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.     

CD4+ CD25+调节性T细胞AICD机制的研究

目的探讨CD4^＋CD25^＋调节性T细胞活化诱导的细胞死亡（AICD）发生的机制。方法CD4^＋CD25^＋T细胞以磁性细胞分离器（MACS）从BALB／c小鼠或DO11．10小鼠的静息T细胞分离纯化。体外细胞增殖抑制实验证实其免疫调节作用。CD4^＋CD25^＋T细胞的AICD以CD3／CD28单克隆抗体活化或以特异性OVA323-339肽、抗原提呈细胞活化等两种方法获得。CD4^＋CD25^＋T细胞凋亡相关基因的表达通过实时定量PCR检测。流式细胞仪检测细胞的凋亡率。进一步观察FasL中和抗体、TRAIL中和抗体及caspase抑制剂zVAD-fmk对CD4^＋CD25^＋T细胞凋亡的影响。结果MACS成功分离CD4^＋CD25^＋T细胞，纯度可达98％，该细胞可特异性表达Foxp3基因，能明显抑制效应性T细胞的体外增殖。CD3／CD28抗体以及OVA特异性抗原活化8d的CD4^＋CD25^＋调节性T细胞AICD达39％～45％。活化前后的CD4^＋CD25^＋调节性T细胞死亡受体家族表达发生明显变化；FasL、TRAIL中和抗体及zVAD-fmk可明显抑制CD4^＋CD25^＋调节性T细胞的凋亡。结论FasL／Fas及其他凋亡相关分子可能参与了CD4^＋CD25^＋调节性T细胞的凋亡。     

SLE患者外周血T细胞亚群凋亡特点及其相关机制的研究

目的:研究系统性红斑狼疮(SLE)患者外周血CD3+、CD4+、CD8+T细胞亚群的凋亡特点及其相关的凋亡机制。方法:采用三色荧光流式细胞术检测高活动性SLE患者、低/非活动性SLE患者以及正常对照者外周血T细胞亚群的百分比例、T细胞亚群膜表面Fas/FasL的表达率、T细胞亚群早期凋亡(AV+PI-)的情况;采用ABC-ELISA法测定各组SLE患者和正常对照者血清IL-10水平;对10例血清IL-10水平异常升高的高活动性SLE患者进行体外PBMCs培养实验,其中分别加入抗FasL抗体和抗IL-10抗体,48小时常规培养后分别检测PBMCs中T细胞亚群百分比例、T细胞亚群膜表面Fas/FasL的表达率、T细胞亚群早期凋亡的变化。结果:SLE患者外周血T细胞凋亡异常增多,其中以高活动性SLE患者CD4+T细胞亚群的凋亡尤为显著(P0.05),CD4+T细胞的异常凋亡与CD4+和CD8+T细胞膜表面表达增高的Fas/FasL密切相关(P0.05);各组SLE患者外周血血清IL-10水平均明显升高(P0.01),高活动性SLE患者更为明显,血清IL-10水平升高不仅与SLE主要临床检验指标相关,而且与CD4+/CD8+比值减少、CD4+T细胞高表达FasL相关(P0.05);随访研究显示,随着SLE病情好转、稳定,血清IL-10水平下降明显、T细胞亚群Fas/FasL的表达率明显减少、T细胞亚群凋亡逐渐减少,以上变化均在CD4+T细胞亚群中体现得最为明显(P0.05)。结论:SLE患者T细胞活动性异常升高,尤其是CD4+T细胞亚群凋亡增加,是SLE疾病发展的重要病理机制,IL-10作为能诱导T细胞高表达Fas/FasL的重要调节因子,参与了SLE患者CD4+T细胞凋亡的免疫调节,SLE患者异常增高的IL-10很可能通过Fas/FasL途径促进了T细胞尤其是CD4+T细胞亚群的凋亡。     

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.     

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     

呼吸道合胞病毒感染对细胞凋亡及FasL、Fas、Bcl-2、Bax基因表达的研究

目的：研究呼吸道合胞病毒(RSV)感染与细胞凋亡的关系及对凋亡相关基因FasL、Fas、bcl-2和bax表达的影响。 方法： 采用A549细胞，在RSV感染后不同时点收集细胞，流式细胞仪和透射电镜检测细胞凋亡，免疫组织化学法检测凋亡相关基因FasL、Fas、Bcl-2和Bax表达情况。 结果： 流式细胞仪检测结果RSV感染后72 h（6.61%）、120 h（10.94%）的细胞凋亡指数明显高于对照组（4.32%、5.31%）；免疫组化法检测结果对照组FasL、Bax基因呈现无表达或局部弱表达；随着RSV感染时间的延长，bax、 Fas、 FasL基因的表达均高于对照细胞，bcl-2基因呈现弱表达或无表达。 结论： RSV在感染后期能诱导宿主细胞发生凋亡，促凋亡基因FasL、Fas 、Bax和抗凋亡基因Bcl-2表达水平的差异是RSV诱导凋亡的机制之一。     

CD3/TCR复合物抗体诱导不成熟胸腺细胞亚群的凋亡

目的：采用AnnexinV,PI染色，流式细胞仪分析的方法、DNA琼脂糖电泳法检测不同CD3/TCR复合物抗体对小鼠胸腺T淋巴细胞亚群的促凋亡作用。方法：新鲜分离胸腺细胞，加入PMA、anti-TCR anti-CD28 mAb,anti-TCR mAb等培养20小时，AnnexinV,PI,CD4,CD8细胞染色以及TCR三染，进行FACS分析，同时抽提培养细胞DNA进行琼脂糖电泳。结果：PMA IONO诱导胸腺T细胞的凋亡作用最强，anti-TCR anti-CD28 mAb次之，anti-TCR mAb最弱。结论：AnnexinV,PI细胞染色，流式细胞仪分析的方法可以灵敏检测T淋巴细胞的凋亡；anti-TCR anti-CD28 mAb能明显增强anti-TCR mAb促不成熟的CD4^ CD8^ TCR^ 和CD4^ TCR^ 细胞的凋亡作用；不成熟T细胞经TCR与自身抗原结合的活性过程能产生克隆删除从而产生自我耐受。     

Fas/FasL途径介导的人肺癌细胞免疫逃逸

目的：观察在3种人肺癌细胞（A549、EBC-1、LCSC）和人T细胞(Jurkat) Fas/FasL表达情况，探讨人肺癌细胞免疫逃逸及反杀伤作用与Fas/FasL途径的关系。 方法： 用FACScan、RT-PCR方法检测Fas/FasL蛋白及mRNA表达；以荧光染色法观察细胞调亡；用台盼蓝拒染法检测细胞存活。 结果： 3种人肺癌细胞及T-细胞系(Jurkat)均表达 Fas及 FasL；肺癌细胞与Jurkat细胞共培养时，肺癌细胞可导致Jurkat细胞生长抑制(P<0.05)及凋亡；在共培养体系中加入FasL中和性抗体NOK1，可封闭肺癌细胞对Jurkat细胞的生长抑制作用(P>0.05)。 结论： Fas/FasL途径可介导上述3种人肺癌细胞对Jurkat细胞的生长抑制及致凋亡作用；中和性抗体可有效阻断Fas信号转导途径，抑制肿瘤细胞的反杀伤作用，有效保护免疫系统。     

IFNγ调控人肺癌A549细胞Fas／FasL表达对T淋巴细胞生长的影响

为探讨IFNγ调控有肺癌细胞Fas/FasL表达对T细胞生长的影响，分别采用FACScan,RT-PCR方法检测Fas/FasL蛋白质及mRNA表达；以荧光染色及FACScan法观察细胞凋亡；用苔酚兰排除实验分析细胞生长。结果表明，人肺癌细胞A549及T－细胞系（Jurkat)均有Fas及FasL表达；IFNγ可引起A549Fas表达上调，且与剂量相关，并增加了A549细胞凋亡诱导的敏感性；A549细胞与Jurkat细胞共培养实验证明：人A549细胞通过Fas/FasL介导导致Jurkat细胞生长抑制及凋亡诱导；IFNγ处理A549细胞后，减少了其对Jurkat细胞的生长抑制。上述结果提示：Fas/FasL途径介导了A549细胞与Jurkat细胞之间的凋亡，IFNγ通过对人肺癌细胞Fas/FasL系统表达调控，使A549细胞自身对凋亡诱导的敏感性增加，并对T细胞生长的抑制作用减弱，提示IFNγ在防止肿瘤细胞逃避免疫监控有一定作用。     

IL-12诱导T细胞凋亡对Fas/FasL和TNFR/TNFα表达的影响

目的:探讨白介素12(IL-12)诱导T细胞凋亡过程中对T细胞的Fas/FasL和TNFR/TNFα表达的影响作用.方法:dUTP缺口末端标记法和Annexin V法;用FITC标记TNFR1,PE标记CD95,生物素标记FasL, 流式细胞仪检测3种T细胞(人淋巴瘤T细胞株HTB176、人急性白血病T细胞株TIB152和正常人T细胞)的百分率;用半定量PCR的方法检测FasL和TNFα的mRNA的表达作用.结果:HTB176和TIB152的细胞在IL-12处理1 h,生物素标记FasL百分率和FasL的mRNA表达率开始增加,24 h达到高峰,但正常T细胞在24 h后才有反应;正常T细胞经IL-12处理1 h内细胞FasL百分率和FasL的mRNA表达率开始增加,在以后的试验期 6、12、24 h始终保持恒定水平;但3种T细胞在IL-12作用下不促进细胞CD95和TNFR1及TNFα的表达.结论:IL-12诱导T细胞凋亡中有许多调节因子的协调作用,但作用机制是不同的.     

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。     

Gemcitabine sensitizes lung cancer cells to Fas/FasL system‐mediated killing

Gemcitabine is a chemotherapy agent commonly used in the treatment of non‐small cell lung cancer (NSCLC) that has been demonstrated to induce apoptosis in NSCLC cells by increasing functionally active Fas expression. The aim of this study was to evaluate the Fas/Fas ligand (FasL) system involvement in gemcitabine‐induced lung cancer cell killing. NSCLC H292 cells were cultured in the presence or absence of gemcitabine. FasL mRNA and protein were evaluated by real‐time PCR, and by Western blot and flow cytometry, respectively. Apoptosis of FasL‐expressing cells was evaluated by flow cytometry, and caspase‐8 and caspase‐3 activation by Western blot and a colorimetric assay. Cytotoxicity of lymphokine‐activated killer (LAK) cells and malignant pleural fluid lymphocytes against H292 cells was analysed in the presence or absence of the neutralizing anti‐Fas ZB4 antibody, by flow cytometry. Gemcitabine increased FasL mRNA and total protein expression, the percentage of H292 cells bearing membrane‐bound FasL (mFasL) and of mFasL‐positive apoptotic H292 cells, as well as caspase‐8 and caspase‐3 cleavage. Moreover, gemcitabine increased CH11‐induced caspase‐8 and caspase‐3 cleavage and proteolytic activity. Cytotoxicity of LAK cells and pleural fluid lymphocytes was increased against gemcitabine‐treated H292 cells and was partially inhibited by ZB4 antibody. These results demonstrate that gemcitabine: (i) induces up‐regulation of FasL in lung cancer cells triggering cell apoptosis via an autocrine/paracrine loop; (ii) induces a Fas‐dependent apoptosis mediated by caspase‐8 and caspase‐3 activation; (iii) enhances the sensitivity of lung cancer cells to cytotoxic activity of LAK cells and malignant pleural fluid lymphocytes, partially via Fas/FasL pathway. Our data strongly suggest an active involvement of the Fas/FasL system in gemcitabine‐induced lung cancer cell killing.     

Induction of FAS ligand expression in a human hepatoblastoma cell line by HCV core protein

Tumour cells and virus infected cells expressing Fas ligand (FasL) can evade immune surveillance by inducing apoptosis in T cells expressing Fas. In order to characterise a possible role of hepatitis C virus (HCV) core protein in similar mechanisms during HCV infection, we investigated Fas ligand expression and activity in a human hepatoblastoma cell line (HepG2) constitutively expressing this protein.Strong FasL induction was detected by immunoblotting and flow cytometry analysis in the core expressing cell lines Hep39. In contrast, vector transfected cells or cell lines expressing HCV E1-E2 proteins did not show FasL expression. Co-cultivation experiments of Hep39 cells with a Fas-sensitive T cell line indicated that FasL induced by the core protein had apoptotic activity toward target cells. Effect of the core protein on induction of FasL promoter was further examined by co-transfection of HepG2 cells with core-bearing plasmid and a vector in which luciferase gene expression is driven by human FasL promoter. Results of the luciferase assay indicated a positive regulation of FasL promoter by the core protein. In conclusion, HCV core protein plays a role in the induction of functional FasL in hepatoblastoma cell line and apoptosis in a target T cell line expressing Fas. Similar mechanisms may contribute, in vivo, to establishment of chronic infection and development of hepatocellular carcinoma (HCC).     

Retinoids induce Fas(CD95) ligand cell surface expression via RARgamma and nur77 in T cells

Cells from the CD4+ murine T hybridoma line IP-12-7 enter the apoptotic suicide program via the Fas ligand (FasL)/Fas-mediated pathway upon TCR stimulation. This stimulus regulates the sensitization of the Fas death pathway and the cell surface appearance of preformed FasL. The apoptosis is dependent on new mRNA and protein synthesis and involves up-regulation of nur77.Two groups of nuclear receptors for retinoic acids (RA) have been identified: retinoic acid receptors (RAR) and retinoid X receptors. IP-12-7 cells express RARalpha and RARgamma. Here we show that,in the IP-12-7 T cells, RA also induced the expression and DNA binding of nur77, and the cell surface appearance of FasL. The induction was mediated via RARgamma. Despite the induced expression of cell surface FasL, only two structurally related RARgamma-selective compounds, CD437 and CD2325, initiated apoptosis in these cells. The lack of apoptosis induction by natural RA was related to the inability of RARgamma to sensitize the Fas death-pathway. Cell surface FasL, however, was able to induce cell death in Fas-bearing target cells. Natural RA also induced the expression of FasL in phytohemagglutinin-activated peripheral murine T cells. It is proposed that therapeutically administered RA might induce apoptosis in Fas-sensitive cells via induction of FasL expression in activated Tcells.     

Correlation between expression of DcR3 on tumor cells and sensitivity to FasL

To investigate the correlation between sensitivity to Fas ligand （FasL） and expression level of decoy receptor 3 （DcR3） on tumor cell surface, Fas/DcR3 mRNA expression was detected by RT-PCR. Anti-DcR3 mAb was used to detect expression level of DcR3 on surface of tumor cells by flow cytometry. Caspase-8, caspase-9, caspase-3, Bcl-2 expressions were analyzed by Western blot, respectively. Sensitivity to apoptosis induced by FasL was determined by Annexin V apoptosis kit. The expressions of DcR3 on the surface of tumor cells from high to low were approximately 35.3% in BGC823 cells, and 21.6% in MCF-7 cells, respectively. The apoptotic rates induced by FasL from low to high were 15.6% in BGC823 cells, and 58.2% in MCF-7 cells, respectively. There was a significant correlation between the expression levels of DcR3 with FasL-inducing apoptosis. Cellular ＆ Molecular Immunology.     

Mechanisms of peripheral T cell deletion: anergized T cells are Fas resistant but undergo proliferation-associated apoptosis

The complementary receptor pair Fas ligand: Fas controls apoptosis during activation-induced cell death (AICD) of peripheral T cells sensitized for the Fas signal pathway by interleukin-2 (IL-2). In the present study, we used the bacterial superantigen staphylococcal enterotoxin B (SEB) to anergize ligand-reactive peripheral T cells in wild-type and Fas-defective lpr mice. In a second step, we investigated whether apoptosis in anergized and thus operationally IL-2-defective peripheral T cells is triggered via the Fas signal pathway. We report here that SEB-driven anergy induction and deletion of anergized peripheral Vβ8⁺ T cells is similar in wild-type and healthy C3H/lpr mice. In monitoring SEB-driven Vβ8⁺ T cell apoptosis in situ, we observe in both wild-type and lpr mice an intimate association between proliferation and apoptosis of anergized Vβ8⁺ T cells. We further show that Vβ8⁺ T cells activated in vitro from wild-type mice express a Fas-sensitive phenotype determined by Fas cross-linking which causes apoptosis. In contrast, Vβ8⁺ T cells anergized in vivo from wild-type mice are Fas resistant. As expected, T cells from lpr mice activated in vitro or anergized in vivo are Fas resistant. Taken together, these data indicate that both in wild-type and Fas-defective C3H/lpr mice, anergized T cells become deleted via a Fas-independent, proliferation-associated apoptosis signal pathway.     

转染反义Fas阻断T细胞凋亡及对肿瘤的治疗意义

目的 通过阻断Ｔ细胞的Ｆａｓ信号传递途径,探讨消除肿瘤对Ｔ细胞的攻击及其对肿瘤的治疗意义。方法 流式细胞术、ＲＴ－ＰＣＲ方法检测卵巢癌细胞表达Ｆａｓ和ＦａｓＬ。构建ｐｃＤＮＡ３－反义Ｆａｓ真核表达载体,经脂质体转染Ｊｕｒｋａｔ细胞,流式细胞仪检测Ｆａｓ表达变化。以Ａｎｎｅｘｉｎ－Ｖ和ＭＴＴ法检测转染反义Ｆａｓ基因对Ｊｕｒｋａｔ细胞凋亡的影响。采用ＭＴＴ体外杀伤实验观察３ＡＯ对Ｊｕｒｋａｔ细胞杀伤变化。结果 ６种卵巢癌细胞均表达Ｆａｓ和ＦａｓＬ。ｐｃＤＮＡ３－反义Ｆａｓ基因可以使Ｊｕｒｋａｔ细胞表达Ｆａｓ量下降并部分阻断Ｆａｓ单抗诱导的Ｊｕｒｋａｔ细胞凋亡,３ＡＯ对其杀伤减弱。结论 卵巢癌细胞表达ＦａｓＬ可能是其逃逸免疫监视并产生对淋巴细胞攻击的原因之一;应用反义技术阻断Ｆａｓ表达,可部分阻断Ｆａｓ单抗诱导Ｊｕｒ     

The renal cell carcinoma lysis by a specific cytotoxic T cell clone is independent of the Fas/Fas-L cytotoxic pathway

The expression of Fas antigen at the surface of renal cell carcinoma and the susceptibility to Fas-mediated lysis by a tumor specific CTL clone were investigated. Renal cell carcinoma cell lines expressed Fas antigen and were susceptible to apoptosis mediated by antibodies to Fas/APO1. Using RT-PCR, we further showed that these cell lines expressed mRNA for Fas deleted transmembrane region, corresponding to a soluble form of Fas/APO-1. To investigate the role of the Fas/FasL pathway in the cytotoxic response against RCC cells, we analyzed the induction of Fas-L on a tumor specific T cell clone (CTL 8C2), previously generated against one RCC cell line. Fas-L expression on CTL 8C2 was detected by RT-PCR after stimulation with autologous tumor cells. However, the cytotoxic activity of CTL 8C2 was completely abolished when EGTA was added, suggesting that the cytolysis was mainly mediated by a Ca++-dependent pathway, perforin/granzyme-based.