Exposure of normal and chronic bronchitis-like mucosa models to aerosolized carbon nanoparticles: comparison of pro-inflammatory oxidative stress and tissue injury/repair responses

Abstract

Carbon nanoparticles (CNP) are generated by incomplete combustion of diesel engines. Several epidemiological studies associated higher susceptibility to particulate matter related adverse respiratory outcomes with preexisting conditions like chronic bronchitis (CB). Therefore, we compared the effect of CNP exposure on primary bronchial epithelial cells (PBEC) developed in air-liquid interface (ALI) models of normal versus CB-like-mucosa.

PBEC cultured at ALI represented normal mucosa (PBEC-ALI). To develop CB-like-mucosa (PBEC-ALI/CB), 1 ng/ml interleukin-13 was added to the basal media of PBEC-ALI culturing. PBEC-ALI and PBEC-ALI/CB were exposed to sham or to aerosolized CNP using XposeALI^® system. Protein levels of CXCL-8 and MMP-9 were measured in the basal media using ELISA. Transcript expression of pro-inflammatory (CXCL8, IL6, TNF, NFKB), oxidative stress (HMOX1, SOD3, GSTA1, GPx), tissue injury/repair (MMP9/TIMP1) and bronchial cell type markers (MUC5AC, CC10) were assessed using qRT-PCR.

Increased secretion of CXCL-8 and MMP-9 markers was detected 24 h post-exposure in both PBEC-ALI and PBEC-ALI/CB with more pronounced effect in the later. Pro-inflammatory and tissue injury markers were increased at both 6 h and 24 h post-exposure in PBEC-ALI/CB. Oxidative stress markers exhibited similar responses at 6 h and 24 h post-exposure in PBEC-ALI/CB. The club cell specific marker CC10 was increased by 300 fold in PBEC-ALI/CB and 20 fold in PBEC-ALI following CNP exposure.

Our data indicates an earlier and stronger reaction of pro-inflammatory, oxidative stress and tissue injury markers in PBEC-ALI/CB models compared to PBEC-ALI models following CNP exposure. The findings may provide insight into the plausible mechanisms of higher susceptibility among predisposed individuals to nanoparticle exposure.

Keywords:

• Carbon nanoparticles
• air-liquid interface model
• chronic bronchitis–like model
• inflammation
• oxidative stress

Acknowledgments

The authors sincerely acknowledge the technical assistance received from Tania A Thimraj and Mizanur Rahman, Institute of Environmental Medicine (IMM), Karolinska Institutet.

Disclosure statement

All authors have read and approved the manuscript. The Coauthors Dr. Per Gerde has stocks in Inhalation Sciences, Sweden. All other authors have no competing financial interests to disclose.

Additional information

Funding

This study was supported by the Swedish Fund for Research without Animal Experiments [22/10, 40/11, F35/12, F25/13, F34-14, and F36/15], the Swedish Research Council (VR 521, 2010-2801, and 2014-02767), the Swedish Heart-Lung Foundation [20100180, 20120376, 20120818, 20150328, 20150329, and 20150330] European Respiratory Society [ERS: ERS LTRF 2014 - 3567], and by the Karolinska Institutet, Sweden. All these funding sources have support on collection, analysis, and interpretation of the data included in the manuscript.