Effect of titanium dioxide nanoparticle (TiO2-NP) exposure in a novel Amur sturgeon Acipenser schrenckii hepatocyte cell line.

In vitro cell culture is crucial for predicting the toxicity of titanium dioxide nanoparticle (TiO2-NP). However, assessing the toxicity of TiO2-NPs in sturgeon remains difficult given the lack of sufficient cell lines. We established and characterized the first hepatocyte cell line from Acipenser schrenckii liver tissue (ASL). This ASL cell line proliferated well in Dulbecco's modified Eagle's medium at 25°C and 10% fetal bovine serum. ASL cells with a chromosome number of 244 were successfully transfected with the pEGFP-N3 plasmid. The ASL cell line's origin was verified as A. schrenckii through mitochondrial cytochrome C oxidase I and mitochondrial 16S ribosomal RNA (rRNA) sequencing. Using the ASL cell line as an in vitro model, we found that TiO2-NP exposure decreased the viability and promoted the damage of ASL cells (96-h LC50 = 331.8 µg mL-1). Increased reactive oxygen species and malondialdehyde levels in ASL cells suggested oxidative stress under TiO2-NP exposure. We also observed dysregulation of aspartate aminotransferase and alanine aminotransferase levels. By detecting calcium ions and mitochondrial membrane potential indicators, we found that the apoptotic pathway induced by endoplasmic reticulum stress played a major role at low concentrations of TiO2-NP-induced stress. Both mitochondria-mediated and endoplasmic reticulum stress promoted apoptosis under increasing TiO2-NP concentrations. In conclusion, the ASL cell line established in this study is a useful in vitro model for toxicological studies of TiO2-NP exposure in fish.

Genome-wide DNA methylation sequencing reveals the involvement of ferroptosis in hepatotoxicity induced by dietary exposure to food-grade titanium dioxide.

BACKGROUND: Following the announcement by the European Food Safety Authority that the food additive titanium dioxide (E 171) is unsafe for human consumption, and the subsequent ban by the European Commission, concerns have intensified over the potential risks E 171 poses to human vital organs. The liver is the main organ for food-grade nanoparticle metabolism. It is increasingly being found that epigenetic changes may play an important role in nanomaterial-induced hepatotoxicity. However, the profound effects of E 171 on the liver, especially at the epigenetic level, remain largely unknown. METHODS: Mice were exposed orally to human-relevant doses of two types of E 171 mixed in diet for 28 and/or 84 days. Conventional toxicology and global DNA methylation analyses were performed to assess E 171-induced hepatotoxicity and epigenetic changes. Whole genome bisulfite sequencing and further ferroptosis protein detection were used to reveal E 171-induced changes in liver methylation profiles and toxic mechanisms. RESULTS: Exposed to E 171 for 28 and/or 84 days resulted in reduced global DNA methylation and hydroxymethylation in the liver of mice. E 171 exposure for 84 days elicited inflammation and damage in the mouse liver, whereas 28-day exposure did not. Whole-genome DNA methylation sequencing disclosed substantial methylation alterations at the CG and non-CG sites of the liver DNA in mice exposed to E 171 for 84 days. Mechanistic analysis of the DNA methylation alterations indicated that ferroptosis contributed to the liver toxicity induced by E 171. E 171-induced DNA methylation changes triggered NCOA4-mediated ferritinophagy, attenuated the protein levels of GPX4, FTH1, and FTL in the liver, and thereby caused ferroptosis. CONCLUSIONS: Long-term oral exposure to E 171 triggers hepatotoxicity and induces methylation changes in both CG and non-CG sites of liver DNA. These epigenetic alterations activate ferroptosis in the liver through NCOA4-mediated ferritinophagy, highlighting the role of DNA methylation and ferroptosis in the potential toxicity caused by E 171 in vivo.

Integrating machine learning with experimental investigation for optimizing photocatalytic degradation of Rhodamine B using neodymium-doped titanium dioxide: a comprehensive approach with toxicity assessment.

In this study, neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles were synthesized via a hydrothermal method for the photocatalytic degradation of Rhodamine B (RhB) under UV and sunlight conditions. The properties of these NPs were comprehensively characterized. And optimization of RhB degradation was conducted using control-variable experiment and artificial neural networks (ANN) under various operational conditions and in the presence of competing compounds. The acute toxicity of both NPs, RhB, and the environmental impact of the photocatalytic treatment effluent on Danio rerio were evaluated. The Nd modification increased the catalyst's specific surface area and thermal stability. X-ray diffraction confirmed the tetragonal anatase phase in undoped TiO2, while Nd-doped TiO2 exhibited shifts in peaks and the presence of brookite and rutile phases. Nd (1 mol%) doped TiO2 demonstrated superior RhB photocatalytic degradation efficiency, achieving 95% degradation and 82% total organic carbon (TOC) removal within 60 min under UV irradiation. Optimization under sunlight conditions yielded 95.14% RhB removal with 0.28 g/L photocatalyst and 1% doping. Under UV light, 98.12% RhB removal was optimized with 0.97% doping, along with the presence of humic acid and CaCl2. ANN modeling achieved high precision (R2 of 0.99) in modeling environmental photocatalysis. Toxicity assessments indicated that the 96-h LC50 values were 681.59 mg L-1 for both NPs, and 23.02 mg L-1 for RhB. The treated dye solution exhibited a significant decline in toxicity, emphasizing the potential of 1% Nd-TiO2 in wastewater treatment.

Differentially Induced Autophagy by Engineered Nanomaterial Treatment Has an Impact on Cellular Homeostasis and Cytotoxicity.

Considering the increasing production of engineered nanomaterials (ENMs), new approach methodologies (NAMs) are essential for safe-by-design approaches and risk assessment. Our aim was to enhance screening strategies with a focus on reactivity-triggered toxicities. We applied in vitro tests to 10 selected benchmark ENMs in two cell models, lung epithelial A549 and differentiated THP-1 macrophage-like cells. Previously, we categorized ENMs based on surface reactivity. Here we elucidated their reactivity-triggered cytotoxicity and mode of action using the WST-1 assay (metabolic activity), LDH assay (cell membrane integrity), autophagosome detection, and proteomics. Nonreactive SiO2 NM-200 showed no significant impact on cell viability. Conversely, highly reactive CuO and ZnO (NM-110 and NM-111) disrupted cell homeostasis. Interestingly, moderately reactive TiO2 (NM-101 and NM-105) and CeO2 (NM-211 and NM-212), apparently without an adverse effect, induced autophagosome formation, evidencing autophagy as a defensive mechanism. Our improved in vitro testing strategy, combined with state-of-the-art reactivity information, screens ENMs for potential reactivity-triggered toxicity.

[Establishment of Nano-ITO induced rat model of indium lung disease and exploration of its pathological characteristics].

Objective: To study the dynamic pathological characteristics of lung tissue in a Nano-ITO induced rat model of indium lung disease and to guide clinical and basic scientific research to further explore the mechanisms of pulmonary interstitial injury and pulmonary alveolar proteinosis (PAP). Methods: Dose-response (three divided doses) and time-course studies (six exposure periods) were performed to investigate the pulmonary toxicity induced by Nano-ITO. At the end of the experiment, cytokine levels and oxidative stress were analyzed in the bronchoalveolar lavage fluid. Rat lung tissues were also collected for staining with H&E, PAS, Masson's, Oil Red O, and Sirius Red. Ultrastructure of lung tissue cells was observed by transmission electron microscopy. Expression of IL-1ß, HO-1, SP-A was observed by immunohistochemistry, and the expression of α-SMA was observed by immunofluorescence. Results: Nano-ITO intratracheal instillation caused pulmonary toxicity by inducing acute inflammation at 3 days, granuloma (nodule) formation and collagen hyperplasia at 14 days, and alveolar proteinosis at 56 days post-exposure. Pathological features of lung tissue included typical alveolar exudates, cellular fibrous nodules, enlarged alveolar fat droplet fusion, cholesterol crystal granuloma and pulmonary alveolar proteinosis. The intra-alveolar eosinophilic material (multilamellated, lattice-shaped, and myelin-like structure) showed abnormal lamellar bodies (features of alveolar type Ⅱ epithelial cells) and abundant rough endoplasmic reticulum and mitochondria (features of fibroblasts) on transmission electron microscopy of the lung tissue from rats exposed to Nano-ITO on the 84th day. Cellular pathology revealed that a large amount of amorphous PAS stain-positive substances appear in BALF at 28 days post-exposure, and pink granular protein-like substances can be seen in alveolar macrophages. Conclusions: There are three characteristic developmental stages in Nano-ITO induced pulmonary injury in rats, acute inflammation, granuloma (nodule) formation and collagen proliferation, and pulmonary alveolar proteinosis, which provide a reference feature model for the pathogenesis of indium lung disease.

Repeated marine heatwaves aggravate the adverse effects of nano-TiO2 on physiological metabolism of the thick-shelled mussel Mytilus coruscus.

Global climate change is a major trigger of unexpected temperature fluctuations. The impacts of marine heatwaves (MHWs) and nano-titanium dioxide (nano-TiO2) on marine organisms have been extensively investigated. However, the potential mechanisms underlying their interactive effects on physiological processes and metabolism remain poorly understood, especially regarding periodic MHWs in real-world conditions. In this study, the effects of nano-TiO2 (at concentrations of 0, 25, and 250 µg/L) and periodic MHWs on the condition index (CI) and underlying metabolic mechanisms were investigated in mussels (Mytilus coruscus). The results showed that mussels try to upregulate their respiration rate (RR) to enhance aerobic metabolism (indicated by elevated succinate dehydrogenase) under short-term nano-TiO2 exposure. However, even at ambient concentration (25 µg/L), prolonged nano-TiO2 exposure inhibited ingestion ability (decreased clearance rate) and glycolysis (inhibited pyruvate kinase, hexokinase, and phosphofructokinase activities), which led to an insufficient energy supply (decreased triglyceride, albumin, and ATP contents). Repeated thermal scenarios caused more severe physiological damage, demonstrating that mussels are fragile to periodic MHWs. MHWs decreased the zeta potential of the nano-TiO2 particles but increased the hydrodynamic diameter. Additionally, exposure to nano-TiO2 and periodic MHWs further affected aerobic respiration (inhibited lactate dehydrogenase and succinate dehydrogenase activities), metabolism (decreased RR, activities of respiratory metabolism-related enzymes, and expressions of PEPCK, PPARγ, and ACO), and overall health condition (decreased ATP and CI). These findings indicate that the combined stress of these two stressors exerts more detrimental impact on the physiological performance and energy metabolism of mussels, and periodic MHWs exacerbate the toxicological effects of ambient concentration nano-TiO2. Given the potential worsening of nanoparticle pollution and the increase in extreme heat events in the future, the well-being of mussels in the marine environment may face further threats.

Co-doped titanium dioxide nanoparticles decrease the cytotoxicity of experimental hydrogen peroxide gels for in-office tooth bleaching.

OBJECTIVE: To evaluate the efficacy and cytotoxicity of experimental 6% and 35% hydrogen peroxide gels (HP6 or HP35) incorporated with titanium dioxide nanoparticles (NP) co-doped with nitrogen and fluorine and irradiated with a violet LED light (LT). METHODS: Bovine enamel-dentin disks adapted to artificial pulp chambers were randomly assigned to bleaching (n = 8/group): NC (negative control), NP, HP6, HP6 + LT, HP6 + NP, HP6 + NP + LT, HP35, HP35 + LT, HP35 + NP, HP35 + NP + LT, and commercial HP35 (COM). Color (ΔE00) and whiteness index (ΔWID) changes were measured before and 14 days after bleaching. The extracts (culture medium + diffused gel components) collected after the first session were applied to odontoblast-like MDPC-23 cells, which were assessed concerning their viability, oxidative stress, and morphology. The amount of HP diffused through the disks was determined. Data were analyzed by generalized linear models or Kruskal Wallis Tests (α = 5%).  RESULTS: HP6 + NP + LT exhibited ΔE00 and ΔWID higher than HP6 (p < 0.05) and similar to all HP35 groups. HP6 + NP + LT showed the lowest HP diffusion, and the highest cell viability (%) among bleached groups, preserving cell morphology and number of living cells similar to NC and NP. HP6 + LT, HP6 + NP, and HP6 + NP + LT exhibited the lowest cell oxidative stress among bleached groups (p < 0.05). HP35, HP35 + LT, and HP35 (COM) displayed the lowest cell viability. CONCLUSION: HP6 achieved significantly higher color and whiteness index changes when incorporated with nanoparticles and light-irradiated and caused lower cytotoxicity than HP35 gels. The nanoparticles significantly increased cell viability and reduced the hydrogen peroxide diffusion and oxidative stress, regardless of HP concentration. CLINICAL SIGNIFICANCE: Incorporation of co-doped titanium dioxide nanoparticles combined with violet irradiation within the HP6 gel could promote a higher perceivable and acceptable efficacy than HP6 alone, potentially reaching the optimal esthetic outcomes rendered by HP35. This approach also holds the promise of reducing cytotoxic damages and, consequently, tooth sensitivity.

Identifying resistance molecules in TiO2 nanoparticle-tolerant strains to facilitate the development of strategies for combating TiO2 nanoparticle pollution.

The severity of environmental pollution caused by TiO2 nanoparticles (nTiO2) is increasing, highlighting the urgent need for the development of strategies to combat nTiO2 pollution. Insights into resistance molecules from nTiO2-tolerant strains may facilitate such development. In this study, we utilized multi-omics, genetic manipulation, physiological and biochemical experiments to identify relevant resistance molecules in two strains (Physarum polycephalum Z259 and T83) tolerated to mixed-phase nTiO2 (MPnTiO2). We discovered that a competing endogenous RNA (ceRNA) network, comprising one long non-coding RNA (lncRNA), four microRNAs, and nine mRNAs, influenced metabolic rearrangement and was associated with significant resistance in these strains. Additionally, we found that the lncRNA in the ceRNAs network and certain small-weight metabolites associated with the ceRNA exhibited notable mitigation effects not only against MPnTiO2 but also against other types of nTiO2 with broad species applicability (they significantly improved the resistance of several non-nTiO2-tolerant cells/organisms in the laboratory and reduced cell damage of non-nTiO2-tolerant cells/organisms in highly suspected nTiO2-polluted areas of the real world). In summary, this study deepens our understanding of nTiO2-tolerant strains, provides valuable insights into resistance molecules in these strains, and facilitates the development of strategies to combat nTiO2 pollution.

The Effect of Green Tea Extract on Pulmonary Inflammation in Nanoparticles-Exposed Mice.

SCOPE: Titanium dioxide nanoparticles (TiO2 NPs) are air pollutants that exacerbate chronic respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD) However, little is known about the mechanism underlying the antipollutant effects of green tea extract (GTE). This study evaluates the efficacy and mechanism of GTE on lung inflammation and fibrosis in mice exposed to TiO2 NPs. METHODS AND RESULTS: The TiO2 NPs model is induced by having mice inhale TiO2 NPs, while controls receive an equivalent volume of saline. Treatment with oral GTE is initiated after TiO2 NPs inhalation and is given once daily for 4 weeks. Airway resistance and pulmonary inflammation are increased in mice exposed to TiO2 NPs. GTE treatment reduces the airway inflammation and airway resistance, and attenuates the pathological changes including lung fibrosis compared to the mice exposed to TiO2 NPs. With GTE, there are no significant increases in cytokines and immunoglobulin E (IgE) in mice exposed to TiO2 NPs. GTE inhibits matrix metalloproteinases (MMPs) and apoptotic factors induced by TiO2 NPs exposure, and these protective effects of GTE are closely related to the mitogen-activated protein kinase (MAPK) signaling pathway. CONCLUSION: GTE modulates pulmonary inflammation in mice exposed to air pollutants, suggesting that GTE may be beneficial in respiratory diseases exacerbated by such pollutants.

Single and combined effects of titanium (TiO2) and zinc (ZnO) oxide nanoparticles in the rainbow trout gill cell line RTgill-W1.

Understanding the environmental impact of nanoparticle (NP) mixtures is essential to accurately assess the risk they represent for aquatic ecosystems. However, although the toxicity of individual NPs has been extensively studied, information regarding the toxicity of combined NPs is still comparatively rather scarce. Hence, this research aimed to investigate the individual and combined toxicity mechanisms of two widely consumed nanoparticles, zinc oxide (ZnO NPs) and titanium dioxide (TiO2 NPs), using an in vitro model, the RTgill-W1 rainbow trout gill epithelial cell line. Sublethal concentrations of ZnO NPs (0.1 µg mL-1) and TiO2 (30 µg mL-1) and a lethal concentration of ZnO NPs causing 10% mortality (EC10, 3 µg mL-1) were selected based on cytotoxicity assays. Cells were then exposed to the NPs at the selected concentrations alone and to their combination. Cytotoxicity assays, oxidative stress markers, and targeted gene expression analyses were employed to assess the NP cellular toxicity mechanisms and their effects on the gill cells. The cytotoxicity of the mixture was identical to the one of ZnO NPs alone. Enzymatic and gene expression (nrf2, gpx, sod) analyses suggest that none of the tested conditions induced a strong redox imbalance. Metal detoxification mechanisms (mtb) and zinc transportation (znt1) were affected only in cells exposed to ZnO NPs, while tight junction proteins (zo1 and cldn1), and apoptosis protein p53 were overexpressed only in cells exposed to the mixture. Osmoregulation (Na + /K + ATPase gene expression) was not affected by the tested conditions. The overall results suggest that the toxic effects of ZnO and TiO2 NPs in the mixture were significantly enhanced and could result in the disruption of the gill epithelium integrity. This study provides new insights into the combined effects of commonly used nanoparticles, emphasizing the importance of further investigating how their toxicity may be influenced in mixtures.

Anti-pneumoconiosis effect of schisantherin A in PMA-induced A549 cells and SiO2/TiO2nanoparticles-induced acute pulmonary injury in mice.

There has been significant global interest in respiratory health driven by the coronavirus disease (COVID-19) and severe environmental pollution. This study explored the potential of schisantherin A (SchA), a compound derived from Schisandra chinensis, to protect against acute pneumoconiosis. We assessed the effects of SchA on phorbol 12-myristate 13-acetate (PMA)-stimulated A549 alveolar epithelial cells and SiO2/TiO2-induced pulmonary injury in mice. In A549 cells, SchA significantly decreased pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and interleukin (IL)-8 levels. SchA-mediated reduction in inflammatory mediators was associated with the downregulation of PMA-stimulated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling activation. In SiO2/TiO2-induced lung-injured mice, SchA administration significantly reduced MUC5AC production in lung tissue. SchA administration significantly downregulated the overexpression of NK-κB and the subsequent production of COX-2, iNOS, and NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes. It significantly suppressed expected increases in total cell numbers and pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and IL-1ß in the bronchoalveolar lavage fluid (BALF) in SiO2/TiO2-stimulated mice. In contrast, the SiO2/TiO2-mediated decrease in IL-10 levels was significantly improved by SchA treatment. These fundamental results can be used to develop potential treatments involving SchA for acute pneumoconiosis.

Combined effects of TiO2 nanoparticle and fipronil co-exposure on microbiota in mouse intestine.

Oral exposure to nanoparticles (NPs) may affect intestinal microbiota, and this effect may be further changed by co-contaminates. In the present study, we investigated the combined effects of TiO2 NPs and fipronil (FPN) on microbiota in mouse intestines. Mice were intragastric exposed to 5.74 mg/kg TiO2 NPs, 2.5 mg/kg FPN, or both of them, once a day, for 30 days. The results showed that individual exposure to TiO2 NPs or FPN decreased body weight and induced pathological changes in intestines. The exposure was also associated with increased cleaved caspase-3 protein, oxidative stress and decreased tight junction protein expression. Furthermore, the levels of diamine oxidase (DAO), lipopolysaccharide (LPS) and inflammatory cytokines in serum were also elevated, indicating increased intestinal barrier permeability. As expected, both TiO2 NPs and FPN decreased the diversity and altered the composition of microbiota. However, the observed effects were not further enhanced after the co-exposure to TiO2 NPs and FPN, except that Romboutsia was only significantly increased after the co-exposure to TiO2 NPs + FPN. We concluded that oral exposure to TiO2 NPs and FPN showed minimal synergistic effects on microbiota in mouse intestine.

Diving into the metabolic interactions of titanium dioxide nanoparticles in "Sparus aurata" and "Ruditapes philippinarum".

The biological response to nanomaterials exposure depends on their properties, route of exposure, or model organism. Titanium dioxide nanoparticles (TiO2 NPs) are among the most used nanomaterials; however, concerns related to oxidative stress and metabolic effects resulting from their ingestion are rising. Therefore, in the present work, we addressed the metabolic effects of citrate-coated 45 nm TiO2 NPs combining bioaccumulation, tissue ultrastructure, and proteomics approaches on gilthead seabream, Sparus aurata and Japanese carpet shell, Ruditapes philippinarum. Sparus aurata was exposed through artificially contaminated feeds, while R. philippinarum was exposed using TiO2 NPs-doped microalgae solutions. The accumulation of titanium and TiO2 NPs in fish liver is associated with alterations in hepatic tissue structure, and alteration to the expression of proteins related to lipid and fatty acid metabolism, lipid breakdown for energy, lipid transport, and homeostasis. While cellular structure alterations and the expression of proteins were less affected than in gilthead seabream, atypical gill cilia and microvilli and alterations in metabolic-related proteins were also observed in the bivalve. Overall, the effects of TiO2 NPs exposure through feeding appear to stem from various interactions with cells, involving alterations in key metabolic proteins, and changes in cell membranes, their structures, and organelles. The possible appearance of metabolic disorders and the environmental risks to aquatic organisms posed by TiO2 NPs deserve further study.

From screens to seas: Tech contaminants in tiger sharks.

The potential negative impacts of Technology-Critical Elements (TCEs) on the environment and wildlife, despite increasingly recognized, remain largely overlooked. In this sense, this study aimed to investigate the concentrations of several TCEs, including rubidium (Rb), titanium (Ti) and various Rare Earth Elements (REEs), in different tissues of tiger sharks. Sharks incidentally caught by artisanal fleets in southern Brazil were opportunistically sampled and liver, gills, kidneys, heart, muscle, eyes, brain, skin, and teeth were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Significant Rb concentration variations were observed across different tissues, with higher levels detected in kidneys and lower levels in the liver. Titanium concentrations also exhibited significant differences, with higher levels detected in teeth and lower levels in liver. Although no statistical differences were observed for the analyzed REEs, a trend of higher accumulation in the liver, gills, and skin was noted. Light Rare Earth Elements (LREEs) were found predominantly in all organs, with neodymium, lanthanum, and cerium as the most significant REEs detected. Several statistically significant correlations were identified between Rb and REEs, as well as between Ti and REEs, indicating systemic transport of these elements across different tissues. These findings indicate that the growing extraction and disposal of metallic elements, driven by technological advancements, may lead to their assimilation by marine fauna, particularly at higher trophic levels. The potential harmful effects on these organisms remain unknown and require urgent investigation. Additionally, as mining activities intensify globally, precise legislative measures are essential to address environmental concerns, species conservation, and human health considerations.

Nano-TiO2 regulates the MAPK (ERK, P38) pathway to promote apoptosis and inhibit proliferation of human colon cells.

BACKGROUND: Nano titanium dioxides (TiO2) are widely used in drug development, food additives and packaging materials. Although several studies have demonstrated the poisonousness of TiO2 in vivo and in vitro, the underlying molecular mechanisms have not been fully revealed. METHODS: Characterization of TiO2 by FTIR, XRD, TEM and DLS. The NCM460 cell line, representing normal colon epithelial cells, was utilized as a model to assess the impact of TiO2 nanoparticles (TiO2-NPs) on cell proliferation and apoptosis. The potential molecular mechanisms underlying its toxic effects were investigated through transcriptome analysis, RT-qPCR, and western blot experiments. RESULTS: The particle size of the TiO2-NPs used is about 25 nm, which has typical characteristics of anatase. TiO2-NPs at a concentration of 30-60 µg/mL will cause changes in colon cell morphology, decreased proliferation ability, and increased number of apoptotic cells. TiO2-NPs at a concentration of 6 µg/mL did not significantly modify the transcriptome expression profile of colon cells; while 30 µg/mL had a significant effect, leading to up-regulation of gene expression. The differentially expressed genes predominantly modulate the MAPK signaling pathway, TNF signaling pathway, cytokine-cytokine receptor interaction, and other related pathways. Further, western blot analysis revealed that higher concentrations of TiO2-NPs (30-60 µg/mL) could up-regulate the expression of P53, P21 and Bax, while down-regulating the expression of Bcl2 by regulating the MAPK (ERK, P38) signaling pathway. Simultaneously, it also promoted the decreased in Fos protein expression and inhibited the phosphorylation of Jun and Fos. CONCLUSION: This study demonstrates that TiO2-NPs may exert potential toxic effects on colon cells, and therefore the intake of TiO2-NPs should be strictly regulated in practical applications.

Effects of metal oxide nanoparticles on healthy and psoriasis-like human epidermal keratinocytes in vitro.

The use of metal oxide nanoparticles (NPs) in skincare products has significantly increased human skin exposure, raising safety concerns. Whilst NP's ability to penetrate healthy skin is minimal, studies have demonstrated that metal oxide NPs can induce toxicity in keratinocytes through direct contact. Moreover, NP's effect on common skin disorders like psoriasis, where barrier impairments and underlying inflammation could potentially increase NP penetration and worsen nanotoxicity is largely unstudied. In this paper, we investigated whether psoriasis-like human keratinocytes (Pso HKs) would exhibit heightened toxic responses to titanium dioxide (TiO2), zinc oxide (ZnO), and/or silica (SiO2) NPs compared to healthy HKs. Cells were exposed to each NP at concentrations ranging between 0.5 and 500 µg/ml for 6, 24, and 48 h. Amongst the metal oxide NPs, ZnO NPs produced the most pronounced toxic effects in both cell types, affecting cell viability, inducing oxidative stress, and activating the inflammasome pathway. Notably, only in ZnO NPs-treated Pso HKs, trappin-2/pre-elafin was cleaved intracellularly through a non-canonical process. In addition, tissue remodelling-related cytokines were upregulated in ZnO NP-treated Pso HKs. The full impact of the observed outcomes on psoriatic symptoms will need further evaluation. Nonetheless, our findings indicate the importance of understanding the sub-lethal impacts of NP exposures on keratinocytes, even though direct exposure may be low, particularly in the context of skin disorders where repeated and long-term exposures are anticipated.

Co-application of titanium dioxide and hydroxyapatite nanoparticles modulated chromium and salinity stress via modifying physio-biochemical attributes in Solidago canadensis L.

Climate change and human activity have led to an increase in salinity levels and the toxicity of chromium (Cr). One promising approach to modifying these stressors in plants is to use effective nanoparticles (NPs). While titanium dioxide nanoparticles (TiO2 NPs) and hydroxyapatite (HAP NPs) have been demonstrated to increase plant tolerance to abiotic stress by enhancing antioxidant capacity, lipid peroxidation, and secondary metabolites, it is unknown how these two compounds can work together in situations when salt and Cr toxicity are present. The objective of the current study was to determine the effects of foliar-applied TiO2 NPs (15 mg L-1) and HAP NPs (250 mg L-1) separately and in combination on growth, chlorophyll (Chl), water content, lipid peroxidation, antioxidant capacity, phenolic content, and essential oils (EOs) of Solidago canadensis L. under salinity (100 mM NaCl) and Cr toxicity (100 mg kg-1 soil). Salinity was more deleterious than Cr by decreasing plant weight, Chl a + b, relative water content (RWC), EO yield, and increasing malondialdehyde (MDA), electrolyte leakage (EL), superoxide dismutase (SOD) activity, and catalase (CAT) activity. The co-application of TiO2 and HAP NPs proved to be more successful. This was evidenced by the increased shoot weight (36%), root weight (29%), Chl a + b (23%), RWC (15%), total phenolic content (TPC, 34%), total flavonoid content (TFC, 28%), and EO yield (56%), but decreased MDA (21%), EL (11%), SOD (22%) and CAT activity (38%) in salt-exposed plants. The study demonstrated the effective strategy of co-applying these NPs to modify abiotic stress by enhancing phenolic compounds and EO yield as key results.

Systematic review of mechanistic evidence for TiO2 nanoparticle-induced lung carcinogenicity.

Nano-sized titanium dioxide particles (TiO2 NPs) are a high-production volume nanomaterial widely used in the paints, cosmetics, food and photovoltaics industry. However, the potential carcinogenic effects of TiO2 NPs in the lung are still unclear despite the vast number of in vitro and in vivo studies investigating TiO2 NPs. Here, we systematically reviewed the existing in vitro and in vivo mechanistic evidence of TiO2 NP lung carcinogenicity using the ten key characteristics of carcinogens for identifying and classifying carcinogens. A total of 346 studies qualified for the quality and reliability assessment, of which 206 were considered good quality. Using a weight-of-evidence approach, these studies provided mainly moderate to high confidence for the biological endpoints regarding genotoxicity, oxidative stress and chronic inflammation. A limited number of studies investigated other endpoints important to carcinogenesis, relating to proliferation and transformation, epigenetic alterations and receptor-mediated effects. In summary, TiO2 NPs might possess the ability to induce chronic inflammation and oxidative stress, but it was challenging to compare the findings in the studies due to the wide variety of TiO2 NPs differing in their physicochemical characteristics, formulation, exposure scenarios/test systems, and experimental protocols. Given the limited number of high-quality and high-reliability studies identified within this review, there is a lack of good enough mechanistic evidence for TiO2 NP lung carcinogenicity. Future toxicology/carcinogenicity research must consider including positive controls, endotoxin testing (where necessary), statistical power analysis, and relevant biological endpoints, to improve the study quality and provide reliable data for evaluating TiO2 NP-induced lung carcinogenicity.

Toxicity of inorganic nanoparticles and commercial sunscreens on marine bacteria.

The Balearic Islands, a top tourist destination for sunny beaches, face physical and chemical pressures from human activities, impacting keystone species like the endemic seagrass Posidonia oceanica and its associated microbiome. This study evaluated the effects of ZnO and TiO2 nanoparticles and three commercial sunscreens with varying protection factors (50 or 90) and chemical complexities (1- SPF50_E "eco-friendly"; 2- SPF50 not "eco-friendly"; 3- SPF90 not "eco-friendly") on five heterotrophic bacteria (Pseudomonas azotifigens, Marinobacterium litorale, Thiothrix nivea, Sedimenticola thiotaurini and Cobetia sp) and two autotrophic cyanobacteria (Halothece sp. and Fischerella muscicola) associated to P. oceanica, as well as a natural leaf epiphytic community. Results indicated that TiO2 affected all heterotrophic bacteria, while ZnO was toxic to only two species, while autotrophs were unaffected. Commercial sunscreens impacted three heterotrophs and the natural epiphytic community, while autotrophs were only affected by SPF50. SPF50_E reduced phosphorus uptake, and both SPF50 and SPF90 decreased alkaline phosphatase activity. Reactive oxygen species production was mainly induced by SPF90, followed by SPF50_E and SPF50. Generally, the smallest bacteria were most sensitive to UV-filters (UVFs). This study indicates that UVFs exposure may alter the epiphytic community structure of P. oceanica.

Effect of Butyrate on Food-Grade Titanium Dioxide Toxicity in Different Intestinal In Vitro Models.

Short-chain fatty acids (SCFA) are an important energy source for colonocytes and crucial messenger molecules both locally in the intestine and systemically. Butyrate, one of the most prominent and best-studied SCFA, was demonstrated to exert anti-inflammatory effects, improve barrier integrity, enhance mucus synthesis in the intestine, and promote cell differentiation of intestinal epithelial cells in vitro. While the physiological relevance is undisputed, it remains unclear if and to what extent butyrate can influence the effects of xenobiotics, such as food-grade titanium dioxide (E171, fgTiO2), in the intestine. TiO2 has been controversially discussed for its DNA-damaging potential and banned as a food additive within the European Union (EU) since 2022. First, we used enterocyte Caco-2 monocultures to test if butyrate affects the cytotoxicity and inflammatory potential of fgTiO2 in a pristine state or following pretreatment under simulated gastric and intestinal pH conditions. We then investigated pretreated fgTiO2 in intestinal triple cultures of Caco-2, HT29-MTX-E12, and THP-1 cells in homeostatic and inflamed-like state for cytotoxicity, barrier integrity, cytokine release as well as gene expression of mucins, oxidative stress markers, and DNA repair. In Caco-2 monocultures, butyrate had an ambivalent role: pretreated but not pristine fgTiO2 induced cytotoxicity in Caco-2 cells, which was not observed in the presence of butyrate. Conversely, fgTiO2 induced the release of interleukin 8 in the presence but not in the absence of butyrate. In the advanced in vitro models, butyrate did not affect the characteristics of the healthy or inflamed states and caused negligible effects in the investigated end points following fgTiO2 exposure. Taken together, the effects of fgTiO2 strongly depend on the applied testing approach. Our findings underline the importance of the experimental setup, including the choice of in vitro model and the physiological relevance of the exposure scenario, for the hazard testing of food-grade pigments like TiO2.