Efeitos citotóxicos e genotóxicos de uma nova nanopartícula de titânio de interesse industrial - in vitro

Abstract

Titanium dioxide nanoparticles (TiO2 NP) are included as one of the most used nanomaterials by industries in general; it is applied in coatings, pigments, and paints for its ability to offer opacity and brightness, in sunscreens blocking ultraviolet rays (UV) and in the manufacture of photovoltaic cells. In addition, nanoparticles are highly used by the petrochemical industry to improve oil extraction. This scenario culminated in the growing use of nanoparticles and in the concern about their harmful effects on the environment and living beings. Thus, it became important to assess the toxic effects of nanomaterials after exposure to biological models (cells and tissues) to understand their risks to those who produce and manipulate them. Our work aimed to evaluate the cytotoxicity and genotoxicity of a new TiO2 NP and its immune response to in vitro models. The MTT cytotoxicity assay was used to assess the cell viability following exposure to TiO2 NP (2000, 1000, 100, 10 and 0.1 µg / mL) at 24, 48, 72 and 96 h in mouse fibroblasts LA-9 and at 24, 48 and 72 h in macrophages J774A.1. The comet assay (pH alkaline) was used to evaluate the genotoxicity of TiO2 NP (100, 10 and 1 µg / mL) after exposure to fibroblasts during 24 h. Cytokines IL-10, TNF-α, and IL-12 were measured in macrophage cell supernatant after exposure to TiO2 NP (1000, 100 and 10 µg / mL) at 24, 48 and 72 h by ELISA, and evaluated the expression of genes Nos2, Stat6 and Nfkb by qRT-PCR. In fibroblasts, TiO2 NP promoted cytotoxic effects at 96 h in the concentrations of 2000 and 1000 µg / mL and was genotoxic in all concentrations tested at 24 h compared to negative control. In macrophages, there was a decrease in cell viability after 48 h of exposure at concentrations of 2000 and 1000 µg/mL. Cytokine dosage and gene expression analysis in macrophages suggest that TiO2 NP uptake in high concentrations (≥ 1000 µg / mL) at 72 h may have generated an intracellular activation process, reflected in the high levels of IL-12, which possibly induced the production of IL-10 as a regulatory factor, in addition to being in agreement with the increased expression of the Stat6 and NF-kB genes that participate in cellular polarization in these cells. The high Nos2 expression after exposure to TiO2 NP (1000 µg / mL) demonstrates the activation of the inflammatory process in this experimental condition. The main toxicity mechanism suggested is the photocatalytic potential of TiO2 NP due to its mineral composition (anatase) and the possible generation of reactive oxygen species. Thus, TiO2 NP was cytotoxic to both cell lines in high concentrations and genotoxic to fibroblast at 24 h.