Decreased perforin and granzyme B expression in senescent HIV-1-specific cytotoxic T lymphocytes

Cytotoxic T lymphocyte (CTL) senescence may be an important mechanism of immune failure in HIV-1 infection. We find that senescence of HIV-1-specific CTL clones causes loss of killing activity, preventable by transduction with telomerase. Furthermore, senescence is associated with reduced expression of the effector molecules granzyme and perforin, suggesting CTL "exhaustion" can result in hypofunction. These results agree with other studies showing that HIV-1-specific CTL exhibit abnormal phenotypes in vivo, and suggest the possibility that chronic turnover is an important mechanism of antiviral failure in HIV-1 infection.     

Human granzyme B is essential for DNA fragmentation of susceptible target cells

We have partially characterized the granules of the human NK cell line, YT-INDY, and assessed granule-mediated lysis and DNA fragmentation of assorted targets. Biochemical studies demonstrated significant quantities of granzyme B (asp-ase) and a heretofore undescribed chymase but no tryptase (i.e., granzyme A or 3) or distinct met-ase. YT-INDY expressed mRNA for granzyme B, perforin and CCPX. The existence of perforin was confirmed by immunoblot. The granules lysed both human and murine NK-sensitive and NK-resistant targets. YTindependent lytic pathway is associated with the granules. In addition, 4-(2-aminoethyl) benzenesulfonylfluoride hydrochloride (AEBSF), an inhibitor that selectively blocked the chymase and 3,4-dichloroisocoumarin (DCI), an inhibitor that inactivated both chymase and asp-ase activities, marginally affected lysis. By gel electrophoresis and ¹²⁵I-labeled deoxyuridine release assay, only murine cells (SP2/0 and YAC-1) underwent DNA fragmentation, and cleavage was completely inhibited by DCI, whereas EGTA, AEBSF and aurintricarboxylic acid (ATA) had no effect. The results, therefore, underscore the central role of granzyme B in granule-mediated DNA fragmentation, emphasize that the protease acts via an ATA-resistant endonuclease pathway and stress that nucleolysis does not invariably accompany granule-mediated cytolysis. Finally, ATA inhibited the asp-ase activity of isolated but not granule-associated granzyme B. ATA, therefore, is not a specific endonuclease inhibitor and results obtained with ATA should be viewed cautiously.     

Regulation of Fas(Apo-1/CD95)- and perforinmediated lytic pathways of primary cytotoxic T lymphocytes by the protooncogene bcl-2

Cytotoxic T cells (CTL) induce cell death of their target cells either by the surface interaction between Fas ligand and Fas or by the release of perforin and granzymes. Both lytic pathways induce apoptosis yet it is not known whether identical or distinct apoptotic pathways are activated. The protooncogene bcl-2 is known to protect various hematopoietic cells from apoptosis induced by diverse agents. Here we show that overexpression of the Bcl-2 protein in the murine mastocytoma line P815 or in concanavalin A-activated splenocytes suppresses apoptotic cell death induced by allospecific primary cytotoxic T lymphocytes (CTL) in which only the Fas lytic pathway was functional. Bcl-2 also reduced target cell killing induced by CTL whose lytic activity was dependent on the perforin/granzyme pathway only. These data provide evidence that, in the target cells studied here, both perforin/granzyme and Fas apoptotic pathways are modulated by Bcl-2 and suggest that these two pathways converge at a step prior to Bcl-2 inhibition.     

人外周血NK细胞在细胞因子刺激下扩增后穿孔素、颗粒酶B基因表达的变化

目的 探讨经过纯化及在多种细胞因子的作用下扩增后的NK细胞,其穿孔素(per-furin)、颗粒酶B(granzyme B)表达水平的改变与细胞杀伤率的关系.方法 应用竞争性定量RT-PCR方法 检测了8例供者纯化、扩增后NK细胞的穿孔素、颗粒酶B基因表达水平,同时检测其对K562细胞的杀伤率.结果 经纯化、扩增后的NK细胞,在多种细胞因子作用下穿孔素和颗粒酶B的基因表达水平明显提高,且.IL-2+IL-15组、IL-2+IL-12+IL-15组基因的表达量均显著高于其他组,NK细胞对K562的杀伤率结果 与基因表达水平一致.结论 应用细胞因子后可使NK细胞的穿孔素、颗粒酶B基因表达水平明显提高,同时提高了NK细胞的杀伤功能.     

Involvement of caspase-8, -9, and -3 in high glucose-induced apoptosis in PC12 cells

Hyperglycemia, which occurs under the diabetic condition, is widely recognized as the causal link between diabetes and its serious complications. Diabetic neuropathies, which are among the most frequent complications of diabetes, affect sensory, motor, and autonomic nerves. The exact molecular mechanisms of high glucose-induced toxicity on neuronal cells, is still unclear. We previously reported that high glucose can induce apoptosis in PC12 cells, as evidenced by DNA fragmentation and high Bax/Bcl-2 ratio. The present study examined the involvement of caspase-3, the executioner, and two initiators of apoptosis, caspase-8 and caspase-9, during high glucose-induced apoptosis in PC12 cells, a neuronal cell line. Cells were exposed to high glucose with or without z-VAD-fmk, a pan-caspase inhibitor. Cell viability was measured by MTT assay. Caspase activity was determined spectrophotometrically using enzyme specific substrates. To correlate and confirm the caspase activity with changes in protein expression, procaspase-8, -9, and -3 were evaluated by Western blot analysis. The DNA-fragmentation was determined by DNA ladder using gel electrophoresis. The PC12 cell viability on high glucose exposure was decreased compared to controls, which was reversed by z-VAD-fmk. The activities of caspase-8, -9, and -3 were significantly increased in treated cells compared to controls. Moreover, high glucose exposure induced a significant decrease in protein levels of procaspases, indicating conversion of pro-form into the mature caspases. Finally, DNA fragmentation (Ladder) was shown in treated cells by high glucose. Based on the current data, it could be concluded that high glucose-induced apoptosis in PC12 cells is mediated, in part, by activation of caspase-8, -9, and -3 dependent pathways.     

Resistance of cultured peripheral T cells towards activation-induced cell death involves a lack of recruitment of FLICE (MACH/caspase 8) to the CD95 death-inducing signaling complex

Phytohemagglutinin-activated peripheral CD95⁺ T cells (day 1 T cells) are resistant to CD95-mediated apoptosis. After prolonged interleukin-2 treatment, these T cells become CD95-mediated apoptosis-sensitive (day 6T cells). To elucidate the molecular mechanism of apoptosis resistance, day 1 and day 6 T cells were tested for formation of the CD95 death-inducing signaling complex (DISC). DISC-associated active Fas-associated DD protein (FADD)-like interleukin-1β-converting enzyme-like protease (FLICE) also referred to as MACH/caspase 8 was only found in apoptosis-sensitive day 6 T cells. Further analysis of mRNA and protein expression levels of apoptosis-signaling molecules FADD, receptor interacting protein, hematopoietic cell protein tyrosine phosphatase, Fas-associated phosphatase-1, FLICE, bcl-2, bcl-x_L, and, bax-α showed that only the expression level of bcl-x_L correlated with T cell resistance to CD95-mediated apoptosis (day 1 T cells: bcl-x^hi_L; day 6 T cells: bcl-x^lo_L). In T cells activated in vitro, up-regulation of bcl-x_L has previously been correlated with general apoptosis resistance. However, the experiments presented suggest that resistance to CD95-mediated apoptosis in T cells can also be regulated at the level of recruitment of FLICE to the DISC.     

Perforin-dependent cytotoxic mechanism in killing by CD8 positive T cells in ginbuna crucian carp, Carassius auratus langsdorfii

T cell-mediated cytotoxicity occurs via pathways based on perforin or Fas mechanisms. Perforin is a protein present in the cytoplasmic granules of CD8⁺ cytotoxic T lymphocytes and is secreted to form pores on target cell membranes. In fish, although the involvement of perforin in cytotoxicity have been suggested for several species, perforin-mediated cytotoxicity of CD8α⁺ lymphocyte in conjunction with expression of the perforin gene has not been reported. In order to investigate the killing mechanism of CD8α⁺ lymphocytes by perforin-mediated pathway in fish, we measured apoptosis of target cells triggered by CD8α⁺ lymphocytes, performed cytotoxic assays in the presence or absence of perforin inhibitor; concanamycin A and EGTA, and analysed the expression of perforin1, perforin2 and perforin3 isotypic genes in ginbuna crucian carp. In the present study, we found that CTLs attached with target cells. CTL should have direct contact with target cells to kill them. Approximately 50% of target cells were positive for annexin V after co-cultured with CD8α⁺ lymphocytes, indicating the induction of apoptotic cell death. Concanamycin A, which induces depolymerization of perforin resulting in lytic function, suppressed the cytotoxicity of CD8α⁺ cells in a dose-dependent manner. In addition, cytotoxicity mediated by CD8α⁺ lymphocytes were significantly suppressed by the addition of the Ca²⁺-chelating agents EGTA or EGTA-Mg²⁺, and the addition of Ca²⁺ restored the killing mechanism of target cells. We further found enhanced expression of perforin1 but not perforin2 or perforin3 in CTLs from allo-sensitized fish. The present study has demonstrated that ginbuna CTLs kill target cells through perforin-mediated pathway, suggesting that perforin-mediated pathway is conserved throughout vertebrate.     

Cleavage of caspase family members by granzyme B: a comparative study in vitro

The aspartase granzyme B is one of the major components of the granules involved in cell killing by cytotoxic T lymphocytes. Granzyme B has been shown to activate the apoptotic death pathway in the target cell, and this involves activation of members of the caspase (CASP) protein family. Therefore, activational cleavage of mouse (m) CASP proforms by granzyme B was examined in vitro. CASP can be subdivided in the CASP-1 (interleukin-1β-converting enzyme; ICE) subfamily, the CASP-2 (Ich1) subfamily, and the CASP-3 (CPP32) subfamily. Our results reveal that the proforms of the CASP-3 subfamily members mCASP-3 and mCASP-7 are hydrolyzed by granzyme B, while proforms of CASP-2 and CASP-1 subfamily members are not directly cleaved. Only one CASP-3 subfamily member, pro-mCASP-6, was not proteolytically cleaved by granzyme B. These results indicate that two members of the CASP-3 subfamily, but no others, become activated by granzyme B.     

颗粒酶B和穿孔素免疫组织化学检测诊断肝移植急性排斥反应的敏感性与特异性

目的　探讨颗粒酶B和穿孔素两种免疫活化分子在肝移植急性排斥诊断中的作用,及其与Banff急性排斥反应组织学诊断标准之间的对应关系。方法　在常规组织学诊断基础上,将41份肝穿刺标本用颗粒酶B与穿孔素单克隆抗体进行免疫组织化学EnVision二步法标记,IPP图像分析软件计算阳性细胞数/mm2 作为免疫活化细胞指数(AI),以组织学诊断作为评判有无急性排斥反应的标准。结果　在41份肝穿刺标本中,组织学诊断为急性排斥反应21份,缺乏急性排斥反应组织学改变20份。急性排斥反应组颗粒酶B与穿孔素AI值显著高于无排斥反应组(P<0. 001),中重度排斥反应组AI值显著高于轻度及其非确定性排斥反应组(P<0. 001)。与组织学诊断比较,颗粒酶B的敏感性、特异性、阳性预测值、阴性预测值及诊断一致率分别达到90. 0%、95. 2%、94. 7%、90. 9%以及92. 7%;穿孔素的各指标也分别达到80. 0%以上。结论　颗粒酶B与穿孔素是急性排斥反应免疫效应细胞活化标志,在临床肝移植急性排斥反应时表达明显升高,作为组织学诊断急性排斥反应的辅助指标具有相当高的敏感性及特异性,可用于肝移植后肝穿刺标本的鉴别诊断。     

不同亚群CD8＋T细胞细胞毒作用对慢性乙型肝炎的影响

目的观察慢性乙型肝炎不同分期及干扰素-a（interferon-a,IFN-a）治疗前后外周血不同亚群CD8＋T细胞细胞毒作用的变化,探讨其在慢性乙型肝炎发病机理及抗病毒治疗中的作用。方法采集20例慢乙肝免疫耐受期患者和20例免疫清除期患者IFN—a治疗前后的外周全血,采用流式细胞仪检测CD8^high和CD8^lowT细胞的颗粒酶B（Granzyme B,GrB）和溶酶体相关膜蛋白-1（Lysosome—associated membrane protein．1,LAMP-1,CD107a）表达变化,并进行分析。结果（1）慢乙肝患者免疫清除期不同亚群CD8＋T细胞GrB和CD107a的表达水平均高于免疫耐受期;（2）不同分期慢乙肝患者CD8^lowT细胞GrB和CD107a的表达水平均高于CD8^highT细胞;（3）IFN—a治疗后CD8^highT细胞的GrB和CD107a表达水平和治疗前相比具有升高趋势,而CD8^lowT细胞反而具有下降趋势;（4）不同亚群CD8＋T细胞的GrB和CD107a表达水平与HBV—DNA载量在免疫耐受期呈正相关,而在免疫清除期呈负相关。结论（1）不同亚群CD8＋T细胞的GrB和CD107a分子在慢乙肝疾病进程及抗病毒治疗中均起重要作用,CD8^lowT细胞的细胞毒作用强于CD8^highT细胞,而CD8^highT细胞的细胞毒效应在IFN—a治疗过程中逐渐增强。（2）不同亚群CD8＋T细胞的GrB和CD107a分子水平与HBV病毒载量的相关性在一定程度上可以提示机体免疫应答与病毒之间的关系。     

白藜芦醇诱导鼻咽癌细胞CNE-2Z凋亡过程中caspase-6的活化

目的:探讨白藜芦醇(Res)诱导鼻咽癌细胞CNE-2Z凋亡过程中是否有caspase-6的活化。方法:用Western-blot分析caspase-6酶原的裂解,半定量RT-PCR检测caspase-6mRNA表达的改变,比色法测定caspase-6活性的变化。结果:用Res 0(对照)、25、50、100、200μmol/L处理细胞24小时,caspase-6酶原的表达随药物浓度的增加而减少,100 μmol/L时开始出现活性裂解片段P20(20 kD),200μmol/L时P20增加;caspase-6 mRNA的表达呈浓度依赖性的增加(P<0.01);caspase-6活性呈浓度和时间依赖性的升高(P<0.01)。结论:Res诱导CNE-2Z细胞凋亡过程中有caspase-6的活化。     

Caspase-8信号分子对SLE患者T细胞亚群的双向调节作用研究

目的 分析SLE患者外周血T细胞内活化Caspase-8、Caspase-3和T细胞膜上Fas、CD69以及外周血中Foxp3 CD4 CD25 调节性T细胞的表达,探讨他们在SLE患者免疫失衡中的作用.方法 用流式细胞术检测活化Caspase-8、Caspase-3和Fas、CD69以及Foxp3 CD4 CD25 Treg的表达.结果 与健康对照相比,SLE患者外周血CD3 CD4 T细胞上Fas表达显著升高(P＜0.05),无论稳定期或活动期SLE患者CD3 CD4 T细胞和CD3 CD8 T细胞中活化Caspase-8的表达均显著增加(P＜0.05),且稳定期和活动期SLE患者CD3 CD8 T细胞中活化Caspase-8的表达高于其在CD3 CD4 T细胞中的表达(P＜0.05);但是仅活动期SLE患者T细胞内活化Caspase-3表达增加(P＜0.05),同时稳定期和活动期SLE患者CD3 CD4 T细胞中活化Caspase-3的表达高于其在CD3 CD8 T细胞中的表达(P＜0.05).同时SLE患者CD3 CD8 T细胞上CD69表达率升高(P＜0.05),但是CD69在CD3 CD4 T细胞上的表达率与健康对照相比无显著性差异(P＞0.05).SLE患者外周血中Foxp3 CD4 CD25 Treg比例显著低于健康对照(P＜0.05).结论 Caspase-8介导的信号事件同时参与诱导SLE患者淋巴细胞的凋亡与活化,促使SLE患者体内免疫反应向Th2极化,同时由于SLE患者外周血中Foxp3 CD4 CD25 Treg表达降低所介导的免疫抑制效应缺陷,他们共同作用促使SLE患者外周免疫平衡障碍.     

Differential expression of human granzymes A, B, and K in natural killer cells and during CD8+ T cell differentiation in peripheral blood

NK cells and cytotoxic T lymphocytes can induce apoptosis in virus-infected and transformed target cells via the granule exocytosis pathway. The key components of the cytolytic granules are perforin and several serine esterases, termed granzymes. While the cellular distribution of human granzymes A (GrA) and B (GrB) has been well characterized much less is known about the expression pattern of human granzyme K (GrK). In this study GrA, GrB, and GrK expression was analyzed in human peripheral blood lymphocytes using flow cytometry. There was a distinct population of GrK expressing CD8+ T cells with a CD27+/CD28+/CCR5high/CCR7-/perforin-/low/IFN-gamma+ memory-like phenotype, while all CD56bright NK cells were also positive for GrK. In addition, GrK was also expressed in subpopulations of CD56+ T cells, CD4+ T cells, and TCRgammadelta+ T cells. In contrast, GrB was primarily expressed in CD56dim NK cells and differentiated memory CD8+ T cells with the CD27-/low/CD28-/low/CCR5-/low/CCR7-/CD11b+/perforinhigh phenotype. Only few CD8+ T cells expressed both GrB and GrK. GrA was found to be co-expressed in all GrB- and GrK-expressing T cells. Our findings suggest that granzyme expression during the differentiation process of memory CD8+ T cells might be as follows: GrA+/GrB-/GrK+ --> GrA+/GrB+/GrK+ --> GrA+/GrB+/GrK-.     

Expression and function of HLA-B27 in lipid-linked form: Implications for cytotoxic T lymphocyte-induced apoptosis signal transduction

Major histocompatibility complex (MHC) class I antigen-restricted cytotoxic T lymphocytes (CTL) kill their target cells not only by inducing irreversible membrane damage but also by triggering a programmed suicide cascade (apoptosis) in target cells. Recent evidence suggests that MHC class I antigens are involved in apoptosis signal transduction in T cells. Therefore, it is possible that MHC class I antigens are also responsible for CTL-induced signal transduction in target cells leading to apoptosis. To test this hypothesis, we have expressed HLA-B27 in Chinese hamster ovary (CHO) cells in a phosphatidyl inositol (PI) anchored form. The expressed Pl-anchored HLA-B27 (PI-B27), a 42-kDa molecule which can be cleaved off the cell surface by Pi-specific phospholipase C, can function as an MHC restriction and antigen presentation element for specific CTL. Furthermore, PI-B27 transfectant CHO cells undergo rapid DNA fragmentation when pulsed with the appropriate peptide and treated with specific CTL, suggesting that the cytoplasmic and transmembrane domains of the heavy chain of class I MHC molecules are not required in CTL-induced apoptosis signal transduction in target cells.     

小脑颗粒神经元细胞凋亡中caspase-8基因变化与二乙酰吗啡的影响

背景：半胱-天冬氨酸蛋白酶8(Caspase-8)是细胞凋亡过程起始的重要因子,二乙酰吗啡可致神经元细胞凋亡,其与二乙酰吗啡致小脑颗粒神经元细胞凋亡之间关系尚未见报道。 目的：验证二乙酰吗啡诱导小脑颗粒神经元细胞凋亡与caspase-8基因表达情况,明确caspase-8参与二乙酰吗啡致神经元凋亡过程。 方法：取出生7 d SD大鼠小脑颗粒神经元细胞进行体外培养,第7天后,以不同质量浓度的二乙酰吗啡(10,40,80,100,120 mg/L)和C-jun氨基末端激酶通路特异性抑制剂SP600125作用小脑颗粒神经元细胞24 h,并分对照组(0 mg/L二乙酰吗啡),80 mg/L二乙酰吗啡组,二乙酰吗啡+SP 600125组;采用Hoechst 33258 荧光染色观察细胞形态学改变,流式细胞仪测细胞凋亡率,免疫荧光、RT-PCR及Western Blotting检测caspase-8 mRNA和蛋白表达情况。 结果与结论：①施加不同质量浓度二乙酰吗啡致神经元细胞凋亡,凋亡细胞出现透亮深蓝色的凋亡小体,细胞核呈现固缩、凝聚及断裂,随给药浓度增加细胞凋亡率呈现升高趋势(P < 0.05)。②与对照组相比,在80 mg/L二乙酰吗啡干预时caspase-8 mRNA和蛋白表达明显明显表达(P < 0.05);caspase-8 mRNA随给药浓度增加呈现升高趋势(P < 0.05),二乙酰吗啡+SP600125组中caspase-8 mRNA和蛋白较80 mg/L二乙酰吗啡组明显下调(P < 0.05)。结果提示caspase-8参与二乙酰吗啡致小脑颗粒神经元细胞凋亡过程,同时也是C-jun氨基末端激酶信号通路中的重要候选促凋亡因子。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

A promoter element of the human serine esterase granzyme B gene controls specific transcription in activated T cells

The human granzyme B gene encodes a serine protease expressed specifically in cytoplasmic granules of cytotoxic T lymphocytes, released upon effector-target cell interaction. Previous studies have shown that granzyme B mRNA was induced in T lymphocytes after antigenic or mitogenic stimulation. To study the regulation of human granzyme B gene expression during lymphocyte activation we analyzed its 5′ flanking region using chloramphenicol acetyl transferase (CAT) reporter gene constructs. We show that a 208-bp fragment (-148 to +60) containing an NF-AT (nuclear factor of activated T cells)-binding site promotes CAT expression in phytohemagglutinin-activated T lymphocytes, in immobilized monoclonal anti-CD3 antibody-activated Jurkat T cell line while it is inactive in unstimulated PEER and Jurkat T cells lines or B Epstein-Barr virus-transformed cell lines.     

Contribution of TIA-1+ and granzyme B+ cytotoxic T lymphocytes to cryptal apoptosis and ulceration in active inflammatory bowel disease

In spite of the clinicopathological differences between Crohn's disease (CD) and ulcerative colitis (UC), they share the fundamental feature of destructive inflammatory processes involving the intestinal wall. The aim of the present study was to investigate the contribution of cell-mediated cytotoxicity to mucosal damage in CD and UC. Colonic mucosal biopsy specimens from patients with active CD (n=25) and UC (n=26) and normal controls (n=12) were immunohistochemically analyzed for the expression of CD3, CD4, CD8, and T cell-restricted intracellular antigen (TIA)-1, which promotes apoptosis by alternative splicing of pre-messenger RNA of the Fas receptor, and granzyme B (GrB), which leads to apoptosis through induction of perforin. Histological scores for cryptal apoptosis and ulceration were assessed in hematoxylin- and eosin-stained sections. In patients with CD and UC, CD3+(P<0.001), CD4+(P<0.001), CD8+(P<0.01), TIA-1+(CD, P<0.01; UC, P<0.001), and GrB+(CD, P<0.01; UC, P<0.001) intraepithelial lymphocytes (IELs) were significantly increased as compared with controls. Positive relationships were found between the histological scores for apoptosis or ulceration and the numbers of CD8+or TIA-1+IELs. In conclusion, cytotoxic T lymphocytes are present in increased numbers in the mucosa of patients with active CD and UC, and local activation of IELs may contribute to mucosal damage with these diseases.     

Co-expression of perforin and granzyme B genes induces apoptosis and inhibits the tumorigenicity of laryngeal cancer cell line Hep-2

Granzyme B and perforin, two of the most important components, have shown anticancer properties in various cancers, but their effects in laryngeal cancer remain unexplored. Here we decided to examine the effects of Granzyme B and perforin in Hep-2 cells and clarify the role of perforin and granzyme B in the tumorigenicity of laryngeal cancer cell line. Hep-2 cells were transfected with pVAX1-PIG co-expression vector (comprising perforin and granzyme B genes), and then the growth and apoptosis of these Hep-2 cells were evaluated. The tumorigenicity of Hep-2 cell line co-expressing perforin and granzyme B genes was tested in BALB/c nu/nu mice. We found that the co-expression of perforin and granzyme B genes could obviously inhibit cell focus formation and induce cell apoptosis in Hep-2 cells. Furthermore, after subcutaneous injection of Hep-2 cells transfected with pVAX1-PIG, an extensive delay in tumor growth was observed in BALB/c-nu/nu mice. Moreover, our studies demonstrated that the anticancer activity of perforin and granzyme B was sustainable in vivo as tumor development by inducing cell apoptosis. Taken together, our data indicate that the co-expression of perforin and granzyme B genes exhibits anticancer potential, and hopefully provide potential therapeutic applications in laryngeal cancer.