[Establishment of an animal model for thyroid associated ophthalmopathy by treatment of mice with human thyrotropin receptors-activated splenocytes]

Abstract

Objective: To establish an animal model for thyroid-associated ophthalmopathy (TAO) by treatment of homoimmune BALB/c mice with human thyrotropin receptors ( hTSHR )-activated splenocytes. METHODS Twenty three BALB/c mice were randomly divided into group A and B, which were immune with recombinant plasmid pcDNA3. 1/hTSHR or blank plasmid pcDNA3. 1 for 3 times at 3-week intervals, respectively. Mice in these two groups were sacrificed 18 weeks after immunization and the splenocytes were isolated. Other 26 homoimmune BALB/c mice were divided randomly into group C and group D which received splenocytes from group A and group B, respectively. Four weeks later the orbital tissues were harvested for pathological examination and serum was collected for TT4, TSH and TRAb measurements. RESULTS After immunization with recombinant plasmid pcDNA3. l/hTSHR, orbital tissues displayed edema and mucinous degeneration in 25% of mice but no proliferation of adipose tissue and fibrous tissue (group A). After immunization with hTSHR-activated splenocytes, orbital tissues displayed proliferation of adipose tissues and fibrous tissues, degeneration and disruption of muscular fibers microscopically in 50% of mice (group C). Under electronic microscope, expansion of smooth endoplasmic reticulum and disorder of myofibrils were found in these mice. In all mice from group B and group D, orbital tissues were normal histologically. After immunization with splenocytes, serum total T4 levels were significantly elevated ( P = 0. 036) in group C (7. 130+/-1.017) [microg /dl when compared with group D (6. 431+/-0. 573) microg /dl. Serum TSH levels were significantly reduced (P = 0. 020) in group C (0. 070+/-0. 032) microIU/ml when compared with group D (0. 098+/-0. 020) microIU/ml. Serum TRAb levels were slightly increased in group C(0. 202 +/-0. 067) as compared to group D(0. 151+/-0. 055) , however, this difference was statistically non-significant (P = 0. 055 ).

Conclusions: TAO animal model established by immunizing homoimmune BALB/c mice with hTSHR-activated splenocytes is similar to human TAO in histological characteristics and is a feasible and reliable experimental method. Our study also proves that the thyrotropin receptor and T cell aiming directly at this auto-antigen play important roles in the autoimmune process of TAO.