RANKL、OPG在初发系统性红斑狼疮患者中的表达及意义

The significance of the RANKL and OPG gene expression in the initial systemic lupus erythematosus patients

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。

Objective To investigate the RANKL and OPG gene expression in peripheral blood lymphocytes of patients with systemic lupus erythematosus （SLE） and its relationship with bone mineral density （BMD）. MethodsThe expressions of RANKL and OPG gene in peripheral blood lymphocytes from 45 SLE patients and 42 normal controls were detected by real-time PCR. BMD measurements in the lumbar spine （L1 - L4） and left proximal femur （femoral neck） were performed using dual X-ray absorptiometry before treatment. The relationship between RANKL and OPG gene expression and the bone mass were studied. Results The expressions of RANKL and OPG gene significantly decreased in initial SLE compared with normal controls（ P 〈 0.01 ）. The initial SLE patients had significantly lower BMD values, and higher frequency of osteopenia（28.89%） at all sites of measurement compared with matched healthy controls（ P 〈 0.01 ）. Recent-onset SLE patients were divided into two groups by BMD, abnormal group and normal group. There are differences in OPG gene expression between them （ P 〈 0.01 ）. There is positive correlation between OPG gene expression and BMD in recent-onset SLE patients （ r =0. 461 ; P = 0. 001 ）. In the SLE patients RANKL gene expressions were not correlated with BMD（ r = - 0. 189, P = 0. 214）. There is no correlation between SLE disease activity and B MD, RANKL gene expressions, OPG gene expressions respectively（ r = 0. 293, P = 0. 138 ; r = - 0.099, P = 0.493 ; r = 0.138, P = 0. 493）. Conclusions Recent onset untreated SLE patients may have lower BMD than expected. There are abnormal RANKL and OPG gene expressions in SLE patients. The low expression of OPG gene may be involved with the osteopenia in the initial SLE patients. The level of RANKL gene is not correlated with BMD.