ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the change in protein expression of peroxiredoxin I (Prx I) during pulmonary fibrosis among rats exposed to silica dust and to investigate the role of Prx I in pulmonary fibrosis.</p><p><b>METHODS</b>Ninety male Wistar rats were randomly divided into control group (n = 60) and experimental group (n = 30). The control group received intratracheal perfusion of saline (1 ml), while the experimental group received intratracheal perfusion of suspension of silica dust (50 mg/ml) to establish a rat model of silicosis. At 1, 2, 3, 4, 6, or 8 weeks after treatment, 10 rats in control group and 5 rats in experimental group were sacrificed. The lung tissues were collected for conventional pathological observation. The protein expression of Prx I at each time point was measured by immunohistochemistry and Western blot.</p><p><b>RESULTS</b>Among the rats exposed to silica dust, Prx I was seen in the form of brown particles that were mainly distributed in the alveolar septa and the cytoplasm of alveolar epithelial cells, macrophages, vascular endothelial cells, and smooth muscle cells around the blood vessels and tracheae. The control group showed weak protein expression of Prx I, and the experimental group had significantly higher protein expression of Prx I than the control group at all time points (P < 0.05). In the experimental group, the protein expression of Prx I was upregulated significantly at 1 and 2 weeks and decreased at 3∼8 weeks.</p><p><b>CONCLUSION</b>The change in protein expression of Prx I may be one of the important causes of the onset and development of pulmonary fibrosis in rats exposed to free silica.</p>