Early Response of the Canine Respiratory Tract Following Long-Term Exposure to a Sulfur(IV) Aerosol at low Concentration. II. Biochemistry and Cell Biology of Lung Lavage Fluid

Abstract

Eight beagle dogs were exposed for 290 d to a low concentration of sulfur(/\/) aerosol 10.3 mg m -3 S(IQ corresponding to 0.6 mg m -3 sulfur dioxide]. 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 (EAL) 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(/\/) exposure. This indicates either a lowered oxidant burden andlor an increased antioxidant capacity in the lungs. The enzyme @-Nacetylglucosaminidase increased significantly (p < .05) in the EAL fluid. This increase might be due to enhanced release of lysosomal 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.

Oxymetazoline Inhibits Proinflammatory Reactions: Effect on Arachidonic Acid-Derived Metabolites

“…The opsonized zymosan was washed twice, suspended in PBS, pH 7, containing 0.1% glucose, and aliquots were frozen until use. The cells were exposed to opsonized zymosan at 100 g/ml, which represents a mass concentration to achieve optimal functional responses (Maier et al, 1992;Beck-Speier et al, 2005). In comparison with UCP, the zymosan particles with their larger diameter (2-3 m) possess a smaller surface area per mass (estimated below 10 m 2 /g) than UCP.…”

“…Figure 4 shows that AMs stimulated by opsonized zymosan in the absence of oxymetazoline exhibited elevated levels of LTB 4 formation and CL (p Ͻ 0.001). The amount of opsonized zymosan used in theses assays corresponded to the standard concentrations necessary to achieve optimal activation of AMs via the Fc-and complement receptor-mediated systems (Maier et al, 1992;Beck-Speier et al, 2005). In the presence of oxymetazoline, the levels of both parameters decreased drastically at higher oxymetazoline concentrations (0.1-1.0 mM).…”

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

“…Canine AMs were harvested by bronchoalveolar lavage of healthy beagles according to the method of Maier et al (22). Cells were recovered by centrifugation (400 × g for 20 min) and resuspended in PBS (without Ca 2+ /Mg 2+ ).…”

Long-term canine exposure studies with ambient air pollutants

“…At lower levels of exposure, respiratory responses were similar to those observed at high levels, but they occurred later. For instance, GREENE et al [42] reported persistent lung inflammation during exposure to 660 mg·m -3 , whereas, at the lowest exposure level, an inflammatory response was detected only late in the study [44]. In this GSF study, no indication of chronic bronchitis was observed, but there were functional and morphometrical indications of the early stage of emphysema, which resulted from delivery of particulate S(IV) to the lung periphery.…”