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The partial hepatectomy (PH) model is widely used to study liver regeneration. Currently, the extent of regeneration is analyzed by measuring the weight of the liver post-mortem or by magnetic resonance imaging. In this study we aimed to determine whether liver volume gain can be accurately measured using micro-computed tomography (microCT). Approximately 42% of the liver was removed by ligation in C57BL/6 N mice. Mice were divided into two study groups. In group 1 conventional characterization of liver hyperplasia was performed by weighing the liver post-mortem. In group 2, liver volume gain was determined by microCT volume estimation. MicroCT results showed equivalent regeneration rates compared with the conventional method without the need to mathematically determine initial liver weights before PH. This parameter is strongly influenced by the age, strain and sex of the mice. In addition non-invasive microCT determination of volume gain over multiple time-points using the same animal reduces the number of animals needing to be used (in line with the 3R principle of replacement, reduction and refinement). [ABSTRACT FROM AUTHOR]

Background and Aims: High frequency electrosurgery has a key role in the broadening application of liver surgery. Its molecular signature, i.e. the metabolites evolving from electrocauterization which may inhibit hepatic wound healing, have not been systematically studied. Methods: Human liver samples were thus obtained during surgery before and after electrosurgical dissection and subjected to a two-stage metabolomic screening experiment (discovery sample: N = 18, replication sample: N = 20) using gas chromatography/mass spectrometry. Results: In a set of 208 chemically defined metabolites, electrosurgical dissection lead to a distinct metabolic signature resulting in a separation in the first two dimensions of a principal components analysis. Six metabolites including glycolic acid, azelaic acid, 2-n-pentylfuran, dihydroactinidiolide, 2-butenal and n-pentanal were consistently increased after electrosurgery meeting the discovery (p<2.0×10−4) and the replication thresholds (p<3.5×10−3). Azelaic acid, a lipid peroxidation product from the fragmentation of abundant sn-2 linoleoyl residues, was most abundant and increased 8.1-fold after electrosurgical liver dissection (preplication = 1.6×10−4). The corresponding phospholipid hexadecyl azelaoyl glycerophosphocholine inhibited wound healing and tissue remodelling in scratch- and proliferation assays of hepatic stellate cells and cholangiocytes, and caused apoptosis dose-dependently in vitro, which may explain in part the tissue damage due to electrosurgery. Conclusion: Hepatic electrosurgery generates a metabolic signature with characteristic lipid peroxidation products. Among these, azelaic acid shows a dose-dependent toxicity in liver cells and inhibits wound healing. These observations potentially pave the way for pharmacological intervention prior liver surgery to modify the metabolic response and prevent postoperative complications. [ABSTRACT FROM AUTHOR]

IL-6 is a key regulator of immune responses after bacterial infection. IL-6 signaling is mediated via the receptor subunits IL-6R and gp130. The signal transducing subunit gp130 is ubiquitously expressed whereas IL-6R expression is restricted to hepatocytes and some leukocytes. The IL-6R can be cleaved from the cell surface by ADAM proteases. The soluble form of the IL-6R (sIL-6R) has the same IL-6 binding affinity as the membrane-bound receptor. The resulting IL-6/sIL-6R complex activates cells, which only express gp130 on their cell surface, a process called trans-signaling. Thus, IL-6-transsignaling following IL-6R proteolysis essentially renders all cells of the body responsive to IL-6. The proteolytic web controlling IL-6R shedding in vivo under pathophysiological conditions is poorly characterized. Recently, it was demonstrated that human IL-6R is a substrate for the protease ADAM17 in contrast to the murine ADAM17, which is mainly cleaved by ADAM10. However, these data were raised in cell culture systems. We analyzed IL-6R shedding in vivo on leukocytes after infection with Listeria monocytogenes or LPS-challenge of ADAM17 and ADAM10-deficient mice. ADAM17 and ADAM10 knockout mice are not viable. For this reason we generated a hypomorphic ADAM17 mouse model which expresses only 5% of the normal ADAM17 levels. Additionally we use conditional ADAM10 mice with ADAM10 deleted either in monocytes or Tcells. Listeria infection led to massive shedding of the IL-6R on Tcells and inflammatory monocytes. Further we could demonstrate that Listeria-induced IL-6R cleavage is abrogated in hypomorphic ADAM17ex/ex mice. Additionally we can show that serum levels of sIL-6R are elevated after LPS challenge of wildtype but not ADAM17ex/ex mice. These results strongly suggest that ADAM17 is the main IL-6R sheddase under pathophysiological conditions. In future experiments we will evaluate the contribution of the protease ADAM10 in mediating IL-6R shedding to uncover the proteolytic steps involved in IL-6 trans-signaling. [ABSTRACT FROM AUTHOR]