Insufficient information is available to establish environmental standards for constituents of oxidant-particulate pollution so as to avoid adverse effects on the respiratory system in normal subjects and individuals with pulmonary disease. While problems in obtaining accurate assessments from inhaled pollutants are formidable, it should be easier to set rational guidelines based on human exposures. We have constructed an environmental chamber that can accurately deliver particulate and gaseous pollutants of known concentrations for up to 48 hours. We propose to investigate whether exposure to NO2 alone, and in combination with other pollutants, at relevant ambient concentrations increases airway inflammation, pro-inflammatory cytokines, and susceptibility to respiratory infection, the three major factors contributing to airway dysfunction in asthmatics. Because asthma prevalence and morbidity is increasing most rapidly in minorities, we will actively recruit Blacks to comprise 1/2 of our initial asthmatic study population. Alterations in lung function will be detected by pulmonary function tests that have sufficient sensitivity to detect changes in lung function before symptoms occur. In normal and asthmatic subjects, mechanisms of injury will be studied using fiberoptic bronchoscopy with bronchoalveolar lavage, brush biopsies, and endobronchial biopsies after pollutant exposure. We will examine changes in pro-inflammatory cytokines by measuring protein product in bronchoalveolar lavage fluid and gene expression in alveolar macrophages and bronchial epithelial cells. A quantitative multiplex competitive reverse transcriptase-polymerase chain reaction method recently developed in our laboratory will be used to measure gene expression in bronchial epithelial cells since the cells obtained by brush biopsies are limited. Pollutant-induced changes in gene expression will be compared in cells from normal and asthmatic subjects. Cell populations and subpopulations in lavage will be assessed by flow cytometry and cell surface markers and in lung tissue by morphometry following pollutant exposure. The susceptibility of the lower respiratory tract to respiratory viruses post-pollutant exposure will be evaluated by infecting both bronchial epithelial cells and alveolar macrophages with influenza and respiratory syncytial virus in vitro. We will quantitate release of infectious virus and production of proinflammatory and antiviral cytokines in response to infection in vitro. We will also examine changes in lymphocyte subset distribution and activation and expression of adhesion molecules on cells in broncho- alveolar lavage and peripheral blood. Since polymorphisms in cytokine genes may explain variability in responses among pollutant-exposed volunteers, we will bank genomic DNA from blood leukocytes prospectively. If there are differences between black and caucasian volunteers in terms of their cellular or biochemical response to pollutants, we will correlate these differences in cytokine production with polymorphisms in cytokine genes. Data obtained from these studies should permit a better assessment of adverse health effects from inhalation of ambient air pollutants as well as an improved understanding of mechanisms of toxicity.
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