CpG-ODN下调HeLa细胞功能性Fas配体的表达

为观察CpG-ODN对宫颈癌细胞系HeLa细胞Fas配体(FasL)表达水平的影响,探讨其对由HeLa细胞Fas-FasL途径诱导的淋巴细胞凋亡作用。采用实时荧光RT-PCR方法检测HeLa细胞、正常宫颈上皮细胞中FasL和Jurkat T淋巴细胞中Fas的表达水平,应用HeLa细胞与Jurkat细胞共培养的方法体外研究HeLa细胞FasL诱导T淋巴细胞凋亡作用。结果显示:①HeLa细胞、正常宫颈上皮细胞中FasL表达阳性,其表达水平分别是(0.99±0.05)、(0.68±0.03),差别具有统计学意义(P=0.0007);Jurkat细胞Fas表达呈阳性;②HeLa细胞与Jurkat细胞共培养后Jurkat细胞的凋亡率为(38.23%±4.98%),应用抗体NOK-2中和HeLa细胞的FasL后,Jurkat细胞凋亡率减少为(3.54%±1.61%),两者相比,差别有显著性意义(P=0.0001);③HeLa细胞用CpG-ODN处理前后FasL的表达水平分别是(0.99±0.05)、(0.79±0.04),差别有统计学意义(P=0.005);CpG-ODN预处理的HeLa细胞与Jurkat细胞共培养后Jurkat细胞凋亡率为(6.41%±2.81%),而没有用CpG-ODN预处理的HeLa细胞与Jurkat细胞共培养Jurkat细胞凋亡率为(29.23±6.85)%,二者的差别有统计学意义(t=13.39,P=0.006)。HeLa细胞可能通过表达FasL主动诱导T淋巴细胞凋亡从而在肿瘤的免疫逃逸中发挥作用,CpG-ODN可通过下调FasL的表达而减少肿瘤细胞主动诱导的T淋巴细胞凋亡。     

雷公藤红素诱导CEM-6T细胞凋亡的机制研究

在已经证明雷公藤红素能诱导人T淋巴细胞株CEM 6T细胞凋亡的基础上 ,进一步探讨此凋亡过程的机制。本项目研究雷公藤红素诱导CEM 6T细胞凋亡过程中Fas/FasL、ICEmRNA的变化以及ICE抑制剂、磷酸酶抑制剂对凋亡的影响。结果发现 ( 1)CEM 6T细胞表达Fas,不表达FasL ,雷公藤红素处理不能改变这一情况 ;( 2 )雷公藤红素不能改变ICEmRNA的表达水平 ,但ICE抑制剂Ac YVAD CHO能使雷公藤红素诱导CEM 6T的凋亡率下降 ;( 3) 1 5 μmol/L磷酸酶抑制剂okadaicacid能使凋亡率下降。提示雷公藤红素诱导CEM 6T细胞凋亡不依赖Fas/FasL ,而与细胞内原已存在的ICE有关 ,蛋白去磷酸化参与了此凋亡过程     

血必净对活化诱导T细胞凋亡的调节

目的 观察活化诱导对脾脏T淋巴细胞凋亡、凋亡相关基因mRNA表达及caspase3活性的影响,以及活血化瘀中药的调节作用.方法 提取BALB/c小鼠脾脏T淋巴细胞并培养,以Con A+IL-2诱导T细胞活化凋亡,MTT法检测细胞增殖活性,流式细胞仪检测细胞凋亡率,RT-PCR检测Fas、FasL、Bcl-2、Bax、IL-2 mRNA表达水平,分光光度法测定caspase3酶活性,并观察活血化瘀中药对上述各项指标的影响.结果 活化T淋巴细胞于诱导18h后凋亡率明显增加,于诱导6h时未见FasL、Bax mRNA表达,Fas、Bcl-2 mRNA表达无明显变化;于诱导18 h后Fas、FasL、Bax mRNA表达升高,Bel-2 mRNA表达下降,caspase3活性增高.活血化瘀中药可降低T细胞凋亡,并可分别降低Fas、FasL、Bax mRNA表达,提高Bcl-2 mRNA表达,减轻easpase3酶活性.在活化诱导早期(6 h)促进T淋巴细胞内IL-2 mRNA表达,在晚期(18 h)减少IL-2 mRNA表达.结论 过度活化是脾脏T淋巴细胞异常凋亡的诱发因素,而凋亡的发生与Fas、FasL、Bax、Bcl-2 mRNA表达的改变有关.活血化瘀中药可通过调节IL-2及凋亡相关基因mRNA表达而减轻脾脏T淋巴细胞凋亡,同时可以促进T淋巴细胞的增殖活性.     

复发性自然流产患者主动免疫治疗前后外周血淋巴细胞Fas/FasL表达水平的研究

目的研究复发性自然流产(RSA)患者外周血淋巴细胞Fas/FasL表达水平,探讨Fas/FasL系统与RSA的发病关系以及主动免疫治疗对RSA患者外周血淋巴细胞Fas/FasL表达水平的影响。方法收集2009年6月至2010年4月在汕头大学医学院附属粤北人民医院妇产科门诊就诊的早孕期RSA患者12例,未孕期RSA患者15例作为研究组,采用荧光标记流式细胞分析技术分别检测主动免疫治疗前后外周血淋巴细胞Fas、FasL表达水平,选择同期正常早孕妇女15例,正常未孕妇女15例作为对照组,比较各组Fas、FasL表达水平的差异。结果 (1)未孕组中,RSA患者外周血NK细胞和CD8+T细胞Fas的表达水平均比正常妇女高,NK细胞FasL表达水平比正常妇女低(P<0.05),CD8+T细胞FasL、CD4+T细胞Fas、FasL的表达水平两组相比无明显差异(P>0.05);(2)早孕组中,RSA患者外周血NK细胞Fas、FasL的表达水平均比正常妇女低,CD8+T细胞Fas表达水平比正常妇女高(P<0.05),CD8+T细胞FasL、CD4+T细胞Fas、FasL的表达水平两组相比则无明显差异(P>0.05);(3)主动免疫治疗后RSA患者(早孕组和未孕组)外周血NK细胞和CD8+T细胞的Fas表达水平均较治疗前下降,FasL表达水平均较治疗前上升,差异有统计学意义(P<0.05),CD4+T细胞Fas、FasL的表达水平与治疗前相比无明显差异(P>0.05)。结论 (1)外周血NK细胞和CD8+T细胞Fas表达升高,FasL表达不足是导致RSA发生的重要免疫学因素之一。(2)主动免疫治疗可能通过改变RSA患者外周血NK细胞和CD8+T细胞的Fas/FasL表达水平,改善细胞凋亡状态而取得疗效。     

膜FasL的纯化与诱导凋亡功能的鉴定

本文用FasL单抗NOK 1与CNBr Sepharose4B偶联 ,制备亲和层析柱 ,从表达FasL的HEpG2细胞膜蛋白抽提液中分离纯化FasL分子。实验证明用本法纯化的FasL其相对分子质量为 3 10 0 0～ 3 3 0 0 0 ,SDS PAGE呈现单一条带 ,Westernblot表明具有一定的抗原性 ,能诱导表达Fas的细胞发生凋亡 ,在一定浓度范围内呈现量 效关系 ,为进一步研究FasL分子的结构功能及制备抗体提供了实验材料。     

可溶性HLA-G1上调活化的同种反应性T细胞表达FasL促进其凋亡

目的探讨可溶性HLAG1对活化的同种反应性T细胞FasL表达及凋亡的影响。方法借助基因工程技术构建表达可溶性HLAG1的真核表达质粒;把重组质粒转染入宿主细胞,表达可溶性HLAG1并借助免疫亲和层析技术纯化可溶性HLAG1蛋白;用EB病毒转化的同种异体B淋巴细胞作为刺激细胞,通过长期混合淋巴细胞培养,激活同种反应性T细胞。活化T细胞经不同浓度可溶性HLAG1处理12h后,用Westernblot法检测其FasL表达情况;处理24h后,用FACS检测其凋亡情况。结果可溶性HLAG1能够上调活化的同种反应性T细胞表达FasL;能够促进活化的T细胞发生凋亡,且上述作用具有剂量依赖性。结论可溶性HLAG1分子能够使活化的同种反应性T细胞表达FasL升高,进而促进其凋亡。     

Fas,FasL与Ⅰ型糖尿病

Fas和FasL是细胞表面的两种跨膜蛋白.当一个细胞的Fas与另一个细胞的FasL结合时,可诱导表达Fas的细胞凋亡;胰岛中浸润的T淋巴细胞表达FasL可以使表达Fas的胰岛β细胞发生凋亡.Fas诱导的胰岛β细胞凋亡可能在1型糖尿病的发生发展中起重要作用.     

Fas,FasL与1型糖尿病

Fas和FasL是细胞表面的两种跨膜蛋白.当一个细胞的Fas与另一个细胞的FasL结合时,可诱导表达Fas的细胞凋亡;胰岛中浸润的T淋巴细胞表达FasL可以使表达Fas的胰岛β细胞发生凋亡.Fas诱导的胰岛β细胞凋亡可能在1型糖尿病的发生发展中起重要作用.     

rhIL-2与阿霉素白蛋白磁微球靶向治疗肿瘤的协同作用

目的：观察重组人白细胞介素-2(rhIL-2)瘤内注射和阿霉素白蛋白磁微球(ADM-MAM)联合外磁场联合治疗H22荷瘤小鼠的协同作用，并探讨其抗肿瘤作用机制。方法：以荷瘤小鼠的瘤重为指标，观察药物的抗肿瘤活性。以乳酸脱氢酶释放法测NK细胞的杀伤活性。以MTT比色法测淋巴细胞的转化率。以流式细胞术检测肿瘤细胞的凋亡及p53、Fas和FasL的表达。用RT—PCR法测定IL—2及IL—12的表达。探讨抗肿瘤机制。结果：ADM—MAM靶向治疗与rhIL—2联用，可显著减小荷瘤小鼠的瘤重；提高NK细胞的杀伤活性和脾脏淋巴细胞的转化率；减小肿瘤细胞的增殖指数，上调肿瘤细胞p53、Fas和FasL的表达，以及增加脾脏淋巴细胞上IL—2及IL—12的表达。结论：ADM—MAM联合外磁场，具有显著增强抑瘤的作用。rhIL—2能增强ADM—MAM靶向治疗的抗肿瘤作用，其抗肿瘤协同作用主要是通过促进T细胞增殖，刺激NK细胞增长等提高机体的免疫功能而实现的。     

白介素12诱导T细胞凋亡时Fas/FasL表达和信号转导的研究

目的:为了解和探讨白介素12(IL-12)作用于T细胞,活化T细胞表面的IL-12受体β1/β2复合物,调节Th1/Th2平衡,诱导T细胞凋亡时对Fas/FasL表达和信号传导的作用。方法:用AnnexinV的方法流式细胞仪检测细胞凋亡;用半定量PCR的方法测定在不同抑制剂作用下对Fas/FasL信号传导的影响。结果:IL-12诱导人TIB-152、HTB-176和正常T细胞的凋亡;IL-12可上调T细胞的FasLmRNA表达。在IL-12作用6h后FasL的表达明显升高,表达的高峰值在24h。HA100抑制剂能促进T细胞的凋亡,PKC抑制剂是IL-12诱导T细胞凋亡信号传导的负性调节因子;AG490抑制剂不抑制IL-12上调的FasLmRNA表达作用,说明其阻断的Jak2通路不参与IL-12对FasL表达的信号传导过程;HA1004不影响T细胞表达FasLmRNA。结论:IL-12能诱导TIB-152、HTB-176和正常人T细胞的凋亡。FasL作为介导分子参与此过程,IL-12对T细胞FasLmRNA表达信号传递与PKC通路有关。而Jak2及PKA通路不参与此过程.     

幽门螺杆菌致T细胞凋亡：Fas/FasL介导的T细胞无反应性

目的 评价幽门杆菌（Hp）致T细胞死亡的方式和机制,探讨这种作用与Hp感染致宿主产生免疫耐受的关系。方法 应用AnnexinV染色流式细胞术检测Hp致T细胞死亡的方式;应用细胞毒实验（JAM技术）和FasIgG抗体、caspase8抑制剂组断实验评价T细胞凋亡与Fas/FasL作用的关系,并通过流式细胞术直接检测Hp对T细胞FasL表达的上调作用及其与T细胞产生凋亡的时效关系。结果 AnnexinV染色和JAM技术证实H致T慢以凋亡方式进行的。这种细胞凋亡能被抗Fas抗体和caspase8抑制剂阻断,因而是Fas依赖,TH2细胞较TH1样T细胞对这种作用更敏感。由于Hp能直接上调T细胞的FasL且其发生时间与凋亡出现时间吻合,证实Hp是通过凋节T细胞之间Fas/FasL相互作用而致其凋亡的。Hp能通过调节Fas/FasL作用而负调节T细胞的生长,这可能是Hp感染致宿主发生T细胞耐受的机制之一。     

特异性ASODN抑制Fas表达降低FasL介导细胞凋亡的研究

为了研究特异性Fas反义寡核苷酸(ASODN)对T细胞Fas表达及肝癌细胞诱导其凋亡的抑制作用,用脂质体介导法将Fas ASODN导入Jurkat T细胞,并通过用流式细胞术、RT-PCR及与肝癌细胞共培养方法研究Fas ASODN对T细胞Fas表达、Fas mRNA水平及凋亡的影响。结果显示:①Hep G2.2.15细胞表达有功能的FasL,可诱导Jurkat细胞凋亡;②Jurkat细胞转染Fas ASODN后,Fas mRNA降低;细胞表面Fas表达下降;与Hep G2.2.15细胞共培养后的凋亡率下降。表明Fas ASODN转染可以部分逆转肝癌细胞对T细胞的凋亡诱导作用。     

ICA、PJA逆转人高转移肺癌细胞Fas/FasL途径免疫逃逸机制的研究

目的：研究ICA、PJA对人高转移肺癌细胞PG细胞免疫逃逸的逆转作用。方法：MTT法检测ICA、PJh对PG细胞增殖的影响以及对CD3AK杀伤敏感性的影响。流式细胞仪检测细胞表面分子Fas、FasL表达水平和细胞凋亡。应用PG细胞与Jurkat T细胞其培养的方法体外研究FasL诱导T淋巴细胞凋亡的作用。结果：PG细胞高表达FasL，低表达Fas，对CD3AK细胞杀伤敏感性较低，并在与Jurkat T细胞共培养中诱导高表达Fas的Jurkat T细胞凋亡。：ICA、PJA对PG细胞有明显的增殖抑制作用。ICA可明显提高PG细胞Fas的表达率。ICA、PJA可明显降低PG细胞FasL的表达率。ICA、PJA可使PG细胞与Jurkat T细胞共培养中，降低Jurkat T细胞的凋亡率。ICA、PJA可提高CD3AK细胞对PG细胞的杀伤活性。结论：ICA、PJA可逆转人高转移肺癌细胞PG通过Fas／FasL途径逃避机体免疫活性细胞的攻击。     

Taurine attenuates CD3/interleukin-2-induced T cell apoptosis in an in vitro model of activation-induced cell death (AICD)

Interleukin (IL)-2 immunotherapy is used for the treatment of metastatic melanoma and renal cell carcinoma and mediates its effects through the clonal expansion of lymphocytes. Although IL-2 remains the most effective form of therapy for these cancers, response rates are poor and dose escalation is hampered by side effects, which include vascular leak and lymphopenia. The mechanism underlying T cell loss is currently unidentified but could be the induction of activation-induced cell death (AICD) mediated by FasL. Our previous studies have shown that the amino acid taurine can attenuate apoptosis induced by a number of factors in different cell types. Here, we induced T cell AICD via CD3 and IL-2 stimulation and investigated the effect of taurine on lymphocyte apoptosis. Anti-CD3-activated Jurkat T cells treated with IL-2 significantly increased FasL expression, which was associated with increased apoptosis. Treatment with taurine prior to stimulation down-regulated FasL protein expression and partially inhibited apoptosis. Inhibition of FasL-signalling resulted in an identical reduction in apoptosis. As the kinetics of AICD are completely different in circulating T cells, we repeated these experiments in such cells to confirm our finding. Stimulation of CD4(+) circulating T cells induced apoptosis in sensitized, but not freshly isolated T cells, which was abrogated partially by taurine. In Jurkat cells it was determined that taurine-mediated down-regulation of FasL protein expression was associated with decreased FasL mRNA expression and reduced NFkappaB activation. These results reveal one possible mechanism underlying the lymphopenia observed with IL-2 immunotherapy, involving increased FasL expression leading to apoptosis. Taurine may be of use in reversing the lymphopenia associated with IL-2, thereby augmenting its immunotherapeutic potential.     

Apoptosis induced in T cells by human neuroblastoma cells: role of Fas ligand

The CD95/CD95L (Fas/Fas ligand) receptor/ligand system plays an important role in regulation of cell survival and induction of a programmed cell death. It is also involved in regulation of effector phase of T and NK cell cytotoxicity, establishment of immune privilege sites, and tumor escape from immune recognition. In this study, we assessed expression of CD95L in tumors obtained from patients with neuroblastoma (NB) and in established NB cell lines. We measured the presence of intratumoral T cell infiltrates and T cell survival in tumor tissue samples. High levels of apoptosis were observed in tumor-associated lymphocytes as well as in Jurkat T cells cocultured with NB cells in vitro. T cell death was reduced after treatment of NB cells (in vitro) with antibody to FAS ligand (FasL). Overall, our data suggest that NB-induced apoptosis of Fas-sensitive Jurkat T cells is mediated by functional FasL expressed on NB and Fas/FasL interaction may be responsible for the elimination of T cells in the NB microenvironment.     

Human urinary bladder transitional cell carcinomas acquire the functional Fas ligand during tumor progression

The interaction between FasL on tumor cells and Fas on lymphocytes may represent a tumor immune escape mechanism. We explored FasL expression and function in human urinary bladder transitional cell carcinomas (TCCs). FasL expression was observed in situ in 45% of TCCs (n = 45) and was absent in normal urothelium (n = 20). A correlation existed between FasL expression and high tumor grade (0% in G1, 14% in G2, and 75% in G3; P < 0.0001) and stage (13% in superficial Ta-T1 versus 81% in invasive T2-T4; P < 0.0001). FasL function was shown by the ability of two FasL-positive primary culture TCC cell lines (established from two FasL-positive invasive TCCs) to induce Fas-mediated killing not only of conventional Fas-sensitive targets (such as Jurkat cells or phytohemagglutinin-lymphoblasts), but also of autologous T lymphocytes generated in a mixed lymphocyte tumor-cell culture. In addition, an association between FasL expression by TCC cells and activated caspase-8, -9, and -3 expression by interferon-gamma-producing CD8-positive tumor-infiltrating lymphocytes was observed in situ. Our results show a functional expression of TCC-expressed FasL that correlates with tumor progression. These results suggest that TCC-expressed FasL may induce apoptosis of anti-tumor T lymphocytes in vivo, providing new insights on the mechanisms involved in bladder TCC progression.     

Suppression of FasL expression in tumor cells and preventing tumor necrosis factor-induced apoptosis by adenovirus 14.7K is an effective escape mechanism for immune cells

To elucidate if the Fas/FasL signal pathway participates in the immune escape of tumor cells, and if contemporary Fas/FasL and tumor necrosis factor (TNF))-induced apoptosis is better for immune cell survival than just blocking Fas/FasL-induced apoptotic signal. FasL expression in mouse H22 hepatocellular cancer cells was suppressed by the siRNA technique. The wild-type Ad5 14.7K gene was amplified by polymerase chain reaction and transduced into Jurkat T-cells. Apoptosis of target Jurkat cells was detected by flow cytometry. TNF-alpha in the culture supernatant of H22 cells by ELISA was seen. FasL and 14.7K gene expression in stably transfected or transduced clones were determined by Western blotting. As a result, FasL expression in H22 cells was down-regulated after stable transfection with a plasmid encoding antisense FasL cDNA. Down-regulation of FasL expression in H22 cells had no effect on tumor growth in vitro. There was an apparent decrease in the number of apoptotic Jurkat T-cells after coculture with transfected H22 cells, relative to coculture with FasL-expressing untransfected cells. Compared with untransduced Jurkat cells, apoptotic rates in 14.7K-transduced Jurkat cells were significantly reduced in three different E/T ratios (P < 0.01), respectively. We conclude that Fas/FasL signal pathway participates in the immune escape of tumor cells by inducing immune cells apoptosis. Reducing the expression of FasL in tumor cells can decrease the apoptotic rate of immune cells, further blocking the apoptotic signal pathway of immune cells by preventing TNF-induced apoptosis can increase the survival of immune cells.     

Activated cytotoxic lymphocytes promote tumor progression by increasing the ability of 3LL tumor cells to mediate MDSC chemoattraction via Fas signaling

The Fas/FasL system transmits intracellular apoptotic signaling, inducing cell apoptosis. However, Fas signaling also exerts non-apoptotic functions in addition to inducing tumor cell apoptosis. For example, Fas signaling induces lung cancer tumor cells to produce prostaglandin E2 (PGE2) and recruit myeloid-derived suppressor cells (MDSCs). Activated cytotoxic T lymphocytes (CTLs) induce and express high levels of FasL, but the effects of Fas activation initiated by FasL in CTLs on apoptosis-resistant tumor cells remain largely unclear. We purified activated CD8⁺ T cells from OT-1 mice, evaluated the regulatory effects of Fas activation on tumor cell escape and investigated the relevant mechanisms. We found that CTLs induced tumor cells to secrete PGE2 and increase tumor cell-mediated chemoattraction of MDSCs via Fas signaling, which was favorable to tumor growth. Our results indicate that CTLs may participate in the tumor immune evasion process. To the best of our knowledge, this is a novel mechanism by which CTLs play a role in tumor escape. Our findings implicate a strategy to enhance the antitumor immune response via reduction of negative immune responses to tumors promoted by CTLs through Fas signaling.