Endocytosis of ultrafine particles by A549 cells

Supported Erythrocyte Membranes on Piezoelectric Sensors for Studying the Interactions with Nanoparticles

Applications of nanoparticles (NPs) in nanodrugs, food additives, and cosmetics can result in the presence of nanomaterials in the human circulatory system and their attachment to red blood cells (RBCs), which may lead to cytotoxic effects. To investigate the interactions of NPs with RBC membranes (RBCm), supported erythrocyte membranes (SRBCm) were developed on piezoelectric sensors in a quartz crystal microbalance with dissipation (QCM-D) at 25 °C. A well-dispersed RBCm suspension at 1 mM NaCl and 0.2 mM NaHCO3 was obtained from whole blood and comprised colloidal membrane fragments with the average hydrodynamic diameter and zeta potential of 390 nm and -0.53 mV, respectively, at pH 7.0. The thin and rigid SRBCm was formed mainly through the deposition of RBCm fragments on the poly-l-lysine-modified crystal sensor, leading to the average frequency shift of -26.2 Hz and the low ratio of the dissipation to frequency shift (7.2 × 10-8 Hz-1). The complete coverage of SRBCm was indicated by the plateau of the frequency shift in the stage of SRBCm formation and no deposition of negatively charged 106 nm polystyrene nanoparticles (PSNPs) on the SRBCm. Atomic force microscopy and immunofluorescence microscopy images showed that RBCm aggregates with the average size of 420 nm and erythrocyte membrane proteins existed on SRBCm, respectively. The methods of determining attachment efficiencies of model positively charged NPs (i.e., hematite NPs or HemNPs) and model negatively charged NPs (i.e., PSNPs) on SRBCm were demonstrated in 1 mM NaCl solution at pH 5.1 and pH 7.0, respectively. HemNPs exhibited a favorable deposition with an attachment efficiency of 0.99 while PSNPs did not show any attachment propensity toward SRBCm.

Lysosomal nanotoxicity: Impact of nanomedicines on lysosomal function

Although several nanomedicines got clinical approval over the past two decades, the clinical translation rate is relatively small so far. There are many post-surveillance withdrawals of nanomedicines caused by various safety issues. For successful clinical advancement of nanotechnology, it is of unmet need to realize cellular and molecular foundation of nanotoxicity. Current data suggest that lysosomal dysfunction caused by nanoparticles is emerging as the most common intracellular trigger of nanotoxicity. This review analyzes prospect mechanisms of lysosomal dysfunction-mediated toxicity induced by nanoparticles. We summarized and critically assessed adverse drug reactions of current clinically approved nanomedicines. Importantly, we show that physicochemical properties have great impact on nanoparticles interaction with cells, excretion route and kinetics, and subsequently on toxicity. We analyzed literature on adverse reactions of current nanomedicines and hypothesized that adverse reactions might be linked with lysosomal dysfunction caused by nanomedicines. Finally, from our analysis it becomes clear that it is unjustifiable to generalize safety and toxicity of nanoparticles, since different particles possess distinct toxicological properties. We propose that the biological mechanism of the disease progression and treatment should be central in the optimization of nanoparticle design.

The influence of exposure approaches to in vitro lung epithelial barrier models to assess engineered nanomaterial hazard

Exposure to engineered nanomaterials (ENM) poses a potential health risk to humans through long-term, repetitive low-dose exposures. Currently, this is not commonplace within in vitro lung cell cultures. Therefore, the purpose of this study was to consider the optimal exposure approach toward determining the stability, sensitivity and validity of using in vitro lung cell mono- and co-cultures to determine ENM hazard. A range of exposure scenarios were conducted with DQ₁₂ (previously established as a positive particle control) (historic and re-activated), TiO₂ (JRC NM-105) and BaSO₄ (JRC NM-220) on both monocultures of A549 cells as well as co-cultures of A549 cells and differentiated THP-1 cells. Cell cultures were exposed to either a single, or a repeated exposure over 24, 48- or 72-hours at in vivo extrapolated concentrations of 0-5.2 µg/cm², 0-6 µg/cm² and 0-1µg/cm². The focus of this study was the pro-inflammatory, cytotoxic and genotoxic response elicited by these ENMs. Exposure to DQ₁₂ caused pro-inflammatory responses after 48 hours repeat exposures, as well as increases in micronucleus frequency. Neither TiO₂ nor BaSO₄ elicited a pro-inflammatory response at this time point. However, there was induction of IL-6 after 24 hours TiO₂ exposure. In conclusion, it is important to consider the appropriateness of the positive control implemented, the cell culture model, the time of exposure as well as the type of exposure (bolus or fractionated) before establishing if an in vitro model is appropriate to determine the level of response to the specific ENM of interest.

Design and Characterization of Atorvastatin Dry Powder Formulation as a potential Lung Cancer Treatment

Lung cancer is the leading cause of cancer death. Many studies have shown the beneficial effects of Atorvastatin in decreasing the mortality risk and improving survival among patients with lung cancer. This research paper focuses on improving AVT cytotoxic activity and cellular uptake by developing mannitol microcarriers as a promising drug delivery system for lung cancer treatment and, studying the impact of improving inhalation deposition on the delivery and Dry Powder formulations efficiency. The AVT loaded mannitol (AM) microparticles (AVT-AM) formulation was prepared by spray drying and characterized for its physicochemical properties and aerodynamic deposition. The results revealed that the AVT-AM formulation has good flow properties and aerosol deposition with a particle size of 3418 nm ± 26.86. The formulation was also assessed in vitro for cytotoxicity effects (proliferation, apoptosis, and cell cycle progression) on A549 human lung adenocarcinoma. Compared with free AVT, the AVT-AM formulation has significantly higher cellular uptake and anti-cancer properties by disrupting cell cycle progression via either apoptosis or cell cycle arrest in the G2/M phase. This study shows that AVT loaded mannitol microcarriers may provide a potentially effective and sustained pulmonary drug delivery for lung cancer treatment.

Formation and biological effects of protein corona for food-related nanoparticles

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

Comparative and mechanistic toxicity assessment of structure-dependent toxicity of carbon-based nanomaterials

The wide application of carbon-based nanomaterials (CNMs) has resulted in the ubiquity of CNMs in the natural environment and they potentially impose adverse consequences on ecosystems and human health. In this study, we comprehensively evaluated and compared potential toxicological effects and mechanisms of seven CNMs in three representative types (carbon blacks, graphene nanoplatelets, and fullerenes), to elucidate the correlation between their physicochemical/structural properties and toxicity. We employed a recently-developed quantitative toxicogenomics-based toxicity testing system with GFP-fused yeast reporter library targeting main cellular stress response pathways, as well as conventional phenotype-based bioassays. The results revealed that DNA damage, oxidative stress, and protein stress were the major mechanisms of action for all the CNMs at sub-cytotoxic concentration levels. The molecular toxicity nature were concentration-dependent, and they exhibited both similarity within the same structural group and distinctiveness among different CNMs, evidencing the structure-driven toxicity of CNMs. The toxic potential based on toxicogenomics molecular endpoints revealed the remarkable impact of size and structure on the toxicity. Furthermore, the phenotypic endpoints derived from conventional phenotype-based bioassays correlated with quantitative molecular endpoints derived from the toxicogenomics assay, suggesting that the selected protein biomarkers captured the main cellular effects that are associated with phenotypic adverse outcomes.

Cytotoxicity and estrogenicity in simulated dental wastewater after grinding of resin-based materials

OBJECTIVE

This study evaluated the cytotoxic and estrogenic effects of dust and eluates released into simulated wastewater after grinding of dental resin-based materials.

METHODS

Four materials were used: ceram.x® universal, Filtek™ Supreme XTE, Lava™ Ultimate and Core-X™ flow. From each composite material, samples (5 × 2 mm, n = 50) were prepared according to the manufacturers' instructions. Lava™ Ultimate was used as blocks. All samples were ground to dust with a diamond bur (106 μm) and suspended in distilled water at 60 mg/mL. After storage for 72 h, the suspensions were separated into a soluble (eluate) and a particulate (dust) fraction. Eluates and dusts were evaluated for inhibition of Vibrio fischeri bioluminescence and cytotoxicity on human A549 lung cells (WST-1-Assay). The estrogenic activity was assessed by YES-Assay using Saccharomyces cerevisiae. Additionally, dental monomers (BisGMA, BisEMA, UDMA, TEGDMA, HEMA) and Bisphenol A were investigated.

RESULTS

All eluates showed inhibition of V. fischeri bioluminescence at concentrations above 1.1 mg/mL (p < 0.05). The activity of the eluates of ceram.x® universal and Filtek™ Supreme XTE was significantly higher than Lava™ Ultimate and Core-X™ flow (p < 0.05). In the WST-1-Assay, all materials induced cytotoxic effects at concentrations of 0.1 mg/mL (p < 0.05), while no significant differences were detected among them. The tested materials revealed no estrogenic activity. All dental monomers and Bisphenol A showed concentration dependent cytotoxic effects (p < 0.05), whereas only Bisphenol A induced an estrogenic effect (p < 0.01).

SIGNIFICANCE

Dust and eluates of resin-based dental materials released into wastewater exert bactericidal and cytotoxic effects in vitro. However, they reveal no estrogenic effect.

Differential response of immobile (pneumocytes) and mobile (monocytes) barriers against 2 types of metal oxide nanoparticles

BACKGROUND

Inhaled nanoparticles (NPs) challenges mobile and immobile barriers in the respiratory tract, which can be represented by type II pneumocytes (immobile) and monocytes (mobile) but what is more important for biological effects, the cell linage, or the type of nanoparticle? Here, we addressed these questions and we demonstrated that the type of NPs exerts a higher influence on biological effects, but cell linages also respond differently against similar type of NPs.

DESIGN

Type II pneumocytes and monocytes were exposed to tin dioxide (SnO₂) NPs and titanium dioxide (TiO₂) NPs (1, 10 and 50 μg/cm²) for 24 h and cell viability, ultrastructure, cell granularity, molecular spectra of lipids, proteins and nucleic acids and cytoskeleton architecture were evaluated.

RESULTS

SnO₂ NPs and TiO₂ NPs are metal oxides with similar physicochemical properties. However, in the absence of cytotoxicity, SnO₂ NPs uptake was low in monocytes and higher in type II pneumocytes, while TiO₂ NPs were highly internalized by both types of cells. Monocytes exposed to both types of NPs displayed higher number of alterations in the molecular patterns of proteins and nuclei acids analyzed by Fourier-transform infrared spectroscopy (FTIR) than type II pneumocytes. In addition, cells exposed to TiO₂ NPs showed more displacements in FTIR spectra of biomolecules than cells exposed to SnO₂ NPs. Regarding cell architecture, microtubules were stable in type II pneumocytes exposed to both types of NPs but actin filaments displayed a higher number of alterations in type II pneumocytes and monocytes exposed to SnO₂ NPs and TiO₂ NPs. NPs exposure induced the formation of large vacuoles only in monocytes, which were not seen in type II pneumocytes.

CONCLUSIONS

Most of the cellular effects are influenced by the NPs exposure rather than by the cell type. However, mobile, and immobile barriers in the respiratory tract displayed differential response against SnO₂ NPs and TiO₂ NPs in absence of cytotoxicity, in which monocytes were more susceptible than type II pneumocytes to NPs exposure.

Cytotoxicity and DNA damage evaluation of TiO2 and ZnO nanoparticles. Uptake in lung cells in culture

The cytotoxicity and DNA damage of titanium dioxide and zinc oxide nanoparticles (TiO₂ and ZnO NPs) have been studied in a human lung carcinoma cell line (A549) after 24 h exposure. TiO₂ and ZnO NPs had mean diameters of 12.9 ± 2.8 and 24.1 ± 8.0 nm, respectively. ZnO NPs reduced cell viability from 250 μg/mL, increasing reactive oxygen species (ROS) and decreased GSH/GSSG ratio. The comet assay detected DNA damage from 50 μg/mL. TiO₂ NPs induced cytotoxicity and DNA damage from 50 to 100 μg/mL, respectively, along with a decrease of the GSH/GSSG ratio. Both particles were found inside the cells, within membrane-bound vesicles. The internalization mechanism is promoted partially by caveolae-mediated endocytosis and, in the case of TiO₂ NPs, also by macropinocytosis.

SARS-CoV-2 infection, COVID-19 pathogenesis, and exposure to air pollution: What is the connection?

Exposure to air pollutants has been previously associated with respiratory viral infections, including influenza, measles, mumps, rhinovirus, and respiratory syncytial virus. Epidemiological studies have also suggested that air pollution exposure is associated with increased cases of SARS-CoV-2 infection and COVID-19-associated mortality, although the molecular mechanisms by which pollutant exposure affects viral infection and pathogenesis of COVID-19 remain unknown. In this review, we suggest potential molecular mechanisms that could account for this association. We have focused on the potential effect of exposure to nitrogen dioxide (NO2 ), ozone (O3 ), and particulate matter (PM) since there are studies investigating how exposure to these pollutants affects the life cycle of other viruses. We have concluded that pollutant exposure may affect different stages of the viral life cycle, including inhibition of mucociliary clearance, alteration of viral receptors and proteases required for entry, changes to antiviral interferon production and viral replication, changes in viral assembly mediated by autophagy, prevention of uptake by macrophages, and promotion of viral spread by increasing epithelial permeability. We believe that exposure to pollutants skews adaptive immune responses toward bacterial/allergic immune responses, as opposed to antiviral responses. Exposure to air pollutants could also predispose exposed populations toward developing COIVD-19-associated immunopathology, enhancing virus-induced tissue inflammation and damage.

Zinc oxide nanoparticles (ZnO NPs) combined with cisplatin and gemcitabine inhibits tumor activity of NSCLC cells

Non-small cell lung cancer (NSCLC) is one of the most common malignancies worldwide. The use of a combination of chemotherapy drugs and zinc oxide nanoparticles (ZnO-NPs), which have proven to induce tumor-selective cell death, reduce the drug resistance and reduce the side effects in vitro. In the present study, we developed ZnO-NPs loaded with both cisplatin (Cp) and gemcitabine (Gem) (ZnO-NPs(Cp/Gem)), then the morphologies and the size distribution of ZnO-NPs(Cp/Gem) particles were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Also, MTT, western blot and Annexin V-PI were used to assess the anti-tumor role of ZnO-NPs(Cp/Gem) in A549 cells. The viability for A549 cells showed a significant decrease in the ZnO NPs(Cp/Gem) group, respectively relative to Cp, Gem, the combination of Cp and Gem (Cp+Gem), and ZnO-NPs loaded with Cp (ZnO-NPs(Cp)) or Gem (ZnO-NPs(Gem)). Furthermore, ZnO-NPs(Cp/Gem) remarkably enhanced the apoptosis-promoting effect of Cp and Gem in A549 cells. The xenograft model showed that Zno-NPS (Cp/Gem) significantly enhanced the inhibition of Cp and Gem on tumor formation. The above results suggested that therapy of NSCLC with ZnO-NPs(Cp/Gem) could enhance the cytotoxic action of chemotherapeutic agents synergistically, indicating a promising potential for ZnO-NPs in antitumor applications.

Food-Grade TiO2 Particles Generate Intracellular Superoxide and Alter Epigenetic Modifiers in Human Lung Cells

Titanium dioxide (TiO₂) particles are a common ingredient in food, providing the bright white color for many candies, gums, and frostings. While ingestion of these materials has been examined previously, few studies have examined the effect of these particles on lung cells. Inhalation is an important exposure pathway for workers processing these foods and, more recently, home users who purchase these particles directly. We examine the response of lung cells to food-grade TiO₂ particles using a combination of fluorescence microscopy and RT-PCR. These experiments show that TiO₂ particles generate intracellular reactive oxygen species, specifically superoxide, and alter expression of two epigenetic modifiers, histone deacetylase 9 (HDAC9) and HDAC10. We use a protein corona formed from superoxide dismutase (SOD), an enzyme that scavenges superoxide, to probe the relationship between TiO₂ particles and superoxide generation. These experiments show that low, non-cytotoxic, concentrations of food-grade TiO₂ particles lead to cellular responses, including altering two enzymes responsible for epigenetic modifications. This production of superoxide and change in epigenetic modifiers could affect human health following inhalation. We expect this research will motivate future in vivo experiments examining the pulmonary response to food-grade TiO₂ particles.

The effect of dust storm particles on single human lung cancer cells

Exposure to dust particles during dust storms can lead to respiratory problems, diseases, and even death. The effect of dust particles at the cellular level is poorly understood. In this study, we investigated the impact that dust storm particles (Montmorillonite) have on human lung epithelial cells (A549) at the single cell level. Using live-cell imaging, we continuously followed individual cells after exposure to a wide range of concentrations of dust particles. We monitored the growth trajectory of each cell including number and timing of divisions, interaction with the dust particles, as well as time and mechanism of cell death. We found that individual cells show different cellular fates (survival or death) even in response to the same dust concentration. Cells that died interacted with dust particles for longer times, and engulfed more dust particles, compared with surviving cells. While higher dust concentrations reduced viability in a dose-dependent manner, the effect on cell death was non-monotonic, with intermediate dust concentration leading to a larger fraction of dying cells compared to lower and higher concentrations. This non-monotonic relationship was explained by our findings that high dust concentrations inhibit cell proliferation. Using cellular morphological features, supported by immunoblots and proinflammatory cytokines, we determined that apoptosis is the dominant death mechanism at low dust concentrations, while higher dust concentrations activate necrosis. Similar single cell approaches can serve as a baseline for evaluating other aerosol types that will improve our understanding of the health-related consequences of exposure to dust storms.

Quasi-ultrafine particles promote cell metastasis via HMGB1-mediated cancer cell adhesion

With increasingly severe air pollution, the aggravated health risks of particulate matter, especially ultrafine particles, are emerging as an urgent and sensitive topic. Considering the heterogeneity and complexity of ultrafine particles, there is insufficient evidence about their toxic effects and possible molecular mechanisms. To address this question, we analyzed the emission characteristics of quasi-ultrafine particles collected during winter in a typical coal-burning city, Taiyuan, and confirmed their contribution to lung cancer cell adhesion and metastasis. For the specific mechanism, we revealed that the endocytosis of quasi-ultrafine particles stimulated the release of HMGB1, induced NFκB-facilitated proinflammatory cytokine production through the interaction of HMGB1 with RAGE, and resulted in cancer-endothelial cell adhesion. These findings remind us of the potential effects of anthropogenic quasi-ultrafine particle pollution and provide a theoretical reference for the mitigation of tumorigenesis in a severe particulate matter contaminated environment.

A Comprehensive Review on the Synthesis, Characterization, and Biomedical Application of Platinum Nanoparticles

Platinum nanoparticles (PtNPs) are noteworthy scientific tools that are being explored in various biotechnological, nanomedicinal, and pharmacological fields. They are unique because of their large surface area and their numerous catalytic applications such as their use in automotive catalytic converters and as petrochemical cracking catalysts. PtNPs have been widely utilized not only in the industry, but also in medicine and diagnostics. PtNPs are extensively studied because of their antimicrobial, antioxidant, and anticancer properties. So far, only one review has been dedicated to the application of PtNPs to nanomedicine. However, no studies describe the synthesis, characterization, and biomedical application of PtNPs. Therefore, the aim of this review is to provide a comprehensive assessment of the current knowledge regarding the synthesis, including physical, chemical, and biological and toxicological effects of PtNPs on human health, in terms of both in vivo and in vitro experimental analysis. Special attention has been focused on the biological synthesis of PtNPs using various templates as reducing and stabilizing agents. Finally, we discuss the biomedical and other applications of PtNPs.

Impacts of Organomodified Nanoclays and Their Incinerated Byproducts on Bronchial Cell Monolayer Integrity

Incorporation of engineered nanomaterials (ENMs) into nanocomposites using advanced manufacturing strategies is set to revolutionize diverse technologies. Of these, organomodified nanoclays (ONCs; i.e., smectite clays with different organic coatings) act as nanofillers in applications ranging from automotive to aerospace and biomedical systems. Recent toxicological evaluations increased awareness that exposure to ONC can occur along their entire life cycle, namely, during synthesis, handling, use, manipulation, and disposal. Compared to other ENMs, however, little information exists describing which physicochemical properties contribute to induced health risk. This study conducted high content screening on bronchial epithelial cell monolayers for coupled high-throughput in vitro assessment strategies aimed to evaluate acute toxicity of a library of ONCs (all of prevalent use) prior to and after simulated disposal by incineration. Coating-, incineration status-, and time-dependent effects were considered to determine changes in the pulmonary monolayer integrity, cell transepithelial resistance, apoptosis, and cell metabolism. Results showed that after exposure to each ONC at its half-maximal inhibitory concentration (IC₅₀) there is a material-induced toxicity effect with pristine nanoclay, for instance, displaying acute loss of monolayer coverage, resistance, and metabolism, coupled with increased number of apoptotic cells. Conversely, the other three ONCs tested displayed little loss of monolayer integrity; however, they exhibited differential coating-dependent increased apoptosis and up to 40-45% initial reduction in cell metabolism. Moreover, incinerated byproducts of ONCs exhibited significant loss of monolayer coverage and integrity, increased necrosis, with little evidence of monolayer re-establishment. These findings indicate that characteristics of organic coating type largely determine the mechanism of cytotoxicity and the ability of the monolayer to recover. Use of high content screening coupled with traditional in vitro assays proves to serve as a rapid pulmonary toxicity assessment tool to help define prevention by targeted physicochemical material properties design strategies.

Air-liquid interface culture changes surface properties of A549 cells

A549 cells are common models in the assessment of respiratory cytotoxicity. To provide physiologically more representative exposure conditions and increase the differentiation state, respiratory cells, for instance Calu-3 bronchial epithelial cells, are cultured at an air-liquid interface (ALI). There are indications that A549 cells also change their phenotype upon culture in ALI. The influence of culture in two variations of transwell cultures compared to conventional culture in plastic wells on the phenotype of A549 cells was studied. Cells were characterized by morphology, proliferation and transepithelial electrical resistance, whole genome transcription analysis, Western blot and immunocytochemical detection of pro-surfactant proteins. Furthermore, lipid staining, surface morphology, cell elasticity, surface tension and reaction to quartz particles were performed. Relatively small changes were noted in the expression of differentiation markers for alveolar cells but A549 cells cultured in ALI showed marked differences in lipid staining and surface morphology, surface tension and cytotoxicity of quartz particles. Data show that changes in physiological reactions of A549 cells in ALI culture were rather caused by change of surface properties than by increased expression of surfactant proteins.

Uptake of nanowires by human lung adenocarcinoma cells

Semiconductor nanowires are increasingly used in optoelectronic devices. However, their effects on human health have not been assessed fully. Here, we investigate the effects of gallium phosphide nanowires on human lung adenocarcinoma cells. Four different geometries of nanowires were suspended in the cell culture for 48 hours. We show that cells internalize the nanowires and that the nanowires have no effect on cell proliferation rate, motility, viability and intracellular ROS levels. By blocking specific internalization pathways, we demonstrate that the nanowire uptake is the result of a combination of processes, requiring dynamin and actin polymerization, which suggests an internalization through macropinocytosis and phagocytosis.

Toxicological evaluation of airborne particulate matter. Are cell culture technologies ready to replace animal testing?

Exposure to atmospheric particulate matter (PM) can affect human health, causing asthma, atherosclerosis, renal disease and cancer. In the last few years, outdoor air pollution has increased globally, leading to a public health emergency. Epidemiological studies have reported a correlation between the development of severe respiratory and systemic diseases and exposure to PM. To evaluate the toxic effect of PM of different origins, conventional experimental toxicological investigations have been conducted in animals; however, animal experimentation poses major ethical issues and usually differs from human conditions. As an alternative, human cell cultures are increasingly being used to investigate cellular and molecular mechanisms of PM toxicity. Although 2D cell cultures have been proven helpful, they are far from being a valid alternative to animal tests. Recently, 3D cell culture and organ-on-chip technology have provided systems that are more complex and that can be more informative for toxicity studies. In this review, the results of the 2D systems that are most frequently used for PM toxicity evaluations are summarized with a special focus on their limitations. We also examined to which extent 3D cell culture and particularly the organ-on-chip technology may overcome these limitations and represent effective tools to improve airborne PM toxicity evaluations.

Effect of pristine and functionalized multiwalled carbon nanotubes on rat renal cortex

The increasing application of carbon nanotubes (CNTs) within environmental, occupational and consumer settings has raised concerns regarding their biosafety and adverse effects on human health. The present study was designed to investigate the possible adverse effect of pristine and functionalized (amylated and polyethelene glycol coated) multi-walled (MW) CNTs on rat kidney with special concern to the histological alterations and the associated oxidative stress, apoptosis and inflammation. Healthy male albino rats (n = 40) were randomly divided into 4 groups: group I (control), group II (pristine MWCNTs), group III (amylated MWCNTs) and group IV [polyethelene glycol (PEG)-coated MWCNTs]. Animals of groups II, III and IV received a single dose of 1 mg/kg body weight of MWCNTs via intra-tracheal (IT) instillation at the beginning of the experiment and all rats were sacrificed after 30 days. Rats in groups II and III showed, nearly similar, renal tissue damage (evidenced by thin collapsed glomeruli, packed mesangial and endothelial cells as well as edematous hemorrhagic glomeruli with apoptotic changes) and functional disruptions (indicated by high serum levels of urea and creatinine) probably through induction of oxidative stress [revealed by high level of the lipid peroxidation marker malondialdehyde (MDA) and lower levels of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx)], apoptosis (indicated by high caspase 3 activity), and inflammation (evidenced by high level of IL1β). However, PEG-coated MWCNTs-treated group (group IV) showed nearly normal renal structure and function. It could be concluded that pristine and functionalized amylated MWCNTs have nephrotoxic effect, while PEG-coated MWCNTs had lowest, or none, toxic effects making them safer for therapy and diagnosis of a variety of diseases.

Single-Domain Antibody-Functionalized pH-Responsive Amphiphilic Block Copolymer Nanoparticles for Epidermal Growth Factor Receptor Targeted Cancer Therapy

Biocompatible antibody-nanoparticle conjugates have attracted interest as anticancer agents due to their potential to selectively target therapeutic agents at disease sites. However, new formulation and conjugation approaches are urgently needed to improve their uniformity for clinical applications. Here, a pH-responsive benzaldehyde-functionalized poly[oligo(ethylene glycol) methacrylate-st-para-formyl phenyl methacrylate]-b-poly[2-(diisopropyl)aminoethyl methacrylate] [P(OEGMA-st-pFPMA)-b-PDPA] block copolymer, prepared by reversible addition-fragmentation chain transfer polymerization, produced PEGylated nanoparticles (pH ∼ 7.4) by a single emulsion-solvent evaporation formulation approach. Efficient site-specific attachment of an aminooxy-functionalized anti-EGFR single-domain antibody (sdAb) on these benzaldehyde-decorated nanoparticles is achieved by oxime bond formation. These nanoconjugates can specifically bind EGFR (modified ELISA) and have enhanced uptake over nonfunctionalized controls in EGFR-positive HeLa cells. Encapsulation of rhodamine 6G dye and its dispersion upon cellular uptake, consistent with nanoparticle stability loss at pH < 5.7, prove their ability to facilitate triggered release in endosomal compartments and highlight their potential for use as next-generation antibody-drug nanoconjugates for therapeutic drug delivery.

Hydrocortisone Promotes Differentiation of Mouse Embryonic Stem Cell-Derived Definitive Endoderm toward Lung Alveolar Epithelial Cells

Objective

The ability to generate lung alveolar epithelial type II (ATII) cells from pluripotent stem cells (PSCs) enables the study of lung development, regenerative medicine, and modeling of lung diseases. The establishment of defined, scalable differentiation methods is a step toward this goal. This study intends to investigate the competency of small molecule induced mouse embryonic stem cell-derived definitive endoderm (mESC-DE) cells towards ATII cells.

Materials and Methods

In this experimental study, we designed a two-step differentiation protocol. mESC line Royan B20 (RB20) was induced to differentiate into DE (6 days) and then into ATII cells (9 days) by using an adherent culture method. To induce differentiation, we treated the mESCs for 6 days in serum-free differentiation (SFD) media and induced them with 200 nM small molecule inducer of definitive endoderm 2 (IDE2). For days 7-15 (9 days) of induction, we treated the resultant DE cells with new differentiation media comprised of 100 ng/ml fibroblast growth factor (FGF2) (group F), 0.5 μg/ml hydrocortisone (group H), and A549 conditioned medium (A549 CM) (group CM) in SFD media. Seven different combinations of factors were tested to assess the efficiencies of these factors to promote differentiation. The expressions of DE- and ATII-specific markers were investigated during each differentiation step.

Results

Although both F and H (alone and in combination) promoted differentiation through ATII-like cells, the highest percentage of surfactant protein C (SP-C) expressing cells (~37%) were produced in DE-like cells treated by F+H+CM. Ultrastructural analyses also confirmed the presence of lamellar bodies (LB) in the ATII-like cells.

Conclusion

These results suggest that hydrocortisone can be a promoting factor in alveolar fate differentiation of IDE2-induced mESC-DE cells. These cells have potential for drug screening and cell-replacement therapies.

Alterations in Cellular Processes Involving Vesicular Trafficking and Implications in Drug Delivery

Endocytosis and vesicular trafficking are cellular processes that regulate numerous functions required to sustain life. From a translational perspective, they offer avenues to improve the access of therapeutic drugs across cellular barriers that separate body compartments and into diseased cells. However, the fact that many factors have the potential to alter these routes, impacting our ability to effectively exploit them, is often overlooked. Altered vesicular transport may arise from the molecular defects underlying the pathological syndrome which we aim to treat, the activity of the drugs being used, or side effects derived from the drug carriers employed. In addition, most cellular models currently available do not properly reflect key physiological parameters of the biological environment in the body, hindering translational progress. This article offers a critical overview of these topics, discussing current achievements, limitations and future perspectives on the use of vesicular transport for drug delivery applications.

The emerging risk of exposure to air pollution on cognitive decline and Alzheimer's disease - Evidence from epidemiological and animal studies

As incidence of Alzheimer's disease (AD) and other neurodegenerative diseases rise, there is increasing interest in environmental factors which may contribute to disease onset and progression. Air pollution has been known as a major health hazard for decades. While its effects on cardiopulmonary morbidity and mortality have been extensively studied, growing evidence has emerged that exposure to polluted air is associated with impaired cognitive functions at all ages and increased risk of AD and other dementias in later life; this association is particularly notable with traffic related pollutants such as nitrogen dioxide, nitrous oxide, black carbon, and small diameter airborne solids and liquids known as particulate matter. The exact mechanisms by which air pollutants mediate neurotoxicity in the central nervous system (CNS) and lead to cognitive decline and AD remain largely unknown. Studies using animal and cell culture models indicate that amyloid-beta processing, anti-oxidant defense, and inflammation are altered following the exposure to constituents of polluted air. In this review, we summarize recent evidence supporting exposure to air pollution as a risk for cognitive decline at all ages and AD at later lifetime. Additionally, we review the current body of work investigating the molecular mechanisms by which air pollutants mediate damage in the CNS. Understanding of the neurotoxic effects of air pollution and its constituents is still limited, and further studies will be essential to better understand the cellular and molecular mechanisms linking air pollution and cognitive decline.

Multi-omics analysis of ten carbon nanomaterials effects highlights cell type specific patterns of molecular regulation and adaptation

New strategies to characterize the effects of engineered nanomaterials (ENMs) based on omics technologies are emerging. However, given the intricate interplay of multiple regulatory layers, the study of a single molecular species in exposed biological systems might not allow the needed granularity to successfully identify the pathways of toxicity (PoT) and, hence, portraying adverse outcome pathways (AOPs). Moreover, the intrinsic diversity of different cell types composing the exposed organs and tissues in living organisms poses a problem when transferring in vivo experimentation into cell-based in vitro systems. To overcome these limitations, we have profiled genome-wide DNA methylation, mRNA and microRNA expression in three human cell lines representative of relevant cell types of the respiratory system, A549, BEAS-2B and THP-1, exposed to a low dose of ten carbon nanomaterials (CNMs) for 48 h. We applied advanced data integration and modelling techniques in order to build comprehensive regulatory and functional maps of the CNM effects in each cell type. We observed that different cell types respond differently to the same CNM exposure even at concentrations exerting similar phenotypic effects. Furthermore, we linked patterns of genomic and epigenomic regulation to intrinsic properties of CNM. Interestingly, DNA methylation and microRNA expression only partially explain the mechanism of action (MOA) of CNMs. Taken together, our results strongly support the implementation of approaches based on multi-omics screenings on multiple tissues/cell types, along with systems biology-based multi-variate data modelling, in order to build more accurate AOPs.

Insights in particulate matter-induced allergic airway inflammation: Focus on the epithelium

Outdoor air pollution is a major environmental health problem throughout the world. In particular, exposure to particulate matter (PM) has been associated with the development and exacerbation of several respiratory diseases, including asthma. Although the adverse health effects of PM have been demonstrated for many years, the underlying mechanisms have not been fully identified. In this review, we focus on the role of the lung epithelium and specifically highlight multiple cytokines in PM-induced respiratory responses. We describe the available literature on the topic including in vitro studies, findings in humans (ie observations in human cohorts, human controlled exposure and ex vivo studies) and in vivo animal studies. In brief, it has been shown that exposure to PM modulates the airway epithelium and promotes the production of several cytokines, including IL-1, IL-6, IL-8, IL-25, IL-33, TNF-α, TSLP and GM-CSF. Further, we propose that PM-induced type 2-promoting cytokines are important mediators in the acute and aggravating effects of PM on airway inflammation. Targeting these cytokines could therefore be a new approach in the treatment of asthma.

Air-Liquid Interface In Vitro Models for Respiratory Toxicology Research: Consensus Workshop and Recommendations

In vitro air-liquid interface (ALI) cell culture models can potentially be used to assess inhalation toxicology endpoints and are usually considered, in terms of relevancy, between classic (i.e., submerged) in vitro models and animal-based models. In some situations that need to be clearly defined, ALI methods may represent a complement or an alternative option to in vivo experimentations or classic in vitro methods. However, it is clear that many different approaches exist and that only very limited validation studies have been carried out to date. This means comparison of data from different methods is difficult and available methods are currently not suitable for use in regulatory assessments. This is despite inhalation toxicology being a priority area for many governmental organizations. In this setting, a 1-day workshop on ALI in vitro models for respiratory toxicology research was organized in Paris in March 2016 to assess the situation and to discuss what might be possible in terms of validation studies. The workshop was attended by major parties in Europe and brought together more than 60 representatives from various academic, commercial, and regulatory organizations. Following plenary, oral, and poster presentations, an expert panel was convened to lead a discussion on possible approaches to validation studies for ALI inhalation models. A series of recommendations were made and the outcomes of the workshop are reported.

The impact of nanomaterial characteristics on inhalation toxicity

During the last few decades, nanotechnology has evolved into a success story, apparent from a steadily increasing number of scientific publications as well as a large number of applications based on engineered nanomaterials (ENMs). Its widespread uses suggest a high relevance for consumers, workers and the environment, hence justifying intensive investigations into ENM-related adverse effects as a prerequisite for nano-specific regulations. In particular, the inhalation of airborne ENMs, being assumed to represent the most hazardous type of human exposure to these kinds of particles, needs to be scrutinized. Due to an increased awareness of possible health effects, which have already been seen in the case of ultrafine particles (UFPs), research and regulatory measures have set in to identify and address toxic implications following their almost ubiquitous occurrence. Although ENM properties differ from those of the respective bulk materials, the available assessment protocols are often designed for the latter. Despite the large benefit ensuing from the application of nanotechnology, many issues related to ENM behavior and adverse effects are not fully understood or should be examined anew. The traditional hypothesis that ENMs exhibit different or additional hazards due to their "nano" size has been challenged in recent years and ENM categorization according to their properties and toxicity mechanisms has been proposed instead. This review summarizes the toxicological effects of inhaled ENMs identified to date, elucidating the modes of action which provoke different mechanisms in the respiratory tract and their resulting effects. By linking particular mechanisms and adverse effects to ENM properties, grouping of ENMs based on toxicity-related properties is supposed to facilitate toxicological risk assessment. As intensive studies are still required to identify these "ENM classes", the need for alternatives to animal studies is evident and advances in cell-based test systems for pulmonary research are presented here. We hope to encourage the ongoing discussion about ENM risks and to advocate the further development and practice of suitable testing and grouping methods.

Biogenic silver nanoparticles inducing Leishmania amazonensis promastigote and amastigote death in vitro

American Cutaneous Leishmaniasis (ACL) is a zoonosis caused by Leishmania protozoa. The ACL chemotherapy available is unsatisfactory motivating researches to seek alternative treatments. In this study, we investigated the action of biogenic silver nanoparticle (AgNp-bio) obtained from Fusarium oxysporium, against Leishmania amazonensis promastigote and amastigote forms. The AgNp-bio promastigote treatment results in promastigote death leading to apoptosis-like events due an increased production of reactive oxygen species (ROS), loss of mitochondrial integrity, phosphatidylserine exposure and damage on promastigotes membrane. In L. amazonensis infected macrophages, AgNp-bio treatment was still able to reduce the percentage of infected macrophages and the amount of amastigotes per macrophage, consequently, the amount of promastigotes recovered. This leishmanicidal effect was also accompanied by a decrease in the levels of ROS and nitric oxide. By observing the ultrastructural integrity of the intracellular amastigotes, we found that the AgNp-bio treatment made a significant damage, suggesting that the compound has a direct effect on intracellular amastigotes. These results demonstrated that AgNp-bio had a direct effect against L. amazonensis forms and acted on immunomodulatory ability of infected macrophages, reducing the infection without inducing the synthesis of inflammatory mediators, which continuous stimulation can generate and aggravate leishmaniotic lesions. Overall, our findings suggest that the use of AgNp-bio stands out as a new therapeutic option to be considered for further in vivo investigations representing a possible treatment for ACL.

Relevance of Physicochemical Characterization of Nanomaterials for Understanding Nano-cellular Interactions

The manufactured nanomaterials (NMs) have specific physicochemical properties that confer unique mechanical, optical, electrical and magnetic characteristics that are beneficial for biomedical and industrial applications. However, recent studies have suggested that such specific physicochemical properties of the NMs may define nano-bio interactions thereby determining their toxic potential.One of the major concerns about NMs is the potential to induce cancer, suggested by some experimental studies, as seen for titanium dioxide nanomaterials or carbon nanotubes. To analyze in a short term the carcinogenic properties of a compound, genotoxicity assays in mammalian cell lines or animal models are frequently used. However, the investigation of the genotoxic properties of NMs has been inconclusive, up to date, since divergent results have been reported throughout the literature. While trying to understand how the NMs' characteristics may encompass increased toxicological effects that harbor uncertainties for public health, the use of correlation analysis highlights some physicochemical properties that influence the genotoxic potential of these NM.In this chapter, it is hypothesized that the different genotoxicity observed in closely related NMs may be due to subtle differences in their physicochemical characteristics. The present work provides an overview of the studies exploring the correlation between physicochemical properties of nanomaterials and their genotoxic effects in human cells, with focus on the toxicity of two groups of NMs, titanium dioxide nanomaterials and multiwalled-carbon nanotubes. It is suggested that, for tackling NMs' uncertainties, the in-depth investigation of the nano-bio interactions must be foreseen, where in vitro research must be integrated with in vivo and biomonitoring approaches, to cope with the complex dynamic behaviour of nanoscale materials.

Nanoparticles of Titanium and Zinc Oxides as Novel Agents in Tumor Treatment: a Review

Cancer has become a global problem. On all continents, a great number of people are diagnosed with this disease. In spite of the progress in medical care, cancer still ends fatal for a great number of the ill, either as a result of a late diagnosis or due to inefficiency of therapies. The majority of the tumors are resistant to drugs. Thus, the search for new, more effective therapy methods continues. Recently, nanotechnology has been attributed with big expectations in respect of the cancer fight. That interdisciplinary field of science creates nanomaterials (NMs) and nanoparticles (NPs) that can be applied, e.g., in nanomedicine. NMs and NPs are perceived as very promising in cancer therapy since they can perform as drug carriers, as well as photo- or sonosensitizers (compounds that generate the formation of reactive oxygen species as a result of either electromagnetic radiation excitation with an adequate wavelength or ultrasound activation, respectively). Consequently, two new treatment modalities, the photodynamic therapy (PDT) and the sonodynamic therapy (SDT) have been created. The attachment of ligands or antibodies to NMs or to NPs improve their selective distribution into the targeted organ or cell; hence, the therapy effectiveness can be improved. An important advantage of the targeted tumor treatment is lowering the cyto- and genotoxicity of active substance towards healthy cells. Therefore, both PDT and SDT constitute a valuable alternative to chemo- or radiotherapy. The vital role in cancer eradication is attributed to two inorganic sensitizers in their nanosized scale: titanium dioxide and zinc oxide.

Revelation of Different Nanoparticle-Uptake Behavior in Two Standard Cell Lines NIH/3T3 and A549 by Flow Cytometry and Time-Lapse Imaging

The uptake of nanomaterials into different cell types is a central pharmacological issue for the determination of nanotoxicity as well as for the development of drug delivery strategies. Most responses of the cells depend on their intracellular interactions with nanoparticles (NPs). Uptake behavior can be precisely investigated in vitro, with sensitive high throughput methods such as flow cytometry. In this study, we investigated two different standard cell lines, human lung carcinoma (A549) and mouse fibroblast (NIH/3T3) cells, regarding their uptake behavior of titanium dioxide NPs. Cells were incubated with different concentrations of TiO₂ NPs and samples were taken at certain time points to compare the uptake kinetics of both cell lines. Samples were analyzed with the help of flow cytometry by studying changes in the side and forward scattering signal. To additionally enable a detection via fluorescence, NPs were labeled with the fluorescent dye fluorescein isothiocyanate (FITC) and propidium iodide (PI). We found that NIH/3T3 cells take up the studied NPs more efficiently than A549 cells. These findings were supported by time-lapse microscopic imaging of the cells incubated with TiO₂ NPs. Our results confirm that the uptake behavior of individual cell types has to be considered before interpreting any results of nanomaterial studies.

Harmful at non-cytotoxic concentrations: SiO2-SPIONs affect surfactant metabolism and lamellar body biogenesis in A549 human alveolar epithelial cells

The pulmonary delivery of nanoparticles (NPs) is a promising approach in nanomedicine. For the efficient and safe use of inhalable NPs, understanding of NP interference with lung surfactant metabolism is needed. Lung surfactant is predominantly a phospholipid substance, synthesized in alveolar type II cells (ATII), where it is packed in special organelles, lamellar bodies (LBs). In vitro and in vivo studies have reported NPs impact on surfactant homeostasis, but this phenomenon has not yet been sufficiently examined. We showed that in ATII-like A549 human lung cancer cells, silica-coated superparamagnetic iron oxide NPs (SiO₂-SPIONs), which have a high potential in medicine, caused an increased cellular amount of acid organelles and phospholipids. In SiO₂-SPION treated cells, we observed elevated cellular quantity of multivesicular bodies (MVBs), organelles involved in LB biogenesis. In spite of the results indicating increased surfactant production, the cellular quantity of LBs was surprisingly diminished and the majority of the remaining LBs were filled with SiO₂-SPIONs. Additionally, LBs were detected inside abundant autophagic vacuoles (AVs) and obviously destined for degradation. We also observed time- and dose-dependent changes in mRNA expression for proteins involved in lipid metabolism. Our results demonstrate that non-cytotoxic concentrations of SiO₂-SPIONs interfere with surfactant metabolism and LB biogenesis, leading to disturbed ability to reduce hypophase surface tension. To ensure the safe use of NPs for pulmonary delivery, we propose that potential NP interference with LB biogenesis is obligatorily taken into account.

Air quality in the Olona Valley and in vitro human health effects

Air quality is a major point in current health policies in force globally to protect human health and ecosystems. Cardiovascular and lung diseases are the pathologies most commonly associated with air pollution and it has been estimated that exposure to particulate matters and ground-level ozone and nitric oxides caused >500.000 premature deaths in Europe. Although air quality was generally improved in the recent years, further efforts are required to reduce the impact of air pollution on humans. The present study applied a multidisciplinary approach to estimate the adverse effects on the health of the inhabitants of the Olona Valley in the north of Italy. Chemical analyses quantified the air levels of metals, dioxins, PCBs, PAHs and some macropollutants, including total, fine and coarse airborne particles. These results were used as input for the health risk assessment and in vitro bioassays were used to evaluate possible adverse effects on the respiratory tract due to the organic pollutants adsorbed on the airborne particulate matter. Critical alerts were identified from the air characterization and from the chemical-based risk assessment in view of the levels of arsenic, nickel, benzene, fine and coarse particulate matters found in the investigated zone, which can induce severe adverse effects on human health. These findings were confirmed by bioassays with A549 and BEAS-2B cells. We also used the cell transformation assay with BALB/c 3T3 cells to assess the carcinogenicity of the organic extracts of collected particles as an innovative tool to establish the possible chronic effects of inhaled pollutants. No significant changes in morphological transformation were found suggesting that, although the extracts contain compounds with proven carcinogenic potential, in our experimental conditions the levels of these pollutants were too low to induce carcinogenesis as resulted also by the chemical-based risk assessment.

Effect of cigarette smoke extract on P-glycoprotein function in primary cultured and newly developed alveolar epithelial cells

The effect of cigarette smoke extract (CSE) on P-glycoprotein (P-gp) function in the distal lung is unclear. In this study, we first examined the expression and function of P-gp and the effect of CSE in rat primary cultured alveolar epithelial cells. The expression of P-gp protein was observed in type I-like cells, but not in type II cells. In type I-like cells, rhodamine 123 (Rho123) accumulation was enhanced by various P-gp inhibitors such as verapamil and cyclosporine A. In addition, the expression of P-gp mRNAs, mdr1a and mdr1b, as well as P-gp activity increased along with the transdifferentiation. When type I-like cells were co-incubated with CSE, P-gp activity was suppressed. Next, we attempted to clarify the effect of CSE on P-gp function in human-derived cultured alveolar epithelial cells. For this purpose, we isolated an A549 clone (A549/P-gp) expressing P-gp, because P-gp expression in native A549 cells was negligible. In A549/P-gp cells, P-gp was functionally expressed, and the inhibitory effect of CSE on P-gp was observed. These results suggested that smoking would directly suppress P-gp activity, and that A549/P-gp cell line should be a useful model to further study the effect of xenobiotics on P-gp function in the alveolar epithelial cells.

A Comparative Study on the Alterations of Endocytic Pathways in Multiple Lysosomal Storage Disorders

Many cellular activities and pharmaceutical interventions involve endocytosis and delivery to lysosomes for processing. Hence, lysosomal processing defects can cause cell and tissue damage, as in lysosomal storage diseases (LSDs) characterized by lysosomal accumulation of undegraded materials. This storage causes endocytic and trafficking alterations, which exacerbate disease and hinder treatment. However, there have been no systematic studies comparing different endocytic routes in LSDs. Here, we used genetic and pharmacological models of four LSDs (type A Niemann-Pick, type C Niemann-Pick, Fabry, and Gaucher diseases) and evaluated the pinocytic and receptor-mediated activity of the clathrin-, caveolae-, and macropinocytic routes. Bulk pinocytosis was diminished in all diseases, suggesting a generic endocytic alteration linked to lysosomal storage. Fluid-phase (dextran) and ligand (transferrin) uptake via the clathrin route were lower for all LSDs. Fluid-phase and ligand (cholera toxin B) uptake via the caveolar route were both affected but less acutely in Fabry or Gaucher diseases. Epidermal growth factor-induced macropinocytosis was altered in Niemann-Pick cells but not other LSDs. Intracellular trafficking of ligands was also distorted in LSD versus wild-type cells. The extent of these endocytic alterations paralleled the level of cholesterol storage in disease cell lines. Confirming this, pharmacological induction of cholesterol storage in wild-type cells disrupted endocytosis, and model therapeutics restored uptake in proportion to their efficacy in attenuating storage. This suggests a proportional and reversible relationship between endocytosis and lipid (cholesterol) storage. By analogy, the accumulation of biological material in other diseases, or foreign material from drugs or their carriers, may cause similar deficits, warranting further investigation.

Quantifying the characteristics of particulate matters captured by urban plants using an automatic approach

It is widely accepted that urban plant leaves can capture airborne particles. Previous studies on the particle capture capacity of plant leaves have mostly focused on particle mass and/or size distribution. Fewer studies, however, have examined the particle density, and the size and shape characteristics of particles, which may have important implications for evaluating the particle capture efficiency of plants, and identifying the particle sources. In addition, the role of different vegetation types is as yet unclear. Here, we chose three species of different vegetation types, and firstly applied an object-based classification approach to automatically identify the particles from scanning electron microscope (SEM) micrographs. We then quantified the particle capture efficiency, and the major sources of particles were identified. We found (1) Rosa xanthina Lindl (shrub species) had greater retention efficiency than Broussonetia papyrifera (broadleaf species) and Pinus bungeana Zucc. (coniferous species), in terms of particle number and particle area cover. (2) 97.9% of the identified particles had diameter ≤10 μm, and 67.1% of them had diameter ≤2.5 μm. 89.8% of the particles had smooth boundaries, with 23.4% of them being nearly spherical. (3) 32.4%-74.1% of the particles were generated from bare soil and construction activities, and 15.5%-23.0% were mainly from vehicle exhaust and cooking fumes.

Configuration-dependent Presentation of Multivalent IL-15:IL-15Rα Enhances the Antigen-specific T Cell Response and Anti-tumor Immunity

Here we report a "configuration-dependent" mechanism of action for IL-15:IL-15Rα (heterodimeric IL-15 or hetIL-15) where the manner by which IL-15:IL-15Rα molecules are presented to target cells significantly affects its function as a vaccine adjuvant. Although the cellular mechanism of IL-15 trans-presentation via IL-15Rα and its importance for IL-15 function have been described, the full effect of the IL-15:IL-15Rα configuration on responding cells is not yet known. We found that trans-presenting IL-15:IL-15Rα in a multivalent fashion on the surface of antigen-encapsulating nanoparticles enhanced the ability of nanoparticle-treated dendritic cells (DCs) to stimulate antigen-specific CD8(+) T cell responses. Localization of multivalent IL-15:IL-15Rα and encapsulated antigen to the same DC led to maximal T cell responses. Strikingly, DCs incubated with IL-15:IL-15Rα-coated nanoparticles displayed higher levels of functional IL-15 on the cell surface, implicating a mechanism for nanoparticle-mediated transfer of IL-15 to the DC surface. Using artificial antigen-presenting cells to highlight the effect of IL-15 configuration on DCs, we showed that artificial antigen-presenting cells presenting IL-15:IL-15Rα increased the sensitivity and magnitude of the T cell response, whereas IL-2 enhanced the T cell response only when delivered in a paracrine fashion. Therefore, the mode of cytokine presentation (configuration) is important for optimal immune responses. We tested the effect of configuration dependence in an aggressive model of murine melanoma and demonstrated significantly delayed tumor progression induced by IL-15:IL-15Rα-coated nanoparticles in comparison with monovalent IL-15:IL-15Rα. The novel mechanism of IL-15 transfer to the surface of antigen-processing DCs may explain the enhanced potency of IL-15:IL-15Rα-coated nanoparticles for antigen delivery.

Does the crystal habit modulate the genotoxic potential of silica particles? A cytogenetic evaluation in human and murine cell lines

Crystalline silica inhaled from occupational sources has been classified by IARC as carcinogenic to humans; in contrast, for amorphous silica, epidemiological and experimental evidence remains insufficient. The genotoxicity of crystalline silica is still debated because of the inconsistency of experimental results ("variability of silica hazard"), often related to the features of the particle surfaces. We have assessed the role of crystal habit in the genotoxicity of silica powders. Pure quartz (crystalline) and vitreous silica (amorphous), sharing the same surface features, were used in an in vitro study with human pulmonary epithelial (A549) and murine macrophage (RAW264.7) cell lines, representative of occupational and environmental exposures. Genotoxicity was evaluated by the comet and micronucleus assays, and cytotoxicity by the trypan blue method. Cells were treated with silica powders for 4 and 24h. Quartz but not vitreous silica caused cell death and DNA damage in RAW264.7 cells. A549 cells were relatively resistant to both powders. Our results support the view that crystal habit per se plays a pivotal role in modulating the biological responses to silica particles.

Meteorological conditions, climate change, new emerging factors, and asthma and related allergic disorders. A statement of the World Allergy Organization

The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population.

Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges.

This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.

Interactions between nano-TiO2 and the oral cavity: impact of nanomaterial surface hydrophilicity/hydrophobicity

Titanium dioxide (TiO2) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle-cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO2 particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species.