Faculty Bibliography

Ozone, one of the most reactive oxidant gases to which humans are routinely exposed, induces inflammation in the lower airways. The airway epithelium is one of the first targets that inhaled ozone will encounter, but its role in airway inflammation is not well understood. Expression of inducible genes involved in the inflammatory response, such as interleukin (IL)-8, is controlled by transcription factors. Expression of the IL-8 gene is regulated by the transcription factors nuclear factor (NF)-kappaB, NF-IL-6, and possibly activator protein-1 (AP-1). Type II-like epithelial cells (A549) were grown on a collagen-coated membrane and exposed in vitro to 0.1 ppm ozone or air. Exposure to ozone induced DNA-binding activity of NF-kappaB, NF-IL-6, and AP-1. IL-8 mRNA and IL-8 protein levels were also increased after ozone exposure. These results link ozone-induced DNA-binding activity of transcription factors and the production of IL-8 by epithelial cells thus demonstrating a potential cellular cascade resulting in the recruitment of inflammatory cells into the airway lumen

In vivo exposure to ozone (O3) has been shown to cause airway epithelial damage and lipid peroxidation. The oxidation of polyunsaturated fatty acids has been shown to produce hydrogen peroxide and aldehydes with reactive oxygen species (ROS) as intermediates. These products of ozonation may react with other bioorganic molecules and cause cellular damage. To assess the production of ROS, confluent primary cultures of guinea pig airway epithelial cells were grown on Costar membrane with a liquid-air interface and exposed to 0.2, 0.4, and 0.6 ppm O3. The concentrations of intracellular ROS during the exposure were monitored using the fluorescent dye dihydrorhodamine-123. The intracellular concentration of ROS increased immediately upon the commencement of the O3 exposure and persisted until the end of the exposure period (up to 1 hr). The concentration of ROS increased with increasing O3 concentration. To determine the species of ROS produced during O3 exposure, airway epithelial cells were perfused with dimethyl sulfoxide (DMSO), sodium formate (hydroxyl radical scavengers), NaN3 (catalase inhibitor), or diethyl-dithio carbamate (DEDC, superoxide dismutase inhibitor) prior to and during the exposure period and the fluorescent intensity was monitored continuously. While both DMSO and sodium formate decreased the concentration of ROS, DEDC and NaN3 had no effect. We concluded that hydroxyl radicals instead of H2O2 or superoxide anions were produced immediately following the commencement of O3 exposure in guinea pig airway epithelial cells in an exposure concentration-dependent fashion

Generating controlled test atmospheres of known chemical identity and airborne concentration upon demand is a significant technical obstacle that limits the scope and repeatability of studies of inhaled substances. We addressed this problem as applied to the generation of atmospheres that result from heating crack cocaine, which include both cocaine and its pyrolyzate methylecgonidine (MEG). A condensation aerosol generator was used to generate atmospheres comprised of monodisperse particles of cocaine, MEG, or mixtures of both that are of submicron size suitable for deposition in the alveolar region of primates. Compressed air seeded with nanometer-size sodium chloride particles was passed through a constant depth of molten cocaine or MEG in a bead bed, reheated, and condensed to an aerosol within an annulus of cold air. To achieve control of a mixture of both compounds, MEG was condensed onto cocaine particles in a separate coating step. On-line analytical instruments provided verification of airborne concentration, estimates of particle size, and dispersion as well as chemical identity. Specific airway conductance (SGaw), heart rate, and rectal and skin temperatures were measured in squirrel monkeys breathing atmospheres containing condensation aerosols of cocaine or MEG free base. SGaw was reduced after inhalation of either base, and both induced temperature and cardiovascular changes, demonstrating that the aerosols so generated had biological activity

In addition to being the single greatest known environmental cause of cancer, cigarette smoke (CS) is also a major contributor to heart disease. We reported previously that 1) inhalation of either mainstream or sidestream CS promotes aortic arteriosclerotic plaque development; 2) 1,3 butadiene, a vapor-phase component of CS, promotes plaque development at 20 ppm, which at the time was only 2 times higher than the threshold limit value; and 3) individual tar fraction carcinogens in CS, including polynuclear aromatic hydrocarbons (PAHs) and nitrosamines, either do not promote plaque development or do so only at high concentrations. These results suggested that the tar fraction is not the primary source of plaque-promoting agents in CS. We asked whether repeated exposure to the tar fraction of CS, collected in a cold trap (TAR), promotes plaque development in an avian model of arteriosclerosis. Acetone extracts of mainstream CS tar from burning, unfiltered reference cigarettes were solubilized in dimethyl sulfoxide (DMSO) and injected weekly into cockerels for 16 weeks (25 mg/kg/week). Positive controls were injected weekly with the synthetic PAH carcinogen, 7,12 dimethylbenz(a)anthracene (DMBA) dissolved in DMSO and negative controls were injected with DMSO. Plaque location and prevalence did not differ from group to group. Morphometric analysis of plaque cross-sectional areas showed that plaque sizes, which are log-normally distributed, were significantly larger in the DMBA cockerels compared to both the TAR and DMSO groups. There were no significant differences in plaque size between DMSO and TAR cockerels. The results reported here, combined with other recent findings, support the conclusion that the primary arteriosclerotic plaque-promoting components of CS are in the vapor phase

Nitric acid (HNO3) vapor is a component of ambient photochemical pollution. Because of its high water solubility and reactivity, it would be anticipated to undergo significant removal within the upper respiratory tract (URT). However, recent studies have shown that inhaled vapor can alter bronchial responsiveness and other functions of the lower respiratory tract (LRT). The penetration of HNO3 into the lungs was assessed using a physical system that mimicked the residence time of inhaled air in the URT of the animal used in this laboratory for toxicologic studies, namely, the rabbit. The system allowed for mixing of precisely metered concentrations of ammonia (NH3), which is present in the URT, under conditions of controlled relative humidity. The size of particles produced when HNO3 was introduced into humid atmospheres was also determined. In an NH3-free atmosphere maintained at 77% relative humidity, ultrafine particles (0.003 mu m) were formed When NH3 was added, the particle size increased to 0.15 mu m. While there was greater production of particles when NH3 was present at various humidity levels, even in the absence of NH3 almost 50% of HNO3 vapor formed particles at high humidity. The ability of other particles to act as vectors for adsorbed/absorbed HNO3 was also examined; such particles could then be carried into the LRT. The results indicate that HNO3 vapor is likely transformed into particle Form al some point following inhalation. Furthermore, endogenous ammonia may react with inhaled HNO3 producing particulate ammonium nitrate. Once formed these particles, and others present in the respiratory-tract air, may serve as vectors for HNO3 delivery to the LRT

We previously demonstrated that rats in a late stage of pregnancy and throughout lactation were more susceptible to pulmonary inflammation induced by exposure to 1 ppm ozone than were age-matched virgin females or rats following lactation. The purpose of the study reported here was to extend the comparison of ozone-induced pulmonary inflammation in lactating and postlactating rats to lower concentrations of ozone and to investigate the hypothesis that the enhanced response demonstrated by lactating rats is attributable to a greater inhaled ozone dose. During pregnancy and lactation the metabolic demands on the female are substantially increased above prepregnancy levels, In response to this metabolic demand, it was shown in this study that the minute volume of air-breathing postpartum rats on day 13 of lactation increased to approximately 150%, of that of age-matched postlactating rats with the same lung size. Heightened ventilation in lactating rats was maintained during exposure to 0.3, 0.5, and 1.0 ppm ozone for 6 h, resulting in greater inhaled ozone doses in lactating rats compared to postlactating rats exposed identically The pulmonary inflammatory response to ozone was assessed in the same rats 18 h after exposure by comparison of protein concentration and polymorphonuclear cell (PMN) numbers in bronchoalveolar lavage fluid (BALF). Both of these parameters were significantly greater in lactating than postlactating rats at 0.3, 0.5, and 1.0 ppm ozone. Statistical analysis indicated that most or all of the greater BALF protein in lactating rats could be accounted for by their greater inhaled dose, whereas a significant portion of the enhanced PMN influx in lactating rats remained unexplained by inhaled ozone dose

Ozone is a ubiquitous air pollutant which can affect numerous function s of the respiratory system. However, previous work has not provided any information concerning its ability to modulate pharmacological receptors of pulmonary macrophages. This study examined, using a chemiluminescence assay, the beta-adrenergic modulation of pulmonary macrophages harvested from rabbits exposed for 3 hr/day for 5 days to 0.1, 0.3 or 0.6 ppm ozone (O3) or to 3 hr/day for 20 days to 0.1 or 0.3 ppm. Receptor activity was monitored using release of reactive oxygen species (ROS) following administration to the cells of the beta2-receptor agonist, isoproterenol. An O3-exposure concentration-dependent response was observed for isoproterenol efficacy following 5-day exposures, in that 0.1 ppm O3 induced a significant enhancement of beta-adrenergic inhibition of ROS production, 0.3 ppm ozone produced no significant change from control, and 0.6 ppm decreased inhibition. No significant effects on beta-adrenergic modulation were noted following the 20-day exposures. The results of this study suggest that short-term repeated exposures to O3 are capable of inducing alterations in the pharmacological functioning of pulmonary macrophages, while longer term exposures may result in adaptation. Alterations in receptor function have implications in terms of pulmonary defense and disease

Kerosene space heaters are widely used as a major source of home heat in the United States and in countries such as Japan and Korea. Based on a report that evaluated particle emissions from unvented kerosene space heaters in an environmental chamber, kerosene space heaters can be an important indoor source of fine particles and a major source of sulfate and acidic aerosols. In this study, guinea pigs were exposed to filtered air or kerosene space heater (9000 Btu radiant heater) emissions for 3 h/day for 1 wk or 6 h/day, 5 days/wk for 4 wk. The following pollutant concentrations were measured during the exposure period: total mass loading, 69 mu g/ms(3); NO2, 0.17 ppm; particle number concentration, 2.7 x 10(5)/cm(3); SO2, 0.093 ppm; SO42-, 28.7 mu g/m(3). Nonspecific airway responsiveness was monitored before and during the 4-wk exposure period. Biochemical parameters in lavage fluid as well as functional characteristics of pulmonary macrophages were determined 24 h after the final exposure. In comparison to preexposure valves, the concentration of acetylcholine that decreased specific airway conductance by 50% was significantly decreased after 1 and 4 wk of exposure. These functional changes were accompanied by a small increase in lavage fluid protein following 4 wk of exposure (58%, p < .05) and by a number of alterations in pulmonary macrophages. Intracellular free Ca2+ concentration ([Ca2+](i) increased by 85% at the end of the 4-wk exposure. Small but statistically significant decreases in intracellular pH (pH(i)) of recovered lavage cells were also observed at the end of the 1-wk and 4-wk exposures. Furthermore, the in vitro phagocytic function of pulmonary macrophages was enhanced by 51% at the end of the 1-wk exposure and depressed by 79% at the end of the 4-wk exposure. Other changes in biochemical parameters or cell numbers were not observed. We conclude that repeated exposure to kerosene space heater emissions at concentrations relevant to those encountered in home use can produce alterations in airway responsiveness and pulmonary macrophage function in guinea pigs

Particulate pollutants are mixtures of a variety of chemical species. Sulfuric acid aerosol is a highly irritating component of particulate matter less than 10 mu m (PM-10) that can produce adverse health effects at current peak ambient concentrations in the United States. We hypothesized that, in addition to the mass concentration of sulfuric acid, the number of sulfuric acid droplets was also an important factor affecting lung injury. To test this hypothesis, guinea pigs were exposed for 3 h to either filtered air; inert carbon particles at 10(8) particles/ml; sulfuric acid at 350 mu g SO42-/m(3) layered on 10(8), 10(7), or 10(6) carbon particles/ml; sulfuric acid at 50, 100, 200, and 300 mu g SO42-/m(3) layered on 10(8) carbon particles/ml. Alterations in phagocytic capacity (PC), intracellular pH (pH(i)), and intracellular free calcium concentration ([Ca2+](i)) of harvested macrophages were used as indices of irritant potency. At a fixed number concentration of particles (10(8) particles/ml), there was a sulfuric acid concentration-dependent decrease in PC, pH(i) and [Ca2+](i). Furthermore, at a fixed mass concentration (350 mu g SO42-/m(3)), sulfuric acid layered carbon particles at 10(8) particles/ml but not at other number concentrations decreased pH(i) of macrophages. The number concentration of sulfuric acid layered carbon particles did not affect PC or [Ca2+](i). These results suggest that there is a threshold for both number concentration and mass concentration for the aerosols to produce a biological response, and that epidemiologic studies should consider other aerosol characteristics in addition to mass when attempting to relate health endpoints to ambient pollutant exposures