系统性红斑狼疮相关候选基因Aiolos的SNP分析及其功能研究

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease, the pathogenesis of which remains unclear. It is generally considered that SLE is related with individual genetic variation. Recently, association study on SNPs of candidate gene has been main strategy of SLE pathogenesis. Aiolos is a SLE susceptibility gene found in genome-wide association study among European and American population. Our early study showed that Aiolos mRNA expression level in SLE patients was significantly lower than that in healthy controls, which was correlated with serum C3, C4, total protein and 24-h proteinuria. The case-control study found that there were four polymorphisms in Aiolos that might be associated with SLE susceptibility. On that basis, our study plans to perform the independent and two-stage joint research of SLE related polymorphisms in Aiolos with enlarged sample, analyze the impact of SLE related polymorphisms on the expression of Aiolos, explore the effect of gene polymorphisms and haplotypes on the disease combining the clinical and pathological data, and clarify the action mode and molecular mechanism of the polymorphisms in SLE pathogenesis. The systemic study of the role of Aiolos in SLE might provide new experiment evidence for clinical diagnosis and treatment of this disease.

SLE是典型的全身性自身免疫性疾病，与遗传因素有关，近年来候选基因多态性作为疾病遗传标记的关联性研究成为探讨SLE发病机制的主要策略。Aiolos是最近在欧美人群全基因组关联研究中发现的SLE易感基因，我们的预实验显示SLE患者外周血单核细胞中Aiolos mRNA表达水平较正常人明显降低，其表达与实验室检验指标（如血清补体C3、C4、血清总蛋白以及24小时蛋白尿水平）具有相关性；病例—对照研究发现Aiolos基因中的4个SNP位点可能与SLE易感性相关联，在此基础上本研究拟对SLE相关多态进行二期扩大样本研究，分析SLE相关多态对Aiolos基因表达的影响，并结合临床病例资料阐明SLE相关多态位点的单一位点效应以及多位点联合效应，同时探讨SLE相关多态的作用模式及其与SLE易感性的相关机制，为SLE临床诊断和治疗提供新的实验依据。

SLE是全身性自身免疫性疾病，多种族人群全基因组关联研究发现多个易感基因。本研究探讨SLE易感基因IKZF3-ZPBP2、IRF8、TMEM39A和LAPTM5的多态性与表达情况：流式细胞检测37例健康人、32例SLE患者和35例RA患者外周血T细胞、B细胞和单核细胞IKZF3（Aiolos）蛋白表达，结果显示SLE组Aiolos+CD8+T细胞和Aiolos+CD14+单核细胞的细胞数比例较对照组显著增加，RA组中Aiolos+CD4+T细胞、Aiolos+CD8+T细胞、Aiolos+CD19+B细胞和Aiolos+CD14+单核细胞比例较对照组也显著增加，同时SLE组中Aiolos+CD8+T细胞比例与ESR呈正相关，而RA组中该细胞比例与RF呈正相关，另一方面Aiolos+CD14+单核细胞的比例与实验室多项检验指标具有相关性，包括ESR、肌酐、CRP 、LDH、蛋白尿、白蛋白和ACCPA。上述结果表明，Aiolos表达异常与SLE和RA病变密切相关。PCR-RFLP和MassARRAY对415例SLE患者和470例健康人进行多态分析，结果显示SLE组中Aiolos rs907091基因型CC和等位基因C的频率较对照组显著下降，rs12150079基因型AA和等位基因A的频率在SLE组中则明显升高，而rs9909593基因型AG的频率在SLE组中略有升高，单倍型分析显示SLE组中GGCG频率较对照组显著下降，而SLE组GGTG频率则显著升高。TMEM39A rs12493175基因型CT和CT+TT显著降低SLE风险，TMEM39A rs12493175基因型CT和CT+TT显著降低SLE风险，rs13062955基因型AC和AC+AA也显著降低SLE风险，而rs2282175基因型CT和CT+TT频率在SLE组中略有升高，提示增加SLE风险，单倍型分析显示CGTA频率在SLE组中显著降低。本次研究未发现LAPTM5存在SLE易感位点，其单倍型GGAT频率在SLE组中显著降低；实时定量PCR结果显示LAPTM5 mRNA在SLE外周血单核细胞中表达较对照组显著降低，狼疮肾患者较无狼疮肾患者表达也显著降低，且表达与临床检验指标呈相关性，提示LAPTM5表达异常与SLE严重程度相关。综上所述，本研究为SLE的诊断与治疗提供了新的实验依据。