The Changes of Expression of Thyroid Specific Antigens in Aging / 대한내분비학회지

ABSTRACT

BACKGROUND: With the prevalence of serum antithyroglobulin(anti-TG) and antithyroperoxidase(anti-TPO) autoantibodies increasing with age, it has been suggested that changes of thyroid autoimmunity with aging are associated with endemic iodine intake. To understand the mechanism of aging-related increases of thyroid autoimmune response, we investigated the expression of thyroid specific autoantigens of aged phenotype, and compared them with those of young phenotype both in vivo and in vitro. METHODS: Sprague-Dawley rats were sacrificed at 5, 10 and 16 weeks(young), and at 23 months(aged). Their FRTL-5 thyroid cells were harvested at cell passages less than 10(fresh) or more than 30 (aged). The expression of thyroid autoantigens, sodium-iodide symporter(NIS), TSH receptor (TSHR), TG and TPO, were examined by northern blot analysis. To evaluate the effects of iodide, 1mM of NaI was added to the medium for 24 hours, and following incubation the expressions of MHC class I and class II were also examined. RESULTS: The expressions of TPO were markedly increased in the aged rats, and those of TG were moderately. However, NIS and TSHR showed no differences in their expression levels between aged rats and young rats. In vitro, there were no differences in the expressions of TG or TPO, nor of NIS or TSHR, between aged cells and fresh cells. Neither did Iodide exhibit any influence on the expression of MHC molecules in aged cells or fresh cells. CONCLUSION: The expression levels of TPO and TG were increased in aged rats, which may partially explain the mechanism of increasing thyroid autoimmunity with age.