Faculty Bibliography

Inhalation of cadmium oxide (CdO) is a significant form of human exposure to cadmium (Cd). Furthermore, there is epidemiological and experimental data relating Cd inhalation with lung cancer. Animal studies indicate that rats are more susceptible to Cd-induced lung cancer than mice, but interstrain sensitivity differences to Cd-induced pulmonary inflammation or carcinogenesis have not been addressed in either species. We compared pulmonary inflammatory processes in Wistar Furth (WF) rats with those in C57 and DBA mice exposed to freshly generated CdO fumes in nose-only inhalation chambers. Animals were exposed to 1 mg Cd/m3 for 3 hr and terminated immediately or 1, 3, and 5 days after exposure. Control animals were exposed to air/argon furnace gases. Cd-induced lung injury was assessed by bronchoalveolar lavage fluid (BALF) analyses, histopathology, and immunohistochemical detection of cell proliferation. Inhalation of CdO resulted in pulmonary inflammatory processes that varied widely across species and strains. C57 mice responded with faster and greater influx of neutrophils and proliferation of alveolar macrophages, type II epithelial cells, and bronchiolar epithelial cells compared to DBA mice or WF rats. DBA mice retained a greater percentage of inhaled Cd in the lungs and presented higher levels of BALF protein than C57 mice or rats. In comparison to mice, WF rats responded with a more transient inflammatory response in BALF parameters and higher degree of acute inflammation in lung tissue. The more pronounced proliferation of alveolar and bronchiolar epithelial cells observed in C57 mice might indicate higher susceptibility of this mice strain to Cd-induced lung carcinogenesis compared to DBA mice or WF rats. Furthermore, the present results of fewer inflammatory cells and lower proliferation of epithelial cells in DBA mice in association with our previous observation of higher Cd-induced metallothionein protein in this strain suggest that DBA might be less susceptible to the pulmonary carcinogenic effects of inhaled Cd than C57 mice or WF rats. We conclude that mice might not necessarily be more resistant than rats to the carcinogenic effects of inhaled Cd, since intraspecies susceptibility differences are strongly suggested by the present data. An extrapolation of this conclusion is that genetic variations in the human population may determine individual sensitivity differences to inhaled Cd

Although several lines of evidence have suggested that oxidizing agents can induce heat shock proteins (HSPs) in vitro, little is known about the induction of HSPs during in vivo exposure to oxidants. Guinea pigs were exposed to ozone for 6 h and euthanized up to 72 h later. Proteins from lavage cells and lung tissue were characterized by immunoblotting with 72- and 73/72-kDa HSP monoclonal antibodies. Although 73-kDa HSP was expressed constituitively in lung tissue, it was not affected by ozone. In contrast, 72-kDa HSP was significantly increased in lavage cells and lung tissue of animals exposed to 0.4 and 0.66 parts/million of ozone. Both heat treatment and arsenite induced 72-kDa HSP in cultured alveolar macrophages. The increase in 72-kDa HSP in the lavage cell pellet peaked at 24 h after ozone, whereas the influx of polymorphonuclear leukocytes peaked at 4 h. Examination of the induction of HSPs by ozone may provide clues to the development of ozone tolerance in humans and animals

Results from animal and preliminary human exposure studies have called into question whether the 5 mg/m3 8-hour time-weighted average threshold limit value (TLV) for zinc oxide fume is sufficient to protect workers against metal fume fever. The objectives of this study were to determine the clinical effects of exposures to low concentrations of zinc oxide and to ascertain whether these exposures elevated circulating levels of specific cytokines, which could account for the symptoms of the metal fume fever syndrome. Thirteen resting naive subjects inhaled, on separate days, air and 2.5 and 5 mg/m3 of furnace-generated zinc oxide fume for 2 hours. Subjects recorded symptoms and temperature and had blood drawn before and after each exposure. The mean (+/- SE) maximum rise in oral temperature at 6 to 12 hours after exposure was 1.4 +/- 0.3 degrees F after 5 mg/m3, compared with 0.6 +/- 0.5 degrees F after air exposure (P < 0.05). Mean temperature was also elevated after exposure to 2.5 mg/m3 zinc oxide (1.2 +/- 0.3 degrees F). In a parallel fashion, plasma levels of interleukin 6 (IL-6), a pyrogen, were significantly elevated after exposure to 5 mg/m3 zinc oxide. Mean IL-6 values (pg/mL) at pre-exposure and at 3 and 6 hours post-exposure were 1.9 (+/- 0.6), 2.8 (+/- 0.7), and 2.9 (+/- 0.6), respectively, on the air day and 1.6 (+/- 0.6), 4.4 (+/- 1.2), and 6.4 (+/- 1.1) on the 5 mg/m3 zinc oxide day. Zinc oxide exposure did not significantly affect plasma levels of tumor necrosis factor. Total symptom scores peaked 9 hours after the 5 mg/m3 zinc oxide exposure. Myalgias, cough, and fatigue were the predominant symptoms reported. Inhalation of zinc oxide for 2 hours at the current TLV of 5 mg/m3 produces fever and symptoms along with elevation in plasma IL-6 levels

To examine the biological plausibility of the adverse health effects of ambient paniculate matter (PM), we have studied the pulmonary and cardiovascular effects of ambient PM in an animal model of pulmonary hypertension. A centrifugal aerosol concentrator was used to concentrate ambient paniculate matter up to 10-fold. Normal and monocrotaline-treated rats were exposed nose-only for 3 hrs to filtered air or concentrated ambient PM ranging from 160 to 900 ?g/m3. At 3 hrs post-exposure, the percentage of neutrophils in peripheral blood was significantly elevated in PM-exposed animals while the percentage of lymphocytes was decreased. This demargination of neutrophils occurred in both normal and monocrotaline-treated animals. The hematological changes returned to control levels by 24 hrs after exposure. Evidence that these changes were a result of exposure to the particulate and not the gaseous components of urban air was demonstrated by a lack of hematological changes in animals exposed to HEPA-filtered air from the centrifugal concentrator. Heart rate and core temperature were monitored in unrestrained normal and monocrotaline-treated rats for 1 hr prior to, during, and 24 hrs after, single or multiple exposures to PM. No consistent changes in heart rate or core temperature were observed after exposure to concentrated ambient PM. Pulmonary injury, as evidenced by increased protein levels in lavage fluid, occurred in monocrotaline-treated but not in normal animals exposed to greater than 360 ?g/m3 PM. The observed pattern of hematological changes suggests an activation of the sympathetic stress response which appeared to manifest pulmonary injury only in animals with compromised health

Humans exhibit an acute inflammatory response in the lungs after controlled laboratory exposure to ozone. The present study was designed to test whether biomarkers of inflammation are detectable in humans exposed to ozone and associated copollutants under natural conditions outdoors. Bronchoscopy with bronchoalveolar lavage (BAL) was carried out on 19 normal volunteer joggers from Governors Island, NY, who exercised in the afternoon during the 1992 summer (S1) season. Fifteen subjects were retested during the following, low ozone, winter season (W). The BAL protocol involved an initial instillation of 20 ml saline followed by four sequential 50-ml saline washes carried out in both the right middle lobe and the lingula. The eight 50-ml samples were pooled as the 'alveolar' sample. Analyses performed on the alveolar lavage samples included cell differentials, release of IL-8, TNF-alpha, and reactive oxygen species (ROS) by pooled cells, and levels of IL-8, protein, LDH, fibronectin, alpha1-antitrypsin (alpha1-AT), complement fragment 3a (C3a), and prostaglandin E2 (PGE2) in lavage fluids. Release of ROS by stimulated BAL cells was lower in S1 than in W (p = 0.03). In contrast, LDH levels in BAL fluids were 2-fold higher in S1 than in W (p = 0.02), as were IL-8 (p = 0.12) and PGE2 (p = 0.06). These results suggest a possible ongoing inflammatory response in the lungs of recreational joggers exposed to ozone and associated copollutants during the summer months

This study examined the production of stored mucosubtances in rats after repeated exposure to aerosolized endotoxin, a common contaminant of bioaerosols. Male Fischer 344 rats were exposed to aerosolized saline (sham control) or endotoxin (target concentrations of 0.05, 0.5, and 5.0 micrograms/m3) for 3 h/day, 5 days/week for 4 weeks. Following the final exposure, the left lung of each animal was lavaged and the right lung and nasal cavity were fixed with buffered formalin. Morphometric examination of Alcian blue/Periodic acid Schiffs-stained (AB/PAS) lung sections demonstrated dose-dependent increases in stored intraepithelial mucosubstances in the intrapulmonary airways of endotoxin-exposed rats. Threefold and eightfold increases in stored mucosubstances were observed in generation 5 airways of animals exposed to 0.5 or 5.0 microgram/m3 endotoxin, respectively (p < .05). This mucous cell metaplasia in the intrapulmonary airways was not accompanied by evidence of lung inflammation or increased AB/PAS-staining high molecular weight material in lavage fluid. Furthermore, despite significant deposition of endotoxin aerosols (mass median aerodynamic diameter of 1.9 microns) in the nasal cavity, no significant changes in stored mucosubstances were observed in the nasal septum. In animals repeatedly exposed to 5.0 micrograms/m3 endotoxin and allowed to recover for 1 month, stored mucosubstances in the intrapulmonary airway were still more than fivefold greater than control values. Thus, in rats, repeated exposure to inhaled endotoxin produced a persistent mucous cell metaplasia only in the intrapulmonary airways

The surfactant layer covering the gas-exchange region of the lung serves as the initial site of interaction with inhaled oxidant gases. Among the endogenous compounds potentially vulnerable to oxidative injury are surfactant proteins. This study focused on the effect of ozone on surfactant protein A (SP-A) function, content, and gene expression. To determine the time course of response to ozone, guinea pigs were exposed to 0.2-0.8 parts/million (ppm) ozone for 6 h and were killed up to 120 h postexposure. To determine the effect of repeated exposure, animals were exposed to 0.8 ppm ozone for 6 h/day and were killed on days 3 and 5. A significant increase in surfactant's ability to modulate the respiratory burst induced by phorbol 12-myristate 13-acetate in naive macrophages was observed at 24 h after a single 0.8 ppm ozone exposure. Because neutralizing antibodies to SP-A blunted this stimulatory effect, we hypothesized that ozone enhanced the modulatory role of SP-A in macrophage function. This alteration in function was accompanied by an influx of inflammatory cells and only marginal changes in SP-A levels as determined by an enzyme-linked immunosorbent assay. No significant changes in steady-state levels of SP-A mRNA were observed after single or repeated exposure to ozone. Thus the inflammation that accompanies in vivo ozone exposure may result in a change in the structure and thus functional role of SP-A in modulating macrophage activity

Occupational exposure to microbial-contaminated machining fluids is associated with a variety of adverse pulmonary effects including chronic bronchitis and increased sputum production. We have previously demonstrated in F344 rats that inhaled endotoxin can increase the amount of stored intraepithelial mucosubstances (Vs) in the respiratory tract. The purpose of the present study was to examine the effect of endotoxin-contaminated machining fluid aerosols on mucous production. Rats were exposed to aerosols of pyrogen-free water, 1 or 10 mg/m3 used machining fluid, or 10 mg/m3 unused machining fluid for 3 hr/day for 3 days. Twenty-four hours after the final exposure, right lung lobes were lavaged and the nasal cavity and left lung were fixed in formalin. The amount of Alcian blue/periodic acid-Schiff-stained mucosubstances was determined by morphometry. Exposure to 10 mg/m3 used machining fluid (equivalent to 0.8 micrograms/m3 endotoxin) produced a significant increase in Vs in the epithelial lining of both the nasal septum and intrapulmonary airways. These changes in Vs were accompanied by a significant increase in total cells and neutrophils in the lavage fluid. No changes in stored mucosubstances or lavage parameters were found in animals exposed to 1 mg/m3 used machining fluid aerosols. A significant increase in Vs was observed in the nasal septum but not in the intrapulmonary airways of animals exposed to 10 mg/m3 unused machining fluids (no measurable endotoxin). These results suggest that in addition to endotoxin, nonendotoxin components of machining fluids may contribute to the increase in sputum and chronic bronchitis reported for workers exposed to machining fluid aerosols

Occupational exposure to endotoxin-contaminated organic dusts is associated with a variety of adverse pulmonary effects, including chronic bronchitis and sputum production. We have previously demonstrated in F344 rats that inhaled endotoxin rapidly induces an increase in the volume of stored intraepithelial mucosubstances (Vs) in the respiratory tract. The present study examined whether endotoxin-contaminated cotton dust can produce a similar increase in Vs in this animal model. Rats were exposed to air or 1.5 to 15.0 mg/m3 cotton dust for 2 h/d for 3 d. Twenty-four hours after the final exposure, the nasal cavity and lungs were fixed in formalin and the presence of Alcian blue/periodic acid-Schiff-staining mucosubstances determined by morphometry. Exposure to cotton dust produced concentration-dependent changes in Vs in the nasal septum and intrapulmonary airways. Statistically significant increases in Vs were observed in the epithelial lining of the nasal septum of animals exposed to 5.3 and 14.5 mg/m3 cotton dust (equivalent to 2.8 and 8.9 micrograms/m3 endotoxin). Vs in the intrapulmonary airways was also significantly increased at these concentrations. No significant changes were observed in the nasal septum or intrapulmonary airways after exposure to 1.8 mg/m3 cotton dust. These results are consistent with the hypothesis that endotoxin may contribute to the increase in human cases of chronic bronchitis reported in occupational settings in which endotoxin-contaminated dusts are encountered

Components of the complement system are thought to play a role in the respiratory effects of inhaled organic dusts encountered in occupational settings such as grain storage sites and cotton mills. This hypothesis is based upon observations that grain dusts and endotoxin can activate complement in vitro and in vivo and that the complement system appears to contribute to the endotoxin-induced lung injury of septic shock. The present study examined whether the inflammatory effects of inhaled endotoxin and cotton dust were (1) blocked by decomplementing animals with cobra venom factor (CVF) or (2) present in animals genetically deficient in specific components of the complement system. In untreated and sham-treated guinea pigs, inhaled endotoxin produced significant increases in biochemical and cellular indices of pulmonary injury in bronchoalveolar lavage fluid. Treatment of guinea pigs with 200 units CVF/kg at 24 h prior to exposure did not block the biochemical and cellular changes produced by inhaled endotoxin or cotton dust. Guinea pigs deficient in the fourth component of complement (C4) also demonstrated evidence of pulmonary injury roughly equivalent to that of normal guinea pigs exposed to inhaled endotoxin or cotton dust. Finally, mice genetically deficient in the fifth component of complement (C5) did not exhibit a decreased pulmonary response to inhaled endotoxin compared to C5-sufficient mice. These studies suggest that despite in vitro and in vivo evidence of complement activation by endotoxin and extracts of organic dusts, the complement system may not play a major role in the acute respiratory effects of inhaled endotoxin and cotton dust