Assessing the mechanism of DNA damage induced by lead through direct and indirect interactions

Paternal Lead Exposure and Pregnancy Outcomes: A Systematic Review and Meta-Analysis

Paternal lead exposure has emerged as a potential contributor to adverse pregnancy outcomes, yet its impact remains underexplored compared to maternal exposure. This systematic review and meta-analysis synthesize evidence on the association between paternal lead exposure and pregnancy outcomes to inform public health interventions and future research. To evaluate the association between paternal lead exposure and adverse pregnancy outcomes, including spontaneous abortion, low birth weight, preterm birth, small-for-gestational-age, and congenital anomalies. A systematic search of PubMed, Scopus, and Google Scholar was conducted up to August 2024. Observational studies examining paternal lead exposure (⩾15 µg/dL) and its effects on pregnancy outcomes were included. Data synthesis adhered to PRISMA 2020 guidelines, and study quality was assessed using the Newcastle-Ottawa Scale. Meta-analysis was performed using a random-effects model to compute pooled odds ratios (ORs) with 95% confidence intervals (CIs). Eleven studies were included in the systematic review, with 7 contributing to the meta-analysis. The pooled OR for congenital anomalies associated with paternal lead exposure was statistically significant (OR = 2.09, 95% CI: 2.09-3.35; P < .01), indicating a strong association. However, no significant associations were observed for other outcomes: spontaneous abortion (OR = 1.11, 95% CI: 0.75-1.64), low birth weight (OR = 0.98, 95% CI: 0.68-1.39), preterm birth (OR = 1.57, 95% CI: 0.61-4.05), and small-for-gestational-age infants (OR = 0.92, 95% CI: 0.78-1.09). Heterogeneity was low for most outcomes, except for spontaneous abortion (I 2 = 39%) and preterm birth (I 2 = 52%). This study highlights a significant association between paternal lead exposure and congenital anomalies, emphasizing the need for occupational and environmental regulations targeting lead exposure among men of reproductive age.

Overall effects of topsoil elements on cancer mortality in rural Greece: A modeling approach

This ecological study examines cancer mortality rates in 61 rural Greek municipalities, covering in total 7,305,554 person-years from 2000 to 2015, based on the Hellenic Statistical Authority data. Topsoil concentrations of Mn, Ni, Pb, Be, As and Cd in Greek grazing land samples were obtained from the GEMAS (Geochemical Mapping of Agricultural and Grazing land Soil) project. Municipalities of rural regions with population of up to 20,000 people were selected as the study area and were divided into four quartiles, according to their age-specific cancer mortality rates, to identify the most divergent areas of low/high mortality. Fusion of demographic data with topsoil measurements aimed to reveal their potential association. Towards a univariate analysis, comparing each element individually across the low/high mortality regions revealed significant overlaps in distributions of concentrations for all elements. Machine learning multi-element models were built to predict whether an area would have a low or high cancer mortality rate, based simultaneously and solely on the concentrations of the six elements of the region, for each group. The out-of-sample median accuracy of the model was very high (83.3%) for the 0-29 age group, high (66.7%) for the 30-39, 40-49 and 50-59 age groups, while the accuracy decreased significantly above age of 60. The interaction of Mn, As, Ni, and partially Be, contributes most to the model's prediction for the 0-29 age group, As becomes the main contributor in the 30-39 age group, while all six elements contribute almost equally for the 40-49 group, and the interaction of Ni, Mn and Be becomes important in the 50-59 age group. The findings of this study strongly suggest that topsoil elements may jointly influence the frequency and geographical distribution of cancer.

A wide survey of heavy metals-induced in-vitro DNA replication stress characterized by rate-limited replication

Heavy metals (HMs) are environmental pollutants that pose a threat to human health and have been accepted to cause various diseases, including cancer and developmental disorders. DNA replication stress has been identified to be associated with such diseases. However, the effect of HMs exclusively on DNA replication stress is still not well understood. In this study, DNA replication stress induced by thirteen HMs was assessed using a simplified in-vitro DNA replication model. Two parameters, Cte/Ctc reflecting the cycle threshold value alteration and Ke/Kc reflecting the linear phase slope change, were calculated based on the DNA replication amplification curve to evaluate the rate of exponential and linear phases. These parameters were used to detect the replication rate reflecting in-vitro DNA replication stress induced by tested HMs. According to the effective concentrations and rate-limiting degree, HMs were ranked as follows: Hg, Ce > Pb > Zn > Cr > Cd > Co > Fe > Mn, Cu, Bi, Sr, Ni. Additionally, EDTA could relieve the DNA replication stress induced by some HMs. In conclusion, this study highlights the potential danger of HMs themselves on DNA replication and provides new insight into the possible links between HMs and DNA replication-related diseases.

Pollutant bioaccumulation in sentinel fish chronically exposed in Iguaçu river reservoirs (Southern Brazil) and human health risk of fish consumption

Bioaccumulation studies in fish mark the initial phase of assessing the risk of chemical exposure to biota and human populations. The Iguaçu River boasting a diverse endemic ichthyofauna, is grappling with the repercussions of human activities. This study delved into the bioaccumulation of micropollutants, the early-warning effects on Rhamdia quelen and Oreochomis niloticus in the Segredo Reservoir (HRS) and the potential risk of human exposure. Two groups of caged fish in three sites of the reservoir were exposed during the autumn-winter and spring-summer, while a third group (O. niloticus) underwent a twelve-month exposure, and inorganic and organic chemicals analysis in water, sediment, and biota. Additionally, metallothionein expression and genotoxicity were employed as biomarkers. PAHs, PCBs, Al, Cu, Fe, and As in water and DDTs, Cu, Zn, and As in sediment surpassed the thresholds set by Brazilian regulations, where DDT exhibited bioaccumulation in muscle, alongside metals in liver, kidney, gills, and muscle tissues. R. quelen showed metallothionein expression whereas DNA damage and NMA frequencies were elevated in target organs and in brain and erythrocytes of O. niloticus during summer. In this species the DNA damage in liver was remarkable after twelve months. Target Hazard Quotients and Cancer Risk values shedding light on the vulnerability of both children and adults. The reservoir's conditions led to heightened sensitivity to micropollutants for R. quelen species. The data presented herein provides decision-makers with pertinent insights to facilitate effective management and conservation initiatives within the Iguaçu Basin.

Micronuclei frequency and exposure to chemical mixtures in three Colombian mining populations

The Colombian mining industry has witnessed significant growth. Depending on the scale and mineral extracted, complex chemical mixtures are generated, impacting the health of occupationally exposed populations and communities near mining projects. Increasing evidence suggests that chromosomal instability (CIN) is an important link between the development of certain diseases and exposure to complex mixtures. To better understand the effects of exposure to complex mixtures we performed a biomonitoring study on 407 healthy individuals from four areas: three located in municipalities exploiting different-scale mining systems and a reference area with no mining activity. Large, medium, and small-scale mining systems were analyzed in Montelibano (Córdoba), artisanal and small-scale mining (ASGM) in Nechí (Antioquia), and a closed mining system in Aranzazu (Caldas). The reference area with no mining activity was established in Montería (Córdoba). ICP-MS measured multi-elemental exposure in hair, and CIN was evaluated using the cytokinesis-block micronucleus technique (MNBN). Exposure to mixtures of chemical elements was comparable in workers and residents of the mining areas but significantly higher compared to reference individuals. In Montelibano, increased MNBN frequencies were associated with combined exposure to Se, Hg, Mn, Pb, and Mg. This distinct pattern significantly differed from other areas. Specifically, in Nechí, Cr, Ni, Hg, Se, and Mg emerged as the primary contributors to elevated frequencies of MNBN. In contrast, a combination of Hg and Ni played a role in increasing MNBN in Aranzazu. Interestingly, Se consistently correlated with increased MNBN frequencies across all active mining areas. Chemical elements in Montelibano exhibit a broader range compared to other mining zones, reflecting the characteristics of the high-impact and large-scale mining in the area. This research provides valuable insights into the effects of exposure to chemical mixtures, underscoring the importance of employing this approach in the risk assessment of communities, especially those from residential areas.

Effects of antimony exposure on DNA damage and genome-wide variation in zebrafish (Danio rerio) liver

Antimony (Sb) is a potentially toxic and carcinogenic cumulative contaminant that poses a serious threat to aquatic ecosystems. To better clarify the genotoxicity of Sb and its mechanism of action. In this study, we investigated DNA damage and genome-wide variation in the liver of a model organism, zebrafish (Danio rerio), under subacute Sb exposure and explored its potential toxicological mechanisms. The results showed that medium and high concentrations of Sb significantly reduced the total antioxidant capacity and increased the content of reactive oxygen species in zebrafish liver, and further studies revealed that it increased oxidative DNA damage and DNA-DNA cross-link (DDC), but had little effect on DNA-protein cross-link (DPC). The result of resequencing showed that the mutation sites of the genes with high concentrations of Sb were higher than those with medium concentrations, and the mutation was mainly a single nucleotide. The pathways significantly enriched for nonsynonymous single nucleotide polymorphisms (SNPs) and insertion/deletion mutations (InDels) variant genes in the coding regions of both the medium and high Sb-treated groups were ECM-receptor interactions, and the high Sb-treated group also included lysine degradation, hematopoietic cell lineage, and cytokine-cytokine receptor interactions. This suggests that ECM-receptor interactions play an important role in the mechanism of antimony toxicity to the liver of zebrafish.

The culprits of superoxide dismutase inactivation under size-dependent stress of ultrafine carbon black: Superoxide anion, genotoxicity and protein corona

As a critical component of atmospheric ultrafine particulates, ultrafine carbon black (UFCB) brings great exposure risk to organisms. At present, the action pathway and activity regulation mechanism of UFCB on functional proteins in vivo are not clear, and the size-dependent effects of UFCB during this process need to be elucidated. Superoxide dismutase (SOD), one of the most applied biomarkers to assess the environmental impact of pollutants, plays crucial roles in resistance to oxidative stress. Here, based on the inactivation of SOD (84.79 %, 86.81 % and 91.70 %) in primary mouse hepatocytes exposed to UFCB (13 nm, 50 nm and 95 nm), oxidative stress, genotoxicity and protein molecular studies were employed to elucidate the inactivation mechanisms. Results showed that inhibition of UFCB-mediated superoxide anion (O₂^-) contributed to a decrease in SOD activity. Furthermore, the significant increase in 8-hydroxy-2-deoxyguanosine content and the comet tail formation indicated the occurrence of DNA damage, supporting that concomitant aberrant transcriptional and protein translational under gene regulation should be responsible for SOD inactivation. At the molecular level, the constricted backbone, reduced content of α-helix and fluorescence sensitization all demonstrated that the attachment-type binding of SOD on UFCB to form the 'protein corona' disrupted protein structure. Enzyme activity assays indicated that SOD backbone tightening and helix decay resulted in decreased activity, which should be another reason for intracellular SOD inactivation. More importantly, the particle sizes of UFCB exert powerful influences on SOD inactivation mechanisms. Smaller UFCB (13 nm) induced more severe O₂^- inhibition and DNA damage, while UFCB_50nm with the best dispersity bound more SOD and induced stronger molecular toxicity, which are their different strengths in stressing SOD inactivation in hepatocytes. Our findings provide novel insights for exploring functional proteins activity and underscore a potentially size-dependent risk of nanoparticles.

F, Barcelos GRM. Association between Polymorphisms of Hemochromatosis (HFE), Blood Lead (Pb) Levels, and DNA Oxidative Damage in Battery Workers

Occupational exposure to lead (Pb) continues to be a serious public health concern and may pose an elevated risk of genetic oxidative damage. In Brazil, car battery manufacturing and recycling factories represent a great source of Pb contamination, and there are no guidelines on how to properly protect workers from exposure or to dispose the process wastes. Previous studies have shown that Pb body burden is associated with genetic polymorphisms, which consequently may influence the toxicity of the metal. The aim of this study was to assess the impact of Pb exposure on DNA oxidative damage, as well as the modulation of hemochromatosis (HFE) polymorphisms on Pb body burden, and the toxicity of Pb, through the analysis of 8-hydroxy-2'-deoxyguanosine (8-OHdG), in subjects occupationally exposed to the metal. Male Pb-exposed workers (n = 236) from car battery manufacturing and recycling factories in Brazil participated in the study. Blood and plasma lead levels (BLL and PLL, respectively) were determined by ICP-MS and urinary 8-OHdG levels were measured by LC-MS/MS, and genotyping of HFE SNPs (rs1799945, C → G; and 1800562, G → A) was performed by TaqMan assays. Our data showed that carriers of at least one variant allele for HFE rs1799945 (CG + GG) tended to have higher PLL than those with the non-variant genotype (β = 0.34; p = 0.043); further, PLL was significantly correlated with the levels of urinary 8-OHdG (β = 0.19; p = 0.0060), while workers that carry the variant genotype for HFE rs1800562 (A-allele) showed a prominent increase in 8-OHdG, as a function of PLL (β = 0.78; p = 0.046). Taken together, our data suggest that HFE polymorphisms may modulate the Pb body burden and, consequently, the oxidative DNA damage induced by the metal.

Associations between DNA methylation and genotoxicity among lead-exposed workers in China

Studies have shown that lead (Pb) exposure caused genotoxicity, however, the underlying mechanisms remain unclear. A mechanism may be via DNA methylation which is one of the most widely studied epigenetic regulations for cellular activities. Whether this is involved in Pb-induced genotoxicity has rarely been studied. Our study aimed to examine whether DNA methylation was associated with Pb exposure and genotoxicity, and to explore its potential mediating roles. A total of 250 Pb-exposed workers were enrolled. Blood lead levels (BLLs) and genotoxic biomarkers (Micronuclei and Comet) were analyzed. Methylation levels at CpG sites of LINE1 and Alu and promoter region of P53, BRCA1, TRIM36 and OGG1 were measured by pyrosequencing. Generalized linear model (GLM) combined with restricted cubic splines (RCS) were used to analyze relationships between Pb exposure, DNA methylation and genotoxicity. Mediation effect was used to explore mediating roles of DNA methylation. The distribution of BLLs was right-skewed and showed wide ranges from 23.7 to 636.2 μg/L with median (P₂₅, P₇₅) being 218.4 (106.1, 313.9) μg/L among all workers. Micronuclei frequencies showed Poisson distribution [1.94 ± 1.88‰] and Comet tail intensity showed normal distribution [1.69 ± 0.93%]. GLM combined with RCS showed that Alu methylation was negatively associated with BLLs, while P53 and OGG1 methylation were positively associated with BLLs. Micronuclei were negatively associated with Alu and TRIM36 methylation but positively with P53 methylation. Comet was positively associated with P53 and BRCA1 methylation. Mediation effect showed that Alu methylation mediated 7% effects on association between Pb exposure and micronuclei, whereas, P53 methylation mediated 14% and BRCA1 mediated 9% effects on association between Pb exposure and Comet. Our data show that Pb exposure induced changes of global and gene-specific DNA methylation which mediated Pb-induced genotoxicity.

Elucidations of Molecular Mechanism and Mechanistic Effects of Environmental Toxicants in Neurological Disorders

Due to rising environmental and global public health concerns associated with environmental contamination, human populations are continually being exposed to environmental toxicants, including physical chemical mutagens widespread in our environment causing adverse consequences and inducing a variety of neurological disorders in humans. Physical mutagens comprise ionizing and non-ionizing radiation, such as UV rays, IR rays, X-rays, which produces a broad spectrum of neuronal destruction, including neuroinflammation, genetic instability, enhanced oxidative stress driving mitochondrial damage in the human neuronal antecedent cells, cognitive impairment due to alterations in neuronal function, especially in synaptic plasticity, neurogenesis repression, modifications in mature neuronal networks drives to enhanced neurodegenerative risk. Chemical Mutagens including alkylating agents (EMS, NM, MMS, and NTG), Hydroxylamine, nitrous acid, sodium azide, halouracils are the major toxic mutagen in our environment and have been associated with neurological disorders. These chemical mutagens create dimers of pyrimidine that cause DNA damage that leads to ROS generation producing mutations, chromosomal abnormalities, genotoxicity which leads to increased neurodegenerative risk. The toxicity of four heavy metal including Cd, As, Pb, Hg is mostly responsible for complicated neurological disorders in humans. Cadmium exposure can enhance the permeability of the BBB and penetrate the brain, driving brain intracellular accumulation, cellular dysfunction, and cerebral edema. Arsenic exerts its toxic effect by induction of ROS production in neuronal cells. In this review, we summarize the molecular mechanism and mechanistic effects of mutagens in the environment and their role in multiple neurological disorders.

Molecular mechanisms underlying the action of carcinogens in gastric cancer with a glimpse into targeted therapy

BACKGROUND

Gastric cancer imposes a substantial global health burden despite its overall incidence decrease. A broad spectrum of inherited, environmental and infectious factors contributes to the development of gastric cancer. A profound understanding of the molecular underpinnings of gastric cancer has lagged compared to several other tumors with similar incidence and morbidity rates, owing to our limited knowledge of the role of carcinogens in this malignancy. The International Agency for Research on Cancer (IARC) has classified gastric carcinogenic agents into four groups based on scientific evidence from human and experimental animal studies. This review aims to explore the potential comprehensive molecular and biological impacts of carcinogens on gastric cancer development and their interactions and interferences with various cellular signaling pathways.

CONCLUSIONS

In this review, we highlight recent clinical trial data reported in the literature dealing with different ways to target various carcinogens in gastric cancer. Moreover, we touch upon other multidisciplinary therapeutic approaches such as surgery, adjuvant and neoadjuvant chemotherapy. Rational clinical trials focusing on identifying suitable patient populations are imperative to the success of single-agent therapeutics. Novel insights regarding signaling pathways that regulate gastric cancer can potentially improve treatment responses to targeted therapy alone or in combination with other/conventional treatments. Preventive strategies such as control of H. pylori infection through eradication or immunization as well as dietary habit and lifestyle changes may reduce the incidence of this multifactorial disease, especially in high prevalence areas. Further in-depth understanding of the molecular mechanisms involved in the role of carcinogenic agents in gastric cancer development may offer valuable information and update state-of-the-art resources for physicians and researchers to explore novel ways to combat this disease, from bench to bedside. A schematic outlining of the interaction between gastric carcinogenic agents and intracellular pathways in gastric cancer H. pylori stimulates multiple intracellular pathways, including PI3K/AKT, NF-κB, Wnt, Shh, Ras/Raf, c-MET, and JAK/STAT, leading to epithelial cell proliferation and differentiation, apoptosis, survival, motility, and inflammatory cytokine release. EBV can stimulate intracellular pathways such as the PI3K/Akt, RAS/RAF, JAK/STAT, Notch, TGF-β, and NF-κB, leading to cell survival and motility, proliferation, invasion, metastasis, and the transcription of anti-apoptotic genes and pro-inflammatory cytokines. Nicotine and alcohol can lead to angiogenesis, metastasis, survival, proliferation, pro-inflammatory, migration, and chemotactic by stimulating various intracellular signaling pathways such as PI3K/AKT, NF-κB, Ras/Raf, ROS, and JAK/STAT. Processed meat contains numerous carcinogenic compounds that affect multiple intracellular pathways such as sGC/cGMP, p38 MAPK, ERK, and PI3K/AKT, leading to anti-apoptosis, angiogenesis, metastasis, inflammatory responses, proliferation, and invasion. Lead compounds may interact with multiple signaling pathways such as PI3K/AKT, NF-κB, Ras/Raf, DNA methylation-dependent, and epigenetic-dependent, leading to tumorigenesis, carcinogenesis, malignancy, angiogenesis, DNA hypermethylation, cell survival, and cell proliferation. Stimulating signaling pathways such as PI3K/Akt, RAS/RAF, JAK/STAT, WNT, TGF-β, EGF, FGFR2, and E-cadherin through UV ionizing radiation leads to cell survival, proliferation, and immortalization in gastric cancer. The consequence of PI3K/AKT, NF-κB, Ras/Raf, ROS, JAK/STAT, and WNT signaling stimulation by the carcinogenic component of Pickled vegetables and salted fish is the Warburg effect, tumorigenesis, angiogenesis, proliferation, inflammatory response, and migration.

Unboxing the molecular modalities of mutagens in cancer

The etiology of the majority of human cancers is associated with a myriad of environmental causes, including physical, chemical, and biological factors. DNA damage induced by such mutagens is the initial step in the process of carcinogenesis resulting in the accumulation of mutations. Mutational events are considered the major triggers for introducing genetic and epigenetic insults such as DNA crosslinks, single- and double-strand DNA breaks, formation of DNA adducts, mismatched bases, modification in histones, DNA methylation, and microRNA alterations. However, DNA repair mechanisms are devoted to protect the DNA to ensure genetic stability, any aberrations in these calibrated mechanisms provoke cancer occurrence. Comprehensive knowledge of the type of mutagens and carcinogens and the influence of these agents in DNA damage and cancer induction is crucial to develop rational anticancer strategies. This review delineated the molecular mechanism of DNA damage and the repair pathways to provide a deep understanding of the molecular basis of mutagenicity and carcinogenicity. A relationship between DNA adduct formation and cancer incidence has also been summarized. The mechanistic basis of inflammatory response and oxidative damage triggered by mutagens in tumorigenesis has also been highlighted. We elucidated the interesting interplay between DNA damage response and immune system mechanisms. We addressed the current understanding of DNA repair targeted therapies and DNA damaging chemotherapeutic agents for cancer treatment and discussed how antiviral agents, anti-inflammatory drugs, and immunotherapeutic agents combined with traditional approaches lay the foundations for future cancer therapies.

The associations between air pollutant exposure and neutralizing antibody titers of an inactivated SARS-CoV-2 vaccine

Air pollution is a critical risk factor for the prevalence of COVID-19. However, few studies have focused on whether air pollution affects the efficacy of the SARS-CoV-2 vaccine. To better guide the knowledge surrounding this vaccination, we conducted a cross-section study to identify the relationships between air pollutant exposure and plasma neutralizing antibody (NAb) titers of an inactivated SARS-CoV-2 vaccine (Vero cell, CoronaVac, SINOVΛC, China). We recruited 239 healthcare workers aged 21-50 years who worked at Suining Central Hospital. Of these, 207 were included in this study, depending on vaccination date. The data regarding air pollutants were collected to calculate individual daily exposure dose (DED). The geometric mean of all six pollutant DEDs was applied to estimate the combined toxic effects (DED_complex). Then, the participants were divided into two groups based on the mean value of DED_complex. The median plasma NAb titer was 12.81 AU/mL, with 85.99% vaccine efficacy in healthcare workers against SARS-CoV-2. In exposure group, observations included lower plasma NAb titers (median: 11.13 AU/mL vs. 14.56 AU/mL), more peripheral counts of white blood cells and monocytes (mean: 6.71 × 10⁹/L vs. 6.29 × 10⁹/L and 0.49 × 10⁹/L vs. 0.40 × 10⁹/L, respectively), and a higher peripheral monocyte ratio (7.38% vs. 6.50%) as compared to the reference group. In addition, elevated air pollutant DEDs were associated with decreased plasma NAb titers. To our knowledge, this study is the first to report the relationship between air pollutant exposure and plasma NAb titers of the SARS-CoV-2 vaccine. This suggests that long-term exposure to air pollutants may inhibit plasma NAb expression by inducing chronic inflammation. Therefore, to achieve early herd immunity and hopefully curb the COVID-19 epidemic, vaccinations should be administered promptly to those eligible, and environmental factors should be considered as well.

Probing the biological toxicity of pyrene to the earthworm Eisenia fetida and the toxicity pathways of oxidative damage: A systematic study at the animal and molecular levels

Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca²⁺ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.

Developmental toxicity of lead in rats after gestational exposure and the protective role of taurine

The present study was conducted to investigate the potential adverse effect of Pb on pregnant Sprague-Dawley rats and their fetuses after maternal exposure, on gestational days (GD) 7-16. The possible protective role of taurine (TA), administered throughout the gestation period (GD 1-20) against Pb toxicity, was also evaluated. Pregnant rats were divided into four groups: Group 1 (control) was given distilled water; Group 2 was exposed to Pb (250 ppm) in drinking water (GD 7-16), whereas Group 3 received TA (50 mg/kg/day) by oral gavage (GD 1-20); Group 4 was exposed to Pb (GD 7-16), whereas pretreated with TA from GD 1 till the end of the gestation period. After termination on GD 20, maternal and embryo-fetal outcomes were evaluated. Blood samples were collected for hematological and biochemical parameters assessment. The results showed that, Pb induced a significant reduction in the maternal body weight, weight gain, uterine and placental weight, in addition to a high incidence of abortion and fetal resorption. Meanwhile, fetuses demonstrated decreased body weight and length, with a high rate of mortality as well as external and skeletal abnormalities. Additionally, Pb induced severe hematological and biochemical alterations in both dams and fetuses. The toxicity of Pb was further emphasized by placental histopathological examination and hepatic DNA fragmentation. Pretreatment with TA greatly attenuated the impact of Pb on both maternal and fetal parameters. Moreover, TA alleviated the incidence of placental damage and hepatic DNA fragmentation. The results highlight the potential prophylaxis role of TA against maternal and developmental Pb toxicity.

Gut microbiota of animals living in polluted environments are a potential resource of anticancer molecules

Cancer is a prominent cause of morbidity and mortality worldwide, in spite of advances in therapeutic interventions and supportive care. In 2018 alone, there were 18·1 million new cancer cases and 9·6 million deaths indicating the need for novel anticancer agents. Plant-based products have often been linked with protective effects against communicable and non-communicable diseases. Recently, we have shown that animals such as crocodiles thrive in polluted environments and are often exposed to carcinogenic agents, but still benefit from prolonged lifespan. The protective mechanisms shielding them from cancer could be attributed to the immune system, and/or it is possible that their gut microbiota produce anticancer molecules. In support, several lines of evidence suggest that gut microbiota plays a critical role in the physiology of its host. Here, we reviewed the available literature to assess whether the gut microbiota of animals thriving in polluted environment possess anticancer molecules.

Recent advances in environmentally benign hierarchical inorganic nano-adsorbents for the removal of poisonous metal ions in water: a review with mechanistic insight into toxicity and adsorption

Recent developments in nanoscience and technology have addressed many of the problems associated with water quality. Accordingly, using the technological outputs of the recent research on nanomaterials, the best solution for the purification of water is highlighted in this review. Herein, the main objective is to provide mechanistic insight into the synthesis of various inorganic nanoadsorbents and their adsorption chemistry for poisonous metal ions present in polluted water. Initially, the toxicity and carcinogenicity of As3+, Pb2+, Cr6+, Cd2+, and Hg2+ metal ions are highlighted. For the removal of these toxic ions, this review focuses on eco-friendly nanoadsorbents. The various preparation procedures utilized for the preparation of nanoadsorbents are briefly discussed. Generally, this is because of the adsorption capacity of nanoadsorbents depends on their morphology, shape, size, surface area, surface active sites, functional groups, and quantization effect. Also, due to the importance of their mechanism of action, the recent developments and challenges of novel nanoadsorbents such as metal oxides, core shell nanoparticles, magnetic nano ferrates, and functionalized core shell magnetic oxides and the processes for the treatment of water contaminated by toxic metal ions such as As3+, Pb2+, Cr6+, Cd2+, and Hg2+ are exclusively reviewed. Further, the adsorption efficiency of inorganic nanoadsorbents is also compared with that of activated carbon derived from various sources for all the above-mentioned metal ions.

Anthracene-induced DNA damage and oxidative stress: a combined study at molecular and cellular levels

At present, research progress of anthracene's toxicity lags far behind the pollution caused on its application fields such as petroleum and minerals. In this paper, anthracene-induced oxidative stress effects and genetic toxicity were investigated at both the molecular and cellular levels. The intracellular oxidative stress effect of anthracene on earthworm primary coelomocyte was confirmed by the detection of reactive oxygen species, antioxidant enzymes activity, and malondialdehyde content. Moreover, after anthracene exposure, the decrease in the mitochondrial membrane potential and cell viability also indicated the adverse effects of anthracene on earthworm coelomocyte. The comet assay proved the break in DNA strand, revealing the anthracene-induced DNA damage. On the molecular level, we revealed that anthracene caused the shrinkage of the catalase skeleton and altered the microenvironment of chromophores of catalase by multi-spectral methods. Molecular simulation results indicated that anthracene interacted with His74 by "arene-arene" force and the dominant binding site between anthracene and catalase was close to the active site of catalase. In addition, anthracene was shown to bind to the DNA molecule by groove binding mode. This study proposed a new combined analysis method for the toxicity evaluation of anthracene at the cellular and molecular levels. Graphical abstract This study creatively proposed a new combined analysis for the toxicity evaluation of ANT at the cellular and molecular levels.

In vivo and in vitro studies on inactivation of selenium containing protein- glutathione peroxidase 3 in mice nephrocytes caused by lead

Glutathione peroxidases (Gpxs) play vital roles in elimination of hydroperoxide and other reactive oxygen species through catalyzing reduced glutathione to protect from oxidative stress caused by heavy metals such as lead. Among the family of Gpxs, Gpx3 is the only extracellular enzyme synthesized in the kidney and actively secreted into the plasma. This study investigated mechanisms of lead-induced GPx3 inactivation both at the animal and molecular levels. Six-week-old mice were randomly divided into 4 groups, and exposed to different lead concentrations (0, 1, 2 and 4 g/L) in their drinking water for 4 weeks. Contents of GPx3 in blood serum were tested by enzyme-linked immunosorbent assay (ELISA) and the mRNA levels of Gpx3 in mice nephrocytes were determined by quantitative real-time PCR (qPCR), both of which showed significantly inhibited at higher lead concentrations accompanied by the decreased Gpx3 activities and the elevated levels of malondialdehyde (MDA) in nephrocytes, which indicated that lead could induce strongly oxidative stress through affecting Gpx3 function. So we further investigated molecular mechanisms of GPx3 inactivation caused by lead with multiple spectroscopic techniques, isothermal titration calorimetry (ITC) and molecular docking studies in vitro. Results showed that lead statically quenched GPx3 fluorescence by tightly binding to the structural domain of GPx3 in a 3:1 ratio with high binding affinity (K = 3.1(±0.087) × 10⁷ mol^-1). Further investigation of the conformation of GPx3 by UV-visible spectroscopy and circular dichroism (CD) spectroscopy indicated that lead changed the secondary structure of GPx3 by loosening the GPx3 skeleton and decreasing the hydrophobicity around tryptophan residues. This work proved in vivo and in vitro experiments that lead could induce oxidative stress in mice nephrocytes by interacting with GPx3.

Binding of Fe(ii)-complex of phenanthroline appended glycoconjugate with DNA, plasmid and an agglutinin protein

A phenanthroline appended glycoconjugate and its Fe(ii) complex have been synthesized and characterized thoroughly. The Fe-complex interacts with DNA and WGA protein and alter their structures as studied by spectroscopy and microscopy.

Perfluorodecanoic acid-induced oxidative stress and DNA damage investigated at the cellular and molecular levels

Perfluorodecanoic acid (PFDA) has been widely used in production of many daily necessities because of its special nature. Althoughtoxic effects of PFDA to organisms have been reported, there is little research on the genotoxicity induced by oxidative stress of PFDA on the cellular and molecular levels simultaneously. Thus, we investigated the DNA oxidative damage caused by PFDA in mouse hepatocytes. On the cellular level, an increase in ROS content indicated that PFDA caused oxidative stress in mouse hepatocytes. In addition, after PFDA exposure, the comet assay confirmed DNA strand breaks and an increased 8-OHdG content demonstrated DNA oxidative damage. On the molecular level, the microenvironment of aromatic amino acids, skeleton and secondary structure of catalase (CAT) were varied after PFDA exposure and the enzyme activity was reduced because PFDA bound near the heme groups of CAT. Moreover, PFDA was shown to interact with DNA molecule by groove binding. This study suggests that PFDA can cause genotoxicity by inducing oxidative stress both on the cellular and molecular levels.

Epigenetic modifications associated with pathophysiological effects of lead exposure

Lead (Pb) exposure during different stages of development has demonstrated dose, duration, sex, and tissue-specific pathophysiological outcomes due to altered epigenetic regulation via (a) DNA methylation, (b) histone modifications, (c) miRNAs, and (d) chromatin accessibility. Pb-induced alteration of epigenetic regulation causes neurotoxic and extra-neurotoxic pathophysiological outcomes. Neurotoxic effects of Pb include dysfunction of memory and learning, behavioral disorder, attention deficit hyperactivity disorder, autism spectrum disorder, aging, Alzheimer's disease, tauopathy, and neurodegeneration. Extra-neurotoxic effects of Pb include altered body weight, metabolic disorder, cardiovascular disorders, hematopoietic disorder, and reproductive impairment. Pb exposure either early in life or at any stage of development results in undesirable pathophysiological outcomes that tends to sustain and maintain for a lifetime.

Molecular toxicity of nanoplastics involving in oxidative stress and desoxyribonucleic acid damage

Microplastic pollution attracted extensive attention because of its global presence and adverse effects on ecosystem. However, it is insufficient to clear the effects of nanoplastics on organisms at the molecular level. Herein, a nanopolystyrene (50 nm) was used to examine molecular responses of superoxide dismutase (SOD) and desoxyribonucleic acid (DNA) using spectroscopy (UV-vis, circular dichroism spectra, and fluorescence measurements) and single cell gel electrophoresis methods. Results showed that nanopolystyrene induced oxidative stress, involving in the increase of SOD activity and malondialdehide (MDA) content, and DNA damage because of the significant increase of olive tail moment, head optical density, and tail DNA percentage in the groups at exposure concentrations above 5 × 10^-6  mol/L. The second structural and microenvironment of aromatic amino acids of SOD were changed with nanopolystyrene exposure. The fluorescence of SOD was quenched by nanopolystyrene at exposure concentration above 1 × 10^-5  mol/L, and the quenching mode could be ascribed to the static type. The results and the combined methods are favorable to explore the molecular toxicity of other nanoplastics and the interaction mechanism.

Molecular mechanisms of lead-induced changes of selenium status in mice livers through interacting with selenoprotein P

As a heavy metal generally considered to be toxic, lead displays the destruction of the antioxidant system and causes oxidative damage through animal, cellular and molecular evidences. Selenium exists in the form of selenocysteine (Sec) upon its incorporation into selenoproteins and plays vital roles in protection from oxidative stress caused by toxic materials such as lead. This study investigated mechanisms of lead-induced changes of selenium status both at the animal and molecular levels. Total selenium concentrations in blood plasma, contents of glutathione peroxidase 3 (Gpx3) and selenoprotein P (SelP) in blood plasma and mRNA levels of key selenoproteins in mice livers were significantly inhibited after lead exposure, and indicators of oxidative damages in mice livers caused by lead also presented significantly higher, including levels of reactive oxygen species, malonaldehyde concentration and TNF-α levels. To further confirm the hypothesis that lead may disturb selenium status through affecting SelP function, we investigated molecular mechanisms of lead on SelP in vitro. Results indicated that lead changed secondary structure of SelP by loosening and destruction its skeleton. This work presents molecular mechanisms changes of selenium status in mice livers caused by lead combined in vivo and in vitro studies, and contributes to a better understanding of lead toxicity on human health.

Lead Induces Genotoxicity via Oxidative Stress and Promoter Methylation of DNA Repair Genes in Human Lymphoblastoid TK6 Cells

Background

Lead (Pb) is a widely used metal in modern industry and is regarded as a health hazard. Although lead-induced genotoxicity has been confirmed, the direct evidence that lead induces genotoxicity in human cells and its related mechanisms has not been fully elucidated. In this study, for the first time, we evaluated the genotoxicity induced by lead in human lymphoblastoid TK6 cells.

Material/Methods

The TK6 cells were incubated with various concentrations of Pb(Ac)₂ for 6 h, 12 h, or 24 h. Cell viability was detected by CCK8 assay. Various biochemical markers were assessed by specific kits. Immunofluorescence assay was used to detect γ-H2AX foci formation. The promoter methylation was assessed by methylation-specific PCR. The protein levels were determined by Western blot assay.

Results

The results showed that after exposure to lead, cell viability was obviously decreased and γ-H2AX foci formation was significantly enhanced in TK6 cells. Moreover, the levels of 8-OHdG, ROS, MDA, and GSSG were increased, while the GSH level and SOD activity were decreased in lead-treated TK6 cells. The activation of the Nrf2-ARE signaling pathway was involved in lead-induced oxidative stress in TK6 cells. Finally, the expressions of DNA repair genes XRCC1, hOGG-1, BRCA1, and XPD were inhibited via enhancing their promoter methylation in TK6 cells after exposure to lead.

Conclusions

Taken together, our study provides the first published evidence that lead exposure results in DNA damage via promoting oxidative stress and the promoter methylation of DNA repair genes in human lymphoblastoid TK6 cells.

Nuclear receptor and VEGF pathways for gene-blood lead interactions, on bone mineral density, in Korean smokers

Osteoporosis has a complex etiology and is considered a multifactorial polygenic disease, in which genetic determinants are modulated by hormonal, lifestyle, environmental, and nutritional factors. Therefore, investigating these multiple factors, and the interactions between them, might lead to a better understanding of osteoporosis pathogenesis, and possible therapeutic interventions. The objective of this study was to identify the relationship between three blood metals (Pb, Cd, and Al), in smoking and nonsmoking patients' sera, and prevalence of osteoporosis. In particular, we focused on gene-environment interactions of metal exposure, including a dataset obtained through genome-wide association study (GWAS). Subsequently, we conducted a pathway-based analysis, using a GWAS dataset, to elucidate how metal exposure influences susceptibility to osteoporosis. In this study, we evaluated blood metal exposures for estimating the prevalence of osteoporosis in 443 participants (aged 53.24 ± 8.29), from the Republic of Korea. Those analyses revealed a negative association between lead blood levels and bone mineral density in current smokers (p trend <0.01). By further using GWAS-based pathway analysis, we found nuclear receptor (FDR<0.05) and VEGF pathways (FDR<0.05) to be significantly upregulated by blood lead burden, with regard to the prevalence of osteoporosis, in current smokers. These findings suggest that the intracellular pathways of angiogenesis and nuclear hormonal signaling can modulate interactions between lead exposure and genetic variation, with regard to susceptibility to diminished bone mineral density. Our findings may provide new leads for understanding the mechanisms underlying the development of osteoporosis, including possible interventions.

Advances in Understanding How Heavy Metal Pollution Triggers Gastric Cancer

With the development of industrialization and urbanization, heavy metals contamination has become a major environmental problem. Numerous investigations have revealed an association between heavy metal exposure and the incidence and mortality of gastric cancer. The mechanisms of heavy metals (lead, cadmium, mercury, chromium, and arsenic) contamination leading to gastric cancer are concluded in this review. There are four main potential mechanisms: (1) Heavy metals disrupt the gastric mucosal barrier by decreasing mucosal thickness, mucus content, and basal acid output, thereby affecting the function of E-cadherin and inducing reactive oxygen species (ROS) damage. (2) Heavy metals directly or indirectly induce ROS generation and cause gastric mucosal and DNA lesions, which subsequently alter gene regulation, signal transduction, and cell growth, ultimately leading to carcinogenesis. Exposure to heavy metals also enhances gastric cancer cell invasion and metastasis. (3) Heavy metals inhibit DNA damage repair or cause inefficient lesion repair. (4) Heavy metals may induce other gene abnormalities. In addition, heavy metals can induce the expression of proinflammatory chemokine interleukin-8 (IL-8) and microRNAs, which promotes tumorigenesis. The present review is an effort to underline the human health problem caused by heavy metal with recent development in order to garner a broader perspective.

Quality decline and oxidative damage in sperm of freshwater crab Sinopotamon henanense exposed to lead

Lead (Pb) induces male infertility in vertebrates. Whether lead is related to reproductive abnormalities in aquatic invertebrates remains uncertain. In this work, effects of Pb on the sperm quality and oxidative stress of the freshwater crab Sinopotamon henanense were investigated after 3, 5 and 7d exposure to different Pb concentrations (0, 3.675, 7.35, 14.7, 29.4 and 58.8mg/L). Sperm quality indices including sperm plasma-membrane integrity and acrosomal-membrane integrity were measured by flow cytometry. DNA integrity was measured by fluorescence microscopy. The results showed that Pb levels in sperm increased significantly upon Pb exposure in most treated groups, sperm plasma-membrane integrity, acrosomal-membrane integrity, and DNA integrity were reduced at higher concentrations after 5 d and 7d. Oxidative stress of sperm induced by Pb was reflected in significant up-regulation of reactive oxygen species (ROS) levels after 3, 5 and 7d. A significant reduction of the total antioxidant capacity levels occurred after exposure to 14.7mg/L Pb and above at 7d compared to the control. The results of oxidative damage to lipids, proteins and DNA of sperm showed that malondialdehyde, protein carbonylation and DNA-protein crosslinks were increased in a concentration- and time-dependent manner. Our findings document that Pb can induce harmful effects on several reproductive endpoints in a freshwater crab.

Oxidative damage induced by copper in mouse primary hepatocytes by single-cell analysis

Copper can disturb the intracellular redox balance, induce oxidative stress, and subsequently cause irreversible damage, leading to a variety of diseases. In the present study, mouse primary hepatocytes were chosen to elucidate the in vitro oxidative damage of short-term copper exposure (10-200 μM) by single-cell analysis. We evaluated the toxicity of copper by reactive oxygen species (ROS), glutathione (GSH), and oxidative DNA damage at the single-cell level. Oxidative damage induced by copper was verified by the morphological changes, persistent elevations of excessive ROS and malondialdehyde (MDA), a decrease in GSH level, and the oxidative DNA damage. Furthermore, the average ROS generation, GSH consumption, and the indicators in DNA damage did not significantly change at relatively low concentrations (10 or 50 μM), but we can find the alterations of parameters in some single cells clearly. Emphasis on the analysis of single cells is conducive to gain a better understanding on the toxicity of copper. This study will also complement studies on the environmental risk assessment of copper pollution.

Effects of Lead on Ultrastructure of Isoetes sinensis Palmer (Isoetaceae), a Critically Endangered Species in China

Isoetes sinensis Palmer (Isoetaceae) is a critically endangered fern that is a marsh plant (that is an aquatic or amphibious plant) in China. To evaluate damage or influence of lead (Pb) on cell ultrastructure in I. sinensis, we used 2000mg·L^-1 Pb(NO₃)₂ solution to treat I. sinensis for 35d, and used transmission electron microscope (TEM) to observe the cell ultrastructure of leaf blades and roots of the plant. Our results indicated that Pb induced distinct changes of the organelles including chloroplast, mitochondria, nucleolus and vacuole. The level of damage organ was lower leaf > upper leaf > root The typical performance of the damages caused by lead shown that part of the nucleolus cracked; the cristae dilated, matrix vacuolized and membrane structure blurred in mitochondria; the vacuole cracked; grana lamella decreased, stroma lamella loosed, starch grains decreased, and membrane structure was disrupted in chloroplasts; Pb deposits were present on cell wall. The damages to chloroplasts and mitochondria were relatively severe, while damage to the nucleus was relatively lighter. The damage to the cell ultrastructure of leaf blades with direct contact with Pb was more severe than that without direct contact with Pb.

Mitochondrial Redox Dysfunction and Environmental Exposures

SIGNIFICANCE

Mitochondria are structurally and biochemically diverse, even within a single type of cell. Protein complexes localized to the inner mitochondrial membrane synthesize ATP by coupling electron transport and oxidative phosphorylation. The organelles produce reactive oxygen species (ROS) from mitochondrial oxygen and ROS can, in turn, alter the function and expression of proteins used for aerobic respiration by post-translational and transcriptional regulation.

RECENT ADVANCES

New interest is emerging not only into the roles of mitochondria in disease development and progression but also as a target for environmental toxicants.

CRITICAL ISSUES

Dysregulation of respiration has been linked to cell death and is a major contributor to acute neuronal trauma, peripheral diseases, as well as chronic neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease.

FUTURE DIRECTIONS

Here, we discuss the mechanisms underlying the sensitivity of the mitochondrial respiratory complexes to redox modulation, as well as examine the effects of environmental contaminants that have well-characterized mitochondrial toxicity. The contaminants discussed in this review are some of the most prevalent and potent environmental contaminants that have been linked to neurological dysfunction, altered cellular respiration, and oxidation.

Cadmium induced apoptosis in mouse primary hepatocytes: the role of oxidative stress-mediated ERK pathway activation and the involvement of histone H3 phosphorylation

Time-delayed apoptosis induced by cadmium in primary hepatocytes through DNA damage, histone modification and ERK signaling cascade, which are all mediated by oxidative stress.

Probing the interactions between carboxylated multi-walled carbon nanotubes and copper-zinc superoxide dismutase at a molecular level

In order to evaluate the toxicity of multi-walled carbon nanotubes (MWCNTs-COOH) at a molecular level, the effect of MWCNTs-COOH on antioxidant enzyme copper-zinc superoxide dismutase (Cu/ZnSOD) was investigated using fluorescence spectroscopy, UV/vis absorption spectroscopy, circular dichroism (CD) spectroscopy and isothermal titration calorimetry (ITC). By deducting the inner filter effect (IFE), the fluorescence emission spectra and synchronous fluorescence spectra indicated that there were interactions between MWCNTs-COOH and Cu/ZnSOD. Moreover, the microenvironment of the amino acid residues in the enzyme was changed slightly. The UV/vis absorption and CD spectroscopic results showed appreciable conformational changes in Cu/ZnSOD. However, the results of a Cu/ZnSOD activity determination did not show any significant difference. In other words, MWCNTs-COOH has no significant effect on enzyme activity. The ITC results showed that the binding of MWCNTs-COOH to Cu/ZnSOD was a weak endothermic process, indicating that the predominant force of the binding was hydrophobic interaction. Moreover, it was essential to consider the IFE in fluorescence assays, which might affect the accuracy and precision of the results. The above results are helpful in evaluating the oxidative stress induced by MWCNTs-COOH in vivo.

Binding mode investigations on the interaction of lead(II) acetate with human chorionic gonadotropin

Lead exposure could induce endocrine disruption and hormonal imbalance of humans, resulting in detrimental effects on the reproductive system even at low doses. However, mechanisms of lead actions remain unknown. This article investigated lead interactions with human chorionic gonadotropin (HCG) as a conceivable mechanism of its reproductive toxicity by spectroscopic technique, isothermal titration calorimetry (ITC), molecular docking study, and enzyme-linked immunosorbent assay (ELISA). Fluorescence measurements showed that lead acetate dynamically quenched intrinsic fluorescence of HCG through collisional mechanism with the association constant (KSV) in the magnitude of 10(3) L/mol at the detected temperatures (298, 303, and 310 K). ITC and molecular docking results revealed lead acetate could bind into 5 binding sites of HCG through electrostatic effects (ΔH < 0, ΔS > 0) and hydrophobic forces (ΔH > 0, ΔS > 0). The conformational investigation of HCG by UV-vis absorption spectroscopy, circular dichroism spectroscopy, and ELISA indicated lead acetate changed the secondary structure of HCG by loosening and destruction of HCG skeleton and increasing the hydrophobicity around Tyr residues and resulted in the decreased bioactivities of HCG. This work presents direct interactions of lead with sex hormones and obtains a possible mechanism on lead induced reproductive toxicity at the molecular level.