Supportive cellular elements for hepatic T cell differentiation: T cells expressing intermediate levels of the T cell receptor are cytotoxic against syngeneic hepatoma,and are lost after hepatocyte damage

Extrathymic T cells exist in the liver and are often seen in close contact with Kupffer cells in the hepatic sinusoids. Since selective depletion of Kupffer cells has become possible by using liposome-encapsulated clodronate, it was investigated whether elimination of Kupffer cells influences the level of extrathymic T cells in the liver. Extrathymic T cells were identified as interleukin-2 receptor β-chain (IL-2Rβ) intermediate TCR (TCR^int) cells by two-color staining for CD3 or T cell receptor (TCR) and IL-2Rβ. The elimination of Kupffer cells did not significantly affect levels of TCR^int cells up to 7 days after treatment. We then examined monocyte colony stimulating factor (M-CSF)-deficient op/op mice (low levels of Kupffer cells). Extrathymic T cells both in the liver and spleen of these mice were detected at a level comparable to that of control mice. Since extrathymic T cells in the liver are sometimes located in the parenchymal space, the relationship between extrathymic T cells and hepatocytes was then examined. Electron microscopy revealed that some hepatic T cells adhered directly to hepatocytes. When hepatocytes were damaged by a single injection of CCl₄, hepatocyte death and subsequent hepatic fibrosis were induced. Beginning 3 days after injection, CD3^int cells, but not other type of cells, decreased prominently. Purified CD3^int cells, as well as whole lymphocytes in the liver, were cytotoxic against syngeneic hepatoma. In parallel with the above-mentioned hepatic damage, the cytotoxic activity of lymphocytes against such targets was impaired in the liver. These results suggest that extrathymic generation of TCR^int cells and their acquisition of cytotoxic function are relatively independent of Kupffer cells, but are dependent on hepatocytes.     

TLR-2 is upregulated and mobilized to the hepatocyte plasma membrane in the space of Disse and to the Kupffer cells TLR-4 dependently during acute endotoxemia in mice

Membrane components of bacteria and fungi are recognized by Toll-like receptors (TLRs) which, when activated, induce several inflammatory mediators important in the host defense. As the liver is constantly exposed to ingested bacteria, hepatic TLRs must be broadly responsive and highly regulated to prevent uncontrolled inflammatory activation. Although several hepatic cells express microbe recognition molecules and inflammatory mediators in vitro, the regulation and cellular localization of these proteins in vivo remain uncertain. The expression and regulation of TLR-2 and TLR-4, and the cytokine expression patterns were evaluated in mouse tissues using a model of acute inflammation induced by intraperitoneal injection of LPS. Five hours after intraperitoneal LPS, induction of TLR-4 was evident in lung, while the low hepatic TLR-4 expression was non-inducible. TLR-2 mRNA and protein were induced both in lung and liver TLR-4 dependently. However, IL-1alpha also contributed to this induction, and IL-1R1 antibody attenuated the TLR-2 increase. Immunoelectron microscopy showed accumulation of cytoplasmic TLR-2 to vesicles near the hepatocyte plasma membrane in the space of Disse, to the sinusoidal endothelium and to the Kupffer cells. NF-kappaB activation was clear in Kupffer cells and hepatocytes during LPS-challenge, suggesting these cells to be the main source of in vivo cytokine production. Hepatic cytokine response to LPS was remarkably rapid in liver, whereas lung responded less acutely. Secondary inflammatory challenge attenuated the TLR-2 response. The innate immune system of the liver is rapidly and transiently activated during endotoxemia by mechanism involving both TLR-4 and TLR-2.     

血清对分离枯否细胞细菌脂多糖摄取过程的影响

本文应用单克隆抗细胞抗细菌多糖抗体，利用免疫荧光及激光共聚焦扫描技术，观察了分离培养的枯否细胞有无血清条件下对二种不内发子结构细菌脂多糖摄取过程的影响，无血清状态下，枯否细胞加入Ｓ型脂多糖（Ｓ－ＬＰＳ）及Ｒ型脂多糖（Ｒｄ－ＬＰＳ）培育５ｍｉｎ后，其胞闪内抗脂多糖荧光强度显著高于空白对照水平。且Ｓ－ＬＰＳ培育后胞浆内荧光强度增高幅度高于Ｒｄ－ＬＰＳ培养后的增高幅度，１０％小牛血清状态下，Ｓ－ＬＰＳ培     

Hepatocyte modulation of Kupffer cell prostaglandin E2 production in vitro

It is likely that dynamic interactions between hepatocytes and Kupffer cells contribute to the responses of these cell types both under normal conditions and during sepsis. In this study, we examined the influences of hepatocytes on the concentration of the inflammatory mediator PGE2 in Kupffer cell cultures. Evidence to suggest that cultured rat hepatocytes both metabolize PGE2 and produce a substance that promotes LPS-stimulated Kupffer cell PGE2 biosynthesis include the following: 1) PGE2 levels in Kupffer cell: hepatocyte coculture were lower than the levels in Kupffer cell cultures early after LPS stimulation; 2) 36 h after LPS, coculture PGE2 levels exceeded the levels in Kupffer cell cultures despite the demonstrated capacity for hepatocytes to metabolize PGE2; 3) a transferable, non-dialyzable, and heat-unstable factor in hepatocyte supernatant promoted PGE2 production when added to Kupffer cells with LPS or after LPS; 4) there was no increased PGE2 synthesis when the hepatocyte supernatant was added without LPS or if hepatocyte supernatant was preincubated with the Kupffer cells for 6 or 18 h before LPS administration; 5) there was an inability of the hepatocyte factor to promote PGE2 production in response to other macrophage-activating agents, including calcium ionophore A23187 or phorphol myristate acetate; and 6) there was no increased cell replication or protein synthesis in the Kupffer cell cultures following hepatocyte supernatant incubation. The increased Kupffer cell PGE2 production by the hepatocyte supernatant was not due to contamination of the hepatocyte supernatant by endotoxin or PGE2. These in vitro results raise the possibility that hepatocytes have the capacity to modulate local PGE2 levels by two distinct mechanisms. Hepatocytes can metabolize PGE2 as well as release factor(s) which promote LPS-induced PGE2 production by Kupffer cells.     

Induction of plasminogen activator inhibitor 1 gene expression in murine liver by lipopolysaccharide. Cellular localization and role of endogenous tumor necrosis factor-alpha.

We previously demonstrated that lipopolysaccharide (LPS) induces plasminogen activator inhibitor 1 (PAI-1) gene expression primarily in endothelial cells in most organs of the mouse, with maximal induction by 3 hours. Here we show that induction in the liver occurs in a distinctly different pattern. For example, the increase in PAI-1 mRNA in liver was biphasic with an initial peak at 1 to 2 hours and a second peak at 6 to 8 hours. Moreover, in situ hybridization experiments revealed that PAI-1 mRNA was induced in both endothelial cells and hepatocytes. The endothelial cell response was monophasic and maximal between 1 and 4 hours, whereas the hepatocyte response was biphasic, peaking at 2 hours and again at 6 to 8 hours. To determine possible mechanisms involved in the induction of PAI-1 by LPS, we analyzed the tissues for changes in tumor necrosis factor (TNF)-alpha LPS caused a rapid induction of TNF-alpha mRNA in Kupffer cells, detectable within 15 minutes. Pretreatment of mice with anti-TNF antiserum before challenge with LPS reduced the subsequent increase in plasma levels of PAI-1 by 50 to 70% and significantly reduced the level of induction of PAI-1 mRNA in the liver at both early and late times. Pretreatment appeared to inhibit induction primarily within hepatocytes. These results suggest that LPS may induce PAI-1 in endothelial cells and hepatocytes by different mechanisms.     

The importance of the Fc receptors for IgA in the recognition of IgA by mouse liver cells: its comparison with carbohydrate and secretory component receptors.

The numbers of murine hepatocytes and Kupffer cells with receptors for human polymeric (pIgA) or monomeric IgA (mIgA) were determined by rosette formation with immunobeads coated with human pIgA or mIgA. About 63% of hepatocytes were found to express receptors for pIgA. Receptors for mIgA were also found in a significantly lower percentage of hepatocytes (50%). Only about 10% of Kupffer cells had this type of receptor. Blocking studies performed with purified human immunoglobulins suggested that both cells expressed a receptor that recognized the Fc portion of IgA (either pIgA or mIgA). In addition, murine multimeric MOPC-315 IgA strongly inhibited in a dose-dependent fashion the pIgA and mIgA rosette formation by both cells. When cells were incubated in the presence of a rabbit antiserum to secretory component (SC), only pIgA rosette-forming hepatocytes were partially inhibited. No such inhibition was seen when an antiserum to human IgG was used. Both galactose and mannose monosaccharides failed to inhibit the IgA rosette formation by either type of cell. These results show that murine hepatocytes, besides having SC receptors for polymeric IgA, also express receptors for the Fc portion of IgA. The carbohydrate receptors did not seem play any role in the recognition of IgA. The fact that Kupffer cells exclusively present Fc alpha R suggests that monomeric and polymeric IgA, either in form of immune complexes or not, are handled in a different manner by the liver cells.     

胰岛素对大鼠肝细胞损伤的保护及其抗炎机制

目的观察胰岛素对大鼠继发性肝细胞损伤是否具有保护作用并探讨其机制。方法胶原酶原位灌流分离大鼠枯否细胞(Kupffercell,KC)及肝细胞并原代培养,分别用脂多糖(LPS)及胰岛素处理KC4h,ELISA法检测KC培养上清液中肿瘤坏死因子-α(TNF-α)和白介素-10(IL-10)水平;将不同处理的KC培养上清液分别作用肝细胞,12h后检测肝细胞损伤及存活率,并给予TNF-α单克隆抗体(TNF-α-mAb)阻断TNF-α,观察胰岛素对肝细胞作用的变化。结果(1)LPS处理的KC培养上清液可引起肝细胞损伤,使丙氨酸氨基转移酶(ALT)和天门冬氨酸氨基转移酶(AST)增高;胰岛素可减轻上述肝细胞损伤(ALT活性降低30.1%,AST活性降低21.2%)(P<0.01,n=8),提高肝细胞存活率(P<0.01,n=8);(2)胰岛素降低KC培养上清液中的TNF-α水平(P<0.01,n=8),同时增加了IL-10的水平(P<0.05,n=8);(3)LPS激活的KC培养上清中加入TNF-α-mAb(中和TNF-α),亦可减轻肝细胞损伤,而此时胰岛素对肝细胞的保护效应未见叠加增强。结论首次发现胰岛素可通过抑制KC分泌促炎性细胞因子TNF-α,同时促进其释放抗炎性细胞因子IL-10,从而减轻肝细胞损伤,促进肝细胞存活。     

Genetic restriction of murine hepatitis virus type 3 expression in liver and brain: comparative study in BALB/c and C3H mice by immunochemistry and hybridization in situ

Summary To study the host-dependent genetic variations in murine hepatitis virus type 3 (MHV 3) induced diseases, we localized the sites of MHV 3 (Mill Hill strain) expression within liver and brain by immunohistochemistry or hybridization in situ. Two strains of mice were studied: BALB/c mice, which develop an acute and lethal hepatitis and C3H mice which develop a chronic brain infection. In BALB/c mice, viral RNA and antigens appeared during the first 24 h post infection (p.i.) in liver, whereas viral RNA was barely detectable in brain, up until death at day 3 p.i. In C3H mice, viral RNA and antigens were detected simultaneously in liver and brain only at day 2 p.i. In brain, the virus was detected in meningeal and ependymal cells and in perivascular cortical areas (days 5 and 7 p.i.). After day 49, the virus was no longer detected in brain parenchyma, but persisted in meningeal cells. Two host-dependent genetic differences in viral processing were observed in the liver: (1) the virus was first detected in Kupffer cells in BALB/c mice and mostly in hepatocytes in C3H mice; (2) in BALB/c mice, the 180 kDa S viral glycoprotein appeared more frequently cleaved in 90 kDa form than in C3H mice.     

Comparative studies of endotoxin uptake by isolated rat Kupffer and peritoneal cells.

The process of uptake of endotoxin by cells of the reticuloendothelial system is of current interest. Rabbit peritoneal macrophages have been used to study macrophage-endotoxin interactions and have suggested a receptor-mediated process. It is generally believed that the site of in vivo endotoxin clearance is the liver and that this clearance involves the Kupffer cell population. In the current report, the uptake characteristics of iodine-125-labeled Salmonella minnesota lipopolysaccharide (LPS) were compared in both isolated rat Kupffer cells and elicited rat peritoneal cells. Both types of cells were isolated from male Sprague-Dawley rats fed a semisynthetic AIN-76 5% saturated-fat diet either by peritoneal lavage for peritoneal cells or by collagenase perfusion followed by purification on a 17.5% metrizamide gradient for Kupffer cells. Hot phenol water-extracted S. minnesota LPS was labeled with iodine by the chloramine-T method following a reaction with methyl-p-hydroxybenzimidate. The in vitro uptake of [125I]LPS by Kupffer cells was unsaturable up to concentrations of 33.33 micrograms/ml, while peritoneal cells became saturated at between 16.67 and 25 micrograms of LPS per ml. Uptake by both types of cells could be inhibited by a 10-fold excess of unlabeled LPS. Kinetic experiments demonstrated that Kupffer cells were unsaturable after 60 min of incubation, while peritoneal cells were saturable after 40 min of incubation. Pretreatment with 75 mM colchicine inhibited uptake by peritoneal cells but not Kupffer cells, while pretreatment with 12 mM 2-deoxyglucose inhibited uptake by Kupffer cells but not peritoneal cells. These results are consistent with a process of receptor-mediated endocytosis for peritoneal cells, while Kupffer cells may internalize endotoxins by absorptive pinocytosis. These results suggest that studies of peritoneal cell-endotoxin interactions do not accurately describe the physiologic process within the liver, the major site for the clearance of gut-derived endotoxins.     

Repopulation of murine Kupffer cells after intravenous administration of liposome-encapsulated dichloromethylene diphosphonate.

Kupffer cells were selectively eliminated in mice by the intravenous administration of liposome-entrapped dichloromethylene diphosphonate. At 5 days, small peroxidase-negative and acid-phosphatase-weakly-positive macrophages appeared, increased in number, and differentiated into peroxidase- and acid-phosphatase-positive Kupffer cells. Repopulating small macrophages actively proliferated, and the number of Kupffer cells returned to the normal level by day 14. The numbers of macrophage precursors in the liver as detected by the monoclonal antibodies ER-MP20 and ER-MP58 increased after liposome-entrapped dichloromethylene diphosphonate injection. ER-MP58-positive cells proliferated and differentiated into ER-MP20-positive cells and eventually into BM8-positive Kupffer cells in the liver. Bone-marrow-derived ER-MP58-positive cells were also detectable in the liver and differentiated into ER-MP20-positive cells, but they did not become BM8-positive macrophages. Macrophage colony-stimulating factor mRNA expression was enhanced in the liver 1 day after injection. The administration of macrophage colony-stimulating factor did not shorten the period of Kupffer cell depletion but increased the number and the proliferative capacity of repopulating Kupffer cells. These findings implied that repopulating Kupffer cells are derived from a macrophage precursor pool in the liver rather than from bone-marrow-derived monocytes. Local production of macrophage colony-stimulating factor in the liver plays a crucial role in the differentiation, maturation, and proliferation of Kupffer cells.     

The Fate of Intravenously Administered Radioactive Cholesterol Dispersion in the Rat

The present work was aimed at studying the first stages of disappearance of particulate cholesterol from the circulation. The distribution of radioactivity in blood, liver, spleen, lungs and kidneys was determined at different time intervals after i.v. injections of aqueous-ethanolic dispersions of radioactive cholesterol to rats. More than 95% of the dose disappeared from the circulation in 10 min. From 71 to 93% of the dose was found in the liver 5 min-2 h after the injection. According to autoradiography, most of the particulate cholesterol was immediately taken up by the liver parenchymal cells. There were only few grains over the Kupffer cells. 2 min to 6 h after the injection the highest specific radioactivity was in the free cholesterol fraction of the liver. The specific activity of liver esterified cholesterol was 54 % of that of the free cholesterol at 1 h. They both declined gradually and reached the same level in 1–2 days. There was a gradual rise of the specific activities of plasma free and esterified cholesterol starting 30 min after the injection. Both reached a maximum in 6–16 h, when the curve of plasma esterified cholesterol intersected that of liver esterified cholesterol. The radioactivity reappearing in plasma was associated with lipoproteins and red cells; the cholesterol of the high density lipoproteins had the highest specific activity. The results indicate that particulate cholesterol is taken up chiefly by the parenchymal cells of the liver and is subsequently incorporated into the plasma lipoproteins, most rapidly into the high density lipoproteins. A large fraction of plasma esterified cholesterol originates in the liver.     

Lipopolysaccharide hyperreactivity of animals infected with Trypanosoma lewisi or Trypanosoma musculi.

Rats and mice infected with Trypanosoma lewisi and Trypanosoma musculi, respectively, showed hyperreactivity to lipopolysaccharide (LPS) from gram-negative bacteria. Fatal shock could be precipitated with a dose of LPS 100 to 1,000 times less in infected compared with noninfected animals. In trypanosome-infected rats and mice, extensive liver damage was evident after LPS challenge. These animals showed a pronounced hypoglycemia, marked elevation of blood aspartate transaminase level, and diffuse severe degeneration and total depletion of glycogen in hepatocytes. Only minor changes were observed in noninfected animals given the same dose of LPS. No mononuclear phagocytic cell infiltration was observed in the liver of infected animals. The most striking change was the great increase in size and the probable increase in phagocytic activity and number of sinusoidal Kupffer cells. We suggest that elevated Kupffer cell activity in trypanosome-infected animals may play a role in LPS-induced hepatotoxicity.     

Kupffer cells modulate iron homeostasis in mice via regulation of hepcidin expression

Hepcidin, a small cationic liver derived peptide, is a master regulator of body iron homeostasis. Cytokines and iron availability have so far been identified as regulators of hepcidin expression. Herein, we investigated the functional role of Kupffer cells for hepcidin expression because of their vicinity to the hepatocytes and their importance for iron recycling via erythrophagocytosis. We investigated C57Bl6 mice and littermates, in which Kupffer cells were eliminated in vivo upon intravenous injection of liposome-encapsulated clodronate. Primary cultures of hepatocytes and Kupffer cells were used to study direct regulatory effects ex vivo. The in vivo depletion of Kupffer cells resulted in a significant increase in liver hepcidin expression, which was paralleled by a significant reduction in serum iron levels. The same pattern of regulation by Kupffer cell depletion was observed upon injection of bacterial lipopolysaccharide into mice and in primary (Hfe -/-) and in secondary iron-overloaded mice. Accordingly, the messenger ribonucleic acid (mRNA) concentrations of the hepcidin iron-sensing molecule hemojuvelin were not significantly changed upon Kupffer cell depletion. When primary hepatocytes were cocultivated with Kupffer cells or stimulated with a Kupffer cell-conditioned medium ex vivo, a significant reduction in hepatocyte hepcidin mRNA expression was observed. Our data suggest that Kupffer cells control body iron homeostasis by exerting negative regulatory signals toward hepcidin expression, which may be primarily referred to the secretion of yet unidentified hepcidin-suppressing molecules by Kupffer cells.     

Involvement of CD14 in lipopolysaccharide- induced liver injury in mice pretreated with Propionibacterium acnes.

OBJECTIVE: The aim of this study was to elucidate the role of CD14 in the Propionibacterium acnes-lipopolysaccharide (LPS) system. METHODS AND RESULTS: CD14 transgenic mice (M14M), which expressed heterotopic CD14 and showed decreased responses to LPS in vivo, were used. Seven days after priming, the size of granulomas induced by an intraperitoneal administration of P. acnes in the M14M mice was smaller than that in the nontransgenic mice. The number of CD14-positive cells in granulomas was also decreased in the M14M mice compared to the nontransgenic mice. An LPS challenge induced apoptotic and necrotic changes in hepatocytes in the nontransgenic mice but not in the M14M mice. Seven days after priming, tumor necrosis factor-alpha expression was found in monocytic cells in granulomas and Kupffer cells in the nontransgenic mice and was significantly upregulated after LPS injection, whereas the expression was very weak in these cells in the M14M mice. CONCLUSIONS: CD14 plays a role in the P. acnes-LPS system in both priming and induction phases.     

Animal model of fatal human monocytotropic ehrlichiosis

Human monocytotropic ehrlichiosis caused by Ehrlichia chaffeensis is a life-threatening, tick-borne, emerging infectious disease for which no satisfactory animal model has been developed. Strain HF565, an ehrlichial organism closely related to E. chaffeensis isolated from Ixodes ovatus ticks in Japan, causes fatal infection of mice. C57BL/6 mice became ill on day 7 after inoculation and died on day 9. The liver revealed confluent necrosis, ballooning cell injury, apoptosis, poorly formed granulomas, Kupffer cell hyperplasia, erythrophagocytosis, and microvesicular fatty metamorphosis. The other significant histological findings consisted of marked expansion of the marginal zone and infiltration of the red pulp of the spleen by macrophages, interstitial pneumonitis, and increased numbers of immature myeloid cells and areas of necrosis in the bone marrow. Ehrlichiae were detected by immunohistology and electron microscopy in the liver, lungs, and spleen. The main target cells were macrophages, including Kupffer cells, hepatocytes, and endothelial cells. Apoptosis was detected in Kupffer cells, hepatocytes, and macrophages in the lungs and spleen. This tropism for macrophages and the pathological lesions closely resemble those of human monocytotropic ehrlichiosis for which it is a promising model for investigation of immunity and pathogenesis.     

Distribution and Localization of Monophosphoryl Lipid A in Selected Tissuef the Rat

The distribution and cellular localization of Monophosphoryl Lipid A in the kidney, liver, lung, spleen, and stomach of rat were investigated by immunohistochemistry on paraffin embedded tissue sections. Rats were sacrificed 24h or 48h following intraperitoneal administration of MPL at a dose of 5mg/Kg. The presence of MPL in selected tissues was indicated by a positive reaction to MPL antibody. In the kidneys, MPL was found in collecting tubules and distal convoluted tubules in the medulla, whereas the glomerulus was essentially free of it. Regarding liver, MPL was found to be abundant in hepatocytes but only occasionally present in Kupffer cells. In lungs, both alveolar and bronchiolar macrophages were positive, indicating the lung can also serve as a possible site for the elimination of MPL. In spleen, endothelial cells and macrophages were positive for MPL. In stomach, MPL was detected in the gastric mucosa and vascular endothelial cells.

In all the tissues studied the intensity of the peroxidase reaction was significantly weaker in 48h samples as compared to corresponding 24h samples indicating possible elimination of MPL from these tissues.     

Studies on the Mechanism of Binding and Uptake of Immune Complexes by Various Cell Types of Rat Liver in Vivo

Soluble heterologous immune complexes (IC) were used to study the mechanism of IC binding to rat liver in vivo. Binding of IC to the various cell types of the liver, endothelial cells, hepatocytes, and Kupffer cells, was only inhibited by aggregated swine immunoglobulins. Binding was not inhibited by the absence of complement components. Intravenous injection of asialoglycoproteins, to block the galactose receptor, could not prevent IC binding. We conclude that Fc receptors play an important role in the binding of soluble heterologous IC to hepatocytes, endothelial cells, and Kupffer cells.     

Distribution of ferritin and hemosiderin in the liver, spleen and bone marrow of normal, phlebotomized and iron overloaded rats

The distribution of ferritin has been studied in many tissues, but has not yet been established on the cellular level. We investigated the cellular distribution of ferritin in the liver, spleen and bone marrow using the immunoperoxidase method, and compared it with that of hemosiderin. We also examined changes in the distribution of these proteins after phlebotomy and iron overload. In normal rats, ferritin was seen in centrilobular hepatocytes, Kupffer cells, macrophages in the red and white pulp of the spleen and central macrophages in bone marrow. Hemosiderin was observed almost exclusively in the red pulp and partly in tangible body macrophages of the white pulp. After phlebotomy, neither ferritin nor hemosiderin were detectable in these cells except for ferritin-positive cells in the white pulp, which showed little change after either phlebotomy or iron overload. In iron overloaded rats, both ferritin and hemosiderin increased in hepatocytes and reticulo-endothelial (RE) cells. Ferritin-positive cells in the liver were mainly located in the periportal area. These results indicated that hepatocytes and RE cells except for those in the white pulp may play an important role in iron storage, and that ferritin-positive cells in the white pulp may have a function other than iron reserve. They also suggested that the zonal distribution of ferritin-positive hepatocytes may be due to microcirculation in the hepatic lobules.     

Superoxide anion generation in the liver during the early stage of endotoxemia in rats

Infiltration of polymorphonuclear neutrophils (PMN) in the rat liver 3 hr after an intravenous (IV) injection of a sublethal dose of Escherichia coli lipopolysaccharide (LPS) was observed without any significant alteration in the total number of Kupffer and endothelial cells. Since previous studies have demonstrated that phagocytic cells in the liver were in a state of metabolic activation under similar experimental conditions, we investigated the in vitro generation of superoxide anion (O2-) by this cell type following the administration of LPS. Kupffer cells from normal rats did not release O2-, in contrast to those obtained from LPS-treated rats. The generation of O2- by Kupffer cells from endotoxic rats was elevated from 3.0 +/- 1.9 nmol/10(6) cells/60 min (mean +/- SD) in the absence of macrophage (M phi) activators, to 5.0 +/- 2.36, 11.33 +/- 5.40, and 4.33 +/- 0.90 in the presence of opsonized zymosan, phorbol myristate acetate (PMA), and the calcium ionophore A23187, respectively. Hepatocytes from normal or endotoxic rats did not produce detectable O2-. Endothelial cells from LPS-treated rats generated less than 0.8 nmol/10(6) cells in the presence of zymosan. PMN that accumulated in the livers of endotoxic rats released O2- only in the presence of zymosan (8.12 +/- 5.40), PMA (15.43 +/- 5.84), or A23187 (1.70 +/- 0.12). The O2- generation by blood monocytes and PMN increased significantly after endotoxin administration and in the presence of activators. These results suggest that the hypermetabolic state of phagocytic cells in the liver shortly after LPS treatment may be correlated with the increased generation of O2-. The latter may subsequently contribute to the induction of hepatic injury in endotoxemia.     

Hydrazine sulfate protection against endotoxin lethality: analysis of effects on expression of hepatic cytokine genes and an acute-phase gene.

Hydrazine sulfate (HS) pretreatment protects mice against the lethal effects of bacterial endotoxin lipopolysaccharide (LPS) through mechanisms yet to be established. The liver was examined as a model organ to determine HS effects on (a) LPS activation of leukocyte (Kupffer cell) interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) genes and (b) subsequent cytokine-mediated induction of the acute-phase response as measured by hepatic metallothionein (MT) gene expression. The utility of this model was documented by in situ hybridization which showed that acute induction by LPS of the IL-1 beta gene occurred in cells found in liver sinusoids, consistent with Kupffer cells, whereas induction of the MT gene occurred in hepatocytes. The cell specific expression of these genes was further verified by Northern blot hybridization to LPS-treated liver RNA which showed that the LPS-mediated increase in hepatic cytokine mRNA levels, unlike that of MT, was not prevented by D-galactosamine (D-GalN) treatment. Northern blot hybridization established that HS pretreatment did not block the acute induction of hepatic cytokine mRNAs (IL-1 beta and TNF-alpha) by LPS nor did it induce these cytokine mRNAs in the absence of LPS. Northern blot hybridization further established that HS did not prevent LPS-mediated activation of hepatocyte MT gene expression. Thus, HS does not prevent LPS from activating liver leukocytes. These results also suggest that HS pretreatment neither prevents the general release of cytokines from LPS activated leukocytes nor the general induction of acute-phase protein gene expression in hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)