M Nagel

Ablation of c-FLIP in hepatocytes enhances death-receptor mediated apoptosis and toxic liver injury in vivo.

BACKGROUND & AIMS Apoptosis is crucially involved in acute and chronic liver injury, including viral, cholestatic, toxic, and metabolic liver disease. Additionally, dysregulation of apoptosis signaling pathways has been implicated in hepatocarcinogenesis. The most prominent members of the apoptosis-mediating tumor necrosis factor receptor superfamily are the TNF-R1 (CD120a) and the CD95 (Apo-1/Fas) receptor. Although extensively studied, the intracellular signaling events in hepatocytes are only incompletely understood. METHODS To examine the role of the caspase-8 homolog cellular FLICE-inhibitory protein (c-FLIP) in liver injury, we generated mice with hepatocyte specific deletion of c-FLIP. Three models of acute liver injury were employed: the agonistic anti-CD95 antibody Jo2, d-galactosamine and LPS (GalN/LPS), and concanavalin A. RESULTS Conditional ablation of c-FLIP in hepatocytes augmented liver injury and cell death in all three models of liver injury. CD95- and GalN/LPS-induced liver injury was ameliorated by a pancaspase inhibitor, while ConA-induced injury was unaffected by caspase inhibition. Augmented activation of the MAPK JNK was observed in parallel to liver injury in c-FLIP knockout mice in all injury models; however, inhibition of JNK only affected TNF- and ConA-mediated injury. CONCLUSIONS In summary, c-FLIP is a central regulator of cell death in hepatocytes, involving increased activation of caspases and the MAPK JNK.

Increased hepatic fibrosis and JNK2-dependent liver injury in mice exhibiting hepatocyte-specific deletion of cFLIP

Chronic liver disease promotes hepatocellular injury involving apoptosis and triggers compensatory regeneration that leads to the activation of quiescent stellate cells in the liver. The deposition of extracellular matrix from activated myofibroblasts promotes hepatic fibrosis and the progression to cirrhosis with deleterious effects on liver physiology. The role of apoptosis signaling pathways in the development of fibrosis remains undefined. The aim of the current study was to determine the involvement of the caspase-8 homologue cellular FLICE-inhibitory protein (cFLIP) during the initiation and progression of fibrosis. Liver injury and fibrosis from carbon tetrachloride (CCl(4)) and thioacetamide (TAA) were examined in mice exhibiting a hepatocyte-specific deletion of cFLIP (flip(-/-)). Acute liver injury from CCl(4) and TAA were enhanced in flip(-/-) mice. This was accompanied by increased activation of caspase-3 and -9, pronounced phosphorylation of JNK, and decreased phosphorylation of Erk. Deletion of the cJun NH(2)-terminal kinase 2 (JNK2) in flip(-/-) mice protected from injury. Hepatic fibrosis was increased at baseline in 12-wk-old flip(-/-) mice, and progression of fibrosis from TAA was accelerated compared with the wild type. In conclusion, deletion of cFLIP in hepatocytes leads to increased fibrosis and accelerated fibrosis progression. This is accompanied by increased injury involving the activation of caspases and JNK2. Thus predisposition to liver injury involving increased hepatocellular apoptosis is a critical mediator of accelerated fibrogenesis, and prevention of liver injury will be a most important measure for patients with chronic liver disease.

Diabetic liver injury from streptozotocin is regulated through the caspase-8 homolog cFLIP involving activation of JNK2 and intrahepatic immunocompetent cells

The endemic occurrence of obesity and the associated risk factors that constitute the metabolic syndrome have been predicted to lead to a dramatic increase in chronic liver disease. Non-alcoholic steatohepatitis (NASH) has become the most frequent liver disease in countries with a high prevalence of obesity. In addition, hepatic steatosis and insulin resistance have been implicated in disease progression of other liver diseases, including chronic viral hepatitis and hepatocellular carcinoma. The molecular mechanisms underlying the link between insulin signaling and hepatocellular injury are only partly understood. We have explored the role of the antiapoptotic caspase-8 homolog cellular FLICE-inhibitory protein (cFLIP) on liver cell survival in a diabetic model with hypoinsulinemic diabetes in order to delineate the role of insulin signaling on hepatocellular survival. cFLIP regulates cellular injury from apoptosis signaling pathways, and loss of cFLIP was previously shown to promote injury from activated TNF and CD95/Apo-1 receptors. In mice lacking cFLIP in hepatocytes (flip−/−), loss of insulin following streptozotocin treatment resulted in caspase- and c-Jun N-terminal kinase (JNK)-dependent liver injury after 21 days. Substitution of insulin, inhibition of JNK using the SP600125 compound in vivo or genetic deletion of the mitogen-activated protein kinase (MAPK)9 (JNK2) in all tissues abolished the injurious effect. Strikingly, the difference in injury between wild-type and cFLIP-deficient mice occurred only in vivo and was accompanied by liver-infiltrating inflammatory cells with a trend toward increased amounts of NK1.1-positive cells and secretion of proinflammatory cytokines. Transfer of bone marrow from rag-1-deficient mice that are depleted from B and T lymphocytes prevented liver injury in flip−/− mice. These findings support a direct role of insulin on cellular survival by alternating the activation of injurious MAPK, caspases and the recruitment of inflammatory cells to the liver. Thus, increasing resistance to insulin signaling pathways in hepatocytes appears to be an important factor in the initiation and progression of chronic liver disease.

Prospective evaluation of the impact of covert hepatic encephalopathy on quality of life and sleep in cirrhotic patients

Minimal hepatic encephalopathy (HE) and HE grade 1 (HE1) according to the West Haven criteria have recently been grouped as one entity named—covert HE‐ (CHE). Data regarding the impact of CHE on health‐related quality of life (HRQoL) and sleep quality are controversial.

Cytokeratin-18 fragments predict treatment response and overall survival in gastric cancer in a randomized controlled trial

Background: Gastric cancer is common malignancy and exhibits a poor prognosis. At the time of diagnosis, the majority of patients present with metastatic disease which precludes curative treatment. Non-invasive biomarkers which discriminate early from advanced stages or predict the response to treatment are urgently required. This study explored the cytokeratin-18 fragment M30 and full-length cytokeratin-18 M65 in predicting treatment response and survival in a randomized, placebo-controlled trial of advanced gastric cancer. Methods: Patients enrolled in the SUN-CASE study received sunitinib or placebo as an adjunct to standard therapy with leucovorin (Ca-folinate), 5-fluorouracil, and irinotecan in second or third line. Treatment response rates, progression-free survival and overall survival were assessed during a follow-up period of 12 months. Cytokeratin-18 fragments were analyzed in 52 patients at baseline and day 14 of therapy. Results: Levels of M30 correlated with the presence of metastasis and lymph node involvement and decreased significantly during chemotherapy. Importantly, baseline levels of M30 were significantly higher in patients who failed therapy. In addition, patients who did not respond to treatment were also identifiable at day 14 based on elevated M30 levels. By stepwise regression analysis, M30 at day 14 was identified as independent predictor of treatment response. Likewise, serum levels of full-length cytokeratin-18 M65 at baseline also correlated with treatment failure and progression-free survival. The addition of sunitinib did not exert any effects on serum levels of M30 or M65. Conclusion: The cytokeratin-18 fragment M30 at day 14 identifies patients that fail to second- or third-line therapy for advanced gastric cancer. Validation of this non-invasive biomarker in gastric cancer is warranted.

Validation of the simplified Animal Naming Test as primary screening tool for the diagnosis of covert hepatic encephalopathy

BACKGROUND Diagnosis of covert hepatic encephalopathy (CHE) is time consuming in clinical practice. Recently, a new diagnostic tool - the simplified Animal Naming Test (S-ANT1) - was presented with promising results in an Italian cohort. The aim of the present study was to validate S-ANT1 in a cohort of cirrhotic patients from a German tertiary referral centre. METHODS 143 cirrhotic patients and 37 healthy controls were enrolled. Hepatic encephalopathy (HE) grade 1 (HE1) was clinically diagnosed according to the West-Haven Criteria. Critical flicker frequency and Psychometric Hepatic Encephalopathy Score were used to detect minimal HE (MHE). All participants were additionally examined by S-ANT1. RESULTS 58 (40.6%) patients presented with CHE (40 MHE, 18 HE1). S-ANT1 was lowest in patients with HE1, followed by patients with MHE, patients without CHE, and healthy controls, respectively (each p < 0.05). Naming <20 animals discriminated best between patients with and without CHE in ROC analysis (with Youdens index). With a cut-off value of ≥23 mentioned animal names further testing for CHE could be avoided in 38.5% of patients with a negative predictive value of 84%. CONCLUSIONS S-ANT1 may become an important first screening tool for the assessment of CHE in clinical practice.

Loss of cellular FLICE-inhibitory protein promotes acute cholestatic liver injury and inflammation from bile duct ligation

Cholestatic liver injury results from impaired bile flow or metabolism and promotes hepatic inflammation and fibrogenesis. Toxic bile acids that accumulate in cholestasis induce apoptosis and contribute to early cholestatic liver injury, which is amplified by accompanying inflammation. The aim of the current study was to evaluate the role of the antiapoptotic caspase 8-homolog cellular FLICE-inhibitory (cFLIP) protein during acute cholestatic liver injury. Transgenic mice exhibiting hepatocyte-specific deletion of cFLIP (cFLIP-/-) were used for in vivo and in vitro analysis of cholestatic liver injury using bile duct ligation (BDL) and the addition of bile acids ex vivo. Loss of cFLIP in hepatocytes promoted acute cholestatic liver injury early after BDL, which was characterized by a rapid release of proinflammatory and chemotactic cytokines (TNF, IL-6, IL-1β, CCL2, CXCL1, and CXCL2), an increased presence of CD68+ macrophages and an influx of neutrophils in the liver, and resulting apoptotic and necrotic hepatocyte cell death. Mechanistically, liver injury in cFLIP-/- mice was aggravated by reactive oxygen species, and sustained activation of the JNK signaling pathway. In parallel, cytoprotective NF-κB p65, A20, and the MAPK p38 were inhibited. Increased injury in cFLIP-/- mice was accompanied by activation of hepatic stellate cells and profibrogenic regulators. The antagonistic caspase 8-homolog cFLIP is a critical regulator of acute, cholestatic liver injury. NEW & NOTEWORTHY The current paper explores the role of a classical modulator of hepatocellular apoptosis in early, cholestatic liver injury. These include activation of NF-κB and MAPK signaling, production of inflammatory cytokines, and recruitment of neutrophils in response to cholestasis. Because these signaling pathways are currently exploited in clinical trials for the treatment of nonalcoholic steatohepatitis and cirrhosis, the current data will help in the development of novel pharmacological options in these indications.

Predictors of advanced fibrosis in non-cirrhotic non-alcoholic fatty liver disease in Germany

Advanced fibrosis has been established as the most important predictor of overall mortality in patients with non‐alcoholic fatty liver disease (NAFLD). In contrast to cirrhosis, advanced, non‐cirrhotic NAFLD is difficult to identify and data from Germany are lacking.

Hepatische Manifestation eines Makrophagen-Aktivierungs-Syndroms (MAS)

Background Elevated liver values are the most common pathological laboratory result in Germany. Frequent findings, especially in younger patients, are nutritive- or medicamentous- toxic reasons, viral or autoimmune hepatitis. A macrophage activation syndrome (MAS) may manifest like a viral infectious disease with fever, hepatosplenomegaly and pancytopenia and is associated with a high mortality. It is based on an enhanced activation of macrophages with increased cytokine release, leading to organ damage and multi-organ failure. In addition to genetic causes, MAS is commonly associated with infections and rheumatic diseases. We report the case of a 26-year-old female patient suffering from MAS as a rare cause of elevated liver enzymes. Methods Patient characteristics, laboratory values, liver histology, bone marrow and radiological imaging were documented and analyzed. Case Report After an ordinary upper airway infection with bronchitis, a rheumatic arthritis appeared and was treated with leflunomide und methotrexate. In the further course of the disease, the patient developed an acute hepatitis with fever, pancytopenia and massive hyperferritinemia. Immunohistochemistry of the liver biopsy revealed hemophagocytosis and activation of CD68-positive macrophages. In the radiological and histological diagnostics of the liver and bone marrow, an MAS was diagnosed as underlying disease of the acute hepatitis. Under therapy with prednisolone, the fever disappeared and transaminases and ferritin rapidly normalized. Conclusion Aside from the frequent causes of elevated liver values in younger patients, such as nutritive toxic, drug induced liver injury, viral or autoimmune hepatitis, especially in case of massive hyperferritinemia, a MAS should be considered as a rare cause of acute liver disease.