An improved method for the establishment of a model of Graves' disease in BALB/c mice

Mouse model of Graves' orbitopathy induced by the immunization with TSHR A and IGF-1R α subunit gene

PURPOSE

The study aimed to establish a mouse model of Graves' disease (GD) with Graves' orbitopathy (GO; GD + GO) that can represent the clinical disease characteristics.

METHODS

A eukaryotic expression plasmid of insulin-like growth factor 1 receptor (IGF-1R) α subunit (pcDNA3.1/IGF-1Rα) and a thyrotropin receptor (TSHR) A subunit plasmid (pcDNA3.1/TSHR-289) were injected in female BALB/c mice followed by immediate electroporation to induce a GD + GO model. Grouping was performed according to the frequency of injection (2- to 4-week intervals) and type of injected plasmids: T: pcDNA3.1/TSHR-289( +), I: pcDNA3.1/IGF-1Rα( +), or co-injection T + I: pcDNA3.1/TSHR-289( +) and pcDNA3.1/IGF-1Rα( +). Serum TSH, T4, TSAb, TSBAb, body weight, and blood glucose levels were evaluated. Thyroid 99mTcO4- imaging and retrobulbar magnetic resonance imaging (MRI) were performed, and bilateral eye muscle volumes were measured. Immunohistochemistry and hematoxylin-eosin staining were performed on the relevant tissues, and semi-quantitative analysis was performed.

RESULTS

A total of 60% of mice (3/5, one mouse died) in the T group developed GD + GO. In the T + I group, 83.3% of mice (5/6) developed GD + GO. Mice in the I group did not develop GD. Compared with the control group, serum T4, TSAb, and TSBAb of the mice in the GD + GO model groups were increased to varying degrees (P < 0.05), and serum TSH and body weight were significantly lower compared to the control group (P < 0.05). The thyroid uptake capacity of 99mTcO4- and the volume of eye muscle of mice in the GD + GO group were significantly higher compared to the control group (P < 0.05). The thyroid and retrobulbar muscles of these mice showed varying inflammatory infiltration and interstitial muscle edema. The severity of GD + GO in the co-injection group was not related to injection frequency; however, GD and ocular signs in co-injection mice were more severe compared to the T group.

CONCLUSIONS

We successfully induced a GD + GO mouse model by a repeated co-injection of pcDNA3.1/IGF-1Rα and pcDNA3.1/TSHR-289 plasmids. Injection of pcDNA3.1/IGF-1Rα alone failed to induce GD. Co-injection of two plasmids induced more severe GD + GO than pcDNA3.1/TSHR-289( +) alone.

An improved mouse model of Graves disease by once immunization with Ad-TSHR289

The novel Graves disease (GD) model was established in BALB/c mice with recombinant adenovirus expressing the full-length human TSHR (Ad-TSHR289) by three times immunizations for nearly three months. Reducing the frequency of immunizations may shorten the modeling time to improve the efficiency of the study. In this study, female BALB/c mice were immunized one time with an adenovirus expressing the autoantigen thyroid-stimulating hormone receptor (Ad-TSHR289). At the 3, 6, 12, 17 weeks after the immunization, mice were sacrificed. The blood was collected and thyroids were removed. T3, T4, TRAB and thyroid weight/body weight (TW/BW) were tested. Compared with the Normal control (NC) group, the incidence of hyperthyroidism at 3, 6, 12 and 17 weeks after immunization were about 66.67%, 100%, 100%, and 100%. Meanwhile, the incidences of goiter were nearly 50%, 83.33%, 100% and 100% at the same stages. Therefore, modeling rates of GD were about 50%, 83.33%, 100%, 100% at 3, 6, 12 and 17 weeks after immunization. T3 in serum continues to increase from 3 weeks to 17 weeks after immunization. Serum TRAb reached to peak at 6 weeks and remained from 12 weeks after immunization, while T4 and TW/BW had kept steady from 6 weeks. There are positive correlations between T3, T4 and TRAb, TRAb and TW/BW, as well as T3, T4 and TW/BW. GD model can be constructed by primary immunization with Ad-TSHR289, which could be detected at 3 weeks and at least until the 17 weeks after primary immunization. It would improve the efficiency of GD research.