SEARCH · Search PubMed

Results for “Choline Deficiency”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMed2000

Hyperthermia induces heat-shock protein expression, reduces pancreatic injury, and improves survival in necrotizing pancreatitis.

Heat-shock proteins (HSPs) function in the cellular response to injury. Increased expression of these proteins was first described in response to hyperthermia, although their production may be prompted by a variety of metabolic insults. HSPs protect cellular proteins from degradation. The self-limited pancreatitis induced by hyperstimulation with supramaximal doses of cerulein is accompanied by increased HSP expression. It may be that HSPs serve a protective function in pancreatitis. We hypothesized that hyperthermia-induced production of HSP-70 would improve survival in a lethal murine model of necrotizing pancreatitis. Necrotizing pancreatitis was induced in two groups of 30 female Swiss Webster mice by feeding them a choline-deficient diet supplemented with 0.5 g% ethionine (CDE) for 72 hours. Immediately before initiation of the CDE diet, the core body temperatures of the mice in the experimental group were elevated to 42 degrees C for 12.5 minutes. Twenty mice from each group were killed after 24 hours. Pancreata were harvested, and pancreatic proteins were extracted from half of the pancreata. HSP-70 was assessed according to a standard Western blotting protocol. The remaining pancreata were used to make histologic comparisons. Serum interleukin 6 and tumor necrosis factor-alpha were determined by enzyme-linked immunosorbent assay (ELISA). Survival was determined by observation of the remaining mice. HSP-70 was expressed in pancreatic protein from all mice exposed to hypothermia but in none of the mice subjected to the CDE diet alone. Mortality was significantly reduced in mice pretreated with hyperthermia compared with control mice (p < 0.05). Survival in the hyperthermia group was 80%, whereas in the control group it was 30%. Hyperthermia resulted in expression of pancreatic HSP-70 in mice. Hyperthermia also reduced mortality in this lethal murine model of necrotizing pancreatitis. It is plausible that a causal relationship exists between HSP-70 production and improved survival in this model.

Animals↗

PubMed1996

Appearance of oval cells in the liver of rats after long-term exposure to ethanol.

Epidemiological studies show an increased risk of developing liver cancer among alcoholics. There is some agreement that ethanol itself is not carcinogenic, but it may enhance the tumorigenic process by inducing drug-metabolizing enzymes, suppression of the immune system or by affecting DNA repair enzymes. Precisely how ethanol predisposes or promotes the development of hepatoma is unknown. Hepatocarcinogenesis induced by a choline-deficient, ethionine-supplemented (CDE) diet produces extensive alteration of the liver architecture with the emergence and rapid proliferation of oval cells. This study examines whether chronic alcohol consumption induces the proliferation of oval cells. Oval cells induced in rats maintained on a 5% ethanol liquid diet (ELD) for up to 24 months, or fed a CDE diet for up to 4 weeks, are compared using a panel of liver-specific markers. In CDE-treated rats, oval cells staining positively for alpha-fetoprotein (AFP), pi-class glutathione S-transferase (pi GST), and the embryonic form of pyruvate kinase (M2-PK) are observed after 1 week. Similar cells are seen in ELD-treated rats after 2 months. Their numbers increase with time, and incorporation of [3H]thymidine confirms they are a dividing population. Acute damage induced by partial hepatectomy and CCI4 poisoning did not induce the appearance of oval cells. We conclude that chronic ethanol consumption induces oval cell proliferation. We suggest that, in addition to other proposed mechanisms, an alteration in cellular composition of the liver be considered as an explanation for the increased incidence of liver cancer among alcoholics.

Animals↗

PubMed2006

Glutathione-enhancing agents protect against steatohepatitis in a dietary model.

UNLABELLED: Nonalcoholic fatty liver (NAFL) and steatohepatitis (NASH) may accompany obesity, diabetes, parenteral nutrition, jejeuno-ileal bypass, and chronic inflammatory bowel disease. Currently there is no FDA approved and effective therapy available. We investigated the potential efficacy of those agents that stimulate glutathione (GSH) biosynthesis on the development of experimental steatohepatitis. Rats fed (ad libitum) amino acid based methionine-choline deficient (MCD) diet were further gavaged with (1) vehicle (MCD), (2) S-adenosylmethionine (SAMe), or (3) 2(RS)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA). RESULTS: MCD diet significantly reduced hematocrit, and this abnormality improved in the treated groups (p < 0.01). Serum transaminases were considerably elevated (AST: 5.8-fold; ALT: 3.22-fold) in MCD rats. However, administration of GSH-enhancing agents significantly suppressed these abnormal enzyme activities. MCD rats developed severe liver pathology manifested by fatty degeneration, inflammation, and necrosis, which significantly improved with therapy. Blood levels of GSH were significantly depleted in MCD rats but normalized in the treated groups. Finally, RT-PCR measurements showed a significant upregulation of genes involved in tissue remodeling and fibrosis (matrix metalloproteinases, collagen-alpha1), suppressor of cytokines signaling1, and the inflammatory cytokines (IL-1beta, IL-6, TNF-alpha, and TGF-beta) in the livers of rats fed MCD. GSH-enhancing therapies significantly attenuated the expression of deleterious proinflammatory and fibrogenic genes in this dietary model. This is the first report that oral administration of SAMe and PTCA provide protection against liver injury in this model and suggests therapeutic applications of these compounds in NASH patients.

Animals↗

PubMed1990

Genetics and diet: synergism in hepatocarcinogenesis in rats.

In previous studies we have shown that male rats carrying genes controlling growth and reproduction (grc) linked to the major histocompatibility complex (MHC) to be more susceptible to N-2-acetylaminofluorene than rats without grc genes. In the present studies we show that by manipulation of the diet of grc rats, hepatocarcinogenesis induced by another carcinogen can be altered. Male rats with the grc gene (R16) and wild type (ACP) were initiated with diethylnitrosamine (DEN) (200 mg/kg body weight). Some were fed laboratory chow (LC) for 9 months; others were fed a choline-supplemented (CS) or a choline-deficient (CD) diet. The rats were killed at various time periods and the liver sections were stained with H&E and for gamma-glutamyltranspeptidase (GGT). After 9 months on LC, the livers of R16 showed greater size and number of GGT-positive foci, bile duct proliferation, cellular atypia, cirrhosis, and nodular hyperplasia than the ACP. While the first hepatocellular carcinoma in R16 fed either a CS or LC was seen at 9-10 months, one R16 rat fed a CD diet had liver cancer at 4 months. On a CS diet the R16 showed greater GGT-positive foci at 2 months than the ACP. On a CD diet the R16 showed even greater size and number of GGT-positive foci. At 12 months, 15 of 22 (68%) of the R16 rats on a CD diet had liver cancer and seven of 24 (29%) of the R16 on a CS diet. Of the ACP, none of 15 (0%) on CS and one of 18 (6%) on CD diet had liver tumors. The results show that the grc genes confer high susceptibility to liver cancer, which is enhanced by a CD diet, suggesting synergism between genetics and diet.

2-Acetylaminofluorene↗

PubMed2005

Mice heterozygous for the Mdr2 gene demonstrate decreased PEMT activity and diminished steatohepatitis on the MCD diet.

BACKGROUND/AIMS: The administration of a methionine and choline deficient (MCD) diet to mice serves as an animal model of NASH. The multidrug resistant 2 (Mdr2) P-glycoprotein encodes for the canalicular phospholipid transporter, and Mdr2 (+/-) mice secrete 40% less phosphatidylcholine than wild-type mice. We have hypothesized that phosphatidylethanolamine-N-methyl transferase (PEMT) up-regulation is a consequence of MCD diet administration, and is important for the pathogenesis of steatohepatitis in this model. However, the effect of decreased phosphatidylcholine secretion and modulation of PEMT on the development of diet-induced steatohepatitis in Mdr2 (+/-) mice has not been explored. Thus, the purpose of the study is to examine the effects of the MCD diet on Mdr2 (+/-) mice. METHODS: Mdr2 (+/-) and Mdr2 (+/+) mice were treated with an MCD or control diet for up to 30 days, and the severity of steatohepatitis, PEMT activity and hepatic S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) levels were measured. RESULTS: Serum ALT levels, hepatic inflammation, and PEMT activity were significantly lower, and hepatic SAM:SAH ratios were significantly higher in Mdr2 (+/-) mice at 7 and 30 days on the MCD diet. CONCLUSIONS: Mdr2 (+/-) mice have diminished susceptibility to MCD diet-induced NASH, which is associated with a relative decrease in PEMT activity and increased SAM:SAH ratios.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

Alterations of the transforming growth factor-beta signaling pathway in hepatocellular carcinomas induced endogenously and exogenously in rats.

To elucidate involvement of the transforming growth factor-beta (TGF-beta) signaling pathway in endogenous and exogenous liver carcinogenesis, we investigated mutations of TGF-beta receptor type II (TGF-betaRII), Smad2 and Smad4 genes, and expression of TGF-betaRII in hepatocellular carcinomas (HCCs) induced by a choline-deficient L-amino acid-defined (CDAA) diet and by N-nitrosodiethylamine (DEN). Male Fischer 344 rats received a CDAA diet continuously and HCCs were sampled after 75 weeks. Administration of DEN was followed by partial hepatectomy (PH), with colchicine to induce cell cycle disturbance and a selection pressure regimen, HCCs being obtained after 42 weeks. Total RNAs were extracted from individual HCCs and mutations in TGF-betaRII, Smad2 and Smad4 were investigated by reverse transcription (RT)-polymerase chain reaction (PCR)-restriction-single-strand conformation polymorphism (SSCP) analysis followed by sequencing analysis. Mutations of Smad2 were detected in 2 out of 12 HCCs (16.7%) induced by the CDAA diet, a GGT-to-GGC transition (Gly to Gly) at codon 30 and a TCT-to-GCT (Ser to Ala) transversion at codon 118, without any TGF-betaRII or Smad4 alterations. No mutations of TGF-betaRII, Smad2 and Smad4 were encountered in eleven HCCs induced by the exogenous carcinogen. Semi-quantitative RT-PCR revealed reduced expression of TGF-betaRII in 2 HCCs (16.7%) without Smad2 mutations out of 12 HCCs induced by the CDAA diet and none of 11 induced by DEN. These results suggest that the TGF-beta signaling pathway may be disturbed in endogenous liver carcinogenesis in rats.

Alkylating Agents↗

PubMed1997

Sinusoidal flow block after warm ischemia in rats with diet-induced fatty liver.

Donor livers with massive fatty infiltration reportedly are susceptible to ischemia/reperfusion injury after transplantation, which contributes to risk of primary nonfunction. We investigated the effect of warm ischemia and reperfusion on sinusoidal microcirculation in rats with fatty livers from a choline-deficient diet. Rats were subjected to partial hepatic warm ischemia for 30, 60, or 90 min. In a second study, an anti-ICAM-1 monoclonal antibody was injected intraportally 2 min after a 60-min ischemic period. In both studies, injury was assessed by liver histology 6 hr after vascular clamp release and by animal survival. After 30 min of hepatic warm ischemia, almost all control and fatty-liver rats survived 7 days. After 60-min ischemia, however, survival was significantly less in rats with fatty livers than in controls with normal livers (10% vs 90%, P < 0.0001). Histologically, rats with fatty livers showed marked sinusoidal congestion, especially in the midzone of the acinus, while control rats showed no disturbance in microcirculation. In rats with fatty livers treated with intraportal injection of an anti-ICAM-1 antibody, sinusoidal microcirculation was well preserved and the 7-day survival rate after warm ischemia was improved (50% vs no antibody 10%; P = 0.0112). In fatty livers, midzonal sinusoidal flow block occurs after hepatic warm ischemia and reperfusion. Although intraportal injection of an anti-ICAM-1 monoclonal antibody corrected this microcirculatory failure, animal survival was not as good as for controls without fatty livers. These results suggest that both sinusoidal microcirculatory failure and ischemic hepatocellular damage contribute to warm ischemia/reperfusion injury in fatty livers.

Animals↗

PubMed2000

Angiogenesis inhibitor TNP-470 suppresses the progression of experimentally-induced hepatocellular carcinoma in rats.

We evaluated the effects of angiogenesis inhibitor, TNP-470, on hepatocellular carcinoma (HCCs) induced by a choline-deficient L-amino acid defined (CDAA) diet in rats. Male Fisher 344 rats were fed CDAA for 68 weeks. Rats were treated by subcutaneous injection of TNP-470 (15 mg/kg) or saline (control) three times per week from 53 to 68 weeks. At the end of the experiment, we determined the frequency and size of HCCs and glutathione S-transferase placental form (GSTP)-positive lesions, histology of liver cirrhosis, liver function, and liver weight per body weight. We also determined, using histologic and immunohistochemical semiquantification analyses, the degree of vascularity, apoptosis and proliferation in HCC and adjacent tissues. Treatment with TNP-470 resulted in a reduction of the size and frequency of HCC compared to untreated rats. However, TNP-470 did not influence the histology of liver cirrhosis and liver function. The liver weight per body weight of TNP-470-treated rats was slightly heavier in comparison with that of the controls. Treatment with TNP-470 significantly reduced tumor vascularity relative to the controls. There were no significant differences in the Ki-67 labeling index of HCCs between TNP-470 treated and control rats. The frequency of apoptotic hepatoma cells in TNP-470-treated rats was higher than in control rats. Our results indicate that TNP-470 suppresses the progression of CDAA-induced HCCs in rats through inhibition of angiogenesis, and suggest that TNP-470 might be useful clinically for HCCs.

Angiogenesis Inhibitors↗

PubMed1990

Nuclear DNA content of altered hepatic foci in a rat liver carcinogenesis model.

In individual altered hepatic foci (AHF), aneuploidy occurs before malignant changes can be diagnosed histologically (O. Sudilovsky and T. K. Hei. Fed. Proc., 42:2225, 1983). In the current experiments Sprague-Dawley rats of both sexes were given i.p. injections of diethylnitrosamine (50 mg/kg body weight) 18 h after partial hepatectomy and were given a choline-sufficient diet (CS) for 1 wk. Four treatment groups were then formed and fed CS, CS containing 0.05% phenobarbital (PHB), choline-deficient diet (CD), and CD with 0.05% PHB. An extra female group received infusions of saline after the hepatectomy and fared CD. Control animals were partially hepatectomized, inoculated i.p. with saline, and placed on CS. The rats were sacrificed 16 wk later, liver sections were stained with a combined Feulgen-gamma-glutamyl transpeptidase stain, and the DNA content of gamma-glutamyl transpeptidase-positive foci was measured cytospectrophotometrically. There were no AHF in the control animals. Hepatocytes from control livers and cells adjacent to foci in treated livers had peaks corresponding to the 2C, 4C, and 8C range. In AHF the ploidy, however, was predominantly diploid, tetraploid, or heterogeneous. The ratio of diploid to tetraploid cells in foci of rats provided with CS + PHB was 5.5 and in those supplied with CD + PHB was 0.09. This suggested that dietary manipulations change the nuclear DNA distribution of AHF. Aneuploidy was also present, as expected, in 4 of 33 AHF in the animals placed on CD + PHB. It was observed as well in 2 of 26 AHF of rats given CD but in none of the 20 AHF fed CS + PHB. These data indicate that CD (which acts as both initiator and promoter) may be responsible for the appearance of aneuploidy. A general model, based on these results and the clonality of each individual focus, is proposed for the development of cells through the preneoplastic stage.

Aneuploidy↗

PubMed1996

Dual phenotypic expression of hepatocytes and bile ductular markers in developing and preneoplastic rat liver.

This study supports the existence of a pluripotent liver stem cell population which has the potential to differentiate into hepatocytes and bile ductular cells. We compared the expression of hepatocyte-specific and bile ductular-specific markers in fetal and preneoplastic rat liver. L-pyruvate kinase (L-PK) and alpha glutathione S-transferase (GST) were used as adult hepatocyte-specific markers, while cytokeratin 19 (CK19) was used as a bile ductular-specific marker. pi GST and M2-pyruvate kinase (M2-PK), which are fetal hepatocyte-specific and expressed at high levels in the oval and duct-like cells, were also used. We characterized fetal liver derived from 13-21 days of gestation (E13-E21). pi GST was detected in the E18 hepatoblasts, which form the intrahepatic bile ducts, while CK19 was detected at E19. Some of these cells express alpha GST and L-PK from E19 to E21. Oval, duct-like and bile ductular cells in rats treated with a choline-deficient diet containing 0.07% ethionine (CDE diet) for up to 8 weeks were characterized by double immunocytochemistry. L-PK and alpha GST are absent from bile ductular cells in the normal adult liver and up to 3 weeks of CDE treatment. After 4-5 weeks on CDE treatment, the majority of bile ductular cells express L-PK, while at 6 weeks some co-express L-PK and alpha GST. There are two populations of oval cells, a major population expressing only the fetal hepatocyte markers, while a minor population expresses the fetal hepatocyte, adult hepatocyte and bile ductular markers. There are at least three different duct-like cell populations which co-express different markers and have characteristics of fetal hepatocytes at sequential stages of differentiation. One population co-expresses pi GST and M2-PK and is similar to fetal hepatocytes derived from E13-E14 fetuses. The second expresses the two fetal markers and L-PK, and this reflects characteristics of E15 hepatocytes. The third expresses pi GST, M2-PK, L-PK and alpha GST which is characteristic of E16-E19 hepatocytes. Upon withdrawal of the CDE diet, autoradiography using tritiated thymidine shows that oval and duct-like cells differentiate into hepatocytes. This study demonstrates that oval and duct-like cells express both hepatocytic and bile ductular markers, and have the capacity to differentiate into hepatocytes, characteristics similar to hepatoblasts in the developing rat liver.

Animals↗

PubMed1995

Decreased mortality of severe acute pancreatitis after proximal cytokine blockade.

OBJECTIVE: This study determined the ability of interleukin-1 receptor antagonist (IL-1ra) to decrease the mortality of experimental acute pancreatitis. The response of the inflammatory cytokine cascade and its subsequent effects on pancreatic morphology were measured to determine the role of these peptides in mediating pancreatic injury. SUMMARY BACKGROUND DATA: Previous studies have shown that proinflammatory cytokines are produced in large amounts during acute pancreatitis and that blockade at the level of the IL-1 receptor significantly decreases intrinsic pancreatic damage. The subsequent effect on survival is not known. METHODS: A lethal form of acute hemorrhagic necrotizing pancreatitis was induced in young female mice by feeding a choline-deficient, ethionine supplemented (CDE) diet for 72 hours. For determination of mortality, the animals were divided into 3 groups of 45 animals each: control subjects received 100/microL normal saline intraperitoneally every 6 hours for 5 days; IL-1ra early mice received recombinant interleukin-1 receptor antagonist 15 mg/kg intraperitoneally every 6 hours for 5 days beginning at time 0; IL-1ra late mice received IL-1ra 15 mg/kg intraperitoneally every 6 hours for 3.5 days beginning 1.5 days after introduction of the CDE diet. A parallel experiment was conducted simultaneously with a minimum of 29 animals per group, which were sacrificed daily for comparisons of serum amylase, lipase, IL-1, IL-6, tumor necrosis factor-alpha, IL-1ra, pancreatic wet weight, and blind histopathologic grading. RESULTS: The 10-day mortality in the untreated control group was 73%. Early and late IL-1ra administration resulted in decreases of mortality to 44% and 51%, respectively (both p < 0.001). Interleukin-1 antagonism also was associated with a significant attenuation in the rise in pancreatic wet weight and serum amylase and lipase in both early and late IL-1ra groups (all p < 0.05). All control animals developed a rapid elevation of the inflammatory cytokines, with maximal levels reached on day 3. The IL-1ra-treated animals, however, demonstrated a blunted rise of these mediators (all p < 0.05). Blind histologic grading revealed an overall decrease in the severity of pancreatitis in those animals receiving the antagonist. CONCLUSIONS: Early or late blockade of the cytokine cascade at the level of the IL-1 receptor significantly decreases the mortality of severe acute pancreatitis. The mechanism by which this is accomplished appears to include attenuation of systemic inflammatory cytokines and decreased pancreatic destruction.

Acute Disease↗

PubMed1983

Prostaglandins and acute pancreatitis--experimental and clinical studies.

Acute pancreatitis has a mortality of 10-20 per cent, and in cases of acute haemorrhagic pancreatitis this rises to 80-90 per cent. At present there is no reliable treatment for this condition. Based on the hypothesis that the release locally and systemically of the intracellularly activated pancreatic digestive enzymes is due to cell membrane instability, we have studied the cytoprotective (cell membrane stabilizing) role of prostaglandins in this condition. In the first part of this study, an animal model of acute pancreatitis with a mortality of 100 per cent by 14 days has been established by feeding mice a choline-deficient ethionine supplemented diet. Using this model we have demonstrated improved survival (16 out of 50 survived 14 days or longer) by administering prostaglandin E2 subcutaneously (P less than 0 X 02). We have demonstrated that the improved survival is dose-dependent, in the range 2 X 5-5 X 0 mg/kg body weight 8 hourly (P less than 0 X 02) and time-dependent, still being effective if treatment is delayed for 24 h (P less than 0 X 02). Great emphasis has been placed on not commencing treatment until after the induction of acute pancreatitis. In the second part we have used cell membrane marker enzymes to study the cell membrane stabilizing effect of prostaglandin E2 in the human. It has been demonstrated that cell membrane instability occurs. In 12 of 50 episodes treated by prostaglandin E2 infusion, the lysosomal, mitochondrial and cell membranes are stabilized, thus decreasing the release of intracellular enzymes.

Acute Disease↗

PubMedDate not supplied

Localization of increased hepatic vascular resistance in liver cirrhosis.

To determine the localization of increased vascular resistance in cirrhotic liver, blood pressures were measured by a direct cannulation method at several key points in the hepatic vascular pathway in normal and cirrhotic rats. Cirrhosis was produced by feeding a choline-deficient diet. Blood pressures in normal rats were 110 mm H2O in the portal vein, 68 mm H2O in the terminal portal venule, 28 mm H2O in the terminal hepatic venule and 20 mm H2O in the inferior vena cava. In cirrhotic rats, blood pressures in the portal vein and the terminal portal venule were 173 and 100 mm H2O, respectively, while those in the terminal hepatic venule and the inferior vena cava were elevated only slightly above normal. These hemodynamic data suggest that an increase in vascular resistance in cirrhotic liver is present in the intrahepatic portal vein and sinusoids, but not in intrahepatic hepatic vein. In cirrhotic liver, stenosis and distortion were found in peripheral branches of the portal vein, and sinusoidal stenoses and a decrease in sinusoidal space were recognized. Accordingly, it is suggested that the increase in vascular resistance in the intrahepatic portal vein and sinusoids correlate with these structural changes. Although severe stenoses and distortion were found in hepatic vein branches, it was thought that they do not contribute to portal hypertension because of lack of increase in vascular resistance in the intrahepatic hepatic vein.

Animals↗

PubMed1994

Liver injury following normothermic ischemia in steatotic rat liver.

The influence of normothermic ischemia on steatotic liver was compared with that on healthy liver in rats. Steatotic liver was induced with 4 wk of a choline-deficient diet. We used a procedure of subcutaneous spleen transposition to develop portosystemic collaterals to avoid splanchnic stasis during total hepatic vascular occlusion. One-week survival rates after 30, 45, and 60 min of normothermic ischemia were 75%, 20% and 0% in the steatotic liver group and 100%, 90% and 70% in the control group, respectively. Significantly poor restoration of energy metabolism was observed in the steatotic liver group. After 1 hr of reflow following 45 and 60 min of ischemia, ATP was restored to 74% and 50%, respectively, of the preischemic level in healthy liver but to only 44% and 27% respectively, in steatotic liver. Microscopically, focal hemorrhage, disruption of the sinusoidal microvasculature and occasional spotty necrosis of hepatocytes were demonstrated after 1 hr of reflow following ischemia in steatotic liver, but no significant changes were evident in healthy liver. This microcirculatory alteration seems to be responsible for the loss of organ viability in steatotic liver. We suggest that steatotic liver is more vulnerable than healthy liver to normothermic ischemia in the rat.

Adenine Nucleotides↗

PubMed2004

Administration of the potent PPARalpha agonist, Wy-14,643, reverses nutritional fibrosis and steatohepatitis in mice.

Administration of a methionine and choline deficient (MCD) diet to rodents causes progressive fibrosing steatohepatitis pathologically similar to human metabolic steatohepatitis. We have previously shown that the peroxisome proliferator-activated receptor-alpha (PPARalpha) agonist, Wy-14,643, prevented the development of MCD diet-induced steatohepatitis. We have now tested whether Wy-14,643 ameliorates established steatohepatitis and fibrosis. Male C57BL6 mice were fed the MCD diet for 51 days to induce severe steatohepatitis. They were then treated with Wy-14,643 together with the MCD diet for 5 or 12 days; positive controls continued on the MCD diet for 5 or 12 days. After 5 days of Wy-14,643 treatment, alanine aminotransferase (ALT) levels were significantly decreased, steatohepatitis less severe, and hepatic lipoperoxides significantly reduced. After 12 days, hepatic triglycerides were normalized and there was near resolution of histological changes. MCD dietary feeding was associated with increased expression of vascular cell adhesion molecule (VCAM)-1, and increased numbers of activated macrophages in the liver. Treatment with Wy-14,643 reduced VCAM-1 expression and macrophage numbers. MCD diet-fed mice developed hepatic fibrosis with increased hepatic collagen alpha1(I), tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, and matrix metalloproteinase (MMP)-13 mRNA levels. After treatment with Wy-14,643, expression of these genes was reduced in a manner that paralleled the reduction in activated hepatic stellate cells and near resolution of liver fibrosis. In conclusion, the present study shows that MCD diet-induced fibrosing steatohepatitis can be reversed by treatment with Wy-14,643. It is likely that activation of PPARalpha reverses fibrosis indirectly by reducing stimuli, such as lipid peroxides, and activation of cells responsible for promoting hepatic fibrosis.

Animals↗

PubMed2006

Antiproliferative effects of interferon alpha on hepatic progenitor cells in vitro and in vivo.

Hepatic progenitor cells (called oval cells in rodents) proliferate during chronic liver injury. They have been suggested as targets of malignant transformation in chronic liver diseases, including chronic hepatitis C. Interferon alpha therapy reduces the risk of hepatocellular carcinoma (HCC) in chronic hepatitis C regardless of viral clearance. The aim of this study was to determine whether interferon alpha could reduce the risk of HCC by modifying preneoplastic events in the hepatic progenitor cell population. Pre- and post-treatment liver biopsies were evaluated for changes in t he hepaticprogenitor cell population in 16 patients with non-responding chronic hepatitis C Interferon alpha-based treatment significantly reduced the numbers of c-kit-positive hepatic progenitor cells by 50%. To determine the mechanism of cell number reduction, the effects of interferon alpha on murinehepatic progenitor cells were studied in vitro. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) proliferation assay and proliferating cell nuclear antigen staining showed that interferon alpha had a dose-dependent, anti-proliferative effect Interferon alpha stimulated hepatocytic and biliary differentiation of the oval cell lines reflected by increased expression of albumin and cytokeratin19 accompanied by decreased expression of alphafetoprotein and Thy-1. To validatethese results in vivo, mice were placed on the choline-deficient, ethionine-supplemented diet to induce liver injury and oval cell proliferation and treated with pegylated interferon alpha 2b for 2 weeks. This resulted in a significant four-fold reduction in the number of oval cells (P < .05). In conclusion, interferon alpha-based treatment reduced the number of hepatic progenitor cells in chronic liver injury by modulating apoptosis, proliferation, and differentiation. Supplementay material for this article can

Animals↗

PubMed2007

Transforming growth factor-beta differentially regulates oval cell and hepatocyte proliferation.

UNLABELLED: Oval cells are hepatocytic precursors that proliferate in late-stage cirrhosis and that give rise to a subset of human hepatocellular carcinomas. Although liver regeneration typically occurs through replication of existing hepatocytes, oval cells proliferate only when hepatocyte proliferation is inhibited. Transforming growth factor-beta (TGF-beta) is a key inhibitory cytokine for hepatocytes, both in vitro and in vivo. Because TGF-beta levels are elevated in chronic liver injury when oval cells arise, we hypothesized that oval cells may be less responsive to the growth inhibitory effects of this cytokine. To examine TGF-beta signaling in vivo in oval cells, we analyzed livers of rats fed a choline-deficient, ethionine-supplemented (CDE) diet for phospho-Smad2. Phospho-Smad2 was detected in more than 80% of hepatocytes, but staining was substantially reduced in oval cells. Ki67 staining, in contrast, was significantly more common in oval cells than hepatocytes. To understand the inverse relationship between TGF-beta signaling and proliferation in oval cells and hepatocytes, we examined TGF-beta signaling in vitro. TGF-beta caused marked growth inhibition in primary hepatocytes and the AML12 hepatocyte cell line. Two oval cell lines, LE/2 and LE/6, were less responsive. The greater sensitivity of the hepatocytes to TGF-beta-induced growth inhibition may result from the absence of Smad6 in these cells. CONCLUSION: Our results indicate that oval cells, both in vivo and in vitro, are less sensitive to TGF-beta-induced growth inhibition than hepatocytes. These findings further suggest an underlying mechanism for the proliferation of oval cells in an environment inhibitory to hepatocytic proliferation.

Animals↗

PubMed1989

Effect of ethanol on hepatocarcinogenesis initiated in rats with 3'-methyl-4-dimethylaminoazobenzene in the absence of liver injuries.

In this study special care was taken to discriminate between the direct effect of ethanol on hepatocarcinogenesis and secondary effects such as choline deficiency or fatty liver. Rats were divided into 2 groups, D and N. Group D was initiated using 3'-Me-DAB, while the control group N was not initiated. Groups N and D were divided into 4 sub-groups. Each subgroup was given, in the drinking water, one of the following ethanol solutions: 0, 5, 10 or 15% for 45 weeks. Liver tumors were induced only in D groups. Evidence obtained indicates that: (a) in the N group, ethanol did not cause any apparent disorders in histology and lipid metabolism, and (b) in the D group no significant differences were observed in the incidence of HCCs and other liver lesions. Ethanol thus does not appear to enhance hepatocarcinogenesis, at least in the absence of liver injury.

Animals↗