Role of oxidative damage in toxicity of particulates

Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice: effects in prenatally exposed offspring on hepatic DNA damage and gene expression

We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan exposure did not induce DNA strand breaks in time-mated mice or their offspring. Transcriptional profiling of newborn livers revealed changes in the gene expression related to the retinoic acid signalling pathway in the females, while gene expression in male offspring was unaffected. Changes may be a secondary response to maternal inflammation although no direct link was evident through gene expression analysis.

Particulate matter neurotoxicity in culture is size-dependent

Exposure to particulate matter (PM) air pollution produces inflammatory damage to the cardiopulmonary system. This toxicity appears to be inversely related to the size of the PM particles, with the ultrafine particle being more inflammatory than larger sizes. Exposure to PM has more recently been associated with neurotoxicity. This study examines if the size-dependent toxicity reported in cardiopulmonary systems also occurs in neural targets. For this study, PM ambient air was collected over a 2 week period from Sterling Forest State Park (Tuxedo, New York) and its particulates sized as Accumulation Mode, Fine (AMF) (>0.18-1μm) or Ultrafine (UF) (<0.18μm) samples. Rat dopaminergic neurons (N27) were exposed to suspensions of each PM fraction (0, 12.5, 25, 50μm/ml) and cell loss (as measured by Hoechst nuclear stain) measured after 24h exposure. Neuronal loss occurred in response to all tested concentrations of UF (>12.5μg/ml) but was only significant at the highest concentration of AMF (50μg/ml). To examine if PM size-dependent neurotoxicity was retained in the presence of other cell types, dissociated brain cultures of embryonic rat striatum were exposed to AMF (80μg/ml) or UF (8.0μg/ml). After 24h exposure, a significant increase of reactive nitrogen species (nitrite) and morphology suggestive of apoptosis occurred in both treatment groups. However, morphometric analysis of neuron specific enolase staining indicated that only the UF exposure produced significant neuronal loss, relative to controls. Together, these data suggest that the inverse relationship between size and toxicity reported in cardiopulmonary systems occurs in cultures of isolated dopaminergic neurons and in primary cultures of the rat striatum.

Multiple aspects of the interaction of biomacromolecules with inorganic surfaces

The understanding of the mechanisms involved in the interaction of biological systems with inorganic materials is of interest in both fundamental and applied disciplines. The adsorption of proteins modulates the formation of biofilms onto surfaces, a process important in infections associated to medical implants, in dental caries, in environmental technologies. The interaction with biomacromolecules is crucial to determine the beneficial/adverse response of cells to foreign inorganic materials as implants, engineered or accidentally produced inorganic nanoparticles. A detailed knowledge of the surface/biological fluids interface processes is needed for the design of new biocompatible materials. Researchers involved in the different disciplines face up with similar difficulties in describing and predicting phenomena occurring at the interface between solid phases and biological fluids. This review represents an attempt to integrate the knowledge from different research areas by focussing on the search for determinants driving the interaction of inorganic surfaces with biological matter.

Oxidative stress, genotoxicity, and vascular cell adhesion molecule expression in cells exposed to particulate matter from combustion of conventional diesel and methyl ester biodiesel blends

Our aim was to compare hazards of particles from combustion of biodiesel blends and conventional diesel (D(100)) in old and improved engines. We determined DNA damage in A549 cells, mRNA levels of CCL2 and IL8 in THP-1 cells, and expression of ICAM-1 and VCAM-1 in human umbilical cord endothelial cells (HUVECs). Viability and production of reactive oxygen species (ROS) were investigated in all cell types. We collected particles from combustion of D(100) and 20% (w/w) blends of animal fat or rapeseed oil methyl esters in light-duty vehicle engines complying with Euro2 or Euro4 standards. Particles emitted from the Euro4 engine were smaller in size and more potent than particles emitted from the Euro2 engine with respect to ROS production and DNA damage, but similarly potent concerning cytokine mRNA expression. Particles emitted from combustion of biodiesel blends were larger in size, and less or equally potent than particles emitted from combustion of D(100) concerning ROS production, DNA damage and mRNA of CCL2 and IL8. ICAM-1 and VCAM-1 expression in HUVECs was only increased by D(100) particles from the Euro4 engine. This suggests that particle emissions from biodiesel in equal mass concentration are less toxic than conventional diesel.

In vitro toxicity of particulate matter (PM) collected at different sites in the Netherlands is associated with PM composition, size fraction and oxidative potential--the RAPTES project

Background

Ambient particulate matter (PM) exposure is associated with respiratory and cardiovascular morbidity and mortality. To what extent such effects are different for PM obtained from different sources or locations is still unclear. This study investigated the in vitro toxicity of ambient PM collected at different sites in the Netherlands in relation to PM composition and oxidative potential.

Method

PM was sampled at eight sites: three traffic sites, an underground train station, as well as a harbor, farm, steelworks, and urban background location. Coarse (2.5-10 μm), fine (< 2.5 μm) and quasi ultrafine PM (qUF; < 0.18 μm) were sampled at each site. Murine macrophages (RAW 264.7 cells) were exposed to increasing concentrations of PM from these sites (6.25-12.5-25-50-100 μg/ml; corresponding to 3.68-58.8 μg/cm²). Following overnight incubation, MTT-reduction activity (a measure of metabolic activity) and the release of pro-inflammatory markers (Tumor Necrosis Factor-alpha, TNF-α; Interleukin-6, IL-6; Macrophage Inflammatory Protein-2, MIP-2) were measured. The oxidative potential and the endotoxin content of each PM sample were determined in a DTT- and LAL-assay respectively. Multiple linear regression was used to assess the relationship between the cellular responses and PM characteristics: concentration, site, size fraction, oxidative potential and endotoxin content.

Results

Most PM samples induced a concentration-dependent decrease in MTT-reduction activity and an increase in pro-inflammatory markers with the exception of the urban background and stop & go traffic samples. Fine and qUF samples of traffic locations, characterized by a high concentration of elemental and organic carbon, induced the highest pro-inflammatory activity. The pro-inflammatory response to coarse samples was associated with the endotoxin level, which was found to increase dramatically during a three-day sample concentration procedure in the laboratory. The underground samples, characterized by a high content of transition metals, showed the largest decrease in MTT-reduction activity. PM size fraction was not related to MTT-reduction activity, whereas there was a statistically significant difference in pro-inflammatory activity between Fine and qUF PM. Furthermore, there was a statistically significant negative association between PM oxidative potential and MTT-reduction activity.

Conclusion

The response of RAW264.7 cells to ambient PM was markedly different using samples collected at various sites in the Netherlands that differed in their local PM emission sources. Our results are in support of other investigations showing that the chemical composition as well as oxidative potential are determinants of PM induced toxicity in vitro.

Topography of tyrosine residues and their involvement in peroxidation of polyunsaturated cardiolipin in cytochrome c/cardiolipin peroxidase complexes

Formation of cytochrome c (cyt c)/cardiolipin (CL) peroxidase complex selective toward peroxidation of polyunsaturated CLs is a pre-requisite for mitochondrial membrane permeabilization. Tyrosine residues - via the generation of tyrosyl radicals (Tyr) - are likely reactive intermediates of the peroxidase cycle leading to CL peroxidation. We used mutants of horse heart cyt c in which each of the four Tyr residues was substituted for Phe and assessed their contribution to the peroxidase catalysis. Tyr67Phe mutation was associated with a partial loss of the oxygenase function of the cyt c/CL complex and the lowest concentration of H(2)O(2)-induced Tyr radicals in electron paramagnetic resonance (EPR) spectra. Our MS experiments directly demonstrated decreased production of CL-hydroperoxides (CL-OOH) by Tyr67Phe mutant. Similarly, oxidation of a phenolic substrate, Amplex Red, was affected to a greater extent in Tyr67Phe than in three other mutants. Tyr67Phe mutant exerted high resistance to H(2)O(2)-induced oligomerization. Measurements of Tyr fluorescence, hetero-nuclear magnetic resonance (NMR) and computer simulations position Tyr67 in close proximity to the porphyrin ring heme iron and one of the two axial heme-iron ligand residues, Met80. Thus, the highly conserved Tyr67 is a likely electron-donor (radical acceptor) in the oxygenase half-reaction of the cyt c/CL peroxidase complex.

Air pollution from traffic and cancer incidence: a Danish cohort study

BACKGROUND

Vehicle engine exhaust includes ultrafine particles with a large surface area and containing absorbed polycyclic aromatic hydrocarbons, transition metals and other substances. Ultrafine particles and soluble chemicals can be transported from the airways to other organs, such as the liver, kidneys, and brain. Our aim was to investigate whether air pollution from traffic is associated with risk for other cancers than lung cancer.

METHODS

We followed up 54,304 participants in the Danish Diet Cancer and Health cohort for 20 selected cancers in the Danish Cancer Registry, from enrolment in 1993-1997 until 2006, and traced their residential addresses from 1971 onwards in the Central Population Registry. We used modeled concentration of nitrogen oxides (NO(x)) and amount of traffic at the residence as indicators of traffic-related air pollution and used Cox models to estimate incidence rate ratios (IRRs) after adjustment for potential confounders.

RESULTS

NO(x) at the residence was significantly associated with risks for cervical cancer (IRR, 2.45; 95% confidence interval [CI], 1.01;5.93, per 100 μg/m(3) NO(x)) and brain cancer (IRR, 2.28; 95% CI, 1.25;4.19, per 100 μg/m(3) NO(x)).

CONCLUSIONS

This hypothesis-generating study indicates that traffic-related air pollution might increase the risks for cervical and brain cancer, which should be tested in future studies.

Fine particulate matter from urban ambient and wildfire sources from California's San Joaquin Valley initiate differential inflammatory, oxidative stress, and xenobiotic responses in human bronchial epithelial cells

Environmental particulate matter (PM) exposure has been correlated with pathogenesis of acute airway inflammatory disease such as asthma and COPD. PM size and concentration have been studied extensively, but the additional effects of particulate components such as biological material, transition metals, and polycyclic aromatic hydrocarbons could also impact initial disease pathogenesis. In this study, we compared urban ambient particulate matter (APM) collected from Fresno, California with wildfire (WF) particulate matter collected from Escalon, California on early transcriptional responses in human bronchial epithelial cells (HBE). Global gene expression profiling of APM treated HBE activated genes related to xenobiotic metabolism (CYP 1B1), endogenous ROS generation and response genes (DUOX1, SOD2, PTGS2) and pro-inflammatory responses associated with asthma or COPD such as IL-1α, IL-1β, IL-8, and CCL20. WF PM treatments also induced a pro-inflammatory gene response, but elicited a more robust xenobiotic metabolism and oxidative stress response. Inhibitor studies targeting endotoxin, ROS, and trace metals, found endotoxin inhibition had modest selective inhibition of inflammation while inhibition of hydrogen peroxide and transition metals had broad effects suggesting additional interactions with xenobiotic metabolism pathways. APM induced a greater inflammatory response while WF PM had more marked metabolism and ROS related responses.

Pulmonary exposure to carbon black by inhalation or instillation in pregnant mice: effects on liver DNA strand breaks in dams and offspring

Effects of maternal pulmonary exposure to carbon black (Printex 90) on gestation, lactation and DNA strand breaks were evaluated. Time-mated C57BL/6BomTac mice were exposed by inhalation to 42 mg/m³ Printex 90 for 1 h/day on gestation days (GD) 8-18, or by four intratracheal instillations on GD 7, 10, 15 and 18, with total doses of 11, 54 and 268 (μg/animal. Dams were monitored until weaning and some offspring until adolescence. Inflammation was assessed in maternal bronchoalveolar lavage (BAL) 3-5 days after exposure, and at weaning. Levels of DNA strand breaks were assessed in maternal BAL cells and liver, and in offspring liver. Persistent lung inflammation was observed in exposed mothers. Inhalation exposure induced more DNA strand breaks in the liver of mothers and their offspring, whereas intratracheal instillation did not. Neither inhalation nor instillation affected gestation and lactation. Maternal inhalation exposure to Printex 90-induced liver DNA damage in the mothers and the in utero exposed offspring.

Genetic and environmental influences on oxidative damage assessed in elderly Danish twins

Previous studies have shown an association between oxidative stress and various diseases in humans including cancer, cardiovascular disease, diabetes, and chronic respiratory disease. To what extents this damage is determined by genetic and environmental factors is unknown. In a classical twin study with 198 elderly twins we examined the contributions of genetic versus environmental factors to nucleic acid oxidation and lipid peroxidation. Urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), 8-oxo-7,8-dihydroguanosine (8-oxoGuo), and dinor,dihydro F₂-isoprostane metabolites (F₂-IsoP-M) was measured using liquid chromatography-tandem mass spectrometry. The environmental influence on nucleic acid oxidation and lipid peroxidation was predominant, leaving only little influence from genetic factors, as evidenced by no differences in intraclass correlations between monozygotic (MZ) and dizygotic (DZ) twins, neither for 8-oxodG (r(MZ)=0.55, r(DZ)=0.47; P=0.43), F(2)-IsoP-M (r(MZ)=0.33, r(DZ)=0.22; P=0.42), nor 8-oxoGuo (r(MZ)=0.45, r(DZ)=0.58; P=0.21). Accordingly, heritability estimates for the three markers of oxidative damage were low (h²=0.17-0.22). The three urinary markers of oxidative stress were closely correlated (r=0.60-0.84). In conclusion, we demonstrated in a large population of elderly Danish twins that "whole-body" oxidative damage to nucleic acids and lipids is predominantly determined by potentially modifiable nongenetic factors.

Lung cancer incidence and long-term exposure to air pollution from traffic

BACKGROUND

Previous studies have shown associations between air pollution and risk for lung cancer.

OBJECTIVE

We investigated whether traffic and the concentration of nitrogen oxides (NOx) at the residence are associated with risk for lung cancer.

METHODS

We identified 592 lung cancer cases in the Danish Cancer Registry among 52,970 members of the Diet, Cancer and Health cohort and traced residential addresses from 1 January 1971 in the Central Population Registry. We calculated the NOx concentration at each address by dispersion models and calculated the time-weighted average concentration for all addresses for each person. We used Cox models to estimate incidence rate ratios (IRRs) after adjustment for smoking (status, duration, and intensity), environmental tobacco smoke, length of school attendance, occupation, and dietary intake of fruit.

RESULTS

For the highest compared with the lowest quartile of NOx concentration at the residence, we found an IRR for lung cancer of 1.30 [95% confidence interval (CI), 1.05-1.61], and the IRR for lung cancer in association with living within 50 m of a major road (>10,000 vehicles/day) was 1.21 (95% CI, 0.95-1.55). The results showed tendencies of stronger associations among nonsmokers, among those with a relatively low fruit intake, and among those with a longer school attendance; only length of school attendance modified the effect significantly.

CONCLUSIONS

This study supports that risk for lung cancer is associated with different markers of air pollution from traffic near the residence.

Gene-air pollution interaction and cardiovascular disease: a review

Genetic susceptibility is likely to play a role in response to air pollution. Hence, gene-environment interaction studies can be a tool for exploring the mechanisms and the importance of the pathway in the association between air pollution and a cardiovascular outcome. In this article, we present a systematic review of the studies that have examined gene-environment interactions in relation to the cardiovascular health effects of air pollutants. We identified 16 articles meeting our search criteria. Of these studies, most have focused on individual functional polymorphisms or individual candidate genes. Moreover, they were all based on 3 study populations that have been extensively investigated in relation to air pollution effects: the Normative Aging Study, Air Pollution and Inflammatory Response in Myocardial Infarction Survivors: Gene-Environment Interaction in a High Risk Group, and Multiethnic Study of Atherosclerosis. In conclusions, the studies differed substantially in both the cardiovascular outcomes examined and the polymorphisms examined, so there is little confirmation of results across cohorts. Gene-environment interaction studies can help explore the mechanisms and the potential pathway in the association between air pollution and a cardiovascular outcome; replication of findings and studies involving multiple cohorts would be needed to draw stronger conclusions.

The effects of evening primrose oil on lipid peroxidation induced by subacute aflatoxin exposure in mice

The present study was aimed at the investigation of the antioxidative effect of evening primrose oil in cases of subacute aflatoxin (AF) intoxication induced in mice. For this purpose, forty-eight 6-8-week-old male BALB/c mice, weighing 30-35 g, were used. The animals were allocated to four groups, each comprising of 12 mice, such that one group was maintained as the control group and the other three constituted the trial groups. The mice included in the control group (Group 1) were not subjected to any treatment. Group 2 was administered with 1.5 ml/kg bw/day of evening primrose oil; Group 3 received 1250 μg/kg bw/day of AF (82.45% AFB(1), 10.65% AFB(2), 4.13% AFG(1) and 2.77% AFG(2)) and Group 4 was given 1250 μg/kg bw/day of AF plus 1.5 ml/kg bw/day of evening primrose oil using a catheter, for a period of 14 days. At the end of the 14th day, the liver, lungs, kidneys, brain, heart and spleen of the animals included in all groups were extracted. Malondialdehyde (MDA) levels and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidise (GSH-Px) activities were measured in tissue homogenates. In result, it was concluded that, evening primrose oil had a positive effect on aflatoxin-induced lipid peroxidation.

Mutation spectrum in FE1-MUTA(TM) Mouse lung epithelial cells exposed to nanoparticulate carbon black

It has been shown previously that carbon black (CB), Printex 90 exposure induces cII and lacZ mutants in the FE1-Muta(TM) Mouse lung epithelial cell line and causes oxidatively damaged DNA and the production of reactive oxygen species (ROS). The purpose of this study was to determine the mutation spectrum in the cII gene of Printex 90 exposed cells. Cells exposed to CB have a substantially different mutation spectrum in the cII gene compared with vehicle exposed controls. The mutation spectra differ both in the positions (P < 0.0001) and types of the mutations (P < 0.0001). Exposure to Printex 90 increased the number of single base deletions by 2.3-fold and larger deletions by 1.9-fold. Most single base deletions were within two repetitive sequences in cII, but the large deletions were not. The mechanism behind the large deletions is not yet known. The largest increases in base substitutions were observed in G:C→T:A, G:C→C:G, and A:T→T:A transversion mutations; this is in keeping with a genetic finger print of ROS and is further substantiated by the observations that Printex 90 generates ROS and oxidatively damaged DNA.

Effect of vitamin C and iron chelation on diesel exhaust particle and carbon black induced oxidative damage and cell adhesion molecule expression in human endothelial cells

Exposure to particulate matter is associated with oxidative stress and risk of cardiovascular diseases. We investigated if vitamin C and desferrioxamine (iron chelator) altered the levels of oxidative stress and expression of cell adhesion molecules upon exposure to diesel exhaust particles (DEP) and carbon black in cultured human umbilical vein endothelial cells (HUVECs). We found that the particles were only slightly cytotoxic in the high concentration ranges. Particle-induced intracellular reactive oxygen species (ROS) production was attenuated by vitamin C administration or iron chelation and particularly when combined (p<0.001). Only desferrioxamine protected the DNA from oxidative damage in terms of strand breaks and formamidopyrimidine DNA glycosylase sensitive sites induced by carbon black (p<0.01). Carbon black and small sized DEP generated from an Euro4 engine increased the surface expression of VCAM-1 and ICAM-1, whereas DEP from an engine representing an old combustion type engine (SRM2975) with larger particles did not affect the expression of cell adhesion molecules. These effects were also attenuated by desferrioxamine but not vitamin C. The study shows that exposure to carbon black and DEP in HUVECs can generate both oxidative stress and expression of cell surface adhesion molecules and that these effects can in part be attenuated by vitamin C and desferrioxamine.

Cytotoxicity and oxidative stress induced by different metallic nanoparticles on human kidney cells

Background

Some manufactured nanoparticles are metal-based and have a wide variety of applications in electronic, engineering and medicine. Until now, many studies have described the potential toxicity of NPs on pulmonary target, while little attention has been paid to kidney which is considered to be a secondary target organ. The objective of this study, on human renal culture cells, was to assess the toxicity profile of metallic nanoparticles (TiO₂, ZnO and CdS) usable in industrial production. Comparative studies were conducted, to identify whether particle properties impact cytotoxicity by altering the intracellular oxidative status.

Results

Nanoparticles were first characterized by size, surface charge, dispersion and solubility. Cytotoxicity of NPs was then evaluated in IP15 (glomerular mesangial) and HK-2 (epithelial proximal) cell lines. ZnO and CdS NPs significantly increased the cell mortality, in a dose-dependent manner. Cytotoxic effects were correlated with the physicochemical properties of NPs tested and the cell type used. Analysis of reactive oxygen species and intracellular levels of reduced and oxidized glutathione revealed that particles induced stress according to their composition, size and solubility. Protein involved in oxidative stress such as NF-κb was activated with ZnO and CdS nanoparticles. Such effects were not observed with TiO₂ nanoparticles.

Conclusion

On glomerular and tubular human renal cells, ZnO and CdS nanoparticles exerted cytotoxic effects that were correlated with metal composition, particle scale and metal solubility. ROS production and oxidative stress induction clearly indicated their nephrotoxic potential.

Hazard identification of particulate matter on vasomotor dysfunction and progression of atherosclerosis

The development and use of nanoparticles have alerted toxicologists and regulators to issues of safety testing. By analogy with ambient air particles, it can be expected that small doses are associated with a small increase in risk of cardiovascular diseases, possibly through oxidative stress and inflammatory pathways. We have assessed the effect of exposure to particulate matter on progression of atherosclerosis and vasomotor function in humans, animals, and ex vivo experimental systems. The type of particles that have been tested in these systems encompass TiO(2), carbon black, fullerene C(60), single-walled carbon nanotubes, ambient air particles, and diesel exhaust particles. Exposure to ambient air particles is associated with accelerated progression of atherosclerosis and vasomotor dysfunction in both healthy and susceptible animal models and humans at risk of developing cardiovascular diseases. The vasomotor dysfunction includes increased vasoconstriction as well as reduced endothelium-dependent vasodilatation; endothelium-independent vasodilatation is often unaffected indicating mainly endothelial dysfunction. Pulmonary exposure to TiO(2), carbon black, and engineered nanoparticles generate vasomotor dysfunction; the effect size is similar to that generated by combustion-derived particles, although the effect could depend on the exposure period and the administered dose, route, and mode. The relative risk associated with exposure to nanoparticles may be small compared to some traditional risk factors for cardiovascular diseases, but superimposed on these and possible exposure to large parts of the population it is a significant public health concern. Overall, assessment of vasomotor dysfunction and progression of atherosclerosis are promising tools for understanding the effects of particulate matter.

c-Src-mediated activation of Erk1/2 is a reaction of epithelial cells to carbon nanoparticle treatment and may be a target for a molecular preventive strategy

Owing to their specific physico/chemical properties, engineered as well as environmental nanoparticles can induce pathogenic endpoints in humans. Earlier studies demonstrated that pure carbon nanoparticles induce cell signaling events at the level of membrane receptor activation in lung epithelial cells. As a possible link between receptor activation and subsequent MAP-kinase signaling, the involvement of Src family kinases was investigated in cell lines of organs potentially exposed to environmental nanoparticles. Human cells from bronchus, intestine, and skin (keratinocytes) as well as rat lung epithelial cells showed similar time patterns for the activation of mitogen-activated protein kinases Erk1/2 as well as Src family kinases (SFK) when treated with carbon nanoparticles. Moreover, c-Src was identified as an integral part of the signaling mediating the transfer of information from membrane receptors to members of the proliferative signaling cascade in lung epithelial cells. Pretreatment of cells with the compatible solute ectoine, which is known to stabilize macromolecules, reduced the nanoparticle specific phosphorylation of SFK. Together with earlier in vivo and in vitro data, this demonstrates that compatible solutes prevent nanoparticle-induced signaling steps at the level of membrane-coupled signaling.

Combined cytotoxic and anti-invasive properties of redox-active nanoparticles in tumor-stroma interactions

Tumor-stroma interaction plays an important role in tumor progression. Myofibroblasts, pivotal for tumor progression, populate the microecosystem of reactive stroma. The formation of myofibroblasts is mediated by tumor derived transforming growth factor β1 (TGFβ1) which initiates a reactive oxygen species cell type dependent expression of alpha-smooth muscle actin, a biomarker for myofibroblastic cells. Myofibroblasts express and secrete proinvasive factors significantly increasing the invasive capacity of tumor cells via paracrine mechanisms. Although antioxidants prevent myofibroblast formation, the same antioxidants increase the aggressive behavior of the tumor cells. In this study, the question was addressed of whether redox-active polymer-coated cerium oxide nanoparticles (CNP, nanoceria) affect myofibroblast formation, cell toxicity, and tumor invasion. Herein, nanoceria downregulate both the expression of alpha-smooth muscle actin positive myofibroblastic cells and the invasion of tumor cells. Furthermore, concentrations of nanoceria being non-toxic for normal (stromal) cells show a cytotoxic effect on squamous tumor cells. The treatment with redox-active CNP may form the basis for protection of stromal cells from the dominating influence of tumor cells in tumor-stroma interaction, thus being a promising strategy for chemoprevention of tumor invasion.

Oxidative stress, DNA damage, and inflammation induced by ambient air and wood smoke particulate matter in human A549 and THP-1 cell lines

Combustion of biomass and wood for residential heating and/or cooking contributes substantially to both ambient air and indoor levels of particulate matter (PM). Toxicological characterization of ambient air PM, especially related to traffic, is well advanced, whereas the toxicology of wood smoke PM (WSPM) is poorly assessed. We assessed a wide spectrum of toxicity end points in human A549 lung epithelial and THP-1 monocytic cell lines comparing WSPM from high or low oxygen combustion and ambient PM collected in a village with many operating wood stoves and from a rural background area. In both cell types, all extensively characterized PM samples (1.25-100 μg/mL) induced dose-dependent formation of reactive oxygen species and DNA damage in terms of strand breaks and formamidopyrimidine DNA glycosylase sites assessed by the comet assay with WSPM being most potent. The WSPM contained more polycyclic aromatic hydrocarbons (PAH), less soluble metals, and expectedly also had a smaller particle size than PM collected from ambient air. All four types of PM combined increased the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine dose-dependently in A549 cells, whereas there was no change in the levels of etheno-adducts or bulky DNA adducts. Furthermore, mRNA expression of the proinflammatory genes monocyte chemoattractant protein-1, interleukin-8, and tumor necrosis factor-α as well as the oxidative stress gene heme oxygenase-1 was upregulated in the THP-1 cells especially by WSPM and ambient PM sampled from the wood stove area. Expression of oxoguanine glycosylase 1, lymphocyte function-associated antigen-1, and interleukin-6 did not change. We conclude that WSPM has small particle size, high level of PAH, low level of water-soluble metals, and produces high levels of free radicals, DNA damage as well as inflammatory and oxidative stress response gene expression in cultured human cells.

Cytotoxic, genotoxic and pro-inflammatory effects of zinc oxide nanoparticles in human nasal mucosa cells in vitro

Despite increasing application of zinc oxide nanoparticles (ZnO-NPs) for industrial purposes, data about potential toxic properties is contradictory. The current study focused on the cyto- and genotoxicity of ZnO-NPs in comparison to ZnO powder in primary human nasal mucosa cells cultured in the air-liquid interface. Additionally, IL-8 secretion as a marker for pro-inflammatory effects was measured. Particle morphology and intracellular distribution were evaluated by transmission electron microscopy (TEM). ZnO-NPs were transferred into the cytoplasm in 10% of the cells, whereas an intranuclear distribution could only be observed in 1.5%. While no cyto- or genotoxicity could be seen for ZnO powder in the dimethylthiazolyl-diphenyl-tetrazolium-bromide (MTT) test, the trypan blue exclusion test, and the single-cell microgel electrophoresis (comet) assay, cytotoxic effects were shown at a ZnO-NP concentration of 50 μg/ml (P<0.01). A significant enhancement in DNA damage was observed starting from ZnO-NP concentrations of 10 μg/ml (P<0.05) in comparison to the control. IL-8 secretion into the basolateral culture medium was increased at ZnO-NP concentrations of 5 μg/ml (P<0.05), as shown by ELISA. Our data indicates cyto- and genotoxic properties as well as a pro-inflammatory potential of ZnO-NPs in nasal mucosa cells. Thus, caution should be taken concerning their industrial and dermatological application. Additionally, further investigation on repetitive NP exposure is needed to estimate the impact of repair mechanisms.

Oxidative stress mediates the effects of Raman-active gold nanoparticles in human cells

Polyethylene glycol (PEG)ylated Raman-active gold nanoparticles (PEG-R-AuNPs) consist of an interchangeable Raman organic molecule layer held onto a gold nanocore by a silica shell. PEG-R-AuNPs have been shown preclinically to increase the sensitivity and specificity of Raman spectroscopy, with picomolar sensitivity and multiplexing capabilities. Although clinical trials are being designed to use functionalized PEG-R-AuNPs in various applications (e.g., to target dysplastic bowel lesions during colonoscopy), the effects of these nanoparticles on human cells remain unknown. The occurrence and mechanisms underlying any potential cytotoxicity induced by these nanoparticles (0-1000 PEG-R-AuNPs/cell) are investigated in immortalized human HeLa and HepG2 cell lines at several time points (0-48 h) after exposure. Using fluorometric assays, cell viability (MTT), reactive oxygen species (ROS) generation (dichlorofluorescein diacetate), protein oxidation (protein carbonyl content), and total cellular antioxidant concentrations the concentrations (metmyoblobin-induced oxidation of ABTS) are assessed. Analysis of lipid oxidation using an enzyme immunoassay (8-isoprostane concentrations), gene expression of antioxidant enzymes using quantitative reverse transcription polymerase chain reactions, and the intracellular location of PEG-R-AuNPs using transmission electron microscopy is also undertaken. PEG-R-AuNPs cause no cytotoxicity in either HeLa or HepG2 cells in the acute setting as ROS generation is balanced by antioxidant enzyme upregulation. Following prolonged exposures (48 h) at relatively high concentrations (1000 PEG-R-AuNPs/cell), nanoparticles are found within vesicles inside cells. Under these conditions, a minimal amount of cytotoxicity is seen in both cell lines owing to increases in cellular oxidative stress, most likely due to ROS overwhelming the antioxidant defenses. Evidence of oxidative stress-induced damage includes increased lipid and protein oxidation. Although further in vivo toxicity studies are necessary, these initial encouraging results show that PEG-R-AuNPs cause minimal toxicity in human cells in the acute setting, which bodes well for potential future applications of these nanoparticles in living subjects.

Genotoxicity of metal nanoparticles

Nanotechnology is currently used in industry, medicine, and military applications, as well as in more than 300 commercial products. Yet, the same properties that make these particles exciting for technology also make them daunting public health concerns because their toxicity is unknown and relatively unexplored. Increased attention is being placed on the study of metal particle genotoxicity; however, a lot of unknowns remain about their effects and the mechanisms. In this article, we highlight some metal and metal oxide nanoparticles of interest and discuss the current in vivo and in vitro studies of genotoxic effects. Many metal nanoparticles were found to cause chromosomal aberrations, DNA strand breaks, oxidative DNA damage, and mutations. Inconsistencies are found in the literature, however, thus drawing conclusions is difficult due to a variety of factors. Therefore, the areas requiring further attention are highlighted and recommendations to improve our understanding of the genotoxic potential are addressed.

Effects of diesel particulate matters on inflammatory responses in static and dynamic culture of human alveolar epithelial cells

Diesel particulate matter (DPM) possesses the potential to induce acute and chronic health issues upon occupational and daily exposure. Many recent studies have focused on understanding molecular mechanisms to depict DPM's side effects inside the lung using static in vitro cell culture models. These studies have provided abundant fundamental information on DPM's adverse effects on cellular responses, but these systems were limited by the absence of dynamic nature to access relevant cellular responses and functionality. We hypothesized that the exposure of DPM under dynamic environment may affect the levels of cellular inflammation and reactive oxygen species, which may be different from those under static environments. In this study, we used the dynamic cell growth condition to mimic mechanically dynamic environment similar to the normal breathing in vivo. We also used high (20, 10, and 5 ppm) and low (3, 1, 0.1, and 0.01 ppm) ranges of DPM exposure to mimic different levels of exposure, respectively. Following 24-, 48-, and 72-h exposure of DPM, Interleukin-8 (IL-8), C-reactive protein (CRP), reactive oxygen species (ROS), and total amount of protein were analyzed. Our results demonstrated the distinct differences in the profiles of inflammatory mediators (IL-8, CRP, and ROS) between the static and dynamic cell growth conditions.

Oxidative stress, inflammation, and DNA damage in rats after intratracheal instillation or oral exposure to ambient air and wood smoke particulate matter

Wood combustion is a significant source of ambient particulate matter (PM) in many regions of the world. Exposure occurs through inhalation or ingestion after deposition of wood smoke particulate matter (WSPM) on crops and food. We investigated effects of ambient PM and WSPM by intragastric or intratracheal exposure in terms of oxidative stress, inflammation, genotoxicity, and DNA repair after 24 h in liver and lung tissue of rats. Rats were exposed to WSPM from high or low oxygen combustion and ambient PM collected in areas with and without many operating wood stoves or carbon black (CB) at the dose of 0.64 mg/kg body weight. The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine, 1,N(6)-etheno-2'-deoxyadenosine, and 1-N(2)-etheno-2'-deoxyguanosine (εdG) were significantly increased with 23% (95% confidence interval [CI]: 0.1-45%), 54% (95% CI:18-90%), and 73% (95% CI: 31-134%) in the liver of rats exposed orally to CB, respectively. Rats orally exposed to PM from the wood stove area and low oxygen combustion WSPM (LOWS) had 35% (95% CI: 0.1-71%) and 45% (95% CI: 10-82%) increased levels of εdG in the liver, respectively. No significant differences were observed for bulky DNA adducts. Increased gene expression of proinflammatory cytokines, heme oxygenase-1, and oxoguanine DNA glycosylase 1 was observed in the liver following intragastric exposure and in the lung following instillation in particular of LOWS. Exposure to LOWS also increased the proportion of neutrophils in BAL fluid. These results indicate that WSPM and CB exert the strongest effect in terms of oxidative stress-induced response, inflammation, and genotoxicity in the organ closest to the port of entry.

Oxidative damage to DNA and lipids as biomarkers of exposure to air pollution

BACKGROUND

Air pollution is thought to exert health effects through oxidative stress, which causes damage to DNA and lipids.

OBJECTIVE

We determined whether levels of oxidatively damaged DNA and lipid peroxidation products in cells or bodily fluids from humans are useful biomarkers of biologically effective dose in studies of the health effects of exposure to particulate matter (PM) from combustion processes.

DATA SOURCES

We identified publications that reported estimated associations between environmental exposure to PM and oxidative damage to DNA and lipids in PubMed and EMBASE. We also identified publications from reference lists and articles cited in the Web of Science.

DATA EXTRACTION

For each study, we obtained information on the estimated effect size to calculate the standardized mean difference (unitless) and determined the potential for errors in exposure assessment and analysis of each of the biomarkers, for total and stratified formal meta-analyses.

DATA SYNTHESIS

In the meta-analysis, the standardized mean differences (95% confidence interval) between exposed and unexposed subjects for oxidized DNA and lipids were 0.53 (0.29-0.76) and 0.73 (0.18-1.28) in blood and 0.52 (0.22-0.82) and 0.49 (0.01-0.97) in urine, respectively. The standardized mean difference for oxidized lipids was 0.64 (0.07-1.21) in the airways. Restricting analyses to studies unlikely to have substantial biomarker or exposure measurement error, studies likely to have biomarker and/or exposure error, or studies likely to have both sources of error resulted in standardized mean differences of 0.55 (0.19-0.90), 0.66 (0.37-0.95), and 0.65 (0.34-0.96), respectively.

CONCLUSIONS

Exposure to combustion particles is consistenly associated with oxidatively damaged DNA and lipids in humans, suggesting that it is possible to use these measurements as biomarkers of biologically effective dose.

A new class of human mast cell and peripheral blood basophil stabilizers that differentially control allergic mediator release

Treatments for allergic disease block the effects of mediators released from activated mast cells and blood basophils. A panel of fullerene derivatives was synthesized and tested for their ability to preempt the release of allergic mediators in vitro and in vivo. The fullerene C(70)-tetraglycolic acid significantly inhibited degranulation and cytokine production from mast cells and basophils, while C(70)-tetrainositol blocked only cytokine production in mast cells and degranulation and cytokine production in basophils. The early phase of FcepsilonRI inhibition was dependent on the blunted release of intracellular calcium stores, elevations in reactive oxygen species, and several signaling molecules. Gene microarray studies further showed the two fullerene derivatives inhibited late phase responses in very different ways. C(70)-tetraglycolic acid was able to block mast cell-driven anaphylaxis in vivo, while C(70)-tetrainositol did not. No toxicity was observed with either compound. These findings demonstrate the biological effects of fullerenes critically depends on the moieties added to the carbon cage and suggest they act on different FcepsilonRI-specific molecules in mast cells and basophils. These next generation fullerene derivatives represent a new class of compounds that interfere with FcepsilonRI signaling pathways to stabilize mast cells and basophils. Thus, fullerene-based therapies may be a new approach for treating allergic diseases.

Indoor air pollution from unprocessed solid fuels in developing countries

Approximately half of the world's population relies on biomass (primarily wood and agricultural residues) or coal fuels (collectively termed solid fuels) for heating, lighting, and cooking. The incomplete combustion of such materials releases byproducts with well-known adverse health effects, hence increasing the risk of many diseases and death. Among these conditions are acute respiratory infections, chronic obstructive pulmonary disease, heart disease, stroke, lung cancer, cataracts and blindness, tuberculosis, asthma, and adverse pregnancy outcomes. The International Agency for Research on Cancer has classified the indoor combustion of coal emissions as Group 1, a known carcinogen to humans. Indoor air pollution exposure is greatest in individuals who live in rural developing countries. Interventions have been limited and show only mixed results. To reduce the morbidity and mortality from indoor air pollution, countermeasures have to be developed that are practical, efficient, sustainable, and economical with involvement from the government, the commercial sector, and individuals. This review focuses on the contribution of solid fuels to indoor air pollution.

The impact of nanomaterials in immune system

As a nanotechnology has been actively applied to the overall areas of scientific fields, it is necessary to understand the characteristic features, physical behaviors and the potential effects of exposure to nanomaterials and their toxicity. In this article we review the immunological influences induced by several nanomaterials and emphasize establishment of the animal models to estimate the impact of these nanomaterials on development of immunological diseases.

Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association

In 2004, the first American Heart Association scientific statement on "Air Pollution and Cardiovascular Disease" concluded that exposure to particulate matter (PM) air pollution contributes to cardiovascular morbidity and mortality. In the interim, numerous studies have expanded our understanding of this association and further elucidated the physiological and molecular mechanisms involved. The main objective of this updated American Heart Association scientific statement is to provide a comprehensive review of the new evidence linking PM exposure with cardiovascular disease, with a specific focus on highlighting the clinical implications for researchers and healthcare providers. The writing group also sought to provide expert consensus opinions on many aspects of the current state of science and updated suggestions for areas of future research. On the basis of the findings of this review, several new conclusions were reached, including the following: Exposure to PM <2.5 microm in diameter (PM(2.5)) over a few hours to weeks can trigger cardiovascular disease-related mortality and nonfatal events; longer-term exposure (eg, a few years) increases the risk for cardiovascular mortality to an even greater extent than exposures over a few days and reduces life expectancy within more highly exposed segments of the population by several months to a few years; reductions in PM levels are associated with decreases in cardiovascular mortality within a time frame as short as a few years; and many credible pathological mechanisms have been elucidated that lend biological plausibility to these findings. It is the opinion of the writing group that the overall evidence is consistent with a causal relationship between PM(2.5) exposure and cardiovascular morbidity and mortality. This body of evidence has grown and been strengthened substantially since the first American Heart Association scientific statement was published. Finally, PM(2.5) exposure is deemed a modifiable factor that contributes to cardiovascular morbidity and mortality.