No abstract

Objective-The formation of neutrophil extracellular traps and the exposure of nucleosomes on these neutrophil extracellular traps contribute to coagulation activation and the propagation of deep vein thrombosis (DVT) in animal models. However, no data are available on the role of neutrophil extracellular traps or nucleosomes in patients with thrombosis. Methods and Results-We conducted a case-control study, in which levels of circulating nucleosomes and neutrophil elastase-α1-antitrypsin complexes were assessed in plasma from 150 patients with objectified symptomatic DVT (cases) and compared with 195 patients with a clinical suspicion of DVT but in whom DVT was excluded (controls). We explored the association between both nucleosomes and elastase-α1-antitrypsin complexes, and the presence of DVT by calculating the odds ratio with corresponding 95% CIs. Elevated levels of both circulating nucleosomes and elastase-α1-antitrypsin complexes were associated with a 3-fold risk of DVT, and the associations remained similar after adjustment for potential confounders (malignancy, smoking, recent immobilization, recent hospitalization). The risk increased with higher nucleosome and elastase-α1-antitrypsin complex levels, suggesting a dose-dependent relationship among circulating nucleosomes, activated neutrophils, and DVT. Conclusion-Our study suggests an association among circulating nucleosomes, activated neutrophils, and presence of DVT in humans, which might have implications for treatment and prevention.

Placement of a new non-foreshortening nitinol enteral stent is safe and without major complications. This stent design produces significant relief of obstructive symptoms and improves quality of life in patients with incurable malignant GOO.

Objective-Coagulation factor XI is proposed as therapeutic target for anticoagulation. However, it is still unclear whether the antithrombotic properties of factor XI inhibitors influence atherosclerotic disease and atherothrombosis. Our aim is to investigate whether factor XI antisense oligonucleotides could prevent thrombus formation on acutely ruptured atherosclerotic plaques. Approach and Results-Atherosclerotic plaques in the carotid arteries of Apoe −/− mice were acutely ruptured using ultrasound. The subsequent thrombus formation was visualized and quantified by intravital microscopy and immunohistochemistry. Mice were pretreated with either factor XI antisense or nonsense oligonucleotides (50 mg/kg) to lower factor XI plasma levels. A tail bleeding assay was used to determine the safety. On plaque rupture, initial platelet adhesion and platelet plug formation were not impaired in animals treated with factor XI antisense oligonucleotides. However, the ensuing thrombus formation and fibrin deposition were significantly lower after 5 to 10 minutes (P<0.05) in factor XI antisense oligonucleotide-treated animals without inducing a bleeding tendency. Furthermore, thrombi from antisense-treated animals were less stable than thrombi from placebo-treated animals. Moreover, macrophage infiltration and collagen deposition were lower in the carotid arteries of factor XI antisense-treated animals. No neutrophils were present. Conclusions-Factor

Coagulation factor XI (FXI) is a promising target for anticoagulation, because of its major role in thrombosis and relatively minor role in haemostasis. This implies that inhibition of FXI can prevent thrombosis without causing bleeding. It was our aim to investigate the antithrombotic properties of two novel inhibitory anti-human FXI antibodies (αFXI-175 and αFXI-203). The in vitro properties of both antibodies were analysed using standard clotting assays and calibrated automated thrombography. For the in vivo model we used FXI knockout mice, in which FXI plasma levels were restored with purified human FXI. Thrombosis was induced by applying ferric chloride to the vena cava inferior, after which time to occlusion was analysed. A tail bleeding assay was used to investigate the safety of both antibodies. Using calibrated automated thrombography, both antibodies inhibited thrombin generation initiated via the intrinsic pathway. In contrast, upon tissue factor (TF)-initiated thrombin generation, αFXI-203 did not inhibit thrombin generation, while αFXI-175 inhibited thrombin generation only at low concentrations of TF. In the murine thrombosis model, the vena cava inferior remained patent for 25 minutes (min) in mice treated with αFXI-175 and for 12.5 min in αFXI-203 treated animals, which was significantly longer than in placebo-treated animals (5 min, p<0.05). Neither antibody caused severe blood loss in a tail bleeding assay. In conclusion, the two inhibitory antibodies against FXI prevented cessation of blood flow in a murine thrombosis model without inducing a bleeding tendency.

The contact pathway of coagulation consists of the proteins factor XI, factor XII, prekallikrein, and high-molecularweight kininogen. Activation of the contact system leads to procoagulant and proinflammatory reactions. The contact system is essential for surface-initiated coagulation, as exemplified by aPTT, but there is probably no role for the contact system in initiating physiologic in vivo coagulation. However, over the last few years, there has been renewed interest, especially because of experimental evidence suggesting that the contact system contributes to thrombosis. Knockout mice deficient in one of the contact proteins were protected against artificially induced thrombosis. Furthermore, inhibiting agents such as monoclonal antibodies, antisense oligonucleotides, and small molecules were found to prevent thrombosis in rodents and primates in both venous and arterial vascular beds. Although it remains to be established whether targeting the contact system will be effective in humans and which of the contact factors is the best target for anticoagulation, it would constitute a promising approach for future effective and safe antithrombotic therapy. Learning Objectives• To understand that the contact system consists of 4 proteins: factor XI, factor XII, PK, and HK • To understand that deficiency of factor XII, PK, or HK is not associated with a bleeding tendency in humans • To understand that targeting the contact system is an effective method to prevent thrombosis in mice •

SummaryAntithrombotic drugs like vitamin K antagonists and heparin have been the gold standard for the treatment and prevention of thromboembolic disease for many years. Unfortunately, there are several disadvantages of these antithrombotic drugs: they are accompanied by serious bleeding problems, it is necessary to monitor the therapeutic window, and there are various interactions with food and other drugs. This has led to the development of new oral anticoagulants, specifically inhibiting either thrombin or factor Xa. In terms of effectiveness, these drugs are comparable to the currently available anticoagulants; however, they are still associated with issues such as bleeding, reversal of the drug and complicated laboratory monitoring. Vitamin K antagonists, heparin, direct thrombin and factor Xa inhibitors have in common that they target key proteins of the haemostatic system. In an attempt to overcome these difficulties we investigated whether the intrinsic coagulation factors (VIII, IX, XI, XII, prekallikrein and high-molecular-weight kininogen) are superior targets for anticoagulation. We analysed epidemiological data concerning thrombosis and bleeding in patients deficient in one of the intrinsic pathway proteins. Furthermore, we discuss several thrombotic models in intrinsic coagulation factor-deficient animals. The combined results suggest that intrinsic coagulation factors could be suitable targets for anticoagulant drugs.

Background Resections for Crohn’s disease should be limited and only resect macroscopically affected bowel. However, recent studies suggest microscopic inflammation at resection margins as a predictor for postoperative recurrence. The clinical impact remains unclear, as non-uniform pathological criteria have been used. The aim of this study was to assess the predictive value of pathological characteristics at ileocecal resection margins for recurrence. Methods Both resection margins of 106 consecutive patients undergoing ileocecal resection for Crohn’s disease between 2002 and 2009 were revised and scored for active inflammation, myenteric plexitis, and granulomas. Pathological findings were correlated to recurrence, defined as recurrent disease activity demonstrated by endoscopy (modified Rutgeerts score ≥i2) requiring upscaling medical treatment, using multivariate analysis. Results Active inflammation was found at the proximal and distal resection margin in 27% and 15% of patients, respectively, myenteric plexitis in 37% and 32%, respectively, and granulomas in 4% and 6%, respectively. In total, 47 out of 106 patients developed recurrence. Only active inflammation at the distal colonic resection margin was an independent significant predictor for recurrence (88% vs 43% vs 51% for distal, proximal, and no involved margins, respectively; P &lt; 0.01). Conclusion Active inflammation at the distal colonic resection margin after ileocecal resection identifies a patient group at high risk for postoperative recurrence both at the anastomotic site and the colon because it identifies undiagnosed L3 disease. These patients have a different and more aggressive natural history and require more intense medical treatment. Therefore, pathological evaluation of the distal resection margin should be implemented in daily practice.