Food-grade titanium dioxide and zinc oxide nanoparticles induce toxicity and cardiac damage after oral exposure in rats.

BACKGROUND: Metallic nanoparticles (NPs) are widely used as food additives for human consumption. NPs reach the bloodstream given their small size, getting in contact with all body organs and cells. NPs have adverse effects on the respiratory and intestinal tract; however, few studies have focused on the toxic consequences of orally ingested metallic NPs on the cardiovascular system. Here, the effects of two food-grade additives on the cardiovascular system were analyzed. METHODS: Titanium dioxide labeled as E171 and zinc oxide (ZnO) NPs were orally administered to Wistar rats using an esophageal cannula at 10 mg/kg bw every other day for 90 days. We evaluated cardiac cell morphology and death, expression of apoptotic and autophagic proteins in cardiac mitochondria, mitochondrial dysfunction, and concentration of metals on cardiac tissue. RESULTS: Heart histology showed important morphological changes such as presence of cellular infiltrates, collagen deposition and mitochondrial alterations in hearts from rats exposed to E171 and ZnO NPs. Intracellular Cyt-C levels dropped, while TUNEL positive cells increased. No significant changes in the expression of inflammatory cytokines were detected. Both NPs altered mitochondrial function indicating cardiac dysfunction, which was associated with an elevated concentration of calcium. ZnO NPs induced expression of caspases 3 and 9 and two autophagic proteins, LC3B and beclin-1, and had the strongest effect compared to E171. CONCLUSIONS: E171 and ZnO NPs induce adverse cardiovascular effects in rats after 90 days of exposure, thus food intake containing these additives, should be taken into consideration, since they translocate into the bloodstream and cause cardiovascular damage.

Titanium Dioxide (E171) Induces Toxicity in H9c2 Rat Cardiomyoblasts and Ex Vivo Rat Hearts.

Cardiovascular diseases are the leading cause of death worldwide. Food-grade TiO2 (E171) is the most widely used additive in the food industry. Existing evidence shows TiO2 nanoparticles reach systemic circulation through biological barriers, penetrate cell membranes, accumulate in cells of different organs, and cause damage; however, their effects on cardiac cells and the development of heart diseases are still unexplored. Therefore, in this work, we tested E171 toxicity in rat cardiomyoblasts and hearts. E171 internalization and impact on cell viability, proliferation, mitochondria, lysosomes, F-actin distribution, and cell morphology were evaluated in H9c2 cells. Additionally, effects of E171 were measured on cardiac function in ex vivo rat hearts. E171 was uptaken by cells and translocated into the cytoplasm. E171 particles changed cell morphology reducing proliferation and metabolic activity. Higher caspase-3 and caspase-9 expression as well as Tunel-positive cells induced by E171 exposure indicate apoptotic death. Mitochondrial and lysosome alterations resulting from mitophagy were detected after 24 and 48 h exposure, respectively. Additionally, high E171 concentrations caused rearrangements of the F-actin cytoskeleton. Finally, hearts exposed to E171 showed impaired cardiac function. These results support E171 toxicity in cardiac cells in vitro altering cardiac function in an ex vivo model, indicating that consumption of this food additive could be toxic and may lead to the development of cardiovascular disease.

TiO2 nanoparticles induce dysfunction and activation of human endothelial cells.

Nanoparticles can reach the blood and cause inflammation, suggesting that nanoparticles-endothelial cells interactions may be pathogenically relevant. We evaluated the effect of titanium dioxide nanoparticles (TiO2) on proliferation, death, and responses related with inflammatory processes such as monocytic adhesion and expression of adhesion molecules (E- and P-selectins, ICAM-1, VCAM-1, and PECAM-1) and with inflammatory molecules (tissue factor, angiotensin-II, VEGF, and oxidized LDL receptor-1) on human umbilical vein endothelial cells (HUVEC). We also evaluated the production of reactive oxygen species, nitric oxide production, and NF-κB pathway activation. Aggregates of TiO2 of 300 nm or smaller and individual nanoparticles internalized into HUVEC inhibited proliferation strongly and induced apoptotic and necrotic death starting at 5 µg/cm². Besides, TiO2 induced activation of HUVEC through an increase in adhesion and in expression of adhesion molecules and other molecules involved with the inflammatory process. These effects were associated with oxidative stress and NF-κB pathway activation. In conclusion, TiO2 induced HUVEC activation, inhibition of cell proliferation with increased cell death, and oxidative stress.