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

Bioavailability of flumequine and diclofenac in mice exposed to a metal-drug chemical cocktail. Evaluation of the protective role of selenium

BACKGROUND AND PURPOSE

Organisms, including humans, are subjected to the simultaneous action of a wide variety of pollutants, the effects of which should not be considered in isolation, as many synergies and antagonisms have been found between many of them. Therefore, this work proposes an in vivo study to evaluate the effect of certain metal contaminants on the bioavailability and metabolism of pharmacologically active compounds. Because the most frequent entry vector is through ingestion, the influence of the gut microbiota and the possible protective effects of selenium has been additionally evaluated.

EXPERIMENTAL APPROACH

A controlled exposure experiment in mammals (Mus musculus) to a "chemical cocktail" consisting of metals and pharmaceuticals (diclofenac and flumequine). The presence of selenium has also been evaluated as an antagonist. Mouse plasma samples were measured by UPLC-QTOF. A targeted search of 48 metabolites was also performed.

KEY RESULTS

Metals significantly affected the FMQ plasma levels when the gut microbiota was depleted. Hydroxy FMQ decreased if metals were present. Selenium minimized this decrease. The 3-hydroxy DCF metabolite was not found in any case. Changes in some metabolic pathways are discussed.

CONCLUSIONS AND IMPLICATIONS

The presence of metals in the mouse diet as well as the prior treatment of mice with an antibiotic mixture (Abxs), which deplete the gut microbiota, has a decisive effect on the bioavailability and metabolism of the tested pharmaceuticals and dietary selenium minimize some of their effects.

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.

Traffic Density Exposure, Oxidative Stress Biomarkers and Plasma Metabolomics in a Population-Based Sample: The Hortega Study

Exposure to traffic-related air pollution (TRAP) generates oxidative stress, with downstream effects at the metabolic level. Human studies of traffic density and metabolomic markers, however, are rare. The main objective of this study was to evaluate the cross-sectional association between traffic density in the street of residence with oxidative stress and metabolomic profiles measured in a population-based sample from Spain. We also explored in silico the potential biological implications of the findings. Secondarily, we assessed the contribution of oxidative stress to the association between exposure to traffic density and variation in plasma metabolite levels. Traffic density was defined as the average daily traffic volume over an entire year within a buffer of 50 m around the participants' residence. Plasma metabolomic profiles and urine oxidative stress biomarkers were measured in samples from 1181 Hortega Study participants by nuclear magnetic resonance spectroscopy and high-performance liquid chromatography, respectively. Traffic density was associated with 7 (out of 49) plasma metabolites, including amino acids, fatty acids, products of bacterial and energy metabolism and fluid balance metabolites. Regarding urine oxidative stress biomarkers, traffic associations were positive for GSSG/GSH% and negative for MDA. A total of 12 KEGG pathways were linked to traffic-related metabolites. In a protein network from genes included in over-represented pathways and 63 redox-related candidate genes, we observed relevant proteins from the glutathione cycle. GSSG/GSH% and MDA accounted for 14.6% and 12.2% of changes in isobutyrate and the CH2CH2CO fatty acid moiety, respectively, which is attributable to traffic exposure. At the population level, exposure to traffic density was associated with specific urine oxidative stress and plasma metabolites. Although our results support a role of oxidative stress as a biological intermediary of traffic-related metabolic alterations, with potential implications for the co-bacterial and lipid metabolism, additional mechanistic and prospective studies are needed to confirm our findings.

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.

The role of selenium in shaping mice brain metabolome and selenoproteome through the gut-brain axis by combining metabolomics, metallomics, gene expression and amplicon sequencing

Selenium (Se) is a trace element crucial for human health. Recently, the impact of Se supplementation on gut microbiota has been pointed out as well as its influence on the expression of certain selenoproteins and gut metabolites. This study aims to elucidate the link between Se supplementation, brain selenoproteins and brain metabolome as well as the possible connection with the gut-brain axis. To this end, an in vivo study with 40 BALB/c mice was carried out. The study included conventional (n=20) and mice model with microbiota depleted by antibiotics (n=20) under a regular or Se supplemented diet. Brain selenoproteome was determined by a transcriptomic/gene expression profile, while brain metabolome and gut microbiota profiles were accomplished by untargeted metabolomics and amplicon sequencing, respectively. The total content of Se in brain was also determined. The selenoproteins genes Dio and Gpx isoenzymes, SelenoH, SelenoI, SelenoT, SelenoV and SelenoW and 31 metabolites were significantly altered in the brain after Se supplementation in conventional mice, while 11 selenoproteins and 26 metabolites were altered in microbiota depleted mice. The main altered brain metabolites were related to glyoxylate and dicarboxylate metabolism, amino acid metabolism, and gut microbiota that have been previously related with the gut-brain axis (e.g., members of Lachnospiraceae and Ruminococcaceae families). Moreover, specific associations were determined between brain selenoproteome and metabolome, which correlated with the same bacteria, suggesting an intertwined mechanism. Our results demonstrated the effect of Se on brain metabolome through specific selenoproteins gene expression and gut microbiota.

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.

Nano-selenium alleviates cadmium-induced cerebellar injury by activating metal regulatory transcription factor 1 mediated metal response

This study aims to investigate the role of metal regulatory transcription factor 1 (MTF1)-mediated metal response in cadmium (Cd)-induced cerebellar injury, and to evaluate the antagonistic effects of nano-selenium (Nano-Se) against Cd toxicity. A total of 80 chicks (1 d old, male, Hy-Line Variety White) were randomly allocated to 4 treatment groups for 3 months: the control group (fed with a basic diet, n = 20), the Nano-Se group (basic diet with 1 mg/kg nano-Se 1 mg/kg Nano-Se in basic diet, n = 20), the Nano-Se + Cd group (basic diet with 1 mg/kg Nano-Se and 140 mg/kg CdCl₂, n = 20) and the Cd group (basic diet with 140 mg/kg CdCl₂ , n = 20). The results of the experiment showed that the Purkinje cells were significantly decreased with their degradation and indistinct nucleoli after Cd exposure. Moreover, exposure to Cd caused a significant accumulation of Cd and cupper. However, the contents of Se, iron, and zinc were decreased, thereby disturbing the metal homeostasis in the cerebellum. The Cd exposure also resulted in high levels of malondialdehyde (MDA) and down regulation of selenoprotein transcriptome. Furthermore, the expressions of MTF1, metallothionein 1 (MT1), MT2, zinc transporter 3 (ZNT3), ZNT5, ZNT10, zrt, irt-like protein 8 (ZIP8), ZIP10, transferrin (TF), ferroportin 1 (FPN1), ATPase copper transporting beta (ATP7B), and copper uptake protein 1 (CTR1) were inhibited by Cd exposure. However, all these changes were significantly alleviated by the supplementation of Nano-Se. This study proved that Cd could disorder metal homeostasis and induce oxidative stress, whereas Nano-Se could relieve all these negative effects caused by Cd via activating the MTF1-mediated metal response in the cerebellum of chicken.

Impact of "chemical cocktails" exposure in shaping mice gut microbiota and the role of selenium supplementation combining metallomics, metabolomics, and metataxonomics

Biological systems are exposed to a complex environment in which pollutants can interact through synergistic or antagonistic mechanisms, but limited information is available on the combined effects. To this end, conventional and antibiotic-treated (Abx) mice models were fed regular rodent or selenium (Se) supplemented diets and exposed to a "chemical cocktail" (CC) including metals and pharmaceuticals. Metallomics, metabolomics, and metataxomics were combined to delve into the impact on gut microbiota, plasma selenoproteome, metabolome, and arsenic metabolization. At the molecular level, Se decreased the concentration of the antioxidant glutathione peroxidase in plasma and increased the arsenic methylation rate, possibly favoring its excretion, but not in the Abx and also plasma metabolomes of Abx, and Abx-Se were not differentiated. Moreover, numerous associations were obtained between plasma selenoproteins and gut microbes. Se-supplementation partially antagonizes the gut microbiota alteration caused by Abx, and slightly by CC, but strongly altered profiles were observed in CC-Abx-Se, suggesting synergistic deleterious effects between pollutants, Abx and Se. Moreover, although CC and Abx changed gut microbiota, several common taxa were enriched in CC-Abx and control mice, indicating possible synergistic effects. Our results suggest a potential beneficial impact of supplementation, but mediated by gut microbes being reversed in their absence.

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.

Antagonistic Interaction of Selenium and Cadmium in Human Hepatic Cells Through Selenoproteins

Cadmium (Cd) is a highly toxic heavy metal for humans and animals, which is associated with acute hepatotoxicity. Selenium (Se) confers protection against Cd-induced toxicity in cells, diminishing the levels of ROS and increasing the activity of antioxidant selenoproteins such as glutathione peroxidase (GPx). The aim of this study was to evaluate the antagonistic effect of selenomethionine (SeMet) against Cd toxicity in HepG2 cells, through the modulation of selenoproteins. To this end, the cells were cultured in the presence of 100 µM SeMet and 5 μM, 15 µM, and 25 µM CdCl₂ and a combination of both species for 24 h. At the end of the experiment, cell viability was determined by MTT assay. The total metal content of Cd and Se was analyzed by triple-quadrupole inductively coupled plasma–mass spectrometry (ICP-QqQ-MS). To quantify the concentration of three selenoproteins [GPx, selenoprotein P (SELENOP), and selenoalbumin (SeAlb)] and selenometabolites, an analytical methodology based on column switching and a species-unspecific isotopic dilution approach using two-dimensional size exclusion and affinity chromatography coupled to ICP-QqQ-MS was applied. The co-exposure of SeMet and Cd in HepG2 cells enhanced the cell viability and diminished the Cd accumulation in cells. Se supplementation increased the levels of selenometabolites, GPx, SELENOP, and SeAlb; however, the presence of Cd resulted in a significant diminution of selenometabolites and SELENOP. These results suggested that SeMet may affect the accumulation of Cd in cells, as well as the suppression of selenoprotein synthesis induced by Cd.

Gene-environment interaction analysis of redox-related metals and genetic variants with plasma metabolic patterns in a general population from Spain: The Hortega Study

Background

Limited studies have evaluated the joint influence of redox-related metals and genetic variation on metabolic pathways. We analyzed the association of 11 metals with metabolic patterns, and the interacting role of candidate genetic variants, in 1145 participants from the Hortega Study, a population-based sample from Spain.

Methods

Urine antimony (Sb), arsenic, barium (Ba), cadmium (Cd), chromium (Cr), cobalt (Co), molybdenum (Mo) and vanadium (V), and plasma copper (Cu), selenium (Se) and zinc (Zn) were measured by ICP-MS and AAS, respectively. We summarized 54 plasma metabolites, measured with targeted NMR, by estimating metabolic principal components (mPC). Redox-related SNPs (N = 291) were measured by oligo-ligation assay.

Results

In our study, the association with metabolic principal component (mPC) 1 (reflecting non-essential and essential amino acids, including branched chain, and bacterial co-metabolism versus fatty acids and VLDL subclasses) was positive for Se and Zn, but inverse for Cu, arsenobetaine-corrected arsenic (As) and Sb. The association with mPC2 (reflecting essential amino acids, including aromatic, and bacterial co-metabolism) was inverse for Se, Zn and Cd. The association with mPC3 (reflecting LDL subclasses) was positive for Cu, Se and Zn, but inverse for Co. The association for mPC4 (reflecting HDL subclasses) was positive for Sb, but inverse for plasma Zn. These associations were mainly driven by Cu and Sb for mPC1; Se, Zn and Cd for mPC2; Co, Se and Zn for mPC3; and Zn for mPC4. The most SNP-metal interacting genes were NOX1, GSR, GCLC, AGT and REN. Co and Zn showed the highest number of interactions with genetic variants associated to enriched endocrine, cardiovascular and neurological pathways.

Conclusions

Exposures to Co, Cu, Se, Zn, As, Cd and Sb were associated with several metabolic patterns involved in chronic disease. Carriers of redox-related variants may have differential susceptibility to metabolic alterations associated to excessive exposure to metals.

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In a population-based sample, cobalt, copper, selenium, zinc, arsenic, cadmium and antimony exposures were related to some metabolic patterns.

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Carriers of redox-related variants displayed differential susceptibility to metabolic alterations associated to excessive metal exposures.

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Cobalt and zinc showed a number of statistical interactions with variants from genes sharing biological pathways with a role in chronic diseases.

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The metabolic impact of metals combined with variation in redox-related genes might be large in the population, given metals widespread exposure.

Targeted and untargeted metabolomic analysis of Procambarus clarkii exposed to a "chemical cocktail" of heavy metals and diclofenac

Water pollution poses an important problem, but limited information is available about the joined effects of xenobiotics of different chemical groups to evaluate the real biological response. Procambarus clarkii (P. clarkii) has been demonstrated to be a good bioindicator for assessing the quality of aquatic ecosystems. In this work, we studied the bioaccumulation of cadmium (Cd), arsenic (As) and diclofenac (DCF) in different tissues of P. clarkii during 21 days after the exposure to a "chemical cocktail" of As, Cd and DCF, and until 28 days considering a depuration period. In addition, a combined untargeted and targeted metabolomic analysis was carried out to delve the metabolic impairments caused as well as the metabolization of DCF. Our results indicate that As and Cd were mainly accumulated in the hepatopancreas followed by gills and finally abdominal muscle. As and Cd show a general trend to increase the concentration throughout the exposure experience, while a decrease in the concentration of these elements is observed after 7 days of the depuration process. This is also the case in the abdominal muscle for Cd, but not for As and DCF, which increased the concentration in this tissue in the depuration phase. The hepatopancreas showed the greatest number of metabolic pathways affected. Thus, we observed a crucial bioaccumulation of xenobiotics and impairments of metabolites in different tissues. This is the first study combining the exposure to metals and pharmaceutically active compounds in P. clarkii by untargeted metabolomics including the biotransformation of DCF.

Selenium supplementation influences mice testicular selenoproteins driven by gut microbiota

Selenium is a well-known essential element with important roles in human reproductive health mainly due to its antioxidant character. This study aimed to investigate the potential role of selenoproteins on gut microbiota and male reproductive health. A new assay for the absolute quantification of selenoproteins in testicular tissue based on two dimensional chromatography with inductively coupled plasma mass spectrometry was performed for the first time. The gut microbiota profile was obtained by 16S rRNA gene sequencing. Numerous associations were found between testicular selenoproteins and gut microbiota (e.g. Mucispirillum, related with sperm activity and testosterone, was associated with glutathione peroxidase (GPx) and selenoalbumin (SeAlb), while Escherichia/Shigella, related to sex hormones, correlated with GPx, selenoprotein P (SelP) and SeAlb). The effects of Se-supplementation on testicular selenoproteins only occur in conventional mice, suggesting a potential selenoproteins-microbiota interplay that underlies testicular function. The selenoproteins GPx and SelP have been quantified for the first time in the testicles, and the novel identification of SeAlb, a protein with nonspecifically incorporated Se, is also reported. These findings demonstrate the significant impact of Se-supplementation on gut microbiota and male reproductive health. In addition, the analytical methodology applied here in selenoprotein quantification in testicular tissue opens new possibilities to evaluate their role in gut microbiota and reproductive health axis.

Identification of epigenetic modifications mediating the antagonistic effect of selenium against cadmium-induced breast carcinogenesis

The antagonistic effect of selenium (Se) against cadmium (Cd)-induced breast carcinogenesis was reported, but underlying mechanisms were unclear. The aim of this study was to identify the epigenetically regulated genes and biological pathways mediating the antagonistic effect. We exposed MCF-7 cells to Cd and Se alone or simultaneously. Cell proliferation was assessed by MTT assay, and differential epigenome (DNA methylation, microRNA, and long non-coding RNA) was obtained by microarrays. We cross-verified the epigenetic markers with differential transcriptome, and the ones modulated by Cd and Se in opposite directions were regarded to mediate the antagonistic effect. The epigenetically regulated genes were validated by using gene expression data in human breast tissues. We further assessed the biological functions of these validated genes. Our results showed that Se alleviated the proliferative effect of Cd on MCF-7 cell. A total of 10 epigenetically regulated genes were regarded to mediate the antagonistic effect, including APBA2, KIAA0895, DHX35, CPEB3, SVIL, MYLK, ZFYVE28, ABLIM2, GRB10, and PCDH9. Biological function analyses suggested that these epigenetically regulated genes were involved in multiple cancer-related pathways, such as focal adhesion and PI3K/Akt pathway. In conclusion, we provided evidence that Se antagonized the Cd-induced breast carcinogenesis via epigenetic modification and revealed the critical pathways.

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.

Untargeted Gut Metabolomics to Delve the Interplay between Selenium Supplementation and Gut Microbiota

Selenium (Se) is an essential trace element with important health roles due to the antioxidant properties of selenoproteins. To analyze the interplay between Se and gut microbiota, gut metabolomic profiles were determined in conventional (C) and microbiota depleted mice (Abx) after Se-supplementation (Abx-Se) by untargeted metabolomics, using an analytical multiplatform based on GC-MS and UHPLC-QTOF-MS (MassIVE ID MSV000087829). Gut microbiota profiling was performed by 16S rRNA gene amplicon sequencing. Significant differences in the levels of about 70% of the gut metabolites determined, including fatty acyls, glycerolipids, glycerophospholipids, and steroids, were found in Abx-Se compared to Abx, and only 30% were different between Abx-Se and C, suggesting an important effect of Se-supplementation on Abx mice metabolism. At genus level, the correlation analysis showed strong associations between metabolites and gut bacterial profiles. Likewise, higher abundance of Lactobacillus spp., a potentially beneficial genus enriched after Se-supplementation, was associated with higher levels of prenol lipids, phosphatidylglycerols (C-Se), steroids and diterpenoids (Abx-Se), and also with lower levels of fatty acids (Abx-Se). Thus, we observed a crucial interaction between Se intake-microbiota-metabolites, although further studies to clarify the specific mechanisms are needed. This is the first study about untargeted gut metabolomics after microbiota depletion and Se-supplementation.

Impact of Antibiotic-Induced Depletion of Gut Microbiota and Selenium Supplementation on Plasma Selenoproteome and Metal Homeostasis in a Mice Model

Selenium (Se) is a micronutrient involved in important health functions and it has been suggested to shape gut microbiota. Limited information on Se assimilation by gut microbes and the possible link with selenoproteins are available. For this purpose, conventional and gut microbiota-depleted BALB/c mice were fed a Se-supplemented diet. The absolute quantification of mice plasma selenoproteins was performed for the first time using heteroatom-tagged proteomics. The gut microbiota profile was analyzed by 16S rRNA gene sequencing. Se-supplementation modulated the concentration of the antioxidant glutathione peroxidase and the Se-transporter selenoalbumin as well as the metal homeostasis, being influenced by microbiota disruption, which suggests an intertwined mechanism. Se also modulated microbiota diversity and richness and increased the relative abundance of some health-relevant taxa (e.g., families Christensenellaceae, Ruminococcaceae, and Lactobacillus genus). This study demonstrated the potential beneficial effects of Se on gut microbiota, especially after antibiotic-treatment and the first associations between specific bacteria and plasma selenoproteins.

Integrated analysis of mRNA-m6A-protein profiles reveals novel insights into the mechanisms for cadmium-induced urothelial transformation

Objective: This study aimed to investigate the mechanisms underlying Cd-induced urothelial transformation, using multi-omics analyses (transcriptome, epitranscriptome, and proteome).Methods: Transcriptomics analysis was performed to estimate the expression of genes, methylated RNA immunoprecipitation sequencing analysis was used to detect m⁶A modification, while proteomics analysis was used to identify differentially expressed proteins. Differentially expressed genes (DEGs) were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis.Results: A total of 9491 DEGs, 711 differentially expressed proteins, and 633 differentially m⁶A modified genes between Cd-transformed cells and control cells were identified. The regulation of most genes varied at different omics layers. The three omics data shared 57 genes, and these genes were enriched in response to DNA damage stimulus and cell proliferation. Interestingly, 13 genes, most of which are related to the onset or progression of cancer, were shared by the m⁶A and proteomics data, but not the transcriptome data. This suggested that m⁶A modification is crucial for post-transcriptional regulation related to Cd²⁺-induced malignant transformation.Conclusion: Our multi-omics analysis provided a comprehensive reference map of gene activity and revealed m⁶A signalling pathways crucial for Cd²⁺ carcinogenesis.

Impacts of environmental issues on health and well-being: a global pollution challenge

Every 2 years, the environmental, chemical, and health research communities meet in Costa de Caparica, Portugal to showcase the latest technologies, methodologies and research advances in pollution detection, contamination control, remediation, and related health issues. Since its inception in 2015, the International Caparica Conference on Pollution Metal Ions and Molecules (PTIM) has become a biennial global forum to hear from those who protect the land, the water, and the air at all environmental scales. During past PTIM editions, we have learned about numerous efforts to develop new recovery and clean-up processes to restore the natural equilibria of our planet. Soil, land, water, and air are the key focus of efforts that will require deeper understanding and better control.

The effect of combined exposure of zinc and nickel on the development of zebrafish

Excessive accumulation of Zn²⁺ or Ni²⁺ can cause various problems to aquatic animals. In this study, the developmental toxicity induced by individual or combined exposure of Zn²⁺ and Ni²⁺ to zebrafish embryos and larvae were evaluated to better understand the interaction between Zn²⁺ and Ni²⁺ . Both of individual and combined exposure of Zn²⁺ and Ni²⁺ could cause obvious developmental toxicity, which mainly occurred after hatching, at a concentration-dependent manner. The calculated 168-h LC₅₀ were 2.79 mg/L for Zn²⁺ and 7.44 mg/L for Ni²⁺ . The interaction of Zn²⁺ and Ni²⁺ based on mortality was found to be an antagonism. Various malformations, including tail curving, spinal curvature, pericardial edema, and yolk sac edema, were observed with significant effects on body length and heartbeat rates after exposure of Zn²⁺ and Ni²⁺ . Meanwhile, some genes related to cardiovascular development and bone formation were mainly down-regulated by the individual and combined exposure of Zn²⁺ and Ni²⁺ . The individual exposure was more toxic than combined exposure because the interaction of Zn²⁺ and Ni²⁺ was determined to be an antagonism. The down-regulation of genes related to cardiovascular development and bone formation may contribute to the observed malformation and decreases of body length and heartbeat rates.

NEUROTOXICITY OF METAL MIXTURES

Environmental exposures and/or alterations in the homeostasis of essential transition metals (ETM), such as Fe, Cu, Zn or Mn, are known to contribute to neurodegenerative diseases (ND), such as Alzheimer's Disease (AD) and Parkinson's Disease (PD). Aberrant ETM homeostasis leads to altered distributions, as significant amounts may accumulate in specific brain areas, while causing metal deficiency in others. The disruption of processes reliant on the interplay between these ETM, may lead to loss of metal balance and the ensuing neurotoxicity via shared mechanisms, such as the induction of oxidative stress (OS). Both ETM imbalance and OS may play a role, via complex positive loop processes, in primary neuropathological signatures of AD, such as the accumulation of amyloid plaques and neurofibrillary tangles (NTF), and in PD, α-Syn aggregation and loss of dopamine(DA)rgic neurons. The association between ETM imbalance and ND is rarely approached under the view that metals such as Fe, Cu, Zn and Mn, can act as dangerous endogenous neurotoxic mixtures when their control mechanisms became disrupted. In fact, their presence as mixtures implies intricacies, which should be kept in mind when developing therapies for complex disorders of metal dyshomeostasis, which commonly occur in ND.