On the dose-response association of fine and ultrafine particles in an urban atmosphere: toxicological outcomes on bronchial cells at realistic doses of exposure at the Air Liquid Interface

• Published in: Chemosphere (Oxford) 2024-10, Vol.366, p.143417, Article 143417
• Main Authors: Gualtieri, M., Melzi, G., Costabile, F., Stracquadanio, M., La Torretta, T., Di Iulio, G., Petralia, E., Rinaldi, M., Paglione, M., Decesari, S., Mantecca, P., Corsini, E.
• Format: Article
• Language: English
• Subjects: Aerosol direct exposure; Air liquid interface lung model; Air Pollutants - analysis; Air Pollutants - toxicity; Air Pollution - statistics & numerical data; Atmosphere - chemistry; Bronchi - cytology; Cell Line; Comet assay; DNA Damage; Dose-response associations; Dose-Response Relationship, Drug; Epithelial Cells - drug effects; Humans; Interleukin-8 - metabolism; Particle Size; Particulate Matter - analysis; Particulate Matter - toxicity; Ultrafine particles toxicity
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.143417

Air pollution and particulate matter (PM) are the leading environmental cause of death worldwide. Exposure limits have lowered to increase the protection of human health; accordingly, it becomes increasingly important to understand the toxicological mechanisms on cellular models at low airborne PM concentrations which are relevant for actual human exposure. The use of air liquid interface (ALI) models, which mimic the interaction between airborne pollutants and lung epithelia, is also gaining importance in inhalation toxicological studies. This study reports the effects of ALI direct exposure of bronchial epithelial cells BEAS-2B to ambient PM1 (i.e. particles with aerodynamic diameter lower than 1 μm). Gene expression (HMOX, Cxcl-8, ATM, Gadd45-a and NQO1), interleukin (IL)-8 release, and DNA damage (Comet assay) were evaluated after 24 h of exposure. We report the dose-response curves of the selected toxicological outcomes, together with the concentration-response association and we show that the two curves differ for specific responses highlighting that concentration-response association may be not relevant for understanding toxicological outcomes. Noteworthy, we show that pro-oxidant effects may be driven by the deposition of freshly emitted particles, regardless of the airborne PM1 mass concentration. Furthermore, we show that reference airborne PM1 metrics, namely airborne mass concentration, may not always reflect the toxicological process triggered by the aerosol. These findings underscore the importance of considering different aerosol metrics to assess the toxicological potency of fine and ultrafine particles. To better protect human health additional metrics should be defined, than account for the properties of the entire aerosol mixture including specific as particle size (i.e. particles with aerodynamic diameter lower than 20 nm), the relevant aerosol sources (e.g., traffic combustion, secondary organic aerosol …) as well as their atmospheric processing (freshly emitted vs aged ones). [Display omitted] •Oxidative responses are induced by freshly emitted combustion particles.•DNA damage responses are associated to organic aerosol species.•To be protective for health mass or number metrics must be associated with composition/aging information.•The black carbon to organic carbon ratio is a good proxy for composition/aging and relevant to understanding PM toxicology.•Effects reported as dose-response curves may differ from concentration-response o