Hepatic Endothelium Research Articles

Vascular adhesion protein 1 mediates binding of T cells to human hepatic endothelium

BACKGROUND & AIMS: Molecules that regulate T-cell adhesion to hepatic endothelium and thereby recirculation of T cells to the liver are poorly understood. Because the adhesion molecule vascular adhesion protein-1 (VAP-1), which mediates lymphocyte binding to lymph node endothelium, is expressed on hepatic endothelium, it could play a role in regulating T-cell recruitment to the liver. The aim of this study was to investigate the distribution of VAP-1 expression in human liver and the ability of VAP-1 to support T-cell binding to hepatic endothelium in vitro. METHODS: Hepatic VAP-1 expression was investigated using immunohistochemistry and specific monoclonal antibodies, and VAP-1-mediated adhesion to hepatic endothelium was investigated with a tissue-binding adhesion assay using human liver sections. RESULTS: VAP-1 was expressed on sinusoidal and vascular endothelium in non-inflamed liver and in inflamed liver from patients with either allograft rejection or primary biliary cirrhosis. T cells from healthy donors bound to hepatic endothelium when added to noninflamed liver sections; this binding was inhibited by a specific anti-VAP-1 antibody but not by antibodies to intercellular adhesion molecule 1, lymphocyte function--associated antigen 1, or very late after activation (antigen) 4. VAP-1--mediated adhesion was unaffected by T-cell activation with phorbol ester. CONCLUSIONS: VAP-1 is constitutively expressed on hepatic endothelium and mediates T-cell adhesion to hepatic endothelium in vitro. VAP-1 could play a critical role in regulating T-cell recirculation to the liver in vivo. (Gastroenterology 1996 Feb;110(2):522-8)

THE EXPRESSION OF ADHESION MOLECULES OF THE INTRAHEPATIC VASCULAR ENDOTHELIAL CELLS IN HEPATECTOMY

The expression of vascular adhesion molecules and neutrophil adherence were investigated in the liver to evaluate the adverse effects of a temporary interruption of the hepatic inflow (Pringle's maneuver) during hepatectomy. In liver tissue specimens obtained from 16 patients (10 with liver cirrhosis (LC) and 6 without LC), immunohistochemical staining was used to detect the expression of granular membrane protein-140 (GMP-140), endothelial leukocyte adhesion molecule-1 (ELAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by the hepatic vascular endothelium. In addition, neutrophil elastase was immunostained. After hepatectomy, the expressions of GMP-140 and VACM-1 were significantly higher in patients with LC than in those without LC. There was weak expression of ELAM-1 in the cirrhotic liver which was observed in 2 cases, but no expression in the non-cirrhotic liver. The adherent neutrohil count in liver tissue after hepatectomy was significantly higher in LC patients than that before hepatectomy as well as than that of non-LC patients. In conclusion, Pringle's maneuver enhances the hepatic neutrophil adhesion by upregulating the expression of endothelial adhesion molecules during an early period after hepatectomy, which may cause damage to the remnant liver in LC patients.

Vascular impairment in patients with primary biliary cirrhosis.

Experimental and clinical observation suggest that patients with primary biliary cirrhosis (PBC) have endothelial dysfunction. Postischemic digital blood flow, nailfold capillaroscopy, von Willebrand factor (vWf) and tissue-type plasminogen activator (t-PA) plasma levels were examined in 59 PBC patients. Forty-six subjects (15 with liver diseases other than PBC, 11 hypercholesterolemics, 20 healthy subjects) served as controls. PBC versus healthy controls (209.8 +/- 1.4% and 16.54 +/- 1.44 ng/ml vs. 120.2 +/- 1.4% and 9.91 +/- 1.49 ng/ml; p<0.001) and related to bilirubin (r = 0.38, p<0.02; r = 0.47, p<0.0005, respectively). vWf was also increased in other liver diseases (249.9 +/- 1.7%; p<0.001) and related to bilirubin (r = 0.59, p<0.05). Postischemic finger blood flow negatively correlated with vWf(p<0.05 or less). Our data indicate that PBC patients have microvascular disease. Whether vessels other than those of the fingers were involved remained unclear. vWf and t-PA might reflect a dysfunction of teh hepatic vascular endothelium.

Liver ultrastructure of juvenile Atlantic salmon (Salmo salar).

Light and transmission electron microscopy of the liver of juvenile Atlantic salmon (Salmo salar) reveals a tubular arrangement of parenchymal cells, with biliary passages typically located at the center of tubules. Hepatocytes generally contain a single nucleus surrounded by a cuff of rough endoplasmic reticulum (RER), with many round to elongate mitochondria associated with the perinuclear RER. Whereas glycogen deposits are common and usually lie at the cell periphery, parenchymal cells seldom contain lipid droplets. Golgi complexes and heterogeneous dense bodies also occur in many hepatocytes, often in close proximity to bile canaliculi. Numerous microvilli from hepatocytes extend into the subendothelial space of Disse, which is also the location of stellate fat-storing cells. Interhepatocytic macrophages, sometimes containing prominent phagolysosomes and residual bodies, are common in the liver. The intrahepatic biliary system consists of intercellular canaliculi, bile pre-ductules, ductules, and ducts. In contrast to some other teleosts, the liver of the Atlantic salmon contains no intracellular bile canaliculi or Kupffer cells. The hepatic endothelium, arterioles, and perivenous regions are also described.

THE EFFECTS OF PRETRANSPLANT CYCLOSPORINE THERAPY ON RATS GRAFTED WITH TWELVE-HOUR COLD-STORED LIVERS—WITH SPECIAL REFERENCE TO REPERFUSION INJURY

The effect of pretreatment with cyclosporine on liver preservation was studied using a rat liver transplant model. In a preliminary 1-week survival study, 59 liver transplants were performed. In group A, neither donors nor recipients were treated. In group B, the recipients were pretreated by a 3-day course of CsA (10 mg/kg/day p.o.), but the donors were untreated. In group C, the donor rats were pretreated for 3 days with the same doses of CsA as in group B, but the recipients were not treated. The donor livers in each group were stored for 12 hr at 4 degrees C with Eurocollins solution and transplanted to the recipients. The CsA pretreatment to recipients (group B) significantly improved 1-week survival (57.1%, 8/14, P less than 0.01 versus control group A; 0%, 0/14 or group C; 14.3%, 2/14). To study lipid peroxidation and morphology, 72 rat livers were studied in 9 groups. In summary, CsA pretreatment to recipients resulted in suppression of the increase in MDA levels and amelioration of endothelial injury after transplantation. On the other hand, donor pretreatment exerted dual effects on the grafts; it ameliorated endothelial injury after reperfusion, but its hepatotoxic action exacerbated hepatocellular damage during hypothermic storage. Our study suggests that CsA pretreatment, particularly to recipients, is beneficial in liver preservation for hepatic transplantation. The mechanisms are discussed with regard to ischemia/reperfusion injury to hepatic endothelium.

Different isoforms of human FcRII distinguished by CDw32 antibodies.

The Third and Fourth International Workshops on Leucocyte Differentiation Antigens identified six mAb, designated CDw32, reacting with human Ig FcR type II (FcRII). We have examined the immunohistochemical and immunocytologic reactivities of these antibodies and find that the antibodies could be divided into three classes of reactivity: 1) antibodies IV.3, CIKM3, and CIKM5 reacted with monocytes, macrophages and neutrophils; 2) antibodies KB61 and 41H.16 gave strong reactions with B lymphocytes, placental and hepatic endothelium, and weaker reactions with monocytes, macrophages, and neutrophils; 3) antibody 2E1 gave an intermediate reaction pattern. Immunoprecipitation from U937 cell lysates showed that antibodies KB61 and 41H.16 recognized Mr 41,000 and Mr 37,000 molecules whereas the other antibodies detected a Mr 42,000 molecule. Preclearing with antibody KB61 removed the Ag recognized by the other five antibodies confirming the identity of the Ag and demonstrating reactivity of KB61 with the Mr 42,000 molecule. Antibodies KB61 and 41H.16 precipitated a Mr 41,000 molecule from B lymphocytes. Flow cytometry and immunoprecipitation studies of cells transfected with cDNA clones coding for two isoforms of FcRII showed that all six of the antibodies react with both transfectants but the only immunoprecipitations were obtained using KB61 and 41H.16 and one of the transfectants. The protein sequence of KB61 Ag isolated from leukemic B cells showed close homology with the proteins encoded by the cDNA clones but diverged in the intracytoplasmic carboxyl-terminal region. It was concluded that preferential recognition of one or more of the numerous isoforms of FcRII underlies the differing reaction patterns of CDw32 antibodies.

Lipoprotein synthesis and secretion by cultured hepatocytes

Hepatic parenchymal cells are situated on double-cell plates. The highly fenestrated hepatic endothelium offers little restriction to the passage of high-molecular-weight substances. Thus, the hepatocyte, with little or no restriction at the endothelial boundary, comes in contact with plasma macromolecules at high concentrations. The cultured hepatocyte system can be a valuable model for investigation of lipoprotein synthesis and secretion. Many experiments not possible with other models can be performed using this system. For some questions, data obtained from the hepatocyte model may be difficult to interpret in regard to the in vivo state. For this reason, hypotheses derived from data obtained using the hepatocyte culture system should be examined further in vivo . There is no reason to assume that differences between cultured hepatocytes and the liver in vivo exist in regard to the intrahepatic processes which regulate lipoprotein synthesis and secretion. However, the environmental, hormonal, and nutritional conditions in culture are markedly different than those which occur in vivo . Understanding the basis of these differences is by itself valuable to the knowledge of physiology. Depending on the questions examined, these differences either can be used to aid the investigator or may be prohibitive in affording physiologically relevant conclusions.

Induction of DR/IA antigens in human liver allografts. An immunocytochemical and clinicopathologic analysis of twenty failed grafts.

Twenty failed human liver allograft specimens obtained at the time of retransplantation procedures were studied using a panel of monoclonal antibodies (T11, T4, T8, NK, B1, OKM1, OKM5, Ia, DR). A clinicopathologic analysis was used to distinguish between graft failures secondary to rejection (n = 10) and those due, at least in part, to other causes (n = 10). T lymphocytes constituted the major infiltrating cellular population in the liver in rejection cases, but significant numbers of B cells and monocytes/macrophages were present also. Following transplantation, but not before, the bile duct epithelium, as well as portal and central vein and hepatic artery endothelium expressed DR/Ia antigens. These structures are preferential targets of the rejection reaction. The selective destruction of bile ducts in livers undergoing rejection was manifested in these patients by striking elevations of serum gamma glutamyl transpeptidase (GGTP) activity, a marker of biliary epithelial damage. The induced expression of DR/Ia antigens on structures targeted for immune destruction may be an important event in the pathogenesis of liver allograft rejection.

血管壁の微細構造と物質輸送経路

The pathways of material transport across the endothelium at the ultrastructural level were examined in different kinds of blood vessels by using tannic acid or horseradish peroxidase as a tracer. Freeze-fracture replicas from the endothelial cells of the aorta and basilar artery of the rat were also made and examined by electron microscopy.Tracer materials could be transported through the cytoplasm of the endothelial cells by means of vesicles linked with pinocytotic activity, transient transendothelial channels formed by serial fusion of vesicles, and fenestrae. The intercelluar gaps of the hepatic sinusoid endothelium could also be a pathway for tracer materials. In the aorta the intercellular junction between adjacent endothelial cells could be a passageway for both tannic acid and horseradish peroxidase, whereas in the basilar artery, these materials could not pass through that junction beyond the tight junction area. Freeze-fracture replicas showed that the strands of intramembrane particles at the tight junction constitute continuous complex networks in the basilar artery whereas those in the aorta were simple in organization, consisting of a few discontinuous strands accompanied with sporadic gap junctions. The observation in freeze-fracture replicas may well explain the fact that tannic acid and peroxidase cannot be transported through the intercellular clefts beyond the tight juction in the basilar artery.

家兎大動脈内皮の培養について

Since Lewis tried to cultuer hepatic endothelium, several authors had reported the in vitro culture of animal endothelium. However, the successive culturing for long time was not performed except by Kitsukawa or Pomerat et al. The author tried to culture the rabbits aortic endothelium in vitro over a year. 0.2% trypsin solution was adopted to gather the endothelial cells from aortic wall. The cells were cultured by 10% fetal calf serum in Eagle medium, and the 8 times “cloning” were done to get a pure strain of the endothelium.1. Cultured endotheliums were asteroid or short fusiform in shape at early stage and changed their shape gradually to fibroblast-like long fusiform types.2. Fibroblasts were also cultured by the same method from rabbits aortic adventitia as the control for cultured endothelium.3. Electron-microscopically, endothelial cells had terminal bars in junctional complex, pinocytotic vesicles and band-like microfilaments which were seen also in human endotheliums.4. The results of C. P. E. test (cytopathic effect test) showed different natures between cultured endothelium and fibroblast (TABLE 1).5. Enzymologically, the cultured endothelium showed marked fibrinolytic activitied which were estimated about 4-5 times greater than that of cultured fibroblast.

The fundamental physiological mechanism of anaphylaxis.

The following is our conception of the fundamental physiological mechanism of canine anaphylaxis, and constitutes our present working hypothesis with other animal species.We assume that the capillary endothelium is the initial point of anaphylactic attack and defense. We further assume that in dogs the different capillary systems have different susceptibilities to the anaphylactic insult, the capillaries of the liver having the greatest susceptibility.On intravenous injection of the usual doses of specific foreign protein into sensitized dogs, the hepatic endothelium alone is unable to resist the anaphylactic insult. There is a sudden increase in capillary permeability in this organ, with the rapid passage of foreign protein and altered blood plasma into the hepatic tissue spaces.The hepatic parenchyma, in consequence, is immediately thrown into exaggerated, possibly atypical functional activity. The chemical products from this activity pass rapidly into the circulating blood, on account of the increased ...

STUDIES ON ENDOTHELIAL REACTIONS

STUDIES ON ENDOTHELIAL REACTIONS

AN EXPERIMENTAL STUDY OF THE HISTOGENESIS OF THE MILIARY TUBERCLE IN VITALLY STAINED RABBITS

AN EXPERIMENTAL STUDY OF THE HISTOGENESIS OF THE MILIARY TUBERCLE IN VITALLY STAINED RABBITS