启动子区域甲基化状态对THP-1细胞肿瘤坏死因子α分泌的影响

目的: 探讨肿瘤坏死因子α( TNF-α )基因启动子区域散在CpG双核苷酸结构甲基化状态对蛋白分泌和基因表达的影响。方法: 检测人单核细胞系THP-1细胞在脂多糖(LPS)刺激状态下,不同时点TNF-α的表达和其基因启动子区域的甲基化状态。采用ELISA法测定细胞培养液上清TNF-α水平;采用重亚硫酸盐转化基因测序法测定DNA甲基化状态。结果: 受到LPS刺激后,THP-1细胞迅速产生 TNF-α ,在4 h达到高峰后快速下降。 TNF-α 基因启动子-344 bp到转录起始位点(TSS)区域内,存在11个散在CpG双核苷酸结构。未受到LPS刺激时均处于甲基化状态;刺激4 h后,有4个处于甲基化状态;刺激8 h后,有9个处于甲基化状态。未刺激与刺激4 h之间,刺激4 h与刺激8 h之间,甲基化率比较均有显著差异(P＜0.01,P<0.05)。结论: 未受到LPS刺激时,THP-1细胞 TNF-α 基因启动子区域甲基化水平较高;LPS刺激后,其该区域甲基化水平降低。该变化与TNF-α表达分泌相关。     

TNF-α对HepG2细胞LXRα介导的胆固醇外流的影响及其分子机制

 目的:观察肿瘤坏死因子α（TNF-α）对肝X受体α（LXRα）启动子活性及其下游ATP结合盒转运蛋白（ABCA1和ABCG1）表达的影响,从而探讨TNF-α加速HepG2细胞内胆固醇积聚的分子机制。方法:构建LXRα基因的启动子表达载体,观察炎症因子TNF-α对LXRα启动子活性的影响,进一步将HepG2细胞分为对照组（control）、TNF-α组（20 μg/L）、高脂组（LDL,100 mg/L）及联合处理组（TNF-α 20 μg/L+ LDL 100 mg/L）。采用实时定量PCR和Western blotting检测LXRfα、ABCA1和 ABCG1的mRNA及蛋白的表达。［3H ］标记胆固醇,液体闪烁计数法检测胆固醇外流量。油红O染色和定量比色法分析细胞内胆固醇的含量。结果:成功构建LXRα启动子的萤火虫萤光素酶报告质粒,证明了该启动子有明显活性,TNF-α能明显抑制LXRα启动子的活性。进一步检测发现,和对照组相比,TNF-α下调了LXRα、ABCA1和ABCG1 mRNA与蛋白表达。高脂组胆固醇外流量增加,而TNF-α组胆固醇外流量明显降低。油红O染色显示,TNF-α使细胞内脂质染色明显增加。结论: TNF-α可通过抑制LXRα启动子活性从而抑制HepG2细胞内胆固醇外流导致肝细胞内脂质异常积聚。     

非小细胞肺癌中ASPP1和ASPP2基因启动子甲基化的意义

目的 检测非小细胞肺癌(NSCLC)中ASPP1和ASPP2基因启动子CpG岛的甲基化状态和相应的蛋白表达,及癌细胞的凋亡水平和p53蛋白的表达,探讨ASPP基因在NSCLC中的作用及其临床意义.方法 采用甲基化特异性PCR(MSP)检测90例NSCLC组织、25例癌旁肺组织中ASPP1、ASPP2基因启动子的甲基化水平,并测序证实其甲基化位点;免疫组织化学EnVision法检测NSCLC组织中ASPP1、ASPP2和p53蛋白的表达;原位末端转移酶标记检测法(TUNEL)检测癌细胞凋亡,计算其凋亡指数(AI).结果 ASPP1基因启动子甲基化率在NSCLC中为42.2%(38/90),癌旁组织中为16.0%(4/25),二者比较差异有统计学意义(P=0.019);ASPP1基因启动子甲基化与患者年龄、性别、组织类型和分化程度无相关性(均P＞0.05),但与患者的TNM分期和淋巴结转移存在相关性(P=0.031,P=0.030);90例肺癌组织中ASPP1甲基化者其蛋白表达率明显低于ASPP1未甲基化者(P=0.002);ASPP1蛋白阳性组的AI值高于阴性组(P=0.022).90例NSCLC和25例癌旁组织中均未检测到ASPP2基因启动子甲基化;ASPP2蛋白表达阳性组和阴性组之间AI值差异也无统计学意义(P=0.282).ASPP1和p53表达呈负相关,(r=-0.259,P＜0.01),ASPP2和p53的表达状态无关(r=-0.119,P＞0.05).结论 NSCLC中ASPP1基因启动子甲基化可能是ASPP1蛋白表达下调的原因,高甲基化可能与NSCLC的恶性进展有关,ASPP1蛋白的表达能促进细胞凋亡.

Abstract：

Objective To investigate the methylation status of CpG islands in the promoter region and the protein expression of ASPP1 and ASPP2 genes in non-small-cell lung cancer (NSCLC) and their relationship with cellular apoptosis and p53 gene expression. Methods The 5'CpG island methylation patterns of ASPP1 and ASPP2 were evaluated by methylation specific polymerase chain reaction (MSP) followed by confirmation of sequencing. Immunohistochemistry was used to detect the expression of ASPP1,ASPP2 and p53 in lung carcinoma tissue samples ( n= 90) and adjacent non-neoplastic lung tissue samples (n = 25 ) . TUNEL assay was used to detect the apoptotic activity. Results The presence of ASPP1 methylation was significantly higher in NSCLC than that in the adjacent non-neoplastic lung tissue [42. 2%(38/90) vs. 16. 0% (4/25), P =0. 019]. ASPP1 promoter methylation had a close relationship with TNM stage and lymph node metastasis( P =0. 031, P =0. 030), but was not related to the age, sex, histological types and the grades of tumor differentiation (P =0. 389, P =0. 278, P =0. 570, and P =0. 103). Tumors with ASPP1 promoter methylation demonstrated a lower expression of ASPP1 as compared with those without the methylation (P =0. 002). ASPP1 expression was associated with a higher apoptotic index (AI) (P =0. 022) and a decreased p53 expression( r = -0. 259, P ＜ 0. 01 ). Methylation in the promoter region of ASPP2 gene was not detected in lung cancer (n = 90 ) or adjacent non-neoplastic lung tissue (n = 25 ).Expression of ASPP2 protein did not correlate with AI ( P = 0. 282 ) and p53 status in NSCLC. Conclusions High methylation of ASPP1 gene promoter regions is one of the important mechanisms that down-regulate its protein expression in NSCLC. ASPP1 promoter methylation may be associated with the malignant progression of the tumor, and ASPP1 expression promotes cellular apoptosis.     

中性粒细胞抑制人单个核细胞释放TNF-α及其机理的研究

目的:探讨人中性粒细胞(PMNs)对人外周血单个核细胞(PBMCs)释放TNF-α的影响及其作用机理。方法:采集健康供血者的新鲜外周静脉血,以葡聚糖沉淀和密度梯度离心法分离其PMNs和PBMCs,将PMNs细胞与PBMCs细胞按2:1的数量比与脂多糖共同培育后,分别采用酶联免疫吸附法测定培养上清的TNF-α浓度,并用流式细胞术测定结合荧光标记脂多糖的单核细胞的百分率及单核细胞表面平均荧光强度。结果:PMNs在细菌脂多糖刺激下不释放TNF-α,PMNs可以抑制PBMCs释放TNF-α,其抑制作用具有细胞特异性;经多聚甲醛固定的PMNs仍具有上述的抑制作用。流式细胞术结果显示PMNs并不影响单核细胞与脂多糖结合。结论:PMNs可抑制人PBMCs释放TNF-α,其机理可能是PMNs干扰脂多糖激活PBMCs的信号转导过程,抑制细菌脂多糖对其的活化,从而下调TNF-α的释放。     

卵巢癌细胞中OY-TES-1基因启动子CpG位点甲基化状态分析

目的:了解卵巢癌SKOV3细胞中OY-TES-1启动子区域CpG位点的甲基化状态.方法:运用免疫细胞化学法检测SKOV3细胞中OY-TES-1蛋白表达;通过硫化测序PCR法,分析SKOV3细胞中OY-TES-1启动子区域CpG位点的甲基化状态,并与睾丸组织相比较.结果:免疫细胞化学法检测结果显示,SKOV3细胞中OY-TES-1蛋白呈阳性反应;在检测的OY-TES-1启动子区域(转录起始点-127 bp～+110 bp,含24个CpG位点)中,CpG位点的甲基化频率为80.21％,其甲基化状态明显高于睾丸组织.结论:SKOV3细胞中OY-TES-1启动子CpG位点处于高甲基化状态,进一步可探讨甲基化抑制剂氮杂脱氧胞嘧啶对OY-TES-1甲基化状态及其表达水平的影响.     

乳腺癌相关基因启动子甲基化的研究进展

表基因的改变是乳腺癌发生发展过程中非常重要的机制。DNA甲基化是一种表观遗传修饰,是基因表达调控的一种方式。目前,已发现许多肿瘤相关基因启动子区CpG岛的甲基化异常与乳腺癌的发生密切相关。该文就乳腺癌相关基因甲基化的研究进展作一综述。     

α7nAChR的激活通过抑制TNF-α表达促进糖尿病小鼠伤口愈合

 目的：观察糖尿病小鼠伤口愈合期间巨噬细胞浸润及肿瘤坏死因子 α（TNF-α）表达特征,探讨α7烟碱型乙酰胆碱受体（α7nAChR）特异性激动剂PNU-282987是否可通过抑制TNF-α表达促进糖尿病小鼠伤口的愈合。方法：(1) 制作糖尿病小鼠切创模型（糖尿病组）,正常小鼠在相同部位制作相同大小创口作为对照（对照组）,分别于切创后1 d、3 d、5 d、10 d、14 d和21 d（每个时间段5只）提取创口样本。免疫组化观察创口中巨噬细胞和成纤维细胞数量,Western blotting检测TNF-α表达水平,Masson染色观察胶原沉积情况。 (2) 在糖尿病小鼠切创后,选择合适的干预时间窗进行PNU-282987干预,然后观察上述指标变化。结果：(1) 与对照组相比,糖尿病组创口愈合明显延迟,在切创初期的伤口中巨噬细胞数量和TNF-α表达水平较低（P<0.05）,而切创5 d后的伤口巨噬细胞数量和TNF-α表达水平显著增加（P<0.05）,成纤维细胞数量和胶原含量减少（P<0.05）。 (2) 在切创5 d后对糖尿病小鼠腹腔注射PNU-282987,可显著减少伤口中TNF-α表达,提高成纤维细胞数量和胶原含量,促进伤口愈合。结论：糖尿病伤口愈合具有炎症反应发生迟但不易消退的特征。在炎症反应明显期激活α7nAChR可抑制TNF-α表达,促进糖尿病小鼠的伤口愈合。     

TNF-α增强人脐带间充质干细胞条件培养基的体外造血支持功能

 目的：研究肿瘤坏死因子α（tumor necrosis factor α, TNF-α）刺激后所得的脐带间充质干细胞条件培养基对脐血CD34+细胞在半固体培养基中集落形成个数及种类的影响。方法：将3~6代人脐带来源间充质干细胞（human umbilical cord mesenchymal stem cells, hUC-MSCs）以2×106接种到75cm2培养瓶中,其中刺激组加入TNF-α（10 g/L）,48 h后收集上清作为条件培养基。Real-time PCR检测hUC-MSCs中各类造血因子mRNA的表达量。密度梯度离心法分离脐血单个核细胞,磁珠分选CD34+细胞,流式细胞术检测细胞纯度后分5组接种到6孔板内：TNF-α刺激hUC-MSC上清+不完全甲基纤维素培养基;hUC-MSC上清+不完全甲基纤维素培养基;TNF-α+DMEM/F12完全培养基+不完全甲基纤维素培养基;完全甲基纤维素培养基;DMEM/F12完全培养基+不完全甲基纤维素培养基。10 d后显微镜下计数各类集落形成单位（colony-forming unit, CFU）的数目,收集集落形成细胞,流式细胞术检测其表型特征。结果：（1）TNF-α刺激后hUC-MSCs中粒细胞集落刺激因子（granulocyte colony-stimulating factor, G-CSF）和白细胞介素6（interleukin-6, IL-6）mRNA表达上调。（2）两种条件培养组均可见粒系CFU（granulocyte CFU, CFU-G）、巨噬系CFU（macrophage CFU, CFU-M）和粒巨噬系CFU（granulocyte-macrophage CFU, CFU-GM）,但TNF-α刺激组CFU-G和CFU-M的数目约为未刺激组的1.5倍,CFU-GM约为未刺激组的2倍;阳性对照组中除粒系、巨噬系集落外还可见红系集落;而DMEM/F12完全培养基加或不加TNF-α组10 d后均未见集落形成。（3）流式细胞术检测TNF-α刺激组与未刺激组集落细胞表型CD14、CD45和CD11b,未见明显差异。结论：hUC-MSC上清作为条件培养基可在体外促进CD34+细胞分化增殖为髓系细胞,具有造血支持作用,TNF-α刺激后此作用增强。     

ASPP2基因启动子区DNA甲基化及转录因子DNA结合位点的干湿研究

对p53凋亡刺激蛋白2 (ASPP2)基因启动子区进行了甲基化及转录因子结合位点(TFBS) 的生物信息学分析及实验研究.结果表明,在该基因近端启动子区存在一个长1391bp的CpG岛,且此区域中包含19个转录因子的37个结合位点,其中有13个转录因子的结合位点含有CpG;甲基化预测发现在含CpG的23个TFBS中有18个位点的CpG易发生甲基化.由此推断ASPP2是典型的多因子调控的CpG岛基因,CpG岛的异常甲基化将影响转录因子结合,导致ASPP2基因表达下调.通过对人肝癌细胞株HepG和人成纤维细胞HFL-1的ASPP2基因启动子CpG岛中含4个E2F结合位点区域的甲基化实验检测,证明这种推断是正确的.这一研究说明,对重要基因启动子区DNA甲基化及TFBS的生物信息学研究可为相关的实验研究提供指南,对促进基因表达的表观遗传调控研究具有重要意义.     

鼻咽癌细胞中上皮细胞钙黏蛋白基因启动子甲基化的研究

目的 探讨鼻咽癌细胞中上皮细胞钙黏蛋白(E-cadherin)启动子甲基化对基因表达的影响,以及经去甲基化药物5-杂氮-2'-脱氧胞苷(5-Aza-dC)作用后肿瘤细胞增殖与侵袭能力的变化.方法采用逆转录(RT)-PCR、Western blot与免疫组织化学(polymer法)检测经5-Aza-dC处理前后HNE1和CNE2细胞中E-cadherin的表达水平,以甲基化特异性PCR(MSP)分析启动子甲基化状态,以四甲基偶氮唑盐(MTT)比色法与侵袭实验测定细胞增殖与侵袭能力的变化.结果 HNE1和CNE2细胞中E-cadherin表达水平减弱,其启动子区域存在部分甲基化现象;经5-Aza-dC作用后可显著上调鼻咽癌细胞E-cadherin的表达水平,降低基因启动子甲基化程度,同时显著抑制肿瘤细胞的增殖能力与侵袭能力.经20 μmol/L 5-Aza-dC作用后,HNE1与CNE2细胞的增殖能力与未处理组相比分别降低27.6%和34.3%,P＜0.05;HNE1与CNE2细胞经5-Aza-dC药物处理后,通过滤膜迁移进至侵袭小室下腔的数量与未处理组相比分别减少37.2%和29.7%,P＜0.05.结论基因启动子区域高甲基化状态是导致E-cadherin表达水平下调的机制之一,应用去甲基化药物可恢复E-cadherin表达并抑制肿瘤细胞的恶性生物学特征.     

Differential DNA methylation profiles of peripheral blood mononuclear cells in allergic asthmatic children following dust mite immunotherapy

Background/PurposeAllergen-specific immunotherapy (SIT) is now considered curative to allergic diseases such as asthma. Mechanistically, our previous work showed DNA hypermethylation of cytokine genes, in T-helper cells, in allergic asthmatic children treated with allergen-SIT. In this study, we extended to work to assess possible changes in the DNA methylomes of peripheral blood mononuclear cells (PBMCs), isolated from mite allergen-SIT asthmatic children, to explore further the underlying methylation changes.MethodsThirteen allergic asthmatic children who received Der p-SIT, 12 non-SIT allergic asthmatic controls, and 12 healthy controls were enrolled. Bisulfite-converted DNA from Der p-stimulated PBMCs was analyzed using Human Methylation 450 k BeadChip. Pyrosequencing and quantitative real-time PCR were used to validate the DNA methylation levels and the gene expression of individual samples.ResultsWe identified 108 significantly differentially methylated regions (DMRs) unique to Der p-treated PBMCs, with 53 probes linked to demethylated DMRs, and 55 probes linked to methylated DMRs. Three associated genes (BCL6, HSPG2, and HSP90AA1), of selected DMRs, were subjected to bisulfite pyrosequencing. Of these, BCL6 showed significant hypomethylation, while HSPG2 and HSP90AA1 were hypermethylated in SIT group, compared to the AA group. Furthermore, SIT group had significantly higher gene expression of BCL6 and lower gene expression of HSPG2. KEGG pathway analysis further revealed DMR genes involved in ECM-receptor interactions, asthma, and antigen processing and presentation pathways.ConclusionsSeveral DNA regions showed DNA methylation altered by Der p specific immunotherapy, indicating desensitization-associated methylomes. Genes belonging to these SIT-altered pathways may represent therapeutic targets for better clinical management of asthma.     

急性白血病p53基因P1启动子区域DNA甲基化研究

目的：通过检测急性白血病（AL）中p53基因P1启动子异常甲基化，探讨p53基因异常甲基化在急性白血病中的意义。方法:分别使用限制性内切酶MspⅠ、HpaⅡ、EcoRⅡ、BstNⅠ酶切提取基因组DNA，然后分别使用酶切后产物及基因组DNA为模板进行PCR扩增。产物电泳后在凝胶成像分析系统内观测电泳条带及摄像；部分标本的电泳条带经凝胶回收纯化后进行测序。结果:急性白血病患者p53基因第一启动子甲基化阳性率为38.7％，而急性淋巴细胞白血病（ALL）与急性非淋巴细胞白血病(ANLL)患者分别为45.5％、35.0％。正常对照标本中未检测到p53基因的异常甲基化。p53基因甲基化情况在急性白血病病人与正常人之间经过统计学检验，P<0.05；但急性淋巴细胞白血病与急性非淋巴细胞白血病患者之间无显著差异，P>0.05。分析急性白血病患者p53基因甲基化与患者临床资料之间的关系，其中，p53基因异常甲基化与肝脾淋巴结是否肿大之间的关系经统计学分析P<0.05。结论:①部分急性白血病患者存在p53基因第一启动子异常甲基化，正常对照中未检测到p53基因的甲基化；②p53基因第一启动子在急性淋巴细胞白血病与急性非淋巴细胞白血病均可发生异常甲基化，两者之间发生甲基化的概率无统计学差异；③p53基因异常甲基化与肝脾淋巴结肿大有显著差异，但p53基因异常甲基化与急性白血病治疗效果及预后的关系尚不能确定，须进一步研究确定。     

Telomerase activity,telomere length and hTERT DNA methylation in peripheral blood mononuclear cells from monozygotic twins with discordant smoking habits

Increased telomerase expression has been implicated in the pathogenesis of lung cancer and, since the primary cause of lung cancer is smoking, an association between telomerase reactivation and tobacco smoke has been proposed. In this work an investigation has been performed to assess the relationship between tobacco smoke exposure and telomerase activity (TA) in peripheral blood mononuclear cells of healthy smokers. The methylation status of the catalytic subunit of telomerase hTERT was concurrently investigated to assess the possible association between epigenetic modifications of hTERT and TA. Besides, the association between smoke and telomere length (TL) has been evaluated. Healthy monozygotic twins with discordant smoking habits were selected as study population to minimize inter‐individual differences because of demographic characteristics and genetic heterogeneity. Statistically significant higher values of TA and TL were observed in smokers compared to nonsmoker co‐twins. The multivariate analysis of data showed, besides smoking habits (P = 0.02), an influence of gender (P = 0.006) and BMI (P = 0.001) on TA and a borderline effect of gender (P = 0.05) on TL. DNA methylation analysis, focused on 100 CpG sites mapping in hTERT, highlighted nine CpG sites differentially methylated in smokers. When co‐twins were contrasted, selecting as variables the intra‐twin difference in TA and hTERT DNA methylation, a statistically significant inverse correlation (P = 0.003) was observed between TA and DNA methylation at the cg05521538 site. In conclusion, these results indicate an association of tobacco smoke with TA and TL and suggest a possible association between smoke‐induced epigenetic effects and TA in healthy smokers. Environ. Mol. Mutagen. 58:551–559, 2017. © 2017 Wiley Periodicals, Inc.     

Immunoassay and molecular methods to investigate DNA methylation changes in peripheral blood mononuclear cells in HIV infected patients on cART

This study aimed to investigate the influence of antiretroviral therapy on methylation markers, in a group of HIV infected, heavily treated patients. Immune and molecular methods were used to investigate potential changes in methylation profile in DNA isolated from peripheral blood mononuclear cells collected from antiretroviral-experienced HIV infected patients and healthy controls. The percentage of 5-methylcytosine was inversely correlated with proviral DNA and active replication while DNMT1 (p = 0.01) and DNMT3A (p = 0.004) independently correlated with active viral replication. DNMT3A expression increased with total treatment duration (p = 0.03), number of antiretroviral drugs ever used (p = 0.003), and cumulative exposure to protease inhibitors (p = 0.02) even in currently HIV undetectable patients.     

CpG promoter methylation status is not a prognostic indicator of gene expression in beryllium challenge

Individuals exposed to beryllium (Be) may develop Be sensitization (BeS) and progress to chronic beryllium disease (CBD). Recent studies with other metal antigens suggest epigenetic mechanisms may be involved in inflammatory disease processes, including granulomatous lung disorders and that a number of metal cations alter gene methylation. The objective of this study was to determine if Be can exert an epigenetic effect on gene expression by altering methylation in the promoter region of specific genes known to be involved in Be antigen-mediated gene expression. To investigate this objective, three macrophage tumor mouse cell lines known to differentially produce tumor necrosis factor (TNF)-α, but not interferon (IFN)-γ, in response to Be antigen were cultured with Be or controls. Following challenges, ELISA were performed to quantify induced TNFα and IFNγ expression. Bisulfate-converted DNA was evaluated by pyrosequencing to quantify CpG methylation within the promoters of TNFα and IFNγ. Be-challenged H36.12J cells expressed higher levels of TNFα compared to either H36.12E cells or P388D.1 cells. However, there were no variations in TNFα promoter CpG methylation levels between cell lines at the six CpG sites tested. H36.12J cell TNFα expression was shown to be metal-specific by the induction of significantly more TNFα when exposed to Be than when exposed to aluminum sulfate, or nickel (II) chloride, but not when exposed to cobalt (II) chloride. However, H36.12J cell methylation levels at the six CpG sites examined in the TNFα promoter did not correlate with cytokine expression differences. Nonetheless, all three cell lines had significantly more promoter methylation at the six CpG sites investigated within the IFNγ promoter (a gene that is not expressed) when compared to the six CpG sites investigated in the TNFα promoter, regardless of treatment condition (p?<?1.17?×?10^?9). These findings suggest that, in this cell system, promoter hypo-methylation may be necessary to allow expression of metal-induced TNFα and that promoter hyper-methylation in the IFNγ promoter may interfere with expression. Also, at the dozen CpG sites investigated in the promoter regions of both genes, beryllium had no impact on promoter methylation status, despite its ability to induce pro-inflammatory cytokine expression.     

Detecting Epstein-Barr virus DNA from peripheral blood mononuclear cells in adult patients with systemic lupus erythematosus in Taiwan

Epstein-Barr virus (EBV) has been found by many serology studies to be associated with systemic lupus erythematosus (SLE). However, the results of DNA studies have been conflicting. Therefore, instead of antibody to EBV, we studied the association between EBV DNA and SLE. In this case-control study in Taiwan, we enrolled 87 SLE patients and 174 age- and sex-matched controls. Peripheral blood mononuclear cells of SLE patients and matched controls were tested for EBV DNA by polymerase chain reaction (PCR) and Southern blot. Of the 87 SLE patients, 71 (81.6%) were found to be positive for EBV DNA, while 85 (48.9%) of the 174 controls (odds ratio 4.64, 95% confidence interval 2.50–8.62, P<0.0001) were positive. While the EBV DNA-positive rate did not decline with age in SLE patients (P>0.05), it did decline with age in controls (P<0.05). Furthermore, based on a real-time quantitative PCR study, we have found a significant difference between EBV viral load in SLE and controls (P=0.008). Therefore, in our molecular study of DNA level, we found evidence for the association of EBV infection and SLE, suggesting that EBV contributes, if not to the development of SLE, then to disease perpetuation.