Objective: To investigate gene and protein expression level of thyrotropin-receptor (TSHR) in retro-bulbar connective tissue and fat tissue in patients with thyroid-associated ophthalmopathy (TAO).
Methods: Retro-bulbar tissues specimens were obtained from 11 cases of TAO patients and 10 control cases during the operation. RNA was extracted from the tissue specimens using single-step method of acid guanidinium-thiocyanate-phenol-chloroform extraction and TSHR mRNA was analyzed by reverse transcription polymerase chain reaction (RT-PCR). Immunochemistry staining was performed in patients expressed TSHR, using a mouse polyclonal anti-TSHR peptide antibody to observe protein expression level of TSHR.
Results: The size of TSHR mRNA segment is 521 bp. The rate of TSHR mRNA expression in TAO retro-bulbar tissue was 91% and was 20% in the control cases, the former was significantly greater than the later. Protein expression rate was 66.7% in TAO patients, and was negative in the controls.
Conclusions: High TSHR mRNA expression level and protein level in TAO retro-bulbar tissue and no expression in control tissue indicate that TSHR exists as a common antigen in the orbit and thyroid, and plays a key role in the pathogenesis of TAO.