[Show abstract][Hide abstract] ABSTRACT: Ambient particulate matter (PM)-associated metals have been shown to play an important role in cardiopulmonary health outcomes. To study the modulation of PM-induced inflammation by leached off metals, we investigated intracellular solubility of radio-labeled iron oxide ((59)Fe(2)O(3)) particles of 0.5 and 1.5 mum geometric mean diameter. Fe(2)O(3 )particles were examined for the induction of the release of interleukin 6 (IL-6) as pro-inflammatory and prostaglandin E(2 )(PGE(2)) as anti-inflammatory markers in cultured alveolar macrophages (AM) from Wistar Kyoto (WKY) rats. In addition, we exposed male WKY rats to monodispersed Fe(2)O(3 )particles by intratracheal instillation (1.3 or 4.0 mg/kg body weight) to examine in vivo inflammation.
Particles of both sizes are insoluble extracellularly in the media but moderately soluble in AM with an intracellular dissolution rate of 0.0037 +/- 0.0014 d(-1 )for 0.5 mum and 0.0016 +/- 0.0012 d(-1 )for 1.5 mum (59)Fe(2)O(3 )particles. AM exposed in vitro to 1.5 mum particles (10 mug/mL) for 24 h increased IL-6 release (1.8-fold; p < 0.05) and also PGE(2 )synthesis (1.9-fold; p < 0.01). By contrast, 0.5 mum particles did not enhance IL-6 release but strongly increased PGE(2 )synthesis (2.5-fold, p < 0.005). Inhibition of PGE(2 )synthesis by indomethacin caused a pro-inflammatory phenotype as noted by increased IL-6 release from AM exposed to 0.5 mum particles (up to 3-fold; p < 0.005). In the rat lungs, 1.5 but not 0.5 mum particles (4.0 mg/kg) induced neutrophil influx and increased vascular permeability.
Fe(2)O(3 )particle-induced neutrophilic inflammatory response in vivo and pro-inflammatory cytokine release in vitro might be modulated by intracellular soluble iron via PGE(2 )synthesis. The suppressive effect of intracellular released soluble iron on particle-induced inflammation has implications on how ambient PM-associated but soluble metals influence pulmonary toxicity of ambient PM.
Particle and Fibre Toxicology 12/2009; 6:34. · 9.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The nasal decongestant oxymetazoline effectively reduces rhinitis symptoms. We hypothesized that oxymetazoline affects arachidonic acid-derived metabolites concerning inflammatory and oxidative stress-dependent reactions. The ability of oxymetazoline to model pro- and anti-inflammatory and oxidative stress responses was evaluated in cell-free systems, including 5-lipoxygenase (5-LO) as proinflammatory, 15-lipoxygenase (15-LO) as anti-inflammatory enzymes, and oxidation of methionine by agglomerates of ultrafine carbon particles (UCPs), indicating oxidative stress. In a cellular approach using canine alveolar macrophages (AMs), the impact of oxymetazoline on phospholipase A(2) (PLA(2)) activity, respiratory burst and synthesis of prostaglandin E(2) (PGE(2)), 15(S)-hydroxy-eicosatetraenoic acid (15-HETE), leukotriene B(4) (LTB(4)), and 8-isoprostane was measured in the absence and presence of UCP or opsonized zymosan as particulate stimulants. In cell-free systems, oxymetazoline (0.4-1 mM) inhibited 5-LO but not 15-LO activity and did not alter UCP-induced oxidation of methionine. In AMs, oxymetazoline induced PLA(2) activity and 15-HETE at 1 mM, enhanced PGE(2) at 0.1 mM, strongly inhibited LTB(4) and respiratory burst at 0.4/0.1 mM (p < 0.05), but did not affect 8-isoprostane formation. In contrast, oxymetazoline did not alter UCP-induced PLA(2) activity and PGE(2) and 15-HETE formation in AMs but inhibited UCP-induced LTB(4) formation and respiratory burst at 0.1 mM and 8-isoprostane formation at 0.001 mM (p < 0.05). In opsonized zymosan-stimulated AMs, oxymetazoline inhibited LTB(4) formation and respiratory burst at 0.1 mM (p < 0.05). In conclusion, in canine AMs, oxymetazoline suppressed proinflammatory reactions including 5-LO activity, LTB(4) formation, and respiratory burst and prevented particle-induced oxidative stress, whereas PLA(2) activity and synthesis of immune-modulating PGE(2) and 15-HETE were not affected.
Journal of Pharmacology and Experimental Therapeutics 03/2006; 316(2):843-51. · 3.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
Free Radical Biology and Medicine 05/2005; 38(8):1080-92. · 5.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Recently, concern has been raised about effects related to environmental sulfur and/or acidic aerosols. To assess long-term effects on nonrespiratory lung function, 8 beagle dogs were exposed over a period of 13 mo for 16.5 h/day to a neutral sulfite aerosol at a sulfur(IV) concentration of 0.32 mg m(-3) and for 6 h/day to an acidic sulfate aerosol providing a hydrogen concentration of 15.2 micromol m(-3) for inhalation. Prior to exposure the dogs were kept under clean air conditions for 16 mo to establish physiological baseline values for each animal. A second group of eight dogs (control) was kept for the entire study under clean air conditions. No clinical symptoms were identified that could be related to the combined exposure. Biochemical and cellular parameters were analyzed in sequential bronchoalveolar lavage (BAL) fluids. The permeability of the alveolo-capillary membrane and diethylenetriaminepentaacetic acid (DTPA) clearance was not affected. Similarly, oxidant burden of the epithelial lining fluid evaluated by levels of oxidation products in the BAL fluid protein fraction remained unchanged. Both the lysosomal enzyme beta-N-acetylglucosaminidase and the alpha-1-AT were increased (p <.05). In contrast, the cytoplasmic marker lactate dehydrogenase remained unchanged, indicating the absence of severe damages to epithelial cells or phagocytes. Various surfactant functions were not altered during exposure. Three animals showed elevated levels of the type II cell-associated alkaline phosphatase (AP), indicating a nonuniform response of type II cells. Significant correlations were found between AP and total BAL protein, but not between AP and lactate dehydrogenase, suggesting proliferation of alveolar type II cells. Absolute and relative cell counts in the BAL fluid were not influenced by exposure. Alveolar macrophages showed no alterations with regard to their respiratory burst upon stimulation with opsonized zymosan. The percentage of alveolar macrophages capable of phagocytozing latex particles was significantly decreased (p<.05), while the phagocytosis index was not altered. In view of the results of this and previous studies, we conclude that there is no synergism of effects of these two air pollutants on nonrespiratory lung functions. It is hypothesized that antagonistic effects of these air pollutants on phospholipase A2-dependent pathways account for compensatory physiological mechanisms. The results emphasize the complexity of health effects on lung functions in response to the complex mixture of air pollutants and disclose the precariousness in the risk assessment of air pollutants for humans.
[Show abstract][Hide abstract] ABSTRACT: Air pollutants are supposed to modulate physiological responses of alveolar macrophages (AM). This study was addressed to the question whether at neutral pH sulfur(IV) species in comparison to sulfur(VI) species cause AM to release proinflammatory mediators and which pathways are involved in their generation. Supernatants obtained from canine AM treated with sulfite (0.1 mM to 2 mM) enhanced the respiratory burst of canine neutrophils, measured by lucigenin-dependent chemiluminescence, whereas supernatants derived from AM treated with sulfite (1 mM) did not. The neutrophil-stimulating activity released by sulfite-treated AM consisted of platelet-activating factor (PAF) and leukotriene B4 (LTB4) as shown by desensitization of the corresponding receptors. Inhibitors of phospholipase A2 substantially suppressed release of neutrophil-stimulating activity by sulfite-treated AM. Inhibition of 5-lipoxygenase in sulfite-treated AM also reduced neutrophil-stimulating activity, while inhibition of cyclooxygenase had no effect. In conclusion, sulfite induces AM to release lipid mediators via phospholipase A2- and 5-lipoxygenase-dependent pathways. These mediators activate neutrophils via the receptors for PAF and LTB4.
Zeitschrift fur Naturforschung C 07/1998; 53(3-4):264-272. · 0.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Alveolar macrophages (AM) were studied for their capability to release mediators involved in modulation of neutrophil (PMN) functions. Initial responses were induced by sulphite. Supernatants obtained from canine, human and rat AM pre-treated with sulphite in concentrations of 0.1-2 mmol/L enhanced the respiratory burst of canine, human and rat PMN, measured by lucigenin-dependent chemiluminescence (CL). This PMN-stimulating activity exhibited platelet-activating factor (PAF)-like properties, as indicated by desensitization of the PAF receptor, inhibition with PAF antagonists WEB 2086 and CV 3988, and the kinetic CL response like PAF after chloroform extraction of supernatants inhibitable by PAF antagonist CV 3988. These results indicate that AM are triggered by sulphite to release mediators that activate the respiratory burst of PMN, primarily via the PAF receptor.
Journal of Bioluminescence and Chemiluminescence 04/1998; 13(2):91-9.
[Show abstract][Hide abstract] ABSTRACT: To assess the effect of sulphite on the oxidative metabolism of human neutrophils, chemiluminescence (CL) measurements were performed using lucigenin and luminol as chemiluminigenic probes. Lucigenin-dependent CL was used for measuring superoxide anion (O2-) production, and luminol-dependent CL was used for determination of myeloperoxidase (MPO)-connected processes. With sulphite concentrations of 0.01 to 1 mmol/L, resting neutrophils showed an up to sixfold increase of lucigenin-dependent CL, but only a 1.9-fold increase of luminol-dependent CL. Subsequent stimulation of sulphite-treated neutrophils with phorbol myristate acetate (PMA) (soluble stimulant) or zymosan (particulate stimulant) resulted in an additional significant increase of lucigenin-dependent CL compared to stimulated control cells, whereas luminol-dependent CL increased slightly by 0.01 mmol/L sulphite and decreased then continuously. Sulphite concentrations above 1 mmol/L decreased both lucigenin- and luminol-dependent CL of resting and PMA- or zymosan-stimulated neutrophils. Lucigenin-dependent CL of sulphite-treated and subsequently stimulated neutrophils was strongly inhibited by extracellularly added superoxide dismutase, whereas luminol-dependent CL was markedly reduced by the MPO inhibitor azide. The intracellular activity of MPO in neutrophils stimulated with PMA in the presence of sulphite (2 mmol/L) was reduced by 55%. Sulphite (0.1 mmol/L) also inhibited strongly the activity of MPO in a cell-free system. These results indicate that micromolar concentrations of sulphite exert a stimulating effect on the O2- production of neutrophils extracellularly, but have an inhibitory effect on MPO-catalysed reactions intracellularly.
Journal of Bioluminescence and Chemiluminescence 01/1995; 10(1):9-19.
[Show abstract][Hide abstract] ABSTRACT: Abstract Eight beagle dogs were exposed for 290 d to a low concentration of sulfur(IV/) aerosol 10.3 mg m−3 S(IV) corresponding to 0.6 mg m−3 sulfur dioxidel. No clinical symptoms were found that could be correlated with the pollutant. However, significant changes were observed in some of the biochemical and cellular parameters determined in sequential bronchoalveolar lavage (BAL) fluids. The protein and albumin concentration increased (p <.05) in the second half of the exposure period, indicating changes in the transudation kinetics of serum proteins into the alveolar lumen. The relative levels of methionine sulfoxide and carbonyl groups in the BAL protein, indicators for oxidative reactions in the respiratory tract, were lowered (p <.03) immediately after the beginning of chronic sulfur(IV) exposure. This indicates either a lowered oxidant burden andlor an increased antioxidant capacity in the lungs. The enzyme β-N-acetylglucosaminidase increased significantly (p <.05) in the EAL fluid. This increase might be due to enhanced release of Iysosomal compounds mediated by sulfite. It did not result from damage of BAL cells, since their viability was not impaired during exposure. Alveolar macrophages (AM) showed a lowered in vitro phagocytosis rate (p<.05) for polystyrene particles and a reduced production (p <.05) of oxygen-derived free radicals after stimulation with opsonized zymosan. These results indicate a reduction in the nonspecific defense capacity of the AM. In conclusion, chronic exposure to an S(IV) aerosol at low concentration might initiate pathobiochemical pathways in the lungs, indicating a potential health hazard.
[Show abstract][Hide abstract] ABSTRACT: During exposure of 8 Beagle dogs for 290 days to particulate sulphur(IV) no clinical symptoms were seen which could be correlated with the pollutant. However, significant changes were observed in some of the biochemical and cellular parameters in the bronchoalveolar lavage (BAL) fluid. In the second half of the exposure period the protein and albumin content of the BAL fluid increased indicating changes in the transudation kinetics of serum proteins into the alveolar lumen. The lysosomal enzyme β-N-acetyl-glucosaminidase also increased in the BAL fluid indicating a higher release of this enzyme from phagocytes. At the same time alveolar macrophages showed a reduced phagocytosis rate in vitro for polystyrene particles and a reduced production of oxygen-derived free radicals. These results indicate a reduced unspecific defence capacity of the alveolar macrophages as well as a change in their lysosomal activity. In conclusion, chronic exposure to particulate S(IV) at a low concentration can initiate pathobiochemical pathways in the lungs indicating the possibility of a health risk.
Journal of Aerosol Science 07/1990; 21:S475-S478. · 2.69 Impact Factor