Intravenous and gastric cerium dioxide nanoparticle exposure disrupts microvascular smooth muscle signaling

The effect and mechanisms of nano cerium dioxide (Nano-CeO2) on cardiovascular development in zebrafish (Danio rerio)

The widespread application of nano-cerium dioxide (Nano-CeO2) in agriculture, industry, and other fields has led to an increasing amount of it being released into the environment and becoming a pollutant with potential biological hazards. However, studies on the effects of ceria on cardiovascular development were limited. This study aims to detect the cardiovascular toxicity of Nano-CeO2, focusing on its impact on zebrafish hematopoietic function and cardiac development, and to explore its potential molecular mechanisms. We found that exposing zebrafish embryos to different concentrations of Nano-CeO2 after 6 hpf of fertilization does not hinder the growth and development of zebrafish embryos during their early life stages. However, RNA-Seq analysis indicated that the gene expression related to zebrafish hematopoiesis was significantly downregulated, and the ECM-receptor interaction pathway was disrupted.The results of o-dianisidine staining, neutral red staining, and Sudan black staining showed that the hemoglobin, macrophages, and neutrophils of zebrafish were reduced, and the vascular dysplasia of zebrafish was observed. Meanwhile, Reactive oxygen species (ROS) accumulated in the heart of zebrafish larvae treated with Nano-CeO2, and heart development-related genes (nppa, hand2, nppb, nkx2.5, and myh7) were significantly down-regulated, while gata4 was up-regulated. The addition of the integrin agonist manganese ions restored the expression of genes related to ECM-receptor interaction pathways, alleviating cardiovascular abnormalities caused by Nano-CeO2. Besides, significant changes in cardiac histopathology were observed with long-term exposure (120 d post-fertilization), indicating that Nano-CeO2 exposure affected the development of the cardiovascular system in zebrafish. In summary, acute and chronic exposure to Nano-CeO2 exhibits cardiovascular toxicity in zebrafish, affecting hematopoietic function and cardiac development, and the mechanism may be related to the ECM-receptor interaction pathway. This study provides useful information for a comprehensive understanding of the toxicity mechanisms and environmental risks of Nano-CeO2.

Lung versus gut exposure to air pollution particles differentially affect metabolic health in mice

BACKGROUND

Air pollution has emerged as an unexpected risk factor for diabetes. However, the mechanism behind remains ill-defined. So far, the lung has been considered as the main target organ of air pollution. In contrast, the gut has received little scientific attention. Since air pollution particles can reach the gut after mucociliary clearance from the lungs and through contaminated food, our aim was to assess whether exposure deposition of air pollution particles in the lung or the gut drive metabolic dysfunction in mice.

METHODS

To study the effects of gut versus lung exposure, we exposed mice on standard diet to diesel exhaust particles (DEP; NIST 1650b), particulate matter (PM; NIST 1649b) or phosphate-buffered saline by either intratracheal instillation (30 µg 2 days/week) or gavage (12 µg 5 days/week) over at least 3 months (total dose of 60 µg/week for both administration routes, equivalent to a daily inhalation exposure in humans of 160 µg/m³ PM_2.5) and monitored metabolic parameters and tissue changes. Additionally, we tested the impact of the exposure route in a "prestressed" condition (high-fat diet (HFD) and streptozotocin (STZ)).

RESULTS

Mice on standard diet exposed to particulate air pollutants by intratracheal instillation developed lung inflammation. While both lung and gut exposure resulted in increased liver lipids, glucose intolerance and impaired insulin secretion was only observed in mice exposed to particles by gavage. Gavage with DEP created an inflammatory milieu in the gut as shown by up-regulated gene expression of pro-inflammatory cytokines and monocyte/macrophage markers. In contrast, liver and adipose inflammation markers were not increased. Beta-cell secretory capacity was impaired on a functional level, most likely induced by the inflammatory milieu in the gut, and not due to beta-cell loss. The differential metabolic effects of lung and gut exposures were confirmed in a "prestressed" HFD/STZ model.

CONCLUSIONS

We conclude that separate lung and gut exposures to air pollution particles lead to distinct metabolic outcomes in mice. Both exposure routes elevate liver lipids, while gut exposure to particulate air pollutants specifically impairs beta-cell secretory capacity, potentially instigated by an inflammatory milieu in the gut.

Nanoparticles: Taking a Unique Position in Medicine

The human nature of curiosity, wonder, and ingenuity date back to the age of humankind. In parallel with our history of civilization, interest in scientific approaches to unravel mechanisms underlying natural phenomena has been developing. Recent years have witnessed unprecedented growth in research in the area of pharmaceuticals and medicine. The optimism that nanotechnology (NT) applied to medicine and drugs is taking serious steps to bring about significant advances in diagnosing, treating, and preventing disease-a shift from fantasy to reality. The growing interest in the future medical applications of NT leads to the emergence of a new field for nanomaterials (NMs) and biomedicine. In recent years, NMs have emerged as essential game players in modern medicine, with clinical applications ranging from contrast agents in imaging to carriers for drug and gene delivery into tumors. Indeed, there are instances where nanoparticles (NPs) enable analyses and therapies that cannot be performed otherwise. However, NPs also bring unique environmental and societal challenges, particularly concerning toxicity. Thus, clinical applications of NPs should be revisited, and a deep understanding of the effects of NPs from the pathophysiologic basis of a disease may bring more sophisticated diagnostic opportunities and yield more effective therapies and preventive features. Correspondingly, this review highlights the significant contributions of NPs to modern medicine and drug delivery systems. This study also attempted to glimpse the future impact of NT in medicine and pharmaceuticals.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.

Cerium dioxide, a Jekyll and Hyde nanomaterial, can increase basal and decrease elevated inflammation and oxidative stress

It was hypothesized that the catalyst nanoceria can increase inflammation/oxidative stress from the basal and reduce it from the elevated state. Macrophages clear nanoceria. To test the hypothesis, M0 (non-polarized), M1- (classically activated, pro-inflammatory), and M2-like (alternatively activated, regulatory phenotype) RAW 264.7 macrophages were nanoceria exposed. Inflammatory responses were quantified by IL-1β level, arginase activity, and RT-qPCR and metabolic changes and oxidative stress by the mito and glycolysis stress tests (MST and GST). Morphology was determined by light microscopy, macrophage phenotype marker expression, and a novel three-dimensional immunohistochemical method. Nanoceria blocked IL-1β and arginase effects, increased M0 cell OCR and GST toward the M2 phenotype and altered multiple M1- and M2-like cell endpoints toward the M0 level. M1-like cells had greater volume and less circularity/roundness. M2-like cells had greater volume than M0 macrophages. The results are overall consistent with the hypothesis.

Maternal exposure to CeO2NPs derails placental development through trophoblast dysfunction mediated by excessive autophagy activation

BACKGROUND

The increasing use of cerium dioxide nanoparticles (CeO₂NPs) in biomedical field has attracted substantial attention about their potential risks to human health. Recent studies have shown that nanoparticles can induce placental dysfunction and even fetal abortion, but a more detailed mechanism of nanoparticles affecting placental development remains elusive.

RESULTS

Here, we constructed a mouse exposure model with different doses of CeO₂NPs (2.5, 4, 5, 7.5, and 10 mg kg^-1 day^-1, average particle size 3-5 nm), finding that intravenous exposure to pregnant mice with CeO₂NPs could cause abnormal placental development. Deposited nanoparticles were able to be observed in the placental trophoblast at doses of 5 and 7.5 mg kg^-1 day^-1. Diving into molecular mechanisms indicated that CeO₂NPs exposure could lead to autophagy activation in placental trophoblast. At the cellular level, exposure to CeO₂NPs inhibited the migration and invasion of HTR-8/SVneo and activated the autophagy through mammalian target of rapamycin complex1 (mTORC1) signaling pathway. Furthermore, inhibition of autophagy initiation by 3-Methyladenine (3-MA) partially restored the function of HTR-8/SVneo, while blocking autophagic flow by Chloroquine (CQ) aggravated the functional damage.

CONCLUSIONS

Maternal exposure to CeO₂NPs impairs placental development through trophoblast dysfunction mediated by excessive autophagy activation. These results suggested that autophagy dysfunction may be a potential mechanism for the impairment of trophoblast by CeO₂NPs exposure. As above, our findings provide insights into the toxicity mechanism to the reproductive system induced by rare-earth nanoparticles exposure.

In vivo guiding inorganic nanozymes for biosensing and therapeutic potential in cancer, inflammation and microbial infections

Researchers have recently introduced some artificial enzymes based on nanomaterials that show significant catalytic activity relative to native enzymes called nanozyme. These nanozymes show superior performance than conventional catalysts and are considered as fascinating candidates for introducing the next generation of biomaterials in various industrial and biomedical fields. Recently, nanozymes have received a great deal of attention in biomedical applications due to their potential properties such as long-term stability, low cost, mass production capability, and controllable catalytic activity. Due to the intrinsic catalytic activity of nanoparticles (NPs) as nanozymes and their ability to be regulated in biomedical processes, this review paper focuses on the in vivo applications of nanozymes in biosensing and therapeutic activities. Despite the challenges and benefits of each approach, this paper attempts to provide an appropriate motivation for the classification of different nanozymes followed by their application in biomedical activities including in vivo biosensing and therapeutic potential in cancer, inflammation and microbial infections. Finally, some ongoing challenges and future perspective of nanozymes in biomedical application were surveyed. In conclusion, this paper may provide useful information regarding the development of nanozymes as promising platforms in biomedical settings due to expedited diagnosis, the advancement of multifactorial therapies and their pronounced stability.

Safety assessment of cerium oxide nanoparticles: combined repeated-dose toxicity with reproductive/developmental toxicity screening and biodistribution in rats

Cerium oxide nanoparticles (CeO₂ NPs) are widely used in various commercial applications because of their characteristic properties. People can be easily exposed to CeO₂ NPs in real life, but the safety assessment of CeO₂ NPs has not been fully investigated. Therefore, in this study, we conducted a combined repeated-dose and reproductive/developmental toxicity screening study (OECD testing guideline 422) to investigate the potential hazards on human health, including reproductive/developmental functions, after repeated daily CeO₂ NPs oral gavage administration to both males and females. In addition, tissues from parental animals and their pups were collected to analyze the internal accumulation of cerium. CeO₂ NPs were orally administered to Sprague-Dawley rats at doses of 0, 100, 300 and 1000 mg/kg during their pre-mating, mating, gestation and early lactation periods. In the general systemic and reproductive/developmental examinations, no marked toxicities were observed in any in-life and terminal observation parameters in this study. In the biodistribution analysis, cerium was not detected in either parental or pup tissues (blood, liver, lungs and kidneys). Repeated oral exposure of CeO₂ NPs did not induce marked toxicities affecting general systemic and reproductive/developmental functions up to the dose level of 1000 mg/kg and the CeO₂ NPs were not systemically absorbed in parental animals or their pups. This result could be used in risk assessment for humans, and additional toxicity studies with CeO₂ NPs will be necessary considering various physicochemical properties and exposure probabilities of these nanoparticles.

Repeated-oral dose toxicity of polyethylene microplastics and the possible implications on reproduction and development of the next generation

With the increased distribution of microplastics in the environment, the potential for harmful effects on human health and ecosystems have become a global concern. Considering that polyethylene microplastics (PE-MPs) are among the most produced plastics worldwide, we administered PE-MPs (0.125, 0.5, 2 mg/day/mouse) by gavage to mice (10 mice/sex/dose) for 90 days. Compared to control, the body weight gain was significantly reduced in the male mice, and the proportion of neutrophils in the blood stream clearly increased in both sexes of mice. Persistence of a PE-MPs-like material and migration of granules to the mast cell membrane and accumulation of damaged organelles were observed in the stomachs and the spleens from the treated dams, respectively. Additionally, the IgA level in the blood stream was significantly elevated in the dams administered with PE-MPs compared to control, and the subpopulation of lymphocytes within the spleen was altered. Following, we performed an additional study to screen the effects of PE-MPs on reproduction and development (5 mice/sex/dose). Importantly, number of live births per dam, the sex ratio of pups, and body weight of pups was notably altered in groups treated with PE-MPs compared to the control group. Additionally, PE-MPs affected the subpopulation of lymphocytes within the spleen of the offspring, as did in the dams. Therefore, we propose that reproductive and developmental toxicity testing is warranted to evaluate the safety of microplastics. Additionally, we suggest that the IgA level may be used as a biomarker for harmful effects following exposure on microplastics.

A comparative study of toxicity of TiO2, ZnO, and Ag nanoparticles to human aortic smooth-muscle cells

PURPOSE

To evaluate the adverse vascular effects of nanoparticles (NPs) in vitro, extensive studies have investigated the toxicity of NPs on endothelial cells, but the knowledge of potential toxicity on human smooth-muscle cells (SMCs) is currently limited.

METHODS

This study compared the toxicity of TiO2, ZnO, and Ag NPs to human aortic SMCs.

RESULTS

Only ZnO NPs significantly induced cytotoxicity, accompanied by increased intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress biomarkers (DDIT3 expression and p-Chop proteins). All the NPs significantly promoted the release of soluble VCAM1 and soluble sICAM1, but not IL6, which suggested that metal-based NPs might promote inflammatory responses. Furthermore, KLF4 expression (a transcription factor for SMC-phenotype switch) was significantly induced by TiO2 NPs and modestly by ZnO NPs, but the expression of CD68 remained unaltered.

CONCLUSION

Our data indicated that ZnO NPs were more cytotoxic to human aortic SMCs than TiO2 and Ag NPs at the same mass concentrations, which might have been associated with intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress.

Nanoparticles in Medicine: A Focus on Vascular Oxidative Stress

Nanotechnology has had a significant impact on medicine in recent years, its application being referred to as nanomedicine. Nanoparticles have certain properties with biomedical applications; however, in some situations, they have demonstrated cell toxicity, which has caused concern surrounding their clinical use. In this review, we focus on two aspects: first, we summarize the types of nanoparticles according to their chemical composition and the general characteristics of their use in medicine, and second, we review the applications of nanoparticles in vascular alteration, especially in endothelial dysfunction related to oxidative stress. This condition can lead to a reduction in nitric oxide (NO) bioavailability, consequently affecting vascular tone regulation and endothelial dysfunction, which is the first phase in the development of cardiovascular diseases. Therefore, nanoparticles with antioxidant properties may improve vascular dysfunction associated with hypertension, diabetes mellitus, or atherosclerosis.

Engineered nanomaterials and oxidative stress: current understanding and future challenges

Engineered nanomaterials (ENMs) are being incorporated at an unprecedented rate into consumer and biomedical products. This increased usage will ultimately lead to increased human exposure; therefore, understanding ENM safety is an important concern to the public. Although ENMs may exert toxicity through multiple mechanisms, one common mechanism of toxicity recognized across a range of ENMs with varying physicochemical properties is oxidative stress. Further, it is recognized that several key physicochemical properties of ENMs including size, material composition, surface chemistry, band gap, and level of ionic dissolution for example contribute to ENM driven oxidative stress. While it has been shown that exposure of cells to ENMs at high acute doses produce reactive oxygen species at a toxic level often leading to cytotoxicity, there is little research looking at oxidative stress caused by ENM exposure at more relevant low or non-toxic doses. Although the former can lead to apoptosis, genotoxicity, and inflammation, the latter can potentially be damaging as chronic changes to the intracellular redox state leads to cellular reprogramming, resulting in disease initiation and progression among other systemic damage. This current opinions article will review the physicochemical properties and mechanisms associated with ENM-driven oxidative stress and will discuss the need for research investigating effects on the redox proteome that may lead to cellular dysfunction at low or chronic doses of ENMs.

Toxicity and tissue distribution of cerium oxide nanoparticles in rats by two different routes: single intravenous injection and single oral administration

Toxicity and target organ distribution of cerium oxide nanoparticles (CeNPs) were investigated via single intravenous injection and single oral administration, respectively. Rats were sacrificed at 24 h after treatment with doses of 30 and 300 mg/kg, and cerium concentrations were measured in liver, kidney, spleen, lung, blood, urine and feces. Results revealed cerium levels in blood and tissues were considerably low in oral treated groups and most cerium was detected in feces, meaning CeNPs would not be absorbed in the gastro-intestinal system. Conversely, high concentrations of cerium were detected in all tissues of rats after intravenous injection. Liver and spleen were main target organs. Cerium levels in liver were 594.9 ± 95.3 μg/g tissue in 30 mg/kg treat group and 3741.7 ± 932.7 μg/g tissue in 300 mg/kg treat group. Cerium levels in spleen reached almost levels of liver. Cerium was also detected, that is relatively low compared to oral administration, in feces of rats treated via intravenous injection, that supports biliary excretion of CeNPs. Urine excretion of CeNPs was not detected in oral treatment and intravenous injection. In accordance with level of cerium distribution, toxicities based on hematology, serum biochemistry and histopathology were observed in rats treated by intravenous injection while no significance was revealed in orally treated groups.

Cerium dioxide nanoparticles exacerbate house dust mite induced type II airway inflammation

Background

Nanomaterial inhalation represents a potential hazard for respiratory conditions such as asthma. Cerium dioxide nanoparticles (CeO₂NPs) have the ability to modify disease outcome but have not been investigated for their effect on models of asthma and inflammatory lung disease. The aim of this study was to examine the impact of CeO₂NPs in a house dust mite (HDM) induced murine model of asthma.

Results

Repeated intranasal instillation of CeO₂NPs in the presence of HDM caused the induction of a type II inflammatory response, characterised by increased bronchoalveolar lavage eosinophils, mast cells, total plasma IgE and goblet cell metaplasia. This was accompanied by increases in IL-4, CCL11 and MCPT1 gene expression together with increases in the mucin and inflammatory regulators CLCA1 and SLC26A4. CLCA1 and SLC26A4 were also induced by CeO₂NPs + HDM co-exposure in air liquid interface cultures of human primary bronchial epithelial cells. HDM induced airway hyperresponsiveness and airway remodelling in mice were not altered with CeO₂NPs co-exposure. Repeated HMD instillations followed by a single exposure to CeO₂NPs failed to produce changes in type II inflammatory endpoints but did result in alterations in the neutrophil marker CD177. Treatment of mice with CeO₂NPs in the absence of HDM did not have any significant effects. RNA-SEQ was used to explore early effects 24 h after single treatment exposures. Changes in SAA3 expression paralleled increased neutrophil BAL levels, while no changes in eosinophil or lymphocyte levels were observed. HDM resulted in a strong induction of type I interferon and IRF3 dependent gene expression, which was inhibited with CeO₂NPs co-exposure. Changes in the expression of genes including CCL20, CXCL10, NLRC5, IRF7 and CLEC10A suggest regulation of dendritic cells, macrophage functionality and IRF3 modulation as key early events in how CeO₂NPs may guide pulmonary responses to HDM towards type II inflammation.

Conclusions

CeO₂NPs were observed to modulate the murine pulmonary response to house dust mite allergen exposure towards a type II inflammatory environment. As this type of response is present within asthmatic endotypes this finding may have implications for how occupational or incidental exposure to CeO₂NPs should be considered for those susceptible to disease.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0261-5) contains supplementary material, which is available to authorized users.

Vasomotor function in rat arteries after ex vivo and intragastric exposure to food-grade titanium dioxide and vegetable carbon particles

Background

Humans are continuously exposed to particles in the gastrointestinal tract. Exposure may occur directly through ingestion of particles via food or indirectly by removal of inhaled material from the airways by the mucociliary clearance system. We examined the effects of food-grade particle exposure on vasomotor function and systemic oxidative stress in an ex vivo study and intragastrically exposed rats.

Methods

In an ex vivo study, aorta rings from naïve Sprague-Dawley rats were exposed for 30 min to food-grade TiO₂ (E171), benchmark TiO₂ (Aeroxide P25), food-grade vegetable carbon (E153) or benchmark carbon black (Printex 90). Subsequently, the vasomotor function was assessed in wire myographs. In an in vivo study, lean Zucker rats were exposed intragastrically once a week for 10 weeks to vehicle, E171 or E153. Doses were comparable to human daily intake. Vasomotor function in the coronary arteries and aorta was assessed using wire myographs. Tetrahydrobiopterin, ascorbate, malondialdehyde and asymmetric dimethylarginine were measured in blood as markers of oxidative stress and vascular function.

Results

Direct exposure of E171 to aorta rings ex vivo increased the acetylcholine-induced vasorelaxation and 5-hydroxytryptamine-induced vasocontraction. E153 only increased acetylcholine-induced vasorelaxation, and Printex 90 increased the 5-hydroxytryptamine-induced vasocontraction, whereas Aeroxide P25 did not affect the vasomotor function. In vivo exposure showed similar results as ex vivo exposure; increased acetylcholine-induced vasorelaxation in coronary artery segments of E153 and E171 exposed rats, whereas E171 exposure altered 5-hydroxytryptamine-induced vasocontraction in distal coronary artery segments. Plasma levels of markers of oxidative stress and vascular function showed no differences between groups.

Conclusion

Gastrointestinal tract exposure to E171 and E153 was associated with modest albeit statistically significant alterations in the vasocontraction and vasorelaxation responses. Direct particle exposure to aorta rings elicited a similar type of response. The vasomotor responses were not related to biomarkers of systemic oxidative stress.

Cerium oxide nanoparticles in neuroprotection and considerations for efficacy and safety

Cerium oxide nanoparticles have widespread use in the materials industry, and have recently come into consideration for biomedical use due to their potent regenerative antioxidant properties. Given that the brain is one of the most highly oxidative organs in the body, it is subject to some of the greatest levels of oxidative stress, particularly in neurodegenerative disease. Therefore, cerium oxide nanoparticles are currently being investigated for efficacy in several neurodegenerative disorders and have shown promising levels of neuroprotection. This review discusses the basis for cerium oxide nanoparticle use in neurodegenerative disease and its hypothesized mechanism of action. The review focuses on an up-to-date summary of in vivo work with cerium oxide nanoparticles in animal models of neurodegenerative disease. Additionally, we examine the current state of information regarding biodistribution, toxicity, and safety for cerium oxide nanoparticles at the in vivo level. Finally, we discuss future directions that are necessary if this nanopharmaceutical is to move up from the bench to the bedside. WIREs Nanomed Nanobiotechnol 2017, 9:e1444. doi: 10.1002/wnan.1444 For further resources related to this article, please visit the WIREs website.

The acute pulmonary and thrombotic effects of cerium oxide nanoparticles after intratracheal instillation in mice

Cerium oxide nanoparticles (CeO₂ NPs), used as a diesel fuel catalyst, can be emitted into the ambient air, resulting in exposure to humans by inhalation. Recent studies have reported the development of lung toxicity after pulmonary exposure to CeO₂ NPs. However, little is known about the possible thrombotic effects of these NPs. The present study investigated the acute (24 hours) effect of intratracheal (IT) instillation of either CeO₂ NPs (0.1 or 0.5 mg/kg) or saline (control) on pulmonary and systemic inflammation and oxidative stress and thrombosis in mice. CeO₂ NPs induced a significant increase of neutrophils into the bronchoalveolar lavage (BAL) fluid with an elevation of tumor necrosis factor α (TNFα) and a decrease in the activity of the antioxidant catalase. Lung sections of mice exposed to CeO₂ NPs showed a dose-dependent infiltration of inflammatory cells consisting of macrophages and neutrophils. Similarly, the plasma levels of C-reactive protein and TNFα were significantly increased, whereas the activities of catalase and total antioxidant were significantly decreased. Interestingly, CeO₂ NPs significantly and dose dependently induced a shortening of the thrombotic occlusion time in pial arterioles and venules. Moreover, the plasma concentrations of fibrinogen and plasminogen activator inhibitor-1 were significantly elevated by CeO₂ NPs. The direct addition of CeO₂ NPs (1, 5, or 25 μg/mL) to mouse whole blood, collected from the inferior vena cava, in vitro neither caused significant platelet aggregation nor affected prothrombin time or partial thromboplastin time, suggesting that the thrombotic events observed in vivo may have resulted from systemic inflammation and/or oxidative stress induced by CeO₂ NPs. This study concludes that acute pulmonary exposure to CeO₂ NPs induces pulmonary and systemic inflammation and oxidative stress and promotes thrombosis in vivo.

Metal Nanomaterial Toxicity Variations Within the Vascular System

Engineered nanomaterials (ENM) are anthropogenic materials with at least one dimension less than 100 nm. Their ubiquitous employment in biomedical and industrial applications in the absence of full toxicological assessments raises significant concerns over their safety on human health. This is a significant concern, especially for metal and metal oxide ENM as they may possess the greatest potential to impair human health. A large body of literature has developed that reflects adverse systemic effects associated with exposure to these materials, but an integrated mechanistic framework for how ENM exposure influences morbidity remains elusive. This may be due in large part to the tremendous diversity of existing ENM and the rate at which novel ENM are produced. In this review, the influence of specific ENM physicochemical characteristics and hemodynamic factors on cardiovascular toxicity is discussed. Additionally, the toxicity of metallic and metal oxide ENM is presented in the context of the cardiovascular system and its discrete anatomical and functional components. Finally, future directions and understudied topics are presented. While it is clear that the nanotechnology boom has increased our interest in ENM toxicity, it is also evident that the field of cardiovascular nanotoxicology remains in its infancy and continued, expansive research is necessary in order to determine the mechanisms via which ENM exposure contributes to cardiovascular morbidity.

Cerium Dioxide Nanoparticle Exposure Improves Microvascular Dysfunction and Reduces Oxidative Stress in Spontaneously Hypertensive Rats

The elevated production of reactive oxygen species (ROS) in the vascular wall is associated with cardiovascular diseases such as hypertension. This increase in oxidative stress contributes to various mechanisms of vascular dysfunction, such as decreased nitric oxide bioavailability. Therefore, anti-oxidants are being researched to decrease the high levels of ROS, which could improve the microvascular dysfunction associated with various cardiovascular diseases. From a therapeutic perspective, cerium dioxide nanoparticles (CeO₂ NP) hold great anti-oxidant potential, but their in vivo activity is unclear. Due to this potential anti-oxidant action, we hypothesize that injected CeO₂ NP would decrease microvascular dysfunction and oxidative stress associated with hypertension. In order to simulate a therapeutic application, spontaneously hypertensive (SH) and Wistar-Kyoto (WKY) rats were intravenously injected with either saline or CeO₂ NP (100 μg suspended in saline). Twenty-four hours post-exposure mesenteric arteriolar reactivity was assessed via intravital microscopy. Endothelium-dependent and –independent function was assessed via acetylcholine and sodium nitroprusside. Microvascular oxidative stress was analyzed using fluorescent staining in isolated mesenteric arterioles. Finally, systemic inflammation was examined using a multiplex analysis and venular leukocyte flux was counted. Endothelium-dependent dilation was significantly decreased in the SH rats (29.68 ± 3.28%, maximal response) and this microvascular dysfunction was significantly improved following CeO₂ NP exposure (43.76 ± 4.33%, maximal response). There was also an increase in oxidative stress in the SH rats, which was abolished following CeO₂ NP treatment. These results provided evidence that CeO₂ NP act as an anti-oxidant in vivo. There were also changes in the inflammatory profile in the WKY and SH rats. In WKY rats, IL-10 and TNF-α were increased following CeO₂ NP treatment. Finally, leukocyte flux was increased in the SH rats (34 ± 4 vs. 17 ± 3 cells/min in the normotensive controls), but this activation was decreased following exposure (15 ± 2 vs. 34 ± 4 cells/min). These results indicated that CeO₂ NP may alter the inflammatory response in both SH and WKY rats. Taken together, these results provide evidence that CeO₂ NP act as an anti-oxidant in vivo and may improve microvascular reactivity in a model of hypertension.

Cardiac and mitochondrial dysfunction following acute pulmonary exposure to mountaintop removal mining particulate matter

Throughout the United States, air pollution correlates with adverse health outcomes, and cardiovascular disease incidence is commonly increased following environmental exposure. In areas surrounding active mountaintop removal mines (MTM), a further increase in cardiovascular morbidity is observed and may be attributed in part to particulate matter (PM) released from the mine. The mitochondrion has been shown to be central in the etiology of many cardiovascular diseases, yet its roles in PM-related cardiovascular effects are not realized. In this study, we sought to elucidate the cardiac processes that are disrupted following exposure to mountaintop removal mining particulate matter (PM MTM). To address this question, we exposed male Sprague-Dawley rats to PM MTM, collected within one mile of an active MTM site, using intratracheal instillation. Twenty-four hours following exposure, we evaluated cardiac function, apoptotic indices, and mitochondrial function. PM MTM exposure elicited a significant decrease in ejection fraction and fractional shortening compared with controls. Investigation into the cellular impacts of PM MTM exposure identified a significant increase in mitochondrial-induced apoptotic signaling, as reflected by an increase in TUNEL-positive nuclei and increased caspase-3 and -9 activities. Finally, a significant increase in mitochondrial transition pore opening leading to decreased mitochondrial function was identified following exposure. In conclusion, our data suggest that pulmonary exposure to PM MTM increases cardiac mitochondrial-associated apoptotic signaling and decreases mitochondrial function concomitant with decreased cardiac function. These results suggest that increased cardiovascular disease incidence in populations surrounding MTM mines may be associated with increased cardiac cell apoptotic signaling and decreased mitochondrial function.

Uterine microvascular sensitivity to nanomaterial inhalation: An in vivo assessment

With the tremendous number and diverse applications of engineered nanomaterials incorporated in daily human activity, exposure can no longer be solely confined to occupational exposures of healthy male models. Cardiovascular and endothelial cell dysfunction have been established using in vitro and in situ preparations, but the translation to intact in vivo models is limited. Intravital microscopy has been used extensively to understand microvascular physiology while maintaining in vivo neurogenic, humoral, and myogenic control. However, a tissue specific model to assess the influences of nanomaterial exposure on female reproductive health has not been fully elucidated. Female Sprague Dawley (SD) rats were exposed to nano-TiO2 aerosols (171 ± 6 nm, 10.1 ± 0.39 mg/m(3), 5h) 24-hours prior to experimentation, leading to a calculated deposition of 42.0 ± 1.65 μg. After verifying estrus status, vital signs were monitored and the right horn of the uterus was exteriorized, gently secured over an optical pedestal, and enclosed in a warmed tissue bath using intravital microscopy techniques. After equilibration, significantly higher leukocyte-endothelium interactions were recorded in the exposed group. Arteriolar responsiveness was assessed using ionophoretically applied agents: muscarinic agonist acetylcholine (0.025 M; ACh; 20, 40, 100, and 200 nA), and nitric oxide donor sodium nitroprusside (0.05 M; SNP; 20, 40, and 100 nA), or adrenergic agonist phenylephrine (0.05 M; PE; 20, 40, and 100 nA) using glass micropipettes. Passive diameter was established by tissue superfusion with 10(-4)M adenosine. Similar to male counterparts, female SD rats present systemic microvascular dysfunction; however the ramifications associated with female health and reproduction have yet to be elucidated.