Minnamari Vippola

Long, needle-like carbon nanotubes and asbestos activate the NLRP3 inflammasome through a similar mechanism.

Carbon nanomaterials (CNM) are targets of great interest because they have multiple applications in industry but also because of the fear of possible harmful heath effects of certain types of CNM. The high aspect ratio of carbon nanotubes (CNT), a feature they share with asbestos, is likely the key factor for reported toxicity of certain CNT. However, the mechanism to explain this toxicity is unclear. Here we investigated whether different CNM induce a pro-inflammatory response in human primary macrophages. Carbon black, short CNT, long, tangled CNT, long, needle-like CNT, and crocidolite asbestos were used to compare the effect of size and shape on the potency of the materials to induce secretion of interleukin (IL) 1-family cytokines. Our results demonstrated that long, needle-like CNT and asbestos activated secretion of IL-1β from LPS-primed macrophages but only long, needle-like CNT induced IL-1α secretion. SiRNA experiments demonstrated that the NLRP3 inflammasome was essential for long, needle-like CNT and asbestos-induced IL-1β secretion. Moreover, it was noted that CNT-induced NLRP3 inflammasome activation depended on reactive oxygen species (ROS) production, cathepsin B activity, P2X(7) receptor, and Src and Syk tyrosine kinases. These results provide new information about the mechanisms by which long, needle-like materials may cause their harmful health effects. Furthermore, the techniques used here may be of use in future risk assessments of nanomaterials.

Proteomic characterization of engineered nanomaterial-protein interactions in relation to surface reactivity.

Adsorption of proteins onto an engineered nanoparticle surface happens immediately after particles come in contact with a biological fluid. However, at the moment very little is known about the mechanisms of interactions between biomolecules and nanomaterials. In this study, eleven thoroughly characterized materials were first investigated in vitro for their ability to enter human lung epithelial cells and human monocyte-derived macrophages. All tested materials were taken up by primary macrophages and epithelial cells. Some of the engineered nanomaterials (ENM) were found in the cytoplasm. Large quantitative and qualitative variation in the binding efficiencies to cellular proteins was observed between different tested nanoparticles. Pulmonary surfactant components significantly reduced the overall protein adsorption on the surface of ENMs. Fibrinogen chains were attached to all materials after exposure to plasma proteins. Common ENM-bound cytoplasmic protein identifications were peroxiredoxin 1, annexin A2, and several ribosomal and cytoskeletal proteins. The underlying mechanism of the ENM-plasma protein interaction may diverge from that of cell lysate proteins, as the binding efficiency to cell lysate proteins appears to depend on the characteristics of the ENM surface, whereas the adsorbed plasma proteins are involved in particle phagocytosis and seem to cover ENMs independently of the their surface properties. Identification of the composition of the nanomaterial-protein complex is crucial for understanding of the uptake mechanisms, biodistribution, and clearance of ENMs, knowledge which is required for safety evaluation and biomedical applications of these materials.

Airway Exposure to Silica-Coated TiO2 Nanoparticles Induces Pulmonary Neutrophilia in Mice

The importance of nanotechnologies and engineered nanoparticles has grown rapidly. It is therefore crucial to acquire up-to-date knowledge of the possible harmful health effects of these materials. Since a multitude of different types of nanosized titanium dioxide (TiO(2)) particles are used in industry, we explored their inflammatory potential using mouse and cell models. BALB/c mice were exposed by inhalation for 2 h, 2 h on 4 consecutive days, or 2 h on 4 consecutive days for 4 weeks to several commercial TiO(2) nanoparticles, SiO(2) nanoparticles, and to nanosized TiO(2) generated in a gas-to-particle conversion process at 10 mg/m(3). In addition, effects of in vitro exposure of human macrophages and fibroblasts (MRC-9) to the different particles were assessed. SiO(2)-coated rutile TiO(2) nanoparticles (cnTiO(2)) was the only sample tested that elicited clear-cut pulmonary neutrophilia. Uncoated rutile and anatase as well as nanosized SiO(2) did not induce significant inflammation. Pulmonary neutrophilia was accompanied by increased expression of tumor necrosis factor-alpha (TNF-alpha) and neutrophil-attracting chemokine CXCL1 in the lung tissue. TiO(2) particles accumulated almost exclusively in the alveolar macrophages. In vitro exposure of murine and human macrophages to cnTiO(2) elicited significant induction of TNF-alpha and neutrophil-attracting chemokines. Stimulation of human fibroblasts with cnTiO(2)-activated macrophage supernatant induced high expression of neutrophil-attracting chemokines, CXCL1 and CXCL8. Interestingly, the level of lung inflammation could not be explained by the surface area of the particles, their primary or agglomerate particle size, or radical formation capacity but is rather explained by the surface coating. Our findings emphasize that it is vitally important to take into account in the risk assessment that alterations of nanoparticles, e.g., by surface coating, may drastically change their toxicological potential.

Genotoxicity of polyvinylpyrrolidone-coated silver nanoparticles in BEAS 2B cells

Silver nanoparticles (AgNPs) are widely utilized in various consumer products and medical devices, especially due to their antimicrobial properties. However, several studies have associated these particles with toxic effects, such as inflammation and oxidative stress in vivo and cytotoxic and genotoxic effects in vitro. Here, we assessed the genotoxic effects of AgNPs coated with polyvinylpyrrolidone (PVP) (average diameter 42.5±14.5 nm) on human bronchial epithelial BEAS 2B cells in vitro. AgNPs were dispersed in bronchial epithelial growth medium (BEGM) with 0.6 mg/ml bovine serum albumin (BSA). The AgNP were partially well-dispersed in the medium and only limited amounts (ca. 0.02 μg Ag(+) ion/l) could be dissolved after 24h. The zeta-potential of the AgNPs was found to be highly negative in pure water but was at least partially neutralized in BEGM with 0.6 mg BSA/ml. Cytotoxicity was measured by cell number count utilizing Trypan Blue exclusion and by an ATP-based luminescence cell viability assay. Genotoxicity was assessed by the alkaline single cell gel electrophoresis (comet) assay, the cytokinesis-block micronucleus (MN) assay, and the chromosomal aberration (CA) assay. The cells were exposed to various doses (0.5-48 μg/cm(2) corresponding to 2.5-240 μg/ml) of AgNPs for 4 and 24 h in the comet assay, for 48 h in the MN assay, and for 24 and 48 h in the CA assay. DNA damage measured by the percent of DNA in comet tail was induced in a dose-dependent manner after both the 4-h and the 24-h exposures to AgNPs, with a statistically significant increase starting at 16 μg/cm(2) (corresponding to 60.8 μg/ml) and doubling of the percentage of DNA in tail at 48 μg/cm(2). However, no induction of MN or CAs was observed at any of the doses or time points. The lack of induction of chromosome damage by the PVP-coated AgNPs is possibly due to the coating which may protect the cells from direct interaction with the AgNPs, either by reducing ion leaching from the particles or by causing extensive agglomeration of the nanoparticles, with a possible reduction of the cellular uptake.

Modified thick thermal barrier coatings: Microstructural characterization

Thick thermal barrier coatings were modified with laser glazing and phosphate based sealing treatments. Surface porosityof the sealed coatings decreased significantly in all cases. Structural analysis showed a strong preferred crystal orientation of the t 0 ZrO2 phase in direction [002] in laser-glazed 25CeO2–2.5Y2O3–ZrO2 coating. In laser-glazed 22MgO–ZrO2 coating the major phase was rhombohedral Mg2Zr5O12. In phosphate sealed 8Y2O3–ZrO2 coating the strengthening mechanism was identified as adhesive binding without chemical bonding. Coating microstructures were determined byscanning electron microscopy , energydispersive spectroscopy, transmission electron microscopy and optical microscopy. Coatings were also characterized by X-ray diffraction, microhardness and porosity. # 2003 Elsevier Ltd. All rights reserved.

Aluminum phosphate sealed alumina coating: characterization of microstructure

Abstract The microstructure of aluminum phosphate sealed plasma-sprayed alumina coating was characterized by X-ray diffractometry, scanning electron microscopy, and analytical transmission electron microscopy. Microstructural characterization was carried out to identify the phases of the coating and to understand better the strengthening effect of aluminum phosphate sealant in the coating. The main phases in the coating are metastable γ-Al 2 O 3 and stable α-Al 2 O 3 . The overall structure of the coating is lamellar with columnar γ-Al 2 O 3 grains. The aluminum phosphate sealant shows good penetration into the coating to the depth of about 300 μm filling the structural defects such as pores, cracks and gaps between the lamellae. The sealant in the coating has the relative composition of 26 at.% aluminum and 74 at.% phosphorus giving the molar ratio P:Al of 3, which refers to the metaphosphates Al(PO 3 ) 3 . There is also some crystalline aluminum phosphate in the coating, in the form of berlinite-type orthophosphate AlPO 4 , owing to the reaction between the sealant and the alumina coating. Thus, the phosphate bonding in the alumina coating is based both on chemical bonding resulting from the chemical reaction with the alumina coating and on adhesive binding resulting from the formation of the condensed phosphates in the structural defects of the coating.

Inhalation of rod-like carbon nanotubes causes unconventional allergic airway inflammation

BackgroundCarbon nanotubes (CNT) represent a great promise for technological and industrial development but serious concerns on their health effects have also emerged. Rod-shaped CNT are, in fact, able to induce asbestos-like pathogenicity in mice including granuloma formation in abdominal cavity and sub-pleural fibrosis. Exposure to CNT, especially in the occupational context, happens mainly by inhalation. However, little is known about the possible effects of CNT on pulmonary allergic diseases, such as asthma.MethodsWe exposed mice by inhalation to two types of multi-walled CNT, rigid rod-like and flexible tangled CNT, for four hours a day once or on four consecutive days. Early events were monitored immediately and 24 hours after the single inhalation exposure and the four day exposure mimicked an occupational work week. Mast cell deficient mice were used to evaluate the role of mast cells in the occurring inflammation.ResultsHere we show that even a short-term inhalation of the rod-like CNT induces novel innate immunity-mediated allergic-like airway inflammation in healthy mice. Marked eosinophilia was accompanied by mucus hypersecretion, AHR and the expression of Th2-type cytokines. Exploration of the early events by transcriptomics analysis reveals that a single 4-h exposure to rod-shaped CNT, but not to tangled CNT, causes a radical up-regulation of genes involved in innate immunity and cytokine/chemokine pathways. Mast cells were found to partially regulate the inflammation caused by rod-like CNT, but also alveaolar macrophages play an important role in the early stages.ConclusionsThese observations emphasize the diverse abilities of CNT to impact the immune system, and they should be taken into account for hazard assessment.

Generation of silver/palladium nanoparticles by liquid flame spray

Ag-Pd alloy nanoparticles have been generated from silver and palladium nitrate precursors using a high temperature aerosol method, the liquid flame spray (LFS) process. In the LFS process, a spray aerosol of precursor liquid is introduced into a high-temperature H 2 -O 2 flame. The primary micron-sized spray droplets evaporate in the flame, and the final particulate product is a result of the nucleation of the pure metal vapors shortly after the flame. In the study, three Ag-Pd molar ratios-10:90, 50:50, and 90:10-were used in the precursor. As a result of the synthesis, metal alloy nanoparticles with practically the same concentration ratios, correspondingly, were produced with the method. In the experiments, metal mass flow rates of 0.01-0.8 g/min were covered. The size of the particles was determined to be in the range of 10-50 nm by aerosol instrumentation. The particles were spherical and slightly agglomerated. It was concluded that the particle size can be controlled via the total precursor mass flow rate, and the composition can be controlled by the molar ratio of Ag and Pd compounds in the precursor liquid.

Topically applied ZnO nanoparticles suppress allergen induced skin inflammation but induce vigorous IgE production in the atopic dermatitis mouse model

BackgroundMetal oxide nanoparticles such as ZnO are used in sunscreens as they improve their optical properties against the UV-light that causes dermal damage and skin cancer. However, the hazardous properties of the particles used as UV-filters in the sunscreens and applied to the skin have remained uncharacterized.MethodsHere we investigated whether different sized ZnO particles would be able to penetrate injured skin and injured allergic skin in the mouse atopic dermatitis model after repeated topical application of ZnO particles. Nano-sized ZnO (nZnO) and bulk-sized ZnO (bZnO) were applied to mechanically damaged mouse skin with or without allergen/superantigen sensitization. Allergen/superantigen sensitization evokes local inflammation and allergy in the skin and is used as a disease model of atopic dermatitis (AD).ResultsOur results demonstrate that only nZnO is able to reach into the deep layers of the allergic skin whereas bZnO stays in the upper layers of both damaged and allergic skin. In addition, both types of particles diminish the local skin inflammation induced in the mouse model of AD; however, nZnO has a higher potential to suppress the local effects. In addition, especially nZnO induces systemic production of IgE antibodies, evidence of allergy promoting adjuvant properties for topically applied nZnO.ConclusionsThese results provide new hazard characterization data about the metal oxide nanoparticles commonly used in cosmetic products and provide new insights into the dermal exposure and hazard assessment of these materials in injured skin.

A Single Aspiration of Rod-like Carbon Nanotubes Induces Asbestos-like Pulmonary Inflammation Mediated in Part by the IL-1 Receptor

Carbon nanotubes (CNT) have been eagerly studied because of their multiple applications in product development and potential risks on health. We investigated the difference of two different CNT and asbestos in inducing proinflammatory reactions in C57BL/6 mice after single pharyngeal aspiration exposure. We used long tangled and long rod-like CNT, as well as crocidolite asbestos at a dose of 10 or 40 µg/mouse. The mice were sacrificed 4 and 16 h or 7, 14, and 28 days after the exposure. To find out the importance of a major inflammatory marker IL-1β in CNT-induced pulmonary inflammation, we used etanercept and anakinra as antagonists as well as Interleukin 1 (IL-1) receptor (IL-1R-/-) mice. The results showed that rod-like CNT, and asbestos in lesser extent, induced strong pulmonary neutrophilia accompanied by the proinflammatory cytokines and chemokines 16 h after the exposure. Seven days after the exposure, neutrophilia had essentially disappeared but strong pulmonary eosinophilia peaked in rod-like CNT and asbestos-exposed groups. After 28 days, pulmonary granulomas, goblet cell hyperplasia, and Charcot-Leyden-like crystals containing acidophilic macrophages were observed especially in rod-like CNT-exposed mice. IL-1R-/- mice and antagonists-treated mice exhibited a significant decrease in neutrophilia and messenger ribonucleic acid (mRNA) levels of proinflammatory cytokines at 16 h. However, rod-like CNT-induced Th2-type inflammation evidenced by the expression of IL-13 and mucus production was unaffected in IL-1R-/- mice at 28 days. This study provides knowledge about the pulmonary effects induced by a single exposure to the CNT and contributes to hazard assessment of carbon nanomaterials on airway exposure.