The biological effects of inhalable nanoparticles have been widely studied with pulmonary cells cultured under submerged and air-liquid interface (ALI) conditions. culture systems may produce less false unfavorable results than screening with Mouse monoclonal to CD57.4AH1 reacts with HNK1 molecule, a 110 kDa carbohydrate antigen associated with myelin-associated glycoprotein. CD57 expressed on 7-35% of normal peripheral blood lymphocytes including a subset of naturel killer cells, a subset of CD8+ peripheral blood suppressor / cytotoxic T cells, and on some neural tissues. HNK is not expression on granulocytes, platelets, red blood cells and thymocytes. submerged cell cultures. However the database is currently too scarce to draw a definite conclusion on this issue. 1 Introduction Exposure to airborne particles has been linked to adverse health effects including pulmonary inflammation thrombosis neurodegeneration and cardiovascular disease [1-3]. A number of studies have indicated that Tamoxifen Citrate particles with diameters below 100?nm have a more pronounced effect than larger particles implying that nanoparticles (or ultrafine particles) are more toxic on a mass basis [3-6]. Zinc is an ubiquitous transition metal associated with industrial emissions (e.g. mining and smelting of zinc) that typically appears in the form of zinc oxide (ZnO) in ambient particulate matter (PM) [7-9]. ZnO is known as an occupational hazard since inhalation of high concentrations of ZnO formed during welding activities can lead to metal fume fever [10 11 associated with a marked upregulation of proinflammatory markers in the lung [11-13]. In addition to these inadvertently generated ZnO nanoparticles there is a variety of ZnO nanostructures which have shown great potential for nanotechnological products including manufacturing and pharmaceutical applications [14 15 However there is increasing concern that this desirable technological characteristics of nanosized ZnO may be countervailed by increased health and environmental risks due to toxic effects that do not occur for bulk ZnO. While the enhanced toxicity potential of nanoparticles is at least in part due to their inherently large surface-to-mass ratio [4 6 16 17 there is also evidence that some metal particles trigger additional toxicological pathways making them more toxic (per surface area) than many other particle types (e.g. carbon polystyrene) . Cell-based toxicity assays are widely used to assess the toxicity of nanoparticles. These toxicological exposure through inhalation involves deposition of PM onto the lung epithelium that is the cells are exposed to inhaled air (airborne PM) from one side while being in contact with the blood circulation from the other side. Since submerged cell systems are completely covered with cell culture medium (see Figure 1(b)) exposure conditions can be mimicked more realistically by exposing epithelial cells at the air-liquid interface (ALI) (Physique 1(a)). Various ALI exposure systems have been introduced [21-28] but it is usually unclear whether the enhanced experimental complexity of the ALI exposures compared to submerged exposures is usually justified. For that reason we compared the cellular response to nanoparticles after ALI and Tamoxifen Citrate submerged exposure. Physique 1 Schematic of the two cell exposure models used for studying particle-cell conversation. (a) Exposure at the air-liquid interface (ALI): airborne particles are directly deposited on cells produced at the air-liquid interface. (b) Exposure under submerged conditions: … One of the most widely accepted paradigms of particle toxicity says that particles induce inflammation via oxidative stress and subsequent activation of redox-sensitive transcription factors . Nel and colleagues refined and expanded this concept into the hierarchical oxidative stress paradigm [30 31 suggesting the transition from an antioxidant defense response (tier1) to inflammation (tier2) and finally to cytotoxicity (tier3) if the induced stress is usually strong enough. Proinflammatory responses mediated by oxidative stress have been proposed to be not only crucial but also the most sensitive readout for particle toxicity . We therefore measured three proinflammatory cytokines (interleukin-8 (IL-8) IL-6 and granulocyte macrophage colony-stimulating factor (GM-CSF)) and three Tamoxifen Citrate oxidative stress markers (heme oxygenase 1 (HMOX1) superoxide dismutase (SOD-2) and glutamate-cysteine synthetase catalytic subunit (GCS)) by qRT-PCR. In this study the first ALI exposure of human epithelial-like cells (A549) to airborne agglomerates of ZnO nanoparticles is usually presented. The dose- and time-dependent cellular responses of the cells were compared after ZnO exposure under submerged and ALI conditions at two Tamoxifen Citrate dose levels (0.7 and 2.5?toxicity data we deduced corresponding lowest observed effect levels (LOELs) and compared them with similar studies available in the literature. 2 Materials and Methods 2.1 Materials Common laboratory chemicals were purchased from Sigma-Aldrich (Taufkirchen Germany). The.