Transcriptional Dynamics of Hepatic Sinusoid-Associated Cells After Liver Injury.

BACKGROUND AND AIMS: Hepatic sinusoidal cells are known actors in the fibrogenic response to injury. Activated hepatic stellate cells (HSCs), liver sinusoidal endothelial cells, and Kupffer cells are responsible for sinusoidal capillarization and perisinusoidal matrix deposition, impairing vascular exchange and heightening the risk of advanced fibrosis. While the overall pathogenesis is well understood, functional relations between cellular transitions during fibrogenesis are only beginning to be resolved. At single-cell resolution, we here explored the heterogeneity of individual cell types and dissected their transitions and crosstalk during fibrogenesis. APPROACH AND RESULTS: We applied single-cell transcriptomics to map the heterogeneity of sinusoid-associated cells in healthy and injured livers and reconstructed the single-lineage HSC trajectory from pericyte to myofibroblast. Stratifying each sinusoidal cell population by activation state, we projected shifts in sinusoidal communication upon injury. Weighted gene correlation network analysis of the HSC trajectory led to the identification of core genes whose expression proved highly predictive of advanced fibrosis in patients with nonalcoholic steatohepatitis (NASH). Among the core members of the injury-repressed gene module, we identified plasmalemma vesicle-associated protein (PLVAP) as a protein amply expressed by mouse and human HSCs. PLVAP expression was suppressed in activated HSCs upon injury and may hence define hitherto unknown roles for HSCs in the regulation of microcirculatory exchange and its breakdown in chronic liver disease. CONCLUSIONS: Our study offers a single-cell resolved account of drug-induced injury of the mammalian liver and identifies key genes that may serve important roles in sinusoidal integrity and as markers of advanced fibrosis in human NASH.

Pyrrolizidine alkaloids-induced hepatic sinusoidal obstruction syndrome: Pathogenesis, clinical manifestations, diagnosis, treatment, and outcomes.

Hepatic sinusoidal obstruction syndrome (HSOS) can be caused by the intake of pyrrolizidine alkaloids (PAs). To date, PAs-induced HSOS has not been extensively studied. In view of the difference in etiology of HSOS between the West and China, clinical profiles, imaging findings, treatment, and outcomes of HSOS associated with hematopoietic stem cell transplantation or oxaliplatin might be hardly extrapolated to PAs-induced HSOS. Reactive metabolites derived from PAs form pyrrole-protein adducts that result in toxic destruction of hepatic sinusoidal endothelial cells. PAs-induced HSOS typically manifests as painful hepatomegaly, ascites, and jaundice. Laboratory tests revealed abnormal liver function tests were observed in most of the patients with PAs-induced HSOS. In addition, contrast computed tomography and magnetic resonance imaging scan show that patients with PAs-induced HSOS have distinct imaging features, which reveal that radiological imaging provides an effective noninvasive method for the diagnosis of PAs-induced HSOS. Liver biopsy and histological examination showed that PAs-induced HSOS displayed distinct features in acute and chronic stages. Therapeutic strategies for PAs-induced HSOS include rigorous fluid management, anticoagulant therapy, glucocorticoids, transjugular intrahepatic portosystemic shunt, liver transplantation, etc. The aim of this review is to describe the pathogenesis, clinical profiles, diagnostic criteria, treatment, and outcomes of PAs-induced HSOS.

Quantification of Hepatic Vascular and Parenchymal Regeneration in Mice.

BACKGROUND: Liver regeneration consists of cellular proliferation leading to parenchymal and vascular growth. This study complements previous studies on cellular proliferation and weight recovery by (1) quantitatively describing parenchymal and vascular regeneration, and (2) determining their relationship. Both together are needed to (3) characterize the underlying growth pattern. METHODS: Specimens were created by injecting a polymerizing contrast agent in either portal or hepatic vein in normal or regenerating livers after 70% partial hepatectomy. 3D image data were obtained through micro-CT scanning. Parenchymal growth was assessed by determining weight and volume of the regenerating liver. Vascular growth was described by manually determined circumscribed parameters (maximal vessel length and radius of right inferior portal/hepatic vein), automatically determined cumulative parameters (total edge length and total vascular volume), and parameters describing vascular density (total edge length/volume, vascular volume fraction). The growth pattern was explored by comparing the relative increase of these parameters to the increase expected in case of isotropic expansion. RESULTS: Liver volume recovery paralleled weight recovery and reached 90% of the original liver volume within 7 days. Comparing radius-related vascular parameters immediately after surgical resection and after virtual resection in-silico revealed a slight increase, possibly reflecting the effect of resection-induced portal hyperperfusion. Comparing length-related parameters between post-operative day 7 and after virtual resection showed similar vascular growth in both vascular systems investigated. In contrast, radius-related parameters increased slightly more in the portal vein. Despite the seemingly homogeneous 3D growth, the observed vascular parameters were not compatible with the hypothesis of isotropic expansion of liver parenchyma and vascular structures. CONCLUSION: We present an approach for the quantitative analysis of the vascular systems of regenerating mouse livers. We applied this technique for assessing the hepatic growth pattern. Prospectively, this approach can be used to investigate hepatic vascular regeneration under different conditions.

Three-dimensional imaging of hepatic sinusoids in mice using synchrotron radiation micro-computed tomography.

Hepatic sinusoid, the smallest vessel in the liver, plays important roles in hepatic microcirculation. Although the structure of the hepatic sinusoids affects diverse functions of the liver, little is known about morphological alterations in the sinusoids under pathological conditions. In this study, we show that the structure of hepatic sinusoids can be identified three-dimensionally in normal and carbon tetrachloride-injured mouse liver, using the absorption mode of synchrotron radiation micro-computed tomography. We observed that the hepatic sinusoidal structure on tomographic slice images was similar to that on histological images of normal and acutely injured mice. Moreover, centrilobular necrosis and structural alterations of the sinusoids in the necrotic region were detectable on tomographic slice and volume-rendered images of the acutely injured mice. Furthermore, quantitative analyses on 3D volume-rendered images of the injured sinusoid revealed decrease in the volume of the sinusoid and connectivity of the sinusoidal network. Our results suggest that the use of synchrotron radiation micro-computed tomography may improve our understanding of the pathogenesis of hepatic diseases by detecting the hepatic sinusoids and their alterations in three-dimensional structures of the damaged liver.

[Effects of platelets on the adhesion between leukocytes and liver sinusoidal endothelium cells as well as on the transendothelial migration of leukocytes undergoing hypoxia-reoxygenation].

OBJECTIVE: To investigate the effects of platelet on intercellular adhesion between leukocyte and liver sinusoidal endothelial cell(LSEC) and the transendothelial migration under the hypoxia-reoxygenation condition, as well as the role of relevant adhesion molecules. METHOD: LSEC was cultured for 24 hours under hypoxia condition and then reoxygenated for 2 hours (hypoxia-reoxygenation, HR). This hypoxia-reoxygenation model was used to simulate the clinical liver ischemia-reperfusion injury process (IRI). Platelets and leukocytes were labeled with fluorescence dye, and then the adhesion was detected by fluorescence microscope, fluorescence plate reader and laser scanning confocal microscope. Antibody blockage experiment was used to analyze the relevant adhesion molecules. RESULTS: The adhesion between platelets and LSEC was increased significantly after HR. The fluorescence intensity of adherent platelets increased from 142.10 ± 7.53 to 289.17 ± 20.00(P < 0.01). After H-R treatment and the addition of platelets, the number of adherent leukocytes increased markedly, and a significant statistical difference (360.71 ± 23.47 and 186.39 ± 17.96, P < 0.01) was found in comparing with the platelet deficient group. These adhesion processes could be blocked respectively by anti-GPIb, anti-GPIIb, anti-GPIIIa, anti-P-selectin, anti-CD31, anti-ICAM-1, anti-VCAM-1 and anti-ELAM-1. Confocal microscopy showed that platelets located between leukocytes and LSEC, and mediated their adhesion process. However, the adhesion of platelets to LSEC decreased the transendothelial migration of leukocytes (227.79 ± 16.51 and 167.27 ± 10.92, P < 0.05). CONCLUSION: During ischemia-reperfusion condition platelets adhere to the surface of LSEC, and then further mediate more adhesion processes between leukocytes and endothelial cells, as well as inhibit the transendothelial migration of leukocytes. The consequence is that large numbers of leukocytes were sequestrated within hepatic sinus, and deteriorate liver ischemia-reperfusion injury.

[Effects of liver sinusoid endothelial cell injury in mouse hepatic veno-occlusive disease].

This study was purposed to investigate the role of monocrotaline-inducing mouse liver sinusoid endothelial cell (SEC) injury in hepatic veno-occlusive disease. BALB/c mice were randomly divided into 2 groups: control group and monocrotaline group, mice were orally administrated with normal saline or monocrotaline with concentration of 200 mg/kg at days 0, 1, 2, respectively. At days 3, 4, 6, 8 and 10 after oral administration with normal saline or monocrotaline, the liver function (ALT, TBIL, AKP) and liver index were examined, and the percentage of activated platelets were detected by flow cytometry. The SEC, vascular endothelial cells and hepatic fibrosis were observed by staining with hematoxylin-eosin and Masson. Transmission electron microscopy was used to observe sinusoidal endothelial cell damage and platelet adhesion. The results showed that compared with control group, mice in monocrotaline group were characterized by severe damage of SEC, numbers of platelet aggregation and adhesion, central number and sinusoidal fibrosis. The percentage of activated platelets and liver index increased (P < 0.05). The characterization of portal hypertension was presented later, such as dysfunction of liver and ascites. It is concluded that SEC injury induced by monocrotaline may be the first step of hepatic veno-occlusive disease, and this kind of SEC injury is self-limiting, but fibrosis is always observed.

AFM imaging of fenestrated liver sinusoidal endothelial cells.

Each microscope with its dedicated sample preparation technique provides the investigator with a specific set of data giving an instrument-determined (or restricted) insight into the structure and function of a tissue, a cell or parts thereof. Stepwise improvements in existing techniques, both instrumental and preparative, can sometimes cross barriers in resolution and image quality. Of course, investigators get really excited when completely new principles of microscopy and imaging are offered in promising new instruments, such as the AFM. The present paper summarizes a first phase of studies on the thin endothelial cells of the liver. It describes the preparation-dependent differences in AFM imaging of these cells after isolation. Special point of interest concerned the dynamics of the fenestrae, thought to filter lipid-carrying particles during their transport from the blood to the liver cells. It also describes the attempts to image the details of these cells when alive in cell cultures. It explains what physical conditions, mainly contributed to the scanning stylus, are thought to play a part in the limitations in imaging these cells. The AFM also offers promising specifications to those interested in cell surface details, such as membrane-associated structures, receptors, coated pits, cellular junctions and molecular aggregations or domains. The AFM also offers nano-manipulation possibilities, strengths and elasticity measurements, force interactions, affinity measurements, stiffness and other physical aspects of membranes and cytoskeleton. The potential for molecular approaches is there. New developments in cantilever construction and computer software promise to bring real time video imaging to the AFM. Home made accessories for the first generation of AFM are now commodities in commercial instruments and make the life of the AFM microscopist easier. Also, the combination of different microscopies, such as AFM and TEM, or AFM and SEM find their way to the market allowing comfortable correlative microscopy.

Hepatocyte transplantation through the hepatic vein: a new route of cell transplantation to the liver.

The efficiency of hepatocyte transplantation into the liver varies with the method of administration. This study investigated whether retrograde infusion via the hepatic vein provides a sufficient number of donor cells for the liver. Donor hepatocytes were isolated from dipeptidyl peptidase IV (DPPIV(+)) rats and transplanted into DPPIV(-) rat livers either by antegrade portal vein infusion or retrograde hepatic vein infusion. Hepatocyte engraftment ratios and localization were evaluated by histological DPPIV enzymatic staining at 1 week and 8 weeks after the transplantation. No significant differences in engraftment efficiency were observed at either 1 week or 8 weeks after transplantation by either route. However, the localization of the transplanted hepatocytes differed with the administration route. Portal vein infusion resulted in predominantly periportal engraftment, whereas hepatic vein infusion led to pericentral zone engraftment. Immunohistochemical analysis showed that the transplanted hepatocytes engrafted in the pericentral zone after retrograde infusion displayed intense CYP2E1 staining similar to the surrounding native hepatocytes. CYP2E1 staining was further enhanced by administration of isosafrole, an inducing agent for various cytochrome P450 enzymes, including CYP2E1. This study demonstrates a novel approach of transplanting hepatocytes into the liver through retrograde hepatic vein infusion as the means to target cell implantation to the pericentral zone.

[Acting mechanism of Cordyceps mycelia extract for antagonizing hepatic sinusoidal capillarization in rats with dimethylnitrosamine induced liver cirrhosis].

OBJECTIVE: To study the acting mechanism of Cordyceps mycelia extract (CME) for antagonizing hepatic sinusoidal capillarization (HSC) in rats with dimethylnitrosamine (DMN) induced liver cirrhosis. METHODS: Rat liver cirrhosis model was established by peritoneal injection of DMN 10 mg/kg 3 times a week for 4 weeks. To rats in the CME-prevented group CME were administrated at a dose of 10 mL/kg, once a day, for 4 weeks. The observation time points were scheduled on the 3rd day (d3), and at the end of the 2nd (W2) and 4th week (W4) after modeling, and the following items were observed: hepatic ultrastructure was observed under electron microscope; expressions of CD44, von Willebrand factor (vWF) and type IV collagen (Col lV) in the liver sinusoidal walls by immunohistochemistry; matrix metalloproteinase-2 and-9 (MMP-2, MMP-9) activity under zymogram method; and serum hyaluronic acid (HA) content by radioimmunoassay. RESULTS: Observation at d3 showed MMP-2 and MMP-9 activity significantly increased, Col IV deposition and CD44 positive staining decreased, vWF positive staining increased in the liver sinusoidal walls, the fenestrae in the sinusoidal endothelial cells (SECs) decreased, and serum HA content increased (P<0.05); at W4, SECs defenestration and sub-SECs basal membrane formation were shown. In the CME-prevented group MMP-2 and MMP-9 activity significantly decreased (P<0.05); defenestration and basal membrane formation alleviated in the early stage (d3, W4); and at W2 and W4 decreases of HA content and vWF positive staining were shown, with increase of CD44 positive staining (P<0.05), more SECs fenestrae, and alleviated basal membrane formation. CONCLUSIONS: The elevation of MMP-2 and MMP-9 activity in the early stage, which degrades the Col IV normally distributed under the sinusoidal endothelium, is an important factor for HSC formation. CME could inhibit the initiation of HSC by decreasing MMP-2 and MMP-9 activity in the early stage, and prevent its formation by decreasing SECs injury and phenotypic changes.

Morphological changes in hepatic vessels during modeling of pulmonary trunk stenosis and after its elimination.

Experiments on dogs showed that pulmonary trunk stenosis increased the tone of arterial vessels in the liver and led to the development of veno-arterial and veno-venous reactions. The number of vessels with intimal musculature and myoelastic sphincters in the arterial bed increases, and muscle rolls in large hepatic veins are thickened. The walls are hypertrophic in all vessels. Elimination of the defect abolished the previously formed vascular adaptation reactions, the tone in afferent liver vessels decreased, which leads to regression of hypertrophic changes in their tunica media. The number of arteries with intimal musculature and sphincters decreases. Muscle rolls in the efferent hepatic veins are thinned.

[Effects of vascular endothelial growth factor on apoptosis of sinusoidal endothelial cells caused by ethanol: experiment with rats].

OBJECTIVE: To investigate the cell death pattern of sinusoidal endothelial cells (SECs) caused by ethanol and the effects of vascular endothelial growth factor (VEGF) on this cell death, as well as the underlying mechanism involving Ets-1 and Caspase-8. METHODS: SECs were isolated from male Wistar rats and cultured in medium containing ethanol (25 - 100 mmol/L). VEGF (20 - 30 ng/ml) was added into the medium to be co-incubated for up to 6 h. Apoptosis was detected by terminal deoxynucleotidyl transferase (TdT)-mediated d-uridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) technique. The protein expression of Ets-1, prototype of anti-apoptotic Ets family, was determined by Western blotting and the Caspase-8 was measured by FLICE/caspase-8 colorimetric protease assay kit. RESULTS: Three days after culture, the SECs showed spindle-like shapes and nearly confluent, however, the cells tended to shrink and die during the time course of ethanol incubation under phase contrast microscope. The control SECs contained only a few percent of TUNEL-positive cells; however, the TUNEL-positive cells started to increase 2 hours after the addition of ethanol (100 mmol/L), and about 75% of the cells were TUNEL-positive 6 hours after ethanol incubation (P < 0.05) under fluorescent microscope. Again, TUNEL-positive cells increased 6 hours after ethanol (25 - 100 mmol/L) incubation in a dose dependent manner (P < 0.05). Six hours after VEGF (20 - 30 ng/ml) was added into the medium with ethanol (100 mmol/L) the percentage of TUNEL positive SECs decreased in a dose dependent manner (P < 0.05), the level of ethanol-induced apoptotic cells in the presence of VEGF (30 ng/ml) being around 71% 6 hours after ethanol incubation alone. The Ets-1 protein level of the SECs decreased 6 hours after ethanol (100 mmol/L) incubation, which was prevented almost completely by VEGF (30 ng/ml). The Caspase-8 activity level was significantly increased to 44.9 +/- 14.3 2 hours after ethanol (100 mmol/L) incubation, and decrease to 30.4 +/- 2.0 and 25.2 +/- 2.2 respectively after the addition of VEGF (20 - 30 ng/ml) (both P < 0.05). CONCLUSION: VEGF prevents the apoptosis of primary cultured SECs induced by ethanol, through at least in part, inhibition of ethanol-induced down-regulation of Ets-1 protein expression and ethanol-induced up-regulation of Casepase-8 activity in SECs.

Differential gene expression in periportal and perivenous mouse hepatocytes.

Hepatocytes located in the periportal and perivenous zones of the liver lobule show remarkable differences in the levels and activities of various enzymes and other proteins. To analyze global gene expression patterns of periportal and perivenous hepatocytes, enriched populations of the two cell types were isolated by combined collagenase/digitonin perfusion from mouse liver and used for microarray analysis. In total, 198 genes and expressed sequences were identified that demonstrated a >/= 2-fold difference in expression between hepatocytes from the two different zones of the liver. A subset of 20 genes was additionally analyzed by real-time RT-PCR, validating the results obtained by the microarray analysis. Several of the differentially expressed genes encoded key enzymes of intermediary metabolism, including those involved in glycolysis and gluconeogenesis, fatty acid degradation, cholesterol and bile acid metabolism, amino acid degradation and ammonia utilization. In addition, several enzymes of phase I and phase II of xenobiotic metabolism were differentially expressed in periportal and perivenous hepatocytes. Our results confirm previous findings on metabolic zonation in liver, and extend our knowledge of the regulatory mechanisms at the transcriptional level.

The ductus venosus and intrahepatic venous system in Callithrix jacchus jacchus and Macaca fascicularis fetuses.

BACKGROUND: The ductus venosus (DV) and the intrahepatic branches of the portal vein are arranged as parallel vessels. Blood shunting through the DV ensures fetal survival during periods of stress. The availability of a suitable animal model with similar structure and function to the human fetus would greatly improve the understanding of DV function. The anatomical and histological structure of the DV has not been thoroughly investigated in non-human primate species. METHODS: Morphological investigations were performed on eight marmoset (Callithrix jacchus jacchus) at 112.5 +/- 5.5 days gestational age (mean +/- SEM) and four near-term (165 days) cynomolgus (Macaca fascicularis) fetuses. RESULTS: The DV drains into the collectus venosus. An asymmetrical muscular lip forms a contractile element of the isthmic portion of the DV. A spherical 'dividing' eminence was found on the dorsal wall of the venous collector just above the outlet of the DV in marmoset fetuses. CONCLUSIONS: Our findings regarding the structure of the DV in cynomolgus and marmoset fetuses were generally in agreement with previous descriptions of the morpho-histological structure of the DV in human fetuses.

Comparative analysis of platelet isolation techniques for the in vivo study of the microcirculation.

OBJECTIVE: In vitro and in vivo studies using isolated platelets require that the cells used for testing are not activated by the isolation procedure. This ensures that the effects measured by the test are the result of the environment or the applied stimulus, but is not an artifact resulting from activation by cell isolation. METHODS: Herein, we analyzed two different platelet isolation procedures (i.e., a Sepharose column versus density gradient centrifugation) with special emphasis on cell activation, including flow cytometric analysis of P-selectin expression, functional quantification of mechanical platelet retention, light microscopic assessment of platelet aggregation, and fluorescence microscopic determination of in vivo rat liver platelet-endothelium cell interaction. RESULTS: Under resting conditions, Sepharose column-isolated platelets showed a negligible fraction of only 2.7 +/- 3.3% cells (mean +/- SEM) with P-selectin expression, and an appropriate response (i.e., a 33-fold increase) upon activation with thrombin receptor-activating peptide (TRAP). In contrast, density gradient centrifugation resulted in P-selectin expression under resting conditions of approximately 50% of the isolated cells and only a 1.6-fold increase on further TRAP stimulation. In addition, density gradient-isolated platelets, but not Sepharose column-isolated platelets, showed increased mechanical retention and agglutination/aggregation in vitro, as well as pronounced adhesion to hepatic venular endothelium in vivo. Interestingly, density gradient-isolated platelets additionally induced in vivo an increase of colocalization of platelets with adherent leukocytes, indicating a generalized microvascular inflammatory response that is comparable to that observed after a 60-minute ischemia/30-minute reperfusion insult. CONCLUSION: Density gradient centrifugation-isolated platelets, but not Sepharose column-isolated platelets, are activated already under resting conditions and induce in vivo a platelet-leukocyte-endothelial cell-associated inflammatory response. Thus, we propose that the method of platelet isolation using the Sepharose column is superior to the density gradient centrifugation technique and might therefore be preferred for in vitro and in vivo assays to study platelet function.

Glucagon-like peptide-1 inhibits glucagon-induced glycogenolysis in perivenous hepatocytes specifically.

Hepatocytes form the hepatic acinus as a unit of microcirculation. Following the bloodstream, at least two different zones can be discerned: the periportal (PPH) and the perivenous (PVH) zones. Recently, we found that insulin inhibits glucagon-induced glycogenolysis in PVH specifically. We therefore investigated the region-specific functional effects of glucagon-like peptide-1 (GLP-1), which is known to have an insulin-like activity, on glucagon-induced glycogenolysis in isolated PPH and PVH prepared by the digitonin-collagenase method. GLP-1 inhibited 0.1 nM glucagon-induced increase in glucose release from the PVH of fed rats specifically (p < 0.01) and had an additive effect with insulin. Insulin binding did not differ between PPH and PVH of fed rats. GLP-1 did not displace [125I]-glucagon binding to the purified hepatic cell membrane. Thus, it is directly confirmed that GLP-1 has an insulin-like activity in the liver.

Electron microscopy of mast cells in the venous wall of canine liver.

Although many mast cells locate under the endothelial layer along the sublobular veins in canine liver, the cell function remains to be fully defined. To establish the nature of the canine mast cell, the mast cells were examined by electron microscopy. A few monocytes contacted with luminal surface of endothelial cells under which mast cells situated. To confirm the chemotaxis of monocyte by hepatic mast cells, the hepatic venous vessels were treated with a histamine releaser (compound 48/80). The monocytes invaded into the subendothelial layer and extended their pseudopodium to the degranulated mast cells. It presumes that some mediators within the mast cell granules might act as a chemotactic substance to the monocyte. On the contrary, mast cells were migrating from subendothelial layer to venous lumen under normal condition. The migrating mast cell showed strong acid phosphatase reaction in their granules. It suggests that the granules of migrating mast cell became visible to acid phosphatase activity by a physical force such as contact stimulation, and that a part of mast cells remigrate from the venous wall to other places by the blood flow. Furthermore, hepatic mast cells were revealed to contain both endothelin-1 and histamine in their granules by immunocytochemistry. As these substances have an activity of stronger venous constriction, it seems that the mast cells play an important role in the blood flow regulation of the canine liver, mast cell, monocyte.

Perivenous localization of insulin receptor protein in rat liver, and regulation of its expression by glucose and oxygen in hepatocyte cultures.

Insulin stimulates glucose utilization in the liver, which occurs mainly in the less aerobic, perivenous, zone. Accordingly, the insulin receptor protein was predominantly expressed in this area, although the insulin receptor mRNA was homogeneously distributed. In hepatocyte cultures venous O(2) partial pressure (pO(2)) induced insulin receptor protein expression. High glucose concentrations enhanced insulin receptor protein under arterial and venous pO(2). The induction of insulin receptor protein by venous pO(2) would explain its zonated expression.

Detection of mononuclear cells as the source of the increased tissue factor mRNA in the liver from lipopolysaccharide-treated rats.

Tissue factor (TF) triggers the coagulation cascade reaction in vivo. Overexpression of TF mRNA is one leading cause of disseminated intravascular coagulation and thrombosis-related organ failure. In response to lipopolysaccharide (LPS) stimulation, various cell types can produce TF mRNA in vitro. However, there is currently no agreement on what types of cells in the liver overexpress TF mRNA after LPS treatment. For the first report, we found the increased TF mRNA with reverse transcription-polymerase chain reaction (RT-PCR), and confirmed a fourfold increase (p<0.001 vs. control, t-test) of the TF mRNA level with RT-competitive PCR in the liver of LPS-treated (2.0 mg/kg i.v. injection) rats. There was no significant difference in the glyceraldehyde-3-phosphate dehydrogenase mRNA level between LPS-treated rats and control rats. To clarify the localization and cellular source of LPS-induced TF mRNA, we performed in situ hybridization analysis with [35S]-labeled oligonucleotides probes, which we originally designed. We detected intense signals of TF mRNA in mononuclear cells but not in endothelial cells around the hepatic vein of LPS-treated rats. In this study, we showed that the TF mRNA level induced by LPS treatment, which may indicate mononuclear cells associated, significantly increased in the liver of rats. These results will provide circumstantial support for the therapeutic strategy that mononuclear cell should be one of the target cells to be treated in the early phase of disseminated intravascular coagulation in the liver, and that the need to suppress its overexpression of TF mRNA is essential for preventing hypercoagulable condition.

Echogenicity of hepatic versus portal vein walls revisited with histologic correlation.

The portal vein wall typically is hyperechoic over a wide range of beam-vessel angles, whereas the hepatic vein wall is hyperechoic only when the incident beam and the vessel are perpendicular. This has been attributed to marked discrepancies in mural thickness, collagen content, or perivascular fat between portal and hepatic veins. We evaluated histologically the walls of portal and hepatic veins using three cadaveric livers. For vessels with luminal diameter above 2 to 3 mm, hepatic vein and portal vein wall thicknesses were similar such that portal vein walls were not more than 50% thicker than those of hepatic veins of comparable size. Hepatic vein walls were mostly composed of parallel, tightly packed collagen fibers. In contrast, portal vein walls were composed of loosely arrayed, nonparallel connective tissue fibers which were separated by multiple intervening spaces and only a minority of which were collagenous. Perivascular fat was not identified adjacent to intrahepatic vessels beyond the liver hilus. The marked differences in echogenicity between portal vein and hepatic vein walls typically observed at ultrasonography thus cannot be attributed to differences in mural thickness, collagen content, or perivascular fat between these vessels. Rather, the distinct composition of the hepatic vein wall renders it a specular reflector, which is hyperechoic only when the angle between the ultrasound beam and the vessel wall is close to 90 degrees, whereas the composition of the portal vein wall enables it to appear hyperechoic at a wide range of beam-vessel angles.

Superoxide generation in neutrophils from hepatic vein in patients undergoing hepatectomy.

The present study was carried out to determine whether neutrophils could be activated to increase superoxide and myeloperoxidase production during liver surgery in clinical settings. We measured superoxide production in polymorphonuclear leukocytes (PMNs) obtained from the radial artery and hepatic vein during hepatectomy. We also determined plasma myeloperoxidase (MPO) as a marker of activation of the neutrophil. Blood samples were obtained from radial artery and from hepatic vein before operation and immediately after hepatectomy. Superoxide generation in PMNs from radial artery showed no significant change during hepatectomy, while oxidant generation in PMNs from hepatic vein increased after hepatectomy (from 40.5 +/- 4.20 to 44.8 +/- 4.80 nmol/10(6) cells/30 min; p < 0.05). MPO in the plasma obtained from hepatic vein also increased significantly after hepatectomy (from 166.6 +/- 23.0 to 225.4 +/- 26.2 micrograms/L; p < 0.05). The results show that neutrophils are activated locally in the liver for enhanced release of superoxide during hepatectomy, suggesting that these oxidant species may be involved in post hepatectomy liver damage.