Circulating microRNAs in autoimmune thyroid diseases

Context Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's thyroiditis (HT), are the most common autoimmune diseases. MicroRNAs (miRNAs) are small noncoding RNAs, which can play pivotal roles in immune functions and development of autoimmunity. Recently, it has been recognized that identification of circulating miRNAs can provide important and novel information regarding disease pathogenesis and clinical condition. However, the role circulating miRNAs in AITD has not yet been described. Objective The aim of this study was to characterize the different circulating levels of miRNA in patients with AITD. Design and methods Sixty-four participants who met the criteria for HT or GD and healthy subjects were recruited. Microarrays were used to analyse the expression patterns of miRNA in serum obtained from patients with HT and GD and healthy subjects. After analysing the microarray data, four interesting miRNAs (miR-16, miR-22, miR-375 and miR-451) were selected and validated by quantitative real-time PCR. Results Several miRNAs were observed to be differently expressed in serum from patients with AITD compared with healthy subjects by microarray analysis. Further analysis consistently showed that serum levels of miR-22, miR-375 and miR-451 were increased in patients with HT. On the other hand, the serum levels of miR-16, miR-22, miR-375 and miR-451 were increased in patients with GD compared with healthy subjects. Conclusions We revealed that different levels of serum miRNAs were associated with GD and HT, which may play a role in the pathogenesis of these diseases.