Induction of prostaglandin E2 production by TiO2 nanoparticles in human gingival fibroblast.

Background: Despite recent progress in the research of nanoparticles (NPs) spanning in many scientific fields, study of NPs in dentistry is limited. This triggered us to investigate the effect of TiO2 NPs on the drug-sensitivity of oral squamous cell carcinoma and inflammation of human gingival fibroblasts (HGFs).

Materials And Methods: The number of viable HGF cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Prostaglandin E2 (PGE2) was quantified by enzyme-linked immunosorbent assay. Contamination with lipopolysaccharide (LPS) was assayed by the endotoxin assay kit. Intracellular uptake and distribution of TiO2 NPs were assessed by transmission electron microscopy.

Results: TiO2 NPs (0.05-3.2 mM) did not affect HGF cell viability, although TiO2 NPs clusters were dose-dependently incorporated into the vacuoles of cells. Interleukin-1β (IL-1β) (3 ng/ml) stimulated the secretion of PGE2 into the culture medium by HGF cells. TiO2 NPs also induced PGE2 production, in synergy with IL-1β. Since only a minor amount of LPS was detected in TiO2 NPs, the enhanced production of PGE2 was not simply due to LPS contamination.

Conclusion: The present study demonstrates, for the first time to our knowledge, that TiO2 NPs at concentrations higher than 0.2 mM exert an pro-inflammatory action against HGF cells, regardless of the presence or absence of IL-1β.