Research

Carbon black nanoparticles induce type II epithelial cells to release chemotaxins for alveolar macrophages

Peter G Barlow^1,2 , Anna Clouter-Baker² , Ken Donaldson³ , Janis MacCallum² and Vicki Stone²

¹M.R.C/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK

²Biomedicine Research Group, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, UK

³ELEGI/Colt Laboratories, M.R.C/University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK

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Particle and Fibre Toxicology 2005, 2:11doi:10.1186/1743-8977-2-11

Published:	6 December 2005

Abstract

Background

Alveolar macrophages are a key cell in dealing with particles deposited in the lungs and in determining the subsequent response to that particle exposure. Nanoparticles are considered a potential threat to the lungs and the mechanism of pulmonary response to nanoparticles is currently under intense scrutiny. The type II alveolar epithelial cell has previously been shown to release chemoattractants which can recruit alveolar macrophages to sites of particle deposition. The aim of this study was to assess the responses of a type II epithelial cell line (L-2) to both fine and nanoparticle exposure in terms of secretion of chemotactic substances capable of inducing macrophage migration.

Results

Exposure of type II cells to carbon black nanoparticles resulted in significant release of macrophage chemoattractant compared to the negative control and to other dusts tested (fine carbon black and TiO₂ and nanoparticle TiO₂) as measured by macrophage migration towards type II cell conditioned medium. SDS-PAGE analysis of the conditioned medium from particle treated type II cells revealed that a higher number of protein bands were present in the conditioned medium obtained from type II cells treated with nanoparticle carbon black compared to other dusts tested. Size-fractionation of the chemotaxin-rich supernatant determined that the chemoattractants released from the epithelial cells were between 5 and 30 kDa in size.

Conclusion

The highly toxic nature and reactive surface chemistry of the carbon black nanoparticles has very likely induced the type II cell line to release pro-inflammatory mediators that can potentially induce migration of macrophages. This could aid in the rapid recruitment of inflammatory cells to sites of particle deposition and the subsequent removal of the particles by phagocytic cells such as macrophages and neutrophils. Future studies in this area could focus on the exact identity of the substance(s) released by the type II cells in response to particle exposure.