Grantee Research Project Results
2024 Progress Report: Development of a quantitative adverse outcome pathway (qAOP) network to assess neurodevelopmental toxicity of per- and polyfluoroalkyl substances (PFAs) mixture in C. elegans
EPA Grant Number: R840453Title: Development of a quantitative adverse outcome pathway (qAOP) network to assess neurodevelopmental toxicity of per- and polyfluoroalkyl substances (PFAs) mixture in C. elegans
Investigators: Tang, Lili , Huang, Qingguo , Wang, Jia-Sheng , Shen, Ye
Institution: University of Georgia
EPA Project Officer: Aja, Hayley
Project Period: September 1, 2022 through May 13, 2025
Project Period Covered by this Report: September 1, 2023 through August 31,2024
Project Amount: $750,000
RFA: Development of Innovative Approaches to Assess the Toxicity of Chemical Mixtures Request for Applications (RFA) (2022) RFA Text | Recipients Lists
Research Category: CSS , Chemical Safety for Sustainability , Children's Health , Endocrine Disruptors , Health Effects , Heavy Metal Contamination of Soil/Water , Human Health , Mixtures , New Approach Methods (NAMs) , Non-Vertebrate Animal Testing , PFAS Treatment , Safer Chemicals , Urban Air Toxics
Objective:
This project aims to development a quantitative AOP network with advanced mixtures risk assessment for assessing developmental neurotoxicity (DNT) of per- and polyfluoroalkyl substances (PFAS) mixture at multiple levels of biological organization using the nematode C. elegans, which can be integrated in a manner useful to hazard and /or risk assessment. The objective will be achieved through the following tasks to: 1) construct an environmentally relevant and representative PFAs reference mixture, which is the top 10 most abundant PFAS derived from the currently available data and analysis generated by Dr. Huang’s laboratory (Co- PI of the project); 2) conduct systematic experiments to evaluate DNT of individual PFAS and reference mixture in C. elegans, which to develop qAOP network for providing much more precision for mixture assessment; 3) perform assessment of whole mixture in water samples by evaluating sufficient similarity to the reference mixture.
Progress Summary:
During this reporting period, we successfully completed the DNT evaluation for individuals and combined PFAS , and published two peer-review journal papers, with two additional papers currently under-review. We first investigated the impact of early life exposure to individuals and combined PFAS on learning, memory, and bioaccumulation in C. elegans. In this study, eleven highly prevalent PFAS and a reference mixture were selected according to various drinking water sources. The nematode, Caenorhabditis elegans, were exposed to PFAS at 0.1, 1, 10, 100, and 200μM, and the toxic effects on learning & memory along with the bioaccumulation were investigated using a high-throughput screening (HTS) platform. Our results showed that PFOS and PFBS exhibited significant inhibitory effects (p<0.05) on learning and memory in both time points at concentrations between 100-200 μmol/L. Then, we selected five PFAS compounds, representing typical daily exposure levels in the United States, including perfluoroalkyl carboxylic acids (PFBA, PFOA) and sulfonic acids (PFBS, PFHxS, PFOS) to determine the integrative mechanisms of the toxic response using transcriptomics sequencing analysis. L1 C. elegans exposed to individual PFAS or a mixture at 0, 5, and 50 ppm for 48 h. There are 2, 12, 8, 6, and 9 signaling pathways identified as being influenced by the DEGs in PFBS, PFOS, PFHxS, PFOA, and PFBA, respectively. The two down regulated pathways, MAPK signaling pathway and metabolic pathways, were identified in multiple individual PFAS and the reference mixture. To extend the scope of analysis, commonly differentially expressed neuronal genes induced by PFAS at 50 ppm levels were categorized based on GO terms. Among them, four genes, aex-1, glna-2, unc-112, and lgc-43 engaged in synaptic development and function. Three of the neuronal related genes, rict-1, dyf-1 and hlh-30, are related in neuron structure. Notably, all these genes were also identified as DEGs within the mixture exposure, indicating their relevance to combined PFAS effects.
Finally, we developed an Artificial intelligence based high-throughput & high-content (HTHC) platform for accessing the effects of PFAS on the neuron morphology. Using this platform, our results demonstrated that 6:2 FTS, HFPO-DA, PFBA, PFBS, PFHxA, and PFOS significantly inhibited dopaminergic neuron activity in synchronized L1-stage worms, with fluorescence intensity reductions observed at concentrations ranging from 0.1 to 100 μmol/L.
Future Activities:
In the subsequent reporting period, the quantitative Adverse Outcome Pathway (qAOP) of PFAS-induced DNT will be assembled based on the toxicity data from Objective 1 and 2. The established causal relationships between the Molecular Initiating Event (MIE), KEs, and AO will be estimated to be using a Bayesian network (BN) model. Additionally, to evaluate the sufficient similarity of water PFAS mixtures, the water samples from diverse sources will be collected and concentrated according to EPA draft method 1633. An advanced approach, which will integrate non-targeted PFAS analysis, 2 CKE (common key events) and AO (adverse outcome, behavior impairment), will be used to determine similarity through hierarchical clustering.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 2 publications | 2 publications in selected types | All 2 journal articles |
|---|
| Type | Citation | ||
|---|---|---|---|
|
|
Currie SD, Ji Y, Huang Q, Wang JS, Tang L. The Impact of Early Life Exposure to Individual and Combined PFAS on Learning, Memory, and Bioaccumulation in C. elegans. Environmental Pollution. 2024 Nov:125257. |
R840453 (2024) |
Exit |
Supplemental Keywords:
PFAS, qAOP, Mixtures Assessment, Developmental Neurotoxicity, C. elegansProgress and Final Reports:
Original AbstractThe 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.