Time course of TiO2 and carbon black nanoparticles induced pulmonary inflammationin in rats

Our understanding of how manufactured nanoparticles affect pulmonary immunological response is poor. The aim of the studywas to evaluate, in healthy rats, the acute lung toxicity of intratracheally instilled nanoscale TiO2 (15 nm) and carbon black nanoparticles (Printex 60 and FW2, Degussa). Groups of six rats were instilled once with 100 (micro)g of particles suspended in rat concentrated bronchoalveolar lavage fluid (BALF) as a vehicle. Rats were sacrificed 3, 7 and 21 days post-exposure. ffect assessment included lung histology and markers of lung inflammatory and immunological response. Exposure to FW2 particles induced a significant increase in total alveolar cells after 3 days (4.2×10(6) cells/rat versus 1.8×10(6) cells in control rats). This increase was no more visible at 7 and 21 days. For all groups, alveolar cells consisted mainly in macrophages, with only a slight influx of neutrophils after 7 days exposure to TiO2 and 7 and 21 days to FW2. One day after exposure, the percentage of phagocytosing macrophages was about 14% for TiO2 and P60 and 8% for FW2. The number of macrophages with particles inside remained constant (up to 21 days) for the carbon-based nanoparticles but decreased with time for TiO2 (4.8% at day 21). No TNF-(alpha) was detected either in serum or in BALF of control and exposed-rats. No visible alteration of the lung tissue was noted. As a conclusion, all these particles showed little toxicity in healthy rats in our experimental conditions. FW2 was the most potent to induce a slight but significant inflammatory response