Grantee Research Project Results
Protein Binding Affinity as the Driver for Studying PFAS Mixture Toxicity
EPA Grant Number: R840456Title: Protein Binding Affinity as the Driver for Studying PFAS Mixture Toxicity
Investigators: Sepulveda, Maria , Gantz, JD , Hoskins, Tyler , Hoverman, Jason , Kar, Supratik , Lee, Linda S. , Leszczynski, Jerry
Current Investigators: Sepulveda, Maria , Lee, Linda S. , Gantz, JD , Hoskins, Tyler , Hoverman, Jason , Kar, Supratik
Institution: Purdue University , Hendrix College , Jackson State University
Current Institution: Purdue University , Jackson State University , Hendrix College , Kean University
EPA Project Officer: Aja, Hayley
Project Period: September 1, 2022 through August 31, 2025
Project Amount: $725,481
RFA: Development of Innovative Approaches to Assess the Toxicity of Chemical Mixtures Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: Computational Toxicology , Safer Chemicals , Health Effects , Human Health , PFAS Treatment , Chemical Safety for Sustainability , New Approach Methods (NAMs) , Mixtures , Predictive Toxicology , CSS
Description:
Environmental exposure to per and polyfluoroalkyl substances (PFAS) occurs as mixtures. Importantly, the bioaccumulation potential and toxicity of a particular mixture is driven by the number of halogenated carbons and functional groups present. PFAS are also highly proteinophilic and known to bind to proteins. Hemoglobins (Hbs) are key proteins responsible for transporting oxygen to tissues and studies show PFAS can bind with Hb interfering with oxygen transport. Chironomids (midges) are highly sensitive to PFAS and >95% of all their hemolymph proteins are Hbs. Using a combination of in silico, in vitro, and in vivo tools, this project will test the overarching hypothesis that binding of PFAS to Hbs is a tractable and sensitive physiological signal for predicting the toxicity of PFAS mixtures.
Objective:
Aim 1) Develop and parameterize mechanistic toxicity in silico models to determine whether the toxicity of PFAS mixtures deviates from additivity.
Aim 2) Inform and validate in silico models using PFAS and Hb binding affinity data.
Aim 3) Inform and validate in silico models using in vivo toxicity tests.
Approach:
Researchers will use protein docking and Quantitative Structure-Activity Relationship (QSAR) to model the interactions between two Hbs (Chironomus tentans and human) and single PFAS and their binary and tertiary mixtures. Using PFAS concentrations and ratios of mixtures found in surface and drinking water across the country, researchers will quantify the binding of single PFAS and their mixtures to Hbs using equilibrium dialysis and liquid chromatography mass spectrometry as well as spectroscopy. This data will be used to inform and validate computational models. Using C. tentans researchers will test the hypothesis that in silico models predict PFAS toxicity in vivo and result in concentration addition. First, the research team will validate QSAR models with single PFAS dose-response curves focused on quantifying changes in Hb (spectra, content, gene expression) and growth rates. Researchers will use this data to calculate effective concentrations for each PFAS and rank them by potency. The rankings will be compared to the modeling and protein binding results obtained under previous aims.
Expected Results:
The long-term goal is to produce sound, mechanistic toxicity data for PFAS mixtures to support human and environmental health risk assessment. The work is highly impactful and innovative as it will show whether a combination of protein PFAS modeling can be tractable to biological responses in an invertebrate animal model which is extremely sensitive to PFAS and easily and cheaply maintained under lab conditions. A major outcome of the work is to produce sound, mechanistic PFAS toxicity data that can be used to assess the effects of mixtures to support human and environmental health risk assessment. This is a huge need as it would be impossible to test all PFAS and their combinations using standard toxicity approaches. Specific outputs from our work include: 1) Development of a webserver for prediction of PFAS mixture toxicity; 2) Development of a novel, simple, cost-effective, and ecologically relevant approach for testing the toxicity of PFAS mixtures using midges; 3) Training of two post-doctoral researchers and undergraduate students; and 4) Presentations at conferences and a minimum of three peer-reviewed articles.
Publications and Presentations:
Publications have been submitted on this project: View all 4 publications for this projectJournal Articles:
Journal Articles have been submitted on this project: View all 1 journal articles for this projectSupplemental Keywords:
Computational toxicology, invertebrates, plasma, serum, circulating proteins, sediments, estuary, health effects, ecological effects, human health, metabolism, dose-response, animal, organism, cellular, population, stressor, chemicals, toxics, ecosystem, indicators, environmental chemistry, biology, ecology, genetics, pathology, modeling, analytical, surveys, Great Lakes, Midwest.
Progress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.