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Qin W, Escher BI, Huchthausen J, Fu Q, Henneberger L. Species Difference? Bovine, Trout, and Human Plasma Protein Binding of Per- and Polyfluoroalkyl Substances. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9954-9966. [PMID: 38804966 PMCID: PMC11171458 DOI: 10.1021/acs.est.3c10824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 05/03/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) strongly bind to proteins and lipids in blood, which govern their accumulation and distribution in organisms. Understanding the plasma binding mechanism and species differences will facilitate the quantitative in vitro-to-in vivo extrapolation and improve risk assessment of PFAS. We studied the binding mechanism of 16 PFAS to bovine serum albumin (BSA), trout, and human plasma using solid-phase microextraction. Binding of anionic PFAS to BSA and human plasma was found to be highly concentration-dependent, while trout plasma binding was linear for the majority of the tested PFAS. At a molar ratio of PFAS to protein ν < 0.1 molPFAS/molprotein, the specific protein binding of anionic PFAS dominated their human plasma binding. This would be the scenario for physiological conditions (ν < 0.01), whereas in in vitro assays, PFAS are often dosed in excess (ν > 1) and nonspecific binding becomes dominant. BSA was shown to serve as a good surrogate for human plasma. As trout plasma contains more lipids, the nonspecific binding to lipids affected the affinities of PFAS for trout plasma. Mass balance models that are parameterized with the protein-water and lipid-water partitioning constants (chemical characteristics), as well as the protein and lipid contents of the plasma (species characteristics), were successfully used to predict the binding to human and trout plasma.
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Affiliation(s)
- Weiping Qin
- Department
of Cell Toxicology, UFZ—Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, Schnarrenbergstr. 94-96, DE-72076 Tübingen, Germany
| | - Beate I. Escher
- Department
of Cell Toxicology, UFZ—Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, Schnarrenbergstr. 94-96, DE-72076 Tübingen, Germany
| | - Julia Huchthausen
- Department
of Cell Toxicology, UFZ—Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, Schnarrenbergstr. 94-96, DE-72076 Tübingen, Germany
| | - Qiuguo Fu
- Department
of Environmental Analytical Chemistry, UFZ—Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
| | - Luise Henneberger
- Department
of Cell Toxicology, UFZ—Helmholtz
Centre for Environmental Research, 04318 Leipzig, Germany
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Qin W, Henneberger L, Glüge J, König M, Escher BI. Baseline Toxicity Model to Identify the Specific and Nonspecific Effects of Per- and Polyfluoroalkyl Substances in Cell-Based Bioassays. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:5727-5738. [PMID: 38394616 PMCID: PMC10993398 DOI: 10.1021/acs.est.3c09950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/11/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024]
Abstract
High-throughput screening is a strategy to identify potential adverse outcome pathways (AOP) for thousands of per- and polyfluoroalkyl substances (PFAS) if the specific effects can be distinguished from nonspecific effects. We hypothesize that baseline toxicity may serve as a reference to determine the specificity of the cell responses. Baseline toxicity is the minimum (cyto)toxicity caused by the accumulation of chemicals in cell membranes, which disturbs their structure and function. A mass balance model linking the critical membrane concentration for baseline toxicity to nominal (i.e., dosed) concentrations of PFAS in cell-based bioassays yielded separate baseline toxicity prediction models for anionic and neutral PFAS, which were based on liposome-water distribution ratios as the sole model descriptors. The specificity of cell responses to 30 PFAS on six target effects (activation of peroxisome proliferator-activated receptor (PPAR) gamma, aryl hydrocarbon receptor, oxidative stress response, and neurotoxicity in own experiments, and literature data for activation of several PPARs and the estrogen receptor) were assessed by comparing effective concentrations to predicted baseline toxic concentrations. HFPO-DA, HFPO-DA-AS, and PFMOAA showed high specificity on PPARs, which provides information on key events in AOPs relevant to PFAS. However, PFAS were of low specificity in the other experimentally evaluated assays and others from the literature. Even if PFAS are not highly specific for certain defined targets but disturb many toxicity pathways with low potency, such effects are toxicologically relevant, especially for hydrophobic PFAS and because PFAS are highly persistent and cause chronic effects. This implicates a heightened need for the risk assessment of PFAS mixtures because nonspecific effects behave concentration-additive in mixtures.
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Affiliation(s)
- Weiping Qin
- Department
of Cell Toxicology, UFZ−Helmholtz
Centre for Environmental Research, Leipzig 04318, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, Schnarrenbergstr. 94-96, Tübingen DE-72076, Germany
| | - Luise Henneberger
- Department
of Cell Toxicology, UFZ−Helmholtz
Centre for Environmental Research, Leipzig 04318, Germany
| | - Juliane Glüge
- Department
of Cell Toxicology, UFZ−Helmholtz
Centre for Environmental Research, Leipzig 04318, Germany
- Institute
of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Zürich 8092, Switzerland
| | - Maria König
- Department
of Cell Toxicology, UFZ−Helmholtz
Centre for Environmental Research, Leipzig 04318, Germany
| | - Beate I. Escher
- Department
of Cell Toxicology, UFZ−Helmholtz
Centre for Environmental Research, Leipzig 04318, Germany
- Environmental
Toxicology, Department of Geosciences, Eberhard
Karls University Tübingen, Schnarrenbergstr. 94-96, Tübingen DE-72076, Germany
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Ford LC, Lin HC, Tsai HHD, Zhou YH, Wright FA, Sedykh A, Shah RR, Chiu WA, Rusyn I. Hazard and risk characterization of 56 structurally diverse PFAS using a targeted battery of broad coverage assays using six human cell types. Toxicology 2024; 503:153763. [PMID: 38423244 DOI: 10.1016/j.tox.2024.153763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/13/2024] [Accepted: 02/23/2024] [Indexed: 03/02/2024]
Abstract
Per- and poly-fluoroalkyl substances (PFAS) are extensively used in commerce leading to their prevalence in the environment. Due to their chemical stability, PFAS are considered to be persistent and bioaccumulative; they are frequently detected in both the environment and humans. Because of this, PFAS as a class (composed of hundreds to thousands of chemicals) are contaminants of very high concern. Little information is available for the vast majority of PFAS, and regulatory agencies lack safety data to determine whether exposure limits or restrictions are needed. Cell-based assays are a pragmatic approach to inform decision-makers on potential health hazards; therefore, we hypothesized that a targeted battery of human in vitro assays can be used to determine whether there are structure-bioactivity relationships for PFAS, and to characterize potential risks by comparing bioactivity (points of departure) to exposure estimates. We tested 56 PFAS from 8 structure-based subclasses in concentration response (0.1-100 μM) using six human cell types selected from target organs with suggested adverse effects of PFAS - human induced pluripotent stem cell (iPSC)-derived hepatocytes, neurons, and cardiomyocytes, primary human hepatocytes, endothelial and HepG2 cells. While many compounds were without effect; certain PFAS demonstrated cell-specific activity highlighting the necessity of using a compendium of in vitro models to identify potential hazards. No class-specific groupings were evident except for some chain length- and structure-related trends. In addition, margins of exposure (MOE) were derived using empirical and predicted exposure data. Conservative MOE calculations showed that most tested PFAS had a MOE in the 1-100 range; ∼20% of PFAS had MOE<1, providing tiered priorities for further studies. Overall, we show that a compendium of human cell-based models can be used to derive bioactivity estimates for a range of PFAS, enabling comparisons with human biomonitoring data. Furthermore, we emphasize that establishing structure-bioactivity relationships may be challenging for the tested PFAS.
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Affiliation(s)
- Lucie C Ford
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Hsing-Chieh Lin
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Han-Hsuan D Tsai
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Yi-Hui Zhou
- Department of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA
| | - Fred A Wright
- Department of Biological Sciences and Statistics, North Carolina State University, Raleigh, NC 27695, USA; Bioinformatics Research Center, North Carolina State University, Raleigh, NC 27695, USA
| | | | | | - Weihsueh A Chiu
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA
| | - Ivan Rusyn
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA.
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Fischer FC, Ludtke S, Thackray C, Pickard HM, Haque F, Dassuncao C, Endo S, Schaider L, Sunderland EM. Binding of Per- and Polyfluoroalkyl Substances (PFAS) to Serum Proteins: Implications for Toxicokinetics in Humans. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:1055-1063. [PMID: 38166384 PMCID: PMC11149785 DOI: 10.1021/acs.est.3c07415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a diverse class of highly persistent anthropogenic chemicals that are detectable in the serum of most humans. PFAS exposure has been associated with many adverse effects on human health including immunotoxicity, increased risk of certain cancers, and metabolic disruption. PFAS binding to the most abundant blood serum proteins (human serum albumin [HSA] and globulins) is thought to affect transport to active sites, toxicity, and elimination half-lives. However, few studies have investigated the competitive binding of PFAS to these proteins in human serum. Here, we use C18 solid-phase microextraction fibers to measure HSA-water and globulin-water distribution coefficients (DHSA/w, Dglob/w) for PFAS with carbon chains containing 4 to 13 perfluorinated carbons (ηpfc = 4-13) and several functional head-groups. PFAS with ηpfc < 7 were highly bound to HSA relative to globulins, whereas PFAS with ηpfc ≥ 7 showed a greater propensity for binding to globulins. Experimentally measured DHSA/w and Dglob/w and concentrations of serum proteins successfully predicted the variability in PFAS binding in human serum. We estimated that the unbound fraction of serum PFAS varied by up to a factor of 2.5 among individuals participating in the 2017-2018 U.S. National Health and Nutrition Examination Survey. These results suggest that serum HSA and globulins are important covariates for epidemiological studies aimed at understanding the effects of PFAS exposure.
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Affiliation(s)
- Fabian Christoph Fischer
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Sophia Ludtke
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Colin Thackray
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Heidi M Pickard
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Faiz Haque
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Clifton Dassuncao
- Eastern Research Group, Inc. (ERG), Arlington, Virginia 22201, United States
| | - Satoshi Endo
- National Institute for Environmental Studies (NIES), Health and Environmental Risk Division, Onogawa 16-2, Tsukuba, Ibaraki 305-8506, Japan
| | - Laurel Schaider
- Silent Spring Institute, Newton, Massachusetts 02460, United States
| | - Elsie M Sunderland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, Cambridge, Massachusetts 02138, United States
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Pye ES, Wallace SE, Marangoni DG, Foo ACY. Albumin Proteins as Delivery Vehicles for PFAS Contaminants into Respiratory Membranes. ACS OMEGA 2023; 8:44036-44043. [PMID: 38027323 PMCID: PMC10666230 DOI: 10.1021/acsomega.3c06239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/20/2023] [Accepted: 10/25/2023] [Indexed: 12/01/2023]
Abstract
Poly- and perfluoroalkyl substances (PFAS) are a family of chemicals that have been used in a wide range of commercial products. While their use is declining, the prevalence of PFAS, combined with their chemical longevity, ensures that detectable levels will remain in the environment for years to come. As such, there is a pressing need to understand how PFAS contaminants interact with other elements of the human exposome and the consequences of these interactions for human health. Using serum albumin as a model system, we show that proteins can bind PFAS contaminants and facilitate their incorporation into model pulmonary surfactant systems and lipid bilayers. Protein-mediated PFAS delivery significantly altered the structure and function of both model membrane systems, potentially contributing to respiratory dysfunction and airway diseases in vivo. These results provide valuable insights into the synergistic interaction between PFAS contaminants and other elements of the human exposome and their potential consequences for human health.
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Affiliation(s)
- Evan S. Pye
- Dept. of Chemistry, St. Francis Xavier University, 2321 Notre Dame Avenue, Antigonish B2G 2W5, Nova Scotia, Canada
| | - Shannon E. Wallace
- Dept. of Chemistry, St. Francis Xavier University, 2321 Notre Dame Avenue, Antigonish B2G 2W5, Nova Scotia, Canada
| | - D. Gerrard Marangoni
- Dept. of Chemistry, St. Francis Xavier University, 2321 Notre Dame Avenue, Antigonish B2G 2W5, Nova Scotia, Canada
| | - Alexander C. Y. Foo
- Dept. of Chemistry, St. Francis Xavier University, 2321 Notre Dame Avenue, Antigonish B2G 2W5, Nova Scotia, Canada
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Huchthausen J, König M, Escher BI, Henneberger L. Experimental exposure assessment for in vitro cell-based bioassays in 96- and 384-well plates. FRONTIERS IN TOXICOLOGY 2023; 5:1221625. [PMID: 37564394 PMCID: PMC10411540 DOI: 10.3389/ftox.2023.1221625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
In vitro cell-based bioassays have great potential for applications in the human health risk assessment of chemicals. The quantification of freely dissolved concentrations (C free) in in vitro assays is essential to generate reliable data for in vitro-to-in vivo extrapolation. Existing methods for the quantification of C free are limited to low-throughput microtiter plates. The present study is a proof of principle for the applicability of a solid-phase microextraction (SPME) method for the determination of C free in the peroxisome proliferator-activated receptor gamma (PPARγ) bioassay run in 384-well plates with 80 µL medium per well. The effect concentrations obtained from 384-well plates were compared with those obtained from 96-well plates in a previous study. Nominal effect concentrations obtained using 96- and 384-well plates agreed with each other within a factor of three, and freely dissolved effect concentrations agreed within a factor of 6.5. The good degree of agreement in the results from both plate formats proves the general applicability of the SPME method for the determination of C free for bioassays in 384-well plates, making the present study a first step toward exposure assessment in high-throughput bioassays.
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Affiliation(s)
- Julia Huchthausen
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
| | - Maria König
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
| | - Beate I. Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
- Department of Geosciences, Environmental Toxicology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
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