Air Liquid Interface (ALI) system: genotoxic and inflammatory profile of BEAS-2B exposed in Bologna, Italy

The study of the detrimental health effects caused by the exposure to air pollutants has mainly been carried out through epidemiological studies or toxicological in vitro techniques. Limitation of in vitro model resides in the challenge to use a highly realistic in vitro exposure set of conditions that mimics what really happens in the respiratory system, following particulate matter (PM) exposure. In order to obtain a higher similarity with a real cellular response, in recent years a new methodology has been developed. The Air Liquid Interface (ALI) exposure allows in vitro models treatment directly to ambient air pollutants for the evaluation of their effects, bypassing the steps of filter collection, extraction, and solubilisation in cellular medium. This study was performed in an urban site of Bologna (Italy) in 10 different days in the framework of the PRIN-RHAPS project. The human bronchial epithelial cell line BEAS-2B was exposed at the ALI for 24 hours. Three inserts out of six were exposed to clean filtered air, while the others were exposed directly to air pollutant passing by a cyclone selecting PM1 fraction. The genotoxic evaluation was carried out via Comet assay, and to have a complete picture of the damage induced by the air exposure, a modified test, relying on the properties of endonuclease enzymes (ENDO III, FPG, ENDO V), was applied. In parallel, the release of the pro-inflammatory cytokine interleukin 8 (IL-8) was evaluated by a commercially available ELISA kit. Results showed differences in the biological responses both in the DNA damage and in IL-8 secretion. The results revealed the presence of DNA damage in most of the days evaluated. The use of ENDOIII and FPG enzymes in the Comet assay highlighted also the presence of oxidative damage. Although the analysis is still on-going, results indicate that changes in sources and/or components of air pollution may determine specific biological responses. In agreement with literature, the methodology here applied permits to study relevant biological responses in in vitro models directly exposed to air pollutants, under conditions relevant for human exposure. The use of ALI also allows to evaluate the day-by-day variability of air pollution, and has proved useful to assess health effects associated to the exposure to aerosol particles, down to the ultrafine particle size range. This work has been funded by the Italian Ministry of the University under the PRIN2017 RHAPS project (grant number: 2017MSN7M8).