OBJECTIVETo explore the pathological changes of pulmonary fibrosis induced by SiO2 in rats and pigs.

METHODSThe 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.

RESULTS(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.

CONCLUSIONThe development of pulmonary fibrosis in silicosis models corresponded with the process from macrophages alveolar inflammation to pulmonary fibrosis.