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Activated factor xiia

Katrijn R Six, Rosalie Devloo, Britt Van Aelst, Philippe Vandekerckhove, Hendrik B Feys, Veerle Compernolle
Microfluidic models of hemostasis assess platelet function under conditions of hydrodynamic shear, but in the presence of anticoagulants, this analysis is restricted to platelet deposition only. The intricate relationship between Ca(2+)-dependent coagulation and platelet function requires careful and controlled recalcification of blood prior to analysis. Our setup uses a Y-shaped mixing channel, which supplies concentrated Ca(2+)/Mg(2+) buffer to flowing blood just prior to perfusion, enabling rapid recalcification without sample stasis...
February 14, 2017: Journal of Visualized Experiments: JoVE
Sarah Hopp, Marc W Nolte, Christian Stetter, Christoph Kleinschnitz, Anna-Leena Sirén, Christiane Albert-Weissenberger
BACKGROUND: Traumatic brain injury (TBI) is a devastating neurological condition and a frequent cause of permanent disability. Posttraumatic inflammation and brain edema formation, two pathological key events contributing to secondary brain injury, are mediated by the contact-kinin system. Activation of this pathway in the plasma is triggered by activated factor XII. Hence, we set out to study in detail the influence of activated factor XII on the abovementioned pathophysiological features of TBI...
February 20, 2017: Journal of Neuroinflammation
Namhee Kim, Ja-Yoon Gu, Hyun Ju Yoo, Se Eun Han, Young Il Kim, Il Sung Nam-Goong, Eun Sook Kim, Hyun Kyung Kim
BACKGROUND: Hyperthyroidism is associated with increased thrombotic risk. As contact system activation through formation of neutrophil extracellular traps (NET) has emerged as an important trigger of thrombosis, we hypothesized that the contact system is activated along with active NET formation in hyperthyroidism and that their markers correlate with disease severity. SUBJECTS AND METHODS: In 61 patients with hyperthyroidism and 40 normal controls, the levels of coagulation factors (fibrinogen, and factor VII, VIII, IX, XI and XII), D-dimer, thrombin generation assay (TGA) markers, NET formation markers (histone-DNA complex, double-stranded DNA and neutrophil elastase) and contact system markers (activated factor XII (XIIa), high-molecular-weight kininogen (HMWK), prekallikrein and bradykinin) were measured...
May 2017: European Journal of Endocrinology
Ivan Ivanov, Ruhama Shakhawat, Mao-Fu Sun, S Kent Dickeson, Cristina Puy, Owen J T McCarty, Andras Gruber, Anton Matafonov, David Gailani
The plasma zymogens factor XI (fXI) and prekallikrein (PK) are activated by factor XIIa (fXIIa) during contact activation. Polyanions such as DNA and RNA may contribute to thrombosis and inflammation partly by enhancing PK and fXI activation. We examined PK and fXI activation in the presence of nucleic acids, and determine the effects of the cofactor high molecular weight kininogen (HK) on the reactions. In the absence of HK, DNA and RNA induced fXI autoactivation. Proteases known to activate fXI (fXIIa and thrombin) did not enhance this process appreciably...
April 3, 2017: Thrombosis and Haemostasis
Christopher M Barbieri, Xinkang Wang, Weizhen Wu, Xueping Zhou, Aimie M Ogawa, Kim O'Neill, Donald Chu, Gino Castriota, Dietmar A Seiffert, David E Gutstein, Zhu Chen
Coagulation Factor XII (FXII) plays a critical role in thrombosis. What is unclear is the level of enzyme occupancy of FXIIa needed for efficacy, and impact of FXIIa inhibition on cerebral embolism. A selective FXIIa inhibitor, recombinant human albumin-tagged mutant Infestin4 (rHA-Mut-inf), was generated to address these questions. rHA-Mut-inf displayed potency comparable to the original wild-type HA-Infestin4 (rHA-WT-inf) (human FXIIa KI = 0.07 and 0.12 nM, respectively), with markedly improved selectivity against FXa and plasmin...
December 29, 2016: Journal of Pharmacology and Experimental Therapeutics
Joshua M Gajsiewicz, Stephanie A Smith, James H Morrissey
The contact pathway of the plasma clotting cascade is dispensable for normal hemostasis, but contributes to thrombosis and serves as a bridge between inflammation and coagulation. This pathway is triggered upon exposure of plasma to certain anionic polymers and artificial surfaces. Recently, extracellular nucleic acids and inorganic polyphosphate (polyP) have been implicated as being important (patho)physiologically relevant activators of this pathway. However, mechanistic details regarding how nucleic acids or polyP modulate the individual reactions of the contact pathway have been lacking...
February 3, 2017: Journal of Biological Chemistry
Manish P Ponda, Jan L Breslow
Chemokines and their receptors play a critical role in immune function by directing cell-specific movement. C-C chemokine receptor 7 (CCR7) facilitates entry of T cells into lymph nodes. CCR7-dependent chemotaxis requires either of the cognate ligands C-C chemokine ligand 19 (CCL19) or CCL21. Although CCR7-dependent chemotaxis can be augmented through receptor up-regulation or by increased chemokine concentrations, we found that chemotaxis is also markedly enhanced by serum in vitro. Upon purification, the serum cofactor activity was ascribed to domain 5 of high-molecular-weight kininogen...
October 24, 2016: Proceedings of the National Academy of Sciences of the United States of America
Ann-Kathrin Schoenfeld, Eric Lahrsen, Susanne Alban
The serpin C1 inhibitor (C1-INH) is the only regulator of classical complement activation as well as the major regulator of the contact system. Its importance is demonstrated by hereditary angioedema (HAE), a severe disease with potentially life-threatening attacks due to deficiency or dysfunction of C1-INH. C1-INH replacement is the therapy of choice in HAE. In addition, C1-INH showed to have beneficial effects in other diseases characterized by inappropriate complement and contact system activation. Due to some limitations of its clinical application, there is a need for improving the efficacy of therapeutically applied C1-INH or to enhance the activity of endogenous C1-INH...
2016: PloS One
Allen P Kaplan, Kusumam Joseph
Plasma of patients with types I and II hereditary angioedema is unstable if incubated in a plastic (i.e., inert) vessel at 37 °C manifested by progressively increasing formation of bradykinin. There is also a persistent low level of C4 in 95 % of patients even when they are symptomatic. These phenomena are due to the properties of the C1r subcomponent of C1, factor XII, and the bimolecular complex of prekallikrein with high molecular weight kininogen (HK). Purified C1r auto-activates in physiologic buffers, activates C1s, which in turn depletes C4...
October 2016: Clinical Reviews in Allergy & Immunology
Zonne L M Hofman, Anurag Relan, Sacha Zeerleder, Christian Drouet, Bruce Zuraw, C Erik Hack
Hereditary angioedema (HAE) caused by a deficiency of functional C1-inhibitor (C1INH) becomes clinically manifest as attacks of angioedema. C1INH is the main inhibitor of the contact system. Poor control of a local activation process of this system at the site of the attack is believed to lead to the formation of bradykinin (BK), which increases local vasopermeability and mediates angioedema on interaction with BK receptor 2 on the endothelium. However, several observations in patients with HAE are difficult to explain from a pathogenic model claiming a local activation process at the site of the angioedema attack...
August 2016: Journal of Allergy and Clinical Immunology
Haley R Gittleman, Alona Merkulova, Omar Alhalabi, Evi X Stavrou, Martina L Veigl, Jill S Barnholtz-Sloan, Alvin H Schmaier
Plasma kallikrein formed from prekallikrein (PK) produces bradykinin from kininogens and activates factor XII. Plasma PK is activated by factors αXIIa, βXIIa, or prolylcarboxypeptidase (PRCP). A cross-sectional investigation determined if there is an association of PRCP and KLKB1 polymorphisms with cardiovascular disease (CVD). DNA was obtained from 2243 individuals from the Prevention of Events with Angiotensin Converting Enzyme trial. Two PRCP SNPs, rs7104980 and rs2298668, and two KLKB1 SNPs, rs3733402 and rs3087505, were genotyped...
2016: Frontiers in Medicine
Pudur Jagadeeswaran, Brian C Cooley, Peter L Gross, Nigel Mackman
Thrombosis is a leading cause of morbidity and mortality worldwide. Animal models are used to understand the pathological pathways involved in thrombosis and to test the efficacy and safety of new antithrombotic drugs. In this review, we will first describe the central role a variety of animal models of thrombosis and hemostasis has played in the development of new antiplatelet and anticoagulant drugs. These include the widely used P2Y12 antagonists and the recently developed orally available anticoagulants that directly target factor Xa or thrombin...
April 29, 2016: Circulation Research
Kjeld Christensen, Huda Kozarcanin, Kristina N Ekdahl, Bo Nilsson
INTRODUCTION: Factor (F) XIIa is an attractive target for anticoagulation in arterial thrombosis. The aim of this study is to investigate the degree of involvement of the contact system in cardiac infarctions. METHODS AND PATIENTS: 165 patients suffering from ST-elevation myocardial infarction (STEMI) and 100 healthy controls were included in the study. Samples were drawn at admission before percutaneous intervention (PCI), 1-3days post-percutaneous intervention (PCI) and, in one-third of the patients, 3months after PCI...
May 2016: Thrombosis Research
Sacha Zeerleder, Marcel Levi
Uncontrolled generation of bradykinin (BK) due to insufficient levels of protease inhibitors controlling contact phase (CP) activation, increased activity of CP proteins, and/or inadequate degradation of BK into inactive peptides increases vascular permeability via BK-receptor 2 (BKR2) and results in subcutaneous and submucosal edema formation. Hereditary and acquired angioedema due to C1-inhibitor deficiency (C1-INH-HAE and -AAE) are diseases characterized by serious and potentially fatal attacks of subcutaneous and submucosal edemas of upper airways, facial structures, abdomen, and extremities, due to inadequate control of BK generation...
2016: Annals of Medicine
Nilima Biswas, Adam X Maihofer, Saiful Anam Mir, Fangwen Rao, Kuixing Zhang, Srikrishna Khandrika, Manjula Mahata, Ryan S Friese, C Makena Hightower, Sushil K Mahata, Dewleen G Baker, Caroline M Nievergelt, Sucheta M Vaingankar, Daniel T O'Connor
BACKGROUND: Plasma coagulation Factor XIIa (Hageman factor; encoded by F12) and kallikrein (KAL or Fletcher factor; encoded by KLKB1) are proteases of the kallikerin-kinin system involved in converting the inactive circulating prorenin to renin. Renin is a key enzyme in the formation of angiotensin II, which regulates blood pressure, fluid and electrolyte balance and is a biomarker for cardiovascular, metabolic and renal function. The renin-angiotensin system is implicated in extinction learning in posttraumatic stress disorder...
2016: BMC Medical Genetics
Yasin Kokoye, Ivan Ivanov, Qiufang Cheng, Anton Matafonov, S Kent Dickeson, Shauna Mason, Daniel J Sexton, Thomas Renné, Keith McCrae, Edward P Feener, David Gailani
Studies with animal models implicate the plasma proteases factor XIIa (FXIIa) and α-kallikrein in arterial and venous thrombosis. As congenital deficiencies of factor XII (FXII) or prekallikrein (PK), the zymogens of FXIIa and α-kallikrein respectively, do not cause bleeding disorders, inhibition of these enzymes may have therapeutic benefit without compromising hemostasis. The relative contributions of FXIIa and α-kallikrein to thrombosis in animal models are not clear. We compared mice lacking FXII or PK to wild type mice in established models of arterial thrombosis...
April 2016: Thrombosis Research
Charlotte Bouckaert, Silvia Serra, Grégoire Rondelet, Eduard Dolušić, Johan Wouters, Jean-Michel Dogné, Raphaël Frédérick, Lionel Pochet
Inhibitors of the coagulation factor XIIa (FXIIa) are attractive to detail the roles of this protease in hemostasis and thrombosis, to suppress artifact due to contact pathway activation in blood coagulation assays, and they are promising as antithrombotic therapy. The 3-carboxamide coumarins have been previously described as small-molecular-weight FXIIa inhibitors. In this study, we report a structure-activity relationship (SAR) study around this scaffold with the aim to discover new selective FXIIa inhibitors with an improved physico-chemical profile...
March 3, 2016: European Journal of Medicinal Chemistry
Jennifer Krupka, Frauke May, Thomas Weimer, Ingo Pragst, Christoph Kleinschnitz, Guido Stoll, Con Panousis, Gerhard Dickneite, Marc W Nolte
BACKGROUND AND PURPOSE: Ischemic stroke provokes severe brain damage and remains a predominant disease in industrialized countries. The coagulation factor XII (FXII)-driven contact activation system plays a central, but not yet fully defined pathogenic role in stroke development. Here, we investigated the efficacy of the FXIIa inhibitor rHA-Infestin-4 in a rat model of ischemic stroke using both a prophylactic and a therapeutic approach. METHODS: For prophylactic treatment, animals were treated intravenously with 100 mg/kg rHA-Infestin-4 or an equal volume of saline 15 min prior to transient middle cerebral artery occlusion (tMCAO) of 90 min...
2016: PloS One
Marie Worm, Elodie C Köhler, Rachita Panda, Andy Long, Lynn M Butler, Evi X Stavrou, Katrin F Nickel, Tobias A Fuchs, Thomas Renné
The plasma protein factor XII (FXII) is the initiating protease of the procoagulant and proinflammatory contact system. FXII activates both the bradykinin (BK) producing kallikrein-kinin system and the intrinsic pathway of coagulation. Contact with negatively charged surfaces induces auto-activation of zymogen FXII that results in activated FXII (FXIIa). Various in vivo activators of FXII have been identified including heparin, misfolded protein aggregates, nucleic acids and polyphosphate. Murine models have established a central role of FXII in arterial and venous thromboembolic diseases...
October 2015: Annals of Translational Medicine
Shan Huang, Anna E Engberg, Nina Jonsson, Kerstin Sandholm, Ian A Nicholls, Tom Eirik Mollnes, Karin Fromell, Bo Nilsson, Kristina N Ekdahl
BACKGROUND: Inappropriate and uncontrolled activation of the cascade systems in the blood is a driving force in adverse inflammatory and thrombotic reactions elicited by biomaterials, but limited data are available on the activation of the contact system by polymers and the present study was undertaken to investigate these mechanisms in established models. METHODS: Polymer particles were incubated in (1) EDTA-plasma (10 mM) to monitor the adsorption of 20 selected proteins; (2) lepirudin-anticoagulated plasma to evaluate contact system activation, monitored by the formation of complexes between the generated proteases factor[F]XIIa, FXIa and kallikrein and the serpins C1-inhibitor [C1INH] and antithrombin [AT]; (3) lepirudin-anticoagulated whole blood to determine cytokine release...
January 2016: Biomaterials
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