Characterization of mannose-binding lectin (MBL) variants by allele-specific sequencing of MBL2 and determination of serum MBL protein levels

Mannose-binding lectin (MBL) is a major component of the lectin pathway of complement activation. High and low MBL levels have been associated with susceptibility and severity of a variety of infectious and autoimmune diseases. Several single-nucleotide polymorphisms (SNPs) in the promoter region and exon 1 of the MBL2 gene are responsible for variations in serum MBL levels. We developed a sequence-based typing method for allele-specific MBL2 genotyping and measured serum MBL protein levels in 24 German blood donors. We identified the common MBL2 haplotypes including five promoter polymorphisms in linkage with the Q allele and correlated serum MBL levels with the respective genotypes. The genotyping method presented here could provide a basis for confirmatory studies in larger cohorts.

Distribution pattern of inhaled ultrafine gold particles in the rat lung

The role of alveolar macrophages in the fate of ultrafine particles in the lung was investigated. Male Wistar-Kyoto rats were exposed to ultrafine gold particles, generated by a spark generator, for 6 h at a concentration of 88 microg/m3 (4 x 10(6)/cm3, 16 nm modal mobility diameter). Up to 7 days, the animals were serially sacrificed, and lavaged cells and lung tissues were examined by transmission electron microscopy. The gold concentration/content in the lung, lavage fluid, and blood was estimated by inductively coupled plasma-mass spectrometry. Gold particles used were spherical and electron dense with diameters of 5-8 nm. The particles were individual or slightly agglomerated. By inductively coupled plasma-mass spectrometry analysis of the lung, 1945 +/- 57 ng (mean +/- SD) and 1512 +/- 184 ng of gold were detected on day 0 and on day 7, respectively, indicating that a large portion of the deposited gold particles was retained in the lung tissue. In the lavage fluid, 573 +/- 67 ng and 96 +/- 29 ng were found on day 0 and day 7, respectively, which means that 29% and 6% of the retained gold particles were lavageable on these days. A low but significant increase of gold (0.03 to 0.06% of lung concentration) was found in the blood. Small vesicles containing gold particles were found in the cytoplasm of alveolar macrophages. In the alveolar septum, the gold particles were enclosed in vesicles observed in the cytoplasm of alveolar type I epithelial cells. These results indicate that inhaled ultrafine gold particles in alveolar macrophages and type I epithelial cells are processed by endocytotic pathways, though the uptake of the gold particles by alveolar macrophages is limited. To a low degree, systemic particle translocation took place.

Aerosol-derived airway morphometry (ADAM) in patients with lung emphysema diagnosed by computed tomography--reproducibility, diagnostic information and modelling

Gravitational deposition of monodisperse particles can be used to determine effective airway diameter (EAD). The aim of our study was to assess intraindividual variability of EAD in healthy subjects and patients with emphysema, to compare EAD in patients with different degree and type of emphysema, and to evaluate whether parametric or model analysis would improve the results. EAD was measured vs volumetric lung depth (LD) in 11 healthy subjects (FEV subset1 107%pred) and 41 patients with emphysema (FEV subset1 60%pred; 8/9/24 mild/moderate/severe, 18/7/16 centriacinar/panacinar/bullous according to HRCT). Repeated measurements in LDs of 6-30% showed coefficients of variation of 7.0-10.4% in healthy subjects and 8.3-11.9% in emphysema. Average EAD in 10-16% LD was increased in emphysema, in particular moderate and severe (p<0.05, each). The slope of EAD in 10-16% LD differed between healthy subjects and emphysema, especially bullous and centriacinar. Patients with severe emphysema also showed a different slope compared to mild emphysema and controls. The parameters of the power function used for data fitting also showed differences between controls and emphysema, as well as between centriacinar vs panacinar and bullous emphysema. In a three-compartment lung model only the diameter of the intermediate compartment was enlarged in emphysema. We conclude that in using aerosol-derived airway morphometry, reproducibility of repeated measurements is acceptable. Average values and slopes of the EAD curve, as well as a power function for data fitting, were sensitive in the detection of type and severity of emphysema. In contrast, application of a lung model did not improve the results.

Dose-controlled exposure of A549 epithelial cells at the air-liquid interface to airborne ultrafine carbonaceous particles

The geometry of commercially available perfusion chambers designed for harbouring three membrane-based cell cultures was modified for reliable and dose-controlled air-liquid interface (ALI) exposures. Confluent A549 epithelial cells grown on membranes were integrated in the chamber system and supplied with medium from the chamber bottom. Cell viability was not impaired by the conditions of ALI exposure without particles. Expression of the inflammatory cytokines interleukin 6 and interleukin 8 by A549 cells during ALI exposure to filtered air for 6h and subsequent stimulation with tumor necrosis factor was not altered compared to submersed controls, indicating that the cells maintained their functional integrity. Ultrafine carbonaceous model particles with a count median mobility diameter of about 95+/-5 nm were produced by spark discharge at a stable concentration of about 2 x 10(6) cm(-3) and continuously monitored for accurate determination of the exposure dose. Delivery to the ALI exposure system yielded a homogeneous particle deposition over the membranes with a deposition efficiency of 2%. Mid dose exposure of A549 cells to this aerosol for 6h yielded a total particle deposition of (2.6+/-0.4) x 10(8) cm(-2) corresponding to (87+/-23) ng cm(-2). The 2.7-fold (p < or = 0.05) increased transcription of heme oxygenase-1 indicated a sensitive antioxidant and stress response, while cell viability did not reveal a toxic mechanism.

Instillation of six different ultrafine carbon particles indicates a surface area threshold dose for acute lung inflammation in mice

Increased levels of particulate air pollution are associated with increased respiratory and cardiovascular mortality and morbidity. Some epidemiologic and toxicologic research suggests ultrafine particles (UFPs) (< 100 nm) to be more harmful per unit mass than larger particles. Our study was aimed at a quantitative comparison of acute adverse effects of different types of carbonaceous UFPs at a dose range that causes a moderate inflammatory response in lungs. We used six different particle types (primary particle size 10-50 nm, specific surface area 30-800 m2/g, and organic content 1-20%): PrintexG, Printex90, flame soot particles with different organic content (SootL, SootH), spark-generated ultrafine carbon particles (ufCP), and the reference diesel exhaust particles (DEP) SRM1650a. Mice were instilled with 5, 20, and 50 microg of each particle type, and bronchoalveolar lavage was analyzed 24 hr after instillation for inflammatory cells and the level of proinflammatory cytokines. At respective mass-doses, particle-caused detrimental effects ranked in the following order: ufCP > SootL > or = SootH > Printex90 > PrintexG > DEP. Relating the inflammatory effects to the particle characteristics--organic content, primary particle size, or specific surface area--demonstrates the most obvious dose response for particle surface area. Our study suggests that the surface area measurement developed by Brunauer, Emmett, and Teller is a valuable reference unit for the assessment of causative health effects for carbonaceous UFPs. Additionally, we demonstrated the existence of a threshold for the particle surface area at an instilled dose of approximately 20 cm2, below which no acute proinflammatory responses could be detected in mice.

Mucociliary and long-term particle clearance in airways of patients with immotile cilia

Spherical monodisperse ferromagnetic iron oxide particles of 1.9 μm geometric and 4.2 μm aerodynamic diameter were inhaled by seven patients with primary ciliary dyskinesia (PCD) using the shallow bolus technique, and compared to 13 healthy non-smokers (NS) from a previous study. The bolus penetration front depth was limiting to the phase1 dead space volume. In PCD patients deposition was 58+/-8 % after 8 s breath holding time. Particle retention was measured by the magnetopneumographic method over a period of nine months. Particle clearance from the airways showed a fast and a slow phase. In PCD patients airway clearance was retarded and prolonged, 42+/-12 % followed the fast phase with a mean half time of 16.8+/-8.6 hours. The remaining fraction was cleared slowly with a half time of 121+/-25 days. In healthy NS 49+/-9 % of particles were cleared in the fast phase with a mean half time of 3.0+/-1.6 hours, characteristic of an intact mucociliary clearance. There was no difference in the slow clearance phase between PCD patients and healthy NS. Despite non-functioning cilia the effectiveness of airway clearance in PCD patients is comparable to healthy NS, with a prolonged kinetics of one week, which may primarily reflect the effectiveness of cough clearance. This prolonged airway clearance allows longer residence times of bacteria and viruses in the airways and may be one reason for increased frequency of infections in PCD patients.

Ultrafine particles cross cellular membranes by nonphagocytic mechanisms in lungs and in cultured cells

High concentrations of airborne particles have been associated with increased pulmonary and cardiovascular mortality, with indications of a specific toxicologic role for ultrafine particles (UFPs; particles < 0.1 microm). Within hours after the respiratory system is exposed to UFPs, the UFPs may appear in many compartments of the body, including the liver, heart, and nervous system. To date, the mechanisms by which UFPs penetrate boundary membranes and the distribution of UFPs within tissue compartments of their primary and secondary target organs are largely unknown. We combined different experimental approaches to study the distribution of UFPs in lungs and their uptake by cells. In the in vivo experiments, rats inhaled an ultrafine titanium dioxide aerosol of 22 nm count median diameter. The intrapulmonary distribution of particles was analyzed 1 hr or 24 hr after the end of exposure, using energy-filtering transmission electron microscopy for elemental microanalysis of individual particles. In an in vitro study, we exposed pulmonary macrophages and red blood cells to fluorescent polystyrene microspheres (1, 0.2, and 0.078 microm) and assessed particle uptake by confocal laser scanning microscopy. Inhaled ultrafine titanium dioxide particles were found on the luminal side of airways and alveoli, in all major lung tissue compartments and cells, and within capillaries. Particle uptake in vitro into cells did not occur by any of the expected endocytic processes, but rather by diffusion or adhesive interactions. Particles within cells are not membrane bound and hence have direct access to intracellular proteins, organelles, and DNA, which may greatly enhance their toxic potential.

Deposition of inhaled particles in the human respiratory tract and consequences for regional targeting in respiratory drug delivery

Particle behavior in the human respiratory tract is well understood and can be used to (1) estimate particle deposition in all regions of the respiratory tract for any aerosol respired at any pattern, and (2) optimize targeting of all regions of the respiratory tract in respiratory drug delivery. Extrathoracic and alveolar regions can effectively be targeted with mono- and polydisperse aerosols respired steadily. Effective targeting of the bronchial region can only be achieved with bolus inhalations. When particles are suspended in a gas heavier than air, targeting the alveolar region can be enhanced.

Oxidative stress and lipid mediators induced in alveolar macrophages by ultrafine particles

In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the capacity of particles to oxidize methionine in a cell-free in vitro system for determination of their innate oxidative potential and by alveolar macrophages (AMs) to determine production of arachidonic acid (AA), including formation of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), reactive oxygen species (ROS), and oxidative stress marker 8-isoprostane. EC exhibiting high oxidative potential induced generation of AA, PGE2, LTB4, and 8-isoprostane in canine and human AMs. Printex 90, Printex G, and DEP, showing low oxidative capacity, still induced formation of AA and PGE2, but not that of LTB4 or 8-isoprostane. Aging of EC lowered oxidative potential while still inducing production of AA and PGE2 but not that of LTB4 and 8-isoprostane. Cellular ROS production was stimulated by all particles independent of oxidative potential. Particle-induced formation of AA metabolites and ROS was dependent on mitogen-activated protein kinase kinase 1 activation of cytosolic phospholipase A2 (cPLA2) as shown by inhibitor studies. In conclusion, cPLA2, PGE2, and ROS formation was activated by all particle types, whereas LTB4 production and 8-isoprostane were strongly dependent on particles' oxidative potential. Physical and chemical parameters of particle surface correlated with oxidative potential and stimulation of AM PGE2 and 8-isoprostane production.

Genomewide Linkage Analysis Identifies Novel Genetic Loci for Lung Function in Mice

RATIONALE

Pulmonary function, including lung volumes and compliance, may be genetically determined, but few genetic polymorphisms have been identified that control these traits. We used an experimental approach and performed the first whole genome scan for pulmonary function in mice.

OBJECTIVES AND METHODS

To identify novel chromosomal regions contributing to lung function, quantitative trait locus linkage analysis was applied in N(2) backcross and F(2) intercross mice derived from two inbred strains-C3H/HeJ and JF1/Msf-with extremely divergent phenotypes.

MAIN RESULTS

Significant linkages to total lung capacity with LOD (logarithm of the odds) scores up to 6.0 were detected on chromosomes 15 and 17, to dead space volume and lung compliance on chromosomes 5 and 15 (LOD scores higher than 4.0), to lung compliance also on chromosome 19 (LOD score of 5.8), and to diffusing capacity on chromosomes 15 and 17 (LOD scores up to 5.0). The region of interest on chromosome 17 near D17Mit133 contains a syntenic region to human chromosome 6q27, which was recently identified to be linked to lung function in humans. The identified intervals harbor valuable candidate genes, such as the relaxin1 and transforming growth factor beta receptor 3 gene, which revealed missense polymorphisms between the parental strains.

CONCLUSION

The study provides evidence for linkage of different measures of lung function on murine chromosomes 5, 15, 17, and 19 and suggests novel candidate genes that may also affect the expression of human pulmonary function.

Cardiovascular responses in unrestrained WKY rats to inhaled ultrafine carbon particles

Based on epidemiologic observations, the issue of adverse health effects of inhaled ultrafine particles (UFP) is currently under intensive discussion. We therefore examined cardiovascular effects of UFP in a controlled animal exposure on young, healthy WKY rats. Short-term exposure (24 h) to carbon UFPs (38 nm, 180 microg m (-3)), generated by spark discharging, induced a mild but consistent increase in heart rate (18 bpm, 4.8%), which was associated with a significant decrease in heart-rate variability during particle inhalation. The timing and the transient character of these responses point to a particle induced alteration of cardiac autonomic balance, mediated by a pulmonary receptor activation. After 24 h of inhalation exposure, bronchoalveolar lavage revealed significant but low-grade pulmonary inflammation (clean air 1.9% vs. UFPs 6.9% polymorphonuclear cells) and on histopathology sporadic accumulation of particle-laden macrophages was found in the alveolar region. There was no evidence of an inflammation-mediated increase in blood coagulability, as UFP inhalation did not induce any significant changes in plasma fibrinogen or factor VIIa levels and there were no prothrombotic changes in the lung or the heart at both the protein and mRNA level. Histological analysis revealed no signs of cardiac inflammation or cardiomyopathy. This study therefore provides toxicological evidence for UFP-associated pulmonary and cardiac effects in healthy rats. Our findings suggest that the observed changes are mediated by an altered sympatho-vagal balance in response to UFP inhalation, but do not support the concept of an inflammation-mediated prothrombotic state by UFP.

Labeled carbon dioxide (C18O2): an indicator gas for phase II in expirograms

Carbon dioxide labeled with 18O (C18O2) was used as a tracer gas for single-breath measurements in six anesthetized, mechanically ventilated beagle dogs. C18O2 is taken up quasi-instantaneously in the gas-exchanging region of the lungs but much less so in the conducting airways. Its use allows a clear separation of phase II in an expirogram even from diseased individuals and excludes the influence of alveolar concentration differences. Phase II of a C18O2 expirogram mathematically corresponds to the cumulative distribution of bronchial pathways to be traversed completely in the course of exhalation. The derivative of this cumulative distribution with respect to respired volume was submitted to a power moment analysis to characterize volumetric mean (position), standard deviation (broadness), and skewness (asymmetry) of phase II. Position is an estimate of dead space volume, whereas broadness and skewness are measures of the range and asymmetry of functional airway pathway lengths. The effects of changing ventilatory patterns and of changes in airway size (via carbachol-induced bronchoconstriction) were studied. Increasing inspiratory or expiratory flow rates or tidal volume had only minor influence on position and shape of phase II. With the introduction of a postinspiratory breath hold, phase II was continually shifted toward the airway opening (maximum 45% at 16 s) and became steeper by up to 16%, whereas skewness showed a biphasic response with a moderate decrease at short breath holding and a significant increase at longer breath holds. Stepwise bronchoconstriction decreased position up to 45 ± 2% and broadness of phase II up to 43 ± 4%, whereas skewness was increased up to twofold at high-carbachol concentrations. Under all circumstances, position of phase II by power moment analysis and dead space volume by the Fowler technique agreed closely in our healthy dogs. Overall, power moment analysis provides a more comprehensive view on phase II of single-breath expirograms than conventional dead space volume determinations and may be useful for respiratory physiology studies as well as for the study of diseased lungs.

Fate and toxic effects of inhaled ultrafine cadmium oxide particles in the rat lung

Female Fischer 344 rats were exposed to ultrafine cadmium oxide particles, generated by spark discharging, for 6 h at a concentration of 70 microg Cd/m(3) (1 x 10(6)/cm(3)) (40 nm modal diameter). Lung morphology and quantification of Cd content/concentration by inductively coupled plasma (ICP)-mass spectrometry were performed on days 0, 1, 4, and 7 after exposure. Cd content in the lung on day 0 was 0.53 +/- 0.12 microg/lung, corresponding to 19% of the estimated total inhaled cumulative dose, and the amount remained constant throughout the study. In the liver no significant increase of Cd content was found up to 4 days. A slight but statistically significant increase was observed in the liver on day 7. We found neither exposure-related morphological changes of lungs nor inflammatory responses in lavaged cells. Another group of rats were exposed to a higher concentration of ultrafine CdO particles (550 microg Cd/m(3) for 6 h, 51 nm modal diameter). The rats were sacrificed immediately and 1 day after exposure. The lavage study performed on day 0 showed an increase in the percentage of neutrophils. Multifocal alveolar inflammation was seen histologically on day 0 and day 1. Although the Cd content in the lung was comparable between day 0 and day 1 (3.9 microg/lung), significant elevation of Cd levels in the liver and kidneys was observed on both days. Two of 4 rats examined on day 0 showed elevation of blood cadmium, indicating systemic translocation of a fraction of deposited Cd from the lung in this group. These results and comparison with reported data using fine CdO particles indicate that inhalation of ultrafine CdO particles results in efficient deposition in the rat lung. With regard to the deposition dose, adverse health effects of ultrafine CdO and fine CdO appear to be comparable. Apparent systemic translocation of Cd took place only in animals exposed to a high concentration that induced lung injury.

Mucociliary and long-term particle clearance in the airways of healthy nonsmoker subjects

Spherical monodisperse ferromagnetic iron oxide particles of 1.9-microm geometric and 4.2-microm aerodynamic diameter were inhaled by 13 healthy nonsmoking subjects using the shallow bolus technique. The bolus width was 100 ml, and the penetration front depth was 150 +/- 27 ml. The mean flow rate during inhalation and exhalation was 250 ml/s. The Fowler dead space and the phase 1 dead space of the airways were 282 +/- 49 and 164 +/- 34 ml, respectively. Deposition was below 20% without breath holding and 51 +/- 8% after an 8-s breath-holding time. We attempted to confine the bolus deposition to the bronchial airways by limiting the bolus front depth to the phase 1 dead space volume. Particle retention was measured by the magnetopneumographic method over a period of 9 mo. Particle clearance from the airways showed a fast and a slow phase; 49 +/- 9% followed the fast phase with a mean half-time of 3.0 +/- 1.6 h and characterized the mucociliary clearance. The remaining fraction was cleared slowly with a half-time of 109 +/- 78 days. The slow clearance phase was comparable to clearance measurements from the lung periphery of healthy nonsmokers, which allowed macrophage-dependent clearance mechanisms of the slow cleared fraction to be taken into account. Despite the fact that part of the slowly cleared particles may originate from peripheral deposition, the data demonstrate that mucociliary clearance does not remove all particles deposited in the airways and that a significant fraction undergoes long-term retention mechanisms, the origin of which is still under discussion.

Long-term clearance kinetics of inhaled ultrafine insoluble iridium particles from the rat lung, including transient translocation into secondary organs

Recently it was speculated that ultrafine particles (UFP) may translocate from deposition sites in the lungs to systemic circulation and whether long-term clearance differs between ultrafine and micrometer-sized particles. We have studied lung retention and clearance kinetics in 12 healthy male adult WKY rats up to 6 mo after an inhalation of (192)Ir-radiolabeled, insoluble, ultrafine 15- to 20-nm iridium particles. Whole-body retention was followed by external gamma counting, and particle clearance kinetics were determined by excretion radioanalysis. Four rats each were sacrificed after 3 wk and 2 and 6 mo; all organs as well as tissues and the carcass were radioanalyzed to balance the entire deposited radioactivity of the particles. The most prominent fraction was retained in the lungs at each time point of sacrifice (26%, 15%, 6%, respectively), and clearance out of the body was solely via excretion. Extrapulmonary particle uptake did not continue to increase but decreased with time in liver, spleen, heart, and brain when compared to previous data obtained during the first 7 days after inhalation (Kreyling et al., 2002). UFP long-term lung retention derived from whole-body measurements was comparable to previously reported data using insoluble micrometer-sized particles (Bellmann et al., 1994; Lehnert et al., 1989). In addition, differential analysis including daily excretion data revealed a pattern of fractional particle clearance rate of the ultrafine iridium particles similar to that of micrometer-sized particles reported by Snipes et al. (1983) and Bailey et al. (1985).

Diesel exhaust particles increase LPS-stimulated COX-2 expression and PGE2production in human monocytes

Little is known about health effects of ultrafine particles (UFP) found in ambient air, but much of their action may be on cells of the lung, including cells of the monocyte/macrophage lineage. We have analyzed the effects of diesel exhaust particles (DEP; SRM1650a) on human monocytes in vitro. DEP, on their own, had little effect on cyclooxygenase (COX)-2 gene expression in the Mono Mac 6 cell line. However, when cells were preincubated with DEP for 1 h, then stimulation with the Toll-like receptor 4 (TLR4) ligand lipopolysaccharide (LPS) induced an up-to fourfold-higher production of COX-2 mRNA with an average twofold increase. This costimulatory effect of DEP led to enhanced production of COX-2 protein and to increased release of prostaglandin E(2) (PGE(2)). The effect was specific in that tumor necrosis factor gene expression was not enhanced by DEP costimulation. Furthermore, costimulation with the TLR2 ligand Pam3Cys also led to enhanced COX-2 mRNA. DEP and LPS showed similar effects on COX-2 mRNA in primary blood mononuclear cells, in highly purified CD14-positive monocytes, and in monocyte-derived macrophages. Our data suggest that UFP such as DEP may exert anti-inflammatory effects mediated by enhanced PGE(2) production.

Pulmonary and systemic effects of short-term inhalation exposure to ultrafine carbon black particles

While environmental particles are associated with mortality and morbidity related to pulmonary and cardiovascular (CV) disease, the mechanisms involved in CV health effects are not known. Changes in systemic clotting factors have been associated with pulmonary inflammation. We hypothesized that inhaled ultrafine particles result in an inflammatory response which may stimulate systemic clotting factor release. Adult male Wistar rats were exposed to either fine or ultrafine carbon black (CB) for 7 h. The attained total suspended particle concentrations were 1.66 mg/m(3) for ultrafine CB and 1.40 mg/m(3) for fine CB. Particle concentration of ultrafine particles was more than 10 times greater than that of fine particles and the count median aerodynamic diameter averaged 114 nm for the ultrafine and 268 nm for the fine carbon particles. Data were collected immediately, 16 and 48 h following exposure. Only ultrafine CB caused an increase in total bronchoalveolar lavage (BAL) leukocytes, whereas both fine (2-fold) and ultrafine (4-fold) carbon particles caused an increase in BAL neutrophils at 16 h postexposure. Exposure to the ultrafine, but not fine, carbon was also associated with significant increases in the total numbers of blood leukocytes. Plasma fibrinogen, factor VII and von Willebrand factor (vWF) were unaffected by particle treatments as was plasma Trolox equivalent antioxidant status (TEAC). Macrophage inflammatory protein-2 mRNA was significantly increased in BAL cells 48 h following exposure to ultrafine CB. The data show that there is a small but consistent significant proinflammatory effect of this exposure to ultrafine particles that is greater than the effect of the same exposure to fine CB.

Lung volume is a determinant of aerosol bolus dispersion

The technique of inhaling a small volume element labeled with particles ("aerosol bolus") can be used to assess convective gas mixing in the lung. While a bolus undergoes mixing in the lung, particles are dispersed in an increasing volume of the respired air. However, determining factors of bolus dispersion are not yet completely understood. The present study tested the hypothesis that bolus dispersion is related, among others, to the total volume in which the bolus is allowed to mix--i.e., to the individual lung size. Bolus dispersion was measured in 32 anesthetized, mechanically ventilated dogs with total lung capacities (TLCs) of 1.1-2.5 L. Six-milliliter aerosol boluses were introduced at various preselected time-points during inspiration to probe different volumetric lung depths. Dispersion (SD) was determined by moment analysis of particle concentrations in the expired air. We found linear correlations between SD at a given lung depth and the individual end-inspiratory lung volume (V(L)). The relationship was tightest for boluses inhaled deepest into the lungs: SD(40) = 0.068 V(L) - 1.77, r(2) = 0.59. Normalizing SD to V(L) abolished this dependency and resulted in a considerable reduction of inter-individual variability as compared to the uncorrected measurements. These data indicate that lung size influences measurements of bolus dispersion. It therefore appears reasonable to apply a normalization procedure before interpreting the data. Apart from a reduction in measurement variability, this should help to separate the effects on bolus dispersion of altered lung volumes and altered mixing processes in diseased lungs.

Effect of magnetic bead agglomeration on cytomagnetometric measurements

Magnetic twisting cytometry (MTC) is a novel tool to measure cytoskeleton-associated cell functions by the use of ferromagnetic microbeads. Magnetic beads are either incorporated by living cells by phagocytic processes or attached to integrin receptors to the cell membrane. The magnetic beads are magnetized and aligned in a strong magnetic field pulse. The application of twisting forces allows to investigate mechanical properties (stiffness, viscoelasticity) of the cytoskeleton of living cells by analyzing the magnetic cell field. Incorporated magnetic beads undergo intracellular transport processes, which result in a loss of particle alignment and in a decay of the remanent magnetic cell field. This process, called relaxation, depends on the mechanical cytoskeletal properties and can directly visualize the intracellular energy of cellular transport processes. The preparation of spherical monodisperse ferromagnetic beads made it possible to understand the above-described processes using mathematical models. Experimental conditions with many magnetic particles per cell enhances the formation of aggregates because of the attractive forces between magnetic spheres, resulting in a change of magnetic properties and of hydrodynamic behavior. Due to mutual magnetization, the remanent magnetic moment of an aggregate is stronger compared to the same number of single particles. This implies a higher cell field. Additionally the relaxation is retarded because of the change in shape factor and in volume, which also implies a faulty estimation of intracellular transport energy. Magnetic particle twisting is less influenced. In summary, valuable cytomagnetometric measurements have to be done with less than one particle per macrophage to ensure low probability of multiple particles per cell.

Sulfur-related air pollutants induce the generation of platelet-activating factor, 5-lipoxygenase- and cyclooxygenase-products in canine alveolar macrophages via activation of phospholipases A2

Recent studies have shown that long-term in vivo exposure of dogs to neutral sulfur(IV)/sulfite aerosols induces mild inflammatory reactions, whereas the combination of neutral sulfite with acidic sulfur(VI)/sulfate aerosols evokes less pronounced effects. To understand underlying mechanisms, we studied in vitro the role of lipid mediators in the responses of alveolar macrophages (AMs) to sulfur-related compounds under neutral (pH 7) or moderate acidic (pH 6) conditions. Canine AMs incubated with sulfite at pH 7 released threefold higher amounts of platelet-activating factor than control (P < 0.005). Generation of arachidonic acid, leukotriene B4, 5-hydroxy-eicosatetraenoic acid, prostaglandin E2, thromboxane B2 and 12-hydroxyheptadecatrienoic acid increased twofold (P < 0.0005). However, these metabolites remained unchanged following incubation of AMs with sulfite at pH 6 or with sulfate at pH 7 or pH 6. Mediator release by sulfite-treated AMs at pH 7 stimulated respiratory burst activity of neutrophils. Inhibition of MAPK pathway by PD 98059, of cytosolic (cPLA2) and secretory phospholipases A2 by AACOCF3 and thioetheramide-PC, respectively, reduced sulfite-induced eicosanoid formation in AMs. Sulfite activated cPLA2 activity twofold at pH 7. This mechanism of sulfite-stimulated responses in phospholipid metabolism predicts that chronic exposure to sulfur(IV)/sulfite is associated with a considerable health risk.

Effects of inhaled CdO particles on the sphingolipid synthesis of rat lungs

Surfactant lipids of the alveolar space protect the lung from various environmental stimuli. We investigated the influence of ultrafine (UF) CdO particles inhalation on two key enzymes involved in lung sphingolipid metabolism, serine palmitoyltransferase (SPT), and sphingomyelinase (SMase). Rats inhaled either 0.63 mg UF-CdO/m(3) for 6 h (group 1), or 1.08 mg UF-CdO/m(3) 12 h/day for 10 days (group 2). Two corresponding control groups inhaled filtered clean air. Additional rats intratracheally instilled with lipopolysaccharide (LPS) were used as positive controls. Semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) of lung tissue showed a significant increase in the level of SPT mRNA (LCB2 subunit) expression in group 2 compared to the corresponding controls (p <.01). Group 1 and LPS were not statistically different from control. No alteration in the mRNA level of SMase was detected in any exposure group. The immunohistochemical analysis showed that SPT (LCB2 subunit) localization was stronger in the alveolar type II cells of group 2 lungs compared to the corresponding controls. These results were correlated with alterations in BALF cellular and biochemical parameters and lung morphology. Since SPT is the key enzyme for de novo sphingolipid synthesis in lung surfactant and SMase is responsible for sphingomyelin catabolism, we can postulate that high-dose UF-CdO exposure for 10 days induces an increase in sphingolipid synthesis in the type II cells of rat lungs that would not be promptly followed by its degradation.

[Pneumological diagnostics by means of models aerosols. IV. Clearance of aerosol particles from the pulmonary alveoli. Foundations and first clinical results]

The elimination of deposited particles (inorganic and organic particles, bacteria, viruses) from the periphery of the human lung (alveolar clearance) implies phagocytosis by alveolar macrophages, intracellular digestion, migration and translocation. Alveolar clearance of poorly soluble particles happens very slowly and primarily depends on the function of alveolar macrophages. In humans, the transport of particles to the bronchial tree is of secondary relevance, suggesting that the elimination of particles primarily depends on digestion (dissolution) processes within macrophages. The dissolved material is excreted via urine, if there is no further metabolization within the body. The pathophysiology of the alveolar clearance mechanisms in the human lung can be studied by a magnetic tracer technique (magnetopneumography). Ferromagnetic magnetite test-particles are deposited in the periphery of the lung by controlled inhalation. After magnetization and particle alignment in a strong external magnetic field pulse, the amount of retained particles can be detected by a sensitive magnetic field sensor (SQUID, superconducting quantum interference device). Long lasting cigarette smoking and chronic lung inflammations (sarcoidosis, interstitial lung fibrosis) induce a significant impairment of alveolar clearance capacity, while patients with chronic bronchitis show only a moderate impairment of alveolar clearance.

Inbred strain variation in lung function

The purpose of the present study was to determine the strain-specific phenotype variance of lung function parameters among common inbred laboratory mouse strains. In accordance with the "Mouse Phenome Project" run by The Jackson Laboratory (http://www.jax.org/phenome), lung volumes, lung mechanics, and diffusing capacity of 16 males and 16 females of the strains C3H/HeJ, BALB/cByJ, C57B1/6J, A/J, FVB/J, 129SV/ImJ, and SWR/J were determined in a standardized manner. The defined respiratory maneuvers for lung function testing were performed with a custom-made, computer-controlled servo-ventilator in anesthetized animals. Sex differences within the strains were found in most (83%) of the absolute lung function parameters. Usually, normalization to body or lung size completely compensates for the observed gender differences. There was great diversity between strains for all of the lung function parameters studied; for example, the total lung capacity as well as the pulmonary diffusing capacity for carbon monoxide varied by 50% and the static lung compliance by a factor of almost two among the strains. Little, but statistically significant variability was detectable for the dead space volume and the respiratory system resistance. There was no clear-cut evidence for any strain exhibiting either the smallest or the largest values for all parameters studied, suggesting that there were no simple allometric relationships of lung size between the strains. Well-established genealogical relationships among strains were not constantly reflected in phenotype similarities of pulmonary function. Therefore, these data strongly support heritable genetic traits for pulmonary function. Moreover, it constitutes a basis for further genetic lung function-related studies.

Ultrafine particles cause cytoskeletal dysfunctions in macrophages

Essential cytoskeletal functions of macrophages are migration, phagocytosis of foreign materials, and intracellular transport and digestion The influence of fine and ultrafine test particles (UFP), such as TiO(2), elemental carbon, commercial carbon black, diesel exhaust particulate matter, and urban dust (UrbD), on cytoskeleton-related functions of macrophages, such as phagocytosis, phagosome transport mechanisms, and mechanical cytoskeletal integrity, were studied by flow cytometry and by cytomagnetometry. Additionally, necrosis and apoptosis caused by the test particles was detected. The diameter of the test particles ranged from 12 to 220 nm and the Brunauer-Emmet-Teller specific surface area ranged from 6 to 600 m(2)/g. Primary alveolar macrophages from beagle dogs (BD-AM), obtained by bronchoalveolar lavage, were used as well as macrophages originating from the cell line J774A.1. For cytomagnetometry studies, spherical 1.8-microm ferromagnetic particles served as probes for cytoskeletal functions and were incubated together with the macrophages 24 h prior to UFP exposure. Macrophages were exposed in vitro with 10-320 microg UFP/ml/10(6) cells up to 24 h. In all experiments, J774A.1 macrophages were more sensitive than BD-AM to UFP exposure. Cytoskeletal dysfunctions evaluated by cytomagnetometry were an impaired phagosome transport and an increased cytoskeletal stiffness and occurred at concentrations of 100 microg UFP/ml/10(6) cells and above, in both BD-AM and J774A.1. Only fine TiO(2) did not show any effect. Urban dust (standard reference material 1649a) and diesel exhaust particles (DEP, standard reference material 1650) caused comparable cytoskeletal dysfunctions to elemental carbon with high specific surface area. Cytoskeletal dysfunctions induced by DEP or UrbD could be reduced after washing the particles by dichloromethane. UFP caused an impaired phagocytosis of 1-microm diameter fluorescent latex beads, inhibited cell proliferation, and decreased cell viability. All recorded cytotoxic parameters showed only weak correlations with the specific surface area or the total number of UFP, which can result from the different types of particles and different surface compositions. UFP cause cytoskeletal toxicity in vitro in macrophages, which can cause cellular dysfunctions, such as impaired proliferation, impaired phagocytic activity, and retarded intracellular transport processes as well as increased cell stiffness and can result in impaired defense ability in the lung.

Respiratory mechanics in mice: strain and sex specific differences

To assess the contribution of genetic background to respiratory mechanics, we developed a ventilator unit to measure lung function parameters in the mouse. We studied two commonly used inbred mice strains originating from Mus musculus domesticus (C57BL/6 and C3HeB/FeJ) and a third strain derived from Mus musculus molossinus [Japanese fancy mouse 1 (JF1)]. The ventilator allows for accurate performance of the different breathing manoeuvres required for measuring in- and expiratory reserve capacity, quasi-static and dynamic compliance, and airway resistance. In combination with a mass spectrometer for monitoring gas concentrations, single-breath manoeuvres were performed and He-expirograms obtained, from which dead space volume and slope of phase III were determined. From each strain and each sex, 10, 2-month old animals were studied immediately after being killed by an intraperitoneal overdose of xylazine and ketamine. C3HeB/FeJ and C57BL/6 exhibited comparable lung volumes. In male C3HeB/FeJ mice, e.g. vital capacity (VC) was 1072 +/- 79 microL, inspiratory reserve capacity 782 +/- 88 microL, and dead space volume at total lung inflation 216 +/- 18 microL. Lung volumes of JF1 were significantly lower (e.g. VC 611 +/- 53 microL, P < 0.01) even when normalized to body weight. In all three strains, specific lung volumes were significantly higher in females than in males, possibly explained by a higher oxygen demand during pregnancy and lactation, both of which fill most of their life times. Static compliance in C3HeB/FeJ was 64.3 +/- 5.4 microL cmH2O-1. It was smaller in C57BL/6 and JF1 mice, even when related to the lung volume. Analysis of the degree of genetic vs. non-genetic components of the phenotypic variation revealed that at least 80% of the total variation of lung volumes and static compliance in the mixed population is attributable to genetic differences between individuals. These differences will be verified in further studies by segregation and genetic linkage analysis.

Increased sputum IL-8 and IL-5 in asymptomatic nonspecific airway hyperresponsiveness

Since asymptomatic, nonspecific airway hyperresponsiveness (BHR) may be due to an enhanced local inflammatory response, we studied molecular markers of inflammation in induced sputum from subjects with asymptomatic BHR (n = 14) compared with control subjects (n = 13) and patients with chronic obstructive pulmonary disease (COPD) (n = 10). Pulmonary lung function parameters were measured by spirometry and body plethysmography. Hyperresponsiveness was defined based on histamine challenge. Induced sputum samples were collected and the solid phase was isolated and analyzed for leukocyte numbers and differential and for cytokines (ELISA). IL-8 was 2.4-fold increased (p = 0.036) in the sputum of subjects with asymptomatic BHR (24.8 +/- 22.0 ng/mL; +/- SD) and 11.2-fold enhanced in patients with COPD (117.8 +/- 106.3 ng/mL) as compared with control subjects (10.5 +/- 7.7 ng/mL). In control subjects, no IL-5 was measured, however, sputum of those with asymptomatic BHR contained IL-5 at 0.044 +/- 0.090 ng/mL fluid and COPD patients at 1.00 +/- 2.01 ng/mL. GM-CSF could not be detected in sputum samples of any subjects investigated. Number of total leukocytes was higher in those with asymptomatic BHR and COPD (with BHR: 9.4 +/- 10.8 x 10(5); COPD: 83.5 +/- 182.5 x 10(5)) compared with persons without BHR (2.9 +/- 3.4 x 10(5)). PMN were increased in patients with asymptomatic BHR (4.1 +/- 5.3 x 10(5)) (38.8 +/- 24.7%) and COPD (32.9 +/- 71.0 x 10(5)) (75.4 +/- 18.6%) compared with controls (0.7 +/- 0.9 x 10(5)) (25.8 +/- 25.7%). In contrast to PMN counts in those with asymptomatic BHR (0.06 +/- 0.11 x 10(5)) (1.5 +/- 3.7%), eosinophil counts were only slightly increased compared with control subjects (0.01 +/- 0.02 x 10(5)) (0.6 +/- 0.9%). This study supports the hypothesis that BHR in asymptomatic people is associated with airway inflammation that may predispose to development of chronic diseases such as COPD.

Human alveolar long-term clearance of ferromagnetic iron oxide microparticles in healthy and diseased subjects

Monodisperse ferrimagnetic microparticles (Fe3O4) with 1.3 microm geometric diameter were inhaled to study alveolar long-term clearance in healthy and diseased human subjects. Nineteen younger (age 20 to 39 years) and 20 older (age 40 to 65 years) healthy volunteers participated in the study as well as 15 patients with sarcoidosis (SAR), 12 patients with idiopathic pulmonary fibrosis (IPF), and 15 patients with chronic obstructive bronchitis (COB). In each group the subjects were divided into never smokers (NS) and active smokers (S). Clearance was measured by magnetopneumography (MPG) for 300 days after inhalation. In COB, 50% of the deposited particles were removed from the lungs after 2 days, indicating high bronchial deposits due to bronchial obstructions. In healthy NS, only 10% of the particles were removed after 2 days and cigarette smoking enhanced the fraction of fast-cleared particles. In subjects who smoked, slow clearance was significantly impaired (P < . 02). Clearance half-lives (in days) for younger, healthy, NS were 124 +/- 66 (mean +/- SD) compared to 220 +/- 74 for S. Similarly for older subjects, the timeswere 162 +/- 120 for NS and 459 +/- 334 for S. The impairment of alveolar clearance due to cigarette smoking increases by 5.7 +/- 1.3 days/pack-year (P < .01). Alveolar clearance was impaired in SAR and in IPF; half-lives were 275 +/- 109 days (P < .05) and 756 +/- 345 days (P < .02), respectively, compared to healthy NS. Most COB patients were ex-smokers, their long-term clearance was 240 +/- 74 days, which is more than healthy NS (P < .01), but less than healthy S and might indicate a recovery of alveolar clearance. In view of studies using totally inert particles like Teflon, we conclude that the lung clearance measured with iron oxide tracer particles primarily reflects clearance by intraphagosomal particle dissolution within alveolar macrophages, which is impaired by cigarette smoke consumption and in patients.

Impulse oscillometry in healthy nonsmokers and asymptomatic smokers: effects of bronchial challenge with methacholine

The clinical application of respiratory impedance measurements by oscillation techniques for monitoring bronchial challenge testing is hampered by the fact that data in healthy nonsmokers and asymptomatic smokers are very limited. The objective of this study was to analyze the changes in impedance to a methacholine provocation test in healthy nonsmokers and asymptomatic smokers, and to investigate whether smokers show a different response compared to nonsmokers. The response to methacholine challenge was assessed by impulse oscillometry (IOS) (resistance R and reactance X at 5, 10, 15, 20, 25, and 35 Hz) and spirometry (FEV1, MEF50) in 105 healthy subjects (55 nonsmokers: "NS"; 50 asymptomatic smokers: "S") in whom the provocation dose of 2.44 mg methacholine did not result in a fall of FEV1 below 20% predicted of the baseline value. The baseline reactance X values of S were significantly lower compared to NS from 10 to 35 Hz (p < or = 0.01), whereas S and NS did not differ in resistance R over the whole frequency spectrum from 5 to 35 Hz. S showed a significantly higher mean baseline resonant frequency X(f0); i.e., the frequency at which inertial forces are equal and opposite to elastic forces, compared to NS (NS: X(fo) = 10.8+/-2.9 Hz; S = 12.6+/-4.0 Hz, p = 0.01). In both groups methacholine challenge resulted in an increase in R (f) especially at 5 and 10 Hz, and a marked decrease in X(f) over the whole frequency spectrum. In S a significantly higher decrease of postchallenge X5Hz and X10Hz was measured compared to NS (NS: deltaX(5Hz) = -0.044+/-0.003; S: deltaX(5HZ) = -0.083+/-0.013; p = 0.0017. NS: deltaX(10Hz) = -0.050+/-0.001; S: deltaX(10Hz) = -0.082+/-0.017; p = 0.008). R and X at low frequencies showed a three to four times higher postchallenge reaction compared to FEV1. Pre- and postchallenge FEV1 did not correlate with resistance R (f) and reactance X(f) over the whole frequency spectrum. In S perchallenge X(f) values from 10 to 35 HZ were significantly lower, and postchallenge decrease of X5Hz and X10Hz values were significantly higher compared to that of NS, whereas pre- and postchallenge R(f) values were similar in both groups. These results can be explained by changes in the elastic properties of the lung induced by a diffuse subclinical respiratory bronchiolitis.

Agglomerates of ultrafine particles of elemental carbon and TiO2 induce generation of lipid mediators in alveolar macrophages

Agglomerates of ultrafine particles (AUFPs) may cause adverse health effects because of their large surface area. To evaluate physiologic responses of immune cells, we studied whether agglomerates of 77-nm elemental carbon [(EC); specific surface area 750 m2/g] and 21 nm titanium dioxide (TiO(2) particles (specific surface area 50 m(2)/g) affect the release of lipid mediators by alveolar macrophages (AMs). After 60-min incubation with 1 microg/mL AUFP-EC (corresponding to 7.5 cm(2) particle surface area), canine AMs (1 x 10(6) cells/mL) released arachidonic acid (AA) and the cyclooxygenase (COX) products prostaglandin E(2) (PGE(2), thromboxane B(2), and 12-hydroxyheptadecatrienoic acid but not 5-lipoxygenase (5-LO) products. AUFP-TiO(2) with a 10-fold higher mass (10 microg/mL) than AUFP-EC, but a similar particle surface area (5 cm(2) also induced AMs to release AA and COX products. Agglomerates of 250 nm TiO(2) particles (specific surface area 6.5 m(2)/g) at 100 microg/mL mass concentration (particle surface area 6.5 cm(2) showed the same response. Interestingly, 75 cm(2)/mL surface area of AUFP-EC and 16 cm(2)/mL surface area of AUFP-TiO(2) additionally induced the release of the 5-LO products leukotriene B(4) and 5-hydroxyeicosatetraenoic acid. Respiratory burst activity of stimulated canine neutrophils was partially suppressed by supernatants of AMs treated with various mass concentrations of the three types of particles. Inhibition of neutrophil activity was abolished by supernatants of AMs treated with COX inhibitors prior to AUFP-incubation. This indicates that anti-inflammatory properties of PGE(2) dominate the overall response of lipid mediators released by AUFP-affected AMs. In conclusion, our data indicate that surface area rather than mass concentration determines the effect of AUFPs, and that activation of phospholipase A(subscript)2(/subscript) and COX pathway occurs at a lower particle surface area than that of 5-LO-pathway. We hypothesize a protective role of PGE(2) in downregulating potential inflammatory reactions induced by ultrafine particles.

Pulmonary and systemic distribution of inhaled ultrafine silver particles in rats

The cardiovascular system is currently considered a target for particulate matter, especially for ultrafine particles. In addition to autonomic or cytokine mediated effects, the direct interaction of inhaled materials with the target tissue must be examined to understand the underlying mechanisms. In the first approach, pulmonary and systemic distribution of inhaled ultrafine elemental silver (EAg) particles was investigated on the basis of morphology and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Rats were exposed for 6 hr at a concentration of 133 microg EAg m(3) (3 x 10(6) cm(3), 15 nm modal diameter) and were sacrificed on days 0, 1, 4, and 7. ICP-MS analysis showed that 1.7 microg Ag was found in the lungs immediately after the end of exposure. Amounts of Ag in the lungs decreased rapidly with time, and by day 7 only 4% of the initial burden remained. In the blood, significant amounts of Ag were detected on day 0 and thereafter decreased rapidly. In the liver, kidney, spleen, brain, and heart, low concentrations of Ag were observed. Nasal cavities, especially the posterior portion, and lung-associated lymph nodes showed relatively high concentrations of Ag. For comparison, rats received by intratracheal instillation either 150 microL aqueous solution of 7 microg silver nitrate (AgNO(3) (4.4 microg Ag) or 150 microL aqueous suspension of 50 microg agglomerated ultrafine EAg particles. A portion of the agglomerates remained undissolved in the alveolar macrophages and in the septum for at least 7 days. In contrast, rapid clearance of instilled water-soluble AgNO(3) from the lung was observed. These findings show that although instilled agglomerates of ultrafine EAg particles were retained in the lung, Ag was rapidly cleared from the lung after inhalation of ultrafine EAg particles, as well as after instillation of AgNO(3), and entered systemic pathways.