Inhalation exposure to nanosized and fine TiO2 particles inhibits features of allergic asthma in a murine model

Background: Nanotechnology and engineered nanomaterials (ENM) are here to stay. Recent evidence suggests that exposure to environmental particulate matter exacerbates symptoms of asthma. In the present study we investigated the modulatory effects of titanium dioxide particle exposure in an experimental allergic asthma. Methods: Nonallergic (healthy) and ovalbumin-sensitized (asthmatic) mice were exposed via inhalation to two different sizes of titanium dioxide particles, nanosized (nTiO(2)) and fine (fTiO(2)), for 2 hours a day, three days a week, for four weeks at a concentration of 10 mg/m(3). Different endpoints were analysed to evaluate the immunological status of the mice. Results: Healthy mice elicited pulmonary neutrophilia accompanied by significantly increased chemokine CXCL5 expression when exposed to nTiO(2). Surprisingly, allergic pulmonary inflammation was dramatically suppressed in asthmatic mice which were exposed to nTiO(2) or fTiO(2) particles - i.e. the levels of leucocytes, cytokines, chemokines and antibodies characteristic to allergic asthma were substantially decreased. Conclusions: Our results suggest that repeated airway exposure to TiO2 particles modulates the airway inflammation depending on the immunological status of the exposed mice.