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As the applications of industrial nanoparticles are being developed, the concerns on the environmental health are increasing. Cytotoxicities of titanium dioxide nanoparticles of different concentrations (5, 10, 20 and 40 microg/ml) were evaluated in this study using a cultured human bronchial epithelial cell line, BEAS-2B. Exposure of the cultured cells to nanoparticles led to cell death, reactive oxygen species (ROS) increase, reduced glutathione (GSH) decrease, and the induction of oxidative stress-related genes such as heme oxygenase-1, thioredoxin reductase, glutathione-S-transferase, catalase, and a hypoxia inducible gene. The ROS increase by titanium dioxide nanoparticles triggered the activation of cytosolic caspase-3 and chromatin condensation, which means that titanium dioxide nanoparticles exert cytotoxicity by an apoptotic process. Furthermore, the expressions of inflammation-related genes such as interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), TNF-a, and C-X-C motif ligand 2 (CXCL2) were also elevated. The induction of IL-8 by titanium dioxide nanoparticles was inhibited by the pre-treatment with SB203580 and PD98059, which means that the IL-8 was induced through p38 mitogen-activated protein kinase (MAPK) pathway and/or extracellular signal (ERK) pathway. Uptake of the nanoparticles into the cultured cells was observed and titanium dioxide nanoparticles seemed to penetrate into the cytoplasm and locate in the peri-region of the nucleus as aggregated particles, which may induce direct interactions between the particles and cellular molecules, to cause adverse biological responses.

Cerium oxide nanoparticles of different sizes (15, 25, 30, 45 nm) were prepared by the supercritical synthesis method, and cytotoxicity was evaluated using cultured human lung epithelial cells (BEAS-2B). Exposure of the cultured cells to nanoparticles (5, 10, 20, 40 microg/ml) led to cell death, ROS increase, GSH decrease, and the inductions of oxidative stress-related genes such as heme oxygenase-1, catalase, glutathione S-transferase, and thioredoxin reductase. The increased ROS by cerium oxide nanoparticles triggered the activation of cytosolic caspase-3 and chromatin condensation, which means that cerium oxide nanoparticles exert cytotoxicity by an apoptotic process. Uptake of the nanoparticles to the cultured cells was also tested. It was observed that cerium oxide nanoparticles penetrated into the cytoplasm and located in the peri-region of the nucleus as aggregated particles, which may induce the direct interaction between nanoparticles and cellular molecules to cause adverse cellular responses.

Mercury is a widespread environmental and industrial pollutant that induces serious adverse effects in both humans and the environment. However, the toxicities and its mechanisms have not been fully elucidated. Among the proposed mechanisms of biological toxicities, the intracellular level of thiol group (-SH) and oxidative stress have been widely studied. In this study, production of reactive oxygen species (ROS) by mercuric chloride (2, 4, 6, and 8 ppm as of mercury) was investigated in cultured human bronchial epithelial cells (BEAS-2B cell line). Exposure of cultured cells to mercuric chloride led to cell death, ROS increase, and cytosolic caspase-3 activation. The ROS increase was related to the decreased level of GSH. Chromatin condensation evaluated by 4',6-diamidino-2-phenylindole (DAPI) staining were also shown in mercury-treated cells and this suggest the apoptotic process of cells by mercuric chloride.

Abstract: Manganese, an essential trace nutrient in human beings, has been widely used in the steel industry to improve hardness, stiffness, and strength. With the increased applications of manganese compounds, discharge into the environment has rapidly increased and may exert adverse effects on human health. In this study, manganese toxicity was investigated using cultured T98G cells, which are derived from human glioblasts with the ability to differentiate into several different types of neuroglia. Cytotoxicity was shown in manganese-treated groups (100, 200, 400, and 800μM of MnCl2), and cell viability was decreased to 58.8% of the control group at 2days after treatment with 800μM of MnCl2. When cells were treated with manganese for 24h, ROS dose-dependently increased while antioxidant intracellular GSH decreased. With the generation of ROS, the increased activity of caspase-3 was shown, and was followed by chromatin condensation and breakage, which is an indication of the cellular apoptotic process. ROS also triggered pro-inflammatory responses in cultured T98G cells, which were demonstrated by the increased gene expression and protein levels of IL-6 and IL-8. [Copyright &y& Elsevier]

Abstract: Octachlorostyrene (OCS) is a persistent and bioaccumulative toxicant (PBT) that is a halogenated aromatic compound. OCS belongs to the primary level I group chemicals designated by the US Environmental Protection Agency, which are the most concerning chemicals among the PBTs. It is known that OCS has never been commercially used but has been widely distributed in the environments. Although OCS has been occasionally measured in human samples as well as environmental samples such as water, soil, sediment, fishes, and marine mammals, the impact of OCS on human health is still unclear. It is assumed that the toxicities of OCS follow the other chlorinated chemicals, like hexachlorobenzene, and there is also possibility to be metabolized to generate radicals. In this study, cell toxicity and induction of reactive oxygen species (ROS) by OCS (6.25, 12.5, 25, 50μM) were studied in cultured human Chang liver cells. Exposure of cultured cells to OCS led to cell death, ROS increase, and cytosolic caspase-3 activation. ROS increase was related to the decreased level of GSH. Chromatin fragmentation and condensation were also shown in OCS-treated cells. These results suggest the toxicity in the human Chang liver cells by OCS may be induced through the apoptotic processes. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles (AgNPs) may induce deleterious effects in aquatic life on environmental release. The hepatotoxicity of AgNPs was assessed in the liver of adult zebrafish, with the aim of studying the roles of oxidative damage and apoptosis. Zebrafish were exposed to an AgNP solution in which free Ag+ ions were absent at the time of treatment. However, the metal-sensitive metallothionein 2 (MT2) mRNA was induced in the liver tissues of AgNP-treated zebrafish, suggesting that Ag+ ions were released from AgNPs after treatment. It is also possible that MT2 mRNA was induced in the liver tissues by AgNP-generated free radicals. A number of cellular alterations including disruption of hepatic cell cords and apoptotic changes were observed in histological analysis of the liver tissues. The levels of malondialdehyde, a byproduct of cellular lipid peroxidation, and total glutathione were increased in the tissues after treatment with AgNPs. The mRNA levels of the oxyradical-scavenging enzymes catalase and glutathione peroxidase 1a were reduced in the tissues. AgNP treatment induced DNA damage, as demonstrated by analysis with the double-strand break marker γ-H2AX and the expression of p53 protein in liver tissues. In addition, the p53-related pro-apoptotic genes Bax, Noxa, and p21 were upregulated after treatment with AgNPs. These data suggest that oxidative stress and apoptosis are associated with AgNP toxicity in the liver of adult zebrafish. [Copyright &y& Elsevier]

Abstract: Silver nanoparticles (AgNPs) are widely applied in many household products and medical uses. However, studies on the effects of AgNPs on human health and environmental implications are in the beginning stage. Furthermore, most data on the toxicity of AgNPs have been generated using nanoparticles modified with detergents to prevent agglomeration, which may alter their toxicities. In this study, we studied toxicity using AgNPs prepared by dispersing them in fetal bovine serum (FBS), biocompatible materials. AgNPs (average size; 68.9nm, concentrations; 0.2, 0.4, 0.8, and 1.6ppm, exposure time; 24, 48, 72, and 96h) showed cytotoxicity to cultured RAW264.7 cells by increasing sub G1 fraction, which indicates cellular apoptosis. AgNPs decreased intracellular glutathione level, increased NO secretion, increased TNF-α in protein and gene levels, and increased gene expression of matrix metalloproteinases (MMP-3, MMP-11, and MMP-19). When cells were treated with AgNPs, they were observed in the cytosol of the activated cells, but were not observed in the dead cells. It seemed that AgNPs were ionized in the cells to cause cytotoxicity by a Trojan-horse type mechanism suggested by previously reported studies. [Copyright &y& Elsevier]