Comparative pulmonary toxicological assessment of oil combustion particles following inhalation or instillation exposure

Inflammation related to inhalation of nano and micron sized iron oxides: a systematic review

Inhalation exposure to iron oxide occurs in many workplaces and respirable aerosols occur during thermal processes (e.g. welding, casting) or during abrasion of iron and steel products (e.g. cutting, grinding, machining, polishing, sanding) or during handling of iron oxide pigments. There is limited evidence of adverse effects in humans specifically linked to inhalation of iron oxides. This contrasts to oxides of other metals used to alloy or for coating of steel and iron of which several have been classified as being hazardous by international and national agencies. Such metal oxides are often present in the air at workplaces. In general, iron oxides might therefore be regarded as low-toxicity, low-solubility (LTLS) particles, and are often considered to be nontoxic even if very high and prolonged inhalation exposures might result in diseases. In animal studies, such exposures lead to cancer, fibrosis and other diseases. Our hypothesis was that pulmonary-workplace exposure during manufacture and handling of SPION preparations might be harmful. We therefore conducted a systematic review of the relevant literature to understand how iron oxides deposited in the lung are related to acute and subchronic pulmonary inflammation. We included one human and several in vivo animal studies published up to February 2023. We found 25 relevant studies that were useful for deriving occupational exposure limits (OEL) for iron oxides based on an inflammatory reaction. Our review of the scientific literature indicates that lowering of health-based occupational exposure limits might be considered.

Comparison of acute phase response in mice after inhalation and intratracheal instillation of molybdenum disulphide and tungsten particles

Inhalation studies are the gold standard for assessing the toxicity of airborne materials. They require considerable time, special equipment, and large amounts of test material. Intratracheal instillation is considered a screening and hazard assessment tool as it is simple, quick, allows control of the applied dose, and requires less test material. The particle-induced pulmonary inflammation and acute phase response in mice caused by intratracheal instillation or inhalation of molybdenum disulphide or tungsten particles were compared. End points included neutrophil numbers in bronchoalveolar lavage fluid, Saa3 mRNA levels in lung tissue and Saa1 mRNA levels in liver tissue, and SAA3 plasma protein. Acute phase response was used as a biomarker for the risk of cardiovascular disease. Intratracheal instillation of molybdenum disulphide or tungsten particles did not produce pulmonary inflammation, while molybdenum disulphide particles induced pulmonary acute phase response with both exposure methods and systemic acute phase response after intratracheal instillation. Inhalation and intratracheal instillation showed similar dose-response relationships for pulmonary and systemic acute phase response when molybdenum disulphide was expressed as dosed surface area. Both exposure methods showed similar responses for molybdenum disulphide and tungsten, suggesting that intratracheal instillation can be used for screening particle-induced acute phase response and thereby particle-induced cardiovascular disease.

Wildfire Variable Toxicity: Identifying Biomass Smoke Exposure Groupings through Transcriptomic Similarity Scoring

The prevalence of wildfires continues to grow globally with exposures resulting in increased disease risk. Characterizing these health risks remains difficult due to the wide landscape of exposures that can result from different burn conditions and fuel types. This study tested the hypothesis that biomass smoke exposures from variable fuels and combustion conditions group together based on similar transcriptional response profiles, informing which wildfire-relevant exposures may be considered as a group for health risk evaluations. Mice (female CD-1) were exposed via oropharyngeal aspiration to equal mass biomass smoke condensates produced from flaming or smoldering burns of eucalyptus, peat, pine, pine needles, or red oak species. Lung transcriptomic signatures were used to calculate transcriptomic similarity scores across exposures, which informed exposure groupings. Exposures from flaming peat, flaming eucalyptus, and smoldering eucalyptus induced the greatest responses, with flaming peat grouping with the pro-inflammatory agent lipopolysaccharide. Smoldering red oak and smoldering peat induced the least transcriptomic response. Groupings paralleled pulmonary toxicity markers, though they were better substantiated by higher data dimensionality and resolution provided through -omic-based evaluation. Interestingly, groupings based on smoke chemistry signatures differed from transcriptomic/toxicity-based groupings. Wildfire-relevant exposure groupings yield insights into risk assessment strategies to ultimately protect public health.

N-acetylcysteine alleviates fine particulate matter (PM2.5)-induced lung injury by attenuation of ROS-mediated recruitment of neutrophils and Ly6Chigh monocytes and lung inflammation

BACKGROUND

Exposure to particulate matter (PM) may contribute to lung inflammation and injury. The therapeutic effect of N-acetylcysteine (NAC), a well-known antioxidant, with regards to the prevention and treatment of fine PM (PM2.5)-induced lung injury is poorly understood. This study aimed to determine the effect of PM2.5 on the recruitment of neutrophils and Ly6C^high monocytes into lung alveoli and the production of proinflammatory proteins by stimulating the generation of reactive oxygen species (ROS), and to investigate the therapeutic effect of NAC on PM2.5-induced lung injury.

METHODS

C57BL/6 mice were exposed to a single administration of PM2.5 (200 μg/100 μl/mouse) or phosphate-buffered saline (control) via intratracheal instillation. The mice were injected intratracheally via a microsprayer aerosolizer with NAC (20 or 40 mg/kg) 1 h before PM2.5 instillation and 24 h after PM2.5 instillation. Total protein, VEGF, IL-6, and TNF-α in bronchoalveolar lavage fluid (BALF) were measured. Oxidative stress was evaluated by determining levels of malondialdehyde (MDA) and nitrite in BALF. Flow cytometric analysis was used to identify and quantify neutrophils and Ly6C^high and Ly6C_low monocyte subsets.

RESULTS

Neutrophil count, total protein, and VEGF content in BALF significantly increased after PM2.5 exposure and reached the highest level on day 2. Increased levels of TNF-alpha, IL-6, nitrite, and MDA in BALF were also noted. Flow cytometric analysis showed increased recruitment of neutrophils and Ly6C^high, but not Ly6C^low monocytes, into lung alveoli. Treatment with NAC via the intratracheal spray significantly attenuated the recruitment of neutrophils and Ly6C^high monocytes into lung alveoli in PM2.5-treated mice in a dose-dependent manner. Furthermore, NAC significantly attenuated the production of total protein, VEGF, nitrite, and MDA in the mice with PM2.5-induced lung injury in a dose-dependent manner.

CONCLUSION

PM2.5-induced lung injury caused by the generation of oxidative stress led to the recruitment of neutrophils and Ly6C^high monocytes, and production of inflammatory proteins. NAC treatment alleviated PM2.5-induced lung injury by attenuating the ROS-mediated recruitment of neutrophils and Ly6C^high monocytes and lung inflammation.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

Studies in a Murine Granuloma Model of Instilled Carbon Nanotubes: Relevance to Sarcoidosis

Poorly soluble environmental antigens, including carbon pollutants, are thought to play a role in the incidence of human sarcoidosis, a chronic inflammatory granulomatous disease of unknown causation. Currently, engineered carbon products such as multiwall carbon nanotubes (MWCNT) are manufactured commercially and have been shown to elicit acute and chronic inflammatory responses in experimental animals, including the production of granulomas or fibrosis. Several years ago, we hypothesized that constructing an experimental model of chronic granulomatosis resembling that associated with sarcoidosis might be achieved by oropharyngeal instillation of MWCNT into mice. This review summarizes the results of our efforts to define mechanisms of granuloma formation and identify potential therapeutic targets for sarcoidosis. Evidence is presented linking findings from the murine MWCNT granuloma model to sarcoidosis pathophysiology. As our goal was to determine what pulmonary inflammatory pathways might be involved, we utilized mice of knock-out (KO) backgrounds which corresponded to deficiencies noted in sarcoidosis patients. A primary example of this approach was to study mice with a myeloid-specific knock-out of the lipid-regulated transcription factor, peroxisome proliferator-activated receptor gamma (PPARγ) which is strikingly depressed in sarcoidosis. Among the major findings associated with PPARγ KO mice compared to wild-type were: (1) exacerbation of granulomatous and fibrotic histopathology in response to MWCNT; (2) elevation of inflammatory mediators; and (3) pulmonary retention of a potentially antigenic ESAT-6 peptide co-instilled with MWCNT. In line with these data, we also observed that activation of PPARγ in wild-type mice by the PPARγ-specific ligand, rosiglitazone, significantly reduced both pulmonary granuloma and inflammatory mediator production. Similarly, recognition of a deficiency of ATP-binding cassette (ABC) lipid transporter ABCG1 in sarcoidosis led us to study MWCNT instillation in myeloid-specific ABCG1 KO mice. As anticipated, ABCG1 deficiency was associated with larger granulomas and increased levels of inflammatory mediators. Finally, a transcriptional survey of alveolar macrophages from MWCNT-instilled wild-type mice and human sarcoidosis patients revealed several common themes. One of the most prominent mediators identified in both human and mouse transcriptomic analyses was MMP12. Studies with MMP12 KO mice revealed similar acute reactions to those in wild-type but at chronic time points where wild-type maintained granulomatous disease, resolution occurred with MMP12 KO mice suggesting MMP12 is necessary for granuloma progression. In conclusion, these studies suggest that the MWCNT granuloma model has relevance to human sarcoidosis study, particularly with respect to immune-specific pathways.

Vanadium Derivative Exposure Promotes Functional Alterations of VSMCs and Consequent Atherosclerosis via ROS/p38/NF-κB-Mediated IL-6 Production

Vanadium is a transition metal widely distributed in the Earth’s crust, and is a major contaminant in fossil fuels. Its pathological effect and regulation in atherosclerosis remain unclear. We found that intranasal administration of the vanadium derivative NaVO₃ significantly increased plasma and urinary vanadium levels and induced arterial lipid accumulation and atherosclerotic lesions in apolipoprotein E-deficient knockout mice (ApoE^−/−) murine aorta compared to those in vehicle-exposed mice. This was accompanied by an increase in plasma reactive oxygen species (ROS) and interleukin 6 (IL-6) levels and a decrease in the vascular smooth muscle cell (VSMC) differentiation marker protein SM22α in the atherosclerotic lesions. Furthermore, exposure to NaVO₃ or VOSO₄ induced cytosolic ROS generation and IL-6 production in VSMCs and promoted VSMC synthetic differentiation, migration, and proliferation. The anti-oxidant N-acetylcysteine (NAC) not only suppresses IL-6 production and VSMC pathological responses including migration and proliferation but also prevents atherosclerosis in ApoE^−/− mice. Inhibition experiments with NAC and pharmacological inhibitors demonstrated that NaVO₃-induced IL-6 production is signaled by ROS-triggered p38-mediated NF-κB-dependent pathways. Neutralizing anti-IL-6 antibodies impaired NaVO₃-mediated VSMC migration and proliferation. We concluded that NaVO₃ exposure activates the ROS-triggering p38 signaling to selectively induce NF-κB-mediated IL-6 production. These signaling pathways induce VSMC synthetic differentiation, migration, and proliferation, leading to lipid accumulation and atherosclerosis.

Inhale, exhale: Why particulate matter exposure in animal models are so acute?

Ecotoxicological studies that try to describe the effects of particulate matter (PM) on human health are important in order to gain a deeper understanding of their effects in disease outcomes. Because exposure protocols are not easily comparable, evaluating human PM exposure is a difficult task. Thus, interpreting ambiguous or conflicting results from different experiments could lead to misleading conclusions about the true nature of PM effects. To address these issues, we compiled a collection of relevant research articles in order to compare present PM exposure methods and extract data related to concentration, inhalation rates (IR), and doses. We also compare the experimental exposure levels reported in these articles to PM levels around the world. In particular, our dataset covers reported results from 75 research articles. To allow for comparison between protocols, we used this data to fit a normalization equation that depends upon concentration, exposure time, dose, inhalability, and physiological parameters. Based on the collected research papers, instillation is the prevalent exposure method. Also, the median PM IR from these experiments is three orders of magnitude higher than the PM IR found in environmental conditions (EAP). Experiments employing inhalation of concentrated PM show IR results that are two orders of magnitude higher than EAP; these results are cause for concerns, since the PM exposure were acute, sudden, and higher than the worst-case exposure scenarios reported by the world megacities. We also found that different PM exposure protocols are sources for the observed variability in physiological response results found from animal models. We discuss these findings and make suggestions for future exposure methodologies. Such considerations should be valuable for quantifying PM exposure in disease outcomes.

Inhale, exhale: Why particulate matter exposure in animal models are so acute? Data and facts behind the history

We present a dataset obtained by extracting information from an extensive literature search of toxicological experiments using mice and rat animal models to study the effects of exposure to airborne particulate matter (PM). Our dataset covers results reported from 75 research articles considering paper published in 2017 and seminal papers from previous years. The compiled data and normalization were processed with an equation based on a PM dosimetry model. This equation allows the comparison of different toxicological experiments using instillation and inhalation as PM exposure protocols with respect to inhalation rates, concentrations and PM exposure doses of the toxicological experiments performed by different protocols using instillation and inhalation PM as exposure methods. This data complements the discussions and interpretations presented in the research article “Inhale, exhale: why particulate matter exposure in animal models are so acute?” Curbani et al., 2019.

Toxicity of pristine and paint-embedded TiO2 nanomaterials

Little is known on the toxicity of nanomaterials in the user phase. Inclusion of nanomaterials in paints is a common nanotechnology application. This study focuses on the toxicity of dusts from sanding of paints containing nanomaterials. We compared the toxicity of titanium dioxide nanomaterials (TiO₂NMs) and dusts generated by sanding boards coated with paints with different amounts of two different types of uncoated TiO₂NMs (diameters:10.5 nm and 38 nm). Mice were intratracheally instilled with a single dose of 18, 54 and 162 µg of TiO₂NMs or 54, 162 and 486 µg of sanding dusts. At 1, 3 and 28 days post-instillation, we evaluated pulmonary inflammation, liver histology and DNA damage in lung and liver. Pulmonary exposure to both pristine TiO₂NMs and sanding dusts with different types of TiO₂NMs resulted in dose-dependently increased influx of neutrophils into the lung lumen. There was no difference between the sanding dusts from the two paints. For all exposures but not in vehicle controls, mild histological lesions were observed in the liver. Pulmonary exposure to pristine TiO₂NMs and paint dusts with TiO₂NMs caused similar type of histological lesions in the liver.

Basic study of intratracheal instillation study of nanomaterials for the estimation of the hazards of nanomaterials

In order to examine the usefulness of intratracheal instillation of nanoparticles for the screening of the harmful effects of nanoparticles, we performed intratracheal instillation studies of nanomaterials on rats using different delivery devices and postures as a basic study. Multiwall carbon nanotubes (MWCNTs) with a geometric mean length and secondary diameter of 2.16 μm and 752 nm, respectively, were used as the nanomaterials. Male F344 rats were intratracheally exposed to 0.04 or 0.2 mg/rat of MWCNT, were dissected at 1 d and 3 d, and cell analyses of the bronchoalveolar lavage fluid (BALF) were analyzed. Two delivery devices were used for the intratracheal instillation of the MWCNTs: a gavage needle and a microsprayer aerolizer. Both induced neutrophil influx in the lung at 1 and 3 d, and there were no significant differences in neutrophil inflammation between the two delivery devices. The main distribution of pulmonary inflammation by both delivery devices was in the centrilobular spaces in the lung. Two postures were used: an angle of approximately 45 degrees and a standing posture on a board, both of which also induced pulmonary influx in BALF and pulmonary inflammation mainly in the centrilobular spaces, with no large difference in pulmonary inflammation between the two postures. Taken together, the differences in the delivery devices and postures of the rats in the intratracheal instillation did not affect the acute pulmonary toxicity of the nanomaterials.

Chemical composition and redox activity of PM0.25 near Los Angeles International Airport and comparisons to an urban traffic site

To investigate the relative impacts of emissions from Los Angeles International Airport (LAX), as well as the impacts of traffic emissions from freeways, on the oxidative potential of particulate matter (PM), PM_0.25 were collected at two urban background locations in Los Angeles. Redox activity of the PM samples was measured by means of an in vitro alveolar macrophage assay that quantifies the formation of reactive oxygen species (ROS) in cells, and detailed chemical analyses were performed to determine the speciated chemical composition of collected PM. A molecular marker-based chemical mass balance (MM-CMB) model was applied to estimate the relative contributions from the following primary sources to the organic carbon (OC) component of PM: mobile sources (combined gasoline and diesel vehicles), wood smoke, vegetative detritus, road dust and ship emissions. A source profile of aircraft emissions was not included in the model; however its contribution was estimated from un-apportioned primary OC in the MM-CMB model ("other OC") after accounting for the contribution of secondary organic carbon (SOC) to OC. The contribution of mobile sources to OC was 82% and 28% at the central Los Angeles site (freeway emissions) and the LAX site, respectively. The estimated contribution of aircraft emissions to PM_0.25 OC was 36% at the LAX site. ROS activity levels showed little spatial variability, with no statistically significant difference between the averages observed at LAX (24.75±4.01μgZymosan/m³) and central Los Angeles (27.77±2 0.32μgZymosan/m³), suggesting similar levels of inhalation exposure to redox active species of PM_0.25. A multiple linear regression analysis indicated that the variability in ROS activity is best explained by the chemical markers of major identified sources: EC emitted by traffic, and sulfur, considered in our study as a potential tracer of aircraft emissions, with statistically significantly higher concentrations of sulfur at the LAX site (p<0.001).

Particulate air pollution: major research methods and applications in animal models

Ambient air pollution is composed of a heterogeneous mixture of gaseous and solid particle compounds in which primary particles are emitted directly into the atmosphere, such as diesel soot, while secondary particles are created through physicochemical transformation. Particulate matter (PM), especially fine and ultrafine particles, can be inhaled and deposited in the alveolar cavities and penetrate into circulation. An association between high levels of air pollutants and human disease has been known for more than half a century and increasing evidences demonstrate a strong link between exposure on PM and the development of systemic diseases, such as cardiovascular and neurological disorders. Experimental animal models have been extensively used to study the underlying mechanism caused by environmental exposure to ambient PM. Due to their availability, quality, cost, and genetically modified strains, rodent models have been widely used. Some common exposure approaches include intranasal instillation, intratracheal instillation, nose-only inhalation, whole-body inhalation, and intravenous injection have been reviewed with brief summary of its performance, merit, limitation, and application. We hope this would provide useful reference in advancing experimental researches about air pollution human health and disease development.

A 104-week pulmonary toxicity assessment of long and short single-wall carbon nanotubes after a single intratracheal instillation in rats

We compared long-term pulmonary toxicities after a single intratracheal instillation of two types of dispersed single-wall carbon nanotubes (SWCNTs), namely, those with relatively long or short linear shapes with average lengths of 8.6 and 0.55 µm, respectively. Both types of SWCNTs were instilled intratracheally in male F344 rats at 0.2 or 1.0 mg/kg (long SWCNTs) or 1.0 mg/kg (short SWCNTs). Pulmonary responses were characterized at 26, 52 and 104 weeks after a single instillation. Inflammatory changes, test substance deposition, test substance engulfment by macrophages, and alveolar wall fibrosis were observed in the lungs of almost all test rats at 52 and 104 weeks after short nanotube instillation. The incidences of these changes were much lower in the long nanotube-treated groups. In almost all rats of the long nanotube-treated groups, fibrosis and epithelium loss in the terminal bronchiole with test substance deposition were observed. These bronchiolar changes were not observed after administering short nanotubes. Both bronchiolo-alveolar adenoma and carcinoma were found in the negative-control group, the high-dose long-nanotube group, and the short-nanotube group at 104 weeks post-instillation, although the incidences were not statistically different. The genotoxicity of the SWCNTs was also evaluated by performing in vivo comet assays with lung cells obtained 26 weeks post-instillation. No significant changes in the percent tail deoxyribonucleic acid were found in any group. These findings suggested that most long SWCNTs were deposited at the terminal bronchioles and that a considerable amount of short SWCNTs reached the alveolus, resulting in chronic inflammatory responses, but no genotoxicity in the lungs.

Length effects of single-walled carbon nanotubes on pulmonary toxicity after intratracheal instillation in rats

We aimed to evaluate the effects of the length of single-walled carbon nanotubes (SWCNTs) on pulmonary toxicity in rats. Each rat received a single intratracheal instillation of short (S-) (average length of 0.40 μm) or long (L-) (average length of 2.77 μm) SWCNTs at a dose of 1 mg/kg and was observed for the next 6 months. Neither S- nor L-SWCNTs affected clinical signs, body weight, or autopsy findings. An increase in lung weight was observed after instillation of S- or L-SWCNTs; however, lung weights were slightly higher in the rats that were administered the S-SWCNTs. Distinct differences in bronchoalveolar lavage fluid (BALF) composition were observed between the S- and L-SWCNT-treated rats as early as 7 days after the intratracheal instillations of the SWCNTs. The S-SWCNTs caused persistent lung injury and inflammation during the 6-month observational period. However, the L-SWCNTs induced minimal lung injury and inflammation. Although the S- and L-SWCNTs changed BALF parameters and histopathological features of the lung, the magnitudes of the changes observed after the S-SWCNT treatment were greater than the respective changes observed after the L-SWCNT treatment. These findings indicate that the severity of the pulmonary toxicity caused after intratracheal instillation of SWCNT depends on the length of the SWCNTs. It appears that shorter SWCNTs induce greater pulmonary toxicity than longer SWCNTs do.

Solid Phase Speciation and Solubility of Vanadium in Highly Weathered Soils

Vanadium (V) is increasingly recognized both as a medical trace element with essential biological functions and as a potentially toxic environmental pollutant, yet the current knowledge on V speciation in soils is limited. Here, we investigated the chemical speciation and extractability of V in highly weathered tropical soils, which are often rich in V compared to soils of temperate climatic regions. Vanadium K-edge X-ray absorption near edge structure (XANES) spectra of soil samples, along with a range of reference compounds differing in V-oxidation state and coordination chemistry, revealed the predominance of V^4+/5+ in a primarily octahedral or tetrahedral coordination. The soil spectra were best fitted with linear combinations of reference spectra of V⁴⁺ in the structure of kaolinite, V⁵⁺ adsorbed to kaolinite, and other V⁵⁺-sorbed solids. Vanadate adsorbed to goethite, ferrihydrite, gibbsite, and/or Fe(III)-natural organic matter complexes and V⁴⁺ in the structure of goethite may be present, but cannot unequivocally be distinguished from each other by XANES spectroscopy. Sequential and single chemical extractions provided complementary information on the solubility of V under various conditions. The most labile V fractions, interpreted as weakly and strongly adsorbed V⁵⁺, are the most relevant to V mobility and bioavailability in the environment, and accounted for only ∼2% of total soil V. Our results demonstrate that kaolinite and Fe oxides can effectively sequester V in highly weathered soils by mechanisms of adsorption and structural incorporation and are relevant to other Fe-oxide-rich environments under acidic and oxic conditions.

A review of toxicity studies on graphene-based nanomaterials in laboratory animals

We summarized the findings of toxicity studies on graphene-based nanomaterials (GNMs) in laboratory mammals. The inhalation of graphene (GP) and graphene oxide (GO) induced only minimal pulmonary toxicity. Bolus airway exposure to GP and GO caused acute and subacute pulmonary inflammation. Large-sized GO (L-GO) was more toxic than small-sized GO (S-GO). Intratracheally administered GP passed through the air-blood barrier into the blood and intravenous GO distributed mainly in the lungs, liver, and spleen. S-GO and L-GO mainly accumulated in the liver and lungs, respectively. Limited information showed the potential behavioral, reproductive, and developmental toxicity and genotoxicity of GNMs. There are indications that oxidative stress and inflammation may be involved in the toxicity of GNMs. The surface reactivity, size, and dispersion status of GNMs play an important role in the induction of toxicity and biodistribution of GNMs. Although this review paper provides initial information on the potential toxicity of GNMs, data are still very limited, especially when taking into account the many different types of GNMs and their potential modifications. To fill the data gap, further studies should be performed using laboratory mammals exposed using the route and dose anticipated for human exposure scenarios.

Effects of Fine Particulate Matter on Erectile Function and Its Potential Mechanism in Rats

OBJECTIVE

To investigate whether the exposure to fine particulate matter (PM_2.5) in a rat model can impair erectile function and the possible mechanism.

MATERIALS AND METHODS

Sprague-Dawley rats were distributed into 4 groups (n = 9 each): 1 control group and 3 groups exposed to different levels of PM_2.5. Rats were exposed to PM_2.5 (0.0 [saline control], 0.8, 1.6, and 3.2 mg/rat). After exposure period, the ratio of maximum intracavernosal pressure to mean arterial pressure, molecular-biological indicators in corpus cavernosum tissue and plasma, and the pathologic changes of the lung tissue and penile tissue were detected and compared between the control group and the 3 exposure groups.

RESULTS

The ratio of maximum intracavernosal pressure to mean arterial pressure in 2 groups exposed to PM_2.5 was significantly lower than that of the control group only (P <.05). Exposure to PM_2.5 could trigger the significant increase of plasma malondialdehyde, vascular endothelial growth factor, C-reactive protein, and tumor necrosis factor-α in experimental groups than that of the control group (P <.05). Expression of endothelial nitric oxide synthase (NOS), neuronal NOS, cyclic guanosine monophosphate, NOS activity, and content of reactive oxygen species in penile tissue were higher than that of the control group in a dose-response way (P <.05).

CONCLUSION

The function of penile erection is impaired by exposure to PM_2.5. The decrease in the expression of endothelial NOS and NOS activity in penile cavernous tissue caused by systemic inflammatory and oxidative stress status induced by exposure to PM_2.5 may be one of the important risk factors of erectile dysfunction.

Usefulness of Intratracheal Instillation Studies for Estimating Nanoparticle-Induced Pulmonary Toxicity

Inhalation studies are the gold standard for the estimation of the harmful effects of respirable chemical substances, while there is limited evidence of the harmful effects of chemical substances by intratracheal instillation. We reviewed the effectiveness of intratracheal instillation studies for estimating the hazards of nanoparticles, mainly using papers in which both inhalation and intratracheal instillation studies were performed using the same nanoparticles. Compared to inhalation studies, there is a tendency in intratracheal instillation studies that pulmonary inflammation lasted longer in the lungs. A difference in pulmonary inflammation between high and low toxicity nanoparticles was observed in the intratracheal instillation studies, as in the inhalation studies. Among the endpoints of pulmonary toxicity, the kinetics of neutrophil counts, percentage of neutrophils, and chemokines for neutrophils and macrophages, heme oxygenase-1 (HO-1) in bronchoalveolar lavage fluid (BALF), reflected pulmonary inflammation, suggesting that these markers may be considered the predictive markers of pulmonary toxicity in both types of study. When comparing pulmonary inflammation between intratracheal instillation and inhalation studies under the same initial lung burden, there is a tendency that the inflammatory response following the intratracheal instillation of nanoparticles is greater than or equal to that following the inhalation of nanoparticles. If the difference in clearance in both studies is not large, the estimations of pulmonary toxicity are close. We suggest that intratracheal instillation studies can be useful for ranking the hazard of nanoparticles through pulmonary inflammation.

Orotracheal administration of contrast agents: a new protocol for brain tumor targeting

The development of new non-invasive diagnostic and therapeutic approaches is of paramount importance in order to improve the outcome of patients with glioblastoma (GBM). In this work we investigated a completely non-invasive pre-clinical protocol to effectively target and detect brain tumors through the orotracheal route, using ultra-small nanoparticles (USRPs) and MRI. A mouse model of GBM was developed. In vivo MRI acquisitions were performed before and after intravenous or orotracheal administration of the nanoparticles to identify and segment the tumor. The accumulation of the nanoparticles in neoplastic lesions was assessed ex vivo through fluorescence microscopy. Before the administration of contrast agents, MR images allowed the identification of the presence of abnormal brain tissue in 73% of animals. After orotracheal or intravenous administration of USRPs, in all the mice an excellent co-localization of the position of the tumor with MRI and histology was observed. The elimination time of the USRPs from the tumor after the orotracheal administration was approximately 70% longer compared with intravenous injection. MRI and USRPs were shown to be powerful imaging tools able to detect, quantify and longitudinally monitor the development of GBMs. The absence of ionizing radiation and high resolution of MRI, along with the complete non-invasiveness and good reproducibility of the proposed protocol, make this technique potentially translatable to humans. To our knowledge, this is the first time that the advantages of a needle-free orotracheal administration route have been demonstrated for the investigation of the pathomorphological changes due to GBMs.

Rat lung response to ozone and fine particulate matter (PM2.5) exposures

Exposure to different ambient pollutants maybe more toxic to lung than exposure to a single pollutant. In this study, we discussed the inflammation and oxidative stress responses of rat lung caused by ozone and PM2.5 versus that of rats exposed to saline, ozone, or single PM2.5 . Wistar rats inhaled 0.8 ppm ozone or air for 4 h and then placed in air for 3 h following intratracheal instillation with 0, 0.2 (low dose), 0.8 (medium dose), 3.2 (high dose) mg/rat PM2.5 dissolved in sterile saline (0.25 mL/rat), repeated twice per week for 3 weeks, the cumulative doses of PM2.5 in animals were 1.2, 4.8, and 19.2 mg. Rats were sacrificed 24 h after the last (sixth) exposure. The collected bronchoalveolar lavage fluid (BALF) was analyzed for inflammatory cells and cytokines. Lung tissues were processed for light microscopic and transmission electron microscopic (TEM) examinations. Results showed that total cell number in BALF of PM2.5 -exposed groups were higher than control (p < 0.05). PM2.5 instillation caused dose-trend increase in tumor necrosis factor alpha (TNF-α), interleukin-6, lactate dehydrogenase, and total protein of BALF. Exposure to ozone alone only caused TNF-α significant change in above-mentioned indicators of lung injury. On the other hand, ozone could enhance PM2.5-induced inflammatory changes and pathological characters in rat lungs. SOD and GSH-Px activities in lung were reduced in PM2.5-exposed rats with and without prior ozone exposure compared to control. To determine whether the PM2.5 and ozone affect endothelium system, iNOS, eNOS, and ICAM-1 mRNA levels in lung were analyzed by real-time PCR. These data demonstrated that inflammation and oxidative stress were involved in toxicology mechanisms of PM2.5 in rat lung and ozone potentiated these effects induced by PM2.5. These results have implications for understanding the pulmonary effects induced by ozone and PM2.5.

Nebulized gadolinium-based nanoparticles: a theranostic approach for lung tumor imaging and radiosensitization

Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium-based ultra-small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo-time magnetic resonance imaging (UTE-MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non-invasively using fluorescence tomography or UTE-MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization.

Ozone co-exposure modifies cardiac responses to fine and ultrafine ambient particulate matter in mice: concordance of electrocardiogram and mechanical responses

Background

Studies have shown a relationship between air pollution and increased risk of cardiovascular morbidity and mortality. Due to the complexity of ambient air pollution composition, recent studies have examined the effects of co-exposure, particularly particulate matter (PM) and gas, to determine whether pollutant interactions alter (e.g. synergistically, antagonistically) the health response. This study examines the independent effects of fine (FCAPs) and ultrafine (UFCAPs) concentrated ambient particles on cardiac function, and determine the impact of ozone (O₃) co-exposure on the response. We hypothesized that UFCAPs would cause greater decrement in mechanical function and electrical dysfunction than FCAPs, and that O₃ co-exposure would enhance the effects of both particle-types.

Methods

Conscious/unrestrained radiotelemetered mice were exposed once whole-body to either 190 μg/m³ FCAPs or 140 μg/m³ UFCAPs with/without 0.3 ppm O₃; separate groups were exposed to either filtered air (FA) or O₃ alone. Heart rate (HR) and electrocardiogram (ECG) were recorded continuously before, during and after exposure, and cardiac mechanical function was assessed using a Langendorff perfusion preparation 24 hrs post-exposure.

Results

FCAPs alone caused a significant decrease in baseline left ventricular developed pressure (LVDP) and contractility, whereas UFCAPs did not; neither FCAPs nor UFCAPs alone caused any ECG changes. O₃ co-exposure with FCAPs caused a significant decrease in heart rate variability when compared to FA but also blocked the decrement in cardiac function. On the other hand, O₃ co-exposure with UFCAPs significantly increased QRS-interval, QTc and non-conducted P-wave arrhythmias, and decreased LVDP, rate of contractility and relaxation when compared to controls.

Conclusions

These data suggest that particle size and gaseous interactions may play a role in cardiac function decrements one day after exposure. Although FCAPs + O₃ only altered autonomic balance, UFCAPs + O₃ appeared to be more serious by increasing cardiac arrhythmias and causing mechanical decrements. As such, O₃ appears to interact differently with FCAPs and UFCAPs, resulting in varied cardiac changes, which suggests that the cardiovascular effects of particle-gas co-exposures are not simply additive or even generalizable. Additionally, the mode of toxicity underlying this effect may be subtle given none of the exposures described here impaired post-ischemia recovery.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0054-4) contains supplementary material, which is available to authorized users.

Exposure to particular matter increases susceptibility to respiratory Staphylococcus aureus infection in rats via reducing pulmonary natural killer cells

Epidemiological studies have shown a correlation between exposure to fine particular matter (PM2.5) and increased respiratory infection, but the mechanisms have remained poorly defined. By using an experimental system we evaluated the effect of PM2.5 exposure on susceptibility to subsequent pulmonary Staphylococcus aureus (S. aureus) infection and its potential mechanisms. Rats were intratracheally instilled with a single dose of PM2.5 sample or PBS followed by an intratracheal inoculation with bacteria S. aureus at 24h after PM2.5 exposure. The rats were examined at 24h post infection. We found that exposure of rats to PM2.5 significantly increased inflammatory cells and levels of IL-6 and TNF-α in bronchoalveolar lavage fluids (BALF). Prior PM2.5 exposure markedly increased the susceptibility of rats to subsequent S. aureus infection. The mechanistic studies showed that alveolar macrophages (AMs) from PM2.5-experienced lungs had depressed phagocytosis of S. aureus, and prior PM2.5 exposure significantly decreased the natural killer (NK) cells recruited into the airways following subsequent S. aureus infection. Further, adoptive transfer of naive NK cells to the lung of prior PM2.5-exposed rats restored PM2.5-impaired antibacterial host defense. The presence of NK cells markedly enhanced the ability of AMs to phagocytose S. aureus ex vivo. Thus, our study identifies PM2.5-impaired NK cell response in the lung to be a novel critical mechanism for PM2.5-mediated susceptibility to S. aureus bacterial infection, which provides a potential mechanism to explain the epidemiological findings that associate ambient air pollution and increased lung bacterial infections. Our findings also suggest that enhancing pulmonary NK cells may be considered for future therapeutic approaches to clinically antibiotic-resistant S. aureus infection in the lung.

Carbon Nanotubes and Chronic Granulomatous Disease

Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

Equivalent titanium dioxide nanoparticle deposition by intratracheal instillation and whole body inhalation: the effect of dose rate on acute respiratory tract inflammation

Background

The increased production of nanomaterials has caused a corresponding increase in concern about human exposures in consumer and occupational settings. Studies in rodents have evaluated dose–response relationships following respiratory tract (RT) delivery of nanoparticles (NPs) in order to identify potential hazards. However, these studies often use bolus methods that deliver NPs at high dose rates that do not reflect real world exposures and do not measure the actual deposited dose of NPs. We hypothesize that the delivered dose rate is a key determinant of the inflammatory response in the RT when the deposited dose is constant.

Methods

F-344 rats were exposed to the same deposited doses of titanium dioxide (TiO₂) NPs by single or repeated high dose rate intratracheal instillation or low dose rate whole body aerosol inhalation. Controls were exposed to saline or filtered air. Bronchoalveolar lavage fluid (BALF) neutrophils, biochemical parameters and inflammatory mediator release were quantified 4, 8, and 24 hr and 7 days after exposure.

Results

Although the initial lung burdens of TiO₂ were the same between the two methods, instillation resulted in greater short term retention than inhalation. There was a statistically significant increase in BALF neutrophils at 4, 8 and 24 hr after the single high dose TiO₂ instillation compared to saline controls and to TiO₂ inhalation, whereas TiO₂ inhalation resulted in a modest, yet significant, increase in BALF neutrophils 24 hr after exposure. The acute inflammatory response following instillation was driven primarily by monocyte chemoattractant protein-1 and macrophage inflammatory protein-2, mainly within the lung. Increases in heme oxygenase-1 in the lung were also higher following instillation than inhalation. TiO₂ inhalation resulted in few time dependent changes in the inflammatory mediator release. The single low dose and repeated exposure scenarios had similar BALF cellular and mediator response trends, although the responses for single exposures were more robust.

Conclusions

High dose rate NP delivery elicits significantly greater inflammation compared to low dose rate delivery. Although high dose rate methods can be used for quantitative ranking of NP hazards, these data caution against their use for quantitative risk assessment.

Quantitative biodistribution and pharmacokinetics of multimodal gadolinium-based nanoparticles for lungs using ultrashort TE MRI

OBJECTIVE

To study the biodistribution and lung pharmacokinetics of tracheally administered gadolinium-based contrast agents [gadoteric acid and multimodal ultra-small rigid platforms (USRPs)], to validate their pharmacokinetics against optical imaging of fluorescent USRPs, and to test their short-term toxicity.

MATERIALS AND METHODS

Ultrashort echo-time (UTE) lung proton magnetic resonance imaging (MRI) was performed at 4.7-Tesla (T) after the intratracheal instillation of different concentrations of contrast agent solutions in mice. Pharmacokinetic models were implemented on the absolute concentration calculated from the MRI signal enhancement measurements. Fluorescent USRPs were used to obtain optical images with the same protocol. Bronchoalveolar lavage inflammatory cell count and serum creatinine measurement were performed on four groups of instilled mice (sham, saline, USRPs, lipopolysaccharide).

RESULTS

MR and optical imaging showed similar kinetics of the USRPs, passing from the airways to the lung tissue and to the kidneys, with negligible hepatic clearance. No significant increase of lung and renal inflammation markers were observed in USRP-instilled animals.

CONCLUSION

A T 1-weighted radial UTE sequence was found to be valuable in quantitatively monitoring the biodistribution and pharmacokinetics of nanoparticles in the lungs of mice. The observed favorable pharmacokinetics, which was validated by fluorescence imaging, ensures the negligible toxicity of the nanoprobes, making the USRPs and the developed protocol good candidates for applications on selected lung diseases.

Developmental effects of aerosols and coal burning particles in zebrafish embryos

Embryo toxicity of particles generated by combustion processes is of special concern for human health. A significant part of these toxic effects is linked to the binding of some pollutants (like polycyclic aromatic hydrocarbons or PAHs) to the Aryl hydrocarbon Receptor (AhR) and the activation of target genes, like the cytochrome P4501A. This activity was analyzed for ambient air and coal-combustion particle extracts in zebrafish embryos (the cyp1aDarT assay) and in two single-cell bioassays: the yeast-based YCM-RYA and the DR-luc (rat cells) assay. Observed AhR ligand activity of samples generally correlated to the predicted toxic effect according to their PAH composition, except for one of the coal combustion samples with an anomalously high activity in the cyp1aDarT assay. This sample induced deformities in zebrafish embryos. We concluded that the combination of morphological and molecular assays may detect embryonic toxic effects that cannot be predicted from chemical analyses or single-cell bioassays.

Comparison of dose-response relations between 4-week inhalation and intratracheal instillation of NiO nanoparticles using polimorphonuclear neutrophils in bronchoalveolar lavage fluid as a biomarker of pulmonary inflammation

Inhalation studies and intratracheal instillation studies using laboratory animals are commonly conducted for pulmonary toxicity tests of nanomaterials. In our study, male Wister rats were exposed to nickel oxide (NiO) particles including a nano-scale, even for aerosols and suspensions, in a 4-week inhalation and intratracheal instillation. Using polymorphonuclear neutrophils (PMNs) in bronchoalveolar lavage fluid as a biomarker of inflammation, we attempted to quantify the relationship between responses to inhalation and intratracheal instillation of the nanoparticles, based on surface area doses. Four kinds of NiO suspension samples with different specific surface areas were singly injected via the tracheas of the rats. The relationship between the instilled doses and PMN production was examined 3 days and 1 month after the instillation. In parallel, 4-week inhalation studies, using two of the suspensions, were conducted for aerosols generated by a pressurized nebulizer. NiO samples induced PMN responses 3 days after instillation according to the surface area doses, but not the mass doses, as has been reported in many studies. When the same NiO samples were tested in a 4-week inhalation and intratracheal instillation, the amount of pulmonary deposition of the sample after the 4-week inhalation, and an intratracheally instilled dose about ten-times higher, induced similar PMN responses 3 days after termination of inhalation and instillation. Using the relationship between these responses to 4-week inhalation and intratracheal instillation, it may be possible to estimate what aerosol concentrations of other nanomaterials might cause the same responses of PMN production as intratracheal instillation tests.

Pulmonary inflammation and tissue damage in the mouse lung after exposure to PM samples from biomass heating appliances of old and modern technologies

Current levels of ambient air fine particulate matter (PM(2.5)) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM(2.5) emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM(1) emissions from five modern and two old technology appliances were examined. The PM(1) samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15 mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM(1) (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM(1) (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect.

Contrast enhanced lung MRI in mice using ultra-short echo time radial imaging and intratracheally administrated Gd-DOTA-based nanoparticles

PURPOSE

To investigate the in vivo T1 -enhancement of the lung parenchyma in free-breathing healthy mice following intratracheal administration of Gd-DOTA-based nanoparticles, to assess the enhancement kinetics of the instilled contrast medium and to identify its elimination pathways.

METHODS

Ultrashort Echo Time (276 μs) proton MRI of the lung was performed (N = 14) at 4.7 T after the intratracheal instillation of 50 μL of seven different concentrations of contrast agent solution (from 2 to 100 mM of Gd(3+) ). The signal enhancement (SE) in lungs, blood, liver, kidneys, and bladder was assessed (N = 3) for a 50 mM concentration solution at different time points.

RESULTS

The largest SE in lungs (266 ± 14%) was observed for a 50 mM solution of Gd(3+) . In lungs, the SE was observed to decay exponentially with a time constant of 149 ± 51 min. The passage of the nanoparticles from lung tissue to blood and kidneys, and ultimately to the bladder, was observed. No significant hepatic enhancement was measured.

CONCLUSION

This study demonstrates the feasibility of large SEs of lung tissue using intratracheally administrated solutions of Gd-based contrast agents. In future applications, the SE in lungs could be used to image the biodistribution of coadministrated drug aerosols or to selectively enhance lung diseased tissues.

Effects of ozone and fine particulate matter (PM(2.5)) on rat system inflammation and cardiac function

In order to understand the toxic mechanisms of cardiovascular system injuries induced by ambient PM(2.5) and/or ozone, a subacute toxicological animal experiment was designed with exposure twice a week for 3 continuous weeks. Wistar rats were randomly categorized into 8 groups (n=6): 1 control group, 3 groups exposed to fine particulate matters (PM(2.5)) alone at 3 doses (0.2, 0.8, or 3.2 mg/rat), 1 group to ozone (0.81 ppm) alone and 3 groups to ozone plus PM(2.5) at 3 doses (0.2, 0.8, or 3.2 mg/rat). Heart rate (HR) and electrocardiogram (ECG) was monitored at approximately 24-h both after the 3rd exposure and the last (6th) exposure, and systolic blood pressure (SBP) was monitored at approximately 24-h after the 6th exposure. Biomarkers of systemic inflammation and injuries (CRP, IL-6, LDH, CK), heart oxidative stress (MDA, SOD) and endothelial function (ET-1, VEGF) were analyzed after the 6th exposure. Additionally, myocardial ultrastructural alterations were observed under transmission electron microscopy (TEM) for histopathological analyses. Results showed that PM(2.5) alone exposure could trigger the significant increase of CRP, MDA, CK, ET-1 and SBP and decrease of heart rate variability (HRV), a marker of cardiac autonomic nervous system (ANS) function. Ozone alone exposure in rats did not show significant alterations in any indicators. Ozone plus PM(2.5) exposure, however, induced CRP, IL-6, CK, LDH and MDA increase, SOD and HRV decrease significantly in a dose-response way. Meanwhile, abnormal ECG types were monitored in rats exposed to PM(2.5) with and without ozone and obvious myocardial ultrastructural changes were observed by TEM. In conclusion, PM(2.5) alone exposure could cause inflammation, endothelial function and ANS injuries, and ozone potentiated these effects induced by PM(2.5).

Bioaccessible heavy metals-sediment particles from Reconquista River induce lung inflammation in mice

The Reconquista River (RR), one of the most polluted watercourses in Argentina, receives effluent discharges from heavily industrialized and highly populated settlements. During winter and summer, the floodplain remains dry, producing the oxidation of sulfide and organic matter present in the sediment, making heavy metals more bioaccessible. Dispersion of this sediment occurs, and thus harmful effects on the pulmonary health of residents and workers inhabiting the RR bank may take place. The authors characterized the sediment particles of the RR (RR-PM) morphologically by scanning electron microscopy and its elemental composition by energy dispersive X-ray spectroscopy (EDX) and Community Bureau of Reference (BCR) sequential extraction. Furthermore, the authors evaluated its biological impact on the respiratory system of BALB/c mice, generating four groups: control healthy, sensibilized with ovalbumin, exposed to particles, and sensibilized and exposed to particles. Sediment particles of the Reconquista River contained fine particulate matter, with a high concentration of bioaccessible Cu and Zn. The authors found that animal exposure to RR-PM caused polymorphonuclear cell lung infiltration, augmentation of O2(-), increase of proinflammatory cytokines (tumor necrosis factor alpha [TNFα], interleukin-6 [IL-6]) and apoptosis. This adverse response was more dramatic in the sensibilized and exposed to particles group. Even more, they proved the bioaccessible fraction present in the RR-PM to be responsible for these harmful effects. The authors conclude that RR-PM produces an adverse biological impact on the airways of healthy animals, which is largely aggravated in previously sensibilized animals.

Effect of submicron and nano-iron oxide particles on pulmonary immunity in mice

Due to advances in nanotechnology, exposure to particle compounds in the workplace has become unavoidable. Assessment of their toxicity on health is an important occupational safety issue. This study was conducted in mice to investigate the toxicological effects of submicron and nano-iron oxide particles on pulmonary immune defences. In that purpose, we explored for the first time, inflammatory and immune responses in lung-associated lymph nodes. For each particle type, mice received either a single intratracheal instillation at different concentrations (250, 375, or 500μg/mouse) or four repeated instillations at 500μg/mouse each. Cytokine production, inflammatory and innate immune response, and humoral immune response were respectively assessed 1, 2, and 6 days after particle exposures. Both types of particles induced lung inflammation associated with increased cytokine productions in lymph node cell cultures and decreased pulmonary immune responses against sheep erythrocytes. Natural killer activity was not modified by particles. In comparison to single instillation, repeated instillations resulted in a reduction of inflammatory cell numbers in both bronchoalveolar lavages and pulmonary parenchyma. Moreover, the single instillation model demonstrated that, for a same dose, nano-iron oxide particles produced higher levels of inflammation and immunodepression than their submicron-sized counterparts.

Chemical speciation of vanadium in particulate matter emitted from diesel vehicles and urban atmospheric aerosols

We report on the development and application of an integrated set of analytical tools that enable accurate measurement of total, extractable, and, importantly, the oxidation state of vanadium in sub-milligram masses of environmental aerosols and solids. Through rigorous control of blanks, application of magnetic-sector-ICPMS, and miniaturization of the extraction/separation methods we have substantially improved upon published quantification limits. The study focused on the application of these methods to particulate matter (PM) emissions from diesel vehicles, both in baseline configuration without after-treatment and also equipped with advanced PM and NO(x) emission controls. Particle size-resolved vanadium speciation data were obtained from dynamometer samples containing total vanadium pools of only 0.2-2 ng and provide some of the first measurements of the oxidation state of vanadium in diesel vehicle PM emissions. The emission rates and the measured fraction of V(V) in PM from diesel engines running without exhaust after-treatment were both low (2-3 ng/mile and 13-16%, respectively). The V(IV) species was measured as the dominant vanadium species in diesel PM emissions. A significantly greater fraction of V(V) (76%) was measured in PM from the engine fitted with a prototype vanadium-based selective catalytic reductors (V-SCR) retrofit. The emission rate of V(V) determined for the V-SCR equipped vehicle (103 ng/mile) was 40-fold greater than that from the baseline vehicle. A clear contrast between the PM size-distributions of V(V) and V(IV) emissions was apparent, with the V(V) distribution characterized by a major single mode in the ultrafine (<0.25 μm) size range and the V(IV) size distribution either flat or with a small maxima in the accumulation mode (0.5-2 μm). The V(V) content of the V-SCR PM (6.6 μg/g) was 400-fold greater than that in PM from baseline (0.016 μg/g) vehicles, and among the highest of all environmental samples examined. Synchrotron based V 1s XANES spectroscopy of vanadium-containing fine-particle PM from the V-SCR identified V(2)O(5) as the dominant vanadium species.

Inflammatory and genotoxic effects of sanding dust generated from nanoparticle-containing paints and lacquers

Nanoparticles are increasingly used in paints and lacquers. Little is known of the toxicity of nanoparticles incorporated in complex matrices and released during different phases of the life cycle. DNA damaging activity and inflammogenicity of sanding dust sampled during standardised sanding of boards painted with paints with and without nanoparticles were determined 24 h after intratracheal instillation of a single dose of 54 μg in mice. Dusts from nanoparticle-containing paints and lacquers did not generate pulmonary inflammation or oxidative stress. Sanding dust from both the nanoparticle-containing and the conventional lacquer and the outdoor acrylic-based reference paint increased the level of DNA strand breaks in bronchoalveolar fluid cells. In conclusion, addition of nanoparticles to paint or lacquers did not increase the potential of sanding dust for causing inflammation, oxidative stress or DNA damage, suggesting that the paint/lacquer matrix is more important as determinant of DNA damage than the nanomaterial.

Spatial and seasonal distribution of aerosol chemical components in New York City: (1) Incineration, coal combustion, and biomass burning

We describe spatial and temporal patterns of fine particulate matter (PM(2.5)) and of 12 of its constituent chemical elements commonly observed in measurements at residential locations in New York City (NYC). These elements, that is, Ni, V, As, Se, S, Cl, Na, K, Pb, Cu, Zn, and Mn, had significant spatial and temporal variability at 10 PM(2.5) sampling locations during our winter and summer sampling campaigns. By grouping the elements into traditional source apportionment categories, we show that specific chemical components of PM(2.5) considered to have a common source category, such as As and Se for coal combustion, do not always follow the same temporal or spatial pattern. PM(2.5) mass had only limited spatial variability and a slight summertime concentration enhancement. Measurements at residential locations were, on average, consistent with EPA sampling network measurements, although we found that during times of low regional concentration, EPA measurements underestimated the PM(2.5) concentration at residential locations. These results have implications for improved understanding of exposures to specific sources of PM(2.5), and raise some concerns about source profiles used in source-receptor modeling tracer input selection.

Novel murine model of chronic granulomatous lung inflammation elicited by carbon nanotubes

Lung granulomas are associated with numerous conditions, including inflammatory disorders, exposure to environmental pollutants, and infection. Osteopontin is a chemotactic cytokine produced by macrophages, and is implicated in extracellular matrix remodeling. Furthermore, osteopontin is up-regulated in granulomatous disease, and osteopontin null mice exhibit reduced granuloma formation. Animal models currently used to investigate chronic lung granulomatous inflammation bear a pathological resemblance, but lack the chronic nature of human granulomatous disease. Carbon nanoparticles are generated as byproducts of combustion. Interestingly, experimental exposures to carbon nanoparticles induce pulmonary granuloma-like lesions. However, the recruited cellular populations and extracellular matrix gene expression profiles within these lesions have not been explored. Because of the rapid resolution of granulomas in current animal models, the mechanisms responsible for persistence have been elusive. To overcome the limitations of previous models, we investigated whether a model using multiwall carbon nanoparticles would resemble chronic human lung granulomatous inflammation. We hypothesized that pulmonary exposure to multiwall carbon nanoparticles would induce granulomas, elicit a macrophage and T-cell response, and mimic other granulomatous disorders with an up-regulation of osteopontin. This model demonstrates: (1) granulomatous inflammation, with macrophage and T-cell infiltration; (2) resemblance to the chronicity of human granulomas, with persistence up to 90 days; and (3) a marked elevation of osteopontin, metalloproteinases, and cell adhesion molecules in granulomatous foci isolated by laser-capture microdissection and in alveolar macrophages from bronchoalveolar lavage. The establishment of such a model provides an important platform for mechanistic studies on the persistence of granuloma.

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

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

Comparison of functional, biochemical, and morphometric alterations in the lungs of 4 rat strains and hamsters following repeated intratracheal instillation of crocidolite asbestos

Four rat strains and hamsters were exposed to 0.7 mg crocidolite asbestos/g lung once/week for 3 weeks by intratracheal instillation (IT). Pulmonary function, biochemistry, and morphometry were evaluated at 3 and 6 months after IT. Each rat strain, but not the hamster, exhibited elevated lung volumes. Quasistatic compliance in rats and hamsters was reduced 15%-40% and 25%-50%, respectively. Diffusing capacity for carbon monoxide was elevated in the rats, but in hamsters, it was reduced at both time points. Hydroxyproline was increased in the rat strains but not in hamsters. Lung protein/dry weight was not altered in most of the rat strains and in hamsters at both time points. The linear mean intercept value was increased in Fischer 344 (F344) rats (3 and 6 months) and Long Evans rats (6 months), whereas in hamsters only at 6 months. Surface area was unchanged in both species. Specific density for parenchymal tissue was reduced for F344 rats at both time points, but alveolar density values did not change overall relative to species and time. The correlated functional and morphological changes in the hamster appeared more consistent with human asbestosis. Divergent lung responses in different species and strains should be considered when selecting laboratory animal models for studies related to asbestos exposure.

Particulate matter inhalation exacerbates cardiopulmonary injury in a rat model of isoproterenol-induced cardiomyopathy

Ambient particulate matter (PM) exposure is linked to cardiovascular events and death, especially among individuals with heart disease. A model of toxic cardiomyopathy was developed in Spontaneously Hypertensive Heart Failure (SHHF) rats to explore potential mechanisms. Rats were infused with isoproterenol (ISO; 2.5 mg/kg/day subcutaneous [sc]), a beta-adrenergic agonist, for 28 days and subsequently exposed to PM by inhalation. ISO induced tachycardia and hypotension throughout treatment followed by postinfusion decrements in heart rate, contractility, and blood pressures (systolic, diastolic, pulse), and fibrotic cardiomyopathy. Changes in heart rate and heart rate variability (HRV) 17 days after ISO cessation indicated parasympathetic dominance with concomitantly altered ventilation. Rats were subsequently exposed to filtered air or Harvard Particle 12 (HP12) (12 mg/m(3))--a metal-rich oil combustion-derived PM--at 18 and 19 days (4 h/day) after ISO infusion via nose-only inhalation to determine if cardio-impaired rats were more responsive to the effects of PM exposure. Inhalation of PM among ISO-pretreated rats significantly increased pulmonary lactate dehydrogenase, serum high-density lipoprotein (HDL) cholesterol, and heart-to-body mass ratio. PM exposure increased the number of ISO-pretreated rats that experienced bradyarrhythmic events, which occurred concomitantly with acute alterations of HRV. PM, however, did not significantly affect mean HRV in the ISO- or saline-pretreated groups. In summary, subchronic ISO treatment elicited some pathophysiologic and histopathological features of heart failure, including cardiomyopathy. The enhanced sensitivity to PM exposure in SHHF rats with ISO-accelerated cardiomyopathy suggests that this model may be useful for elucidating the mechanisms by which PM exposure exacerbates heart disease.