Hepatic microvasculature in liver injury

Injury to the hepatic microvasculature, the hepatic sinusoids, manifests in several ways. The sinusoidal endothelial cells (SECs) may lose porosity and scavenger function (capillarization); SECs may loosen from their tetherings to the space of Disse or even detach completely (ischemia-reperfusion injury, early sinusoidal obstruction syndrome, peliosis hepatis, early acetaminophen toxicity); the space of Disse may be completely denuded of sinusoidal lining cells that then embolize and obstruct the sinusoid (early sinusoidal obstruction syndrome); or the sinusoid may be obstructed by fibrosis (hepatic sinusoidal fibrosis, late sinusoidal obstruction syndrome). In many of these microvascular injuries, the change to the sinusoid is a primary event that may lead to hepatocyte hypoxia with liver dysfunction and disruption of the portal circulation. With the exception of hepatic fibrosis, which will be reviewed elsewhere in this issue, each of these types of microvascular injuries will be described in this article.     

Defect of sinusoidal Fc receptors and immune complex uptake in CCl4-induced liver cirrhosis in rats

The purpose of this paper is to provide a histopathologic basis for abnormalities in immune-complex clearance in liver disease. Fc receptors in CCl4-induced liver cirrhosis in rats were studied by applying peroxidase-antiperoxidase immunoglobulin G complex as a ligand to the frozen sections. Intravenous injection of bovine serum albumin-antibovine serum albumin complexes or colloidal carbon was combined with histological staining for endogenous peroxidase, fibronectin, laminin, or a lectin, Bandeiraea simplicifolia agglutinin I. In the cirrhotic process, sinusoidal Fc receptors showed a weakened reactivity to the ligand with focal absence, and the length of the Fc receptor-positive portion of the sinusoids in unit area decreased to about 50% of the normal value in the advanced cirrhosis. Fibronectin and the lectin showed the presence of sinusoids where Fc receptors were absent. The endothelium in Fc receptor-negative areas did not take up either immune complexes or carbon, and Kupffer cells were absent in these areas. A disturbed immune-complex metabolism was thus suggested to occur in association with the defect of sinusoidal Fc receptors in liver cirrhosis. These abnormalities appeared to not be directly related to perisinusoidal laminin deposition, i.e., capillarization of the sinusoid.     

银杏叶提取物对肝硬化大鼠门静脉压及肝窦病理变化的影响

目的探讨银杏叶提取物（EGb）对肝硬化大鼠肝窦微循环及门静脉高压的影响。方法25只雄性Wistar大鼠分为3组：正常对照组（5只）,CCl_4组（10只）,EGb治疗组（10只）。肠系膜上静脉插管测定各组大鼠灌注EGb前后门静脉压力;肝组织匀浆中检测丙二醛（MDA）,血管内皮素（ET-1）,血小板活化因子（PAF）,一氧化氮（NO）,构生型一氧化氮合成酶（cNOS）和诱生型一氧化氮合成酶（iNOS）水平;电镜观察各组肝窦微循环特征。结果EGb灌注后CCl4组门静脉压由（8．7±0．8）mm Hg降至（7．4±0．6）mmHg,降低幅度15%,t 4．11,P＜0．01; EGb治疗组与CCl_4组比较,门静脉压、肝组织MDA、ET-1、PAF、NO和iNOS水平显著降低（P＜0．05或P＜0．01）,肝窦内胶原沉积、微血栓形成、肝窦毛细血管化程度减轻。结论银杏叶提取物能改善肝窦微循环障碍,降低门静脉压力,其可能机制是降低MDA、ET 1、PAF含量,下调iNOS的表达调节NO含量,对慢性肝病治疗具有重要意义。     

The hepatic microcirculation in the isolated perfused human liver

In cirrhosis, capillarization of sinusoids could result in impaired exchanges between the hepatocytes and the blood perfusing the liver and contribute to liver failure irrespective of the metabolic capacity of the liver. To characterize anomalies of the hepatic microcirculation, we used the multiple-indicator dilution approach in isolated perfused livers obtained from patients with cirrhosis at the time of transplantation, and from organ donors with normal or near-normal livers or hepatic steatosis. In organ donors, the sinusoidal volume and the permeability of sinusoids to albumin, sucrose, and water were found to be comparable to that of normal dog and rat livers. The sinusoidal volume and the extravascular volume (EVV) accessible to diffusible tracers were larger after hepatic artery than after portal vein injection, probably because of an unshared arterial sinusoidal bed. In cirrhotic livers, two kinds of alterations were found: the appearance of a barrier between the sinusoids and the hepatocytes (capillarization) and intrahepatic shunts. The extravascular space accessible to albumin decreased with increasing severity of cirrhosis, and the diffusion of sucrose in the space of Disse showed a barrier-limited pattern, instead of the normal flow-limited behavior. In cirrhotic livers, a correlation was found between the hepatic extraction of indocyanine green (ICG) and the extravascular space accessible to albumin (r = .84, P < .05), suggesting that the impaired access of this protein-bound dye to the hepatocyte surface contributed to its impaired elimination. Intrahepatic shunts were found between portal and hepatic vein (21% +/- 16% of portal flow), but not between hepatic artery and hepatic veins. We conclude that (1) the behavior of diffusible tracers in human livers with normal liver architecture is comparable to that reported in normal animals; (2) the permeability of sinusoids in cirrhotic livers is abnormal, (3) permeability changes are related to changes in liver function in cirrhosis. (Hepatology 1996 Jan;23(1):24-31)     

四氯化碳诱导的肝纤维化大鼠肝窦毛细血管化的形成

目的：观察四氯化碳（CCl4）诱导的大鼠肝纤维化过程中肝窦毛细血管化的形成过程,探讨其与肝纤维化的关系。方法32只清洁级雄性SD大鼠,随机分为正常对照组,肝纤维化模型组,正常对照组大鼠腹腔注射0．9％氯化钠溶液2 mL/kg ,模型组大鼠腹腔注射50％ CCl4-蓖麻油混合液2 mL/kg ,每周2次,共8周;分别于造模第2、4、6、8周处死大鼠,观察肝组织炎症及纤维化程度,放射免疫法检测血清中透明质酸（HA）的含量,透射电镜观察肝窦窦壁结构,S-P 免疫组织化学检测各组大鼠肝组织CD31、层黏连蛋白（LN）、IV型胶原（Col-IV）的表达。结果肝脏组织学证实CCl4诱导的大鼠肝纤维化模型构建成功,6周可见纤维间隔形成;透射电镜显示,CCl4诱导2周时,部分肝窦内皮细胞（liver sinusoidal endothelial cells ,LSEC）窗孔减少,内皮下未见基底膜（Basement membrane,BM）,随着造模的进程,LSEC 窗孔进一步减少,部分甚至消失,第6、8周时局部肝窦内皮下形成连续的BM。同时,随着肝纤维化的进程,HA浓度逐渐升高,肝窦内皮细胞表面标志物CD31及基底膜主要成分Col-IV、LN表达逐渐增强。结论在CCl4诱导大鼠肝纤维化过程中,肝窦毛细血管化是逐渐形成的,LSEC失窗孔早于纤维间隔的形成,而肝窦内皮下基底膜出现在纤维间隔形成以后。     

当归对大鼠慢性CCl4肝损伤时肝脏超微结构的影响

采用大鼠慢性CCl_4肝损伤模型观察当归对其肝脏超微结构的影响。结果表明,CCI_4组大鼠肝脏有大量肝细胞变性坏死,坏死灶中可见大量胶原纤维,残存肝细胞体积缩小,细胞器变化轻微,CCl_4加当归组肝细胞坏死偶见,肝细胞内线粒体、内质网明显增生。CCl_4组肝细胞间隙极度增宽,其内为肿胀的微绒毛、坏死物质和胶原纤维,肝窦腔明显狭窄或角塞,有明显Disse间隙胶原化及肝窦毛细血管化:CCl_4加当归组也有肝细胞间隙增宽,其内主要为增多、延长的微绒毛,坏死物少见,没有胶原沉积,肝窦通畅。研究证实,当归对CCl_4所致的慢性肝损伤的肝脏超微结构有明显保护作用,其作用机理可能主要与改善肝脏微循环有关。     

Ultrastructural localization of type IV collagen and laminin in the Disse space of rat liver with carbon tetrachloride induced fibrosis

Monospecific antibodies, directed against type IV collagen and laminin, were used to clarify the process of sinusoidal capillarization in rats after carbon tetrachloride (CCl4) intoxication by the direct immunoperoxidase method. After acute intoxication, both type IV collagen and laminin were increased in the area of hepatic necrosis, adjacent to the central veins; however, sinusoidal capillarization was not found. During chronic intoxication, deposition of laminin was co-distributed with that of type IV collagen, but deposition proceeded more slowly than that of the type IV collagen. Deposition of laminin was increased in the Disse space. Sinusoidal capillarization was noted as thick deposition of both antigens by light microscopy. Immunoelectron microscopy showed that both components were continuously present in the Disse space. Intracellularly, both antigens were found in the rough endoplasmic reticulum (RER) of fat-storing cells (FSC) and endothelial cells, and these cells showed morphological changes, becoming slender and flattened. In contrast, few immunoreactive products of the two components were observed in the hepatocytes. These findings suggest that type IV collagen and laminin are indispensable for the establishment of sinusoidal capillarization, and that FSC play an important role in the production of both components.     

Distribution and cellular origin of collagen VI during development and in cirrhosis.

Collagen VI is a ubiquitous microfibrillar collagen that forms a network in most interstitial connective tissues, including soft organs and cartilage. The extracellular and intracellular distribution of collagen VI in human liver was studied by light and electron microscopy using the indirect immunoperoxidase method. In normal adult liver, collagen VI was seen mainly in portal spaces and formed a continuous layer in the sinusoids. Fetal liver contained more of collagen VI in the sinusoid than newborn and adult livers. In alcoholic fibrotic and cirrhotic livers, collagen VI antibodies intensely stained fibrous septa that invaded the lobule. Immunoelectron microscopy on normal liver showed that collagen VI antibodies labeled microfibrillar material and occasionally the surface of cells including hepatocytes. In both perinatal and fibrotic livers, electron-dense deposits were abundant in the space of Disse, intensely staining fibrils located around bundles of banded collagen. In both normal and fibrotic adult livers, collagen VI was abundant in the rough endoplasmic reticulum of Ito cells, while hepatocytes were constantly negative. In fetal livers, hepatocytes also contained collagen VI. These results suggest that collagen VI is a major constituent of the hepatic extracellular matrix. Furthermore, the cellular sources of collagen VI appear to be different in adult and developing livers.     

Myofibroblasts in the cirrhotic rat liver reflect hepatic remodeling and correlate with fibrosis and sinusoidal capillarization

BACKGROUND/AIMS: Myofibroblasts are essential in fibrogenesis during development of cirrhosis. In the present study we stereologically quantitated MFB's and correlated them with fibrosis and sinusoidal capillarization. METHODS: Male SD rats were rendered cirrhotic by chronic exposure to phenobarbital/CCl4, (CIR; n = 16); untreated littermates served as controls (CTR; n = 10). Sinusoidal capillarization was assessed by a multiple indicator dilution technique as previously described. The volume fractions of myofibroblasts and other liver components were estimated by morphometry. RESULTS: Myofibroblasts averaged 15.7 +/- SD 0.7% in CIR as compared to 6.7% +/- SD 0.4% in CTR (p < 0.01). An extra-littoral compartment of myofibroblasts was found in portal tracts and within fibrous septa. In CIR, hepatocytes showed a bimodal distribution of volume fractions, and hepatocyte volume distribution disclosed a mirror image of that of myofibroblasts. Connective tissue was markedly increased in CIR, averaging 13.2 +/- 1.2% in CIR vs. 1.2 +/- 0.3% in CTR (p < 0.0001). Extravascular albumin space--a measure of sinusoidal capillarization--was reduced by 44% in CIR (0.028 +/- 0.017 vs. 0.050 +/- 0.010 ml/g; p < 0.001). The volume fraction of myofibroblasts correlated best with extravascular albumin space (r = -0.84, p < 0.001). Multiple regression analysis selected only extravascular albumin space and connective tissue to be determined by the volume fraction of myofibroblasts (r = 0.923; p < 0.001). CONCLUSION: We conclude that increased myofibroblasts reflect the degree of hepatic remodeling rather than cirrhosis inasmuch as myofibroblast volume fraction inversely reflects that of hepatocyte bimodality. Myofibroblasts form an extra-littoral compartment in this model of CIR and correlate with hepatic fibrosis and sinusoidal capillarization.     

Localization of hyaluronan in human liver sinusoids: a histochemical study using hyaluronan-binding protein

Abstract: Circulating hyaluronan is mostly derived from lymph, fibroblast and Ito cells in the liver, and more than 90% of hyaluronan is degraded in hepatic sinusoidal endothelial cells. Thus, elevated serum hyaluronan is regarded as an indication of hepatic fibrosis with activated Ito cells and dysfunctional sinusoidal endothelial cells. We studied the distribution of hyaluronan in human liver sinusoids to determine the influences on elevated hyaluronan levels in sera. Histochemical examination was made using hyaluronan-binding protein (HABP) and serial sections of liver tissue for staining of alpha-smooth muscle actin (ASMA) (an indicator of activated Ito cells) and of ulex europaeus agglutinin I lectin (UEA-1) (closely related to hepatic sinusoidal capillarization). Positive staining, indicating the presence of hyaluronan, was noted in fibrous regions around the portal tracts, areas of focal necrosis in the liver parenchyma, and walls of the sinusoids in chronic hepatitis. In this group, hyaluronan-positive areas corresponded to positive ASMA staining and faint staining of UEA-1. On the contrary, in liver cirrhosis, UEA-1-positive areas were essentially identical to hyaluronan-positive areas and to ASMA-negative areas in sinusoidal walls. Hyaluronan and ASMA could be detected in the same areas of sinusoidal walls in chronic hepatitis, but not in liver cirrhosis. Hyaluronan appears to be mainly related to the staining of activated Ito cells in chronic hepatitis. Therefore, we concluded that in chronic hepatitis, the production of hyaluronan was accelerated in Ito cells; however, degradation of hyaluronan by sinusoidal endothelial cells continued. On the contrary, in liver cirrhosis, hyaluronan production decreased in Ito cells, and a marked transformation of sinusoidal endothelial cells with hepatic sinusoidal capillarization indicated loss of the ability to degrade hyaluronan. These different mechanisms in chronic hepatitis and liver cirrhosis may operate in the sinusoidal walls and may cause the elevation of hyaluronan in sera.     

The role of capillarization in hepatic failure: studies in carbon tetrachloride-induced cirrhosis.

During the cirrhotic process, the hepatic microvascular phenotype is transformed from sinusoids (discontinuous capillaries) into continuous capillaries. This transformation has been termed capillarization. Many hepatic functions depend on the rapid, bidirectional exchange of macromolecules between plasma and hepatocytes. To determine whether capillarization contributes to hepatic failure in cirrhosis, we decided to study the plasma clearance (125I) and hepatocyte uptake (electron microscopy) of three tracers in normal and cirrhotic rats. The tracers chosen were a hemeundecapeptide with peroxidatic activity (fluid-phase pinocytosis), asialofetuin (receptor-mediated endocytosis of a medium size protein) and ferritin (receptor-mediated endocytosis of a large size protein). The results demonstrate a decreased hepatocyte uptake of hemeundecapeptide; a significant delay in plasma clearance of asialofetuin; and a minor delay in plasma clearance of ferritin, but a striking trapping of ferritin in the cirrhotic capillary basement membrane. The delayed plasma clearance in cirrhosis cannot be ascribed to a decreased number of surface receptors because, in isolated hepatocytes, the number of molecules bound per cell was equivalent in normal and cirrhotic livers. These findings support the concept of capillarization, with the formation of continuous diffusion and filtration barriers between plasma and hepatocytes, representing a significant hindrance to the bidirectional macromolecular exchange normally taking place between these two compartments. Furthermore, at least in the case of ferritin, the capillary basement membrane of cirrhotic livers seems to be the major filtration barrier. This hindrance to hepatocyte uptake, and presumably also to secretion, may be the cause (or at least a major determinant) of the hepatic failure characteristic of cirrhosis.     

慢性乙型肝炎及肝硬化患者肝脏微循环改变

为探讨慢性乙型肝炎（慢乙肝）及肝硬化患者的肝脏微循环状态。对141例慢乙肝、12例肝硬化患者和2例正常人的肝组织进行HE染色,光镜观察,并对其中53例慢乙肝和2例肝硬化患者的肝组织进行了电镜观察。结果显示,正常人的肝窦腔通畅,无狭窄和闭塞,无红细胞聚集现象。慢乙肝患者86.52%有肝窦腔狭窄,60.28%肝窦腔内见红细胞聚集,34.04%肝窦腔内有血栓形成;电镜观察见94.34%的患者肝窦内皮细胞窗孔减小减少,33.96%有基底膜形成,24.53%狄氏腔内出现胶原纤维。肝硬化患者肝组织结构紊乱,肝腺泡消失,假小叶形成。提示慢乙肝患者存在肝脏微循环障碍,肝硬化时肝脏微循环结构丧失。     

Histochemical properties of vascular and sinusoidal endothelial cells in liver diseases

Liver biopsy specimens with or without liver diseases were examined immunohistochemically to determine the distribution of endothelial cell markers, factor VIII-related antigen (FVIII-RAg), Ulex europaeus agglutinin I (UEA-I) lectin and PAL-E. We also investigated the localization of laminin, a component of the basement membrane. In normal livers, FVIII-RAg, UEA-I and laminin were negative in sinusoidal endothelial cells, but positive in blood vascular endothelia of the portal area. The antigen detected by PAL-E was distributed in venous endothelial cells. PAL-E did not label endothelial cells of the artery. In the lobule, immunoreactivity with PAL-E was weakly detected only in some sinusoids of the periportal area. In chronic active hepatitis and liver cirrhosis, FVIII-RAg and UEA-I stained endothelial cells of neovasculatures in the enlarged portal areas of the fibrous septum surrounding pseudolobules. Some sinusoidal endothelial cells in cirrhotic livers were reactive to UEA-I and FVIII-RAg, whereas PAL-E-positive cells were found rarely in the pseudolobules. In carcinomatous sinusoidal endothelial cells, FVIII-RAg, UEA-I and PAL-E were strongly stained. Laminin underlay these carcinomatous sinusoids. These suggest capillarization of sinusoids in hepatocellular carcinoma. The histochemical approach using endothelial cell markers could be a practical tool in the diagnosis of hepatocellular carcinoma.     

整合素α6在肝窦毛细血管化中的表达

目的探讨整合素α6在肝窦毛细血管化时的表达情况. 方法皮下注射四氯化碳制备大鼠肝纤维化模型,进行层粘连蛋白(LN)及其整合素受体α6免疫组织化学检测及整合素α6斑点免疫印迹研究. 结果动态观察了LN在肝纤维化时沿肝窦在Disse间隙沉积形成肝窦毛细血管化;正常时整合素α6局限于汇管区血管内皮和胆管内皮细胞膜上,窦内皮细胞(SEC)上无表达,肝窦毛细血管化时,SEC出现整合素α6阳性表达沿肝窦连续分布,整合素α6在纤维化时组织中含量明显高于正常(P＜0.05). 结论肝窦毛细血管化时SEC出现整合素α6亚基的诱导表达.     

Three-dimensional examination of hepatic stellate cells in rat liver and response to endothelin-1 using confocal laser scanning microscopy

BACKGROUND AND AIM: Hepatic stellate cells (HSC) are located in the space of Disse and are considered to participate in the regulation of sinusoidal flow. The contractility of quiescent HSC in normal liver has remained controversial, unlike activated HSC in injured liver. The aim of the present study was to examine the morphological changes in quiescent HSC in response to endothelin-1 (ET-1) perfusion. METHODS: Sections (50 micro m thick) obtained from 15 normal rat livers with or without ET-1 perfusion (1 or 400 nmol/L) were stained immunohistochemically with antiglial fibrillary acidic protein (GFAP) antibody and then examined using confocal laser scanning microscopy. For examination of HSC, hepatic lobules were divided into three anatomic regions from the portal areas to the central veins. The length of HSC cytoplasmic processes and area of the sinusoids relative to the section area, excluding portal tracts and central veins, were measured. RESULTS: The GFAP-positive HSC were distributed relatively evenly in the hepatic lobules and those in region 2 (the area between periportal and pericentral areas) tended to have longer cytoplasmic processes. Perfusion of 1 or 400 nmol/L ET-1 for 25 min resulted in swelling of the cell bodies of GFAP-positive HSC and condensation of the intermediate filaments compared with those perfused with buffer only. Although narrowing of the sinusoidal lumen was observed in each region after perfusion with 400 nmol/L ET-1, there was no apparent shortening of the cytoplasmic processes of HSC. These findings were also confirmed quantitatively. CONCLUSION: In the normal rat liver, quiescent HSC are not involved in the regulation of sinusoidal blood flow in response to ET-1.     

Histochemical properties of vascular and sinusoidal endothelial cells in liver diseases.

Liver biopsy specimens with or without liver diseases were examined immunohistochemically to determine the distribution of endothelial cell markers, factor VIII-related antigen (FVIII-RAg). Ulex europaeus agglutinin I (UEA-I) lectin and PAL-E. We also investigated the localization of laminin, a component of the basement membrane. In normal livers, FVIII-RAg, UEA-I and laminin were negative in sinusoidal endothelial cells, but positive in blood vascular endothelia of the portal area. The antigen detected by PAL-E was distributed in venous endothelial cells. PAL-E did not label endothelial cells of the artery. In the lobule, immunoreactivity with PAL-E was weakly detected only in some sinusoids of the periportal area. In chronic active hepatitis and liver cirrhosis, FVIII-RAg and UEA-I stained endothelial cells of neovasculatures in the enlarged portal areas of the fibrous septum surrounding pseudolobules. Some sinusoidal endothelial cells in cirrhotic livers were reactive to UEA-I and FVIII-RAg, whereas PAL-E-positive cells were found rarely in the pseudolobules. In carcinomatous sinusoidal endothelial cells, FVIII-RAg, UEA-I and PAL-E were strongly stained. Laminin underlay these carcinomatous sinusoids. These suggest capillarization of sinusoids in hepatocellular carcinoma. The histochemical approach using endothelial cell markers could be a practical tool in the diagnosis of hepatocellular carcinoma.     

Enhanced expression of endothelin receptor subtypes in cirrhotic rat liver

BACKGROUND/AIMS: A number of vasoactive substances have been implicated as potential mediators of intrahepatic portal hypertension. Endothelin (ET)-1 has been suggested to be involved in the regulation of hepatic microcirculation and development of portal hypertension. The aim of this study was to clarify the localization of two subtypes of ET receptors, ET A (ETAR) and B receptors (ETBR), in normal rat liver, and how the receptor expressions are altered in CCl4-induced cirrhotic rat liver. METHODS: Liver specimens were examined immunohistochemically after reacting with anti-ETAR and anti-ETBR rabbit polyclonal antibodies. Immunogold staining was also performed using the same antibodies, and examined under light and electron microscopy. RESULTS: In normal rat liver, immunohistochemistry revealed expression of ETAR and ETBR on the hepatic sinusoidal lining cells. By immunogold electron microscopy, electron-dense gold particles indicating the presence of ETARs were localized mainly on hepatic stellate cells (HSCs) and to a lesser extent on sinusoidal endothelial cells (SECs), while ETBRs were expressed equally intensely on HSCs and SECs. In cirrhotic animals, both ETAR and ETBR increased significantly on HSCs, while there were no significant increases in either receptor on SECs. CONCLUSIONS: In the normal state, HSCs possess both ETARs and ETBRs, while SECs mainly possess ETBRs. In cirrhosis, endothelins may exert more intense effects on HSCs via the enhanced ETARs and ETBRs, causing an increase in hepatic sinusoidal microvascular tone.     

Dynamic changes of capillarization and peri-sinusoid fibrosis in alcoholic liver diseases

AIM:To investigate the dynamic changes of capillarization and peri-sinusoid fibrosis in an alcoholic liver disease model induced by a new method.METHODS:Male SD rats were randomly divided into 6 groups,namely normal,4d,2w,4w,9w and 11w groups.The animals were fed with a mixture of alcohol for designated days and then decollated,and their livers were harvested to examine the pathological changes of hepatocytes, hepatic stellate cells,sinusoidal endothelial cells,sinusoid, perisinusoid.The generation of three kinds of extra cellular matrix was also observed.RESULTS:The injury of hepatocytes became severer as modeling going on.Under electronic microscope,fatty vesicles and swollen mitochondria in hepatocytes,activated hepatic stellate cells with fibrils could been seen near or around it.Fenestrae of sinusoidal endothelial cells were decreased or disappeared,sinusoidal basement was formed.Under light microscopy typical peri-sinusoid fibrosis, griddinglike fibrosis, broaden portal areas, hepatocyte‘s fatty and balloon denaturation,iron sediment,dot necrosis,congregated lymphatic cells and leukocytes were observed.Type I collagen showed an increasing trend as modeling going on,slightly recovered when modeling stopped for 2 weeks. Meanwhile,type IV collagen decreased rapidly when modeling began and recovered after modeling stopped for 2 weeks.Laminin increased as soon as modeling began and did not recover when modeling stopped for 2 weeks.CONCLUSION:The pathological changes of the model were similar to that of human ALD,but mild in degree.It had typical peri-sinusoid fibrosis, however,capillarization seemed to be instable.It may be related with the reduction of type IV collagen in the basement of sinusoid during modeling.     

Expression and cellular localization of fibrillin-1 in normal and pathological human liver

BACKGROUND: The expression and the distribution of fibrillin-1 and elastin were studied in normal and pathological human liver samples. METHODS: As controls, histologically normal/subnormal liver samples (n = 24) were used. Pathological samples corresponded to seven cirrhosis and eight hepatocellular carcinomas (HCC) developed on cirrhotic (four) or noncirrhotic (four) liver. RESULTS: In normal liver, fibrillin-1 and elastin co-localized in vessel walls and portal tract connective tissue. Fibrillin-1 alone was detected along sinusoids and in portal spaces at the interface with the limiting hepatocytic plates and close to the basement membrane of bile ducts. By transmission electron microscopy, typical bundles of microfibrils were detected both in Disse space and in portal zones. Cirrhotic nodules were usually rich in fibrillin-1 along sinusoids; fibrillin-1 and elastin were co-localized in fibrotic septa surrounding nodules. In HCC, fibrillin-1 was present between tumoral hepatocytes; stromal reaction around the tumors contained both fibrillin-1 and elastin. CONCLUSIONS: Fibrillin-1 was associated with elastin in portal mesenchyme and vessel walls of normal liver, in fibrotic septa around cirrhotic nodules and stromal reaction around HCC, but was expressed alone in the perisinusoidal space. The functional roles for fibrillin-1 in non-elastic tissues, such as the liver, remain to be elucidated.     

Intrahepatic circulation in liver disease

Using the multiple indicator dilution approach, events occurring in the microvascular bed can be characterized in experimental animals with different types of cirrhosis and in man. Intrahepatic shunts can be found shunting blood away from sinusoids in both cirrhotic patients and cirrhotic animals. Such shunts were present in about one-third of cirrhotic patients with portal hypertension, and occurred mainly between the portal vein and hepatic veins. In cirrhotics, portohepatic anastomoses are usually large in diameter (more than 20 micron in diameter). Collagenization of the space of Disse and the progressive transformation of sinusoids into capillary-like channels decrease the extravascular space accessible to albumin and probably to other large molecules and protein-bound substances. However, unlike findings obtained in well-capillarized organs, these sinusoidal changes do not appear to limit the diffusion of sucrose, water, and lipophilic substances, such as lidocaine in the extravascular and intracellular spaces. The pattern observed for labeled sucrose curves following hepatic artery injection in cirrhotic patients could be secondary to the passage through the dense peribiliary capillary plexus originating from the enlarged arterial bed in cirrhosis. The difference in the perfusion of cirrhotic nodules with regard to the portal venous and hepatic artery routes introduces important new concepts in the overall mechanism of the elimination of endogenous and exogenous substances by the cirrhotic liver: blood entering the liver by the two afferent vessels will not flow through the same vascular bed before reaching the efferent hepatic veins.