Involvement of Fas system-mediated apoptosis in pathogenesis of viral hepatitis

Enhanced Fas system-mediated hepatocyte apoptosis is observed in hepatitis C virus (HCV)- and hepatitis B virus (HBV)-associated chronic liver diseases. In these forms of viral hepatitis, liver-infiltrating lymphocytes that recognize the viral antigen on hepatocytes become activated and express cytolytic Fas ligand (FasL) molecules. In contrast, hepatocytes exhibit enhanced Fas expression and become susceptible to FasL-mediated death. Augmentation of the Fas system has also been observed in other liver diseases and biliary disorders. Moreover, the Fas system is involved in removing aged hepatocytes. Thus, Fas-mediated apoptosis plays an important role in several liver diseases and in maintaining normal liver homeostasis.     

丁型肝炎患者肝组织中Fas/FasL和肝细胞凋亡表达

目的探讨Fas/FasL及肝细胞凋亡在丁型肝炎患者肝组织中的表达及作用.方法采用免疫组化双重染色和TUNEL技术,检测79例丁肝患者肝组织HDAg,Fas/FasL表达,以及肝细胞凋亡,以54例乙型肝炎作对照.结果Fas以肝细胞浆表达为主,HDAg以核浆型表达为主,二抗原表达及分布有相关性.FasL主要表达在浸润淋巴细胞浆、肝细胞核,与HDAg表达及分布不全一致.HDAg,Fas/FasL和肝细胞凋亡在各型肝炎中的表达强度有显著性差别意义.结论HDV感染可诱导肝细胞Fas/FasL表达,增强Fas/FasL途径介导的肝细胞凋亡,这一机制在丁型肝炎发病机制中可能有一定的重要作用.     

In situ investigation of Fas/FasL expression in chronic hepatitis B infection and related liver diseases

To evaluate Fas/FasL expression in hepatitis B virus-related chronic liver disease, liver biopsies from 44 such cases were studied immunohistochemically. FasL was detected in the infiltrating lymphocytes and both FasL and Fas were found in the hepatocytes. The Fas and FasL-positive cells were mostly found at the advancing edges of interphase hepatitis, and Fas/FasL expression was closely correlated with the inflammatory activity. Unexpectedly, FasL was also expressed in liver cirrhotic nodules, particularly in those with hepatocellular carcinoma with or without inflammation. These results suggest that the factors which induce hepatocyte transformation might also trigger FasL expression and promote FasL/Fas-mediated apoptosis.     

血吸虫病小鼠肝纤维化肝组织中Fas/FasL的表达

目的 探讨Fas／FasL在血吸虫病肝纤维化肝组织中的表达及意义。 方法 采用免疫组化技术检测血吸虫病小鼠肝纤维化肝组织中Fas／FasL的表达,并对照经吡喹酮、已酮可可碱治疗前后其表达的变化,分析其意义。 结果Fas以肝细胞浆表达为主,FasL主要在浸润淋巴细胞浆、肝细胞核表达。经吡喹酮及高剂量已酮可可碱治疗后其肝组织Fas／FasL表达明显减少(P<0.01)。 结论 血吸虫感染可诱导肝细胞Fas／FasL的表达,增强Fas／FasL途径介导的肝细胞凋亡,这一机制在血吸虫病肝纤维化的发病中可能起重要作用。吡喹酮及高剂量已酮可可碱可明显下调Fas／FasL的表达,抑制肝细胞凋亡,改善肝功能。     

Fas ligand-induced apoptosis of hepatocytes in natural killer cell leukaemia

Neoplastic natural killer (NK) cells overexpress Fas ligand (FasL), which may cause damage of Fas-bearing tissues. We report a patient with NK cell leukaemia who developed liver injury after pharyngitis. The NK leukaemic cells expressed functional FasL. In addition to soluble FasL, serum levels of interleukin-6 and interferon-gamma were increased dramatically when liver injury was aggravated. Moreover, hepatocytes expressed Fas and apoptotic hepatocytes were detected in the portal areas. These findings are consistent with the notion that inflammatory cytokines enhance the sensitivity to FasL and trigger apoptosis of hepatocytes in NK cell malignancies.     

慢性HBV携带者肝组织Fas和Fas配体表达变化及其意义

目的：观察慢性HBV携带者（chronic asymptomatic HBV carrier,ASC）肝组织Fas和Fas配体（FasL）的表达和血清可溶性Fas（sFas）水平的变化。方法对120例ASC行肝穿刺,采用免疫组织化学法检测肝组织Fas和FasL表达,采用ELISA法检测血清sFas水平。结果120例ASC肝组织完全正常者仅占11%,轻度肝炎占59%,而中、重度肝炎占30%;表现正常的肝组织无Fas和FasL表达,轻度肝炎肝组织多无表达或仅限于界面炎症区的肝细胞及淋巴细胞阳性表达,而中、重度肝炎肝组织Fas和FasL多为阳性,Fas强阳性率分别达34.8%和69.2%,FasL强阳性率分别达30.4%和53.8%,均明显高于正常组和轻度炎症组（P〈0.05）,同时中、重度肝炎组间也存在显著性差异（P〈0.05）,其分布除界面炎症区外,肝小叶中也弥漫分布;肝组织表现正常的ASC血清sFas水平为（1.68±0.33） ng/L,而轻、中、重度肝炎患者则分别为（2.58±0.31）ng/L、（3.94±0.21）ng/L和（5.94±0.26）ng/L,均较正常组显著升高（F=218.01,P〈0.01）,各组间sFas水平也均具有统计学差异（P〈0.01）。结论 Fas和FasL介导的肝细胞凋亡在慢性HBV携带者肝组织病变中可能起到了重要作用。     

A novel cDNA-uPA/SCID/Rag2−/−/Jak3−/− mouse model for hepatitis virus infection and reconstruction of human immune system

Although human hepatocyte-transplanted immunodeficient mice support infection with hepatitis viruses, these mice fail to develop viral hepatitis due to the lack of an adaptive immune system. In this study, we generated new immunodeficiency cDNA-urokinase-type plasminogen activator (uPA)/SCID/Rag2^−/−/Jak3^−/− mice and established a mouse model with both a humanized liver and immune system. Transplantation of human hepatocytes with human leukocyte antigen (HLA)-A24 resulted in establishment of a highly replaced liver in cDNA-uPA/SCID/Rag2^−/−/Jak3^−/− mice. These mice were successfully infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) for a prolonged period and facilitate analysis of the effect of anti-HCV drugs. Administration of peripheral blood mononuclear cells (PBMCs) obtained from an HLA-A24 donor resulted in establishment of 22.6%–81.3% human CD45-positive mononuclear cell chimerism in liver-infiltrating cells without causing graft-versus-host disease in cDNA-uPA/SCID/Rag2^−/−/Jak3^−/− mice without human hepatocyte transplantation. When mice were transplanted with human hepatocytes and then administered HLA-A24-positive human PBMCs, an alloimmune response between transplanted human hepatocytes and PBMCs occurred, with production of transplanted hepatocyte-specific anti-HLA antibody. In conclusion, we succeeded in establishing a humanized liver/immune system characterized by an allo-reaction between transplanted human immune cells and human liver using a novel cDNA-uPA/SCID/Rag2^−/−/Jak3^−/− mouse. This mouse model can be used to generate a chronic hepatitis mouse model with a human immune system with application not only to hepatitis virus virology but also to investigation of the pathology of post-transplantation liver rejection.     

HDV/HBV感染树鼩肝组织Fas/FasL表达与肝细胞凋亡

目的 探讨HDV感染树鼩肝组织中Fas/FasL表达与HDV感染之间的关系,以及Fas/FasL在丁型肝炎肝细胞凋亡中的作用。 方法 采用免疫组化和原位杂交技术对45份HDV感染树鼩肝组织中HDAg,Fas/FasL和Fas/FasL mRNA的表达进行了检测;应用原位末端标记技术对肝细胞凋亡进行了检测;并应用免疫组化双重染色对HDAg,Fas/FasL的表达以及肝细胞凋亡进行了检测。 结果 45份肝组织中有39份可检出Fas/FasL(阳性率87％),有41份可检出凋亡细胞(阳性率91％),HDAg表达与Fas/FasL表达之间有显著相关性(X_1~2=29.2,X_2~2=27.9,P<0.05),HDAg表达越强,Fas和FasL表达也越强,凋亡在HDAg阳性和阴性细胞中均可发生,以HDAg阳性细胞发生为主,Fas/FasL表达与肝细胞凋亡之间有显著相关性(X_1~2=35.1,X_2~2=40.2,p<0.05),Fas和FasL表达越强,凋亡阳性细胞越多。 结论 丁型肝炎病毒感染和未感染的肝细胞均可发生凋亡,但凋亡只在少数细胞发生;肝细胞内的病毒抗原表达可诱导Fas/FasL的表达;Fas/FasL肝细胞凋亡中起重要作用。     

Fas、FasL在慢性乙型肝炎患者肝细胞和外周血淋巴细胞上的表达

探讨慢性乙型肝炎患者肝细胞及外周血淋巴细胞上Fas、FasL的表达与乙型肝炎病毒（HBV）复制水平及肝组织炎症程度的关系。对30例慢性乙型肝炎患者进行肝穿刺肝组织病理检查及免疫组化SP法检测肝细胞中Fas、FasL表达强度。并采用单克隆抗体经流式细胞仪检测外周血淋巴细胞上Fas、FasL表达阳性百分率;同时,采用荧光实时标记法测定血清中病毒复制指标HBV DNA水平;采用Beckman全自动生化分析仪检测肝功能并研究其相关性。慢性乙型肝炎患者肝细胞中Fas、FasL表达强度随肝组织炎症活动度加重而增强（P均〈0．001）,与白蛋白及丙氨酸转移酶（ALT）呈负相关（P〈0．005,P〈0．001）,与球蛋白、总胆红质无明显相关性（P均〉0．05）。外周血淋巴细胞上Fas、FasL的表达阳性率与血清中肝炎病毒复制指标HBV DNA水平呈正相关;与慢性肝炎分度无明显的相关性。乙型肝炎病毒感染可诱导肝细胞及外周血淋巴细胞上Fas、FasL的表达。肝细胞Fas、FasL的表达随炎症活动度加重而表达增强,但其介导的凋亡并不引起肝细胞炎症损伤即ALT活性并不升高,相反减少;同时在某种程度上影响白蛋白的合成。提示Fas—FasL介导的肝细胞凋亡是以非细胞损伤方式参与慢性乙型肝炎的发病过程。同时,随血清HBV DNA水平增高,外周血淋巴细胞上Fas、FasL的表达亦增强,淋巴细胞的凋亡因而增多,是导致乙型肝炎慢性化的原因之一。由此可见,Fas、FasL介导的凋亡参与了慢性乙型肝炎的发病机制,且在慢性乙型肝炎的发生发展中起重要作用。     

Increased susceptibility to liver injury in hepatitis B virus transgenic mice involves NKG2D-ligand interaction and natural killer cells

The innate immunopathogenesis responsible for the susceptibility to hepatocyte injury in chronic hepatitis B surface antigen carriers is not well defined. In this study, hepatitis B virus (HBV) transgenic mice (named HBs-Tg) were oversensitive to liver injury after immunologic [polyinosinic:polycytidylic acid or concanavalin A (ConA)] or chemical (CCl4) triggering. It was then found that the nonhepatotoxic low dose of ConA for wild-type mice induced severe liver injury in HBs-Tg mice, which was dependent on the accumulated intraheptic natural killer (NK) cells. Expressions of NKG2D ligands (Rae-1 and Mult-1) in hepatocytes were markedly enhanced upon ConA stimulation in HBs-Tg mice, which greatly activated hepatic NK cells via NKG2D/Rae-1 or Mult-1 recognition. Interestingly, the presence of NK T cells was necessary for NK cell activation and worked as positive helper cell possibly by producing interferon-gamma and interleukin-4 in this process. CONCLUSION: Our findings for the first time suggested the critical role of NKG2D recognition of hepatocytes by NK cells in oversensitive liver injury during chronic HBV infection.     

肝细胞凋亡与慢性乙型肝炎病毒携带者肝组织病变的关系

目的 观察慢性HBV携带者（ASC）肝组织凋亡指数及Fas、FasL的表达,探讨肝细胞凋亡在ASC肝组织病变中的作用.方法 选取HBV携带者患者120例,并进行肝组织活检.采用原位末端转移酶标技术进行肝细胞凋亡情况检测,采用免疫组织化学技术检测肝组织中的Fas、FasL.结果 120例ASC肝组织完全正常者仅占11％,轻度肝炎组占59％,而中、重度肝炎组占30％.ASC患者的凋亡指数（AI）随着炎症程度加重而升高,正常组为1.50±1.04,而中度组、重度组分别为11.33 ±1.51和17.67 ±6.42,各组间比较差异有统计学意义（P＜0.05）.肝组织免疫组化结果显示,Fas、FasL表达程度随炎症活动度加重而增强,尤其在汇管区周围碎屑状坏死区及周边小叶更明显,正常组基本无表达,而轻度组以无表达或阳性表达为主,仅见于界面炎症区的肝细胞及淋巴细胞上;中、重度肝炎组Fas、FasL则均为阳性及强阳性表达,除界面炎症区外,肝小叶中也弥漫分布.Fas强阳性表达率在中、重度组分别为34.8％和69.2％,FasL的强阳性表达率分别为30.4％和53.8％,均明显高于正常组和轻度组（P＜0.05）,同时中、重度组间比较差异亦有统计学意义,肝组织中Fas、FasL表达程度随炎症活动度加重而增强,两者间明显相关.结论 肝细胞凋亡在ASC肝组织病变的发生发展中可能起到重要作用.     

Overexpression of granulocyte‐macrophage colony‐stimulating factor in mouse liver enhances the susceptibility of lipopolysaccharide leading to massive apoptosis of hepatocytes

Abstract: Background/Aims: We examined whether antigen‐nonspecific accumulation of dendritic cells (DCs) and macrophages in the liver by the overexpression of granulocyte macrophage‐colony stimulating factor (GM‐CSF) could prime severe liver injury after LPS injection. Methods: We injected a recombinant adenovirus encoding GM‐CSF intravenously (AdGM), and LPS was administered 7 days later. Liver histology, serum alanine aminotransferase (ALT) levels and apoptosis of hepatocytes were examined. Results: Liver histology of the AdGM‐primed mice showed marked infiltrates of mononuclear cells (DCs and macrophages) without granuloma formation on day 7. Expression of toll‐like receptor‐4 on intrahepatic mononuclear cells isolated from AdGM‐primed mice was up‐regulated. After LPS injection, serum ALT levels in AdGM‐primed mice reached about 6000 IU/l at 12 h, and all those mice died within 24 h. Hemorrhagic liver injury with massive apoptosis of hepatocytes was histologically recognized. When AdGM and LPS were injected in FasL‐deficient C57BL/6J‐gld/gld mice, serum ALT levels were not elevated by the pretreatment with a neutralizing anti‐TNF‐α antibody. Conclusions: Our present study provides a new model of severe liver injury, in which antigen‐nonspecific accumulation of DCs and macrophages in the liver by overexpressing GM‐CSF enhances the susceptibility to LPS, leading to hemorrhagic liver injury with massive hepatocyte apoptosis after LPS injection.     

慢性乙型肝炎和肝病中Fas和FasL表达的原位研究

目的了解慢性乙型肝炎和肝病时介导凋亡的Ｆａｓ／ＦａｓＬ表现。方法以免疫组化法原位检查各种慢性肝病４５例的活检肝组织。结果肝内浸润的淋巴细胞中检出ＦａｓＬ，肝细胞Ｆａｓ／ＦａｓＬ表达与炎症活动性一致，多分布在界面性炎症区。肝细胞表达ＦａｓＬ，可能也发挥细胞毒效应。结论新的发现是ＦａｓＬ可在肝细胞结节和肝癌细胞表达，提示有细胞毒效应的ＦａｓＬ在ＨＢ相关慢性肝病中有发病学意义。肝癌细胞中未检出Ｆａｓ而检出ＦａｓＬ，可能是一种肿瘤逃避免疫攻击的机制     

Transfection of apoptosis related gene Fas ligand in human hepatocellular carcinoma cells and its significance in apoptosis

AIM: To evaluate the expression of apoptosis related gene Fas ligand (FasL) in human hepatocellular carcinoma (HCC) cells HepG2 and its significance in apoptosis. METHODS: Levels of soluble Fas ligand (sFasL) in a group of patients with hepatitis B virus (HBV)-induced chronic hepatitis, HBV-positive liver cirrhosis and HCC were evaluated. In a further study, the recombinant eukaryotic expression plasmid pcDNA3.1hisB-FasL was transfected into HCC cells HepG2 by lipofection, and then soluble FasL was examined in the supernatant of culture cells by EIA, FasL expression in HepG2 cells was detected by immuohistochemistry. After being stained by annexin V and propidium iodine, cells were passed through a flow cytometer and examined by a fluorescence microscope and a laser scanning microscope. RESULTS: The sFasL levels were significantly lower in patients with HCC when compared to the patients with hepatitis or liver cirrhosis. In comparison with untransfected cells, the soluble FasL could be detected in the supernatant of transfected cells. FasL was expressed on the membranes and cytoplasm of transfected cells. The apoptotic cell rate was 36.30% in transfected cells, and was 11.53% in untransfected cells. Moreover, the different stage of apoptotic cells could be distinguished by annexin V and propidium iodine staining. CONCLUSION: Fas ligand is an apoptotic pathway of HCC cells.     

凋亡相关基因Fas、Fas配体及bax在慢性病毒肝炎组织中的表达及意义

为探讨凋亡相关基因Ｆａｓ、Ｆａｓ配体及ｂａｘ在慢性病毒性肝炎中表达的意义。采用免疫组化技术研究４８例慢性肝炎（乙型肝炎３３例,丙型肝炎１５例）组织中Ｆａｓ、ＦａｓＬ及ｂａｘ的表达。结果：慢性乙型肝炎和丙型肝炎组织中Ｆａｓ、ＦａｓＬ及ｂａｘ表达均较正常肝增加,以细胞坏死和炎细胞浸润区域增加明显。结论：凋亡相关基因Ｆａｓ、Ｆａｓ及ｂａｘ可能参与了肝炎病毒致肝细胞的损伤过程。     

慢性丙型肝炎肝组织CPP32、Fas和Fas配体的表达及其与病毒抗原的关系

目的 探讨慢性丙型病毒性肝炎（ＣＨＣ）中Ｆａｓ－ＦａｓＬ－ＣＰＰ３２介导的细胞凋亡的意义及其与丙型肝炎病毒（ＨＣＶ）抗原表达间的关系。方法 用免疫组织化学和核酸原位杂交法,在连续组织切片上对６５例不同病变程度的ＣＨＣ穿刺活检肝组织中ＣＰＰ３２、Ｆａｓ和ＦａｓＬ蛋白（酶）及其ｍＲＮＡ的表达进行检测。同时用免疫组织化学方法检测ＨＣＶ核心抗原、ＮＳ３和ＮＳ５抗原的表达,原位检测结果用图象分析作定量测定,     

Fas、FasL在慢性乙型肝炎肝组织中的表达

探讨Fas、FasL在慢性乙型肝炎肝组织中的表达特点。对 30例慢性乙型肝炎患者进行肝穿刺肝组织病理检查及免疫组化法检测肝组织中的Fas/FasL表达强度。 (1)Fas、FasL在肝组织肝细胞膜及胞浆均有不同程度表达 ,其表达阳性细胞主要位于汇管区小叶内及周边碎屑状坏死区 ,呈弥漫分布 ,在其周围浸润的淋巴细胞上多为FasL阳性细胞 ,亦可见到Fas阳性细胞。 (2 )肝组织中Fas、FasL表达随着慢性肝炎程度即炎症和纤维化程度加重而加强 (P均 <0 0 0 1)。Fas-FasL系统介导的细胞凋亡 ,确实参与了慢性乙型肝炎的发病机制 ,且在慢性乙型肝炎的发生发展中起重要作用。     

Impairment of liver regeneration correlates with activated hepatic NKT cells in HBV transgenic mice

A fraction of HBV carriers have a risk to develop liver cancer. Because liver possesses a strong regeneration capability, surgical resection of cancerous liver or transplantation with healthy liver is an alternate choice for HBV-caused hepatocarcinoma therapy. How HBV infection affects the regeneration of hepatectomized or transplanted liver remains elusive. We report that partial hepatectomy (PHx)-induced liver regeneration was reduced in HBV transgenic (HBV-tg) mice, a model of human HBV infection. PHx markedly triggered natural killer T (NKT) cell accumulation in the hepatectomized livers of HBV-tg mice, simultaneously with enhanced interferon gamma (IFN-gamma) production and CD69 expression on hepatic NKT cells at the early stage of liver regeneration. The impairment of liver regeneration in HBV-tg mice was largely ameliorated by NKT cell depletion, but not by natural killer (NK) cell depletion. Blockage of CD1d-NKT cell interaction considerably alleviated NKT cell activation and their inhibitory effect on regenerating hepatocytes. Neutralization of IFN-gamma enhanced bromodeoxyuridine incorporation in HBV-tg mice after PHx, and IFN-gamma mainly induced hepatocyte cell cycle arrest. Adoptive transfer of NKT cells from regenerating HBV-tg liver, but not from normal mice, could inhibit liver regeneration in recipient mice. CONCLUSION: Activated NKT cells negatively regulate liver regeneration of HBV-tg mice in the PHx model.