A combination of metallomics and metabolomics studies to evaluate the effects of metal interactions in mammals. Application to Mus musculus mice under arsenic/cadmium exposure

Recent developments in speciation and determination of arsenic in marine organisms using different analytical techniques. A review

Marine organisms play a vital role as the main providers of essential and functional food. Yet they also constitute the primary pathway through which humans are exposed to total arsenic (As) in their diets. Since it is well known that the toxicity of this metalloid ultimately depends on its chemical forms, speciation in As is an important issue. Most relevant articles about arsenic speciation have been investigated. This extended not only from general knowledge about As but also the toxicity and health related issues resulting from exposure to these As species from the food ecosystem. There can be enormous side effects originating from exposure to As species that must be measured quantitatively. Therefore, various convenient approaches have been developed to identify different species of As in marine samples. Different extraction strategies have been utilized based on the As species of interest including water, methanol and mixtures of both, and many other extraction agents have been explained in this article. Furthermore, details of hyphenated techniques which are available for detecting these As species have been documented, especially the most versatile and applied technique including inductively coupled plasma mass spectrometry.

Transcriptional and biochemical changes in mouse liver following exposure to a metal/drug cocktail. Attenuating effect of a selenium-enriched diet

Real-life pollution usually involves simultaneous co-exposure to different chemicals. Metals and drugs are frequently and abundantly released into the environment, where they interact and bioaccumulate. Few studies analyze potential interactions between metals and pharmaceuticals in these mixtures, although their joint effects cannot be inferred from their individual properties. We have previously demonstrated that the mixture (PC) of the metals Cd and Hg, the metalloid As and the pharmaceuticals diclofenac (DCF) and flumequine (FLQ) impairs hepatic proteostasis. To gain a deeper vision of how PC affects mouse liver homeostasis, we evaluated here the effects of PC exposure upon some biochemical and morphometric parameters, and on the transcriptional profiles of selected group of genes. We found that exposure to PC caused oxidative damage that exceeded the antioxidant capacity of cells. The excessive oxidative stress response resulted in an overabundance of reducing equivalents, which hindered the metabolism and transport of metabolites, including cholesterol and bile acids, between organs. These processes have been linked to metabolic and inflammatory disorders, cancer, and neurodegenerative diseases. Therefore, our findings suggest that unintended exposure to mixtures of environmental pollutants may underlie the etiology of many human diseases. Fortunately, we also found that a diet enriched with selenium mitigated the harmful effects of this combination of toxicants.

Gut-gonad crosstalk in mice exposed to a "chemical cocktail" combining metabolomics and microbial profile by amplicon sequencing

Testes are very prone to be damaged by environmental pollutants, but there is a lack of information about the impact of "chemical cocktails" (CC) on the testicular metabolome and the possible influence in the gut-gonad crosstalk. For this, BALB/c mice were given flumequine and diclofenac orally in food and potentially toxic trace elements (Cd, Hg, As) in drinking water. A mice group was supplemented with selenium, a well-known antagonist against many pollutants. Our results revealed that the steroid 5-alpha-androstan-17-beta-ol propionate, suggested as a parameter of androgenicity independent of testosterone levels, proline that improves reproductive indicators in male rabbits affected by environmental stress) among others metabolites are only present after CC exposure with rodent and selenium supplemented diet. Selenium also antagonized the up-or down-regulation of anandamide (20:l, n-9) (p < 0.001 and FC 0.54 of CC vs C but p > 0,05 and FC 0.74 of CC-Se vs C), that regulates gonadotropin-releasing hormones in mammals, 2,3-dinor-11b-PGF2a (p < 0.001 and FC 0.12 of CC vs C but p > 0,05 and FC 0.34 of CC-Se vs C), which has been related with reproductive hormones, besides others testicular metabolites altered by the exposure to the CC and reversed the levels to control. Moreover, numerous significant associations between gut microbes and testicular metabolites indicated a possible impact of pollutants in the testes mediated by gut microbiota due to a gut-gonad crosstalk.

Study on the mechanism of arsenic-induced renal injury based on SWATH proteomics technology

BACKGROUND

Arsenic (As) poisoning is a worldwide endemic disease affecting thousands of people. As is excreted mainly through the renal system, and arsenic has toxic effects on the kidneys, but the mechanism has not been elucidated. In this study, the molecular basis of arsenic's nephrotoxicity was studied by using a high-throughput proteomics technique.

METHODS

Eight SD (Sprague-Dawley) rats, half male and half female, were fed an As diet containing 50 mg/kg NaAsO2. Age- and sex-matched rats fed with regular chow were used as controls. At the end of the experiment (90 days), kidney tissue samples were collected and assessed for pathological changes using hematoxylin-eosin staining. Proteomic methods were used to identify alterations in protein expression levels in kidney tissues, and bioinformatic analyses of differentially expressed proteins between arsenic-treated and control groups were performed. The expression of some representative proteins was validated by Western blot analysis.

RESULTS

NaAsO2 could induce renal injury. Compared with the control group, 112 proteins were up-regulated, and 46 proteins were down-regulated in the arsenic-treated group. These proteins were associated with the electron transport chain, oxidative phosphorylation, mitochondrial membrane, apoptosis, and proximal tubules, suggesting that the mechanisms associated with them were related to arsenic-induced kidney injury and nephrotoxicity. The expressions of Atp6v1f, Cycs and Ndufs1 were verified, consistent with the results of omics.

CONCLUSION

These results provide important evidence for arsenic-induced kidney injury and provide new insights into the molecular mechanism of arsenic-induced kidney injury.

Omics insights into the responses to dietary selenium

Selenium is a well-known health-relevant element related with cancer chemoprevention, neuroprotective roles, beneficial in diabetes, and in several infectious diseases, among others. It is naturally present in some foods, but deficiency in people led to the production of nutraceuticals, supplements, and functional food enriched in this element. There is a U-shaped link between selenium levels and health and a narrow range between toxic and essential levels, and thus, supplementation should be performed carefully. Omics methodologies have become valuable approaches to delve into the responses of dietary selenium in mammals that allowed a deeper knowledge about the metabolism of this element as well as its biological role. In this review, we discuss omics approaches from the workflows to their applications that has been previously used to deep insight into the metabolism of dietary selenium. There is a special focus on selenoproteins, metabolomics responses in blood and tissues (e.g., brain, reproductive organs, etc.) as well as the impact on gut microbiota and its metabolites profile. Thus, we mainly reviewed heteroatom-tagged proteomics, metallomics, metabolomics, and metataxonomics, usually combined with transcriptomics, genomics, and other molecular methods.

Toxicity, arsenic speciation and characteristics of hyphenated techniques used for arsenic determination in vegetables. A review

Arsenic (As) speciation is an interesting topic because it is well recognized that the toxicity of this metalloid ultimately depends on its chemical form. More than 300 arsenicals exist naturally. However, As can be present in four oxidation states: As-III, As0, AsIII and AsV. Long-term exposure to As from different sources, such as anthropogenic processes, or water, fauna and flora contaminated with As, has put human health at risk for decades. There are many side-effects correlated with exposure to InAs species, such as skin problems, respiratory diseases, kidney problems, cardiovascular diseases and even cancer. There are different levels and types of As in foods, particularly in vegetables. Furthermore, different chemical methods and techniques have been developed. Therefore, this review focuses on the general properties of various approaches used to identify As species in vegetation samples published worldwide. This includes various approaches (different solvents and techniques) used to extract As species from the matrix. Then, versatile chromatographic and non-chromatographic systems to separate different forms of As are reviewed. Finally, the general properties of the most common instruments used to detect As species from samples of interest are listed.

Metabolic Changes and Their Associations with Selected Nutrients Intake in the Group of Workers Exposed to Arsenic

Arsenic (As) exposure causes numerous adverse health effects, which can be reduced by the nutrients involved in the metabolism of iAs (inorganic As). This study was carried out on two groups of copper-smelting workers: WN, workers with a urinary total arsenic (tAs) concentration within the norm (n = 75), and WH, workers with a urinary tAs concentration above the norm (n = 41). This study aimed to analyze the association between the intake level of the nutrients involved in iAs metabolism and the signal intensity of the metabolites that were affected by iAs exposure. An untargeted metabolomics analysis was carried out on urine samples using liquid chromatography-mass spectrometry, and the intake of the nutrients was analyzed based on 3-day dietary records. Compared with the WN group, five pathways (the metabolism of amino acids, carbohydrates, glycans, vitamins, and nucleotides) with twenty-five putatively annotated metabolites were found to be increased in the WH group. In the WN group, the intake of nutrients (methionine; vitamins B2, B6, and B12; folate; and zinc) was negatively associated with six metabolites (cytosine, D-glucuronic acid, N-acetyl-D-glucosamine, pyroglutamic acid, uridine, and urocanic acid), whereas in the WH group, it was associated with five metabolites (D-glucuronic acid, L-glutamic acid, N-acetyl-D-glucosamine, N-acetylneuraminic acid, and uridine). Furthermore, in the WH group, positive associations between methionine, folate, and zinc intake and the signal intensity of succinic acid and 3-mercaptolactic acid were observed. These results highlight the need to educate the participants about the intake level of the nutrients involved in iAs metabolism and may contribute to further considerations with respect to the formulation of dietary recommendations for people exposed to iAs.

Ionomics and metabolomics analysis reveal the molecular mechanism of metal tolerance of Pteris vittata L. dominating in a mining site in Thai Nguyen province, Vietnam

This study aims to find the interaction between ionome and metabolome profiles of Pteris vittata L., an arsenic hyperaccumulator plant, to reveal its metal tolerance mechanism. Therefore, at the Pb-Zn mining sites located in Thai Nguyen province, Vietnam, where these species dominate, soil and plant samples were collected. Their multi-element compositions were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) and thus referred to as the "ionomics" approach. In parallel, the widely targeted metabolomics profiles of these plant samples were performed using liquid chromatography-tandem mass spectrometry (UPLC-QqQ-MS). Nineteen elements, including both metals and nonmetals, were detected and quantified in both tissues of thirty-five plant individuals. A comparison of these elements' levels in two tissues showed that above-ground parts accumulated more As and inorganic P, whereas Zn, Pb, and Sb were raised mostly in the under-ground samples. The partial least squares regression (PLSR) model predicting the level of each element by the whole metabolome indicated that the enhancement of flavonoids content plays an essential contribution in adaptation with the higher levels of Pb, Ag, and Ni accumulated in the aerial part, and Mn, Pb in subterranean part. Moreover, the models also highlighted the effect of Mn and Pb on the metabolic induction of adenosine derivatives in subterranean parts. At the same time, the model presented the most contribution of As to the metabolisms of the amino acids of this tissue. On those accounts, the developed integration approach linking the ionomics and metabolomics data of P. vittata improved the understanding of the molecular mechanism of hyperaccumulation characteristics and provided markers that could be targeted in future investigations.

Single and joint effects of cadmium and selenium on bioaccumulation, oxidative stress and metabolomic responses in the clam Scrobicularia plana

Selenium (Se) is a vital trace element for many living organisms inclusive of aquatic species. Although the antagonistic action of this element against other pollutants has been previously described for mammals and birds, limited information on the join effects in bivalves is available. To this end, bivalves of the species Scrobicularia plana were exposed to Se and Cd individually and jointly. Digestive glands were analysed to determine dose-dependent effects, the potential influence of Se on Cd bioaccumulationas well as the possible recover of the oxidative stress and metabolic alterations induced by Cd. Selenium co-exposure decreased the accumulation of Cd at low concentrations. Cd exposure significantly altered the metabolome of clams such as aminoacyltRNA biosynthesis, glycerophospholipid and amino acid metabolism, while Se co-exposure ameliorated several altered metabolites such asLysoPC (14:0), LysoPE (20:4), LysoPE (22:6), PE (14:0/18:0), PE (20:3/18:4) andpropionyl-l-carnitine.Additionally, Se seems to be able to regulate the redox status of the digestive gland of clams preventing the induction of oxidativedamage in this organ. This study shows the potential Se antagonism against Cd toxicity in S. plana and the importance to study join effects of pollutants to understand the mechanism underlined the effects.

Mice brain metabolomics after the exposure to a "chemical cocktail" and selenium supplementation through the gut-brain axis

Several environmental pollutants have been shown to damage brain and affect gut microbiota. Limited evidence is available about the impact of "chemical cocktails" (CC) of xenobiotics on brain metabolome and their possible influence in the gut-brain crosstalk. To this end, BALB/c mice were exposed to heavy metals (As, Hg, Cd) and pharmaceuticals (diclofenac and flumequine) under regular rodent diet or supplemented with selenium (Se). Selenium, an antioxidant well-known for its antagonism against the neurotoxicity of several pollutants, modulated several brain metabolic impairments caused by CC (e.g., brain levels of the excitatory amino acid N-acetyl aspartic acid) by influencing mainly the metabolisms of purine, glycosylate and dicarboxylate, glutamate, glycerophospholipid, alanine and aspartate. Numerous associations were obtained between brain metabolites and gut microbes and they changed after Se-supplementation (e.g., Lactobacillus was positively associated with a brain ceramide, phosphoserine, phosphocholine, vitamin D3 derivative, fatty acids, malic acid, amino acids, and urea after the exposure, but not after Se-supplementation). Our results showed numerous evidences about the impact of CC on brain metabolome, the potential role of Se as an antagonist and their impact on the gut-brain axis. Further research is needed to understand the complex mechanism of action implied on CC-brain-microbiota interactions.

Integration of omics analysis and atmospheric pressure MALDI mass spectrometry imaging reveals the cadmium toxicity on female ICR mouse

Acute cadmium toxicity induces multi-system organ failure. Mass spectrometry (MS)-based omics analyses and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-MALDI MSI) are powerful tools for characterizing the biomarkers. Many studies on cadmium toxicity by metabolomics have been investigated, whereas the applications of lipidomics and MSI studies are still inadequate. In this study, the systematic metabolomics study on female ICR mice tissues including liver, kidney, heart, stomach, brain as well as spleen under cadmium exposure was firstly conducted and lipidomic characterizations on female ICR mice liver, kidney and heart were further constructed step by step. To deeply understand its toxicological mechanisms, several representative lipids on the mouse liver were visualized by AP-MALDI MSI. The results demonstrated that exposure to cadmium caused significant metabolic alterations in the liver, kidney and heart among all the tissues. Additionally, the toxicological mechanisms of cadmium in the mouse models are closely associated with the inflammation response, energy expenditure, oxidative stress, DNA and mitochondria damage, and lipid homeostasis. These insights could enhance knowledge in acute cadmium toxicity of public health and guide risk assessment in the future.

Omic methodologies for assessing metal(-loid)s-host-microbiota interplay: A review

Omic methodologies have become key analytical tools in a wide number of research topics such as systems biology, environmental analysis, biomedicine or food analysis. They are especially useful when they are combined providing a new perspective and a holistic view of the analytical problem. Methodologies for microbiota analysis have been mostly focused on genome sequencing. However, information provided by these metagenomic studies is limited to the identification of the presence of genes, taxa and their inferred functionality. To achieve a deeper knowledge of microbial functionality in health and disease, especially in dysbiosis conditions related to metal and metalloid exposure, the introduction of additional meta-omic approaches including metabolomics, metallomics, metatranscriptomics and metaproteomics results essential. The possible impact of metals and metalloids on the gut microbiota and their effects on gut-brain axis (GBA) only begin to be figured out. To this end new analytical workflows combining powerful tools are claimed such as high resolution mass spectrometry and heteroatom-tagged proteomics for the absolute quantification of metal-containing biomolecules using the metal as a "tag" in a sensitive and selective detector (e.g. ICP-MS). This review focus on current analytical methodologies related with the analytical techniques and procedures available for metallomics and microbiota analysis with a special attention on their advantages and drawbacks.

Environmental metal toxicity assessment by the combined application of metallomics and metabolomics

The growing interest of our society for the environment, climate change, and the assurance of the quality of life and health has been the motor of new methodological proposals that allow a more comprehensive knowledge of the problems to be solved. In this sense, the potential of omic methodologies to study these problems from a global perspective represents a milestone in environmental studies. Therefore, the study of essential and toxic metals has a special interest, particularly in relation to toxicity issues and their association to biological interactions, transport, binding to biomolecules, and behavior in biological interfaces. These studies have promoted new instrumental platforms and methodological approaches that allow addressing these problems. Furthermore, to encompass the reality of molecule-atoms interactions in their completeness, combinations of omics have been tried, focusing on environment, food, and health issues. In this sense, the present work is situated, with the objective of reviewing the most recent methodological proposals in the field of the environment and their applications, considering not only the analytical approaches but also how they have to be applied, the use of bioindicators' exposure experiments in the laboratory, and the potential transfer of the findings from the laboratory to the field. This latter point is a true touchstone, which makes these new analytical methodologies in the necessary tools for understanding the environment and the consequences of its imbalance.

Absolute quantification of selenoproteins and selenometabolites in lung cancer human serum by column switching coupled to triple quadrupole inductively coupled plasma mass spectrometry

One of the most important causes of the high mortality rate and low life expectancy of lung cancer is the detection at advanced stages. Thus, there is an urgent need for early diagnosis and the search of new selective biomarkers. Selenium is an important constituent of selenoproteins and a powerful antioxidant able to protect against cancer. In this work, the absolute quantification of selenium in selenoproteins and the total content in selenometabolites has been performed for the first time in serum from lung cancer patients (LC) and healthy controls (HC). To this end, a method for the simultaneous speciation of selenoproteins using size exclusion chromatography (SEC) and affinity chromatography (AF) with detection by ICP-QQQ-MS, and quantification by isotopic dilution (IDA) (SEC-AF-HPLC-SUID-ICP-QQQ-MS) was developed to determine the selenium concentration in eGPx, SEPP1 and SeAlb, as well as total selenometabolites, to find alterations that may serve as biomarkers of this disease. In the same way, a method based on anion-exchange chromatography coupled to ICP-QQQ-MS was developed to quantify selenometabolites (SeCys2, SeMeSeCys, SeMet, selenite and selenate) in the same LC and HC serum samples. The results showed that the averaged concentrations of selenium in eGPx, SeAlb and selenite were significantly higher in LC patients (LC (eGPx: 21.24 ± 0.77 ng g^-1; SeAlb: 49.56 ± 3.16 ng g^-1 and Se(IV): 6.20 ± 1.22 ng g^-1) than in HC group (eGPx: 16.96 ± 0.53 ng g^-1; SeAlb: 38.33 ± 2.66 ng g^-1 and Se(IV): 3.56 ± 0.55 ng g^-1). In addition, the ratios between selenoproteins and selenometabolites have been calculated for the first to study their potential use as LC biomarkers. The rates eGPx/SEPP1, SEPP1/SeAlb, eGPx/Se(IV) and SEPP1/Se(IV) were significantly different between LC and HC groups.

Metabolic impairments, metal traffic, and dyshomeostasis caused by the antagonistic interaction of cadmium and selenium using organic and inorganic mass spectrometry

Cadmium (Cd) has become one of the most important environmental pollutants in the world, derived from natural and industrial sources, which is known to be accumulated in the human body, producing serious health effects. On the other hand, Selenium (Se) is an essential element for mammals, which is well known for its antagonistic interaction against Cd toxicity, such as the prevention of oxidative stress induced by this element. For this reason, the use of complementary analytical methods to study the homeostasis of metals, "traffic" between different organs and massive information about metabolites altered by the exposure, is of great interest. To this end, a metabolomic workflow based on the use of direct infusion mass spectrometry (DIMS) and gas chromatography mass spectrometry (GC-MS) was applied in mice serum. On the other hand, metal homeostasis and traffic between different organs and serum of mice exposed to Cd and Se have been evaluated by determining the concentration of metals by inductively coupled plasma mass spectrometry. This work demonstrates for the first time that Cd exposure causes a decrease of all the elements studied in the lung except itself. On the other hand, Se provokes As trafficking from metabolically less active organs (brain, lung, and testes) to others with greater metabolic activity (kidney), which also facilitates its excretion. Moreover, when mice are only exposed to Se, it provokes the accumulation of almost all the elements in the kidney, except Cd that increases also in the liver and brain. However, when both elements are simultaneously administered, Se increases Cd concentration in all the organs except in the serum and especially in the testis. On the other hand, important metabolic alterations have been detected in the energy and amino acid metabolism, as well as degradation of phospholipidic membranes, and in free fatty acids. In summary, the results show the high potential of the combined use of organic and inorganic mass spectrometry to establish Cd and Se interaction and the biological impairments caused and to provide information about metal traffic and metabolomic changes in exposure experiments.

Urinary 1H NMR metabolomics profile of Italian citizens exposed to background levels of arsenic: a (pre)cautionary tale

Objectives: Arsenic is a toxic metal ubiquitous in the environment and in daily life items. Long-term arsenic exposure is associated with severe adverse health effects involving various target organs. It would be useful to investigate the existence of metabolic alterations associated with lifestyle and/or with the environment. For this purpose, we studied the correlation between urinary arsenic levels and urinary proton nuclear magnetic resonance spectroscopy (¹H NMR) metabolomics profiles in a non-occupationally nor environmentally arsenic exposed general population.Methods: Urine samples were collected from 86 healthy subjects. Total and non-alimentary urinary arsenic (U-naAs) levels, namely the sum of arsenite, arsenate, monomethylarsonate and dimethylarsinate, were measured and ¹H NMR analysis was performed. Orthogonal Projection to Latent Structures was applied to explore the correlation between the metabolomics profiles and U-naAs levels.Results: Despite the extremely low U-naAs levels (mean value = 6.13 ± 3.17 µg/g creatinine) of our studied population a urinary metabolomics profile related to arsenic was identified.Conclusion: The identified profile could represent a fingerprint of early arsenic biological effect and could be used in further studies as an indicator of susceptibility, also in subjects exposed to a low arsenic dose, with implications in occupational health, toxicology, and public health.

Lipid Metabolism Alterations in a Rat Model of Chronic and Intergenerational Exposure to Arsenic

Chronic exposure to arsenic (As), whether directly through the consumption of contaminated drinking water or indirectly through the daily intake of As-contaminated food, is a health threat for more than 150 million people worldwide. Epidemiological studies found an association between chronic consumption of As and several pathologies, the most common being cancer-related disorders. However, As consumption has also been associated with metabolic disorders that could lead to diverse pathologies, such as type 2 diabetes mellitus, nonalcoholic fatty liver disease, and obesity. Here, we used ultra-performance liquid chromatography (UPLC) coupled to electrospray ionization/quadrupole time-of-flight mass spectrometry (ESI-QToF) to assess the effect of chronic intergenerational As exposure on the lipid metabolism profiles of serum from 4-month-old Wistar rats exposed to As prenatally and also during early life in drinking water (3 ppm). Significant differences in the levels of certain identified lysophospholipids, phosphatidylcholines, and triglycerides were found between the exposed rats and the control groups, as well as between the sexes. Significantly increased lipid oxidation determined by the malondialdehyde (MDA) method was found in exposed rats compared with controls. Chronic intergenerational As exposure alters the rat lipidome, increases lipid oxidation, and dysregulates metabolic pathways, the factors associated with the chronic inflammation present in different diseases associated with chronic exposure to As (i.e., keratosis, Bowen's disease, and kidney, liver, bladder, and lung cancer).

Metabolic Impairments Caused by a "Chemical Cocktail" of DDE and Selenium in Mice Using Direct Infusion Triple Quadrupole Time-of-Flight and Gas Chromatography-Mass Spectrometry

Among organic contaminants, pesticides are one of the most important groups of chemicals due to their persistent character and toxicity. However, the biological systems are exposed to a complex environment in which the contaminants can interact in a synergistic/antagonistic fashion, and for this reason, the study of "chemical cocktails" is of great interest to fully understand the final biological effect. In this way, selenium is known for its antagonistic action against several toxicants. In this paper, metabolic impairments caused by the joint exposure of p,p'-dichloro diphenyl trichloroethane (DDE) and selenium (Se) have been issued for the first time. A metabolomic workflow was applied to mice fed DDE and DDE with Se diet, on the basis of the complementary use of two organic mass spectrometric techniques, combining direct infusion mass spectrometry (DI-ESI-QqQ-TOF MS) and gas chromatography-mass spectrometry (GC-MS). The results show a good classification between the studied groups caused by about 70 altered metabolites in the liver, kidney, or brain, including the pathways of energy metabolism, degradation of phospholipidic membrane, β-oxidation, and oxidative stress, which confirm the potential of combined metabolomic platforms in environmental studies.

Metalloproteomics Approach to Analyze Mercury in Breast Milk and Hair Samples of Lactating Women in Communities of the Amazon Basin, Brazil

Mercury is a potentially toxic element that is present in the environment of the Brazilian Amazon and is responsible for adverse health effects in humans. This study sought to assess possible protein biomarkers of mercury exposure in breast milk samples from lactating women in the Madeira and Negro Rivers in the Brazilian Amazon. The mercury content of hair samples of lactating women was determined, and the proteome of breast milk samples was obtained using two-dimensional electrophoresis after protein precipitation with acetone. Mercury measurements of protein spots obtained via protein fractionation were performed by graphite furnace atomic absorption spectrometry (GFAAS), and it was observed that mercury is linked to proteins with molecular masses in the range of 14-26 kDa. The total mercury concentration was also determined by GFAAS in unprocessed milk, lyophilized milk, and protein pellets, with the purpose of determining the mercury mass balance in relation to the concentration of this element in milk and pellets. Approximately 85 to 97% of mercury present in the lyophilized milk from samples of lactating women of the Madeira River is bound in the protein fraction. From lactating women of the Negro River, approximately 49% of the total mercury is bound in the protein fraction, and a difference of 51% is bound in the lipid fraction.

Analysis of 28 trace elements in the blood and serum antioxidant status in chickens under arsenic and/or copper exposure

This study aimed to evaluate the 28 trace elements in the blood and serum antioxidant status in chickens under arsenic (As) and/or copper (Cu) exposure. A total of 200 1-day-old male Hy-Line chickens were fed either a commercial diet (C-group) or arsenic trioxide (30 mg/kg) and/or cupric sulfate (300 mg/kg) for 90 days. The 28 trace element levels in the blood were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of As in the blood of chickens were elevated approximately 17.15-fold, 2.30-fold, and 13.37-fold in the As-group, Cu-group, and As + Cu-group, respectively, at 90 days. The concentrations of Cu did not change in the As-group and increased approximately 29.53 and 23.37% in the Cu-group and As + Cu-group, respectively, at 90 days. Moreover, As exposure caused ion profile disorders in the blood, including increased concentrations of Na, Mg, Si, K, Cr, Fe, and Se and reduced B, Ca, Ti, V, Mn, Co, Ni, Zn, Sr, and Mo. Cu exposure increased the contents of Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Zn, and Se and decreased the content of B, Ca, Al, Ni, and Mo. As + Cu exposure increased the contents of Mg, Si, Cr, Fe, Zn, and Se and decreased the content of B, Ca, Ti, Co, Ni, Sr, and Mo. Moreover, As and/or Cu exposure induced oxidative stress in the blood of chickens. In conclusion, the results indicated that the mixture of As and Cu caused a synergistic effect via disturbing homeostasis of trace elements and oxidative stress in the blood of chickens.

Integration of microRNAome, proteomics and metabolomics to analyze arsenic-induced malignant cell transformation

Long-term exposure to arsenic has been linked to tumorigenesis in different organs and tissues, such as skin; however, the detailed mechanism remains unclear. In this present study, we integrated “omics” including microRNAome, proteomics and metabolomics to investigate the potential molecular mechanisms. Compared with non-malignant human keratinocytes (HaCaT), twenty-six miRNAs were significantly altered in arsenic-induced transformed cells. Among these miRNAs, the differential expression of six miRNAs was confirmed using Q-RT-PCR, representing potential oxidative stress genes. Two-dimensional gel electrophoresis (2D-PAGE) and mass spectrometry (MS) were performed to identify the differential expression of proteins in arsenic-induced transformed cells, and twelve proteins were significantly changed. Several proteins were associated with oxidative stress and carcinogenesis including heat shock protein beta-1 (HSPB1), peroxiredoxin-2 (PRDX2). Using ultra-performance liquid chromatography and Q-TOF mass spectrometry (UPLC/Q-TOF MS), 68 metabolites including glutathione, fumaric acid, citric acid, phenylalanine, and tyrosine, related to redox metabolism, glutathione metabolism, citrate cycle, met cycle, phenylalanine and tyrosine metabolism were identified and quantified. Taken together, these results indicated that arsenic-induced transformed cells exhibit alterations in miRNA, protein and metabolite profiles providing novel insights into arsenic-induced cell malignant transformation and identifying early potential biomarkers for cutaneous squamous cell carcinoma induced by arsenic.

Relationship between Methyl Tertiary Butyl Ether Exposure and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Petrol Station Attendants in Southern China

Methyl tertiary butyl ether (MTBE)—A well known gasoline additive substituting for lead alkyls—causes lipid disorders and liver dysfunctions in animal models. However, whether MTBE exposure is a risk factor for non-alcoholic fatty liver disease (NAFLD) remains uncertain. We evaluate the possible relationship between MTBE exposure and the prevalence of NAFLD among 71 petrol station attendants in southern China. The personal exposure concentrations of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS. NAFLD was diagnosed by using abdominal ultrasonography according to the guidelines for the diagnosis and treatment of NAFLD suggested by the Chinese Hepatology Association. Demographic and clinical characteristics potentially associated with NAFLD were investigated. Mutivariate logistic regression analysis was applied to measure odds ratios and 95% confidence intervals (CI). The result showed that the total prevalence of NAFLD was 15.49% (11/71) among the study subjects. The average exposure concentrations of MTBE were 292.98 ± 154.90 μg/m³ and 286.64 ± 122.28 μg/m³ in NAFLD and non-NAFLD groups, respectively, and there was no statistically significant difference between them (p > 0.05). After adjusting for age, gender, physical exercise, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), alanine aminotransferase (ALT), white blood cell (WBC), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), the odds ratios were 1.31 (95% CI: 0.85–1.54; p > 0.05), 1.14 (95% CI: 0.81–1.32; p > 0.05), 1.52 (95% CI: 0.93–1.61; p > 0.05) in the groups (including men and women) with exposure concentrations of MTBE of 100–200 μg/m³, 200–300 μg/m³, and ≥300 μg/m³, respectively, as compared to the group (including men and women) ≤100 μg/m³. Our investigation indicates that exposure to MTBE does not seem to be a significant risk factor for the prevalence of NAFLD among petrol station attendants in southern China.

Differential proteomic expression of human placenta and fetal development following e-waste lead and cadmium exposure in utero

Prenatal exposure to lead (Pb) and cadmium (Cd) has been associated with a series of physiological problems resulting in fetal growth restriction. We aimed to investigate the effects of Pb and Cd exposure on placental function and the potential mechanisms involved in fetal development. Placental specimens and questionnaires were collected from an e-waste area and a reference area in China. Two-dimensional electrophoresis combined with MALDI-TOF-MS/MS and molecular network relationship were performed to analyze differentially expressed proteins using a compositing sample pool. Compared with the reference group, the exposed group exhibited significantly higher levels of placental Pb and Cd (p<0.01), shorter body length and higher gestational age (p<0.01). After bivariate adjustment in a linear regression model, decreases of 205.05g in weight and 0.44cm in body length were associated with a 10ng/g wt increase in placental Cd. Pb showed a negative trend but lacked statistical significance. Proteomic analysis showed 32 differentially-expressed proteins and were predominantly involved in protein translocation, cytoskeletal structure, and energy metabolism. Fumarate hydratase was down-regulated in the exposed placenta tissues and validated by ELISA. Alterations in placental proteome suggest that imbalances in placental mitochondria respiration might be a vital pathway targeting fetal growth restriction induced by exposure to Cd.

Metabolomic Characterizations of Liver Injury Caused by Acute Arsenic Toxicity in Zebrafish

Arsenic is one of the most common metalloid contaminants in groundwater and it has both acute and chronic toxicity affecting multiple organs. Details of the mechanism of arsenic toxicity are still lacking and profile studies at metabolic level are very limited. Using gas chromatography coupled with mass spectroscopy (GC/MS), we first generated metabolomic profiles from the livers of arsenic-treated zebrafish and identified 34 significantly altered metabolite peaks as potential markers, including four prominent ones: cholic acid, glycylglycine, glycine and hypotaurine. Combined results from GC/MS, histological examination and pathway analyses suggested a series of alterations, including apoptosis, glycogenolysis, changes in amino acid metabolism and fatty acid composition, accumulation of bile acids and fats, and disturbance in glycolysis related energy metabolism. The alterations in glycolysis partially resemble Warburg effect commonly observed in many cancer cells. However, cellular damages were not reflected in two conventional liver function tests performed, Bilirubin assay and alanine aminotransferase (ALT) assay, probably because the short arsenate exposure was insufficient to induce detectable damage. This study demonstrated that metabolic changes could reflect mild liver impairments induced by arsenic exposure, which underscored their potential in reporting early liver injury.

Metabolomic profiles of arsenic (+3 oxidation state) methyltransferase knockout mice: effect of sex and arsenic exposure

Arsenic (+3 oxidation state) methyltransferase (As3mt) is the key enzyme in the pathway for methylation of inorganic arsenic (iAs). Altered As3mt expression and AS3MT polymorphism have been linked to changes in iAs metabolism and in susceptibility to iAs toxicity in laboratory models and in humans. As3mt-knockout mice have been used to study the association between iAs metabolism and adverse effects of iAs exposure. However, little is known about systemic changes in metabolism of these mice and how these changes lead to their increased susceptibility to iAs toxicity. Here, we compared plasma and urinary metabolomes of male and female wild-type (WT) and As3mt-KO (KO) C57BL/6 mice and examined metabolomic shifts associated with iAs exposure in drinking water. Surprisingly, exposure to 1 ppm As elicited only small changes in the metabolite profiles of either WT or KO mice. In contrast, comparisons of KO mice with WT mice revealed significant differences in plasma and urinary metabolites associated with lipid (phosphatidylcholines, cytidine, acyl-carnitine), amino acid (hippuric acid, acetylglycine, urea), and carbohydrate (L-sorbose, galactonic acid, gluconic acid) metabolism. Notably, most of these differences were sex specific. Sex-specific differences were also found between WT and KO mice in plasma triglyceride and lipoprotein cholesterol levels. Some of the differentially changed metabolites (phosphatidylcholines, carnosine, and sarcosine) are substrates or products of reactions catalyzed by other methyltransferases. These results suggest that As3mt KO alters major metabolic pathways in a sex-specific manner, independent of iAs treatment, and that As3mt may be involved in other cellular processes beyond iAs methylation.

Metabolomics analysis reveals heavy metal copper-induced cytotoxicity in HT-29 human colon cancer cells

LC-MS based metabolomics analysis reveals heavy metal copper-induced cytotoxicity in a human intestinal cell line, HT-29.

Huang-Lian-Jie-Du decoction treated sepsis via regulating ERK and SRC/STAT3 pathways and ameliorating metabolic status

LPS disturbed the metabolomic profiles and activated the ERK and SRC/STAT3 signaling pathways of mice, and HLJDD exerted therapeutic effects on sepsis induced by LPS.

Identification of diagnostic biomarkers and metabolic pathway shifts of heat-stressed lactating dairy cows

Controlling heat stress (HS) is a global challenge for the dairy industry. However, simple and reliable biomarkers that aid the diagnoses of HS-induced metabolic disorders have not yet been identified. In this work, an integrated metabolomic and lipidomic approach using (1)H nuclear magnetic resonance and ultra-fast LC-MS was employed to investigate the discrimination of plasma metabolic profiles between HS-free and HS lactating dairy cows. Targeted detection using LC-MS in multiple reaction monitoring mode was used to verify the reliability of the metabolites as biomarker candidates. Overall, 41 metabolites were identified as candidates for lactating dairy cows exposed to HS, among which 13 metabolites, including trimethylamine, glucose, lactate, betaine, creatine, pyruvate, acetoacetate, acetone, β-hydroxybutyrate, C16 sphinganine, lysophosphatidylcholine (18:0), phosphatidylcholine (16:0/14:0), and arachidonic acid, had high sensitivity and specificity in diagnosing HS status, and are likely to be the potential biomarkers of HS dairy cows. All of these potentially diagnostic biomarkers were involved in carbohydrate, amino acid, lipid, or gut microbiome-derived metabolism, indicating that HS affected the metabolic pathways in lactating dairy cows. Further research is warranted to evaluate these biomarkers in practical applications and to elucidate the physiological mechanisms of HS-induced metabolic disorders.

BIOLOGICAL SIGNIFICANCE

Heat stress (HS) annually causes huge losses to global dairy industry, including animal performance decrease, metabolic disorder and health problem. So far, physiological mechanisms underlying HS of dairy cows still remain elusive. To our best knowledge, this is the first attempt to elucidate the HS-induced metabolic disorders of dairy cows using integrated (1)H NMR and LC-MS-based metabolic study. The results not only provided potential diagnostic biomarkers for HS lactating dairy cows, but also significantly explored the related physiological mechanisms of metabolic pathway shifts induced by HS environment. This work offers comprehensive insights into the global metabolic alterations of dairy cows exposed to HS and provides a new perspective for further study.

An insight into silver nanoparticles bioavailability in rats

A comprehensive study of the bioavailability of orally administered silver nanoparticles (AgNPs) was carried out using a rat model. The silver uptake was monitored in liver and kidney tissues, as well as in urine and in feces. Significant accumulation of silver was found in both organs, the liver being the principal target of AgNPs. A significant (∼50%) fraction of silver was found in feces whereas the fraction excreted via urine was negligible (< 0.01%). Intact silver nanoparticles were found in feces by asymmetric flow field-flow fractionation (AsFlFFF) coupled with UV-Vis analysis. Laser ablation-ICP MS imaging showed that AgNPs were able to penetrate into the liver, in contrast to kidneys where they were retained in the cortex. Silver speciation analysis in cytosols from kidneys showed the metallothionein complex as the major species whereas in the liver the majority of silver was bound to high-molecular (70-25 kDa) proteins. These findings demonstrate the presence of Ag(i), released by the oxidation of AgNPs in the biological environment.