Die Interaktion zwischen pulmonalem Surfactant und inhalierbaren Partikeln

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Cellular uptake and localization of inhaled gold nanoparticles in lungs of mice with chronic obstructive pulmonary disease

Background: Inhalative nanocarriers for local or systemic therapy are promising. Gold nanoparticles (AuNP) have been widely considered as candidate material. Knowledge about their interaction with the lungs is required, foremost their uptake by surface macrophages and epithelial cells. Diseased lungs are of specific interest, since these are the main recipients of inhalation therapy. We, therefore, used Scnn1b-transgenic (Tg) mice as a model of chronic obstructive pulmonary disease (COPD) and compared uptake and localization of inhaled AuNP in surface macrophages and lung tissue to wild-type (Wt) mice. Methods: Scnn1b-Tg and Wt mice inhaled a 21-nm AuNP aerosol for 2 h. Immediately (0 h) or 24 h thereafter, bronchoalveolar lavage (BAL) macrophages and whole lungs were prepared for stereological analysis of AuNP by electron microscopy. Results: AuNP were mainly found as singlets or small agglomerates of ≤ 100 nm diameter, at the epithelial surface and within lung-surface structures. Macrophages contained also large AuNP agglomerates (> 100 nm). At 0 h after aerosol inhalation, 69.2±4.9% AuNP were luminal, i.e. attached to the epithelial surface and 24.0±5.9% in macrophages in Scnn1b-Tg mice. In Wt mice, 35.3±32.2% AuNP were on the epithelium and 58.3±41.4% in macrophages. The percentage of luminal AuNP decreased from 0 h to 24 h in both groups. At 24 h, 15.5±4.8% AuNP were luminal, 21.4±14.2% within epithelial cells and 63.0±18.9% in macrophages in Scnn1b-Tg mice. In Wt mice, 9.5±5.0% AuNP were luminal, 2.2±1.6% within epithelial cells and 82.8±0.2% in macrophages. BAL-macrophage analysis revealed enhanced AuNP uptake in Wt animals at 0 h and in Scnn1b-Tg mice at 24 h, confirming less efficient macrophage uptake and delayed clearance of AuNP in Scnn1b-Tg mice. Conclusions: Inhaled AuNP rapidly bound to the alveolar epithelium in both Wt and Scnn1b-Tg mice. Scnn1b-Tg mice showed less efficient AuNP uptake by surface macrophages and concomitant higher particle internalization by alveolar type I epithelial cells compared to Wt mice. This likely promotes AuNP depth translocation in Scnn1b-Tg mice, including enhanced epithelial targeting. These results suggest AuNP nanocarrier delivery as successful strategy for therapeutic targeting of alveolar epithelial cells and macrophages in COPD

Surfactant Protein D modulates allergen particle uptake and inflammatory response in a human epithelial airway model

<p>Abstract</p> <p>Background</p> <p>Allergen-containing subpollen particles (SPP) are released from whole plant pollen upon contact with water or even high humidity. Because of their size SPP can preferentially reach the lower airways where they come into contact with surfactant protein (SP)-D. The aim of the present study was to investigate the influence of SP-D in a complex three-dimensional human epithelial airway model, which simulates the most important barrier functions of the epithelial airway. The uptake of SPP as well as the secretion of pro-inflammatory cytokines was investigated.</p> <p>Methods</p> <p>SPP were isolated from timothy grass and subsequently fluorescently labeled. A human epithelial airway model was built by using human Type II-pneumocyte like cells (A549 cells), human monocyte derived macrophages as well as human monocyte derived dendritic cells. The epithelial cell model was incubated with SPP in the presence and absence of surfactant protein D. Particle uptake was evaluated by confocal microscopy and advanced computer-controlled analysis. Finally, human primary CD4⁺T-Cells were added to the epithelial airway model and soluble mediators were measured by enzyme linked immunosorbent assay or bead array.</p> <p>Results</p> <p>SPP were taken up by epithelial cells, macrophages, and dendritic cells. This uptake coincided with secretion of pro-inflammatory cytokines and chemokines. SP-D modulated the uptake of SPP in a cell type specific way (e.g. increased number of macrophages and epithelial cells, which participated in allergen particle uptake) and led to a decreased secretion of pro-inflammatory cytokines.</p> <p>Conclusion</p> <p>These results display a possible mechanism of how SP-D can modulate the inflammatory response to inhaled allergen.</p

A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of −20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability) of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver nanoparticles dissolve in water in the presence of oxygen. In addition, in biological media (i.e., in the presence of proteins) the surface of silver nanoparticles is rapidly coated by a protein corona that influences their physicochemical and biological properties including cellular uptake. Silver nanoparticles are taken up by cell-type specific endocytosis pathways as demonstrated for hMSC, primary T-cells, primary monocytes, and astrocytes. A visualization of particles inside cells is possible by X-ray microscopy, fluorescence microscopy, and combined FIB/SEM analysis. By staining organelles, their localization inside the cell can be additionally determined. While primary brain astrocytes are shown to be fairly tolerant toward silver nanoparticles, silver nanoparticles induce the formation of DNA double-strand-breaks (DSB) and lead to chromosomal aberrations and sister-chromatid exchanges in Chinese hamster fibroblast cell lines (CHO9, K1, V79B). An exposure of rats to silver nanoparticles in vivo induced a moderate pulmonary toxicity, however, only at rather high concentrations. The same was found in precision-cut lung slices of rats in which silver nanoparticles remained mainly at the tissue surface. In a human 3D triple-cell culture model consisting of three cell types (alveolar epithelial cells, macrophages, and dendritic cells), adverse effects were also only found at high silver concentrations. The silver ions that are released from silver nanoparticles may be harmful to skin with disrupted barrier (e.g., wounds) and induce oxidative stress in skin cells (HaCaT). In conclusion, the data obtained on the effects of this well-defined type of silver nanoparticles on various biological systems clearly demonstrate that cell-type specific properties as well as experimental conditions determine the biocompatibility of and the cellular responses to an exposure with silver nanoparticles

Size and surface charge of gold nanoparticles determine absorption across intestinal barriers and accumulation in secondary target organs after oral administration

It is of urgent need to identify the exact physico-chemical characteristics which allow maximum uptake and accumulation in secondary target organs of nanoparticulate drug delivery systems after oral ingestion. We administered radiolabelled gold nanoparticles in different sizes (1.4-200 nm) with negative surface charge and 2.8 nm nanoparticles with opposite surface charges by intra-oesophageal instillation into healthy adult female rats. The quantitative amount of the particles in organs, tissues and excrements was measured after 24 h by gamma-spectroscopy. The highest accumulation in secondary organs was mostly found for 1.4 nm particles; the negatively charged particles were accumulated mostly more than positively charged particles. Importantly, 18 nm particles show a higher accumulation in brain and heart compared to other sized particles. No general rule accumulation can be made so far. Therefore, specialized drug delivery systems via the oral route have to be individually designed, depending on the respective target organ

The influence of pulmonary surfactant on nanoparticulate drug delivery systems

The pulmonary route is very attractive for drug delivery by inhalation. In this regard, nanoparticulate drug delivery systems, designed as multifunctional engineered nanoparticles, are very promising since they combine several opportunities like a rather uniform distribution of drug dose among all ventilated alveoli allowing for uniform cellular drug internalization. However, although the field of nanomedicine offers multiple opportunities, it still is in its infancy and the research has to proceed in order to obtain a specific targeting of the drug combined with minimum side effects. If inhaled nanoparticulate drug delivery systems are deposited on the pulmonary surfactant, they come into contact with phospholipids and surfactant proteins. It is highly likely that the interaction of nanoparticulate drug delivery systems with surfactant phospholipids and proteins will be able to mediate/modulate the further fate of this specific drug delivery system. In the present comment, we discuss the potential interactions of nanoparticulate drug delivery systems with pulmonary surfactant as well as the potential consequences of this interaction

Cytotoxic and proinflammatory effects of PVP-coated silver nanoparticles after intratracheal instillation in rats

Silver nanoparticles (AgNP) are among the most promising nanomaterials, and their usage in medical applications and consumer products is growing rapidly. To evaluate possible adverse health effects, especially to the lungs, the current study focused on the cytotoxic and proinflammatory effects of AgNP after the intratracheal instillation in rats. Monodisperse, PVP-coated AgNP (70 nm) showing little agglomeration in aqueous suspension were instilled intratracheally. After 24 hours, the lungs were lavaged, and lactate dehydrogenase (LDH), total protein, and cytokine levels as well as total and differential cell counts were measured in the bronchoalveolar lavage fluid (BALF). Instillation of 50 µg PVP-AgNP did not result in elevated LDH, total protein, or cytokine levels in BALF compared to the control, whereas instillation of 250 µg PVP-AgNP caused a significant increase in LDH (1.9-fold) and total protein (1.3-fold) levels as well as in neutrophil numbers (60-fold) of BALF. Furthermore, while there was no change in BALF cytokine levels after the instillation of 50 µg PVP-AgNP, instillation of 250 µg PVP-AgNP resulted in significantly increased levels of seven out of eleven measured cytokines. These finding suggest that exposure to inhaled AgNP can induce moderate pulmonary toxicity, but only at rather high concentrations

Age-Dependent Rat Lung Deposition Patterns of Inhaled 20 Nanometer Gold Nanoparticles and their Quantitative Biokinetics in Adult Rats

The increasing use of gold nanoparticles leads to a possible increase of exposure by inhalation. Therefore, we have studied the deposition patterns of inhaled 20 nm gold nanoparticles (AuNP) in 7-90 day old rats and their biokinetics in 60 day old ones. Wistar-Kyoto rats inhaled intratracheally 20 nm Au-195-radiolabeled AuNP by negative pressure ventilation over 2 h. Immediately afterward lungs were excised, inflated and microwave dried. AuNP deposition was analyzed by single-photon emission computed tomography, computed-tomography and autoradiography. Completely balanced, quantitative biodistributions in major organs and all body tissues and total excretion were analyzed from 1 h to 28 d after inhalation. Intratracheal inhalation caused AuNP deposition predominately in the caudal lungs, independent of age. About 30% AuNP were deposited on airway epithelia and rapidly cleared by mucociliary clearance. About 80% of AuNP deposited in alveoli was relocated from the epithelium into the interstitium within 24 h and was inaccessible to broncho-alveolar lavage. During interstitial long-term retention, re-entrainment within macrophages back onto the lung epithelium and to the larynx and gastrointestinal tract (GIT) dominated AuNP clearance (rate 0.03 d(-1)) In contrast, AuNP-translocation across the air-blood barrier was much smaller leading to persistent retention in secondary organs and tissues in the ranking order liver &gt; soft issue &gt; spleen &gt; kidneys &gt; skeleton &gt; blood &gt; uterus &gt; heart &gt; brain. The age independent, inhomogeneous AuNP deposition was probably caused by the negative pressure ventilation. Long-term AuNP clearance was dominated by macrophage-mediated transport from the interstitium to the larynx and GIT. Translocation across the rat air blood barrier appeared to be similar to that of humans for similar sized AuNP