The expression of circulating rennin—angiotensin—aldosterone related microRNAs in the patients with thyrotoxic heart disease

Thyrotoxic heart disease (THD) is a common and severe complication of hyperthyroidism and the etiology of this complication remains poorly understood. Activation of the rennin-angiotensin- aldosterone system by excess thyroxin is one of the major factors that contribute to the pathogenesis of THD. Several microRNAs such as miR-21, miR-155, miR-208a, and miR-499 are closely related to the rennin-angiotensin-aldosterone system and therefore should be involved in this process. Our study intends to explore whether these miRNAs are involved in the pathogenesis of THD, and if these miRNAs could be secreted into the circulation and serve as sentinel indicators for THD. Though there is a trend of elevation of miR- 155 in THD than in simple hyperthyroidism patients, we did not find statistically significant differences in the expression of these miRNAs in the blood of THD patients, but we found that miR-155 was significantly up-regulated in patients with Graves' disease with or without THD in comparison with healthy controls. Thus, miR-155 can serve as a novel biomarker for Graves' disease and can play important roles in pathogenesis of Graves' disease.