特发性扩张型心肌病CTLA-4基因3′非翻译区(AT)n微卫星多态性研究

Association between the cytotoxic T lymphocyte antigen-4 gene microsatellite polymorphism in the 3′ untranslated region and idiopathic dilated cardiomyopathy

目的特发性扩张型心肌病(idiopathic dilated cardiomyopathy,IDC)的发病机制与T细胞免疫应答密切相关。细胞毒性T淋巴细胞相关抗原24(cytotoxic Tlymphocyte antigen-4,CTLA-4)主要在已激活的T细胞上表达,通过与CD28竞争结合B7,抑制T细胞过度激活,维持免疫系统内环境稳定。CTLA-4基因3′非翻译区(AT)n微卫星多态性影响CTLA-4功能。本研究旨在探讨外周血单个核细胞(PBMC)CTLA-4表达状况及3′非翻译区(AT)n微卫星基因多态性与IDC的相关性。方法分别用原位杂交、免疫组化、序列特异性引物PCR等方法检测38例无血缘关系的北方汉族IDC患者以及50例正常对照者的CTLA-4 mRNA、蛋白质表达、CTLA24基因外显子3′末端非翻译区(AT)n重复序列多态性,并对PCR扩增产物进行序列分析。结果IDC组与对照组相比,PBMC经金黄色葡萄球菌肠毒素B刺激后CTLA-4 mRNA、蛋白质表达强度显著减弱,且无一定规律;3′末端非翻译区共发现18种CTLA24等位基因,与对照组比较,106bp等位基因频率在IDC患者中显著增高[22.22%vs1%,P=0.0002,OR=23.56,95%可信区间(CI):9.65～83.74]。结论IDC患者CTLA-4基因转录和表达缺陷,该缺陷与CTLA-4基因3′末端非翻译区(AT)n重复序列多态性存在关联。

Objective To investigate an association between CTLA-4 gone 3＇ untranslated region micro-atellite polymorphisms and IDC and to explore the immunogenetic pathogenesis of IDC. Methods Genetically unrelated Chinese Han patients 38 with IDC and healthy controls 50 were studied. Expression of CTLA-4 mRNA and antigen was detected by in situ hybridization and immunohistechemistry. The （AT） n repeat sequence in the 3＇ untranslated region of exon 4 was amplified by allele-specific PCR. The amplified products were electrophorosised by 12% polyacrylamid gel and then examined by silver staining. Results Expression of both mRNA and antigen of CTLA-4 was significantly but unregularly weaker on PBMC induced by staphytoceccal enterotoxin B（SEB） in patients than that in normal controls. Eighteen alleles of CTLA-4 microsatellite were found in Chinese patients and healthy individuals. Long allele, 106 bp was apparently increased in patients with IDC as compared with healthy controls （22.22% vs 1%, P=0.0002, OR=23.56, 95% CI： 9.65-83.74）. Conclusion Defective transla- tion and expression of CTLA-4 take place in patients with IDC, it is possibly related to the CTLA-4 gone microsatellite polymorphism.