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Several difficulties hamper the toxicological evaluation of particulate substancesin vitro. One of the most serious difficulties is that most particles are insoluble in water, and easily agglomerate during the assay. Albumin and some detergents have been used to disperse the particles in the culture medium. However, effects of these additives on the cellular uptake of particles and the following biological consequences are unknown. The first event when phagocytic cells encounter particulate substances is an association of the plasma membrane with the particle surface. Macrophage receptor with collagenous structure (MARCO) has been identified as a receptor for environmental particles such as titanium dioxide (TiO2) and carbonaceous particles. However, it remained to be revealed how MARCO recognizes the unopsonized particles. While investigating the particle surface-cell membrane interaction using GFP-tagged MARCO-expressing cells, we found that cytosolic proteins were released from the cells and rapidly adsorbed on the surface of TiO2particles. The GFP-tagged MARCO-overexpressing cells were further engineered to express RFP-tagged LC3 (cytosolic protein) to visualize adsorption of proteins on the surface of titanium dioxide (TiO2) particles. We found that cytosolic proteins including LC3 were released in the culture medium from intact cells and adsorbed on the particle surface quickly in the cell culture system. These results indicate that MARCO probably recognizes adsorbed intracellular proteins rather than the uncoated inorganic surface of environmental particles.

Promyelocytic leukemia-nuclear bodies (PML-NBs) are dot-like protein assemblies and implicated in the pathogenesis of leukemia and viral infection. PML is the scaffold protein of PML-NB and its client proteins such as SUMO, DAXX, and Sp100 reside in PML-NBs. It is known that a short exposure to trivalent arsenic (As3+) induces the solubility change and the subsequent SUMOylation of PML, and the SUMO interacting motif (SIM) is not necessary for these biochemical changes. However, it has not been well studied how As3+initiates or enhances the association of SUMO with PML and the other PML-NB client proteins. Here, we report that As3+enhanced non-covalent association of PML with SUMO via the SUMO-SIM interaction which is dispensable for the solubility change and SUMOylation of PML. We also report that the As3+-induced solubility change of PML was not affected by ML792, a SUMO E1 enzyme inhibitor, even though the nuclear localization of SUMO2/3 and protein SUMOylation were halted by ML792. As3+did not change the solubility of DAXX and SUMOylation enzymes such as SAE1, UBA2, and UBC9. In contrast, As3+induced SUMOylation of Sp100 with a concomitant loss of its solubility like PML in human leukemia cell lines. Our current results indicate that both covalent and non-covalent associations of SUMO with PML are increased in As3+-exposed cells, and Sp100 may play a role in the maintenance of PML-NBs.

Arsenic is a well-known environmental carcinogen and chronic exposure to arsenic through drinking water has been reported to cause skin, bladder and lung cancers, with arsenic metabolites being implicated in the pathogenesis. In contrast, arsenic trioxide (As2O3) is an effective therapeutic agent for the treatment of acute promyelocytic leukemia, in which the binding of arsenite (iAsIII) to promyelocytic leukemia (PML) protein is the proposed initial step. These findings on the two-edged sword characteristics of arsenic suggest that after entry into cells, arsenic reaches the nucleus and triggers various nuclear events. Arsenic is reduced, conjugated with glutathione, and methylated in the cytosol. These biotransformations, including the production of reactive metabolic intermediates, appear to determine the intracellular dynamics, target organs, and biological functions of arsenic.

Promyelocytic leukemia (PML) nuclear bodies (PML-NBs), a class of membrane-less cellular organelles, participate in various biological activities. PML-NBs are known as the core-shell-type nuclear body, harboring ‘client’ proteins in their core. Although multiple membrane-less organelles work in the oocyte nucleus, PML-NBs have been predicted to be absent from oocytes. Here, we show that some well-known PML clients (but not endogenous PML) co-localized with small ubiquitin-related modifier (SUMO) protein in the nucleolus and peri-centromeric heterochromatin of maturing oocytes. In oocytes devoid of PML-NBs, endogenous PML protein localized in the vicinity of chromatin. During and after meiotic resumption, PML co-localized with SUMO gathering around chromosomes. To examine the benefit of the PML-NB-free intranuclear milieu in oocytes, we deliberately assembled PML-NBs by microinjecting human PML-encoding plasmids into oocytes. Under conditions of limited SUMO availability, assembled PML-NBs tended to cluster. Upon proteotoxic stress, SUMO delocalized from peri-centromeric heterochromatin and co-localized with SC35 (a marker of nuclear speckles)-positive large compartments, which was disturbed by pre-assembled PML-NBs. These observations suggest that the PML-NB-free intranuclear environment helps reserve SUMO for emergent responses by redirecting the flux of SUMO otherwise needed to maintain PML-NB dynamics.

Recent epidemiological studies have reported significantly increasing hospital admission rates for mental disorders such as anxiety and depression, not only in adults but also in children and adolescents, indicating more research is needed for evaluation of the etiology and possible reduction and prevention of these disorders. The aim of the present study was to examine the associations between perinatal exposure to traffic-related air pollutants and anxiety-like behaviors and alterations in neurological and immunological markers in adulthood using a rat model. Sprague Dawley pregnant rats were exposed to clean air (control), diesel exhaust (DE) 101 ± 9 μg/m3 or diesel exhaust origin secondary organic aerosol (DE-SOA) 118 ± 23 μg/m3 from gestational day 14 to postnatal day 21. Anxiety-related behavioral tests including open field tests, elevated plus maze, light/dark transition tests and novelty-induced hypophagia were performed on 10-week-old rats. The hippocampal expression of neurotransmitters, neurotrophic factors, and inflammatory molecular markers was examined by real-time RT-PCR. Anxiety-like behaviors were observed in both male and female rat offspring exposed to DE or DE-SOA. Moreover, serotonin receptor (5HT1A), dopamine receptor (Drd2), brain-derived neurotrophic factor and vascular endothelial growth factor A mRNAs were significantly decreased, whereas interleukin-1β, cyclooxygenase-2, heme oxygenase-1 mRNAs and microglial activation were significantly increased in both male and female rats. These findings indicate that brain developmental period exposure to traffic-related air pollutants may induce anxiety-like behaviors via modulation of neurotransmitters, neurotrophic factors, and immunological molecular markers, triggering neuroinflammation and microglia activation in rats.

Promyelocytic leukemia (PML) nuclear bodies (PML-NBs), a class of membrane-less organelles in cells, are involved in multiple biological activities and are present throughout cells of adult organisms. Although the oocyte nucleus is an active region for the flux of multiple non-membranous organelles, PML-NBs have been predicted to be absent from oocytes. Here, we show that the deliberate assembly of PML-NBs during oocyte growth preferentially sequestered Small Ubiquitin-related Modifier (SUMO) protein from the nucleoplasm. SUMO not only was involved in the regulation of oocyte nuclear maturation but also was committed to the response, mediated by liquid droplet formation, to multiple stressors including nucleolar stress and proteotoxic stresses. Exogenous assembly of PML-NBs in the nucleus of oocytes affected the efficiency of the response of SUMO. These observations suggest that the PML-NB-free intranuclear milieu ensures that a reserve of SUMO remains available for emergent responses in oocyte development. This work demonstrated a benefit of the PML-NB-free intranuclear milieu, namely the ability to redirect the flux of SUMO otherwise needed to control PML-NB dynamics.

The functional roles of protein modification by small ubiquitin-like modifier (SUMO) proteins are not well understood compared to ubiquitination. Promyelocytic leukemia (PML) proteins are good substrates for SUMOylation, and PML-nuclear bodies (PML-NBs) may function as a platform for the PML SUMOylation. PML proteins are rapidly modified both with SUMO2/3 and SUMO1 after exposure to arsenite (As

In the technological process of manufacturing, distribution and recycling of nanoparticles, is easy to spread them in the air. The respiratory system is the primary target for inhaled NPs. The authors discuss the influence of the complexing compounds used in the “button up” synthesis of inorganic nanoparticles, on the cells activity during in vitro studies. We decided to examine the impact of yttrium aluminum borates (YAB) nanoparticles doped with ytterbium ions synthesized from various polymeric precursors on the viability of human bronchial epithelial cells using the WST-8 assay, depending on the concentrations of these nanoparticles. The optically active YAB:Yb3+ nanoparticles were obtained by the sol–gel method. In our experiments three various hydrophilic polysaccharides and two different acids were used as polymeric complexing agents. Luminescent materials may be utilised in various fields, including medical diagnostic, however YAB:Yb3+ NPs are considered to be harmful or inert. We have tested those particles to determine the way their shape influences biological response. We show the effect of NPs suspension in biological media and their behavior under physiological conditions. In our work we demonstrate the influence of polymeric agents on the viability of bronchial cells, and consequently, on the probably inflammatory response. In the present study we report, that mannitol with citric acid favours the formation of fibrous particles while others polymeric agents, as salicylic acid with sorbitol favour spherical shape formation. Cellular responses to fibrous particles are different from these to spherical ones because bio-persistent fibers induce multiplication and possibility to obtain inflammasome. Particles in fiber form trigger the inflammation process, and thus can cause cell multiplication effect. We determined whether the polymeric precursors can have impact on the activation of the surface of NPs, and if they trigger interactions of NPs with cells. It turns out, that the issue of the toxicity of nanoparticles is very complex and should be approached comprehensively. Our results confirmed that stability, agglomeration, cytotoxicity of NPs and the multiplication of cells, depend on polymeric agents used in sol–gel synthesis. It had been shown that the method of nanoparticles synthesis has a significant impact on cellular viability and multiplication of cells. Preliminary studies on human bronchial cell demonstrated that the high viability and proliferation depends on the polymer precursors used in synthesis process. To describe the structure of the obtained NPs the following methods were used: Scanning Electron Microscopy, Transmission Electron Microscopy, Atomic Forces Microscopy, X-ray diffraction and Raman Spectroscopy.

Secondary organic aerosol (SOA) is a component of airborne particulate matter in urban areas. However, their toxicities remain incompletely understood. In this study, we investigated the oxidative and inflammatory potency of SOA derived from three different volatile organic compounds (α-pinene, m-xylene, and trimethylbenzene) using human bronchial epithelial cells (BEAS-2B) and macrophages (U937). In BEAS-2B cells, all types of SOA extracts increased the expression of the heme oxygenase 1 (HMOX1) and interleukin-8 (IL8) genes, a typical marker for oxidative stress and inflammatory responses, respectively. Among the three types of SOA, m-xylene-derived SOA showed the strongest induction of the HMOX1 and IL8 genes, and transcriptional activity via the antioxidant response element (ARE). A causal candidate for SOA induction of oxidative stress is 2,6-dimethyl-1,4-benzoquinone (DMBQ) because only this quinone compound increased the transcriptional activity via ARE among components tested in this study. Similar to the case of BEAS-2B cells, SOA extracts increased the expression of HMOX1 and IL8 genes in U937 cells, mainly through oxidative stress, but these responses in U937 cells were prolonged when compared with BEAS-2B cells. Together, these results show that SOA affects lung epithelial cells and macrophages mainly through oxidative stress and inflammation, suggesting their contribution to the development of respiratory diseases.

Paraquat (PQ) is one of the commonly used herbicides in the world, despite its high toxicity. The ingestion of PQ accidentally or intentionally causes severe damage in diverse organs including the lung. Pulmonary fibrosis triggered by PQ accumulation in the lung epithelial cells is one of the major causes of death. This study investigated the intracellular accumulation of PQ, reactive oxygen species (ROS) generation and mitochondrial injury using two lung epithelial cell lines A549 and BEAS-2B (BEAS). Although A549 exhibit greater resistance to oxidative stress than BEAS, a cytotoxicity assay for PQ demonstrated that EC50 for lethality in A549 was 7 times lower than that in BEAS. When exposed to PQ at a concentration around EC50 for lethality, the amount of ROS generated in A549 was as low as that in BEAS. Conversely, the cellular concentration of PQ in A549 after exposure was higher than that in BEAS, which suggests a distinct difference in the susceptibility to PQ between these cell lines. After a 16 h exposure to PQ, mitochondrial membrane potential (MMP) decreased in A549, but decreased only slightly in BEAS even following a 30 h exposure. PQ-exposed A549 reduced an accumulation of PTEN-induced kinase 1 (PINK1), which works in degradation of damaged mitochondria, following the decrease of MMP, whereas PQ did not decline the PINK1 in BEAS. These results suggest that mitochondrial dysfunction due to cellular accumulation of PQ might contribute to the PQ-provoked toxicity more than the ROS generation in the lung epithelial cells.

Promyelocytic leukemia (PML) proteins are involved in the pathogenesis of acute promyelocytic leukemia (APL). Trivalent arsenic (As3+) is known to cure APL by binding to cysteine residues of PML and enhance the degradation of PML-retinoic acid receptor α (RARα), a t(15;17) gene translocation product in APL cells, and restore PML-nuclear bodies (NBs). The size, number, and shape of PML-NBs vary among cell types and during cell division. However, topological changes of PML-NBs in As3+-exposed cells have not been well-documented. We report that As3+-induced solubility shift underlies rapid SUMOylation of PML and late agglomeration of PML-NBs. Most PML-NBs were toroidal and granular dot-like in GFPPML-transduced CHO-K1 and HEK293 cells, respectively. Exposure to As3+ and antimony (Sb3+) greatly reduced the solubility of PML and enhanced SUMOylation within 2 h in the absence of changes in the number and size of PML-NBs. However, the prolonged exposure to As3+ and Sb3+ resulted in agglomeration of PML-NBs. Exposure to bismuth (Bi3+), another Group 15 element, did not induce any of these changes. ML792, a SUMO activation inhibitor, reduced the number of PML-NBs and increased the size of the NBs, but had little effect on the As3+-induced solubility change of PML. These results warrant the importance of As3+- or Sb3+-induced solubility shift of PML for the regulation intranuclear dynamics of PML-NBs.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication, poor social interactions, and repetitive behaviors. We aimed to examine autism-like behaviors and related gene expressions in rats exposed to diesel exhaust (DE)-origin secondary organic aerosol (DE-SOA) perinatally. Sprague&ndash, Dawley pregnant rats were exposed to clean air (control), DE, and DE-SOA in the exposure chamber from gestational day 14 to postnatal day 21. Behavioral phenotypes of ASD were investigated in 10~13-week-old offspring using a three-chambered social behavior test, social dominance tube test, and marble burying test. Prefrontal cortex was collected to examine molecular analyses including neurological and immunological markers and glutamate concentration, using RT-PCR and ELISA methods. DE-SOA-exposed male and female rats showed poor sociability and social novelty preference, socially dominant behavior, and increased repetitive behavior. Serotonin receptor (5-HT(5B)) and brain-derived neurotrophic factor (BDNF) mRNAs were downregulated whereas interleukin 1 &beta, (IL-&beta, ) and heme oxygenase 1 (HO-1) mRNAs were upregulated in the prefrontal cortex of male and female rats exposed to DE-SOA. Glutamate concentration was also increased significantly in DE-SOA-exposed male and female rats. Our results indicate that perinatal exposure to DE-SOA may induce autism-like behavior by modulating molecules such as neurological and immunological markers in rats.

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor class-A protein that is expressed on the cell surface of macrophages. MARCO mediates binding and ingestion of unopsonized environmental particles, including nano-sized materials. Exosomes are cell-derived, nano-sized vesicles (40–150 nm) that can contain lipids, RNA, DNA, and various proteins. Exosomes play an essential role in cell-to-cell communication via body fluids. However, mechanisms for the recognition and internalization of exosomes by recipient cells remain poorly characterized. In this study, cellular association of serum-derived fluorescent exosomes and 20-nm fluorescent nanoparticles (positive control) was compared between MARCO-expressing (CHO-MARCO) and control (CHO-CT) CHO-K1 cells to examine whether MARCO expression by recipient cells mediates the cellular uptake of exosomes and environmental nanoparticles. Fluorescence microscopic studies and quantitative analyses revealed that the cellular associations of both exosomes and 20-nm nanoparticles were greater in CHO-MARCO cells than in CHO-CT cells. Exosomes and nanoparticles colocalized with green fluorescent protein (GFP)-MARCO in cells transfected with GFP-MARCO-encoding constructs . Furthermore, inhibitory studies showed that actin reorganization and dynamin are involved in the MARCO-mediated cellular internalization of exosomes. These results indicated that MARCO plays a role in the uptake of exosomes.

Background Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social communication, social interactions and repetitive behaviors. The etiology of autism remains unknown and its molecular basis is not well understood. Both genetic and environmental factors may contribute ASD. In this study, we used diesel exhaust origin secondary organic aerosol (DE-SOA) as environmental pollutants. The aim of present study is to examine autism-like behaviors and related gene expressions in rats exposed to DE-SOA perinatally. Sprague-Dawley pregnant rats were exposed to clean air (control), diesel exhaust (DE) and DE-SOA in the exposure chamber for 5 h per day, 5days a week from gestational day 8 to postnatal day 21. At postnatal day 21, the male and female offspring rats were allocated into three different groups as follows: 1) rats exposed to clean filtered air; 2) rats exposed to DE; 3) rats exposed to DE-SOA. Social behaviors were investigated at 10 ~ 13-weeks-old rats using a 3-chambered social behavior test, social dominance tube test and marble burying test. Prefrontal cortex was collected under deep anesthesia to examine neurological and immunological markers, glutamate concentration, mast cell and microglia activation using real-time RT-PCR method, ELISA method and immunohistochemical analysis. Results DE-SOA-exposed male and female rats showed poor sociability and social novelty preference, socially dominant behavior and increased repetitive behavior compared with the control rats. The mRNA expression levels of serotonin receptor (5-HT(5B)) and brain-derived neurotrophic factor (BDNF) were down-regulated whereas interleukin 1 β (IL-β), and heme oxygenase 1 (HO-1) were upregulated in the prefrontal cortex of male and female rats exposed to DE-SOA compared to the control rats. In addition, the expression of mast cells and microglia marker ionized calcium-binding adapter molecule (Iba)1 were increased in the prefrontal cortex of male and female rats exposed to DE-SOA. Glutamate concentration was increased significantly in the prefrontal cortex of both male and female rats exposed to DE-SOA. Conclusion Our results indicate that perinatal exposure to DE-SOA may induce autism-like behavior in rats by modulating neurological and immunological markers in the prefrontal cortex.

Holmium-doped monoclinic KGd(WO4)2 nanoparticles were synthesized by the mechano-chemical method. The structure and morphology of KGW:Ho 10 at.% nanopowders were investigated with the use of X-ray Powder Diffraction, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Emission and excitation spectra of KGW nanocrystals were also measured using a fluorometer with a xenon lamp and OPO laser source. The influence of nanoparticles of KGW doped with 10 at.% of holmium on the viability of J774.1 mouse BALB/c monocyte macrophage cells was tested by the WST8 assay. Preliminary immunity cell studies demonstrated a high viability of KGW:Ho 10 at%. Hence, these nanoparticles are promising for imaging applications. To characterize and quantify the physical stability of the nanoparticles of KGW:Ho 10 at.% suitable for biomedical applications, nanoparticles of KGW:Ho in the range of 80–200 nm were prepared.

The human health and environmental risk assessment of engineered nanomaterials (NPs) is nowadays of high interest. It is important to assess and predict the biological activity, toxicity, physicochemical properties, fate and transport of NPs. In this work, a combined experimental and computational study is performed in order to estimate the toxicity and develop a predictive model for heterogeneous NPs (i.e. modified NPs, created from more than one type of NPs). Quantitative structure–activity relationship (QSAR) methods have not been yet adopted for predicting the toxicity/physicochemical properties of modified heterogeneous nanoparticles (so-called heterogeneous NPs). Since the main problem for nano-QSAR/nano-QSPR modeling of heterogeneous NPs was a lack of appropriate descriptors that are able to express the specific characteristics of 2nd generation NPs, we developed here a novel approach. The novel approach to encode heterogeneous NPs is based on the idea of additive descriptors for mixture systems previously applied only to mixtures of organic/inorganic compounds. Thus, based on the proposed novel approach, we have performed experimental and theoretical studies to develop nano-QSAR models describing the cytotoxicity of 34 TiO2-based NPs modified by (poly)metallic clusters (Au, Ag, Pt) to the Chinese hamster ovary cell line. The models showed a good predictive ability and robustness. This approach can be used as an efficient tool for assessing the toxicity as well as physicochemical properties of unexplored heterogeneous NPs.

Titania-supported palladium, gold and bimetallic nanoparticles (second-generation nanoparticles) demonstrate promising photocatalytic properties. However, due to unusual reactivity, second-generation nanoparticles can be hazardous for living organisms. Considering the ever-growing number of new types of nanoparticles that can potentially contaminate the environment, a determination of their toxicity is extremely important. The main aim of presented study was to investigate the cytotoxic effect of surface modified TiO2-based nanoparticles, to model their quantitative nanostructure–toxicity relationships and to reveal the toxicity mechanism. In this context, toxicity tests for surface-modified TiO2-based nanoparticles were performed in vitro, using Gram-negative bacteria Escherichia coli and Chinese hamster ovary (CHO-K1) cells. The obtained cytotoxicity data were analyzed by means of computational methods (quantitative structure–activity relationships, QSAR approach). Based on a combined experimental and computational approach, predictive models were developed, and relationships between cytotoxicity, size, and specific surface area (Brunauer–Emmett–Teller surface, BET) of nanoparticles were discussed.

Yoshika Kurokawa,1 Hideko Sone,1 Tin-Tin Win-Shwe,1 Yang Zeng,1 Hiroyuki Kimura,2 Yosuke Koyama,1 Yusuke Yagi,2 Yasuto Matsui,3 Masashi Yamazaki,4 Seishiro Hirano1 1Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki, 2Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, 3Department of Environmental Engineering, Kyoto University Graduate School of Engineering, Kyoto, 4TIA Center Office, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan Abstract: Dendrimers have been expected as excellent nanodevices for brain medication. Anamine-terminated polyamidoamine dendrimer (PD), an unmodified plain type of PD, has the obvious disadvantage of cytotoxicity, but still serves as an attractive molecule because it easily adheres to the cell surface, facilitating easy cellular uptake. Single-photon emission computed tomographic imaging of a mouse following intravenous injection of a radiolabeled PD failed to reveal any signal in the intracranial region. Furthermore, examination of the permeability of PD particles across the blood–brain barrier (BBB) in vitro using a commercially available kit revealed poor permeability of the nanoparticles, which was suppressed by an inhibitor of caveolae-mediated endocytosis, but not by an inhibitor of macropinocytosis. Physicochemical analysis of the PD revealed that cationic PDs are likely to aggregate promptly upon mixing with body fluids and that this prompt aggregation is probably driven by non-Derjaguin–Landau–Verwey–Overbeek attractive forces originating from the surrounding divalent ions. Atomic force microscopy observation of a freshly cleaved mica plate soaked in dendrimer suspension (culture media) confirmed prompt aggregation. Our study revealed poor transfer of intravenously administered cationic PDs into the intracranial nervous tissue, and the results of our analysis suggested that this was largely attributable to the reduced BBB permeability arising from the propensity of the particles to promptly aggregate upon mixing with body fluids. Keywords: PAMAM dendrimer, nanomaterial, aggregation, blood–brain barrier

Inorganic arsenicals are well-known carcinogens, whereas arsenite (iAsIII) compounds are now recognized as potent therapeutic agents for several leukemias, and arsenic trioxide has been used for the treatment of recurrent acute promyelocytic leukemia (APL). However, recent clinical trials revealed that arsenite is not always effective for non-APL malignancies. Another arsenical, S-dimethylarsino-glutathione ([DMAIII(GS)]), which is a putative metabolic intermediate in the hepatic metabolism of iAsIII, shows promise for treating several types of lymphoma. However, the metabolism of [DMAIII(GS)] has not been well investigated, probably because [DMAIII(GS)] is not stable in biological fluids where the concentration of glutathione is low. In the present study, we injected [DMAIII(GS)] intravenously into mice and compared the tissue distribution and metabolic dynamics of [DMAIII(GS)] with those of sodium arsenite (NaAsO2). We found a unique organ preference for the distribution of [DMAIII(GS)] to the lung and brain in comparison to NaAsO2. Furthermore, [DMAIII(GS)] appeared to bind to serum albumin by exchanging its glutathione moiety quickly after administration, providing novel insights into the longer retention of [DMAIII(GS)] in plasma.

Autophagy molecules such as microtubule-associated protein light chain 3 (LC3) and p62/SQSTM1 have been used as biomarkers of protective or conversely adverse effects of exposure to toxicants. In the present study we show changes in LC3-II (a lipidated form of LC3-I) and p62 levels in response to zinc compounds and some other toxicants in J774.1 murine macrophages. The cytotoxicity of either ZnO or ZnSO4 largely depended on the concentration of FBS or albumin in the culture medium. Accordingly, these authophagy markers were more remarkably increased when the cells were exposed to ZnO or ZnSO4 in the absence of FBS. We next addressed lysosomal function impairment and changes in LC3-II and p62 levels following exposure to TiO2, ZnO, and ZnSO4. Lysosomal pH was quickly decreased by autolysosome inhibitors such as bafilomycin A1 and chloroquine, while TiO2, ZnO and ZnSO4 did not decrease lysosomal pH. However, the amounts of LC3-II and p62 and the LC3-II/LC3-I ratio were increased either by the lysosomal inhibitors and the Zn compounds. LC3-II and p62 levels were increased after exposure to arsenite and lipopolysaccharide (LPS). The p62 and phospho-p62 levels were also increased by either ZnSO4 and bafilomycin A1 in HEK293 cells stably expressing RFP-LC3. The current observations suggest that LC3-II and p62 levels were increased as consequences of early effects of toxicants without changing lysosomal pH.

Filter environmental samples of PM2.5 were collected at a traffic intersection in Kawasaki, Japan, and at a residential site (Tsukuba, Japan) in summer and winter, and the chemical compositions of the samples and their oxidative abilities in the dithiothreitol (DTT) assay were determined. Laboratory-generated aerosols (diesel exhaust particles [DEPs], gasoline direct injection spark ignition particles, and secondary organic aerosols [SOAs] generated from various precursors) were also investigated. To assess the effects of transition metals in the filter samples, we also conducted DTT assays on solutions of metal compounds similarly to the filter samples. In addition, the samples were pretreated with chelating reagents to mask the effects of transition metals. The DTT consumption average values for the filter samples collected at the traffic site were 53 and 50 pmol min–1 µg–1 in summer and winter, respectively, and these values were 1.3 and 1.1 times the corresponding values at the residential site and were also higher than the values for the laboratory-generated aerosols. Transition metals (Cu, Fe, Ni, and Mn) in the environmental samples were considered to be major contributors to DTT consumption (more than 80%). After removal of the effect of these transition metals with the chelating reagents, the oxidative abilities of the environmental samples were correlated with the amounts of organic carbon, water-soluble organic carbon, and organic acids and were weakly correlated with the amounts of elemental carbon and inorganic ions. We also found that the oxidative abilities based on the amount of organic carbon after removal of the effects of transition metals for DEPs, photochemically generated SOAs, and environmental samples except in the case of the traffic site in summer were compatible.

Silver is commonly used as a disinfectant, and chronic exposure to silver may cause argyria, resulting in a gray–blue discoloration of human skin. However, the mechanism for cellular toxicity of silver has not been well explained. We studied the mode of cell death, the ratio of glutathione disulfide/glutathione, induction of metallothionein and activation of mitogen-activated protein kinases in J774.1 cells together with activation of antioxidant responsive element and nuclear factor-κB in CHO cells following exposure to silver ion (Ag+) to investigate the mechanism by which Ag+ causes lethal effects. Ag+ increased phosphorylation levels of extracellular signal-regulated, c-Jun N-terminal and p38 mitogen-activated protein kinases and remarkably increased the ratio of glutathione disulfide/glutathione in both a time- and concentration-dependent manner. Luciferase reporter gene assays revealed that antioxidant responsive element and nuclear factor-κB were activated following exposure to Ag+. In addition, exposure to Ag+ increased the mRNA and protein levels of metallothionein. We investigated whether or not Ag+ killed J774.1 cells by inducing apoptosis. Ag+ increased the activity of caspase-3/7 which was abrogated by caspase 3 and pan-caspase inhibitors. However, these inhibitors did not ameliorate the cytotoxic effects of Ag+, suggesting that Ag+ causes oxidative stress, which leads to necrotic rather than apoptotic cell death in J774.1 cells by decreasing functional sulfhydryl groups including glutathione in the cells. Copyright © 2016 John Wiley & Sons, Ltd.

Quaternary ammonium compounds (e.g., benzalkonium chloride (BAC) and cetylpyridinium chloride (CPC)) constitute a group of cationic surfactants are widely used for personal hygiene and medical care despite the potential pulmonary toxicity. To examine whether BAC and CPC aerosols deposited in the alveolar region alter pulmonary function, we studied the effects on pulmonary surfactant using two-step in vitro models; cytotoxicity using A549 alveolar epithelial cell and changes in surface activity of the pulmonary surfactant monolayer using both Surfacten® and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Cell viability was decreased with BAC and CPC dose-dependently. A comparison of cytotoxicity among BAC homologues with different length of alkyl chain showed that C16-BAC, which has the longest alkyl chain, was more cytotoxic than C12- or C14-BAC. Caspase-3/7 activity and cleaved form of caspase-3 and PARP were increased in BAC- and CPC-exposed cells. The elevated caspase-3/7 activity and their cleaved active forms were abolished by caspase-3-inhibitor. Furthermore, we examined the features of the surface pressure/trough area (π-A) isotherm by the Langmuir-Wilhelmy method and atomic force microscopy (AFM) images of lipid monolayers on a subphase containing BAC, CPC, or pyridinium chloride (PC, as a control). The π-A isotherms showed that addition of BAC or CPC yielded dose-dependent increases in surface pressure without compression, indicating that BAC and CPC expand the isotherm to larger areas at lower pressure. The collapse pressure diminished with increasing concentration of CPC. Topographic images indicated that BAC and CPC resulted in smaller condensed lipid domains compared to the control. Conversely, PC without hydrocarbon tail group, showed no cytotoxicity and did not change the isotherms and AFM images. These results indicate that BAC and CPC cause cell death via caspase-3-dependent apoptotic pathway in A549 cells and alter the alveolar surfactant activity. These effects can be attributed to the long alkyl chain of BAC and CPC.

Promyelocytic leukemia (PML) and a suite of other proteins form nuclear bodies (NBs) where SUMOylation of PML and tumor suppression events occur in response to arsenite (As3+) treatment. Soluble PML is rapidly modified to the insoluble form in response to As3+, yet the relationship between the solubility change and nuclear localization of PML and PML-nuclear body (PML-NB) proteins remained elusive. We have investigated differences in the solubility change of well-known PML-NB proteins such as death-associated protein 6 (DAXX), SUMO, and PML in genetically engineered HEK293, and Jurkat and HL60 cells. The solubility of PML and SUMO2/3 monomers in RIPA solution decreased in 2 h in response to As3+. Live image analysis of GFP-PML revealed that extranuclear PML was insoluble in RIPA irrespective of the As3+-treatment and PML in PML-NBs, which was soluble in the untreated cells, was converted to insoluble forms by As3+. The solubility of DAXX was not changed by As3+, even though PML and DAXX co-localized completely in the subcellular compartments. Murine double mutant 2 (MDM2), which is known to interacts with intranuclear PML, did not affect the As3+-induced solubility change of PML. These results indicate that As3+ selectively reorganizes PML and SUMO2/3 monomers into insoluble forms in PML-NBs, and then PML SUMOylation proceeds.

Surface modified TiO2-based nanoparticles (the so-called second generation nanoparticles) have unique semiconducting properties. They act as efficient photocatalysts, demonstrating catalytic activity under UV-vis and light-emitting diode (mix-LED) light. Consequently, they can be used as versatile, low-cost, clean and environmentally benign components in many innovative solutions, e.g. treatment technology for a wide range of environmental pollutants. However, for commercial application of TiO2-based systems, it is crucial to develop nano-powders that can absorb light in the visible spectrum. Our investigation has demonstrated the potential benefits of using a chemoinformatics approach to obtaining knowledge on structural features responsible for the photocatalytic activity of second generation NPs under visible light. Through a combination of multiple linear regression (MLR) and a genetic algorithm (GA), we have developed a quantitative structure–properties relationship (Nano-QSPR) model (R2 = 0.89, RMSEC = 1.67, QLOO2 = 0.82, RMSECV = 2.18, QEXT2= 0.80, RMSEP = 1.46) based on the most relevant physicochemical properties that characterized selected Au/Pd–TiO2 NPs. According to the developed Nano-QSPR model, the anatase phase and palladium content are the main factors responsible for the higher activity of Au/Pd–TiO2 photocatalysts under visible light. It should be noted that the methodology presented here can serve as an important starting point for further design of new nanomaterials with enhanced functionality, supported by chemoinformatics methods.

Polyamidoamine (PAMAM) dendrimers have potential for biological applications as delivery systems for genes, drugs, and imaging agents into the brain, but their developmental neurotoxicity remains unknown. We investigated the effects of PAMAM dendrimers with various surface functional groups and multiple generations on neuronal differentiation using human neural progenitor cells at an equal mass concentration. Only PAMAM dendrimers containing amine (NH2) surface groups at concentrations of 10 μg/mL significantly reduced cell viability and neuronal differentiation, compared with non-amine-terminated dendrimers. PAMAM-NH2 with generation (G)3, G4, G5 G6, and G7 significantly decreased cell viability and inhibited neuronal differentiation from a concentration of 5 μg/mL, but G0, G1, and G2 dendrimers did not have any effect at this concentration. Cytotoxicity indices of PAMAM-NH2 dendrimers at 10 μg/mL correlated well with the zeta potentials of the particles. Surface group density and particle number in unit volume is more important characteristic than particle size to influence cytotoxicity for positive changed dendrimers. PAMAM-50% C12 at 1 μg/mL altered the expression level of the oxidative stress-related genes, ROR1, CYP26A1, and TGFB1, which is a DNA damage response gene. Our results indicate that PAMAM dendrimer exposure may have a surface charge-dependent adverse effect on neuronal differentiation, and that the effect may be associated with oxidative stress and DNA damage during development of neural cells.

Diphenylarsinic acid (DPAA) was detected as the primary compound responsible for the arsenic poisoning that occurred in Kamisu, Ibaraki, Japan, where people using water from a well that was contaminated with a high level of arsenic developed neurological (mostly cerebellar) symptoms and dysregulation of regional cerebral blood flow. To understand the underlying molecular mechanism of DPAA-induced cerebellar symptoms, we focused on astrocytes, which have a brain-protective function. Incubation with 10 µM DPAA for 96 h promoted cell proliferation, increased the expression of antioxidative stress proteins (heme oxygenase-1 and heat shock protein 70), and induced the release of cytokines (MCP-1, adrenomedullin, FGF2, CXCL1, and IL-6). Furthermore, DPAA overpoweringly increased the phosphorylation of three major mitogen-activated protein kinases (MAPKs) (ERK1/2, p38MAPK, and SAPK/JNK), which indicated MAPK activation, and subsequently induced expression and/or phosphorylation of transcription factors (Nrf2, CREB, c-Jun, and c-Fos) in cultured rat cerebellar astrocytes. Structure-activity relationship analyses of DPAA and other related pentavalent organic arsenicals revealed that DPAA at 10 µM activated astrocytes most effective among organic arsenicals tested at the same dose. These results suggest that in a cerebellum exposed to DPAA, abnormal activation of the MAPK-transcription factor pathway and irregular secretion of these neuroactive, glioactive, and/or vasoactive cytokines in astrocytes can be the direct/indirect cause of functional abnormalities in surrounding neurons, glial cells, and vascular cells: This in turn might lead to the onset of cerebellar symptoms and disruption of cerebral blood flow.

Promyelocytic leukemia (PML), which is a tumor suppressor protein that nevertheless plays an important role in the maintenance of leukemia initiating cells, is known to be biochemically modified by As{sup 3+}. We recently developed a simple method to evaluate the modification of PML by As{sup 3+} resulting in a change in solubility and the covalent binding of small ubiquitin-like modifier (SUMO). Here we semi-quantitatively investigated the SUMOylation of PML using HEK293 cells which were stably transfected with PML-VI (HEK-PML). Western blot analyses indicated that PML became insoluble in cold RadioImmunoPrecipitation Assay (RIPA) lysis buffer and was SUMOylated by both SUMO2/3 and SUMO1 by As{sup 3+}. Surprisingly SUMO1 monomers were completely utilized for the SUMOylation of PML. Antimony (Sb{sup 3+}) but not bismuth (Bi{sup 3+}), Cu{sup 2+}, or Cd{sup 2+} biochemically modified PML similarly. SUMOylated PML decreased after removal of As{sup 3+} from the culture medium. However, unSUMOylated PML was still recovered in the RIPA-insoluble fraction, suggesting that SUMOylation is not requisite for changing the RIPA-soluble PML into the RIPA-insoluble form. Immunofluorescence staining of As{sup 3+}-exposed cells indicated that SUMO2/3 was co-localized with PML in the nuclear bodies. However, some PML protein was present in peri-nuclear regions without SUMO2/3. Functional Reallymore » Interesting New Gene (RING)-deleted mutant PML neither formed PML nuclear bodies nor was biochemically modified by As{sup 3+}. Conjugation with intracellular glutathione may explain the accessibility of As{sup 3+} and Sb{sup 3+} to PML in the nuclear region evading chelation and entrapping by cytoplasmic proteins such as metallothioneins. - Highlights: • As{sup 3+} is a carcinogen and also a therapeutic agent for leukemia. • PML becomes insoluble in RIPA and SUMOylated by As{sup 3+}. • Sb{sup 3+} modifies PML similar to As{sup 3+}. • Functional RING motif is necessary for As{sup 3+}-induced PML modification.« less

Neurodevelopmental toxicity of silver nanoparticles (AgNPs) remains largely unknown. In this study, we applied a neurosphere assay for neurodevelopmental effects of AgNPs. The neural stem cells were isolated from rat mesencephalon. They were cultured as a sphere. In an assay with coated plates, cells appeared by anchoraging on the dish and then started to migrate along the radial axis from the neurosphere. AgNPs inhibited cell migration in a dose-dependent manner. There was a linear correlation between the inhibition of migration and the logarithm of the particle concentration (1.25-10 μg/ml); the half-maximal inhibitory concentration was 0.41 μg/ml for 16-h exposure. Preceding migrated cells were retarded and/or collapsed by exposure to AgNPs: lower doses of AgNPs (0.31-1.2 μg/ml) caused a 42% retardation for 48 h, while higher doses of AgNPs (2.5-10 μg/ml) collasped migrating cells. Furthermore, collapsed cells were TUNEL-positive and showed a defect in the mitochondrial membrane potential. Thus, we showed the neurodevelopmental toxicity of AgNPs using an in vitro neurosphere assay system.

The aims of our present study were to establish a novel olfactory-based spatial learning test and to examine the effects of exposure to nano-sized diesel exhaust-origin secondary organic aerosol (SOA), a model environmental pollutant, on the learning performance in preweaning mice. Pregnant BALB/c mice were exposed to clean air, diesel exhaust (DE), or DE-origin SOA (DE-SOA) from gestational day 14 to postnatal day (PND) 10 in exposure chambers. On PND 11, the preweaning mice were examined by the olfactory-based spatial learning test. After completion of the spatial learning test, the hippocampus from each mouse was removed and examined for the expressions of neurological and immunological markers using real-time RT-PCR. In the test phase of the study, the mice exposed to DE or DE-SOA took a longer time to reach the target as compared to the control mice. The expression levels of neurological markers such as the N-methyl-d-aspartate (NMDA) receptor subunits NR1 and NR2B, and of immunological markers such as TNF-α, COX2, and Iba1 were significantly increased in the hippocampi of the DE-SOA-exposed preweaning mice as compared to the control mice. Our results indicate that DE-SOA exposure in utero and in the neonatal period may affect the olfactory-based spatial learning behavior in preweaning mice by modulating the expressions of memory function–related pathway genes and inflammatory markers in the hippocampus.

The air–liquid interface (ALI) cell exposure system is a useful tool for assessing the toxicity of atmospheric aerosols and airborne engineered nanomaterials for in vitro studies. In order to evaluate dose–response relationships, it is necessary to determine the efficiency with which particles are deposited on cells in the ALI cell exposure chamber. In the present study, we determined the deposition efficiency for eight particle sizes between 30 and 1005 nm using two methods. Transmission electron microscopy was used to directly count the number of deposited particles, and particle trajectories were simulated using computational fluid dynamics, taking into account the drag, gravitational, and Brownian forces on the particle. The deposition efficiencies were validated separately and the results obtained by both methods were consistent. Both sets of results showed that the deposition efficiency was a minimum (below 1%) for 200–300 nm particles. A parametric study was also conducted, in particular to determine the influence of the distance ( S ) between the nozzle head and the bottom surface of the target cells on the deposition efficiency. For a particle size of 1005 nm, where the gravitational force dominates, the deposition efficiency was found to decrease linearly with increasing S . In contrast, for a particle size of 100 nm, where diffusion dominates, the decrease in deposition efficiency with increasing S followed a power law. It was shown that the deposition efficiency could be predicted for arbitrary particle properties, air flow conditions, and ALI cell exposure chamber geometry, based on the Stokes number, Froude number, Peclet number, and ratio of S to the inlet nozzle radius.

Asbestos and silica (exogenous danger) and adenosine triphosphate (ATP, endogenous danger-signaling molecule) synergistically increase IL-1β release from endotoxin-primed macrophage, which is mediated by NOD-like receptor protein 3 (NLRP3) inflammasome. However, the conversion of pro-IL-1β to its active form seems to depend on the macrophage cell types. In the present study, bone marrow-derived macrophages (BMM) and three murine macrophage cell lines, J774.1, J774A.1, and RAW264.7 were exposed to ATP or fibrous titanium dioxide (FTiO2) in the presence or absence of lipopolysaccharide (LPS), and the concentrations of IL-1β and IL-6 in both cell lysates and in the culture media were measured by immunoblotting to differentiate active form of IL-1β from pro-IL-1β. IL-1β release was synergistically increased when the cells were exposed to both LPS and ATP or FTiO2, while IL-6 was readily released by LPS alone. IL-1β released into the culture medium was pro-IL-1β in J774.1 and RAW264.7, and most of the pro-IL-1β remained inside the cells. In contrast, the active form of IL-1β was released together with pro-IL-1β from J774A.1 and BMM after the co-stimulation. J774A.1 and BMM express apoptosis-associated speck-like protein contains a carboxyl-terminal CARD (ASC) while J774.1 and RAW264.7 do not or only faintly express ASC, and accordingly, caspase-1, which converts pro-IL-1β to its active form, is activated only in J774A.1 and BMM. Collectively, the canonical inflammasome pathway is not activated in J774.1 and RAW264.7, and the apparent synergistical increase of IL-1β in the culture medium mostly reflects the leakage of pro-IL-1β from these cells.

Exposure to ambient air pollutants has been reported to have various adverse health impacts. Ambient particulate matter comprises primary particles released directly via engine exhaust and secondary organic aerosols (SOAs) formed from oxidative reactions of the ultrafine particle fraction of diesel exhaust (DE). Toll-like receptor 4 (TLR4) is well known to initiate the inflammatory cascade in the central nervous system. However, whether and how DE and DE-SOA exposure influences TLR4 signaling in the immature brain remains unclear. We attempted to evaluate the roles of TLR-4, inflammatory mediators and microglial markers in the impaired spatial learning ability of neonatal mice exposed to DE and DE-SOAs. Pregnant C3H/HeN (TLR4-intact) and C3H/HeJ (TLR4- mutated) mice were exposed to clean air, DE or DE-SOA from gestational day 14 to postnatal day (PND) 10 (5 h/day for 5 days) in exposure chambers. PND11 neonatal mice were examined for their performance in the olfactory-based spatial learning test. After the spatial learning test, the hippocampi of the mice were removed and real-time RT-PCR analysis was performed to examine the neurological and immunological markers. Both male and female C3H/HeN and C3H/HeJ neonatal mice exposed to DE and DE-SOAs showed poor performance in the test phase of spatial learning as compared to the mice exposed to clean air. However, this spatial learning deficit was prominent in C3H/HeJ neonatal mice. In the neonatal C3H/HeN male mice exposed to DE and DE-SOAs, the mRNA expression levels of the NMDA receptor subunits (NR1, NR2B), proinflammatory cytokines, tumor necrosis factor-α and cyclooxygenase-2, oxidative stress marker, heme oxygenase-1, and microglial marker, Iba1, in the hippocampus were significantly increased, but these changes were not observed in female mice. Our findings indicate that activation of the neuroimmune system and TLR4 signaling may possibly be involved in environmental pollutant-induced spatial learning impairment in neonatal mice.

Particulate air pollution (PM 2.5) is a worldwide concern. Growing epidemiological evidence has shown pathophysiological effects of PM 2.5, not only on cardiovascular system but also on reproductive performance. The composition and physicochemical properties of PM 2.5 vary depending on the emission sources, climate conditions, and complex chemical reactions in the air. These factors make it difficult to understand the cause and mechanistic details of the adverse health effects of PM 2.5. Here, we show potential impacts of PM 2.5 on oocyte maturation in mice by utilizing diesel exhaust-derived secondary organic aerosol (SOA), a major component of urban PM 2.5. We found that the SOA destabilized microtubules of mouse oocytes and p-benzoquinone is one of the candidates for the microtubule-destabilizing compounds. We propose that some biologically reactive components of PM 2.5 should be prioritized for the regulation of atmospheric quality.

Inorganic arsenite (iAs(3+)) is a two-edged sword. iAs(3+) is a well-known human carcinogen; nevertheless, it has been used as a therapeutic drug for acute promyelocytic leukemia (APL), which is caused by a fusion protein comprising retinoic acid receptor-α and promyelocytic leukemia (PML). PML, a nuclear transcription factor, has a RING finger domain with densely positioned cysteine residues. To examine PML-modulated cellular responses to iAs(3+), CHO-K1 and HEK293 cells were each used to establish cell lines that expressed ectopic human PML. Overexpression of PML increased susceptibility to iAs(3+) in CHO-K1 cells, but not in HEK293 cells. Exposure of PML-transfected cells to iAs(3+) caused PML to change from a soluble form to less soluble forms, and this modification of PML was observable even with just 0.1 μM iAs(3+) (7.5 ppb). Western blot and immunofluorescent microscopic analyses revealed that the biochemical changes of PML were caused at least in part by conjugation with small ubiquitin-like modifier proteins (SUMOylation). A luciferase reporter gene was used to investigate whether modification of PML was caused by oxidative stress or activation of antioxidant response element (ARE) in CHO-K1 cells. Modification of PML protein occurred faster than activation of the ARE in response to iAs(3+), suggesting that PML was not modified as a consequence of oxidative stress-induced ARE activation.