Participation of the Fas and Fas ligand systems in apoptosis during atrophy of the rat submandibular glands

Most acinar cells and some duct cells undergo apoptosis during atrophy of the submandibular gland. The present study was designed to elucidate whether Fas and its receptor ligand (FasL) are involved during apoptotic atrophy of the gland. The excretory duct of the right submandibular gland of rats was doubly ligated with metal clips from 1 to 14 days for induction of gland atrophy. Control rats were untreated. Fas and FasL expression in the atrophied submandibular gland was detected using immunohistochemistry (IHC) and Western immunoblot. Expression of activated caspase 8 and activated caspase 3 was also detected with IHC. Fas-positive acinar and duct cells and FasL-positive duct cells increased in the atrophic glands at 3 and 5 days after duct ligation when apoptotic cells were commonly observed. Thereafter, Fas- and FasL-positive cells declined in number. Patterns of expression of Fas and FasL using Western immunoblots concurred with the IHC results. Activated caspase 8-positive cells were present at every time interval but peaked at 3 and 5 days following duct ligation. The cells showing immunoreaction for activated caspase 3 first appeared on day 3, with the peak in apoptosis, after which they decreased. The results indicate that the Fas/FasL systems likely play an important role in apoptotic pathways during atrophy of the submandibular gland.     

Fas和Fas配体在角膜移植免疫排斥反应中的表达

目的 了解Fas和Fas配体(FasL)在发生免疫排斥的角膜植片中的表达情况，探讨其在角膜移植免疫排斥反应中的作用。方法 角膜移植术后排斥反应的患者42例，于再次行穿通性角膜移植术时取其排斥的移植片；正常角膜6例。进行免疫组织化学染色，观察正常角膜和移植片中上皮、基质和内皮层的Fas及：Fas配体的表达。结果 在6例正常角膜中，角膜上皮、内皮Fas和FasL．为阳性表达。42例移植片中，角膜上皮．Fas和FasL均有表达。有新生血管形成及免疫细胞浸润的角膜基质中，血管内皮细胞、基质细胞FasL为阳性表达，Fas在部分浸润的免疫细胞中有表达；移植片内皮细胞层广泛破坏。结论 Fas、FasL在角膜移植片中的表达，可能与角膜移植免疫排斥反应有关。     

Study of Fas (CD95) and FasL (CD178) polymorphisms in liver transplant recipients

The Fas receptor is capable of transducing apoptotic cell death upon interaction with their ligand (FasL). Recent studies suggest that the Fas/FasL system is involved both in graft rejection and in transplantation tolerance. In this study, we analyzed the effect of Fas and FasL polymorphisms in liver allograft outcome. Fas and FasL polymorphisms were analyzed in 151 primary liver graft recipients. The Fas (-670 A/G) and the FasL (IVS2nt -124 A/G and IVS3nt 169 T/delT) polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Fas -1377 G/A polymorphism was determined by allele-specific amplification. Fas and FasL polymorphisms were not associated with acute and chronic rejection in liver transplant. In contrast, those recipients bearing the AA -670 Fas genotype showed significantly lower graft survival rate (S = 40%) than those bearing the GA genotype (S = 63.1%). These differences were detected from the first year post-transplant. Multivariate analysis confirmed that the AA genotype increased the risk of liver graft loss. This work suggests for the first time a possible harmful effect of Fas -670 AA genotype on liver graft survival, whereas the Fas and FasL polymorphisms are not associated with acute or chronic rejection in liver graft recipients.     

肾移植受者血清sFas和sFasL变化及在早期急性排异反应预测中的应用

背景：细胞凋亡在移植免疫和移植物功能丧失发生过程中起十分重要的作用,其中Fas/FasL系统被认为是细胞凋亡参与肾移植的急性排异反应过程的主要途径之一。 目的：分析肾移植受者术后血清sFas和sFasL水平变化及其在预测早期急性排异反应中的应用价值。 方法：肾移植受者80例分为肾功能稳定组(49例)、急性排斥反应组(23例)和环孢素A中毒组(8例)。另选择性别、年龄与肾移植受者相匹配的健康体检者50例为对照组。肾移植受者术后均常规使用环孢素A+硫唑嘌呤+泼尼松三联免疫抑制治疗。发生急性排斥反应时给予每日甲基强的松龙6~8 mg/kg冲击治疗,3 d为1个疗程。采用ELISA法检测患者手术前后的血清sFas和sFasL水平。 结果与结论：肾移植组患者手术前的血清sFas和sFasL水平均明显高于对照组(P  < 0.05)。急性排斥反应组血清sFas、sFasL水平高于相同时间段肾功能稳定组(P < 0.05)。环孢素A中毒的肾移植患者术后各时间点血清sFas、sFasL水平变化与肾功能稳定组基本相同,差异无显著性意义。提示动态监测血清sFas、sFasL水平可能对早期诊断及鉴别诊断肾移植急性排斥反应具有重要参考价值。     

乙型肝炎肝组织Fas，FasL和HBV抗原的表达

目的 评价Fas和FasL介导细胞凋亡在乙型肝炎肝损伤中的作用及其与HBV抗原的关系。方法 应用免疫组化方法检测了62例乙型肝炎患者肝组织内的Fas、FasL和HBsAg、HBcAg,并以6例下正常肝组织为对照。结果 Fas/FasL在正常肝组织内无表达;Fas主要在乙型肝炎患者肝细胞质内表达,58例阳性（93．5％）;FasL在肝内浸润的单个核细胞和肝细胞质内均见到,37例阳性（59．7％）。结论 Fas/FasL的表达程度与肝组织活动性炎症程度密切相关;Fas/FasL介导的细胞凋亡可能在乙型肝炎时肝损伤中起重要作用;Fas/FasL表达程度与肝内HBV抗原HBsAg、HBcAg无明显相关性。     

The role of Fas ligand as an effector molecule in corneal graft rejection

Previous studies have shown that the expression of Fas ligand (FasL; CD95L) by donor corneas is critical to their survival when placed on allogeneic recipients. Since there have been reports that the cornea expresses Fas, we tested the idea that FasL on lymphoid cells could be an effector molecule during rejection episodes. When FasL defective BALB/c-gld mice were engrafted with allogeneic corneas, significantly more of these corneas were accepted than by normal BALB/c mice. However, this was not due to impaired FasL-mediated effector function in these mice as the allogeneic corneas did not express detectable Fas by Western blot or RT-PCR analysis. Furthermore, donor corneas without Fas were given no survival advantage, but were rejected similar to wild-type donor allogeneic corneas. Examination of the T cell compartment in gld mice revealed that these cells express higher levels of Fas and are more susceptible to Fas-mediated death than wild-type cells. These results indicate that FasL is not an effector molecule in corneal graft rejection and that gld mice show reduced graft rejection due to greater susceptibility of their T cells to Fas-mediated apoptosis.     

脊髓全横断损伤后凋亡因子Fas和FasL的表达变化

本研究通过制备SD大鼠脊髓全横断性损伤模型,应用免疫组织化学ABC法和灰度值测定揭示促凋亡因子Fas和FasL在脊髓完全性损伤后,不同时间点之间的相互变化趋势,以探讨Fas和FasL在脊髓损伤中的作用。结果显示:正常和脊髓全横断损伤后的不同时间组SD大鼠脊髓灰质的前角神经元中均可观察到Fas和FasL的免疫阳性产物。与正常组比较,Fas、FasL阳性神经元细胞数在术后1、3、7、14d组均升高(P<0.05),21d组则降低(P<0.05)。前角Fas、FasL阳性神经元的灰度值在术后1、3、7d组较正常组降低(P<0.05),14、21d组无显著性差异(P>0.05)。结果提示大鼠脊髓全横断损伤后,在损伤节段尾侧脊髓前角神经元Fas与FasL的表达经历了由增高到降低的过程,Fas和FasL表达增加有诱导神经细胞凋亡的趋势,可能参与诱导了脊髓继发性损伤。     

Fas/FasL介导的caspase-3活化与急性胰腺炎腺泡细胞凋亡的关系

目的： 研究凋亡调控基因及蛋白Fas、FasL和caspase-3在大鼠急性胰腺炎（AP）组织中的表达及其相互关系。方法：经胰胆管逆行注射不同浓度的牛磺胆酸钠建立不同炎症程度的AP模型,采用RT-PCR、Western blotting技术检测大鼠胰腺炎组织Fas、FasL和caspase-3蛋白及mRNA的表达, TUNEL法检测胰腺炎组织腺泡细胞凋亡。结果：在正常胰腺组织内即可见Fas、FasL、caspase-3蛋白和mRNA的表达;建立AP模型后,随胰腺炎症程度的加重,Fas、FasL、caspase-3蛋白和mRNA的表达逐渐下降,腺泡细胞凋亡率亦逐渐下降,且caspase-3 表达水平在各个组间的变化趋势与Fas/FasL系统的变化趋势相一致。结论：Fas/FasL系统介导的凋亡途径参与了急性胰腺炎腺泡细胞凋亡的调节。     

癫痫大鼠海马神经元Fas、FasL和Caspase-3的表达

目的观察Fas、FasL和Caspase-3在癫痫大鼠海马神经元中的表达,探讨Fas、FasL和Caspase-3表达与癫痫的关系,为癫痫的生物治疗提供实验依据。方法通过腹腔注射戊四氮建立癫痫大鼠模型,用免疫组织化学方法和图像分析技术检测Fas、FasL和Caspase-3在癫痫大鼠海马神经元中的表达。结果 Fas、FasL和Caspase-3在癫痫大鼠海马神经元中的表达水平和阳性细胞数量与正常对照组相比均明显增多(<0.05)。结论 Fas、FasL和Caspase-3在癫痫大鼠海马过表达。     

Significance of Fas and Fas ligand in tuberculous lymphadenitis

The Fas/Fas-ligand (FasL) system plays an important role in regulation of apoptosis and the immune response, and is exploited by mycobacteria to evade the immune response. This study was performed to investigate the distribution and levels of FasL and Fas in lymph node granulomas and sera of tuberculous lymphadenitis patients by immunohistochemistry and enzyme-linked immunosorbent assay. The validity of soluble Fas (sFas) or soluble FasL (sFasL) as a diagnostic tool was also examined. Levels of sFasL in serum were elevated among patients. The numbers of FasL stained cells in lymph node granulomas were higher than Fas. Children had significantly higher levels of sFasL as compared to adults. The human immunodeficiency virus (HIV)-tuberculosis (TB)-coinfected patients displayed no differences in the levels of sFasL or sFas compared with HIV-negative patients. The healthy controls from a high endemic tuberculosis country (having latent TB) had significantly higher levels of sFasL than from a country with no TB transmission. The sensitivity and specificity of the FasL and Fas test were low when compared with the culture results as the gold standard. However, by using histology as the gold standard, the sensitivity and specificity of the FasL test were increased to 66.7% and 100%, respectively, but for the Fas test remained low. In conclusion, sFasL and sFas cannot be used as diagnostic tests for tuberculous lymphadenitis. However, its utility in detecting latent TB and childhood tuberculous lymphadenitis remains to be evaluated. FasL seems to play a role in immune modulation and pathogenesis of TB. Modulators of Fas/FasL-mediated apoptosis may therefore be clinically useful.     

Serum levels of soluble Fas ligand in patients with silicosis

Certain patients with silicosis have been reported to exhibit immunological abnormalities such as the appearance of antinuclear antibodies and the occurrence of autoimmune diseases. Fas ligand (FasL) is a type II membrane protein which induces apoptosis by binding to its membrane receptor, Fas. FasL is converted to a soluble form by a metalloproteinase-like enzyme. We have already found serum soluble Fas (sFas) levels in silicosis patients as well as in patients with systemic lupus erythematosus (SLE) to be significantly higher than those in healthy volunteers. To examine further the role of the Fas/FasL system in silica-induced immunological abnormalities, we investigated serum soluble FasL (sFasL) levels in silicosis patients with no clinical symptoms of autoimmune diseases, using ELISA for sFasL. Although the serum sFasL levels in patients with SLE were significantly higher than those in healthy volunteers and showed a slight positive correlation with serum sFas levels, those in silicosis patients exhibited no significant difference from those in healthy volunteers, and there was no correlation with serum sFas levels. However, sFasL levels were elevated in silicosis patients with slight dyspnoea or normal PCO2 among various clinical parameters of silicosis. It may be speculated that the immunological disturbances presented by the abnormalities of apoptosis-related molecules in silicosis patients do not occur with a similar degree of respiratory involvement. Further studies are required to clarify which kinds of factors are involved in silicosis patients who exhibit immunological abnormalities.     

支气管哮喘大鼠淋巴液中淋巴细胞线粒体跨膜电位以及Fas/FasL变化

目的探讨哮喘大鼠淋巴液中淋巴细胞跨膜电位（mitochondrial membrane potential,△.ψm）和淋巴细胞表面Fas、FasL表达水平,并与其血液、支气管肺泡灌洗液（bronchoalveolar lavage fluid,BALF）水平比较。方法流式细胞仪、免疫组化方法检测对照组和哮喘组激发后2、6、12、24、48h各时间点淋巴液、血液、BALF中淋巴细胞线粒体的跨膜电位、淋巴细胞表面Fas、FasL蛋白表达。结果哮喘组淋巴液、血液和BALF中淋巴细胞△.ψm峰值在各时间点均较对照组明显升高（P〈0.01）,Fas、FasL蛋白表达水平低于对照组水平（P〈0.01）;哮喘组淋巴液中淋巴细胞△.ψm在不同时间点均较血液水平明显升高（P〈0.05）,血液中淋巴细胞△.ψm与BALF水平间无显著性差异（P〉0.05）。结论哮喘大鼠淋巴液、血液、BALF中均存在明显的淋巴细胞早期凋亡障碍和Fas/FasL表达降低,尤其是哮喘淋巴液中淋巴细胞凋亡障碍和Fas/FasL降低程度较其血液、BALF更为明显。     

The role of the Fas/Fas ligand system in estrogen-induced thymic alteration

PROBLEM: Estrogen induces atrophy in the thymus by an unknown mechanism. Since the Fas/FasL system is one of the main pathways in T cell apoptosis, we tested the hypothesis that estrogen-induced thymic atrophy is mediated by the Fas/FasL system. METHODS OF STUDY: In vivo experiments were done using ovariectomized female rats treated with estrogen or saline. In vitro experiments were performed using isolated thymocytes. Estrogen receptor (ER) alpha and beta expression was characterized using flow cytometry, RT-PCR and immunofluorescence. Fas and FasL mRNA and protein expression was evaluated using RT-PCR and Western blot analysis respectively. RESULTS: ERalpha and ERbeta are present in thymocytes and stromal cells. ER expression is mainly localized in the Double Positive CD4+CD8+ thymocytes. Estrogen treatment decreases thymus size and increase FasL expression. CONCLUSION: CD4+CD8+ thymocytes and thymic stroma cells express ERalpha and ERbeta. In vivo and in vitro we showed that estrogen treatment increases FasL expression while decreasing thymus cell number. These findings support the hypothesis that estrogen-induced thymic atrophy occurs as a result of apoptosis and is mediated by estrogen-induced FasL expression.     

Contribution of Fas ligand to cardiac allograft rejection

Effector mechanisms for allograft injury remain unclear. Inthe present study, we verified the contribution of Fas and Fasligand (FasL) to cardiac allograft rejection by utilizing theFas-deficlent lpr or FasL-deficient gid mice as the donor orrecipient. Cardiac myocytes prepared from normal mice, but notthose from lpr mice, constitutively expressed Fas and were susceptibleto FasL-mediated lysis. Survival of cardiac allografts was substantiallyprolonged when gld or lpr mice were used as the recipient. Incontrast, cardiac allografts from ipr mice were normally rejectedwithout a delay. Histological examination of the grafts in thegld or lpr recipients demonstrated a lesser cellular infiltrationand much milder myocyte damage. Proliferative response and cytotoxicT lymphocyte induction against the donor-type alloantigens werenot impaired in the gld or lpr recipients. These results indicatea substaintial contribution of FasL to cardiac allograft rejection,independent of Fas in the grafts. This raises a possibilitythat FasL may be more generally involved in tissue damage associatedwith various diseases than expected from the expression of Fasin the target organs.     

Soluble apoptosis molecules in primary biliary cirrhosis: analysis and commitment of the Fas and tumour necrosis factor-related apoptosis-inducing ligand systems in comparison with chronic hepatitis C

Apoptosis in the liver is generated mainly by the Fas system. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has been proposed recently as a new apoptotic inducer. In the liver environment hepatocytes and biliary epithelial cells express TRAIL receptors which are up-regulated by increased levels of bile acids and during viral hepatitis. As for FasL, a soluble form of TRAIL has been described. To explore the commitment and level of activation of these two apoptotic systems in patients affected by primary biliary cirrhosis (PBC) or chronic hepatitis C (CH-C), a comparative study was drawn. Thirty patients with PBC on ursodeoxycholic acid have been enrolled. This group was compared with 30 patients with CH-C and with 20 healthy subjects. Soluble Fas ligand (sFasL) and soluble TRAIL (sTRAIL) levels were evaluated by double determinant immune assay and enzyme-linked immunosorbent assay (ELISA), respectively. Soluble FasL molecules were higher in PBC compared to CH-C (P=0 x 009). Soluble FasL was not detected in controls. Soluble TRAIL was significantly higher in CH-C patients compared to PBC (P=0 x 0001). Soluble TRAIL levels were higher in PBC and in CH-C than in controls (P=0 x 015 and P<0 x 001, respectively). No correlation between sFasL and sTRAIL, stage of disease, liver histology in each disease and cytolysis was present. Our data show different levels of commitment of TRAIL and Fas apoptosis-inducing systems in CH-C and PBC. Thus a different prominent role of TRAIL and Fas systems in the pathogenesis of these two conditions can be speculated: the former by inducing the death of infected hepatocytes, the latter by mediating the disappearance of bile duct.     

Fas ligand exerts its pro-inflammatory effects via neutrophil recruitment but not activation

Fas ligand (FasL) expression induces apoptosis of activated T cells and has been suggested as a strategy to inhibit graft rejection. Unfortunately, the use of FasL to confer 'immune privilege' in this setting has been hampered by the finding that it may also provoke a destructive granulocytic response. While the Fas/FasL-mediated apoptotic pathways are well defined, the pro-inflammatory effects of FasL are poorly understood. Our aim in this study was to define in vitro the biological effects of FasL on neutrophil recruitment and activation. DAP-3 cells expressing human FasL on the cell membrane (mFasL) potently induced apoptosis in human neutrophils and in activated T lymphocytes. Recombinant human soluble FasL (sFasL), by contrast, was a very weak inducer of apoptosis, even at high concentrations. This latter observation suggests that cleavage of mFasL by naturally occurring matrix metalloproteinases may serve to down-regulate FasL activity in vivo. However, in the presence of a cross-linking antibody, the efficiency of apoptosis-induction by sFasL was greatly increased, suggesting that the lesser pro-apoptotic potency of sFasL reflects an inability to induce trimerization of the Fas receptor. With regard to pro-inflammatory effects, we found that sFasL is a potent neutrophil chemoattractant and, given that it induces little apoptosis, the dominance of sFasL over mFasL may mean that graft-infiltrating neutrophils will survive to mediate inflammation. Neither sFasL nor mFasL produced neutrophil activation as assessed by chemiluminescence assay. This suggests that neutrophils recruited to an inflammatory site by FasL will be activated by mechanisms other than Fas-FasL signalling.