| Objective: To establish a mouse model for Graves' disease by genetic immunization. To demonstrate the pathological change and explore the pathogenesis of liver damage of Graves' disease based on this model. To screen liver damage-related genes by analyzing changed gene expression patterns in damaged liver tissue of the murine model for Graves' disease.Methods: 60 6~8 week-old female BALB-c mice were used. 45 mice among them were immunized by hTSH-pcDNA at 0 week, 4th week, 8 th week and 12th week, while another 15 mice used as controls were injected with saline. All mice were sacrificed at 16 th week. The changes of weight, TsAb, TSH, TT4 and ALT were analyzed. At 16th week, their thyroids were removed to weigh and examine histologically, and their livers were observed with electron microscope. According to TsAb at 16th week, all mice were devided into Graves' disease group (immunized mice with elevated TsAb), positive control group (immunized mice with normal TsAb) and blank control group (normal mice). Changes of ALT and liver tissue observed by electron microscope were demonstrated. The correlation among TsAb, TT4 and ALT in Graves' disease group were analyzed. Graves' disease BALB-c mice were divided into two subgroups according to ALT : control subgroup( normal ALT levels); liver-damage subgroup( increased ALT levels). The fluorescent labeled DNA probes were prepared from mRNA, which were extracted from the liver tissue both of the control (Cy3 fluorescein) and liver-damage Graves' disease mice(Cy5 fluorescein). Two kinds of probes were then hybridized against BioDoor Genechip including 1500 reported genes and 2500 unreported genes, the fluorescent signals were scanned by Scan Array4000 scaning apparatus and analyzed by GenePix Pro 3.0 software. All processes were repeated twice. The differentially expressed genes were tested by RT-PCR. Result: TsAb increased in 14 immunized mice at 16 th week, accompanied by typical features of Graves' disease such as reduced TSH, elevated TT4, increased thyroid weight, lymphocytic infiltration in the thyroid tissue and body weight loss. TsAb and TT4, as well as TsAb and the weight of thyroid gland, showed significant positivecorrelation in Graves' disease mice. At the end of the study, ALT levels of control mice and immunized mice without Graves' disease were normal, but they increased in 64.3% of Graves' diseases mice. Graves' disease group was divided into two subgroups according to ALT levels at16 th week. TsAb or TT4 levels of elevated ALT subgroup were significantly higher than which in normal ALT subgroup. Electron microscopic examination demonstrated the following changes in Graves' disease mice with elevated ALT. The intercellular space of liver cells became broader, deeply incisura can be seen in some liver cell nucleus, The mitochondria were enlarged obviously. There was a large quantity of lipid droplet in liver cells, and lipofuscin deposition can be seen easily, which also could be found in cholangioles. In Graves' disease mice with normal ALT level, mitochondria were enlarged slightly, less lipid droplet was found in liver cells of these mice. No alteration was observed in mice of group B and group C by electron microscopic examination.The study of gene expression profile in liver tissue in Graves' disease mice showed, (1) There were 17 genes altered in gene expression profile in Graves' disease mice with increased ALT, showing consistent changes in expression level of at least 1.7 folds, in which 6 genes were reported while 11 genes were new. (2) Among reported genes, the expression level of 2 genes were up-regulated while 4 genes down-regulated significantly in liver tissue of Graves' disease mice with increased ALT, especially the xanthine dehydrogenase (up-regulated, changes in expression level ≥3 folds), Prss8 and glucokinase activity related gene1 (down-regulated, changes in expression level ≥3 folds). Briefly, we successfully established a mouse model for Graves' disease by genetic immunization, illustrated the pathologi...
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