing the NAD⁺ pool in mice.

Misuse of Cardiac Lipid upon Exposure to Toxic Trace Elements-A Focused Review

Heavy metals and metalloids like cadmium, arsenic, mercury, and lead are frequently found in the soil, water, food, and atmosphere; trace amounts can cause serious health issues to the human organism. These toxic trace elements (TTE) affect almost all the organs, mainly the heart, kidney, liver, lungs, and the nervous system, through increased free radical formation, DNA damage, lipid peroxidation, and protein sulfhydryl depletion. This work aims to advance our understanding of the mechanisms behind lipid accumulation via increased free fatty acid levels in circulation due to TTEs. The increased lipid level in the myocardium worsens the heart function. This dysregulation of the lipid metabolism leads to damage in the structure of the myocardium, inclusive fibrosis in cardiac tissue, myocyte apoptosis, and decreased contractility due to mitochondrial dysfunction. Additionally, it is discussed herein how exposure to cadmium decreases the heart rate, contractile tension, the conductivity of the atrioventricular node, and coronary flow rate. Arsenic may induce atherosclerosis by increasing platelet aggregation and reducing fibrinolysis, as exposure interferes with apolipoprotein (Apo) levels, resulting in the rise of the Apo-B/Apo-A1 ratio and an elevated risk of acute cardiovascular events. Concerning mercury and lead, these toxicants can cause hypertension, myocardial infarction, and carotid atherosclerosis, in association with the generation of free radicals and oxidative stress. This review offers a complete overview of the critical factors and biomarkers of lipid and TTE-induced cardiotoxicity useful for developing future protective interventions.

Role of N6-methyladenosine RNA modification in the imbalanced inflammatory homeostasis of arsenic-induced skin lesions

This study aimed to investigate the effect of N6-methyladenosine (m⁶ A) modification in modulating inflammatory homeostasis of arsenic (As)-induced skin lesions. Our bioinformatic analysis revealed abnormal expression of m⁶ A RNA methylation regulators and cytokines in the arsenic-exposed population. In human keratinocytes, arsenite increased the levels of m⁶ A methylation by upregulating the RNA methyltransferase like 3 (METTL3), mediating the disordered secretion of indicators that reflect inflammatory homeostasis (IL-6, IL-17, and IL-10). The indicators reflecting arsenic-induced skin lesions (Krt1 and Krt10) were also significantly elevated, which contributed to the occurrence of skin lesions. Our results also confirmed the association between METTL3 with inflammatory homeostasis and arsenic-induced skin lesions using arsenic-exposed human skin samples. In the arsenic-exposed group, the upregulation of METTL3 exacerbated the increase in cytokine levels (IL-6, IL-17, and IL-10), which was associated with the upregulation of keratins (Krt1 and Krt10). In addition, significant correlations among these factors corroborate the theoretical links. Finally, alteration of the m⁶ A levels via knockdown or enhancement of the METTL3 protein could antagonize or aggravate arsenite-induced imbalanced inflammatory homeostasis and human keratinocyte damage in HaCaT cells. Collectively, our study reveals some evidence that regulation of m⁶ A modification plays an important role in arsenic-induced skin lesions, which provide a new perspective on the mechanism of arsenite-induced imbalanced inflammatory homeostasis in the field of RNA epigenetics.

Sacubitril/valsartan protects against arsenic trioxide induced cardiotoxicity in vivo and in vitro

The cardiotoxicity induced by arsenic trioxide (ATO) limits its clinical application in acute promyelocytic leukemia treatment. Sacubitril/valsartan (LCZ696) is an effective drug for the treatment of heart failure. In this study, we aimed to investigate the protective effect and mechanisms of LCZ696 against the ATO-induced cardiotoxicity in mice and H9c2 cells. We found that LCZ696 could alleviate the decrease of ejection fraction and fractional shortening induced by ATO, thereby improving mouse cardiac contractile function. LCZ696 could also reduce the myocardial enzyme, resist oxidative stress, mitigate myocardial fibrosis, and ameliorate myocardial structure, thereby alleviating myocardial damage caused by ATO. In addition, LCZ696 could significantly increase the cell viability and reduce the accumulation of reactive oxygen species in ATO-treated H9c2 cells. Besides, in vivo and in vitro studies have been found that LCZ696 could restore the expression of Bcl-2 and reduce Bax and Caspase-3 levels, inhibiting ATO-induced apoptosis. Meanwhile, LCZ696 decreased the levels of IL-1, IL-6, and TNF-α, alleviating the inflammatory injury caused by ATO. Furthermore, LCZ696 prevented NF-κB upregulation induced by ATO. Our findings revealed that LCZ696 has a considerable effect on preventing cardiotoxicity induced by ATO, which attributes to its capability to suppress oxidative stress, inflammation, and apoptosis.

Exploring the role of senescence inducers and senotherapeutics as targets for anticancer natural products

During the last few decades, cancer has remained one of the deadliest diseases that endanger human health, emphasizing urgent drug discovery. Cellular senescence has gained a great deal of attention in recent years because of its link to the development of cancer therapy. Senescent cells are incapable of proliferating due to irreversibly inhibited the initiation of the cell cycle pathways. However, senescent cells aggregate in tissues and produce a pro-inflammatory secretome called senescence-associated secretory phenotype (SASP) that can cause serious harmful effects if not managed properly. There is mounting evidence that senescent cells lead to various phases of tumorigenesis in various anatomical sites, owing mostly to the paracrine activities of the SASP. Therefore, a new treatment field called senotherapeutics has been established. Senotherapeutics are newly developed anticancer agents that have been demonstrated to inhibit cancer effectively. In light of recent findings, several promising natural products have been identified as senescence inducers and senotherapeutics, including, miliusanes, epigallocatechin gallate, phloretin, silybin, resveratrol, genistein, sulforaphane, quercetin, allicin, fisetin, piperlongumine, berberine, triptolide, tocotrienols and curcumin analogs. Several of them have already been validated through preclinical trials and exert an enormous potential for clinical trials. This review article focuses on and summarises the latest advances on cellular senescence and its potential as a target for cancer treatment and highlights the well-known natural products as senotherapeutics for cancer treatment.

Purification and characterization of Se-enriched Grifola frondosa glycoprotein, and evaluating its amelioration effect on As3+ -induced immune toxicity

BACKGROUND

Selenium (Se)-enriched glycoproteins have been a research highlight for the role of both Se and glycoproteins in immunoregulation. Arsenic (As) is a toxicant that is potentially toxic to the immune function and consequently to human health. Several reports suggested that Se could reduce the toxicity of heavy metals. Moreover, more and more nutrients in food had been applied to relieve As-induced toxicity. Hence glycoproteins were isolated and purified from Se-enriched Grifola frondosa, and their preliminary characteristics as well as amelioration effect and mechanism on As³⁺ -induced immune toxicity were evaluated.

RESULTS

Four factions, namely Se-GPr11 (electrophoresis analysis exhibited one band: 14.32 kDa), Se-GPr22 (two bands: 20.57 and 31.12 kDa), Se-GPr33 (three bands: 15.08, 20.57 and 32.78 kDa) and Se-GPr44 (three bands: 16.73, 32.78 and 42.46 kDa), were obtained from Se-enriched G. frondosa via DEAE-52 and Sephacryl S-400 column. In addition, Se-GPr11 and Se-GPr44 are ideal proteins that contain high amounts of almost all essential amino acids. Thereafter, the RAW264.7 macrophage model was adopted to estimate the effect of Se-GPr11 and Se-GPr44 on As³⁺ -induced immune toxicity. The results showed that the pre-intervention method was the best consequent and the potential mechanisms were, first, by improving the oxidative stress state (enhancing the activity of superoxide dismutase and glutathione peroxidase, decreasing the levels of reactive oxygen species and malondialdehyde); secondly, through nuclear factor-κB and mitogen-activated protein kinase-mediated upregulation cytokines (interleukin-2 and interferon-γ) secretion induced by As³⁺ .

CONCLUSION

The results suggested Se-enriched G. frondosa may be a feasible supplement to improve health level of the As³⁺ pollution population. © 2021 Society of Chemical Industry.

Long non-coding RNAs and microRNAs as crucial regulators in cardio-oncology

Cancer is one of the leading causes of morbidity and mortality worldwide. Significant improvements in the modern era of anticancer therapeutic strategies have increased the survival rate of cancer patients. Unfortunately, cancer survivors have an increased risk of cardiovascular diseases, which is believed to result from anticancer therapies. The emergence of cardiovascular diseases among cancer survivors has served as the basis for establishing a novel field termed cardio-oncology. Cardio-oncology primarily focuses on investigating the underlying molecular mechanisms by which anticancer treatments lead to cardiovascular dysfunction and the development of novel cardioprotective strategies to counteract cardiotoxic effects of cancer therapies. Advances in genome biology have revealed that most of the genome is transcribed into non-coding RNAs (ncRNAs), which are recognized as being instrumental in cancer, cardiovascular health, and disease. Emerging studies have demonstrated that alterations of these ncRNAs have pathophysiological roles in multiple diseases in humans. As it relates to cardio-oncology, though, there is limited knowledge of the role of ncRNAs. In the present review, we summarize the up-to-date knowledge regarding the roles of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in cancer therapy-induced cardiotoxicities. Moreover, we also discuss prospective therapeutic strategies and the translational relevance of these ncRNAs.

MMP2-responsive dual-targeting drug delivery system for valence-controlled arsenic trioxide prodrug delivery against hepatic carcinoma

Arsenic trioxide (ATO) is the active ingredient in traditional Chinese medicine, i.e., Arsenic, which has shown excellent therapeutic effects on hepatocellular carcinoma. However, due to its poor tumor distribution and high toxicity, the mass adoption of ATO in clinical applications has been severely impeded. In this study, matrix metalloproteinase 2 (MMP2)-responsive cleaved cell-penetrating peptide (PF) and folate (FA) co-modified liposome coated calcium arsenate nanoparticles (FA/PF-LP-CaAs) were fabricated based on these two considerations: (1) The tumor microenvironment characterized by overexpressed MMP2 in extracellular matrix and folate receptor on the cell membrane can enhance drug accumulation and accelerate endocytosis; (2) leveraging different toxicity of arsenic in different valence states, i.e., AsV can be reduced to more toxic AsIII by glutathione in tumor cells. Furthermore, FA/PF-LP-CaAs could be responsively degraded by the mild acidic tumor environment, and the degraded product could escape from lysosomes after endocytosis. More importantly, in light of the in vivo biodistribution and pharmacodynamic studies, the vehicle was able to accumulate in the tumor efficiently. Also, it was able to exhibit excellent anti-tumor efficacy with minimized side effects when compared to single-modified counterparts. Thus, the novel strategy based on the tumor microenvironment proposed in this work can enhance the tumor-targeting efficiency and intratumor toxicity.

Key Characteristics of Cardiovascular Toxicants

BACKGROUND

The concept of chemical agents having properties that confer potential hazard called key characteristics (KCs) was first developed to identify carcinogenic hazards. Identification of KCs of cardiovascular (CV) toxicants could facilitate the systematic assessment of CV hazards and understanding of assay and data gaps associated with current approaches.

OBJECTIVES

We sought to develop a consensus-based synthesis of scientific evidence on the KCs of chemical and nonchemical agents known to cause CV toxicity along with methods to measure them.

METHODS

An expert working group was convened to discuss mechanisms associated with CV toxicity.

RESULTS

The group identified 12 KCs of CV toxicants, defined as exogenous agents that adversely interfere with function of the CV system. The KCs were organized into those primarily affecting cardiac tissue (numbers 1-4 below), the vascular system (5-7), or both (8-12), as follows: 1) impairs regulation of cardiac excitability, 2) impairs cardiac contractility and relaxation, 3) induces cardiomyocyte injury and death, 4) induces proliferation of valve stroma, 5) impacts endothelial and vascular function, 6) alters hemostasis, 7) causes dyslipidemia, 8) impairs mitochondrial function, 9) modifies autonomic nervous system activity, 10) induces oxidative stress, 11) causes inflammation, and 12) alters hormone signaling.

DISCUSSION

These 12 KCs can be used to help identify pharmaceuticals and environmental pollutants as CV toxicants, as well as to better understand the mechanistic underpinnings of their toxicity. For example, evidence exists that fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5)] air pollution, arsenic, anthracycline drugs, and other exogenous chemicals possess one or more of the described KCs. In conclusion, the KCs could be used to identify potential CV toxicants and to define a set of test methods to evaluate CV toxicity in a more comprehensive and standardized manner than current approaches. https://doi.org/10.1289/EHP9321.

Recent Progress in Environmental Toxins-Induced Cardiotoxicity and Protective Potential of Natural Products

Humans are unconsciously exposed to environmental toxins including heavy metals as well as various pesticides, which have deleterious effects on human health. Accumulating studies pointed out that exposure to environmental toxins was associated with various cardiopathologic effects. This review summarizes the main mechanisms of cardiotoxicity induced by environmental toxins (cadmium, arsenic and pesticides) and discusses the potential preventive effects of natural products. These findings will provide a theoretical basis and novel agents for the prevention and treatment of environmental toxins-induced cardiotoxicity. Furthermore, the limitations of current studies, future needs and priorities are discussed.

Liposome-Coated Arsenic-Manganese Complex for Magnetic Resonance Imaging-Guided Synergistic Therapy Against Carcinoma

Purpose

A liposome-coated arsenic-manganese complex, denoted as LP@MnAs_x was constructed for the targeted delivery of arsenic trioxide (ATO) against carcinoma.

Methods

Arsenite, the prodrug of ATO, was encapsulated within a liposome via electrostatic interaction with the manganese ions. The as-prepared material was characterized with dynamic light scattering and transmission electron microscopy. The entrapment efficiency and drug loading of arsenic in the carrier were measured using inductively coupled plasma spectrometry. The in vitro release of arsenic was evaluated by using the dialysis bag method. Furthermore, the Fenton-like activity and in vitro cytodynamics research of LP@MnAs_x were monitored in this work. And the cellular uptake study was used to investigate the in vitro entry mechanism. Furthermore, the cytotoxicity, cell apoptosis and cell cycle study were performed to evaluate the tumor-killing efficiency. Also, the pharmacokinetic and antitumor studies were investigated in HepG2 tumor-bearing nude mice.

Results

The as-prepared LP@MnAs_x possessed a spherical morphology, uniformly distributed hydrodynamic diameter, and excellent drug-loading efficiency. LP@MnAs_x displayed robust stability and sustained-release profile under physiological environments. LP@MnAs_x could degrade with high sensitivity to the pH variation in the tumor microenvironment. As such, this could lead to a burst release profile of Mn²⁺ and arsenite to achieve a synergistic therapy of chemodynamic therapy and chemotherapy. When compared to the carrier-free arsenate, in vitro experiments revealed that LP@MnAs_x exhibited enhanced cellular uptake and tumor-killing efficiency. LP@MnAs_x also demonstrated significantly enhanced tumor-specific in vivo distribution of arsenic, prolonged systemic circulation lifetime, and increased accumulation at the tumor site.

Conclusion

Based on the experimental results, LP@MnAs_x is an ideal arsenic-based nanodelivery system, whereby it can improve the non-specific distribution of NaAsO₂ in vivo. Thus, this work can expand the research and application of arsenic trioxide against solid tumors.

Pharmacokinetic Characteristics, Tissue Bioaccumulation and Toxicity Profiles of Oral Arsenic Trioxide in Rats: Implications for the Treatment and Risk Assessment of Acute Promyelocytic Leukemia

Oral arsenic trioxide (ATO) has demonstrated a favorable clinical efficiency in the treatment of acute promyelocytic leukemia (APL). However, the pharmacokinetic characteristics, tissue bioaccumulation, and toxicity profiles of arsenic metabolites in vivo following oral administration of ATO have not yet been characterized. The present study uses high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) to assess the pharmacokinetics of arsenic metabolites in rat plasma after oral and intravenous administration of 1 mg kg^-1 ATO. In addition, the bioaccumulation of arsenic metabolites in blood and selected tissues were evaluated after 28 days oral administration of ATO in rats at a dose of 0, 2, 8, and 20 mg kg^-1 d^-1. The HPLC-HG-AFS analysis was complemented by a biochemical, hematological, and histopathological evaluation conducted upon completion of ATO treatment. Pharmacokinetic results showed that arsenite (As^III) reached a maximum plasma concentration rapidly after initial dosing, and the absolute bioavailability of As^III was 81.03%. Toxicological results showed that the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and white blood cells (WBC) in the 20 mg kg^-1 d^-1 ATO group were significantly increased compared to the control group (p < 0.05). The distribution trend of total arsenic in the rat was as follows: whole blood > kidney > liver > heart. Dimethylated arsenic (DMA) was the predominant bioaccumulative metabolite in the whole blood, liver, and heart, while monomethylated arsenic (MMA) was the predominant one in the kidney. Collectively, these results revealed that oral ATO was rapidly absorbed, well-tolerated, and showed organ-specific and dose-specific bioaccumulation of arsenic metabolites. The present study provides preliminary evidence for clinical applications and the long-term safety evaluation of oral ATO in the treatment of APL.

Concurrent Heavy Metal Exposures and Idiopathic Dilated Cardiomyopathy: A Case-Control Study from the Katanga Mining Area of the Democratic Republic of Congo

Blood and/or urine levels of 27 heavy metals were determined by ICPMS in 41 patients with dilated cardiomyopathy (DCM) and 29 presumably healthy subjects from the Katanga Copperbelt (KC), in the Democratic Republic of Congo (DRC). After adjusting for age, gender, education level, and renal function, DCM probability was almost maximal for blood concentrations above 0.75 and 150 µg/dL for arsenic and copper, respectively. Urinary concentrations above 1 for chromium, 20 for copper, 600 for zinc, 30 for selenium, 2 for cadmium, 0.2 for antimony, 0.5 for thallium, and 0.05 for uranium, all in μg/g of creatinine, were also associated with increased DCM probability. Concurrent and multiple exposures to heavy metals, well beyond permissible levels, are associated with increased probability for DCM. Study findings warrant screening for metal toxicity in case of DCM and prompt public health measures to reduce exposures in the KC, DRC.

Long non-coding RNA DICER1-AS1-low expression in arsenic-treated A549 cells inhibits cell proliferation by regulating the cell cycle pathway

Arsenic, an environmental pollution with diverse toxicities, incurs public health problems. Arsenic trioxide could inhibit cell proliferation in vitro experiments, but the underlying mechanisms are not fully known. LncRNAs are also involved in the arsenic-induced toxicological responses. In our study, we found that the expression of lncRNA DICER1-AS1 was significantly inhibited by sodium arsenite in a dose-dependent manner. DICER1-AS1 silencing decreased the A549 cell proliferation and inhibited cell cycle progression. Importantly, DICER1-AS1 silencing induced upregulation of p21 and downregulation of Cyclin A2, Cyclin E2, CDK1 and PCNA. In conclusion, our study provided a new lncRNA-dictated regulatory mechanism participating in arsenic-induced inhibition of cell proliferation.

ATF3 Promotes Arsenic-Induced Apoptosis and Oppositely Regulates DR5 and Bcl-xL Expression in Human Bronchial Epithelial Cells

Arsenic is one of the most common environmental pollutants eliciting serious public health issues; however, it is also a well-recognized chemotherapeutic agent for acute promyelocytic leukemia. The association between arsenic exposure and lung diseases has been established, but underlying molecular mechanisms are poorly defined. Here we investigated the toxicology of arsenic in airway epithelium. Arsenic rapidly induced the activating transcription factor ATF3 expression through the JNK and p38 pathways. The ATF3-deficient BEAS-2B cells were relatively resistant to apoptosis upon arsenic exposure, indicating a facilitatory role of ATF3 in arsenic-induced apoptosis. We further showed that ATF3 oppositely regulated the transcription of death receptor (DR5) and Bcl2-like 1 (Bcl-xL) by directly binding to the promoter DR5 and Bcl-xL. Altogether, our findings establish ATF3 as a pro-apoptotic protein in arsenic-induced airway epithelial apoptosis through transcriptionally regulating DR5 and Bcl-xL, highlighting the potential of ATF3 as an early and sensitive biomarker for arsenic-caused lung injury.

A review on the protective effects of naringenin against natural and chemical toxic agents

Naringenin (NRG), as a flavanone from flavonoids family, is widely found in grapefruit, lemon tomato, and Citrus fruits. NRG has shown strong anti-inflammatory and antioxidant activities in body organs via mechanisms such as enhancement of glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity, but reduction of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malondialdehyde (MDA). Furthermore, NRG anti-apoptotic potential was indicated to be mediated by regulating B-cell lymphoma (Bcl-2), Bcl-2-associated X protein (Bax) and caspase3/9. Overall, these properties make NRG a highly fascinating compound with beneficial pharmacological effects. Based on the literature, NRG-induced protective effects against toxicities produced by natural toxins, pharmaceuticals, heavy metals, and environmental chemicals, were mainly mediated via suppression of lipid peroxidation, oxidative stress (through boosting the antioxidant arsenal), and inflammatory factors (e.g., TNF-α, interleukin [IL]-6, IL-10, and IL-12), and activation of PI3K/Akt and MAPK survival signaling pathways. Despite considerable body of evidence on protective properties of NRG against a variety of toxic compounds, more well-designed experimental studies and particularly, clinical trials are required before reaching a concrete conclusion. The present review discusses how NRG protects against the above-noted toxic compounds.

Application of the in vivo oxidative stress reporter Hmox1 as mechanistic biomarker of arsenic toxicity

Inorganic arsenic (iAs) is a naturally occurring metalloid present in drinking water and polluted air exposing millions of people globally. Epidemiological studies have linked iAs exposure to the development of numerous diseases including cognitive impairment, cardiovascular failure and cancer. Despite intense research, an effective therapy for chronic arsenicosis has yet to be developed. Laboratory studies have been of great benefit in establishing the pathways involved in iAs toxicity and providing insights into its mechanism of action. However, the in vivo analysis of arsenic toxicity mechanisms has been difficult by the lack of reliable in vivo biomarkers of iAs's effects. To address this issue we have applied the use of our recently developed stress reporter models to study iAs toxicity. The reporter mice Hmox1 (oxidative stress/inflammation; HOTT) and p21 (DNA damage) were exposed to iAs at acute and chronic, environmentally relevant, doses. We observed induction of the oxidative stress reporters in several cell types and tissues, which was largely dependent on the activation of transcription factor NRF2. We propose that our HOTT reporter model can be used as a surrogate biomarker of iAs-induced oxidative stress, and it constitutes a first-in-class platform to develop treatments aimed to counteract the role of oxidative stress in arsenicosis. Indeed, in a proof of concept experiment, the HOTT reporter mice were able to predict the therapeutic utility of the antioxidant N-acetyl cysteine in the prevention of iAs associated toxicity.

A phase 1 trial of 4-(N-(S-penicillaminylacetyl)amino)-phenylarsonous acid (PENAO) in patients with advanced solid tumours

PURPOSE

This phase I study was conducted to evaluate the safety and Maximum Tolerated Dose of PENAO (4-(N-(S-penicillaminylacetyl)amino)-phenylarsonous acid), a second-generation organic arsenical with anti-mitochondrial activity, when given as a continuous intravenous infusion (CIVI), in patients with advanced solid tumours.

METHODS

Eligibility criteria for this trial included age ≥ 18 years, advanced solid tumour, ECOG Performance Status ≤ 1 and adequate organ function. PENAO was administered by CIVI, with dose levels initially increased by infusion duration in a 21-day cycle at a fixed daily dose and then increased daily dose. Standard dose-limiting toxicity (DLT) definitions were used in a "3 + 3" design. Patients had regular monitoring of toxicity and efficacy. Pharmacokinetic assays of serum and urine As were performed.

RESULTS

Twenty-six patients were treated across 8 dose levels. The only dose-limiting toxicity (DLT) observed was fatigue, that occurred in one patient treated at the highest dose level of 9 mg/m²/day. No significant organ toxicity or objective responses were observed, although there were two patients with stable disease lasting up to 7 months. Pharmacokinetic analysis unexpectedly indicated a half-life of 9-19 days, invalidating the CIVI dosing resulting in discontinuation of the study before the RP2D was defined.

CONCLUSIONS

PENAO was administered by CIVI at dose levels up to 9 mg/m²/day with only one DLT noted. Pharmacokinetic studies invalidated the rationale for continuous dosing and led to discontinuation of the trial without defining a RP2D. Future clinical development of PENAO will use intermittent dosing schedule, alone and in combination with rapamycin.

Ursodeoxycholic Acid Protects Against Arsenic Induced Hepatotoxicity by the Nrf2 Signaling Pathway

Arsenic is ubiquitous toxic metalloid responsible for many human diseases all over the world. Contrastingly, Ursodeoxycholic acid (UDCA) has been suggested as efficient antioxidant in various liver diseases. However, there are no reports of the effects of UDCA on arsenious acid [As(III)]-induced hepatotoxicity. The objective of this study is to elucidate the protective actions of UDCA on As(III)-induced hepatotoxicity and explore its controlling role in biomolecular mechanisms in vivo and in vitro. The remarkable liver damage induced by As(III) was ameliorated by treatment with UDCA, as reflected by reduced histopathological changes of liver and elevation of serum AST, ALT levels. UDCA play a critical role in stabilization of cellular membrane potential, inhibition of apoptosis and LDH leakage in LO2 cells. Meanwhile, the activities of SOD, CAT and GSH-Px and the level of TSH, GSH were enhanced with UDCA administration, while the accumulations of intracellular ROS, MDA and rate of GSSG/GSH were decreased in vivo and in vitro. Further study disclosed that UDCA significantly inhibited As(III)-induced apoptosis through increasing the expression of Bcl-2 and decreasing the expression of Bax, p53, Cyt C, Cleaved caspase-3 and 9. Moreover, UDCA promoted the expression of nuclear Nrf2, HO-1, and NQO1, although arsenic regulated nuclear translocation of Nrf2 positively. When Nrf2 was silenced, the protective effect of UDCA was abolished. Collectively, the results of this study showed that UDCA protects hepatocytes antagonize As(III)-induced cytotoxicity, and its mechanism may be related to activation of Nrf2 signaling.

Mechanisms underlying the protective effect of tannic acid against arsenic trioxide‑induced cardiotoxicity in rats: Potential involvement of mitochondrial apoptosis

Arsenic trioxide (ATO) is a frontline chemotherapy drug used in the therapy of acute promyelocytic leukemia. However, the clinical use of ATO is hindered by its cardiotoxicity. The present study aimed to observe the potential effects and underlying mechanisms of tannic acid (TA) against ATO-induced cardiotoxicity. Male rats were intraperitoneally injected with ATO (5 mg/kg/day) to induce cardiotoxicity. TA (20 and 40 mg/kg/day) was administered to evaluate its cardioprotective efficacy against ATO-induced heart injury in rats. Administration of ATO resulted in pathological damage in the heart and increased oxidative stress as well as levels of serum cardiac biomarkers creatine kinase and lactate dehydrogenase and the inflammatory marker NF-κB (p65). Conversely, TA markedly reversed this phenomenon. Additionally, TA treatment caused a notable decrease in the expression levels of cleaved caspase-3/caspase-3, Bax, p53 and Bad, while increasing Bcl-2 expression levels. Notably, the application of TA decreased the expression levels of cytochrome c, second mitochondria-derived activator of caspases and high-temperature requirement A2, which are apoptosis mitochondrial-associated proteins. The present findings indicated that TA protected against ATO-induced cardiotoxicity, which may be associated with oxidative stress, inflammation and mitochondrial apoptosis.

Heavy metals analysis in chalk sticks based on ICP-AES and their associated health risk

The purpose of this study was to determine the contents of 12 metals in obtainable chalk sticks and assess their associated health risk. Chalk stick samples from 16 factories were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results showed that 12 metals were detectable in white and colored chalks. The contents of Al, Fe, and Mg were in the range of 646.2-3909 μg/g, 408.8-2075.1 μg/g, and 125-6825.7 μg/g, respectively. Additionally, the levels of Cu, Pb, Mn, and Cr were ranked in the order of Cu>Cr>Pb>Mn, while the maximum levels of As, Ni, Cd, and Sn in all samples (9.90, 10.14, 7.27, and 6.08 μg/g, respectively) were relatively lower than those of other metals. Furthermore, the cumulative hazard index (HI) values of all metals and carcinogenic risk (CR) of As (1.12E-4), Ni (1.39E-4), and Cr (1.15E-4) for children were also higher than the threshold value (1.0E-6 to 1.0E-4), suggesting that chalk dust particles may exert adverse effects on children.

Arsenic trioxide as a novel anti-glioma drug: a review

Arsenic trioxide has shown a strong anti-tumor effect with little toxicity when used in the treatment of acute promyelocytic leukemia (APL). An effect on glioma has also been shown. Its mechanisms include regulation of apoptosis and autophagy; promotion of the intracellular production of reactive oxygen species, causing oxidative damage; and inhibition of tumor stem cells. However, glioma cells and tissues from other sources show different responses to arsenic trioxide. Researchers are working to enhance its efficacy in anti-glioma treatments and reducing any adverse reactions. Here, we review recent research on the efficacy and mechanisms of action of arsenic trioxide in the treatment of gliomas to provide guidance for future studies.

Arsenic induces dose-dependent structural and ultrastructural pathological remodeling in the heart of Wistar rats

AIM

Arsenic, an environmental contaminant, represents a public health problem worldwide. Studies have shown its association with molecular mechanisms related to cardiomyocytes redox balance. However, the microstructure and ultrastructure of cardiac tissue, as well as the activity of its antioxidant defenses front of disturbances in the mineral bioavailability induced by arsenic are still scarce. Thus, the aim of this study was to evaluate if arsenic exposure might induce structural and ultrastructural damages in cardiac tissue, including pathological remodeling of the parenchyma and stroma. Moreover, its impact on micromineral distribution and antioxidant enzymes activity in heart tissue was also evaluated.

MAIN METHODS

Adult male Wistar rats were divided into three groups that received 0, 1 and 10 mg/L sodium arsenite in drinking water for eight weeks. The hearts were collected and subjected to structural and ultrastructural analysis, mineral microanalysis and antioxidant enzymes quantification. Functional markers of cardiac damages were evaluated using serum samples.

KEY FINDINGS

Arsenic exposure induced dose-dependent structural and ultrastructural remodeling of cardiac tissue, with parenchyma loss, increase of stroma components, collagen deposition, and pathological damages such as inflammation, sarcomere disorganization, mitochondria degeneration and myofilament dissociation. Moreover, this metalloid was bioaccumulated in the tissue affecting its micromineral content, which resulted in antioxidant imbalance and increased levels of oxidative stress and cardiac markers.

SIGNIFICANCE

Taken together, our findings indicate that the heart is a potential target to arsenic toxicity, and long-term exposure to this metalloid must be avoided, once it might induce several cardiac tissue pathologies.

LncRNA UCA1 Antagonizes Arsenic-Induced Cell Cycle Arrest through Destabilizing EZH2 and Facilitating NFATc2 Expression

Arsenic (As) is a widespread metalloid contaminant, and its internal exposure is demonstrated to cause serious detrimental health problems. Albeit considerable studies are performed to interrogate the molecular mechanisms responsible for As-induced toxicities, the exact mechanisms are not fully understood yet, especially at the epigenetic regulation level. In the present study, it is identified that long non-coding RNA (lncRNA) urothelial cancer associated 1 (UCA1) alleviates As-induced G2/M phase arrest in human liver cells. Intensive mechanistic investigations illustrate that UCA1 interacts with enhancer of zeste homolog 2 (EZH2) and accelerates the latter's protein turnover rate under normal and As-exposure conditions. The phosphorylation of EZH2 at the Thr-487 site by cyclin dependent kinase 1 (CDK1) is responsible for As-induced EZH2 protein degradation, and UCA1 enhances this process through increasing the interaction between CDK1 and EZH2. As a consequence, the cell cycle regulator nuclear factor of activated T cells 2 (NFATc2), a downstream target of EZH2, is upregulated to resist As-blocked cell cycle progress and cytotoxicity. In conclusion, the findings decipher a novel prosurvival signaling pathway underlying As toxicity from the perspective of epigenetic regulation: UCA1 facilitates the ubiquitination of EZH2 to upregulate NFATc2 and further antagonizes As-induced cell cycle arrest.

Milk thistle (Silybum Marianum) as an antidote or a protective agent against natural or chemical toxicities: a review

Biological and chemical agents cause dangerous effects on human health via different exposing ways. Recently, herbal medicine is considered as a biological and safe treatment for toxicities. Silybum marianum (milk thistle), belongs to the Asteraceae family, possesses different effects such as hepatoprotective, cardioprotective, neuroprotective, anti-inflammatory and anti-carcinogenic activities. Several studies have demonstrated that this plant has protective properties against toxic agents. Herein, the protective effects of S. marianum and its main component, silymarin, which is the mixture of flavonolignans including silibinin, silydianin and silychristin acts against different biological (mycotoxins, snake venoms, and bacterial toxins) and chemical (metals, fluoride, pesticides, cardiotoxic, neurotoxic, hepatotoxic, and nephrotoxic agents) poisons have been summarized. This review reveals that main protective effects of milk thistle and its components are attributed to radical scavenging, anti-oxidative, chelating, anti-apoptotic properties, and regulating the inflammatory responses.