目的研究初发系统性红斑狼疮（systemic lupus erythematosus，SLE）患者外周血淋巴细胞中细胞核因子-κB受体激活剂配体（receptor activator of nuclear factor kappa B ligand，RANKL）、护骨素（osteoprotegerin，OPG）基因mRNA的表达情况，探讨其表达水平与初发SLE患者骨质疏松的关系。方法选择初发SLE患者45例及正常对照42例，运用实时定量PCR方法检测患者外周血淋巴细胞RANKL、OPG的mRNA表达水平。采用双能X线骨密度仪分别检测患者腰椎（L1-4）和股骨近端2个部位的骨密度，单因素分析RANKL、OPG基因mRNA表达水平与SLE患者骨密度的关系。结果SLE患者RANKL、OPG基因mRNA表达水平较正常对照组明显减低（P〈0．01）；SLE患者2个部位的骨密度均低于正常对照组（P〈0．05），骨量异常发生率为28-89％，骨量异常降低的SLE患者OPG基因mRNA的表达水平比骨量正常的患者显著降低，两者间的差异有统计学意义（P〈0．01）；而RANKL基因mRNA表达水平的差异无统计学意义（P〉0．05）；OPG基因mRNA表达水平与初发SLE患者骨密度间存在正相关（r=0．461；P=0．001），即OPG表达水平越低，骨量减少越明显；而RANKL基因mRNA表达降低与初发SLE患者骨密度无明显相关性（r=-0．189，P=0．214）；初发SLE患者疾病活动度与骨量减少、RANKL及OPG基因表达水平间不存在相关性（r=0．293，P=0．138；r=-0．099，P=0．493；，=0．138，P=0．493）。结论初发SLE患者骨量减少的发病率较正常人群增高，并且初发SLE患者体内RANKL和OPG基因表达存在异常；其中OPG表达水平的降低可能与初发SLE患者的骨量减少有密切关系。
Systemic lupus erythematosus (SLE) is an archetypical systemic,autoimmune inflammatory disease,of which the mechanism still not unveiled. Studies on epigenetics in SLE have long been the subject of investigation and as part of epigenetics. DNA methylation has been confirmed to play a role in the pathogenesis of SLE. The high autoreactivity of CD4+T cell from SLE patients is associated with DNA hypomethylation. DNA hypomethylation is crucial to induce SLE-like autoimmune disease in SLE-non-susceptible mice. The reactivation of inactive X chromosome by hypomethylation may lead to high incidence of SLE in women. Drug-induced SLE is also connected with DNA hypomethylation. To understand the role of DNA methylation in the onset of SLE comprehensively,we review the findings reported in the literatures about DNA methylation and SLE.
