Pulmonary Toxicity In Mice Research Articles

Co-modification with MSC membrane and PDA prevents Fe3O4-induced pulmonary toxicity in mice via AMPK-ULK1 axis

Fe3O4 nanoparticles are widely used in the diagnosis and treatment of diseases due to their superparamagnetism, but their toxicity in vivo, which can result in apoptosis or autophagy, cannot be ignored. It has been reported that polydopamine (PDA) modification can reduce the toxicity of Fe3O4 and increase its biocompatibility. However, more research is warranted to further improve the modification method. We therefore developed a new method to coat Fe3O4@PDA nanoparticles with the mesenchymal stem cell membrane (MSCM) and evaluated the toxicity of the modified particles in the lungs of mice.We found that the MSCM modification significantly reduced lung injury induced by Fe3O4 particles in mice. Compared with Fe3O4@PDA nanoparticles, co-modification with MSCM and PDA significantly reduced autophagy and apoptosis in mouse lung tissue, and reduced activation of autophagy mediated by the AMPK-ULK1 pathway axis. Thus, co-modification with MSCM and PDA prevents Fe3O4-induced pulmonary toxicity in mice by inhibiting autophagy, apoptosis, and oxidative stress.

Toxicokinetics and systematic responses of differently sized indium tin oxide (ITO) particles in mice via oropharyngeal aspiration exposure

Indium tin oxide (ITO) is an important semiconductor material, because of increasing commercial products consumption and potentially exposed workers worldwide. So, urgently we need to assess and manage potential health risks of ITO. Although the Occupational Exposure Limit (OEL) has been established for ITO exposure, there is still a lack of distinguishing the risks of exposure to particles of different sizes. Therefore, obtaining toxicological data of small-sized particles will help to improve its risk assessment data. Important questions raised in quantitative risk assessments for ITO particles are whether biodistribution of ITO particles is affected by particle size and to what extent systematic adverse responses is subsequently initiated. In order to determine whether this toxicological paradigm for size is relevant in ITO toxic effect, we performed comparative studies on the toxicokinetics and sub-acute toxicity test of ITO in mice. The results indicate both sized-ITO resided in the lung tissue and slowly excreted from the mice, and the smaller size of ITO being cleared more slowly. Only a little ITO was transferred to other organs, especially with higher blood flow. Two type of ITO which deposit in the lung mainly impacts respiratory system and may injure liver or kidney. After sub-acute exposure to ITO, inflammation featured by neutrophils infiltration and fibrosis with both dose and size effects have been observed. Our findings revealed toxicokinetics and dose-dependent pulmonary toxicity in mice via oropharyngeal aspiration exposure, also replenish in vivo risk assessment of ITO. Collectively, these data indicate that under the current OEL, there are potential toxic effects after exposure to the ITO particles. The observed size-dependent biodistribution patterns and toxic effect might be important for approaching the hazard potential of small-sized ITO in an occupational environment.

Glycyrrhizic acid, as an inhibitor of HMGB1, alleviates bleomycin-induced pulmonary toxicity in mice through the MAPK and Smad3 pathways

Aim High-mobility group box 1 (HMGB1) protein has been noticed particularly for its pivotal role in several pathologies. However, the relevance between HMGB1 and pathological progress in lung toxicity still remains unclear. In the study, we evaluated the effect of glycyrrhizic acid as an HMGB1 inhibitor on the early inflammation and late fibrosis in bleomycin-induced pulmonary toxicity in mice. Methods We established a bleomycin-induced pulmonary toxicity model to detect the relevance between HMGB1 and pathological changes in the early inflammatory and late fibrotic stages. Results We found that bleomycin-induced increase in inflammatory cytokines interleukin (IL)-β1, tumor necrosis factor (TNF)-α, monocyte chemotactic protein (MCP)-1, and inflammatory lesions in lung tissue in the early stage of the model. However, markers of fibrosis such as transforming growth factor (TGF)-β1 and α-smooth muscle actin (α-SMA) were significantly elevated on day 7 after bleomycin instillation. Interestingly, HMGB1 also began to rise on day 7, rather than in the early inflammatory phase. However, early (from day 0 to 14 after bleomycin instillation) or late (from day 14 to 28) intervention with HMGB1 neutralizing antibody or glycyrrhizic acid alleviated inflammation and fibrosis through down-regulating the inflammatory signaling mitogen-activated protein kinase (MAPK) and fibrotic signaling Smad3 pathway. Conclusion Our results suggested that HMGB1 mediates both inflammation and fibrosis in this model. The development of high-potency and low-toxicity HMGB1 inhibitors may be a class of potential drugs for the treatment of pulmonary fibrosis.

Raspberry Ketones Attenuate Cyclophosphamide-Induced Pulmonary Toxicity in Mice through Inhibition of Oxidative Stress and NF-ΚB Pathway.

Cyclophosphamide (CP) was found to have a potential toxic effect on lung tissues. Raspberry ketones (RKs) are natural antioxidant chemicals isolated from red raspberries (Rubus ideaus). They are commonly used for weight loss and obesity. The current study aimed to evaluate the possible protective effects of RKs against lung toxicity induced by CP. Mice were allocated into six groups: (1) control group; (2) CP group: received a single intraperitoneal dose of CP (150 mg/kg, i.p.); and (3–6) mice were pre-treated orally with different doses of RKs (25, 50, 100, and 200 mg/kg) for 14 consecutive days, respectively, before the administration of an intraperitoneal dose of CP (150 mg/kg, i.p.). Mice were then sacrificed under anesthesia, then lungs were removed for histopathological and biochemical investigations. A single dose of CP markedly altered the levels of some oxidative stress biomarkers and resulted in the fragmentation of DNA in lung homogenates. Histological examination of CP-treated mice demonstrated diffuse alveolar damage that involved apparent hyalinization of membranes, thickening of inter alveolar septa, and proliferation of type II pneumocytes. The immunohistochemical results of CP-treated mice revealed strongly positive Bax and weakly positive proliferating cell nuclear antigen (PCNA) staining reactivity of the nuclei of the lining epithelium of the bronchioles and alveoli. CP activated the cyclooxygenase-2/nuclear factor-kappa B pathway. However, pre-treatment with RKs significantly attenuated CP-evoked alterations in the previously mentioned parameters, highlighting their antioxidant, anti-inflammatory, and anti-apoptotic potential. RKs may be suggested to be a potential candidate to ameliorate CP-induced pulmonary toxicity.

Oxidative stress, apoptosis and inflammatory responses involved in copper-induced pulmonary toxicity in mice.

At present, there are few studies focused on the relationship between copper (Cu) and oxidative stress, apoptosis, or inflammatory responses in animal and human lungs. This study was conducted to explore the effects of Cu on pulmonary oxidative stress, apoptosis and inflammatory responses in mice orally administered with 0 mg/kg (control), 10 mg/kg, 20 mg/kg, and 40 mg/kg of CuSO4 for 42 days. The results showed that CuSO4 increased ROS production, and MDA, 8-OHdG and NO contents as well as iNOS activities and mRNA expression levels. Meanwhile, CuSO4 reduced the activities and mRNA expression levels of antioxidant enzymes (GSH-Px, CAT, and SOD) and GSH contents, and ASA and AHR abilities. Also, CuSO4 induced apoptosis, which was accompanied by decreasing Bcl-2, Bcl-xL mRNA expression levels and protein expression levels, and increasing Bax, Bak, cleaved-caspase-3, cleaved-caspase-9 mRNA, and protein expression levels, and Bax/Bcl-2 ratio. Concurrently, CuSO4 caused inflammation by increasing MPO activities and activating the NF-κB signalling pathway, and down-regulating the mRNA and protein expression levels of anti-inflammatory cytokines (IL-2, IL-4, IL-10). In conclusion, the abovementioned findings demonstrated that over 10 mg/kg CuSO4 can cause oxidative stress, apoptosis, and inflammatory responses, which contribute to pulmonary lesions and dysfunction in mice.

Respiratory exposure to nano-TiO2 induces pulmonary toxicity in mice involving reactive free radical-activated TGF-β/Smad/p38MAPK/Wnt pathways.

Numerous studies have shown that lung injury can be caused by respiratory exposure to nanoparticulate titanium dioxide (nano-TiO2 ), but whether pulmonary inflammation and fibrosis are related to the activation of the TGF-β/Smad/p38MAPK/Wnt pathways remains unclear. In this study, mice were administrated nano-TiO2 by nasal instillation for nine consecutive months, and the molecular mechanisms of nano-TiO2 on the pulmonary toxicity of mice were examined. The findings suggested that nano-TiO2 caused pneumonia and pulmonary fibrosis. Furthermore, the results also showed that an overproduction of reactive free radicals occurred in mouse lungs, and that the expression of TGF-β/p38MAPK/Wnt pathway-related factors, including hypoxia-inducible factor 1α (HIF-1α), transforming growth factor-β1 (TGF-β1), phosphorylated p38 mitogen activated protein kinases (p-p38MAPK), small mothers against decapentaplegic homolog 2 (Smad2), extracellular matrix (ECM), Wingless/Integrated 3 (Wnt3), Wingless/Integrated 4 (Wnt4), integrin-linked kinase (ILK), β-catenin, nuclear factor-κB (NF-κB), α-smooth muscle actin (α-SMA), c-Myc, Type I collage (collagen I), and Type collage III (collagen III) were remarkably elevated, while phosphorylated glycogen synthase kinase-3β (p-GSK-3β) expression was decreased. Those data implied that the pulmonary inflammation and fibrosis caused by nano-TiO2 exposure may be involved in reactive free radical-mediated activation of the TGF-β/Smad/p38MAPK/Wnt pathways.

The acute pulmonary toxicity in mice induced by Staphylococcus aureus, particulate matter, and their combination.

Inhalation of pathogenic bacteria transported by particulate matter (PM) presents an important potential threat to human health. Therefore, the pulmonary toxicity in mice caused by Staphylococcus aureus (S. aureus) and PM as individual matter and mixtures was studied. PM and S. aureus were instilled intratracheally into Kunming mice at doses of 0.2 mg/mouse and 5.08 × 106 CFU /mouse, respectively, as individual matter and in combination two times at 5-day intervals. After the exposure period, oxidative stress markers and nitric oxide (NO) in the lung, cellular infiltration, neurotrophins, chemokines, and cytokines in bronchoalveolar lavage fluid (BALF), and immunoglobulin (Ig) in sera were examined. Exposure to the combination of PM and S. aureus caused significant increases in malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and NO and significant decreases in total antioxidant capacity (T-AOC) and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in the lung. Meanwhile, the ratio of interleukin (IL)-4 to interferon (INF)-γ, the IL-4 level in BALF, and the IgE concentration in sera were significantly increased in the groups exposed to S. aureus or the combination of PM and S. aureus. Substance P and IL-8 in BALF were significantly increased in mice exposed to PM, S. aureus or their combination. In addition, PM, S. aureus, and their combination caused infiltration of leukocytes into the alveolar tissue spaces. The results suggested that exposure to the combination of PM and S. aureus induced a lung inflammatory response that was at least partly caused by oxidative stress and mediators from the activated eosinophils, neutrophils, alveolar macrophages, and epithelial cells.

Soluble epoxide hydrolase inhibitor AUDA decreases bleomycin-induced pulmonary toxicity in mice by inhibiting the p38/Smad3 pathways.

Bleomycin (BLM) has potent tumor cell-killing properties that have given it an important place in cancer chemotherapy, but pulmonary toxicity is its major adverse effect. Soluble epoxide hydrolase (sEH) inhibitors have been reported to have protective effects in fibrosis models, but the effects of AUDA, an sEH inhibitor of BLM-induced pulmonary toxicity and fibrosis, remain to be researched. In this study, we assessed the effects of AUDA on the BLM-induced pulmonary fibrosis in a mouse model, and transforming growth factor (TGF)-β1-induced epithelial proliferation and epithelial-mesenchymal transition (EMT) in vitro by monitoring changes in pulmonary function, inflammatory response, fibrotic remodeling, and signaling pathways. AUDA was administered by intragastric administration (i.g) daily for three weeks, starting at seven days after intratracheal instillation of BLM. All examinations were performed 24h after the last i.g. In vivo, AUDA significantly improved BLM-induced decline in lung function and body weight, and inhibited inflammatory cell accumulation and the mRNA and protein expression of interleukin (IL)-1β, TGF-β1, and matrix metalloproteinase 9 (MMP-9) in lung tissue. Moreover, AUDA attenuated BLM-induced deposition of collagen fibers, destruction of alveolar structures, and pulmonary parenchyma. Additionally, AUDA regulated the expression of α-smooth muscle actin (α-SMA) and E-cadherin by inhibiting the Smad3/p38 signaling pathway. In vitro, AUDA significantly inhibited TGF-β1-induced epithelial cells and fibroblast proliferation, reduced sEH expression and α-SMA expression, and increased epoxyeicosatrienoic acid (EET) levels and E-cadherin expression in epithelial cells. These effects were blocked by AUDA by downregulating the Smad3 and p38 signaling pathways. Taken together, these data indicate that treatment with sEH inhibitors may improve BLM-induced pulmonary toxicity.

In vitro and in vivo evaluation of BMAP-derived peptides for the treatment of cystic fibrosis-related pulmonary infections.

Patients with cystic fibrosis require pharmacological treatment against chronic lung infections. The alpha-helical antimicrobial peptides BMAP-27 and BMAP-28 have shown to be highly active in vitro against planktonic and sessile forms of multidrug-resistant Pseudomonas aeruginosa, Staphylococcus aureus, and Stenotrophomonas maltophilia cystic fibrosis strains. To develop small antibacterial peptides for therapeutic use, we tested shortened/modified BMAP fragments, and selected the one with the highest in vitro antibacterial activity and lowest in vivo acute pulmonary toxicity. All the new peptides have shown to roughly maintain their antibacterial activity in vitro. The 1-18 N-terminal fragment of BMAP-27, showing MIC90of16µg/ml against P. aeruginosa isolates and strain-dependent anti-biofilm effects, showed the lowest pulmonary toxicity in mice. However, when tested in a murine model of acute lung infection by P. aeruginosa, BMAP-27(1-18) did not show any curative effect. If exposed to murine broncho-alveolar lavage fluid BMAP-27(1-18) was degraded within 10min, suggesting it is not stable in pulmonary environment, probably due to murine proteases. Our results indicate that shortened BMAP peptides could represent a starting point for antibacterial drugs, but they also indicate that they need a further optimization for effective in vivo use.

Pulmonary toxicity in mice following exposure to cerium chloride.

The widespread application of lanthanoids (Lns) in manufacturing industries has raised occupational and environmental health concerns about the possible increased health risks to humans exposed to Lns in their working and living environments. Numerous studies have shown that exposures to Ln cause pulmonary injury in animals, but very little is known about the molecular mechanisms of the pulmonary inflammation caused by cerium chloride (CeCl3) exposure. In this study, we evaluated the oxidative stress and molecular mechanism underlying with the pulmonary inflammation associated with chronic lung toxicity in mice treated with nasally instilled CeCl3 for 90 consecutive days. Our findings suggest that significant cerium accumulated in the lung, leading the obvious increase of the lung indices, significant increases in inflammatory cells and levels of lactate dehydrogenase, alkaline phosphate, and total protein, overproduction of reactive oxygen species and peroxidation of lipids, reduced antioxidant capacity, and pulmonary inflammation. CeCl3 exposure also activated nuclear factor κB, increased the expression of tumor necrosis factor α, cyclooxygenase-2, heme oxygenase 1, interleukin 2, interleukin 4, interleukin 6, interleukin 8, interleukin 10, interleukin 18, interleukin 1β, and CYP1A1. However, CeCl3 reduced the expression of nuclear factor κB (NF-κB)-inhibiting factor and heat shock protein 70. These findings suggest that the pulmonary inflammation caused by CeCl3 in mice is closely associated with oxidative stress and inflammatory cytokine expression.

Toxicity assessment of zinc oxide nanoparticles using sub-acute and sub-chronic murine inhalation models

BackgroundAlthough ZnO nanoparticles (NPs) are used in many commercial products and the potential for human exposure is increasing, few in vivo studies have addressed their possible toxic effects after inhalation. We sought to determine whether ZnO NPs induce pulmonary toxicity in mice following sub-acute or sub-chronic inhalation exposure to realistic exposure doses.MethodsMice (C57Bl/6) were exposed to well-characterized ZnO NPs (3.5 mg/m3, 4 hr/day) for 2 (sub-acute) or 13 (sub-chronic) weeks and necropsied immediately (0 wk) or 3 weeks (3 wks) post exposure. Toxicity was assessed by enumeration of total and differential cells, determination of total protein, lactate dehydrogenase activity and inflammatory cytokines in bronchoalveolar lavage (BAL) fluid as well as measurements of pulmonary mechanics. Generation of reactive oxygen species was assessed in the lungs. Lungs were evaluated for histopathologic changes and Zn content. Zn concentration in blood, liver, kidney, spleen, heart, brain and BAL fluid was measured.ResultsAn elevated concentration of Zn2+ was detected in BAL fluid immediately after exposures, but returned to baseline levels 3 wks post exposure. Dissolution studies showed that ZnO NPs readily dissolved in artificial lysosomal fluid (pH 4.5), but formed aggregates and precipitates in artificial interstitial fluid (pH 7.4). Sub-acute exposure to ZnO NPs caused an increase of macrophages in BAL fluid and a moderate increase in IL-12(p40) and MIP-1α, but no other inflammatory or toxic responses were observed. Following both sub-acute and sub-chronic exposures, pulmonary mechanics were no different than sham-exposed animals.ConclusionsOur ZnO NP inhalation studies showed minimal pulmonary inflammation, cytotoxicity or lung histopathologic changes. An elevated concentration of Zn in the lung and BAL fluid indicates dissolution of ZnO NPs in the respiratory system after inhalation. Exposure concentration, exposure mode and time post exposure played an important role in the toxicity of ZnO NPs. Exposure for 13 wks with a cumulative dose of 10.9 mg/kg yielded increased lung cellularity, but other markers of toxicity did not differ from sham-exposed animals, leading to the conclusion that ZnO NPs have low sub-chronic toxicity by the inhalation route.

Pulmonary response of mice to a sequential exposure of side-stream cigarette smoke and multi-walled carbon nanotubes

Due to their unique properties, nano-sized carbon materials are predicted to have numerous applications in industry, but significant evidence exists to suggest their potential to cause toxicity. To determine if pre-exposure to side-stream cigarette smoke (SSCS) influences their toxicity, we examined the pulmonary response of smoke-exposed mice to multi-walled carbon nanotubes (MWCNT). Female A/J mice were exposed to SSCS in a whole body exposure chamber at approximately 40 mg/m3 for 4 weeks (6 h/d, 5 d/wk) and challenged with a single dose of MWCNT (40 µg) by the pharyngeal aspiration technique. A total of four groups were compared: air/phosphate buffered saline (PBS)-control, SSCS/PBS, air/MWCNT, and SSCS/MWCNT. At days 1 and 3 post-MWCNT treatment, lung tissues and bronchoalveolar lavage fluid (BALF) were collected and analyzed. In comparison with controls, significantly higher levels of total BAL cells were obtained from mice exposed to SSCS and MWCNT alone or combination. Influx of polymorphonuclear leukocytes (PMN) into BALF greatly increased in MWCNT alone and SSCS/MWCNT groups at both days 1 and 3 compared with controls. However, pre-exposure to SSCS significantly suppressed PMN response to MWCNT on day 1 but not day 3. Total BALF protein, lactate dehydrogenase, and mucin were significantly elevated in MWCNT and SSCS/MWCNT groups but not in the SSCS group, except mucin at day 3, when compared with controls. These results demonstrate that MWCNT markedly increases pulmonary toxicity in mice and SSCS pre-exposure plays a minor role in modulating MWCNT-induced lung toxicity at the concentrations and time points selected in the present study.

Subacute effects of inhaled Jet Fuel-A (Jet A) on airway and immune function in female rats

Two studies were conducted to assess the potential airway and immune effects following subacute (14 d) exposure of female rats to 500, 1000 or 2000 mg/m3 of Jet-A for 4 h/d. The first study used Sprague-Dawley rats; the second study included both Fischer 344 (F344) and Sprague-Dawley rats. In the first study, exposure to 2000 mg/m3 jet fuel may have caused significant upper airway inflammation on day 7 post-exposure, as indicated by elevated protein and lactate dehydrogenase in nasal lavage fluid, but any inflammation resolved by day 14 post-exposure. No significant impact on immune cell populations in the spleens was observed. The histological examination showed no evidence of infectious or toxic effect. In the second study, body weights of the F344 rats in the 2000 mg/m3 group were depressed, as compared to the controls, at the end of the exposure. Some lung lavage fluid markers were increased at 24 h after the final exposure, however, no test article-induced histological changes were observed in the lungs, nasal cavities, or any other tissue of any of the jet fuel exposed animals. Overall, these studies demonstrated limited evidence of effects of 14 d of exposure to Jet A on the airways, immune system, or any other organ or system of female Sprague-Dawley and F344 rats, with no remarkable differences between strains. The lack of identified significant airway or immune effects was in contrast to previous examinations of jet fuel for pulmonary toxicity in mice and rats and for immunotoxicity in mice.

Multi-walled carbon nanotubes induce apoptosis via mitochondrial pathway and scavenger receptor

We have demonstrated previously that the acid-treated multi-walled carbon nanotubes (aci-MWCNTs) and taurine functionalized MWCNTs (tau-MWCNTs) induced differential pulmonary toxicity in mice after instillation exposure. In order to compare differences of cytotoxicity between the aci- and tau-MWCNTs, RAW 264.7 cells (a murine macrophage cell line) were chosen to be exposed to the aci- and tau-MWCNTs at concentrations of 0, 5, 20, 40, and 80μg/ml for 12 or 24h respectively. The results showed that although the aci- and tau-MWCNTs induced only mild decrease in cell viability to RAW 264.7 cells, the two types of MWCNTs elicited significant increase in apoptosis and decreased ability in cellular phagocytosis. Moreover, by using the specific inhibitors, we found that the scavenger receptors (SR) and caspase-9 were actively involved in the apoptosis induced by the aci- and tau-MWCNTs. The taurine functionalized MWCNTs (tau-MWCNTs) showed less cytotoxicity and apoptotic effect to RAW 264.7 cells than those of aci-MWCNTs. Taken together, the results indicated the important role of scavenger receptors and mitochondria in the apoptosis induced by MWCNTs.

Pulmonary Toxicity in Mice by 2‐ and 13‐week Inhalation Exposures to Indium‐tin Oxide and Indium Oxide Aerosols

Inhalation toxicities of indium-tin oxide (ITO) and indium oxide (IO) in mice were characterized in comparison with those previously reported in rats. B6C3F(1) mice of both sexes were exposed by inhalation to ITO or IO aerosol for 6 h/day, 5 day/wk for 2 wk at 0, 0.1, 1, 10 or 100 mg/m(3) or 13 wk at 0, 0.1or 1 mg/m(3). ITO and IO particles were deposited in the lung, mediastinal lymph node (MLN) and nasal-associated lymphoid tissue. Alveolar proteinosis, infiltrations of alveolar macrophages and inflammatory cells and increased lung weight were induced by 2- and 13-week exposures to ITO and IO, while alveolar epithelial hyperplasia occurred only in the 2-week exposures. Thickened pleural wall, hyperplastic MLN, extramedullary hematopoiesis in the spleen and increased levels of erythrocyte parameters were induced by 13-week exposure to ITO. The ITO- and IO-induced pulmonary lesions were milder in mice than those previously reported in rats, and the fibrotic lesions were different between these two species. Indium levels in the lung and pooled blood were analyzed in the mice exposed to ITO and IO for 13 wk. In the 13-week inhalation exposure of mice to ITO, alveolar proteinosis and significantly increased lung weight were induced at the same exposure concentration as the current threshold limit value for indium and its compounds.

Nanosilver induces minimal lung toxicity or inflammation in a subacute murine inhalation model

BackgroundThere is increasing interest in the environmental and health consequences of silver nanoparticles as the use of this material becomes widespread. Although human exposure to nanosilver is increasing, only a few studies address possible toxic effect of inhaled nanosilver. The objective of this study was to determine whether very small commercially available nanosilver induces pulmonary toxicity in mice following inhalation exposure.ResultsIn this study, mice were exposed sub-acutely by inhalation to well-characterized nanosilver (3.3 mg/m3, 4 hours/day, 10 days, 5 ± 2 nm primary size). Toxicity was assessed by enumeration of total and differential cells, determination of total protein, lactate dehydrogenase activity and inflammatory cytokines in bronchoalveolar lavage fluid. Lungs were evaluated for histopathologic changes and the presence of silver. In contrast to published in vitro studies, minimal inflammatory response or toxicity was found following exposure to nanosilver in our in vivo study. The median retained dose of nanosilver in the lungs measured by inductively coupled plasma - optical emission spectroscopy (ICP-OES) was 31 μg/g lung (dry weight) immediately after the final exposure, 10 μg/g following exposure and a 3-wk rest period and zero in sham-exposed controls. Dissolution studies showed that nanosilver did not dissolve in solutions mimicking the intracellular or extracellular milieu.ConclusionsMice exposed to nanosilver showed minimal pulmonary inflammation or cytotoxicity following sub-acute exposures. However, longer term exposures with higher lung burdens of nanosilver are needed to ensure that there are no chronic effects and to evaluate possible translocation to other organs.

Pulmonary Toxicity in Mice Exposed to Low and Medium Doses of Water-Soluble Multi-Walled Carbon Nanotubes

Carbon nanotubes (CNTs) are a class of new allotrope of carbon. Different functionalized CNTs may vary from their physical and chemical properties to the biological property. In this study, the toxicity of water-soluble taurine multi-walled CNTs (tau-MWNTs), raw MWNTs and positive control crystalline silicon dioxide particles on mouse lungs via intratracheal instillation (i.t.) was investigated. The dosages we used were 0.125, 0.25, 0.5 or 1 mg/kg of tau-MWNTs and raw MWNTs, and 1 mg/kg of silicon dioxide particles; Serum and lungs were collected at 1, 7, 14 or 28 days postexposure. The biochemical and cellular parameters were assessed, which include the ratio of the lung weight and body weight (lung indices), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and angiotensin converting enzyme (ACE) in serum, and malondialdehyde (MDA), reduced glutathione (GSH), total sulfhydryl group (TSH) in lung tissue homogenates as well as the hydroxyproline in lungs. The characteristic recovery of the lung injury at 28 days postexposure was examined by the assessment of LDH, ALP, lung indices, and histopathology. ACE, MDA, GSH, TSH and histopathological changes showed that tau-MWNTs were less toxic than the raw MWNTs. Histopathological and ultrastructural investigation indicated that the acute pulmonary inflammation in lungs alleviated after 7d postexposure, and were greatly recovered within 28d. Meanwhile, the entrapment of tau-MWNTs reduced greatly by the 28d postexposure. Whereas the heavier pathologic changes induced by raw MWNTs lasted 7 days more than that of tau-MWNTs. Notably, no occurrence of granulomas and fibrosis were found in this study both in the two CNTs samples through 28d postexposure. Silicon dioxide particles, on the contrary, produced more severe damage to lungs than CNTs did in lung index, as well as other biochemical and cellular parameters. These findings indicate that water-soluble tau-MWNTs in low and medium doses induce slight and recoverable pulmonary inflammation in mice, and are less toxic than the insoluble raw MWNTs.

The acute pulmonary toxicity in mice induced by multiwall carbon nanotubes, benzene, and their combination

Carbon nanotubes (CNTs) have been synthesized and produced on large scale for their wide application. They have high absorption ability to organic contaminants (such as benzene) and can form CNTs-benzene combination with benzene. In this article, the acute pulmonary toxicity, induced by multiwall carbon nanotubes (MWCNTs), benzene, and their combination, was studied by administrating the three test materials into mice lungs via intratracheal instillation. The biochemical parameters in bronchoalveolar lavage fluid (BALF) and pathological lesions in lungs were used as endpoints to evaluate the pulmonary toxicity of the three test materials at 3-day and 7-day postexposure, respectively. After the mice were intratracheally instilled with MWCNTs, benzene and MWCNTs-benzene combination at doses of 6.67 mg/kg, 2.67 mg/kg, and 9.34 mg/kg (containing 6.67 mg/kg MWCNTs and 2.67 mg/kg benzene), the total protein, alkaline phosphatase (ALP), acid phosphatase (ACP), and lactate dehydrogenase (LDH) in BALF and pathological lesions in lungs were examined. At 3-day postexposure, MWCNTs induced obvious pulmonary toxicity and benzene only induced slight pulmonary toxicity, whereas their combination induced very severe pulmonary toxicity. At 7-day postexposure, MWCNTs and benzene did not induce pulmonary toxicity individually, whereas their combination still induced severe pulmonary toxicity. These data indicated that, at the instilled doses in this experiment, the MWCNTs can alone induce acute pulmonary toxicity in mice and the benzene does not induce pulmonary toxicity, but the pulmonary toxicity of MWCNTs is enhanced after they form MWCNTs-benzene combination with low dose of benzene. The enhanced pulmonary toxicity may be due to the change of MWCNTs aggregation ability after benzene is adsorbed on them.

Heavy-Duty Engine Emissions: Response

Vol. 112, No. 13 PerspectivesOpen AccessHeavy-Duty Engine Emissions: Response Janet Arey Janet Arey Search for more papers by this author Published:1 September 2004https://doi.org/10.1289/ehp.112-a728aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit In his letter, Schaeffer concludes that because of the ongoing changes in diesel technology, “establishing standardized reference materials [of diesel exhaust particles (DEPs)] will be particularly challenging.” As amply illustrated by the work of DeMarini et al. (2004) and Singh et al. (2004), which prompted my commentary (Arey 2004), the effort is worth making because multidisciplinary studies on representative DEP samples are needed if meaningful assessments of the health hazards associated with DEPs are to be made. DeMarini et al. (2004) and Singh et al. (2004) highlighted the chemical, physical, and biological differences between two widely used DEP samples, one mainly studied for pulmonary toxicity and the other for genotoxicity; before their studies, the chemical composition and biologic activity of the samples had not been compared.In his letter, Schaeffer describes the Advanced Collaborative Emissions Study (ACES), an important diesel assessment project currently in the planning stage by the Health Effects Institute (Boston, MA). Perusing Warren’s presentation on the project (Warren 2004) cited by Schaeffer, I found that the utility of standard reference materials that allow for collaborations and exhaustive characterization of DEPs is reinforced by several issues Warren highlighted; for example, which of the “794 measurements under consideration” should be made; what should the results be compared to; and what health effect testing should be conducted? Until we fully understand the mechanisms of action of diesel and ambient particles that are involved in their adverse health effects, we need more multidisciplinary, collaborative efforts to study samples that can be shared among researchers.ReferencesArey J. 2004. A tale of two diesels. Environ Health Perspect 112:812-81315175165. Link, Google ScholarDeMarini DM, Brooks LR, Warren SH, Kobayashi T, Gilmour MI, Singh P. 2004. Bioassay-directed fractionation and Salmonella mutagenicity of automobile and forklift diesel exhaust particles. Environ Health Perspect 112:814-81915175166. Link, Google ScholarSingh P, DeMarini DM, Dick CAJ, Tabor DG, Ryan JV, Linak WPet al.. 2004. Sample characterization of automobile and forklift diesel exhaust particles and comparative pulmonary toxicity in mice. Environ Health Perspect 112:820-82515175167. Link, Google ScholarWarren J 2004. Update on the ACES Diesel Assessment Program. Available: http://www.healtheffects.org/Slides/AnnConf2004/Warren.pdf [accessed 1 July 2004]. Google ScholarFiguresReferencesRelatedDetails Vol. 112, No. 13 September 2004Metrics About Article Metrics Publication History Originally published1 September 2004Published in print1 September 2004 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Sample characterization of automobile and forklift diesel exhaust particles and comparative pulmonary toxicity in mice.

Two samples of diesel exhaust particles (DEPs) predominate in health effects research: an automobile-derived DEP (A-DEP) sample and the National Institute of Standards Technology standard reference material (SRM 2975) generated from a forklift engine. A-DEPs have been tested extensively for their effects on pulmonary inflammation and exacerbation of allergic asthmalike responses. In contrast, SRM 2975 has been tested thoroughly for its genotoxicity. In the present study, we combined physical and chemical analyses of both DEP samples with pulmonary toxicity testing in CD-1 mice to compare the two materials and to make associations between their physicochemical properties and their biologic effects. A-DEPs had more than 10 times the amount of extractable organic material and less than one-sixth the amount of elemental carbon compared with SRM 2975. Aspiration of 100 micro g of either DEP sample in saline produced mild acute lung injury; however, A-DEPs induced macrophage influx and activation, whereas SRM 2975 enhanced polymorphonuclear cell inflammation. A-DEPs stimulated an increase in interleukin-6 (IL-6), tumor necrosis factor alpha, macrophage inhibitory protein-2, and the TH2 cytokine IL-5, whereas SRM 2975 only induced significant levels of IL-6. Fractionated organic extracts of the same quantity of DEPs (100 micro g) did not have a discernable effect on lung responses and will require further study. The disparate results obtained highlight the need for chemical, physical, and source characterization of particle samples under investigation. Multidisciplinary toxicity testing of diesel emissions derived from a variety of generation and collection conditions is required to meaningfully assess the health hazards associated with exposures to DEPs. Key words: automobile, diesel exhaust particles, forklift, mice, pulmonary toxicity, SRM 2975.