ABSTRACT
<p><b>OBJECTIVE</b>To explore the pathological changes of pulmonary fibrosis induced by SiO2 in rats and pigs.</p><p><b>METHODS</b>The silicosis models in rats and pigs were established by non-exposure method. The pathologic changes in lung tissues of rats and pigs were observed with HE staining under a light microscopy and under a transmission electron microscopy (TEM), the expression of cytokines was detected by immunohistochemistry.</p><p><b>RESULTS</b>(1) The main pathologic changes of silicosis models in rats and pigs included: in 7 ∼ 15 days after treatment, silica dusts, dust cells, a lot of macrophages, lung epithelial cells, a few neutrophils, macrophage alveolar inflammation and nodules of stage I were found in alveolar space; in 30 ∼ 90 days after treatment, many nodules of stage I-III or IV with lymphocytes infiltration were observed in respiratory bronchioles, alveoli, interlobular septa, the subpleural and around blood vessels and bronchi. (2) The expression levels of CK protein, SP-A protein, CD68, b-FGF, TNF-α, IL-6, TGF-β1, NFKappa/P50, Kappa/P65 and VEGF reduced with exposure time, but still were higher than those of the control. (3) The shed alveolar type I cells, proliferation of alveolar type II cells or macrophages and activated cellular function induced by silica were observed under TEM.</p><p><b>CONCLUSION</b>The development of pulmonary fibrosis in silicosis models corresponded with the process from macrophages alveolar inflammation to pulmonary fibrosis.</p>