Hannes Hartman

P-selectin mediates neutrophil rolling and recruitment in acute pancreatitis.

The adhesive mechanisms regulating leucocyte–endothelium interactions in the pancreas remain elusive, but selectins may play a role. This study examined the molecular mechanisms mediating leucocyte rolling along the endothelium in the pancreas and the therapeutic potential of targeting the rolling adhesive interaction in acute pancreatitis (AP).

Neutrophil Extracellular Traps Induce Trypsin Activation, Inflammation, and Tissue Damage in Mice With Severe Acute Pancreatitis.

BACKGROUND & AIMS Neutrophils are involved in the development of acute pancreatitis (AP), but it is not clear how neutrophil-induced tissue damage is regulated. In addition to secreting antimicrobial compounds, activated neutrophils eliminate invading microorganisms by expelling nuclear DNA and histones to form extracellular web-like structures called neutrophil extracellular traps (NETs). However, NETs have been reported to contribute to organ dysfunction in patients with infectious diseases. We investigated whether NETs contribute to the development of AP in mice. METHODS AP was induced in C57BL/6 mice by infusion of taurocholate into the pancreatic duct or by intraperitoneal administration of L-arginine. Pancreata were collected and extracellular DNA was detected by Sytox green staining, levels of CXC chemokines, histones, and cytokines also were measured. Cell-free DNA was quantified in plasma samples. Signal transducer and activator of transcription 3 phosphorylation and trypsin activation were analyzed in isolated acinar cells. NETs were depleted by administration of DNase I to mice. Plasma was obtained from healthy individuals (controls) and patients with severe AP. RESULTS Infusion of taurocholate induced formation of NETs in pancreatic tissues of mice and increased levels of cell-free DNA in plasma. Neutrophil depletion prevented taurocholate-induced deposition of NETs in the pancreas. Administration of DNase I to mice reduced neutrophil infiltration and tissue damage in the inflamed pancreas and lung, and decreased levels of blood amylase, macrophage inflammatory protein-2, interleukin 6, and high-mobility groups protein 1. In mice given taurocholate, DNase I administration also reduced expression of integrin α M (macrophage-1 antigen) on circulating neutrophils. Similar results occurred in mice with L-arginine-induced AP. Addition of NETs and histones to acinar cells induced formation of trypsin and activation of signal transducer and activator of transcription 3; these processes were blocked by polysialic acid. Patients with severe AP had increased plasma levels of NET components compared with controls. CONCLUSIONS NETs form in the pancreata of mice during the development of AP, and NET levels are increased in plasma from patients with AP, compared with controls. NETs regulate organ inflammation and injury in mice with AP, and might be targeted to reduce pancreatic tissue damage and inflammation in patients.

Platelets regulate P-selectin expression and leukocyte rolling in inflamed venules of the pancreas

Recent data suggest that platelets regulate inflammatory changes and tissue damage in acute pancreatitis although the role of platelets in leukocyte-endothelium interactions in the pancreatic microcirculation is not known. The aim of this study was to define the impact of platelets on leukocyte rolling and adhesion in acute pancreatitis. Acute pancreatitis was induced in C57BL/6 mice by caerulein challenge. Mice were treated with an anti-GP1bα (CD42b) antibody, which depletes platelets, or a control antibody before caerulein. Leukocyte rolling and adhesion were determined by the use of intravital fluorescence microscopy 18 h after the last dose of caerulein. In separate experiments, leukocyte-endothelium interactions were determined before and after administration of an anti-P-selectin, anti-PSGL-1 and a control antibody in mice with caerulein pancreatitis. Circulating platelet-neutrophil aggregates and pancreatic P-selectin mRNA were quantified 1 and 6h respectively after caerulein challenge. Caerulein administration increased leukocyte and platelet interactions in the pancreatic microvasculature, increased tissue damage and expression of P-selectin mRNA in the pancreas as well as platelet-neutrophil complexes in the circulation. Notably, platelet depletion markedly reduced caerulein-provoked leukocyte rolling and adhesion in postcapillary venules. Interestingly, depletion of platelets significantly decreased caerulein-induced gene expression of P-selectin in the pancreas. Moreover, immunoneutralization of P-selectin and PSGL-1 abolished leukocyte rolling in the pancreatic venules triggered by caerulein. Our novel findings demonstrate that platelets regulate leukocyte rolling in acute pancreatitis via induction of P-selectin, which was critical in supporting leukocyte rolling in inflamed venules of the pancreas.

Predictive Capacity of Biomarkers for Severe Acute Pancreatitis.

Background: Early prediction of severe acute pancreatitis (SAP) substantially improves treatment of patients. A large amount of biomarkers have been studied with this objective. The aim of this work was to study predictive biomarkers using preset cut-off levels in an unselected population of patients with acute pancreatitis (AP). Methods: 232 patients (52.2% males, median age 66 years) with AP admitted to Skåne University Hospital, Malmö, were consecutively enrolled. Blood samples were collected upon admission and clinical data were gathered both prospectively at inclusion and through review of medical notes. Cut-off levels were defined based on the reports of prior studies, and through their results eight biomarkers (IL-1β, IL-6, IL-8, IL-10, TNF-α, MCP-1, procalcitonin and D-dimer) were selected for analysis. Results: Of the patients, 83.2% had mild AP and 16.8% had SAP. Levels of IL-1β, IL-6 and IL-10 were significantly (p < 0.05) higher upon admission in the group with SAP. When applying the preset cut-off levels on our material, sensitivity and specificity for prediction of severity were low. Receiver operating characteristic curves showed that selected cut-off levels were acceptable, but areas under the curves were inferior compared to other studies. The results did not improve when using the revised Atlanta 2012 classification. Conclusions: Previous studies on severity prediction of AP are difficult to compare due to large variations in setups and outcomes. Calculated cut-offs in our cohort were in acceptable range from preset levels, however areas under the curves were low, indicating suboptimal biomarkers for the unselected population investigated. For comparable results and possible clinical implementations, future studies need large consecutive series with a reasonable percentage of severe cases. Additionally, novel biomarkers need to be explored.

Contents Vol. 56, 2016

I. Alwayn, Halifax D.K. Bartsch, Marburg C. Bassi, Verona W.O. Bechstein, Frankfurt am Main J.A. Bradley, Cambridge M. Cikirikcioglu, Geneva P.-A. Clavien, Zurich U. Dahmen, Jena R.W.F. de Bruin, Rotterdam S. Fichtner-Feigl, Regensburg H. Friess, Munich G. Galata, London D.J. Gouma, Hilversum J.K. Habermann, Lübeck M. Heberer, Basel M. Heger, Amsterdam T. Hubert, Lille W.R. Jarnagin, New York, N.Y. J.C. Kalff, Bonn M.W. Laschke, Homburg/Saar H.-A. Lehr, Friedrichshafen C.M. Malata, Cambridge T. Minor, Bonn M. Morino, Torino J. Pirenne, Leuven A. Schachtrupp, Melsungen T. Schmitz-Rixen, Frankfurt a.M. R. Schramm, Munich L. Steinstraesser, Oldenburg A. Szijártó, Budapest R.H. Tolba, Aachen M. van Griensven, Munich T.M. van Gulik, Amsterdam M.A. Venermo, Helsinki M.H. Wilhelmi, Hannover D.C. Winter, Dublin Y. Yamamoto, Akita Clinical and Experimental Surgery