长链非编码RNA MAFTRR在桥本甲状腺炎中的作用及其机制研究

T helper type 1 Cells(Th1) , as an inflammatory CD4+T cells subset, play an important role in Hashimoto’s thyroiditis (HT). However, the underlying mechanisms of HT remain largely unknown. Long noncoding RNAs (lncRNAs) are increasingly appreciated as key regulators of genome transcription. LncRNA MAFTRR contributing to Th1 cells response in HT patients has not been reported. We found that the proportion of circulating Th1 cells and the level of IFNG mRNA were increased in patients with HT, and Upregulated expression of MAFTRR with downregulated MAF expression were confirmed in HT patients. Studies have shown that MAFTRR, a chromatin-associated Th1-specific lincRNA, could regulate MAF transcription, a Th2-associated transcription factor. Thus, we speculate that enhanced expression of MAFTRR can contribute to Th1 cell response via depressing MAF expression in HT patients. Because the expression of MAFTRR in Th1 cells was both specific and stable, we investigated whether this was the result of epigenetic changes , contained histone modifications , RNA polymerase II occupancy and transcription factors binding to the promoter region, that occurred during Th1 cells differentiation in HT. We found that a canonical binding site in MAFTRR promoter region for the transcription factor STAT4, which is a key regulator of Th1 cells differentiation. Preliminary data confirmed STAT4 expression was significantly increased in HT patients. Thus, we speculate that the active epigenetic modifications on MAFTRR promoter region by STAT4 contribute to the specific expression in Th1 cells. This study aims to clarify the underlying mechanisms and the role of MAFTRR contributed to Th1 cell response in HT, which could further demonstrate the pathogenesis of HT and formulate a key theoretical basis for potential management for diagnosis and treatment in HT.

桥本甲状腺炎（HT）中Th1细胞发挥重要作用，其机制尚未完全阐明。长链非编码RNA（lncRNAs）是一类参与分子调控的非编码RNA。HT患者中lncRNA MAFTRR对Th1细胞作用的研究尚未报道。我们发现HT患者Th1细胞明显增加，lncRNA MAFTRR表达亦增高，MAF表达减低。已有报道Th1细胞特异性MAFTRR能够抑制MAF转录。由此我们推测HT中，MAFTRR通过抑制MAF表达促进Th1细胞分化。那么，什么因素导致HT中MAFTRR高表达？基因转录调控涉及组蛋白修饰，RNA聚合酶聚集，转录因子结合等表观遗传改变。我们发现MAFTRR启动子区域存在STAT4结合位点，且其在HT患者高表达，由此推测HT中，STAT4正向调控MAFTRR基因启动子区域表观遗传修饰，为其转录提供有力条件，促进其转录。本项目研究HT发病过程中MAFTRR特异性表达的因素，以及对Th1细胞的作用机制。进一步阐释HT的发病机制，为寻找HT潜在诊疗方案提供理论依据。

桥本甲状腺炎（HT）是一种临床上常见的器官特异性自身免疫病，以体内出现针对甲状腺组织的自身抗体和大量淋巴细胞浸润为主要特征，最终导致甲状腺组织破坏和功能丧失。但具体发病机制尚未完全阐明。本研究主要探讨长链非编码RNA（lncRNA）在HT中的作用，揭示lncRNA-MAFTRR与HT患者体内辅助性CD4+T细胞异常变化的关系，为深入了解疾病发病机制、诊疗靶点提供新思路，主要完成情况如下：.1、桥本甲状腺炎患者外周血中lncRNA表达谱变化.与对照者相比，HT患者PBMCs中存在97286种差异表达的lncRNAs，其中差异表达倍数大于1.5倍的lncRNAs有218种（包括94种表达上调的lncRNAs和124表达下调的lncRNAs）。生物信息学分析发现这些异常表达的lncRNAs与NF-B、PI3K-Akt、MAPK及Jak-STAT信号通路存在关联。.2、MAFTRR在HT患者中的变化及调控基因分析.生信分析lncRNAs潜在调控基因，并且这些潜在靶基因与HT有关，结合二者选择研究MAFTRR，其潜在靶基因MAF。研究证实MAFTRR在HT患者中显著增高，与测序结果一致，且与血清TgAb、TPOAb均呈正相关，ROC曲线分析显示MAFTRR具有潜在诊断价值。而HT患者中MAF水平显著降低，且与患者IFNG水平呈负相关。体外实验证实MAFTRR能够抑制MAF表达。.3、HT疾病中MAFTRR对Th1细胞的影响.HT患者Th1细胞比例和IFNG水平显著增高，MAFTRR与Th1细胞比例和IFNG水平均呈正相关。体外下调MAFTRR后， Th1细胞比例和IFNG水平明显下调。HT患者外周血中STAT4表达增高，下调STAT4后MAFTRR表达下降。以上结果提示HT患者体内MAFTRR通过MAF参与Th1细胞反应，其表达增高与STAT4有关。.4、HT患者甲状腺组织中MAFTRR的表达情况.HT患者甲状腺组织中MAFTRR和IFNG水平显著高于单纯甲状腺肿大患者，二者呈显著正相关；而MAF水平则显著降低。.综上所述，MAFTRR可通过调控Th1细胞反应参与HT的疾病过程。通过本项目研究，一方面揭示MAFTRR在桥本甲状腺炎中的作用，另一方面进一步揭示桥本甲状腺炎的发病机制，为寻找桥本甲状腺炎的诊疗靶点提供理论依据。