Titanium dioxide nanoparticle exposure alters metabolic homeostasis in a cell culture model of the intestinal epithelium and Drosophila melanogaster

Abstract

Nanosized titanium dioxide (TiO₂) is a common additive in food and cosmetic products. The goal of this study was to investigate if TiO₂ nanoparticles affect intestinal epithelial tissues, normal intestinal function, or metabolic homeostasis using in vitro and in vivo methods. An in vitro model of intestinal epithelial tissue was created by seeding co-cultures of Caco-2 and HT29-MTX cells on a Transwell permeable support. These experiments were repeated with monolayers that had been cultured with the beneficial commensal bacteria Lactobacillus rhamnosus GG (L. rhamnosus). Glucose uptake and transport in the presence of TiO₂ nanoparticles was assessed using fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG). When the cell monolayers were exposed to physiologically relevant doses of TiO₂, a statistically significant reduction in glucose transport was observed. These differences in glucose absorption were eliminated in the presence of beneficial bacteria. The decrease in glucose absorption was caused by damage to intestinal microvilli, which decreased the surface area available for absorption. Damage to microvilli was ameliorated in the presence of L. rhamnosus. Complimentary studies in Drosophila melanogaster showed that TiO₂ ingestion resulted in decreased body size and glucose content. The results suggest that TiO₂ nanoparticles alter glucose transport across the intestinal epithelium, and that TiO₂ nanoparticle ingestion may have physiological consequences.

Keywords:

• GI tract
• glucose
• Caco-2
• Lactobacillus rhamnosus
• microbiome

Acknowledgements

The authors would also like to acknowledge Yizhong Liu and Fabiola Moreno-Olivas for assistance with electron microscopy.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding for this work was provided by the National Institutes of Health [1R15 ES022828], the Research Foundation for the State University of New York, and by a grant to the State University of New York at Binghamton from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program.