Titanium dioxide (TiO2) nanoparticles induce neutrophil influx and local production of several pro-inflammatory mediators in vivo.

We have recently described the in vitro effects of titanium dioxide (TiO(2)) nanoparticles (NPs) in human neutrophils. The objective of the present study was to determine if TiO(2) NPs induced leukocyte infiltration in the in vivo murine air pouch model of acute inflammation and, if so, to identify which of the main cell populations were attracted. TiO(2) NPs induced leukocyte influx after 3-9h of treatment, since the number of leukocytes attracted significantly increased when compared to controls. Neutrophils are the most abundant leukocytes attracted by TiO(2) representing more than ~80% of cells, with the rest being mononuclear cells. Using an antibody array technique to detect 40 different analytes, we observed that TiO(2) increased the local production of several analytes in the exudates, including diverse chemokines. Using an ELISA assay, we found that the concentration of TiO(2)-induced MIP-1β was significantly increased vs controls, corroborating the antibody array results.