C6-Deficient Mice Are Protected From the Pathogenic Effects of Antiphospholipid Antibodies.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 147-147
Author(s):  
Ana Laura Carrera-Marin ◽  
Zurina Romay-Penabad ◽  
Renan Aguilar-Valenzuela ◽  
Laura Aline Martinez-Martinez ◽  
Elizabeth Papalardo ◽  
...  
Keyword(s):  
Carotid Arteries ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Complement C3 ◽  
C5a Receptor ◽  
Chromogenic Assay ◽  
Deficient Mice

Abstract Abstract 147 Background: The pathogenic mechanisms mediated by antiphospholipid (aPL) antibodies are only partially understood. Tissue factor (TF) upregulation has been shown to play an important role and recent studies have demonstrated that mice deficient in complement C3, C5 or C5a receptor (R) are resistant to the thrombogenic effects of aPL antibodies. The complement membrane attack (C5b-9 MAC) complex has been shown to bind specific receptors, to induce TF expression and to exert procoagulant effect in various cell types (i.e. endothelial cells). However whether C5b-9 MAC plays a role in the pathogenesis of thrombosis in Antiphospholipid Syndrome (APS) is unknown. Here we addressed that question by studying the effects of human aPL antibodies on thrombosis and TF upregulation in C6 deficient (−/−) mice. Methods: C6 deficient (−/−) mice and the corresponding wild-type (WT) mice C3H/HeJ (C6+/+) were injected twice with 500γg/ml IgG isolated from a patient with APS (IgG-APS) or with the corresponding control IgG-NHS. Seventy-two h after the first injection the size of induced thrombi in the femoral vein, IgG anticardiolipin (ACL) activity in the sera were determined. TF activity was determined in homogenates of carotid arteries and in peritoneal macrophages using a chromogenic assay. Results: Thrombus sizes were significantly larger in WT mice C6 (+/+) treated with IgG-APS when compared with C6 (+/+) mice treated with IgG-NHS (p= <0.001) The sizes of thrombi were significantly smaller in the C6 (−/−) mice injected with IgG-APS compared to their WT C6 (+/+) counterparts (p= <0.001) showing an important abrogation of thrombus formation in mice lacking C6. Thrombus sizes in C6 (−/−) mice injected with IgG-NHS were not different when compared to C6 (+/+) mice treated with IgG-NHS (p= 0.786), Similarly, upregulation of TF activity in carotid arteries homogenates and in peritoneal macrophages in C6 (+/+) mice treated with IgG-APS were significantly diminished in C6 (−/−) mice (p=0.036 and p=0.041, respectively). All mice injected with IgG-APS had medium-high titers of aCL in their serum (see Table) Conclusions: These data indicate that the C6 component of the complement system mediates aPL-thrombogenic effects and not only underscore the importance of complement activation by aPL antibodies, but also propose its inhibition as a possibly novel therapeutic target for thrombosis in APS . Disclosures: No relevant conflicts of interest to declare.

Apolipoprotein E Receptor 2′ Mediates Pathogenic Effects of Dimeric β2glycoprotein I and of Anti- β2glycoprotein I Antibodies in Vivo

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 408-408
Author(s):  
Zurina Romay-Penabad ◽  
Rolf T Urbanus ◽  
Elizabeth Pappalardo ◽  
Yong Hwang ◽  
Ronald H.W.M. Derksen ◽  
...  
Keyword(s):  
Apolipoprotein E ◽  
Laser Scanning ◽  
Carotid Arteries ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Peritoneal Macrophages ◽  
Laser Scanning Microscopy ◽  
Target Cells ◽  
Pathogenic Effects

Abstract Antiphospholipid antibodies (aPL) recognize β2Glycoprotein (β2GPI)-bound to receptor (s) in target cells and trigger a pro-coagulant/pro-inflammatory phenotype [i e.:expression of tissue factor (TF), vascular cell adhesion molecule-1 (VCAM-1)] that lead to thrombosis. The interaction of β2GPI with target cells may involve more than one protein. Investigators have shown that dimeric β2GPI binds to apolipoprotein E receptor 2′ (apoER2′) in platelets, in the absence of anti-β2GPI antibodies, increases their activation and induces enhanced thrombosis and TF activity in mice. However, the role of apoER2′ in vivo in Antiphospholipid Syndrome (APS) is not completely understood. Here, we examined the in vivo effects of dimeric β2GPI and of anti-β2GPI antibodies (IgG-APS) in apoER2′ deficient (−/−) mice and in normal mice pre-treated with recombinant soluble domain 1 of apoER2′ (BD1). In vivo, dynamics of thrombus formation (thrombus sizes), TF activities in carotid artery homogenates and in peritoneal macrophages and ex vivo expression of VCAM-1 in aortas and of TF activity in peritoneal macrophages were examined in the various types of mice after two i.p. injections with 40 μg of recombinant dimeric β2GPI – or with the corresponding monomer control – or with 500 μg IgG-APS (isolated from a patient with APS by protein G Sepharose) or with control IgG (IgG-NHS). Mice injected with IgG-APS had significant titers of anticardiolipin (aCL) and anti-β2GPI antibodies in their sera. In vivo, IgG-APS increased significantly the size of the induced thrombi as well as the TF activities in carotid arteries and in peritoneal macrophages in C57BL/6J (wild type) mice when compared to same type of mice treated with IgG-NHS. Similarly, ex vivo expression of VCAM-1 in mouse aortas and of TF in peritoneal macrophages, detected by two photon excitation laser scanning microscopy were increased in normal mice treated with IgG-APS when compared to control mice. The pre-treatment with 40 μg of BD1 i.p., significantly reduced those effects. Importantly, dimeric β2GPI (in the absence of anti-β2GPI antibodies) or IgGAPS did not increase significantly thrombus size, TF activities in homogenates of carotid arteries or in peritoneal macrophages, or ex vivo expression of VCAM-1 and TF in mice lacking apoER2′. Conclusions: Altogether these data show that dimers of β2GPI mimic pathogenic effects of anti-β2GPI antibodies in mice. Most importantly, apoER2′ is a mediator of those effects in vivo. These findings may provide insights not only for a better understanding of the pathophysiology of APS but may be important in the development of new targeted therapies, by means of interfering with the binding of β2GPI-aPL complexes with their receptor(s) in target cells in vivo.

Annexin A2 Deficient Mice Are Resistant to Pathogenic Effects of Antiphospholipid Antibodies in Vivo

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 421-421
Author(s):  
Zurina Romay-Penabad ◽  
Guadalupe Montiel-Manzano ◽  
Elizabeth Pappalardo ◽  
Katherine A. Hajjar ◽  
Tuya Shilagard ◽  
...  
Keyword(s):  
Antiphospholipid Antibodies ◽  
Cell Adhesion Molecule ◽  
Carotid Arteries ◽  
Thrombus Formation ◽  
Annexin A2 ◽  
Target Cells ◽  
Wild Type ◽  
Deficient Mice ◽  
Pathogenic Effects

Abstract Background: Thrombosis is an important cause of morbidity and mortality in Antiphospholipid Syndrome (APS) and in SLE patients with antiphospholipid antibodies (aPL). APL recognize β2 glycoprotein I (β2GPI)-bound to receptor (s) in endothelial cells (EC) and other target cells (i.e. platelets, monocytes) and trigger an intracellular signalling and a pro-coagulant and pro-inflammatory phenotype [i e.expression of tissue factor (TF), vascular cell adhesion molecule-1 (VCAM-1)] that lead to thrombosis. There is in vitro evidence that annexin A2 (A2), a receptor for tissue plasminogen activator (tPA) and plasminogen – and possibly other proteins such as toll-like receptors or the receptor for apolipoprotein E2′ - may be binding β2GPI on the membrane of target cells. Here, we examined the involvement of A2 in aPL-mediated pathogenic effects in vivo. We studied the effects of aPL Abs on thrombus formation, VCAM-1 expression in aortas of mice, and TF function in carotid artery homogenates in annexin A2 deficient (−/−) mice. Methods: A2 (−/−) mice and the corresponding wild-type (WT) mice, in groups of 10, were injected i.p. twice (0 and 48 hours later) with IgG from a patient with APS (IgG-APS) or with control IgG (IgG-NHS). Seventy-two hours after the first injection, several procedures were done in each mice: dynamics of thrombus formation (thrombus size), TF function in homogenates of carotid arteries, and c) VCAM-1 expression in the aortas using quantum dot nano crystals and two-photon excitation laser scanning microscopy. In addition, we examined the effect of an anti-A2 antibody on aPL-induced expression of intercellular cell-adhesion molecule (ICAM-1), E-selectin and TF acvitity on cultured endothelial cells (EC). Results: The titers of aCL and anti-β2GPI Abs in the sera of the mice at the time of surgery were medium-high positive in A2 (−/−) mice and in wild type mice injected with IgG-APS. Thrombus sizes were significantly larger in WT mice injected with IgG-APS when compared to similar type of mice treated with IgG-NHS (p=0.003). The size of thrombus in A2 (−/−) mice injected with IgG-APS was significantly smaller than mean thrombus size in WT mice injected with IgG-APS (p:0.0005). However, thrombus size in A2 (−/−) mice was larger in mice injected with IgG-APS when compared to same type of mice treated with control IgG-NHS (p=0.003), indicating a partial but significant abrogation of the thrombogenic effect. TF activity was significantly larger in WT mice treated with IgG-APS when compared to mice injected with IgG-NHS. Importantly, TF activity in carotid arteries homogenates of annexin A2 (−/−) mice injected with IgG-APS was significantly decreased (by 52%) when compared to wild type mice treated with IgG-APS. The expression of VCAM-1 in aorta of annexin A2 (−/−) ex vivo was also significantly reduced compared to LPS-treated mice (positive control) (p= 0.01). Interestingly, anti-A2 antibody significantly decreased aPL-induced expression of ICAM-1, E-sel and TF on cultured EC. Conclusions: Altogether these data indicate for the first time that A2 is involved in vivo pathogenic effects of aPL Abs. These findings may have important implications to devise new targeted and more specific therapeutic approaches to block the pathogenic effects of aPL Abs in patients with APS and SLE.

New Insights Into Factor XI Function: From Biochemistry to Animal Models

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. SCI-20-SCI-20
Author(s):  
David Gailani
Keyword(s):  
Animal Models ◽  
Arterial Thrombosis ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Anticoagulation Therapy ◽  
Factor Ix ◽  
Bleeding Complications ◽  
Contact Activation ◽  
Factor Xi ◽  
Deficient Mice

Abstract Abstract SCI-20 Factor XI (fXI) is the zymogen of an enzyme (fXIa) that contributes to blood coagulation through activation of factor IX (fIX). FXI has structural and mechanistic features that distinguish it from the vitamin K-dependent proteases of coagulation. The protein is a dimer of identical 80 kDa subunits, each containing four apple domains (A1-A4) that form a platform at the base of the trypsin-like protease domain. The apple domains contain binding sites for fIX, platelet receptors, and high molecular weight kininogen. FXI is converted to fXIa by cleavage of a single bond on each subunit, unmasking exosites required for fIX binding. Conversion of fXI to fXIa proceeds through an intermediate with only one activated subunit (1/2-fXIa). 1/2-fXIa, and monomeric forms of fXIa, activate fIX in a manner similar to fully activated fXIa, indicating each subunit functions as a complete enzyme. The importance of the dimeric structure of fXI is not clear at this point. It may facilitate activation, or allow fXIa to bind simultaneously to fIX and a surface (a platelet for example) at a wound site. Congenital fXI deficiency is associated with a variable propensity to bleed excessively after trauma to certain tissues. Symptoms are usually milder than in fIX deficiency (hemophilia B), and many affected individuals are asymptomatic. In the cascade-waterfall model of coagulation, fXI is activated by factor XIIa (fXIIa) during a process called contact activation. However, current models often omit contact activation, because fXII deficiency is not associated with abnormal hemostasis. Thrombin activates fXI, providing an explanation for normal hemostasis in fXII deficiency. In contrast to its modest role in hemostasis, fXI may serve an important role in thromboembolic diseases. High fXI levels are a risk factor for arterial and venous thrombosis in humans; and deficiency or inhibition of fXI confers resistance to thrombosis in animal models. FXI deficient mice are as resistant to arterial thrombosis as fIX deficient mice, or wild type mice treated with a supra-therapeutic dose of heparin. In arterial thrombosis models in mice, rabbits and baboons, lack of fXI activity results in instability of platelet rich thrombi, preventing vessel occlusion. FXI deficiency also prolongs survival and lessens the severity of disseminated intravascular coagulation in a mouse polymicrobial sepsis model. Interestingly, mice with combined deficiencies of fXI and fIX are more resistant to arterial thrombus formation than mice deficient in only one of these proteins, indicating fXIa has proteolytic targets other than fIX. The observation that fXII deficient mice are resistant to arterial thrombosis suggests that activation of fXI by contact activation, while unnecessary for hemostasis, contributes to thrombin generation in some pathologic processes. If the observations in mice apply to thromboembolism in humans, then fXIa and/or fXIIa may be excellent targets for novel antithrombotic strategies. In contrast to drugs such as heparin and warfarin, agents targeting fXIa or fXIIa would likely be associated with relatively few bleeding complications, and could be employed in clinical situations where anticoagulation therapy is currently contraindicated. Disclosures: No relevant conflicts of interest to declare.

Effects of Soluble Domain 1 of Apolipoprotein ER2′ (BD1 apoER2′) on Pathogenic Effects of a Dimer of β2glycoprotein I (β2GPI) In Vivo.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3620-3620
Author(s):  
Silvia S. Pierangeli ◽  
Zurina Romay-Penabad ◽  
R.T. Urbanus ◽  
Guadalupe Montiel-Manzano ◽  
M.T. Pennings ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Carotid Artery ◽  
Platelet Activation ◽  
Platelet Rich Plasma ◽  
Femoral Vein ◽  
Clinical Manifestations ◽  
Peritoneal Macrophages ◽  
Target Cells ◽  
Chromogenic Assay

Abstract Background: It has been shown that endothelial cell (EC) activation and tissue factor (TF) upregulation in EC and monocytes and platelet activation by anti-β2glycoprotein I (aβ2GPI) antibodies leads to a prothrombotic state. However, the receptor recognized by aβ2GPI Abs in target cells is not known. It has been demonstrated that dimers of β2GPI mimic the effects of β2GPI-aβ2GPI complexes in that they increased platelet adhesion to collagen and that these dimers bind to apolipoprotein ER2′ (apoER2′) in platelets. Here, we examined the effects of a dimeric form of β2GPI on thrombosis, on platelet activation and TF activity in vivo in mice. The effects of soluble recombinant binding domain 1 (BD1) of apoER2′ were also studied. Methods: We treated CD1 mice with 50 μg/mL (i.p) recombinant dimeric β2GPI or with recombinant monomeric β2GPI twice at 0 and 48 hours later. Some mice were infused i.p. with 40 μg of BD1. The size of an induced thrombus in the femoral vein of the mice was examined as described elsewhere 72 hours after the first injection. TF activity was determined using a chromogenic assay in homogenates of carotid arteries, and in peritoneal cells of mice. Platelet aggregation was determined by aggregometry in mouse platelet rich plasma. Results: In vivo, dimers of β2GP1 increased significantly the size of the induced thrombi, TF activity in carotid artery homogenates, in peritoneal macrophages and platelet aggregation, when compared to mice treated with control protein. (Table). These effects were significantly diminished by pre-treatment of the mice with BD1apoER2′. Conclusions: Thus, when β2GPI is dimerised, it can induce thrombosis, TF and platelet activation in mice independently of the presence of antibodies. The data also indicate that the binding of dimerised β2GPI to target cells may involve apoER2′ since the effects observed were ameliorated by BD1 apoER2′. These findings may be important in understanding the pathogenic mechanisms of thrombosis in Antiphospholipid Syndrome (APS) and in designing new modalities to prevent/ameliorate clinical manifestations of APS. Treatment Thrombus size (μm2) TF in carotid artery (pM/mg/ml) TF macrophages (pM/mg/ml) Platelet aggregation (%) Dimer 3129±562 346 ± 24 187 ± 36 56 dimer + BD1 533 ± 148 123 ± 15 34 ± 26 23 control monomer 552 ± 79 238 ± 12 42 ± 25 10

Antithrombotic Effects and Bleeding Time Prolongation with Synthetic Platelet GPIIb/llla Inhibitors in Animal Models of Platelet-Mediated Thrombosis

1994 ◽  
Vol 71 (01) ◽  
pp. 095-102 ◽  
Author(s):  
Désiré Collen ◽  
Hua Rong Lu ◽  
Jean-Marie Stassen ◽  
Ingrid Vreys ◽  
Tsunehiro Yasuda ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Bleeding Time ◽  
Bolus Injection ◽  
Cell Injury ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Femoral Vein ◽  
Thrombotic Occlusion ◽  
Antithrombotic Effects

SummaryCyclic Arg-Gly-Asp (RGD) containing synthetic peptides such as L-cysteine, N-(mercaptoacetyl)-D-tyrosyl-L-arginylglycyl-L-a-aspartyl-cyclic (1→5)-sulfide, 5-oxide (G4120) and acetyl-L-cysteinyl-L-asparaginyl-L-prolyl-L-arginyl-glycyl-L-α-aspartyl-[0-methyltyrosyl]-L-arginyl-L-cysteinamide, cyclic 1→9-sulfide (TP9201) bind with high affinity to the platelet GPIIb/IIIa receptor.The relationship between antithrombotic effect, ex vivo platelet aggregation and bleeding time prolongation with both agents was studied in hamsters with a standardized femoral vein endothelial cell injury predisposing to platelet-rich mural thrombosis, and in dogs with a carotid arterial eversion graft inserted in the femoral artery. Intravenous administration of G4120 in hamsters inhibited in vivo thrombus formation with a 50% inhibitory bolus dose (ID50) of approximately 20 μg/kg, ex vivo ADP-induccd platelet aggregation with ID50 of 10 μg/kg, and bolus injection of 1 mg/kg prolonged the bleeding time from 38 ± 9 to 1,100 ± 330 s. Administration of TP9201 in hamsters inhibited in vivo thrombus formation with ID50 of 30 μg/kg, ex vivo platelet aggregation with an ID50 of 50 μg/kg and bolus injection of 1 mg/kg did not prolong the template bleeding time. In the dog eversion graft model, infusion of 100 μg/kg of G4120 over 60 min did not fully inhibit platelet-mediated thrombotic occlusion but was associated with inhibition of ADP-induccd ex vivo platelet aggregation and with prolongation of the template bleeding time from 1.3 ± 0.4 to 12 ± 2 min. Infusion of 300 μg/kg of TP9201 over 60 min completely prevented thrombotic occlusion, inhibited ex vivo platelet aggregation, but was not associated with prolongation of the template bleeding time.TP9201, unlike G4120, inhibits in vivo platelet-mediated thrombus formation without associated prolongation of the template bleeding time.

Continuous Quantitative Monitoring of Mural, Platelet-Dependent, Thrombus Kinetics in the Crushed Rat Femoral Vein

1991 ◽  
Vol 65 (04) ◽  
pp. 425-431 ◽  
Author(s):  
F Stockmans ◽  
H Deckmyn ◽  
J Gruwez ◽  
J Vermylen ◽  
R Acland
Keyword(s):  
Thrombus Formation ◽  
Femoral Vein ◽  
Maximum Size ◽  
Digital Analysis ◽  
Video Recordings ◽  
Quantitative Monitoring ◽  
Set Up ◽  
Kinetics Of ◽  
Quantitative Nature

SummaryA new in vivo method to study the size and dynamics of a growing mural thrombus was set up in the rat femoral vein. The method uses a standardized crush injury to induce a thrombus, and a newly developed transilluminator combined with digital analysis of video recordings. Thrombi in this model formed rapidly, reaching a maximum size 391 ± 35 sec following injury, after which they degraded with a half-life of 197 ± 31 sec. Histological examination indicated that the thrombi consisted mainly of platelets. The quantitative nature of the transillumination technique was demonstrated by simultaneous measurement of the incorporation of 111In labeled platelets into the thrombus. Thrombus formation, studied at 30 min interval in both femoral veins, showed satisfactory reproducibility overall and within a given animalWith this method we were able to induce a thrombus using a clinically relevant injury and to monitor continuously and reproducibly the kinetics of thrombus formation in a vessel of clinically and surgically relevant size

scholarly journals Mice Lacking the Inhibitory Collagen Receptor LAIR-1 Exhibit a Mild Thrombocytosis and Hyperactive Platelets

2017 ◽  
Vol 37 (5) ◽  
pp. 823-835 ◽  
Author(s):  
Christopher W. Smith ◽  
Steven G. Thomas ◽  
Zaher Raslan ◽  
Pushpa Patel ◽  
Maxwell Byrne ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Thrombus Formation ◽  
Physiological Role ◽  
Src Family Kinase ◽  
Glycoprotein Vi ◽  
Collagen Receptor ◽  
Deficient Mice

Objective— Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is a collagen receptor that belongs to the inhibitory immunoreceptor tyrosine-based inhibition motif–containing receptor family. It is an inhibitor of signaling via the immunoreceptor tyrosine-based activation motif–containing collagen receptor complex, glycoprotein VI-FcRγ-chain. It is expressed on hematopoietic cells, including immature megakaryocytes, but is not detectable on platelets. Although the inhibitory function of LAIR-1 has been described in leukocytes, its physiological role in megakaryocytes and in particular in platelet formation has not been explored. In this study, we investigate the role of LAIR-1 in megakaryocyte development and platelet production by generating LAIR-1–deficient mice. Approach and Results— Mice lacking LAIR-1 exhibit a significant increase in platelet counts, a prolonged platelet half-life in vivo, and increased proplatelet formation in vitro. Interestingly, platelets from LAIR-1–deficient mice exhibit an enhanced reactivity to collagen and the glycoprotein VI–specific agonist collagen-related peptide despite not expressing LAIR-1, and mice showed enhanced thrombus formation in the carotid artery after ferric chloride injury. Targeted deletion of LAIR-1 in mice results in an increase in signaling downstream of the glycoprotein VI–FcRγ-chain and integrin αIIbβ3 in megakaryocytes because of enhanced Src family kinase activity. Conclusions— Findings from this study demonstrate that ablation of LAIR-1 in megakaryocytes leads to increased Src family kinase activity and downstream signaling in response to collagen that is transmitted to platelets, rendering them hyper-reactive specifically to agonists that signal through Syk tyrosine kinases, but not to G-protein–coupled receptors.

Effects of bafilomycin A1 on cytosolic pH of sheep alveolar and peritoneal macrophages: evaluation of the pH-regulatory role of plasma membrane V-ATPases.

1995 ◽  
Vol 198 (8) ◽  
pp. 1711-1715 ◽  
Author(s):  
T A Heming ◽  
D L Traber ◽  
F Hinder ◽  
A Bidani
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Initial Rate ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Bafilomycin A1 ◽  
Atpase Inhibitor ◽  
Cytosolic Ph ◽  
Phi Regulation

The role of plasma membrane V-ATPase activity in the regulation of cytosolic pH (pHi) was determined for resident alveolar and peritoneal macrophages (m theta) from sheep. Cytosolic pH was measured using 2',7'-biscarboxyethyl-5,6-carboxyfluorescein (BCECF). The baseline pHi of both cell types was sensitive to the specific V-ATPase inhibitor bafilomycin A1. Bafilomycin A1 caused a significant (approximately 0.2 pH units) and rapid (within seconds) decline in baseline pHi. Further, bafilomycin A1 slowed the initial rate of pHi recovery (dpHi/dt) from intracellular acid loads. Amiloride had no effects on baseline pHi, but reduced dpHi/dt (acid-loaded pHi nadir &lt; 6.8) by approximately 35%. Recovery of pHi was abolished by co-treatment of m theta with bafilomycin A1 and amiloride. These data indicate that plasma membrane V-ATPase activity is a major determinant of pHi regulation in resident alveolar and peritoneal m theta from sheep. Sheep m theta also appear to possess a Na+/H+ exchanger. However, Na+/H+ exchange either is inactive or can be effectively masked by V-ATPase-mediated H+ extrusion at physiological pHi values.

Local delivery of soluble platelet collagen receptor glycoprotein VI inhibits thrombus formation in vivo

2006 ◽  
Vol 95 (05) ◽  
pp. 763-766 ◽  
Author(s):  
Andreas Bültmann ◽  
Christian Herdeg ◽  
Zhongmin Li ◽  
Götz Münch ◽  
Christine Baumgartner ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Vascular Injury ◽  
Carotid Arteries ◽  
Thrombus Formation ◽  
Critical Role ◽  
Local Delivery ◽  
Computer Assisted ◽  
Glycoprotein Vi ◽  
Collagen Receptor

SummaryPlatelet-mediated thrombus formation at the site of vascular injury isa major trigger for thrombo-ischemic complications after coronary interventions. The platelet collagen receptor glycoprotein VI (GPVI) plays a critical role in the initiation of arterial thrombus formation. Endothelial denudation of the right carotid artery in rabbits was induced through balloon injury. Subsequently, local delivery of soluble, dimeric fusion protein of GPVI (GPVI-Fc) (n=7) or control Fc (n=7) at the site of vascular injury was performed with a modified double-balloon drugdelivery catheter.Thrombus area within the injured carotid artery was quantified using a computer-assisted image analysis and was used as index of thrombus formation.The extent of thrombus formation was significantly reduced in GPVI-Fc- compared with control Fc-treated carotid arteries (relative thrombus area, GPVI-Fc vs. Fc: 9.3 ± 4.2 vs. 2.3 ± 1.7, p<0.001). Local delivery of soluble GPVI resulted in reduced thrombus formation after catheter-induced vascular injury.These data suggest a selective pharmacological modulation of GPVI-collagen interactions to be important for controlling onset and progression of pathological arterial thrombosis, predominantly or even exclusively at sites of injured carotid arteries in the absence of systemic platelet therapy.

scholarly journals Toll-Like Receptor 2 Controls the Gamma Interferon Response to Francisella tularensis by Mouse Liver Lymphocytes

2007 ◽  
Vol 75 (11) ◽  
pp. 5338-5345 ◽  
Author(s):  
Kee-Jong Hong ◽  
Jason R. Wickstrum ◽  
Hung-Wen Yeh ◽  
Michael J. Parmely
Keyword(s):  
Francisella Tularensis ◽  
Cell Types ◽  
Gamma Interferon ◽  
Interferon Response ◽  
Interleukin 12 ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Ifn Γ ◽  
Deficient Mice

ABSTRACT The production of gamma interferon (IFN-γ) is a key step in the protective innate immune response to Francisella tularensis. Natural killer cells and T cells in the liver are important sources of this cytokine during primary F. tularensis infections, and interleukin-12 (IL-12) appears to be an essential coactivating cytokine for hepatic IFN-γ expression. The present study was undertaken to determine whether or not macrophages (Mφ) or dendritic cells (DC) provide coactivating signals for the liver IFN-γ response in vitro, whether IL-12 mediates these effects, and whether Toll-like receptor (TLR) signaling is essential to induce this costimulatory activity. Both bone marrow-derived Mφ and DC significantly augmented the IFN-γ response of F. tularensis-challenged liver lymphocytes in vitro. While both cell types produced IL-12p40 in response to F. tularensis challenge, only DC secreted large quantities of IL-12p70. DC from both IL-12p35-deficient and TLR2-deficient mice failed to produce IL-12p70 and did not costimulate liver lymphocytes for IFN-γ production in response to viable F. tularensis organisms. Conversely, liver lymphocytes from TLR2-deficient mice cocultured with wild-type accessory cells produced IFN-γ at levels comparable to those for wild-type hepatic lymphocytes. These findings indicate that TLR2 controls hepatic lymphocyte IFN-γ responses to F. tularensis by regulating DC IL-12 production. While Mφ also coinduced hepatic IFN-γ production in response to F. tularensis, they did so in a fashion less dependent on TLR2.

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