Cholangiocyte endothelin 1 and transforming growth factor beta1 production in rat experimental hepatopulmonary syndrome

BACKGROUND & AIMS: Hepatic production and release of endothelin 1 plays a central role in experimental hepatopulmonary syndrome after common bile duct ligation by stimulating pulmonary endothelial nitric oxide production. In thioacetamide-induced nonbiliary cirrhosis, hepatic endothelin 1 production and release do not occur, and hepatopulmonary syndrome does not develop. However, the source and regulation of hepatic endothelin 1 after common bile duct ligation are not fully characterized. We evaluated the sources of hepatic endothelin 1 production after common bile duct ligation in relation to thioacetamide cirrhosis and assessed whether transforming growth factor beta1 regulates endothelin 1 production. METHODS: Hepatopulmonary syndrome and hepatic and plasma endothelin 1 levels were evaluated after common bile duct ligation or thioacetamide administration. Cellular sources of endothelin 1 were assessed by immunohistochemistry and laser capture microdissection of cholangiocytes. Transforming growth factor beta1 expression and signaling were assessed by using immunohistochemistry and Western blotting and by evaluating normal rat cholangiocytes. RESULTS: Hepatic and plasma endothelin 1 levels increased and hepatopulmonary syndrome developed only after common bile duct ligation. Hepatic endothelin 1 and transforming growth factor beta1 levels increased over a similar time frame, and cholangiocytes were a major source of each peptide. Transforming growth factor beta1 signaling in cholangiocytes in vivo was evident by increased phosphorylation and nuclear localization of Smad2, and hepatic endothelin 1 levels correlated directly with liver transforming growth factor beta1 and phosphorylated Smad2 levels. Transforming growth factor beta1 also stimulated endothelin 1 promoter activity, expression, and production in normal rat cholangiocytes. CONCLUSIONS: Cholangiocytes are a major source of hepatic endothelin 1 production during the development of hepatopulmonary syndrome after common bile duct ligation, but not in thioacetamide-induced cirrhosis. Transforming growth factor beta1 stimulates cholangiocyte endothelin 1 expression and production. Cholangiocyte-derived endothelin 1 may be an important endocrine mediator of experimental hepatopulmonary syndrome.     

细胞毒性T细胞穿入现象在原发性胆汁性胆管炎中的表现及意义*

目的:研究原发性胆汁性胆管炎(primary biliary cholangitis,PBC)中发生CD8+细胞毒性T细胞(cytotoxic T lymphocyte,CTL)穿入现象及其意义。方法:收集53例PBC患者肝穿刺标本,采用H&E染色和免疫荧光染色方法,在光学显微镜和激光共聚焦显微镜下观察PBC肝组织中CTL的穿入及穿入宿主细胞的类型,并分析与病程的关系。结果:53例PBC患者中10例(18.9%)发生淋巴细胞穿入肝细胞,15例(28.3%)发生淋巴细胞穿入胆管上皮,仅1例患者同时存在淋巴细胞穿入肝细胞和胆管上皮细胞。免疫荧光染色证实穿入的淋巴细胞是CD8阳性细胞毒性T细胞(CTL)。早期PBC患者中4例(22.2%)、晚期PBC患者中6例(17.1%)发生CTL穿入肝细胞,两组差异无统计学意义(P>0.05)。早期PBC患者中9例(50.0%)、晚期PBC患者中6例(17.1%)发生CTL穿入胆管上皮,两组差异有统计学意义(Z=2.52,P<0.05)。结论:在PBC肝组织中,CTL可穿入肝细胞和胆管上皮细胞,CTL穿入胆管上皮细胞并导致其发生凋亡可能是PBC发病过程中胆管损伤的机制之一。     

Effector role of neonatal hepatic CD8+ lymphocytes in epithelial injury and autoimmunity in experimental biliary atresia

BACKGROUND & AIMS: Lymphocytes populate the livers of infants with biliary atresia, but it is unknown whether neonatal lymphocytes regulate pathogenesis of disease. Here, we investigate this question by examining the role of T lymphocytes in the destruction of extrahepatic bile ducts of neonatal mice using an experimental model of biliary atresia. METHODS: Inoculation of neonatal mice with rhesus rotavirus followed by multistaining flow cytometry to quantify expression of interferon-gamma by hepatic lymphocytes, and real-time polymerase chain reaction for mRNA expression of pro-inflammatory cytokines. This was followed by determining the consequences of antibody-mediated depletion of lymphocyte subtypes on the development of biliary obstruction, and coculture and cell transfer experiments to investigate the effector role of lymphocyte subtypes on neonatal biliary disease. RESULTS: Rotavirus infection results in overexpression of interferon-gamma by neonatal hepatic T cells. Among these cells, depletion of CD4(+) cells did not change the course of inflammatory injury and obstruction of neonatal bile ducts. In contrast, loss of CD8(+) cells remarkably suppressed duct injury, prevented luminal obstruction, and restored bile flow. Coculture experiments showed that rotavirus-primed, but not na?ve, CD8(+) cells were cytotoxic to cholangiocytes. In adoptive transfer experiments, we found that primed CD8(+) cells preferentially homed to extrahepatic bile ducts of neonatal mice and invaded their epithelial lining. CONCLUSIONS: Primed neonatal CD8(+) cells can activate a pro-inflammatory program, target diseased and healthy duct epithelium, and drive the phenotypic expression of biliary atresia, thus constituting a potential therapeutic target to halt disease progression.     

5-羟色胺在胆管上皮细胞与门管成纤维细胞自分泌／旁分泌中的作用

目的探讨5-羟色胺（5_hydmxytryptamine,5-HT）在胆管上皮细胞（biliary epithelia cells,BECs）与门管区成纤维细胞（portal fibroblasts,PFs）之间自分泌／旁分泌效应中的意义,阐述两种细胞之间的相互作用。方法体外细胞培养分为6组：1）BECs组单独培养;2）BECs＋TGF—β1组,BECs单独培养,用2ng／ml重组TGF—β1干预24h后更换培养液;3）BECs＋5-HT组,BECs单独培养,以60ng／ml的5-HT干预48h后更换培养液;4）PFs组单独培养;5）PFs＋5-HT组,PFs单独培养,以60ng／ml的5-HT干预48h后更换培养液;6）BECs＋PFs,共同培养。各组均在培养72h后,以酶联免疫吸附分析法（ELISA）检测培养介质内5-HT、TGF—β1含量;实时荧光定量多聚酶链反应（QRT—PCR）检测BECs内色氨酸羟化酶（TPHl、TPH2）和5-HT受体1A、1B表达;以BrdU、α—SMA分别作为BECs增殖及PFs转化为肌纤维母细胞（myofibroblasts,MFs）的标志,免疫细胞化学检测。结果单独培养的BECs表达5-HT合成限速酶TPH1、TPH2及5-HTRIA、5-HTR1B,5-HT分泌较高而BECs增殖不明显;经TGF—β1处理或与PFs共培养后,TPH1、TPH2表达各减少80％和87％,5-HTR1A、5-HTR1B表达分别减少75％和85％,BECs增殖明显。单独培养的PFs分泌TGF—β1,部分呈α—SMA阳性的MFs;经5-HT处理或与BECs共培养后,TGF—β1表达及MFs显著增加。结论BECs来源的5-HT以及PFs来源的TGF—β1介导BECs与PFs之间的自分泌与旁分泌效应,维持BECs增殖和PFs向MFs的转化,在胆管病发病机制中可能具有重要意义。     

Bile duct proliferation associated with bile salt-induced hypercholeresis in Mdr2 P-glycoprotein-deficient mice.

BACKGROUND/AIMS: Bile flow consists of bile salt-dependent bile flow (BSDF), generated by canalicular secretion of bile salts, and bile salt-independent flow (BSIF), probably of combined canalicular and ductular origin. Bile salt transport proteins have been identified in cholangiocytes, suggesting a role in control of BSDF and/or in control of bile salt synthesis through cholehepatic shunting. METHODS: We studied effects of bile duct proliferation under non-cholestatic conditions in multidrug resistance-2 P-glycoprotein (Abcb4)-deficient multidrug resistance gene-2 (Mdr2(-/-)) mice. BSDF and BSIF were determined in wild-type and Mdr2(-/-) mice during infusion of step-wise increasing dosages of tauroursodeoxycholate (TUDC). Cholate synthesis rate was determined by 2H4-cholate dilution. Results were related to expression of transport proteins in liver and intestine. RESULTS: During TUDC infusion, BSDF was increased by approximately 50% and BSIF by approximately 100% in Mdr2(-/-) mice compared with controls. Cholate synthesis rate was unaffected in Mdr2(-/-) mice. Hepatic expression of the apical sodium-dependent bile salt transporter (Asbt), its truncated form (tAsbt) and the multidrug resistance-related protein 3 were upregulated in Mdr2(-/-) mice. CONCLUSIONS: Bile duct proliferation in Mdr2(-/-) mice enhances cholehepatic shunting of bile salts, which is associated with a disproportionally high bile flow but does not affect bile salt synthesis.     

Hes1基因诱导小鼠肝原始细胞分化为胆管上皮细胞

背景与目的： 采用体外获得性表达外源发状分裂相关增强子-1(hairy and enhancer of split 1,Hes1)基因的方法,探讨Hes1在肝干细胞分化以及胆管上皮细胞发育中的作用。 材料与方法： 通过PCR方法从小鼠基因组中克隆Hes1基因片段,构建表达载体pEGFP-C1-Hes1和pcDNA3.1- Hes1,将2种表达载体分别转染肝原始细胞系(LEPCs) ,应用RT-PCR和Real-time PCR技术检测胆管细胞分子标志物CK19、GGT,胆管上皮细胞相关转录因子HNF6、HNF1β,肝细胞分子标志物GS、BGP和肝卵圆细胞的分子标志物Thy-1的表达,并在荧光显微镜下观察EGFP标记的LEPCs细胞系荧光强度的变化。结果：成功构建表达载体pEGFP-C1- Hes1和pcDNA3.1-Hes1。RT-PCR和Real-time PCR检测均表明胆管细胞分子标志CK19、GGT表达量上调;胆管上皮细胞相关转录因子HNF6、HNF1β表达上调;肝细胞分子标志GS、BGP表达量下调;卵圆细胞的分子标志Thy-1表达量下调;LEPCs细胞系绿色荧光增强。 结论： 初步证明小鼠肝原始细胞经Hes1的表达诱导后可向胆管上皮细胞方向分化,推测Hes1为胆管上皮细胞分化的转录调控因子。     

Integrating systematic pharmacology-based strategy and experimental validation to explore mechanism of Tripterygium glycoside on cholangiocyte-related liver injury

Objective: Tripterygium glycoside(TG) is widely used in clinical practice for its multiple bioactivities including anti-inflammatory and immunosuppressive effects. However, emerging studies have frequently reported TG-induced adverse reactions to multiple organs, especially liver. Here, this studyaimed to investigate the mechanism of liver damage induced by TG and explore representative components to reflect TG hepatotoxicity. Methods: Network pharmacology was used to determine the potential targets of bile duct injury caused by TG. Next, the hepatotoxic effects of TG, triptolide (TP) and celastrol (CEL) were investigated and compared in vivo and in vitro. Liver function was determined by measuring serum transaminase and histopathology staining. The cell proliferation and apoptosis were determined by cell viability assay, scratch assay and flow cytometry. The expression of gene of interest was determined by qPCR and Western blot. Results: Based on the network pharmacological analysis of 12 bioactive ingredients found in TG, a total of 35 targets and 15 pathways related to bile duct injury were obtained. Both TG and TP resulted in cholangiocyte damage and liver injury, as illustrated by increased levels of serum transaminase and oxidative stress, stimulated portal edema and lymphocytic infiltration and decreased expression of cholangiocyte marker, cytoskeletal 19. In addition, TG and TP inhibited cell proliferation and migration, arrested cell cycle and promoted Caspase-dependent apoptosis of cholangiocytes via suppressing the phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) and protein kinase B (AKT). While, CEL at equivalent dosage had no obvious hepatotoxicity. Conclusion: We revealed that TG-stimulated liver injury was specifically characterized by cholangiocyte damage and TP might be the decisive ingredient to reflect TG hepatotoxicity. Our results not only provide novel insights into the mechanism underlying the hepatotoxicity effects of TG but also offer reference for clinical rational use of TG.     

胆道闭锁胆管细胞破坏与修复的研究进展

摘要：胆道闭锁（BA）是一种由肝内外胆管系统堵塞引发的小儿肝胆外科疾病，如不及时治疗将引起胆汁性肝硬 化，最终发展为肝衰竭而导致患儿死亡。胆管上皮细胞破坏，胆管管腔逐渐狭窄，最终形成纤维条索是BA主要病理 改变。胆管上皮细胞不仅是被动受害者，也被认为是胆管病理学中潜在的效应物。目前，随着国内外对于BA胆管 上皮细胞的研究越来越深入，胆管上皮细胞破坏与修复方面取得了一些进展，本文就胆管结构改变、胆管上皮细胞 破坏、胆管增生与修复、上皮间质转化与肝纤维化的关系等方面作一综述。