Combinatory Effects of Cerium Dioxide Nanoparticles and Acetaminophen on the Liver-A Case Study of Low-Dose Interactions in Human HuH-7 Cells.

The interactions between pharmaceuticals and nanomaterials and its potentially resulting toxicological effects in living systems are only insufficiently investigated. In this study, two model compounds, acetaminophen, a pharmaceutical, and cerium dioxide, a manufactured nanomaterial, were investigated in combination and individually. Upon inhalation, cerium dioxide nanomaterials were shown to systemically translocate into other organs, such as the liver. Therefore we picked the human liver cell line HuH-7 cells as an in vitro system to investigate liver toxicity. Possible synergistic or antagonistic metabolic changes after co-exposure scenarios were investigated. Toxicological data of the water soluble tetrazolium (WST-1) assay for cell proliferation and genotoxicity assessment using the Comet assay were combined with an untargeted as well as a targeted lipidomics approach. We found an attenuated cytotoxicity and an altered metabolic profile in co-exposure experiments with cerium dioxide, indicating an interaction of both compounds at these endpoints. Single exposure against cerium dioxide showed a genotoxic effect in the Comet assay. Conversely, acetaminophen exhibited no genotoxic effect. Comet assay data do not indicate an enhancement of genotoxicity after co-exposure. The results obtained in this study highlight the advantage of investigating co-exposure scenarios, especially for bioactive substances.

Metal Homeostasis and Gas Exchange Dynamics in Pisum sativum L. Exposed to Cerium Oxide Nanoparticles.

Cerium dioxide nanoparticles are pollutants of emerging concern. They are rarely immobilized in the environment. This study extends our work on Pisum sativum L. as a model plant, cultivated worldwide, and is well suited for investigating additive interactions induced by nanoceria. Hydroponic cultivation, which prompts accurate plant growth control and three levels of CeO2 supplementation, were applied, namely, 100, 200, and 500 mg (Ce)/L. Phytotoxicity was estimated by fresh weights and photosynthesis parameters. Additionally, Ce, Cu, Zn, Mn, Fe, Ca, and Mg contents were analyzed by high-resolution continuum source atomic absorption and inductively coupled plasma optical emission techniques. Analysis of variance has proved that CeO2 nanoparticles affected metals uptake. In the roots, it decreased for Cu, Zn, Mn, Fe, and Mg, while a reversed process was observed for Ca. The latter is absorbed more intensively, but translocation to above-ground parts is hampered. At the same time, nanoparticulate CeO2 reduced Cu, Zn, Mn, Fe, and Ca accumulation in pea shoots. The lowest Ce concentration boosted the photosynthesis rate, while the remaining treatments did not induce significant changes. Plant growth stimulation was observed only for the 100 mg/L. To our knowledge, this is the first study that demonstrates the effect of nanoceria on photosynthesis-related parameters in peas.

Cerium oxide and barium sulfate nanoparticle inhalation affects gene expression in alveolar epithelial cells type II.

BACKGROUND: Understanding the molecular mechanisms of nanomaterial interacting with cellular systems is important for appropriate risk assessment. The identification of early biomarkers for potential (sub-)chronic effects of nanoparticles provides a promising approach towards cost-intensive and animal consuming long-term studies. As part of a 90-day inhalation toxicity study with CeO2 NM-212 and BaSO4 NM-220 the present investigations on gene expression and immunohistochemistry should reveal details on underlying mechanisms of pulmonary effects. The role of alveolar epithelial cells type II (AEII cells) is focused since its contribution to defense against inhaled particles and potentially resulting adverse effects is assumed. Low dose levels should help to specify particle-related events, including inflammation and oxidative stress. RESULTS: Rats were exposed to clean air, 0.1, 0.3, 1.0, and 3.0 mg/m3 CeO2 NM-212 or 50.0 mg/m3 BaSO4 NM-220 and the expression of 391 genes was analyzed in AEII cells after one, 28 and 90 days exposure. A total number of 34 genes was regulated, most of them related to inflammatory mediators. Marked changes in gene expression were measured for Ccl2, Ccl7, Ccl17, Ccl22, Ccl3, Ccl4, Il-1α, Il-1ß, and Il-1rn (inflammation), Lpo and Noxo1 (oxidative stress), and Mmp12 (inflammation/lung cancer). Genes related to genotoxicity and apoptosis did not display marked regulation. Although gene expression was less affected by BaSO4 compared to CeO2 the gene pattern showed great overlap. Gene expression was further analyzed in liver and kidney tissue showing inflammatory responses in both organs and marked downregulation of oxidative stress related genes in the kidney. Increases in the amount of Ce were measured in liver but not in kidney tissue. Investigation of selected genes on protein level revealed increased Ccl2 in bronchoalveolar lavage of exposed animals and increased Lpo and Mmp12 in the alveolar epithelia. CONCLUSION: AEII cells contribute to CeO2 nanoparticle caused inflammatory and oxidative stress reactions in the respiratory tract by the release of related mediators. Effects of BaSO4 exposure are low. However, overlap between both substances were detected and support identification of potential early biomarkers for nanoparticle effects on the respiratory system. Signs for long-term effects need to be further evaluated by comparison to a respective exposure setting.

Synergistic role of nanoceria on the ability of tobacco smoke to induce carcinogenic hallmarks in lung epithelial cells.

AIM: Since controversial results have been obtained in studies dealing with nanoceria usefulness in biomedical applications, the transforming effects of long-term exposure to nanoceria in lung epithelial cells, alone or together with cigarette smoke condensate (CSC), were evaluated. MATERIALS & METHODS: In vitro cell transformation techniques were used to study several hallmarks of carcinogenesis. Morphology, cell proliferation, gene expression, cell migration, anchorage-independent cell growth and cell secretome were analyzed. RESULTS & CONCLUSION: Data evidence no transforming ability of nanoceria, but support a synergistic role on CSC's transforming ability. A more noticeable spindle-like phenotype, increased proliferation rate, higher degree of differentiation status dysregulation, higher migration capacity, increased anchorage-independent cell growth and higher levels of MMP-9 and cell growth promoting capability, were observed. In addition, nanoceria co-exposure exacerbates the expression of FRA-1.

Redox-active cerium oxide nanoparticles protect human dermal fibroblasts from PQ-induced damage.

Recently, it has been published that cerium (Ce) oxide nanoparticles (CNP; nanoceria) are able to downregulate tumor invasion in cancer cell lines. Redox-active CNP exhibit both selective pro-oxidative and antioxidative properties, the first being responsible for impairment of tumor growth and invasion. A non-toxic and even protective effect of CNP in human dermal fibroblasts (HDF) has already been observed. However, the effect on important parameters such as cell death, proliferation and redox state of the cells needs further clarification. Here, we present that nanoceria prevent HDF from reactive oxygen species (ROS)-induced cell death and stimulate proliferation due to the antioxidative property of these particles.

Cerium oxide nanoparticles induced toxicity in human lung cells: role of ROS mediated DNA damage and apoptosis.

Cerium oxide nanoparticles (CeO2 NPs) have promising industrial and biomedical applications. In spite of their applications, the toxicity of these NPs in biological/physiological environment is a major concern. Present study aimed to understand the molecular mechanism underlying the toxicity of CeO2 NPs on lung adenocarcinoma (A549) cells. After internalization, CeO2 NPs caused significant cytotoxicity and morphological changes in A549 cells. Further, the cell death was found to be apoptotic as shown by loss in mitochondrial membrane potential and increase in annexin-V positive cells and confirmed by immunoblot analysis of BAX, BCl-2, Cyt C, AIF, caspase-3, and caspase-9. A significant increase in oxidative DNA damage was found which was confirmed by phosphorylation of p53 gene and presence of cleaved poly ADP ribose polymerase (PARP). This damage could be attributed to increased production of reactive oxygen species (ROS) with concomitant decrease in antioxidant "glutathione (GSH)" level. DNA damage and cell death were attenuated by the application of ROS and apoptosis inhibitors N-acetyl-L-cysteine (NAC) and Z-DEVD-fmk, respectively. Our study concludes that ROS mediated DNA damage and cell cycle arrest play a major role in CeO2 NPs induced apoptotic cell death in A549 cells. Apart from beneficial applications, these NPs also impart potential harmful effects which should be properly evaluated prior to their use.

[Cerium-induced granulomatous dermatitis]. / Granulomatose cutanée au cérium.

BACKGROUND: The presence of inorganic foreign bodies in granulomatous cutaneous lesions is not infrequent. In this paper, we describe the first case of cerium-induced cutaneous granulomatous dermatitis. CASE REPORT: A 57-year-old woman seriously burned four years ago presented with papulonodular lesions affecting only the burned areas treated with topical cerium nitrate-silver sulfadiazine cream (Flammacérium). Biopsies revealed sarcoidal granuloma associated with exogenous particles. Electron probe X-ray microanalysis demonstrated a high cerium content. Screening for systemic sarcoidosis was negative. The patient was treated with hydroxychloroquine. After four months of follow-up, clinical and histological evidence of decreased infiltrate was noted. DISCUSSION: Cerium nitrate-silver sulfadiazine cream (Flammacérium) is widely used for the topical treatment of burns. The main effect of cerium is to create superficial calcification, which decreases wound colonization and prevents the formation of granulation tissue (no hypertrophic scar formation) in burns. Prior to our case, no cutaneous side-effects of cerium had been encountered. Inoculation of foreign matter may or may not induce granuloma formation or sarcoidosis in different subjects, according to their immunologic status. The favorable outcome in this case could in fact be due to a change in the pattern of cytokinin production (TH1=> TH2) rather than the effects of hydroxychloroquine therapy.

Rare earth (cerium oxide) pneumoconiosis: analytical scanning electron microscopy and literature review.

Rare earth pneumoconiosis is an uncommonly reported disease caused by the inhalation of dust containing lanthanides, also known as rare earth metals, which are common industrial materials. The pathologic manifestations and natural history of this disorder are incompletely understood. We describe a male patient with a 35-year history of optical lens grinding, an occupation associated with exposure to cerium oxide, a rare earth metal-containing compound. The patient presented with progressive dyspnea and an interstitial pattern on chest X-ray; open lung biopsy showed interstitial fibrosis histologically indistinguishable from usual interstitial pneumonitis. However, scanning electron microscopy with energy-dispersive X-ray analysis demonstrated numerous particulate deposits in the lung, of which the majority contained the rare earth metal cerium alone or in combination with other elements. Our case is one of the first to describe rare earth pneumoconiosis associated with pulmonary fibrosis in the occupational setting of optical lens manufacture. Besides reinforcing the contention that rare earth metals are potentially harmful, our case suggests that such agents may be causally related to the development of pulmonary fibrosis.

[Pneumoconiosis caused by "rare earths" (cer-pneumoconiosis)]. / Pneumokoniose durch "Seltene Erden" (Cer-Pneumokoniose).

Slowly progressive restriction in respiratory function was observed in five reproduction photographers who had been exposed to fumes of carbon arc lamps for more than a decade. In all cases interstitial lung fibrosis had developed and accumulations of fine granular dust particles were found in the tissue. Combined analyses including X-ray diffraction, infrared spectroscopy, plasma analysis, X-ray microanalysis and electron diffraction revealed the presence of rare earth minerals (mainly cerium compounds) in all lungs. The rare earth minerals originating from the core of the burned carbon rods used in the arc lamps represent the etiological factors responsible for the development of so-called "cerium pneumoconiosis".

Topical chemotherapy for burns using cerium salts and silver sulfadiazine.

These experimental data indicate that cerium compounds exert a measurable antimicrobial action in vitro. In vivo the simultaneous use of cerium sulfadiazine and silver sulfadiazine was more effective than silver sulfadiazine alone or the combination of cerous nitrate and silver sulfadiazine. When cerous nitrate was used clically, gram-positive bacteria predominated. In contrast, wounds exposed to silver salts alone harbor a predominately gram-negative flora. The combination of cerous nitrate and silver sulfadiazine appears to provide a broad spectrum inhibitory to both types of organisms. It is apparent that a sampling problem exists in any attempt to monitor wounds that may exceed a square meter in extent. These bacteriologic data pertain only to the surface flora. The need to culture tissue samples of burn wounds has been emphasized. Our experience, however, is that invasion of deep tissue without dense surface colonization, greater than 10(5), is infrequent. Furthermore, fragments of eschar were submitted regularly for culture; those results confirmed the surface culture findins. The characteristic yellow-green color of cerium nitrate treated eschars may results from oxidation of trivalent cerium to yellow ceric ions. Free silver and sulfadiazine ions are available also in small amounts because of limited ionization of the highly insoluble silver sulfadiazine. This might promote the in vivo formation of cerous sulfadiazine and would provide a continuous source of ionic cerium for microbial inhibition. The modification of silver sulfadiazine cream by incorporating cerous nitrate into it strikingly enhances its topical antiseptic effect in burn wounds without increasing toxicity.

Cerium nitrate: a new topical antiseptic for extensive burns.

The wounds of 60 burned patients were treated topically with cerium nitrate, which was applied either as a cream or in aqueous solution. Cerium nitrate has a potent antiseptic effect in human burn wounds, especially against gram negative bacteria and fungi. Pseudomonas aeruginosa was recovered from the wounds infrequently and never predominated. Fungi were practically never found. No patient treated with cerium developed a necrotizing wound infection. Analysis of the detailed bacteriological data indicated that, in contrast to previous results with use of the nitrate or sulfadiazine salts of silver, when gram negative species predominated, the flora tended to be predominantly gram positive when cerium was used. Therefore, some patients were treated simultaneously with cerium nitrate and silver sulfadiazine; this resulted in an even more efficient suppression of the wound flora than was observed previously with either cerium alone or silver salts alone; results with the simultaneous topical therapy in patients with injuries that previously were uniformly lethal were excellent. No toxicity attributable to the use of cerium was observed, although one instance of methemoglobinemia due to nitrate was documented. The adsorption of topically applied cerium essentially is nil. The use of cerium nitrate was associated with a nearly 50 percent reduction in the anticipated death rate. Cerium nitrate is a promising new topical antiseptic agent for the treatment of burns, particularly when it is used in combination with silver sulfadiazine.