Defying death: the hepatocyte's survival kit

Aqueous extract from Madhuca indica bark protects cells from oxidative stress caused by electron beam radiation: in vitro, in vivo and in silico approach

In an endeavor to find the novel natural radioprotector to secure normal cells surrounding cancerous cell during radiation exposure, Madhuca indica (M. indica) aqueous stem bark extract was evaluated for radioprotective activity using in vitro, in vivo, and in silico models. M. indica extract exhibited concentration dependent protective effect on electron beam radiation (EBR) induced damage to pBR322 DNA; the highest protection was achieved at 150 μg concentrations. Similarly, M. indica extract (400 mg/kg) administrated to mice prior to irradiation protected DNA from the radiation damage, which was confirmed by inhibiting comet parameters. The study showed a significant increase in the levels of glutathione and superoxide dismutase levels. The study also revealed that administration of M. Indica at the different dose to mice significantly reduced EBR induced MDA, sialic acid and nitric acid levels. Further extract prevented histophatological changes of skin and liver. In contrast, protein-protein interaction studies were performed to find the hub protein, involved in radiation-induced DNA damage. Among 437 proteins that are found expressed during radiation, p53 was found to be a master protein regulating the whole pathway. Molecular interaction between p53 and M. indica extract was predicted by quantitative structure-activity relationship and ADMET properties. Biomolecules such as quercetin, myricetin, and 7-hydroxyflavone were found to be promising inhibitors of p53 protein and may help in the protection of EBR induced DNA damage during cancer treatment.

β-Arrestin 2 Promotes Hepatocyte Apoptosis by Inhibiting Akt Protein

Recent studies reveal that multifunctional protein β-arrestin 2 (Arrb2) modulates cell apoptosis. Survival and various aspects of liver injury were investigated in WT and Arrb2 KO mice after bile duct ligation (BDL). We found that deficiency of Arrb2 enhances survival and attenuates hepatic injury and fibrosis. Following BDL, Arrb2-deficient mice as compared with WT controls displayed a significant reduction of hepatocyte apoptosis as demonstrated by the TUNEL assay. Following BDL, the levels of phospho-Akt and phospho-glycogen synthase kinase 3β (GSK3β) in the livers were significantly increased in Arrb2 KO compared with WT mice, although p-p38 increased in WT but not in Arrb2-deficient mice. Inhibition of GSK3β following BDL decreases hepatic apoptosis and decreased p-p38 in WT mice but not in Arrb2 KO mice. Activation of Fas receptor with Jo2 reduces phospho-Akt and increases apoptosis in WT cells and WT mice but not in Arrb2-deficient cells and Arrb2-deficient mice. Consistent with direct interaction of Arrb2 with and regulating Akt phosphorylation, the expression of a full-length or N terminus but not the C terminus of Arrb2 reduces Akt phosphorylation and coimmunoprecipates with Akt. These results reveal that the protective effect of deficiency of Arrb2 is due to loss of negative regulation of Akt due to BDL and decreased downstream GSK3β and p38 MAPK signaling pathways.

Metformin protects rat hepatocytes against bile acid-induced apoptosis

BACKGROUND

Metformin is used in the treatment of Diabetes Mellitus type II and improves liver function in patients with non-alcoholic fatty liver disease (NAFLD). Metformin activates AMP-activated protein kinase (AMPK), the cellular energy sensor that is sensitive to changes in the AMP/ATP-ratio. AMPK is an inhibitor of mammalian target of rapamycin (mTOR). Both AMPK and mTOR are able to modulate cell death.

AIM

To evaluate the effects of metformin on hepatocyte cell death.

METHODS

Apoptotic cell death was induced in primary rat hepatocytes using either the bile acid glycochenodeoxycholic acid (GCDCA) or TNFα in combination with actinomycin D (actD). AMPK, mTOR and phosphoinositide-3 kinase (PI3K)/Akt were inhibited using pharmacological inhibitors. Apoptosis and necrosis were quantified by caspase activation, acridine orange staining and Sytox green staining respectively.

RESULTS

Metformin dose-dependently reduces GCDCA-induced apoptosis, even when added 2 hours after GCDCA, without increasing necrotic cell death. Metformin does not protect against TNFα/ActD-induced apoptosis. The protective effect of metformin is dependent on an intact PI3-kinase/Akt pathway, but does not require AMPK/mTOR-signaling. Metformin does not inhibit NF-κB activation.

CONCLUSION

Metformin protects against bile acid-induced apoptosis and could be considered in the treatment of chronic liver diseases accompanied by inflammation.

Sphingosine kinase-1 inhibition protects primary rat hepatocytes against bile salt-induced apoptosis

Sphingosine kinases (SphKs) and their product sphingosine-1-phosphate (S1P) have been reported to regulate apoptosis and survival of liver cells. Cholestatic liver diseases are characterized by cytotoxic levels of bile salts inducing liver injury. It is unknown whether SphKs and/or S1P play a role in this pathogenic process. Here, we investigated the putative involvement of SphK1 and S1P in bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to glycochenodeoxycholic acid (GCDCA) to induce apoptosis. GCDCA-exposed hepatocytes were co-treated with S1P, the SphK1 inhibitor Ski-II and/or specific antagonists of S1P receptors (S1PR1 and S1PR2). Apoptosis and necrosis were quantified. Ski-II significantly reduced GCDCA-induced apoptosis in hepatocytes (-70%, P<0.05) without inducing necrosis. GCDCA increased the S1P levels in hepatocytes (P<0.05). GCDCA induced [Ca(2+)] oscillations in hepatocytes and co-treatment with the [Ca(2+)] chelator BAPTA repressed GCDCA-induced apoptosis. Ski-II inhibited the GCDCA-induced intracellular [Ca(2+)] oscillations. Transcripts of all five S1P receptors were detected in hepatocytes, of which S1PR1 and S1PR2 appear most dominant. Inhibition of S1PR1, but not S1PR2, reduced GCDCA-induced apoptosis by 20%. Exogenous S1P also significantly reduced GCDCA-induced apoptosis (-50%, P<0.05), however, in contrast to the GCDCA-induced (intracellular) SphK1 pathway, this was dependent on S1PR2 and not S1PR1. Our results indicate that SphK1 plays a pivotal role in mediating bile salt-induced apoptosis in hepatocytes in part by interfering with intracellular [Ca(2+)] signaling and activation of S1PR1.

Nucling, a novel protein associated with NF-κB, regulates endotoxin-induced apoptosis in vivo

Nucling is a proapoptotic protein that regulates the apoptosome and nuclear factor-kappa B (NF-κB) signalling pathways. Strong stimuli, such as Gram-negative bacterial lipopolysaccharide (LPS), induce the simultaneous secretion of cytokines following the activation of NF-κB. Proinflammatory cytokines can induce liver damage through several mechanisms such as increases in oxidative stress and apoptotic reactions leading to tissue necrosis. Herein, we show that Nucling-knockout (KO) mice are resistant to LPS that consistently caused mortality in wild-type (WT) counterparts. Although serum levels of cytokines such as tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 did not differ significantly between WT and Nucling-KO mice after the LPS challenge, hepatocytes of Nucling-KO mice were refractory to LPS- or TNF-α-induced cell death. These results were consistent with the decreased expression of proapoptotic proteins including apoptosis-inducing factor and cleaved form of poly (ADP-ribose) polymerase and terminal deoxynucleotidyl transferase dUTP nick end-labelling positive cells in the liver of Nucling-KO mice after the administration of a lethal dose of LPS. Moreover, the upregulation of NF-κB-regulated anti-apoptotic molecules including cellular inhibitor of apoptosis (cIAP) 1 and cIAP2 was observed in the liver of Nucling-KO mice after LPS treatment. These findings indicate that the Nucling deficiency leads to resistance to apoptosis in liver. We propose that Nucling is important for the induction of apoptosis in cells damaged by cytotoxic stressors through the NF-κB signalling pathway.

Pertussis toxin, an inhibitor of G(αi) PCR, inhibits bile acid- and cytokine-induced apoptosis in primary rat hepatocytes

Excessive hepatocyte apoptosis is a common event in acute and chronic liver diseases leading to loss of functional liver tissue. Approaches to prevent apoptosis have therefore high potential for the treatment of liver disease. G-protein coupled receptors (GPCR) play crucial roles in cell fate (proliferation, cell death) and act through heterotrimeric G-proteins. G_αiPCRs have been shown to regulate lipoapoptosis in hepatocytes, but their role in inflammation- or bile acid-induced apoptosis is unknown. Here, we analyzed the effect of inhibiting G_αiPCR function, using pertussis toxin (PT), on bile acid- and cytokine-induced apoptosis in hepatocytes. Primary rat hepatocytes, HepG2-rNtcp cells (human hepatocellular carcinoma cells) or H-4-II-E cells (rat hepatoma cells) were exposed to glycochenodeoxycholic acid (GCDCA) or tumor necrosis factor-α (TNFα)/actinomycin D (ActD). PT (50–200 nmol/L) was added 30 minutes prior to the apoptotic stimulus. Apoptosis (caspase-3 activity, acridine orange staining) and necrosis (sytox green staining) were assessed. PT significantly reduced GCDCA- and TNFα/ActD-induced apoptosis in rat hepatocytes (−60%, p<0.05) in a dose-dependent manner (with no shift to necrosis), but not in HepG2-rNtcp cells or rat H-4-II-E cells. The protective effect of pertussis toxin was independent of the activation of selected cell survival signal transduction pathways, including ERK, p38 MAPK, PI3K and PKC pathways, as specific protein kinase inhibitors did not reverse the protective effects of pertussis toxin in GCDCA-exposed hepatocytes. Conclusion: Pertussis toxin, an inhibitor of G_αiPCRs, protects hepatocytes, but not hepatocellular carcinoma cells, against bile acid- and cytokine-induced apoptosis and has therapeutic potential as primary hepatoprotective drug, as well as adjuvant in anti-cancer therapy.

Hepatoprotective effects of S-adenosylmethionine and silybin on canine hepatocytes in vitro

Inflammation and oxidative stress are associated with liver injury and development of liver disease. The transcription factors nuclear factor-kappa beta (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) play critical roles in modulating liver injury and damage. Activation of NF-κB induces production of pro-inflammatory molecules including prostaglandin E2 (PGE2 ), interleukin-8 (IL-8) and macrophage chemotactic protein-1 (MCP-1). Nrf2 regulates genes controlling antioxidants. Our laboratory previously showed that hepatocytes, the primary functional cell type comprising liver tissue, respond to the cytokine interleukin-1 beta (IL-1β) by increased production of PGE2 , IL-8 and MCP-1. This increase is associated with nuclear translocation of NF-κB. In this study, we evaluated whether primary canine hepatocytes pre-treated with the combination of S-adenosylmethionine (SAMe; 30 and 2000 ng/ml) and silybin (SB; 298 ng/ml), agents with known anti-inflammatory and antioxidant properties, could attenuate IL-1β-induced inflammation and oxidative stress. The SAMe and SB combination reduced cytokine-induced PGE2 , IL-8 and MCP-1 production while also inhibiting NF-κB nuclear translocation. These changes were accompanied by increased antioxidant enzyme-reduced glutathione (GSH) comparable to control levels. The study shows for the first time that the SAMe and SB combination inhibits both inflammation and oxidative stress through two separate signalling pathways.

Silybin inhibits interleukin-1β-induced production of pro-inflammatory mediators in canine hepatocyte cultures

Hepatocytes are highly susceptible to cytokine stimulation and are fundamental to liver function. We established primary canine hepatocyte cultures to study effects of anti-inflammatory agents with hepatoprotective properties. Hepatocyte cultures were incubated with control media alone, silybin (SB), or the more bioavailable silybin-phosphatidylcholine complex (SPC), followed by activation with interleukin-1 beta (IL-1β; 10 ng/mL). Inflammatory response was measured by prostaglandin E2 (PGE(2) ), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) production and also nuclear factor-kappa B (NF-κB) translocation. Hepatocyte cultures continued production of the phenotypic marker albumin for more than 7 days in culture. IL-1β exposure increased PGE(2) , IL-8, and MCP-1 production, which was paralleled by NF-κB translocation from the cytoplasm to the nucleus. Pretreatment with SB and SPC significantly inhibited IL-1β-induced production of pro-inflammatory markers and attenuated NF-κB nuclear translocation. We demonstrate for the first time that primary canine hepatocyte cultures can be maintained in culture without phenotypic loss. The observation that hepatocyte cultures respond to pro-inflammatory IL-1β activation indicates hepatocytes as primary cellular targets of extrinsic IL-1β. The ability of SB and SPC to inhibit hepatocyte culture activation by IL-1β reinforces the notion of their hepatoprotective effects. Our primary canine hepatocyte culture model facilitates identification of hepatoprotective agents and their mechanism of action.

Amphiregulin induces the alternative splicing of p73 into its oncogenic isoform DeltaEx2p73 in human hepatocellular tumors

BACKGROUND & AIMS

Inactivation of the product of the tumor suppressor gene TP73 does not usually occur by mutation but rather through expression of truncated isoforms that have dominant-negative effects on p73 and p53. The truncated oncogenic isoform DeltaEx2p73 is expressed in hepatocellular carcinomas (HCC) and is produced through the alternative splicing of p73 pre-messenger RNA (pre-mRNA); however, the underlying mechanisms regulating this process are unknown.

METHODS

We used human normal and diseased liver tissue samples, as well as human HCC cell lines, to examine the association between activation of epidermal growth factor receptor (EGFR) by its ligand amphiregulin (AR) and the alternative splicing of p73 pre-mRNA into the tumorigenic isoform DeltaEx2p73, via c-Jun N-terminal-kinase-1-mediated signaling.

RESULTS

DeltaEx2p73 was expressed in a subset of premalignant cirrhotic livers and in otherwise healthy livers that harbored a primary tumor, as well as in HCC tissues. DeltaEx2p73 expression was correlated with that of the EGFR ligand AR, which was previously shown to have a role in hepatocarcinogenesis. Autocrine activation of the EGFR by AR triggered c-Jun N-terminal kinase-1 activity and inhibited the expression of the splicing regulator Slu7, leading to the accumulation of DeltaEx2p73 transcripts in HCC cells.

CONCLUSIONS

This study provided a mechanism for the generation of protumorigenic DeltaEx2p73 during liver tumorigenesis, via activation of EGFR signaling by AR and c-Jun N-terminal kinase-1 activity, leading to inhibition of the splicing regulator Slu7.

Evaluation of a 99mTc-labeled AnnexinA5 variant for non-invasive SPECT imaging of cell death in liver, spleen and prostate

PURPOSE

We investigate radio-labeling and pharmacokinetics of a new AnnexinA5 variant (HYNIC-cys-AnxA5) and then assess its utility for the non-invasive detection of cell death in liver, spleen and prostate.

METHODS

AnnexinA5 binds to phosphatidylserine expressed on the surface of apoptotic and necrotic cells. Contrary to other AnnexinA5 variants, the new cys-AnxA5 allows for site-specific conjugation of a hydrazinonicotinamide-maleimide moiety and subsequent radio-labeling with (99m)Tc at a position not involved in the AnxA5-phosphatidylserine interaction. Distribution of (99m)Tc-HYNIC-cys-AnxA5 was studied in rats, both invasively and via SPECT/CT. Cycloheximide was used to induce cell death in liver and spleen, whereas apoptosis in the prostate was induced by castration.

RESULTS

HYNIC-cys-AnxA5 was efficiently and reproducibly labeled with (99m)Tc. Blood clearance of radioactivity after iv-injection was adequately described by a two-compartment model, the renal cortex representing the main site of accumulation. Cycloheximide treatment resulted in increased accumulation of intravenous-injected (99m)Tc-HYNIC-cys-AnxA5 in liver and spleen over controls, which correlated well with TUNEL staining for cell death in corresponding tissue sections. However, the increase in TUNEL-positive prostate epithelial cells observed following castration was not paralleled by greater (99m)Tc-HYNIC-cys-AnxA5 accumulation.

CONCLUSION

(99m)Tc-HYNIC-cys-AnxA5 appears a suitable tracer for assessment of cell death in liver and spleen, but not prostate.

Copper activation of NF-kappaB signaling in HepG2 cells

Copper is a persistent environmental contaminant, and exposure to elevated levels of this transition metal can result in a variety of pathologies. Copper affects the transcription of multiple defense and repair genes to protect against metal-induced pathologies. HepG2 cells were treated with copper under multiple conditions and microarray analyses were previously performed to better understand the mechanisms by which copper affects the transcription of stress-responsive genes. Analysis of the microarray data indicated that copper modulates multiple signal transduction pathways, including those mediated by NF-kappaB. Luciferase assays, quantitative reverse transcription real-time PCR, and chemical inhibition in HepG2 cells validated the microarray results and confirmed that NF-kappaB was activated by stress-inducible concentrations of copper. In addition, two novel NF-kappaB-regulated genes, SRXN1 (sulfiredoxin 1 homolog) and ZFAND2A (zinc-finger, AN1-type domain 2A), were identified. Our results indicate that the activation of NF-kappaB may be important for survival under elevated concentrations of copper.

Components of the mitogen-activated protein kinase cascade are activated in hepatic cells by Echinococcus multilocularis metacestode

AIM: To explore the effect of Echinococcus multilocularis (E. multilocularis) on the activation of mitogen-activated protein kinase (MAPK) signaling pathways and on liver cell proliferation.

METHODS: Changes in the phosphorylation of MAPKs and proliferating cell nuclear antigen (PCNA) expression were measured in the liver of patients with alveolar echinococcosis (AE). MAPKs, MEK1/2 [MAPK/extracellular signal-regulated protein kinase (ERK) kinase] and ribosomal S6 kinase (RSK) phosphorylation were detected in primary cultures of rat hepatocytes in contact in vitro with (1) E. multilocularis vesicle fluid (EmF), (2) E. multilocularis-conditioned medium (EmCM).

RESULTS: In the liver of AE patients, ERK 1/2 and p38 MAPK were activated and PCNA expression was increased, especially in the vicinity of the metacestode. Upon exposure to EmF, p38, c-Jun N-terminal kinase (JNK) and ERK1/2 were also activated in hepatocytes in vitro, as well as MEK1/2 and RSK, in the absence of any toxic effect. Upon exposure to EmCM, only JNK was up-regulated.

CONCLUSION: Previous studies have demonstrated an influence of the host on the MAPK cascade in E. multilocularis. Our data suggest that the reverse, i.e. parasite-derived signals efficiently acting on MAPK signaling pathways in host liver cells, is actually operating.

Multidrug resistance-associated proteins are crucial for the viability of activated rat hepatic stellate cells

Hepatic stellate cells (HSCs) survive and proliferate in the chronically injured liver. ATP-binding cassette (ABC) transporters play a crucial role in cell viability by transporting toxic metabolites or xenobiotics out of the cell. ABC transporter expression in HSCs and its relevance to cell viability and/or activation have not been reported so far. The aim of this study was to investigate the expression, regulation, and function of multidrug resistance-associated protein (Mrp)-type and multidrug resistance protein (Mdr)-type ABC transporters in activated rat HSCs. Rat HSCs were exposed to cytokines or oxidative stress. ABC transporter expression was determined by quantitative polymerase chain reaction and immunohistochemistry. HSCs were exposed to the Mdr inhibitors verapamil and PSC-833 and the Mrp inhibitor MK571. Mdr and Mrp transporter function was evaluated with flow cytometry. Apoptosis was determined by activated caspase-3 and acridine orange staining, and necrosis was determined by Sytox green nuclear staining. An in vivo model of carbon tetrachloride (CCl(4))-induced liver fibrosis was used. With respect to hepatocytes, activated HSCs expressed high levels of Mrp1 and comparable levels of Mrp3, Mrp4, Mdr1a, and Mdr1b but not the hepatocyte-specific transporters bile salt export pump, Mrp2, and Mrp6. Mrp1 protein staining correlated with desmin staining in livers from CCl(4)-treated rats. Mrp1 expression increased upon activation of HSCs. Cytokines induced Mdr1b expression only. Oxidative stress was not a major regulator of Mdr and Mrp transporter expression. Activated HSCs became necrotic when exposed to the Mrp inhibitors.

CONCLUSION

Activated HSCs contain relatively high levels of Mrp1. Mrp-type transporters are required for the viability of activated HSCs. Mrp-dependent export of endogenous metabolites is important for the survival of activated HSCs in chronic liver diseases.

Arecoline-induced growth arrest and p21WAF1 expression are dependent on p53 in rat hepatocytes

Betel-quid use is associated with the risk of liver cirrhosis and hepatocellular carcinoma and arecoline, the major alkaloid of betel-quid, is hepatotoxic in mice. Therefore, we studied the cytotoxic and genotoxic effects of arecoline in normal rat hepatocytes (Clone-9 cells). Arecoline dose-dependently (0.1-1mM) decreased cell cycle-dependent proliferation while inducing DNA damage at 24h. Moreover, arecoline (1mM)-induced apoptosis and necrosis at 24h. Arecoline dose-dependently (0.1-0.5mM) increased transforming growth factor-beta (TGF-beta) mRNA, gene transcription and bioactivity and neutralizing TGF-beta antibody attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. Arecoline (0.5mM) also increased p21(WAF1) protein expression and p21(WAF1) gene transcription. Moreover, arecoline (0.5mM) time-dependently (8-24h) increased p53 serine 15 phosphorylation. Pifithrin-alpha (p53 inhibitor) and the loss of the two p53-binding elements in the p21(WAF1) gene promoter attenuated arecoline-induced p21(WAF1) gene transcription at 24h. Pifithrin-alpha also attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. We concluded that arecoline induces cytotoxicity, DNA damage, G(0)/G(1) cell cycle arrest, TGF-beta1, p21(WAF1) and activates p53 in Clone-9 cells. Moreover, arecoline-induced p21(WAF1) is dependent on p53 while arecoline-inhibited growth is dependent on both TGF-beta and p53.

INTESTINAL ISCHEMIA-REPERFUSION-INDUCED ACUTE LUNG INJURY AND ONCOTIC CELL DEATH IN MULTIPLE ORGANS

Most acute respiratory distress syndrome studies have been focused on the lung injury. Little is known about other organs during the development of acute respiratory distress syndrome. Herein, we investigated the injury and cell death in multiple organs after intestinal ischemia-reperfusion (IIR) in C57BL/6 mice. Terminal transferase dUTP nick end labeling staining was used as a marker of cell death. Caspase 3 and cathepsin B activation as markers of caspase-dependent and caspase-independent apoptosis, respectively, and electron microscopy for ultimate characterization of cell death were used. In comparison with control and sham-operated mice, the IIR group showed interstitial inflammatory infiltrates in the lung and significant increases of lung injury parameters and plasma lactate dehydrogenase and aspartate aminotransferase levels. Terminal transferase dUTP nick end labeling-positive cells and immunostaining for hemeoxygenase 1, an enzyme induced by inflammatory stimuli, were increased in the lung, heart, and kidney, but not in the liver. The number of hemeoxygenase 1-positive cells positively and significantly correlated to the number of terminal transferase dUTP nick end labeling-positive cells. Cell death was not associated with caspase 3 or cathepsin B activation. Electron microscopy showed morphological features compatible with oncotic rather than apoptotic cell death or necrosis, including mitochondrial swelling and cytoplasm disorganization in pulmonary and renal epithelial cells, lung and cardiac endothelial cells, and myocytes. These results indicate that, although lung injury is the most significant manifestation after IIR, oncotic cell death occurs in the lung, heart, and kidney, which may be related to ischemia and inflammation.

Amphiregulin: A new growth factor in hepatocarcinogenesis

Amphiregulin (AR) is a member of the epidermal growth factor family and a ligand of the epidermal growth factor receptor (EGFR). As other ligands of the EGFR, AR is synthesized as a precursor that is shed from the plasma membrane by metalloproteases. Hyperactive autocrine loops involving AR production have been described in a variety of tumors, and this growth factor is thought to play a non-redundant role in cancer development. AR expression is not detected in the normal liver, however it is readily induced during acute liver injury and behaves as a potent pro-regenerative and survival factor. Increased AR expression is also detected in human chronic liver injury (liver cirrhosis), which is considered a pre-neoplastic condition. Recent evidences suggest that AR can play a unique role in liver tumorigenesis and in the maintenance of the neoplastic phenotype of hepatocarcinoma cells. In this review, we summarize some aspects of AR patho-biology and the rationale behind its definition as a novel target in hepatocarcinoma therapy.

From alcohol toxicity to treatment

This article presents the proceedings of a symposium held at the meeting of the International Society for Biomedical Research on Alcoholism in Mannheim, Germany, in October 2004. This symposium was dedicated to Charles S. Lieber in recognition of his contribution in alcohol research over the last 50 years. It was divided into two parts, namely effects of alcohol on the gastrointestinal tract and effects of alcohol on the liver. Major emphasis was given to recent discoveries elucidating mechanisms of alcohol-associated carcinogenesis. M. Salaspuro (Finland) discussed the role of acetaldehyde in the saliva and in the large intestine with respect to its role in the pathogenesis of alcohol-associated cancer, and H. K. Seitz (Germany) presented new data identifying individuals homozygous for the ADH1C&1 allele as high on risk for alcohol-associated upper aerodigestive tract cancer. M. Savolainen (Finland) discussed the role phosphatidylethanol as a bioactive lipid that can mediate beneficial and harmful effects of alcohol drinking. In the second part of the symposium, alcoholic liver disease was discussed. P. Haber (Australia) presented new data on hepatic transcriptome in alcoholic liver disease with the identification of new genes possibly involved in alcohol-initiated fibrogenesis of the liver, and H. Moshage (The Netherlands) described survival mechanisms of the cholestatic hepatocytes with implications for therapy in cholestatic liver disease. The role of the hepatic microsomal ethanol oxidizing system in the metabolism of alcohol in alcoholic liver disease was summarized by R. Teschke (Germany). H. Ishii (Japan) discussed the current status and treatment of alcoholic hepatitis in Japan. Finally, in a state-of-the-art lecture, Charles S. Lieber (USA) discussed the development of the understanding of the pathophysiology of alcoholic liver disease in the last 50 years. He emphasized the role of pathophysiology as an important prerequisite for better treatment strategies.

The use of flow cytometric methods in acute and long-term in vitro testing

One principal demand for in vitro screening for toxic effects is the ease of performance and the high throughput of test methods. Flow cytometry offers the possibility to study several parameters simultaneously, e.g. cell cycle modulation, mode of cell death, activity of mitochondria. Aim of the present study was to assess the suitability of flow cytometry for the determination of cytotoxicity of test chemicals. Six chemicals chosen from the MEIC list (acetaminophen, isoniazid, paraquat, malathion, digoxin and 2,4-dichlorophenoxy acetic acid) were tested in HepG2, AAH-1, YAC-1 cells and human lymphocytes. Chemicals were applied for 24, 48 h or 28 days. The phases of the cell cycle were determined and the induction of apoptosis and necrosis was demonstrated by annexin binding, analysis of mitochondrial membrane potential and DNA strand breaks. The results of the present study show that flow cytometric methods are well suited to screen for the cytotoxicity of chemicals, both in adherent cells and cells grown in suspension.

Insulin prevents liver damage and preserves liver function in lipopolysaccharide-induced endotoxemic rats

BACKGROUND/AIMS

Liver integrity and function are crucial for survival of patients suffering from trauma, operations or infections. Insulin decreased mortality and prevented the incidence of multi organ failure and infection in critically ill patients. The aim of the present study was to determine whether insulin exerts positive effects on hepatic homeostasis and function during endotoxemia.

METHODS

Endotoxemic rats received either saline or insulin. Hepatic morphology and function was determined by measuring the effect of insulin on liver proteins, enzymes, hepatocyte apoptosis and proliferation including caspases-3 and -9 and Bcl-2. Intrahepatic ATP, glucose and lactate concentration were determined by bioluminescence. To determine possible molecular changes the effect of insulin on hepatic cytokine mRNA and gene profile analysis were assessed.

RESULTS

Insulin significantly improved hepatic protein synthesis by increasing albumin and decreasing c-reactive protein, P<0.05. Insulin attenuated hepatic damage by decreasing AST and ALT, P<0.05. Improved liver morphology was due to decreased hepatocyte apoptosis along with decreased caspase-3 concentration and increased hepatocyte proliferation along with Bcl-2 concentration, P<0.05. Insulin decreased hepatic IL-1beta, IL-6 and MIF mRNA and improved hepatic glucose metabolism and glycolysis, P<0.05. GeneChip analysis revealed an anti-inflammatory effect of insulin.

CONCLUSIONS

Insulin improves hepatic integrity, hepatic glucose metabolism and hepatic function by increasing cell survival and attenuating the hepatic inflammatory response in endotoxemic rats.