TY - JOUR
T1 - Critical issues in genotoxicity assessment of TiO2 nanoparticles by human peripheral blood mononuclear cells
AU - Andreoli, Cristina
AU - Leter, Giorgio
AU - De Berardis, Barbara
AU - Degan, Paolo
AU - De Angelis, Isabella
AU - Pacchierotti, Francesca
AU - Crebelli, Riccardo
AU - Barone, Flavia
AU - Zijno, Andrea
PY - 2018/12/1
Y1 - 2018/12/1
N2 - In the last years, a number of in vitro studies have been performed to assess the genotoxic activity of titanium dioxide (TiO2). To resolve the contradictory results, in this study, we investigated the genotoxic activity of commercial TiO2 nanoparticles (NPs) and microparticles of different forms (anatase, rutile and mix of both). We evaluated micronucleus formation in stimulated lymphocytes, as well as DNA strand breaks and 8-oxo-7,8-dihydro-2′-deoxyguanosine in peripheral blood mononuclear cells (PBMCs), a mixed population of lymphocytes and monocytes. Different responses to TiO2 exposure were obtained depending on the assay. Both TiO2 NPs and microparticles and all the crystalline forms elicited a significant increase in 8-oxo-7,8-dihydro-2′-deoxyguanosine and DNA strand breaks in the whole PBMC population, without a concurrent increase of micronuclei in proliferating lymphocytes. The distribution of DNA damage in PBMCs, detected by the comet assay, that measures DNA damage at level of single cells, indicated the presence of a more susceptible cell subpopulation. The measurement of side scatter signals by flow cytometry highlighted the preferential physical interaction of TiO2 particles with monocytes that also displayed higher reactive oxygen species generation, providing a mechanistic explanation for the different responses observed in genotoxicity assays with PBMCs and lymphocytes. This study confirmed the suitability of human PBMCs as multi-cell model to investigate NP-induced DNA damage, but suggested some caution in the use of stimulated lymphocytes for the assessment of NP clastogenicity.
AB - In the last years, a number of in vitro studies have been performed to assess the genotoxic activity of titanium dioxide (TiO2). To resolve the contradictory results, in this study, we investigated the genotoxic activity of commercial TiO2 nanoparticles (NPs) and microparticles of different forms (anatase, rutile and mix of both). We evaluated micronucleus formation in stimulated lymphocytes, as well as DNA strand breaks and 8-oxo-7,8-dihydro-2′-deoxyguanosine in peripheral blood mononuclear cells (PBMCs), a mixed population of lymphocytes and monocytes. Different responses to TiO2 exposure were obtained depending on the assay. Both TiO2 NPs and microparticles and all the crystalline forms elicited a significant increase in 8-oxo-7,8-dihydro-2′-deoxyguanosine and DNA strand breaks in the whole PBMC population, without a concurrent increase of micronuclei in proliferating lymphocytes. The distribution of DNA damage in PBMCs, detected by the comet assay, that measures DNA damage at level of single cells, indicated the presence of a more susceptible cell subpopulation. The measurement of side scatter signals by flow cytometry highlighted the preferential physical interaction of TiO2 particles with monocytes that also displayed higher reactive oxygen species generation, providing a mechanistic explanation for the different responses observed in genotoxicity assays with PBMCs and lymphocytes. This study confirmed the suitability of human PBMCs as multi-cell model to investigate NP-induced DNA damage, but suggested some caution in the use of stimulated lymphocytes for the assessment of NP clastogenicity.
KW - comet assay
KW - flow cytometry
KW - genotoxicity
KW - micronucleus
KW - Nanoparticles
KW - titanium dioxide
UR - http://www.scopus.com/inward/record.url?scp=85055037225&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85055037225&partnerID=8YFLogxK
U2 - 10.1002/jat.3650
DO - 10.1002/jat.3650
M3 - Article
C2 - 29869339
AN - SCOPUS:85055037225
VL - 38
SP - 1471
EP - 1482
JO - Journal of Applied Toxicology
JF - Journal of Applied Toxicology
SN - 0260-437X
IS - 12
ER -