Biomedical subjects

E Wisse

Publications and source records attributed to E Wisse.

At least 55 records · Page 3Linked to original sources

PubMed1992

High deformability and motility of lymphokine-activated killer cells in vitro and in vivo.

The motility and deformability of lymphokine-activated killer cells, purified by their adherence to plastic (A-LAK cells), was investigated in vivo and in vitro. In vitro, A-LAK cells were observed as intrinsically motile cells. They continuously changed their shape while forming protopods or pseudopods and crawled over the culture surface. A-LAK cells were able to migrate across micropores of 3 microns diameter, which was three times smaller than the average diameter of an A-LAK cell. Even in the absence of serum factors and of interleukin-2 (IL-2), more than half of the inoculated cells migrated across such micropore membranes within 18 h. Electron microscopic examination of these micropore membranes showed that the A-LAK cells were highly deformable. A-LAK cells also migrated across a confluent monolayer of endothelium-like 10T1/2 cells. After 24 h incubation on the monolayers, about 20% of the A-LAK cells were found underneath the monolayer. There, they actively moved in the narrow space between the monolayer and the bottom of the culture dish. In vivo IL-2-activated cells showing the large granular lymphocyte morphology accumulated in the hepatic microvasculature. Electron microscopic observations indicate that these cells did not accumulate by mechanical entrapment due to rigidity and size but rather by adherence to the endothelial lining of the sinusoidal capillaries. This also appeared to be the case for adoptively transferred A-LAK cells, which were seen to be attached to the capillary wall. These observations stress the importance of adhesive entrapment to explain the accumulation of intravenously transferred LAK cells in the vascular beds.

Animals↗

PubMed1992

Pit cells in the liver.

There is now sufficient evidence to consider the pit cells as a hepatic, intrasinusoidal population of large granular lymphocytes. They should be considered as resident sinusoidal cells of the liver, even if they depend on a continuous influx of precursor cells from the bone marrow, since they differ in several phenotypic and functional respects from their circulating (precursor) counterparts. There is growing evidence that a comparable population of activated or further differentiated, liver-specific pit cells (or LGL) is not only present in the rat but also in the human liver. Pit cells exert high spontaneous cytotoxic activity against tumor cell lines and may act as a primary defense barrier to metastasizing tumor cells and to virus infections. The total number of pit cells in the liver can be greatly increased by the administration of interleukin-2 or by a variety of biological response modifiers, which may represent a mechanism of defense against disease. Their involvement in liver pathologies deserves more attention.

Animals↗

PubMed1992

Tenascin expression in human chronic liver disease and in hepatocellular carcinoma.

Tenascin is an oligomeric glycoprotein of the extracellular matrix synthesized during embryonic development. It is prominently expressed in a variety of tumors. The role of tenascin in liver tissue is, however, unknown. We used immunocytochemistry to define the localization of tenascin and compare this with the localization of non-collagenous proteins, such as laminin and fibronectin, in normal human liver and pathological liver from patients with chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. In normal liver, tenascin expression was localized along the sinusoidal and vascular wall. In fibrotic liver, tenascin was also observed in the region between the hepatic parenchyma and the fibrosing portal tracts, especially in areas of piecemeal necrosis in chronic hepatitis. Immuno-EM study of liver tissue in chronic hepatitis strongly suggested the synthesis and secretion of tenascin by fat-storing cells into the space of Disse. In hepatocellular carcinoma, tenascin was expressed in both the capsule and lobular septa, but not in the sinusoidal walls of the tumors. These results led us to postulate a close relationship between the occurrence of this protein and disease processes such as fibrosis and cancer invasion.

Carcinoma, Hepatocellular↗

PubMed1992

Liver cell heterogeneity: functions of non-parenchymal cells.

The normal hepatic sinusoid is formed or lined by four different cell types, each with its specific phenotypic characteristics, functions and topography. Endothelial cells constitute the closed lining or wall of the capillary. They contain small fenestrations to allow the free diffusion of substances, but not of particles like chylomicrons, between the blood and the hepatocyte surface. This filtering effect regulates the fat uptake by the liver. Sinusoidal endothelial cells also have a pronounced endocytotic capacity which makes them an important part of the reticuloendothelial system. They are also active in the secretion of bioactive factors and extracellular matrix components of the liver. Recently, a zonal heterogeneity of the endothelial lining has been reported with regard to its filtering capacity (fenestration) and binding capacity for lectins and cells. Kupffer cells are intrasinusoidally located tissue macrophages with a pronounced endocytotic capacity. They are potent mediators of the inflammatory response by the secretion of a variety of bioactive factors and play an important part in the immune defense. A zonal heterogeneity has been established with regard to the endocytotic capacity and cytotoxic function. Pit cells are now known to represent a liver-associated population of large granular lymphocytes. They have the capacity to kill tumor cells and probably also play a role in the antiviral defense of the liver. In addition, pit cells may have a growth-regulatory function of the liver. They are known to be numerically more prominent in the periportal region, as is also the case for Kupffer cells. Fat-storing or Ito cells are present in the perisinusoidal space of Disse and are thought to represent the main hepatic source of extracellular matrix components. They are also the main site of vitamin-A storage. Fat-storing cells are more numerous in the periportal region than in the central region of the hepatic acinus. The periportal cells also store higher amounts of vitamin A. Sinusoidal cells may be considered to represent a functional unit at the border line between the hepatocytes or parenchymal cells and the blood. They participate in various liver functions and liver pathologies and our knowledge about this is growing. The heterogeneity of these cell types and possible cooperations between them and the hepatocytes may add to our understanding of liver functions.

Animals↗

PubMed1991

Effect of warfarin on early rat tooth development.

Rat pups were treated from birth to 5 days of age with the vitamin K antagonist warfarin in order to investigate possible functions of the vitamin K-dependent dentin Gla protein (DGP) in tooth development. Warfarin completely eliminated the immunocytochemically detectable DGP which is a prominent feature of dentin in control rat pups, and also caused an increased concentration of DGP in odontoblasts. Warfarin treatment did not affect the ultrastructure of cells or the extracellular matrix in the tooth germs. The width of the predentin layer, which is considered to be correlated with the rate of mineralization, was unchanged. These results are the first to demonstrate that warfarin treatment prevents the accumulation of DGP in dentin, and that the deposition of DGP has no influence on the overall rate of dentin matrix mineralization in tooth germs.

Animals↗

PubMed1991

Role of fat-storing cells in hepatic fibrogenesis. Retinoids as possible therapeutic agents.

In normal liver, fat-storing cells are the main storage site of vitamin A derivatives, mainly of retinyl palmitate and oleate. During liver injury, the phenotype of fat-storing cells alters dramatically. The cells gradually lose their fat-droplets, proliferate and synthesize large amounts of connective tissue molecules. In the present paper, we summarize the characteristics of fat-storing cells, review the role of fat-storing cells in development of hepatic fibrosis, and describe how retinoids affect the protein synthesis and proliferation of these cells.

Animals↗

PubMed1991

Tissue distribution, quantitation and proliferation kinetics of fat-storing cells in carbon tetrachloride-injured rat liver.

In this study, we have investigated the cell population kinetics of fat-storing cells in livers of rats intoxicated with CCl4. Fat-storing cells were identified in cryostat sections by immunoperoxidase staining of desmin. The peroxidase label was visualized using diaminobenzidine/hydrogen peroxide containing Ni2+ and Co(2+)-ions (Nico/diaminobenzidine method). In normal rats, we found 12.8 fat-storing cells/0.1 mm2 in periportal areas vs. 9.4 in pericentral fields. After one injection of CCl4, the number of pericentral cells increased gradually to reach a maximum of 39.4 cells/0.1 mm2 96 hr after injection. The desmin staining intensity of the pericentral fat-storing cells increased from 48 hr onward. At 72 to 120 hr, strongly stained cells were observed in pericentral areas and in bands of tissue between adjacent central veins, reminiscent of the connective tissue septa in fibrotic livers. In the periportal areas the number of fat-storing cells was not altered. After a second and third injection of CCl4, the number of cells increased further in the pericentral areas. When more than three injections were given, the pericentral fat-storing cell population reached a new steady state with the cell number being seven times higher than in control animals. Proliferation of fat-storing cells at different stages of CCl4 intoxication was studied by intravenous administration of 3H-thymidine, followed by combined desmin staining and autoradiography. Autoradiographical labeling of fat-storing cells was nearly absent in control animals and at 24 hr after a single CCl4 injection. At 48 to 96 hr, labeling indices of pericentral fat-storing cells were significantly higher than in control animals, with a maximum at 72 hr when 22.9% of the cells were labeled. After multiple injections of CCl4, labeling indices between 4.9% and 8.4% were found. We conclude that fibrogenesis is preceded by a strong expansion of the fat-storing cell population in the pericentral areas of the liver lobules and in bands of tissue between adjacent central veins. Local proliferation is an important mechanism underlying the expansion of this cell population.

Animals↗

PubMed1990

Characterization of a phenotypically and functionally distinct subset of large granular lymphocytes (pit cells) in rat liver sinusoids.

Pit cells, or large granular lymphocytes, with natural tumoricidal activity are found in the sinusoids of normal rat liver. Hepatic large granular lymphocytes are heterogeneous and can be subdivided into two subsets. These subsets were compared with peripheral-blood large granular lymphocytes and were found to differ phenotypically and functionally. Phenotypical differences included lower expression of the asialo-GM1 marker of natural killer cells, lower cellular density and many more small cytoplasmic granules in hepatic large, granular lymphocytes. Low-density hepatic large, granular lymphocytes were five to eight times more cytotoxic than blood large, granular lymphocytes on a per-cell basis as measured against YAC-1 cells and colon carcinoma cells. In addition, hepatic large, granular lymphocytes were able to lyse P-815 target cells, which are resistant to blood natural killer cells. Large, granular lymphocytes isolated from the liver also contained a subset with intermediate phenotypical and functional characteristics, possibly representing a transitional form between blood and "liver-specific" large, granular lymphocytes. The liver thus contains a specific population of highly activated or further differentiated large granular lymphocytes.

Animals↗

PubMed1990

Collagen type I and III occur together in hybrid fibrils in the space of Disse of normal rat liver.

Collagen type I and procollagen type III were localized at the ultrastructural level on ultrathin frozen sections of rat liver by the protein A-gold technique using affinity-purified primary antibodies. Both collagen type I and procollagen type III were localized on nearly all solitary and bundled fibrils in the space of Disse. Simultaneous localization of collagen type I and procollagen type III by a double-labeling procedure using protein A-gold probes of different sizes unequivocally demonstrated the presence of both collagens in the same fibrils. Measurement of the diameter of large numbers of collagen fibrils in the space of Disse of the rat liver showed a unimodal distribution of the fibril diameters around an average value of 62.4 nm (S.D. = 12.8 nm), and 91% of the collagen bundles contained less than 30 fibrils. Additional measurements on epoxy resin-embedded material of five biopsy specimens of normal human liver showed a comparable unimodal distribution of the fibril diameters around an average value of 57.2 nm (S.D. = 9.6 nm), and 74% of the bundles contained less than 60 fibrils. The latter observation demonstrates that human liver contains broader interstitial collagen bundles than rat liver. From these results, we conclude that the space of Disse of normal rat and human liver contains a uniform population of striated interstitial collagen fibrils. In the rat liver, these fibrils contain both collagen type I and procollagen type III. Therefore the concept that procollagen type III is predominantly localized in small diameter fibrils or bundles, whereas collagen type I is preferentially localized in thick ones, does not hold.

Animals↗

PubMed1990

Electron microscopic observations on the accumulation of large granular lymphocytes (pit cells) and Kupffer cells in the liver of rats treated with continuous infusion of interleukin-2.

Treatment schedules were investigated for in vivo induction of lymphokine-activated killer cells in the rat liver. Treatment of rats with continuous systemic or regional infusion of recombinant human interleukin-2 with a dose of 4 to 8 x 10(4) U/day during 7 days, resulted in an increase in number of large granular lymphocytes or pit cells in the liver up to 43 times normal. Kupffer cells, nongranular lymphocytes, monocytes and neutrophils also increased in number, but with a maximal fivefold increase this was much less pronounced than for large granular lymphocytes. Kupffer cells showed morphological signs of activation and were frequently seen in mitosis. Frequent mitoses were also observed for large granular lymphocytes, but not for other leukocytes. This indicates that the effect of interleukin-2 treatment on hepatic (sinusoidal) cells was primarily directed to large granular lymphocytes and Kupffer cells. The large granular lymphocyte accumulation occurred mainly intrasinusoidally, but they were also frequently observed in the space of Disse where they are not found in control rats. This may be explained partly by the observed damage or gaps in the endothelial lining. The intrasinusoidal large granular lymphocytes adhered to the endothelium and to Kupffer cells. Higher responses, for all cell types, were found when interleukin-2 was administered regionally, that is, through the hepatic artery rather than through the systemic route (jugular vein), although the differences were not statistically significant. Doses below 4 x 10(4) U/day did not result in significant increases of large granular lymphocytes in the liver.

Animals↗

PubMed1990

Ultrastructure and function of hepatic fat-storing and pit cells.

The present paper reviews the literature on the ultrastructure and function of sinusoidal fat-storing cells and pit cells in the mammalian liver. Ultrastructurally, fat-storing cells are characterized by the presence of cytoplasmic fat droplets, well developed rough endoplasmic reticulum; a Golgi complex; multivesicular bodies; one or two centrioles; and few, rather small, lysosomes. These lysosomes are sometimes associated with fat droplets. Fat-storing cells may bear a cilium and project characteristic cytoplasmic processes into the space of Disse. These processes contain microtubules and filaments. Fat-storing cells are the main storage site of retinol esters in the mammalian body. Moreover, these cells have the potential of synthesizing several connective tissue components including the collagens type I, III, and IV; fibronectin; laminin; heparan sulfate; chondroitin sulfate; and dermatan sulfate. Pit cells are polarized cells, with most organelles localized at one site of the nucleus near the cytocentre. They are characterized electron microscopically by the presence of dense cytoplasmic granules with a specific ultrastructure, by rod-cored vesicles, and by multivesicular bodies. It has recently been shown that pit cells have natural killer activity to certain tumor cells and have many features in common with large granular lymphocytes. They therefore may act in the liver as a first line of defense against neoplasia, metastasis, and viral infections.

Animals↗

PubMed1990

The role of bile acids in the development of endotoxemia during obstructive jaundice in the rat.

The role of bile acids in the development of endotoxemia during obstructive jaundice was studied in rats. Endotoxin was not found in portal and peripheral plasma of control rats. The bile ducts of seven rats were ligated. On day 7 following bile duct ligation, six animals showed portal endotoxemia and five peripheral. Oral administration of sodium ursodeoxycholate reduced this frequency to 1/7 for portal plasma and 0/7 in the case of peripheral plasma. Subsequently the influence of a bile salt mixture (85% taurocholate, 15% taurodeoxycholate) on the binding and uptake of Salmonella abortus equi lipopolysaccharide by cultured rat Kupffer cells was studied. In control preparations, the percentage cell-associated lipopolysaccharide increased with time and reached a plateau after about 2 h of incubation at 37 degrees C. In the presence of 0.3, 0.6 and 1 mumol bile salts/ml the cell-associated lipopolysaccharide was about 5%, 13% and 29% lower, respectively, of that in control cultures. Tauroursodeoxycholate (1 mM) did not inhibit the lipopolysaccharide uptake by cultured rat Kupffer cells. Based on these observations, it is likely that both phenomena, i.e., (a) the low amount of bile acids in the intestines and (b) the high serum bile acid level, account for the high frequency of endotoxemia in the peripheral blood during obstructive jaundice.

Administration, Oral↗

PubMed1990

Subcellular abnormalities of liver sinusoidal lesions in human hepatocellular carcinoma.

Liver sinusoidal lesions in 20 cases of human hepatocellular carcinoma (HCC) were examined with the electron microscope. Kupffer cells existed in the compact type of HCC. In area with pseudoglandular and trabecular cell patterns, Kupffer cells could not be observed. Only a few macrophages were distributed in the tumor tissues. Endothelial cells were altered and showed a poly-layered arrangement and were attached to each other with desmosome-like junctional complexes. There was a general loss of endothelial fenestrae. Endocytotic vesicles could be recognized in these endothelial cells. Poly-layered endothelial cells and accompanying layers of basal laminae were variably arranged between sinusoids and tumor cells with pseudoglandular, trabecular, or compact types of tumor cell patterns. Atypical cells containing numerous lysosomes, together with altered fat-storing (Ito) cells, were located in the tissue space bordering the capillaries. Moreover, tumor cells possessed flattened sinusoidal surfaces. These alterations of the sinusoidal wall suggest that capillarization of liver sinusoids in HCC took place, by loss of fenestrations, formation of basal laminae, and loss of microvilli on the surface of tumor cells. These architectural alterations are thought to completely change the physiological pattern of exchange of metabolites between tumor cells and the sinusoidal lumen. The absence of large numbers of Kupffer cells suggests that at this stage of tumor development, local cellular defense mechanisms were inoperative.

Basement Membrane↗

PubMed1989

Localization of adrenergic and neuropeptide tyrosine-containing nerves in the mammalian liver.

The distribution of adrenergic nerves in guinea pig and rat liver was studied by the immunolocalization of fibers containing tyrosine hydroxylase and dopamine beta-hydroxylase, enzymes involved in the synthesis of catecholamines. In both species, adrenergic fibers were identified within portal tracts, often in close proximity to hepatic artery branches. In guinea pig liver, but not rat liver, abundant intraacinar fibers were identified; fibers were also seen within the walls of terminal hepatic vein radicles and larger hepatic veins. The presence of peptidergic nerves containing the regulatory peptide neuropeptide tyrosine and the C-flanking peptide CPON was investigated by indirect immunofluorescence. The distribution of these nerves was similar to that of tyrosine hydroxylase- and dopamine beta-hydroxylase-positive nerves and showed the same species difference. The effector sympathetic nature of tyrosine hydroxylase- and neuropeptide tyrosine-positive fibers in rat liver was confirmed by chemical denervation studies using 6-hydroxydopamine.

Adrenergic Fibers↗

PubMed1989

Ultrastructural localization of dentine phosphoprotein in rat tooth germs by immunogold staining.

Dentine phosphoprotein (DPP) was localized on thin frozen sections of fixed rat tooth germs by indirect immunogold staining. Antisera were directed against DPP and against glutaraldehyde-treated DPP and were characterized by immuno-electroblotting. In odontoblasts, DPP was found to be localized in the cisternae of the rough endoplasmic reticulum (RER) and the Golgi apparatus and in Golgi-associated vesicles. Odontoblastic processes were moderately positive for DPP and dentine was intensely labeled on frozen sections of unfixed tissue. Predentine showed a slight immunoreactivity. These results indicate the synthesis of DPP in the RER, its accumulation in the Golgi apparatus and its vesicular transport and secretion via the odontoblastic processes into dentine. The close association of the gold particles with the dentinal collagen fibres makes a role of DPP in linking mineral to collagen conceivable. Matrix vesicles were negative for DPP, suggesting that the protein is not present at the sites of matrix vesicle-associated nucleation.

Animals↗

PubMed1989

The fate of lipopolysaccharide in cultured rat Kupffer cells.

Cultured rat Kupffer cells were incubated in presence of biologically tritiated Salmonella abortus equi lipopolysaccharide. Uptake of lipopolysaccharide increased rapidly during the first 2 h of incubation and then levelled off. Within the first h of incubation 10(6) Kupffer cells were able to ingest up to 18 micrograms lipopolysaccharide. Kupffer cells metabolised lipopolysaccharide and released lipopolysaccharide-related substances, but neither the cell-associated lipopolysaccharide nor the released lipopolysaccharide products were detoxified, as measured by the mouse lethality test.

Animals↗

PubMed1989

The role of bile acids in the reduction in lipopolysaccharide uptake by cultured rat Kupffer cells.

The influence of bile salts on the binding and uptake of Salmonella abortus equi lipopolysaccharide by cultured Kupffer cells was studied. In control preparations, the percentage of cell-associated lipopolysaccharide increased with time and reached a plateau after about 2 h incubation at 37 degrees C. About 1.2 micrograms lipopolysaccharide was associated with 10(6) Kupffer cells at this time interval. In the presence of 0.3, 0.6 and 1 mumol bile salts/ml the cell-associated lipopolysaccharide was respectively, about 5%, 13% and 29% lower than in control cultures. In the presence of 1 mumol bile salts/ml, the association of lipopolysaccharide to cells at 0 degrees C was about 25% lower than in controls. Preincubation of Kupffer cells with 1 mumol bile salts/ml, with or without lipopolysaccharide, did not affect cell-associated lipopolysaccharide after removal of the bile salts. The rate of secretion of radioactivity by Kupffer cells was not influenced by the presence of bile salts during the uptake or the secretion periods. Bile acids proved to inactivate lipopolysaccharide. From these observations it was concluded that low concentrations of bile salts influence the binding and uptake of lipopolysaccharide by Kupffer cells. It was, therefore, considered likely that, in patients with obstructive jaundice, the high serum bile acid level accounts for spill-over of portal lipopolysaccharide into the systemic blood.

Animals↗

PubMed1989

In vitro differentiation of fat-storing cells parallels marked increase of collagen synthesis and secretion.

Fat-storing cells were isolated and purified from livers of normal adult rats and maintained in primary culture. By light and electron microscopy it was established that they underwent phenotypic changes into cells with the ultrastructural characteristics of myofibroblasts, between the third and sixth day in culture. These morphological changes were accompanied by a 2-fold increase of L-[3H]proline incorporation into secretory proteins and an 11-fold increase into secreted collagenase-sensitive proteins. In contrast, incorporation into cell layer-associated proteins and into cell layer-associated collagenase-sensitive proteins was not significantly elevated. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in combination with fluorography, demonstrated that the main collagen type secreted by the myofibroblast-like cells was collagen type I. Collagen types III and IV, and fibronectin were present in lesser amounts. The similarity between the well known in vivo alterations of fat-storing cells under pathological conditions and the spontaneous in vitro differentiation described in this study, makes primary cultures of fat-storing cells a valuable tool for studying their role in chronic liver disease.

Adipose Tissue↗