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Background and Aim: The progression of non-alcoholic fatty liver disease (NAFLD) likely involves a ‘multiple hit’ mechanism. We hypothesized that partial hepatectomy, a procedure performed frequently in patients with NAFLD, would accelerate the progression of disease. Methods: C57BL/6JolaHsd mice were fed a choline-deficient L-amino acid-defined diet (CD-AA) or a choline-sufficient L-amino acid-defined control diet (CS-AA). Part of the mice in the CD-AA group received a diet enriched in vitamin E (~20 mg /day). Two weeks after the start of the diet, mice underwent a partial hepatectomy or a sham operation. Results: In the CD-AA group, NAFLD activity scores were significantly higher at 7 days after partial hepatectomy compared to the sham operated mice (3.7 ± 1.3 vs. 1.8 ± 0.7; P<0.05). In addition, TBARS, a measure for oxidative stress, in liver tissue of the CD-AA group were significantly higher at day 1, 3 and 7 after partial hepatectomy compared to the sham operated mice (P<0.05). Vitamin E therapy significantly reduced TBARS level at day 7 after partial hepatectomy compared to the CD-AA diet group (P< 0.05). Vitamin E suppletion reduced NAFLD activity score at day 7 after partial hepatectomy compared to the CD-AA group (2.3 ± 0.8 vs. 3.8 ± 1.0; P<0.05). Conclusion: Partial hepatectomy accelerates the progression of NAFLD. Disease progression induced by partial hepatectomy is substantially attenuated by vitamin E. [ABSTRACT FROM AUTHOR]

Background: A real-time objective evaluation for the extent of liver steatosis during liver transplantation is currently not available. Diffuse reflectance spectroscopy (DRS) rapidly and accurately assesses the extent of steatosis in human livers with mild steatosis. However, it is yet unknown whether DRS accurately quantifies moderate/severe steatosis and is able to distinguish between micro- and macrovesicular steatosis.Methods: C57BL/6JolaHsd mice were fed wit a choline-deficient L-amino acid-defined diet (CD-AA) or a choline-sufficient L-amino acid-defined control diet (CS-AA) for 3, 8, and 20 weeks. In addition B6.V-Lepob/OlaHsd (ob/ob) mice and their lean controls were studied. A total of 104 DRS measurements were performed in liver tissue ex vivo. The degree of steatosis was quantified from the DRS data and compared with histopathological analysis.Results: When assessed by histology, livers of mice fed with a CD-AA and CS-AA diet displayed macrovesicular steatosis (range 0-74 %), ob/ob mice revealed only microvesicular steatosis (range 75-80 %), and their lean controls showed no steatosis. The quantification of steatosis by DRS correlated well with pathology (correlation of 0.76 in CD-AA/CS-AA fed mice and a correlation of 0.75 in ob/ob mice). DRS spectra did not distinguish between micro- and macrovesicular steatosis. In samples from CD-AA/CS-AA fed mice, the DRS was able to distinguish between mild and moderate/severe steatosis with a sensitivity and specificity of 86 and 81 %, respectively.Conclusion: DRS can quantify steatosis with good agreement to histopathological analysis. DRS may be useful for real-time objective evaluation of liver steatosis during liver transplantation, especially to differentiate between mild and moderate/severe steatosis. [ABSTRACT FROM AUTHOR]

Abstract: 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 [Ca2+] oscillations in hepatocytes and co-treatment with the [Ca2+] chelator BAPTA repressed GCDCA-induced apoptosis. Ski-II inhibited the GCDCA-induced intracellular [Ca2+] 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 [Ca2+] signaling and activation of S1PR1. [Copyright &y& Elsevier]

Angiotensin II (AT-II) is a pro-fibrotic compound that acts via membrane-bound receptors (AT-1R/AT-2R) and thereby activates hepatic stellate cells (HSCs). AT-II receptor blockers (ARBs) are thus important candidates in the treatment of liver fibrosis. However, multiple case reports suggest that AT-1R blockers may induce hepatocyte injury. Therefore, we investigated the effect of AT-II and its receptor blockers on cytokine-, oxidative stress- and bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to TNF- α /Actinomycin D, the ROS-generating agent menadione or the bile salts: glycochenodeoxycholic acid (GCDCA) and tauro-lithocholic acid-3 sulfate (TLCS), to induce apoptosis. AT-II (100 nmol/L) was added 10 minutes prior to the cell death-inducing agent. AT-1R antagonists (Sartans) and the AT-2R antagonist PD123319 were used at 1 mmol/L. Apoptosis (caspase-3 activity, acridine orange staining) and necrosis (Sytox green staining) were quantified. Expression of CHOP (marker for ER stress) and AT-II receptor mRNAs were quantified by QPCR. AT-II dose-dependently reduced GCDCA-induced apoptosis of hepatocytes (250%, p<0.05) without inducing necrosis. In addition, AT-II reduced TLCS-induced apoptosis of hepatocytes (250%, p<0.05). However, AT-II did not suppress TNF/ Act-D and menadione-induced apoptosis. Only the AT-1R antagonists abolished the protective effect of AT-II against GCDCA-induced apoptosis. AT-II increased phosphorylation of ERK and a significant reversal of the protective effect of AT-II was observed when signaling kinases, including ERK, were inhibited. Moreover, AT-II prevented the GCDCA-induced expression of CHOP (the marker of the ER-mediated apoptosis). Conclusion: Angiotensin II protects hepatocytes from bile salt-induced apoptosis through a combined activation of PI3-kinase, MAPKs, PKC pathways and inhibition of bile saltinduced ER stress. Our results suggest a mechanism for the observed hepatocyte-toxicity of Sartans (angiotensin receptor blockers, ARBs) in some patients with chronic liver injury. [ABSTRACT FROM AUTHOR]

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 (GαiPCR) play crucial roles in cell fate (proliferation, cell death) and act through heterotrimeric G-proteins. GaiPCRs 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 GaiPCR function, using pertussis toxin (PT), on bile acid- and cytokineinduced apoptosis in hepatocytes. Primary rat hepatocytes, HepG2-rNtcp cells (human hepatocellular carcinoma cells) or H4-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 GaiPCRs, 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 anticancer therapy. [ABSTRACT FROM AUTHOR]

Background: The renin-angiotensin system has an important role in hepatic inflammation and fibrosis. Renin-angiotensin system blockade by angiotensin-converting enzyme (ACE) inhibitors provides some protective effects against hepatic fibrogenesis. Captopril as an ACE inhibitor can decrease inflammatory mediators and attenuate hepatic fibrosis in the livers of bile duct ligated (BDL) rats., Objective: The present study was conducted to investigate the effects of captopril on cytokine production in hepatic fibrosis induced by a bile duct ligation model in rats., Methods: Male rats were divided into four groups including; control, sham operated, BDL, and BDL plus captopril (10 mg/kg/day, orally). After 28 days of treatment, the livers were removed for cytokine analysis. Hepatic interleukin (IL)-10 and tumor necrosis factor (TNF)-α levels were measured., Results: Captopril treatment decreased the hepatic content of the proinflammatory cytokine TNF-α and increased the anti-inflammatory cytokine IL-10., Conclusion: the present study suggests that the protective effect of captopril on hepatic fibrosis is likely to be mediated by cytokine production.