Fas与FasL的分子及细胞生物学研究进展

Ｆａｓ是Ｉ型膜蛋白,属ＴＮＦ受体家庭成员,许多细胞表达Ｆａｓ。而Ｆａｓ配体（ＦａｓＬ）只在激活Ｔ淋巴细胞表达,是Ⅱ型膜蛋白,属ＴＮＦ家庭成员,当ＦａｓＬ与Ｆａｓ结合时,Ｆａｓ可向细胞传递“死亡信号”,细胞在数小时内凋亡,Ｆａｓ－ＦａｓＬ介导的细胞凋亡在免疫调失及免疫病理中,可能有重要作用。     

Fas/FasL与系统性红斑狼疮的关系

Ｆａｓ系统参与淋巴细胞凋亡及自身免疫耐受维持 ,所以 ,Ｆａｓ和ＦａｓＬ基因改变引起的相应蛋白质分子变化所导致的功能丧失 ,可能与自身免疫病的发生密切相关。Ｆａｓ基因和ＦａｓＬ基因的功能缺失会引起小鼠产生淋巴增生 (ｌｙｍｐｈｏｐｒｏｌｉｆｅｒａｔｉｏｎ ,ｌｐｒ)和广泛性淋巴增生病 (ｇｅｎｅｒａｌｉｚｅｄｌｙｍｐｈｏｐｒｏｌｉｆ ｅｒａｔｉｏｎｄｉｓｅａｓｅ ,ｇｌｄ)两种类似人类系统性红斑狼疮 (ＳＬＥ)的自身免疫病[1] 。这两种小鼠出现淋巴结病和脾肿大 ,产生大量的ＩｇＧ和ＩｇＭ型自身抗体 ,包括抗ＤＮＡ抗体和类…     

Fas－Fas L诱导的细胞凋谢与免疫赦免

Ｆａｓ－Ｆａｓ　Ｌ诱导的细胞凋谢与免疫赦免李贵新,张玲（山东省医学科学院基础医学研究所,济南２５００６２）关键词Ｆａｓ抗原,Ｆａｓ配体,细胞凋谢,免疫赦免,器官移植免疫赦免区被认识已有１２０余年,它指机体内易于接受同种或／和异种组织器官的移植而不发生...     

人体胸腺和周围淋巴器官内T细胞亚群和NK细胞分布的研究

本文用多种Ｔ细胞和ＮＫ细胞单抗和免疫组织化学的ＡＢＣ技术,在冰冻切片上对人扁桃体、淋巴结、牌和胸腺内Ｔ细胞亚群和ＮＫ细胞的分布进行了检测。结果显示,ＣＤ５、ＣＤ８、ＣＤ４、ＣＤ３和ＡＩＧ３阳性细胞主要分布在扁桃体,淋巴结的副皮质区、脾的动脉周围淋巴鞘和胸腺,但各种抗体的反应强度不同。从各种Ｔ细胞工群的染色强度和形状看,胸腺髓质部的胸腺细胞相当于周围淋巴器官内的胸腺依赖区。胸腺内Ｔ细胞在分化过程中,质膜上的抗原也有相应变化。ＮＫ细胞主要分布在淋巴小结的生发中心,淋巴结和扁桃体的副皮质区,脾的红髓以及胸腺的筋质部。这些不同的分布,说明ＮＫ细胞不仅与淋巴小结的活动有关,可能还参与机体的免疫调节功能。     

突触体素、S-100蛋白、NSE免疫反应神经纤维在人淋巴结的分布

探讨突触体素、S－100蛋白、NSE免疫反应神经纤维在人淋巴结的分布,为淋巴结的神经免疫相互作用提供形态学资料。应用免疫组织化学ABC法观察人类腹股沟、腋窝、肠系膜、肺等淋巴结40例,10％福尔马林固定,石蜡包埋组织切片。结果显示：突触体素、S－100蛋白、NSE免疫反应神经纤维呈细丝状沿被膜和门部结缔组织小梁及血管进入皮质后主要分布于副皮质区,环境淋巴小结,进一步分支到达髓质。同时在淋巴小结发生中心及副皮质区有S－100蛋白免疫反应阳性细胞。在髓质髓窦内有NSE免疫反应阳性细胞。结论;淋巴结内有突触体素、S－100蛋白、NSE免疫反应神经纤维的支配、并有S－100蛋白、NSE免疫反应阳性细胞,为淋巴结的神经免疫相互作用提供形态学资料。     

FasL—Fas／APO—1（CD95）系统

Ｆａｓ配体（ＦａｓＬ）与Ｆａｓ受体（Ｆａｓ,即ＡＰＯ－１,又称ＣＤ９５）分别属于肿瘤坏死因子（ＴＮＦ）及ＴＮＦ受体（ＴＮＦＲ）家族,以膜分子或可溶性分子形式存在于哺乳类机体内。ＦａｓＬ或Ｆａｓ单克隆抗体（ＦａｓｍＡｂ）与Ｆａｓ结合可引起Ｆａｓ了性反应细胞的功能增强,继而出现程序性细胞死亡（ＰＣＤ）。ＦａｓＬ与Ｆａｓ相互作用及其所介导的信息途径是目前ＰＣＤ研究的重要内容之一。     

成年贵州小型猪淋巴结组织形态学观察及免疫组化研究

目的对成年贵州小型猪淋巴结进行形态学观察及免疫组化研究,为其用于建立人类免疫相关疾病模型提供参考。方法分别取24只成年贵州小型猪淋巴结组织进行固定、切片、HE染色,光镜下观察组织形态,免疫组化SP法检测CD3、CD4、CD8及CD20阳性细胞的比例和分布。结果成年贵州小型猪淋巴结皮质、髓质分布不规则,皮质、髓质并非完全倒置。皮质由淋巴小结和弥散性淋巴组织构成,髓质内可见髓索和髓窦。CD3、CD4、CD8阳性细胞主要分布在副皮质区,CD20阳性细胞主要分布在淋巴小结和髓质内。结论成年贵州小型猪淋巴结组织结构与其他哺乳动物有所不同,淋巴结内可见皮质、髓质倒置分布,但并非完全倒置。淋巴结中T、B细胞分布与人和其它哺乳动物之间没有明显的差异。     

人FasL的研究进展

ＦａｓＬ（Ｆａｓ ｌｉｇａｎｄ）为Ⅱ型跨膜糖蛋白,属于肿瘤坏死因子（ｔｕｍｏｒ ｎｅｃｒｏｓｉｓ ｆａｃｔｏｒ,ＴＮＦ）家族成员,与其它成员包括ＴＮＦα、ＴＮＦβ、ＣＤ４０Ｌ、ＣＤ３７Ｌ、ＣＤ３０Ｌ等在结构上有一定的同源笥,但与这些成员（除ＴＮＦ外）诱导细胞分化,增殖的作用不同,ＦａｓＬ的主要生物学活性是诱导Ｆａｓ＾＋细胞的凋亡,因而在淋巴细胞的克隆选择,免疫耐受的形成以及一些疾病的发生过程中都有     

c—Myc介绍导的细胞凋亡途径

细胞凋亡是细胞生物学行为中一复杂的主要运程,受细胞内多种因子调控,本文阐述了ｃ－Ｍｙｃ在细胞凋亡中与其它癌基因,抑癌基因ｂｃｌ－２、ｐ５３等产物的相互作用,与蛋白酶类的关系以及与Ｆａｓ／ＦａｓＬ凋亡途径的偶联。     

抗体形成细胞发育的免疫组织化学研究

本文采用辣根过氧化物酶(HRP)作为抗原,与福氏佐剂一起对雄性豚鼠进行二次免疫,追踪腘淋巴结中抗体形成细胞的发育和分化。在二次免疫后的早期(2—3天),淋巴结的皮质区(特别是淋巴滤泡间区)和髓质区几乎同时出现阳性反应的细胞,主要是淡棕色的小淋巴细胞和中淋巴细胞。至6—9天,这二个区域的阳性细胞数明显增加达到高峰,主要是棕色和棕褐色的前浆细胞和浆细胞,皮质区与髓质区的阳性细胞在某些区域相连接。从12天起这二个区域的阳性细胞开始下降,在27—49天,淋巴结中只存在少数分散的阳性细胞,部分细胞萎缩变形成残留的浆细胞。在同一切片视野中除了看到棕褐色浆细胞和淡棕色小淋巴细胞外,还可以看到包括中淋巴细胞和前浆细胞等过渡型细胞。因此,我们认为浆细胞是分别在皮质区和髓质区由淋巴细胞发育而成。     

Fas/Fas Ligand�Cmediated Apoptosis in Different Cell Lineages and Functional Compartments of Human Lymph Nodes

We have optimized an immunohistochemical double-staining method combining immunohistochemical lymphocyte lineage marker detection and apoptosis detection with terminal deoxyribonucleotidyl transferase–mediated dUTP nick end labeling. The method was used to trace Fas-mediated apoptosis in human reactive lymph nodes according to cell lineage and anatomical location. In addition to Fas, we also studied the expression of Fas ligand (FasL), CD3, CD20, CD19, CD23, and CD68 of apoptotic cells. The presence of simultaneous Fas and FasL positivity indicated involvement of activation-induced death in the induction of paracortical apoptosis. FasL expression in the high endothelial venules might be an inductor of apoptosis of Fas-positive lymphoid cells. In addition to B-lymphocyte apoptosis in the germinal centers, there was often a high apoptosis rate of CD23-expressing follicular dendritic cells. In summary, our double-staining method provides valuable new information about the occurrence and mechanisms of apoptosis of different immune cell types in the lymph node compartments. Among other things, we present support for the importance of Fas/FasL–mediated apoptosis in lymph node homeostasis. (J Histochem Cytochem 58:131–140, 2010)     

Hyperoxia-induced apoptosis and Fas/FasL expression in lung epithelial cells

Alveolar epithelial apoptosis is an important feature of hyperoxia-induced lung injury in vivo and has been described in the early stages of bronchopulmonary dysplasia (chronic lung disease of preterm newborn). Molecular regulation of hyperoxia-induced alveolar epithelial cell death remains incompletely understood. In view of functional involvement of Fas/FasL system in physiological postcanalicular type II cell apoptosis, we speculated this system may also be a critical regulator of hyperoxia-induced apoptosis. The aim of this study was to investigate the effects of hyperoxia on apoptosis and apoptotic gene expression in alveolar epithelial cells. Apoptosis was studied by TUNEL, electron microscopy, DNA size analysis, and caspase assays. Fas/FasL expression was determined by Western blot analysis and RPA. We determined that in MLE-12 cells exposed to hyperoxia, caspase-mediated apoptosis was the first morphologically and biochemically recognizable mode of cell death, followed by necrosis of residual adherent cells. The apoptotic stage was associated with a threefold upregulation of Fas mRNA and protein expression and increased susceptibility to direct Fas receptor activation, concomitant with a threefold increase of FasL protein levels. Fas gene silencing by siRNAs significantly reduced hyperoxia-induced apoptosis. In murine fetal type II cells, hyperoxia similarly induced markedly increased Fas/FasL protein expression, confirming validity of results obtained in transformed MLE-12 cells. Our findings implicate the Fas/FasL system as an important regulator of hyperoxia-induced type II cell apoptosis. Elucidation of regulation of hyperoxia-induced lung apoptosis may lead to alternative therapeutic strategies for perinatal or adult pulmonary diseases characterized by dysregulated type II cell apoptosis.     

TNF-alpha and IFN-gamma regulate expression and function of the Fas system in the seminiferous epithelium

Sertoli cells have long been considered to be involved in the regulation of the immune response in the testis. More recently, the Fas system has been implicated in the maintenance of the immune privilege in the testis as well as in the regulation of germ cell apoptosis. However, the control of Fas and Fas ligand (FasL) expression in the testis remains unknown. In the present study, we demonstrate that cultured mouse Sertoli cells constitutively express a low level of membrane-bound Fas protein, but not a soluble form of Fas. Sertoli cells stimulated with TNF-alpha and IFN-gamma markedly increase the expression of both soluble and membrane-bound Fas in a dose-dependent manner. The up-regulated membrane-bound Fas protein is functionally active because it induces a significant level of Sertoli cell death in the presence of Neuro-2a FasL+ effector cells. Interestingly, the soluble form of Fas, which is induced by the same cytokines but has an antiapoptotic effect, is also functional. In fact, conditioned media from TNF-alpha-stimulated Sertoli cell cultures inhibit Neuro-2a FasL+-induced cell death. Taken together, our data suggest a possible regulatory role of TNF-alpha and IFN-gamma on Fas-mediated apoptosis in the testis through disruption of the balance between different forms of Fas.     

Upregulation of Fas ligand expression by human immunodeficiency virus in human macrophages mediates apoptosis of uninfected T lymphocytes.

Apoptosis has been proposed to mediate CD4+ T-cell depletion in human immunodeficiency virus (HIV)-infected individuals. Interaction of Fas ligand (FasL) with Fas (CD95) results in lymphocyte apoptosis, and increased susceptibility to Fas-mediated apoptosis has been demonstrated in lymphocytes from HIV-infected individuals. Cells undergoing apoptosis in lymph nodes from HIV-infected individuals do not harbor virus, and therefore a bystander effect has been postulated to mediate apoptosis of uninfected cells. These data raise the possibility that antigen-presenting cells are a source of FasL and that HIV infection of cells such as macrophages may induce or increase FasL expression. In this report, we demonstrate that HIV infection of monocytic cells not only increases the surface expression of Fas but also results in the de novo expression of FasL. Interference with the FasL-Fas interaction by anti-Fas blocking antibodies abrogates HIV-induced apoptosis of monocytic cells. Human monocyte-derived macrophages from healthy donors contain detectable FasL mRNA, which is further upregulated following HIV infection with monocytotropic strains. HIV-infected human macrophages result in the apoptotic death of Jurkat T cells and peripheral blood T lymphocytes. Interruption of the FasL-Fas interaction abrogates the HIV-infected macrophage-dependent death of T lymphocytes. These results provide evidence that human macrophages can provide a source of FasL, especially following HIV infection, and can thus participate in lymphocyte depletion in HIV-infected individuals.     

Interferon alpha augments activation-induced T cell death by upregulation of Fas (CD95/APO-1) and Fas ligand expression.

Interferon alpha (IFN-alpha) plays a prominent role in the therapy of a variety of diseases. The Fas/FasL system is crucial for the cytotoxic function and the peripheral elimination of activated T lymphocytes (ATC) by a mechanism referred to as activation-induced cell death (AICD). Recent studies suggest a link between IFN-alpha, the 2', 5'- oligoadenylate system and apoptosis. We therefore asked whether IFN-alpha is able to regulate the Fas/FasL pathway and thereby affects AICD. Peripheral blood mononuclear cells (PBMC), purified T cells and ATC of healthy volunteers were stimulated with various agents and the influence of IFN-alpha on Fas/FasL was assessed by mRNA and protein studies. The proportion of ATC undergoing AICD or anti-Fas-induced apoptosis was determined by FITC-annexin V staining and propidium iodide uptake. IFN-alpha upregulated mRNA expression of Fas and FasL in activated PBMC. Furthermore the concentration of the soluble form of FasL (sFasL) was increased in PBMC and T cells co-stimulated with IFN-alpha and various agents, whereas Fas surface expression was enhanced by IFN-alpha alone. IFN-alpha enhanced apoptosis induced by anti-Fas antibody and augmented AICD via the Fas/FasL pathway. IFN-alpha-regulated AICD may contribute to lymphopenia observed during IFN-alpha therapy. Our data further support that IFN-alpha is a multifunctional cytokine with profound effects on the immune cascades.     

Activation-induced cell death: the controversial role of Fas and Fas ligand in immune privilege and tumour counterattack

Activation-induced cell death (AICD) is the process by which cells undergo apoptosis in a controlled manner through the interaction of a death factor and its receptor. Programmed cell death can be induced by a number of physiological and pathological factors including Fas (CD95)-Fas ligand (FasL/CD95L) interaction, tumour necrosis factor (TNF), ceramide, and reactive oxygen species (ROS). Fas is a 48-kDa type I transmembrane protein that belongs to the TNF/nerve growth factor receptor superfamily. FasL is a 40-kDa type II transmembrane protein that belongs to the TNF superfamily. The interaction of Fas with FasL results in a series of signal transductions which initiate apoptosis. The induction of apoptosis in this manner is termed AICD. Activation-induced cell death and Fas-FasL interactions have been shown to play significant roles in immune system homeostasis. In this review the involvement of Fas and Fas ligand in cell death, with particular reference to the T cell, and the mechanism(s) by which they induce cell death is described. The role of AICD in immune system homeostasis and the controversy surrounding the role of FasL in immune privilege, inflammation, and so-called tumour counterattack is also discussed.     

Requirement of the Fas ligand-expressing luteal immune cells for regression of corpus luteum

Apoptosis in corpus luteum (CL) is induced by prolactin (PRL) in female rats. PRL-induced apoptosis in CL is mediated by the Fas/Fas ligand (FasL) system. The CL consists of steroidogenic and non-steroidogenic cells, including immunocytes. Fas mRNA was detected only in the luteal steroidogenic cells, and FasL mRNA was expressed only by the non-steroidogenic CD3-positive luteal immunocytes. Removing the luteal immune cells from the luteal cells inhibited PRL-induced luteal cell apoptosis effectively. Thus, FasL-expressing non-steroidogenic luteal immunocytes are required for PRL-induced luteal cell apoptosis and heterogeneous induction of apoptosis by Fas/FasL in CL.