Immunomodulation and T Helper TH(1)/TH(2) Response Polarization by CeO(2) and TiO(2) Nanoparticles

Immunomodulation by nanoparticles, especially as related to the biochemical properties of these unique materials, has scarcely been explored. In an in vitro model of human immunity, we demonstrate two catalytic nanoparticles, TiO(2) (oxidant) and CeO(2) (antioxidant), have nearly opposite effects on human dendritic cells and T helper (T(H)) cells. For example, whereas TiO(2) nanoparticles potentiated DC maturation that led towards T(H)1-biased responses, treatment with antioxidant CeO(2) nanoparticles induced APCs to secrete the anti-inflammatory cytokine, IL-10, and induce a T(H)2-dominated T cell profile. In subsequent studies, we demonstrate these results are likely explained by the disparate capacities of the nanoparticles to modulate ROS, since TiO(2), but not CeO(2) NPs, induced inflammatory responses through an ROS/inflammasome/IL-1β pathway. This novel capacity of metallic NPs to regulate innate and adaptive immunity in profoundly different directions via their ability to modulate dendritic cell function has strong implications for human health since unintentional exposure to these materials is common in modern societies.