Amorphous nanosilica induce endocytosis-dependent ROS generation and DNA damage in human keratinocytes

Background

The alveolar macrophage (AM) - first line of innate immune defence against pathogens and environmental irritants - constitutively expresses peroxisome-proliferator activated receptor γ (PPARγ). PPARγ ligand-induced activation keeps the AM quiescent, and thereby contributes to combat invaders and resolve inflammation by augmenting the phagocytosis of apoptotic neutrophils and inhibiting an excessive expression of inflammatory genes. Because of these presumed anti-inflammatory functions of PPARγ we tested the hypothesis, whether reduced functional receptor availability in mutant mice resulted in increased cellular and molecular inflammatory response during acute inflammation and/or in an impairment of its resolution.

Methods

To address this hypothesis we examined the effects of a carbon-nanoparticle (CNP) lung challenge, as surrogate for non-infectious environmental irritants, in a murine model carrying a dominant-negative point mutation in the ligand-binding domain of PPARγ (P465L/wt). Animals were instilled intratracheally with Printex 90 CNPs and bronchoalveolar lavage (BAL) was gained 24 h or 72 h after instillation to investigate its cellular and protein composition.

Results

Higher BAL cell numbers - due to higher macrophage counts - were found in mutants irrespective of treatment. Neutrophil numbers in contrast were slightly lower in mutants. Intratracheal CNP instillation resulted in a profound recruitment of inflammatory neutrophils into the alveolus, but genotype related differences at acute inflammation (24 h) and resolution (72 h) were not observed. There were no signs for increased alveolar-capillary membrane damage or necrotic cell death in mutants as determined by BAL protein and lactate-dehydrogenase content. Pro-inflammatory macrophage-derived cytokine osteopontin was higher, but galectin-3 lower in female mutants. CXCL5 and lipocalin-2 markers, attributed to epithelial cell stimulation did not differ.

Conclusions

Despite general genotype-related differences, we had to reject our hypothesis of an increased CNP induced lung inflammation and an impairment of its resolution in PPARγ defective mice. Although earlier studies showed ligand-induced activation of nuclear receptor PPARγ to promote resolution of lung inflammation, its reduced activity did not provide signs of resolution impairment in the settings investigated here.     

Titanium dioxide nanoparticles induce oxidative stress and DNA-adduct formation but not DNA-breakage in human lung cells

Titanium dioxide (TiO₂), also known as titanium (IV) oxide or anatase, is the naturally occurring oxide of titanium. It is also one of the most commercially used form. To date, no parameter has been set for the average ambient air concentration of TiO₂ nanoparticles (NP) by any regulatory agency. Previously conducted studies had established these nanoparticles to be mainly non-cyto- and -genotoxic, although they had been found to generate free radicals both acellularly (specially through photocatalytic activity) and intracellularly. The present study determines the role of TiO₂-NP (anatase, ∅ < 100 nm) using several parameters such as cyto- and genotoxicity, DNA-adduct formation and generation of free radicals following its uptake by human lung cells in vitro. For comparison, iron containing nanoparticles (hematite, Fe₂O₃, ∅ < 100 nm) were used. The results of this study showed that both types of NP were located in the cytosol near the nucleus. No particles were found inside the nucleus, in mitochondria or ribosomes. Human lung fibroblasts (IMR-90) were more sensitive regarding cyto- and genotoxic effects caused by the NP than human bronchial epithelial cells (BEAS-2B). In contrast to hematite NP, TiO₂-NP did not induce DNA-breakage measured by the Comet-assay in both cell types. Generation of reactive oxygen species (ROS) was measured acellularly (without any photocatalytic activity) as well as intracellularly for both types of particles, however, the iron-containing NP needed special reducing conditions before pronounced radical generation. A high level of DNA adduct formation (8-OHdG) was observed in IMR-90 cells exposed to TiO₂-NP, but not in cells exposed to hematite NP. Our study demonstrates different modes of action for TiO₂- and Fe₂O₃-NP. Whereas TiO₂-NP were able to generate elevated amounts of free radicals, which induced indirect genotoxicity mainly by DNA-adduct formation, Fe₂O₃-NP were clastogenic (induction of DNA-breakage) and required reducing conditions for radical formation.     

Silica nanoparticles induce neurodegeneration-like changes in behavior,neuropathology, and affect synapse through MAPK activation

Background

Silica nanoparticles (SiO₂-NPs) are naturally enriched and broadly utilized in the manufacturing industry. While previous studies have demonstrated toxicity in neuronal cell lines after SiO₂-NPs exposure, the role of SiO₂-NPs in neurodegeneration is largely unknown. Here, we evaluated the effects of SiO₂-NPs-exposure on behavior, neuropathology, and synapse in young adult mice and primary cortical neuron cultures.

Results

Male C57BL/6 N mice (3 months old) were exposed to either vehicle (sterile PBS) or fluorescein isothiocyanate (FITC)-tagged SiO₂-NPs (NP) using intranasal instillation. Behavioral tests were performed after 1 and 2 months of exposure. We observed decreased social activity at both time points as well as anxiety and cognitive impairment after 2 months in the NP-exposed mice. NP deposition was primarily detected in the medial prefrontal cortex and the hippocampus. Neurodegeneration-like pathological changes, including reduced Nissl staining, increased tau phosphorylation, and neuroinflammation, were also present in the brains of NP-exposed mice. Furthermore, we observed NP-induced impairment in exocytosis along with decreased synapsin I and increased synaptophysin expression in the synaptosome fractions isolated from the frontal cortex as well as primary neuronal cultures. Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) were also activated in the frontal cortex of NP-exposed mice. Moreover, inhibition of ERK activation prevented NP-mediated changes in exocytosis in cultured neurons, highlighting a key role in the changes induced by NP exposure.

Conclusions

Intranasal instillation of SiO₂-NPs results in mood dysfunction and cognitive impairment in young adult mice and causes neurodegeneration-like pathology and synaptic changes via ERK activation.

     

NanoTIO2 (UV-Titan) does not induce ESTR mutations in the germline of prenatally exposed female mice

Background

Particulate air pollution has been linked to an increased risk of cardiovascular disease and cancer. Animal studies have shown that inhalation of air particulates induces mutations in the male germline. Expanded simple tandem repeat (ESTR) loci in mice are sensitive markers of mutagenic effects on male germ cells resulting from environmental exposures; however, female germ cells have received little attention. Oocytes may be vulnerable during stages of active cell division (e.g., during fetal development). Accordingly, an increase in germline ESTR mutations in female mice prenatally exposed to radiation has previously been reported. Here we investigate the effects of nanoparticles on the female germline. Since pulmonary exposure to nanosized titanium dioxide (nanoTiO₂) produces a long-lasting inflammatory response in mice, it was chosen for the present study.

Findings

Pregnant C57BL/6 mice were exposed by whole-body inhalation to the nanoTiO₂ UV-Titan L181 (~42.4?mg UV-Titan/m³) or filtered clean air on gestation days (GD) 8?C18. Female C57BL/6?F1 offspring were raised to maturity and mated with unexposed CBA males. The F2 descendents were collected and ESTR germline mutation rates in this generation were estimated from full pedigrees (mother, father, offspring) of F1 female mice (192 UV-Titan-exposed F2 offspring and 164?F2 controls). ESTR mutation rates of 0.029 (maternal allele) and 0.047 (paternal allele) in UV-Titan-exposed F2 offspring were not statistically different from those of F2 controls: 0.037 (maternal allele) and 0.061 (paternal allele).

Conclusions

We found no evidence for increased ESTR mutation rates in F1 females exposed in utero to UV-Titan nanoparticles from GD8-18 relative to control females.     

Mechanisms of action of inhaled fibers, particles and nanoparticles in lung and cardiovascular diseases

Background  

A symposium on the mechanisms of action of inhaled airborne particulate matter (PM), pathogenic particles and fibers such as silica and asbestos, and nanomaterials, defined as synthetic particles or fibers less than 100 nm in diameter, was held on October 27 and 28, 2005, at the Environmental Protection Agency (EPA) Conference Center in Research Triangle Park, North Carolina. The meeting was the eighth in a series of transatlantic conferences first held in Penarth, Wales, at the Medical Research Council Pneumoconiosis Unit (1979), that have fostered long-standing collaborations between researchers in the fields of mineralogy, cell and molecular biology, pathology, toxicology, and environmental/occupational health.     

Mechanisms of action of inhaled fibers, particles and nanoparticles in lung and cardiovascular diseases

Nanotechnology is the new industrial revolution of the 21st Century as the various processes lead to radical improvements in medicine, manufacturing, energy production, land remediation, information technology and many other everyday products and applications. With this revolution however, there are undoubted concerns for health, safety and the environment which arise from the unique nature of materials and processes at the nanometre scale. The in vitro assays used in the screening strategy are all validated, internationally accepted protocols and provide a useful indication of potential toxicity of a chemical as a result of effects on various toxicological endpoints such as local site of contact (dermal) irritation, general cytotoxicity and mutagenicity. The initial in vitro screening strategy described in this paper to investigate the potential health implications, if any, which may arise following exposure to one specific application of nanoparticulate cerium oxide used as a diesel fuel borne catalyst, reflects a precautionary approach and the results will inform judgement on how best to proceed to ensure safe use.     

Acute and chronic nephrotoxicity of platinum nanoparticles in mice

Platinum nanoparticles are being utilized in various industrial applications, including in catalysis, cosmetics, and dietary supplements. Although reducing the size of the nanoparticles improves the physicochemical properties and provides useful performance characteristics, the safety of the material remains a major concern. The aim of the present study was to evaluate the biological effects of platinum particles less than 1 nm in size (snPt1). In mice administered with a single intravenous dose of snPt1, histological analysis revealed necrosis of tubular epithelial cells and urinary casts in the kidney, without obvious toxic effects in the lung, spleen, and heart. These mice exhibited dose-dependent elevation of blood urea nitrogen, an indicator of kidney damage. Direct application of snPt1 to in vitro cultures of renal cells induced significant cytotoxicity. In mice administered for 4 weeks with twice-weekly intraperitoneal snPt1, histological analysis of the kidney revealed urinary casts, tubular atrophy, and inflammatory cell accumulation. Notably, these toxic effects were not observed in mice injected with 8-nm platinum particles, either by single- or multiple-dose administration. Our findings suggest that exposure to platinum particles of less than 1 nm in size may induce nephrotoxicity and disrupt some kidney functions. However, this toxicity may be reduced by increasing the nanoparticle size.     

Carboplatin liposomal nanoparticles: Preparation,characterization, and cytotoxicity effects on lung cancer in vitro environment

The study aimed to encapsulate anticancer drug carboplatin into liposomal nanoparticles by reverse-phase evaporation technique and evaluate its efficacy on lung cancer in vitro environment. Nanoparticles were characterized in terms of size, drug loading efficiency, drug retention capability, and cytotoxicity effects. Nanoscale particles with 67% drug encapsulation efficiency were prepared. Also, high retention capability (drug release equal to 25% after 72?h) of the nanodrug was confirmed. In addition, results of the nanodrug cytotoxicity indicated nanoparticles increased potency of the drug by approximately 90%. Findings of the study indicated liposome can be used for carboplatin delivery to lung cancer.     

Electrochemical detection of in situ DNA damage with layer-by-layer films containing DNA and glucose oxidase and protection effect of catalase layers against DNA damage

Natural double-stranded DNA and the enzyme glucose oxidase (GOD) were assembled into layer-by-layer films on electrode surface. In the presence of glucose and Fe²⁺ in incubation solutions, GOD in the films could catalyze the reaction of glucose and O₂, and the produced H₂O₂ would further react with Fe²⁺, generating hydroxyl radical (OH) as in the Fenton reaction, which could severely damage DNA in the films. The electrocatalytic oxidation of DNA guanines by (bpy = 2,2′-bipyridine) produced by electrooxidation of at the electrodes was used to detect DNA damage induced by the in situ Fenton reaction. The additional catalase (Cat) layers assembled into the films could effectively protect the DNA from damage by decomposing the H₂O₂ produced in situ, and only when the Cat layers were located in close proximity to the GOD layers, the protection of DNA in the inner layers was most effective. The present work provides an in vitro model system to mimic the real bioprocess in DNA damage and protection through a simple electrochemical approach combined with layer-by-layer assembly.     

Gold nanoparticles induce cytotoxicity in the alveolar type-II cell lines A549 and NCIH441

Background  

During the last years engineered nanoparticles (NPs) have been extensively used in different technologies and consequently many questions have arisen about the risk and the impact on human health following exposure to nanoparticles. Nevertheless, at present knowledge about the cytotoxicity induced by NPs is still largely incomplete. In this context, we have investigated the cytotoxicity induced by gold nanoparticles (AuNPs), which differed in size and purification grade (presence or absence of sodium citrate residues on the particle surface) in vitro, in the human alveolar type-II (ATII)-like cell lines A549 and NCIH441.     

磁性纳米颗粒的功能化及其在DNA提取中的应用

提出了一种应用功能化的磁性纳米颗粒进行DNA提取的新方法．该方法首先通过3-氨丙基三乙氧基硅烷（APTES）在纳米颗粒表面修饰上氨基（-NH2）官能团,然后利用氨基化的磁性Fe3O4纳米粒子（NH2-MNPs）进行DNA提取。结果表明,利用100μgNH2-MNPs从200μL全血中提取的基因组DNA大于2．89μg,OD260／OD280比值介于1．78和1．82之间。     

Cobalt ferrite nanoparticles hosted in activated carbon from renewable sources as catalyst for methanol decomposition

High quality micro-mesoporous activated carbon was prepared from waste bio-mass (peach shells) and used as a host matrix of cobalt ferrite nanoparticles. The obtained materials were characterized by N₂ physisorption, XRD, FTIR and Moessbauer spectroscopy and tested as catalysts for hydrogen production from methanol. Depending on the Co/Fe ratio formation of pure CoFe₂O₄ or a mixture of CoO and ferrite phases were observed for carbon supported bi-component materials, while under the same condition the silica support provides the formation of non-stoichiometric ferrite phase. The catalytic active phase which is formed by the influence of the reaction medium represents a complex mixture of non-changed ferrite, magnetite, Co–Fe alloy and/or Fe₃C in different proportions.     

Cobalt Aluminate Formation in Alumina-Supported Cobalt Catalysts: Effects of Cobalt Reduction State and Water Vapor

The gas phase hydrodechlorination (HDC) of chlorobenzene (at 523 K) was studied over Ni/SiO₂ (prepared by precipitation-deposition and impregnation) and Ni-impregnated Al₂O₃, MgO, activated carbon and graphite; the Ni loading spanned the range 1.5-20.3% w/w. The activated catalysts (with and without precalcination) were characterized by TEM/H₂ chemisorption and the Ni particle size (distribution) is related to HDC activity. The levels of reversibly and irreversibly held Cl on the used catalysts were recorded: spent Ni/MgO bore the highest residual Cl. The reaction is structure sensitive, with an increase in specific HDC rate at higher (average) Ni particle sizes over the range 1.4–22.1 nm. The exception to this trend is Ni/graphite and (to a lesser extent) Ni/Al₂O₃, where Ni-support interactions are responsible for the lowering HDC activity.     

快速测定镍钴合金镀液中的镍和钴

采用分光光度法快速直接测定共存在镀液中常量和镍和钴。在７２０ｎｍ波长处测定镍时,钴不干扰。在５１０ｎｍ波长处测定钴时,镍对钴的吸光度的干扰值与镍量呈线性关系,因而采用扣除相应镍量所造成吸光度增加的方法消除镍对钴的干扰。     

DNA damage and cytotoxicity in type II lung epithelial (A549) cell cultures after exposure to diesel exhaust and urban street particles

Background  

Exposure to air pollution particles has been acknowledged to be associated with excess generation of oxidative damage to DNA in experimental model systems and humans. The use of standard reference material (SRM), such as SRM1650 and SRM2975, is advantageous because experiments can be reproduced independently, but exposure to such samples may not mimic the effects observed after exposure to authentic air pollution particles. This study was designed to compare the DNA oxidizing effects of authentic street particles with SRM1650 and SRM2975. The authentic street particles were collected at a traffic intensive road in Copenhagen, Denmark.