fibrin and Infections

Plasminogen is an abundant plasma protein that exists in various zymogenic forms. Plasmin, the proteolytically active form of plasminogen, is known for its essential role in fibrinolysis. To date, therapeutic targeting of the fibrinolytic system has been for 2 purposes: to promote plasmin generation for thromboembolic conditions or to stop plasmin to reduce bleeding. However, plasmin and plasminogen serve other important functions, some of which are unrelated to fibrin removal. Indeed, for >40 years, the antifibrinolytic agent tranexamic acid has been administered for its serendipitously discovered skin-whitening properties. Plasmin also plays an important role in the removal of misfolded/aggregated proteins and can trigger other enzymatic cascades, including complement. In addition, plasminogen, via binding to one of its dozen cell surface receptors, can modulate cell behavior and further influence immune and inflammatory processes. Plasminogen administration itself has been reported to improve thrombolysis and to accelerate wound repair. Although many of these more recent findings have been derived from in vitro or animal studies, the use of antifibrinolytic agents to reduce bleeding in humans has revealed additional clinically relevant consequences, particularly in relation to reducing infection risk that is independent of its hemostatic effects. The finding that many viruses harness the host plasminogen to aid infectivity has suggested that antifibrinolytic agents may have antiviral benefits. Here, we review the broadening role of the plasminogen-activating system in physiology and pathophysiology and how manipulation of this system may be harnessed for benefits unrelated to its conventional application in thrombosis and hemostasis.

Topics: Animals; Antifibrinolytic Agents; Brain; Conjunctivitis; Enzyme Activation; Fibrin; Fibrinolysin; Fibrinolysis; Fibrinolytic Agents; Humans; Immunity; Infections; Inflammation; Mice; Plasminogen; Radiodermatitis; Receptors, Cell Surface; Skin Diseases, Genetic; Thrombosis; Tranexamic Acid; Wound Healing; Wounds and Injuries

As our knowledge of the structure and functions of fibrinogen and fibrin has increased tremendously, several key findings have given some people a superficial impression that the biological and clinical significance of these clotting proteins may be less than earlier thought. Most strikingly, studies of fibrinogen knockout mice demonstrated that many of these mice survive to weaning and beyond, suggesting that fibrin(ogen) may not be entirely necessary. Humans with afibrinogenemia also survive. Furthermore, in recent years, the major emphasis in the treatment of arterial thrombosis has been on inhibition of platelets, rather than fibrin. In contrast to the initially apparent conclusions from these results, it has become increasingly clear that fibrin is essential for hemostasis; is a key factor in thrombosis; and plays an important biological role in infection, inflammation, immunology, and wound healing. In addition, fibrinogen replacement therapy has become a preferred, major treatment for severe bleeding in trauma and surgery. Finally, fibrin is a unique biomaterial and is used as a sealant or glue, a matrix for cells, a scaffold for tissue engineering, and a carrier and/or a vector for targeted drug delivery.

Topics: Animals; Fibrin; Fibrinogen; Hemorrhage; Hemostasis; Humans; Infections; Inflammation; Mice; Mice, Knockout; Wound Healing; Wounds and Injuries

Topics: beta-Thromboglobulin; Biocompatible Materials; Blood Coagulation; Blood Platelets; Cell Adhesion; Fibrin; Humans; Infections; Kidney Failure, Chronic; Leukocytes; Leukopenia; Lymphocyte Activation; Membranes, Artificial; Platelet Activation; Platelet Adhesiveness; Platelet Factor 4; Polymethyl Methacrylate; Renal Dialysis; Respiratory Burst; Thrombin; Thromboxane A2

From the preceding exposition it is now clear that the regulation of monocyte/macrophage PCA is dependent upon a complex network of interacting pathways, some of which amplify the response of the monocyte/macrophage, while others inhibit. In all probability many more will emerge. The construct illustrated in Figure 3, therefore, is a simplified view of the two major stimulatory pathways: the T cell-dependent pathway, activated by immune recognition and mediated by lymphokine(s); and the T cell-independent pathway, activated by direct perturbation of monocytes by such stimuli as LPS. At least 2 or 3 different PCAs can be expressed by monocyte/macrophages from different species, depending upon the anatomic site of the origin of the cell and the types of stimuli imposed. Inhibition of PCA expression is accomplished by at least one set of regulatory lipoproteins, and other inhibitory loops may be found. The result of these multiple interactions is the deposition of fibrin on the cell surface or in the surrounding milieu. It is our belief that this close relationship between coagulation reactions and inflammatory reactions, resulting in fibrin deposition, represents a fundamental host defense designed to delimit the inflammatory response. Nevertheless, the precise role of monocyte procoagulants in vivo remains unclear. A number of potential mechanisms exist for activation of coagulation in both inflammatory and neoplastic disorders, and the finding of enhanced monocyte procoagulant activity by no means establishes its importance in physiologic or, pathosphysiologic responses in vivo. Further studies, possibly with agents capable of specific inhibition of monocyte procoagulants in vivo, will be necessary to define the precise importance of these procoagulants in clinical disorders.

Topics: Animals; Anti-Inflammatory Agents; Antigens; Blood Coagulation; Blood Coagulation Factors; Cell Line; Factor V; Factor VII; Factor X; Factor Xa; Fibrin; Fibrin Fibrinogen Degradation Products; Guinea Pigs; Humans; Hypersensitivity, Delayed; Immunologic Deficiency Syndromes; Infections; Inflammation; Lipopolysaccharides; Macrophages; Mice; Monocytes; Neoplasms; Neutrophils; Rabbits; Rats; T-Lymphocytes; Thromboembolism; Thromboplastin; Warfarin

Topics: Animals; Antibodies; Arteries; Blood Platelets; Capillaries; Coronary Disease; Coronary Vessels; Cortisone; Dogs; Endocarditis; Fibrin; Graft Rejection; Heart Failure; Heart Transplantation; Hemorrhage; Humans; Immunosuppression Therapy; Immunosuppressive Agents; Infections; Kidney Transplantation; Male; Microscopy, Electron; Middle Aged; Myocarditis; Myocardium; Necrosis; Rabbits; Shwartzman Phenomenon; Time Factors; Transplantation Immunology; Transplantation, Homologous

Platelet activation contributes to microvascular thrombosis and organ failure in systemic inflammation. We tested the hypothesis whether anti-platelet drugs might favourably affect outcome in patients at risk for organ failure as well as in a mouse model of endotoxin shock. Two hundred twenty-four consecutive patients who were admitted for community acquired pneumonia over a time period of 5 years to a University Hospital were enrolled; about 20% of whom received anti-platelet drugs (acetylsalicylic acid, thienopyridines) for secondary prevention of cardiovascular disease. Patients with anti-platelet drugs were about 12 years old but did not differ in SOFA score and routine laboratory parameters at admission. Logistic regression and 2 x 2 table analysis in age-matched subgroups indicated that anti-platelet drugs may reduce the need of intensive care treatment (odds ratio (OR) 0.32 [95% confidential interval: 0.10-1.00] and 0.19 [0.04-0.87], respectively). In age-matched subgroups, the use of anti-platelet drugs was also associated with a shorter stay in hospital (13.9 +/- 6.2 vs. 18.2 +/- 10.2 days; p < 0.02). In the animal model Balb/c mice were pre-treated with clopidogrel (added to drinking water) for 4 days prior to intraperitoneal (i.p.) administration of endotoxin (lipopolsaccharide (LPS) from Escherichia coli 0111:B4). Within the first 48 hours after LPS there were no differences between clopidogrel and control animals (n = 26 each) in macro-haemodynamics. However, clopidogrel abolished the LPS-induced drop in platelet count and reduced fibrin deposition in lung tissue. Using DNA microarray technology, we could show that clopidogrel suppressed endotoxin-induced up-regulation of inflammation-relevant genes, including arachidonate-5-lipoxygenase activating protein and leukotriene B4 receptor 1. According to our data a possible benefit of anti-platelet drugs in patients on risk for systemic inflammation and organ failure should be tested in a prospective trial.

Topics: Adult; Aged; Animals; Cell Line; Clopidogrel; Female; Fibrin; Gene Expression Profiling; Hemodynamics; Humans; Infections; Intensive Care Units; Length of Stay; Leukocytes; Lung; Male; Mice; Mice, Inbred BALB C; Middle Aged; Oligonucleotide Array Sequence Analysis; Platelet Activation; Platelet Aggregation Inhibitors; Pneumonia; Retrospective Studies; Shock, Septic; Ticlopidine

Hemostatic parameters were examined before and during 102 courses of chemotherapy in 42 patients with malignant lymphoma with high risk for infection. The white blood cell count was significantly reduced in all patients at days 1 and 3, but significantly increased at days 7 and 9, compared to before chemotherapy. At day 7 of chemotherapy, tissue factor (TF) mRNA levels in leukocytes were significantly increased in all patients, especially those with infection. Plasma concentrations of granulocyte elastase derived-XDP (GE-XDP) levels correlated with D-dimer levels during chemotherapy in patients with malignant lymphoma, suggesting that the elevated D-dimer is fibrin products degraded by granulocyte elastase. GE-XDP, C-reactive protein (CRP), GE-XDP and D-dimer were significantly higher in patients with infection, disseminated intravascular coagulation (DIC) and acute respiratory distress syndrome (ARDS) than those without. In patients with DIC or ARDS, TF mRNA correlated with D-dimer, and GE-XDP correlated with leukocyte count, CRP and D-dimer, suggesting that inflammatory changes due to thrombosis may cause the activation of leukocytes in patients with malignant lymphoma during chemotherapy. Activated leukocytes and granulocyte elastase may elicit a hypercoagulable state and ARDS in patients with malignant lymphoma during chemotherapy.

Topics: Aged; Antineoplastic Agents; C-Reactive Protein; Disseminated Intravascular Coagulation; Female; Fibrin; Fibrin Fibrinogen Degradation Products; Fibrinogen; Hemostasis; Humans; Infections; Leukocyte Count; Leukocyte Elastase; Leukocytes; Lymphoma; Male; Middle Aged; Prospective Studies; Respiratory Distress Syndrome; RNA, Messenger; Thromboplastin; Time Factors

Inflammatory cytokines potently impact hemostatic pathways during infection, but the tissue-specific regulation of coagulation and fibrinolysis complicates studies of the underlying mechanisms.. Here, we describe assays that quantitatively measuring prothrombinase (PTase), protein C-ase (PCase) and plasminogen activator (PA) activities in situ, thereby facilitating studies of tissue-specific hemostasis. Using these assays, we investigate the mechanisms regulating hepatic fibrin deposition during murine toxoplasmosis and the means by which interferon-gamma (IFN-gamma) suppresses infection-stimulated fibrin deposition. We demonstrate that Toxoplasma infection upregulates hepatic PTase, PCase, and PA activity. Wild type and gene-targeted IFN-gamma-deficient mice exhibit similar levels of infection-stimulated PTase activity. By contrast, IFN-gamma-deficiency is associated with increased PCase activity and reduced PA activity during infection. Parallel analyses of hepatic gene expression reveal that IFN-gamma-deficiency is associated with increased expression of thrombomodulin (TM), a key component of the PCase, increased expression of thrombin-activatable fibrinolysis inhibitor (TAFI), a PC substrate, and reduced expression of urokinase PA (u-PA).. These findings suggest that IFN-gamma suppresses infection-stimulated hepatic fibrin deposition by suppressing TM-mediated activation of TAFI, thereby destabilizing fibrin deposits, and concomitantly increasing hepatic u-PA activity, thereby promoting fibrinolysis. We anticipate that further application of these in situ assays will improve our understanding of tissue-specific hemostasis, its regulation by cytokines, and its dysregulation during coagulopathy.

Topics: Animals; Carboxypeptidase B2; Fibrin; Fibrinolysis; Hemostasis; Infections; Interferon-gamma; Liver; Mice; Mice, Knockout; Plasminogen Activators; Thrombomodulin; Thromboplastin; Toxoplasmosis, Animal; Urokinase-Type Plasminogen Activator

Plasma levels of soluble fibrin (SF) were measured in 1184 patients with disseminated intravascular coagulation (DIC) according to Japanese Ministry of Health and Welfare (JMHW) criteria. The usefulness of SF for the diagnosis of DIC was compared with other hemostatic molecular markers. Most hemostatic markers were significantly increased in patients with DIC than in those without DIC. Plasma levels of fibrin and fibrinogen degradation products, thrombin-antihtrombin complex, plasmin-plasmin inhibitor complex, D-dimer, thrombomodulin, and SF levels were also significantly higher in those with pre-DIC than in those without DIC. In classification of overt DIC by International Society of Thrombosis and Haemostasis (ISTH) criteria, most hemostatic markers were significantly increased in patients with overt DIC than in those without overt DIC. Plasma levels of SF 'in patients with DIC were significantly higher than those in patients with pre-DIC, which were significantly higher than in those without DIC. Plasma levels of SF were also significantly higher in patients with overt DIC than in those with non-overt DIC. The correlation between plasma SF levels and DIC score according to JMHW criteria or ISTH criteria was good. Receiver operating characteristic analysis shows that SF was the best marker for the diagnosis of DIC or overt DIC. These findings suggest that plasma SF might be useful marker for the diagnosis of DIC or overt DIC.

Topics: Biomarkers; Disseminated Intravascular Coagulation; Fibrin; Hematologic Neoplasms; Humans; Infections; Platelet Count; Reference Values; Reproducibility of Results; ROC Curve

We evaluated 50 consecutive patients with acute ischemic stroke to assess the prevalence of systemic infection preceding the neurological event. We analyzed the immunohematologic characteristics of patients with and without signs and/or symptoms of a preceding infectious process. Patients were examined less than or equal to 7 days after cerebral infarction and evaluated for fibrinogen, anticardiolipin antibodies, fibrin D-dimer (a fragment of cross-linked fibrin), plasminogen activator inhibitor-1, and protein S. Of the 50 patients, 17 had symptoms of infection beginning less than or equal to 1 month before the stroke (11 had upper respiratory tract infections, three urinary tract infections, two subacute bacterial endocarditis, and one pneumonia). Compared with patients without infection, patients with infection had significant increases in fibrin D-dimer concentration (5.3 +/- 1.1 versus 4.7 +/- 0.9 log-transformed ng/ml, p less than 0.05) and cardiolipin immunoreactivity, IgG isotype (1.8 +/- 1.3 versus 1.1 +/- 0.9 log-transformed phospholipid units, p less than 0.04), and, when studied less than or equal to 2 days after the stroke, increased fibrinogen levels (459 +/- 126 versus 360 +/- 94 mg/dl, p less than 0.05). In conclusion, infection-associated cerebral infarction is common and is associated with substantial immunohematologic abnormalities.

Topics: Adult; Aged; Cardiolipins; Cerebral Infarction; Female; Fibrin; Fibrinogen; Humans; Immunoglobulin G; Immunoglobulin Isotypes; Infections; Male; Middle Aged; Phospholipids

Topics: Aged; Arthritis, Rheumatoid; Blood Cell Count; Blood Platelets; Carbon Radioisotopes; Collagen Diseases; Factor XIII; Female; Fibrin; Fibrinolysis; Heart Failure; Humans; Hypertension, Malignant; Infections; Leukemia; Liver Diseases; Neoplasms; Pulmonary Embolism; Sepsis; Streptokinase

Topics: Aneurysm; Arteries; Blood Vessel Prosthesis; Collagen; Elasticity; Endothelium; Fibrin; Fibroblasts; Fistula; Humans; Infections; Intestinal Fistula; Plastics; Polyethylene Terephthalates; Postoperative Complications; Textiles; Thrombosis; Vascular Diseases

Topics: Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Factor IX; Factor V; Factor VII; Factor VIII; Factor X; Fibrin; Humans; Infections; Kidney Diseases; Phospholipids; Shock, Septic

Topics: Adolescent; Adult; Animals; Antigens; Aortic Valve; Calcinosis; Collagen; Elastic Tissue; Female; Fibrin; Formaldehyde; Humans; Infections; Male; Microscopy, Electron; Middle Aged; Mitral Valve Insufficiency; Stress, Mechanical; Swine; Thrombosis; Tissue Preservation; Transplantation Immunology; Transplantation, Heterologous

Topics: Anemia, Hemolytic; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Blood Transfusion; Child; Diagnosis, Differential; Disseminated Intravascular Coagulation; Factor V; Factor VIII; Fibrin; Fibrinolysis; Hemorrhagic Disorders; Heparin; Hepatitis; Humans; Infections; Pediatrics; Uremia

Topics: Fibrin; Humans; Infections; Infusions, Parenteral; Injections, Intravenous; Penicillins; Time Factors

Topics: Birth Weight; Blood; Blood Coagulation Factors; Cesarean Section; Female; Fibrin; Hemorrhage; Humans; Immunoelectrophoresis; Infant, Newborn; Infant, Newborn, Diseases; Infant, Premature; Infections; Labor Presentation; Labor, Obstetric; Maternal-Fetal Exchange; Pregnancy; Respiratory Distress Syndrome, Newborn; Time Factors; Umbilical Cord

Topics: Endopeptidases; Fibrin; Fibrinolysis; Humans; Infections; Inflammation; Streptodornase and Streptokinase

Topics: Fibrin; Infections

Topics: Blood Sedimentation; Coagulants; Fibrin; Fibrinogen; Hemostatics; Humans; Infections; Mental Disorders; Plasma