A realistic in vitro exposure revealed seasonal differences in (pro-)inflammatory effects from ambient air in Fribourg, Switzerland

Abstract

Ambient air pollutant levels vary widely in space and time, therefore thorough local evaluation of possible effects is needed. In vitro approaches using lung cell cultures grown at the air–liquid interface and directly exposed to ambient air can offer a reliable addition to animal experimentations and epidemiological studies. To evaluate the adverse effects of ambient air in summer and winter a multi-cellular lung model (16HBE14o-, macrophages, and dendritic cells) was exposed in a mobile cell exposure system. Cells were exposed on up to three consecutive days each 12 h to ambient air from Fribourg, Switzerland, during summer and winter seasons. Higher particle number, particulate matter mass, and nitrogen oxide levels were observed in winter ambient air compared to summer. Good cell viability was seen in cells exposed to summer air and short-term winter air, but cells exposed three days to winter air were compromised. Exposure of summer ambient air revealed no significant upregulation of oxidative stress or pro-inflammatory genes. On the opposite, the winter ambient air exposure led to an increased oxidative stress after two exposure days, and an increase in three assessed pro-inflammatory genes already after 12 h of exposure. We found that even with a short exposure time of 12 h adverse effects in vitro were observed only during exposure to winter but not summer ambient air. With this work we have demonstrated that our simple, fast, and cost-effective approach can be used to assess (adverse) effects of ambient air.

Keywords:

• Ambient summer and winter air
• in vitro
• multi-cellular lung model
• pro-inflammation
• oxidative stress
• realistic exposure
• 16HBE14o-cells
• mobile cell exposure chamber

Acknowledgements

We acknowledge the help and air pollutant data of Bernard Sturny, Amt für Umwelt, Staat Freiburg. We would also like to thank Dr. Gruenert (University of California, San Francisco) for providing the 16HBE14o-cell line. Further we would like to thank the BioNanomaterials group members at the Adolphe Merkle Institute, University of Fribourg, and Prof. em Peter Gehr, University of Bern for the constructive discussions to design the study. Last but not least we would like to thank Dr. Andreas Mayer (Technik Thermischer Maschinen, Niederrohrdorf), Dr. Norbert Heeb (EMPA Dübendorf), Dr. Loretta Müller (Children’s University hospital Basel), Pierre Comte, and Prof. Jan Czerwinski (both Bern University of Applied Sciences, Biel) for the continuous support and discussions about the project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by Adolphe Merkle Foundation; Bundesamt für Energie; Bundesamt für Umwelt; VERT association; Schweizer Erdölvereinigung; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung.