The Use of Quantitative Two-dimensional Gel Electrophoresis to Analyze Changes in Alveolar Macrophage Proteins in Humans Exposed to Ozone

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Abstract
Acute exposure of humans to 0.4 ppm ozone is known to cause production of components that mediate inflammation and damage in the lung. However, ozone may cause even more extensive changes in the lung than those currently measured by traditional enzymatic or immunologic methods. The contribution of alveolar macrophages to these processes is not well understood. Therefore we have used molecular techniques to measure changes in the total spectrum of alveolar macrophage proteins in humans exposed to ozone. In this study, 8 human volunteers were each exposed to 0.4 ppm ozone and to filtered air for 2 h with intermittent exercise. Eighteen hours later, bronchoalveolar lavage was performed and alveolar macrophages were isolated. Changes in proteins made by these cells after air or ozone exposure were analyzed by high-resolution two-dimensional gel electrophoresis, using computerized densitometry to quantify changes in individual proteins. Of the nearly 900 proteins analyzed, 45 (5.1%) were synthesized at a significantly increased rate following ozone exposure, while 78 (8.8%) were synthesized at a significantly reduced rate. These results indicate that exposure of humans to ozone causes extensive changes in the spectrum of macrophage proteins being produced. Quantitative two-dimensional gel electrophoresis is a highly sensitive technique that may reveal much more information about the in vivo effects of a pollutant than has previously been available. Furthermore, the ability to survey large numbers of macrophage proteins after exposure to various inhaled pollutants may allow a better understanding of the mechanisms of action of these agents, as well as provide new biomarkers of pollutant exposure.