Maternal exposure to titanium dioxide nanoparticles during pregnancy; impaired memory and decreased hippocampal cell proliferation in rat offspring

Titanium dioxide nanoparticles (TiO₂-NPs) are massively produced in the environment, and because of their wide usage, they are a potential risk of damage to human health. TiO₂-NPs are often used as additives for paints, papers, and foods. The central nervous system (CNS), including hippocampal regions, is potentially susceptible targets for TiO₂-NPs. This study aimed to determine the effects of exposure to TiO₂-NPs during pregnancy on hippocampal cell proliferation and the learning and memory of offspring. Pregnant Wistar rats received intragastric TiO₂-NPs (100 mg/kg body weight) daily from gestational day (GD) 2 to (GD) 21. Animals in the control group received the same volume of distilled water via gavage. After delivery, the one-day-old neonates were deeply anesthetized and weighed. They were then killed and the brains of each group were collected. Sections of the brains from the rat offspring were stained using Ki-67 immunolabeling and the immunohistochemistry technique. Some of the male offspring (n = 12 for each group) were weaned at postnatal day (PND21), and housed until adulthood (PND60). Then the learning and memory in animals of each group were evaluated using passive avoidance and Morris water maze tests. The immunolabeling of Ki-67 protein as a proliferating cell marker showed that TiO₂-NPs significantly reduced cell proliferation in the hippocampus of the offspring (P < 0.05). Moreover, both the Morris water maze test and the passive avoidance test showed that exposure to TiO₂-NPs significantly impaired learning and memory in offspring (P < 0.05). These results may provide basic experimental evidence for a better understanding of the neurotoxic effects of TiO₂-NPs on neonatal and adult brains.     

Susceptible genes regulate the adverse effects of TiO2-NPs at predicted environmental relevant concentrations on nematode Caenorhabditis elegans

Contributions from mutations of susceptible genes to TiO₂-NPs toxicity at environmental relevant concentrations (ERCs) and the underlying mechanism are largely unclear. After prolonged exposure, among the examined 19 mutants associated with oxidative stress or stress response, we show that sod-2, sod-3, mtl-2, and hsp-16.48 were susceptible genes for TiO₂-NPs toxicity on reproduction and locomotion behavior, sod-2, sod-3, and mtl-2 were susceptible genes for TiO₂-NPs toxicity on survival and intestinal development, and mtl-2 was susceptible gene for TiO₂-NPs toxicity on development. Mutations of these susceptible genes, together with sensitive endpoints, could be used to evaluate TiO₂-NPs toxicity at the concentration of 0.0001 μg/L. Our results imply the usefulness of identified susceptible genes in assessing the potential nanotoxicity of engineered nanomaterial (ENM) at ERCs. One important mechanism to explain property of identified susceptible genes for TiO₂-NPs toxicity was that mutations of these susceptible genes enhanced the uptake of TiO₂-NPs into body of nematodes.From the Clinical EditorThis team of authors identified susceptibility genes influencing the uptake and consequential toxicity of TiO₂ nanoparticles in a nematode, highlighting the general importance of investigating genetic influence on nanoparticle delivery.     

TiO2 nanoparticles induce endothelial cell activation in a pneumocyte–endothelial co-culture model

The effects of particulate matter (PM) on endothelial cells have been evaluated in vitro by exposing isolated endothelial cells to different types of PM. Although some of the findings from these experiments have been corroborated by in vivo studies, an in vitro model that assesses the interaction among different cell types is necessary to achieve more realistic assays. We developed an in vitro model that mimics the alveolar–capillary interface, and we challenged the model using TiO₂ nanoparticles (TiO₂-NPs). Human umbilical endothelial cells (HUVECs) were cultured on the basolateral side of a membrane and pneumocytes (A549) on the apical side. Confluent co-cultures were exposed on the apical side to 10 μg/cm² of TiO₂-NPs or 10 ng/mL of TNFα for 24 h. Unexposed cultures were used as negative controls. We evaluated monocyte adhesion to HUVECs, adhesion molecule expression, nitric oxide concentration and proinflammatory cytokine release. The TiO₂-NPs added to the pneumocytes induced a 3- to 4-fold increase in monocyte adhesion to the HUVECs and significant increases in the expression of adhesion molecules (4-fold for P-selectin at 8 h, and about 8- and 10-fold for E-selectin, ICAM-1, VCAM-1 and PECAM-1 at 24 h). Nitric oxide production also increased significantly (2-fold). These results indicate that exposing pneumocytes to TiO₂-NPs causes endothelial cell activation.     

Close association of intestinal autofluorescence with the formation of severe oxidative damage in intestine of nematodes chronically exposed to Al(2)O(3)-nanoparticle

In nematodes, acute exposure (24-h) to 8.1–30.6 mg/L Al₂O₃-nanoparticles (NPs) or Al₂O₃ did not influence intestinal autofluorescence, whereas chronic exposure (10-d) to Al₂O₃-NPs at concentrations of 8.1–30.6 mg/L or Al₂O₃ at concentrations of 23.1–30.6 mg/L induced significant increases of intestinal lipofuscin accumulation, and formation of severe stress response and oxidative damage in intestines. Moreover, significant differences of intestinal autofluorescence, stress response and oxidative damage in intestines of Al₂O₃-NPs exposed nematodes from those in Al₂O₃ exposed nematodes were detected at examined concentrations. Oxidative damage in intestine was significantly correlated with intestinal autofluorescence in exposed nematodes, and oxidative damage in intestine was more closely associated with intestinal autofluorescence in nematodes exposed to Al₂O₃-NPs than exposed to Al₂O₃. Thus, chronic exposure to Al₂O₃-NPs may cause adverse effects on intestinal lipofuscin accumulation by inducing the formation of more severe oxidative stress in intestines than exposure to Al₂O₃ in nematodes.     

Effects of Th1 and Th2 cells balance in pulmonary injury induced by nano titanium dioxide

To explore the potential immunoregulatory mechanisms linking nano TiO₂ and pulmonary injury, Sprague Dawley rats were exposed by intra-tracheal instillation to nano TiO₂ with the individual doses of 0.5, 4.0 and 32 mg/kg b.w., micro TiO₂ with 32 mg/kg b.w. and 0.9% NaCl, respectively. The exposure was conducted twice a week, for four consecutive weeks. The results of lung histology demonstrated increased macrophages accumulation, extensive disruption of alveolar septa, slight alveolar thickness and expansion hyperemia. Mitochondria tumefaction organelles dissolution, endoplasmic reticulum expansion and the gap of nuclear broadening were shown. The changes of IFN-γ and IL-4 level showed no statistical difference. The mRNA expression of GATA-3 was up-regulated, whereas T-bet was significantly down-regulated. The protein expression of T-bet decreased and there were significant differences in nano 4 and 32 mg/kg groups. The imbalance of Th1/Th2 cytokines might be one of the mechanisms of immunotoxicity of respiratory system induced by nano TiO₂ particles.     

Silver and fullerene nanoparticles’ effect on interleukin-2-dependent proliferation of CD4 (+) T cells

Immunotoxicity studies of nanoparticles on T cells addressed their effects on activation by T antigen receptor, but have neglected the regulation of proliferation by IL-2. In this study, the IL-2-dependent T lymphoblastoid WE17/10 cell line was used to compare silver (Ag-NPs) and fullerene (C₆₀-NPs) nanoparticles’ toxicity and evaluate whether these NPs could interfere with IL-2-dependent proliferation. Results have shown that Ag-NPs are more toxic, as they reduced cell viability at the highest concentration tested (100 μg/ml), while C₆₀-NPs have shown good biocompatibility. Characterization of NP suspensions by dynamic light scattering measured large aggregates for C₆₀-NPs, whereas Ag-NPs were relatively stable and well dispersed. This translated into a much larger uptake of Ag-NPs compared to C₆₀-NPs, as measured by flow cytometry. Proliferation measurements by CFSE following 72 h incubation have shown that Ag-NPs decrease cell proliferation and C₆₀-NPs slightly increase proliferation. CD25 expression was unchanged following exposure to C₆₀-NPs, but was significantly increased by Ag-NPs’ presence for short and long-term incubations. Analyses of three key signaling proteins activated by IL-2 receptor (Stat5, JNK and ERK1/2) by western immunoblotting have shown no effects from either NPs on Stat5 and JNK phosphorylation. ERK1/2 was slightly activated following a short exposure to Ag-NPs, while C₆₀-NPs had no effect. Our results show that C₆₀-NPs have good biocompatibility and do not interfere with IL-2-dependent proliferation. A deeper investigation would be needed for the case of Ag-NPs, since the mechanism of their action is still unclear.     

Influence of silver and titanium dioxide nanoparticles on in vitro blood-brain barrier permeability

An in vitro blood-brain barrier (BBB) model being composed of co-culture with endothelial (bEnd.3) and astrocyte-like (ALT) cells was established to evaluate the toxicity and permeability of Ag nanoparticles (AgNPs; 8 nm) and TiO₂ nanoparticles (TiO₂NPs; 6 nm and 35 nm) in normal and inflammatory central nervous system. Lipopolysaccharide (LPS) was pre-treated to simulate the inflammatory responses. Both AgNPs and Ag ions can decrease transendothelial electrical resistance (TEER) value, and cause discontinuous tight junction proteins (claudin-5 and zonula occludens-1) of BBB. However, only the Ag ions induced inflammatory cytokines to release, and had less cell-to-cell permeability than AgNPs, which indicated that the toxicity of AgNPs was distinct from Ag ions. LPS itself disrupted BBB, while co-treatment with AgNPs and LPS dramatically enhanced the disruption and permeability coefficient. On the other hand, TiO₂NPs exposure increased BBB penetration by size, and disrupted tight junction proteins without size dependence, and many of TiO₂NPs accumulated in the endothelial cells were observed. This study provided the new insight of toxic potency of AgNPs and TiO₂NPs in BBB.     

Continuous in vitro exposure of intestinal epithelial cells to E171 food additive causes oxidative stress,inducing oxidation of DNA bases but no endoplasmic reticulum stress

The whitening and opacifying properties of titanium dioxide (TiO₂) are commonly exploited when it is used as a food additive (E171). However, the safety of this additive can be questioned as TiO₂ nanoparticles (TiO₂-NPs) have been classed at potentially toxic. This study aimed to shed some light on the mechanisms behind the potential toxicity of E171 on epithelial intestinal cells, using two in vitro models: (i) a monoculture of differentiated Caco-2 cells and (ii) a coculture of Caco-2 with HT29-MTX mucus-secreting cells. Cells were exposed to E171 and two different types of TiO₂-NPs, either acutely (6–48?h) or repeatedly (three times a week for 3 weeks). Our results confirm that E171 damaged these cells, and that the main mechanism of toxicity was oxidation effects. Responses of the two models to E171 were similar, with a moderate, but significant, accumulation of reactive oxygen species, and concomitant downregulation of the expression of the antioxidant enzymes catalase, superoxide dismutase and glutathione reductase. Oxidative damage to DNA was detected in exposed cells, proving that E171 effectively induces oxidative stress; however, no endoplasmic reticulum stress was detected. E171 effects were less intense after acute exposure compared to repeated exposure, which correlated with higher Ti accumulation. The effects were also more intense in cells exposed to E171 than in cells exposed to TiO₂-NPs. Taken together, these data show that E171 induces only moderate toxicity in epithelial intestinal cells, via oxidation.     

Aluminum nanoparticle exposure in L1 larvae results in more severe lethality toxicity than in L4 larvae or young adults by strengthening the formation of stress response and intestinal lipofuscin accumulation in nematodes

Toxicity of Al(2)O(3)-NPs, as compared to that of Al(2)O(3), to L1-larval, L4-larval or young adult nematodes was evaluated. When exposure was performed at L1-larval stage, the significant increases of lethality, stress response, and intestinal lipofuscin autofluorescence were observed in 6.3-203.9 mg/L of Al(2)O(3)-NPs exposed nematodes. In contrast, when exposure was performed at L4-larval or young adult stage, the significant increases of lethality and intestinal lipofuscin autofluorescence were observed in 12.7-203.9 mg/L of Al(2)O(3)-NPs exposed nematodes, and the significant inductions of stress response were detected in 25.5-203.9 mg/L of Al(2)O(3)-NPs exposed nematodes. Moreover, the lethality was significantly correlated with the stress response and the intestinal lipofuscin autofluorescence in Al(2)O(3)-NPs exposed nematodes. These data imply that Al(2)O(3)-NPs exposure in L1 larvae causes more severe lethality toxicity than in L4 larvae or young adults by strengthening the formation of stress response and intestinal lipofuscin accumulation in nematodes.     

Involvement of JNK and P53 activation in G2/M cell cycle arrest and apoptosis induced by titanium dioxide nanoparticles in neuron cells

Despite that applications of titanium dioxide nanoparticles (TiO₂-NPs) have been developed in the fields of paints, waste water treatment, sterilization, cosmetics, food additive, bio-medical ceramic and implant biomaterials and so on, relatively few studies have been conducted to determine the neurotoxicity of TiO₂-NPs exposure. In the present study, we investigated the cytotoxicity of TiO₂-NPs using PC12 cells and intended to clarify the molecular mechanisms underlying the biological effects of TiO₂-NPs. PC12 cell is a type of cells, which have been used as an in vitro model of dopaminergic neurons for neurodegenerative diseases research. In addition, the roles of the particle size and crystal structure of TiO₂-NPs to the neurotoxicity were also investigated. The anatase TiO₂-NPs displayed a dose-dependent behavior on decreasing cell viability, increasing levels of lactate dehydrogenase (LDH), activating oxidative stress, inducing apoptosis, disturbing cell cycle, triggering JNK- and p53-mediated signaling pathway. In comparison to anatase TiO₂-NPs, the rutile TiO₂-NPs showed moderately toxic effect on neuron cells. The micron-sized TiO₂ did not exhibit any toxic response. It is suggested from our results that reactive oxygen species (ROS) have a mediation effect to oxidative stress and up-regulation of JNK and P53 phosphorylation involved in mechanistic pathways of TiO₂-NPs can induce apoptosis and cell cycle arrest in PC12 cells. In addition, both the size and crystal structure of TiO₂-NPs exposure contributed to the neurotoxicity. Nanoparticles were more toxic than micrometer-sized particles and the anatase form were more toxic than the rutile.     

Transmissions of serotonin,dopamine, and glutamate are required for the formation of neurotoxicity from Al2O3-NPs in nematode Caenorhabditis elegans

Abstract

In this study, we investigated genetic mechanisms of neurotransmitters in regulating the formation of adverse effects on locomotion behavior in Al₂O₃ nanoparticles (NPs)-exposed Caenorhabditis elegans. Al₂O₃-NPs exposure caused the decrease of locomotion behavior with head thrash and body bend as endpoints. Interestingly, the neurotransmitters of glutamate, serotonin, and dopamine were required for the adverse effects of Al₂O₃-NPs on locomotion behavior in nematodes. Glutamate transporter EAT-4, serotonin transporter MOD-5, and dopamine transporter DAT-1 might serve as the molecular targets of Al₂O₃-NPs for neurotoxicity formation. Moreover, the behavioral response of nematodes to Al₂O₃-NPs exposure was primarily mediated by non-NMDA glutamate receptors GLR-2 and GLR-6, ionotropic serotonin receptor MOD-1, and D1-like dopamine receptor DOP-1. Therefore, Al₂O₃-NPs exposure influences locomotion behavior of nematodes primarily by impinging on their glutamatergic, serotoninergic, and dopaminergic systems. Our data will shed light on questions surrounding the involvement of neurotransmitters in mediating the adverse behavioral effects from Al₂O₃-NPs.     

Activation of human neutrophils by titanium dioxide (TiO2) nanoparticles

This paper describes the in vitro effects of titanium dioxide (TiO₂) nanoparticles (NPs) upon human neutrophils. Kinetic experiments revealed no cell necrosis after 24 h of treatment with TiO₂ (0–100 μg/ml). In contrast, TiO₂-induced change in cellular morphology in a concentration-dependent manner in neutrophils over time, indicating its potential to activate these cells. To further support this, we demonstrated that TiO₂ markedly and rapidly induced tyrosine phosphorylation events, including phosphorylation of two key enzymes, p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases-1/2 (Erk-1/2). We also determined the effects of TiO₂ on two neutrophil functions requiring a longer exposure period between NPs and cells: apoptosis and cytokine production. Interestingly, at concentrations ⩾20 μg/ml, TiO₂ inhibited neutrophil apoptosis in a concentration-dependent manner after 24 h of treatment. Supernatants from TiO₂-induced neutrophils were harvested after 24 h and tested for the presence of 36 different analytes (cytokines, chemokines) using an antibody array assay. TiO₂ treatment increased production of 13 (36%) analytes, including IL-8, which exhibited the greatest increase (∼16 × control cell levels). The increased production of IL-8 was confirmed by ELISA. We conclude that TiO₂ exerts important neutrophil agonistic properties in vitro.     

Toxicity assessment of anatase and rutile titanium dioxide nanoparticles: The role of degradation in different pH conditions and light exposure

Titanium dioxide nanoparticles (TiO₂NPs), in the two crystalline forms, rutile and anatase, have been widely used in many industrial fields, especially in cosmetics. Therefore, a lot of details about their safety issues have been discussed by the scientific community. Many studies have led to a general agreement about TiO₂NPs toxicity, in particular for anatase form, but no mechanism details have been proved yet. In this study, data confirm the different toxic potential of rutile and anatase TiO₂NPs in two cell lines up to 5 nM nanoparticles concentration. Moreover, we evaluated the role of titanium ions released by TiO₂NPs in different conditions, at pH = 4.5 (the typical lysosomal compartment pH) and at pH = 5.5 (the skin physiological pH) in conditions of darkness and light, to mimic the dermal exposure of cosmetics. Anatase nanoparticles were proner to degradation both in the acidic conditions and at skin pH. Our study demonstrates that pH and sunlight are dominant factors to induce oxidative stress, TiO₂NPs degradation and toxicity effects.     

Effects of un-ionized ammonia on histological,endocrine, and whole organism endpoints in slimy sculpin (Cottus cognatus)

Ammonia is known to be an important toxicant in aquatic environments. Although ammonia toxicity has been well studied in many fish species, effects of chronic exposure on slimy sculpin (Cottus cognatus), a critical biomonitoring species for northern aquatic habitats, are not well known. Further, with increasing mining development in Canada's north, this information is critical to better predict potential effects of mine effluent discharges on northern fish species. Slimy sculpin were exposed to six concentrations of un-ionized ammonia (NH₃) relevant to concentrations found in northern mining effluents: control (0 ppm), 0.278 ppm, 0.556 ppm, 0.834 ppm, 1.112 ppm, and 1.668 ppm. An LC₅₀ of 1.529 ppm was calculated from mortality data. Histopathological examination of gills indicated significant tissue damage, measured as lamellar fusion and epithelial lifting, at 0.834 ppm, 1.112 ppm, and 1.668 ppm. Using gill endpoints, NOEC and LOEC were calculated as 0.556 ppm and 0.834 ppm, respectively. An EC₅₀ of 0.775 ppm was determined for lamellar fusion and an EC₅₀ of 0.842 ppm for epithelial lifting. Hemorrhage of gills was present in mortalities, which occurred at 1.668 ppm of un-ionized ammonia. A significant decrease in liver somatic index (LSI) was seen in both male and female fish at 0.834 ppm and 1.112 ppm, respectively. Gonadosomatic index (GSI) in female fish significantly increased at 1.668 ppm un-ionized ammonia with an associated significant increase in total wholebody testosterone concentrations. GSI in male fish also significantly increased at 1.668 ppm but no differences were seen in testosterone concentrations. No significant differences were seen in gonad histopathological assessments or condition factor. Gill histopathology endpoints may be a more sensitive indicator for detecting effects in slimy sculpin exposed to ammonia than traditional chronic endpoints. Results from this study indicate that ammonia concentrations commonly reported in northern mine effluents hold potential to affect the health of slimy sculpin including acute, chronic, histological and endocrine endpoints.     

Acute respiratory and systemic toxicity of pulmonary exposure to rutile Fe-doped TiO(2) nanorods

Nanomaterials are extensively used in medicines, industry and daily life, but little is known about their possible health effects. Titanium dioxide (TiO₂) nonmaterial-based photocatalysis is useful in the complete mineralization of organic pollutants in waste water and air. While the Fe-doping of TiO₂ enhances their photocatalytic activity, their potential pathophysiologic effects are unknown. Here, rutile Fe-doped (9%) pure titanium dioxide (TiO₂) nanorods were prepared and characterized. Subsequently, we assessed the acute (24 h) pulmonary and extrapulmonary effects of intratracheal (i.t.) instillation of these nanorods (1 and 5 mg/kg) in Wistar rats. In the bronchoalveolar lavage, the treatment induced a significant and dose-dependent increase of neutrophils, an increase of interleukin-6 (IL-6, at 5 mg/kg), and caused a dose-dependent-decrease of superoxide dismutase (SOD) activity. The lung sections of rats exposed to rutile Fe–TiO₂ nanorods showed infiltration of inflammatory cells in dose-dependent manner. Similarly, the heart rate, systolic blood pressure, plasma IL-6, and leukocyte and platelet numbers were increased at 5 mg/kg. The plasma SOD and reduced glutathaione activities were dose-dependently decreased after exposure to the nanorods. Histopathologically, the liver showed mild inflammatory cells infiltration of few portal tracts, but the kidneys and heart were unaffected. In plasma, the levels of lactate dehydrogenase and hepatic enzymes, i.e., alanine aminotranferease and aspartate aminotransferase were increased significantly. The in vitro exposure of human lung cancer cells NCI-H460-Luc2 and human hepatoma cells HepG2 to FeTiO₂ (6.25–100 μg/ml) dose-dependently reduced cellular viability. Also, the In vitro direct addition of these nanorods (0.1–1 μg/ml) to untreated rat blood, significantly and dose-dependently induced platelet aggregation. In conclusion, exposure to rutile Fe–TiO₂ promotes pulmonary and systemic inflammation and oxidative stress. It affects the liver, enhances thrombotic potential, heart rate and systolic blood pressure. Moreover, the rutile Fe–TiO₂ elicited direct toxicity on NCI-H460-Luc2 and HepG2 cells.     

Proteomic analyses of early response of unicellular eukaryotic microorganism Tetrahymena thermophila exposed to TiO2 particles

Key biological functions involved in cell survival have been studied to understand the difference between the impact of exposure to TiO₂ nanoparticles (TiO₂-NPs) and their bulk counterparts (bulk-TiO₂). By selecting a unicellular eukaryotic model organism and applying proteomic analysis an overview of the possible impact of exposure could be obtained. In this study, we investigated the early response of unicellular eukaryotic protozoan Tetrahymena thermophila exposed to TiO₂-NPs or bulk-TiO₂ particles at subtoxic concentrations for this organism. The proteomic analysis based on 2DE?+?nLC-ESI-MS/MS revealed 930 distinct protein spots, among which 77 were differentially expressed and 18 were unambiguously identified. We identified alterations in metabolic pathways, including lipid and fatty acid metabolism, purine metabolism and energetic metabolism, as well as salt stress and protein degradation. This proteomic study is consistent with our previous findings, where the early response of T. thermophila to subtoxic concentrations of TiO₂ particles included alterations in lipid and fatty acid metabolism and ion regulation. The response to the lowest TiO₂-NPs concentration differed significantly from the response to higher TiO₂-NPs concentration and both bulk-TiO₂ concentrations. Alterations on the physiological landscape were significant after exposure to both nano- and bulk-TiO₂; however, no toxic effects were evidenced even at very high exposure concentrations. This study confirms the relevance of the alteration of the lipid profile and lipid metabolism in understanding the early impact of TiO₂-NPs in eukaryotic cells, for example, phagocytosing cells like macrophages and ciliated cells in the respiratory epithelium.     

Silver and fullerene nanoparticles’ effect on interleukin-2-dependent proliferation of CD4 (+) T cells

Immunotoxicity studies of nanoparticles on T cells addressed their effects on activation by T antigen receptor, but have neglected the regulation of proliferation by IL-2. In this study, the IL-2-dependent T lymphoblastoid WE17/10 cell line was used to compare silver (Ag-NPs) and fullerene (C₆₀-NPs) nanoparticles’ toxicity and evaluate whether these NPs could interfere with IL-2-dependent proliferation. Results have shown that Ag-NPs are more toxic, as they reduced cell viability at the highest concentration tested (100 μg/ml), while C₆₀-NPs have shown good biocompatibility. Characterization of NP suspensions by dynamic light scattering measured large aggregates for C₆₀-NPs, whereas Ag-NPs were relatively stable and well dispersed. This translated into a much larger uptake of Ag-NPs compared to C₆₀-NPs, as measured by flow cytometry. Proliferation measurements by CFSE following 72 h incubation have shown that Ag-NPs decrease cell proliferation and C₆₀-NPs slightly increase proliferation. CD25 expression was unchanged following exposure to C₆₀-NPs, but was significantly increased by Ag-NPs’ presence for short and long-term incubations. Analyses of three key signaling proteins activated by IL-2 receptor (Stat5, JNK and ERK1/2) by western immunoblotting have shown no effects from either NPs on Stat5 and JNK phosphorylation. ERK1/2 was slightly activated following a short exposure to Ag-NPs, while C₆₀-NPs had no effect. Our results show that C₆₀-NPs have good biocompatibility and do not interfere with IL-2-dependent proliferation. A deeper investigation would be needed for the case of Ag-NPs, since the mechanism of their action is still unclear.     

Exposure and recovery response of isomers of HCH,metabolites of DDT and estradiol-17β in the female catfish,Heteropneustes fossilis

Effects of 40 days of exposure and 20 days of recovery response at sublethal concentration of technical grades of gamma isomer of hexachlorocyclohexane (γ-HCH, 0.025 ppm, 99.8%) and dichlorodiphenyltrichloroethane (DDT, 5.0 ppm) in tissue (liver, brain and ovary) bioconcentrations, gonadosomatic index (GSI) and plasma levels of estradiol-17β (E2) have been estimated during prespawning phase in the catfish Heteropneustes fossilis (Bloch). The results indicated that the tissue bioconcentrations of both HCHs (HCH isomers) and DDTs (metabolites of DDT) in liver, brain and ovary were in preferential order (liver > brain > ovary). The GSI and plasma levels of E2 were declined in response to exposure of γ-HCH and DDT. On withdrawal of exposure of pesticide there was recovery of HCHs in exposed fish for all tissues studied, whereas DDTs exposed fish showed recovery only in liver. Recovery of E2 production was also recorded in γ-HCH exposed fish whereas very little recorded in DDT exposed fish. It is suggested that HCHs and DDTs have preferential order (liver > brain > ovary) of their tissue bioconcentrations and HCH/DDT-withdrawal-dependent recovery during studied phase.     

Titanium dioxide nanoparticles induced intracellular calcium homeostasis modification in primary human keratinocytes. Towards an in vitro explanation of titanium dioxide nanoparticles toxicity

Abstract

Deciphering the molecular basis of toxicology mechanism induced by nanoparticles (NPs) remains an essential challenge. Ion Beam Analysis (IBA) was applied in combination with Transmission Electron Microscopy and Confocal Microscopy to analyze human keratinocytes exposed to TiO₂-NPs. Investigating chemical elemental distributions using IBA gives rise to a fine quantification of the TiO₂-NPs uptake within a cell and to the determination of the intracellular chemical modifications after TiO₂-NPs internalization. In addition, fluorescent dye-modified TiO₂-NPs have been synthesized to allow their detection, precise quantification and tracking in vitro. The internalization of these TiO₂-NPs altered the calcium homeostasis and induced a decrease in cell proliferation associated with an early keratinocyte differentiation, without any indication of cell death. Additionally, the relation between the surface chemistry of the TiO₂-NPs and their in vitro toxicity is clearly established and emphasizes the importance of the calcium homeostasis alteration in response to the presence of TiO₂-NPs.