Ingested titanium dioxide nanomaterials: new approach to investigate intestinal genotoxicity and key cellular/molecular effects

Oral exposure to titanium dioxide nanomaterials (TiO2NMs) is due to their presence in food, food contact materials, medicines and cosmetics. The gastrointestinal tract(GIT) represents primary site of contact, that may result in systemic exposure, if biological barriers are surpassed. The INGESTnano project aimed to investigate nano-bio interactions at the cellular/molecular levels within the context of the intestinal tract and digestion processes, for understanding potential effects on human health. A group of three TiO₂NMs(NM-102, NM-103, NM-105) was selected as case study using a new approach methodology(NAM), incorporating the in vitro human digestion simulation prior to biological assays in Caco-2 and HT29-MTX-E12 intestinal cells. The endpoints included cyto- and genotoxicity, cell uptake, intestinal permeability, GIT transport and epigenomic modifications. The results showed a more pronounced cytotoxicity in HT29-MTX-E12 cells for digested NM-105, as compared to undigested, concomitantly with subtle changes in hydrodynamic-size. DNA-damage induction was more relevant for NM-105, and the micronucleus assay showed chromosomal damage in HT29-MTX-E12 cells for all TiO2NMs, especially after in vitro digestion.All NMs, digested or not, were internalized by intestinal cells, but did not affect transepithelial resistance, nor the epithelial markers in polarized enterocytes. NM-102 was retained in lysosomes, while NM-103 and NM-105 showed transcytosis, a potential gateway for systemic distribution. Using Reduced Representation Bisulfite Sequencing, several differentially methylated genes were identified for the TiO₂NMs, either digested or not. Pathway and Gene Ontology analyses showed that each TiO2NMs has a different functional impact on intestinal cells, probably linked to specific physicochemical properties, and digestion seems to reduce this impact. A trend towards CpG hypermethylation was observed upon NM-105 exposure, unlike for the other TiO2NMs. This integrated approach enabled the identification of key events and molecular pathways elicited by TiO2NMs, highlighting the importance of considering the digestion on the induction of adverse outcomes.

Descrição

Abstract disponível em: Book of Abstracts of the 53rd EEMGS Congress / 47th Annual CSSMC Meeting (EEMGS/CSSMC 2025); 2025 Jun 2–5; Bratislava, Slovak Republic. p. 26.