Research directives toward deciphering adverse outcome pathways induced by environmental metallotoxins

An exposome connectivity paradigm for the mechanistic assessment of the effects of prenatal and early life exposure to metals on neurodevelopment

The exposome paradigm through an integrated approach to investigating the impact of perinatal exposure to metals on child neurodevelopment in two cohorts carried out in Slovenia (PHIME cohort) and Greece (HERACLES cohort) respectively, is presented herein. Heavy metals are well-known neurotoxicants with well-established links to impaired neurodevelopment. The links between in utero and early-life exposure to metals, metabolic pathway dysregulation, and neurodevelopmental disorders were drawn through urinary and plasma untargeted metabolomics analysis, followed by the combined application of in silico and biostatistical methods. Heavy metal prenatal and postnatal exposure was evaluated, including parameters indirectly related to exposure and health adversities, such as sociodemographic and anthropometric parameters and dietary factors. The primary outcome of the study was that the identified perturbations related to the TCA cycle are mainly associated with impaired mitochondrial respiration, which is detrimental to cellular homeostasis and functionality; this is further potentiated by the capacity of heavy metals to induce oxidative stress. Insufficient production of energy from the mitochondria during the perinatal period is associated with developmental disorders in children. The HERACLES cohort included more detailed data regarding diet and sociodemographic status of the studied population, allowing the identification of a broader spectrum of effect modifiers, such as the beneficial role of a diet rich in antioxidants such as lycopene and ω-3 fatty acids, the negative effect the consumption of food items such as pork and chicken meat has or the multiple impacts of fish consumption. Beyond diet, several other factors have been proven influential for child neurodevelopment, such as the proximity to pollution sources (e.g., waste treatment site) and the broader living environment, including socioeconomic and demographic characteristics. Overall, our results demonstrate the utility of exposome-wide association studies (EWAS) toward understanding the relationships among the multiple factors that determine human exposure and the underlying biology, reflected as omics markers of effect on neurodevelopment during childhood.

Urinary metals, arsenic, and polycyclic aromatic hydrocarbon exposure and risk of chronic bronchitis in the US adult population

Metals, arsenic, and polycyclic aromatic hydrocarbons (PAHs) have all been linked to respiratory diseases. Chronic bronchitis, which is a form of chronic obstructive pulmonary disease (COPD), is a major public health concern and source of morbidity and mortality in the US. The purpose of this study was to analyze the correlation of 14 urinary metals (antimony, barium, cadmium, cesium, cobalt, lead, manganese, mercury, molybdenum, strontium, thallium, tin, tungsten, uranium), seven species of arsenic, and seven forms of polycyclic aromatic hydrocarbon (PAH) concentrations and chronic bronchitis in the US population. A cross-sectional analysis using three datasets from the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2016 in adults, aged 20 years and older. Chronic bronchitis was determined using a self-questionnaire from the NHANES dataset. A specialized weighted complex survey design analysis package was used to analyze NHANES data. Multivariate logistic regression models were used to determine the correlation between urinary metals, arsenic, PAHs, and chronic bronchitis. Models were adjusted for lifestyle and demographic factors. A total of 4186 participants were analyzed; 49.8% were female and 40.5% were non-Hispanic White. All seven types of PAHs showed a positive association with chronic bronchitis (1-hydroxynaphthalene odds ratio (OR): 1.559, 95% confidence interval (CI): 1.271-1.912; 2-hydroxynaphthalene OR: 2.498, 95% CI: 1.524-4.095; 3-hydroxyfluorene OR: 2.752, 95% CI: 2.100-3.608; 2-hydroxyfluorene OR: 3.461, 95% CI: 2.438-4.914; 1-hydroxyphenanthrene OR: 2.442, 95% CI: 1.515-3.937; 1-hydroxypyrene OR: 2.828, 95% CI: 1.728-4.629; 2 & 3-hydroxyphenanthrene OR: 3.690, 95% CI: 2.309-5.896). Of the metals, only urinary cadmium showed a statistically significant positive association (OR: 2.435, 95% CI: 1.401-4.235) with chronic bronchitis. No other metals or arsenic were correlated with chronic bronchitis. Seven forms of urinary PAHs, cadmium, and several demographic factors were associated with chronic bronchitis.

Neurodevelopmental exposome: The effect of in utero co-exposure to heavy metals and phthalates on child neurodevelopment

In this study, the exposome paradigm has been applied on a mother-child cohort adopting an optimised untargeted metabolomics approach for human urine followed by advanced bioinformatics analysis. Exposome-wide association algorithms were used to draw links between in utero co-exposure to metals and phthalates, metabolic pathways deregulation, and clinically observed phenotypes of neurodevelopmental disorders such as problems in linguistic, motor development and cognitive capacity. Children (n = 148) were tested at the first and second year of their life using the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Their mothers had been exposed to metals and phthalates during the pregnancy, according to human biomonitoring results from previously performed studies. Untargeted metabolomics analysis of biobanked urine samples from the mothers was performed using a combination of the high throughput analytical methods liquid chromatography-high resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance (NMR). Most perturbed metabolic pathways from co-exposure heavy metals and phthalates were pathways related to the tricarboxylic acid cycle (TCA cycle) and oxidative phosphorylation, indicating the possibility of disruption of mitochondrial respiration. Overproduction of reactive oxygen species (ROS); the presence of glutathione peroxidase 3 (GPx3) during pregnancy and presence of glutathione peroxidase 1 (GPx1) in the umbilical cord were linked to verbal development problems. Another finding of the study is that in real life, adverse outcomes occur as a combination of environmental and social factors, all of them acting synergistically towards the deployment of an observed phenotype. Finally, the two-steps association process (exposure to pathways and pathways to adverse outcomes) was able to (a) provide associations that are not evident by directly associating exposure to outcomes and (b) provides additional insides on the mechanisms of environmental disease.

Multi-omics analysis reveals that co-exposure to phthalates and metals disturbs urea cycle and choline metabolism

This study aimed to evaluate the response of HepaRG cells after co-exposure to phthalates and heavy metals, using a high-dimensional biology paradigm (HDB). Liver is the main metabolism site for the majority of xenobiotics. For this reason, the HepaRG cell line was used as an in vitro model, and cells were exposed to two characteristic mixtures of phthalates and heavy metals containing phthalates (DEHP, DiNP, BBzP) and metals (lead, methylmercury, total mercury) in a concentration-dependent manner. The applied chemical mixtures were selected as the most abundant pollutants in the REPRO_PL and PHIME cohorts, which were studied using the exposome-wide approach in the frame of the EU project HEALS. These studies investigated the environmental causation of neurodevelopmental disorders in neonates and across Europe. The INTEGRA computational platform was used for the calculation of the effective concentrations of the chemicals in the liver through extrapolation from human biomonitoring data and this dose (and a ten-times higher one) was applied to the hepatocyte model. Multi-omics analysis was performed to reveal the genes, proteins, and metabolites affected by the exposure to these chemical mixtures. By extension, we could detect the perturbed metabolic pathways. The generated data were analyzed using advanced bioinformatic tools following the HEALS connectivity paradigm for multi-omics pathway analysis. Co-mapped transcriptomics and proteomics data showed that co-exposure to phthalates and heavy metals leads to perturbations of the urea cycle due to differential expression levels of arginase-1 and -2, argininosuccinate synthase, carbamoyl-phosphate synthase, ornithine carbamoyltransferase, and argininosuccinate lyase. Joint pathway analysis of proteomics and metabolomics data revealed that the detected proteins and metabolites, choline phosphate cytidylyltransferase A, phospholipase D3, group XIIA secretory phospholipase A2, α-phosphatidylcholine, and the a 1,2-diacyl-sn-glycero-3-phosphocholine, are responsible for the homeostasis of the metabolic pathways phosphatidylcholine biosynthesis I, and phospholipases metabolism. The urea, phosphatidylcholine biosynthesis I and phospholipase metabolic pathways are of particular interest since they have been identified also in human samples from the REPRO_PL and PHIME cohorts using untargeted metabolomics analysis and have been associated with impaired psychomotor development in children at the age of two. In conclusion, this study provides the mechanistic evidence that co-exposure to phthalates and metals disturb biochemical processes related to mitochondrial respiration during critical developmental stages, which are clinically linked to neurodevelopmental perturbations.

Toxic metal exposure as a possible risk factor for COVID-19 and other respiratory infectious diseases

Multiple medical, lifestyle, and environmental conditions, including smoking and particulate pollution, have been considered as risk factors for COronaVIrus Disease 2019 (COVID-19) susceptibility and severity. Taking into account the high level of toxic metals in both particulate matter (PM2.5) and tobacco smoke, the objective of this review is to discuss recent data on the role of heavy metal exposure in development of respiratory dysfunction, immunotoxicity, and severity of viral diseases in epidemiological and experimental studies, as to demonstrate the potential crossroads between heavy metal exposure and COVID-19 severity risk. The existing data demonstrate that As, Cd, Hg, and Pb exposure is associated with respiratory dysfunction and respiratory diseases (COPD, bronchitis). These observations corroborate laboratory findings on the role of heavy metal exposure in impaired mucociliary clearance, reduced barrier function, airway inflammation, oxidative stress, and apoptosis. The association between heavy metal exposure and severity of viral diseases, including influenza and respiratory syncytial virus has been also demonstrated. The latter may be considered a consequence of adverse effects of metal exposure on adaptive immunity. Therefore, reduction of toxic metal exposure may be considered as a potential tool for reducing susceptibility and severity of viral diseases affecting the respiratory system, including COVID-19.

High blood lead levels are associated with lead concentrations in households and day care centers attended by Brazilian preschool children

BACKGROUND

A previous study observed high blood lead levels (BLL) in preschool children attending 50 day care centers (DCC) in São Paulo, Brazil.

OBJECTIVE

To identify whether lead levels found in both homes and DCC environments are associated with high blood lead levels.

METHODS

Children attending 4 DCCs, quoted here as NR, VA, PS and PF, were divided into two groups according to BLL: high exposure (HE: ≥13.9 μg/dL; 97.5 percentile of the 2013 year sample) and low exposure (LE: <5 μg/dL). For in situ lead measurements (lead paint mode: mg/cm² and ROHS mode: μg/g) in the children's households and in the DCC environments, a field portable X-ray-fluorescence analyzer was used. Multiple logistic regressions were performed to control for confounding factors. Odds ratios were adjusted for age, sex, day care center's measured lead, and tobacco.

RESULTS

In an NR DCC building, 33.8% of the measurements had lead levels >600 μg/g, whereas such levels were observed in 77.1% of NR playground measurements. In VA DCC, 22% and 23% of the measurements in the building and in the playgrounds had levels higher than 600 μg/g, respectively. The percentage of high lead levels in the children's houses of the LE group was 5.9% (95% CI: 4.3-7.6%) and 13.2 (95% CI: 8.3-18.0%) in the HE group. Moreover, a significant association was found between high BLLs and lead levels found both in households and DCCs (p < 0.001). Most of the high lead measurements were found in tiles and playground equipment.

CONCLUSIONS

Lead exposure estimated from the DCCs, where children spend about 10 h/day, can be as relevant as their household exposure. Therefore, public authorities should render efforts to provide a rigorous surveillance for lead-free painting supplies and for all objects offered to children.

Human biomonitoring data analysis for metals in an Italian adolescents cohort: An exposome approach

The first Italian human biomonitoring survey (PROBE - PROgramme for Biomonitoring general population Exposure) considered a reference population of adolescents, aged 13-15 years, living in urban and rural areas and investigated their exposure to metals. The study was expanded up to 453 adolescents living in the same areas of Latium Region (Italy) and blood samples were analyzed for 19 metals (As, Be, Cd, Co, Cr, Hg, Ir, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Sb, Sn, Tl, V, and W) by sector field inductively coupled plasma mass spectrometry. The exposure assessment was contextualized following an exposome approach that considered several determinants related to the subjects, available environmental parameters and geo-coding of residence address. To assess the influence of exposure determinants and modifiers on children biomarkers levels we used two independent methodologies. The first makes use of the so-called Environment-Wide Association Study (EWAS) methodology while the second was based on the application of a Generalized Liner Model (GLM) capturing co-exposures to pairs of key determinants. Based on our analysis, Hg and As were positively associated with dietary pathways (primarily linked to fish and to a lesser extent to milk consumption) while Cr showed a more complex interaction between co-exposure to different dietary pathways (milk and fish) coupled to proximity of residence to industrial activities. In addition to diet, socio-economic status of the mother revealed robust statistical associations with Cd, Ni and W biomonitoring levels in the respective children.

Synthetic endeavors on cadmium species bearing glycolate and aromatic chelators with structure-specific biotoxic correlations in vitro

Cadmium is a well-known metallotoxin widespread in the environment and easily reaching cellular targets in lower and higher organisms, including humans. The form(s) of that metal ion through which it interacts with biomolecular targets in a cellular milieu are critical in cell survival. Poised to investigate the structure-specific activity of Cd(II) in a cellular environment and delve into the associated biotoxic processes, binary and ternary systems of that metal ion in the presence of the physiological α-hydroxycarboxylic acid glycolic acid and aromatic (N,N')-binders 2,2'-bipyridine (2,2'-bipy) and 4,4'-bipyridine (4,4'-bipy) were examined synthetically in aqueous media and a pH-specific fashion. The arising new materials [Cd(C₂H₃O₃)₂]_n (1), [Cd(C₂H₃O₃)(C₁₀H₈N₂)(NO₃)]_n·nH₂O (2), and {[Cd(C₂H₃O₃)(C₁₀H₈N₂)(H₂O)](NO₃)}_n·2nH₂O (3) project coordination polymers, which were physicochemically characterized through elemental analysis, FT-IR, NMR, luminescence and X-ray crystallography. The distinct spectroscopic features of 1-3, with luminescence exemplifying distinct behavior (2,3), further corroborated by crystallographic analysis, lend credence to a structure-specific selection of species employed in ensuing in vitro biological studies. The emerging results in two different cell lines (3T3-L1, Saos-2) reveal a concentration-dependent, structure-specific and cell line-specific toxicity profile of Cd(II), reflecting its coordination composition and formulation, rendering it soluble and bioavailable (1,2). Mechanistic information riding on caspase-dependent investigation unravels that metal ion's specific behavior compromising cell survival and integrity. Employment of ethylenediamine tetraacetic acid (EDTA) a) shows efficient sequestration of Cd(II) away from its toxic reactivity denoting the strength of interactions involved, and b) lends credence to further development of appropriately configured organic binders, selectively providing molecular protection from Cd(II) toxicity.