Differential Gene Expression And Key Signal Transduction Pathways Of Pulmonary Fibrosis Of Rats Exposed To Silica

Objective: The aim of this study was to explore the molecular mechanism of silicosis. Differential gene expression profiling in pulmonary tissue of rats exposed to silica was carried out and the function and key biology pathways of these differential genes were explored which in order to reveal formation mechanism for silicosis based on the Genetic level.Methods: A total of 80 wistar rats were divided into two experimental groups randomly: the control group and silicosis group (silica-instilled group) .The two groups have five time points respectively,as 1d,7d,14d,21d,28, and eight rats each group. After lightly anesthetized with pentobarbital, rats were received a single intratracheal instillation of 1ml 50mg/ml silica suspension in silica-treated group. In control group, rats were treated in the same way but instillation of 1 ml sterilized saline instead. At the 1d, 7d, 14d, 21d, and 28d after establishment of animal models, eight rats in each group were sacrificed, and lungs were removed and stored immediately in liquid nitrogen. The changes of lung histomorphology of rats were observed by HE staining of histological section. I, III type collagens of lung tissue were stained by sirius red. A gene chip system (Illumina Company, USA) was used in studying gene profile of lung total RNA in rats exposed to silica. Following scanning and standardizing (Illumina Company, USA), Fold was calculated and thus differential expressed gene could be got. Matlab and KEGG software were used in gene functional annotation and classification.Results: The staining results of HE and sirius red both show success of rats silicosis model. Compared with the control group, 2 694 genes were differential expressed including 290 genes were up-regulated at each time point, and 90 clusters could be classified by Maylab analysis software combined with GO database. The clusters involved genes: (1) cell bio-chemical reaction related genes for cell cycle, differentiation and proliferation, apoptosis, cytoskeleton, signal transduction, transfer and stress reaction, DNA damage and heat shock protein; (2) metabolism and transcription related genes of DNA, RNA and protein; (3) enzyme related genes including oxidoreductase, phosphatase, hydrolase, glutathione transferase and protein kinase; (4) cytokines, chemokines and immunological reaction related genes. Also, KEGG pathways analysis showed that 141 pathways involved in the process of pulmonary fibrosis induced by silica, and including 48 pathways were more significant than others (p<0.01), especially MAPK pathway.Conclusions: Our experiment successfully shows the differential gene expression profiling in pulmonary tissue of rats exposed to silica. Through the researches of key pathways related to silicosis, we confirm that a complex network of gene signal transduction pathway exists in the development of silicosis.