在急性冠脉综合征（ACS）患者的粥样斑块和外周血中发现缺失CD28分子表达的CD4+CD28-T细胞，在斑块破裂中起重要作用，该细胞缺失CD28分子表达的机制尚不清楚。DNA甲基化和组蛋白修饰是重要的表观遗传修饰方式，参与基因转录调控。预实验初步证实ACS CD4+CD28-T细胞CD28分子表达缺失可能与CD28基因转录抑制有关，但是否受表观遗传调控迄今国内外未见报道。因此，我们推测DNA甲基化和组蛋白修饰调控CD4+CD28-T细胞CD28 基因转录抑制，导致CD28分子表达缺失。本课题组拟通过体外实验，采用实时定量PCR和FCM检测CD4+CD28-T细胞CD28mRNA和CD28表达，亚硫酸盐测序和ChIP观察CD28基因启动子DNA甲基化和组蛋白修饰，并进行表观遗传干预试验。研究结果将从新视觉阐明CD4+CD28-T细胞CD28分子表达缺失的机制，为防治斑块破裂提供新的药物靶点。

The CD4+CD28-T cells with lose of CD28 were found in atherosclerotic plaque and peripheral blood in patients with acute coronary syndrome ( ACS ). The CD4+CD28-T cells play an important role in process of atherosclerotic plaque rupture. To date, mechanisms losing of CD28 in CD4+CD28-T cells remain unclear. DNA methylation and histone modification are important epigenetics modification which play a significant role in regulation of gene transcription, Preliminary experiments have confirmed that CD28 lose is correlated with a lack of CD28mRNA. No study, however, has examined that epigenetics modification regulate CD28 gene transcription inhibition.Therefore,we speculated that DNA methylation and histone modification regulate transcription inhibition of CD28 gene which lead to the absence of CD28 molecule. In the present study, DNA methylation and histone modification are detected in the CD28 gene promoter region using bisulfite sequencing and chromatin immunoprecipitation in CD4+CD28-T cell, and expression of CD28 mRNA and CD28 are measured by real-time PCR and FCM, then epigenetics intervention experiment are performed. Our findings will elucidate the role of DNA methylation and histone modification in absence of CD28 in CD4+CD28-T cells and provide new drug targets for prevention of plaque rupture.

在急性冠脉综合征（ACS）患者的粥样斑块和外周血中发现缺失CD28分子表达的CD4+CD28-T细胞，在斑块破裂中起重要作用，该细胞缺失CD28分子表达的机制尚不清楚。DNA甲基化和组蛋白修饰是重要的表观遗传修饰方式，参与基因转录调控。为证实DNA甲基化和组蛋白修饰是否参与了ACS患者CD4+CD28-T细胞CD28分子表达缺失的调控，我们采用实时定量PCR和FCM技术检测CD4+CD28-T细胞CD28mRNA和分子表达，亚硫酸盐测序和ChIP观察CD28基因启动子DNA甲基化和组蛋白修饰，并进行表观遗传干预试验。结果显示ACS患者CD4+T细胞CD28启动子区域DNA甲基化水平上调，组蛋白H3、H4乙酰化水平下调.在应用DNA甲基转移酶抑制剂5-azaC和组蛋白去乙酰化酶抑制剂TSA处理ACS患者CD4+CD28-T细胞后，组蛋白H3、H4乙酰化和H3K4甲基化水平明显升高，CD28mRNA的表达显著上调。综上所述，ACS患者CD4+T细胞CD28启动子区域DNA高甲基化和组蛋白H3、H4的低乙酰化H3K4低甲基化是CD28表达缺失的重要原因。本研究进一步揭示了ACS CD4+CD28-T细胞CD28表达缺失的表观遗传机制，为临床有效防治斑块破裂导致的ACS提供新理论和药物作用新靶点。