Toxic effects of brake wear particles on epithelial lung cells in vitro

Fine particulate matter originating from traffic correlates with increased morbidity and mortality. An important source of traffic particles is brake wear of cars which contributes up to 20% of the total traffic emissions.

The aim of this study was to evaluate potential toxicological effects of human epithelial lung cells exposed to freshly generated brake wear particles.

Results: An exposure-box was mounted around a car's braking system. Lung cells cultured at the air-liquid interface were then exposed to particles emitted from two typical braking behaviours (full stop and normal deceleration).

The particle size distribution as well as the brake emission components like metals and carbons were measured on-line, and the particles deposited on grids for transmission electron microscopy were counted. The actin cytoskeleton as well as the tight junction arrangement was observed by laser scanning microscopy.

Cellular responses were assessed by investigating the production of reactive oxidative species and the inflammatory cytokine interleukin-8. The tight junction protein occludin density decreased significantly (p <0.05) with increasing concentrations of metals on the particles (iron, copper and manganese, whichwere all strongly correlated with each other).

Occludin was also negatively correlated with the intensity of reactive oxidative species. Increasing concentrations of interleukin-8 were significantly correlated with increasing organic carbon concentrations.

No correlation was observed between occludin and interleukin-8, nor between reactive oxidative species and interleukin-8.

Conclusions: These findings suggest that the metals on brake wear particles damage tight junctions with a mechanism involving oxidative stress. Brake wear particles also increase inflammation.

However, this might be due to another mechanism than via oxidative stress.

Author: Michael GasserMichael RiedikerLoretta MuellerAlain PerrenoudFabian BlankPeter GehrBarbara Rothen-Rutishauser
Credits/Source: Particle and Fibre Toxicology 2009, 6:30

Published on: 2009-11-20

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