The delivery of doxorubicin of multifunctional β‐cyclodextrin‐modified CdSe/ZnS quantum dots for bioactivity and nano‐probing

The modified quantum dots (QDs) have been used in intracellular probing and drug delivery because of their special chemical and physical properties. In this paper, two β‐cyclodextrin (β‐CD)‐modified CdSe/ZnS QDs with strong optical emission properties were synthesized as drug carriers to induce apoptosis. The positively charged l ‐Arginine (l ‐Arg) and neutral l ‐Tryptophan (l ‐Trp) were selected as ligands to compare the effect of charge on bioactivity of QDs nanoparticles. The in vitro assays revealed that these modified QDs showed good Dox carrier ability and significantly high inhibition rate to cancer cells. Especially, the more positively charged β‐CD‐l ‐Arg‐polyamine‐coated CdSe/ZnS QDs could effectively deliver the doxorubicin (Dox) into cells and exhibit excellent cell selectivity in cancer versus normal cells. The Dox‐loaded QDs could enter intracellular, which showed that the Dox can efficiently go through the membranes at the existence of β‐CD. Several lines of evidence suggest that the Dox‐loaded QDs can efficiently induce apoptosis likely related to the production of ROS. We expect that the modified QDs can enhance the amount of hydrophobic antitumor drugs in cells and can also be used as fluorescent imaging agents.     

Heme oxygenase expression as a biomarker of exposure to amphiphilic polymer-coated CdSe/ZnS quantum dots

Abstract

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.     

Acute toxicity and tissue distribution of CdSe/CdS‐MPA quantum dots after repeated intraperitoneal injection to mice

Quantum dots (QDs) are novel tools with multiple biological and medical applications because of their superior photoemission and photostability characteristics. However, leaching of toxic metals from QDs is of great concern. Therefore, for the successful application of QDs in bioscience, it is essential to understand their biological fate and toxicity. We investigated toxicological effects and tissue distribution of mercaptopropionic acid‐conjugated cadmium selenide/cadmium sulfide (CdSe/CdS‐MPA) QDs after repeated intraperitoneal injection into BALB/c mice. The mice were injected every 3 days with various doses of QDs (0, 5, 10 and 25 mg kg^?1). The subsequent effects of QDs on plasma levels of various biomarkers were evaluated at different time points (at 0, 1, 4, 7, 10, 13 and 15 days). Various tissue samples (spleen, liver, lung, kidneys, brain, heart and thymus) were collected for toxicity analysis, distribution testing, histopathological examination and inflammation assessment. No abnormal clinical signs or behaviors were recorded but the body weight of mice treated with 25 mg kg^?1 QDs was significantly decreased from day 7 compared with control mice. QDs were observed in the liver, spleen, lung and kidneys, but not in brain or heart. Significantly higher levels of lactate dehydrogenase and nicotinamide adenine dinucleotide phosphate oxidase were found in the plasma, liver and spleen. Histopathological examination did not show any tissue toxicity but the levels of interleukin‐6, a pro‐inflammatory marker, were increased in the plasma, liver and spleen. All of these findings provide insight into the observed toxicological effect levels and tissue‐specific distribution of CdSe/CdS‐MPA QDs. Copyright © 2012 John Wiley & Sons, Ltd.     

DNA damage in BV‐2 cells: An important supplement to the neurotoxicity of CdTe quantum dots

Microglial cells are resident immune cells in the central nervous system. Activation of microglia as induced by CdTe quantum dots (QDs) can trigger damage to neurons. To quantify the intracellular QDs, we monitored the intracellular Cd concentration in the QD‐exposed mouse microglial cells (BV‐2 cell line). The extent of cell injury at different times correlated with the Cd concentration in cells at that time. In addition to Cd ion detection, we also monitored the intracellular fluorescence of the QDs. More QDs accumulated in the nucleus than in the cytoplasm. Comet assays confirmed that QDs induce DNA damage. However, DNA cannot interact with QDs, so the DNA damage was not caused by CdTe QDs adducts to DNA but by the increase of the Cd ion concentration and the secondary oxidative damage. In addition to DNA damage, biofilm injury and endogenous reduced glutathione depletion were also apparent in QD‐exposed BV‐2 cells. These changes can be prevented or even reversed by exogenous reduced glutathione administration.     

Assessment of cytocompatibility of surface-modified CdSe/ZnSe quantum dots for BALB/3T3 fibroblast cells

With the widespread use of quantum dots (QDs), the likelihood of exposure to QDs has been assumed to have increased substantially. Recently, QDs have been employed in numerous biological and medical applications. However, there is a lack of toxicological data pertaining to QDs. In this study, we aimed to investigate the cytocompatibility of surface-modified CdSe/ZnSe QDs for BALB/3T3 fibroblast cells. The ligands used for surface modification are mercaptopropionic acid (MPA) and Gum arabic (GA)/tri-n-octylphosphine oxide (TOPO). Cells were exposed to different concentrations of QDs followed by illustrative cytotoxicity analyses. Furthermore, we used a confocal microscope to assess intracellular uptake of QDs. Confocal images showed that MPA-coated QDs were distributed inside the cytoplasmic region of cells. In contrast, GA/TOPO-coated QDs were not found inside cells. MPA-coated QDs were highly cytocompatible, whereas GA/TOPO-coated QDs were toxic to the cells. Cells treated with GA/TOPO-coated QDs showed altered morphology, decreased viability, significant concentrations of intracellular free cadmium, detectable reactive oxygen species (ROS) formation, depolymerized cytoskeleton, and irregular-shaped nuclei. This study suggests that surface modification by ligands plays a significant role in the prevention of cytotoxicity of QDs.     

Proteomic responses of human intestinal Caco‐2 cells exposed to silver nanoparticles and ionic silver

Even although quite a number of studies have been performed so far to demonstrate nanoparticle‐specific effects of substances in living systems, clear evidence of these effects is still under debate. The present study was designed as a comparative proteomic analysis of human intestinal cells exposed to a commercial silver nanoparticle reference material and ions from AgNO₃. A two‐dimensional gel electrophoresis/MALDI mass spectrometry (MS)‐based proteomic analysis was conducted after 24‐h incubation of differentiated Caco‐2 cells with non‐cytotoxic and low cytotoxic silver concentrations (2.5 and 25 µg ml^?1 nanosilver, 0.5 and 5 µg ml^?1 AgNO₃). Out of an overall number of 316 protein spots differentially expressed at a fold change of ≥ 1.4 or ≤ ?1.4 in all treatments, 169 proteins could be identified. In total, 231 spots were specifically deregulated in particle‐treated groups compared with 41 spots, which were limited to AgNO₃‐treatments. Forty‐four spots (14 %) were commonly deregulated by both types of treatment. A considerable fraction of the proteins differentially expressed after treatment with nanoparticles is related to protein folding, synthesis or modification of proteins as well as cellular assembly and organization. Overlays of networks obtained for particulate and ionic treatments showed matches, indicating common mechanisms of combined particle and ionic silver exposure and exclusive ionic silver treatment. However, proteomic responses of Caco‐2 cells treated with higher concentrations of silver species also showed some differences, for example regarding proteins related to fatty acid and energy metabolism, suggesting an induction of also some different molecular mechanisms for particle exposure and ionic treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

Use of GC × GC/TOF‐MS and LC/TOF‐MS for metabolomic analysis of Hyalella azteca chronically exposed to atrazine and its primary metabolite,desethylatrazine

Atrazine is one of the most commonly detected contaminants in the U.S. Little information is available on one of atrazine's metabolites, desethylatrazine (DEA). Two‐dimensional gas chromatography and liquid chromatography coupled with time of flight‐ mass spectrometry were used to examine metabolite profiles of Hyalella azteca chronically exposed to 30 µg/L atrazine and DEA. The majority of identified metabolites were by‐products of β‐oxidation of fatty acids suggesting possible disruption in energy metabolism. Eicosanoids increased in exposed females suggesting possible perturbations in neuropeptide hormonal systems. Overall, this research demonstrates the feasibility of utilizing metabolomic profiling of invertebrate species exposed to environmental contaminants as a way to determine mechanisms of toxicity. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of silica nanoparticles on cadmium‐induced cytotoxicity,oxidative stress,and apoptosis in human liver HepG2 cells

Extensive application of amorphous silica nanoparticles (Si NPs) and ubiquitous cadmium (Cd) may increase their chances of coexposure to humans. Studies on combined effects of Si NPs and Cd in human cells are very limited. We investigated the potential mechanism of toxicity caused by coexposure of amorphous Si NPs and Cd in human liver (HepG2) cells. Results showed that Si NPs were not toxic to HepG2. However, Cd induced significant toxicity in HepG2 cells. Interestingly, we observed that a noncytotoxic concentration of Si NPs potentiated the cytotoxicity of Cd in HepG2 cells. We further noticed that coexposure of Si NPs and Cd augmented oxidative stress evidenced by the generation of oxidants (reactive oxygen species, hydrogen peroxide, and lipid peroxidation) and depletion of antioxidants (glutathione level and antioxidant enzyme activity). Coexposure of Si NPs and Cd also augmented mitochondria‐mediated apoptosis in HepG2 cells indicated by altered regulation of apoptotic genes (p53, bax, bcl‐2, caspase‐3, and caspase‐9) along with reduced mitochondrial membrane potential. Interaction data indicated that Si NPs facilitate the cellular uptake of Cd due to its strong adsorption on the surface of Si NPs. Hence, Si NPs increased the bioaccumulation and toxicity of Cd in HepG2 cells. This study warrants further research to explore the potential mechanisms of combined toxicity of Si NPs and Cd in animal models.     

Assessment of DNA damage and oxidative stress in juvenile Channa punctatus (Bloch) after exposure to multi‐walled carbon nanotubes

Multi‐walled carbon nanotubes (MWCNTs) have many applications in industry and used as additives in polymers, catalysts, anodes in lithium‐battery and drug delivery. There is little information about MWCNTs' (210 nm) genotoxic potential on juvenile freshwater fish Channa punctatus. Therefore, in this study, we have determined the toxic effects of MWCNTs on freshwater fish C. punctatus by assessing toxicological endpoints such as oxidative stress, mutagenicity, and genotoxicity after acute MWCNTs exposure for 5 days. MWCNTs LC₅₀‐96 hours value for C. punctatus was 21.8 mg/L and on this basis three different MWCNTs concentrations were selected, that is, sub‐lethal I, II, and III, for 5‐days exposure trials with C. punctatus. The level of lipid peroxidation increased in the gills and kidney of exposed fish at sub‐lethal concentrations II and III. Contrastingly, glutathione decreased more in the gills than in the kidney. The activity of catalase enzymes decreased more in the gills than in the kidney at sublethal concentrations I and II. Glutathione S‐transferase decreased in gill tissue but increased in kidney tissue following sub‐lethal III exposure. Moreover, the level of glutathione reductase decreased in both tissues. In addition, MWCNTs genotoxicity was confirmed by DNA damage in lymphocytes, gills, kidney cells, and production of micronuclei (MNi) in red blood cells of freshwater fish following sub‐lethal I, II, and III exposures. In conclusion, this study revealed that application of micronucleus and comet assays for in vivo laboratory studies using freshwater fish for screening the genotoxic potential of MWCNTs.     

Direct‐oxidative DNA damage and apoptosis induction in different human respiratory cells exposed to low concentrations of sodium chromate

The mechanism of Cr(VI) genotoxicity has still not been elucidated. We used Fpg‐modified comet assay to assess direct‐oxidative DNA damage on human lung (A549) and bronchial (BEAS‐2B) cells exposed to 0.1, 0.5, 1.0 and 10 μm sodium chromate for 0.5, 1 and 4 h. Moreover we evaluated apoptosis by morphological analysis and caspase‐3 activity, also after 24 h. On A549 cells a time‐dependent DNA damage, expressed as tail DNA%, beginning from 0.5 μm was found. For oxidative DNA damage an induction after 30 min to 0.5 μm decreasing with time, and a time‐dependent increase at 10 μm was found, indicating for low Cr(VI) concentration the oxidative stress as the first event followed by direct DNA damage and for the highest concentration a time‐dependent increase in oxidative DNA damage. On BEAS‐2B cells DNA damage was induced within 1 h at 0.5–10 μm , without changes with time, showing that BEAS‐2B cells are able to resist to Cr(VI) genotoxicity. Early oxidative DNA damage at 0.1 μm decreasing with time was also found. Significant apoptosis was observed by morphological analysis in A549 cells and to a lower extent in BEAS‐2B at 10 μm . The exposure to 10 μm induced caspase‐3 activity after 4 h in BEAS‐2B and after 24 h in A549 cells. The findings show a higher responsiveness of A549 cells to genotoxic effect of Cr(VI) and early transient oxidative DNA damage in BEAS‐2B. The results emphasize the suitability of this experimental model to evaluate the early genotoxic response of different cells to non‐cytotoxic concentrations of Cr(VI) on target organ. Copyright © 2009 John Wiley & Sons, Ltd.     

Cyto‐genotoxicity and oxidative stress in common carp (Cyprinus carpio) exposed to a mixture of ibuprofen and diclofenac

Thirty million people worldwide consume each day nonsteroidal anti‐inflammatory drugs (NSAIDs), a heterogeneous group of pharmaceuticals used for its analgesic, antipyretic, and anti‐inflammatory properties. Recent studies report high NSAID concentrations in wastewater treatment plant effluents, in surface, ground, and drinking water, and in sediments. NSAIDs are also known to induce toxicity on aquatic organisms. However, toxicity in natural ecosystems is not usually the result of exposure to a single substance but to a mixture of toxic agents, yet only a few studies have evaluated the toxicity of mixtures. The aim of this study was to evaluate the toxicity induced by diclofenac (DCF), ibuprofen (IBP), and their mixture on a species of commercial interest, the common carp Cyprinus carpio. The median lethal concentration of IBP and DCF was determined, and oxidative stress was evaluated using the following biomarkers: lipid peroxidation and activity of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase. Cyto‐genotoxicity was evaluated by micronucleus test, comet assay, and the specific activity of caspase‐3. Results show that DCF, IBP, and a mixture of these pharmaceuticals induced free radical production, oxidative stress and cyto‐genotoxicity in tissues of C. carpio. However, a greater effect was elicited by the mixture than by either pharmaceutical alone in some biomarkers evaluated, particularly in gill. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1637–1650, 2017.     

Application of the SOS/umu test and high‐content in vitro micronucleus test to determine genotoxicity and cytotoxicity of nine benzothiazoles

Benzothiazole and benzothiazole derivatives (BTs) have been detected in various environmental matrices as well as in human beings, but little is currently available regarding their toxicities. In our study, genotoxicities of nine BTs (benzothiazole [BT], 2‐chlorobenzothiazole [CBT], 2‐bromobenzothiazole [BrBT], 2‐fluorobenzothiazole [FBT], 2‐methylbenzothiazole [MeBT], 2‐mercaptobenzothiazole [MBT], 2‐aminobenzothiazole [ABT], 2‐hydroxy‐benzothiazole [OHBT] and 2‐methythiobenzothiazole [MTBT]) are comprehensively evaluated by the SOS/umu test using the bacterial Salmonella typhimurium TA1535/pSK1002 for DNA‐damaging effect and the high content in vitro micronucleus test using two human carcinoma cells (MGC‐803 and A549) for chromosome‐damaging effect. The cytotoxicity of BTs on both bacteria and two human cells was also evaluated. Except for the cytotoxic effect of MBT on MGC‐803 and A549, the other tested BTs showed more than 50% cytotoxicity at their highest concentrations in a dose‐dependent manner, and their LC50s ranged from 19 (MBT in bacteria) to 270 mg l^–1 (CBT in A549). Activation and inactivation were observed for specific BTs after metabolism. On the other hand, no evidence of genotoxicity was obtained for BT, FBT and MBT, and DNA damage was induced by ABT, OHBT, BrBT and MTBT in MGC‐803, by MeBT in A549 and by CBT in both cells. Through quantitative structure–activity relationship analysis, two structure alerts for chemical genotoxicity, including heterocyclic amine and hacceptor‐path3‐hacceptor are present in ABT and OHBT respectively; however, the underlying mechanisms still need further evaluation. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparative assessment of HIF‐1α and Akt responses in human lung and skin cells exposed to benzo[α]pyrene: Effect of conditioned medium from pre‐exposed primary fibroblasts

Exposure to atmospheric pollutants has been accused for many adverse health effects. Benzo[α]pyrene (Β[α]Ρ) in particular, the most extensively studied member of pollutants, is implicated in both cancer initiation and promotion. In the present study, we compared the effects of noncytotoxic doses of Β[α]Ρ, between human skin and lung epithelial cells A431 and A549, respectively, focusing on Akt kinase and HIF‐1α, as it is well known that these proteins are upregulated in various human cancers promoting survival, angiogenesis and metastasis of tumor cells. Also, taking into consideration that fibroblasts are involved in cancer progression, we tested the possible modulation of epithelial cell response by paracrine factors secreted by Β[α]Ρ‐treated fibroblasts. Low doses of Β[α]Ρ were found to enhance epithelial cell proliferation and upregulate both Akt kinase and HIF‐1α, with A549 cells exhibiting a more sustained profile of upregulation. It is to notice that, the response of HIF‐1α was remarkably early, acting as a sensitive marker in response to airborne pollutants. Also, HIF‐1α was induced by Β[α]Ρ in both lung and skin fibroblasts indicating that this effect may be conserved throughout different cell types and tissues. Interestingly however, the response of both proteins was differentially modified upon treatment with conditioned medium from Β[α]Ρ‐exposed fibroblasts. This is particularly evident in A459 cells and confirms the critical role of intercellular and paracrine factors in the modulation of the final response to an extracellular signal. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1103–1112, 2016.     

Contribution of ionic silver to genotoxic potential of nanosilver in human liver HepG2 and colon Caco2 cells evaluated by the cytokinesis‐block micronucleus assay

Extensive human exposure to food‐ and cosmetics‐related consumer products containing nanosilver is of public concern because of the lack of information about their safety. Genotoxicity is an important endpoint for the safety and health hazard assessment of regulated products including nanomaterials. The in vitro cytokinesis‐block micronucleus (CBMN) assay is a very useful test for predictive genotoxicity testing. Recently, we have reported the genotoxicity of 20 nm nanosilver in human liver HepG2 and colon Caco2 cells evaluated using the CBMN assay. The objective of our present study was three‐fold: (i) to evaluate if HepG2 and Caco2 cells are valuable in vitro models for rapid genotoxicity screening of nanosilver; (ii) to test the hypothesis that the nanoparticle size and cell types are critical determinants of its genotoxicity; and (iii) to determine if ionic silver contributes to the nanosilver genotoxicity. With these objectives in mind, we evaluated the genotoxic potential of 50 nm nanosilver of the same shape, composition, surface charge, obtained from the same commercial source, under the same experimental conditions and the same genotoxic CBMN endpoint used for the previously tested 20 nm silver. The ionic silver (silver acetate) was also evaluated under the same conditions. Results of our study show that up to the concentrations tested in these cell types, the smaller (20 nm) nanosilver induces micronucleus formation in both the cell types but the larger (50 nm) nanosilver and the ionic silver provide a much weaker response compared with controls under the same conditions. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.     

Real‐time visualization of oxidative stress in a floating macrophyte Lemna minor L. exposed to cadmium,copper, menadione,and AAPH

An ultra‐sensitive digital imaging system was employed to visualize oxidative stress in intact L. minor plants exposed to Cd, Cu, menadione, AAPH, and ascorbate in real time. The increase of ROS production was assessed by measuring the rate of fluorescence intensity increases of the test medium supplemented with a fluorescing probe (dichlorofluorescein diacetate). The addition of 100 μM CdCl₂ or 100 μM CuSO₄ to the growth medium resulted in a significant increase of medium fluorescence. Additionally, CuSO₄ caused a significantly higher fluorescence intensity than CdCl₂ did. A strong positive correlation (R² = 0.99) between menadione concentration and fluorescence intensity was observed. The positive correlation between AAPH concentration and fluorescence intensity was not as strong as in the case of menadione (R² = 0.81). Menadione induced a stronger oxidative stress than similar concentration of AAPH. The addition of 100 μM ascorbate to L. minor treated with 50 μM menadione significantly reduced the fluorescence intensity increase. A linear trend of the fluorescence increase was observed in all treatments, indicating that chemical‐induced oxidative stress is a gradual process and that the applied concentrations of the chemicals caused a constant increased production of ROS with different intensities, depending on the treatment. This is the combined result of a gradual diminishing of antioxidant reserves and accumulating oxidative damage. The observed rates of ROS production were slower than those in the studies using cell cultures. © 2009 Wiley Periodicals, Inc. Environ Toxicol 25: 573–580, 2010.     

Inflammatory response and endothelial dysfunction in the hearts of mice co‐exposed to SO2, NO2, and PM2.5

SO₂, NO₂, and PM_2.5 are typical air pollutants produced during the combustion of coal. Increasing evidence indicates that air pollution has contributed to the development and progression of heart‐related diseases over the past decades. However, little experimental data and few studies of SO₂, NO₂, and PM_2.5 co‐exposure in animals exist; therefore, the relevant mechanisms underlying this phenomenon are unclear. An important characteristic of air pollution is that co‐exposure persists at a low concentration throughout a lifetime. In the present study, we treated adult mice with SO₂, NO₂, and PM_2.5 at various concentrations (0.5 mg/m³ SO₂, 0.2 mg/m³ NO₂ 6 h/d, with intranasal instillation of 1 mg/kg PM_2.5 every other day during these exposures; or 3.5 mg/m³ SO₂, 2 mg/m³ NO₂ 6 h/d, and 10 mg/kg PM_2.5 for 28 d). Blood pressure (BP), heart rate (HR), histopathological damage, and inflammatory and endothelial cytokines in the heart were assessed. The results indicate that co‐exposure caused endothelial dysfunction by elevating endothelin‐1 (ET‐1) expression and repressing the endothelial nitric oxide synthase (eNOS) level as well as stimulating the inflammatory response by increasing the levels of cyclooxygenase‐2 (COX‐2), inducible nitric oxide synthase (iNOS), tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6). Additionally, these alterations were confirmed by histological staining. Furthermore, we observed decreased BP and increased HR after co‐exposure. Our results indicate that co‐exposure to SO₂, NO₂, and PM_2.5 may be a major risk factor for cardiac disease and may induce injury to the hearts of mammals and contribute to heart disease. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1996–2005, 2016.     

Resveratrol attenuates hyperoxia‐induced oxidative stress,inflammation and fibrosis and suppresses Wnt/β‐catenin signalling in lungs of neonatal rats

Although survival rate of infants born prematurely has been raised by supplemental oxygen treatment, it is followed by high morbidity of hyperoxia‐induced bronchopulmonary dysplasia. In this study, the effect of resveratrol on the lung injury was evaluated in hyperoxia‐exposed rats of preterm birth. The results demonstrated that hyperoxia led to thickened alveolar wall, simplified alveolar architecture and fibrosis. In addition, elevated methane dicarboxylic aldehyde level, decreased glutathione level and superoxide dismutase activity were also found in hyperoxic lungs, as well as the increased tumor necrosis factor‐α, interleukin‐1β and interleukin‐6 in the bronchoalveolar lavage fluid. Fibrotic‐associated proteins transforming growth factor‐β1, α‐smooth muscle actin, collagen I and fibronectin deposition were also found in interstitial substance of lungs. Furthermore, Wnt/β‐catenin signalling was found to be active in hyperoxia‐induced lungs. In addition, expression of SP‐C was increased and T1α was decreased in hyperoxia‐exposed lungs. Resveratrol intraperitoneal administration alleviated hyperoxia‐induced histological injury of lungs, regulated redox balance, decreased pro‐inflammatory cytokine release, and down‐regulated expression of fibrotic‐associated proteins. Furthermore, Wnt/β‐catenin signalling was also suppressed by resveratrol, as represented by diminished expression of lymphoid enhancer factor‐1, Wnt induced signalling protein‐1 and cyclin D1. In addition, the increase of SP‐C and decrease of T1α expression was prevented as well. The present study showed that resveratrol could protect lungs from hyperoxia‐induced injury through its antioxidant, anti‐inflammatory and anti‐fibrotic effects. The transdifferentiation of alveolar epithelial type II cells to alveolar epithelial type I cells promotion and Wnt/β‐catenin signalling suppression are also involved in the protective effect.     

Acute exposure to 3‐methylcholanthrene induces hepatic oxidative stress via activation of the Nrf2/ARE signaling pathway in mice

Polycyclic aromatic hydrocarbons (PAHs) are the most common contaminants in the environment. The primary focus on the toxicity of PAHs is their ability to activate the aryl hydrocarbon receptor (AhR)‐mediated pathway and lead to carcinogenesis in different organisms. However, the influence of PAHs on the antioxidant system in mammalian systems has received only limited attention. In the present study, we observed that the intraperitoneal injection of 100 mg/kg 3‐methylcholanthrene (3MC) into mice significantly increased reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents and decreased glutathione (GSH) contents and the activity of total antioxidant capacity (T‐AOC), indicating that serious oxidative stress had been induced in the liver of mice. Then, the oxidative stress signal activated the nuclear factor erythroid 2‐related factor 2/antioxidant response element (Nrf2/ARE) pathway by enhancing the mRNA levels of Nrf2, p38, and Erk2. Moreover, the mRNA levels of Nrf2/ARE target genes, including glutathione peroxidase (Gpx), glutathione reductase (GR), glutathione synthetase (GS), NAD(P)H: quinone oxidoreductase 1 (Nqo1), superoxide dismutase 1 (Sod1), and Sod2, increased significantly after treatment with 3MC for 24 hours. The hepatic levels of NQO1 and the activities of GR and GS were also significantly enhanced at 24 hours after 3MC treatment. Because the expression of NQO1 is co‐regulated by Nrf2/ARE and AhR/XRE in mammalian tissues, NQO1 may play an important role in protecting against the oxidative stress induced by 3MC. Taken together, our findings suggested that acute exposure to 3MC altered the cellular redox balance in hepatocytes to trigger Nrf2‐regulated antioxidant responses, which may represent an adaptive cell defense mechanism against the oxidative stress induced by PAHs. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1399–1408, 2014.