Pulmonary exposure of mice to ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX) suppresses the innate immune response to carbon black nanoparticles and stimulates lung cell proliferation

Abstract

Background

Per- and polyfluoroalkyl substances (PFAS) have been associated with respiratory diseases in humans, yet the mechanisms through which PFAS cause susceptibility to inhaled agents is unknown. Herein, we investigated the effects of ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), an emerging PFAS, on the pulmonary immune response of mice to carbon black nanoparticles (CBNP). We hypothesized that pulmonary exposure to GenX would increase susceptibility to CBNP through suppression of innate immunity.

Methods

Male C57BL/6 mice were exposed to vehicle, 4 mg/kg CBNP, 10 mg/kg GenX, or CBNP and GenX by oropharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) was collected at 1 and 14 days postexposure for cytokines and total protein. Lung tissue was harvested for histopathology, immunohistochemistry (Ki67 and phosphorylated (p)-STAT3), western blotting (p-STAT3 and p-NF-κB), and qRT-PCR for cytokine mRNAs.

Results

CBNP increased CXCL-1 and neutrophils in BALF at both time points evaluated. However, GenX/CBNP co-exposure reduced CBNP-induced CXCL-1 and neutrophils in BALF. Moreover, CXCL-1, CXCL-2 and IL-1β mRNAs were increased by CBNP in lung tissue but reduced by GenX. Western blotting showed that CBNP induced p-NF-κB in lung tissue, while the GenX/CBNP co-exposed group displayed decreased p-NF-κB. Furthermore, mice exposed to GenX or GenX/CBNP displayed increased numbers of BALF macrophages undergoing mitosis and increased Ki67 immunostaining. This was correlated with increased p-STAT3 by western blotting and immunohistochemistry in lung tissue from mice co-exposed to GenX/CBNP.

Conclusions

Pulmonary exposure to GenX suppressed CBNP-induced innate immune response in the lungs of mice yet promoted the proliferation of macrophages and lung epithelial cells.

Keywords:

• Carbon black
• nanoparticles
• PFAS
• lung
• immunity

Acknowledgments

The authors thank Michael Abraczinskas at the North Carolina Department of Environmental Quality for helpful comments related to release of airborne GenX during the preparation of this manuscript. We are grateful to Dereje Jima for input and advice on statistical analysis. We thank Nicholas Pankow in the Pathology Services Core at the University of North Carolina at Chapel Hill for expert technical assistance with tissue sectioning for histopathology.

Disclosure statement

The authors do not have any conflict of interest to report.

Additional information

Funding

Research reported in this publication was supported by the National Institute of Environmental Health Sciences (NIEHS) grant P30ES025128 and NIEHS grant R01ES032443. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. HYL was supported by NIEHS Training Grant T32ES007046. LMR and GDC in the Pathology Services Core at the University of North Carolina at Chapel Hill were supported in part by NCI Center Core Support Grant 5P30CA016080-42.