Titanium Dioxide Exposure Induces Acute Eosinophilic Lung Inflammation in Rabbits

Abstract

Titanium dioxide (TiO₂) is increasingly widely used in industrial, commercial and home products. TiO₂ aggravates respiratory symptoms by induction of pulmonary inflammation although the mechanisms have not been well investigated. We aimed to investigate lung inflammation in rabbits after intratracheal instillation of P25 TiO₂. One ml of 10, 50 and 250 µg of P25 TiO₂ was instilled into one of the lungs of rabbits, chest computed-tomography was performed, and bronchoalveolar lavage (BAL) fluid was collected before, at 1 and 24hr after P25 TiO₂ exposure. Changes in inflammatory cells in the BAL fluids were measured. Lung pathological assay was also carried out at 24hr after P25 TiO₂ exposure. Ground glass opacities were noted in both lungs 1hr after P25 TiO₂ and saline (control) instillation. Although the control lung showed complete resolution at 24hr, the lung exposed to P25 TiO₂ showed persistent ground glass opacities at 24hr. The eosinophil counts in BAL fluid were significantly increased after P25 TiO₂ exposure. P25 TiO₂ induced a dose dependent increase of eosinophils in BAL fluid but no significant differences in neutrophil and lymphocyte cell counts were detected. The present findings suggest that P25 TiO₂ induces lung inflammation in rabbits which is associated with eosinophilic inflammation.