Legacy and emerging per- and polyfluoroalkyl substances suppress the neutrophil respiratory burst

Abstract

Per- and polyfluoroalkyl substances (PFASs) are used in a multitude of processes and products, including nonstick coatings, food wrappers, and fire-fighting foams. These chemicals are environmentally-persistent, ubiquitous, and can be detected in the serum of 98% of Americans. Despite evidence that PFASs alter adaptive immunity, few studies have investigated their effects on innate immunity. The report here presents results of studies that investigated the impact of nine environmentally-relevant PFASs [e.g. perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid potassium salt (PFOS-K), perfluorononanoic acid (PFNA), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 7H-perfluoro-4-methyl-3,6-dioxa-octane sulfonic acid (Nafion byproduct 2), and perfluoromethoxyacetic acid sodium salt (PFMOAA-Na)] on one component of the innate immune response, the neutrophil respiratory burst. The respiratory burst is a key innate immune process by which microbicidal reactive oxygen species (ROS) are rapidly induced by neutrophils in response to pathogens; defects in the respiratory burst can increase susceptibility to infection. The study here utilized larval zebrafish, a human neutrophil-like cell line, and primary human neutrophils to ascertain whether PFAS exposure inhibits ROS production in the respiratory burst. It was observed that exposure to PFHxA and GenX suppresses the respiratory burst in zebrafish larvae and a human neutrophil-like cell line. GenX also suppressed the respiratory burst in primary human neutrophils. This report is the first to demonstrate that these PFASs suppress neutrophil function and support the utility of employing zebrafish larvae and a human cell line as screening tools to identify chemicals that may suppress human immune function.

Keywords:

• Innate immunity
• neutrophils
• per- and polyfluoroalkyl substances (PFAS)
• reactive oxygen species
• zebrafish

Acknowledgments

The authors thank Ashley M. Connors (NC State University) for critical review of the manuscript, volunteer donors for their time and blood for ex vivo studies, and the North Carolina State University Center for Human Health and the Environment Comparative Pathology Core for assistance with cytology experiments.

Author contributions

DWP and JAY contributed to study conception. DWP, MKS, SWK, JCD and JAY contributed to study design. Material preparation and data collection were performed by DWP, AIP, HEC, GF, JHD, KEL and MKS. Data analyses were performed by DWP and DMR aided in statistical analysis. The first manuscript draft was written by DWP. All authors commented on previous versions of the manuscript, and read and approved the final manuscript. SWK, JCD, MKS and JAY secured funding for this study. JAY supervised the completion of the project

Disclosure statement

DWP was paid a one-time fee by the Center for Environmental Health (Oakland, CA, USA) for serving as a scientific advisor (May 2019–August 2022) to aid in writing a petition under the Toxic Substances Control Act to the United States Environmental Protection Agency, regarding testing of certain PFASs. JCD serves/has served as a plaintiff’s expert witness for several court cases involving PFAS manufacturers. All other authors declare no competing interests relevant to the content of this article.

Data availability

Raw data from zebrafish developmental toxicity assays, cell viability assays, respiratory burst assays, and ToxPi analysis are freely-available through the Dryad database at doi: https://doi.org/10.5061/dryad.qjq2bvqj4.

Additional information

Funding

Research reported here was supported by the National Institute of Environmental Health Sciences (NIEHS) of the United States National Institutes of Health (NIH) (P42 ES031009 [DMR, SWK, JCD, JAY]) and the North Carolina State University Center for Human Health and the Environment (P30 ES025128 [MKS and JAY]). DWP was supported by a NIH Biotechnology Traineeship (T32 GM008776). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.