103 Tyre Wear Particle Sampling Position During Real-World Driving Impacts Bioreactivity on Human Lung Alveolar Epithelial Cells in Vitro

Abstract

Abstract Tyre wear particles (TWPs) are a predominant component of particulate air pollution from road transport and emissions may increase in future due to increasing use of heavier cars. We hypothesized that inhaled respirable TWPs would have adverse effects on human lung alveolar epithelium, which would differ between alveolar type 1 (AT1; gas exchanging) and type 2 (AT2; secretory) cells. Two real-time road-generated samples were each collected into Milli-Q water using custom-made apparatus whilst driving a car for 2h: S1) high, behind the tyre (“pure” TWP) and S2) low, sideways to the tyre (mixed TWP/brake/road wear). Alveolar epithelial type 1-like (AT1L) and type 2-like (AT2L) cell lines were exposed for 24h to each TWP sample at 62.5-250µg/ml. The response differed between AT1L and AT2L cells. AT1L cell viability/metabolism and cytotoxity (MTT/LDH assays) were unaffected by either TWP sample, whereas AT2L cell metabolic activity increased (MTT measures metabolic activity) at all concentrations of TWP, ~20%-30% (p<0.01). S1 induced IL-6 mediator release (~5-fold; p<0.0001) and IL-8 mediator release (~2.2-fold; p<0.01) by AT1L cells, whereas S2 did not. S1 and S2 induced IL-6 (S1, ~10-fold, p<0.0001: S2, ~4-fold, p<0.0001) and IL-8 (S1, ~4-fold, p<0.0001: S2, ~2-fold, p<0.0001) release by AT2L cells, thus mediator release was significantly greater for S1 and greater than for AT1L cells. These data indicate that AT2L cells were more sensitive to TWP than AT1L cells; the “pure” TWP were significantly more bioreactive than the mixed TWP/brake/road wear particles.