[Differential analysis of two-dimensional gel electrophoresis profiles in lung tissue of rats exposed to silica early].

Objective: To analyze the differences of lung tissue proteins in rats exposed to silica early by using comparative proteomics method and investigate the related mechanism with the occurrence and development of silicosis.

Methods: Adult male Wistar rats were randomly divided into control group and silica-treated group. The animal model was established by intratracheal (IT) instillation with silica suspension. On the 14th day after establishment of animal model, rats were sacrificed and lung tissues were collected. The total proteins were separated by means of two-dimensional gel electrophoresis (2-DE) and the differentially expressed proteins were identified by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In addition, Western blotting was performed to verify the expression of certain candidate protein.

Results: Eleven differential expression protein spots were tested by MALDI-TOF-MS, and six proteins were identified. The levels of cathepsin D precursor, peroxiredoxin-1 (Prx-1), heat shock cognate 71 000 protein (HSP7C), heterogeneous nuclear ribonucleoprotein A3 (hnRNPA3) and fatty acid-binding protein (epidermal, E-FABP) were up-regulated in silica-treated group with the optical density (A) values. These values were 116.50+/-12.56, 148.75+/-22.40; 40.00+/-1.63, 66.00+/-13.93; 51.25+/-7.37, 92.75+/-8.69; 83.00+/-6.48, 122.75+/-24.62; 50.75+/-6.50, 93.50+/-23.10 and 100.25+/-19.99, 142.50+/-21.21 respectively. The statistical difference was observed as compared with control group (t=-2.51, -3.71, -7.28, -3.12, -3.56 and -2.90, P<0.05). However, SEC14-like protein 3 with the A values 153.00+/-11.28, 109.75+/-18.32 was down-regulated (t=4.02, P<0.01). Western blotting showed that in the expression of Prx-1 was higher in silica-treated group (0.61+/-0.05) than that in the control (0.35+/-0.05) (t=-7.24, P<0.01) when calculating the semi-quantification of this protein using ratio of optical density.

Conclusion: 2-DE pattern of lung tissue from rats exposed to silica has been established and six differentially expressed proteins have been identified. Our study is of help for further research of the mechanisms of silicosis.