瘦素促进大鼠肝星状细胞活化及其细胞外信号调节激酶磷酸化

近年研究发现，瘦素在肝纤维化病理形成中具有重要意义，可促进实验性动物肝脏炎症与纤维化病理发展。但是瘦素是否直接促进肝纤维化形成的关键细胞——肝星状细胞（HSC）活化尚不清楚。本实验采用大鼠HSCT6细胞株，观察不同浓度的瘦素对HSC-T6增殖、α-平滑肌肌动蛋白（α-SMA）与Ⅰ型胶原蛋白表达的作用．及其对细胞外信号调节激酶（ERK）磷酸化的影响．探讨瘦素对HSC活化的影响与部分作用机制。     

肝星状细胞的活化与肝纤维化

肝纤维化是机体对损伤的一种修复作用，即使可以应用基因或其他疗法彻底消除纤维化，但机体对抑制或消除纤维化后将产生何种反应及后果尚难预测。肝星状细胞（hepatic stellate cells，HSC）是引起肝纤维化的主要细胞，对HSC与其活化型一肌成纤维细胞（myofibroblast，MF）在肝损伤中作用的研究已颇为深入，而HSC激活在肝纤维化发生、发展中的作用甚为重要。     

外源性转化生长因子β1对大鼠原代肝星状细胞活化的影响

目的探讨大鼠原代肝星状细胞(HSC)体外培养过程中,不同时期外源性转化生长因子β1(TGF-β1)对其活化的影响及相关因素的变化.方法分离大鼠原代HSC,于无包被的塑料培养板上分别培养2,3,4,5,6,7 d时予TGF-β15 μg/L处理24 h,倒置显微镜下观察细胞的形态变化,应用Western blot法检测处理前后细胞α-肌动蛋白(α-SMA)的变化,及活化过程中TGF-β1Ⅱ型受体(TβR-Ⅱ)的表达.结果HSC在体外培养过程中,不同培养时间对TGF-β1的刺激活化作用反应不同.TGF-β1处理后,对培养2,3,4,5 d HSC的活化有促进作用,以对培养第3天的细胞作用最明显,其α-SMA表达增加78.05%,而培养6,7 d的HSC的形态和α-SMA变化不明显.培养第7天的HSC比培养第3天的细胞TβR-Ⅱ表达增高(3.30±0.83 vs 1.55±0.38,P＜0.05).结论TGF-β1对处部分活化状态中某阶段细胞的活化具有促进作用.完全活化的细胞对TGF-β1的刺激活化作用不敏感,原因与TβR-Ⅱ的表达量无关.     

抗纤二号药物血清对活化型肝星状细胞的影响

为了解抗纤二号的抗肝纤维化作用机制，采用动物体内给药，分离药物血清，作用于体外培养细胞的血清药理学实验方法，探讨该方对肝星状细胞（HSC）激活的标志平滑肌肌动蛋白（smooth muscle actin，SMA）表达的影响及Ⅰ、Ⅲ型胶原和转化生长因子β1（TGFβ1）及其下游信号Smad 3表达的影响，从细胞分子学水平探讨该方抗肝纤维化的作用机制。     

瘦素与肝纤维化

瘦素(leptin)是由ob基因(位于人类染色体7q31.3)编码的一种肽类激素,通过多种形式的瘦素受体(obese gene receptor,OB-R),作用于中枢和外周的多个位点,影响机体许多生理系统及代谢通路.自1998年Potter发现活化的肝星状细胞表达瘦素后,人们开始关注瘦素与肝脏疾病的关系.近年研究发现,瘦素与肝纤维化的发生有密切关系,而且与肝纤维化分级相关[1～5].     

瘦素与肝纤维化

瘦素是肥胖基因(ob基因)的编码产物,通过与其受体结合在体内发挥多种生物学作用,调节摄食、能量代谢、生殖、造血、免疫等生理功能.参与炎性反应、损伤修复等病理生理过程.肝纤维化是多种原因所致慢性肝损伤的修复反应,是各种慢性肝病共同的病理基础.研究发现瘦素与肝纤维化的发生发展有一定的关系,本文就此作一综述.     

熊果酸对肝纤维化大鼠肝组织TGF-β1和α-SMA表达的

织TGF-β1基因与蛋白及α平滑肌肌动蛋白(α-SMA)表达的影响, 并探讨其抗肝纤维化作用机制.方法: SD大鼠96只随机分为正常对照组(N组)、模型组(M组)、UA低剂量组(U1组)、UA中剂量组(U2组)、UA高剂量组(U3组)及秋水仙碱组(C组), 每组16只. 除N组外, 均用二甲基亚硝胺(Dimethylnitrosamine, DMN)诱导肝纤维化4 wk, 分别给予安慰剂、不同剂量的UA、秋水仙碱腹腔注射, 治疗4 wk处死大鼠,取肝组织行病理HE染色及VG染色判断炎症和肝纤维化程度; 分别采用免疫组织化学和Western blot检测TGF-β1蛋白和α-SMA蛋白的表达; 采用RT-PCR检测TGF-β1 mRNA的表达.结果: U2和U3组肝细胞坏死和纤维组织增生明显减轻; M组TGF-β1蛋白、TGF-β1 mRNA及α-SMA蛋白较N组的表达明显增加(8.76±1.47 vs 1.48±0.24; 0.60±0.11 vs 0.05±0.02;0.51±0.10 vs 0.09±0.02, 均P<0.01). U1组和C组TGF-β1蛋白的表达较M组降低( P<0.05),U2和U3组TGF-β1蛋白的表达较M组明显降低(5.32±1.63, 3.98±0.67 vs 8.76±1.47,均P<0.01), 且低于C组的表达(7.14±1.29,P<0.05或0.01). U2和U3组的TGF-β1 mRNA的表达也明显低于M组(0.36±0.07, 0.25±0.06 vs 0.60±0.11, 均P<0.01)和C组(0.47±0.10, P<0.05或0.01). U1-U3组较M组α-SMA蛋白的表达明显降低(0.36±0.08, 0.23±0.02,0.15±0.03 vs 0.51±0.10, 均P<0.01); U2和U3组α-SMA蛋白的表达也显著低于C组(0.43±0.05, 均P<0.01).结论: UA能明显改善肝纤维化大鼠的肝脏组织结构, 减轻肝纤维化; 其抗肝纤维化的机制可能与降低TGF-β1表达, 抑制HSC的激活有关.     

瘦素在肝纤维化形成中的作用与地位

瘦素,ob基因产物,是相对分子质量为16 000的蛋白,主要由白脂肪产生并分泌.瘦素在肝纤维化进程中具有促纤维化作用.瘦素增加Ⅰ型前胶原的表达和转化生长因子(TGF-β)的作用,上调金属蛋白酶组织抑制因子-1(TIMP-1)的表达,减少基质金属蛋白酶-1(MMP-1)的形成,减少产生纤维的细胞外基质(ECM)的降解,最终产生促纤维化作用.     

肝星状细胞在肝纤维化中的作用

肝纤维化是肝硬化的早期阶段,其发生涉及肝内多种细胞,而肝星状细胞在肝纤维化的发生发展中具有重要作用,本文综合国内外最新研究,对肝星状细胞的形态及其在肝纤维化中的作用(活化、信号转导、凋亡等)进行了综述。     

瘦素对乙醛诱导肝星状细胞活化过程中Ⅰ型胶原及α-平滑肌肌动蛋白表达的影响

目的:观察瘦素对乙醛诱导肝星状细胞(HSC)活化过程中α-SMA和I型胶原表达的影响,旨在从体外探讨瘦素在酒精性肝病中的可能作用。方法:采用SD大鼠肝脏原位灌流消化的方法获得并原代及传代培养HSC,分乙醛(200μmol/L)处理组,瘦素(100nmol/L)处理组及联合处理组(乙醛200μmol/L加瘦素100nmol/L)。用实时荧光定量PCR方法检测各组细胞TGF-β1、Ⅰ型胶原及α-SMA(α-平滑肌肌动蛋白)mRNA表达水平,Western blot检测各组细胞α-SMA表达量,ELISA法检测培养上清中TGF-β1及Ⅰ型胶原含量。结果:①乙醛处理组中TGF-β1和Ⅰ型胶原基因及蛋白表达量明显高于空白对照组(P<0.05),α-SMA表达量与对照组相比差异无显著性意义(P>0.05);②瘦素处理组TGF-β1、Ⅰ型胶原及α-SMA表达量与对照组相比差异无显著性意义(P>0.05);③联合处理组TGF-β1、Ⅰ型胶原及α-SMA表达量明显高于对照组(P<0.05),但TGF-β1、Ⅰ型胶原表达量与乙醛处理组相比差异无显著性意义(P>0.05)。结论:在乙醛诱导肝星状细胞活化过程中,瘦素能协同上调α-SMA的表达;但对TGF-β1及Ⅰ型胶原的表达无影响,Ⅰ型胶原和α-SMA的表达可能是依赖于不同的调控机制来实现。     

Hedgehog通路与肝纤维化及肝星状细胞活化的关系研究

目的:探讨Hedgehog通路与肝纤维化及肝星状细胞(HSC)活化的关系.方法:清洁级SD雄性大鼠20只,均分为模型组和对照组.模型组采用腹腔注射四氯化碳(CCl4)和高脂饮食诱导肝纤维化,对照组予以正常饮食.第8周末取模型组存活大鼠与对照组中大鼠各5只处死,取左叶肝脏组织.HE、Masson染色观察两组肝组织病理变化;逆转录-多聚酶链反应(RT-PCR)检测纤维化大鼠肝脏中表达Hedgehog通路成员超音速Hedgehog信号通路(Shh)、膜受体patched(Ptc)、smoothened(Smo)和核转录因子Gli表达;实时荧光定量PCR法检测Hedgehog通路成员及HSC活化标志基因α-平滑肌肌动蛋白(α-SMA)mRNA在两组大鼠肝脏中的表达差异.体外培养HSC-T6细胞,RT-PCR检测HSC-T6细胞株中Hedgehog通路成员的表达;四甲基偶氮唑盐比色分析(MTT)法检测不同浓度环耙明(Cyclopamine,Cyc)对HSC-T6增殖的影响;分别用0、100/μmol/L的Cye干预HSC-T6,实时荧光定量PCR法检测Shh、Smo、Ptc、Gli-1及αSMA mRNA表达差异.结果:模型组大鼠肝脏有大量脂质及胶原沉积,且肝脏组织中均有Shh、Smo、Ptc、Gli-1表达.荧光定量PCR结果示模型组大鼠Shh、Smo、Gli-1及αSMA mRNA表达均较对照大鼠升高(20.45±3.31、12.78±0.53、10.88±2.41、4.91±2.59比1;P值均<0.05).Cyc在体外对HSC-T6有明显的抑制作用,且抑制作用呈剂量依赖性(F=636.81,P<0.01).荧光定量PCR结果示,用Cyc 100 μmol/L干预的HSC-T6中,Ptc、Smo、Gli-1和αSMA表达量分别为0.20±0.11、0.21±0.08、0.28±0.05和0.27±0.10,与Cyc 0μmol/L干预比较差异均有统计学意义(P值均<0.01).结论:肝纤维化过程中Hedgehog通路成员表达增高,抑制Hedgehog通路可抑制HSC活化,推测Hedgehog通路通过活化HSC促进肝纤维化的发生.     

Roles of kupffer cell polarization and hepatic stellate cell activation in hepatic inflammation and fibrosis in NAFLD

正Objective To investigate the roles of Kupffer cell polarization and HSC activation in the development of hepatic inflammation and fibrosis in progression of non-alcoholic fatty liver disease(NAFLD).Methods C57BL/6 mice were fed with high fat(HF)diet and methioninecholine-deficient(MCD)diet to induce experimental non-alcoholic fatty liver(NAFL)and non-alcoholic     

高血糖对大鼠肝纤维化及肝星状细胞活化的影响

目的探讨高血糖对大鼠肝纤维化及肝星状细胞活化的影响。方法取大鼠66只,随机分为4组,A组和B组均采用STZ(链脲佐菌素)和CCl4(四氯化碳)诱导为肝纤维化并糖尿病模型。A组诱导成功不做处理。B组糖尿病诊断成立后,皮下注射门冬胰岛素,3次/d控制血糖。C组单纯利用CCl4(四氯化碳分析纯)诱导为肝纤维化模型。D组(空白对照组)常规喂养,不做处理。观察各组大鼠一般情况(包括鼠食消耗、毛发变化、活动指数),8周后处死,测量大鼠体质量、肝脏体积及重量,采集血液及肝脏标本,分析对比各组大鼠肝脏系数,HE染色后光镜下肝组织纤维化情况;免疫组化SP法检测肝组织内α-SMA表达。结果实验各组与对照组大鼠相比体质量明显减轻(P<0.05),肝脏系数明显增加(P<0.05),肝组织α-SMA表达均不同程度增强(P<0.05);其中A组的体质量减轻最明显,肝纤维化、肝脏系数增加最显著(P<0.05),肝组织α-SMA表达亦有显著性差异(P<0.05);B组与C组相比体质量无明显减轻(P>0.05),肝脏系数无明显增加(P>0.05),而肝组织α-SMA表达差异有统计学意义(P<0.05)。结论高血糖可促进大鼠肝纤维化形成及肝星状细胞的活化。     

Induction of tropomyosin during hepatic stellate cell activation and the progression of liver fibrosis

The activation of hepatic stellate cells (HSCs) is a cue to initiate liver fibrosis. Activated stellate cells acquire contractile activity similar to pericytes and myofibroblasts in other organs by inducing the contractile machinery of cytoskeletons such as smooth muscle α-actin (α-SMA), a well-known marker of activated stellate cells, and actin-binding proteins. We further show herein the expression of tropomyosin in rat HSCs in the course of their activation during primary culture and liver tissue damaged by thioacetamide intoxication. In immunoblot analysis, tropomyosin became detectable in an early stage of the primary culture of rat stellate cells in a manner similar to the expression of α-SMA and platelet-derived growth factor receptor-β. Tropomyosin was found to be colocalized with α-SMA on fluorescent immunocytochemistry. At the liver tissue level, an increased expression of tropomyosin was observed by immunoblot analysis and immunohistochemistry along the septum of fibrosis, where α-SMA was enriched. These results strongly suggest that tropomyosin is a new marker of activated stellate cells and may serve as a useful diagnostic marker of liver fibrosis.     

Expression of bcl-2 in ductular proliferation is related to periportal hepatic stellate cell activation and fibrosis progression in patients with autoimmune cholestasis

AIM: To study bcl-2 expression in ductular proliferation cholangiocytes and hepatic stellate cell activation in liver biopsies from patients with autoimmune cholangitis and primary biliary cirrhosis. MATERIALS AND METHODS: Twenty-four primary biliary cirrhosis patients and 11 autoimmune cholangitis patients were included. Thirty-four females, average age: 52.5+/-12.6 years. We studied the presence of ductular proliferation, cholestasis, florid ductal lesion, granulomata, ductopenia and histologic stage. Patients were classified in primary biliary cirrhosis or autoimmune cholangitis according to antimitochondrial antibodies, antinuclear antibodies, smooth muscle antibody, antiGP210 and antiSP100 autoantibodies. We studied the presence of bcl-2 by monoclonal antibcl-2 antibody (clon 100, BioGenex). The presence of activated (specific antialpha-actin antibodies) and independent lobular, periportal and portal hepatic stellate cell was assessed using a semiquantitative scale. RESULTS: Interlobular ducts bcl-2 was seen in 18 (51.4%) patients. Activated periportal hepatic stellate cell correlated with Ludwig's stage (r=0.43; n=35; p=0.01). Ten out of 15 (66.6%) patients with ductular proliferation showed positive interlobular ducts bcl-2 while bcl-2 was negative in 8 out of 20 (40%) patients without ductular proliferation; p<0.05. Bcl-2 positive patients in ductular proliferation showed a more advanced Ludwig's stage (2.33+/-0.77 versus 1.26+/-1.05; p<0.05) and a higher periportal hepatic stellate cell activation index (0.83+/-0.78 versus 0.23+/-0.43; p=0.009). No relationship was found among periportal hepatic stellate cell activation and the presence of florid ductal lesion, cholestasis, granulomata or biliary erosive necrosis. Hepatic stellate cell activation was similar in patients with either autoimmune cholangitis or primary biliary cirrhosis. CONCLUSIONS: Periportal hepatic stellate cell activation seems to play a main role in fibrosis progression in patients with autoimmune cholestasis. Bcl-2 expression in ductular proliferation may promote hepatic stellate cell activation and fibrosis.     

Interferon gamma decreases hepatic stellate cell activation and extracellular matrix deposition in rat liver fibrosis

Interferon gamma (IFN-gamma) inhibits in vitro the activation of hepatic stellate cells (HSC), the primary extracellular matrix-producing cells in liver fibrosis. This study was undertaken to determine in vivo the effect of IFN-gamma in the rat model of liver fibrosis induced by dimethylnitrosamine (DMN), where HSC activation represents an early response to cell injury. Rats were killed after 1 or 3 weeks of treatment with DMN, IFN-gamma, DMN + IFN-gamma, or saline. Immunohistochemistry was used to identify proliferating (desmin- positive/bromodeoxyuridine (BrdU)-positive cells) and activated (alpha- smooth-muscle actin [alpha-SMA]-positive cells) HSCs. Collagen deposition was determined colorimetrically and by morphometry. The parenchymal extension of desmin- and actin-positive cells and of fibrotic tissue was measured by point-counting technique and expressed as a percentage of area. Western blot was used to determine laminin and fibronectin accumulation. The levels of messenger RNA (mRNA) for procollagen type I, fibronectin, and laminin were evaluated by Northern blot. No differences were observed in rats treated with either saline or IFN-gamma alone. IFN-gamma reduced HSC activation induced by liver injury, as shown by the decreased number of proliferating HSC and the reduction of parenchymal area occupied by alpha-SMA-positive cells observed in DMN + IFN-gamma-treated animals compared with the DMN group. This was associated with reduced collagen, laminin, and fibronectin accumulation and lower levels of mRNA for procollagen type I, fibronectin, and laminin in the DMN + IFN-gamma group. Thus, this study indicates that IFN-gamma reduces extracellular matrix deposition in vivo by inhibition of HSC activation. (Hepatology 1996 May;23(5):1189-99)