乙型肝炎病毒Ⅹ基因对肝细胞凋亡的影响及其作用机制

乙型肝炎病毒X基因(HBx)在HBV慢性感染导致肝硬化,原发性肝癌(HCC)的发生过程中,起着重要的作用[1].X连锁凋亡抑制因子(XIAP)为凋亡抑制蛋白(IAPs)家族成员,是一种强效的凋亡抑制蛋白,可以抑制半胱氨酸蛋白酶活性,阻断细胞凋亡过程[2].我们观察了肝癌细胞株以及正常肝细胞株在转染HBx前后凋亡抑制蛋白XIAP表达的差异,了解和分析HBx对不同肝细胞系细胞凋亡的作用及其是否与凋亡抑制蛋白XIAP基因相关.     

核转录因子Rel/NF-κB与乙型肝炎病毒

乙型肝炎病毒(HBV)的感染,不仅引起急、慢性病毒性肝炎,而且与肝纤维化、肝细胞癌(HCC)的发生密切相关.真核细胞转录因子NF-κB在慢性HBV感染及致HCC发生过程中发挥重要作用,本文对核转录因子Rel/NF-κB的分子生物学特征、活化和转录调控机制、参与-HBV编码蛋白致病及在细胞凋亡发生过程中的机制进行了简要综述.     

NF-κB生物学特性及在肝病中作用

核因子-κB(nuclear factor-kappaB,NF-κB)是一种广泛存在于体内多种细胞的核转录因子,参与多种疾病的病理生理过程,在调节机体的免疫和炎症反应及凋亡调控等方面发挥重要作用[1].     

乙型肝炎与肝癌关系

目的乙型肝炎病毒(HBV)持续感染和宿主免疫反应可导致肝细胞癌(HCC)发生.研究HBV感染致癌机制和乙肝免疫预防HCC具有重要的理论和实际意义.①从分子生物学观点出发探索HBV感染与HCC关系与HCC相关的最危险因素HBV的XORF常整合于宿主DNA并高度表达.现有越来越多的证据表明反式激活剂HBx可能通过封闭抑癌基因p53的功能而致癌.结构与功能分析表明HBx的远C末端为其抑制p53诱导凋亡的必需区.最近发现HBx基因反式激活功能区发生天然"突然”,即可消除其诱导细胞生长停顿和凋亡的效应.②HBx是一多功能调节因子近来研究相对集中在HBx对肝细胞凋亡的作用上,促凋亡或抑凋亡.发现HBx可抑制cospase3酶活性阻断细胞凋亡.但另有报告HBx可致敏细胞引起凋亡.联系上述HBx可封闭由于p53过表达而诱导的凋亡,可见病毒根据不同细胞环境或外来刺激采取不同的策略.③乙肝免疫预防HCCHBVDNA,多在HBx基因整合于宿主DNA,可激活或抑制与生长增殖有关的细胞基因.如整合得到阻遏,细胞转化不至发生.台湾儿童广行乙肝免疫使HBV携带率10%降至0.9%,HCC发生率0.52%降至0.13%,证明控制乙肝是有效防癌措施.     

乙型肝炎病毒P22e蛋白经核因子-κB抑制HepG2细胞凋亡

目的 探讨核因子-κB(NF-κB)在乙型肝炎病毒P22e蛋白抑制HepG2细胞凋亡中的作用.方法 用含HBV P22e基因的重组pEGFP-C2HBVP22e质粒的肝癌细胞HepG2,以放线菌素-D(Act-D)、肿瘤坏死因子(TNF)α诱导该细胞凋亡,采用激光共聚焦显微镜、核蛋白电泳迁移率等技术,观察在HBV P22e抑制TNFα诱导HepG2EGFP-C2HBVP22e细胞的凋亡过程中NF-κB的核转移、活化等情况.用NF-κB抑制剂ALLN抑制其信号通路,检测以Act-D、TNFα诱导的HepG2、HepG2EGFP-C2HBVP22e细胞凋亡率的变化.对实验结果的数据分析用秩和检验和t检验. 结果激光共聚焦显微镜及电泳迁移率实验观察到HepG2EGFP-C2HBVP22e细胞在发生凋亡前后,有明显的NF-κB向核内迁移活化现象.NF-κB抑制剂ALLN可使以Act-D、TNF α诱导HepG2EGFP-C2HBVP22e细胞的凋亡率明显升高(6.19%±1.58%与39.99%±7.620/0,t=7.515,P<0.01).结论 在HBV P22e蛋白抑制肝癌细胞凋亡过程中,NF-κB信号途径起着重要作用.     

核因子-κB与肥胖

核因子-κB(NF-κB)是独特的核转录因子,广泛存在于高级真核生物的各种细胞中,参与炎性反应、分化和凋亡等多种细胞反应.近年来的研究显示,NF-κB在肥胖的发病中起重要作用.NF-κB可能通过促进脂肪组织炎性反应、抑制脂肪细胞分化以及调节脂肪细胞凋亡而参与肥胖的发生与发展.     

核因子-κB抑制蛋白在动脉粥样硬化中的作用及其中医药研究进展

动脉粥样硬化(AS)的发病机制涉及多种学说,炎症学说是AS发病机制中的重要学说。核因子-κB(NF-κB)是炎症反应中的主要转录因子,参与炎症细胞凋亡和细胞增殖的基因调控。NF-κB抑制蛋白通过调节NF-κB信号通路的活动,调控炎症因子的表达,在AS的发生、发展过程中发挥重要的作用。现探究中医药通过调控NF-κB信号通路干预治疗AS的作用机制,以期为中医药治疗动脉粥样硬化提供更多的思路。     

核因子-κB异常激活与肝炎病毒感染关系的研究进展

核因子-κB(NF-κB)是与免疫球蛋白κ轻链增强子B区结合,具有和某些基因上启动子区固定核苷酸序列结合而启动该基因转录的蛋白质。NF-κB是具有多向性调节作用的核转录因子,可调控多种基因(免疫、炎症反应、病毒和原癌基因)的转录表达[1]。激活的NF-κB参与癌症的启动、发生及发展过程,在炎症性相关的肝癌(HCC)发生发展中呈高表达,在肝细胞炎症与癌变间起桥梁作用,其中包括肝脏免疫炎症反应相关基因、肝炎病毒相关基因和原癌基因的转录表达。在肝癌组织中异常激活,可抑制细胞凋亡,促进肝细胞存活,与肝癌的发生发展密切相关[2]。1NF-…     

乙型肝炎病毒X蛋白在原发性肝癌中的作用

乙型肝炎病毒X蛋白(HBx)是一种由HBV X基因编码的多功能蛋白,参与调节基因转录、细胞信号转导、细胞增殖转化、细胞周期和细胞凋亡。目前HBx蛋白被认为在HBV诱发原发性肝癌的过程中发挥重要作用。介绍了HBx蛋白与癌基因、抑癌基因、细胞增殖、细胞凋亡、肝癌侵袭转移和肝癌干细胞的关系,探讨了HBx蛋白在肝癌发生发展中的作用。     

X蛋白调节乙型肝炎病毒复制的研究进展

乙型肝炎病毒X蛋白(hepatitis B virus X protein, HBx)由一段154aa的多肽组成,由HBV的X基因编码,在肝癌的形成中起重要作用,并且广泛参与宿主细胞的基因表达、反式激活和细胞信号传导等 [1].HBx不能直接与DNA结合,但是能活化多种DNA顺式作用元件,如核因子κ B、激活蛋白1、激活蛋白2、CCAAT增强子结合蛋白、活化转录因子/cAMP反应元件结合蛋白等.     

美国2006年慢性乙型肝炎病毒感染处理治疗规范简介

2004年Keeffe等在“临床胃肠病和肝病学”杂志上发表“美国慢性乙型肝炎病毒感染处理治疗规范”。近2年来，由于美国食品药品监督管理局（FDA）先后批准恩替卡韦和聚乙二醇化干扰素（PegIFN）α--2a用于慢性乙型肝炎治疗，并对慢性乙型肝炎的自然史有了新的研究结果，因此，最近Keeffe等美国肝病专家对该《规范》进行了修订，并发表于2006年7月“临床胃肠病和肝病学”杂志。     

Kinetics and risk of de novo hepatitis B infection in HBsAg-negative patients undergoing cytotoxic chemotherapy

BACKGROUND & AIMS: De novo hepatitis B virus (HBV)-related hepatitis after chemotherapy results in high morbidity and mortality. We evaluate the clinical course of de novo HBV-related hepatitis after chemotherapy. METHODS: Two hundred forty-four consecutive hepatitis B surface antigen (HBsAg)-negative lymphoma patients treated with chemotherapy were followed up for a median of 12.4 (range, 0.1-65.0) months. Serially collected serum samples were analyzed for hepatitis, serum HBV DNA, and HBsAg seroreversion. RESULTS: Eight of the 244 patients (3.3%) developed de novo HBV-related hepatitis. A 100-fold increase in serum HBV DNA preceded de novo HBV-related hepatitis by a median of 18.5 (range, 12-28) weeks. All 8 patients had normal serum alanine aminotransaminase level when the 100-fold increase in serum HBV DNA occurred. Patients with de novo HBV-related hepatitis were more likely to have occult HBV infection before chemotherapy. Direct sequencing results showed that these 8 patients had de novo HBV-related hepatitis from reactivation of occult HBV infection. Three of the 8 patients with de novo HBV-related hepatitis compared with 6 of the 236 patients without de novo HBV-related hepatitis developed fulminant hepatic failure (37.5% vs 2.5%, respectively, P < .001). On multivariate Cox analysis, de novo HBV-related hepatitis was independently associated with a higher risk of fulminant hepatic failure (relative risk, 29.854; 95% confidence interval: 4.844-183.980; P < .001). CONCLUSIONS: Close surveillance for a 100-fold increase in HBV DNA is recommended for HBsAg-negative patients treated with chemotherapy so that early commencement of antiviral therapy can be initiated before the occurrence of de novo HBV-related hepatitis.     

天津市1992-2010年新生儿乙型肝炎疫苗免疫策略成本效果分析

目的：探讨天津市1992-2010年新生儿乙型肝炎（乙肝）疫苗免疫策略的效果和经济效益。方法以天津市疾病预防控制中心历年计划免疫报告资料和血清学监测结果为基础，借助社区大规模乙肝及相关疾病监测，以乙肝及相关疾病患者为经济负担调查对象，运用成本效益分析方法进行综合评价。结果现行乙肝疫苗免疫接种的策略下，天津市20岁以下人群报告发病率由14.14/10万（1992年）下降到9.46/10万（2010年），下降幅度达33.00%。1992-2010年共减少HBsAg携带者98984例，慢性乙肝17830例，乙肝肝硬化5310例，肝癌1606例。共产出效益473.51亿元，净效益473.12亿元，效益成本比为1213∶1。结论天津市实施儿童乙肝疫苗免疫策略可获得巨大经济效益和社会效益。     

Lamivudine plus low-dose hepatitis B immunoglobulin to prevent recurrent hepatitis B following liver transplantation

BACKGROUND AND AIMS: High-dose intravenous hepatitis B immunoglobulin (HBIG) may prevent recurrent hepatitis B virus (HBV) infection, but the cost has limited its widespread use in countries with endemic HBV infection. We report on long-term safety and efficacy of an alternative strategy of very low doses (400-800 IU/month) of intramuscular (IM) HBIG plus lamivudine. METHODS: Australian and New Zealand patients who received low-dose HBIG plus lamivudine following liver transplantation for HBV-related end-stage liver disease were studied. Prior to transplantation, patients with detectable serum HBV DNA received lamivudine 100 mg daily. Posttransplantation, all patients received lamivudine 100 mg daily plus IM HBIG 400 or 800 IU daily for 1 week then monthly thereafter. Serum HBV DNA levels were measured prior to lamivudine, at transplantation, and at 12 months posttransplantation. Serum titers of antibody to HBV surface antigen were measured at 1, 3, and 12 months posttransplantation. RESULTS: Between February 1996 and October 2004, 147 patients received low-dose HBIG plus lamivudine. Thirty-one percent were hepatitis B e antigen positive, and 85% were HBV DNA+ prior to transplantation. The median duration of pretransplantation lamivudine was 92 days (range, 1-1775). Median follow-up posttransplantation was 1860 days. Kaplan-Meier patient survival was 92% at 1 year and 88% at 5 years. The actuarial risk of HBV recurrence was 1% at 1 year and 4% at 5 years. Baseline HBV DNA titer was associated with HBV recurrence. CONCLUSION: Low-dose IM HBIG plus lamivudine provides safe and effective long-term prophylaxis against recurrent HBV at <10% the cost of the high-dose regimen.     

Hepatitis B vaccination alone is not adequate for the categorizing of adult subjects with isolated anti-HBc

Abstract To evaluate the meaning of isolated antibody to hepatitis B core antigen (anti-HBc), 88 Chinese subjects with isolated anti-HBc received rescreening of hepatitis B virus (HBV) markers. Eighty (90.9%) of them were still positive for this antibody and 29 were also found to be positive for antibody to hepatitis B surface antigen (anti-HBs). The remaining 51 subjects (58.0%) were positive for anti-HBc alone; 50 of them received a four-dose schedule of hepatitis B (HB) vaccine. After the initial dose, only one vaccinee disclosed an amnestic anti-HBs response, that is, anti-HBs titre > 1000 miu/mL. Forty-five vaccinees completed the vaccination schedule and 44 (97.8%) had anti-HBs response. The anti-HBs responses in 25 of these vaccinees were compared with 25 age- and sex-matched normal susceptible vaccinees. The anti-HBs response rates in both groups were the same (96 vs 96%). However, the geometric mean titre was significantly lower in the vaccinees with isolated anti-HBc (512 mIU/mL vs 4688 mIU/mL, P < 0.001). Prevaccinated sera were available in 49 vaccinees with isolated anti-HBc for detection of antibody to hepatitis B e antigen (anti-HBe) and HBV DNA; 37 (75.5%) of them had one or two of these markers. As we regarded the rescreening of HBV markers, response to hepatitis B vaccination and presence or absence of anti-HBe and/or HBV DNA together for categorizing the 88 subjects with isolated anti-HBc, at least three-quarters of them had past infection of HBV. The subjects with false positive anti-HBc test were a minor group. We concluded that the presence or absence of amnestic anti-HBs response to HB vaccination is not a reliable indicator for categorizing subjects with isolated anti-HBc. Rescreening of HBV markers, with addition of anti-HBe and HBV DNA, may be helpful in determining the necessity of HB vaccination.     

Application of nucleoside analogues to liver transplant recipients with hepatitis B

Hepatitis B is a common yet serious infectious disease of the liver, affecting millions of people worldwide. Liver transplantation is the only possible treatment for those who advance to end-stage liver disease. Donors positive for hepatitis B virus(HBV) core antibody(HBc Ab) have previously been considered unsuitable for transplants. However, those who test negative for the more serious hepatitis B surface antigen can now be used as liver donors, thereby reducing organ shortages. Remarkable improvements have been made in the treatment against HBV, most notably with the development of nucleoside analogues(NAs), which markedly lessen cirrhosis and reduce post-transplantation HBV recurrence. However, HBV recurrence still occurs in many patients following liver transplantation due to the development of drug resistance and poor compliance with therapy. Optimized prophylactic treatment with appropriate NA usage is crucial prior to liver transplantation, and undetectable HBV DNA at the time of transplantation should be achieved. NA-based and hepatitis B immune globulin-based treatment regimens can differ between patients depending on the patients' condition, virus status, and presence of drug resistance. This review focuses on the current progress in applying NAs during the perioperative period of liver transplantation and the prophylactic strategies using NAs to prevent de novo HBV infection in recipients of HBc Ab-positive liver grafts.