Tada-Oikawa Saeko, Ichihara Gaku, Fukatsu Hitomi, Shimanuki Yuka, Tanaka Natsuki, Watanabe Eri, Suzuki Yuka, Murakami Masahiko, Izuoka Kiyora, Chang Jie, Wu Wenting, Yamada Yoshiji, Ichihara Sahoko
Department of Human Nutrition, School of Life Studies, Sugiyama Jogakuen University, Nagoya 464-8662, Japan.
Graduate School of Regional Innovation Studies, Mie University, Tsu 514-8507, Japan.
Int J Mol Sci. 2016 Apr 16;17(4):576. doi: 10.3390/ijms17040576.
Titanium dioxide (TiO₂) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO₂ nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO₂ nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO₂ particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO₂ particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO₂ particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO₂ particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO₂ particles also increased IL-8 expression. The results indicated that anatase TiO₂ nanoparticles induced inflammatory responses compared with other TiO₂ particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.
二氧化钛（TiO₂）纳米颗粒广泛应用于化妆品、防晒霜、生物医学和食品中。当用作食品添加剂时，TiO₂纳米颗粒被大量用作白色食品着色剂。然而，TiO₂纳米颗粒对胃肠道的影响仍不清楚。本研究旨在确定五种不同晶体结构和尺寸的TiO₂颗粒对人上皮结直肠癌（Caco-2）细胞和THP-1单核细胞衍生巨噬细胞的影响。在THP-1巨噬细胞中，24小时暴露于锐钛矿型（初级粒径：50和100 nm）和金红石型（50 nm）TiO₂颗粒会以剂量依赖的方式降低细胞活力，但在Caco-2细胞中则不会。然而，Caco-2细胞暴露于锐钛矿型（50 nm）TiO₂颗粒72小时会以剂量依赖的方式降低细胞活力。锐钛矿型（100 nm）、金红石型（50 nm）和P25 TiO₂颗粒的最高剂量（50 µg/mL）也会降低Caco-2细胞的活力。无论TiO₂颗粒的类型如何，两种细胞中的活性氧生成均有增加的趋势。将THP-1巨噬细胞暴露于50 µg/mL的锐钛矿型（50 nm）TiO₂颗粒会增加白细胞介素（IL）-1β的表达水平，将Caco-2细胞暴露于50 µg/mL的锐钛矿型（50 nm）TiO₂颗粒也会增加IL-8的表达。结果表明，与其他TiO₂颗粒相比，锐钛矿型TiO₂纳米颗粒会引发炎症反应。需要进一步研究以确定这些发现与体内情况的相关性，以避免摄入颗粒的危害。
