Diesel Exhaust

This report evaluates airway inflammatory responses and expression of the enzyme neprilysin in response to diesel exhaust particle exposure. Dr. Wong and colleagues hypothesized that components of diesel exhaust decrease neprilysin levels in airways, leading to airway function disorders and heightened responses to diesel exhaust. They exposed normal mice, mice genetically deficient in neprilysin, human subjects, and human airway epithelial cells to diesel exhaust particles and measured airway inflammation, neprilysin expression, and any unique responses in neprilysin-deficient mice.

This report explores the possible physiological basis for epidemiologic results suggesting that people over the age of 55 are more sensitive than younger people to the effects of exposure to particulate matter. Dr. Debra Laskin and colleagues hypothesized that this sensitivity resulted from the lung cells of the elderly producing less of the cytokine tumor necrosis factor-α (a cell protein involved in systemic inflammation), as compared with the lung cells of the young after exposure to air pollution.

This report describes a study to investigate the suggested association between exposure to traffic-derived pollution and increases in symptoms of airway diseases, including exacerbation of asthma. Dr. Jack Harkema and colleagues assessed the effects of two pollutant mixtures, concentrated ambient particles (CAPs) and diesel exhaust, on airway inflammatory and allergic responses in a rodent model of asthma. The study was one part of an HEI 3-study program of animal and human research on these important questions.