In a nude mouse model of colorectal liver metastases, we have identified a paracrine tumor cell/host cell signalling pathway that is apparently required for successful tumor growth. Whereas recombinant platelet derived growth factor-C (PDGF-C) and supernatants from PDGF-C secreting wild type LS174T colon carcinoma cells could rescue tumor promoting hepatic stellate cells (HSC) from growth inhibition by serum starvation, supernatants from LS174T colon carcinoma cells with reduced secretion of PDGF-C had much less effect on serum starved HSC. Autocrine growth inhibition of LS174T cells by PDGF-C knock-down was only marginal. In vivo, a prominent inhibition of liver metastasis was observed if PDGF-C was knocked-down in LS174T cells. By whole genome array analysis of host cells of the invasion front and subsequent immunohistochemical staining we identified p21 activated kinase-2 (PAK-2) as being strongly and specifically expressed by HSC. The above described effect of PDGF-C on HSC was found to be dependent on PAK-2 because in contrast to wild type HSC, silencing of PAK-2 in HSC only allowed for a partial PDGF-C-mediated rescue from serum starvation leading to only a slight increase of proliferation. These data indicate that PDGF-C promotes tumor growth via a growth promoting effect on HSC that is at least in part dependent on the presence of functional PAK-2. PMID: 22362252
It has been shown that the majority of the cellular alterations and changes in gene expression in several fibrotic diseases is caused by the cytokine TGF-beta1. Furthermore, it was found that in some cases another member of the TGF-beta superfamily of cytokines, BMP-7, can antagonize the profibogenic effects of TGF-beta1. One feature of liver fibrosis is the transdifferentiation of hepatic stellate cells to a myofibroblast-like phenotype. These cells contribute to the development of the fibrosis by massive expression of proteins of the extra-cellular matrix. During this study, the myoblast cell line L6E9 served as a model for this process, as they also transdifferentiate to myofibroblast-like cells when treated with TGF-beta1. Furthermore, the transduction of TGF-beta1 signals is well known in this cell line and can be easier distinguished from BMP-7 signaling compared to hepatic stellate cells. It was shown that BMP-7 signals are detected via the BMP-type I-receptors Alk2 and Alk3 in L6E9. Intracellulary, the signals are mediated to the nucleus via Smad1 and Smad5, where they lead to the upregulation of the expression of Id1, Id2 and Id3 in a concentration-dependent manner. Additionally, the activation of the MAP-kinase pathway by BMP-7 and TGF-beta1 was validated with a probable selectivity for the MAP-kinase p38. The stimulation of L6E9 with BMP-7 leads to the inhibition of the expression of Ctgf, a fibrosis-associated TGF-beta1 target gene. This effect is not based on a direct inhibition of TGF-beta1 signal transduction or transcription of Ctgf, but is mediated by the upregulation of a BMP-7 target gene. The specific inhibition of the TGF-beta1/Smad3 pathway had no influence on the expression of Ctgf, whereas the inhibition of the MAP-kinases p38 and p44/42 led to a down-regulation of Ctgf expression. In conclusion the Ctgf expression is regulated by TGF-beta1 via the MAP-kinase pathway in L6E9, while the antagonistic effect of BMP-7 is mediated via an indirect mechanism which is based on the described Smad1/5 pathway.
During inflammation, the inflammasomes representing a group of multi-protein complexes trigger the biological maturation of pro-inflammatory cytokines such as interleukin-1β and interleukin-18 by proteolytic activation of caspase-1 from its inactive proforms. The individual genes encoding components of the inflammasome machinery are regulated at transcriptional and post-transcriptional levels. Once activated, they drive a wide variety of cellular responses that are necessary to mediate host defense against microbial pathogens and to guarantee tissue homeostasis. In the present work, we have studied the expression of the different inflammasomes in various primary hepatic cell subpopulations, in models of acute inflammation and during experimental liver fibrogenesis. We demonstrate that NLRP-1, NLRP-3 and AIM2 are prominently expressed in Kupffer cells and liver sinusoidal endothelial cells, moderately expressed in periportal myofibroblasts and hepatic stellate cells, and virtually absent in primary cultured hepatocytes. We found that the challenge with the lipopolysaccharides results in a time- and concentration-dependent expression of the NOD-like receptor family members NLRP-1, NLRP-3 and NLRC4/NALP4 in cultured hepatic stellate cells and a strong transcriptional activation of NLRP-3 in hepatocytes. Moreover, we detect a diverse regulatory network of the different inflammasomes in the chosen experimental models of acute and chronic liver insult suggesting that the various inflammasomes might contribute simultaneously to the outcome of inflammatory and fibrotic liver insult, irrespectively of the underlying inflammatory stimulus.
The data presented in this brief report support the research article “Altered mitochondrial and peroxisomal integrity in lipocalin-2-deficient mice with hepatic steatosis” [1, doi: 10.1016/j.bbadis.2017.04.006]. We tested whether the absence of Lipocalin-2 (LCN2) could dysregulate the phosphatidylinositol 3-kinase/protein kinase B (PI3K-PKB) pathway and hepatic homeostasis in Non-Alcoholic-Steatohepatitis (NASH). The article highlights the role of LCN2 in hepatic homeostasis.
BACKGROUND: The soluble interleukin-2 receptor (sIL-2R, sIL2R, sTAC, sCD25) is a reliable biomarker for disease activity in inflammatory disorders such as sarcoidosis. Based on the essential pathogenic role of inflammation for progression of liver diseases, we hypothesized that sIL-2R might be an indicator of inflammatory cell activation and disease severity in patients with chronic liver diseases (CLD). METHODS: We measured sIL-2R serum levels in 71 patients with different stages and etiologies of CLD in comparison to 41 healthy controls. Serum sIL-2R concentrations were correlated with laboratory markers of liver diseases, cytokine / chemokine levels and circulating immune cell subpopulations as simultaneously assessed by FACS analysis from peripheral leukocytes. RESULTS: CLD patients showed significantly elevated serum sIL-2R levels compared with controls. sIL-2R was significantly higher in patients with compared to patients without established liver cirrhosis and increased with the Child-Pugh stage of cirrhosis, independent of the underlying etiology. sIL-2R levels correlated inversely with parameters indicating the hepatic biosynthetic capacity, such as albumin or international normalized ratio, and positively with non-invasive markers of liver fibrosis such as hyaluronic acid or procollagen-III-peptide. Circulating immune cells might represent a major source of sIL-2R. In fact, sIL2-R levels correlated closely with circulating monocytes, especially non-classical CD14+ CD16+ monocytes, which were found to express high levels of CD25 by FACS. Pro-inflammatory cytokines, including IL-2, IFNγ or IL-6, and chemokines were also associated with sIL2-R. In addition, renal failure was an important confounder of sIL-2R levels independent of liver dysfunction and inflammation. CONCLUSIONS: sIL-2R is elevated in patients with liver diseases and cirrhosis, is associated with circulating inflammatory cells and is increased in concomitant renal failure. These data indicate that sIL-2R might be a potential marker for immune cell activation in CLD, especially for proinflammatory and profibrogenic non-classical CD14 + CD16+ monocytes.
Abstract Background and Aims CCN 3/ NOV , a matricellular protein of the CYR61‐CTGF‐NOV ( CCN ) family, comprises six secreted proteins that associate specifically with the extracellular matrix. CCN proteins lack specific high‐affinity receptors; instead, they regulate crucial biological processes, such as fibrosis, by signalling via integrins and proteoglycans. Recent studies have linked overexpression of CCN 3/ NOV to mitigate kidney fibrosis. This study aims to investigate CCN 3/ NOV overexpression in liver fibrogenesis in vivo . Methods The biological efficacy of adenoviral expressed CCN 3/ NOV directed under transcriptional control of the constitutively active Cytomegalovirus promoter (Ad‐ NOV ) was analysed in a bile duct ligation model and in cultured primary hepatocytes. Results and Conclusions Even though Ad‐ NOV gene transfer in a 3‐week bile duct ligation mouse model showed the expected high levels of CCN 3/ NOV in both mRNA and protein, it failed to reduce liver fibrogenesis, but instead enhanced hepatocyte apoptosis. Furthermore, overexpressed CCN 3/ NOV in cultured primary hepatocytes resulted in decreased levels of CCN 2/ CTGF , the profibrotic marker protein in liver fibrosis. Both Ad‐ NOV and Ad‐ CTGF induced reactive oxygen species production, enhanced p38 and JNK activation. Therefore, we conclude that CCN 3/ NOV overexpression in vivo is insufficient to mitigate liver fibrogenesis because of the induction of hepatocyte injury and apoptosis.
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Read moreAbstract Recent data suggest that the chemokine receptor CXCR3 is functionally involved in fibroproliferative disorders, including liver fibrosis. Neoangiogenesis is an important pathophysiological feature of liver scarring, but a functional role of angiostatic CXCR3 chemokines in this process is unclear. We therefore investigated neoangiogenesis in carbon tetrachloride (CCl4)-induced liver fibrosis in Cxcr3 −/− and wildtype mice by histological, molecular, and functional imaging methods. Furthermore, we assessed the direct role of vascular endothelial growth factor (VEGF) overexpression on liver angiogenesis and the fibroproliferative response using a Tet-inducible bitransgenic mouse model. The feasibility of attenuation of angiogenesis and associated liver fibrosis by therapeutic treatment with the angiostatic chemokine Cxcl9 was systematically analyzed in vitro and in vivo . The results demonstrate that fibrosis progression in Cxcr3 −/− mice was strongly linked to enhanced neoangiogenesis and VEGF/VEGFR2 expression compared with wildtype littermates. Systemic VEGF overexpression led to a fibrogenic response within the liver and was associated with a significantly increased Cxcl9 expression. In vitro , Cxcl9 displayed strong antiproliferative and antimigratory effects on VEGF-stimulated endothelial cells and stellate cells by way of reduced VEGFR2 (KDR), phospholipase Cγ (PLCγ), and extracellular signal-regulated kinase (ERK) phosphorylation, identifying this chemokine as a direct counter-regulatory molecule of VEGF signaling within the liver. Accordingly, systemic administration of Cxcl9 led to a strong attenuation of neoangiogenesis and experimental liver fibrosis in vivo . Conclusion: The results identify direct angiostatic and antifibrotic effects of the Cxcr3 ligand Cxcl9 in a model of experimental liver fibrosis. The amelioration of liver damage by systemic application of Cxcl9 might offer a novel therapeutic approach for chronic liver diseases associated with increased neoangiogenesis. (Hepatology 2012)
Read moreSTUDY QUESTION: Can anti-Müllerian hormone (AMH) automated immunoassays (Elecsys® and Access) be used interchangeably as a companion diagnostic for individualisation of follitropin delta dosing? SUMMARY ANSWER: The Access assay gives systematically higher AMH values than the Elecsys® assay which results in over 29% of women being misclassified to a different follitropin delta dose. WHAT IS KNOWN ALREADY: Follitropin delta is the first gonadotrophin to be licenced with a companion diagnostic, the Roche Elecsys® AMH Plus assay. Alternative automated AMH assays including the Beckman Coulter Access immunoassay are considered to provide similar results, but clarification of their suitability as an off-licence companion diagnostic for follitropin delta is required. STUDY DESIGN, SIZE, DURATION: We systematically searched the existing literature for studies that had measured AMH using both automated assays in the same cohort of women. Individual paired patient data were acquired from each author and combined with unpublished data. PARTICIPANTS/MATERIALS, SETTING, METHODS: We identified five eligible prospective published studies and one additional unpublished study. A 100% response from the authors was achieved. We collected paired AMH data on samples from 848 women. Passing-Bablok regression and Bland-Altman plots were used to compare the analytical performance of the two assays. The degree of misclassification to different treatment categories was estimated should the Access AMH be used as a companion diagnostic instead of the Elecsys AMH in determining the dosing of follitropin delta. MAIN RESULTS AND THE ROLE OF CHANCE: The Passing-Bablok regression shows a linear relationship (Access = -0.05 + 1.10 × Elecsys). The Access assay systematically gave higher values by an average of 10% compared with the Elecsys assay (slope = 1.10, 95% CI: 1.09 to 1.12). The average of the difference between the two assays was 2.7 pmol/l. The 95% limits of agreement were -11.7 to 6.3. Overall 253 (29.3%) women would have received an inappropriate follitropin delta dose if the Beckman Coulter Access assay was used. Specifically, a substantial proportion of women (ranging from 49% to 90% depending on the AMH category) would receive a lower dose of follitropin delta based on the Access AMH assay. Up to 10% (ranging from 2.5% to 10%) of women with high ovarian reserve would have been misclassified to a greater dose of follitropin delta based on the Access AMH assay. LIMITATIONS REASONS FOR CAUTION: We compared the values of the two principal automated assays, extrapolation of our findings to other automated AMH assays would require similar comprehensive examination. WIDER IMPLICATIONS OF THE FINDINGS: An international standard for the calibration of the automated AMH assays is warranted to facilitate efficient use of AMH as a companion diagnostic. The variable calibration of alternative automated AMH assays may adversely impact on the performance of the follitropin delta dosing algorithm. STUDY FUNDING/COMPETING INTEREST(S): No formal funding has been received for this study. SI is funded by a UK Medical Research Council skills development fellowship (MR/N015177/1). SMN has received speakers fees, travel to meetings and participated in advisory Boards for Beckman Coulter, IBSA, Ferring Pharmaecuticals, Finox, Merck Serono, Merck and Roche Diagnostics. SMN has received research support from Ansh laboratories, Beckman Coulter, Ferring Pharmaceuticals and Roche Diagnostics. TRIAL REGISTRATION NUMBER: N/A.
Read moreBACKGROUND: Factor VII activating protease (FSAP) is a circulating serine protease strongly expressed in unstable plaques and may serve as a marker of plaque destabilization. The aim of this study was to examine the relation between plasma concentrations of FSAP and clinical instability and outcome in coronary artery disease (CAD). METHODS AND RESULTS: Circulating FSAP concentration and activity, as well as FSAP mRNA expression in monocytes, were measured in 231 sequential patients who underwent coronary angiography because of stable angina pectoris (n=50), unstable angina pectoris (n=43), or acute myocardial infarction (n=87). FSAP activity, but not FSAP antigen concentration, was elevated in patients with CAD compared with a control group. Elevated FSAP activity (≥1.035 plasma equivalent units [PEU]/ml) indicated a significantly increased risk of death or non-fatal myocardial infarction during 1 year of follow-up as compared with patients with low activity of FSAP (odds ratio 1.895 [95% confidence interval 1.093-3.283]; P=0.023). Furthermore, there were no significant changes in the FSAP expression in monocytes from CAD and control subjects in the basal state but there were differences after stimulation with proinflammatory factors. CONCLUSIONS: Plasma FSAP activity was significantly increased in patients with acute coronary syndrome and may be involved in the pathogenesis of these conditions. High levels of FSAP activity were predictive of adverse events during follow-up, suggesting its potential role in risk stratification and clinical management of CAD patients.
Read moreHintergrund: Im Rahmen der Leberschädigung differenzieren ruhende hepatische Sternzellen (HSCs) in aktivierte Myofibroblasten (MFB). TGF-β und der auxiläre Rezeptor Endoglin (ENG) sind wichtige Zytokine, die hierbei zelluläre Signale vermitteln. Murine Sternzell-Linien sind ein wichtiges Werkzeug um hepatische Sternzellen in vitro zu untersuchen.
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