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Because of their unique optical properties, quantum dots (QDs) have become a preferred system for ultrasensitive detection and imaging. However, since QDs commonly contain Cd and other heavy metals, concerns have been raised regarding their toxicity. QDs are thus commonly synthesised with a ZnS cap structure and/or coated with polymeric stabilisers. We recently synthesised amphiphilic polymer-coated tri-n-octylphosphine oxide - poly(maleic anhydride-alt-1-tetradecene (TOPO-PMAT) QDs, which are highly stable in aqueous environments. The effects of these QDs on viability and stress response in five cell lines of mouse and human origins are reported here. Human and mouse macrophages and human kidney cells readily internalised these QDs, resulting in modest toxicity. TOPO-PMAT QD exposure was highly correlated with the induction of the stress response protein heme oxygenase-1 (HMOX1). Other stress biomarkers (glutamate cysteine ligase modifier subunit, NAD(P)H, necrosis) were only moderately affected. HMOX1 may thus be a useful biomarker of TOPO-QDOT QD exposure across cell types and species. [ABSTRACT FROM AUTHOR]

Context: Inhalation of ambient fine particulate matter (PM2.5) is associated with adverse respiratory and cardiovascular effects. A major fraction of PM2.5 in urban settings is diesel exhaust particulate (DEP), and DEP-induced lung inflammation is likely a critical event mediating many of its adverse health effects. Oxidative stress has been proposed to be an important factor in PM2.5-induced lung inflammation, and the balance between pro- and antioxidants is an important regulator of this inflammation. An important intracellular antioxidant is the tripeptide thiol glutathione (GSH). Glutamate cysteine ligase (GCL) carries out the first step in GSH synthesis. In humans, relatively common genetic polymorphisms in both the catalytic (Gclc) and modifier (Gclm) subunits of GCL have been associated with increased risk for lung and cardiovascular diseases. Objective: This study was aimed to determine the effects of Gclm expression on lung inflammation following DEP exposure in mice. Materials and methods: We exposed Gclm wild type, heterozygous, and null mice to DEP via intranasal instillation and assessed lung inflammation as determined by neutrophils and inflammatory cytokines in lung lavage, inflammatory cytokine mRNA levels in lung tissue, as well as total lung GSH, Gclc, and Gclm protein levels. Results: The Gclm heterozygosity was associated with a significant increase in DEP-induced lung inflammation when compared to that of wild type mice. Discussion and conclusion: This finding indicates that GSH synthesis can mediate DEP-induced lung inflammation and suggests that polymorphisms in Gclm may be an important factor in determining adverse health outcomes in humans following inhalation of PM2.5. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) is a major player in cellular defense against oxidative stress. Deletion of the modifier subunit of glutamate cysteine ligase (GCLM), the first and the rate-limiting enzyme in the synthesis of GSH, leads to significantly lower GSH levels in all tissues including the brain. GCLM-knockout (Gclm-/-) mice may thus represent a model for compromised response to oxidative stress amenable to in vitro and in vivo investigations. In order to determine whether the diminished GSH content would by itself cause behavioral alterations, a series of behavioral tests were carried out comparing young adult Gclm-/- with wild-type mice. Tests included the rotarod, acoustic startle reflex and prepulse inhibition of the startle reflex, open field behavior, and the platform reversal variant of the Morris Water Maze. Results showed no differences between Gclm-/- and wild-type mice in any of the neurobehavioral tests. However, more subtle alterations, or changes which may appear as animals age, cannot be excluded. [ABSTRACT FROM AUTHOR]

Abstract: Polybrominated diphenyl ether (PBDE) flame retardants have become widespread environmental contaminants. Body burden in the U.S. population has been shown to be higher than in other countries, and infants and toddlers have highest exposure through maternal breast milk and household dust. The primary concern for adverse health effects of PBDEs relates to their potential developmental neurotoxicity, which has been found in a number of animal studies. Information on the possible mechanisms of PBDE neurotoxicity is limited, though some studies have suggested that PBDEs may elicit oxidative stress. The present study examined the in vitro neurotoxicity of DE-71, a penta-BDE mixture, in primary neurons and astrocytes obtained from wild-type and Gclm knockout mice, which lack the modifier subunit of glutamate–cysteine ligase and, as a consequence, have very low levels of glutathione (GSH). These experiments show that neurotoxicity of DE-71 in these cells is modulated by cellular GSH levels. Cerebellar granule neurons (CGNs) from Gclm (−/−) mice displayed a higher sensitivity to DE-71 toxicity compared to CGNs from wild-type animals. DE-71 neurotoxicity in CGNs from Gclm (+/+) mice was exacerbated by GSH depletion, and in CGNs from both genotypes it was antagonized by increasing GSH levels and by antioxidants. DE-71 caused an increase in reactive oxygen species and in lipid peroxidation in CGNs, that was more pronounced in Gclm (−/−) mice. Toxicity of DE-71 was mostly due to the induction of apoptotic cell death. An analysis of DE-71-induced cytotoxicity and apoptosis in neurons and astrocytes from different brain areas (cerebellum, hippocampus, cerebral cortex) in both mouse genotypes showed a significant correlation with intracellular GSH levels. As an example, DE-71 caused cytotoxicity in hippocampal neurons with IC50s of 2.2 and 0.3 μM, depending on genotype, and apoptosis with IC50s of 2.3 and 0.4 μM, respectively. These findings suggest that the developmental neurotoxicity of PBDE may involve oxidative stress, and that individual with genetic polymorphisms leading to lower GSH levels may be more susceptible to their adverse effects. [Copyright &y& Elsevier]

Abstract: Phospholipid hydroperoxide glutathione peroxidase (GPx4) is a member of the family of selenium-dependent enzymes that catalyze the reduction of cell membrane-bound phospholipid hydroperoxides in situ and thus protects against membrane damage. Overexpression of GPx4 protects cultured cells from phosphatidylcholine hydroperoxide (PCOOH)-induced loss of mitochondrial membrane potential and blocks cell death induced by treatment with various apoptotic agents. We have generated mice that are heterozygous for a GPx4 null allele (GPx4 +/-); the homozygous null genotype is embryonic lethal. We report that cultured lung fibroblasts (LFs) isolated from adult GPx4 +/- mice had approximately 50% of the GPx4 activity of LFs from GPx4 +/+ mice and were significantly more susceptible to H2O2, cadmium, and cumene hydroperoxide-induced cytotoxicity, as measured by neutral red assay. Both GPx4 +/+ and GPx4 +/- LFs were susceptible to PCOOH-induced cytotoxicity at a high PCOOH concentration. We also found that GPx4 +/- LFs have lower mitochondrial membrane potential, greater cardiolipin oxidation, and lower amounts of reduced thiols relative to GPx4 +/+ LFs, but are more resistant than GPx4 +/+ LFs to further decrements in these endpoints following PCOOH treatment. These results suggest that adult lung fibroblasts deficient in GPx4 may have upregulated compensatory mechanisms to deal with the highly oxidized environment in which they developed. [Copyright &y& Elsevier]

Exposure of mouse cerebellar granule neurons (CGNs) to domoic acid induced cell death, either by apoptosis or by necrosis, depending on its concentration. Necrotic damage predominated in response to domoic acid above 0.1μM. In contrast, cell injury with apoptotic features (assessed by Hoechst staining and DNA laddering assay) was evident after exposure to lower concentrations of domoic acid (≤ 0.1μM). The AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptor antagonist 2,3-dihydroxy-6-nitro-sulfamoylbenzo [f] quinoxaline, but not the N-methyl-D-aspartate receptor antagonist MK-801, prevented domoic acid–induced apoptosis. To evaluate the role of oxidative stress in domoic acid–induced apoptosis, experiments were carried out in CGNs isolated from wild-type mice (Gclm (+/+)) and mice lacking the modifier subunit of glutamate-cysteine ligase, the first and rate-limiting step of glutathione (GSH) biosynthesis (Gclm (−/−)). CGNs from Gclm (−/−) mice have very low levels of GSH and were more sensitive to domoic acid–induced apoptosis and necrosis than Gclm (+/+) CGNs. The antioxidant melatonin (200μM) and the membrane-permeant GSH delivery agent GSH ethyl ester (2.5mM) prevented domoic acid–induced apoptosis. Domoic acid increased formation of reactive oxygen species but did not affect intracellular GSH levels. Domoic acid also increased cytosolic and mitochondrial calcium levels, increased oxidative stress in mitochondria, and altered mitochondrial membrane potential, which ultimately caused cytochrome c release, activation of caspase-3, and degradation of poly (ADP-ribose) polymerase. These results indicate that low concentrations of domoic acid cause apoptotic neuronal cell death mediated by oxidative stress. [ABSTRACT FROM PUBLISHER]

The analgesic and antipyretic drug acetaminophen (APAP) is bioactivated to the reactive intermediate N-acetyl-p-benzoquinoneimine, which is scavenged by glutathione (GSH). APAP overdose can deplete GSH leading to the accumulation of APAP–protein adducts and centrilobular necrosis in the liver. N-acetylcysteine (NAC), a cysteine prodrug and GSH precursor, is often given as a treatment for APAP overdose. The rate-limiting step in GSH biosynthesis is catalyzed by glutamate cysteine ligase (GCL) a heterodimer composed of catalytic and modifier (GCLM) subunits. Previous studies have indicated that GCL activity is likely to be an important determinant of APAP toxicity. In this study, we investigated APAP toxicity, and NAC or GSH ethyl ester (GSHee)–mediated rescue in mice with normal or compromised GCLM expression. Gclm wild-type, heterozygous, and null mice were administered APAP (500 mg/kg) alone, or immediately following NAC (800 mg/kg) or GSHee (168 mg/kg), and assessed for hepatotoxicity 6 h later. APAP caused GSH depletion in all mice. Gclm null and heterozygous mice exhibited more extensive hepatic damage compared to wild-type mice as assessed by serum alanine aminotransferase activity and histopathology. Additionally, male Gclm wild-type mice demonstrated greater APAP-induced hepatotoxicity than female wild-type mice. Cotreatment with either NAC or GSHee mitigated the effects of APAP in Gclm wild-type and heterozygous mice, but not in Gclm null mice. Collectively, these data reassert the importance of GSH in protection against APAP-induced hepatotoxicity, and indicate critical roles for GCL activity and gender in APAP-induced liver damage in mice. [ABSTRACT FROM PUBLISHER]

Tetrafluoroethylcysteine (TFEC), a metabolite of the industrial gas tetrafluoroethylene, can cause both nephrotoxicity and limited hepatotoxicity in animal models, and this is associated with the covalent modification of specific intramitochondrial proteins including heat shock protein 60 (HSP60), mitochondrial HSP70 (mtHSP70), aspartate aminotransferase (AST), aconitase, and α-ketoglutarate dehydrogenase (αKGDH). Using the murine TAMH cell line as a useful in vitro model for TFEC toxicity, we demonstrate a rapid and sustained induction of Nrf2, a member of the “cap-and-collar” transcription factor family, following exposure to cytotoxic concentrations of TFEC. A functional correlate was also established with the rapid translocation of cytosolic Nrf2 into the nucleus. In addition, transcriptional and translational upregulation of known Nrf2 regulated genes including glutamate cysteine ligase (GCL), both catalytic and modulatory subunits, heme oxygenase-1, and glutathione S-transferase (GST) isoforms were detected. While Nrf2 activation is often linked to perturbation of cellular thiol status and/or oxidative stress, we were unable to detect any significant depletion of cellular glutathione or oxidation of mitochondrial membrane cardiolipin or increases in reactive oxygen species (ROS). These data suggest Nrf2 activation is likely independent of classical oxidative stress or, at best, a result of a transient, low-level redox stress. Moreover, supporting evidence indicates an early endoplasmic reticular (ER) stress response after TFEC treatment, with a time-dependent upregulation of the ER responsive genes gadd34, gadd45, gadd153, and ndr1 . These findings suggest an alternative pathway for Nrf2 activation, i.e., Nrf2 phosphorylation through ER-mediated protein kinases such as PKR-like endoplasmic reticular kinase (PERK). Overall, the results implicate a role for Nrf2 in the cellular response to TFEC toxicity and suggest a previously unrecognized role for the ER in this model of mitochondrially initiated cytotoxicity. [ABSTRACT FROM AUTHOR]

The antioxidant tripeptide glutathione has been proposed to be important in defense against oxidative stress and heavy metal toxicity. We evaluated alterations in glutathione regulation and synthesis associated with low-level chronic methylmercury (MeHg) exposure in the developing mouse fetus. Female C57Bl/6 mice were given 0, 3, or 10 ppm MeHg in the drinking water for 2 weeks prior to breeding and throughout pregnancy. Fetuses were collected on gestational days (gd) 12 and 16. Total glutathione, reduced glutathione (GSH), oxidized glutathione (GSSR), and glutamate-L-cysteine ligase (Glcl) activity were assessed in yolk sacs and fetuses at gd 16. Western and Northern blots for Glcl-catalytic (Glclc) and Glcl-regulatory (Glclr) subunits were performed on gd 12 and gd 16 fetuses. There were no changes in total glutathione in gd 16 mouse fetuses with exposure, but there were dose-related decreases in GSH and increases in GSSR. In contrast, visceral yolk sacs exhibited an increase in total glutathione in the low-dose groups, but no changes in the high-dose group. There were no changes in Glcl activity in fetuses, but there was a 2-fold increase in Glcl activity in yolk sacs from both low-dose and high-dose groups. There was a 2-fold induction in Glclc mRNA and protein in the gd 16 yolk sacs at both 3 and 10 ppm MeHg. No treatment-related changes in Glclr protein in either gd 12 or gd 16 yolk sacs or fetuses were found. Thus, the yolk sac is capable of up-regulating Glclc and GSH synthetic capacity in response to MeHg exposure. This increase appears to be sufficient to resist MeHg-induced GSH depletion in the yolk sac; however fetal glutathione redox status is compromised with exposure to 10 ppm MeHg. [ABSTRACT FROM PUBLISHER]

Provides information on a study that elucidated the molecular mechanisms mediating transforming growth factorβ1 (TGFΒ1)-induced hepatocyte apoptosis and determined whether suppression of glutathione biosynthesis may play a role in TGFΒ1-induced apoptotic cell death. Findings of the study; Conclusions.

Silver nanoparticles (AgNPs) are widely used in consumer and pharmaceutical products due to their antipathogenic properties. However, safety concerns have been raised due to their bioactive properties. While reports have demonstrated AgNPs can embed within the extracellular matrix, their effects on basement membrane (BM) production, integrin engagement, and tissue-integrity are not well-defined. This study analyzed the effects of AgNPs on BM production, composition and integrin/focal adhesion interactions in representative lung, esophageal, breast and colorectal epithelia models. A multidisciplinary approach including focused proteomics, QPCR arrays, pathway analyses, and immune-based, structural and functional assays was used to identify molecular and physiological changes in cell adhesions and the BM induced by acute and chronic AgNP exposure. Dysregulated targets included CD44 and transforming growth factor-beta, two proteins frequently altered during pathogenesis. Results indicate AgNP exposure interferes with BM and cell adhesion dynamics, and provide insight into the mechanisms of AgNP-induced disruption of epithelial physiology. The effect of silver nanoparticles (AgNP) on epithelial cell basement membrane (BM) production, composition and barrier integrity is not well-defined. BM-focused proteomics, quantitative PCR and pathway analysis identified specific acute and chronic AgNP-sensitive targets in normal lung, esophageal, colon and breast epithelial cell models. Immunological, functional and structural assays suggest caveolae-mediated AgNP uptake, loss of barrier function, altered collagen fiber organization and composition, and dysregulated CD44 and TGFβ all significantly modify epithelial physiology. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract: Control of vascular insufficiencies due to various cardiovascular pathologies is important for developing specific and effective treatments. Fluctuations in oxidative stress significantly alter the progression of angiogenesis under physiological and pathological conditions. However, the precise amount of reactive oxygen species (ROS) required to influence subsequent signaling pathways for ischemic angiogenesis remains undefined. Here, we have determined the effect of ROS-mediated molecular mechanisms on angiogenesis in a murine model of peripheral artery disease using Gclm mutant mice (a model of compromised glutathione synthesis and therefore reduced antioxidant capacity). Left femoral artery ligation and excision were performed in Gclm WT (+/+), heterozygous (+/−), and null (−/−) mice. Blood flow (laser Doppler), angiogenic index (CD31/DAPI), and proliferation index (Ki67/DAPI) were significantly increased in Gclm+/− mice but not in Gclm+/+ or Gclm−/− mice. Measurements of reactive oxygen species suggest that the amount of superoxide required to stimulate angiogenesis after the induction of ischemia is 9.82pmol/mg of tissue. Protein carbonyl levels increased in a manner consistent with increasing oxidative stress. Superoxide and protein carbonyl levels were reduced by the addition of the nitroxide tempol, a known superoxide dismutase mimetic. Finally, restoration of blood flow in Gclm+/− mice was attenuated by a VEGF164 aptamer, verifying that slightly elevated levels of ROS restore blood flow by stimulating endothelial cell proliferation through a VEGF-dependent pathway. The results of this study reveal new information on the amount of ROS necessary for angiogenic activity and provide the foundation of critical redox parameters for vascular remodeling responses. The information obtained from this study on vascular ischemia, using a model of decreased antioxidant capacity, has provided insight into the control of revascularization and is a step forward in our ability to regulate angiogenic therapies. [Copyright &y& Elsevier]

Abstract: Traffic related particulate matter air pollution is a risk factor for cardiovascular events; however, the biological mechanisms are unclear. We hypothesize that diesel exhaust (DE) inhalation induces up-regulation of inducible nitric oxide synthase (iNOS), which is known to contribute to vascular dysfunction, progression of atherosclerosis and ultimately cardiovascular morbidity and mortality. Methods: ApoE knockout mice (30-week) were exposed to DE (at 200μg/m3 of particulate matter) or filtered-air (control) for 7weeks (6h/day, 5days/week). iNOS expression in the blood vessels and heart was evaluated by immunohistochemistry and western blotting analysis. To examine iNOS activity, thoracic aortae were mounted in a wire myograph, and vasoconstriction stimulated by phenylephrine (PE) was measured with and without the presence of the specific inhibitor for iNOS (1400W). NF-κB (p65) activity was examined by ELISA. The mRNA expression of iNOS and NF-κB (p65) was determined by real-time PCR. Results: DE exposure significantly enhanced iNOS expression in the thoracic aorta (4-fold) and heart (1.5 fold). DE exposure significantly attenuated PE-stimulated vasoconstriction by ~20%, which was partly reversed by 1400W. The mRNA expression of iNOS and NF-κB was significantly augmented after DE exposure. NF-κB activity was enhanced 2-fold after DE inhalation, and the augmented NF-κB activity was positively correlated with iNOS expression (R2 =0.5998). Conclusions: We show that exposure to DE increases iNOS expression and activity possibly via NF-κB-mediated pathway. We suspect that DE exposure-caused up-regulation of iNOS contributes to vascular dysfunction and atherogenesis, which could ultimately lead to urban air pollution-associated cardiovascular morbidity and mortality. [Copyright &y& Elsevier]

Recent evidence suggests that complex diseases can result from early life exposure to environmental toxicants. Polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) and remain a continuing risk to human health despite being banned from production. Developmental BPA exposure mediated-adult onset of liver cancer via epigenetic reprogramming mechanisms has been identified. Here, we investigated whether the gut microbiome and liver can be persistently reprogrammed following neonatal exposure to POPs, and the associations between microbial biomarkers and disease-prone changes in the hepatic transcriptome in adulthood, compared with BPA. C57BL/6 male and female mouse pups were orally administered vehicle, BPA, BDE-99 (a breast milk-enriched PBDE congener), or the Fox River PCB mixture (PCBs), once daily for three consecutive days (postnatal days [PND] 2–4). Tissues were collected at PND5 and PND60. Among the three chemicals investigated, early life exposure to BDE-99 produced the most prominent developmental reprogramming of the gut-liver axis, including hepatic inflammatory and cancer-prone signatures. In adulthood, neonatal BDE-99 exposure resulted in a persistent increase in Akkermansia muciniphila throughout the intestine, accompanied by increased hepatic levels of acetate and succinate, the known products of A. muciniphila. In males, this was positively associated with permissive epigenetic marks H3K4me1 and H3K27, which were enriched in loci near liver cancer-related genes that were dysregulated following neonatal exposure to BDE-99. Our findings provide novel insights that early life exposure to POPs can have a life-long impact on disease risk, which may partly be regulated by the gut microbiome. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNP) are used in multiple applications but primarily in the manufacturing of antimicrobial products. Previous studies have identified AgNP toxicity in airway epithelial cells, but no in vitro studies to date have used organotypic cultures as a high-content in vitro model of the conducting airway to characterize the effects of interactions between host genetic and acquired factors, or gene × phenotype interactions (G × P), on AgNP toxicity. In the present study, we derived organotypic cultures from primary murine tracheal epithelial cells (MTEC) to characterize nominal and dosimetric dose-response relationships for AgNPs with a gold core on barrier dysfunction, glutathione (GSH) depletion, reactive oxygen species (ROS) production, lipid peroxidation, and cytotoxicity across two genotypes (A/J and C57BL/6J mice), two phenotypes ('Normal' and 'Type 2 [T2]-Skewed'), and two exposures (an acute exposure of 24 h and a subacute exposure of 4 h, every other day, over 5 days [5 × 4 h]). We characterized the 'T2-Skewed' phenotype as an in vitro model of chronic respiratory diseases, which was marked by increased sensitivity to AgNP-induced barrier dysfunction, GSH depletion, ROS production, lipid peroxidation, and cytotoxicity, suggesting that asthmatics are a sensitive population to AgNP exposures in occupational settings. This also suggests that exposure limits, which should be based upon the most sensitive population, should be derived using in vitro and in vivo models of chronic respiratory diseases. This study highlights the importance of considering dosimetry as well as G × P effects when screening and prioritizing potential respiratory toxicants. Such in vitro studies can be used to inform regulatory policy aimed at special protections for all populations. [ABSTRACT FROM AUTHOR]

Oxoaldehyde stress has recently emerged as a major source of tissue damage in aging and age‐related diseases. The prevailing mechanism involves methylglyoxal production during glycolysis and modification of arginine residues through the formation of methylglyoxal hydroimidazolones (MG‐H1). We now tested the hypothesis that oxidation of vitamin C (ascorbic acid or ASA) contributes to this damage when the homeostatic redox balance is disrupted especially in ASA‐rich tissues such as the eye lens and brain. MG‐H1 measured by liquid chromatography mass spectrometry is several fold increased in the lens and brain from transgenic mice expressing human vitamin C transporter 2 (hSVCT2). Similarly, MG‐H1 levels are increased two‐ to fourfold in hippocampus extracts from individuals with Alzheimer's disease (AD), and significantly higher levels are present in sarkosyl‐insoluble tissue fractions from AD brain proteins than in the soluble fractions. Moreover, immunostaining with antibodies against methylglyoxal hydroimidazolones reveals similar increase in substantia nigra neurons from individuals with Parkinson's disease. Results from an in vitro incubation experiment suggest that accumulated catalytic metal ions in the hippocampus during aging could readily accelerate ASA oxidation and such acceleration was significantly enhanced in AD. Modeling studies and intraventricular injection of 13C‐labeled ASA revealed that ASA backbone carbons 4–6 are incorporated into MG‐H1 both in vitro and in vivo, likely via a glyceraldehyde precursor. We propose that drugs that prevent oxoaldehyde stress or excessive ASA oxidation may protect against age‐related cataract and neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The airway epithelium is critical for maintaining innate and adaptive immune responses, and occupational exposures that disrupt its immune homeostasis may initiate and amplify airway inflammation. In our previous study, we demonstrated that silver nanoparticles (AgNP), which are engineered nanomaterials used in multiple applications but primarily in the manufacturing of many antimicrobial products, induce toxicity in organotypic cultures derived from murine tracheal epithelial cells (MTEC), and those differentiated toward a "Type 2 [T2]-Skewed" phenotype experienced an increased sensitivity to AgNP toxicity, suggesting that asthmatics could be a sensitive population to AgNP exposures in occupational settings. However, the mechanistic basis for this genotype × phenotype (G × P) interaction has yet to be defined. In this study, we conducted transcriptional profiling using RNA-sequencing to predict the enrichment of specific canonical pathways and upstream transcriptional regulators to assist in defining a mechanistic basis for G × P effects on AgNP toxicity. Organotypic cultures were derived from MTEC across 2 genetically inbred mouse strains (A/J and C57BL/6J mice), 2 phenotypes ("Normal" and "T2-Skewed"), and 1 AgNP exposure (an acute 24 h exposure) to characterize G × P effects on transcriptional response to AgNP toxicity. The "T2-Skewed" phenotype was marked by increased pro-inflammatory T17 responses to AgNP toxicity, which are significant predictors of neutrophilic/difficult-to-control asthma and suggests that asthmatics could be a sensitive population to AgNP exposures in occupational settings. This study highlights the importance of considering G × P effects when identifying these sensitive populations, whose underlying genetics or diseases could directly modify their response to AgNP exposures. [ABSTRACT FROM AUTHOR]

Sarcopenia and exercise intolerance are major contributors to reduced quality of life in the elderly for which there are few effective treatments. We tested whether enhancing mitochondrial function and reducing mitochondrial oxidant production with SS-31 (elamipretide) could restore redox balance and improve skeletal muscle function in aged mice. Young (5 mo) and aged (26 mo) female C57BL/6Nia mice were treated for 8-weeks with 3 mg/kg/day SS-31. Mitochondrial function was assessed in vivo using 31P and optical spectroscopy. SS-31 reversed age-related decline in maximum mitochondrial ATP production (ATPmax) and coupling of oxidative phosphorylation (P/O). Despite the increased in vivo mitochondrial capacity, mitochondrial protein expression was either unchanged or reduced in the treated aged mice and respiration in permeabilized gastrocnemius (GAS) fibers was not different between the aged and aged+SS-31 mice. Treatment with SS-31 also restored redox homeostasis in the aged skeletal muscle. The glutathione redox status was more reduced and thiol redox proteomics indicated a robust reversal of cysteine S-glutathionylation post-translational modifications across the skeletal muscle proteome. The gastrocnemius in the age+SS-31 mice was more fatigue resistant with significantly greater mass compared to aged controls. This contributed to a significant increase in treadmill endurance compared to both pretreatment and untreated control values. These results demonstrate that the shift of redox homeostasis due to mitochondrial oxidant production in aged muscle is a key factor in energetic defects and exercise intolerance. Treatment with SS-31 restores redox homeostasis, improves mitochondrial quality, and increases exercise tolerance without an increase in mitochondrial content. Since elamipretide is currently in clinical trials these results indicate it may have direct translational value for improving exercise tolerance and quality of life in the elderly. fx1 [ABSTRACT FROM AUTHOR]

Abstract Quantum dot nanoparticles (QDs) are engineered nanomaterials (ENMs) that have utility in many industries due to unique optical properties not available in small molecules or bulk materials. QD-induced acute lung inflammation and toxicity in rodent models raise concerns about potential human health risks. Recent studies have also shown that some ENMs can exacerbate allergic airway disease (AAD). In this study, C57BL/6J and A/J mice were exposed to saline, house dust mite (HDM), or a combination of HDM and QDs on day 1 of the sensitization protocol. Mice were then challenged on days 8, 9 and 10 with HDM or saline only. Significant differences in cellular and molecular markers of AAD induced by both HDM and HDM + QD were observed between C57BL/6J and A/J mice. Among A/J mice, HDM + QD co-exposure, but not HDM exposure alone, significantly increased levels of bronchoalveolar lavage fluid (BALF). IL-33 compared to saline controls. BALF total protein levels in both mouse strains were also only significantly increased by HDM + QD co-exposure. In addition, A/J mice had significantly more lung type 2 innate lymphoid cells (ILC2s) cells than C57BL/6J mice. A/J lung ILC2s were inversely correlated with lung glutathione and MHC-IIhigh resident macrophages, and positively correlated with MHC-IIlow resident macrophages. The results from this study suggest that 1) QDs influence HDM-induced AAD by potentiating and/or enhancing select cytokine production; 2) that genetic background modulates the impact of QDs on HDM sensitization; and 3) that potential ILC2 contributions to HDM induced AAD are also likely to be modulated by genetic background. Highlights • Quantum dots (QDs) influence house dust mite-induced allergic airway disease. • QDs can potentiate and/or enhance select cytokine production. • Genetic background modulates QD-effects on HDM sensitization. • ILC2s likely contribute to HDM-induced allergic airway disease. • The impact of ILC2s is also modulated by genetic background. [ABSTRACT FROM AUTHOR]

Behavioral responses inform toxicology studies by rapidly and sensitively detecting molecular initiation events that propagate to physiological changes in individuals. These behavioral responses can be unique to chemical specific mechanisms and modes of action (MOA) and thus present diagnostic utility. In an initial effort to explore the use of larval fish behavioral response patterns in screening environmental contaminants for toxicity and to identify behavioral responses associated with common chemical specific MOAs, we employed the two most common fish models, the zebrafish and the fathead minnow, to define toxicant induced swimming activity alterations during interchanging photoperiods. Though the fathead minnow ( Pimephales promelas ) is a common model for aquatic toxicology research and regulatory toxicology practice, this model has received little attention in behavioral studies compared to the zebrafish, a common biomedical model. We specifically compared behavioral responses among 7 different chemicals (1-heptanol, phenol, R-(-)-carvone, citalopram, diazinon, pentylenetetrazole (PTZ), and xylazine) that were selected and classified based on anticipated MOA (nonpolar narcosis, polar narcosis, electrophile, specific mechanism) according to traditional approaches to examine whether these comparative responses differ among chemicals with various structure-based predicted toxicity. Following standardized experimental guidelines, zebrafish embryos and fathead minnow larvae were exposed for 96 h to each compound then were observed using digital behavioral analysis. Behavioral observations included photomotor responses, distance traveled, and stimulatory, refractory and cruising locomotor activity. Though fathead minnow larvae displayed greater behavioral sensitivity to 1-heptanol, phenol and citalopram, zebrafish were more sensitive to diazinon and R-(-)-carvone. Both fish models were equally sensitive to xylazine and PTZ. Further, the pharmaceuticals citalopram and xylazine significantly affected behavior at therapeutic hazard values, and each of the seven chemicals elicited unique behavioral response profiles. Larval fish behaviors appear useful as early tier diagnostics to identify mechanisms and pathways associated with diverse biological activities for chemicals lacking mechanistic data. [ABSTRACT FROM AUTHOR]

Micromass culture systems have been developed as three-dimensional organotypic in vitro alternatives to test developmental toxicity. We have optimized a murine-based embryonic midbrain micromass system in two genetic strains to evaluate neurodevelopmental effects of gold-cored silver nanoparticles (AgNPs) of differing sizes and coatings—20 nm AgCitrate, 110 nm AgCitrate, and 110 nm AgPVP. AgNPs are increasingly used in consumer, commercial, and medical products for their antimicrobial properties and observations of Ag in adult and fetal brain following in vivo exposures to AgNPs have led to concerns about the potential for AgNPs to elicit adverse effects on neurodevelopment and neurological function. Cytotoxicity was assessed at three time points of development by both nominal dose and by dosimetric dose. Ag dosimetry was assessed in cultures and the gold core component of the AgNPs was used as a tracer for determination of uptake of intact AgNPs and silver dissolution from particles in the culture system. Results by both nominal and dosimetric dose show cell death increased significantly in a dose-dependent manner at later time points (days 15 and 22 in vitro ) that coincide with differentiation stages of development in both strains. When assessed by dosimetric dose, cultures were more sensitive to smaller particles, despite less uptake of Ag in smaller particles in both strains. [ABSTRACT FROM AUTHOR]

Introduction: Concerns have been raised regarding occupational exposure to engineered nanomaterials (ENMs). Potential impacts on lung function from inhalation exposures are of concern as the lung is a sensitive ENM target in animals. Epidemiological data suggest that occupational exposure to ENMs may impact respiratory and cardiovascular health. Quantum dots (QDs) are ENMs with outstanding semiconductor and fluorescent properties with uses in biomedicine and electronics. QDs are known to induce inflammation and cytotoxicity in rodents and high dose exposures impact lung function 2 weeks after exposure. However, effects of mouse strain and the temporality of QD effects on lung function at more occupationally relevant doses have not been well-established. Objective: We evaluated the impact of QD exposure on respiratory mechanics in C57BL/6J and A/J mice. Previous work found a greater initial inflammatory response to QD exposure in A/J mice compared to C57BL/6J mice. Thus, we hypothesized that A/J mice would be more sensitive to QD-induced effects on lung mechanics. Methods: C57BL/6J and A/J mice were exposed to 6 μg/kg Cd equivalents of amphiphilic polymer-coated Cd/Se core, ZnS shell QDs via oropharyngeal aspiration. Lung mechanics were measured using forced oscillation, and inflammation was characterized by neutrophils and cytokines in bronchoalveolar lavage fluid. Results: Both strains showed signs of QD-induced acute lung inflammation. However, lung mechanics were impacted by QD exposure in A/J mice only. Conclusions: Our findings suggest that susceptibility to QDs and similar ENM-induced changes in lung function may depend at least in part on genetic background. [ABSTRACT FROM AUTHOR]

Green chemistry can strongly attract students to chemistry. We, therefore, developed a green chemistry educational game that motivates students at the undergraduate and advanced high school levels to consider green chemistry and sustainability concerns as they design a hypothetical, chemical product. The game is intended for incorporation into any chemistry course for majors and non-majors that teaches sustainability and/or the Principles of Green Chemistry at the undergraduate level. The game is free of charge and encourages students to think like professional chemical designers and to develop a chemical product with respect to function and improved human and environmental health. This computer simulation has been assessed by educators and can be seamlessly integrated into an existing curriculum. [ABSTRACT FROM AUTHOR]

Significance: MicroRNAs (miRNAs) are important regulators of gene expression and define part of the epigenetic signature. Their influence on every realm of biomedicine is established and progressively increasing. The impact of environment on human health is enormous. Among environmental risk factors impinging on quality of life are those of chemical nature (toxic chemicals, heavy metals, pollutants, and pesticides) as well as those related to everyday life such as exposure to noise or mental and psychosocial stress. Recent Advances: This review elaborates on the relationship between miRNAs and these environmental risk factors. Critical Issues: The most relevant facts underlying the role of miRNAs in the response to these environmental stressors, including redox regulatory changes and oxidative stress, are highlighted and discussed. In the cases wherein miRNA mutations are relevant for this response, the pertinent literature is also reviewed. Future Directions: We conclude that, even though in some cases important advances have been made regarding close correlations between specific miRNAs and biological responses to environmental risk factors, a need for prospective large-cohort studies is likely necessary to establish causative roles. Antioxid. Redox Signal. 28, 773-796. [ABSTRACT FROM AUTHOR]

Herein, we provide an overview of a research network that is aimed at fostering interdisciplinary collaboration between chemists and toxicologists with the goal of rationally designing safer commercial chemicals. The collaborative is the Molecular Design Research Network (MoDRN) that was created in 2013 with funding from the EPA-National Science Foundation Networks for Sustainable Molecular Design and Synthesis (NSMDS) program. MoDRN is led by 4 universities, Baylor University, University of Washington, The George Washington University, and Yale University. The overarching goal of the network is to enable and empower the design of safer chemicals based on the fourth Principle of Green Chemistry that states, "chemical products should be designed to preserve efficacy of function while minimizing toxicity." [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are employed in a variety of consumer products; however, in vivo rodent studies indicate that AgNPs can cause lung inflammation and toxicity in a strain- and particle type-dependent manner, but mechanisms of susceptibility remain unclear. The aim of this study was to assess the variation in AgNP-induced lung inflammation and toxicity across multiple inbred mouse strains and to use genome-wide association (GWA) mapping to identify potential candidate susceptibility genes. Mice received doses of 0.25 mg/kg of either 20-nm citrate-coated AgNPs or citrate buffer using oropharyngeal aspiration. Neutrophils in bronchoalveolar lavage fluid (BALF) served as markers of inflammation. We found significant strain- and treatment-dependent variation in neutrophils in BALF. GWA mapping identified 10 significant single-nucleotide polymorphisms (false discovery rate, 15%) in 4 quantitative trait loci on mouse chromosomes 1, 4, 15, and 18, and Nedd4l (neural precursor cell expressed developmentally downregulated gene 4-like; chromosome 18), Ano6 (anocatmin 6; chromosome 15), and Rnf220 (Ring finger protein 220; chromosome 4) were considered candidate genes. Quantitative RT-PCR revealed significant inverse associations between mRNA levels of these genes and neutrophil influx. Nedd4l, Ano6, and Rnf220 are candidate susceptibility genes for AgNP-induced lung inflammation that warrant additional exploration in future studies. [ABSTRACT FROM AUTHOR]

The liver is the main site for drug and xenobiotics metabolism, including inactivation or bioactivation. In order to improve the predictability of drug safety and efficacy in clinical development, and to facilitate the evaluation of the potential human health effects from exposure to environmental contaminants, there is a critical need to accurately model human organ systems such as the liver in vitro . We are developing a microphysiological system (MPS) based on a new commercial microfluidic platform (Nortis, Inc.) that can utilize primary liver cells from multiple species ( e.g. , rat and human). Compared to conventional monolayer cell culture, which typically survives for 5–7 days or less, primary rat or human hepatocytes in an MPS exhibited higher viability and improved hepatic functions, such as albumin production, expression of hepatocyte marker HNF4α and canaliculi structure, for up to 14 days. Additionally, induction of Cytochrome P450 (CYP) 1A and 3A4 in cryopreserved human hepatocytes was observed in the MPS. The acute cytotoxicity of the potent hepatotoxic and hepatocarcinogen, aflatoxin B 1 , was evaluated in human hepatocytes cultured in an MPS, demonstrating the utility of this model for acute hepatotoxicity assessment. These results indicate that MPS-cultured hepatocytes provide a promising approach for evaluating chemical toxicity in vitro . [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are engineered semiconductor nanoparticles with unique physicochemical properties that make them potentially useful in clinical, research and industrial settings. However, a growing body of evidence indicates that like other engineered nanomaterials, QDs have the potential to be respiratory hazards, especially in the context of the manufacture of QDs and products containing them, as well as exposures to consumers using these products. The overall goal of this study was to investigate the role of mouse strain in determining susceptibility to QD-induced pulmonary inflammation and toxicity. Male mice from 8 genetically diverse inbred strains (the Collaborative Cross founder strains) were exposed to CdSe–ZnS core–shell QDs stabilized with an amphiphilic polymer. QD treatment resulted in significant increases in the percentage of neutrophils and levels of cytokines present in bronchoalveolar lavage fluid (BALF) obtained from NOD/ShiLtJ and NZO/HlLtJ mice relative to their saline (Sal) treated controls. Cadmium measurements in lung tissue indicated strain-dependent differences in disposition of QDs in the lung. Total glutathione levels in lung tissue were significantly correlated with percent neutrophils in BALF as well as with lung tissue Cd levels. Our findings indicate that QD-induced acute lung inflammation is mouse strain dependent, that it is heritable, and that the choice of mouse strain is an important consideration in planning QD toxicity studies. These data also suggest that formal genetic analyses using additional strains or recombinant inbred strains from these mice could be useful for discovering potential QD-induced inflammation susceptibility loci. [ABSTRACT FROM AUTHOR]

Polybrominated diphenyl ethers (PBDEs), used for decades as flame retardants, have become widespread environmental contaminants. Exposure is believed to occur primarily through diet and dust, and infants and toddlers have the highest body burden, raising concern for potential developmental neurotoxicity. The exact mechanisms of PBDE neurotoxicity have not been elucidated, but two relevant modes of action relate to impairment of thyroid hormone homeostasis and to direct effects on brain cells causing alterations in signal transduction, oxidative stress and apoptotic cell death. The present study shows that BDE-47 (2,2′,4,4′-tetrabromodiphenyl ether) induces oxidative stress and ensuing apoptotic cell death in mouse cerebellar granule neurons in vitro . Similarly, in vivo administration of BDE-47, according to an exposure protocol shown to induce behavioral and biochemical alterations (10 mg/kg, per os on post-natal day 10), induces oxidative stress and apoptosis, without altering serum levels of thyroid hormones. The effects of BDE-47 both in vitro and in vivo were more pronounced in a mouse model lacking the modifier subunit of glutamate cysteine ligase (GCLM) which results in reduced anti-oxidant capability due to low levels of GSH. Concentrations of BDE-47 in brain were in the mid-nanomolar range. These findings indicate that effects observed with BDE-47 in vitro are also present after in vivo administration, suggesting that in addition to potential endocrine effects, which were not seen here, direct interactions with brain cells should be considered as a potential mechanism of BDE-47 neurotoxicity. [ABSTRACT FROM AUTHOR]