[Role of splenin and its active factor in regulating liver monooxygenase system in experimental immunodeficiency and hepatosohepatitis]

An influence of splenin and its non-peptide factor of splenin (NFS) on the state of cytochrome P-450 dependent monooxygenase system (MOS) of liver microsomes in healthy animals under immunodeficiency (splenectomy, administration of gamma-aminobutyric acid (GABA) and toxic hepatosohepatitis was studied. The stimulating action of splenin and NFS on cytochrome P-450 content and MOS activity of liver microsomes in healthy animals has been established. The indices studied markedly decreased after splenectomy. The splenin or NFS administrations promote the recovery of these indices up to starting level in asplenic animals. A decrease in thymic mass dependent in GABA administration is prevented by NFS pretreatment of animals; there is no any effect of mediator acid on cytochrome P-450 content and MOS activity was noted. The preliminary administration NFS potentiates hepatotoxic effect of carbon tetrachloride and increases its inhibitory effect on P-450 dependent MOS of liver microsomes. Under the NFS action the effect in activity of the last is caused by the factor influence on the reparative processes in the liver.

In vivo evidence for accelerated generation of hydroxyl radicals in liver of Long-Evans Cinnamon (LEC) rats with acute hepatitis

The Long-Evans Cinnamon (LEC) rats accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease (WD) and spontaneously develop acute hepatitis with severe jaundice. Although hydroxyl radicals (*OH) have been proposed to be a cause of hepatitis by the accumulation of Cu, it is not clear whether or not *OH can be produced in the liver of hepatitic LEC rats in vivo and also can be involved in the onset of hepatitis. In the present study, *OH production in plasma and liver of hepatitic LEC rats was quantified by trapping *OH with salicylic acid (SA) as 2, 3-dihydroxybenzoic acid (2, 3-DHBA). The ratios of 2, 3-DHBA/SA were significantly higher in plasma and liver of hepatitic LEC rats than those of Wistar rats and LEC rats showing no signs of hepatitis. Furthermore, the ratios of 2, 3-DHBA/SA in plasma and liver of hepatitic LEC rats were almost the same as those of Wistar rats treated orally with CuSO(4) (0.5 mmol/kg) 2 h before acetylsalicylic acid (ASA) injection. We also evaluated the protective effects of D-mannitol (a *OH scavenger) treatment against acute hepatitis in LEC rats. D-mannitol (500 mg/kg) was administered intraperitoneally to 10-week-old LEC rats for 3 weeks. D-mannitol treatment suppressed the increases in serum aspartate aminotransferase activity and total bilirubin concentration. In addition, D-mannitol treatment significantly reduced hepatic mitochondrial lipid peroxidation, which is thought to be important in the pathogenesis of Cu-induced hepatotoxicity. These observations suggest that accelerated generation of *OH catalyzed by free Cu in the liver may, at least in part, play a role in the pathogenesis of acute hepatitis in LEC rats.

JunD protects cells from p53-dependent senescence and apoptosis

JunD is the most broadly expressed member of the Jun family and the AP-1 transcription factor complex. Primary fibroblasts lacking JunD displayed p53-dependent growth arrest, upregulated p19(Arf) expression, and premature senescence. In contrast, immortalized cell lines lacking JunD showed increased proliferation and higher cyclinD1 levels. These properties are reminiscent of the effects of oncogenic Ras expression on primary and established cell cultures. Furthermore, JunD(-/-) fibroblasts exhibited increased p53-dependent apoptosis upon ultraviolet irradiation and were sensitive to the cytotoxic effects of TNF-alpha. The antiapoptotic role of JunD was confirmed using an in vivo model of TNF-mediated hepatitis. We propose that JunD protects cells from senescence, or apoptotic responses to stress stimuli, by acting as a modulator of the signaling pathways that link Ras to p53.

[Effectiveness of dietary non-starch polysaccharides in experimental toxic hepatitis]

The efficiency of some polysaccharides was investigated in mice with an experimental toxic hepatitis. Hepatitis was induced by the oral administration of 10% solution CCl4 in olive oil at a dosage of 3 ml/kg body weight every day during 7 days. After that tested substances were administrated every day 30-40 min before a feeding at a dosage of 150 mg/kg body weight during 14-21 days. Results showed that a calcium alginate, two low-methoxyl pectins (one with the degree of esterification about 50% and other with the degree of esterification less 5%), fucoidan, and chitozan, but not lambda-carrageenan and kappa-carrageenan, have beneficial affects on liver total lipid, glycogen, malondialdehyde, and diene conjugates as well as on blood total lipid and alanine aminotransferase activity in animals with experimental toxic hepatitis.

Hepatic copper accumulation induces DNA strand breaks in the liver cells of Long-Evans Cinnamon strain rats

Effects of accumulation of copper and iron on the production of DNA strand breaks were investigated in Long-Evans Cinnamon (LEC) strain rats that spontaneously develop fulminant hepatitis. Copper and iron accumulated in the liver of LEC rats in an age-dependent manner from 4 to 15 weeks. Low-copper food prevented the accumulation of copper in the liver, but did not prevent accumulation of iron. When the amounts of DNA single strand breaks were estimated by comet assay, the number of DNA strand breaks in the liver cells of rats fed standard food increased with age from 4 to 15 weeks. The number of DNA strand breaks in the liver cells from rats fed low-copper food were the same as those of rats at 4 weeks of age. Thus, the copper accumulation in the liver of LEC rats induced DNA strand breaks, but accumulation of iron did not.

The NFkappaBb/IkappaB system in acute inflammation

The transcription factor NFkappaB is a primary regulator of a wide variety of proinflammatory mediators. Under normal conditions, NFkappaB is retained in the cytoplasm bound to inhibitory proteins of the IkappaB family. Following cell activation, a number of signal transduction pathways lead to degradation of IkappaB proteins which results in nuclear translocation of NFkappaB and the ensuing transcriptional activation of proinflammatory genes. Several endogenous regulatory mediators, which function to prevent uncontrolled inflammation, exert their effects by blocking the activation of NFkappaB. Thus, NFkappaB appears to be at the heart of the acute inflammatory response. The present review discusses the role of NFkappaB in the induction and propagation of the acute inflammatory response as well as the regulation and resolution of this process.

Inhibition of Fas-mediated fulminant hepatitis in CrmA gene-transfected mice

Hyperimmune response via Fas/Fas-ligand and perforin/granzyme pathways may be essential in pathogenesis of virus-induced fulminant hepatitis. CrmA inhibits activation of caspases and granzyme B, suggesting it may block these pathways. We investigated whether CrmA expression would inhibit Fas-associated lethal hepatitis in mice. We successfully generated AxCALNLCrmA, a recombinant adenovirus expressing CrmA gene with a Cre-mediated switching cassette. We increased CrmA expression level in the liver transfected with AxCALNLCrmA (10(9) pfu) by increasing administration dose (10(7)-10(9) pfu) of AxCANCre, a recombinant, adenovirus-expressing Cre gene. Injection of anti-Fas antibody into the control mice rapidly led to animal death due to massive liver apoptosis, while the apoptosis was dramatically reduced in the CrmA-expressed mice. The animal survival increased with an increase of CrmA expression. The formation of active caspase-3 was markedly inhibited in the crmA-transfected hepatocytes in vitro. These results suggest that crmA is an effective gene that can inhibit immune-related liver apoptosis.

Bile duct ligation in rats induces biliary expression of cytokine-induced neutrophil chemoattractant

BACKGROUND & AIMS

Bile duct obstruction causes neutrophilic inflammation of the liver and leads to hepatic fibrosis. In obstructive liver disease, the localization of neutrophils in portal tracts suggests that cells within this region produce neutrophil chemoattractants. In this study, we investigated whether bile duct obstruction in rats induces portal expression of cytokine-induced neutrophil chemoattractant (CINC).

METHODS

Rats underwent bile duct ligation for 3 hours to 8 days. CINC regulation was examined in vivo at various intervals by immunohistochemistry, ribonuclease protection, and in situ hybridization. CINC production was also investigated in cell culture, in response to putative stimuli from obstructed liver.

RESULTS

Bile duct ligation caused neutrophilic infiltration of the liver within 3 hours. CINC was also rapidly induced, with specific expression identified in biliary cells. Rat intrahepatic biliary cells produced CINC constitutively in culture; when exposed to cholestatic bile, they showed a 12-fold increase in CINC secretion. The effect of bile was not attributable to toxicity or to dissolved cytokines or endotoxin. Mechanical strain, designed to mimic the stretching of biliary cells during obstruction, did not induce CINC.

CONCLUSIONS

Biliary cells contribute to hepatic inflammation during cholestasis by producing neutrophil chemoattractants. A major stimulus to biliary chemoattractant production in vivo may be bile itself.

Expression of matrix metalloproteinases and their inhibitors during hepatic tissue repair in the rat

Matrix metalloproteinases (MMPs) and their specific inhibitors (TIMPs) are thought to play an essential role in liver injury associated with tissue remodeling. However, their distinct expression profile in different liver repair models still remains to be established. Hepatic expression of collagenase (MMP-13), gelatinases A and B (MMP-2, -9), stromelysin-1 and -2 (MMP-3, -10), membrane-type MMP-1 (MMP-14), and TIMP-1 and -2 was studied following single and repeated CCl4-mediated injury and after partial hepatectomy. Expression was analyzed by reverse transcription-PCR (RT-PCR), northern blot analysis, zymography, and immunohistochemistry. Following a single toxic liver injury, MMPs and TIMPs were induced in a distinct time frame in that expression of most MMPs was induced during the early phase of liver injury, was maximal during the inflammatory reaction, and was diminished in the recovery phase. In contrast, TIMP and MMP-2 steady state mRNA levels remained constant in the early phase, were strongly induced during tissue inflammation, and remained increased until the recovery phase. Interestingly, hepatic TNF-alpha expression paralleled the MMP induction profile, while the increase of TGF-beta1 expression mapped to the increase of TIMPs. Chronic liver injury was accompanied by an increase in the steady state mRNA levels of MMP-2 and TIMPs, while other MMPs remained more or less unchanged or were diminished. Partial hepatectomy was followed by a dramatic increase of MMP-14 and to a lesser extent also of TIMP-1 expression; other MMPs and TIMPs were not significantly induced. Liver injury is accompanied by profound changes in hepatic MMP/TIMP expression, the latter being critically dependent on the type of injury. Single toxic injury resulting in complete restoration was characterized by a sequential induction of MMPs and TIMPs suggesting initial matrix breakdown and matrix restoration thereafter. Chronic liver injury leading to fibrosis displays overall diminished matrix degradation mainly through TIMP induction, while liver regeneration induced by partial hepatectomy caused an induction of MMP-14 and TIMP-1 only, which might be unrelated to matrix turnover but connected to pericellular fibrinolysis or fibrolysis required for hepatocellular replication.

The Long Evans Cinnamon (LEC) rat develops hepatocellular damage in the absence of antimicrosomal antibodies

Long Evans Cinnamon (LEC) rats are an inbred strain with a mutation affecting a copper transporter. As a result, hepatic copper levels rise and the rats spontaneously develop hepatitis that is fatal in about 40% of the rats. The rats that die have been reported to develop anti-microsomal antibodies, most frequently against protein disulfide isomerase (PDI), prior to the onset of liver damage. The association between the presence of antibodies and death of the LEC rats, along with the detection of antibodies prior to the detection of liver damage suggested that the antibodies may have a role in the pathogenesis of liver damage. The objective of this study was to more clearly delineate the temporal relationship between antibody production and the onset of liver damage and copper accumulation. Serum was screened for the presence of anti-microsomal antibodies by immunoblotting. Liver damage was assessed by serum biochemistry and histological examination on rats between 6 and 12 weeks of age (four per group). Copper accumulation in the liver was determined by biochemistry and histological examination. Evidence of liver damage was detectable by serum biochemistry and histopathology by 11.5 weeks. Copper was rarely detected in hepatocytes, although it was detected in macrophages. Sera from only one of seven rats with evidence of liver damage had detectable anti-microsomal protein antibodies. The protein recognized was not PDI. The development of anti-microsomal autoantibodies did not precede the development of significant liver damage, suggesting that they play only a secondary role, if any, in the pathogenesis of hepatitis in this rat strain.

Accumulation of diacylglycerol in the liver membrane of the Long-Evans Cinnamon (LEC) rat with hepatitis: FT-IR spectroscopic and HPLC detection

Long-Evans Cinnamon (LEC) rats develop severe hepatitis and subsequent hepatoma with excess accumulation of copper in the liver with increasing age. Lipids extracted from the LEC rat liver membrane were studied using FT-IR spectroscopy and an HPLC technique at the stages of pre-hepatitis and hepatitis, i.e. at 10 and 16 weeks of age, respectively. The 10-week-old rats exhibited an IR spectrum characteristic of a phosphatidylcholine and phosphatidylethanolamine mixture with a ratio of 2:1. The 16-week-old rats developed new absorption bands at 1161 and 1070 cm(-1), which were assigned to the spectra of triglyceride, neutral lipid, and diacylglycerol, an endogenous activator of protein kinase C, respectively. The diacylglycerol was estimated to amount to ca. 10% (w/w) of phospholipid extract by comparing the spectrum with those of model compounds. This was confirmed using an HPLC assay. Previously, we found that a serum response factor is activated by copper in the LEC rat liver, and suggested that it must mediate proto-oncogene c-fos induction. The results obtained here suggest that accumulation of diacylglycerol plays an important role in development of hepatoma in LEC rats by mediating proto-oncogene c-fos induction.

Dissolution of copper-rich granules in hepatic lysosomes by D-penicillamine prevents the development of fulminant hepatitis in Long-Evans cinnamon rats

BACKGROUND/AIM

The Long-Evans cinnamon rat has a mutation homologous to the human Wilson disease gene, leading to gross copper accumulation and the development of hepatitis. D-penicillamine, a copper-chelating drug widely and efficiently used in treating Wilson disease, has also been shown to prevent hepatitis in Long-Evans cinnamon rats. The objectives of this study were: i) to investigate the effectiveness of D-penicillamine when administered to the already affected animals, and ii) to elucidate the mechanism of action of the drug.

METHODS

Long-Evans cinnamon rats were divided into groups according to age and treatment with D-penicillamine. The drug was administered orally before and after the onset of hepatitis. Livers were examined by light and electron microscopy. The effect of D-penicillamine on the subcellular distribution and binding of copper was investigated in more detail. Finally, the interaction between D-penicillamine and specific hepatic copper-binding proteins was studied in vitro.

RESULTS

D-penicillamine when given to either healthy or diseased animals prevented or reversed hepatitis, respectively. The drug particularly inhibited the disease-specific accumulation of copper in lysosomes of hepatocytes, tissue macrophages and Kupffer cells. When administered to diseased animals, the drug sequestered copper particularly from insoluble lysosomal particles. According to results obtained in vitro, the mobilization of this copper is likely to proceed through the solubilization of these particles. In contrast and as supported by the in vitro data, D-penicillamine had only a minor effect on copper bound to metallothionein in the cytosol.

CONCLUSION

Our findings on the Long-Evans cinnamon rat provide some conclusions on the mechanism of action of D-penicillamine in Wilson disease therapy. The drug prevents the formation or promotes the solubilization of copper-rich particles which occur in lysosomes of hepatocytes and Kupffer cells in the livers of patients with Wilson disease. Once chelated with D-penicillamine copper might then be excreted into urine. However, the mobilization of copper by D-penicillamine seems to be limited due to the binding of the metal to metallothionein in liver cytosol. This copper, even at relatively high concentrations, apparently may be well tolerated.

Pharmacokinetics and pharmacodynamics of vecuronium in rats with systemic inflammatory response syndrome: treatment with NG-monomethyl-L-arginine

BACKGROUND

Insufficient detoxification caused by nitric oxide-related inhibition of cytochrome P450 may be important for metabolism of numerous drugs, including vecuronium. The present study investigated the pharmacodynamics and pharmacokinetics of vecuronium in rats with inflammatory liver dysfunction.

METHODS

Male Sprague-Dawley rats (n = 56) were randomly allocated into two groups: In the sepsis group, liver inflammation was established by injection of 56 mg/kg heat-killed Corynebacterium parvum; control rats received the solvent. At day 4, groups were subdivided according to treatment with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (250 mg/kg) or placebo. The aminopyrine breath test was performed to assess cytochrome P450 activity. Rats were anesthetized with propofol and mechanically ventilated. Duration of action of vecuronium (1.2 mg/kg) was measured by evoked mechanomyography (stimulation of the sciatic nerve, contraction of the gastrocnemius muscle). In seven rats of each subgroup a 50% neuromuscular blockade was established by a continuous vecuronium infusion. Vecuronium plasma levels were measured and plasma clearance of vecuronium was calculated. Nitric oxide synthesis was assessed by measuring nitrite/nitrate serum levels.

RESULTS

In sepsis/placebo rats, vecuronium-induced neuromuscular blockade was prolonged (144% of contro/placebo), vecuronium plasma levels at 50% neuromuscular blockade were increased (122% of control/placebo), and plasma clearance was decreased (68% of control/placebo). N(G)-monomethyl-L-arginine therapy in rats with sepsis improved cytochrome P450 activity and plasma clearance of vecuronium, shortened duration of action of vecuronium, but did not alter the elevated vecuronium plasma levels.

CONCLUSIONS

A systemic inflammatory response syndrome with liver dysfunction results in decreased sensitivity to and a decreased elimination of vecuronium. Modulation of nitric oxide synthesis may be a strategy that can be used in the future to improve xenobiotic metabolism in sepsis.

Propionibacterium acnes induces acute TNFalpha-mediated apoptosis of hepatocytes followed by inflammatory T-cell-mediated granulomatous hepatitis in mice

The CD3+/TCRalphabeta+ T-cell-mediated hepatic inflammation induced by Propionibacterium acnes could be divided into an acute and a chronic phase. The acute phase occurred within 72 h after injection and displayed hepatic apoptosis. Anti-TNFalpha antibody inhibited both the P. acnes-induced hepatic apoptosis and lymphocyte infiltration seen in this phase, indicating the involvement of this cytokine. Thereafter, a chronic phase was manifested from days 7 to 14 after injection. It was characterized as granulomatous inflammation admixed with apoptosis of infiltrating lymphocytes and some hepatocytes. Immunohistochemical staining showed that the infiltrating lymphocytes displayed TNFalpha, TNF type I receptor and a variety of cytokines including IL-1beta, IL-4, IL-6, IL-10, IFNgamma or IL-12. Interestingly, in naive mice, the arteries in the liver constitutively expressed IFNgamma. Its expression appeared to be substantially increased at 48 h, decreased at 72 h, and increased again on day 14 after P. acnes injection. Furthermore, Fas or FasL was only detected on the lymphocytes within the granuloma. We conclude that P. acnes can induce a TNFalpha-mediated acute hepatic apoptosis which subsequently progress to a T-cell-mediated granulomatous hepatitis with increased expression of multiple cytokines and Fas/FasL.

An iron-deficient diet stimulates the onset of the hepatitis due to hepatic copper deposition in the Long-Evans Cinnamon (LEC) rat

To study effects of dietary Cu and Fe levels on the onset of hepatitis in Long-Evans Cinnamon (LEC) rats, female rats (40 days old) were fed a semipurified diet containing 0.1 or 10 mg Cu/kg and 1.5 or 150 mg Fe/kg in a 2 x 2 factorial arrangement for 35 days. At 75 days after birth, LEC rats (+Cu-Fe) fed a Cu-sufficient but Fe-deficient diet (Cu, 10 mg/kg; Fe, 1.5 mg/kg) showed jaundice, with lethargy, anorexia, and malaise. The biochemical variables relating to liver function were significantly increased compared to three other groups, a Cu- and Fe-deficient (-Cu-Fe) group, a Cu-deficient but Fe-sufficient (-Cu+Fe) group, and a Cu and Fe sufficient (+Cu+Fe) group. Furthermore, the +Cu-Fe rat liver showed massive necrosis with huge nuclei. The other three groups presented no biochemical and histological findings of hepatitis. Hepatic Cu and metallothionein concentrations were 289 +/- 87 (mean +/- SD) microg/g liver and 8.7 +/- 1.8 mg/g liver, respectively, in the +Cu-Fe rats. However, in the +Cu+Fe group the values were 196 +/- 28 microg Cu/g liver and 10.8 +/- 1.0 mg/g liver. Hepatic Fe deposition was not influenced significantly by the dietary Cu level. The +Cu-Fe group with jaundice showed the highest free Cu concentration in the liver among the four groups, but the hepatic free Fe concentration was similar to those in the -Cu+Fe and +Cu+Fe groups. Our results indicate that an Fe-deficient diet enhances the deposition of hepatic Cu due to increased absorption of Cu from the gastrointestinal tract. This deposition stimulated the onset of hepatitis.

Differential changes in alpha2-macroglobulin and hemopexin in brain and liver in response to acute inflammation

Changes in serum and cerebrospinal fluid (CSF) proteins following generalized acute inflammation induced by fermented yeast in the rat was examined by concanavalin A-blotting, immunoblotting, and radioimmunoassay. Using alpha2-macroglobulin (alpha2-M) and hemopexin (HPX) as marker proteins, the concentration alpha2-M was found to increase in serum and CSF by 150- and 5-fold, respectively, whereas the concentration of HPX increased by about 4-fold in both fluids following yeast-induced inflammation. The lesser increase in alpha2-M in the CSF versus the systemic circulation is not likely to be the result of changes in the permeability of the blood--brain barrier, since no change in the total protein content of CSF was detected in inflamed rats when compared to control animals. These results, however, illustrate the regulation of the same protein, such as alpha2-M, in two separate organs within the same animal can be drastically different. These results also suggest a possible protective role of alpha2-M in the brain during acute inflammation. Moreover, these observations are consistent with the previous observation that there is a differential response in the level of alpha2-M between the testis and the systemic circulation during inflammation.

Macrophage populations and apoptotic cells in the liver before spontaneous hepatitis in Long-Evans Cinnamon (LEC) rats

The inbred mutant strains of Long-Evans Cinnamon (LEC) rats spontaneously develops acute hepatitis as a result of abnormal copper accumulation, followed by chronic hepatitis, cholangiofibrosis and hepatocellular carcinoma. To shed some light on the role of macrophages in the liver failure, immunohistochemical methods were used to investigate the kinetics of macrophage populations in the liver of male LEC rats, in relation to the appearance of myofibroblastic cells and hepatocyte apoptosis. Rats examined at 24 weeks of age and moribund rats killed at 22-25 weeks of age had increased serum concentrations of aspartate aminotransferase and alanine aminotransferase, with jaundice and histological changes indicative of hepatic failure, whereas rats examined at 8, 12, 16 or 20 weeks old showed no such abnormal findings. Immunolabelling with ED1 (a monoclonal antibody recognizing rat macrophages) and ED2 (a monoclonal antibody specific for rat resident macrophages) revealed that numbers of blood monocyte-derived macrophages and Kupffer cells began to increase markedly at 16 weeks of age (before the onset of hepatitis). However, alpha-smooth muscle actin (SMA)-positive myofibroblastic cells (modulated perisinusoidal cells) and hepatocyte apoptosis, demonstrable by the TUNEL method, were rarely seen at 8, 12, 16, 20 or 24 weeks. There was no close relationship between macrophage expansion and the appearance of myofibroblastic cells or hepatocyte apoptosis. In moribund rats, only a few SMA-positive cells were seen in the periportal zones; hepatocytes undergoing apoptosis increased in number, and macrophages engulfing apoptotic bodies were observed occasionally, suggesting that apoptosis was related to hepatic failure as an early event. In addition, immunohistochemical examination demonstrated abnormal deposits of laminin along the sinusoids from 20 weeks, as an initial extracellular matrix protein in LEC rat livers.

[Effect of glucosamine on amino acid transport and intensity of protein synthesis in liver cells in an inflammation model]

The effect of glucosamine on the transport of amino acids and protein synthesis in hepatocytes when modelling inflammation was studied. It was found the considerable decrease of the amino acid transport via hepatocyte membranes. The protein synthesis intensity was displayed as also significantly reduced. Administration of glucosamine to the rats normalized both studied processes.

Cx32 mRNA in rat liver: effects of inflammation on poly(A) tail distribution and mRNA degradation

Previous studies showed that the expression of connexin 32 (Cx32), the polypeptide subunit component of the major hepatic gap junction, is reduced in liver by changes in mRNA stability during bacterial lipopolysaccharide (LPS)-induced inflammation. In this study, we examined the distribution of Cx32 mRNA poly(A) tail lengths during LPS-induced inflammation, because this is considered the first step in the degradation of many mRNAs. During LPS treatment the first detectable change in Cx32 mRNA was a gradual shortening of its poly(A) tail, which reached a final size of approximately 20 nucleotides. However, the poly(A) tail did not disappear entirely before the bulk of Cx32 mRNA was degraded. Treatment with actinomycin D, which blocks the degradation of Cx32 mRNA after LPS administration, resulted in the appearance of a completely deadenylated mRNA, which otherwise could not be detected. On the contrary, treatment with cycloheximide resulted in a decrease in the stability of Cx32 mRNA without an apparent change of the poly(A) tail size. The effect of cycloheximide on Cx32 mRNA stability seems to be due indirectly to the induction of an inflammatory response by this drug. These results suggest that, similar for many mRNAs, shortening of the poly(A) tail is one of the first steps in the degradation of Cx32 mRNA during inflammation.

Effect of intravenous immunoglobulin G on the TNFalpha-mediated hepatic microvascular inflammatory response

The effect of intravenous immunoglobulin G (ivIG) on the hepatic microvascular inflammatory response elicited by tumor necrosis factor alpha (TNFalpha) in rats was studied by means of in vivo microscopy and histological examination. One hour after the portal infusion of TNFalpha, the average number of leukocytes adhering to the sinusoidal endothelium was increased sevenfold, and the average number of the perfused sinusoids was decreased by 15% when compared with controls. Concomitantly, the expression of intercellular adhesion molecule-1 (ICAM-1) on the hepatic sinusoidal endothelium and that of the central vein was increased. The phagocytic activity of Kupffer cells in centrilobular sinusoids was increased by 54%, as were the number of ED2-positive Kupffer cells in tissue sections. Pretreatment with a clinically relevant high dose of ivIG (1 g/kg body weight, Sandoglobulin) minimized these responses by reducing leukocyte-endothelial interactions and Kupffer cell phagocytic function. The results suggest that high doses of ivIG limit the hepatic microvascular inflammatory response by inhibiting the action of the proinflammatory cytokine TNFalpha.

Guinea pig alpha 1-microglobulin/bikunin: cDNA sequencing, tissue expression and expression during acute phase

cDNA encoding alpha 1-microglobulin/bikunin (AMBP) was amplified from guinea pig (Cavia porcellus) liver mRNA by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends methods, cloned and sequenced. The deduced amino acid sequence was found to be homologous to the sequence of AMBP of other mammals (69-76% amino acid identity). It has two Kunitz-type trypsin inhibitor domains in the bikunin part as reactive sites, one in the N-terminal region and another in the C-terminal region. The N-terminal inhibitor domain sequence is well-conserved, but the P1 residue of the C-terminal inhibitor domain sequence was found to be Gln rather than Arg, a residue highly conserved in the AMBP of seven other mammals examined to date. By RT-PCR and nested PCR, AMBP mRNA was detected not only in liver tissue, previously known to be a site of its synthesis, but also in pancreas, stomach, small intestine, colon, lung, spleen, kidney, testis, skeletal muscle, and leukocytes, but not in brain or heart. We examined the AMBP mRNA levels in guinea pig liver by RT-PCR, comparing normal levels and those in a state of inflammation. The mRNA levels, however, did not significantly change.

Interleukin-10 expression and function in experimental murine liver inflammation and fibrosis

Kupffer cells (KC) play a central role in the initiation and perpetuation of hepatic inflammation, which, if uncontrolled, can result in tissue damage, fibrosis, and cirrhosis. Interleukin-10 (IL-10) can inhibit a range of macrophage functions. We hypothesized that the transcription, synthesis, and release of IL-10 may influence the development of liver injury. Rat KC were activated in vitro with lipopolysaccharide (LPS), and expression of IL-10 mRNA compared with IL-13 and IL-1beta by reverse-transcription polymerase chain reaction (RT-PCR). The effects of pretreatment with recombinant IL-10 (rIL-10) on KC phagocytosis, production of superoxide (SO), and tumor necrosis factor (TNF-) were examined by fluorescent activated cell sorter (FACS), reduction of ferricytochrome C, and bioassay, respectively. Rats were administered intraperitoneal carbon tetrachloride (CCl4), and expression of IL-10 mRNA and protein in vivo compared with IL-13 and IL-1beta by RT-PCR and immunoblotting. Results were correlated with histological inflammatory changes. Finally, IL-10 gene-deleted (IL-10-/-) mice and wild-type (WT) controls were administered intraperitoneal CCl4 biweekly for up to 70 days, and the development of inflammation and fibrosis compared by scoring histological changes. IL-10 mRNA was up-regulated early, both in KC in vitro and in whole liver in vivo, concurrent with that of IL-1beta. IL-10 was able to inhibit KC production of both SO and TNF- in vitro, and this was achieved more effectively than IL-4 or IL-13; no such effects were seen on KC phagocytosis. After 70 days of treatment with CCl4, IL-10-/- mice showed significantly more severe fibrosis and exhibited higher hepatic TNF- levels than WT controls. These results suggest that IL-10 synthesized during the course of liver inflammation and fibrosis may modulate KC actions, and influence subsequent progression of fibrosis.

Role of P-selectin cytoplasmic domain in granular targeting in vivo and in early inflammatory responses

P-selectin is an adhesion receptor for leukocytes expressed on activated platelets and endothelial cells. The cytoplasmic domain of P-selectin was shown in vitro to contain signals required for both the sorting of this protein into storage granules and its internalization from the plasma membrane. To evaluate in vivo the role of the regulated secretion of P-selectin, we have generated a mouse that expresses P-selectin lacking the cytoplasmic domain (DeltaCT mice). The deletion did not affect the sorting of P-selectin into alpha-granules of platelets but severely compromised the storage of P-selectin in endothelial cells. Unstored P-selectin was proteolytically shed from the plasma membrane, resulting in increased levels of soluble P-selectin in the plasma. The DeltaCT-P-selectin appeared capable of mediating cell adhesion as it supported leukocyte rolling in the mutant mice. However, a secretagogue failed to upregulate leukocyte rolling in the DeltaCT mice, indicating an absence of a releasable storage pool of P-selectin in the endothelium. Furthermore, the neutrophil influx into the inflamed peritoneum was only 30% of the wild-type level 2 h after stimulation. Our results suggest that different sorting mechanisms for P-selectin are used in platelets and endothelial cells and that the storage pool of P-selectin in endothelial cells is functionally important during early stages of inflammation.

[Comparative study of the effects of essentiale and the novel Russian hepatoprotective agent "phospholiv" in a model of acute hepatitis in rats]

Curative effect of new preparation "Phospholiv", elaborated in Institute of Biomedical Chemistry, in acute CCl4 induced rat hepatit model was studied. The preparation consists of polyunsaturated phosphatidylcholine and glycyrrhizinic acid salt. Recovery of damaged biosynthesis of albumin and total cell liver RNA--by incorporation of C14-leucine and C14-orotic acid--were observed after 3 days Phospholiv administration, that showed on reparation of damaged protein-synthesis system. Label incorporation into liver fraction > 80S--that was decreased under CCl4 influence--was also restored after Phospholiv treatment, that may testify on its regenerative effect on wholeness of subcellular hepatocytes structures. Substantial decrease of morphologic damages of liver tissue was demonstrated as well. Other phospholipid preparation--known hepatoprotector Essentiale--gave some positive effects too, but Phospholiv influence on biochemical and morphological liver features were 1.5-2 fold as compared with that of Essentiale. Results show on efficiency of polyunsaturated phospholipids in the treatment of acute hepatit in rats--as a result of influence on hepatocytes cell membrane--and on preferential effect of new hepatoprotector Phospholiv.

[Use of a novel hepato-protective preparation "phospholiv" for inhibition of development of chronic hepatitis in rats]

Protective influence of a new phospholipid preparation "Phospholiv" was studied using a model of chronic hepatitis. Animals were treated 45 days intraperitoneay with CCl4 with parallel intragastral administration of Phospholiv or--(for comparison)--the of other phospholipid hepatoprotector, Essential. Morphologic changes of liver, as well as protein and RNA biosynthesis were evaluated in the end of experiment--by means of measuring C14-leucine and C14-orotic acid incorporation into hepatocyte subcellular fractions. Both phospholipid preparations attenuated dystrophic liver changes, Phospholiv effect being more pronounced. They both prevented CCl4 induced inhibition of label incorporation into subcellular fraction proteins, but only Phospholiv, promoted the maintaining normal level of radioactivity incorporation into cytosol proteins and hepatocyte RNA. The results, confirming certain protective effect of Essential, show more pronounced hepatoprotective action of the new preparation Phospholiv (developed on the basis of polyunsaturated phosphatidylcholine and glycyrrhizinic acid salt). Data show also on possible fit hepatitis treatment.

Carcinoembryonic antigen-related cell-cell adhesion molecule C-CAM is greatly increased in serum and urine of rats with liver diseases

C-CAM (rat cell CAM/human CD66a) is ubiquitous and multifunctional. It is involved in intercellular adhesion, signal transduction and cell growth inhibition. Structurally, it is related to the carcinoembryonic antigen. In the present study serum, bile and urine of rats with liver diseases were analyzed for the presence of cell CAM. After bile duct ligation and during galactosamine (GalN) hepatitis we found that large amounts of liver membrane-bound C-CAM are secreted or shed into blood. The serum level of another liver membrane-bound protein, LI-cadherin, is not increased. It was shown that C-CAM is also present in bile fluid, and for the first time that C-CAM is present in the urine of rats with liver diseases. A particularly high concentration was measured in the urine of rats suffering from GalN hepatitis.

Epidermal growth factor and transforming growth factor-alpha-associated overexpression of cyclin D1, Cdk4, and c-Myc during hepatocarcinogenesis in Helicobacter hepaticus-infected A/JCr mice

Helicobacter hepaticus is a new bacterial species that is homologous to Helicobacter pylori, a human gastric carcinogen. H. hepaticus causes chronic active hepatitis, with progression to hepatocellular tumors. We hypothesized that chronic up-regulation of epidermal growth factor (EGF), transforming growth factor-alpha, and nuclear oncogenes (cyclin D1 and c-Myc), all known to transform by overexpression, might contribute to tumorigenesis. Livers from mice that were 6-18 months old were analyzed, including nonneoplastic and preneoplastic tissues and tumors, along with age-matched controls, by immunohistochemistry and immunoblotting. EGF and transforming growth factor-alpha were increased at the earliest stage, with a further increase in EGF in tumors. Cyclin D1, cyclin-dependent kinase 4, and c-Myc were strongly increased in all infected livers, with even greater increases in tumors. An increase in cyclin D1/cyclin-dependent kinase 4 complex was also demonstrated in tumors, and its functionality was confirmed by an increase in the hyperphosphorylated:hypophosphorylated retinoblastoma protein ratio. Our findings suggest a possible cooperation of growth factors, cell cycle proteins, and transcription factors during the development of H. hepaticus-associated liver tumors and may have relevance to human cancers associated with bacterial, viral, or parasitic infections.

Interleukin-8 and hIRH (SDF1-alpha/PBSF) mRNA expression and histological activity index in patients with chronic hepatitis C

Recombinant human intercrine reduced in hepatomas (hIRH)/stromal cell-derived factor 1 (SDF1-alpha)/pre-B-cell growth-stimulating factor (PBSF), a new chemokine, exhibits an in vitro chemotaxis to neutrophils and a mixed in vivo chemotactic activity to neutrophils, lymphocytes, and monocytes in a rat intradermal injection model. We have investigated the messenger RNA (mRNA) expression of interleukin-8 (IL-8) and hIRH, in chronic hepatitis C of differing severity. Levels of expression of IL-8 and hIRH mRNA obtained from 37 human liver biopsy samples were measured by reverse-transcription and semiquantitative polymerase chain reaction (RT-PCR) amplification. We examined the correlation between mRNA expression and components of the histological activity index (HAI). Patients with HAI > or = 8 had a significantly higher corrected IL-8 mRNA expression ratio (0.24 +/- 0.13 [mean +/- SD]; n = 20) than those with HAI < or = 7 (0.05 < or = 0.03; n = 17; P < .0001). Additionally, IL-8 mRNA expression was strongly associated with the severity of portal inflammation (PI) (high PI vs. low PI, 0.22 +/- 0.14 vs. 0.05 +/- 0.04; P < .0001) and with the presence of bile duct lesions (0.29 +/- 0.15 vs. 0.11 +/- 0.1; P < .01). In contrast, hIRH mRNA expression was not associated with the total HAI, any components of the HAI, or bile duct inflammation or injury. These results suggest that hIRH, although having the -CXC-, alpha chemokine motif, and exhibiting in vivo and in vitro inflammatory activity as does IL-8, plays a different role from IL-8 in hepatic inflammation and injury. IL-8 expression is directly associated with inflammation in patients with chronic hepatitis C, while hIRH expression does not correlate with histopathological severity of inflammation.

Association of copper to metallothionein in hepatic lysosomes of Long-Evans cinnamon (LEC) rats during the development of hepatitis [se e comments]

BACKGROUND

The Long-Evans cinnamon (LEC) rat has a mutation homologous to the human Wilson's disease gene, leading to copper-induced hepatotoxicity. The mechanism of how excess copper damages the liver or what chemical form of copper is toxic is still unclear.

RESULTS

In liver cytosol, copper levels were highest just before the onset of hepatitis and declined thereafter. In cytosol, total copper was bound to metallothionein (MT). Considerable amounts of both copper and iron accumulated in lysosomes with increasing age and development of liver damage. Lysosomal levels of presumably reactive non-MT-bound copper were increased. In severely affected livers, large amounts of copper were associated with insoluble material of high density which, upon ultrastructural information, was found to be derived from the lysosomes of Kupffer cells. This copper-rich material is considered to consist of polymeric degradation products of copper-MT.

CONCLUSION

We suggest that chronic copper toxicity in LEC rats involves the uptake of copper-loaded MT into lysosomes, where it is incompletely degraded and polymerizes to an insoluble material containing reactive copper. This copper, together with iron, initiates lysosomal lipid peroxidation, leading to hepatocyte necrosis. Subsequent to phagocytosis by Kupffer cells, the reactive copper may amplify liver damage either directly or through stimulation of these cells.

The LEC rat possesses reduced hepatic selenium, contributing to the severity of spontaneous hepatitis and sensitivity to carcinogenesis

The hepatic concentrations of copper, zinc, magnesium, calcium, and selenium were measured in LEC rats, which develop a spontaneous form of hepatitis at 3-4 months of age, and compared to trace metal concentrations in the LEA rat, its asymptomatic congenic strain. Consistent with results found by other groups, copper was found to accumulate within the liver of LEC rats to levels more than 50 times those measured in LEA rats. In addition, liver selenium concentration in LEC rats was found to be around 50% of that in LEA rats. The enzyme activity, and RNA for the selenium dependent enzyme, glutathione peroxidase, was also found to be reduced in LEC rat liver. These results indicate that hepatic selenium in the LEC rat is depleted and that, as a result of this, the capacity to protect cells from copper-induced free-radical damage is reduced.

Antibodies to tumor necrosis factor alfa attenuate hepatic necrosis and inflammation caused by chronic exposure to ethanol in the rat

Tumor necrosis factor (TNF)alpha, a pivotal cytokine involved in inflammation, is produced primarily by Kupffer cells in the liver. It has been shown that inactivation of Kupffer cells prevents alcohol-induced liver injury; therefore, the purpose of this study was to determine if neutralizing anti-TNF-alpha antibody is also effective. Male Wistar rats were exposed to ethanol (11 to 12 g x kg(-1) x d[-1]) continuously for up to 4 weeks via intragastric feeding using an enteral feeding model. Before ethanol exposure, polyclonal anti-mouse TNF-alpha rabbit serum was injected (2.0 mg/kg intravenously). There were no significant differences in body weight, mean ethanol concentration, or cyclic patterns of ethanol in urine when ethanol- and ethanol plus antibody-treated groups were compared. Expression of TNF-alpha and macrophage inflammatory protein 2 (MIP-2) messenger RNA (mRNA), determined using reverse transcription-polymerase chain reaction, was three- to four-fold higher in livers of ethanol-treated rats than in those of rats fed an ethanol-free, high-fat control diet. In addition, MIP-2 levels were also elevated when detected by Northern blot analysis. Anti-TNF-alpha antibody did not affect expression of mRNA for interleukin (IL) 1alpha, IL-6, transforming growth factor beta1, or TNF-alpha. However, MIP-2 mRNA expression, which is regulated by TNF-alpha, was decreased significantly by anti-TNF-alpha antibody treatment. Serum aspartate transaminase levels were elevated in ethanol-treated rats to 136 +/- 12 IU/L after 4 weeks but only reached 90 +/- 5 IU/L (P < .05) in rats treated with anti-TNF-alpha antibody. The hepatic inflammation and necrosis observed in ethanol-fed rats were attenuated significantly by antibody treatment, and steatosis was not. These results support the hypothesis that TNF-alpha plays an important role in inflammation and necrosis in alcohol-induced liver injury and that treatment with anti-TNF-alpha antibody may be therapeutically useful in this disease.

Inhibition of nitric oxide synthesis improves detoxication in inflammatory liver dysfunction in vivo

Inflammatory stimulation of the liver induces nitric oxide (NO) biosynthesis and suppression of detoxication. In this study the effect of NO biosynthesis on cytochrome P-450 (CYP) enzyme activity was investigated by comparing in vivo and in vitro assays. To establish liver inflammation, CD rats were injected with Corynebacterium parvum (C. parvum) suspension. After 5 days NO biosynthesis was highly induced as indicated by increased NO2- plus NO3- serum concentrations. At the same time the aminopyrine breath test (ABT), measuring CYP activity in vivo, was reduced to 42% and the in vitro assay of aminopyrine turnover was suppressed to 12% of NaCl- injected controls. When C. parvum-injected animals were treated with the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA), CYP activities significantly improved with an ABT of 76% and an in vitro aminopyrine turnover of 47% of controls. Neither C. parvum injections nor L-NMMA treatment resulted in a significant change of CYP protein concentrations. These data indicate that suppression of xenobiotic metabolism can be attenuated by inhibition of NO biosynthesis during an ongoing process of inflammation.

Chronic hepatitis: a retrospective study in 34 dogs

The aims of this study were to characterize the histological changes observed in 34 accessioned cases of canine chronic hepatitis and to correlate these changes with the clinical pathological data. Cases of chronic hepatitis were subdivided into 6 categories: chronic active hepatitis (10/34), chronic persistent hepatitis (7/32), chronic cholestatic hepatitis (6/34), fibrosing hepatitis with cirrhosis (3/34), chronic cholangiohepatitis (3/34), and miscellaneous secondary hepatitis (5/34). Iron accumulation was a consistent finding in all livers examined. Although all cases of chronic hepatitis had elevated liver enzymes, no correlation was detected between biochemical parameters and the severity of morphologic changes. Similarly, no correlation was detected between rhodanine staining for copper and morphologic or biochemical indicators of cholestasis. However, presence of copper correlated well with reticulo-fibrosis (r = 0.8) and bile duct hyperplasia, suggesting that changes in the hemodynamics of the hepatic acini due to fibrosis could influence storage of copper.

Analysis of Arg-Gly-Asp mimetics and soluble receptor of tumour necrosis factor as therapeutic modalities for concanavalin A induced hepatitis in mice

BACKGROUND/AIMS

It has been shown that synthetic non-peptidic analogues of Arg-Gly-Asp, a major cell adhesive ligand of extracellular matrix, prevented an increase in serum aminotransferase activity, as a manifestation of concanavalin A induced liver damage in mice. This study examined the effects of an Arg-Gly-Asp mimetic on liver histology and cytokine release in response to concanavalin A administration, and the efficacy of soluble receptor of tumour necrosis factor (TNF) alpha in preventing hepatitis in this model of liver injury.

METHODS

Mice were pretreated with either the Arg-Gly-Asp mimetic SF-6,5 or recombinant soluble receptor of TNF alpha before their inoculation with 10 mg/kg concanavalin A. Liver enzymes, histology, and the serum values of TNF alpha and interleukin (IL)6 were examined.

RESULTS

The histopathological damage in the liver, and the concanavalin A induced release of TNF alpha and IL6 were significantly inhibited by the synthetic Arg-Gly-Asp mimetic (p < 0.001). Liver injury, manifested by the increase in serum aminotransferase and cytokines, as well as by histological manifestations of hepatic damage, was effectively prevented by pretreatment of the mice with the soluble TNF receptor (p < 0.001).

CONCLUSIONS

This study confirms the efficacy of a synthetic Arg-Gly-Asp mimetic and soluble TNF receptor in the prevention of immune mediated liver damage in mice.

Induction of hepatocyte growth factor activator messenger RNA in the liver following tissue injury and acute inflammation

Hepatocyte growth factor activator (HGFA) is a serine protease that is responsible for localized activation of hepatocyte growth factor (HGF) in injured tissue. The activated HGF may be involved in regeneration of the injured tissue. HGFA is produced and secreted by the liver and circulates in the plasma as an inactive zymogen. In response to tissue injury, the HGFA zymogen is converted to the active form by limited proteolysis. In this study, we isolated a rat HGFA complementary DNA (cDNA) clone and analyzed the production of HGFA messenger RNA (mRNA) in response to tissue injury using this cDNA clone as a probe. The nucleotide sequence of the cDNA revealed that the amino acid sequences of rat and human HGFA showed a high degree of conservation in the regions of the characteristic domain structures, suggesting that rat and human HGFA are activated by a similar mechanism and have similar enzymatic activities in vivo. Tissue distribution analysis showed that the liver was the major site of rat HGFA mRNA synthesis. Moreover, the cells producing HGFA mRNA were identified as parenchymal liver cells. The level of HGFA mRNA increased in the liver after hepatotoxin or nephrotoxin treatment. This increase was also observed during acute inflammation induced by turpentine. These results suggest that the increase in production of HGFA mRNA in response to tissue injury is the result of an inflammatory response, and that HGFA is an acute phase protein.

Hepatic inflammation following 70% hepatectomy may be related to up-regulation of epithelial neutrophil activating protein-78

Tumor necrosis factor-alpha (TNF) is known to be released after partial hepatectomy. Furthermore, TNF triggers the release of chemotactic cytokines, such as epithelial neutrophil activating protein (ENA-78), which are important for neutrophil chemotaxis, activation, and propagation of the inflammatory response. We now postulate that ENA-78 may play a role the hepatic inflammatory response that occurs following partial hepatectomy. Rats were subjected to 70% hepatectomy or sham laparotomy and were killed in a time-dependent manner. Hepatic neutrophil influx, as assessed by myeloperoxidase (MPO) levels, serum alanine aminotransferase (ALT), and hepatic TNF and ENA-78 levels, as measured by ELISA, were evaluated at 1, 6, and 12 h following operation. MPO levels became significantly elevated within 6 h of hepatectomy and remained elevated at 12 h. Serum ALT became significantly elevated within 1 h of hepatectomy and continued to rise at 12 h. Hepatic TNF and ENA-78 were also increased significantly after hepatectomy. Next, rats undergoing 70% hepatectomy were treated with neutralizing anti-ENA-78 serum; this resulted in a significant decrease in hepatic MPO and serum ALT, suggesting less hepatic injury. To determine whether ENA-78 release was induced by TNF is this model, rats were treated with neutralizing anti-TNF serum and hepatic ENA-78 levels measured 6 h posthepatectomy. ENA-78 levels were significantly decreased in the animals receiving the anti-TNF serum, suggesting that ENA-78 is released in response to TNF in this model. These data suggest that TNF triggers the release of ENA-78 following 70% hepatectomy and that ENA-78 contributes to the hepatic neutrophil influx and liver injury following 70% hepatectomy.

The relationship between hepatic copper content and morphologic changes in the liver of West Highland White Terriers

Liver tissue from 17 West Highland White Terriers (WHWTs) with cirrhosis, subacute bridging necrosis, hepatitis, or massive necrosis were examined for the presence, composition, and distribution of inflammatory foci. Copper analysis was performed on the specimens. The foci of inflammation and necrosis composed a significant part of the lesion in 15 of the samples. The foci were of two types. One, characteristic of idiopathic chronic active hepatitis, consisted of one or two apoptotic hepatocytes attended by lymphocytes and plasma cells. These foci were found primarily in the vicinity of the portal tracts, not associated with centrolobular copper-laden hepatocytes. The other type of focus was characteristic of copper toxicosis. These foci were larger and composed of debris-filled macrophages, lymphocytes, plasma cells, and scattered neutrophils, and on occasion apoptotic hepatocytes were found at the periphery. These foci were always found around the central vein among the copper-laden hepatocytes. Such foci were found only in dogs with copper concentration > 2,000 parts/million on a dry weight basis. These morphologic studies show that clinical liver disease in WHWTs is caused by more than one etiologic agent. Among 17 WHWTs with clinical liver disease, two had copper toxicosis, five had idiopathic chronic active hepatitis, and 10 had hepatic disease of undetermined type.

Hepatocyte growth factor and c-met expression in Long-Evans Cinnamon rats with spontaneous hepatitis and hepatoma

The Long-Evans Cinnamon (LEC) rat is characterized by the spontaneous onset of acute and chronic hepatitis, followed by occurrence of liver cancer, and is thus able to provide a unique experimental model for human genetical liver disease, Wilson's disease. Hepatocyte growth factor (HGF) is a potent hepatotrophic factor in liver regeneration, and its expression is up-regulated in response to liver injuries. We found that the plasma HGF level in LEC rats rose markedly during the fulminant hepatitis phase, fell during the phase of chronic/cholangiofibrosis, and fluctuated during the hepatoma phase. Immunohistological staining of the liver revealed that the number of HGF-positive cells increased remarkably during the fulminant hepatitis phase, and that many of these cells were localized at the portal triads. Fewer HGF-positive cells were observed during the phase of chronic hepatitis. The surface of the hepatocellular carcinoma (HCC) cells and the cytoplasm of the nonepithelial cells in cancerous liver tissues were HGF-positive. The HGF-messenger RNA (mRNA) level in the liver rose in the fulminant hepatitis phase, fell in the chronic hepatitis phase, and was intermediate or high during the hepatoma phase. The expression of c-met mRNA was strong in the tissues of LEC rats with fulminant hepatitis and, especially, in the cholangiofibrosis tissues. c-met mRNA was also detected in HCCs. These results suggest that the HGF-c-met system may play an important role in the regeneration of hepatocytes as well as in the development of HCC in paracrine or autocrine mechanisms.

Posttranscriptional regulation of connexin 32 expression in liver during acute inflammation

Gap junctions mediate the communication between adjacent cells in tissues. In the liver, connexin 32 (Cx32) subunits make up the predominating gap junctions. The expression of Cx32 gene has been observed to be down-regulated in response to inflammatory states and during liver regeneration. In the present study we attempt to elucidate the molecular mechanisms underlying the down-regulation of the Cx32 expression during acute inflammation. A decrease in the level of Cx32 mRNA in rat liver occurred between 3 and 6 h after intravenous administration of bacterial lipopolysaccharide (LPS), simultaneously with the induction of an acute inflammatory response characterized by an increase in the level for beta-fibrinogen and a reduction of phosphoenolpyruvate carboxykinase mRNA. The reduction in Cx32 steady-state mRNA levels appears to occur at the posttranscriptional level, since the rate of degradation of this message seems to be higher than the rate of transcription of the gene. Degradation of Cx32 mRNA was blocked by the administration of actinomycin D, but not by cycloheximide, prior to injection of LPS. The stabilization of Cx32 message by actinomycin D correlated with the preservation of Cx32 on the cell surface, which otherwise disappears after administration of LPS alone. These results suggest that cellular communication via gap junctions could be regulated at the level of gene expression, by a posttranscriptional mechanism, during acute inflammatory states.

Influences of chronic cholangiohepatitis and cholestasis on hepatic metabolism of benzo[a]pyrene in white suckers (Catostomus commersoni) from industrially polluted areas of Lake Ontario

White suckers from polluted regions of western Lake Ontario have an increased prevalence of cholangiocellular and hepatocellular and hepatocellular neoplasms associated with an idiopathic chronic cholangiohepatitis. We examined the hypothesis that bile duct obstructions and cholestasis in these fish might increase the susceptibility of liver to administered benzo[a]pyrene (B[a]P). Cytosolic glutathione S-transferase (GST) activity (CDNB) was reduced in obstructed liver to 45% of activity in adjacent unobstructed liver. At micromolar concentrations, chenodeoxycholic acid, deoxycholic acid, bilirubin and haematin each inhibited GST activity of hepatic cytosolic and S-hexylglutatione-affinity-purified GST preparations from unobstructed liver. Liver cytosol and affinity-purified hepatic GSTs from normal white sucker liver reduced DNA binding of 3H-benzo[a]-pyrene-7,8-diol-9,10-epoxide (3H-BPDE) after preincubation in vitro in the presence of 5 mM GSH. Under these conditions, cytosol from adjacent unobstructed liver had a moderately stronger protective activity against DNA binding by BPDE (16.4 +/- 1.3 pmol BPDE/mg DNA) than did cytosol from obstructed liver (20.6 +/- 1.6 pmol BPDE/mg DNA). Suckers with obstructed livers identified by laparotomy were orally administered 3H-benzo[a]pyrene (3H-B[a]P) (0.2 mmol/kg) or unlabelled B[a]P (2.0 mg/kg) and the level of B[a]P macromolecular binding was analyzed in liver tissue by liquid scintillation counting and by immunohistochemistry with antibodies to BPDE-DNA adducts. Covalent binding of 3H-B[a]P to hepatic protein was 30% less in adjacent unobstructed liver compared to obstructed liver; however, there was no significant difference in the levels of 3H-B[a]P bound to DNA in the obstructed lobes compared with non-obstructed adjacent liver. These studies demonstrate that some endogenous non-substrate ligands that accumulate during cholestasis can reduce hepatic GST activity in white suckers. While these changes are insufficient to influence total 3H-B[a]P-DNA adducts in obstructed liver, the preferential localization of BPDE-DNA adducts in GST-deficient hyperplastic biliary tracts suggests that cholangiohepatitis might increase susceptibility to cholangiolar neoplasia in fish exposed to genotoxic polycyclic aromatic hydrocarbons.

Pathology and immunohistochemistry of callitrichid hepatitis, an emerging disease of captive New World primates caused by lymphocytic choriomeningitis virus

Callitrichid hepatitis is an arenavirus infection that recently emerged as a highly fatal disease of New World primates in the Callitrichidae family. As we previously reported, these primates develop hepatitis after contact with mice that are infected with variants of LCMV (LVMCCH), recently determined to have 86% identity with GC-P gene of the Armstrong and Western strains of LCMV. Here, we describe the histopathological lesions and tissue localization of viral antigens in confirmed cases of callitrichid hepatitis from recent outbreaks in two U.S. zoos. The liver in marmosets and tamarins with fatal infections consistently showed degeneration, necrosis, and inflammation, with variable involvement of the spleen, lymph nodes, adrenal glands, intestine, pancreas, and central nervous system. Lymphocytic choriomeningitis virus antigens were identified immunohistochemically in necrotic foci in these organs as well as in nondegenerating areas in lungs, kidney, urinary bladder, brain, and testes. The multi-organ tropism and histological pattern of LCMV infection in marmosets and tamarins are similar to those reported for the highly virulent arenavirus that causes Lassa fever in humans. Comparative studies of callitrichid hepatitis and Lassa fever would therefore be mutually beneficial for human and nonhuman primate medicine.

Changes in free radical-metabolizing enzymes and lipid peroxides in the liver of Long-Evans with cinnamon-like coat color rats

We report changes in free radical-metabolizing enzymes and the increased generation of lipid peroxides associated with extreme metal accumulation in the liver of the Long-Evans with cinnamon-like coat color (LEC) rat, a new mutant strain displaying hereditary hepatitis and subsequent hepatocellular carcinoma. The activity of free radical-metabolizing enzymes and lipid peroxides, and the concentration of metal in the liver were determined sequentially after birth. Mn-superoxide dismutase activity significantly increased immediately after the onset of hepatitis in LEC rats, whereas no remarkable change was observed in control rats. Cu, Zn-superoxide dismutase activity in LEC rats was similar to that in control rats. Glutathione reductase activity increased, while glutathione peroxidase activity was lower in LEC rats than in control rats throughout the observation periods. Lipid peroxides, estimated by thiobarbituric acid reaction, also increased 4- to 5-fold immediately after the onset of hepatitis in LEC rats. Copper concentration was 30- to 50-fold higher in the liver of LEC rats than in control rats, and the iron content also increased significantly before and after the onset of hepatitis. These findings suggested that an oxidant injury generated by toxic metals could be one of the factors responsible for hepatocellular damage in this unique hereditary hepatitis.

[Expression of hepatocyte growth factor (HGF) in LEC rats at various phases of hepatitis and hepatoma]

The role of hepatocyte growth factor (HGF) in LEC rats were investigated at various phases of liver diseases by the detection of HGF expression, using ELISA assay, mRNA analysis and immunohistochemistry. Levels of plasma HGF increase in the fulminant hepatitis phase, decreased during chronic/cholangiofibrosis phase, and in some LEC rats, high levels of HGF were observed in hepatoma phase. HGF mRNA level in the liver was very high in fulminant hepatitis phase and low in chronic hepatitis phase. In hepatoma phase, HGF mRNA level was intermediate or high in the liver. In fulminant hepatitis phase, HGF mRNA level in the lung was slightly increased, while it was almost stable in the kidney in all the conditions studied. Immunohistochemical studies revealed that the frequency of HGF positive cells increased remarkably in fulminant hepatitis phase, and that many of them were located at the portal triads. Fewer HGF-positive cells were found in chronic hepatitis phase and were not found in the tissue of cholangiofibrosis. HGF was found in the surface of hepatocellular carcinoma cells and in the cytoplasm of the non-epithelial cells in cancerous liver tissues. HGF-positive cells appeared 24h after partial hepatectomy, diffusely, and HGF mRNA increased earlier in the kidney and lung than in the liver. Moreover, HGF mRNA level was higher in the lung than in the liver. These results suggest that in the natural course of spontaneous hepatitis and hepatoma in LEC rats, HGF is expressed mainly in the liver and that HGF may play an important role in the regeneration of hepatocytes in a paracrine manner. In contrast, after partial hepatectomy, HGF produced in the lung may be effective for liver regeneration in an endocrine manner.

Novel insights into the biology and physiology of the Ito cell

Ito cells, perisinusoidal mesenchymal elements with possible pericytic functions within the liver, recently have been shown to play multiple physiological and pathophysiological roles. In particular, several in vivo and in vitro studies have clearly indicated that Ito cells play a relevant role in the progression of liver fibrogenesis. More recently, attention has been focussed on the mechanisms leading to Ito cell activation, proliferation and synthesis of extracellular matrix components. Among other soluble factors potentially involved in these processes, transforming growth factor-beta 1 and platelet-derived growth factor have been shown to act in a paracrine, and possibly autocrine, fashion on Ito cells, thus perpetuating their activated state. Finally, other studies have shown that Ito cells could play an active role in chronic liver tissue inflammation by promoting chemotaxis of infiltrating inflammatory cells.

Copper metabolism leading to and following acute hepatitis in LEC rats

The accumulation process of copper (Cu) in the liver and the following metabolic disorder of Cu were examined in LEC rats, a mutant strain which accumulates Cu with age and shows spontaneous acute hepatitis and/or hepatoma. Cu concentration in the liver of female rats was approximately 220 micrograms/g liver at 2 weeks of age, decreased to 100 micrograms/g liver at 4-6 weeks, and then started to increase with age linearly to the highest concentration of 250 micrograms/g liver at 16 weeks. Although the Cu level expressed by concentration (microgram/g liver) decreased during weaning, it increased linearly with age when it was expressed by content (mg/liver), indicating a constant and preferential accumulation of Cu in the liver. Cu concentration stopped increasing at 16 weeks in the liver, followed by a sudden decrease to 1/2 the highest level. Biological markers (serum lactate dehydrogenase and glutamic-oxaloacetic transaminase activities) for liver damage started to increase, together with the appearance of signs of jaundice, when Cu attained the highest concentration. Distributions of Cu and zinc (Zn) in the supernatant fraction of the liver indicated that both metals were mostly distributed to metallothionein (MT) and, to a small extent, to superoxide dismutase on a gel filtration column throughout the course of the experiments. Serum Cu concentration started to increase in a form of ceruloplasmin, together with serum marker enzyme activities for liver damage. Cu concentration in the kidneys also started to increase after the increase of serum Cu. The results indicate that Cu accumulates in the form of MT in the liver of LEC rats to a maximum level of approximately 250 micrograms/g liver, and then decreases suddenly with the onset of acute hepatitis. The maximum level seems to be related to the capacity of MT synthesis, and acute hepatitis is assumed to occur when Cu accumulates beyond the capacity. Serum Cu started to increase, from the abnormally low level, when the metal accumulated beyond the capacity of MT synthesis in the liver, and it was partly reabsorbed by the kidneys and the rest was excreted into urine. Changes in iron and zinc levels were determined and discussed in relation to those of Cu.