DNA羟化酶TET2调控HIF-1A表达的机制及其在系统性红斑狼疮Th17/Treg细胞失衡中的作用

The imbalance between Th17/Treg cells plays an important role in the pathogenesis of systemic lupus erythematosus (SLE) and the underlying mechanism remains unclear. In previous studies, we found that elevated expression of TET2 in SLE CD4+ T cells, and increased hydroxymethylcytosine (hmC) level at HIF-1A promoter by hydroxymethylated DNA immunoprecipitation chip. Both the mRNA level of HIF-1A and the mRNA ratio of IL-17A/Foxp3 were significantly down-regulated in SLE CD4+ T cells transfected with TET2-siRNA, while up-regulated in normal CD4+ T cells transfected with TET2-expressing plasmid. HIF-1A, a key transcription factor in metabolic processes, can induce the imbalance between Th17/Treg cells. Therefore, we hypothesize TET2 may result in the imbalance between Th17/Treg cells by up-regulating HIF-1A expression, and promote the occurrence and development of SLE. In order to verify the hypothesis, we will enlarge the size of samples, explore the roles of TET2 in the imbalance between Th17/Treg cells by regulating the expression of HIF-1A and the underlying mechanisms in systemic lupus erythematosus. These studies will help demonstrate a novel mechanism in SLE pathogenesis and explore new therapeutic targets.

Th17/Treg细胞失衡在系统性红斑狼疮（SLE）发病中起重要作用，但致其失衡的机制至今尚不明确。我们前期研究表明：在SLE CD4+T细胞中，DNA羟甲基化酶TET2异常增高；羟甲基化DNA免疫共沉淀芯片示HIF-1A启动子区呈高羟甲基化；沉默或过表达TET2可相应降低或增高CD4+T细胞中HIF-1A mRNA水平及IL-17A/Foxp3 mRNA比值。HIF-1A是代谢重要的转录因子，同时可诱导Th17/Treg细胞失衡。因此，我们推测TET2有可能通过上调HIF-1A表达，而导致Th17/Treg细胞失衡，最终促进SLE发生发展。为验证这一假说，我们将扩大样本，以CD4+T细胞为模型，深入探讨DNA 羟甲基化酶TET2通过调控HIF-1A表达，介导SLE患者Th17/Treg细胞失衡的作用及机制。本研究将有助于进一步揭示SLE的发病机制及探寻新的治疗靶标。

Th17/Treg细胞失衡在系统性红斑狼疮（SLE）发病中起重要作用，但致其失衡的机制至今尚不明确。在文献及前期研究的基础上，我们推测DNA羟化酶TET2有可能通过上调HIF-1A表达，而导致Th17/Treg细胞失衡，最终促进SLE发生发展。为验证这一假说，我们分别检测了SLE患者外周血CD4+T细胞中TET2、HIF-1A、FoxP3、IL-17A的表达，及它们在SLE患者皮损组织切片中的表达，分析了它们之间相关性；明确了HIF-1A在SLE患者Th17/Treg细胞失衡中的作用；检测了SLE CD4+T细胞中HIF-1A启动子区的表观遗传学修饰状态，如：DNA甲基化、羟甲基化及组蛋白修饰H3K4me3、H3K27me3水平；明确了TET2是否调控SLE CD4+T细胞HIF-1A表达；探讨了TET2促进Th17/Treg细胞失衡的机制。.我们的结果表明HIF-1A促进SLE患者Th17/Treg细胞失衡；SLE CD4+T细胞HIF-1A基因启动子区DNA羟甲基化水平增高，组蛋白修饰H3K27Me3水平也增高;TET2对HIF-1A的表达没有明显调控作用；TET2可通过增高SLE患者CD4+T细胞IL17A启动子区DNA羟甲基化和H3K4me3水平，促进IL-17A表达，从而加重Th17/Treg细胞失衡。以上结果说明Th17/Treg细胞平衡受DNA羟化酶TET2和代谢转录因子HIF-1A双重调控。表观遗传和经典的代谢通路均在免疫失衡中起作用，并促进SLE发生发展。.本研究进一步揭示了SLE的发病机制，并为开辟新治疗提供了很有前景的新靶标（DNA羟化酶TET2和代谢转录因子HIF-1A），值得进一步深入研究。项目待发表论文2篇。培养研究生3名，1名在读，两名合作的研究生均已毕业，分别取得硕士和博士学位。项目投入经费18万元，支出14.4848万元，支出与预算稍有调整。剩余经费3.5152万元，计划用于本项目研究后续支出。