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VOLUME 15, 2014  Issue Number 2 , 929-935
DownLoad : 929-935 11.15 Takamasa Numano.pdf
Comparative Study of Toxic Effects of Anatase and Rutile Type Nanosized Titanium Dioxide Particles in vivo and in vitro
Takamasa Numano et al
Two types of nanosized titanium dioxide, anatase (anTiO2) and rutile (rnTiO2), are widely used in industry,
commercial products and biosystems. TiO2
been evaluated as a Group 2B carcinogen. Previous reports
indicated that anTiO2 is less toxic than rnTiO2, however, under ultraviolet irradiation anTiO2 is more toxic than
rnTiO2 in vitro because of differences in their crystal structures. In the present study, we compared the in vivo
and in vitro toxic effects induced by anTiO2 and rnTiO2. Female SD rats were treated with 500 mg/ml of anTiO2
or rnTiO2 suspensions by intra-pulmonary spraying 8 times over a two week period. In the lung, treatment with
anTiO2 or rnTiO2 increased alveolar macrophage numbers and levels of 8-hydroxydeoxyguanosine (8-OHdG);
these increases tended to be lower in the anTiO2 treated group compared to the rnTiO2 treated group. Expression
of MIP1a mRNA and protein in lung tissues treated with anTiO2 and rnTiO2 was also significantly up-regulated,
with MIP1a mRNA and protein expression significantly lower in the anTiO2 group than in the rnTiO2 group.
In cell culture of primary alveolar macrophages (PAM) treated with anTiO2 and rnTiO2, expression of MIP1a
mRNA in the PAM and protein in the culture media was significantly higher than in control cultures. Similarly
to the in vivo results, MIP1a mRNA and protein expression was significantly lower in the anTiO2 treated cultures
compared to the rnTiO2 treated cultures. Furthermore, conditioned cell culture media from PAM cultures treated
with anTiO2 had less effect on A549 cell proliferation compared to conditioned media from cultures treated
with rnTiO2. However, no significant difference was found in the toxicological effects on cell viability of ultra
violet irradiated anTiO2 and rnTiO2. In conclusion, our results indicate that anTiO2 is less potent in induction of
alveolar macrophage infiltration, 8-OHdG and MIP1a expression in the lung, and growth stimulation of A549
cells in vitro than rnTiO2.
Key Words: Nanosized titanium dioxide - anatase - rutile - lung toxicity - MIP1a
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