Cerium dioxide nanoparticles exacerbate house dust mite induced type II airway inflammation.

BACKGROUND

Nanomaterial inhalation represents a potential hazard for respiratory conditions such as asthma. Cerium dioxide nanoparticles (CeONPs) have the ability to modify disease outcome but have not been investigated for their effect on models of asthma and inflammatory lung disease. The aim of this study was to examine the impact of CeONPs in a house dust mite (HDM) induced murine model of asthma.

RESULTS

Repeated intranasal instillation of CeONPs in the presence of HDM caused the induction of a type II inflammatory response, characterised by increased bronchoalveolar lavage eosinophils, mast cells, total plasma IgE and goblet cell metaplasia. This was accompanied by increases in IL-4, CCL11 and MCPT1 gene expression together with increases in the mucin and inflammatory regulators CLCA1 and SLC26A4. CLCA1 and SLC26A4 were also induced by CeONPs + HDM co-exposure in air liquid interface cultures of human primary bronchial epithelial cells. HDM induced airway hyperresponsiveness and airway remodelling in mice were not altered with CeONPs co-exposure. Repeated HMD instillations followed by a single exposure to CeONPs failed to produce changes in type II inflammatory endpoints but did result in alterations in the neutrophil marker CD177. Treatment of mice with CeONPs in the absence of HDM did not have any significant effects. RNA-SEQ was used to explore early effects 24 h after single treatment exposures. Changes in SAA3 expression paralleled increased neutrophil BAL levels, while no changes in eosinophil or lymphocyte levels were observed. HDM resulted in a strong induction of type I interferon and IRF3 dependent gene expression, which was inhibited with CeONPs co-exposure. Changes in the expression of genes including CCL20, CXCL10, NLRC5, IRF7 and CLEC10A suggest regulation of dendritic cells, macrophage functionality and IRF3 modulation as key early events in how CeONPs may guide pulmonary responses to HDM towards type II inflammation.

CONCLUSIONS

CeONPs were observed to modulate the murine pulmonary response to house dust mite allergen exposure towards a type II inflammatory environment. As this type of response is present within asthmatic endotypes this finding may have implications for how occupational or incidental exposure to CeONPs should be considered for those susceptible to disease.