肝纤维化逆转和肝星状细胞凋亡的研究进展

肝纤维化是肝损伤的修复机制.肝星状细胞表型转换和增生在肝纤维化形成中起重要作用.通过TNF超家族受体Fas及P75、外周苯二氮卓类受体PBR、整合素受体介导激活的肝星状细胞凋亡而使其数量减少,细胞外基质和基质金属蛋白酶组织抑制因子明显下降,从而导致肝纤维化发生逆转.肝星状细胞的凋亡受到凋亡和抗凋亡基因、细胞因子等的调控.表明可通过调节肝星状细胞的凋亡为治疗肝纤维化寻找理想途径.     

肝纤维化中HSC调控与基质降解的靶向RNA干扰实验研究进展

肝纤维化是各种慢性肝损伤因素引起肝组织反复发生炎症损伤,导致结缔组织异常增生的病理过程。肝纤维化过程复杂,受多种因素影响。目前认为肝星状细胞(hepatic stellate cell, HSC)是其关键因素。尽管不断有新的肝纤维化治疗方法的阐释,但至今临床仍缺乏针对肝纤维化的单一环节特效靶向药物。RNA干扰(RNA interference,RNAi)等基因生物技术的发展为该疾病的基因治疗提供了新的途径。近年来RNAi在肝纤维化中HSC的调控和细胞外基质降解的实验研究发展较快,文章对此最新研究进展作一综述。     

肝纤维化中星状细胞信号转导通路

肝星状细胞活化增殖是肝纤维化发生的关键。肝星状细胞在活化增殖过程中受多种细胞因子或蛋白的调控,通过表面受体激活信号转导网络系统,促使肝纤维化的发生发展。这些表面受体和信号转导通路成为研究的靶向,为纤维化的发生和逆转提供理论依据。     

吡非尼酮抗肝纤维化机制

吡非尼酮是正在研发的新型广谱抗纤维化药物,目前抗肝纤维化治疗已进入Ⅱ期临床试验阶段,其作用机制与抑制脂质过氧化、减轻炎症反应、抑制肝星状细胞活化和增殖、调节细胞外基质的合成与降解有关.本文对吡非尼酮抗肝纤维化的研究现状及作用机制作一综述.     

NK细胞在肝纤维化中作用的研究进展

慢性肝损伤激活肝星状细胞产生I型胶原纤维,造成大量的细胞外基质堆积,从而形成肝纤维化。免疫微环境的变化在肝纤维化的进展和转归中发挥重要作用。自然杀伤(natural killer,NK)细胞是肝脏重要的固有免疫细胞,能够通过直接的细胞毒性作用和产生γ-干扰素等效应分子杀死肝星状细胞,起到明显的抗肝纤维化作用,同时也会对...     

Hedgehog信号通路与肝纤维化研究进展

<正>肝纤维化是机体对各种慢性肝损伤产生的一种修复反应。目前认为,在肝纤维化的发生发展和逆转过程中,肝星状细胞(hepatic stellate cell, HSC)将被活化并最终成为肌成纤维细胞活化和增殖的最大贡献者~([1])。HSC的激活受一系列细胞因子和复杂细胞内信号转导网络的调控。Hedgehog(Hh)信号通路不仅在正常胚胎发育和成人组织稳态中有重要作用,其异常活化还与包括肝纤维化在内的多种疾病密切相关。现对Hh信号通路及其在肝纤维化中的调控机制,以     

诱导肝星状细胞铁死亡治疗肝纤维化的研究进展

铁死亡是一种铁依赖性的调节性细胞死亡形式,通过使肝星状细胞(HSC)失活、抑制肝纤维化和诱导肝细胞死亡参与肝纤维化发病机制,药物诱导HSC铁死亡治疗肝纤维化。探索诱导HSC铁死亡成为治疗肝纤维化的新靶点。     

肝纤维化肝窦内皮细胞对肝星状细胞的影响

肝纤维化是肝损伤后修复性应答。当损肝因素导致肝损伤时,肝内相关细胞分泌多种细胞冈子经旁分泌和自分泌的形式激活肝星状细胞(hepatic stellate cell,HSC),致使其分泌大量细胞外基质(extracellular matrix,ECM),导致ECM的生成大于降解,以致ECM过度沉积,从而引起肝窦毛细血管化,促使肝纤维化形成,故HSC的激活是     

盐酸石蒜碱通过Akt/Smad通路抑制肝星状细胞增殖与活化

目的探索并验证盐酸石蒜碱(LH)抗肝纤维化活性,并初步阐明其机制,为LH研发成为抗肝纤维化药物提供理论支持。方法利用I型胶原α1(COL1A1)启动子-荧光素酶报告系统筛选LH抗肝纤维化活性,利用SRB方法检测LH对人肝星状细胞LX2增殖的影响。通过TGF-β1诱导LX2细胞活化建立体外肝纤维化模型,运用q RT-PCR和Western blot方法检测不同浓度LH对肝纤维化标志基因转录水平以及蛋白表达水平的抑制作用。Western blot方法检测肝纤维化相关信号通路的蛋白表达变化。结果 LH可剂量依赖性地抑制COL1A1基因启动子活性,提示其可能有抗肝纤维化活性。LH显著抑制肝星状细胞LX2的增殖,其对LX2细胞的IC_(50)值为(9.79±1.02)μmol/L;LH可以抑制活化的LX2细胞肝纤维化相关基因的mRNA和蛋白的水平;LH可以抑制Akt/Smad信号通路的活性。结论 LH可能通过Akt/Smad信号通路抑制肝星状细胞增殖与活化,从而发挥抗肝纤维化的作用。     

贮脂细胞凋亡与肝纤维化逆转

贮脂细胞经过激活、刺激性增殖、表型转换后分泌大量的细胞外基质和基质金属硫蛋白酶抑制剂 (TIMPs)而在肝纤维化中发挥了关键作用。但随着贮脂细胞的激活 ,其凋亡敏感性发生改变 ,通过Fas依赖途径发生凋亡 ,其数量明显减少 ,细胞外基质合成和TIMPs的表达快速下降 ,而使肝纤维化发生逆转。这一过程涉及贮脂细胞中凋亡和抑凋亡基因的表达变化。提示通过诱导激活的贮脂细胞凋亡 ,可能为肝纤维化的逆转治疗提供一新的乐观手段。     

Anti-fibrotic treatments for chronic liver diseases: The present and the future

Liver fibrosis reflects tissue scarring in the liver due to the accumulation of excessive extracellular matrix in response to chronically persistent liver injury. Hepatocyte cell death can trigger capillarization of liver sinusoidal endothelial cells, stimulation of immune cells including macrophages and Kupffer cells, and activation of hepatic stellate cells (HSCs), resulting in progression of liver fibrosis. Liver cirrhosis is the terminal state of liver fibrosis and is associated with severe complications, such as liver failure, portal hypertension, and liver cancer. Nevertheless, effective therapy for cirrhosis has not yet been established, and liver transplantation is the only radical treatment for severe cases. Studies investigating HSC activation and regulation of collagen production in the liver have made breakthroughs in recent decades that have advanced the knowledge regarding liver fibrosis pathophysiology. In this review, we summarize molecular mechanisms of liver fibrosis and discuss the development of novel anti-fibrotic therapies.     

Notch signaling affects biliary fibrosis via transcriptional regulation of RBP-jκ in an animal model of chronic liver disease

Liver repair in patients with a chronic liver disease requires the orchestrated action of epithelial, mesenchymal, and inflammatory cells. Notch components are expressed in both the epithelial and mesenchymal compartments of the adult liver and are differentially regulated after injury. However, the functional role of Notch signaling in regulating epithelial/mesenchymal cross-talk during fibrogenic pathologic repair remains unknown. The aim of this study was to investigate how proliferation of the bile duct influences biliary fibrosis and to recognize the effect of inhibiting Notch signaling in biliary fibrotic tissue of the injured liver. We designed a synthetic decoy oligodeoxynucleotide (ODN) for recombination signal binding protein immunoglobulin kappa J (RBP-jκ), which is a common DNA-binding partner of Notch receptors. The effect of blocking RBP-jκ on fibrogenesis was assessed in the 3,5-Diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet mouse model. We observed the reduced fibrosis and decreased expression of associated signaling molecules after the RBP-jκ decoy ODN treatment. These data demonstrate that Notch signaling may play an important role in progression of ductular reaction and fibrosis. Further studies are required to unveil how ductular cells interact with other liver cell types, such as hepatic stellate cells or Kupffer cells,in patients with cholestatic liver diseases based on Notch signaling. These results suggest that controlling the ductular reaction using a synthetic ring type decoy RBP-jκ ODN will help develop a novel therapeutic approach targeting biliary fibrosis in patients with chronic liver diseases.     

Histochemical characteristics of fat-storing cells in alcoholic liver disease: a study by the gold chloride method using needle biopsy specimens of the liver

To evaluate the relationship between fat-storing cells and fibrosis of the liver in alcoholic liver disease, the characteristics of fat-storing cells were studied by light microscopy with a modification of Kupffer's gold chloride method. Liver biopsy specimens were obtained at laparoscopy with a Trucut needle from 59 patients with alcoholic liver disease, 10 with no hepatic fibrosis, 18 with mild fibrosis, 18 with moderate fibrosis, and 13 with liver cirrhosis. These specimens were divided into three classes (weak, moderate, and strong) with respect to the response of fat-storing cells to the gold chloride reaction, which indicates the amount of vitamin A contained in fat-storing cells. It was found that in alcoholic liver disease the gold chloride reaction became weaker as hepatic fibrosis progressed (P less than 0.001). By contrast, no significant association was observed between the gold chloride reaction and the degree of hepatic fibrosis in 74 specimens from patients with nonalcoholic liver disease. These results show that in alcoholic liver disease hepatic fibrosis is characterized histochemically by the reduced response of fat-storing cells to the gold chloride reaction. The role of the change in fat-storing cells in alcoholic liver disease remains to be elucidated.     

A genotypic association implicates myeloperoxidase in the progression of hepatic fibrosis in chronic hepatitis C virus infection

The hepatitis C virus (HCV) is a major cause of liver disease and the complications of cirrhosis. Liver biopsies, performed prior to the development of liver cirrhosis, characteristically show an inflammatory cell infiltrate with varying degrees of fibrosis. Precisely how HCV infection induces hepatic fibrogenesis is unknown. Recent studies suggest the release of oxidants, cytokines and proteases from the host immune system are key to the development of fibrosis. Macrophages and neutrophils, cells heavily represented in the inflammatory cell response, contain the oxidant generating enzyme myeloperoxidase (MPO). Cellular levels of MPO can be influenced by a functional promotor polymorphism, -463G/A, which precedes the MPO gene. We examined the relationship between this MPO promotor genotype and the degree of fibrosis in 166 patients with chronic HCV infection. All patients had previously participated in clinical drug trials for the treatment of chronic HCV infection. The MPO genotype was determined from cryo-preserved lymphocytes obtained from patients prior to treatment. The degree of fibrosis was estimated from liver biopsy specimens obtained prior to treatment. We found that patients with the MPO GA/AA genotype were more likely to have advanced fibrosis scores compared with those with the GG genotype: Of the patients with GG genotype, 78% (79 of 102 cases) had lower Knodell Fibrosis scores of 0 or 1, compared to 56% (37 of 64 cases) of patients with GA/AA genotype (P < 0.05). The mechanism(s) by which MPO contributes to fibrosis progression remains to be determined.     

Liver morphology and function in visceral leishmaniasis (Kala-azar).

AIM--To study the morphology and function of the liver in visceral leishmaniasis (Kala-azar). METHODS--Percutaneous liver biopsy specimens from 18 patients with confirmed visceral leishmaniasis were examined under light and electron microscopy before and after treatment with pentovalent antimony. The tissue was also examined for hepatitis B surface and core antigens using immunoperoxidase staining. Liver function was investigated in nine patients before and after treatment. RESULTS--Specimens before treatment showed Kupffer cells and macrophages colonised by leishmania parasites in 40% of cases. A chronic mononuclear cell infiltrate had affected the portal tracts and lobules. Ballooning degeneration of the hepatocytes, fibrosis of the terminal hepatic venules, and pericellular fibrosis were common findings. The fibrosis was related to Ito cells transforming to fibroblast-like cells. None of the patients had hepatitis B infection. All patients had biochemical evidence of liver dysfunction before treatment. Liver function improved after treatment. CONCLUSION--Visceral leishmaniasis causes morphological and functional disturbance in the liver. Focal fibrosis rather than cirrhosis occurs. The exact aetiology of hepatic damage is unclear but may have an immunological basis.     

Liver fibrogenesis: a new role for the renin-angiotensin system

Liver fibrosis is the consequence of chronic liver injury of any etiology. When advanced, fibrosis causes portal hypertension and liver insufficiency, and is a risk factor for developing hepatocellular carcinoma. In the last decade, there have been major advances in the knowledge of the pathogenesis of hepatic fibrosis. Hepatic stellate cells (HSCs) are recognized as the main collagen-producing cells in the injured liver, and key fibrogenic factors have been identified. Among these factors, the renin-angiotensin system (RAS) appears to play a major role. Angiotensin II (Ang II) mediates key biological actions involved in hepatic tissue repair, including myofibroblast proliferation, infiltration of inflammatory cells, and collagen synthesis. Activated HSCs secrete Ang II, which induces fibrogenic actions through the activation of NADPH oxidase. Importantly, the blockade of the RAS attenuates fibrosis development in different experimental models of chronic liver injury. Based on these studies, it has been proposed that the blockade of the RAS could be effective in preventing fibrosis progression in chronic liver diseases. Although no prospective studies have evaluated the antifibrotic effect of RAS inhibitors in patients with chronic liver diseases, controlled clinical trials are under way.     

Immunological basis of stem cell therapy in liver diseases

Unbalanced immune cell populations or immune cell infiltration of the liver can disrupt the immune-privileged state of the liver, resulting in liver injury or fibrosis. Therefore, the treatment for liver diseases involves not only hepatic regeneration but also immunological regulation. Recent studies demonstrated that stem cells, especially mesenchymal stem cells, have the capacity for not only hepatic differentiation but also immunomodulation. In this respect, stem cell therapy could be a realistic aim for liver diseases by modulating the liver regenerative processes and down-regulating immune-mediated liver damage. In this review, we discuss in detail the importance of immune cells in liver injury and repair; the mechanism by which stem cells demonstrate an immune-tolerant phenotype that can be used for allogeneic transplantation; the effect of stem cell transplantation on immune-mediated diseases, especially liver diseases; and the mechanism by which stem cells improve the hepatic microenvironment.     

脐带源间充质干细胞移植治疗肝纤维化及肝硬化的相关机制

背景：肝硬化是多种原因引起的肝脏慢性病变,目前尚没有有效的治疗方法,很多研究表明,间充质干细胞对肝纤维化及肝硬化有一定的治疗作用。 目的：研究人脐带源间充质干细胞移植对大鼠肝纤维化及肝硬化的治疗作用及其作用机制。 方法：应用CCl4诱导制备肝纤维化及肝硬化模型,造模后经尾静脉注射人脐带间充质干细胞。细胞移植后采用Beckman Coulter analyzer检测人脐带源间充质干细胞移植对大鼠肝功能的影响;采用天狼猩红染色检测肝组织病理改变;应用免疫组织化学染色、Western blot和real-time Q-PCR方法检测Ⅰ、Ⅲ型胶原、基质金属蛋白酶2、基质金属蛋白酶抑制剂2蛋白与mRNA在大鼠肝组织中的表达。 结果与结论：人脐带源间充质干细胞移植可以改善肝纤维化及肝硬化大鼠的肝功能。人脐带源间充质干细胞移植后,除肝纤维化细胞移植1周组与对应模型组相比差异无显著性意义外,其余各细胞移植组肝脏组织中基质金属蛋白酶2 mRNA及蛋白表达水平明显升高,而Ⅰ、Ⅲ型胶原、基质金属蛋白酶抑制剂2表达水平明显降低。人脐带源间充质干细胞通过上调基质金属蛋白酶2表达,下调基质金属蛋白酶抑制剂2表达,对肝纤维化及肝硬化起到治疗作用;在致病因素持续存在的情况下,人脐带源间充质干细胞移植并不能逆转肝纤维化或者肝硬化,只能延缓肝纤维化或肝硬化的进程。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Immune modulation of ovalbumin-induced lung injury in mice using β-glucosylceramide and a potential role of the liver

CD1d-restricted natural killer T (NKT) cells are implicated in the pathogenesis of asthma. β-Glucosylceramide (GC), a naturally occurring lipid, was previously shown to alter NKT cell distribution in the liver. We hypothesized that GC can affect lung and liver NKT cell distribution and ameliorate asthma. Mice were sensitized by intra-peritoneal injection of ovalbumin (OVA) for 2 weeks followed by repeated intranasal OVA challenges to induce lung injury mimicking asthma. OVA induced asthma groups were either treated by intranasal instillation of normal saline, intranasal instillation of GC or inhaled budesonide. To investigate the role of the liver, hepatic fibrosis was induced using carbon tetrachloride prior to asthma induction. Allergen induced bronchoconstriction was measured prior to sacrifice. Isolated lymphocytes from lungs, livers and spleens were analyzed for OVA induced proliferation and flow cytometry. Liver and lung histology, serum aminotransferase and anti-OVA antibodies level were assessed. Treatment with GC significantly reduced OVA induced airway responsiveness (p < 0.001) similar to inhaled budesonide. GC significantly reduced the peri-bronchial and peri-vascular inflammatory infiltration mainly through an effect on T cells, as suggested by decreased T cell proliferation (p = 0.009). Liver CD4 and NKT cells significantly increased after GC treatment suggesting liver involvement. Inducing hepatic fibrosis blunted the propagation of asthma in spite of sufficient increase of serum anti-OVA titers. GC has an immunomodulatory effect on a murine model of experimental asthma. We also suggest that the liver acts as an immunomodulatory organ and might have a regulatory effect on pulmonary diseases.     

The Anti-Fibrotic Effect of Bone Morphogenic Protein-7(BMP-7) on Liver Fibrosis

Background/Aims: Transforming growth factor-β₁ (TGF-β₁) plays an important role in the pathogenesis of liver fibrosis and cirrhosis. Recombinant human bone morphogenic protein-7 (rhBMP-7) alleviates renal fibrosis and improves kidney function. However, the beneficial effect of BMP-7 on hepatic fibrosis and cirrhosis remains unknown. The purpose of this study was to investigate the prophylactic and therapeutic effects of rhBMP-7 on liver fibrosis and the underlying mechanisms.Methods: Liver fibrosis in the rat model was induced by peritoneal injection of porcine-serum (0.5ml/kg body weight) twice a week over 8 weeks. The effect of rhBMP-7 on hepatic fibrosis was monitored in rhBMP-7 pre-treated and non-treated rats. Pathologic changes were determined by immunohistolocial staining. TGF-β₁ expression was investigated by immunohistolocial staining, western blotting, and real-time PCR. Collagen secretion was measured by enzyme-linked immunosorbent assay.Results: Liver fibrosis was significantly reduced by rhBMP-7. The secretion of collagen type-I and -III was decreased by rhBMP-7 in hepatic stellate cells (HSCs) but not in hepatocytes. The anti-fibrotic effect of rhBMP-7 on liver fibrosis was resulted by blocking the nuclear accumulation of Smad2/3 or by inhibiting TGF-β₁ expression in HSCs or hepatocytes.Conclusions: The anti-fibrogenic mechanism of rhBMP-7 in the rat liver fibrosis was depended on the reduction of TGF-β₁ overexpression and the inhibition of TGF-β₁ triggered intracellular signalling in hepatic cells.