Hepatocyte apoptosis and its molecular mechanisms in mice caused by titanium dioxide nanoparticles

The Nephroprotective Effect of In Utero Administration of Green Synthesized Titanium Dioxide Nanoparticles in Albino Rats

Titanium dioxide nanoparticles (TiO2-NPs) are one of the most popular nanoscale materials and have a wide range of applications in the manufacturing industry; nonetheless, researchers' focus has been directed to the detrimental consequences of TiO2-NPs. The current study was designed to assess the potential hazardous effects of chemically synthesized TiO2-NPs on the placenta and feto-maternal kidneys of rats. On the other hand, the probable positive impact of TiO2-NPs made after green synthesis was also evaluated. HepG2 cell lines were used to assess the cytotoxicity of chemical and green TiO2-NPs. Five groups of fifty pregnant female rats were formed (n=10). The first (control) group received distilled water. The second and third groups were orally given 100 and 300 mg/kg body weight (bw) of chemical TiO2-NPs, respectively. The fourth and fifth groups were orally given 100 and 300 mg/kg bw of green synthesized TiO2-NPs, respectively. On gestational day 20 (GD 20), blood and tissues were collected for biochemical and histological studies. Our findings revealed that chemical TiO2-NPs induced apoptosis in HepG2 cells at high concentrations, while there was no observed toxicity for green TiO2-NPs. The chemically treated TiO2-NPs groups showed a significant decrease in the level of HDL and a significant increase in cholesterol, LDL-cholesterol, and triglyceride levels. Renal tissues showed necrosis with exfoliation of lining epithelial cells, degenerated tubules, and glomerulonephritis. While the placenta was atrophied and hyalinized. Moreover, Bax expression significantly increased in the renal tubular cells and the villi of the placenta. Contrariwise, green TiO2-NPs-treated groups showed a significant rise in HDL levels with a significant reduction in triglycerides and LDL levels, while cholesterol levels were unaffected. Also, renal tissues showed mild degenerative changes in the glomeruli and renal tubules; thus, noticeable regeneration of epithelium lining tubules was detected in the maternal kidney. Bax showed a minimal reaction in the renal tubules and the villi of the placenta. It concluded that in contrast to chemical TiO2-NPs, biosynthesized TiO2-NPs with garlic showed a positive impact on the biochemical profile and histological investigations.

Exposure to Titanium Dioxide Nanoparticles Leads to Specific Disorders of Spermatid Elongation via Multiple Metabolic Pathways in Drosophila Testes

Titanium dioxide nanoparticles (TiO2 NPs) have been extensively utilized in various applications. However, the regulatory mechanism behind the reproductive toxicity induced by TiO2 NP exposure remains largely elusive. In this study, we employed a Drosophila model to assess potential testicular injuries during spermatogenesis and conducted bulk RNA-Seq analysis to elucidate the underlying mechanisms. Our results reveal that while prolonged exposure to lower concentrations of TiO2 NPs (0.45 mg/mL) for 30 days did not manifest reproductive toxicity, exposure at concentrations of 0.9 and 1.8 mg/mL significantly impaired spermatid elongation in Drosophila testes. Notably, bulk RNA-seq analysis revealed that TiO2 NP exposure affected multiple metabolic pathways including carbohydrate metabolism and cytochrome P450. Importantly, the intervention of glutathione (GSH) significantly protected against reproductive toxicity induced by TiO2 NP exposure, as it restored the number of Orb-positive spermatid clusters in Drosophila testes. Our study provides novel insights into the specific detrimental effects of TiO2 NP exposure on spermatid elongation through multiple metabolic alterations in Drosophila testes and highlights the protective role of GSH in countering this toxicity.

TET3 boosts hepatocyte autophagy and impairs non-alcoholic fatty liver disease by increasing ENPP1 promoter hypomethylation

BACKGROUND

Dysregulated ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family occurs in metabolic reprogramming pathological processes. Nonetheless, the epigenetic mechanisms by which ENPP family impacts NAFLD, also known as metabolic dysfunction-associated steatotic liver disease (MASLD), is poorly appreciated.

METHODS

We investigated the causes and consequences of ENPP1 promoter hypomethylation may boost NAFLD using NAFLD clinical samples, as well as revealed the underlying mechanisms using high-fat diet (HFD) + carbon tetrachloride (CCl4) induced mouse model of NAFLD and FFA treatment of cultured hepatocyte.

RESULTS

Herein, we report that the expression level of ENPP1 are increased in patients with NAFLD liver tissue and in mouse model of NAFLD. Hypomethylation of ENPP1, is associated with the perpetuation of hepatocyte autophagy and liver fibrosis in the NAFLD. ENPP1 hypomethylation is mediated by the DNA demethylase TET3 in NAFLD liver fibrosis and hepatocyte autophagy. Additionally, knockdown of TET3 methylated ENPP1 promoter, reduced the ENPP1 expression, ameliorated the experimental NAFLD. Mechanistically, TET3 epigenetically promoted ENPP1 expression via hypomethylation of the promoter. Knocking down TET3 can inhibit the hepatocyte autophagy but an overexpression of ENPP1 showing rescue effect.

CONCLUSIONS

We describe a novel epigenetic mechanism wherein TET3 promoted ENPP1 expression through promoter hypomethylation is a critical mediator of NAFLD. Our findings provide new insight into the development of preventative measures for NAFLD.

Hepatotoxicity of titanium dioxide nanoparticles

The food additive E171 (titanium dioxide, TiO2), is widely used in foods, pharmaceuticals and cosmetics. It is a fine white powder, with at least one third of its particles sized in the nanoparticulate (˂100 nm range, TiO2 NPs). The use of E171 is controversial as its relevant risk assessment has never been satisfactorily accomplished. In vitro and in vivo studies have shown dose-dependent toxicity in various organs including the liver. TiO2 NPs have been shown to induce inflammation, cell death and structural and functional changes within the liver. The toxicity of TiO2 NPs in experimental models varies between organs and according to their physiochemical characteristics and parameters such as dosage and route of administration. Among these factors, ingestion is the most significant exposure route, and the liver is a key target organ. The aim of this review is to highlight the reported adverse effects of orally administered TiO2 NPs on the liver and to discuss the controversial state of its toxicity.

Differential intestinal effects of water and foodborne exposures of nano-TiO2 in the mussel Mytilus coruscus under elevated temperature

With the wide use of nanomaterials in daily life, nano-titanium dioxide (nano-TiO2) presents potential ecological risks to marine ecosystems, which can be exacerbated by ocean warming (OW). However, most previous studies have only centered around waterborne exposure, while there is a scarcity of studies concentrating on the impact of trophic transfer exposure on organisms. We investigated the differences in toxic effects of 100 μg/L nano-TiO2 on mussels via two pathways (waterborne and foodborne) under normal (24 °C) and warming (28 °C) conditions. Single nano-TiO2 exposure (waterborne and foodborne) elevated the superoxide dismutase (SOD) and catalase (CAT) activities as well as the content of glutathione (GSH), indicating activated antioxidatant response in the intestine. However, depressed antioxidant enzymes and accumulated peroxide products (LPO and protein carbonyl content, PCC) demonstrated that warming in combination with nano-TiO2 broke the prooxidant-antioxidant homeostasis of mussels. Our findings also indicated that nano-TiO2 and high temperature exhibited adverse impacts on amylase (AMS), trypsin (PS), and trehalase (THL). Additionally, activated immune function (lysozyme) comes at the cost of energy expenditure of protein (decreased protein concentration). The hydrodynamic diameter of nano-TiO2 at 24 °C (1693-2261 nm) was lower than that at 28 °C (2666-3086 nm). Bioaccumulation results (range from 0.022 to 0.432 μg/g) suggested that foodborne induced higher Ti contents in intestine than waterborne. In general, the combined effects of nano-TiO2 and warming demonstrated a more pronounced extent of interactive effects and severe damage to antioxidant, digestive, and immune parameters in mussel intestine. The toxicological impact of nano-TiO2 was intensified through trophic transfer. The toxic effects of nano-TiO2 are non-negligible and can be exerted together through both water- and foodborne exposure routes, which deserves further investigation.

Molecular mechanism of nanomaterials induced liver injury: A review

The unique physicochemical properties inherent to nanoscale materials have unveiled numerous potential applications, spanning beyond the pharmaceutical and medical sectors into various consumer industries like food and cosmetics. Consequently, humans encounter nanomaterials through diverse exposure routes, giving rise to potential health considerations. Noteworthy among these materials are silica and specific metallic nanoparticles, extensively utilized in consumer products, which have garnered substantial attention due to their propensity to accumulate and induce adverse effects in the liver. This review paper aims to provide an exhaustive examination of the molecular mechanisms underpinning nanomaterial-induced hepatotoxicity, drawing insights from both in vitro and in vivo studies. Primarily, the most frequently observed manifestations of toxicity following the exposure of cells or animal models to various nanomaterials involve the initiation of oxidative stress and inflammation. Additionally, we delve into the existing in vitro models employed for evaluating the hepatotoxic effects of nanomaterials, emphasizing the persistent endeavors to advance and bolster the reliability of these models for nanotoxicology research.

Dysregulation along the gut microbiota-immune system axis after oral exposure to titanium dioxide nanoparticles: A possible environmental factor promoting obesity-related metabolic disorders

Food additives are one major hallmark of ultra-processed food in the Western-diet, a food habit often associated with metabolic disorders. Among these additives, the whitener and opacifying agent titanium dioxide (TiO₂) raises public health issues due to the ability of TiO₂ nanoparticles (NPs) to cross biological barriers and accumulate in different systemic organs like spleen, liver and pancreas. However before their systemic passage, the biocidal properties of TiO₂ NPs may alter the composition and activity of the gut microbiota, which play a crucial role for the development and maintenance of immune functions. Once absorbed, TiO₂ NPs may further interact with immune intestinal cells involved in gut microbiota regulation. Since obesity-related metabolic diseases such as diabetes are associated with alterations in the microbiota-immune system axis, this raises questions about the possible involvement of long-term exposure to food-grade TiO₂ in the development or worsening of these diseases. The current purpose is to review the dysregulations along the gut microbiota-immune system axis after oral TiO₂ exposure compared to those reported in obese or diabetic patients, and to highlight potential mechanisms by which foodborne TiO₂ NPs may increase the susceptibility to develop obesity-related metabolic disorders.

Ameliorative effect of biosynthesized titanium dioxide nanoparticles using garlic extract on the body weight and developmental toxicity of liver in albino rats compared with chemically synthesized nanoparticles

The application of metallic nanoparticles poses risks to human and animal health. Titanium dioxide nanoparticles (TiO₂NPs) are the most commonly synthesized metallic oxides in the world. Exposure to TiO₂NPs can cause toxicity in the target organisms. This study aimed to evaluate the effects of green and chemical TiO₂NPs on maternal and embryo-fetal livers. Green TiO₂NPs using garlic extract (GTiO₂NPs) and chemical TiO₂NPs (CHTiO₂NPs) were synthesized and characterized by x-ray powder diffraction and high-resolution transmission electron microscopy. The cytotoxicity of both chemical and green TiO₂NPs was determined against HepG₂ cell lines. Fifty pregnant female Albino rats were equally and randomly divided into five groups. Group 1 was kept as a control. Groups 2 and 3 were orally treated with 100 and 300 mg/kg body weight of CHTiO₂NPs, respectively. Groups 4 and 5 were orally treated with 100 and 300 mg/kg of GTiO₂NPs, respectively, from day 6 to 19 of gestation. All dams were euthanized on gestation day 20. All live fetuses were weighed and euthanized. Blood and tissue samples were collected for biochemical, histopathological, and Bax-immunohistochemical expression analyses. Our results indicated that garlic could be used as a reducing agent for the synthesis of TiO₂NPs, and the produced NPs have no toxic effect against HepG₂ cells compared with CHTiO₂NPs. The maternal and fetal bodyweights were greatly reduced among the chemically TiO₂NPs induced animals. The mean serum level of AST and ALT activities and the total protein level significantly increased when TiO₂NPs were administered at high doses. Histologically, the CHTiO₂NPs-treated groups revealed vacuolated and necrotized hepatocytes with congested and dilated blood vessels in the fetal and maternal livers. The immunohistochemistry revealed distinct positive staining of Bax expressed in the hepatocytes. Nevertheless, the biosynthesis of TiO₂NPs using garlic extract had a minimal effect on the normal architecture of the liver. It could be concluded that the bioactivity of TiO₂NPs can be modified by green synthesis using garlic extract. Compared to the CHTiO₂NPs, the exposure to GTiO₂NPs showed reduced liver damage in maternal and embryo-fetal rats.

Thermal stress and TiO2 nanoparticle-induced oxidative DNA damage and apoptosis in mouse hippocampus

Titanium dioxide (nano-TiO₂) is used abundantly in various industrial products and novel medical therapies. In addition, the impact of climate change on the health and safety will undoubtedly increase in the future. However, the effects of exposure to these nanoparticles and heat stress on hippocampal DNA damage and apoptosis remain unclear. This study was conducted to evaluate the DNA damage and apoptosis in the hippocampal tissue and the physiological responses in mice induced by intraperitoneal (i.p.) administration of TiO₂ nanoparticles (NPs) and heat stress for 14 consecutive days. The results showed that heat stress and TiO₂-NPs were induced in the mouse hippocampus that led to hippocampal reactive oxygen species generation, oxidative damage of DNA, and apoptosis in a partly dose-dependent manner, especially at very hot temperature. High doses of nanosized TiO₂ and severe heat stress significantly damaged the function of the hippocampus, as shown in the comet assay and apoptosis tests. The results of this study may provide data for appropriate measures to control and assess the risk of nano-TiO₂ and thermal stress hazards to human health, especially workers. Safety guidelines and policies should be considered when handling nanomaterials in a hot environment.

Unchanged pulmonary toxicity of ZnO nanoparticles formulated in a liquid matrix for glass coating

The inclusion of nanoparticles can increase the quality of certain products. One application is the inclusion of Zinc oxide (ZnO) nanoparticles in a glass coating matrix to produce a UV-absorbing coating for glass sheets. Yet, the question is whether the inclusion of ZnO in the matrix induces toxicity at low exposure levels. To test this, mice were given single intratracheal instillation of 1) ZnO powder (ZnO), 2) ZnO in a glass matrix coating in its liquid phase (ZnO-Matrix), and 3) the matrix with no ZnO (Matrix). Doses of ZnO were 0.23, 0.67, and 2 µg ZnO/mouse. ZnO Matrix doses had equal amounts of ZnO, while Matrix was adjusted to have an equal volume of matrix as ZnO Matrix. Post-exposure periods were 1, 3, or 28 d. Endpoints were pulmonary inflammation as bronchoalveolar lavage (BAL) fluid cellularity, genotoxicity in lung and liver, measured by comet assay, histopathology of lung and liver, and global gene expression in lung using microarrays. Neutrophil numbers were increased to a similar extent with ZnO and ZnO-Matrix at 1 and 3 d. Only weak genotoxicity without dose-response effects was observed in the lung. Lung histology showed an earlier onset of inflammation in material-exposed groups as compared to controls. Microarray analysis showed a stronger response in terms of the number of differentially regulated genes in ZnO-Matrix exposed mice as compared to Matrix only. Activated canonical pathways included inflammatory and cardiovascular ones. In conclusion, the pulmonary toxicity of ZnO was not changed by formulation in a liquid matrix for glass coating.

Ingestion of titanium dioxide nanoparticles: a definite health risk for consumers and their progeny

Titanium dioxide (TiO₂) is one of the most commonly used nanomaterials in the world. Additive E171, which is used in the food industry, contains a nanometric particle fraction of TiO₂. Oral exposure of humans to these nanoparticles (NPs) is intensive, leading to the question of their impact on health. Daily oral intake by rats of amounts of E171 that are relevant to human intake has been associated with an increased risk of chronic intestinal inflammation and carcinogenesis. Due to their food preferences, children are very exposed to this NP. Furthermore, maternal-foetal transfer of TiO₂ NPs during pregnancy, as well as exposure of the offspring by breastfeeding, have been recently described. In France, the use of E171 in the production of foodstuffs was suspended in January 2020 as a precautionary measure. To provide some answers to this public health problem and help global regulatory agencies finalize their decisions, we reviewed in vitro and in vivo studies that address the effects of TiO₂ NPs through oral exposure, especially their effects on the gastrointestinal tract, one of the most exposed tissues. Our review also highlights the effects of exposure on the offspring during pregnancy and by breastfeeding.

Exposure to boron trioxide nanoparticles and ions cause oxidative stress, DNA damage, and phenotypic alterations in Drosophila melanogaster as an in vivo model

Boron trioxide nanoparticles (B₂ O₃ NPs) have recently been widely used in a range of applications including electronic device technologies, acousto-optic apparatus fields and as nanopowder for the production of special glasses. We propose Drosophila melanogaster as a useful in vivo model system to study the genotoxic risks associated with NP exposure. In this study we have conducted a genotoxic evaluation of B₂ O₃ NPs (size average 55.52 ± 1.41 nm) and its ionic form in D. melanogaster. B₂ O₃ NPs were supplied to third instar larvae at concentrations ranging from 0.1-10 mM. Toxicity, intracellular oxidative stress (reactive oxygen species, ROS), phenotypic alterations, genotoxic effect (via the wing somatic mutation and recombination test (SMART), and DNA damage (via Comet assay) were the end-points evaluated. B₂ O₃ NPs did not cause any mutagenic/recombinogenic effects in all tested non-toxic concentrations in Drosophila SMART. Negative data were also obtained with the ionic form. Exposure to B₂ O₃ NPs and its ionic form (at two highest concentrations, 2.5 and 5 mM) was found to induce DNA damage in Comet assay. Additionally, ROS induction in hemocytes and phenotypic alterations were determined in the mouths and legs of Drosophila. This study is the first study reporting genotoxicity data in the somatic cells of Drosophila larvae, emphasizing the importance of D. melanogaster as a model organism in investigating the different biological effects in a concentration dependent manner caused by B₂ O₃ NPs and its ionic form. The obtained in vivo results contribute to improvement the genotoxicity database on the B₂ O₃ NPs.

Apoptotic and histopathological defects enhanced by titanium dioxide nanoparticles in male mice after short-term exposure

Titanium dioxide nanoparticles (TiO2NPs) are commercially utilized in diverse fields. Therefore, the current study investigated the apoptotic and histopathological defects that were caused in male mice following intraperitoneal (i.p) injection of TiO2NPs for 28 days. Doses: 2.5, 5.0, 10.0 and 20.0 mg/kg body weight were applied (10 mice for each group). Results revealed that, lactate dehydrogenase (LDH) activity was significantly increased in homogenates of liver, spleen, kidney, lung, heart, and muscles of treated animals, respect to their controls. Also, significant alterations in acid and alkaline phosphatase (ACP and ALP) activities were reported. The dose 5.0 mg/kg exhibited a significant decline in cell viability of blood samples (74.9 %) (P 0.05 = 0.0177), followed by 2.5 mg/kg (80.8 %), and finally the 10.0 mg/kg (81.8 %) with respect to control (96.3 %). Additionally, significant increases of expressed proteins of caspases-3 and-7 were noticed in cells of the treated animals. Ultrastructural investigations in sections of liver, kidney, lung and spleen of the treated animals showed significant defects, especially in the nucleus, mitochondria and rough endoplasmic reticulum (RER), compared to normal patterns of the control. Also, significant induction of nanoparticle (NPs)-phagolysosomes was visualized in sections of the treated animals. The present findings might provide evidence for the risk pattern of TiO2NPs in mammals after short-term exposure. So, TiO2NPs-based commercial products have now increased in the markets, and it is prudent to investigate their mammalian toxicology.

Multi-walled carbon nanotubes inhibit potential detoxification of dioxin-mediated toxicity by blocking the nuclear translocation of aryl hydrocarbon receptor

Despite numerous studies on effects of environmental accumulation of nano-pollutants, the influence of nanoparticles on the biological perturbations of coexisting pollutants in the environment remained unknown. The present study aimed at elucidating the perturbations of six environmental nanoparticles on detoxification of dioxin-induced toxicity at cellular level. We discovered that there was no remarkable difference in the cell uptake and intracellular distributions of these six nanoparticles. However, they have different effects on the detoxification of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Multi-walled carbon nanotubes (MWCNTs) inhibited the translocation of aryl hydrocarbon receptor (AhR) from cytosol to the nucleus, leading to the downregulation of cytochrome P450 family 1 subfamily A member 1 (CYP1A1) and inhibition of detoxification function. These findings demonstrate that MWCNTs can impact the potential detoxification of dioxin-induced toxicity through modulating AhR signaling pathway. Co-exposures to MWCNTs and dioxin may cause even more toxicity than single exposure to dioxin or MWCNTs alone.

Anti-toxoplasma and Cytotoxic Activities of Holothuria leucospilota Extract and TiO2NPs In vitro and In vivo

BACKGROUND

An impressive treatment for toxoplasmosis is the combinatory use of sulfadiazine and pyrimethamine. However, both the drugs involve significant side effects and toxicity for the host. Therefore, the discovery of new anti-toxoplasma medications with high efficacy and less to no side effects is urgently needed.

OBJECTIVE

This study aimed to evaluate the anti-toxoplasmic effects of Holothuria leucospilota (H. leucospilota) extract and TiO₂NPs on the cell death of Toxoplasma gondii (T. gondii) tachyzoites in vitro and serum liver enzymes (AST, ALT, and ALP), and also to evaluate the immune response and production of IL-5, IFN-γ, and TNF-α in a mouse model.

MATERIALS AND METHODS

The cytotoxicity of TiO₂NPs and H. leucospilota extract against the tachyzoite of T. gondii was evaluated by the methyl thiazolyl tetrazolium (MTT) assay. The levels of serum TNF-α, IFN-γ, IL-5, and liver enzymes were measured, as well. All the groups were subjected to T. gondii, and the survival rate of experimental mice was evaluated.

RESULTS

Our findings suggested in vivo and in vitro anti-toxoplasmic activity of TiO₂NPs and H. leucospilota extract by inhibiting the proliferation and invasion of T. gondii tachyzoite. In addition, a significant increase in IFN-γ and TNF-α production was observed in mice treated with high doses of TiO₂NPs and H. leucospilota extract. However, IL-5 levels decreased in TiO₂NPs and H. leucospilota extract-treated mice. Our results also showed a highly significant increase (P < 0.05) in the levels of ALT, AST, and ALP in the groups injected with TiO₂NPs and H. leucospilota extract, but not the control group.

CONCLUSION

TiO₂NPs and H. leucospilota extract have greater anti-toxoplasma effects in vitro and in vivo. These two compounds could be considered as a candidate for use against toxoplasmosis, both therapeutically and prophylactically.

Impact of Polyphenol Interactions with Titanium Dioxide Nanoparticles on Their Bioavailability and Antioxidant Activity

Titanium dioxide is widely utilized as a pigment in the food industry to enhance the whiteness or brightness of foods and beverages. The powdered forms of titanium dioxide used as food ingredients contain a substantial fraction of nanoparticles (d < 100 nm), which may have adverse effects on human health. This is a model study that investigated the molecular interactions between TiO₂ nanoparticles and selected polyphenols, as well as their influence on the in vitro bioavailability and antioxidant activity of the polyphenols. Our results showed that the chemical structure of polyphenols significantly influenced their binding affinity to TiO₂ nanoparticle surfaces, with those possessing vicinal trihydroxy groups having the highest binding affinities. The presence of TiO₂ nanoparticles was shown to reduce the bioavailability of polyphenols using an in vitro digestion model. This effect was mainly ascribed to the formation of large TiO₂ nanoparticle-polyphenol complex agglomerates that could not pass through the pores in the dialysis tube used to simulate the epithelium layer. Additionally, the binding of polyphenols to the surfaces of TiO₂ nanoparticles reduced their antioxidant activity. This study provides valuable insights into the impact of inorganic nanoparticles on the bioavailability and bioactivity of polyphenols.

Novel Strategies for Disrupting Cancer-Cell Functions with Mitochondria-Targeted Antitumor Drug-Loaded Nanoformulations

Any variation in normal cellular function results in mitochondrial dysregulation that occurs in several diseases, including cancer. Such processes as oxidative stress, metabolism, signaling, and biogenesis play significant roles in cancer initiation and progression. Due to their central role in cellular metabolism, mitochondria are favorable therapeutic targets for the prevention and treatment of conditions like neurodegenerative diseases, diabetes, and cancer. Subcellular mitochondria-specific theranostic nanoformulations for simultaneous targeting, drug delivery, and imaging of these organelles are of immense interest in cancer therapy. It is a challenging task to cross multiple barriers to target mitochondria in diseased cells. To overcome these multiple barriers, several mitochondriotropic nanoformulations have been engineered for the transportation of mitochondria-specific drugs. These nanoformulations include liposomes, dendrimers, carbon nanotubes, polymeric nanoparticles (NPs), and inorganic NPs. These nanoformulations are made mitochondriotropic by conjugating them with moieties like dequalinium, Mito-Porter, triphenylphosphonium, and Mitochondria-penetrating peptides. Most of these nanoformulations are meticulously tailored to control their size, charge, shape, mitochondriotropic drug loading, and specific cell-membrane interactions. Recently, some novel mitochondria-selective antitumor compounds known as mitocans have shown high toxicity against cancer cells. These selective compounds form vicious oxidative stress and reactive oxygen species cycles within cancer cells and ultimately push them to cell death. Nanoformulations approved by the FDA and EMA for clinical applications in cancer patients include Doxil, NK105, and Abraxane. The novel use of these NPs still faces tremendous challenges and an immense amount of research is needed to understand the proper mechanisms of cancer progression and control by these NPs. Here in this review, we summarize current advancements and novel strategies of delivering different anticancer therapeutic agents to mitochondria with the help of various nanoformulations.

Foodborne TiO2 Nanoparticles Induced More Severe Hepatotoxicity in Fructose-Induced Metabolic Syndrome Mice via Exacerbating Oxidative Stress-Mediated Intestinal Barrier Damage

The hazard of titanium dioxide nanoparticles (TiO₂ NPs) in diseased population should be given focus due to the huge number of these NPs in foods and medicine. This study aimed to evaluate the stronger biological adverse effect of oral exposure to TiO₂ NPs in a fructose-induced metabolic syndrome mouse model. Compared to the normal mice, low-dose (2 mg/kg) TiO₂ NPs did not cause severe hepatotoxicity. However, high-dose (20 mg/kg) TiO₂ NPs induced aggravated hepatic inflammation, fibrosis, and apoptosis, with substantial alteration of related biochemical parameters in the mouse model. Moreover, significantly increased Ti and lipopolysaccharide burden were observed in metabolic syndrome murine liver and serum, which possibly worsened the portend intestinal leakage. The expression of tight junction-related protein showed that TiO₂ NPs induced further increase in serious intestinal permeability. The intestinal inflammatory and oxidative stress response in the model were also assessed. Results showed that TiO₂ NPs caused more severe intestinal inflammatory injury by intensifying the oxidative stress in metabolic syndrome mice and then induced further liver injury. This work provides information on the insights into the toxic effect of TiO₂ NPs in sub-healthy population.

Reactive oxygen species: the root cause of nanoparticle-induced toxicity in Drosophila melanogaster

Nanotechnology is a rapidly developing technology in the twenty-first century. Nanomaterials are extensively used in numerous industries including cosmetics, food, medicines, industries, agriculture, etc. Along with its wide application toxicity is also reported from studies of various model organisms including Drosophila. The toxicity reflects cytotoxicity, genotoxicity, and teratogenicity. The current study correlates the toxicity as a consequence of reactive oxygen species (ROS) generated owing to the presence of nanoparticles with the living cell. ROS mainly includes hydroxyl ions, peroxide ions, superoxide anions, singlet oxygen, and hypochlorous acids. An elevated level of ROS can damage the cells by various means. To protect the body from excess ROS, living cells possess a set of antioxidant enzymes which includes peroxidase, glutathione peroxidase, and catalase. If the antioxidant enzymes cannot nullify the elevated ROS level than DNA damage, cell damage, cytotoxicity, apoptosis, and uncontrolled cell regulations occur resulting in abnormal physiological and genotoxic conditions. Herewith, we are reporting various morphological and physiological defects caused after nanoparticle treatment as a function of redox imbalance.

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO₂) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO₂, as well as the toxicity interaction between NPTiO₂ and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO₂ alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO₂ alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO₂. In general, the results of this study indicated that both NPTiO₂ alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.

Hepatotoxicity induced by nanomaterials: mechanisms and in vitro models

The unique physicochemical properties of materials at nanoscale have opened a plethora of opportunities for applications in the pharmaceutical and medical field, but also in consumer products from food and cosmetics industries. As a consequence, daily human exposure to nanomaterials through distinct routes is considerable and, therefore, may raise health concerns. Many nanomaterials have been described to accumulate and induce adversity in the liver. Among these, silica and some types of metallic nanoparticles are the most broadly used in consumer products and, therefore, the most studied and reported. The reviewed literature was collected from PubMed.gov during the month of March 2020 using the search words "nanomaterials induced hepatotoxicity", which yielded 181 papers. This present paper reviews the hepatotoxic effects of nanomaterials described in in vitro and in vivo studies, with emphasis on the underlying mechanisms. The induction of oxidative stress and inflammation are the manifestations of toxicity most frequently reported following exposure of cells or animal models to different nanomaterials. Furthermore, the available in vitro models for the evaluation of the hepatotoxic effects of nanomaterials are discussed, highlighting the continuous interest in the development of more advanced and reliable in vitro models for nanotoxicology.

C-reactive Protein Signaling and Chromosomal Abnormalities in Nanotoxicity Induced via Different Doses of TiO2 (80 nm) Boost Liver Function

The wide application of nanotechnology merits the need to clarify their nanotoxicity. In vivo studies have raised concerns about the toxicity of titanium dioxide nanoparticles (TiO₂ NPs), but there are limited data on chromosomal abnormalities induced in hepatic tissue. In this article, the toxicity of three IP doses of TiO₂ NPs (80 nm) (50, 250, and 500 mg/kg) through three time intervals (up to 7, 15, and 45 days) on liver tissue was assessed. Hepatic catalase (CAT), glutathione (GSH), nitric oxide (NOx), and malondialdehyde (MDA) levels varied with the administered dose and exposure time of TiO₂ NPs. As a result, TiO₂ NPs caused a statistically significant decrease in hepatic CAT and GSH activities and a significant alleviation in MDA and NOx levels (p < 0.05), suggesting that the liver exposed to these various doses of TiO₂ NPs suffered from severe oxidative stress. The extent of depletion of antioxidant enzymes and the elevation of MDA and NOx in the liver exposed to the highest dose and duration of TiO₂ NPs 500 mg for 45 days was the greatest, suggesting that the toxicity might be dose and time dependent. Further, C-reactive protein (CRP) as an inflammatory marker was also alleviated, in addition to the apparent chromosomal aberration and liver pathologies including necrotic and fibrotic hepatocytes after exposure to 250 and 500 mg/kg of TiO₂ NPs for 14 and 45 days that were deduced. Hence, nanotechnology-based industries are growing rapidly leading to large-scale production of engineered nanoparticles. They contribute to increased chances of human NPs exposure and health risk.

[Influence of oxidative/antioxidative biomarkers and inflammatory cytokines on rats after sub-acute orally administration of titanium dioxide nanoparticles]

OBJECTIVE

To evaluate the sub-acute oral effect of titanium dioxide (TiO₂) nanoparticles on the oxidation/antioxidation biomarkers and inflammatory cytokines in blood, liver, intestine, and colon in rats.

METHODS

Twenty four 4-week-old clean-grade Sprague Dawley (SD) rats were randomly devided into 4 groups by body weight (n=6, control, low, middle, and high), in which the rats were orally exposed to TiO₂ nanoparticles at doses of 0, 2, 10 and 50 mg/kg body weight/day for 28 consecutive days separately. Food intake, body weight and abnormal behaviors during the experiment were recorded. The rats were euthanized on the 29th day. The blood was collected via abdominal aortic method and centrifuged to collect the serum. Tissues from liver, intestine and colon were collected and homogenated. Then enzyme-linked immunosorbent assay (ELISA) and microwell plate methods were used to detect oxidation/antioxidation biomarkers including superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px), total mercapto (T-SH), glutathione disulfide (GSSG), malomdialdehvde (MDA) and inflammatory cytokines including interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in the serum, liver, intestine and colon in the rats.

RESULTS

Compared with the control group, no significant differences in body weight, food intake and organ coefficients were observed in all the three groups after TiO₂ gavage. No significant changes in GSH, GSH-Px, T-SH, and IL-6 were observed. Compared with the control group, significant increase of SOD activity in serum in high dose group, signi-ficant increase of GSSG concentration in intestine in middle and high dose group and significant increase of MDA concentration in liver in low and high dose group were observed. Compared with the control group, a significant increase of TNF-α in liver in middle and high dose group was observed.

CONCLUSION

TiO₂ nanoparticle can increase antioxidant enzymes activities in blood, increase oxidative biomarkers in liver and intestine, increase inflammatory cytokines in liver in rats after a 28-day sub-acute orally administration. Among blood, liver, intestine, and colon, liver is most sensitive to the toxicity induced by TiO₂ nanoparticles, followed by intestine, blood, and colon in sequence.

Foodborne Titanium Dioxide Nanoparticles Induce Stronger Adverse Effects in Obese Mice than Non-Obese Mice: Gut Microbiota Dysbiosis, Colonic Inflammation, and Proteome Alterations

The recent ban of titanium dioxide (TiO₂ ) as a food additive (E171) in France intensified the controversy on safety of foodborne-TiO₂ nanoparticles (NPs). This study determines the biological effects of TiO₂ NPs and TiO₂ (E171) in obese and non-obese mice. Oral consumption (0.1 wt% in diet for 8 weeks) of TiO₂ (E171, 112 nm) and TiO₂ NPs (33 nm) does not cause severe toxicity in mice, but significantly alters composition of gut microbiota, for example, increased abundance of Firmicutes phylum and decreased abundance of Bacteroidetes phylum and Bifidobacterium and Lactobacillus genera, which are accompanied by decreased cecal levels of short-chain fatty acids. Both TiO₂ (E171) and TiO₂ NPs increase abundance of pro-inflammatory immune cells and cytokines in the colonic mucosa, indicating an inflammatory state. Importantly, TiO₂ NPs cause stronger colonic inflammation than TiO₂ (E171), and obese mice are more susceptible to the effects. A microbiota transplant study demonstrates that altered fecal microbiota by TiO₂ NPs directly mediate inflammatory responses in the mouse colon. Furthermore, proteomic analysis shows that TiO₂ NPs cause more alterations in multiple pathways in the liver and colon of obese mice than non-obese mice. This study provides important information on the health effects of foodborne inorganic nanoparticles.

Toxicity of TiO2 Nanoparticles: Validation of Alternative Models

There are many studies concerning titanium dioxide (TiO2) nanoparticles (NP) toxicity. Nevertheless, there are few publications comparing in vitro and in vivo exposure, and even less comparing air-liquid interface exposure (ALI) with other in vitro and in vivo exposures. The identification and validation of common markers under different exposure conditions are relevant for the development of smart and quick nanotoxicity tests. In this work, cell viability was assessed in vitro by WST-1 and LDH assays after the exposure of NR8383 cells to TiO2 NP sample. To evaluate in vitro gene expression profile, NR8383 cells were exposed to TiO2 NP during 4 h at 3 cm2 of TiO2 NP/cm2 of cells or 19 μg/mL, in two settings-submerged cultures and ALI. For the in vivo study, Fischer 344 rats were exposed by inhalation to a nanostructured aerosol at a concentration of 10 mg/m3, 6 h/day, 5 days/week for 4 weeks. This was followed immediately by gene expression analysis. The results showed a low cytotoxic potential of TiO2 NP on NR8383 cells. Despite the absence of toxicity at the doses studied, the different exposures to TiO2 NP induce 18 common differentially expressed genes (DEG) which are involved in mitosis regulation, cell proliferation and apoptosis and inflammation transport of membrane proteins. Among these genes, we noticed the upregulation of Ccl4, Osm, Ccl7 and Bcl3 genes which could be suggested as early response biomarkers after exposure to TiO2 NP. On the other hand, the comparison of the three models helped us to validate the alternative ones, namely submerged and ALI approaches.

Possible effects of titanium dioxide particles on human liver, intestinal tissue, spleen and kidney after oral exposure

Recent studies reported adverse liver effects and intestinal tumor formation after oral exposure to titanium dioxide (TiO₂). Other oral toxicological studies, however, observed no effects on liver and intestine, despite prolonged exposure and/or high doses. In the present assessment, we aimed to better understand whether TiO₂ can induce such effects at conditions relevant for humans. Therefore, we focused not only on the clinical and histopathological observations, but also used Adverse Outcome Pathways (AOPs) to consider earlier steps (Key Events). In addition, aiming for a more accurate risk assessment, the available information on organ concentrations of Ti (resulting from exposure to TiO₂) from oral animal studies was compared to recently reported concentrations found in human postmortem organs. The overview obtained with the AOP approach indicates that TiO₂ can trigger a number of key events in liver and intestine: Reactive Oxygen Species (ROS) generation, induction of oxidative stress and inflammation. TiO₂ seems to be able to exert these early effects in animal studies at Ti liver concentrations that are only a factor of 30 and 6 times higher than the median and highest liver concentration found in humans, respectively. This confirms earlier conclusions that adverse effects on the liver in humans as a result of (oral) TiO₂ exposure cannot be excluded. Data for comparison with Ti levels in human intestinal tissue, spleen and kidney with effect concentrations were too limited to draw firm conclusions. The Ti levels, though, are similar or higher than those found in liver, suggesting these tissues may be relevant too.

Co-exposure to the food additives SiO2 (E551) or TiO2 (E171) and the pesticide boscalid increases cytotoxicity and bioavailability of the pesticide in a tri-culture small intestinal epithelium model: Potential health implications

Many toxicity investigations have evaluated the potential health risks of ingested engineered nanomaterials (iENMs); however, few have addressed the potential combined effects of iENMs and other toxic compounds (e.g. pesticides) in food. To address this knowledge gap, we investigated the effects of two widely used, partly nanoscale, engineered particulate food additives, TiO2 (E171) and SiO2 (E551), on the cytotoxicity and cellular uptake and translocation of the pesticide boscalid. Fasting food model (phosphate buffer) containing iENM (1% w/w), boscalid (10 or 150 ppm), or both, was processed using a simulated in vitro oral-gastric-small intestinal digestion system. The resulting small intestinal digesta was applied to an in vitro tri-culture small intestinal epithelium model, and effects on cell layer integrity, viability, cytotoxicity and production of reactive oxygen species (ROS) were assessed. Boscalid uptake and translocation was also quantified by LC/MS. Cytotoxicity and ROS production in cells exposed to combined iENM and boscalid were greater than in cells exposed to either iENM or boscalid alone. More importantly, translocation of boscalid across the tri-culture cellular layer was increased by 20% and 30% in the presence of TiO2 and SiO2, respectively. One possible mechanism for this increase is diminished epithelial cell health, as indicated by the elevated oxidative stress and cytotoxicity observed in co-exposed cells. In addition, analysis of boscalid in digesta supernatants revealed 16% and 30% more boscalid in supernatants from samples containing TiO2 and SiO2, respectively, suggesting that displacement of boscalid from flocculated digestive proteins by iENMs may also contribute to the increased translocation.

Chemical induction of hepatic apoptosis in rodents

The urge of identifying new pharmacological interventions to prevent or attenuate liver injury is of critical importance and needs an expanded experimental toolbox. Hepatocyte injury and cellular death is a prominent feature behind the pathology of liver diseases. Several research activities focused on identifying chemicals and hepatotoxicants that induce cell death by apoptosis, in addition to presenting its corresponding signaling pathway. Although such efforts provided further understanding of the mechanisms of cell death, it has also raised confusion concerning identifying the involvement of several modes of cell death including apoptosis, necrosis and fibrosis. The current review highlights the ability of several chemicals and potential hepatotoxicants to induce liver damage in rodents by means of apoptosis while the probable involvement of other modes of cell death is also exposed. Thus, several chemical substances including hepatotoxins, mycotoxins, hyperglycemia inducers, metallic nanoparticles and immunosuppressant drugs are reviewed to explore the hepatic cytotoxic spectrum they could exert on hepatocytes of rodents. In addition, the current review address the mechanism by which hepatotoxicity is initiated in hepatocytes in different rodents aiding the researcher in choosing the right animal model for a better research outcome.

Impact of Titanium Dioxide on the Bioaccessibility of β-Carotene in Emulsions with Different Particle Sizes

Commercial, titanium dioxide (TiO₂) ingredients used as color additives (E171) in foods and beverages contain an appreciable fraction of particles in the nanoscale range. At present, little information is available regarding the potential impact of food-grade TiO₂ nanoparticles on the gastrointestinal fate of co-ingested bioactives, such as nutraceuticals. In this study, the impact of TiO₂ on the bioaccessibility of β-carotene solubilized in model food emulsions was investigated using a simulated gastrointestinal tract model. Raman spectroscopy showed that there was no charge transfer between β-carotene and TiO₂ but that some β-carotene absorbed to the surface of TiO₂ particles. The initial particle size of the food emulsion did not significantly affect β-carotene bioaccessibility, probably because the same amount of free fatty acids (FFAs) was released by the end of digestion. The addition of TiO₂ at levels typically found in foods also had no significant impact on β-carotene bioaccessibility and FFA release, which suggested that this type of inorganic particle does not interfere with the gastrointestinal fate of these lipophilic bioactive agents. This information is important for ensuring the safety of inorganic nanoparticle utilization within the food industry.

Transcriptomics analysis reveals new insights in E171-induced molecular alterations in a mouse model of colon cancer

Titanium dioxide as a food additive (E171) has been demonstrated to facilitate growth of chemically induced colorectal tumours in vivo and induce transcriptomic changes suggestive of an immune system impairment and cancer development. The present study aimed to investigate the molecular mechanisms behind the tumour stimulatory effects of E171 in combination with azoxymethane (AOM)/dextran sodium sulphate (DSS) and compare these results to a recent study performed under the same conditions with E171 only. BALB/c mice underwent exposure to 5 mg/kg_bw/day of E171 by gavage for 2, 7, 14, and 21 days. Whole genome mRNA microarray analyses on the distal colon were performed. The results show that E171 induced a downregulation of genes involved in the innate and adaptive immune system, suggesting impairment of this system. In addition, over time, signalling genes involved in colorectal cancer and other types of cancers were modulated. In relation to cancer development, effects potentially associated with oxidative stress were observed through modulation of genes related to antioxidant production. E171 affected genes involved in biotransformation of xenobiotics which can form reactive intermediates resulting in toxicological effects. These transcriptomics data reflect the early biological responses induced by E171 which precede tumour formation in an AOM/DSS mouse model.

Effects of Different Temperatures on the Chemical Structure and Antitumor Activities of Polysaccharides from Cordyceps militaris

The effects of different extraction temperatures (4 and 80 °C) on the physicochemical properties and antitumor activity of water soluble polysaccharides (CMPs-4 and CMPs-80) from Cordyceps militaris (C. militaris) were evaluated in this study. The results of gas chromatography (GC) and high-performance gel permeation chromatography (HPGPC) showed that a higher extraction temperature could degrade the polysaccharides with 188 kDa, mainly composed of glucose, and increase the dissolution rate of polysaccharides about 308 kDa, mainly consisting of rhamnose and galactose. In addition, the CMPs displayed the same sugar ring and category of glycosidic linkage based on Fourier-transform infrared spectroscopy (FTIR) analysis, however, their invisible structural difference occurred in the specific rotation and conformational characteristics according to the results of specific optical rotation measurement and Congo red test. In vitro antitumor experiments indicated that CMPs-4 possessed stronger inhibitory effects on human esophagus cancer Eca-109 cells by inducing cell apoptosis more than CMPs-80 did. These findings demonstrated that the polysaccharides extracted with cold water (4 °C) could be applied as a novel alternative chemotherapeutic agent or dietary supplement with its underlying antitumor property.

Hepatoprotective effect of thymol against subchronic toxicity of titanium dioxide nanoparticles: Biochemical and histological evidences

The study was aimed to investigate the protective action of thymol against nano titanium dioxide (nano-TiO₂) induced hepatotoxicity in rats. To achieve this purpose, the rats were divided into four groups (n = 6) including control, nano-TiO₂ (100 mg/kg), nano-TiO₂ + thymol (10 mg/kg) and nano-TiO₂ + thymol (30 mg/kg). Intragastric (IG) administration of nano-TiO₂ for 60 consecutive days caused widespread histological changes and significantly induced oxidative stress in the liver tissues as manifested by the rise in serum transaminase activities accompanied by marked decline of enzymatic (catalase, superoxide dismutase and glutathione peroxidase) and non-enzymatic (ferric reducing antioxidant power and glutathione) antioxidant levels, and rise of malondialdehyde levels in liver tissue. Pretreatment with thymol (IG) prior to nano-TiO₂ administration significantly ameliorated all of biochemical and histopathological alterations in a dose-dependent manner. In conclusion, thymol effectively protects against nano-TiO₂-induced hepatotoxicity in rats by its antioxidant properties.

Toxicity of nanotitanium dioxide (TiO2-NP) on human monocytes and their mitochondria

The effect of nanotitanium dioxide (TiO₂-NP) in human monocytes is still unknown. Therefore, an understanding of probable cytotoxicity of TiO₂-NP on human monocytes and underlining the mechanisms involved is of significant interest. The aim of this study was to assess the cytotoxicity of TiO₂-NP on human monocytes. Using biochemical and flow cytometry assessments, we demonstrated that addition of TiO₂-NP at 10 μg/ml concentration to monocytes induced cytotoxicity following 12 h. The TiO₂-NP-induced cytotoxicity on monocytes was associated with intracellular reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, TiO₂-NP triggers oxidative stress and organelles damages in monocytes which are important cells in defense against foreign agents. Finally, our findings suggest that use of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with TiO₂-NP.

Impact of co-exposure of aldrin and titanium dioxide nanoparticles at biochemical and molecular levels in Zebrafish

Aldrin (ALD), a persistent-organic-pollutant (POP), an organochlorine-cyclodiene-pesticide is highly toxic in nature. Titanium dioxide nanoparticles (TNP) are widely used for various industrial applications. Despite the remarkable research on pesticide toxicity, the work with impact of nanoparticles on POP has been dealt with marginally. Chemicals co-exist in the environment and exhibit interactive effects. An investigation was carried out to evaluate the individual and combined effects of ALD (6 ppm) and TNP (60 ppm) exposure at sub-lethal concentration for 24 h in zebrafish. Significant reversal of lipid peroxidation level in liver and brain tissues and restoration in enhanced catalase activity in all examined tissues were observed in combined group. For other parameters, combined exposure of ALD and TNP does not show significant reversal action on ALD toxicity. Further studies are inline to understand combined effects of both to achieve significant reversal of ALD toxicity by TNP nanoparticles with threshold concentration of aldrin.

Gestational exposure to titanium dioxide nanoparticles impairs the placentation through dysregulation of vascularization, proliferation and apoptosis in mice

Background

Titanium dioxide nanoparticles (TiO₂ NPs) have recently found applications in a wide variety of consumer goods. TiO₂ NPs exposure significantly increases fetal deformities and mortality. However, the potential toxicity of TiO₂ NPs on the growth and development of placenta has been rarely studied during mice pregnancy.

Purpose

The objective of this study was to investigate the effects of maternal exposure of TiO₂ NPs on the placentation.

Methods

Mice were administered TiO₂ NPs by gavage at 0, 1 and 10 mg/kg/day from gestational day (GD) 1 to GD 13. Uteri and placentas from these mice were collected and counted the numbers of implanted and resorbed embryo and measured the placental weight on GD 13. Placental morphometry was observed by hematoxylin and eosin staining. The levels of Hand1, Esx1, Eomes, Hand2, Ascl2 and Fra1 mRNA were assessed by qRT-PCR. Uterine NK (uNK) cells were detected by using DBA lectin. Laminin immunohistochemical staining was to identify fetal vessels. Western blotting and transmission electron micrograph (TEM) were used to assess the apoptosis of placenta.

Results

No treatment-related difference was observed in the numbers of implanted and resorbed embryos and weight of placenta between the groups. However, 1 mg/kg/day TiO₂ NPs treatment significantly reduced the ratio of placenta/body weight on GD 13. The proportion of spongiotrophoblast in the 10 mg/kg/day dose group became higher than that in the control group, yet that of labyrinth was significantly lower in 10 mg/kg/day mice. The expression levels of Hand1, Esx1, Eomes, Hand2, Ascl2 and Fra1 mRNA markedly decreased in TiO₂ NP treated placentas. Furthermore, TiO₂ NPs treatment impaired the formation of intricate networks of fetal vessels and reduced the number of uNK cells, and inhibited proliferation and induced apoptosis of placenta by nuclear pyknosis, the activation of caspase-3 and upregulation of Bax protein and downregulation of Bcl-2 protein on GD 13.

Conclusion

Gestational exposure to TiO₂ NPs significantly impairs the growth and development of placenta in mice, with a mechanism that seems to be involved in the dysregulation of vascularization, proliferation and apoptosis. Therefore, our results suggested the need for great caution while handling of the nanomaterials by workers and specially pregnant consumers.

Effect of titanium dioxide nanoparticles on glucose homeostasis after oral administration

As food additives, titanium dioxide nanoparticles (TiO₂ NPs) have been widely used in various products that are usually simultaneously consumed with a high content of sugar, thus necessitating research on the effect of TiO₂ NPs on glucose homeostasis. We conducted an animal study to explore the effect of orally administrated TiO₂ NPs on glucose absorption and metabolism in rats at 0, 2, 10 and 50 mg kg^-1 body weight day^-1 for 30 and 90 days. The results showed that oral exposure to TiO₂ NPs caused a slight and temporary hypoglycemic effect in rats at 30 days post-exposure but recovered at 90 days post-exposure. Decreased levels of intestinal glucose absorption and increased levels of hepatic glucose metabolism may be responsible for the hypoglycemic effect. Remodeling of the villi in the small intestine that decreased the surface area available for glucose absorption and increased levels of hepatic glucose uptake, utilization and storage related to hepatocellular injury are supposed to be the mechanisms. Our results demonstrated that dietary intake of TiO₂ NPs as food additives could affect the absorption and metabolism of glucose.

Titanium dioxide nanoparticles induce mitochondria-associated apoptosis in HepG2 cells

Widespread applications of nanosized materials over the past decade have prompted investigations of desirable properties and potential hazards to humans and the environment.

The Potential Liver, Brain, and Embryo Toxicity of Titanium Dioxide Nanoparticles on Mice

Nanoscale titanium dioxide (nano-TiO₂) has been widely used in industry and medicine. However, the safety of nano-TiO₂ exposure remains unclear. In this study, we evaluated the liver, brain, and embryo toxicity and the underlying mechanism of nano-TiO₂ using mice models. The results showed that titanium was distributed to and accumulated in the heart, brain, spleen, lung, and kidney of mice after intraperitoneal (i.p.) nano-TiO₂ exposure, in a dose-dependent manner. The organ/body weight ratios of the heart, spleen, and kidney were significantly increased, and those of the brain and lung were decreased. High doses of nano-TiO₂ significantly damaged the functions of liver and kidney and glucose and lipid metabolism, as showed in the blood biochemistry tests. Nano-TiO₂ caused damages in mitochondria and apoptosis of hepatocytes, generation of reactive oxygen species, and expression disorders of protective genes in the liver of mice. We found ruptured and cracked nerve cells and inflammatory cell infiltration in the brain. We also found that the activities of constitutive nitric oxide synthases (cNOS), inducible NOS (iNOS), and acetylcholinesterase, and the levels of nitrous oxide and glutamic acid were changed in the brain after nano-TiO₂ exposure. Ex vivo mouse embryo models exhibited developmental and genetic toxicity after high doses of nano-TiO₂. The size of nano-TiO₂ particles may affect toxicity, larger particles producing higher toxicity. In summary, nano-TiO₂ exhibited toxicity in multiple organs in mice after exposure through i.p. injection and gavage. Our study may provide data for the assessment of the risk of nano-TiO₂ exposure on human health.

Gene expression profiling in colon of mice exposed to food additive titanium dioxide (E171)

Dietary factors that may influence the risks of colorectal cancer, including specific supplements, are under investigation. Previous studies showed the capacity of food additive titanium dioxide (E171) to induce DNA damage in vitro and facilitate growth of colorectal tumours in vivo. This study aimed to investigate the molecular mechanisms behind these effects after E171 exposure. BALB/c mice were exposed by gavage to 5 mg/kg_bw/day of E171 for 2, 7, 14, and 21 days. Transcriptome changes were studied by whole genome mRNA microarray analysis on the mice's distal colons. In addition, histopathological changes as well as a proliferation marker were analysed. The results showed significant gene expression changes in the olfactory/GPCR receptor family, oxidative stress, the immune system and of cancer related genes. Transcriptome analysis also identified genes that thus far have not been included in known biological pathways and can induce functional changes by interacting with other genes involved in different biological pathways. Histopathological analysis showed alteration and disruption in the normal structure of crypts inducing a hyperplastic epithelium. At cell proliferation level, no consistent increase over time was observed. These results may offer a mechanistic framework for the enhanced tumour growth after ingestion of E171 in BALB/c mice.

Genotoxicity and gene expression analyses of liver and lung tissues of mice treated with titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO₂ NPs) are used in paints, plastics, papers, inks, foods, toothpaste, pharmaceuticals and cosmetics. However, TiO₂ NPs cause inflammation, pulmonary damage, fibrosis and lung tumours in animals and are possibly carcinogenic to humans. Although there are a large number of studies on the toxicities of TiO₂ NPs, the data are inconclusive and the mechanisms underlying the toxicity are not clear. In this study, we used the Comet assay to evaluate genotoxicity and whole-genome microarray technology to analyse gene expression pattern in vivo to explore the possible mechanisms for toxicity and genotoxicity of TiO₂ NPs. Mice were treated with three daily i.p. injections of 50 mg/kg 10 nm anatase TiO₂ NPs and sacrificed 4 h after the last treatment. The livers and lungs were then isolated for the Comet assay and whole genome microarray analysis of gene expression. The NPs were heavily accumulated in liver and lung tissues. However, the treatment was positive for DNA strand breaks only in liver measured with the standard Comet assay, but positive for oxidative DNA adducts in both liver and lung as determined with the enzyme-modified Comet assay. The genotoxicity results suggest that DNA damage mainly resulted from oxidised nucleotides. Gene expression profiles and functional analyses revealed that exposure to TiO₂ NPs triggered distinct gene expression patterns in both liver and lung tissues. The gene expression results suggest that TiO₂ NPs impair DNA and cells by interrupting metabolic homeostasis in liver and by inducing oxidative stress, inflammatory responses and apoptosis in lung. These findings have broad implications when evaluating the safety of TiO₂ NPs used in numerous consumer products.

Synthesis of novel dibenzoxanthene derivatives and observation of apoptosis in human hepatocellular cancer cells

We have synthesized dibenzoxanthene derivatives 2a-2i via nucleophilic substitution of methoxyl group and evaluated underlying antitumor molecular mechanism of target compounds. Compounds showed high cytotoxic activities against BEL-7402, A549, HeLa and MG-63 cancer cells in the µM range. These compounds inhibited the cell growth of BEL-7402 cells at S or G2/M phase. The compounds 2a-2i also induced the apoptosis of BEL-7402 cells. In addition, compounds enhanced the level of intramolecular ROS and decreased the mitochondrial membrane potential. Western blot analysis showed caspase-3 were activated and the expression of Bcl-2 and Bcl-xl was down-regulated. According to given results, these dibenzoxanthenes exhibited a broad spectrum of antiproliferative effects on various tumors and therapeutic efficacy. Molecular mechanism indicated that induction of apoptosis was associated with DNA fragmentation, ROS generation, mitochondria dysfunction. Compounds induced apoptosis in BEL-7402 cells through the intrinsic ROS-mediated mitochondrial pathway.

Hormonal and organ-specific dysfunction induced by the interaction between titanium dioxide nanoparticles and salicylic acid in male mice

BACKGROUND

Nanomaterials coating gained much concern in orthopedic implants and cosmetics. Drug combination may be a promising strategy for treating multi-factorial diseases. Titanium dioxide (TDN) nanoparticles are being widely used in many industries as well as in medicine and pharmacology. Therefore, increased human and environmental exposure can be expected, which has put TDN under toxicological scrutiny, and it is necessary to address the potential health and safety implications of nanomaterials used in nanomedicine. The toxicity of titanium oxide nanoparticles (TDN) and salicylic acid (SA) separately or in combination was studied for 21 days.

METHODS

The liver and kidney biomarker were determined, and hormones and oxidative stress levels were detected in mice.

RESULTS

The intraperitoneal (i.p.) injection of TDN and SA in combination had a potential toxicological effect on major organs and hormonal homeostasis of mice. TDN and SA could antagonistically interact to affect the liver and kidney functions. No synergistic damage was observed in the liver function of mice that were treated with both TDN and SA as compared to the SA group. TDN acted as a synergistic agent to SA in the case of total cholesterol and total proteins levels. SA acted as antagonistic to the effect of TDN when injected together in mice because the effect on kidney functions is less than that predicted on the basis of the additive. The effect of co-administration of SA and TDN on the following hormones; triiodothyronine, thyroxine, estradiol II and insulin various among additive, potentiation, antagonistic and no effect, respectively as compared to TDN group. The interaction of TDN and SA was also found to induce oxidative stress as indicated by the increase in lipid peroxidation (LPO) levels. The decrease in the level of the reduced glutathione in the co-treated group indicated that there were no synergistic damages. SA and TDN co-administration could induce a potential increase in LPO levels in liver, kidney, and spleen but not in heart tissue. These results have not suggested that TDN and SA have a synergistic sub-chronic toxicity in mice after i.p. administration. SA may decrease the toxicity of TDN to some degree that could be related to the potentiation chemical reaction between SA and TDN.

CONCLUSIONS

Our results suggested that the damage observed in mice treated with TDN and SA is organ-specific and associated with hormonal homeostasis and oxidative damage.

Progress of in vivo studies on the systemic toxicities induced by titanium dioxide nanoparticles

Titanium dioxide nanoparticles (TiO2 NPs) are inorganic materials with a diameter of 1-100 nm. In recent years, TiO2 NPs have been used in a wide range of products, including food, toothpaste, cosmetics, medicine, paints and printing materials, due to their unique properties (high stability, anti-corrosion, and efficient photocatalysis). Following exposure via various routes including inhalation, injection, dermal deposition and gastrointestinal tract absorption, NPs can be found in various organs in the body potentially inducing toxic effects. Thus more attention to the safety of TiO2 NPs is necessary. Therefore, the present review aims to provide a comprehensive evaluation of the toxic effects induced by TiO2 NPs in the lung, liver, stomach, intestine, kidney, spleen, brain, hippocampus, heart, blood vessels, ovary and testis of mice and rats in in vivo experiments, and evaluate their potential toxic mechanisms. The findings will provide an important reference for human risk evaluation and management following TiO2 NP exposure.

Characterization of the Interactions between Titanium Dioxide Nanoparticles and Polymethoxyflavones Using Surface-Enhanced Raman Spectroscopy

Nanosized titanium dioxide (TiO₂) particles are commonly present in TiO₂ food additives (E171) and have been associated with potential adverse effects on health. However, little knowledge is available regarding the interactions between TiO₂ nanoparticles (NPs) and other food components, such as flavonoids. In this study, we aim to study the molecular interactions between TiO₂ anatase NPs and three structurally closely related polymethoxyflavones (PMFs, flavonoids found in citrus fruits), namely, 3',4'-didemethylnobiletin (DDN), 5-demethylnobiletin (5DN), and 5,3',4'-tridemethylnobiletin (TDN), using ultraviolet-visible (UV-vis) spectrometry and surface-enhanced Raman spectroscopy (SERS). In the UV-vis absorption spectra, bathochromic effects were observed after DDN and TDN conjugated with TiO₂ NPs. The results from SERS analysis clearly demonstrated that DDN and TDN could bind TiO₂ NPs with the functional groups 3'-OH and 4'-OH on ring B and formed charge-transfer complexes. However, 5DN with functional groups C═O on ring C and 5-OH on ring A could not bind TiO₂ NPs. Knowledge on the molecular interactions between TiO₂ NPs and food components, such as flavonoids, will facilitate the understanding of the fate of TiO₂ NPs during food processing and in the gastrointestinal tract after oral consumption.