ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01788.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractFenestrae control the exchange of fluids, dissolved compounds and small particles between the blood and the space of Disse, and are primarily limited at one side by parenchymal cells. We recently described a simple and rapid method for the isolation, purification and cultivation of rat liver sinusoidal endothelial cells. With regard to the purity and morphology of liver endothelial cells, a detailed microscopic study was performed. Purity and viability after selective adherence was 74 and 95%, respectively. Liver endothelial cell purity was further enhanced to about 95% during adherence and spreading on collagen after 8 h of culture. Liver endothelial cells isolated by this method provide a viable cell population, enabling the study of structure and function of these cellsin vitro.We investigated the cytoskeleton associated with fenestrae and sieve plates of liver endothelial cells. Cultured cells were slightly fixed and treated with cytoskeleton extraction buffer containing 0.1 % Triton. Whole mounts of extracted liver endothelial cells were prepared for scanning and transmission electron microscopy. Extracted liver endothelial cells show an integral, intricate cytoskeleton. Sieve plates and fenestrae are clearly delineated by cytoskeleton elements. Fenestrae are surrounded by a filamentous, fenestrae‐associated cytoskeleton ring with an average filament thickness of 16 nm. Additionally, sieve plates are surrounded and delineated by microtubuli, which form a network together with additional branching cytoskeletal elements. Microtubuli are sometimes found delineating linear arrangements of fenestrae. In conclusion, liver endothelial cells possess a cytoskeleton, that defines and supports sieve plates and fenestrae. Fenestrae‐associated cytoskeleton rings are involved in determining the size of fenestrae. The fenestrae‐associated cytoskeleton therefore probably controls the important hepatic function of endothelial filtr

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01792.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractIto cells, located in the space of Disse, extend their numerous long cytoplasmic processes to surround the sinusoidal wall. Conventional and immune electron microscopy demonstrates abundant microfilaments and a great amount of actin and myosin in these cytoplasmic processes. These morphological findings suggest the possibility of control of the sinusoidal circulation by their contraction. Two mechanisms may be involved in their contraction: namely nervous and humoral factors. Ito cells, often in close contact with the nerve endings, which contain many granules of substance P (SP), have numerous receptors for this peptide. Ito cells also have receptors for endothelin‐I (ET‐1), more commonly found in the periportal area of the hepatic lobule. Experimental studies using cultured Ito cells showed their contraction following treatment with ET‐1 or SP. These results suggest that Ito cells play an important role in the regulation of hepatic sinusoidal circul

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01806.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDuring the prereplicative period of liver regeneration the changes in the levels of mRNA for tumour necrosis factor‐α (TNF‐α) and its receptors were nearly synchronous. The mRNA levels reached their maximum 1 – 3 h after operation and exceeded the values for intact animals about tenfold. Lipopolysaccharide stimulation induced an increase in TNF‐α and TNF receptor production comparable with that occurring during regeneration.Nitric oxide (NO) production in the regenerating liver was determined by electron paramagnetic resonance (EPR) spectroscopy. The first increase in NO production occurred approximately 1 h after partial hepatectomy (PHE). The second and more pronounced peak of NO production was observed about 6 h after PHE when the hepatocytes entered the first cell cycle; it originated mainly from these cells. The consequent minimum of NO synthesis coincided with the maximal rate of DNA synthesis. The third gradual rise of NO production was seen at the transit from the first to the second cell cycle of the hepatocytes and the entrance of the non‐parenchymal cells into proliferation.Hepatocytes, Kupffer and endothelial cells were isolated from livers after PHE. They were found to start their main NO production in the described sequence at the times corresponding to their respective entrance into the cell cycle. The maxima of NO synthesis were inversely correlated to the DNA‐synthesizing activity of the indivi

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01789.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractKupffer cells (KC) and gut‐derived bacterial endotoxin have been implicated in the aetiology of alcoholic liver disease. Usingin vivomicroscopic methods, we have shown that ethanol ingestion in mice causes a dose dependent increase in leucocyte adhesion and endothelial cell swelling in hepatic sinusoids. Activation of KC is elicited at low doses while depression occurs at high doses and with chronic exposure. The responses are exacerbated in the presence of endotoxaemia or sepsis and are not seen in endotoxin‐resistant animals, implicating a role for endotoxin in the ethanol‐induced inflammatory response. In addition, the responses are abolished with anti‐TNFαsuggesting that TNFαis a primary mediator of these events. Nitric oxide (NO) initially appears to play an important role in these events by stabilizing the TNFα‐mediated hepatic microvascular inflammatory response to acute ethanol ingestion, thereby helping to protect the liver from ischaemia and leucocyte induced oxidative injury. Finally, an ongoing clinical study has confirmed a mild systemic endotoxaemia in patients hospitalized for alcoholic liver disease. All of these results support important roles for endotoxin, cytokines, nitric oxide and sinusoidal lining cells in the pathophysiology of liver injury resulting from ethanol alone or in combination wi

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01790.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractKupffer cells have been implicated in mechanisms of pathophysiology following liver transplantation. Recently, postoperative injury in ethanol‐induced fatty liver has been evaluated because fatty livers often fail following transplantation. The low‐flow, reflow liver perfusion model was used to study the role of Kupffer cells (KC) in reperfusion injury to fatty livers from rats fed a diet containing ethanol for 4–5 weeks. Treatment with GdCl3, which selectively destroys KC, decreased cell death significantly. Thus, destruction of KC minimized hepatic reperfusion injury, most likely by inhibiting free radical formation and improving microcirculation.Since it was demonstrated recently that destruction of KC prevented the hypermetabolic state observed with acute alcohol exposure, their involvement in events leading to alcohol‐induced liver disease was investigated. In rats exposed to ethanol continuously via intragastric feeding for up to 4 weeks, GdCl3treatment prevented elevation of aspartate aminotransferase (AST) and dramatically reduced the average hepatic pathological score. These results indicate that KC participate in the early phases of alcohol‐induced liver injury.Endotoxaemia occurs in alcoholics and activates KC; therefore, we evaluated the effect of minimizing bacterial endotoxin by intestinal sterilization with the antibiotics polymyxin B and neomycin. Antibiotics diminished plasma endotoxin levels significantly and prevented ethanol‐induced increases in AST values. These results indicate that endotoxin is involved in the mechanism of ethanol‐induced liver injury.A six‐line radical spectrum was detected with electron paramagnetic resonance spectroscopy in bile from alcohol‐treated rats which was blocked by GdCl3. The free radical adducts had hyperfine coupling constants characteristic of lipid‐derived free radical products. In conclusion, these studies demonstrate that KC are involved in reperfusion injury to ethanol‐induced fatty livers and hepatic injury due to long‐term

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01791.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAn additional administration of high dose ethanol to chronic alcohol‐fed rats led to a decrease in endotoxin clearance and an increase in endotoxin accumulation in the spleen accompanied by an elevation of tumour necrosis factor (TNF) levels in the portal vein. Endotoxin uptake and TNF production by Kupffer cells (KC) and splenic macrophages in the chronic ethanol load rats were significantly greater than those in the control rats. When these cells were precultured in the medium containing 10 to 100mmol/L ethanol, the endotoxin uptake and TNF production of KC were decreased. However, this did not affect the endotoxin uptake and TNF production of splenic macrophages.The hepatic production of endotoxin binding protein was increased when KC were preincubated in the medium containing ethanol and the resultant culture supernatant was added to the hepatocyte culture system. This endotoxin binding protein was proved to enhance the uptake of endotoxin and suppressed the production of TNF in the KC. When KC and hepatocytes were isolated from chronically alcohol‐fed rats, further addition of ethanol to the culture medium of KC did not affect the hepatic production of endotoxin binding protein. The increase in hepatic production of endotoxin binding protein may serve as a defence mechanism against endotoxicity. There is a possibility that an impairment of this defence mechanism has a pivotal role in the development of endotoxaemia and endotoxicity in chronic alcohol

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01793.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractWe characterized the structural changes of sinusoidal endothelial cells in chronic ethanolfed rats and rats with cirrhosis induced by thioacetamide. The phenotypic changes of sinusoidal endothelial cells in fibrotic rats induced by thioacetamide and the reversibility of these changes were also investigated under transmission and scanning electron microscopy, regular microscopy and by immunohistochemistry with laminin and von Willebrand factor antibodies. The diameter and porosity of sinusoidal endothelial fenestrations were increased in chronic ethanol‐fed rats without liver fibrosis, however, they decreased within 4 weeks of the cessation of thioacetamide treatment. A basement membrane‐like structure in Disse's space was noted 6 weeks after thioacetamide treatment. Laminin was detected in Disse's space after 4 weeks and von Willebrand factor was detected in the cytoplasm as granular fluorescence after 6 weeks of thioacetamide treatment. Reversibility of the phenotypic changes of the sinusoidal endothelial cells was demonstrated in fibrotic liver of rats that received thioacetamide for 6 weeks after long‐term discontinuation of thioacetamide administration. These results indicate that the structural and immunohistochemical characteristics of sinusoidal endothelial cells change in chronic ethanol‐fed rats and fibrotic rats and these changes are rev

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01794.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractSinusoidal endothelial cell damage is produced by activation of hepatic macrophages after endotoxin administration in rats pretreated withCornyebacterium parvumor undergoing 70% hepatectomy. Such damage causes fibrin deposition in the hepatic sinusoids leading to massive hepatic necrosis. In theC. parvummodel, cytotoxic mediators, such as tumour necrosis factor (TNF)α and superoxide anions released from activated hepatic macrophages directly destroy sinusoidal endothelial cells. In contrast, in the partial hepatectomy model, endothelial cell damage occurs as a result of fibrin deposition due to derangement of the coagulation equilibrium regulated by tissue factor and thrombomodulin expressed on hepatic macrophages and sinusoidal endothelial cells, respectively. Immunohistological examination revealed that the expression of ICAM‐1 in sinusoidal endothelial cells and LFA‐1 in hepatic macrophages was greater in both models than in normal rats preceding the development of hepatic necrosis. The extent of liver injury was significantly attenuated by treatment with monoclonal antibodies against both adhesion molecules in theC. parvummodel, but aggravated in the partial hepatectomy model, compared to control rats. We conclude that adhesion of activated macrophages to endothelial cells via LFA‐1 and ICAM‐1 in the hepatic sinusoids is essential for endothelial cell destruction in theC. parvummodel, but can act protectively against provocation of fibrin deposition in the hepatecto

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01795.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractMorphological and phenotypical data indicate that liver sinusoids contain a heterogeneous population of lymphocytes of which large granular lymphocytes are only one element. It is suggested that the term of liver‐associated lymphocytes (LAL), which encompasses all sinusoidal lymphocytes, be used for this fourth sinusoidal cell type.Studies realized by flow cytometry on isolated cells have shown that human LAL differ phenotypically from peripheral blood lymphocytes (PBL). LAL are characterized by a three‐fold increase in the percentage of cells presenting the CD56 antigen, a natural killer (NK) marker, but also an increase in the percentage of CD8 cells and a decrease in the percentage of CD4. Furthermore, within the CD56+ LAL population, 95% of cells are CD3+/‐ CD16‐, whereas the majority of CD56+ cells in PBL are CD3‐/CD16+. These differences do not seem to depend on liver pathology since no differences were found in the LAL phenotype, for all markers analysed, between patients with liver metastasis or with benign liver tumours. Liver sinusoids also harbour T cells bearing the γ/δ chains with a repertoire of V gene arrangements which differs from that found in PBL from the same patients, confirming a site‐specificity.Functionally, LAL were shown to possess a higher level of NK cell activity against K‐562 cells than PBL. LAL also expressed a lymphokine activated killer (LAK) activity against NK‐resistant cell lines (Raji cells), whereas no such activity was detected in PBL from the same patients. Interestingly, LAK‐activity from LAL isolated from patients with liver metastases was dramatically decreased compared to that from LAL isolated from patients with benign liver disease. The level of LAK activity of LAL situated distant to the malignant tumour was higher than that obtained from LAL close to the tumour, thus suggesting that cytotoxic lymphocyte capabilities could be inhibited by tumoral celis. LAL differ, both quantitatively and qualitatively, from PBL in the expression of cellular adhesion molecules. Precise mechanisms of their homing orin situdifferentiation must

ISSN:0815-9319    

DOI:10.1111/j.1440-1746.1995.tb01796.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY