Ingestion of titanium dioxide (TiO2) nanoparticles from products such as agricultural chemicals, processed food, and nutritional supplements is nearly unavoidable. The gastrointestinal tract serves as a critical interface between the body and the external environment, and is the site of essential nutrient absorption. The goal of this study was to examine the effects of ingesting the 30 nm TiO2 nanoparticles with an in vitro cell culture model of the small intestinal epithelium, and to determine how acute or chronic exposure to nano-TiO2 influences intestinal barrier function, reactive oxygen species generation, proinflammatory signaling, nutrient absorption (iron, zinc, fatty acids), and brush border membrane enzyme function (intestinal alkaline phosphatase). A Caco-2/HT29-MTX cell culture model was exposed to physiologically relevant doses of TiO2 nanoparticles for acute (four hours) or chronic (five days) time periods. Exposure to TiO2 nanoparticles significantly decreased intestinal barrier function following chronic exposure. Reactive oxygen species (ROS) generation, proinflammatory signaling, and intestinal alkaline phosphatase activity all showed increases in response to nano-TiO2. Iron, zinc, and fatty acid transport were significantly decreased following exposure to TiO2 nanoparticles. This is because nanoparticle exposure induced a decrease in absorptive microvilli in the intestinal epithelial cells. Nutrient transporter protein gene expression was also altered, suggesting that cells are working to regulate the transport mechanisms disturbed by nanoparticle ingestion. Overall, these results show that intestinal epithelial cells are affected at a functional level by physiologically relevant exposure to nanoparticles commonly ingested from food.

中文翻译：

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二氧化钛纳米颗粒的摄入改变了小肠体外模型中的营养吸收

从农业化学品、加工食品和营养补充剂等产品中摄入二氧化钛 (TiO2) 纳米颗粒几乎是不可避免的。胃肠道是身体与外部环境之间的重要接口，是吸收必需营养素的场所。本研究的目的是用小肠上皮的体外细胞培养模型检查摄入 30 nm TiO2 纳米颗粒的影响，并确定急性或慢性暴露于纳米 TiO2 对肠道屏障功能、活性氧的影响生成、促炎信号、营养吸收（铁、锌、脂肪酸）和刷状缘膜酶功能（肠碱性磷酸酶）。Caco-2/HT29-MTX 细胞培养模型在急性（四小时）或慢性（五天）时间段内暴露于生理相关剂量的二氧化钛纳米粒子。长期接触二氧化钛纳米颗粒后，肠道屏障功能显着降低。活性氧 (ROS) 的产生、促炎信号和肠道碱性磷酸酶活性都显示出对纳米二氧化钛的响应增加。暴露于 TiO2 纳米颗粒后，铁、锌和脂肪酸的转运显着降低。这是因为纳米颗粒暴露导致肠上皮细胞中吸收性微绒毛的减少。营养转运蛋白基因表达也发生了变化，这表明细胞正在努力调节被纳米颗粒摄入干扰的转运机制。全面的，