Project description:Per- and polyfluoroalkyl substances (PFAS) are a very large (thousands of chemicals) category; these substances have important industrial and consumer product applications. PFAS are highly persistent in the environment, and some are known to pose human health hazard. Regulatory agencies worldwide are considering restrictions and outright bans of PFAS; however, little data exists to make informed decisions. Therefore, a prioritization strategy is urgently needed for evaluation of potential hazards of PFAS. Structure-based grouping could expedite selection of PFAS for testing; still, the hypothesis that structure-effect relationships exist requires confirmation. We tested 26 structurally diverse PFAS from 8 groups in two human cell types from organs that are thought to be targets for PFAS. We used human induced pluripotent stem cell-derived hepatocytes and cardiomyocytes and tested concentration-response effects on both cell function and gene expression. Few phenotypic effects were observed in hepatocytes, but negative chronotropy was observed for 8 of 26 PFAS. Substance- and cell-dependent transcriptomic changes were more pronounced; however, little evidence of group-specific effects was observed. In hepatocytes, we found up-regulation of stress-related and extracellular matrix organization pathways, and down-regulation of fat metabolism. In cardiomyocytes, contractility-related pathways were most affected. Using these data, we derived phenotypic and transcriptomic point of departure estimates and compared them to predicted PFAS exposures. The conservative estimates for bioactivity and exposure were used to derive margin-of-exposure (MOE) for each PFAS. We found that most (23 of 26) PFAS had MOE>1. Overall, our data suggests that chemical structure-based grouping of PFAS may not be an appropriate strategy to predict their biological effects. This means that testing of the individual PFAS would be needed for confident decision-making. Our proposed strategy of using two human cell types and considering both phenotypic and transcriptomic effects, combined with dose-response analysis, may be used for prioritization of PFAS.

Project description:Per- and polyfluoroalkyl substances (PFAS) are some of the most prominent organic contaminants in human blood that have the potential to disrupt biological processes and pathways in the liver. Although the toxicological implications from human exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are well established, data on other, lesser-understood PFAS are limited. A challenge for regulatory authorities is to determine acceptable levels of human exposure to large, diverse classes of environmental contaminants. New approach methodologies (NAMs) that apply bioinformatics tools to interpret biological data are being increasingly considered to inform risk assessment when traditional toxicology methodologies are not amenable. The aim of the current investigation was to identify the biological responses relevant to PFAS mode of action as the concentration (benchmark dose) that these effects take place in order to utililze this information to inform/facilitate read-across for risk assessment of data-poor PFAS. A TempO-Seq platform (BioSpyder) measured gene expression changes in human liver microtissues (i.e., spheroids) after 1-day and 10-day exposures to increasing concentrations of PFAS. A bioinformatics framework was applied to 23 PFAS sub-classed into carboxylates (PFCAs), sulfonates (PFSAs), or PFAS precursors that were analyzed for the total altered transcripts, the concentration where effects take place, and identifying target genes of interest. Both PFCAs and PFSAs exhibited a trend toward increased transcriptional changes with carbon chain-length. Specifically, longer-chain compounds (7 to 10 carbons) were more likely to surpass liver-toxic transcriptomic thresholds established from previous studies than shorter chain PFAS. Longer-chain PFAS were also more potent, inducing transcriptional effects at lower concentrations. However, PFOS was the most potent PFAS and of all precursors, only PFOSA (a PFOS precursor) induced a response. The combined high-throughput transcriptomic and bioinformatics analyses revealed the capability of NAMs to assess the effects of PFAS in liver microtissues; such data improves our understanding of PFAS-related effects in humans and facilitates the use of read-across in human health risk assessment for other data-poor chemicals.

Project description:This Agilent QTOF data consists of urine and liver of mice fed AFFF, as well as PFAS chemical standards treated with mouse enzymes for biotransformation. Data acquired by Sheng Liu and David A. Dukes. It goes alongside the manuscript: "Expanding PFAS Identification with Transformation Product Libraries: Non-Targeted Analysis Reveals Biotransformation Products in Mice" published in Environmental Science & Technology An interactive dataset after FluoroMatch annotation for the urine data can be found here: https://innovativeomics.com/datasets/non-targeted-pfas-dataset-from-urine-of-afff-fed-mice/ Software with the biotransformation libraries can also be found at: https://innovativeomics.com Per- and polyfluoroalkyl substances (PFAS) are widely used persistent synthetic chemicals that have been linked to adverse health effects. While the behavior of PFAS has been evaluated in the environment, our understanding of reaction products in mammalian systems is limited. This study identified biological PFAS transformation products and generated mass spectral libraries to facilitate automated search and identification. The biological transformation products of 27 PFAS, spanning 5 chemical subclasses (alcohols, sulfonamides, carboxylic acids, ethers, and esters), were evaluated following enzymatic reaction with mouse liver S9 fractions. Four major pathways were identified by liquid chromatography-high resolution mass spectrometry: glucuronidation; sulfation; dealkylation and oxidation. Class-based fragmentation rules and associated PFAS transformation product libraries were generated and integrated into an automated non-targeted PFAS data analysis software (FluoroMatch). Fragmentation was additionally predicted for the potential transformation products of more than 2,500 PFAS in the EPA CompTox Chemicals Dashboard PFASSTRUCTv4. Generated mass spectral libraries were validated by applying FluoroMatch to a dataset of urine from aqueous film-forming foam (AFFF)-dosed mice. Toxicity predictions showed identified PFAS transformation products as potential developmental and mutagenic toxicants. This research enables more comprehensive PFAS characterization in biological systems which will improve assessment of exposures and evaluation of the associated health impacts.

Project description:Traditional toxicity testing has been unable to keep pace with the introduction of new chemicals into commerce. Consequently, there are limited or no toxicity data upon which to base a risk assessment for many chemicals to which fish and wildlife may be exposed. Per- and polyfluoroalkyl substances (PFAS) are emblematic of this issue in that most the ecological hazards of most PFAS remain uncharacterized. The present study employed a high throughput assay to identify the concentration at which 20 PFAS, with diverse properties, elicited a concerted gene expression response in larval fathead minnows (Pimephales promelas, 5-6 days post-fertilization) exposed for 24 h. Based on a reduced transcriptome approach that measured whole body expression of 1832 genes, the median transcriptomic point of departure (tPOD) for the 20 PFAS tested was 10 µM. Longer chain carboxylic acids (12-13 C-F) and an eight C-F di-alcohol, N-alkyl sulfonamide, and telomer sulfonic acid were among the most potent PFAS, eliciting gene expression responses at concentrations below 1 µM. With a few exceptions, larval fathead minnow tPODs were concordant with those based on whole transcriptome response in human cell lines. However, larval fathead minnow tPODs were often greater than those for Daphnia magna exposed to the same PFAS. The tPODs overlapped concentrations at which other sub-lethal effects have been reported in fish (available for 10 PFAS; including a range of species, life stages, and study designs). Nonetheless, fathead minnow tPODs were all orders of magnitude higher than aqueous PFAS concentrations detected in tributaries of the North American Great Lakes suggesting a substantial margin of safety in those systems, even for PFAS with significant potential for bioaccumulation. Overall, results broadly support the use of a fathead minnow larval transcriptomics assay to derive screening level potency estimates for use in ecological risk-based prioritization. Traditional toxicity testing has been unable to keep pace with the introduction of new chemicals into commerce. Consequently, there are limited or no toxicity data upon which to base a risk assessment for many chemicals to which fish and wildlife may be exposed. Per- and polyfluoroalkyl substances (PFAS) are emblematic of this issue in that most the ecological hazards of most PFAS remain uncharacterized. The present study employed a high throughput assay to identify the concentration at which 20 PFAS, with diverse properties, elicited a concerted gene expression response in larval fathead minnows (Pimephales promelas, 5-6 days post-fertilization) exposed for 24 h. Based on a reduced transcriptome approach that measured whole body expression of 1832 genes, the median transcriptomic point of departure (tPOD) for the 20 PFAS tested was 10 µM. Longer chain carboxylic acids (12-13 C-F) and an eight C-F di-alcohol, N-alkyl sulfonamide, and telomer sulfonic acid were among the most potent PFAS, eliciting gene expression responses at concentrations below 1 µM. With a few exceptions, larval fathead minnow tPODs were concordant with those based on whole transcriptome response in human cell lines. However, larval fathead minnow tPODs were often greater than those for Daphnia magna exposed to the same PFAS. The tPODs overlapped concentrations at which other sub-lethal effects have been reported in fish (available for 10 PFAS; including a range of species, life stages, and study designs). Nonetheless, fathead minnow tPODs were all orders of magnitude higher than aqueous PFAS concentrations detected in tributaries of the North American Great Lakes suggesting a substantial margin of safety in those systems, even for PFAS with significant potential for bioaccumulation. Overall, results broadly support the use of a fathead minnow larval transcriptomics assay to derive screening level potency estimates for use in ecological risk-based prioritization.

Project description:Background: Previous epidemiological studies have repeatedly found per- and polyfluoroalkyl substances (PFAS) exposure associated with higher circulating cholesterol, one of the greatest risk factors for development of coronary artery disease. The main route of cholesterol catabolism is through its conversion to bile acids, which circulate between the liver and ileum via enterohepatic circulation. Patients with coronary artery disease have decreased bile acid excretion, indicating that PFAS-induced changes of enterohepatic circulation may play a critical role in cardiovascular risk. Objectives: Using a mouse model with high LDL-VLDL cholesterol and aortic lesion development similar to humans, the current study investigates mechanisms linking exposure to a PFAS mixture with increased cholesterol. Methods: Male and female Ldlr-/- mice were fed an atherogenic diet (Clinton/Cybulsky low fat, 0.15% cholesterol) and exposed to a mixture of 5 PFAS representing legacy, replacement, and emerging subtypes (i.e., PFOA, PFOS, PFNA, PFHxS, GenX), each at a concentration of 2 mg/L, for 7 weeks. Blood was collected longitudinally for cholesterol measurements and mass spectrometry was used to measure circulating and fecal bile acids. Transcriptomic analysis of ileal samples was performed via RNA-sequencing. Results: After 7 weeks of PFAS exposure, average circulating PFAS levels were measured at 21.6, 20.1, 31.2, 23.5, and 1.5 µg/mL in PFAS-exposed females and 12.9, 9.7, 23, 14.3, and 1.7 µg/mL in PFAS-exposed males for PFOA, PFOS, PFHxS, PFNA, and GenX, respectively. PFAS exposure led to elevated circulating cholesterol levels after 7 weeks compared to vehicle mice, with females increasing 18% and males increasing 24%. Total circulating bile acid levels were elevated in PFAS-exposed mice by 230% in males and 290% in females compared to vehicle. PFAS decreased fecal bile acid levels by 62% in females and 59% in males. In the ileum, expression levels of the bile acid reuptake transporter ASBT were increased due to PFAS exposure. Discussion: Mice exposed to a PFAS mixture display increased circulating cholesterol and bile acids perhaps due to changes in enterohepatic circulation. This study implicates PFAS-mediated effects at the site of the ileum as a possible critical mediator of increased cardiovascular risk due to PFAS.

Project description:Human milk (breastmilk) is much more than nutrition for the infant, containing an array of regulatory agents with immunoprotective and developmental functions. Amongst those, microRNAs (miRNAs) have recently been identified, with their properties, roles, origin and distribution in breastmilk as well as in the mammary gland being still undetermined. In this study, we examined the miRNA profile of different fractions of human milk (cells and lipids) using the OpenArray system (Applied Biosystems, 770 miRNA species measured per sample) and compared it with maternal peripheral blood mononuclear cells (PBMCs) and plasma. Although PBMCs were the richest group in miRNA species, plasma showed very low expression pattern. Thus, the human milk fractions (cells, lipid) and skim milk (not being investigated in this study) were found to conserve higher levels of miRNAs than blood in general. Specifically, human milk cell miRNA quantity was found relatively close to PBMCs, and higher than milk lipids. Correlation and clustering analyses indicated that miRNA expression and types of milk cells were highly similar to those in lipids. Milk miRNAs showed a slight correlation to PBMCs, so PBMCs potentially are not contributing to milk miRNAs. Plasma was different to all other three groups in miRNA content and expression pattern. Further, two infant formulae (a plant-based and a cow milk-based) were compared to human milk and found to contain significantly fewer miRNA species than human milk cells and lipids (p>0.001). Taken together with previous studies on miRNAs, our findings demonstrate that human milk is one of the richest sources of miRNAs among human body fluids. As a non-invasive and plentiful source of miRNAs, human milk could be used as a disease biomarker for the mammary gland, with potential in assessing lactation performance. Finally, gene target and pathways analyses identified several target mRNAs regulated by miRNAs found to be abundant in breastmilk. Given the recently identified stability and function of food-derived miRNAs in regulating mammalian genes, we propose that breastmilk is a rich source of miRNA ingested by the infant during the first months of life, and which potentially contribute to early infant development. 10 exclusively breastfeeding dyads were recruited. 10 whole milk and 10 whole blood samples were collected and fractionated to obtain 10 milk cells, 10 milk lipid, 10 mononeucleoted blood cells (PBMCs), and 10 plasma. In addition to the above 40 samples, 2 infant formula were profiled. 4 different extraction kits were used, miRNeasy mini Kit for human milk cell and PBMC samples. miRCURY RNA Isolation-Biofluids Kit for human milk lipid samples and both infant formulae. mirVana PARIS Kit for plasma samples. NanoDrop 2000 and Bioanalyzer 2100 were used to determine concentration and purity of the extracted miRNA from all samples (n=42). miRNA OpenArray panel system (Life Technologies, CA, USA) was used to profile 754 human mature miRNAs in samples. RNU48, RNU44 and U6 rRNA were used as housekeeping controls for normalisation. ath-miR159a was used as a negative control for human samples. GeneGO and Ingenuity Pathway Analysis were used to determine biological pathways. Please note that normalization of miRNAs was done in R but without generating deltaCT values, thus [1] only the list of normalized miRNA with Ct vlaue between 8 and 29 and that detected in at least 4 samples out of 10 analysed in each group is provided ('normalized_miRNAs_list.txt') [2] the sample data tables contain raw data.

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Data for Maternal PFAS Transfer through Lactation: Dolphin Milk Reveals Routes of Early-Life Exposure

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