Prenatal exposure to TiO2 nanoparticles in mice causes behavioral deficits with relevance to autism spectrum disorder and beyond.
ABSTRACT: Environmental factors are involved in the etiology of autism spectrum disorder (ASD) and may contribute to the raise in its incidence rate. It is currently unknown whether the increasing use of nanoparticles such as titanium dioxide (TiO2 NPs) in consumer products and biomedical applications may play a role in these associations. While nano-sized TiO2 is generally regarded as safe and non-toxic, excessive exposure to TiO2 NPs may be associated with negative health consequences especially when occurring during sensitive developmental periods. To test if prenatal exposure to TiO2 NPs alters fetal development and behavioral functions relevant to ASD, C57Bl6/N dams were subjected to a single intravenous injection of a low (100?µg) or high (1000?µg) dose of TiO2 NPs or vehicle solution on gestation day 9. ASD-related behavioral functions were assessed in the offspring using paradigms that index murine versions of ASD symptoms. Maternal exposure to TiO2 NPs led to subtle and dose-dependent impairments in neonatal vocal communication and juvenile sociability, as well as a dose-dependent increase in prepulse inhibition of the acoustic startle reflex of both sexes. These behavioral alterations emerged in the absence of pregnancy complications. Prenatal exposure to TiO2 NPs did not cause overt fetal malformations or changes in pregnancy outcomes, nor did it affect postnatal growth of the offspring. Taken together, our study provides a first set of preliminary data suggesting that prenatal exposure to nano-sized TiO2 can induce behavioral deficits relevant to ASD and related neurodevelopmental disorders without inducing major changes in physiological development. If extended further, our preclinical findings may provide an incentive for epidemiological studies examining the role of prenatal TiO2 NPs exposure in the etiology of ASD and other neurodevelopmental disorders.
Project description:<h4>Background</h4>Pregnancy exposure to titanium dioxide nanoparticles (TiO<sub>2</sub>NPs) is a vital consideration due to their inadvertent ingestion from environmental contamination. The potential health effects of TiO<sub>2</sub>NPs on the neurodevelopmental process should be seriously concerned in health risk assessment, especially for the pregnant women who are susceptible to the neurodevelopmental toxicity of nano-sized particles. However, the available evidence of neurodevelopmental toxicity of TiO<sub>2</sub>NPs remains very limited.<h4>Methods</h4>In the present study, the pregnant mice were intragastric administered with 150 mg/kg TiO<sub>2</sub>NPs from gestational day (GD) 8 to 21, the maternal behaviors and neurodevelopment-related indicators in offspring were all assessed at different time points after delivery. The gut microbial community in both dams and their offspring were detected by using 16S ribosomal RNA (rRNA) gene sequencing. The gut-brain axis related indicators were also determined in the offspring.<h4>Results</h4>The results clearly demonstrated that exposure to TiO<sub>2</sub>NPs did not affect the maternal behaviors of pregnant mice, or cause the deficits on the developmental milestones and perturbations in the early postnatal development of offspring. Intriguingly, our data revealed that pregnancy exposure of TiO<sub>2</sub>NPs did not affect locomotor function, learning and memory ability and anxiety-like behavior in offspring at postnatal day (PD) 21, but resulted in obvious impairments on these neurobehaviors at PD49. Similar phenomena were obtained in the composition of gut microbial community, intestinal and brain pathological damage in offspring in adulthood. Moreover, the intestinal dysbiosis induced by TiO<sub>2</sub>NPs might be highly associated with the delayed appearance of neurobehavioral impairments in offspring, possibly occurring through disruption of gut-brain axis.<h4>Conclusions</h4>This is the first report elucidated that pregnancy exposure to TiO<sub>2</sub>NPs caused delayed appearance of neurobehavioral impairments in offspring when they reached adulthood, although these perturbations did not happen at early life after delivery. These findings will provide valuable insights about neurodevelopmental toxicity of TiO<sub>2</sub>NPs, and call for comprehensive health risk assessment of TiO<sub>2</sub>NPs on the susceptible population, such as pregnant women.
Project description:Benzo(a)pyrene (B(a)P) is a well-known genotoxic agent, the removal of which from environmental matrices is mandatory, necessitating the application of cleaning strategies that are harmless to human and environmental health. The potential application of nanoparticles (NPs) in the remediation of polluted environments is of increasing interest. Here, specifically designed NPs were selected as being non-genotoxic and able to interact with B(a)P, in order to address the genetic and chromosomal damage it produces. A newly formulated pure anatase nano-titanium (nano-TiO<sub>2</sub>), a commercial mixture of rutile and anatase, and carbon black-derived hydrophilic NPs (HNP) were applied. Once it had been ascertained that the NPs selected for the work did not induce genotoxicity, marine mussel gill biopsies were exposed in vitro to B(a)P (2 μg/mL), alone and in combination with the selected NPs (50 µg/mL nano-TiO<sub>2</sub>, 10 µg/mL HNP). DNA primary reversible damage was evaluated by means of the Comet assay. Chromosomal persistent damage was assessed on the basis of micronuclei frequency and nuclear abnormalities by means of the Micronucleus-Cytome assay. Transmission Electron Microscopy (TEM) was performed to investigate the mechanism of action exerted by NPs. Pure Anatase n-TiO<sub>2</sub> was found to be the most suitable for our purpose, as it is cyto- and genotoxicity free and able to reduce the genetic and chromosomal damage associated with exposure to B(a)P.
Project description:Titanium dioxide nanoparticles (TiO<sub>2</sub> NPs) are manufactured worldwide. Once they arrive in the soil environment, they can endanger living organisms. Hence, monitoring and assessing the effects of these nanoparticles is required. We focus on the <i>Eisenia andrei</i> earthworm immune cells exposed to sublethal concentrations of TiO<sub>2</sub> NPs (1, 10, and 100 µg/mL) for 2, 6, and 24 h. TiO<sub>2</sub> NPs at all concentrations did not affect cell viability. Further, TiO<sub>2</sub> NPs did not cause changes in reactive oxygen species (ROS) production, malondialdehyde (MDA) production, and phagocytic activity. Similarly, they did not elicit DNA damage. Overall, we did not detect any toxic effects of TiO<sub>2</sub> NPs at the cellular level. At the gene expression level, slight changes were detected. Metallothionein, fetidin/lysenin, lumbricin and MEK kinase I were upregulated in coelomocytes after exposure to 10 µg/mL TiO<sub>2</sub> NPs for 6 h. Antioxidant enzyme expression was similar in exposed and control cells. TiO<sub>2</sub> NPs were detected on coelomocyte membranes. However, our results do not show any strong effects of these nanoparticles on coelomocytes at both the cellular and molecular levels.
Project description:We investigate the role of the mitochondrion, an organelle highly sensitive to environmental agents, in the influence of prenatal air pollution exposure on neurodevelopment and behavior in 96 children with autism spectrum disorder (ASD) [45 with neurodevelopmental regression (NDR); 76% Male; mean (SD) age 10 y 9 m (3 y 9 m)]. Mitochondrial function was assessed using the Seahorse XFe96 in fresh peripheral blood mononuclear cells. Second and third trimester average and maximal daily exposure to fine air particulate matter of diameter ≤2.5 µm (PM<sub>2.5</sub>) was obtained from the Environmental Protection Agency's Air Quality System. Neurodevelopment was measured using the Vineland Adaptive Behavior Scale 2nd edition and behavior was assessed using the Aberrant Behavior Checklist and Social Responsiveness Scale. Prenatal PM<sub>2.5</sub> exposure influenced mitochondrial respiration during childhood, but this relationship was different for those with (r = 0.25-0.40) and without (r = -0.07 to -0.19) NDR. Mediation analysis found that mitochondrial respiration linked to energy production accounted for 25% (SD = 2%) and 10% (SD = 2%) of the effect of average prenatal PM<sub>2.5</sub> exposure on neurodevelopment and behavioral symptoms, respectively. Structural equation models estimated that PM<sub>2.5</sub> and mitochondrial respiration accounted for 34% (SD = 4%) and 36% (SD = 3%) of the effect on neurodevelopment, respectively, and that behavior was indirectly influenced by mitochondrial respiration through neurodevelopment but directly influenced by prenatal PM<sub>2.5</sub>. Our results suggest that prenatal exposure to PM<sub>2.5</sub> disrupts neurodevelopment and behavior through complex mechanisms, including long-term changes in mitochondrial respiration and that patterns of early development need to be considered when studying the influence of environmental agents on neurodevelopmental outcomes.
Project description:The application of Biolog EcoPlate™ for community-level physiological profiling of soils is well documented; however, the functional diversity of aquatic bacterial communities has been hardly studied. The objective of this study was to investigate the applicability of the Biolog EcoPlate™ technique and evaluate comparatively the applied endpoints, for the characterisation of the effects of metal oxide nanoparticles (MONPs) on freshwater microbial communities. Microcosm experiments were run to assess the effect of nano ZnO and nano TiO<sub>2</sub> in freshwater at 0.8-100 mg/L concentration range. The average well colour development, substrate average well colour development, substrate richness, Shannon index and evenness, Simpson index, McIntosh index and Gini coefficient were determined to quantify the metabolic capabilities and functional diversity. Comprehensive analysis of the experimental data demonstrated that short-term exposure to TiO<sub>2</sub> and ZnO NPs affected the metabolic activity at different extent and through different mechanisms of action. TiO<sub>2</sub> NPs displayed lower impact on the metabolic profile showing up to 30% inhibition. However, the inhibitory effect of ZnO NPs reached 99% with clearly concentration-dependent responses. This study demonstrated that the McIntosh and Gini coefficients were well applicable and sensitive diversity indices. The parallel use of general metabolic capabilities and functional diversity indices may improve the output information of the ecological studies on microbial communities.
Project description:<h4>Background</h4>Expanding biomedical application of anatase titanium dioxide (TiO<sub>2</sub>) nanoparticles (NPs) is raising the public concern on its potential health hazards. Here, we demonstrated that TiO<sub>2</sub> NPs can increase phosphatidylserine (PS) exposure and procoagulant activity of red blood cells (RBCs), which may contribute to thrombosis.<h4>Results</h4>We conducted in vitro studies using RBCs freshly isolated from healthy male volunteers. TiO<sub>2</sub> NPs exposure (≦ 25 μg/mL) induced PS exposure and microvesicles (MV) generation accompanied by morphological changes of RBCs. While ROS generation was not observed following the exposure to TiO<sub>2</sub> NPs, intracellular calcium increased and caspase-3 was activated, which up-regulated scramblase activity, leading to PS exposure. RBCs exposed to TiO<sub>2</sub> NPs could increase procoagulant activity as measured by accelerated thrombin generation, and enhancement of RBC-endothelial cells adhesion and RBC-RBC aggregation. Confirming the procoagulant activation of RBC in vitro, exposure to TiO<sub>2</sub> NPs (2 mg/kg intravenously injection) in rats increased thrombus formation in the venous thrombosis model.<h4>Conclusion</h4>Collectively, these results suggest that anatase TiO<sub>2</sub> NPs may harbor prothrombotic risks by promoting the procoagulant activity of RBCs, which needs attention for its biomedical application.
Project description:<h4>Objective</h4>Up to 44% of particulates of food-grade titanium dioxide (TiO<sub>2</sub>) are in nanoscale, while the effect and combined effect of which with other substances on intestinal barrier haven't been fully understood yet. This study is aimed to study the effect of two kinds of TiO<sub>2</sub> nanoparticles (TiO<sub>2</sub> NPs and TiO<sub>2</sub> MPs) on intestinal barrier functions, to reveal the combined effect of TiO<sub>2</sub> NPs and Lipopolysaccharide (LPS) on intestinal barrier.<h4>Methods</h4>Male ICR mice were randomly divided into 18 groups (3 feed types * 3 exposure length * 2 LPS dosage) and were fed with normal or TiO<sub>2</sub>-mixed feed (containing 1% (mass fraction, w/w) TiO<sub>2</sub> NPs or TiO<sub>2</sub> MPs) for 1, 3, 6?months, followed by a single oral administration of 0 or 10?mg/(kg body weight) LPS. Four hours later, the transportation of TiO<sub>2</sub>, the intestinal barrier functions and the inflammatory response were evaluated.<h4>Results</h4>Both TiO<sub>2</sub> notably increased the intestinal villi height / crypt depth ratios after 1 and 3?months of exposure, and increased the expression of ileal tight junction proteins (ZO-1 and occludin) after 1?month of exposure. After 6?months of exposure, TiO<sub>2</sub> NPs led to reduced feed consumption, TiO<sub>2</sub> MPs caused spare microvilli in small intestine and elevated Ti content in the blood cells. The intestinal permeability didn't change in both TiO<sub>2</sub> exposed groups. After LPS administration, we observed altered intestinal villi height / crypt depth ratios, lowered intestinal permeability (DAO) and upregulated expression of ileal ZO-1 in both (TiO<sub>2</sub> +LPS) exposed groups. There are no significant changes of ileal or serum cytokines except for a higher serum TNF-? level in LPS treated group. The antagonistic effect was found between TiO<sub>2</sub> NPs and LPS, but there are complicated interactions between TiO<sub>2</sub> MPs and LPS.<h4>Conclusion</h4>Long-term intake of food additive TiO<sub>2</sub> could alter the intestinal epithelial structure without influencing intestinal barrier function. Co-exposure of TiO<sub>2</sub> and LPS would enhance intestinal barrier function without causing notable inflammatory responses, and there is antagonistic effect between TiO<sub>2</sub> NPs and LPS. All the minor effects observed might associate with the gentle exposure method where TiO<sub>2</sub> being ingested with feed.
Project description:Autism spectrum disorders (ASDs) are a neurodevelopmental disorder characterized by impairments in social interactions and stereotyped behaviors. While ASD has a strong genetic background, environmental factors including toxins, pesticides, infection and drugs are also known to confer autism susceptibility, likely by inducing epigenetic changes. Exposure to Valproic acid (VPA), a drug for epilepsy and bipolar disorders, during pregnancy is highly associated with the risk of ASD children. In rodents, in utero VPA exposure can precipitate behavioral phenotypes related to ASD in the offspring. Since VPA is an inhibitor of histone deacethytransferase (HDAC) activity, it thought to cause ASD with epigenetic modification. However, the core mechanism by which prenatal VPA exposure causes onset of ASD is still not fully uncovered. Here we revealed that prenatal VPA exposure strongly influences development of vasoactive intestinal peptide (VIP) - positive neurons, a subtype of cortical GABAergic interneurons. The number of VIP+ interneurons was severely reduced in somatosensory area of VPA-exposed ASD animals. We then found that the reduction in VIP+ interneurons is caused by the inhibition of HDAC3 activity upon prenatal VPA exposure. Importantly, prenatal HDAC3 inhibition caused not only the selective reduction in VIP+ interneurons but also the ASD-like behaviors in mice. We then demonstrated that the HDAC3 inhibition aberrantly activates Notch signaling, which influences the cell fate determination of VIP+ interneuron progenitors in caudal ganglionic eminence. Thus, this study uncovers the mechanism by which specific HDAC inhibition during development influences a specific type of GABAergic interneurons in the ASD model. The findings provide a novel insight into the understanding of ASD pathophysiology. Overall design: To explore the whole aspect of prenatal VPA exposure on neural development, we screened the gene alteration in the in vitro VPA model that mimics in utero VPA exposure by transcriptomic analyses.
Project description:The enhancement of the photocatalytic activity of TiO? nanoparticles (NPs), synthesized in the presence of a very small amount of magnetite (Fe?O?) nanoparticles, is here presented and discussed. From X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses, the crystallinity of TiO? nanoparticles (NPs) seems to be affected by Fe?O?, acting as nano-seeds to improve the tetragonal TiO? anatase structure with respect to the amorphous one. Photocatalytic activity data, i.e., the degradation of methylene blue and the Ofloxacin fluoroquinolone emerging pollutant, give evidence that the increased crystalline structure of the NPs, even if correlated to a reduced surface to mass ratio (with respect to commercial TiO? NPs), enhances the performance of this type of catalyst. The achievement of a relatively well-defined crystal structure at low temperatures (<i>T</i><sub>max</sub> = 150 °C), preventing the sintering of the TiO? NPs and, thus, preserving the high density of active sites, seems to be the keystone to understand the obtained results.
Project description:Low dose repeated exposures are considered more relevant/realistic in assessing the health risks of nanomaterials (NM), as human exposure such as in workplace occurs in low doses and in a repeated manner. Thus, in a three-week study, we assessed the biological effects (cell viability, cell proliferation, oxidative stress, pro-inflammatory response, and DNA damage) of titanium-di-oxide nanoparticle (TiO<sub>2</sub> NP) agglomerates and synthetic amorphous silica (SAS) aggregates of different sizes in human bronchial epithelial (HBE), colon epithelial (Caco2), and human monocytic (THP-1) cell lines repeatedly exposed to a non-cytotoxic dose (0.76 µg/cm<sup>2</sup>). We noticed that neither of the two TiO<sub>2</sub> NPs nor their agglomeration states induced any effects (compared to control) in any of the cell lines tested while SAS aggregates induced some significant effects only in HBE cell cultures. In a second set of experiments, HBE cell cultures were exposed repeatedly to different SAS suspensions for two weeks (first and second exposure cycle) and allowed to recover (without SAS exposure, recovery period) for a week. We observed that SAS aggregates of larger sizes (size ~2.5 µm) significantly affected the cell proliferation, IL-6, IL-8, and total glutathione at the end of both exposure cycle while their nanosized counterparts (size less than 100 nm) induced more pronounced effects only at the end of the first exposure cycle. As noticed in our previous short-term (24 h) exposure study, large aggregates of SAS did appear to be similarly potent as nano sized aggregates. This study also suggests that aggregates of SAS of size greater than 100 nm are toxicologically relevant and should be considered in risk assessment.