雌激素对血液凝固与纤维蛋白溶解的影响及对心血管的保护作用

为了探讨雌激素促纤溶、抗凝血的心血管保护作用及其细胞和分子生物学机制,应用全自动血凝／纤溶分析仪和发色底物显色测定、组织和细胞原位杂交及激光共聚焦扫描显微镜等手术,观察去卵巢大鼠纤维蛋白原、组织型纤溶酶原激活物和纤溶酶原激活物抑制剂－１活性及基因表达,以及补充雌激素的影响。同时观察人脐静脉内皮细胞中雌激素对组织型纤溶酶原激活物和纤溶酶原激活物抑制剂－１活性及基因表达,以及被雌激素的影响。同时观察人     

肿瘤坏死因子α对人脐静脉内皮细胞纤溶酶原激活物抑制剂1表达及转录调控的影响

探讨肿瘤坏死因子α对人脐静脉内皮细胞纤溶酶原激活物抑制剂1活性和mRNA表达的影响，以及纤溶酶原激活物抑制剂1基因5’上游序列的调控元件在该基因转录调控中的作用。体外培养人脐静脉内皮细胞，加入不同浓度肿瘤坏死因子α作用不同时间。采用发色底物法测定纤溶酶原激活物抑制剂1活性。Northern印迹分析法测定纤溶酶原激活物抑制剂1 mRNA水平。基因重组技术构建四个含人纤溶酶原激活物抑制剂1基因不同长度5’上游序列的荧光素酶报告基因质粒，瞬时转染进入内皮细胞，并测定荧光素酶的表达情况。运用聚合酶链反应和序列分析法对构建质粒上的三个AP-元件分别进行定点突变。结果发现，不同浓度肿瘤坏死因子α作用人脐静脉内皮细胞后，纤溶酶原激活物抑制剂1活性和mRNA表达量均明显增高；当转染质粒含有纤溶酶原激活物抑制剂1基因上游序列-1509/ 90和-823／ 90时，肿瘤坏死因子α使转染细胞的荧光素酶表达量比对照组明显增高；当转染质粒含有-553／ 90和-47， 90时，肿瘤坏死因子α的诱导作用不明显。在纤溶酶原激活物抑制剂15’上游序列的三个AP-1元件突变后，肿瘤坏死因子α的诱导作用明显降低。结果提示，肿瘤坏死因子α增强血管内皮细胞纤溶酶原激活物抑制剂1活性与mRNA表达；纤溶酶原激活物抑制剂1活性提高与其mRNA表达增加呈正相关；纤溶酶原激活物抑制剂15’上游序列中三个AP-1元件在肿瘤坏死因子α对纤溶酶原激活物抑制剂1诱导中具有重要调控作用。     

山莨菪碱下行调节培养的内皮细胞表达纤溶酶原激活物抑制剂1

为了探讨山莨菪碱对正常及内毒素脂多糖刺激过的内皮细胞纤溶酶原激活物抑制剂 1表达的作用及机制。本文采用酶消化法培养人脐静脉内皮细胞 ;用酶联免疫吸附试验 (ELISA)方法检测人脐静脉内皮细胞条件培养基纤溶酶原激活物抑制剂 1和组织型纤溶酶原激活物蛋白量 ;用Northern印迹方法检测人脐静脉内皮细胞纤溶酶原激活物抑制剂 1的mRNA表达 ;用电泳迁移检测法对人脐静脉内皮细胞的核因子κB核内转移情况进行研究。结果发现 ,脂多糖能使人脐静脉内皮细胞纤溶酶原激活物抑制剂 1蛋白及mRNA表达显著增强 ,但加入山莨菪碱后 ,脂多糖的这种作用明显减弱。而且 ,山莨菪碱还能抑制人脐静脉内皮细胞纤溶酶原激活物抑制剂 1基础水平的表达。经脂多糖刺激的人脐静脉内皮细胞核提取物与核因子κB探针结合明显增强 ,而山莨菪碱则能阻止脂多糖致核因子κB的核内转移现象。提示山莨菪碱不仅下行调节脂多糖所致内皮细胞纤溶酶原激活物抑制剂 1的蛋白分泌和mRNA表达 ,而且下行调节其纤溶酶原激活物抑制剂 1基础水平表达 ,这种调节可能通过核因子κB途径而发挥作用     

反义纤溶酶原激活物抑制剂1 RNA对家兔动脉粥样硬化形成的影响

为探讨纤溶酶原激活物抑制剂1反义RNA对家兔血浆纤溶活性及纤溶酶原激活物抑制剂1的表达、血脂及对动脉粥样硬化斑块形成的影响,通过聚合酶链反应扩增纤溶酶原激活物抑制剂1第二外显子,将聚合酶链反应产物纯化克隆后连入真核细胞表达载体pcDNA3.1,构建纤溶酶原激活物抑制剂1 反义RNA重组质粒.将pcDNA3.1-反义纤溶酶原激活物抑制剂1重组质粒注射到哈尔滨大白兔腹部皮下组织.通过发色底物法测定家兔血浆组织型纤溶酶原激活物及纤溶酶原激活物抑制剂1活性变化,通过免疫组织化学方法检测组织中纤溶酶原激活物抑制剂1表达的改变.测定家兔血脂变化,病理检测其动脉粥样硬化程度.结果显示,应用反义纤溶酶原激活物抑制剂1 RNA重组质粒的家兔血浆纤溶酶原激活物抑制剂1活性降低,组织型纤溶酶原激活物活性升高, 纤溶酶原激活物抑制剂1蛋白表达于内皮细胞,而在平滑肌细胞中未表达 (动脉粥样硬化对照组中内皮细胞、平滑肌细胞和泡沫细胞内均有表达);应用反义纤溶酶原激活物抑制剂1 RNA重组质粒的家兔胆固醇和甘油三酯明显低于动脉粥样硬化对照组(96±42 mg/L比123±12 mg/L, 15±10 mg/L比46±29 mg/L),且动脉粥样硬化程度亦轻于后者.以上提示,反义纤溶酶原激活物抑制剂1 RNA重组质粒的皮下注射能有效阻断家兔体内纤溶酶原激活物抑制剂1蛋白的合成,减轻动脉粥样硬化程度.     

高甘油三酯血症与血凝纤溶系统的关系

为研究脂质代谢紊乱与血浆凝血纤溶活性的关系，分别测定了61例高脂血症患者（混合性高脂血症16例和单纯性高甘油三酯血症45例）的血清脂质和血浆反映凝血纤溶活性的有关指标，并与18例正常人对比。结果发现，高脂血症患者的血浆纤溶酶原激活剂抑制物-1、凝血因子VII和凝血因子X活性明显高于正常对照组（P＜0．05～0．001），组织型纤溶酶原激活物活性明显低于正常对照组（P＜0．05）。血清甘油三酯水平与血浆纤溶酶原激活物抑制剂-1、因子VII和因子X活性是显著的正相关性（P＜0．05～0．001），与组织型纤溶酶原激活物活性是显著的负相关性（P＜0．01）；血清胆固醇水平与血浆纤维蛋白原水平和纤溶酶原激活物抑制剂-1活性呈显著的正相关性（P＜0．05）。结果提示，脂质代谢紊乱，特别是高甘油三酯血症可增加体内凝血活性，降低纤溶活性，有利于血栓形成，对动脉粥样硬化的发生和发展有不利的影响。     

纤维蛋白原对内皮细胞t-PA和PAI-1 mRNA表达的影响

目的 探讨纤维蛋白原（Ｆｇ）对内皮细胞（ＥＣ）组织型纤溶酶原激活物（ｔ－ＰＡ）和纤溶酶原灭活剂（ＰＡＩ－１） ｍＲＮＡ表达的影响。方法 不同浓度Ｆｇ与ＥＣ孵育不同时间后,用单管逆转录聚合酶链反应（ＲＴ－ＰＣＲ）半定量法检测ｔ－ＰＡ和ＰＡＩ－ｍＲＮＡ的表达。结果 用２０,２００,２０００ｍｇ／Ｌ Ｆｇ与ＥＣ孵育１、１２、２４ｈ、ＰＡＩ－１ ｍＲＮＡ的相对表达水平分别为同时相对照组的１．７,３．６,２     

冠心病患者血浆纤维蛋白溶解系统活性测定及与脂蛋白(a)水平的关系

为探讨冠心病患者血浆纤维蛋白溶解酶（简称纤溶酶）活性及与脂蛋白（a）水平的关系，对37例冠心病患者血浆组织型纤溶酶原激活刘、纤溶酶原激活剂抑制物、纤溶酶原和血清脂蛋白（a）水平进行了测定，并与13名健康人对照。结果发现．冠心病患者血浆组织型纤溶酶原激活剂活性低于健康人（P＜0．05）。纤溶酶原激活剂抑制物活性显著高于健康人（P＜0.001），纤溶酶原活性低于健康人（P＜0．05）．血清脂蛋白（a）水平除急性心肌梗塞患者高于健康人（P＜0．05）外，其他患者与健康人相比．差异无显著性。结果还发现：急性心肌梗塞患者血浆组织型纤溶酶原激活刻的活性与血清脂蛋白（a）水平呈负相关（r=-0.898．P＜0．001）。以上结果提示，测量血浆纤溶系统活性和脂蛋白（a）水平，对于冠心病的诊治具有参考价值。     

普罗布考对溶血磷脂酰胆碱致培养人脐静脉内皮细胞损伤的保护作用

为探讨普罗布考对溶血磷脂酰胆碱致培养人脐静脉内皮细胞损伤的保护作用 ,采用培养的人脐静脉血管内皮细胞 ,观察溶血磷脂酰胆碱对内皮细胞产生和分泌一氧化氮及其合酶、组织型纤溶酶原激活剂、纤溶酶原激活物抑制剂及乳酸脱氢酶活性的影响 ,并观察普罗布考的保护作用。结果发现 ,溶血磷脂酰胆碱明显增加乳酸脱氢酶活性 (4 8.0± 4 .1比 2 8.0± 7.5 ,P <0 .0 5 ) ,增加细胞死亡率 (9.9± 1.2比 6 .3± 0 .9,P <0 .0 5 ) ;同时抑制内皮型一氧化氮合酶 (4 8.0± 4 .3比 6 3.4± 6 .8)及组织型纤溶酶原激活剂活性 (0 .31± 0 .0 5比 0 .4 3± 0 .0 7,P <0 .0 5 ) ,增强纤溶酶原激活物抑制剂的活性 (1.39± 0 .2 1比 0 .97± 0 .11,P <0 .0 5 ) ,具有剂量—依赖效应。预先应用不同剂量的普罗布考 (10～ 5 0mmol L)后 ,该效应明显减弱。以上提示 ,溶血磷脂酰胆碱能直接损伤内皮细胞 ,抑制组织型纤溶酶原激活剂及内皮型一氧化氮合酶活性 ,增强纤溶酶原激活物抑制剂活性 ,普罗布考对内皮细胞具有保护作用     

同型半胱氨酸和叶酸对内皮细胞纤溶系统影响

同型半胱氨酸（Hcy）水平的升高与动脉粥样硬化及心脑血管疾病密切相关，叶酸补充治疗可以减少Hcy水平，然而高胱氨酸血症（HHE）的致病机制及叶酸的保护机制还不完全清楚。为了探讨Hcy及叶酸对纤溶系统的影响，我们首次研究了生理及超生理浓度的Hcy与叶酸共同作用对人脐静脉血管内皮细胞（HUVEC）的组织型纤溶酶原激活物（tPA）和纤溶酶原激活物抑制剂-1（PAI-1）的抗原合成及mRNA表达的影响。     

川芎嗪抗血栓形成的机制研究

纤溶酶原激活物抑制剂-1是一种重要的促凝血因子。内毒素脂多糖通过刺激血管内皮细胞分泌纤溶酶原激活物抑制剂-1导致炎症过程中血栓形成。为探讨其机制，本文采用酶联免疫吸附试验法、North-ern印迹法和电泳迁移法观察中药川芎嗪对内毒素脂多糖所致内皮细胞纤溶酶原激活物抑制剂-1表达的影响及可能机制进行探讨。结果发现．川芎嗪不仅抑制内毒素脂多糖所致内皮细胞纤溶酶原激活物抑制剂-1蛋白分泌和mRNA表达．而且抑制内皮细胞纤溶酶原激活物抑制剂-1基础水平的表达。此结果提示，川芎嗪并非通过核因子NF－KB途径抑制内毒素脂多糖所致内皮细胞纤溶酶原激活物抑制剂-1表达增强的作用。     

蛋白激酶C-胞外信号调节激酶1/2信号通路在尼古丁诱导的血管内皮细胞表达纤维溶解酶原激活物抑制物-1中的作用

目的 探讨蛋白激酶C(PKC)-胞外信号调节激酶(ERK)1/2信号通路在尼古丁诱导人脐静脉内皮细胞(HUVECs)表达纤维溶解酶原激活物抑制物-1(PAI-1)中的作用.方法 体外培养HUVECs,采用不同实验条件尼古丁进行干预,ELISA法测定细胞上清液中PAI-1的浓度,观察尼古丁作用的最佳浓度和时间.进一步分别用PKC的抑制剂星型胞菌素staurosporine (STS)和ERK的抑制剂PD98059干预HUVECs,观察PKC或ERK被阻断后对尼古丁诱导的HUVECs 表达PAI-1的影响,ELISA测定各组细胞上清液中PAI-1蛋白的表达水平,RT-PCR检测各组细胞PAI-1 mRNA的表达.结果 100 μmol/L尼古丁组PAI-1蛋白水平[(22.6 ± 1.1)μg/L]明显高于对照组[(14.2± 2.8)μg/L,q=5.64,P＜0.05];以100 μmol/L 尼古丁分别与HUVECs孵育0、4、6、8、12及24 h,各组PAI-1蛋白表达呈时间依赖性升高,并在12 h达到高峰(F=32.063,P＜0.05);尼古丁组PAI-1 mRNA及蛋白含量[(1.32±0.20),(21.08±0.83)μg/L]明显高于对照组[(0.73±0.10),(13.39± 0.93)μg/L,q=8.43、11.97,均P＜0.05];尼古丁+STS组PAI-1 mRNA及蛋白含量[(1.07±0.10),(16.19±2.15)μg/L]较尼古丁组降低(q=5.61、7.61,均P＜0.05),但仍高于对照组(q=7.84、4.36,均P＜0.05);尼古丁+ PD98059组PAI-1 mRNA及蛋白表达[(1.12±0.11),(17.52±1.72)μg/L]低于尼古丁组(q=4.68、5.54,均P＜0.05),仍高于对照组(q=8.77、6.43,均P＜0.05).结论 PKC-ERK1/2信号通路在尼古丁诱导的血管内皮细胞PAI-1表达上调中发挥一定作用.

Abstract：

Objective To explore the role of protein kinase C (PKC)- extracellular signal-regulated kinase (ERK)1/2 signal pathway in the process of plasminogen activator inhibitor-1(PAI-1) protein and mRNA expression in cultured human umbilical vein endothelial cells(HUVECs) induced by nicotine. Methods HUVECs were cultured to examine the effect of nicotine on the expression of secreting PAI-1 in HUVECs on different experimental conditions. The expression of PAI-1 protein was measured by ELISA. PKC inhibitor staurosporine (STS)and ERK1/2 inhibitor PD98059 were used to detect PKC or ERK1/2 function on the expression of PAI-1 in HUVECs induced by nicotine. The PAI-1 mRNA expression was determined by RT-PCR. Results The expression level of PAI-1 protein in 100 μmol/L nicotine treated group [(22.6±1.1) μg/L] increased significantly compared to the control group [(14.2±2.8) μg/L; q=5.64,P<0.05]. After stimulation with 100 μmol/L nicotine for 0,4,6,8,12 and 24 h, the levels of PAI-1 protein increased over time and reached the peak at 12 h (F=32.063,P<0.05).The PAI-1 mRNA and protein expression in nicotine treated group [(1.32±0.20), (21.08 ± 0.83) μg/L] increased significantly compared to the control group [(0.73±0.10), (13.39±0.93) μg/L; q=8.43,11.97,all P<0.05].Compared with nicotine treated group , the PAI-1 mRNA and protein expression in nicotine and STS treated group [(1.07±0.10),(16.19±2.15) μg/L] decreased significantly(q=5.61,7.61, all P<0.05), but still higher than the control group (q=7.84,4.36, all P<0.05). In nicotine and PD98059 treated group, the PAI-1 mRNA and protein expression [(1.12±0.11),(17.52±1.72) μg/L] decreased significantly compared to the nicotine treated group(q= 4.68,5.54, all P<0.05), still higher than the control group (q=8.77,6.43, all P<0.05). Conclusion PKC-ERK1/2 signal pathway may play a partial role in the up-regulation of PAI-1 induced by nicotine in HUVECs.     

Regulation of plasminogen activator inhibitor-1 secretion by urokinase and tissue plasminogen activator in rat epithelioid-type smooth muscle cells

Tissue plasminogen activator (tPA) and urokinase (uPA) are targets of plasminogen activator inhibitor-1 (PAI-1) inhibition. We have previously shown that both proteases can also induce PAI-1 secretion in rat smooth muscle cells (SMCs). We now report that both proteases appear to use very similar cellular mechanisms for signal transduction. They induced PAI-1 secretion using a pathway(s) involving protein kinase C (PKC). They also activated the Raf/Mek/mitogen-activated protein kinase (MAPK) pathway, which lies downstream of PKC activation. Activation of protein kinase A (PKA), however, lowered PAI-1 secretion induced by uPA and tPA, as a result of an inhibition of the PKC pathway and inhibition of Raf, Mek and MAPK phosphorylations. Src and syk family non-receptor tyrosine kinases (TK) were also involved in PAI-1 induction. The mechanisms of interaction of these tyrosine kinases with other pathways appeared to be quite different: src appeared to act within the PKC and PKA pathways, while syk operated independently of these pathways. Furthermore, whereas src inhibition resulted in inhibition of Raf/Mek/Erk phosphorylations, syk inhibition could only inhibit Mek and Erk phosphorylations but not the phosphorylation of Raf. These multiple pathways utilized by uPA and tPA to modulate PAI-1 secretion might be involved in determining the proteolytic or antiproteolytic potential of the SMCs under different pathophysiological conditions.     

Stimulation of plasminogen activator and inhibitor in the lymphatic endothelium

Chromogenic assays, immunoblotting, and Northern blot hybridization methods were employed to assess the effects of various agonists on the production of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) by the lymphatic endothelium (LEC). Fibrin autography showed that plasminogen-dependent fibrinolytic activity occurred at M(r) of 110 kDa, which represents a complex of tPA with PAI-1, and 65- and 55-kDa bands corresponding to tPA and uPA, respectively. The fractionation of lymph collected from ovine lymphatic vessels also produced a prominent lytic band of approximately 110 kDa, suggesting the formation of PA/PAI complexes in lymph. The stimulation of various agonists produced large-scale increases in tPA mRNA, as shown by Northern blot hybridization analyses. The effects of ECGF, histamine, and LPS on the presence of tPA and on enhancing the levels of mRNA reached maximum activity at 4 h and declined to levels below that of controls by 8 h. However, phorbol-treated cells exhibited reduced levels of tPA mRNA at 4 h, but was significantly increased by 8 h. A large-scale increase in PAI-1 mRNA steady-state levels was also stimulated by the agonists used in these studies. Both the 3.4- and 2.4-kb species of PAI-1 mRNA were increased. These observations demonstrated that tPA and PAI-1 are produced and secreted by LEC monolayer cultures and are also present in lymph.     

Glucocorticoid regulation of plasminogen activator inhibitor-1 messenger ribonucleic acid and protein in normal and malignant rat osteoblasts.

Glucocorticoids exert potent inhibitory effects on bone formation. We have previously shown that glucocorticoids suppress plasminogen activator (PA) activity in normal and malignant rat osteoblasts. To clarify the mechanism of this suppression, we investigated the effects of dexamethasone on PA inhibitor-1 (PAI-1), tissue-type PA (tPA), and urokinase-type PA (uPA) expression and also on PAI-1 protein and PA activity in both normal rat calvarial osteoblasts and a clonal osteogenic sarcoma cell line, UMR 106-01. Dexamethasone increased PAI-1 mRNA and protein in both cell types. The increase in PAI-1 protein and the decrease in PA activity were obtained over the same concentration range, with a half-maximally effective concentration of dexamethasone of about 10(-9) M. The increase in PAI-1 mRNA caused by dexamethasone was retained with cycloheximide treatment, but abolished with actinomycin-D. Dexamethasone had no effect on tPA or uPA mRNA in either cell type. The glucocorticoid antagonist RU 486 prevented the effects of dexamethasone on PA activity and PAI-1 protein. Dihydrotestosterone, progesterone, and 17 beta-estradiol did not influence PA activity or PAI-1 formation. Although tPA and uPA protein could not be measured, these results suggest that glucocorticoids suppress PA activity predominantly by increasing PAI-1 synthesis in rat osteoblasts. Suppression of PA activity through actions on PAI-1 formation by glucocorticoids could contribute to the mechanisms by which glucocorticoids inhibit bone formation.     

Different effects of lipopolysaccharide on plasminogen activator inhibitor-1 production in aortic media in vivo and in culture

Background Lipopolysaccharide (endotoxin) has been shown to increase the expression of plasminogen activator inhibitor type-1 (PAI-1) in the vessel wall. Endotoxin is known to increase PAI-1 production in endothelial cells, but its action on smooth muscle cells (SMCs) is presently not clear. In this study we determined the effect of endotoxin on PAI-1 and tissue plasminogen activator (t-PA) production by aortic SMCs in vivo in two animal species, and in culture.Methods The aortas of Sprague Dawley rats and of New Zealand White rabbits were rapidly excised after parenteral administration of endotoxin. Total RNA was extracted from the aortic media, and PAI-1 and t-PA mRNA levels were quantified after Northern blotting. In addition, cultured rat aortic SMCs were treated with endotoxin. PAI activity in the conditioned medium was determined with a spectrophotometric assay, and total RNA was extracted from the cells and analyzed.Results A rapid and strong induction in the aortic media of PAI-1 mRNA was observed by endotoxin in both rat (50 mg/kg) and rabbit (1 mg/kg). t-PA mRNA was barely detectable and was not increased by endotoxin. Studies in cultured SMCs showed low expression of PAI-1 mRNA under serum-free conditions and little PAI activity in the cell-conditioned medium. Endotoxin did not increase the levels of PAI-1 mRNA nor PAI activity under serum-free conditions. The effect of endotoxin (10 mg/ml) in the presence of 10% (v/v) newborn calf serum on PAI-1 mRNA was negligible; PAI activity, however, increased by 50.3 ± 7.3% compared with controls. mRNA levels of t-PA and low-density lipoprotein/receptor-related protein/₂-macroglobulin receptor also increased after endotoxin administration. PAI activity was identified as PAI-1 by immunoblotting. Fibrin zymography showed that t-PA was present only in complex with PAI-1.Conclusions A strong increase in PAI-1 gene expression by endotoxin was observed in aortic SMCs in vivo but not in culture. This suggests that the effect of endotoxin on SMCs is indirect. The fibrinolytic/proteolytic potential of the SMCs in the vessel wall is likely to have important implications for the migration of cells during vessel wall remodeling, such as neointima formation, during tumor cell metastasis, and for the fate of intramural thrombi.     

Increased expression of plasminogen activator and plasminogen activator inhibitor during liver fibrogenesis of rats: role of stellate cells.

BACKGROUND/AIMS: Plasminogen activators and plasminogen activator inhibitors are important regulators of the balance between the proteolytic and antiproteolytic activities that determine extracellular matrix turnover. We examined the expression of plasminogen activator-plasmin system components in experimental liver fibrosis of rats. METHODS: Liver fibrosis was produced in rats by injecting carbon tetrachloride for 6 to 12 weeks. Gene expression for plasminogen activator inhibitor-1 (PAI-1), urokinase and tissue plasminogen activators (uPA and tPA), urokinase plasminogen activator receptor (uPAR), and transforming growth factor-beta1 (TGF-beta1) was examined by Northern analysis. Western analysis was performed to detect protein expression of PAI-1, uPA and uPAR. An immunohistochemical study was performed to detect the localization of PAI-1. Additionally, primary cultured liver cells were examined by Northern and Western analyses for this protein with or without prior incubation with TGF-beta1. RESULTS: At 6 weeks, when fibrosis had occurred, uPA and uPAR mRNAs had increased 2.8-fold and 1.8-fold, respectively; PAI-1 and tPA mRNA levels were unchanged. At the cirrhotic stage (9 to 12 weeks), mRNA levels for PAI-1, uPA, uPAR and tPA were all increased. Western analysis also showed increased uPA and uPAR expressions in fibrotic liver, and increased PAI-1, uPA and uPAR expressions in cirrhotic liver. PAI-1 protein was also demonstrated immunohistochemically along sinusoids, vessels, and bile duct cells of normal and fibrotic liver. In liver cell cultures, Kupffer cells, hepatocytes, and especially stellate cells, expressed PAI-1. Expression was enhanced in stellate cells cultured from fibrotic or cirrhotic liver or stimulated in vitro with TGF-beta1. CONCLUSION: Though increased uPA and uPAR may act on matrix degradation in fibrotic liver, increased PAI-1 together with uPA, uPAR and tPA are associated with overall inhibition of matrix degradation in cirrhotic liver. Hepatic stellate cells are an important source of PAI-1 during liver fibrosis.