Abstract
Introduction: Airborne fine particulate matter (diameter <2.5μm; PM2.5) is a leading risk factor for lung disease. Improved exhaust technology and car electrification are decreasing exhaust-derived PM emissions but without a similar decrease in poorly characterised, unregulated “non-exhaust” PM, predominantly brakewear PM (BWPM). This study aimed to characterise the toxicology of PM2.5 from 4 brake pad types compared to roadwear and diesel exhaust (DEP).
Methods: An alveolar type-II epithelial cell line (ATIIER:KRASV12) was exposed to 12.5-100µg/ml PM2.5 from 4 brake pad types (low-metallic, semi-metallic, non-asbestos organic, ceramic), roadwear, or DEP for 2, 6 or 24hrs. Cytotoxicity was measured by LDH/MTT assays. Cytokine release (IL-6, IL-8) was assayed by ELISA. ROS generation was assessed using DCFDA. Expression of antioxidant gene haemoxygenase-1 (HMOX1) and metal-binding metallothionein 1G and 2A (MT1G, MT2A) was determined by RT-qPCR.
Results: Exposure to all PM2.5 types elicited concentration-dependent increases in both cytotoxicity, IL-6/IL-8 release, and ROS generation with non-asbestos organic and ceramic BWPM being the most potent inducers of these endpoints. Furthermore, at non-cytotoxic concentrations, only the non-asbestos organic and ceramic BWPM elicited significant upregulation of genes involved in oxidative stress (HMOX1), metal-binding (MT1G/MT2A), and inflammation (IL-6, IL-8).
Conclusions: ATIIER:KRASV12 responses were dependent on PM source, with non-asbestos organic and ceramic BWPM most potent. Future work will further characterise the cellular effects of these PM types and how these relate mechanistically to their composition.
Footnotes
Cite this article as ERJ Open Research 2022; 8: Suppl. 8, 188.
This article was presented at the 2022 ERS Lung Science Conference, in session “Poster Session 2”.
This is an ERS Lung Science Conference abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
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