Exposure to Cerium Oxide Nanoparticles Is Associated With Activation of Mitogen-activated Protein Kinases Signaling and Apoptosis in Rat Lungs

Toxic Effects of Rare Earth Elements on Human Health: A Review

Rare earth elements (REEs) are a new type of material resource which have attracted significant attention in recent years. REEs have emerged as essential metals in modern-day technology due to their unique functions. The long-term, large-scale mining and utilization of rare earths has caused serious environmental pollution and constitutes a global health issue, which has raised concerns regarding the safety of human health. However, the toxicity profile of suspended particulate matter in REEs in the environment, which interacts with the human body, remains largely unknown. Studies have shown that REEs can enter the human body through a variety of pathways, leading to a variety of organ and system dysfunctions through changes in genetics, epigenetics, and signaling pathways. Through an extensive literature search and critical analysis, we provide a comprehensive overview of the available evidence, identify knowledge gaps, and make recommendations for future research directions.

Blood multiple heavy metals exposure and lung function in young adults: A prospective Cohort study in China

The content of single heavy metal in blood is associated with lung function decline, but there is little evidence on the joint effect of multiple heavy metals on lung function. To explore whether heavy metal mixture exposure is associated with lung function reduction among young adults. The study based on a cohort of 518 students recruited from a college in Shandong, China. We measured their lung function and blood heavy metal concentrations. The BKMR model was used to analyse the association between blood heavy metals mixture levels and lung function, and to identify the critical single heavy metal which contributes most to joint effects. As the sensitivity analysis, we used quantile g-computation model and GLM to explore the joint effect and independent effects of heavy metals. Our findings revealed a significant reduction of FVC and FEV1 levels after exposure to heavy metals mixture. An IQR increase in Cu was associated with a 0.079 L and 0.083 L decrease in FEV1 and FVC, respectively. And an IQR increase in Fe was associated with 0.036 L higher FEV1 and 0.033 L higher FVC. For adults, reducing blood heavy metals concentration might be an effective intervention to protect lung function.

Influence of Ce3+ Substitution on Antimicrobial and Antibiofilm Properties of ZnCexFe2-xO4 Nanoparticles (X = 0.0, 0.02, 0.04, 0.06, and 0.08) Conjugated with Ebselen and Its Role Subsidised with γ-Radiation in Mitigating Human TNBC and Colorectal Adenocarcinoma Proliferation In Vitro

Cancers are a major challenge to health worldwide. Spinel ferrites have attracted attention due to their broad theranostic applications. This study aimed at investigating the antimicrobial, antibiofilm, and anticancer activities of ebselen (Eb) and cerium-nanoparticles (Ce-NPs) in the form of ZnCexFe2-XO4 on human breast and colon cancer cell lines. Bioassays of the cytotoxic concentrations of Eb and ZnCexFe2-XO4, oxidative stress and inflammatory milieu, autophagy, apoptosis, related signalling effectors, the distribution of cells through the cell-cycle phases, and the percentage of cells with apoptosis were evaluated in cancer cell lines. Additionally, the antimicrobial and antibiofilm potential have been investigated against different pathogenic microbes. The ZOI, and MIC results indicated that ZnCexFe2-XO4; X = 0.06 specimen reduced the activity of a wide range of bacteria and unicellular fungi at low concentration including P. aeruginosa (9.5 mm; 6.250 µg/mL), S. aureus (13.2 mm; 0.390 µg/mL), and Candida albicans (13.5 mm; 0.195 µg/mL). Reaction mechanism determination indicated that after ZnCexFe2-xO4; X = 0.06 treatment, morphological differences in S.aureus were apparent with complete lysis of bacterial cells, a concomitant decrease in the viable number, and the growth of biofilm was inhibited. The combination of Eb with ZFO or ZnCexFe2-XO4 with γ-radiation exposure showed marked anti-proliferative efficacy in both cell lines, through modulating the oxidant/antioxidant machinery imbalance, restoring the fine-tuning of redox status, and promoting an anti-inflammatory milieu to prevent cancer progression, which may be a valuable therapeutic approach to cancer therapy and as a promising antimicrobial agent to reduce the pathogenic potential of the invading microbes.

Biocompatible dextran-coated gadolinium-doped cerium oxide nanoparticles as MRI contrast agents with high T1 relaxivity and selective cytotoxicity to cancer cells

Gd-based complexes are widely used as magnetic resonance imaging (MRI) contrast agents. The safety of previously approved contrast agents is questionable and is being re-assessed. The main causes of concern are possible gadolinium deposition in the brain and the development of systemic nephrogenic fibrosis after repeated use of MRI contrasts. Thus, there is an urgent need to develop a new generation of MRI contrasts that are safe and that have high selectivity in tissue accumulation with improved local contrast. Here, we report on a new type of theranostic MRI contrast, namely dextran stabilised, gadolinium doped cerium dioxide nanoparticles. These ultra-small (4-6 nm) Ce_0.9Gd_0.1O_1.95 nanoparticles have been shown to possess excellent colloidal stability and high r₁-relaxivity (3.6 mM^-1 s^-1). They are effectively internalised by human normal and cancer cells and demonstrate dose-dependent selective cytotoxicity to cancer cells.

Effects of radiation and role of plants in radioprotection: A critical review

Radiation can be lethal at high doses, whereas controlled doses are useful in medical applications. Other applications include power generation, agriculture sterilization, nuclear weapons, and archeology. Radiation damages genetic material, which is reflected in genotoxicity and can cause hereditary damage. In the medical field, it is essential to avoid the harmful effects of radiation. Radiation countermeasures and the need for radioprotective agents have been explored in recent years. Considering plants that evolve in radiative conditions, their ability to protect organisms against radiation has been studied and demonstrated. Crude extracts, fractioned extracts, isolated phytocompounds, and plant polysaccharides from various plants have been used in radioprotection studies, and their efficiency has been proven in various in vitro and in vivo experimental models. It is important to identify the mechanism of action to develop a potent plant-based radioprotective agent. To identify this protective mechanism, it is necessary to understand the damage caused by radiation in biological systems. This review intends to discuss the effects of ionizing radiation on biological systems and evaluate plant-based radioprotectants that have tested thus far as well as their mechanism of action in protecting against the toxic effects of radiation. From the review, the mechanism of radioprotection exhibited by the plant-based products could be understood. Meanwhile, we strongly suggest that the potential products identified so far should undergo clinical trials for critically evaluating their effects and for developing an ideal and compatible radioprotectant with no side-effects.

Effects of contaminated surface water and groundwater from a rare earth mining area on the biology and the physiology of Sprague-Dawley rats

Previous studies have shown that an effective damage detection method for model rats from macro individual to micro cellular, was applied to assess the groundwater quality from rare earth metals tailings seepage. To determine whether it is universal method for measuring the toxicological damage caused by contaminated water around other mining areas to organisms at the organ-tissue-cell-chromosome-gene level. In this study, a rare earth mining area in North China was used as research base. Firstly, the core pollution factors in surface water and groundwater from five different sites were analyzed. Then, the degree of toxicological damage to Sprague-Dawley (SD) rats caused by contaminated water were systematically assessed using biological methods. Finally, the possible molecular mechanism of toxicological damage was further discussed. The synthesis results showed that the main pollution factors were some metal elements (Mn, Zn, Co, Ni) and rare earth elements (Sc, Nb, La, Ce, Pr, Dy and Y), which might cause significant DNA genetic damage to SD rats. Further, differential gene expression profile showed that DNA damage-inducible genes (Gadd45g and Ddit4), immunity-related genes (Mpo, Slpi and Elane) and two cancer-related genes (Mmp8 and Ltf) were used as a new prognostic and predictive biomarker for biosafety assessment. Therefore, this study provides a possible molecular mechanism for the toxicological damage, and also it provides a universal method to scientifically and effectively evaluate the water pollution risk for other mining areas.

Combined Toxicity of Metal Nanoparticles: Comparison of Individual and Mixture Particles Effect

Toxicity of metal nanoparticles (NPs) are closely associated with increasing intracellular reactive oxygen species (ROS) and the levels of pro-inflammatory mediators. However, NP interactions and surface complexation reactions alter the original toxicity of individual NPs. To date, toxicity studies on NPs have mostly been focused on individual NPs instead of the combination of several species. It is expected that the amount of industrial and highway-acquired NPs released into the environment will further increase in the near future. This raises the possibility that various types of NPs could be found in the same medium, thereby, the adverse effects of each NP either could be potentiated, inhibited or remain unaffected by the presence of the other NPs. After uptake of NPs into the human body from various routes, protein kinases pathways mediate their toxicities. In this context, family of mitogen-activated protein kinases (MAPKs) is mostly efficient. Despite each NP activates almost the same metabolic pathways, the toxicity induced by a single type of NP is different than the case of co-exposure to the combined NPs. The scantiness of toxicological data on NPs combinations displays difficulties to determine, if there is any risk associated with exposure to combined nanomaterials. Currently, in addition to mathematical analysis (Response surface methodology; RSM), the quantitative-structure-activity relationship (QSAR) is used to estimate the toxicity of various metal oxide NPs based on their physicochemical properties and levels applied. In this chapter, it is discussed whether the coexistence of multiple metal NPs alter the original toxicity of individual NP. Additionally, in the part of "Toxicity of diesel emission/exhaust particles (DEP)", the known individual toxicity of metal NPs within the DEP is compared with the data regarding toxicity of total DEP mixture.

Hepatotoxic Effect of Oral Zinc Oxide Nanoparticles and the Ameliorating Role of Selenium in Rats: A histological, immunohistochemical and molecular study

Despite the emerging concerns about the hepatotoxic risks associated with Zinc oxide nanoparticles (ZnO NPs), yet, the morphological and molecular alterations associated with these extensively-used nanoparticles remain to be elucidated. Thus, the current study has been designed to analyze the effect of ZnO NPs on the hepatic histopathological and immunohistochemical changes, along with the modulation of the oxidative-stress induced JNK/p38MAPK and the STAT-3 signalling. The study also explored the potential protective role of selenium against those alterations. ZnO NPs disrupted the hepatic architecture, elevated the serum liver enzyme alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) levels and caused dose-dependent decrease in the activity of the antioxidant enzymes glutathione-peroxidase, superoxide dismutase and catalase along with an increase in the lipid peroxidation product malondialdehyde. ZnO NPs also increased the area of immune-reactivity of the apoptotic protein bax and decreased the area of immune-reactivity of the anti-apoptotic protein bcl2 together with augmentation of the hepatic caspase 3 gene expression. The role of selenium in ameliorating the hepatotoxicity, oxidative stress injury, and apoptosis induced by ZnO-NPs, along with its role in modulating the JNK/p38MAPK and the STAT-3 signalling and improving the histopathological hepatic changes, offers selenium as a promising adjunctive therapy in individuals subjected to high concentrations of ZnO NPs especially in cases of extensive occupational, medicinal and industrial exposure.

Cerium oxide nanoparticles and their importance in cell signaling pathways for predicting cellular behavior

Cerium oxide nanoparticles (CeO₂-NPs) have prolifically attracted immense interest of researchers due to their prominent anti-oxidant nature. However, these characteristics are accompanied by some ambiguities in other studies reporting their oxidant and toxic properties. In this regard previous literature has pointed to the importance of the NPs morphology and environmental conditions as well as biomolecules that induce a different response by initiating a cascade of activities. Therefore, due to the fact that signaling proteins are key mediators in cellular responses, the cognizance of the CeO₂-NP-targeted signaling pathways could facilitate predicting the cellular behavior and thus more efficient applications of these NPs for clinical purposes. Consequently, a comprehensive review is necessary in this field, to clarify the impacts of CeO₂-NPs on various signaling pathways.

Protection effect of cerium oxide nanoparticles against radiation-induced acute lung injuries in rats

INTRODUCTION

Radiation therapy is one of the most common tools for treating cancer. The aim is to deliver adequate doses of radiation to kill cancer cells and the most challenging part during this procedure is to protect normal cells from radiation. One strategy is to use a radioprotector to spare normal tissues from ionizing radiation effects. Researchers have pursued cerium oxide nanoparticles as a therapeutic agent, due to its diverse characteristics, which include antioxidant properties, making it a potential radioprotector.

MATERIALS AND METHODS

One hundred rats were divided into five groups of A) control group, intraperitoneal (IP) saline injection was done twice a week; B) bi-weekly IP injection of 14.5 nM (0.00001 mg/kg) CNP for two weeks; C) a single whole thorax radiation dose of 18 Gy; D) a single whole thorax radiation dose of 18 Gy + bi-weekly injection of 14.5 nM CNP for two weeks after radiation; E) bi-weekly IP injection of 14.5 nM CNP for two weeks prior to radiation + a single whole thorax radiation dose of 18 Gy. Thirty days after irradiation, 7 rats from each group were anesthetized and their lungs extracted for histopathological examination.

RESULTS

Statistical analyses revealed that CNP significantly decreased the incidence of tissue collapse and neutrophile aggregation in rats receiving CNP before radiation in comparison with the radiation group.

CONCLUSION

The results suggested the possibility of using CNP as a future radioprotector due to its ability to protect normal cells against radiation-induced damage.

Subchronic toxicity of cerium nitrate by 90-day oral exposure in wistar rats

This study evaluated the subchronic toxicity of cerium nitrate and determined the no observed adverse effect level (NOAEL) in Wistar rats. In accordance with the Organization for Economic Co-operation and Development guidelines, cerium nitrate was orally administered to Wistar rats by gavage at 0, 0.2, 75, 150, and 300 mg/kg bw/day for 90 days, followed by 28 days of recovery period in the 300 mg/kg bw/day and the control groups. The following parameters were evaluated: mortality, abnormalities, body weight, food consumption, hematology, serum biochemistry, urinanalysis, gross necropsy and histopathology. At the end of the treatment, several significant changes were observed in the 300 mg/kg bw/day groups: relatively decreased mean body weight of males, increased LYMPH%, RET% and decreased NEUT%, RBC of the females, increased ALT, AST and decreased ALB, T-Bil, CHO, CK, LDH of males. Significantly decreased T-Bil, CHO, CK and LDH were also observed in males of the 150 mg/kg bw/day group. Pathological examination revealed that the incidences of foreign body granulomatous lesions in lungs were higher in the 150 and 300 mg/kg bw/day groups as compared with the control group. These findings were attributed to unexpected gavage exposure because the granuloma exhibited a bronchiole-derived distribution. Taken together, the NOAEL of cerium nitrate in Wistar rats is set to be 75 mg/kg bw/day in the present study.

The first inorganic mitogens: Cerium oxide and cerium fluoride nanoparticles stimulate planarian regeneration via neoblastic activation

We report the first experimental evidence for the mitogenic action of cerium(IV) oxide and cerium(III) fluoride nanoparticles (CONs and CFNs) on the regeneration of a whole organism - freshwater flatworms Schmidtea mediterranea (planarian). Both types of cerium-containing nanoparticles are shown to be a highly potent mitogen for planaria. Both CONs and CFNs, in micro- and nanomolar concentrations, markedly accelerate planarian blastema growth, due to the enhancement of cellular proliferation, causing an increase in the mitotic index and in the quantity of blastema cells in regenerating planaria. CONs provided maximum activity at concentrations which were two orders of magnitude lower than those for CeF₃. The valence state of cerium in cerium-containing nanoparticles plays a significant role in the planarian regeneration mechanism: CeO₂ nanoparticles containing predominantly Ce⁴⁺ species presumably scavenge wound induced reactive oxygen species and moderately activate gene expression processes, while the regenerative action of CeF₃ nanoparticles containing only Ce³⁺ species is manifested in the pronounced expression of the genes involved in cell division, differentiation and migration. This is the first report on the effect of cerium-containing nanoparticles on tissue regeneration in vivo, further revealing the mechanisms of their biological action, which enhances the possibility of their use in cellular technologies.

Pulmonary toxicity of inhaled nano-sized cerium oxide aerosols in Sprague-Dawley rats

Cerium oxide nanoparticles (CeO₂NPs), used in some diesel fuel additives to improve fuel combustion efficiency and exhaust filter operation, have been detected in ambient air and concerns have been raised about their potential human health impact. The majority of CeO₂NP inhalation studies undertaken to date have used aerosol particles of larger sizes than the evidence suggests are emitted from vehicles using such fuel additives. Hence, the objective of this study was to investigate the effects of inhaled CeO₂NP aerosols of a more environmentally relevant size, utilizing a combination of methods, including untargeted multi-omics to enable the broadest possible survey of molecular responses and synchrotron X-ray spectroscopy to investigate cerium speciation. Male Sprague-Dawley rats were exposed by nose-only inhalation to aerosolized CeO₂NPs (mass concentration 1.8 mg/m³, aerosol count median diameter 40 nm) for 3 h/d for 4 d/week, for 1 or 2 weeks and sacrificed at 3 and 7 d post-exposure. Markers of inflammation changed significantly in a dose- and time-dependent manner, which, combined with results from lung histopathology and gene expression analyses suggest an inflammatory response greater than that seen in studies using micron-sized ceria aerosols. Lipidomics of lung tissue revealed changes to minor lipid species, implying specific rather than general cellular effects. Cerium speciation analysis indicated a change in Ce³⁺/Ce⁴⁺ ratio within lung tissue. Collectively, these results in conjunction with earlier studies emphasize the importance of aerosol particle size on toxicity determination. Furthermore, the limited effect resolution within 7 d suggested the possibility of longer-term effects.

Nanoparticles induce apoptosis via mediating diverse cellular pathways

With a special size and structure, nanoparticles (NPs) have excellent application prospects in various fields and are widely used in the biomedicine, cosmetics and chemical industries nowadays. However, there have been some reports on the biosafety of this new type of material, pointing out its cytotoxicity in inducing apoptosis. With different physicochemical properties in size, shape, surface charge, and ligand, NPs exhibit different biocompatibilities when interacting with different cells. Therefore, a comprehensive and deep study into the proapoptotic mechanism of NPs is necessary. In the present review, we summarize the NP-triggered apoptotic signal pathways in detail and highlight some important functional molecules involved. We hope our findings and perspectives provide a new direction for the sound development of nanotechnology in the future.

Intranasal Delivery of Copper Oxide Nanoparticles Induces Pulmonary Toxicity and Fibrosis in C57BL/6 mice

Copper oxide nanoparticles (CuO NPs) are widely used as catalysts or semiconductors in material fields. Recent studies have suggested that CuO NPs have adverse genotoxicity and cytotoxicity effects on various cells. However, little is known about the toxicity of CuO NPs following exposure to murine lungs. The purpose of this fundamental research was to investigate whether CuO NPs could induce epithelial cell injury, pulmonary inflammation, and eventually fibrosis in C57BL/6 mice. Our studies showed that CuO NPs aggravated pulmonary inflammation in a dose-dependent manner. CuO NPs induced apoptosis of epithelial cells as indicated by TUNEL staining, flow cytometry and western blot analysis, which was partially caused by increased reactive oxygen species (ROS). In addition, CuO NPs exposure promoted collagen accumulation and expression of the progressive fibrosis marker α-SMA in the lung tissues, indicating that CuO NP inhalation could induce pulmonary fibrosis in C57BL/6 mice. All data provide novel evidence that there is an urgent need to prevent the adverse effects of CuO NPs in the human respiratory system.

High-dimensional single cell mapping of cerium distribution in the lung immune microenvironment of an active smoker

BACKGROUND

Mass cytometry leverages inductively coupled mass spectrometry to perform high dimensional single cell analyses using antibodies tagged with rare earth isotopes that are considered to be largely absent in biological samples. We have recently noted an unusual exception to this rule while analyzing tissue samples from patients undergoing surgical resection for early stage lung cancer, and here we present a detailed cytometric characterization of cerium in a clinical patient sample.

METHODS

We performed a CyTOF analysis on cell suspensions derived from matched blood, tumor lesion, and non-involved lung tissue from an active smoker undergoing surgical resection for early stage lung adenocarcinoma. The samples were stained with a 31-parameter antibody panel to allow a detailed characterization of the cellular heterogeneity of the samples. The data were visualized using viSNE, major immune subsets were identified based on canonical marker expression patterns, and single cell cerium levels were evaluated across each of these defined subsets.

RESULTS

High dimensional immune cell mapping revealed that high levels of cerium were specifically associated with a phenotypically distinct subset of lung macrophages that were most prevalent in noninvolved lung tissue, whereas tumor associated macrophages showed relatively lower levels of cerium. We hypothesize that these findings reflect alveolar macrophage phagocytosis of inhaled cerium derived from cigarette flint lighters.

CONCLUSIONS

These results demonstrate the first high-dimensional single cell characterization of environmental metal exposure associated with smoking, and offer a demonstration of the unique potential for applying mass cytometry to the field of environmental toxicology. © 2017 International Clinical Cytometry Society.

Effects from a 90-day inhalation toxicity study with cerium oxide and barium sulfate nanoparticles in rats

Background

Nanomaterials like cerium oxide and barium sulfate are frequently processed in industrial and consumer products and exposure of humans and other organisms is likely. Generally less information is given on health effects and toxicity, especially regarding long-term exposure to low nanoparticle doses. Since inhalation is still the major route of uptake the present study focused on pulmonary effects of CeO₂NM-212 (0.1, 0.3, 1.0, 3.0 mg/m³) and BaSO₄NM-220 nanoparticles (50.0 mg/m³) in a 90-day exposure setup. To define particle-related effects and potential mechanisms of action, observations in histopathology, bronchoalveolar lavage and immunohistochemistry were linked to pulmonary deposition and clearance rates. This further allows evaluation of potential overload related effects.

Results

Lung burden values increased with increasing nanoparticle dose levels and ongoing exposure. At higher doses, cerium clearance was impaired, suggesting lung overload. Barium elimination was extremely rapid and without any signs of overload. Bronchoalveolar lavage fluid analysis and histopathology revealed lung tissue inflammation with increasing severity and post-exposure persistency for CeO₂. Also, marker levels for genotoxicity and cell proliferation were significantly increased. BaSO₄ showed less inflammation or persistency of effects and particularly affected the nasal cavity.

Conclusion

CeO₂ nanoparticles penetrate the alveolar space and affect the respiratory tract after inhalation mainly in terms of inflammation. Effects at low dose levels and post-exposure persistency suggest potential long-term effects and a notable relevance for human health. The generated data might be useful to improve nanoparticle risk assessment and threshold value generation. Mechanistic investigations at conditions of non-overload and absent inflammation should be further investigated in future studies.

Anti-inflammatory and antioxidant effect of cerium dioxide nanoparticles immobilized on the surface of silica nanoparticles in rat experimental pneumonia

A massage with the potent counter-inflammatory material, cerium dioxide nanoparticles, is promising and the antioxidant properties of CeO₂ are considered the main, if not the only, mechanism of this action. Nevertheless, the elimination of ceria nano-particles from the organism is very slow and there is a strong concern for toxic effect of ceria due to its accumulation. To overcome this problem, we engineered a combined material in which cerium nanoparticles were immobilized on the surface of silica nanoparticles (CeO₂ NP), which is shown to be easily removed from an organism and could be used as carriers for nano-ceria. In our study particle size was 220±5nm, Zeta-potential -4.5mV (in water), surface charge density -17.22μC/cm² (at pH 7). Thirty-six male Wistar rats, 5 months old and 250-290g were divided into four groups: 1) control; 2) CeO₂ NP treatment; 3) experimental pneumonia (i/p LPS injection, 1mg/kg); and 4) experimental pneumonia treated with CeO₂ NP (4 times during the study in dosage of 0.6mg/kg with an orogastric catheter). Gas exchange and pulmonary ventilation were measured four times: 0, 1, 3 and 24h after LPS injection in both untreated and CeO₂ NP-treated animals. The mRNA of TNF-α, Il-6, and CxCL2 were determined by RT-PCR. ROS-generation in blood plasma and lung tissue homogenates were measured by means of lucigenin- and luminol-enhanced chemiluminescence. Endotoxemia in the acute phase was associated with: (1) pathological changes in lung morphology; (2) increase of ROS generation; (3) enhanced expression of CxCL2; and (4) a gradual decrease of VO₂ and V_E. CeO2 NP treatment of intact animals did not make any changes in all studied parameters except for a significant augmentation of VO₂ and V_E. CeO₂ NP treatment of rats with pneumonia created positive changes in diminishing lung tissue injury, decreasing ROS generation in blood and lung tissue and decreasing pro-inflammatory cytokine expression (TNF-α, Il-6 and CxCL2). Oxygen consumption in this group was increased compared to the LPS pneumonia group. In our study we have shown anti-inflammatory and antioxidant effects of CeO₂ NP. In addition, this paper is the first to report that CeO₂ NP stimulates oxygen consumption in both healthy rats, and rats with pneumonia. We propose the key in understanding the mechanisms behind the phenomena lies in the property of CeO₂ NP to scavenge ROS and the influence of this potent antioxidant on mitochondrial function. The study of biodistribution and elimination of СеО₂NP is the purpose of our ongoing study.

Zinc Oxide Nanoparticle-Poly I:C RNA Complexes: Implication as Therapeutics against Experimental Melanoma

There is current interest in harnessing the combined anticancer and immunological effect of nanoparticles (NPs) and RNA. Here, we evaluate the bioactivity of poly I:C (pIC) RNA, bound to anticancer zinc oxide NP (ZnO-NP) against melanoma. Direct RNA association to unfunctionalized ZnO-NP is shown by observing change in size, zeta potential, and absorption/fluorescence spectra upon complexation. RNA corona was visualized by transmission electron microscopy (TEM) for the first time. Binding constant (K_b = 1.6-2.8 g^-1 L) was determined by modified Stern-Volmer, absorption, and biological surface activity index analysis. The pIC-ZnO-NP complex increased cell death for both human (A375) and mouse (B16F10) cell lines and suppressed tumor cell growth in BALB/C-B16F10 mouse melanoma model. Ex vivo tumor analysis indicated significant molecular activity such as changes in the level of phosphoproteins JNK, Akt, and inflammation markers IL-6 and IFN-γ. High throughput proteomics analysis revealed zinc oxide and poly I:C-specific and combinational patterns that suggested possible utility as an anticancer and immunotherapeutic strategy against melanoma.

Fine Particulate Matter and Sulfur Dioxide Coexposures Induce Rat Lung Pathological Injury and Inflammatory Responses Via TLR4/p38/NF-κB Pathway

Fine particulate matter (PM_2.5) and sulfur dioxide (SO₂) are 2 common air pollutants, but their toxicological effects of coexposure are still not fully clear. In this study, SO₂ exposure (5.6 mg/m³) couldn't cause obvious inflammatory responses in rat lungs. The PM_2.5 exposure (1.5 mg/kg body weight) increased inflammatory cell counts in bronchoalveolar lavage fluid (BALF) and some inflammation damage. Importantly, SO₂ and PM_2.5 (1.5, 6.0, and 24.0 mg/kg) coexposure induced pathological and ultrastructural damage and raised inflammatory cells in BALF compared with the control. Also, they significantly elevated the levels of pro-inflammatory cytokines, adhesion molecule, and nitric oxide (NO) and promoted the gene expression of nuclear factor kappa B (NF-κB), phosphorylated p38 (p-p38), and Toll-like receptor 4 (TLR4) in rat lungs treated with higher dose of PM_2.5 (6.0 and 24.0 mg/kg) plus SO₂ relative to the control or SO₂ group, along with the decreased inhibitor of NF-κBα and increased inhibitor of NF-κB kinase β expressions. The changes in the inflammatory markers in the presence of PM_2.5 plus SO₂ were not significant compared with the PM_2.5 group. The results indicated that inflammatory injury and pathological and ultrastructural damage in rat lungs exposed to PM_2.5 plus SO₂ were involved in TLR4/p38/NF-κB pathway activation accompanied by oversecretion of pro-inflammatory cytokine, adhesion molecule, and NO. It provides more useful evidence to understand the possible toxicological mechanism that PM_2.5 and SO₂ copollution exacerbate lung disease.