Faculty Bibliography

Beryllium (Be) has physical-chemical properties, including low density and high tensile strength, which make it useful in the manufacture of products ranging from space shuttles to golf clubs. Despite its utility, a number of standard setting agencies have determined that beryllium is a carcinogen. Only a limited number of studies, however, have addressed the underlying mechanisms of the carcinogenicity and mutagenicity of beryllium. Importantly, mutation and chromosomal aberration assays have yielded somewhat contradictory results for beryllium compounds and whereas bacterial tests were largely negative, mammalian test systems showed evidence of beryllium-induced mutations, chromosomal aberrations, and cell transformation. Although inter-laboratory differences may play a role in the variability observed in genotoxicity assays, it is more likely that the different chemical forms of beryllium have a significant effect on mutagenicity and carcinogenicity. Because workers are predominantly exposed to airborne particles which are generated during the machining of beryllium metal, ceramics, or alloys, testing of the mechanisms of the mutagenic and carcinogenic activity of beryllium should be performed with relevant chemical forms of beryllium

There are limited data on the efficacy of procedures for adapting rodents to restraint in nose-only holders. We examined: (1) What effect does restraint in nose-only holders have on heart rate and body temperature? (2) Does a gradual increase in the duration of restraint facilitate adaptation? (3) How long does it take for rodents to become fully adapted to nose-only holders? (4) Do rats and mice respond and adapt similarly to restraint in nose only holders? Heart rate and body temperature were monitored as measures of stress using electrocardiograph (ECG) transmitters in male C57Bl/6J mice and Sprague-Dawley rats. In naive animals during the first hour of restraint, heart rate increased by 58 beats per minute (BPM) (18.6%) in rats and by 174 BPM (32.3%) in mice as compared to cage controls. Temperature increased by 2 degrees C in mice and was unchanged in rats compared to cage controls. Heart rate and temperature values remained within normal physiologic values during restraint. In rats, the response to restraint in nose-only holders was the same after 4 days regardless of whether the duration of restraint was increased gradually to 4 h/day or kept constant at 4 h/day. In mice, the group that was gradually adapted had a statistically significant higher heart rate and temperature after 4 days than the fixed-duration adapted group. Rats and mice restrained for 4 h/day every day showed a gradual decrease in heart rate and temperature over time. Full adaptation to restraint required 14 days of fixed-duration daily restraint

The initiation and maintenance of airway immune responses in Th2 type allergic diseases such as asthma are dependent on the specific activation of local airway dendritic cells (DCs). The cytokine microenvironment, produced by local cells, influences the recruitment of specific subsets of immature DCs and their subsequent maturation. In the airway, DCs reside in close proximity to airway epithelial cells (AECs). We examined the ability of primary culture human bronchial epithelial cells (HBECs) to synthesize and secrete the recently described CC-chemokine, MIP-3alpha/CCL20. MIP-3alpha/CCL20 is the unique chemokine ligand for CCR6, a receptor with a restricted distribution. MIP-3alpha/CCL20 induces selective migration of DCs because CCR6 is expressed on some immature DCs but not on CD14+ DC precursors or mature DCs. HBECs were stimulated with pro-inflammatory cytokines tumor necrosis factor-alpha and interleukin (IL)-1beta or, because of their critical role in allergic diseases, IL-4 and IL-13. Cells were also exposed to small size-fractions of ambient particulate matter. Each of these stimuli induced MIP-3alpha/CCL20 gene and protein expression. Moreover, these agents upregulated mitogen-activated protein kinase pathways in HBECs. Inhibition of the ERK1/2 pathway or p38 reduced cytokine-induced MIP-3alpha/CCL20 expression. These data suggest a mechanism by which AEC may facilitate recruitment of DC subsets to the airway

Respiratory-tract infection, specifically pneumonia, contributes substantially to the increased morbidity and mortality among elderly individuals exposed to airborne particulate matter of <10 micro m diameter (PM(10)). These epidemiological findings suggest that PM(10) may act as an immunosuppressive factor that can undermine normal pulmonary antimicrobial defense mechanisms. To investigate whether, and how, compromised pulmonary immunocompetence might contribute to increased mortality, two sets of laboratory studies were performed. The first examined the effects of a single inhalation exposure to concentrated ambient PM(2.5) (CAPS) from New York City air on pulmonary/systemic immunity and on the susceptibility of exposed aged rats to subsequent infection with Streptococcus pneumoniae. The second set of studies determined whether CAPS exposure, at a concentration approximating or somewhat greater than the promulgated 24-h NAAQS of 65 micro g/m(3), could exacerbate an ongoing infection. Taken together, results demonstrated that a single exposure of healthy animals to CAPS had little effect on pulmonary immune function or bacterial clearance during subsequent challenge with S. pneumoniae. Alterna-tively, CAPS exposure of previously infected rats significantly increased bacterial burdens and decreased percentages of lavageable neutrophils and proinflammatory cytokine levels compared to those in infected filtered-air-exposed controls. These studies demonstrate that a single exposure to ambient PM(2.5) compromises a host's ability to handle ongoing pneumococcal infections and support the epidemiological findings of increased pneumonia-related deaths in ambient PM-exposed elderly individuals

Environmental pollutants, including ambient particulate matter (PM), increase respiratory morbidity. Studies of model PM particles, including residual oil fly ash and freshly generated diesel exhaust particles, have demonstrated that PM affects inflammatory airway responses. Neither of these particles completely represents ambient PM, and therefore questions remain about ambient particulates. We hypothesized that ambient PM of different size fractions collected from an urban environment (New York City air), would activate primary culture human bronchial epithelial cells (HBECs). Because of the importance of granulocyte-macrophage colony-stimulating factor (GM-CSF) on inflammatory and immunomodulatory processes, we focused our studies on this cytokine. We demonstrated that the smallest size fraction (ultrafine/fine; < 0.18 micro m) of ambient PM (11 micro g/cm(2)), upregulated GM-CSF production (2-fold increase). The absence of effect of carbon particles of similar size, and the day-to-day variation in response, suggested that the chemical composition, but not the particle itself, was necessary for GM-CSF induction. Activation of the extracellular signal-regulated kinase and the p38 mitogen-activated protein kinase was associated with, and necessary for, GM-CSF release. These studies serve to corroborate and extend those on model particles. Moreover, they emphasize the role of the smallest size ambient particles in airway epithelial cell responses

Mutations in the p53 gene have been implicated to play an important role in the development of various human cancers. To evaluate the importance of p53 in lung cancer, a transgenic mouse model was established by utilizing the Clara cell secretory protein (CCSP) promoter to target the expression of a dominant-negative mutant form of p53 (dnp53) in the lung. In two transgenic CCSP-dnp53 founder lines, the dnp53 protein was expressed exclusively in the lungs. The incidence of spontaneous lung cancer in 18-month-old transgenic mice was 45%, whereas that in age-matched control mice was 20%. The relative risk of lung tumors in CCSP-dnp53 mice was 2.3 times that of wild-type mice (exact confidence limits of 0.69, 17.5). In addition to the increased incidence of spontaneous lung tumor, these mice were more susceptible to the development of lung adenocarcinoma after exposure to benzo(a)pyrene (BaP). Six months after intratracheal instillation of benzo(a)pyrene, the tumor incidence in wild-type and CCSP-dnp53 mice was 39% and 73%, respectively. The risk of lung tumors was 25.3 times greater in BaP-treated mice adjusted for transgene expression (95% confidence limits of 3.29, 678, mid-p corrected). These results suggest that p53 function is important for protecting mice from both spontaneous and BaP-induced lung cancers

Although acute exposure to ozone (03*) has been shown to influence the severity and prevalence of airway hyperresponsiveness, information has been lacking on effects due to long-term exposure at relatively low exposure concentrations. The goals of this study were to determine whether long-term repeated ozone exposures could induce nonspecific hyperresponsiveness in normal, nonatopic (nonsensitized) animals, whether such exposure could exacerbate the preexisting hyperresponsive state in atopic (sensitized) animals, or both. The study was also designed to determine whether gender modulated airway responsiveness related to ozone exposure. Airway responsiveness was measured during and after exposure to 0.1 and 0.3 ppm ozone for 4 hours/day, 4 days/week for 24 weeks in normal, nonsensitized guinea pigs, in guinea pigs sensitized to an allergen (ovalbumin) prior to initiation of ozone exposures, and in animals sensitized concurrently with ozone exposures. Both male and female animals were studied. Ozone exposure did not produce airway hyperresponsiveness in nonsensitized animals. Ozone exposure did exacerbate airway hyperresponsiveness to specific and nonspecific bronchoprovocation in both groups of sensitized animals, and this effect persisted at least 4 weeks after the end of the exposures. Although the overall degree of airway responsiveness did differ between genders (males had more responsive airways than did females), the airway response to ozone exposure did not differ between the two groups. Ozone-induced effects upon airway responsiveness were not associated with the number of pulmonary eosinophils or with any chronic pulmonary inflammatory response. Levels of antigen-specific antibodies increased in sensitized animals, and a significant correlation was observed between airway responsiveness and antibody levels. The results of this study provide support for a role of ambient ozone exposure in exacerbation of airway dysfunction in persons with atopy

While acute exposures to ozone (O(3)) can alter airway responsiveness, effects from long-term exposures at low concentrations are less clear. This study assessed whether such exposures could induce nonspecific hyperresponsiveness in nonatopic (nonsensitized) guinea pigs and/or could exacerbate the pre-existing hyperresponsive state in atopic (sensitized) animals, and whether gender was a factor modulating any effect of O(3). Responsiveness was measured during and following exposures to 0.1 and 0.3 ppm O(3) for 4 h/day, 4 days/wk for 24 wk in male and female nonsensitized animals, those sensitized to allergen (ovalbumin) prior to initiation of O(3) exposures, and those sensitized concurrently with exposures. Ozone did not produce hyperresponsiveness in nonsensitized animals, but did exacerbate hyperresponsiveness to both specific and nonspecific bronchoprovocation challenges in sensitized animals, an effect that persisted through at least 4 wk after exposures ended. Gender was not a factor modulating response to O(3). Induced effects on responsiveness were not associated with numbers of eosinophils in the lungs nor with any chronic pulmonary inflammatory response, but were correlated with antigen-specific antibodies in blood. This study supports a role for chronic O(3) exposure in the exacerbation of airways dysfunction in a certain segment of the general population, namely, those demonstrating atopy