miRNA-181a-SIRT1在调节病毒性心肌炎Th17/Th9细胞平衡中的作用与机制研究

The imbalance of Th17/Treg cells has been shown to play the important role in the development of viral myocarditis (VMC). Recently, we found that a new subtype of CD4+ Th cells named the Th9 cell could significantly improve the progression of VMC by secreting IL-9, and the proportion of Th9 cells in myocardial lesions was higher than that of Treg cells. So we propose that regulating the balance of Th17/Th9 cells might be a better way to slow down the progress of VMC. But the critical molecule targeting the balance of Th17/Th9 cells and its mechanism in VMC remains unknown. Lately, some studies indicated that the deacetylase SIRT1 was associated with the differentiation of CD4+ Th cells. Furthermore, our preliminary experiment scaned and observed that the expression of SIRT1 was increased in Th17 cells while decreased in Th9 cells in VMC patients, and regulated by miRNA-181a. Then this study was to determine the regulatory effect and mechanism of miRNA-181a-SIRT1 on the balance of Th17/Th9 cells in VMC by establishing VMC mouse models induced with CVB3, transfecting miRNA-181a oligonucleotides or siRNA into CD4+ Th cells or VMC mice, investigating the expression of CD4+ Th cell SIRT1, the differentiation and transformation of Th17/Th9 cells, the activation of transcription factors, the secretion of inflammatory cytokines and so on. The data would reveal the new immunological pathogenesis of VMC and provide a new target for VMC treatment.

研究证实Th17/Treg细胞失衡加重病毒性心肌炎（VMC）心肌损伤，然而我们最近研究发现CD4+Th9细胞通过分泌IL-9抑制VMC进程，且它在心肌炎症区域浸润明显多于Treg细胞。因此调控Th17/Th9细胞平衡可能成为延缓VMC发展的更重要手段，但是其调控靶点及作用机制尚未阐明。新近研究报道去乙酰化酶SIRT1与CD4+Th细胞分化有关，而我们前期筛选发现它在VMC患者Th17细胞中升高、在Th9细胞中显著降低，且其表达受miRNA-181a调控。本研究拟建立柯萨奇B3病毒诱导的VMC小鼠模型，分别在体内外应用转染技术导入miRNA-181a寡核苷酸和siRNA，检测CD4+Th细胞SIRT1表达对Th17/Th9细胞分化和转化、转录因子变化、炎症因子生成等影响，探讨miRNA-181a/SIRT1对Th17/Th9细胞平衡的调控作用与机制，从而揭示VMC新的治疗靶点和免疫学机理。

病毒性心肌炎（VMC）的发病机制与病毒对心肌细胞的直接损伤和机体自身免疫失调密切相关，CD4+ Th细胞在其中有重要作用，然而机制尚未完全阐明。SIRT1是细胞内一种NAD+依赖的去乙酰化酶，在细胞能量代谢等病理生理过程中起着重要作用。我们的研究表明：miR-181a在VMC患者血液单个核细胞中低表达，而SIRT1高表达；SIRT1在VMC小鼠的心肌组织高表达，其表达受miRNA-181a的调控；SIRT1能抑制Th17的分化，减轻VMC的病情；对Th9分化作用不明显。miRNA-181a和SIRT1可能为VMC的早期治疗的新靶点，从而为降低VMC和扩张型心肌病（DCM）的发病和死亡风险、减轻家庭和社会负担提供可能性。