Inhalation and oropharyngeal aspiration exposure to rod-like carbon nanotubes induces highly similar airway inflammation and biological pathways in mouse lungs

Inhalation and low-dose aspiration elicit highly similar pulmonary inflammation which was confirmed by activation of essentially similar biological pathways and even the same genes. Present results provide evidence that oropharyngeal aspiration is valid approach for hazard assessment of nanomaterials and proper alternative method for inhalation exposure. To compare two alternative airway exposure methods, C57BL/6 mice were exposed to rCNT by inhalation method (aerosol mass concentrations of 6.2-8.2 mg/m3; 4h/day for 4 days), or by oropharyngeal aspiration. Low-dose (10 ug/day in 50 ul of PBS ) or high-dose (40 ug/day in 50ul of PBS) aspiration exposure of rCNT was used for four days. Bronchoalveolar lavage and lung tissue samples were collected, histological sections analyzed and mRNA expression profiles were determined by Agilent microarray. Untreated mice were used as Controls for inhalation, and vehichle treated (PBS) as Controls for aspiration.