Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023890 (cirrhosis)
 42,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The liver is continuously exposed to a large antigenic load that includes pathogens, toxins, tumor cells and dietary antigens. Amongst the hepatitis viruses, only hepatitis B virus (HBV) and hepatitis C virus (HCV) cause chronic hepatitis, which can progress to cirrhosis and hepatocellular carcinoma. Of the different antiviral defense systems employed by the tissue, apoptosis significantly contributes to the prevention of viral replication, dissemination, and persistence. Loss of tolerance to the liver autoantigens may result in autoimmune hepatitis (AIH). This review outlines the recent findings that highlight the role and mechanisms of apoptotic processes in the course of liver diseases. Among factors that contribute to liver pathology, we discuss the role of tumor necrosis factor (TNF)-alpha, HBx, ds-PKR, TRAIL, FasL, and IL-1alpha. Since TNF and FasL-induced hepatocyte apoptosis is implicated in a wide range of liver diseases, including viral hepatitis, alcoholic hepatitis, ischemia/reperfusion liver injury, and fulminant hepatic failure, these items will be discussed in greater detail in this review. We also highlight some recent discoveries that pave the way for the development of new therapeutic strategies by protecting hepatocytes (for example by employing Bcl-2, Bcl-XL or A1/Bfl-1, IAPs, or synthetic caspase inhibitors), or by the induction of apoptosis in stellate cells. The assessment of the severity of liver disease, as well as monitoring of patients with chronic liver disease, remains a major challenge in clinical hepatology practice. Therefore, a separate chapter is devoted to a novel cytochrome c-based method useful for the diagnosis and monitoring of fulminant hepatitis.
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PMID:Apoptosis in liver diseases--detection and therapeutic applications. 1625 9

Hepatitis C virus (HCV) is the major causative agent of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, and can be involved in very long chronic infections up to 30 years or more. Therefore, it has been speculated that HCV possesses mechanisms capable of modulating host defense systems such as innate and adaptive immunity. To investigate this virus-host interaction, we generated HCV replicons containing various HCV structural proteins and then analyzed the sensitivity of replicon-containing cells to the apoptosis-inducing agent, TRAIL. TRAIL-induced apoptosis was monitored by cleavage of procaspase-3 and procaspase-9 as well as that of their substrate poly(ADP-ribose) polymerase. TRAIL-induced apoptosis was inhibited in cells expressing HCV E2. Moreover, expression of HCV E2 enhanced the colony forming efficiency of replicon-containing cells by 25-fold. Blockage of apoptosis by E2 seems to be related to inhibition of TRAIL-induced cytochrome c release from the mitochondria. Based on these results, we propose that E2 augments persistent HCV infection by blocking host-induced apoptosis of infected cells.
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PMID:E2 of hepatitis C virus inhibits apoptosis. 1633 62

Interleukin-6 (IL-6) is an important mediator of liver regeneration and repair that is also elevated in chronic liver diseases, including fatty liver of obesity and cirrhosis. IL-6 has been reported both to delay and accelerate liver regeneration. We examined the effects on liver injury and regeneration of a continuous administration of exogenous IL-6 to mice by injection of an IL-6-expressing CHO-cell line in athymic nude mice and by osmotic mini-pump delivery of recombinant murine IL-6. Short-term IL-6 administration (1-2 days) accelerated early recovery of liver mass, whereas more long-term administration (5-7 days) markedly impaired liver regeneration. Similarly, short-term IL-6 treatment increased hepatic resistance to the lethal effects of the Fas agonist Jo-2, but on more prolonged IL-6 exposure the Jo-2 resistance vanished. IL-6 administration initially induced expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL, correlating with protection against Fas-mediated cell death. More prolonged IL-6 administration, however, resulted in marked induction of the pro-apoptotic protein Bax. This result coincided with increased activation of the type II or intrinsic, mitochondrial path to cell death, manifested by increased caspase-9 activation and increased cytochrome c release after Jo-2 exposure. These data demonstrate that IL-6 can function acutely to improve hepatic regeneration and repair, but that more chronic exposure not only abolishes the protective effects of IL-6, but actually sensitizes the liver to injury and death. In conclusion, elevated IL-6 in certain chronic liver diseases contributes to an increased likelihood of liver failure after injury.
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PMID:Paradoxical effects of short- and long-term interleukin-6 exposure on liver injury and repair. 1649 6

We have investigated the mechanism of COX-2 (cyclo-oxygenase 2)-dependent inhibition of apoptosis in liver, a key pathway underlying proliferative actions of COX-2 in liver cancers, cirrhosis, chronic hepatitis C infection and regeneration after partial hepatectomy. Stable expression of COX-2 in CHL (Chang liver) cells induced proliferation, with an increase in the proportion of cells in S-phase, but no other significant changes in cell-cycle distribution. This was associated with a marked inhibition of the apoptotic response to serum deprivation, an effect mimicked by treating empty-vector-transfected control cells (CHL-V cells) with prostaglandin E2 and prevented in COX-2-expressing cells (CHL-C cells) treated with selective inhibitors of COX-2. Serum-deprived CHL-V cells displayed several indicators of activation of intrinsic apoptosis: caspases 9 and 3 activated within 6 h and caspase 8 within 18 h, Bax expression was induced, cytochrome c was released to the cytosol, and PARP-1 [poly(ADP-ribose) polymerase 1] cleavage was evident in nuclei. COX-2 expression blocked these events, concomitant with reduced expression of p53 and promotion of Akt phosphorylation, the latter indicating activation of survival pathways. CHL cells were resistant to stimulation of the extrinsic pathway with anti-Fas antibody. Moreover, in vivo expression of GFP (green fluorescent protein)-labelled COX-2 in mice by hydrodynamics-based transient transfection conferred resistance to caspase 3 activation and apoptosis induced by stimulation of Fas.
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PMID:Cyclo-oxygenase 2 expression impairs serum-withdrawal-induced apoptosis in liver cells. 1680 Aug 15

Patients coinfected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) have progressive liver disease that frequently leads to cirrhosis and death. We previously showed that hepatocytes exposed to HCV and HIV envelope proteins undergo apoptosis via an innocent-bystander mechanism as a result of the cell surface binding of these proteins, independent of direct viral infection. Here, we have defined the mechanism of this hepatocytic apoptosis. We observed enhanced signal transducer and activator of transcription factor 1 (STAT1) activation and phosphorylation after costimulation with HCV-E2 and HIV-gp120. Moreover, inhibitor studies indicated that Lyn kinase, p38 mitogen-activated protein kinase, and protein kinase C delta might be involved in STAT1 phosphorylation. To elucidate the downstream STAT1-mediated signaling, we overexpressed wild-type STAT1 alpha and the C-terminal domain-deleted mutant STAT1 beta . STAT1 alpha overexpression increased cell apoptosis and Fas ligand expression, compared with STAT1 beta overexpression. STAT1 alpha also enhanced the release of cytochrome c from the mitochondria and caspase-3 activity. These studies indicate that the HCV/HIV envelope proteins cooperatively induce hepatocytic apoptosis by activating a novel downstream STAT1 signaling pathway.
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PMID:Signal transducer and activator of transcription factor 1 mediates apoptosis induced by hepatitis C virus and HIV envelope proteins in hepatocytes. 1719 63

Alpha-lipoic acid (alpha-LA) is an antioxidant used for the treatment of a variety of diseases, including liver cirrhosis, heavy metal poisoining, and diabetic polyneuropathy. In addition to its protective effect against oxidative stress, alpha-LA induces apoptosis in different cancer cells types. However, whether alpha-LA acid induces apoptosis of hepatoma cells is unknown. Herein, we investigated whether alpha-LA induces apoptosis in two different hepatoma cell lines FaO and HepG2. The results showed that alpha-LA inhibits the growth of both cell lines as indicated by the reduction in cell number, the reduced expression of cyclin A and the increased levels of the cyclin/CDKs inhibitors, p27(Kip1) and p21(Cip1). Cell cycle arrest was associated with cell loss, and DNA laddering indicative of apoptosis. Apoptosis was preceded by increased generation of reactive oxygen species, and associated with p53 activation, increased expression of Bax, release of cytochrome c from mitochondria, caspases activation, decreased levels of survivin, induction of pro-apoptotic signaling (i.e JNK) and inhibition of anti-apoptotic signaling (i.e. PKB/Akt) pathways. In conclusion, this study provides evidence that alpha-LA induces apoptosis in hepatoma cells, describes a possible sequence of molecular events underlying its lethal effect, and suggests that it may prove useful in liver cancer therapy.
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PMID:Increased ROS generation and p53 activation in alpha-lipoic acid-induced apoptosis of hepatoma cells. 1713 95

Liver fibrosis and cirrhosis may be reversible, possibly through the selective clearance of activated hepatic stellate cells/myofibroblasts by apoptosis. Hepatic stellate cells transdifferentiate into myofibroblast-phenotype cells in culture, a process that recapitulates hepatic stellate cell activation in vivo. Bakuchiol, a prenylated phenolic terpene isolated from the seed of Psoralea corylifolia L. (Leguminosae), reduced activated hepatic stellate cells when treated to rats during liver injury recovery period as demonstrated by alpha-smooth muscle actin immunostaining in rat liver and induced apoptosis in activated hepatic stellate cells/myofibroblasts as demonstrated by DNA fragmentation, activation of caspase-3, release of cytochrome c into the cytoplasm, translocation of Bax into mitochondria, and the proteolytic cleavage of poly(ADP-ribose) polymerase (PARP) in vitro. Bakuchiol-induced apoptosis was prevented by z-DEVD-fmk, a specific inhibitor of caspase-3, and z-VAD-fmk, a general caspase inhibitor, suggesting that bakuchiol-induced apoptosis occurs through a caspase-3-dependent pathway in vitro. Bakuchiol treatment stimulated the activation of extracellular signal-regulated kinase 1/2 (ERK), c-Jun NH2-terminal protein kinase (JNK), and p38 mitogen-activated protein kinases (MAPK) in vitro. Pretreatment with SP600125 attenuated the bakuchiol-induced translocation of Bax into mitochondria, cytochrome c release into the cytosol, caspase-3 activation, and PARP cleavage. In contrast, preincubation with SB203580, a p38 MAPK inhibitor, and U0126, an ERK inhibitor, had no effect on bakuchiol-induced cell death and caspase-3 activity. Taken together, these findings indicate that bakuchiol induces caspase-3-dependent apoptosis through the activation of JNK, followed by Bax translocation into mitochondria in rat liver myofibroblasts.
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PMID:Bakuchiol-induced caspase-3-dependent apoptosis occurs through c-Jun NH2-terminal kinase-mediated mitochondrial translocation of Bax in rat liver myofibroblasts. 1729 78

Portal hypertension (PHT) gastropathy is a frequent complication of liver cirrhosis and one of the leading causes of death from cirrhosis. Apoptosis is widely considered to be an active energy-dependent mode of cell death and a distinct entity from necrotic cell death. It is unclear whether gastric mucosal apoptosis is involved in PHT gastropathy. Prostaglandins (PGs) produced through cyclooxygenase (COX) are thought to play a key role in protection of the gastrointestinal mucosa from injury and apoptosis. However, the role of COX in PHT gastropathy is still not clearly understood. The aims of this study were to investigate whether (1) gastric mucosal apoptosis is involved in PHT gastropathy and (2) downregulation of COX contributes to this apoptosis. In this study, we show that gastric mucosal apoptosis was remarkably increased while mucosal proliferation was inhibited in PHT rats. Gastric mucosal COX-1 was significantly suppressed at both the mRNA and protein levels, and PGE(2) was reduced in PHT rats. Further, PGE(2) treatment suppressed gastric mucosal apoptosis in PHT rats. However, gastric mucosal COX-2 levels did not differ between sham-operated rats and PHT rats. Gastric mucosal levels of tumor necrosis factor-alpha (TNF-alpha) and Fas ligand, but not TNF-related apoptosis-inducing ligand, were increased, and activated caspase-8 and caspase-3 levels were upregulated in PHT rats. The release of cytochrome c from the mitochondria to the cytosol was not observed in PHT rats. Our data indicate that downregulation of COX-1 is involved in gastric mucosal apoptosis via death signaling-mediated type-I cell death in PHT rats.
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PMID:Downregulation of cyclooxygenase-1 is involved in gastric mucosal apoptosis via death signaling in portal hypertensive rats. 1966 63

Mitochondrial dysfunction is a major mechanism of liver injury. A parent drug or its reactive metabolite can trigger outer mitochondrial membrane permeabilization or rupture due to mitochondrial permeability transition. The latter can severely deplete ATP and cause liver cell necrosis, or it can instead lead to apoptosis by releasing cytochrome c, which activates caspases in the cytosol. Necrosis and apoptosis can trigger cytolytic hepatitis resulting in lethal fulminant hepatitis in some patients. Other drugs severely inhibit mitochondrial function and trigger extensive microvesicular steatosis, hypoglycaemia, coma, and death. Milder and more prolonged forms of drug-induced mitochondrial dysfunction can also cause macrovacuolar steatosis. Although this is a benign liver lesion in the short-term, it can progress to steatohepatitis and then to cirrhosis. Patient susceptibility to drug-induced mitochondrial dysfunction and liver injury can sometimes be explained by genetic or acquired variations in drug metabolism and/or elimination that increase the concentration of the toxic species (parent drug or metabolite). Susceptibility may also be increased by the presence of another condition, which also impairs mitochondrial function, such as an inborn mitochondrial cytopathy, beta-oxidation defect, certain viral infections, pregnancy, or the obesity-associated metabolic syndrome. Liver injury due to mitochondrial dysfunction can have important consequences for pharmaceutical companies. It has led to the interruption of clinical trials, the recall of several drugs after marketing, or the introduction of severe black box warnings by drug agencies. Pharmaceutical companies should systematically investigate mitochondrial effects during lead selection or preclinical safety studies.
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PMID:Mitochondrial involvement in drug-induced liver injury. 2002 Feb 67

Portal hypertension is a major complication of cirrhosis that frequently leads to a neuropsychiatric disorder that affects cognition. We compared the performance of 18-month-old prehepatic portal hypertensive rats (PH) and 18-month-old normal rats (CO) in spatial short-term and reference memory tasks in the Morris water maze and in active avoidance task. The PH group showed worse spatial short-term memory than the CO group. Also, the PH group tended to perform worse than the CO group in the reference memory task, but it presented a correct acquisition of the active avoidance task. We assessed the brain metabolic activity of the animals by means of cytochrome c-oxidase (COx) histochemistry. We found that the PH group developed prefrontal dysfunction characterized by increased COx activity in this region compared to the CO group. Similar results were found in the medial mammillary nucleus and dentate gyrus, whereas the CA1 area, bed nucleus of the stria terminalis, and supramammillary nucleus showed lower COx activity in the PH group as compared to the CO group. We conclude that the 18-month-old portal hypertensive rats present spatial memory impairment without alteration of implicit learning. This deficit could be related to the alteration of the metabolic activity of the brain regions involved in the processing of spatial memories.
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PMID:Portal hypertension in 18-month-old rats: memory deficits and brain metabolic activity. 2018 5


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