口腔慢性移植物抗宿主病（cGVHD）是异基因造血干细胞移植术后常见并发症之一，是以口腔粘膜苔藓样变为诊断性特征的类似自身免疫性疾病，其发生发展可能与患者Th17/Treg失衡相关。微RNA（miRNA）在免疫细胞的发育和成熟中发挥重要作用，并具有组织特异性。已证实miRNA-155与硬皮病、扁平苔藓等多种免疫疾病有关。本项目拟通过检测miRNA-155在allo-HSCT后口腔cGVHD患者血液和口腔病损中的表达，结合Th17/Treg细胞免疫平衡状况，探讨miRNA-155对口腔cGVHD发生发展的影响及其可能的调控机制；此外，构建小鼠cGVHD模型，通过miRNA-155干预试验，探讨miRNA-155对Th17/Treg细胞免疫的影响及JAK-STAT及TGF-β/Smad信号通路在其中的作用。本项目旨在进一步理解口腔cGVHD的疾病机制，为其临床防治提供新的思路。

Oral chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT)，manifests as an inflammatory and autoimmune-like disorder characterized by lichen planus-like changes on the oral mucosa which is its diagnostic features. The occurrence and progress of oral cGVHD may be related to the imbalance of Th17/Treg. MicroRNA(miRNA) is a class of small noncoding RNA which plays a role in immune cell differentiation and involves in many autoimmune diseases like scleroderma and oral lichen planus. Aimed to explore the role of miRNA-155 in the Th17/Treg balance in oral cGVHD, as well as to understand the mechanism involved, we detect the miRNA-155 differential expression in peripheral blood and oral exfoliative cells among patients with oral cGVHD after allo-HSCT, and Th17 and Treg cells differentiation and cytokines production. Further, cGVHD mice model is established to observe the effect of miRNA-155 on the balance of Th17/Treg，as well as the activation of JAK-STAT and TGF-β/Smad signal pathway by over-expression and inhibition of miRNA-155 .