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51 Publications visible to you, out of a total of 51

Abstract (Expand)

MicroRNA (miRNA)-mediated gene regulation contributes to liver pathophysiology, including hepatic stellate cell (HSC) activation and fibrosis progression. Here, we investigated the role of miR-942 in human liver fibrosis. The expression of miR-942, HSC activation markers, transforming growth factor-beta pseudoreceptor BMP and activin membrane-bound inhibitor (BAMBI), as well as collagen deposition, were investigated in 100 liver specimens from patients with varying degree of hepatitis B virus (HBV)-related fibrosis. Human primary HSCs and the immortalized cell line (LX2 cells) were used for functional studies. We found that miR-942 expression was upregulated in activated HSCs and correlated inversely with BAMBI expression in liver fibrosis progression. Transforming growth factor beta (TGF-beta) and lipopolyssacharide (LPS), two major drivers of liver fibrosis and inflammation, induce miR-942 expression in HSCs via Smad2/3 respective NF-kappaB/p50 binding to the miR-942 promoter. Mechanistically, the induced miR-942 degrades BAMBI mRNA in HSCs, thereby sensitizing the cells for fibrogenic TGF-beta signaling and also partly mediates LPS-induced proinflammatory HSC fate. In conclusion, the TGF-beta and LPS-induced miR-942 mediates HSC activation through downregulation of BAMBI in human liver fibrosis. Our study provides new insights on the molecular mechanism of HSC activation and fibrosis.

Authors: L. Tao, D. Xue, D. Shen, W. Ma, J. Zhang, X. Wang, W. Zhang, L. Wu, K. Pan, Y. Yang, Z. C. Nwosu, S. Dooley, E. Seki, C. Liu

Date Published: 12th Aug 2018

Publication Type: Not specified

Abstract (Expand)

Upon liver intoxication with malnutrition or high-fat diet feeding, fibrinogen is synthesized by hepatocytes and secreted into the blood in human and mouse. Its primary function is to occlude blood vessels upon damage and thereby stop excessive bleeding. High fibrinogen levels may contribute to the development of pathological thrombosis, which is one mechanism linking fatty liver disease with cardiovascular disease. Our previous results present ERRgamma as key regulator of hepatocytic fibrinogen gene expression in human. In a therapeutic approach, we now tested ERRgamma inverse agonist GSK5182 as regulator of fibrinogen levels in mouse hyperfibrinogenemia caused by diet-induced obesity and in mouse hepatocytes. ACEA, a CB1R agonist, up-regulated transcription of mouse fibrinogen via induction of ERRgamma, whereas knockdown of ERRgamma attenuated the effect of ACEA (10 microM) on fibrinogen expression in AML12 mouse hepatocytes. Deletion analyses of the mouse fibrinogen gamma (FGG) gene promoter and ChIP assays revealed binding sites for ERRgamma on the mouse FGG promoter. ACEA or adenovirus ERRgamma injection induced FGA, FGB and FGG mRNA and protein expression in mouse liver, while ERRgamma knockdown with Ad-shERRgamma attenuated ACEA-mediated induction of fibrinogen gene expression. Moreover, mice maintained on a high-fat diet (HFD) expressed higher levels of fibrinogen, whereas cannabinoid receptor type 1 (CB1R)-KO mice fed an HFD had nearly normal fibrinogen levels. Finally, GSK5182 (40 mg/kg) strongly inhibits the ACEA (10 mg/kg) or HFD-mediated induction of fibrinogen level in mice. Taken together, targeting ERRgamma with its inverse agonist GSK5182 represents a promising therapeutic strategy for ameliorating hyperfibrinogenemia.

Authors: Y. Zhang, D. K. Kim, Y. S. Jung, Y. H. Kim, Y. S. Lee, J. Kim, W. I. Jeong, I. K. Lee, S. J. Cho, S. Dooley, C. H. Lee, H. S. Choi

Date Published: 19th Jul 2018

Publication Type: Not specified

Abstract (Expand)

Drug-induced liver injury (DILI) has become a major problem for patients and for clinicians, academics and the pharmaceutical industry. To date, existing hepatotoxicity test systems are only poorly predictive and the underlying mechanisms are still unclear. One of the factors known to amplify hepatotoxicity is the tumor necrosis factor alpha (TNFalpha), especially due to its synergy with commonly used drugs such as diclofenac. However, the exact mechanism of how diclofenac in combination with TNFalpha induces liver injury remains elusive. Here, we combined time-resolved immunoblotting and live-cell imaging data of HepG2 cells and primary human hepatocytes (PHH) with dynamic pathway modeling using ordinary differential equations (ODEs) to describe the complex structure of TNFalpha-induced NFkappaB signal transduction and integrated the perturbations of the pathway caused by diclofenac. The resulting mathematical model was used to systematically identify parameters affected by diclofenac. These analyses showed that more than one regulatory module of TNFalpha-induced NFkappaB signal transduction is affected by diclofenac, suggesting that hepatotoxicity is the integrated consequence of multiple changes in hepatocytes and that multiple factors define toxicity thresholds. Applying our mathematical modeling approach to other DILI-causing compounds representing different putative DILI mechanism classes enabled us to quantify their impact on pathway activation, highlighting the potential of the dynamic pathway model as a quantitative tool for the analysis of DILI compounds.

Authors: A. Oppelt, D. Kaschek, S. Huppelschoten, R. Sison-Young, F. Zhang, M. Buck-Wiese, F. Herrmann, S. Malkusch, C. L. Kruger, M. Meub, B. Merkt, L. Zimmermann, A. Schofield, R. P. Jones, H. Malik, M. Schilling, M. Heilemann, B. van de Water, C. E. Goldring, B. K. Park, J. Timmer, U. Klingmuller

Date Published: 15th Jun 2018

Publication Type: Not specified

Abstract (Expand)

BACKGROUND/AIMS: Common genetic variations in vitamin D metabolism are associated with liver stiffness. Whether these genes are implicated in hepatic steatosis remains unclear. Here we aimed to analyse the association of common vitamin D pathway gene variants with liver steatosis. METHODS: Liver steatosis was assessed non-invasively in 241 patients with chronic liver conditions by controlled attenuation parameter (CAP). The following polymorphisms were genotyped using TaqMan assays: group-specific component (GC) rs7041, 7-dehydrocholesterol reductase (DHCR7) rs12785878, cytochrome P450 2R1 (CYP2R1) rs10741657, -vitamin D receptor (VDR) rs7974353. Chemiluminescence immunoassay determined serum 25-hydroxyvitamin D (25(OH) D) concentrations. RESULTS: Vitamin D deficiency (defined by 25(OH)D concentrations <20 ng/mL) occurred in 66% of patients. Median CAP was 296 (100-400) dB/m. Patients with advanced steatosis (CAP >/=280 dB/m) had significantly (p = 0.033) lower 25(OH)D levels as compared to patients with CAP <280 dB/m. Moreover, the rare allele [T] in GC rs7041 was significantly (p = 0.018) associated with higher 25(OH)D levels in patients with CAP <280 dB/m. However, GC, DHCR7, CYP2R1, and VDR polymorphisms were not related to liver steatosis and obesity traits. CONCLUSIONS: Higher CAP values are associated with low serum 25(OH)D concentrations but not with common vitamin D pathway gene variants.

Authors: M. Jamka, A. Arslanow, A. Bohner, M. Krawczyk, S. N. Weber, F. Grunhage, F. Lammert, C. S. Stokes

Date Published: 8th Mar 2018

Publication Type: Not specified

Abstract (Expand)

Non-alcoholic fatty liver disease (NAFLD) is frequent among obese individuals with metabolic syndrome. Variants PNPLA3 p.I148M, TM6SF2 p.E167K and MBOAT7 rs641738 are associated with higher liver fat contents. Here we analyzed 63 biopsied non-obese, non-diabetic patients with NAFLD (39 men, age: 20-72 years) recruited within the German NAFLD CSG program. The frequencies of the PNPLA3, TM6SF2 and MBOAT7 polymorphisms were compared with the remaining patients in the NAFLD CSG cohort and with a control population (n = 174). Serum CK18-M30 was measured by ELISA. In non-obese NAFLD patients, the frequency of the PNPLA3 p.I148M allele (74.6%), but not of the TM6SF2 or MBOAT7 polymorphisms, was significantly (P < 0.05) higher as compared to the other patients in the NAFLD CSG cohort (54.9%) or controls (40.2%). The presence of the minor PNPLA3 p.I148M risk allele increased the risk of developing NAFLD (OR = 3.29, P < 0.001) and was associated with higher steatosis, fibrosis, and serum CK18-M30 levels (all P < 0.05). According to the population attributable fraction (PAF), 49.8% of NAFLD cases could be eliminated if the PNPLA3 mutation was absent. The MBOAT7 polymorphism was more frequent (P = 0.019) in patients with severe hepatic steatosis. In conclusion, PNPLA3, and to a lesser extent, MBOAT7 variants are associated with NAFLD risk and modulate liver injury in non-obese patients without diabetes.

Authors: M. Krawczyk, H. Bantel, M. Rau, J. M. Schattenberg, F. Grunhage, A. Pathil, M. Demir, J. Kluwe, T. Boettler, S. N. Weber, A. Geier, F. Lammert

Date Published: 28th Feb 2018

Publication Type: Not specified

Abstract (Expand)

Upon stimulation of cells with transforming growth factor beta (TGF-beta), Smad proteins form trimeric complexes and activate a broad spectrum of target genes. It remains unresolved which of the possible Smad complexes are formed in cellular contexts and how these contribute to gene expression. By combining quantitative mass spectrometry with a computational selection strategy, we predict and provide experimental evidence for the three most relevant Smad complexes in the mouse hepatoma cell line Hepa1-6. Utilizing dynamic pathway modeling, we specify the contribution of each Smad complex to the expression of representative Smad target genes, and show that these contributions are conserved in human hepatoma cell lines and primary hepatocytes. We predict, based on gene expression data of patient samples, increased amounts of Smad2/3/4 proteins and Smad2 phosphorylation as hallmarks of hepatocellular carcinoma and experimentally verify this prediction. Our findings demonstrate that modeling approaches can disentangle the complexity of transcription factor complex formation and its impact on gene expression.

Authors: P. Lucarelli, M. Schilling, C. Kreutz, A. Vlasov, M. E. Boehm, N. Iwamoto, B. Steiert, S. Lattermann, M. Wasch, M. Stepath, M. S. Matter, M. Heikenwalder, K. Hoffmann, D. Deharde, G. Damm, D. Seehofer, M. Muciek, N. Gretz, W. D. Lehmann, J. Timmer, U. Klingmuller

Date Published: 19th Feb 2018

Publication Type: Not specified

Abstract (Expand)

Background/Aims: Common genetic variations in vitamin D metabolism are associated with liver stiffness. Whether these genes are implicated in hepatic steatosis remains unclear. Here we aimed to analyse the association of common vitamin D pathway gene variants with liver steatosis. Methods: Liver steatosis was assessed non-invasively in 241 patients with chronic liver conditions by controlled attenuation parameter (CAP). The following polymorphisms were genotyped using TaqMan assays: group-specific component ( GC ) rs7041, 7-dehydrocholesterol reductase ( DHCR7 ) rs12785878, cytochrome P450 2R1 ( CYP2R1 ) rs10741657, vitamin D receptor ( VDR ) rs7974353. Chemiluminescence immunoassay determined serum 25-hydroxyvitamin D (25(OH) D) concentrations. Results: Vitamin D deficiency (defined by 25(OH)D concentrations <20 ng/mL) occurred in 66% of patients. Median CAP was 296 (100–400) dB/m. Patients with advanced steatosis (CAP ≥ 280 dB/m) had significantly ( p = 0.033) lower 25(OH)D levels as compared to patients with CAP <280 dB/m. Moreover, the rare allele [T] in GC rs7041 was significantly ( p = 0.018) associated with higher 25(OH)D levels in patients with CAP <280 dB/m. However, GC , DHCR7, CYP2R1 , and VDR polymorphisms were not related to liver steatosis and obesity traits. Conclusions: Higher CAP values are associated with low serum 25(OH)D concentrations but not with common vitamin D pathway gene variants.

Authors: Malgorzata Jamka, Anita Arslanow, Annika Bohner, Marcin Krawczyk, Susanne N. Weber, Frank Grünhage, Frank Lammert, Caroline S Stokes

Date Published: 7th Feb 2018

Publication Type: Not specified

Abstract (Expand)

IL-6 is a central mediator of the immediate induction of hepatic acute phase proteins (APP) in the liver during infection and after injury, but increased IL-6 activity has been associated with multiple pathological conditions. In hepatocytes, IL-6 activates JAK1-STAT3 signaling that induces the negative feedback regulator SOCS3 and expression of APPs. While different inhibitors of IL-6-induced JAK1-STAT3-signaling have been developed, understanding their precise impact on signaling dynamics requires a systems biology approach. Here we present a mathematical model of IL-6-induced JAK1-STAT3 signaling that quantitatively links physiological IL-6 concentrations to the dynamics of IL-6-induced signal transduction and expression of target genes in hepatocytes. The mathematical model consists of coupled ordinary differential equations (ODE) and the model parameters were estimated by a maximum likelihood approach, whereas identifiability of the dynamic model parameters was ensured by the Profile Likelihood. Using model simulations coupled with experimental validation we could optimize the long-term impact of the JAK-inhibitor Ruxolitinib, a therapeutic compound that is quickly metabolized. Model-predicted doses and timing of treatments helps to improve the reduction of inflammatory APP gene expression in primary mouse hepatocytes close to levels observed during regenerative conditions. The concept of improved efficacy of the inhibitor through multiple treatments at optimized time intervals was confirmed in primary human hepatocytes. Thus, combining quantitative data generation with mathematical modeling suggests that repetitive treatment with Ruxolitinib is required to effectively target excessive inflammatory responses without exceeding doses recommended by the clinical guidelines.

Authors: S. Sobotta, A. Raue, X. Huang, J. Vanlier, A. Junger, S. Bohl, U. Albrecht, M. J. Hahnel, S. Wolf, N. S. Mueller, L. A. D'Alessandro, S. Mueller-Bohl, M. E. Boehm, P. Lucarelli, S. Bonefas, G. Damm, D. Seehofer, W. D. Lehmann, S. Rose-John, F. van der Hoeven, N. Gretz, F. J. Theis, C. Ehlting, J. G. Bode, J. Timmer, M. Schilling, U. Klingmuller

Date Published: 9th Oct 2017

Publication Type: Not specified

Abstract

Not specified

Authors: Zeribe Chike Nwosu, Dominik Andre Megger, Seddik Hammad, Barbara Sitek, Stephanie Roessler, Matthias Philip Ebert, Christoph Meyer, Steven Dooley

Date Published: 1st Sep 2017

Publication Type: Not specified

Abstract (Expand)

Carbon tetrachloride-induced liver injury is a thoroughly studied model for regeneration and fibrosis in rodents. Nevertheless, its pattern of liver fibrosis is frequently misinterpreted as portal type. To clarify this, we show that collagen type IV+ "streets" and alpha-SMA+ cells accumulate pericentrally and extend to neighbouring central areas of the liver lobule, forming a 'pseudolobule'. Blood vessels in the center of such pseudolobules are portal veins as indicated by the presence of bile duct cells (CK19+) and the absence of pericentral hepatocytes (glutamine synthetase+). It is critical to correctly describe this pattern of fibrosis, particulary for metabolic zonation studies.

Authors: S. Hammad, A. Braeuning, C. Meyer, F. E. Z. A. Mohamed, J. G. Hengstler, S. Dooley

Date Published: 22nd Aug 2017

Publication Type: Not specified

Abstract (Expand)

Familial cholangiopathies are rare but potentially severe diseases. Their spectrum ranges from fairly benign conditions as, for example, benign recurrent intrahepatic cholestasis to low-phospholipid associated cholelithiasis and progressive familial intrahepatic cholestasis (PFIC). Many cholangiopathies such as primary biliary cholangitis (PBC) or primary sclerosing cholangitis (PSC) affect first the bile ducts ("ascending pathophysiology") but others, such as PFIC, start upstream in hepatocytes and cause progressive damage "descending" down the biliary tree and leading to end-stage liver disease. In recent years our understanding of cholestatic diseases has improved, since we have been able to pinpoint numerous disease-causing mutations that cause familial cholangiopathies. Accordingly, six PFIC subtypes (PFIC type 1-6) have now been defined. Given the availability of genotyping resources, these findings can be introduced in the diagnostic work-up of patients with peculiar cholestasis. In addition, functional studies have defined the pathophysiological consequences of some of the detected variants. Furthermore, ABCB4 variants do not only cause PFIC type 3 but confer an increased risk for chronic liver disease in general. In the near future these findings will serve to develop new therapeutic strategies for patients with liver diseases. Here we present the latest data on the genetic background of familial cholangiopathies and discuss their application in clinical practice for the differential diagnosis of cholestasis of unknown aetiology. As look in the future we present "system genetics" as a novel experimental tool for the study of cholangiopathies and disease-modifying genes. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Authors: M. C. Reichert, R. A. Hall, M. Krawczyk, F. Lammert

Date Published: 2nd Aug 2017

Publication Type: Journal

Abstract (Expand)

Understanding the dynamics of human liver metabolism is fundamental for effective diagnosis and treatment of liver diseases in general and the metabolism of drugs in particular. This knowledge can be obtained with systems biology/medicine approaches that account for the complexity of hepatic responses and their systemic consequences in other organs. Computational modelling can reveal hidden principles of the system by classification of individual components, analysing their interactions and simulating the effects that are difficult to investigate experimentally. Herein we review the state-of-the-art computational models that describe liver dynamics from the metabolic, gene regulatory and signal transduction perspectives. We focus especially on large-scale liver models described either by genome scale metabolic networks (GSMN) or object-oriented approach. We also discuss the benefits and limitations of each modelling approach and their value for clinical applications in diagnosis, therapy and prevention of liver diseases as well as precision medicine in hepatology. This article is protected by copyright. All rights reserved.

Authors: T. Cvitanovic, M. C. Reichert, M. Moskon, M. Mraz, F. Lammert, D. Rozman

Date Published: 19th May 2017

Publication Type: Not specified

Abstract (Expand)

OBJECTIVE: Bone morphogenetic protein (BMP)-9, a member of the transforming growth factor-beta family of cytokines, is constitutively produced in the liver. Systemic levels act on many organs and tissues including bone and endothelium, but little is known about its hepatic functions in health and disease. DESIGN: Levels of BMP-9 and its receptors were analysed in primary liver cells. Direct effects of BMP-9 on hepatic stellate cells (HSCs) and hepatocytes were studied in vitro, and the role of BMP-9 was examined in acute and chronic liver injury models in mice. RESULTS: Quiescent and activated HSCs were identified as major BMP-9 producing liver cell type. BMP-9 stimulation of cultured hepatocytes inhibited proliferation, epithelial to mesenchymal transition and preserved expression of important metabolic enzymes such as cytochrome P450. Acute liver injury caused by partial hepatectomy or single injections of carbon tetrachloride (CCl4) or lipopolysaccharide (LPS) into mice resulted in transient downregulation of hepatic BMP-9 mRNA expression. Correspondingly, LPS stimulation led to downregulation of BMP-9 expression in cultured HSCs. Application of BMP-9 after partial hepatectomy significantly enhanced liver damage and disturbed the proliferative response. Chronic liver damage in BMP-9-deficient mice or in mice adenovirally overexpressing the selective BMP-9 antagonist activin-like kinase 1-Fc resulted in reduced deposition of collagen and subsequent fibrosis. CONCLUSIONS: Constitutive expression of low levels of BMP-9 stabilises hepatocyte function in the healthy liver. Upon HSC activation, endogenous BMP-9 levels increase in vitro and in vivo and high levels of BMP-9 cause enhanced damage upon acute or chronic injury.

Authors: K. Breitkopf-Heinlein, C. Meyer, C. Konig, H. Gaitantzi, A. Addante, M. Thomas, E. Wiercinska, C. Cai, Q. Li, F. Wan, C. Hellerbrand, N. A. Valous, M. Hahnel, C. Ehlting, J. G. Bode, S. Muller-Bohl, U. Klingmuller, J. Altenoder, I. Ilkavets, M. J. Goumans, L. J. Hawinkels, S. J. Lee, M. Wieland, C. Mogler, M. P. Ebert, B. Herrera, H. Augustin, A. Sanchez, S. Dooley, P. Ten Dijke

Date Published: 23rd Mar 2017

Publication Type: Not specified

Abstract (Expand)

Latest data suggest that placental growth factor (PLGF), growth differentiation factor-15 (GDF-15) and hepatic growth factor (HGF) are involved in hepatic fibrogenesis. Diagnostic performance of these markers for non-invasive liver fibrosis prediction was evaluated based on liver histology and stiffness. In total 834 patients were recruited. Receiver-operating-characteristics were used to define cut-offs for markers correlating to fibrosis stages. Odds-ratios were calculated for the presence/absence of fibrosis/cirrhosis and confirmed in the sub-group of patients phenotyped by elastography only. Logistic and uni- and multivariate regression analyses were used to test for association of markers with liver fibrosis stages and for independent prediction of liver histology and stiffness. Marker concentrations correlated significantly (P<0.001) with histology and stiffness. Cut-offs for liver fibrosis (>/=F2) were PLGF = 20.20 pg/ml, GDF15 = 1582.76 pg/ml and HGF = 2598.00 pg/ml. Logistic regression confirmed an increase of ORs from 3.6 over 33.0 to 108.4 with incremental (1-3) markers positive for increased liver stiffness (>/=12.8kPa; all P<0.05). Subgroup analysis revealed associations with advanced fibrosis for HCV (three markers positive: OR = 59.9, CI 23.4-153.4, P<0.001) and non-HCV patients (three markers positive: OR = 144, CI 59-3383, P<0.001). Overall, serum markers identified additional 50% of patients at risk for advanced fibrosis presenting with low elastography results. In conclusion, this novel combination of markers reflects the presence of significant liver fibrosis detected by elastography and histology and may also identify patients at risk presenting with low elastography values.

Authors: M. Krawczyk, S. Zimmermann, G. Hess, R. Holz, M. Dauer, J. Raedle, F. Lammert, F. Grunhage

Date Published: 17th Mar 2017

Publication Type: Not specified

Abstract (Expand)

BACKGROUND: The liver is the major site for alcohol metabolism in the body and therefore the primary target organ for ethanol (EtOH)-induced toxicity. In this study, we investigated the in vitro response of human liver cells to different EtOH concentrations in a perfused bioartificial liver device that mimics the complex architecture of the natural organ. METHODS: Primary human liver cells were cultured in the bioartificial liver device and treated for 24 hours with medium containing 150 mM (low), 300 mM (medium), or 600 mM (high) EtOH, while a control culture was kept untreated. Gene expression patterns for each EtOH concentration were monitored using Affymetrix Human Gene 1.0 ST Gene chips. Scaled expression profiles of differentially expressed genes (DEGs) were clustered using Fuzzy c-means algorithm. In addition, functional classification methods, KEGG pathway mapping and also a machine learning approach (Random Forest) were utilized. RESULTS: A number of 966 (150 mM EtOH), 1,334 (300 mM EtOH), or 4,132 (600 mM EtOH) genes were found to be differentially expressed. Dose-response relationships of the identified clusters of co-expressed genes showed a monotonic, threshold, or nonmonotonic (hormetic) behavior. Functional classification of DEGs revealed that low or medium EtOH concentrations operate adaptation processes, while alterations observed for the high EtOH concentration reflect the response to cellular damage. The genes displaying a hormetic response were functionally characterized by overrepresented "cellular ketone metabolism" and "carboxylic acid metabolism." Altered expression of the genes BAHD1 and H3F3B was identified as sufficient to classify the samples according to the applied EtOH doses. CONCLUSIONS: Different pathways of metabolic and epigenetic regulation are affected by EtOH exposition and partly undergo hormetic regulation in the bioartificial liver device. Gene expression changes observed at high EtOH concentrations reflect in some aspects the situation of alcoholic hepatitis in humans.

Authors: W. Schmidt-Heck, E. C. Wonne, T. Hiller, U. Menzel, D. Koczan, G. Damm, D. Seehofer, F. Knospel, N. Freyer, R. Guthke, S. Dooley, K. Zeilinger

Date Published: 23rd Feb 2017

Publication Type: Not specified

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