Titanium dioxide nanoparticles induce emphysema‐like lung injury in mice

Evaluation of possible cytotoxic, genotoxic and epigenotoxic effects of titanium dioxide nanoparticles and possible protective effect of melatonin

Nanoparticles (NPs) are particles of matter that are between 1 to 100 nm in diameter. They are suggested to cause toxic effects in both humans and environment thorough different mechanisms. However, their toxicity profile may be different from the parent material. Titanium dioxide (TiO2) NPs are widely used in cosmetic, pharmaceutical and food industries. As a white pigment, the use of TiO2 is used in food coloring, industrial paints, clothing and UV filters has increased tremendously in recent years. Melatonin, on the other hand, is a well-known antioxidant and may prevent oxidative stress caused by a variety of different substances, including NPs. In the current study, we aimed to comparatively investigate the effects of normal-sized TiO2 (220 nm) and nano-sized TiO2 (21 nm) on cytopathology, cytotoxicity, oxidative damage (lipid peroxidation, protein oxidation and glutathione), genotoxicity (8-hydroxydeoxyguanosine), apoptosis (caspase 3, 8 and 9) and epigenetic alterations (global DNA methylation, H3 acetylation) on 3T3 fibroblast cells. In addition, the possible protective effects of melatonin, which is known to have strong antioxidant effects, against the toxicity of TiO2 were also evaluated. Study groups were: a. the control group; b. melatonin group; c. TiO2 group; d. nano-sized TiO2 group; e. TiO2 + melatonin group and f. nano-sized TiO2 + melatonin group. We observed that both normal-sized and nano-sized TiO2 NPs showed significant toxic effects. However, TiO2 NPs caused higher DNA damage and global DNA methylation compared to normal-sized TiO2 whereas normal-sized TiO2 led to lower H3 acetylation vs. TiO2 NPs. Melatonin showed partial protective effect against the toxicity caused by TiO2 NPs.

The toxicological effects of nano titanium dioxide on target organs and mechanisms of toxicity

Nano-titanium dioxide (TiO2 NPs) is widely used for its extremely high stability, corrosion resistance, and photocatalytic properties and has penetrated into various fields of production and life. Assessing its toxicity to different organs should be a key part of preclinical toxicity assessment of TiO2 NPs, which is relatively incomprehensive yet. Therefore, this review focuses on the toxic effects of TiO2 NPs on various organs in mammals and biological mechanisms from different organs. The commonality of toxic effects on various target organs reflected in tissue structure damage and dysfunction, such as liver damage and dysfunction; pulmonary fibrosis; and renal impairment (including hematuria and nephritis); damage of brain tissue and neurons; alteration of intestinal villi; and weight loss. And effects on the reproductive system are affected by different sexes, including ovarian dysfunction, testicular development damage, and sperm viability reduction. We believe that the toxic mechanisms of TiO2 NPs in target organs have commonalities, such as oxidative stress, inflammatory responses, and organelle damage. However, different target organ toxicities also have their specificities. TiO2 NPs disturb the intestinal flora and cause undesirable changes in feces products. And in spleen are infiltration of neutrophils and lymphadenopathy and eventually immune deficiency. Although the toxic pathways are different, but there may be a close link between the different toxic pathways. In this article, the main manifestations of the toxic effects of titanium dioxide nanoparticles on major mammalian organs are reviewed, in order to provide basic data for their better application from a medical perspective.

Wound healing performance of electrospun PVA/70S30C bioactive glass/Ag nanoparticles mats decorated with curcumin: In vitro and in vivo investigations

Biocompatible fibrous scaffold containing polyvinyl alcohol (PVA), 70S30C bioactive glass (BG), silver (Ag) nanoparticles and curcumin (Cur) was fabricated through electrospinning method. Scanning electron microscope (SEM) and Field emission scanning electron microscopy (FESEM) were employed to investigate the morphological characteristics of the scaffolds. In addition, biodegradability, hydrophilicity, and contact angle were studied as criteria for evaluating physical properties of the scaffolds. Tensile strength was reported to be 0.971 ± 0.093 MPa. Also, the viability of fibroblasts after 7 days of cell culture was 93.58 ± 1.36 %. The antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria was illustrated using inhibition zones of 13.12 ± 0.69 and 14.21 ± 1.37 mm, respectively. Histological results revealed that tissue regeneration after 14 days of surgery was much higher for the dressing group compared to the blank group. According to the obtained results, the authors introduce the PVA-BG-Ag-Cur scaffold as a promising candidate for skin tissue engineering applications.

Scanning Electron Microscopy and EDX Spectroscopy of Commercial Swabs Used for COVID-19 Lateral Flow Testing

The chemical composition of COVID test swabs has not been examined beyond the manufacturer's datasheets. The unprecedented demand for swabs to conduct rapid lateral flow tests and nucleic acid amplification tests led to mass production, including 3D printing platforms. Manufacturing impurities could be present in the swabs and, if so, could pose a risk to human health. We used scanning electron microscopy and energy dispersive X-ray (EDX) spectroscopy to examine the ultrastructure of seven assorted brands of COVID test swabs and to identify and quantify their chemical elements. We detected eight unexpected elements, including transition metals, such as titanium and zirconium, the metalloid silicon, as well as post-transition metals aluminium and gallium, and the non-metal elements sulphur and fluorine. Some of the elements were detected as trace amounts, but for others, the amount was close to reported toxicological thresholds for inhalation routes. Experimental studies have shown that the detrimental effects of unexpected chemical elements include moderate to severe inflammatory states in the exposed epithelium as well as proliferative changes. Given the massive testing still being used in the context of the COVID pandemic, we urge caution in continuing to recommend repeated and frequent testing, particularly of healthy, non-symptomatic, individuals.

Experimental animal models of chronic inflammation

Inflammation is a general term for a wide variety of both physiological and pathophysiological processes in the body which primarily prevents the body from diseases and helps to remove dead tissues. It has a crucial part in the body immune system. Tissue damage can recruit inflammatory cells and cytokines and induce inflammation. Inflammation can be classified as acute, sub-acute, and chronic. If it remained unresolved and lasted for prolonged periods, it would be considered as chronic inflammation (CI), which consequently exacerbates tissue damage in different organs. CI is the main pathophysiological cause of many disorders such as obesity, diabetes, arthritis, myocardial infarction, and cancer. Thus, it is critical to investigate different mechanisms involved in CI to understand its processes and to find proper anti-inflammatory therapeutic approaches for it. Animal models are one of the most useful tools for study about different diseases and mechanisms in the body, and are important in pharmacological studies to find proper treatments. In this study, we discussed the various experimental animal models that have been used to recreate CI which can help us to enhance the understanding of CI mechanisms in human and contribute to the development of potent new therapies.

A multiplex inhalation platform to model in situ like aerosol delivery in a breathing lung-on-chip

Prolonged exposure to environmental respirable toxicants can lead to the development and worsening of severe respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD) and fibrosis. The limited number of FDA-approved inhaled drugs for these serious lung conditions has led to a shift from in vivo towards the use of alternative in vitro human-relevant models to better predict the toxicity of inhaled particles in preclinical research. While there are several inhalation exposure models for the upper airways, the fragile and dynamic nature of the alveolar microenvironment has limited the development of reproducible exposure models for the distal lung. Here, we present a mechanistic approach using a new generation of exposure systems, the Cloud α AX12. This novel in vitro inhalation tool consists of a cloud-based exposure chamber (VITROCELL) that integrates the breathing ^AXLung-on-chip system (AlveoliX). The ultrathin and porous membrane of the AX12 plate was used to create a complex multicellular model that enables key physiological culture conditions: the air-liquid interface (ALI) and the three-dimensional cyclic stretch (CS). Human-relevant cellular models were established for a) the distal alveolar-capillary interface using primary cell-derived immortalized alveolar epithelial cells (^AXiAECs), macrophages (THP-1) and endothelial (HLMVEC) cells, and b) the upper-airways using Calu3 cells. Primary human alveolar epithelial cells (^AXhAEpCs) were used to validate the toxicity results obtained from the immortalized cell lines. To mimic in vivo relevant aerosol exposures with the Cloud α AX12, three different models were established using: a) titanium dioxide (TiO2) and zinc oxide nanoparticles b) polyhexamethylene guanidine a toxic chemical and c) an anti-inflammatory inhaled corticosteroid, fluticasone propionate (FL). Our results suggest an important synergistic effect on the air-blood barrier sensitivity, cytotoxicity and inflammation, when air-liquid interface and cyclic stretch culture conditions are combined. To the best of our knowledge, this is the first time that an in vitro inhalation exposure system for the distal lung has been described with a breathing lung-on-chip technology. The Cloud α AX12 model thus represents a state-of-the-art pre-clinical tool to study inhalation toxicity risks, drug safety and efficacy.

Recent Insights into NIR-Light-Responsive Materials for Photothermal Cell Treatments

Controlling cells using photo-responsive materials is highly indispensable in the current biomedical sector. Considering the potential side effects of nanoparticles, it has become a challenge to control cells with photo-responsive materials. Recent studies have described several methods for controlling cell behavior using nanoparticles subjected to the near-infrared (NIR) laser light operating at the wavelength of 808 nm to 980 nm and at the power densities of 0.33 to 0.72 W·cm^-2. The challenge here is the preparation of biocompatible nanoparticles for both in vivo and in vitro studies and understanding cell behavior with an external light source recommended for biological application. Earlier studies have well documented many approaches and associated mechanisms for controlling cell behavior and the interaction between nanoparticles, cells, and appropriate external light sources. In this review, various nanomaterials such as metal nanomaterials and carbon-based nanomaterials are compared systematically regarding the effects of controlling cell behavior and inflammation by studying their mechanisms, route of administration, dose, and adverse effects such as toxicity and the interaction of nanoparticles with a specific wavelength of the light. Future directions should focus on stable and efficient light-responsive materials with minimal cytotoxicity.

An Overview of Essential Microelements and Common Metallic Nanoparticles and Their Effects on Male Fertility

Numerous factors affect reproduction, including stress, diet, obesity, the use of stimulants, or exposure to toxins, along with heavy elements (lead, silver, cadmium, uranium, vanadium, mercury, arsenic). Metals, like other xenotoxins, can cause infertility through, e.g., impairment of endocrine function and gametogenesis or excess production of reactive oxygen species (ROS). The advancement of nanotechnology has created another hazard to human safety through exposure to metals in the form of nanomaterials (NMs). Nanoparticles (NPs) exhibit a specific ability to penetrate cell membranes and biological barriers in the human body. These ultra-fine particles (<100 nm) can enter the human body through the respiratory tract, food, skin, injection, or implantation. Once absorbed, NPs are transported to various organs through the blood or lymph. Absorbed NPs, thanks to ultrahigh reactivity compared to bulk materials in microscale size, disrupt the homeostasis of the body as a result of interaction with biological molecules such as DNA, lipids, and proteins; interfering with the functioning of cells, organs, and physiological systems; and leading to severe pathological dysfunctions. Over the past decades, much research has been performed on the reproductive effects of essential trace elements. The research hypothesis that disturbances in the metabolism of trace elements are one of the many causes of infertility has been unquestionably confirmed. This review examines the complex reproductive risks for men regarding the exposure to potentially harmless xenobiotics based on a series of 298 articles over the past 30 years. The research was conducted using PubMed, Web of Science, and Scopus databases searching for papers devoted to in vivo and in vitro studies related to the influence of essential elements (iron, selenium, manganese, cobalt, zinc, copper, and molybdenum) and widely used metallic NPs on male reproduction potential.

Exploring the intrinsic micro-/nanoparticle size on their in vivo fate after lung delivery

Micro-/nanocarriers due to their significant advantages are widely investigated in pulmonary drug delivery. However, different size carriers have varied drug release rate, concealing the effect of particle size on the fate of drugs in vivo. Therefore, by keeping drug release rate comparable, the objective of this study is to elucidate the influence of particle size itself on drug in vivo fate after intratracheal instillation to mice. Here, using paclitaxel (PTX) as a drug model, 100 nm, 300 nm, 800 nm, and 2500 nm poly(lactide-co-glycolide) (PLGA) particles with the same release rate were prepared. It was demonstrated that the in vivo fate of particles after lung delivery was size-dependent. Consistent with most reports of model particles with neglected release kinetics, the mucus penetration capacity in airtifical mucus decreased with increasing particle size and there is no significant difference between 800 nm and 2500 nm particles. The in vivo airway distribution experiments confirmed the results of the in vitro mucus penetration study, that is, the smaller the particles, the more distributed in the airway. Both in vitro and in vivo macrophage uptake results confirmed that the larger particles were more readily taken up by macrophages. In contrast, the uptake of smaller particles in A549 cells was higher than that of larger particles. Some new findings were disclosed in lung retention, lung absorption and lung targeting. Different from previous reports, this study demonstrated that particles with smaller size had longer lung retention, AUC_(0-t) in bronchoalveolar lavage fluid (BALF) of 100 nm particles was 1.6, 1.9, 2.5 times higher than that of 300 nm, 800 nm, and 2500 nm particles and 11.7 times of the PTX solution group. The same trend was observed in lung tissue absorption, the AUC_(0-t) in the lavaged lung of 100 nm particles was 1.8, 2.2, 2.8, 8.6 times higher than that of 300 nm, 800 nm, 2500 nm particles and PTX solution groups, respectively. The lung targeting efficiency was particles size independent. In conclusion, the in vivo fate of particles with the same release kinetics after intratracheal instillation is size-dependent, smaller size particles are conducive for lung retention and lung absorption. Overall, our study provided scientific guidance for the rational design of particle based pulmonary drug delivery system.

Titanium Dioxide: Structure, Impact, and Toxicity

Titanium dioxide, first manufactured a century ago, is significant in industry due to its chemical inertness, low cost, and availability. The white mineral has a wide range of applications in photocatalysis, in the pharmaceutical industry, and in food processing sectors. Its practical uses stem from its dual feature to act as both a semiconductor and light scatterer. Optical performance is therefore of relevance in understanding how titanium dioxide impacts these industries. Recent breakthroughs are summarised herein, focusing on whether restructuring the surface properties of titanium dioxide either enhances or inhibits its reactivity, depending on the required application. Its recent exposure as a potential carcinogen to humans has been linked to controversies around titanium dioxide's toxicity; this is discussed by illustrating discrepancies between experimental protocols of toxicity assays and their results. In all, it is important to review the latest achievements in fast-growing industries where titanium dioxide prevails, while keeping in mind insights into its disputed toxicity.

A New Look at the Effects of Engineered ZnO and TiO2 Nanoparticles: Evidence from Transcriptomics Studies

Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) have attracted a great deal of attention due to their excellent electrical, optical, whitening, UV-adsorbing and bactericidal properties. The extensive production and utilization of these NPs increases their chances of being released into the environment and conferring unintended biological effects upon exposure. With the increasingly prevalent use of the omics technique, new data are burgeoning which provide a global view on the overall changes induced by exposures to NPs. In this review, we provide an account of the biological effects of ZnO and TiO2 NPs arising from transcriptomics in in vivo and in vitro studies. In addition to studies on humans and mice, we also describe findings on ecotoxicology-related species, such as Danio rerio (zebrafish), Caenorhabditis elegans (nematode) or Arabidopsis thaliana (thale cress). Based on evidence from transcriptomics studies, we discuss particle-induced biological effects, including cytotoxicity, developmental alterations and immune responses, that are dependent on both material-intrinsic and acquired/transformed properties. This review seeks to provide a holistic insight into the global changes induced by ZnO and TiO2 NPs pertinent to human and ecotoxicology.

Role of necroptosis of alveolar macrophages in acute lung inflammation of mice exposed to titanium dioxide nanoparticles

Titanium dioxide (TiO₂) nanoparticles are indispensable for daily life but induce acute inflammation, mainly via inhalation exposure. TiO₂ nanoparticles can be phagocytosed by alveolar macrophages (AMs) in vivo and cause necroptosis of exposed cells in vitro. However, the relationship between localization of TiO₂ nanoparticles in the lungs after exposure and their biological responses including cell death and inflammation remains unclear. This study was conducted to investigate the intra/extracellular localization of TiO₂ nanoparticles in murine lungs at 24 h after intratracheal exposure to rutile TiO₂ nanoparticles and subsequent local biological reactions, specifically necroptosis of AMs and lung inflammation. We found that TiO₂ exposure induced leukocyte migration into the alveolar region and increased the secretion of C-C motif ligand (CCL) 3 in the bronchoalveolar lavage (BAL) fluid. A combination of Raman spectroscopy and staining of cell and tissue samples confirmed that AMs phagocytose TiO₂. AMs that phagocytosed TiO₂ nanoparticles showed necroptosis, characterized by the expression of phosphorylated mixed lineage kinase domain-like protein and translocation of high mobility group box-1 from the cell nucleus to the cytoplasm. In primary cultured AMs, TiO₂ also induced necroptosis and increased the secretion of CCL3. Necroptosis inhibitors suppressed the increase in CCL3 secretion in both the BAL fluid and culture supernatant of AMs and suppressed the increase in leukocytes in the BAL fluid. These data suggest that necroptosis of AMs that phagocytose TiO₂ nanoparticles is involved as part of the mechanism by which TiO₂ induces acute lung inflammation.

Maternal and developmental toxicity induced by Nanoalumina administration in albino rats and the potential preventive role of the pumpkin seed oil

Although Nanoalumina is widely used in many biomedical applications, its potential toxic effect on pregnant women and developing embryos/fetuses has not been reported. In this investigation, the maternal and developmental toxicity caused by Nanoalumina during gestation and the potential preventive role of the pumpkin seed oil (PSO) were evaluated. Four groups of pregnant rats were orally administered during days 5–19 of gestation as follows: control group, Nanoalumina group (70 mg/kg b.w), PSO- group (4 ml/kg b.w.), and Nanoalumina plus PSO- group. Nanoalumina induced detrimental impacts in pregnancy outcomes, fetal growth retardation, morphological anomalies, hepatic and neural DNA damage, and histopathological changes in hepatic and neural tissues of both mother and fetus, respectively. Furthermore, the level of MDA is significantly increased and activities of GSH and CAT are significantly reduced in both tissues of nanoalumina‐administered rats. PSO co administration improved pregnancy outcomes, fetal growth parameters, DNA damage, antioxidant defenses the histopathological changes of nanoalumina‐gavaged rats and significantly diminished MDA level. Finally, PSO has a preventive role against the detrimental impacts of nanoalumina in dams and fetuses probably via its potential to prevent reactive oxygen species.

In vitro acaricidal activity of green synthesized nickel oxide nanoparticles against the camel tick, Hyalomma dromedarii (Ixodidae), and its toxicity on Swiss albino mice

The green synthesized nanoparticles have been determined as a novel pesticide against arthropod pests. This study was designed to evaluate the in vitro acaricidal activity of green synthesized nickel oxide nanoparticles (NiO NPs) using aqueous extract of Melia azedarach ripened fruits against different developmental stages of the camel tick Hyalomma dromedarii in addition to their toxic effect on laboratory animals. The synthesized NiO NPs were characterized by UV-visible (UV-Vis) spectroscopy, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The UV-Vis spectra of the NiO NPs showed an absorption peak at 307 nm. FTIR analysis showed the possible functional groups used for capping and stabilization of NiO NPs with strong bands at 3416.2 and 1626.6 cm^-1. The SEM images of the NiO NPs exhibited a size ranging from 21 to 35 nm. The immersion test was used for the in vitro application of the synthesized NiO NPs on the various tick stages (egg, nymph, larva, and adult). Mortality percentages and LC₅₀ values of each tick stage were calculated. The oviposition and hatchability of the engorged females were monitored for the survived tick after treatment. The LC₅₀ values for NiO NPs on embryonated eggs, larvae, and engorged nymphs were 5.00, 7.15, and 1.90 mg/mL, respectively. The egg productive index (EPI), egg number, and hatchability (%) were lower in females treated with the NiO NPs than in control ticks. The toxicity of the NiO NPs on laboratory animals was also investigated using Swiss albino mice by oral dose of 500 mg/kg/day administration for five consecutive days. The hematological, biochemical, and histopathological changes were evaluated. The hematological analysis showed significant increase in the level of white blood cells (WBC) and hemoglobin (Hb). Biochemical analysis showed non-significant decrease in alkaline phosphatase (ALP) and alanine amino transferase (ALT). We concluded that NiO NPs have a significant acaricidal activity as demonstrated on eggs, larvae, engorged nymphs, and fully fed females of H. dromedarii. From a toxicological point of view further in vivo investigations are needed to determine the mechanism of toxic effect of NiO NPs.

Cytotoxicity and DNA damage evaluation of TiO2 and ZnO nanoparticles. Uptake in lung cells in culture

The cytotoxicity and DNA damage of titanium dioxide and zinc oxide nanoparticles (TiO₂ and ZnO NPs) have been studied in a human lung carcinoma cell line (A549) after 24 h exposure. TiO₂ and ZnO NPs had mean diameters of 12.9 ± 2.8 and 24.1 ± 8.0 nm, respectively. ZnO NPs reduced cell viability from 250 μg/mL, increasing reactive oxygen species (ROS) and decreased GSH/GSSG ratio. The comet assay detected DNA damage from 50 μg/mL. TiO₂ NPs induced cytotoxicity and DNA damage from 50 to 100 μg/mL, respectively, along with a decrease of the GSH/GSSG ratio. Both particles were found inside the cells, within membrane-bound vesicles. The internalization mechanism is promoted partially by caveolae-mediated endocytosis and, in the case of TiO₂ NPs, also by macropinocytosis.

DNA damage and ovarian ultrastructural lesions induced by nickel oxide nano-particles in Blaps polycresta (Coleoptera: Tenebrionidae)

Nickel oxide nanoparticles (NiO-NPs) have extensively used in industrial and consumer products. The present study conducted to gain more knowledge about the safe use of NiO-NPs and also to understand their impact on the environment and biological systems. Herein, we examined the genotoxic and ultra-structural effects of a sublethal dose of NiO-NPs (0.03 mg/g) on the ovarian tissues of the ground beetle, Blaps polycresta. The mean diameter of NiO-NPs was 24.49 ± 3.88 nm, as obtained through transmission electron microscopy (TEM). In terms of DNA damage levels, the frequency of micronucleus (MN) formation was highly significant in the NiO-NPs treated group versus the controls. Besides, NiO-NPs treatment resulted in a significant increase in the tail length of comets. Further, electron microscopy revealed a progressive increase in chromatin condensation of the ovarian nurse and follicular cells, in addition to the accumulation of lysosomes and endo-lysosomes in their cytoplasm. In conclusion, NiO-NPs are capable of gaining access to the ovary of B. polycresta and causing DNA damage and a high degree of cellular toxicity in the ovarian cells. The present study highlights, for the first time, the adverse effects of these NPs to female gonads of insects and raised the concern of its genotoxic potential. It would be of interest to investigate NiO-NPs mediated intracellular ROS generation in future studies.

Titanium dioxide nanoparticles impair the inner blood-retinal barrier and retinal electrophysiology through rapid ADAM17 activation and claudin-5 degradation

Background

Depending on their distinct properties, titanium dioxide nanoparticles (TiO₂-NPs) are manufactured extensively and widely present in our daily necessities, with growing environmental release and public concerns. In sunscreen formulations, supplementation of TiO₂-NPs may reach up to 25% (w/w). Ocular contact with TiO₂-NPs may occur accidentally in certain cases, allowing undesirable risks to human vision. This study aimed to understand the barrier integrity of retinal endothelial cells in response to TiO₂-NP exposure. bEnd.3 cells and human retinal endothelial cells (HRECs) were exposed to TiO₂-NP, followed by examination of their tight junction components and functions.

Results

TiO2-NP treatment apparently induced a broken structure of the junctional plaques, conferring decreased transendothelial electrical resistance, a permeable paracellular cleft, and improved cell migration in vitro. This might involve rapid activation of metalloproteinase, a disintegrin and metalloproteinase 17 (ADAM17), and ADAM17-mediated claudin-5 degradation. For the in vivo study, C57BL/6 mice were administered a single dose of TiO2-NP intravitreally and then subjected to a complete ophthalmology examination. Fluorescein leakage and reduced blood flow at the optical disc indicated a damaged inner blood-retinal barrier induced by TiO₂-NPs. Inappreciable change in the thickness of retinal sublayers and alleviated electroretinography amplitude were observed in the TiO₂-NP-treated eyes.

Conclusions

Overall, our data demonstrate that TiO2-NP can damage endothelial cell function, thereby affecting retinal electrophysiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-020-00395-7.

Food-Grade TiO2 Particles Generate Intracellular Superoxide and Alter Epigenetic Modifiers in Human Lung Cells

Titanium dioxide (TiO₂) particles are a common ingredient in food, providing the bright white color for many candies, gums, and frostings. While ingestion of these materials has been examined previously, few studies have examined the effect of these particles on lung cells. Inhalation is an important exposure pathway for workers processing these foods and, more recently, home users who purchase these particles directly. We examine the response of lung cells to food-grade TiO₂ particles using a combination of fluorescence microscopy and RT-PCR. These experiments show that TiO₂ particles generate intracellular reactive oxygen species, specifically superoxide, and alter expression of two epigenetic modifiers, histone deacetylase 9 (HDAC9) and HDAC10. We use a protein corona formed from superoxide dismutase (SOD), an enzyme that scavenges superoxide, to probe the relationship between TiO₂ particles and superoxide generation. These experiments show that low, non-cytotoxic, concentrations of food-grade TiO₂ particles lead to cellular responses, including altering two enzymes responsible for epigenetic modifications. This production of superoxide and change in epigenetic modifiers could affect human health following inhalation. We expect this research will motivate future in vivo experiments examining the pulmonary response to food-grade TiO₂ particles.

Effect of titanium dioxide nanoparticles on DNA methylation in multiple human cell lines

Nanoscale titanium dioxide (TiO2) is manufactured in wide scale, with a range of applications in consumer products. Significant toxicity of TiO2 nanoparticles has, however, been recognized, suggesting considerable risk to human health. To evaluate fully their toxicity, assessment of the epigenetic action of these nanoparticles is critical. However, only few studies are available examining capability of nanoparticles to alter epigenetic integrity. In the present study, the effect of TiO2 nanoparticles exposure on DNA methylation, a major epigenetic mechanism, was investigated in in vitro cellular model systems. A panel of cells relevant to portals of human exposure (Caco-2 (colorectal), HepG2 (liver), NL20 (lung), and A-431 (skin)) was exposed to TiO2 nanoparticles to assess effects on global methylation, gene-specific methylation, and expression levels of DNA methyltransferases, MBD2, and UHRF1. Global methylation was determined by enzyme-linked immunosorbent assay-based immunochemical analysis. Degree of promoter methylation across a defined panel of genes was evaluated using EpiTect Methyl II Signature PCR System Array technology. Expression of DNMT1, DNMT3a, DNMT3b, MBD2, and URHF1 was quantified by qRT-PCR. Decrease in global DNA methylation in cell lines Caco-2, HepG2, and A-431 exposed to TiO2 nanoparticles was shown. Across four cell lines, eight genes (CDKN1A, DNAJC15, GADD45A, GDF15, INSIG1, SCARA3, TP53, and BNIP3) were identified in which promotors were methylated after exposure. Altered expression of these genes is associated with disease etiology. The results also revealed aberrant expression of epigenetic regulatory genes involved in DNA methylation (DNMT1, DNMT3a, DNMT3b, MBD2, and UHRF1) in TiO2 exposed cells, which was cell type dependent. Findings from this study clearly demonstrate the impact of TiO2 nanoparticles exposure on DNA methylation in multiple cell types, supporting potential involvement of this epigenetic mechanism in the toxicity of TiO2 nanoparticles. Hence for complete assessment of potential risk from nanoparticle exposure, epigenetic studies are critical.

Zinc Oxide Nanowires Exposure Induces a Distinct Inflammatory Response via CCL11-Mediated Eosinophil Recruitment

High aspect ratio zinc oxide nanowires (ZnONWs) have become one of the most important products in nanotechnology. The wide range applications of ZnONWs have heightened the need for evaluating the risks and biological consequences to these particles. In this study, we investigated inflammatory pathways activated by ZnONWs in cultured cells as well as the consequences of systemic exposure in mouse models. Confocal microscopy showed rapid phagocytic uptake of FITC-ZnONWs by macrophages. Exposure of macrophages or lung epithelial cells to ZnONWs induced the production of CCL2 and CCL11. Moreover, ZnONWs exposure induced both IL-6 and TNF-α production only in macrophages but not in LKR13 cells. Intratracheal instillation of ZnONWs in C57BL/6 mice induced a significant increase in the total numbers of immune cells in the broncho alveolar lavage fluid (BALFs) 2 days after instillation. Macrophages and eosinophils were the predominant cellular infiltrates of ZnONWs exposed mouse lungs. Similar cellular infiltrates were also observed in a mouse air-pouch model. Pro-inflammatory cytokines IL-6 and TNF-α as well as chemokines CCL11, and CCL2 were increased both in BALFs and air-pouch lavage fluids. These results suggest that exposure to ZnONWs may induce distinct inflammatory responses through phagocytic uptake and formation of soluble Zn²⁺ ions.

The role of sex in particle-induced inflammation and injury

The use of engineered nanomaterials within various applications such as medicine, electronics, and cosmetics has been steadily increasing; therefore, the rate of occupational and environmental exposures has also increased. Inhalation is an important route of exposure to nanomaterials and has been shown to cause various respiratory diseases in animal models. Human lung disease frequently presents with a sex/gender-bias in prevalence or severity, but investigation of potential sex-differences in the adverse health outcomes associated with nanoparticle inhalation is greatly lacking. Only ~20% of basic research in the general sciences use both male and female animals and a substantial percentage of these do not address differences between sexes within their analyses. This has prevented researchers from fully understanding the impact of sex-based variables on health and disease, particularly the pathologies resulting from the inhalation of particles. The mechanisms responsible for sex-differences in respiratory disease remain unclear, but could be related to a number of variables including sex-differences in hormone signaling, lung physiology, or respiratory immune function. By incorporating sex-based analysis into respiratory nanotoxicology and utilizing human data from other relevant particles (e.g., asbestos, silica, particulate matter), we can improve our understanding of sex as a biological variable in nanoparticle exposures. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Effects of nanoparticles on neuroinflammation in a mouse model of asthma

The interaction between chronic inflammation and neural dysfunction points to a link between the nervous and immune systems in the airways. In particular, environmental exposure to nanoparticles (NPs), defined as particulate matter having one dimension <100 nm, is associated with an enhanced risk of childhood and adult asthma. However, the impact of NPs on the neural response in asthma remains to be determined. This study determined the impact of NPs on neuroinflammation in a mouse model of allergic asthma. Ovalbumin (OVA) sensitized mice were treated with saline (Sham), OVA challenged and exposed to 200 μg/m³ NPs 1 h a day for 3 days on days 21-23 in a closed-system chamber attached to a ultrasonic nebulizer. The effect of NPs on the levels of neuropeptides, transient receptor potential vanilloid 1 (TRPV1), TRPV4, P2 × 4, and P2 × 7 was assessed by enzyme-linked immunosorbent assays, immunoblotting, and immunohistochemistry. NP exposure increased airway inflammation and responsiveness in OVA mice, and these increases were augmented in OVA plus NP-exposed mice. The lung tissue levels of TRPV1, TRPV4, P2 × 4, and P2 × 7 were increased in OVA mice, and these increases were augmented in OVA plus NP-exposed mice. The substance P, adenosine triphosphate (ATP), and calcitonin gene-related peptide (CGRP) levels in bronchoalveolar lavage fluid were increased in OVA mice, and these increases were augmented in OVA plus NP-exposed mice. Bradykinin, ATP, and CGRP were dose dependently increased in NP-exposed normal human bronchial epithelial (NHBE) cells. The calcium concentration was increased in NHBE cells exposed to NPs for 8 h. These results indicate that neuroinflammation can be involved in the pathogenesis of bronchial asthma and that NPs can exacerbate asthma via neuromediator release.

Different effects of titanium dioxide nanoparticles instillation in young and adult mice on DNA methylation related with lung inflammation and fibrosis

Wide use of titanium dioxide nanoparticles (TiO₂ NPs) as white pigments induces unintentionally release in environment which increases concerns about their adverse health effects on respiratory system. So it is crucial to get a deep understanding of the disease process and molecular mechanism. Epigenetic mechanisms, such as DNA methylation, have been found to play a role in the development of lung diseases by affecting expression of key genes. In addition, there could be potential different toxic effects of TiO₂ NPs between young and adult. Thus, the comparative toxicity of TiO₂ NPs in 5-week (young) and 10-week (adult) old NIH mice is investigated in this study following nasal inhalation of TiO₂ NPs at dose of 20 mg/kg (body weight)/day for 30 days. Global DNA methylation and hydroxymethylation in lung were measured. Promoter methylation of inflammatory genes (IFN-γ and TNF-α) and tissue fibrosis gene (Thy-1) were determined. Additional, RNA-sequencing runs were performed on the pulmonic libraries. We found the induced pulmonary inflammation and fibrosis were more severe in young mice. Decreased global methylation and hydroxymethylation were only found in the young group. The altered methylation in promoter of TNF-α and Thy-1 were found to play a role in the inflammatory response and fibration. RNA-sequencing showed that in pathways in cancer expression of 197 genes was up-regulated in the young mice more that in the adult mice. All these results suggested that the young ages are more sensitive to TiO₂ NP exposure and the potential of abnormal DNA methylation might be used as biomarkers of both exposure and disease development.

The impact of implant abutment surface treatment with TiO2 on peri-implant levels of angiogenesis and bone-related markers: a randomized clinical trial

The goal of this randomized, blinded, split-mouth controlled clinical trial was to assess the influence of abutment surface treatment on tissue healing. Fifteen patients received two implants distributed randomly to two groups: test (TiO₂ abutment surface), control (standard abutment surface). Levels of epidermal growth factor (EGF), bone morphogenetic protein 9 (BMP-9), endothelin 1 (ET-1), fibroblast growth factor (FGF), placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) were quantified in the peri-implant fluid after 3, 14, 30, and 60 days. Inter-group comparisons indicated higher levels of EGF, BMP-9, ET-1, FGF, and PlGF in the test group after 30days (P<0.05). PlGF levels were also higher in the test group after 60 days. In the test group, intra-group analysis revealed different levels of ET-1 and FGF between days 3 and 30, and days 3 and 60 (P<0.05); furthermore, VEGF levels were significantly higher on day 60 than on day 3 (P <0.05). In the control group, intra-group analysis demonstrated significantly different levels of ET-1, FGF, and PlGF between days 3 and 60 and of PlGF between days 14 and 60 (P<0.05). In conclusion, abutment surfaces treated with TiO₂ influenced the levels of angiogenesis and bone-related markers.

Role of Endocrine-Disrupting Engineered Nanomaterials in the Pathogenesis of Type 2 Diabetes Mellitus

Nanotechnology has enabled the development of innovative technologies and products for several industrial sectors. Their unique physicochemical and size-dependent properties make the engineered nanomaterials (ENMs) superior for devising solutions for various research and development sectors, which are otherwise unachievable by their bulk forms. However, the remarkable advantages mediated by ENMs and their applications have also raised concerns regarding their possible toxicological impacts on human health. The actual issue stems from the absence of systematic data on ENM exposure-mediated health hazards. In this direction, a comprehensive exploration on the health-related consequences, especially with respect to endocrine disruption-related metabolic disorders, is largely lacking. The reasons for the rapid increase in diabetes and obesity in the modern world remain largely unclear, and epidemiological studies indicate that the increased presence of endocrine disrupting chemicals (EDCs) in the environment may influence the incidence of metabolic diseases. Functional similarities, such as mimicking natural hormonal actions, have been observed between the endocrine-disrupting chemicals (EDCs) and ENMs, which supports the view that different types of NMs may be capable of altering the physiological activity of the endocrine system. Disruption of the endocrine system leads to hormonal imbalance, which may influence the development and pathogenesis of metabolic disorders, particularly type 2 diabetes mellitus (T2DM). Evidence from many in vitro, in vivo and epidemiological studies, suggests that ENMs generally exert deleterious effects on the molecular/hormonal pathways and the organ systems involved in the pathogenesis of T2DM. However, the available data from several such studies are not congruent, especially because of discrepancies in study design, and therefore need to be carefully examined before drawing meaningful inferences. In this review, we discuss the outcomes of ENM exposure in correlation with the development of T2DM. In particular, the review focuses on the following sub-topics: (1) an overview of the sources of human exposure to NMs, (2) systems involved in the uptake of ENMs into human body, (3) endocrine disrupting engineered nanomaterials (EDENMs) and mechanisms underlying the pathogenesis of T2DM, (4) evidence of the role of EDENMs in the pathogenesis of T2DM from in vitro, in vivo and epidemiological studies, and (5) conclusions and perspectives.

Retracted: Pulmonary fibrosis of mice and its molecular mechanism following chronic inhaled exposure to TiO2 nanoparticles

Nanoparticulate titanium dioxide (nano-TiO2 ) has been widely used in industry, medicine and daily life. However, assessment of nano-TiO2 toxicity on health is an important occupational safety issue. Numerous studies have demonstrated that nano-TiO2 can induced sustained pulmonary inflammation, but whether chronic exposure to nano-TiO2 results in pulmonary fibrosis is unclear. In this study, therefore, nano-TiO2 was administered to the male mice by nasal administration for six consecutive months, the inflammatory and/or fibrogenic responses induced by nano-TiO2 were investigated. The results showed that chronic inhaled nano-TiO2 induced pulmonary inflammation and firosis, increased expression of inflammatory cytokines and fibrotic cytokines including nuclear factor-κB, interleukin-1β, tumor necrosis factor-α, monocyte chemotactic protein 1, macrophage inflammatory protein-2, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, transform growth factor -β1, osteopontin, matrix metalloproteinase-1, -2, -3, and -9, tissue inhibitors of metalloproteinase-1, collagen, platelet derived growth factor, and connective tissue growth factor in mouse lung. Taken together, nano-TiO2 -induced pulmonary inflammation and fibrosis are closely associated with increased expression of inflammatory and/or fibrotic cytokines, an imbalanced production of MMPs and TIMP-1 that favors fibrosis in mice, implying that nano-TiO2 may lead to potential health effects.

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.

Histopathological Effects of Titanium Dioxide Nanoparticles and The Possible Protective Role of N-Acetylcysteine on The Testes of Male Albino Rats

BACKGROUND

Titanium dioxide (TiO₂) is a white pigment which is used in paints, plastics, etc. It is reported that TiO₂ induces oxidative stress and DNA damage. N-acetylcysteine (NAC) has been used to fight oxidative stress-induced damage in different tissues. The objective of this study was to evaluate the toxic effects of orally administered TiO₂ nanoparticles and the possible protective effect of NAC on the testes of adult male albino rats.

MATERIALS AND METHODS

In this experimental study, 50 adult male albino rats were classified into five groups. Group I was the negative control, group II was treated with gum acacia solution , group III was treated with NAC, group IV was treated with TiO₂ nanoparticles, and group V was treated with 100 mg/kg of NAC and 1200 mg/kg TiO₂ nanoparticles. Total testosterone, glutathione (GSH), and serum malondialdehyde (MDA) levels were estimated. The testes were subjected to histopathological, electron microscopic examinations, and immunohistochemical detection for tumor necrosis factor (TNF)-α. Cells from the left testis were examined to detect the degree of DNA impairment by using the comet assay.

RESULTS

TiO₂ nanoparticles induced histopathological and ultrastructure changes in the testes as well as positive TNF-α immunoreaction in the testicular tissue. Moreover, there was an increase in serum MDA while a decrease in testosterone and GSH levels in TiO₂ nanoparticles-treated group. TiO₂ resulted in DNA damage. Administration of NAC to TiO₂- treated rats led to improvement of the previous parameters with modest protective effects against DNA damage.

CONCLUSION

TiO₂-induced damage to the testes was mediated by oxidative stress. Notably, administration of NAC protected against TiO₂'s damaging effects.

Genotoxicity study of nickel oxide nanoparticles in female Wistar rats after acute oral exposure

Nanoparticles (NPs) apart from their widespread advantages and increased utilisation, have aroused concerns over their safe use. Nickel (II) oxides (NiO) NPs are used as catalysts, biosensors and in many of the consumer products. The increasing use of NiO NPs necessitates an improved understanding of their potential impact on the environment and human health. In this study, we investigated the acute genotoxic effects of NiO NPs by oral route administration with three different doses (125, 250 and 500 mg/kg bw). Before the in vivo toxicological evaluation, characterisation of particles by Transmission Electron Microscopy, X-ray diffraction, Dynamic Light Scattering (DLS) and Laser Doppler Velocimetry analysis was performed. Genotoxicity biomarkers such as comet, micronucleus and chromosomal aberrations (CAs) assays were utilised in this study. To document the uptake, retention and elimination of the NPs, biodistribution studies were also performed. The particle size obtained from Transmission Electron Microscopy analysis for NiO NPs was 15.62 ± 2.59 nm. The mean hydrodynamic diameter and PdI of NiO NPs in Milli-Q water suspension obtained by DLS was 168.9 ± 17.13 nm and 0.375, respectively. Comet assay revealed significant (P < 0.001) DNA damage at 500 mg/kg bw dose in the PBL, liver and kidney cells of rats at the 24-h sampling time. The result of micronucleus and CAs tests was in agreement with the comet assay data. Biodistribution of NiO NPs revealed a maximum accumulation of Ni in the liver tissue at the 24-h sampling time. Our study showed significant DNA damage at the high dose level and the effect was more prominent at 24-h sampling time, providing preliminary evidence that the NiO NPs are capable of inducing genotoxicity when administered through the oral route. However, mechanistic investigations are needed before drawing any firm conclusion regarding the toxicology of NiO NPs.

A perspective of mitochondrial dysfunction in rats treated with silver and titanium nanoparticles (AgNPs and TiNPs)

Nanotechnology is a growing branch of science that deals with the development of structural features bearing at least one dimension in the nano range. More specifically, nanomaterials are defined as objects with dimensions that range from 1 to 100 nm, which give rise to interesting properties. In particular, silver and titanium nanoparticles (AgNPs and TiNPs, respectively) are known for their biological and biomedical properties and are often used in consumer products such as cosmetics, food additives, kitchen utensils, and toys. This situation has increased environmental and occupational exposure to AgNPs and TiNPs, which has placed demand for the risk assessment of NPs. Indeed, the same properties that make nanomaterials so attractive could also prove deleterious to biological systems. Of particular concern is the effect of NPs on mitochondria because these organelles play an essential role in cellular homeostasis. In this scenario, this work aimed to study how AgNPs and TiNPs interact with the mitochondrial respiration chain and to analyze how this interaction interferes in the bioenergetics and oxidative state of the organelles after sub-chronic exposure. Mitochondria were exposed to the NPs by gavage treatment for 21 days to check whether co-exposure of the organelles to the two types of NPs elicited any mitochondrion-NP interaction. More specifically, male Wistar rats were randomly assigned to four groups. Groups I, II, III, and IV received mineral oil, TiNPs (100 μg/kg/day), AgNPs (100 μg/kg/day), and TiNPs + AgNPs (100 μg/kg/day), respectively, by gavage. The liver was immediately removed, and the mitochondria were isolated and used within 3 h. Exposure of mitochondria to TiNPs + AgNPs lowered the respiratory control ratio, causing an uncoupling effect in the oxidative phosphorylation system. Moreover, both types of NPs induced mitochondrial swelling. Extended exposure of mitochondria to the NPs maintained increased ROS levels and depleted the endogenous antioxidant system. The AgNPs and TiNPs acted synergistically-the intensity of the toxic effect on the mitochondrial redox state was more significant in the presence of both types of NPs. These findings imply that the action of the NPs on mitochondria underlie NP toxicity, so future application of NPs requires special attention.

Effect of sleeved ceramic femoral heads on titanium ion release

INTRODUCTION

Metal ion release from wear and corrosion at the femoral head-stem taper junction can evoke local adverse reactions to metal debris (ARMD). In a specific large-diameter head (LDH) total hip arthroplasty (THA) system, ceramic femoral heads of 44 to 48 mm are available with a titanium (Ti) adaptor sleeve, while heads of 36- to 40-mm come without sleeves. The hypothesis of this study is that the Ti adaptor sleeve with LDH ceramic-on-ceramic (CoC) bearings will not cause wear or corrosion at the taper junction and, thus, will not generate high whole blood Ti ion levels.

METHODS

We compared whole blood Ti levels at minimum 1-year follow-up in 27 patients with unilateral primary LDH CoC THA with head sizes ranging from 36 to 48 mm using a Ti stem and acetabular component.

RESULTS

Although Ti ion levels in patients with 36- to 40-mm head diameters without Ti sleeve were found to be statistically significantly higher (2.3 μg/l: 1.6-3.1, SD 0.44) compared to those with a Ti sleeve (1.9 μg/l: 1.6-2.2, SD 0.19) (p = 0.020), the found difference has no clinical importance. No patients presented clinical signs of ARMD, and the clinical results in both groups were similar.

CONCLUSIONS

LDH CoC THA Ti levels were low and probably related to unavoidable passive corrosion of implant surfaces. Measurement of Ti in subjects with ceramic LDH, with or without Ti adaptor sleeve, did not disclose undirected signs of trunnionosis.

In vitro comparative cytotoxicity study of aminated polystyrene, zinc oxide and silver nanoparticles on a cervical cancer cell line

Nanoparticles use in nano-biotechnology applications have increased significantly with Aminated polystyrene amine (AmPs NP), Zinc oxide (ZnO NP), and Silver (Ag NP) nanoparticles utilized in wide variety of consumer products. This has presented a number of concerns due to their increased exposure risks and associated toxicity on living systems. Changes in the structural and physicochemical properties of nanoparticles can lead to changes in biological activities. This study investigates, compares, and contrasts the potential toxicity of AmPs, ZnO and Ag NPs on an in vitro model (HeLa cells) and assesses the associated mechanism for their corresponding cytotoxicity relative to the surface material. It was noted that NPs exposure attributed to the reduction in cell viability and high-level induction of oxidative stress. All three test particles were noted to induce ROS to varying degrees which is irrespective of the attached surface group. Cell cycle analysis indicated a G2/M phase cell arrest, with the corresponding reduction in G0/G1 and S phase cells resulting in caspase-mediated apoptotic cell death. These findings suggest that all three NPs resulted in the decrease in cell viability, increase intracellular ROS production, induce cell cycle arrest at the G2/M phase and finally result in cell death by caspase-mediated apoptosis, which is irrespective of their differences in physiochemical properties and attached surface groups.

Local Intratracheal Delivery of Perfluorocarbon Nanoparticles to Lung Cancer Demonstrated with Magnetic Resonance Multimodal Imaging

Eighty percent of lung cancers originate as subtle premalignant changes in the airway mucosal epithelial layer of bronchi and alveoli, which evolve and penetrate deeper into the parenchyma. Liquid-ventilation, with perfluorocarbons (PFC) was first demonstrated in rodents in 1966 then subsequently applied as lipid-encapsulated PFC emulsions to improve pulmonary function in neonatal infants suffering with respiratory distress syndrome in 1996. Subsequently, PFC nanoparticles (NP) were extensively studied as intravenous (IV) vascular-constrained nanotechnologies for diagnostic imaging and targeted drug delivery applications.

Methods: This proof-of-concept study compared intratumoral localization of fluorescent paramagnetic (M) PFC NP in the Vx2 rabbit model using proton (¹H) and fluorine (¹⁹F) magnetic resonance (MR) imaging (3T) following intratracheal (IT) or IV administration. MRI results were corroborated by fluorescence microscopy.

Results: Dynamic ¹H-MR and ¹⁹F-MR images (3T) obtained over 72 h demonstrated marked and progressive accumulation of M-PFC NP within primary lung Vx2 tumors during the first 12 h post IT administration. Marked ¹H and ¹⁹F MR signal persisted for over 72 h. In contradistinction, IV M-PFC NP produced a modest transient signal during the initial 2 h post-injection that was consistent circumferential blood pool tumor enhancement. Fluorescence microscopy of excised tumors corroborated the MR results and revealed enormous intratumor NP deposition on day 3 after IT but not IV treatment. Rhodamine-phospholipid incorporated into the PFC nanoparticle surfactant was distributed widely within the tumor on day 3, which is consistent with a hemifusion-based contact drug delivery mechanism previously reported. Fluorescence microscopy also revealed similar high concentrations of M-PFC NP given IT for metastatic Vx2 lung tumors. Biodistribution studies in mice revealed that M-PFC NP given IV distributed into the reticuloendothelial organs, whereas, the same dosage given IT was basically not detected beyond the lung itself. PFC NP given IT did not impact rabbit behavior or impair respiratory function. PFC NP effects on cells in culture were negligible and when given IV or IT no changes in rabbit hematology nor serum clinical chemistry parameters were measured.

Conclusion: IT delivery of PFC NP offered unique opportunity to locally deliver PFC NP in high concentrations into lung cancers with minimal extratumor systemic exposure.

Effect of titanium dioxide nanoparticles (TiO2 NPs) on the expression of mucin genes in human airway epithelial cells

OBJECTIVE

Titanium dioxide nanoparticles (TiO₂ NPs) are utilized with growing frequency for a wide variety of industrial applications. Recently, acute and chronic exposures to TiO₂ NPs have been found to induce inflammatory response in the human respiratory tract. However, the effect and mechanism underlying the induction of major airway mucins by TiO₂ NPs have not been elucidated. This study was conducted to characterize the effect of TiO₂ NPs, and the mechanism involved, on the expressions of airway mucins in human airway epithelial cells.

MATERIALS AND METHODS

In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effects of TiO₂ NPs and signaling pathway for airway mucin genes were investigated by reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassays and immunoblot analysis using several specific inhibitors and small interfering RNAs (siRNAs).

RESULTS

TiO₂ NPs increased MUC5B expression and activated the phosphorylations of extracellular signal-related kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). U0126 (an ERK1/2 MAPK inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited TiO₂ NPs-induced MUC5B expression. And knockdown of ERK1, ERK2 and p38 MAPK using siRNAs significantly blocked TiO₂ NPs-induced MUC5B mRNA expression. Furthermore, Toll-like receptor 4 (TLR4) mRNA expression was increased by TiO₂ NPs, and knockdown by TLR4 siRNA significantly attenuated TiO₂ NPs-induced MUC5B mRNA expression and the TiO₂ NPs-induced phosphorylations of ERK1/2 and p38 MAPK.

DISCUSSION AND CONCLUSIONS

These results demonstrate for the first time that TiO₂ NPs induce MUC5B expression via TLR4-dependent ERK1/2 and p38 MAPK signaling pathways in respiratory epithelium.

Cytotoxicity assessment, inflammatory properties, and cellular uptake of Neutraplex lipid-based nanoparticles in THP-1 monocyte-derived macrophages

Current antiretroviral drugs used to prevent or treat human immunodeficiency virus type 1 (HIV-1) infection are not able to eliminate the virus within tissues or cells where HIV establishes reservoirs. Hence, there is an urgent need to develop targeted delivery systems to enhance drug concentrations in these viral sanctuary sites. Macrophages are key players in HIV infection and contribute significantly to the cellular reservoirs of HIV because the virus can survive for prolonged periods in these cells. In the present work, we investigated the potential of the lipid-based Neutraplex nanosystem to deliver anti-HIV therapeutics in human macrophages using the human monocyte/macrophage cell line THP-1. Neutraplex nanoparticles as well as cationic and anionic Neutraplex nanolipoplexes (Neutraplex/small interfering RNA) were prepared and characterized by dynamic light scattering. Neutraplex nanoparticles showed low cytotoxicity in CellTiter-Blue reduction and lactate dehydrogenase release assays and were not found to have pro-inflammatory effects. In addition, confocal studies showed that the Neutraplex nanoparticles and nanolipoplexes are rapidly internalized into THP-1 macrophages and that they can escape the late endosome/lysosome compartment allowing the delivery of small interfering RNAs in the cytoplasm. Furthermore, HIV replication was inhibited in the in vitro TZM-bl infectivity assay when small interfering RNAs targeting CXCR4 co-receptor was delivered by Neutraplex nanoparticles compared to a random small interfering RNA sequence. This study demonstrates that the Neutraplex nanosystem has potential for further development as a delivery strategy to efficiently and safely enhance the transport of therapeutic molecules into human monocyte-derived macrophages in the aim of targeting HIV-1 in this cellular reservoir.

Exacerbation of Ventilation-Induced Lung Injury and Inflammation in Preterm Lambs by High-Dose Nanoparticles

Mechanical ventilation of preterm neonates causes lung inflammation and injury, with potential life-long consequences. Inert 50-nm polystyrene nanoparticles (PS50G) reduce allergic inflammation in the lungs of adult mice. We aimed to confirm the anti-inflammatory effects of PS50G in a sheep asthma model, and investigate the effects of prophylactic administration of PS50G on ventilation-induced lung injury (VILI) in preterm lambs. We assessed lung inflammatory cell infiltration, with and without PS50G, after airway allergen challenge in ewes sensitised to house dust mite. Preterm lambs (0.83 gestation) were delivered by caesarean section for immediate tissue collection (n = 5) or ventilation either with (n = 6) or without (n = 5) prophylactic intra-tracheal administration of PS50G nanoparticles (3% in 2 ml). Ventilation was continued for a total of 2 h before tissue collection for histological and biomolecular assessment of lung injury and inflammation. In ewes with experimental asthma, PS50G decreased eosinophilic infiltration of the lungs. Ventilated preterm lambs showed molecular and histological signs of lung injury and inflammation, which were exacerbated in lambs that received PSG50G. PS50G treatment decreased established inflammation in the lungs of asthmatic sheep. However, prophylactic administration of PSG50 exacerbated ventilation-induced lung injury and lung inflammation in preterm lambs.

WITHDRAWN: Titanium dioxide nanoparticles induce human eosinophil adhesion onto endothelial EA.hy926 cells via activation of phosphoinositide 3-kinase/Akt cell signalling pathway

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Redox-active nanomaterials for nanomedicine applications

Nanomedicine utilizes the remarkable properties of nanomaterials for the diagnosis, treatment, and prevention of disease. Many of these nanomaterials have been shown to have robust antioxidative properties, potentially functioning as strong scavengers of reactive oxygen species. Conversely, several nanomaterials have also been shown to promote the generation of reactive oxygen species, which may precipitate the onset of oxidative stress, a state that is thought to contribute to the development of a variety of adverse conditions. As such, the impacts of nanomaterials on biological entities are often associated with and influenced by their specific redox properties. In this review, we overview several classes of nanomaterials that have been or projected to be used across a wide range of biomedical applications, with discussion focusing on their unique redox properties. Nanomaterials examined include iron, cerium, and titanium metal oxide nanoparticles, gold, silver, and selenium nanoparticles, and various nanoscale carbon allotropes such as graphene, carbon nanotubes, fullerenes, and their derivatives/variations. Principal topics of discussion include the chemical mechanisms by which the nanomaterials directly interact with biological entities and the biological cascades that are thus indirectly impacted. Selected case studies highlighting the redox properties of nanomaterials and how they affect biological responses are used to exemplify the biologically-relevant redox mechanisms for each of the described nanomaterials.

New perspectives in nanotherapeutics for chronic respiratory diseases

According to the World Health Organization (WHO), hundreds of millions of people of all ages and in all countries suffer from chronic respiratory diseases, with particular negative consequences such as poor health-related quality of life, impaired work productivity, and limitations in the activities of daily living. Chronic obstructive pulmonary disease, asthma, occupational lung diseases (such as silicosis), cystic fibrosis, and pulmonary arterial hypertension are the most common of these diseases, and none of them are curable with current therapies. The advent of nanotechnology holds great therapeutic promise for respiratory conditions, because non-viral vectors are able to overcome the mucus and lung remodeling barriers, increasing pharmacologic and therapeutic potency. It has been demonstrated that the extent of pulmonary nanoparticle uptake depends not only on the physical and chemical features of nanoparticles themselves, but also on the health status of the organism; thus, the huge diversity in nanotechnology could revolutionize medicine, but safety assessment is a challenging task. Within this context, the present review discusses some of the major new perspectives in nanotherapeutics for lung disease and highlights some of the most recent studies in the field.

Engineered nanoparticles of titanium dioxide (TIO2): Uptake and biological effects in a sea bass cell line

With the rapid development of nanotechnology there has been a corresponding increase in the application of titanium dioxide nanoparticles (TiO₂-NPs) in various consumer and industrial products, consequently their potential health hazards and environmental effects are considered an aspect of great concern. In the present study, in order to assess the impact of TiO₂-NPs in the marine environment, the biological effects of TiO₂-NPs on a sea bass cell line (DLEC) were investigated. Cells were exposed for 24 h to different concentrations of TiO₂-NPs (1, 8, 40, 200 and 1000 μg/ml) or co-exposed with CdCl₂ (Cd). The effects of UV light irradiation were also investigated in cells treated with TiO₂-NPs and/or Cd. The internalization of TiO₂-NPs and the morphological cell modifications induced by the treatments were examined by transmission and scanning electron microscopy, this latter coupled with energy dispersive X-ray spectroscopy (EDS) for particle element detection. In addition, the effects of controlled exposures were studied evaluating the cytotoxicity, the DNA damage and the expression of inflammatory genes. Our study indicates that TiO₂-NPs were localized on the cell surface mainly as agglomerates revealed by EDS analysis and that they were uptaken by the cells inducing morphological changes. Photoactivation of TiO₂-NPs and/or co-exposure with Cd affects ATP levels and it contributes to induce acute cellular toxicity in DLEC cells dependent on Ti concentration. The inflammatory potential and the DNA damage, this latter displayed through a caspase-3 independent apoptotic process, were also demonstrated. Overall our data suggest that the interaction of TiO₂-NPs with marine water contaminants, such as cadmium, and the UV irradiation, may be an additional threat to marine organisms.

Nano-TiO2 penetration of oral mucosa: in vitro analysis using 3D organotypic human buccal mucosa models

BACKGROUND

Oral cavity is a doorway for a variety of products containing titanium dioxide (TiO2 ) nanoparticles (NPs) (nano-TiO2 ) such as food additives, oral healthcare products and dental materials. Their potential to penetrate and affect normal human oral mucosa is not yet determined.

OBJECTIVES

To evaluate the ability of nano-TiO2 to penetrate the in vitro reconstructed normal human buccal mucosa (RNHBM).

METHODS

RNHBM was generated from primary normal human oral keratinocytes and fibroblasts isolated from buccal oral mucosa of healthy patients (n = 6). The reconstructed tissues were exposed after 10 days to clinically relevant concentrations of spherical or spindle rutile nano-TiO2 in suspension for short (20 min) and longer time (24 h). Ultrahigh-resolution imaging (URI) microscopy (CytoViva™ , Auburn, AL, USA) was used to assess the depth of penetration into reconstructed tissues.

RESULTS

Ultrahigh-resolution imaging microscopy demonstrated the presence of nano-TiO2 mostly in the epithelium of RNHBM at both 20 min and 24-h exposure, and this was shape and doze dependent at 24 h of exposure. The depth of penetration diminished in time at higher concentrations. The exposed epithelium showed increased desquamation but preserved thickness.

CONCLUSION

Nano-TiO2 is able to penetrate RNHBM and to activate its barrier function in a doze- and time-dependent manner.

Anodically Grown Titania Nanotube Induced Cytotoxicity has Genotoxic Origins

Nanoarchitectures of titania (TiO₂) have been widely investigated for a number of medical applications including implants and drug delivery. Although titania is extensively used in the food, drug and cosmetic industries, biocompatibility of nanoscale titania is still under careful scrutiny due to the conflicting reports on its interaction with cellular matter. For an accurate insight, we performed in vitro studies on the response of human dermal fibroblast cells toward pristine titania nanotubes fabricated by anodic oxidation. The nanotubes at low concentrations were seen to induce toxicity to the cells, whereas at higher concentrations the cell vitality remained on par with controls. Further investigations revealed an increase in the G₀ phase cell population depicting that majority of cells were in the resting rather than active phase. Though the mitochondrial set-up did not exhibit any signs of stress, significantly enhanced reactive oxygen species production in the nuclear compartment was noted. The TiO₂ nanotubes were believed to have gained access to the nuclear machinery and caused increased stress leading to genotoxicity. This interesting property of the nanotubes could be utilized to kill cancer cells, especially if the nanotubes are functionalized for a specific target, thus eliminating the need for any chemotherapeutic agents.

Titanium dioxide nanoparticles induce size-dependent cytotoxicity and genomic DNA hypomethylation in human respiratory cells

Titanium dioxide nanoparticles induce size-dependent cytotoxicity and genomic DNA hypomethylation in human respiratory cells.

Activation of human AML14.3D10 eosinophils by nanoparticles: Modulatory activity on apoptosis and cytokine production

Eosinophilic inflammation is frequently observed in response to nanoparticle (NP) exposure in airway rodent models of allergies where the number of eosinophils is increased in lungs. Despite this, it is surprising that the potential cytotoxic effect of NP, as well as their direct role on eosinophils is poorly documented. The present study investigated how different NP can alter the biology of the human eosinophilic cell line AML14.3D10. It was found that among NP forms of CeO2, ZnO, TiO2, and nanosilver of 20 nm (AgNP20) or 70 nm (AgNP70) diameters, only ZnO and AgNP20 induced apoptosis. Caspases-7 and -9 were not activated by the tested NP while caspase-3 was activated by AgNP20 only. However, both ZnO and AgNP20 induced cytoskeletal breakdown as evidenced by the cleavage of lamin B1. Using an ELISArray approach for the simultaneous detection of several analytes (cytokines/chemokines), it was found that only ZnO and AgNP20 increased the production of different analytes including the potent pro-inflammatory CXCL8 (IL-8) chemokine. From the data here, we conclude that toxic effects of some NP could be observed in human eosinophil-like cells and that this could be related, at least partially, by induction of apoptosis and production of cytokines and chemokines involved in inflammation. The results of this study also indicate that distinct NP do not activate similarly human eosinophils, since ZnO and AgNP20 induce apoptosis and cytokine production while others such as TiO2, CeO2, and AgNP70 do not.

Advanced Therapeutic Strategies for Chronic Lung Disease Using Nanoparticle-Based Drug Delivery

Chronic lung diseases include a variety of obstinate and fatal diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF), and lung cancers. Pharmacotherapy is important for the treatment of chronic lung diseases, and current progress in nanoparticles offers great potential as an advanced strategy for drug delivery. Based on their biophysical properties, nanoparticles have shown improved pharmacokinetics of therapeutics and controlled drug delivery, gaining great attention. Herein, we will review the nanoparticle-based drug delivery system for the treatment of chronic lung diseases. Various types of nanoparticles will be introduced, and recent innovative efforts to utilize the nanoparticles as novel drug carriers for the effective treatment of chronic lung diseases will also be discussed.