scholarly journals Antiadhesive effect of fibrinogen: a safeguard for thrombus stability

Blood ◽  
2006 ◽  
Vol 109 (4) ◽  
pp. 1541-1549 ◽  
Author(s):  
Valeryi K. Lishko ◽  
Timothy Burke ◽  
Tatiana Ugarova
Keyword(s):  
Wound Healing ◽  
Vessel Wall ◽  
Potent Inhibitor ◽  
Leukocyte Adhesion ◽  
Fibrin Clot ◽  
Flow Conditions ◽  
High Concentration ◽  
Fibrin Gel ◽  
Wall Injury

Abstract The recruitment of phagocytic leukocytes to sites of vessel wall injury plays an important role in thrombus dissolution by proteases elaborated on their adhesion. However, leukocyte adhesion to the fibrin clot can be detrimental at the early stages of wound healing when hemostatic plug integrity is critical for preventing blood loss. Adhesion of circulating leukocytes to the insoluble fibrin(ogen) matrix is mediated by integrins and occurs in the presence of a high concentration of plasma fibrinogen. In this study, the possibility that soluble fibrinogen could protect fibrin from excessive adhesion of leukocytes was examined. Fibrinogen was a potent inhibitor of adhesion of U937 monocytoid cells and neutrophils to fibrin gel and immobilized fibrin(ogen). An investigation of the mechanism by which soluble fibrinogen exerts its influence on leukocyte adhesion indicated that it did not block integrins but rather associated with the fibrin(ogen) substrate. Consequently, leukocytes that engage fibrinogen molecules loosely bound to the surface of fibrin(ogen) matrix are not able to consolidate their grip on the substrate; subsequently, cells detach. This conclusion is based on the evidence obtained in adhesion studies using various cells and performed under static and flow conditions. These findings reveal a new role of fibrinogen in integrin-mediated leukocyte adhesion and suggest that this mechanism may protect the thrombus from premature dissolution.

Evidence That Fibrinogen Inhibits Leukocyte Adhesion to Fibrin Clot and Immobilized Fibrinogen by Binding to the Substrate but Not to Integrins.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2631-2631
Author(s):  
Valeryi K. Lishko ◽  
Tatiana P. Ugarova
Keyword(s):  
Leukocyte Adhesion ◽  
Fibrin Clot ◽  
Plasma Fibrinogen ◽  
Flow Conditions ◽  
Fibrin Gel ◽  
Surface Receptors ◽  
High Concentrations ◽  
Adhesive Interactions ◽  
Adhesive Effect

Abstract The recruitment of phagocytic leukocytes to sites of injured vessel wall plays an important role in thrombus remodeling during normal vascular repair and in the pathophysiology of thrombosis. Fibrin and fibrinogen, present in the thrombus, are potent adhesive substrates for neutrophils and monocytes. They support cellular attachment by binding cell surface receptors that belong to the β2 subfamily of integrins. Adhesive interactions of neutrophils and monocytes with polymerized fibrin and insoluble fibrinogen matrix in vivo occur in the presence of high concentrations of circulating plasma fibrinogen (~2–4 mg/ml). One important property of fibrinogen that would have a major bearing on leukocyte adhesion is its capacity to form complexes with fibrin. Therefore, by virtue of its binding to the fibrin clot and/or immobilized fibrinogen, soluble plasma fibrinogen can influence leukocyte adhesion to these substrates. In this study, the possibility that soluble fibrinogen could protect fibrin from adhesion of leukocytes was examined. Fibrinogen was an efficient inhibitor of adhesion of U937 monocytoid cells and neutrophils to fibrin gel and immobilized fibrin(ogen). An investigation of the mechanism by which fibrinogen exerts its influence on leukocyte adhesion indicated that it did not block integrins but rather associated non-covalently and weakly with fibrin(ogen) substrates. Consequently, leukocyte integrins that engage fibrinogen molecules loosely bound to the fibrin(ogen) matrix are not able to consolidate their grip on the substrate; subsequently, cells detach. This conclusion is based on the evidence obtained in adhesion studies using various β2-integrin bearing cells and performed under static and flow conditions. Furthermore, surface plasmon resonance studies, undertaken to determine the Kd of fibrinogen-fibrin interactions under flow conditions, indicated that fibrinogen formed complexes with fibrin(ogen) with micromolar affinities. Thus, these findings reveal a new role of fibrinogen in integrin-mediated leukocyte adhesion. They also imply that the anti-adhesive effect of fibrinogen may protect the thrombus from an excessive leukocyte accumulation and premature dissolution at the early stages of wound healing when hemostatic plug integrity is critical for preventing blood loss.

Control of Platelet Adhesion by Rigidity Sensing at the Surface of Fibrin Clot.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3906-3906
Author(s):  
Nataly P. Podolnikova ◽  
Benjamin Bowen ◽  
Valeryi K. Lishko ◽  
Andriy V. Podolnikov ◽  
Tatiana Ugarova
Keyword(s):  
Platelet Adhesion ◽  
Leukocyte Adhesion ◽  
Thrombus Formation ◽  
Focal Adhesions ◽  
Fibrin Clot ◽  
Fibrin Gel ◽  
Vessel Occlusion ◽  
Leukocyte Integrins ◽  
Low Concentrations ◽  
Platelet Spreading

Abstract Thrombus formation at sites of vascular injury must occur quickly to reduce blood loss, but is carefully controlled to limit vessel occlusion. Arrest of bleeding is mediated by adhesion and aggregation of platelets and the formation of the fibrin clot. While the interactions responsible for platelet adhesion and thrombus growth have been extensively researched, the mechanisms that limit platelet adhesion are not clear. We have previously demonstrated that plasma fibrinogen is a potent inhibitor of integrin-mediated leukocyte adhesion to fibrin clots and surface-bound fibrinogen, and have provided evidence that fibrinogen reduces cell adhesion by binding to the surface of fibrin rather than blocking leukocyte integrins. Accordingly, cells that engage fibrinogen molecules loosely bound to fibrin (soft substrate) are not able to consolidate their grip on the surface; subsequently, cells detach. Conversely, cells that adhere to the naked fibrin clot (rigid substrate) adhere firmly. Since fibrin and immobilized fibrinogen support platelet adhesion, we examined the effect of soluble fibrinogen on integrin αIIbβ3-mediated adhesion. We show that the anti-adhesive fibrinogen layer formed on the surface of fibrin inhibits platelet adhesion. We also demonstrate that fibrinogen immobilized on plastic at high densities (>20 μg/ml) supports weak platelet adhesion whereas at low concentrations (∼2 μg/ml) it is highly adhesive. An investigation of the mechanism underlying differential platelet adhesion indicates that platelet adhesion to rigid substrates (low-density fibrinogen and naked fibrin gel) induces much stronger phosphorylation of FAK and Syk kinases than that to soft substrates (high-density fibrinogen and fibrin exposed to soluble fibrinogen). Furthermore, the rigid, but not the soft substrates induce recruitment of signaling molecules talin and skelemin to αIIbβ3-containing focal adhesions. Consistent with their limited ability to induce sufficient signaling, soft substrates do not support platelet spreading. These data suggest that circulating fibrinogen prevents stable platelet adhesion by modifying the mechanical properties of the fibrin clot’s surface which results in reduced force generation and insufficient signaling.

Fibronectin provides a conduit for fibroblast transmigration from collagenous stroma into fibrin clot provisional matrix

1997 ◽  
Vol 110 (7) ◽  
pp. 861-870 ◽  
Author(s):  
D. Greiling ◽  
R.A. Clark
Keyword(s):  
Wound Healing ◽  
In Vitro Model ◽  
Collagen Gel ◽  
Fibrin Clot ◽  
Dependent Manner ◽  
Fibrin Gel ◽  
Concentration Dependent Manner ◽  
Vitro Model ◽  
Early Wound

After injury, the wound space is filled with a fibrin/fibronectin clot containing growth factors released by platelets and monocytes. In response to these factors, fibroblasts migrate into the fibrin clot and contribute to the formation of granulation tissue. The functional mechanisms allowing fibroblasts to leave the collagenous matrix of normal connective tissue and invade the provisional matrix of the fibrin clot have not been fully defined. To investigate these mechanisms we established a new in vitro model which simulates specific aspects of early wound healing, that is, the migration of fibroblasts from a three-dimensional collagen matrix into a fibrin clot. This transmigration could be induced by physiological concentrations of platelet releasate or platelet-derived growth factor BB (PDGF-BB) in a concentration-dependent manner. At 24 hours irradiated fibroblasts invaded the fibrin gel almost as well as non-irradiated cells, indicating that transmigration was independent of proliferation. Plasminogen and its activators appear to be necessary for invasion of the fibrin clot since protease inhibitors decreased the amount of migration. These serine proteases, however, were not necessary for exit from the collagen gel as fibroblasts migrated out of the collagen gel onto a surface coated with fibrin fibrils even in the presence of inhibitors. Removal of fibronectin (FN) from either the collagen gel or the fibrin gel markedly decreased the number of migrating cells, suggesting that FN provides a conduit for transmigration. Cell movement in the in vitro model was inhibited by RGD peptide, and by monoclonal antibodies against the subunits of the alpha5 beta1 and alpha v beta3 integrin receptor. Thus, the functional requirements for fibroblast transmigration from collagen-rich to fibrin-rich matrices, such as occurs in early wound healing, have been partially defined using an in vitro paradigm of this important biologic process.

Platelet Associated Fibrinogen and ICAM-2 Induce Firm Adhesion of Neutrophils under Flow Conditions

1998 ◽  
Vol 80 (09) ◽  
pp. 443-448 ◽  
Author(s):  
P. H. M. Kuijper ◽  
H. I. Gallardo Torres ◽  
J.-W. J. Lammers ◽  
J. J. Sixma ◽  
L. Koenderman ◽  
...  
Keyword(s):  
Vessel Wall ◽  
High Shear ◽  
Flow Conditions ◽  
Shear Rates ◽  
Β2 Integrin ◽  
High Shear Rates ◽  
Wall Injury ◽  
Blocking Antibodies ◽  
Low Shear

SummarySurface-bound platelets support selectin-mediated rolling and β2-integrin-mediated firm adhesion of neutrophils (PMN) under flow conditions. We examined which ligands on platelets mediate this firm adhesion. Surface-bound platelets express ICAM-2 and GPIIbIIIa-bound fibrinogen, which are ligands for LFA-1 and MAC-1. In a well defined model for vessel wall injury, blood from an afibrinogenemic patient was perfused over ECM-coated coverslips to obtain fibrinogen-free platelet surfaces. At high shear rates, PMN-adhesion to fibrinogen-free platelet surfaces decreased compared to fibrinogen-containing controls. Under these conditions, firm adhesion and not rolling was blocked demonstrating the importance of fibrinogen in this process. In addition, MAC-1 and LFA-1 on PMN and ICAM-2 on platelets played a role in firm adhesion; the effect of blocking antibodies was most evident at high shear. The effects of fibrinogen depletion and ICAM-2 blocking were additive. In conclusion, multiple redundant ligands, like ICAM-2 and fibrinogen, induce firm and shear resistant PMN adhesion to platelets under flow conditions. Individually these ligands become critical at higher shear. Blocking of two or more interactions also interferes with low shear adhesion.

scholarly journals Platelet-dependent primary hemostasis promotes selectin- and integrin- mediated neutrophil adhesion to damaged endothelium under flow conditions

Blood ◽  
1996 ◽  
Vol 87 (8) ◽  
pp. 3271-3281 ◽  
Author(s):  
PH Kuijper ◽  
HI Gallardo Torres ◽  
JA van der Linden ◽  
JW Lammers ◽  
JJ Sixma ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Vessel Wall ◽  
Platelet Adhesion ◽  
Leukocyte Adhesion ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Neutrophil Adhesion ◽  
Shear Stresses ◽  
Flow Conditions

Co-localization of blood platelets and granulocytes at sites of hemostasis and inflammation has triggered an intense interest in possible interactions between these cellular processes and induction of vessel wall injury. Leukocyte adhesion to endothelial cells decreases with increasing shear and is dependent on an initial rolling phase mediated by selectins. We hypothesized that flow-dependent platelet adhesion at an injured vessel wall will lead to P-selectin expression by platelets, thus mediating leukocyte co-localization. A perfusion chamber was used in which flowing whole blood induced platelet adhesion to a subendothelial matrix (ECM) of cultured human umbilical vein endothelial cells (HUVEC). We compared neutrophil (polymorphonuclear leukocyte [PMN]) interactions with HUVEC and their ECM with and without adhered platelets. PMNs adhered predominantly to ECM-adhered platelets and not to endothelial cells. ECM alone did not support PMN adhesion under flow conditions. PMN adhesion to unstimulated HUVEC was only substantial at low shear (up to 200 cells/mm2 at shear stress 80 mPa). In marked contrast, PMN adhesion to ECM-adhered platelets was dramatically increased, and adhesion was demonstrated at much higher shear stress (up to 640 mPa). Studies with specific antibodies showed that the platelet-dependent neutrophil adhesion was selectin-mediated. Inhibition of P-selectin caused a marked inhibition of adhesion at high shear stress, whereas the role of leukocyte L-selectin was less pronounced. beta2-Integrin-blocking antibodies inhibited static neutrophil adhesion. fMLP induced L-selectin shedding from leukocytes, resulting in decreased leukocyte adhesion. In conclusion, platelet- dependent hemostasis at the ECM appears to be a powerful intermediate in neutrophil-vessel wall interactions at shear stresses that normally do not allow neutrophil adhesion to intact endothelium.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

Gene Induction in Vessel Wall Injury

1993 ◽  
Vol 70 (01) ◽  
pp. 180-183 ◽  
Author(s):  
Mark B Taubman
Keyword(s):  
Vessel Wall ◽  
Gene Induction ◽  
Wall Injury

Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

1976 ◽  
Vol 36 (01) ◽  
pp. 037-048 ◽  
Author(s):  
Eric P. Brass ◽  
Walter B. Forman ◽  
Robert V. Edwards ◽  
Olgierd Lindan
Keyword(s):  
Particle Size ◽  
Induction Period ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Appreciable Amount ◽  
Buffer System ◽  
Homeostatic Mechanism ◽  
Fibrin Formation ◽  
Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

The Effects of Heparin and Annexin V on Fibrin Accretion after Injury in the Jugular Veins of Rabbits

1993 ◽  
Vol 69 (03) ◽  
pp. 227-230 ◽  
Author(s):  
J Van Ryn-McKenna ◽  
H Merk ◽  
T H Müller ◽  
M R Buchanan ◽  
W G Eisert
Keyword(s):  
Vessel Wall ◽  
Thrombin Generation ◽  
Antithrombin Iii ◽  
Specific Effect ◽  
Annexin V ◽  
Inhibitory Effect ◽  
Jugular Veins ◽  
Prothrombinase Complex ◽  
Wall Injury

SummaryWe compared the relative abilities of unfractionated heparin and annexin V to prevent fibrin accretion onto injured jugular veins in vivo. Heparin was used to accelerate the inhibition of thrombin by antithrombin III, and annexin V was used to inhibit the assembly of the prothrombinase complex on phospholipid surfaces, thereby blocking thrombin generation. Rabbit jugular veins were isolated in situ, a 2 cm segment was injured by perfusing it with air, and then blood flow was re-established. Five minutes later, each rabbit was injected with heparin (20 U/kg) or annexin V (0.3 mg/kg) and then with 125I-fibrinogen. The amount of 125I-fibrin accumulation onto each injured vessel wall segment was measured 4 h later. Each injured vessel was completely deendothelialized as a result of the air perfusion as demonstrated by electron microscopy. 125I-fibrin accretion onto the injured jugular veins was enhanced 2.4-fold as compared to the uninjured veins in sham-operated animals. Heparin treatment did not reduce fibrin accretion, whereas, annexin V treatment decreased fibrin accretion by 60%, p <0.05. This latter effect was achieved without sustained circulating anticoagulation. Additional experiments confirmed that the inhibitory effect of annexin V on fibrin accretion was associated with a surface specific effect, since more annexin V bound to the injured jugular vein segments as compared to the non-injured jugular veins. We conclude that, i) mild vessel wall injury (selective de-endothelialization) in veins results in a thrombogenic vessel wall; ii) the thrombogenecity of which is not inhibited by prophylactic doses of heparin; but iii) is inhibited by annexin V, which binds to injured vessel wall surface, and inhibits thrombin generation independently of antithrombin III.

Tridegin, a Novel Peptidic Inhibitor of Factor XIIIa from the Leech, Haementeria ghilianii, Enhances Fibrinolysis In Vitro

1997 ◽  
Vol 77 (05) ◽  
pp. 0959-0963 ◽  
Author(s):  
Lisa Seale ◽  
Sarah Finney ◽  
Roy T Sawyer ◽  
Robert B Wallis
Keyword(s):  
Potent Inhibitor ◽  
Platelet Rich Plasma ◽  
Factor Xiiia ◽  
Cross Linking ◽  
Fibrinolytic Enzymes ◽  
Small Polypeptide ◽  
Tissue Plasminogen ◽  
Protein Cross Linking

SummaryTridegin is a potent inhibitor of factor Xllla from the leech, Haementeria ghilianii, which inhibits protein cross-linking. It modifies plasmin-mediated fibrin degradation as shown by the absence of D-dimer and approximately halves the time for fibrinolysis. Plasma clots formed in the presence of Tridegin lyse more rapidly when either streptokinase, tissue plasminogen activator or hementin is added 2 h after clot formation. The effect of Tridegin is markedly increased if clots are formed from platelet-rich plasma. Platelet-rich plasma clots are lysed much more slowly by the fibrinolytic enzymes used and if Tridegin is present, the rate of lysis returns almost to that of platelet- free clots. These studies indicate the important role of platelets in conferring resistance to commonly used fibrinolytic enzymes and suggest that protein cross-linking is an important step in this effect. Moreover they indicate that Tridegin, a small polypeptide, may have potential as an adjunct to thrombolytic therapy.

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