Open Access Research

Pulmonary surfactant coating of multi-walled carbon nanotubes (MWCNTs) influences their oxidative and pro-inflammatory potential in vitro

Michael Gasser12, Peter Wick2, Martin JD Clift1, Fabian Blank3, Liliane Diener2, Bing Yan45, Peter Gehr6, Harald F Krug2 and Barbara Rothen-Rutishauser13*

Author Affiliations

1 Adolphe Merkle Institute, University of Fribourg, Marly, Switzerland

2 Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland

3 Respiratory Medicine, Department of Clinical Research, Inselspital University Hospital, University of Bern, Bern, Switzerland

4 Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, USA

5 School of Chemistry and Chemical Engineering, Shandong University, Jinan, China

6 Institute of Anatomy, University of Bern, Bern, Switzerland

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Particle and Fibre Toxicology 2012, 9:17  doi:10.1186/1743-8977-9-17

Published: 24 May 2012

Abstract

Background

Increasing concern has been expressed regarding the potential adverse health effects that may be associated with human exposure to inhaled multi-walled carbon nanotubes (MWCNTs). Thus it is imperative that an understanding as to the underlying mechanisms and the identification of the key factors involved in adverse effects are gained. In the alveoli, MWCNTs first interact with the pulmonary surfactant. At this interface, proteins and lipids of the pulmonary surfactant bind to MWCNTs, affecting their surface characteristics. Aim of the present study was to investigate if the pre-coating of MWCNTs with pulmonary surfactant has an influence on potential adverse effects, upon both (i) human monocyte derived macrophages (MDM) monocultures, and (ii) a sophisticated in vitro model of the human epithelial airway barrier. Both in vitro systems were exposed to MWCNTs either pre-coated with a porcine pulmonary surfactant (Curosurf) or not. The effect of MWCNTs surface charge was also investigated in terms of amino (−NH2) and carboxyl (−COOH) surface modifications.

Results

Pre-coating of MWCNTs with Curosurf affects their oxidative potential by increasing the reactive oxygen species levels and decreasing intracellular glutathione depletion in MDM as well as decreases the release of Tumour necrosis factor alpha (TNF-α). In addition, an induction of apoptosis was observed after exposure to Curosurf pre-coated MWCNTs. In triple cell-co cultures the release of Interleukin-8 (IL-8) was increased after exposure to Curosurf pre-coated MWCNTs. Effects of the MWCNTs functionalizations were minor in both MDM and triple cell co-cultures.

Conclusions

The present study clearly indicates that the pre-coating of MWCNTs with pulmonary surfactant more than the functionalization of the tubes is a key factor in determining their ability to cause oxidative stress, cytokine/chemokine release and apoptosis. Thus the coating of nano-objects with pulmonary surfactant should be considered for future lung in vitro risk assessment studies.

Keywords:
Multi-walled carbon nanotubes (MWCNTs); Pulmonary surfactant (Curosurf); Macrophages; Epithelial cells; Dendritic cells; Triple cell co-culture; Pro-inflammatory and oxidative reactions