thromboplastin and Escherichia-coli-Infections

Review of primate studies of Escherichia coli sepsis and endotoxemia with a reexamination of the rationale for diagnosis and treatment of these multistage disorders.. Animal research and intensive care units in a university medical school.. Cyanocephalus baboons (E. coli) and normal human subjects (endotoxin).. Baboon studies: anti-tissue factor, protein C, endothelial protein C receptor, and anti-tumor necrosis factor antibodies, and active site inhibited factor recombinant VIIa and factor Xa.. This review concerns the primate microvascular endothelial response to inflammatory and hemostatic stress. Studies of the impact of inflammatory and hemostatic stress on this microvasculature have fallen into four categories. First, studies of pure hemostatic stress using factor Xa phospholipid vesicles showed that blockade of protein C as well as protein C plus tissue plasminogen activator produced a severe but transient consumptive and a lethal thrombotic coagulopathy, respectively. These studies showed that the protein C and fibrinolytic systems can work in tandem to regulate even a severe response if the endothelium is not rendered dysfunctional by metabolic or inflammatory factors. Second, studies of compensated (nonlethal) inflammatory stress using E. coli or endotoxin in baboon and human subjects showed that even under minimal stress in which there is no evidence of overt disseminated intravascular coagulation, injury of the endothelium and activation of neutrophils and hemostatic factors are closely associated. This showed that molecular markers of hemostatic activity could be used to detect microvascular endothelial stress (nonovert disseminated intravascular coagulation) in patients who are compensated but at risk. These studies also showed that the compensated response to inflammatory stress could exhibit two stages, each with its unique inflammatory and hemostatic response signature. The first is driven by vasoactive peptides, cytokines, and thrombin, followed 12 to 14 hrs later by a second stage driven by C-reactive protein/complement complexes, tissue factor, and plasminogen activator inhibitor 1 secondary to oxidative stress after reperfusion. Third, studies of uncompensated (lethal) inflammatory stress using E. coli showed that irreversible thrombosis of the microvasculature was not a link in the lethal chain of events even though inhibition of components of the protein C network (protein C and endothelial protein C receptor) converted compensated responses to sublethal E. coli into uncompensated lethal responses. Fourth, these studies also showed that there were variants of the lethal response ranging from capillary leak and shock to recurrent sustained inflammatory disorders. We believe that each of these variants arises from their sublethal counterparts, depending on underlying or modulating host factors operating at the time of challenge. Such underlying conditions range from preexisting microvascular ischemia, reperfusion, and oxidati

Topics: Animals; Cytokines; Disease Models, Animal; Endothelium, Vascular; Endotoxemia; Escherichia coli Infections; Factor VIIa; Factor Xa; Hemostasis; Homeostasis; Humans; Inflammation; Microcirculation; Papio; Protein C; Sepsis; Thrombin; Thromboplastin; Tumor Necrosis Factor-alpha

The baboon model of E. coli sepsis illustrates three concepts with respect to the host response and vascular endothelium. First, the endothelium is the primary target. E. coli sepsis is an acute inflammatory disease of the vascular endothelium. Second, the endothelium is not a passive target. Initially it regulates both the inflammatory and coagulopathic aspects of E. coli sepsis through membrane associated regulatory receptor/plasma protein assemblies including protein C/thrombomodulin, activated protein C/protein S, C4bBP/protein S, tissue factor pathway inhibitor/Xa, antithrombin III/glycosaminoglycans. Third, when overridden by inflammatory events, the endothelium can change its anticoagulant phenotype and mount a massive procoagulant fibrinolytic counter-attack on its luminal side through the expression of tissue factor and release of tissue plasminogen activator. Fourth, again when overridden by inflammatory events, the endothelium can change its antioxidant phenotype and produce a "distal" tissue hypoxia on its abluminal side through induction of free radical generation and peroxidation of mitochondrial lipid membranes of those tissues with high metabolic rates. It has become increasingly clear that the so-called anticoagulant systems which act on the proximal factors of the clotting cascade (protein C, TFPI, AT-III, PGI2) also attenuate the amplification of the inflammatory response. Aspects of the mechanism by which this occurs are coming to light. This includes the attenuation of Il-6 response by TFPI and the attenuation of the complement effects by C4bBP/PS. The specifics of these observations in the E. coli sepsis model will be reviewed.

Topics: Animals; Antibodies; Anticoagulants; Carrier Proteins; Complement Inactivator Proteins; Disease Models, Animal; Disseminated Intravascular Coagulation; Endothelium, Vascular; Escherichia coli Infections; Glycoproteins; Interleukin-6; Lipoproteins; Papio; Protein C; Protein S; Thromboplastin; Tumor Necrosis Factor-alpha

Topics: Animals; Bacteremia; Biomarkers; Disseminated Intravascular Coagulation; Dogs; Edema; Escherichia coli Infections; Inflammation; Papio; Protein C; Rats; Shock, Septic; Thromboplastin; Tumor Necrosis Factor-alpha

Clinical trials show that interleukin (IL)-6 represents a predictive marker in human sepsis. Furthermore, IL-6 has been proposed as a candidate mediator for endotoxin (lipopolysaccharide)-induced coagulation activation: In a primate model, an (alphaIL-6 antibody (alphaIL-6 Ab) almost abolished lipopolysaccharide-induced coagulation activation. Therefore, we wished to determine if an alphaIL-6 Ab (B-E8) may also attenuate lipopolysaccharide-induced activation of coagulation in humans.. The study was a randomized, double blind, placebo-controlled parallel group trial (n = 12 per group).. University medical center.. Healthy volunteers.. Healthy volunteers were randomized to receive either 80 mg of a monoclonal anti-IL-6 Ab (B-E8) or placebo intravenously before bolus infusion of 2 ng/kg lipopolysaccharide.. B-E8 effectively decreased IL-6 bioactivity as measured by a Bg-bioassay in vitro and concentrations of C reactive protein. However, B-E8 did not decrease lipopolysaccharide-induced tissue factor-messenger RNA transcription or plasma concentrations of downstream coagulation variables (prothrombin fragment 1 + 2, thrombin-antithrombin III complexes, and D-dimer concentrations). Similarly, tumor necrosis factor-alpha concentrations, fibrinolytic activity (plasmin-antiplasmin complexes), endothelial activation (soluble E-selectin), and IL-10 were unaffected.. IL-6 does not appear to mediate early-phase lipopolysaccharide-induced coagulation activation in humans.

Topics: Adult; Antibodies, Monoclonal; Blood Coagulation Disorders; C-Reactive Protein; Dose-Response Relationship, Immunologic; Double-Blind Method; E-Selectin; Endotoxemia; Escherichia coli; Escherichia coli Infections; Fibrin Fibrinogen Degradation Products; Fibrinolysis; Humans; Infusions, Intravenous; Interleukin-10; Interleukin-6; Lipopolysaccharides; Male; Polymerase Chain Reaction; Thromboplastin; Transcription, Genetic; Treatment Outcome; Tumor Necrosis Factor-alpha

There is a close cross-talk between complement, Toll-like receptors (TLRs) and coagulation. The role of the central complement component 5 (C5) in physiological and pathophysiological hemostasis has not, however, been fully elucidated. This study examined the effects of C5 in normal hemostasis and in Escherichia coli-induced coagulation and tissue factor (TF) up-regulation. Fresh whole blood obtained from six healthy donors and one C5-deficient individual (C5D) was anti-coagulated with the thrombin inhibitor lepirudin. Blood was incubated with or without E. coli in the presence of the C5 inhibitor eculizumab, a blocking anti-CD14 monoclonal antibody (anti-CD14) or the TLR-4 inhibitor eritoran. C5D blood was reconstituted with purified human C5. TF mRNA was measured by quantitative polymerase chain reaction (qPCR) and monocyte TF and CD11b surface expression by flow cytometry. Prothrombin fragment 1+2 (PTF1·2) in plasma and microparticles exposing TF (TF-MP) was measured by enzyme-linked immunosorbent assay (ELISA). Coagulation kinetics were analyzed by rotational thromboelastometry and platelet function by PFA-200. Normal blood with eculizumab as well as C5D blood with or without reconstitution with C5 displayed completely normal biochemical hemostatic patterns. In contrast, E. coli-induced TF mRNA and TF-MP were significantly reduced by C5 inhibition. C5 inhibition combined with anti-CD14 or eritoran completely inhibited the E. coli-induced monocyte TF, TF-MP and plasma PTF1·2. Addition of C5a alone did not induce TF expression on monocytes. In conclusion, C5 showed no impact on physiological hemostasis, but substantially contributed to E. coli-induced procoagulant events, which were abolished by the combined inhibition of C5 and CD14 or TLR-4.

Topics: Antibodies, Blocking; Antibodies, Monoclonal, Humanized; Blood Cells; Blood Coagulation; Cells, Cultured; Complement C5; Disaccharides; Escherichia coli; Escherichia coli Infections; Female; Hemostasis; Hirudins; Humans; Lipopolysaccharide Receptors; Male; Platelet Function Tests; Receptor Cross-Talk; Recombinant Proteins; Sepsis; Sugar Phosphates; Thrombelastography; Thromboplastin; Toll-Like Receptor 4

Inhibition of tissue factor, the primary initiator of coagulation in sepsis, attenuates morbidity in primates infused with Escherichia coli. In a human endotoxemia model, microparticles expressing procoagulant TF (MP-TF) are released in blood concurrently with markers of inflammation and coagulation. We investigated whether the release of MP-TF into blood is accompanied by procoagulant and inflammatory changes in patients with E. coli urinary tract infection.. In a multicenter cohort study, we determined clinical disease severity using APACHE II scores and measured plasma MP-TF activity, TAT, sE-selectin, sVCAM-1, procalcitonin and monocyte count in blood of 215 patients with community-acquired febrile E. coli urinary tract infections.. Plasma MP-TF activity on admission corresponded with clinical disease severity (APACHE II score; P=0.006) and correlated significantly but weakly with plasma markers of disease severity (sE-selectin, sVCAM-1, procalcitonin). Additionally, median plasma MP-TF activity was higher in patients than in healthy controls (197 vs. 79 fM Xa/min; P<0.0001), and highest in bacteremic patients (325 fM Xa/min). MP-TF activity showed a weak inverse correlation with monocyte count (rs -0.22; P=0.016) and a weak correlation with TAT (rs 0.23, P=0.017). After 3 days of antibiotic treatment, upon resolution of the infection, plasma MP-TF activity and TAT concentrations declined.. Microparticle-associated procoagulant tissue factor activity is related to disease severity and bacteremia in febrile E. coli UTI patients and may contribute to the prothrombotic state in gram-negative sepsis.

Topics: Adult; Aged; Aged, 80 and over; Bacteremia; Cell-Derived Microparticles; Cohort Studies; Escherichia coli Infections; Female; Fever; Humans; Male; Middle Aged; Severity of Illness Index; Thromboplastin; Urinary Tract Infections; Young Adult

The complement pathway and CD14 play essential roles in inflammation, but little is known about the relative roles of complement and CD14 in E. coli-induced tissue factor (TF) mRNA upregulation, expression by monocytes, and functional activity in human whole blood.. Whole E. coli bacteria were incubated for up to 4 h in human whole blood containing the anticoagulant lepirudin, which does not affect complement activation. TF mRNA levels were analyzed using reverse transcription, quantitative real-time PCR (RT-qPCR), and the expression of TF on the cell surface was analyzed using flow cytometry. Complement was selectively inhibited using the C3 convertase inhibitor compstatin or a C5a receptor antagonist (C5aRa), while CD14 was blocked by an anti-CD14 F(ab')2 monoclonal antibody.. The E. coli-induced TF mRNA upregulation was reduced to virtually background levels by compstatin, whereas anti-CD14 had no effect. Monocyte TF expression and TF activity in plasma microparticles were significantly reduced by C5aRa. Anti-CD14 alone only slightly reduced E. coli-induced monocyte TF expression but showed a modest additive effect when combined with the complement inhibitors. Inhibiting complement and CD14 efficiently reduced the expression of the E. coli-induced cytokines IL-1beta, IL-6, IL-8, and platelet-derived growth factor bb.. Our results indicate that E. coli-induced TF mRNA upregulation is mainly dependent on complement activation, while CDI4 plays a modest role in monocyte TF expression and the plasma TF activity in human whole blood.

Topics: Adult; Anticoagulants; Complement Inactivating Agents; Complement System Proteins; Cytokines; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Escherichia coli Infections; Flow Cytometry; Hirudins; Humans; Lipopolysaccharide Receptors; Monocytes; Real-Time Polymerase Chain Reaction; Recombinant Proteins; RNA, Messenger; Sepsis; Thromboplastin; Up-Regulation

Neisseria meningitidis causes sepsis with coagulopathy. The present study evaluated the tissue factor (TF)-inducing capacity of bacterial LPS in different presentation forms, i.e. membrane-bound LPS versus purified LPS, and of non-LPS components of N. meningitidis. By using a wild-type N. meningitidis, a mutant N. meningitidis lacking LPS (LPS-deficient N. meningitidis), purified LPS from N. meningitidis and Escherichia coli, we measured TF-expression and TF-activity on human monocytes and microparticles (MPs). The effect of TF-modulators, such as phosphatidylserine (PS), tissue factor pathway inhibitor (TFPI) and recombinant IL-10 (rhIL-10) was investigated. In plasmas from meningococcal patients, fibrinopeptide A (FPA), LPS and IL-10 were quantified. Monocytes and MPs exposed to purified LPS or wild-type N. meningitidis had much higher TF-activity than monocytes and MPs exposed to LPS-deficient N. meningitidis (clot formation assay). Incubation with wild-type N. meningitidis, but also LPS-deficient N. meningitidis, resulted in TF-expression on monocytes (flow cytometry, qRT-PCR). Increased cellular TF-activity is associated with coincident surface-exposure of PS and the number of monocytes positive for both PS and TF was significantly higher for monocytes exposed to wild-type N. meningitidis (7.6%) compared with monocytes exposed to LPS-deficient N. meningitidis (1.8%). Treatment with rhIL-10 reduced monocyte- and MP-associated TF-activity, the number of monocytes positive for both TF and PS, and microvesiculation. Patients with meningococcal septicemia had significantly higher levels of LPS, FPA and IL-10 than patients with distinct meningitis. Our results indicate that LPS from N. meningitidis is crucial for inducing TF-activity, but not for monocyte- and MP-associated TF-expression. TF-activity seems to require coincident expression of TF and PS on monocytes, and LPS induces such double-positive monocytes.

Topics: Blood Coagulation; Cell-Derived Microparticles; Cells, Cultured; Escherichia coli; Escherichia coli Infections; Fibrinopeptide A; Gene Expression Regulation, Bacterial; Humans; Interleukin-10; Lipopolysaccharides; Lipoproteins; Meningitis, Meningococcal; Meningococcal Infections; Monocytes; Neisseria meningitidis, Serogroup B; Phosphatidylserines; Thromboplastin

Tissue factor expression in sepsis activates coagulation in the lung, which potentiates inflammation and leads to fibrin deposition. We hypothesized that blockade of factor X binding to the tissue factor-factor VIIa complex would prevent sepsis-induced damage to the lungs and other organs. Acute lung injury was produced in 15 adult baboons primed with killed Escherichia coli [1 x 10(9) colony-forming units (CFU)/kg], and then 12 h later, they were given 1 x 10(10) CFU/kg live E. coli by infusion. Two hours after live E. coli, animals received antibiotics with or without monoclonal antibody to tissue factor intravenously to block tissue factor-factor X binding. The animals were monitored physiologically for 34 h before being killed and their tissue harvested. The antibody treatment attenuated abnormalities in gas exchange and lung compliance, preserved renal function, and prevented tissue neutrophil influx and bowel edema relative to antibiotics alone (all P < 0.05). It also attenuated fibrinogen depletion (P < 0.01) and decreased proinflammatory cytokines, e.g., IL-6 and -8 (P < 0.01), in systemic and alveolar compartments. Similar protective effects of the antibody on IL-6 and -8 expression and permeability were found in lipopolysaccharide-stimulated endothelial cells. Blockade of factor X binding to the tissue factor-factor VIIa complex attenuates lung and organ injuries in established E. coli sepsis by attenuating the neutrophilic response and inflammatory pathways.

Topics: Animals; Antibodies, Monoclonal; Blood Circulation; Capillary Permeability; Cells, Cultured; Cytokines; Endothelial Cells; Escherichia coli Infections; Factor X; Humans; Immunoglobulin Fab Fragments; Inflammation Mediators; Lipopolysaccharides; Male; Papio; Renal Insufficiency; Respiratory Insufficiency; Thromboplastin

Endothelium plays a critical role in the pathobiology of sepsis by integrating systemic host responses and local rheological stimuli. We studied the differential expression and activation of tissue factor (TF)-dependent coagulation on linear versus branched arterial segments in a baboon sepsis model. Animals were injected intravenously with lethal doses of Escherichia coli or saline and sacrificed after 2 to 8 hours. Whole-mount arterial segments were stained for TF, TF-pathway inhibitor (TFPI), factor VII (FVII), and markers for endothelial cells (ECs), leukocytes, and platelets, followed by confocal microscopy and image analysis. In septic animals, TF localized preferentially at branches, EC surface, leukocytes, and platelet aggregates and accumulated in large amounts in the subendothelial space. FVII strongly co-localized with TF on ECs and leukocytes but less so with subendothelial TF. TFPI co-localized with TF and FVII on endothelium and leukocytes but not in the subendothelial space. Focal TF increases correlated with fibrin deposition and increased endothelial permeability to plasma proteins. Biochemical analysis confirmed that aortas of septic baboons expressed more TF mRNA and protein than controls. Branched segments contained higher TF protein levels and coagulant activity than equivalent linear areas. These data suggest that site-dependent endothelial heterogeneity and rheological factors contribute to focal procoagulant responses to E. coli.

Topics: Animals; Aorta; Arteries; Biomarkers; Blood Coagulation; Blood Platelets; Disease Models, Animal; Endothelial Cells; Escherichia coli Infections; Factor VII; Image Processing, Computer-Assisted; Leukocytes; Lipopolysaccharides; Lipoproteins; Microscopy, Confocal; Models, Biological; Papio; RNA, Messenger; Shock, Septic; Thromboplastin; Up-Regulation

Anticoagulants have gained increasing attention for the treatment of sepsis. Inhibition of the tissue factor (TF)/factor (F) VIIa pathway has been shown to attenuate the activation of coagulation and to prevent death in a primate model of sepsis caused by gram-negative bacteria.. To determine the role of the TF/FVIIa complex in the host response to peritonitis, mice received an intraperitoneal injection of live Escherichia coli with or without concurrent treatment with recombinant nematode anticoagulant protein c2 (rNAPc2), a selective inhibitor of the TF/FVIIa pathway.. Peritonitis was associated with an increase in the expression of TF at the tissue level and activation of coagulation, as reflected by elevated levels of thrombin-antithrombin complexes and by increased fibrin(ogen) deposition in the liver and lungs. rNAPc2 strongly attenuated this procoagulant response but did not influence the inflammatory response (histopathology, leukocyte recruitment to the peritoneal cavity, and cytokine and chemokine levels). Moreover, rNAPc2 did not alter bacterial outgrowth locally or dissemination of the infection, and survival was not different between rNAPc2-treated mice and control mice.. These data suggest that TF/FVIIa activity contributes to the activation of coagulation during E. coli peritonitis but does not play a role in the inflammatory response or antibacterial host defense.

Topics: Animals; Blood Coagulation; Disease Models, Animal; Escherichia coli; Escherichia coli Infections; Factor VIIa; Helminth Proteins; Inflammation; Male; Mice; Mice, Inbred C57BL; Peritonitis; Thromboplastin

Blockade of tissue factor before lethal sepsis prevents acute lung injury and renal failure in baboons, indicating that activation of coagulation by tissue factor is an early event in the pathogenesis of acute lung injury and organ dysfunction. We hypothesized that blockade of tissue factor would also attenuate these injuries in established sepsis by prevention of further fibrin deposition and inflammation. Twelve male baboons received heat-killed Escherichia coli intravenously followed 12 hours later by live E. coli infusion. Six animals were treated 2 hours after the live bacteria with site-inactivated Factor VIIa, a competitive tissue factor inhibitor, and six animals were vehicle-treated sepsis control subjects. Animals were ventilated and monitored for 48 hours. Physiologic and hematologic parameters were measured every 6 hours, and pathologic evaluation was performed after 48 hours. Animals treated with site inactivated Factor VIIa had less severe lung injury, with preserved gas exchange, better lung compliance and histology scores, and decreased lung wet/dry weight. In treated animals, urine output was higher, metabolic acidosis was attenuated, and renal tubular architecture was protected. Coagulopathy was attenuated, and plasma interleukin-6, interleukin-8, and soluble tumor necrosis factor receptor-1 levels were significantly lower in the treated animals. These results show that blockade of coagulation attenuates acute lung and renal injury in established Gram-negative sepsis accompanied by antiinflammatory effects of therapy.

Topics: Acute Kidney Injury; Animals; Antigens, CD; Cytokines; Disease Models, Animal; Drug Monitoring; Escherichia coli Infections; Factor VIIa; Hemodynamics; Inflammation; Interleukin-6; Interleukin-8; Lung Compliance; Male; Papio; Pulmonary Gas Exchange; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Type I; Respiratory Distress Syndrome; Sepsis; Severity of Illness Index; Thromboplastin

Topics: Biomarkers; Child; Escherichia coli Infections; Escherichia coli O157; Hemolytic-Uremic Syndrome; Humans; Thromboplastin

Sepsis-induced tissue factor (TF) expression activates coagulation in the lung and leads to a procoagulant environment, which results in fibrin deposition and potentiates inflammation. We hypothesized that preventing initiation of coagulation at TF-Factor VIIa (FVIIa) complex would block fibrin deposition and control inflammation in sepsis, thereby limiting acute lung injury (ALI) and other organ damage in baboons. A model of ALI was used in which adult baboons were primed with killed Escherichia coli (1 x 10(9) CFU/kg), and bacteremic sepsis was induced 12 h later by infusion of live E. coli at 1 x 10(10) CFU/kg. Animals in the treatment group were given a competitive inhibitor of TF, site-inactivated FVIIa (FVIIai), intravenously at the time of the infusion of live bacteria and monitored physiologically for another 36 h. FVIIai dramatically protected gas exchange and lung compliance, prevented lung edema and pulmonary hypertension, and preserved renal function relative to vehicle (all p < 0.05). Treatment attenuated sepsis-induced fibrinogen depletion (p < 0.01) and decreased systemic proinflammatory cytokine responses, for example, interleukin 6 (p < 0.01). The protective effects of TF blockade in sepsis-induced ALI were confirmed by using tissue factor pathway inhibitor. The results show that TF-FVIIa complex contributes to organ injury in septic primates in part through selective stimulation of proinflammatory cytokine release and fibrin deposition.

Topics: Acute Kidney Injury; Animals; Bacteremia; Blood Coagulation; Disease Models, Animal; Drug Evaluation, Preclinical; Escherichia coli Infections; Factor VIIIa; Fibrinogen; Hemodynamics; Inflammation; Interleukin-6; Kidney Function Tests; Lung Compliance; Male; Papio; Pulmonary Edema; Pulmonary Gas Exchange; Random Allocation; Respiratory Distress Syndrome; Thromboplastin; Tumor Necrosis Factor-alpha

Microvascular thrombosis in the kidney plays an important role in the pathogenesis of hemolytic uremic syndrome (HUS). Tissue factor (TF), present on the vascular surface of endothelial cells, binds factor VIIa. The complex initiates the coagulating cascade by activating factors X and IX.. In cases of HUS associated with verotoxin-producing E. coli (VTEC) infection, VTEC gastroenteritis without HUS and normal controls, we measured plasma concentrations of TF and tissue factor pathway inhibitor (TFPI) to evaluate their clinical significance. In children with non-HUS chronic renal failure (CRF), the TF levels were also measured as another control group.. In the acute phase of HUS, plasma levels of TF and TFPI were significantly elevated, then returned to normal range in the recovery phase. The TF levels were closely correlated with the thrombin antithrombin-III complex, a marker of thrombin activity in circulating blood, and with creatinine clearance (Ccr). Furthermore, a positive correlation was noted between plasma TF levels and plasma soluble thrombomodulin (sTM) levels, which is a marker of endothelial cell injury. The influence of decreased excretion from damaged kidneys should be considered since a definite lot correlation was observed between plasma TF levels and Ccr in children with non-HUS CRF.. From these findings, we concluded that elevated TF circulating levels may also play an important role in blood-clotting activation observed in VTEC-HUS patients, and may also be a useful marker for renal damage.

Topics: Case-Control Studies; Child, Preschool; Enzyme-Linked Immunosorbent Assay; Escherichia coli Infections; Escherichia coli O157; Female; Hemolytic-Uremic Syndrome; Humans; Lipoproteins; Male; Shiga Toxins; Thromboplastin

To determine whether treatment with recombinant human tissue factor pathway inhibitor (TFPI), an inhibitor of the extrinsic coagulation pathway, can improve survival in a clinically relevant model of gram-negative sepsis, rabbits were given an intraperitoneal inoculation of a suspension containing hemoglobin (40 microg/mL), porcine mucin (150 microg/mL), and viable Escherichia coli O18:K1 (1.0 +/- 0.5 x 10(5) cfu/kg). Treatment with gentamicin (5 mg/kg every 12 h for five doses) was instituted 4 h after induction of peritonitis. At the same time point, rabbits were randomized to receive a 24-h infusion of vehicle or one of three different doses of TFPI. Treatment groups, 7-day survival rates, and significance versus control were as follows: control, 1 of 20; TFPI(LOW DOSE) (0.1 mg/kg, then 1 microg/kg/min), 3 of 12 (P = .14); TFPI(MID DOSE), (0.5 mg/kg, then 5 microg/kg/min), 7 of 12 (P = .002); TFPI(HIGH DOSE) (10 mg/kg, then 10 microg/kg/min), 4 of 13 (P = .04). Thus, delayed treatment with TFPI improves survival in septic rabbits.

Topics: Animals; Anti-Bacterial Agents; Anticoagulants; Blood Coagulation; Blood Pressure; Dose-Response Relationship, Drug; Drug Therapy, Combination; Escherichia coli Infections; Gentamicins; Humans; Lipoproteins; Oxygen; Peritonitis; Rabbits; Recombinant Proteins; Shock, Septic; Thromboplastin

The procoagulant activity of mononuclear cells (MNCs) may play an important role in the disseminated intravascular coagulation seen in septic shock. This study compares the capacity of Escherichia coli (E. coli) and recombinant human TNF-alpha (rhTNF-alpha) to induce procoagulant activity by baboon MNCs. In vivo studies showed that MNC procoagulant activity was significantly increased at T + 120 min after LD100 E. coli infusion into baboons. Most of this procoagulant activity was attributable to tissue factor. In contrast, a bolus infusion of rhTNF-alpha (150 micrograms/kg) and a monoclonal antibody to activated protein C (2 mg/kg) did not induce any increase of MNC procoagulant activity at T + 120 min even though the plasma TNF-alpha level was 10 times higher than that seen following infusion of E. coli. In vitro studies showed that E. coli at concentrations comparable to that observed in the vivo study and LPS at a concentration of 2.5 ng/mL induced more intense tissue factor expression by both human and baboon monocytes than rhTNF-alpha in the concentrations ranging from 10 to 1,000 ng/mL. These results suggest that TNF-alpha alone is not sufficient to induced noticeable MNC procoagulant activity, at least, in the early stage of this septic shock model.

Topics: Animals; Blood Pressure; Coagulants; Disseminated Intravascular Coagulation; Escherichia coli; Escherichia coli Infections; Fibrinogen; Humans; Lethal Dose 50; Leukocytes; Leukocytes, Mononuclear; Lipopolysaccharides; Papio; Platelet Count; Recombinant Proteins; Shock, Septic; Thromboplastin; Tumor Necrosis Factor-alpha

Reciprocal interactions between elements of the acute inflammatory response and the coagulation system play important roles in host defense homeostasis during Gram-negative bacterial sepsis. However, derangements in the regulation of the inflammatory-coagulant axis in this setting may result in progressive tissue damage and disseminated intravascular coagulation. In this article, the integrated responses in the baboon model of Escherichia coli sepsis are analyzed as a basis of understanding these response interactions in the critically ill. In particular, three topics will be reviewed. First, the role of tissue factor in mediating the coagulant response to inflammation and the role of tumor necrosis factor (TNF) in initiating and amplifying this coagulant response into a full-blown consumptive coagulopathy are defined. A second and parallel topic concerns the role played by tissue factor pathway inhibitor and other anticoagulant systems in not only regulating this coagulant response, but also in attenuating the initial inflammatory response. The third topic concerns the use of assays of enzyme inhibitor complexes composed of components of these regulatory anticoagulant systems to help define the hypercoagulable state and possibly to make an early, specific diagnosis of sepsis prior to overt failure of the hemostatic system.

Topics: Animals; Blood Coagulation; Blood Coagulation Factors; Disseminated Intravascular Coagulation; Endothelium, Vascular; Escherichia coli Infections; Fibrin; Inflammation; Lipoproteins; Papio; Sepsis; Thromboplastin; Tumor Necrosis Factor-alpha

Disseminated intravascular thrombosis is a frequent complication of endotoxic shock, and modulation of endothelial cell hemostatic properties has been proposed to play a role in its pathogenesis based on studies of endothelial cells in culture. This study examined the in vivo expression of tissue factor (TF) and thrombomodulin (TM) in a baboon model of lethal Escherichia coli sepsis using immunohistochemistry with monospecific antibodies. Expression of E-selectin (E-sel) was also determined as a marker of endothelial cell activation. Correlation of immunoreactivity with procoagulant activity in lipopolysaccharide-stimulated cultured human endothelial cells showed that immunohistochemistry was sufficiently sensitive to detect as little as 5% of the maximum in vitro endothelial cell TF response. Vascular endothelium of control animals expressed TM but had no detectable TF or E-sel. Following E. coli infusion, widespread E-sel expression and microvascular fibrin deposition was evident within 6 hours. However, expression of TF by endothelial cells became detectable only in the splenic microvasculature, where endothelial specificity of TF expression was confirmed by dual immunofluorescence of TF with von Willebrand's factor and with TM. In the spleen, there was a dissociation of expression of TF and E-sel, with marginal zone vessels being TF-positive and E-sel-negative, whereas sinusoidal endothelium was E-sel-positive but TF-negative. TM expression was unchanged from controls. Additionally, expression of TF by lung alveolar epithelial cells, splenic macrophages, and epithelial cells of the renal glomeruli was observed to be enhanced in septic animals. This study documents endothelial cell expression of TF in vivo in a relevant pathological setting. At the same time, compared with endothelial cells in culture, there is in vivo both significantly greater control of TF expression than expected, given the strong positive stimuli present in lethal E. coli septic shock and an unpredicted heterogeneity of activation responses.

Topics: Animals; Cell Adhesion Molecules; E-Selectin; Endothelium, Vascular; Escherichia coli Infections; Immunohistochemistry; Lipopolysaccharides; Membrane Glycoproteins; Microcirculation; Papio; Receptors, Cell Surface; Receptors, Thrombin; Shock, Septic; Thrombin; Thromboplastin; Tissue Distribution

Gram-negative bacteremia poses a major health problem, causing one-half of cases of lethal septic shock acquired during hospitalization. Bacterial lipopolysaccharide (LPS) and the inflammatory cytokines, tumor necrosis factor (TNF) and interleukin-1 (IL-1), have been shown to be essential mediators of septic shock. Among the effects of these mediators is a coagulopathy that may be triggered by induced expression of tissue factor (TF) on macrophages and endothelial cells. We now report that 500 micrograms/kg of either immunoglobulin G (IgG) or Fab fragments of a monoclonal antibody against TF administered to baboons as a pretreatment attenuates the coagulopathy and protects against LD100 Escherichia coli. This study provides direct evidence of an essential effector role for TF in septic shock.

Topics: Adrenal Glands; Animals; Antibodies, Monoclonal; Blood Pressure; Creatinine; Escherichia coli Infections; Factor VII; Fibrinogen; Kidney; Liver; Lung; Papio; Shock, Septic; Spleen; Thromboplastin

Endotoxin and monocyte thromboplastin activity were evaluated in rats with gram-negative septicaemia induced by caecal perforation or intravenous Escherichia coli challenge and treated with antibiotics or placebo. Endotoxin burst was not detected in either form of septicaemia during antibiotic treatment. Thromboplastin synthesis in monocytes is known to be stimulated by endotoxin, but the rats showed no increase of monocyte thromboplastin activity after antibiotic treatment, which constituted further evidence against the concept of massive endotoxin liberation during antibiotic therapy for gram-negative septicaemia.

Topics: Animals; Anti-Bacterial Agents; Cefotaxime; Endotoxins; Escherichia coli Infections; Gentamicins; Male; Monocytes; Rats; Rats, Inbred Strains; Sepsis; Thromboplastin; Tinidazole

Tissue thromboplastin generation in monocytes was studied during various stages of Escherichia coli endotoxinaemia in pigs. The pigs were monitored in halothane anaesthesia and mechanically ventilated. Blood was sampled from the superior caval vein before and during endotoxin infusion and up to 6 hours after its start. Monnuclear leukocytes were harvested with Lymphoprep separation and monocyte counts were made, using TRITC-labelled sheep erythrocytes, acridine orange and a fluorescence microscope. Thromboplastin was quantified in a two-stage assay by incubating the test sample together with purified factor X, factor VII and Ca++. The generated factor Xa was thereafter assayed. There was statistically significant increase of tissue thromboplastin activity in monocytes after endotoxin infusion. Maximum level was reached at the end of the infusion and was maintained throughout the observation period. Decrease occurred in platelets, leukocytes, antithrombin III, fibrinogen and clotting factors V, VII and VIII, and clotting time was prolonged. These findings indicated significant disseminated intravascular coagulation. The endotoxin-stimulated monocytes with their elevated tissue thrombo-plastin activity thus may play an important part in development of the DIC which so often follows septicemia.

Topics: Animals; Antithrombin III; Blood Pressure; Disseminated Intravascular Coagulation; Endotoxins; Escherichia coli Infections; Factor V; Factor VII; Factor VIII; Female; Fibrinogen; Leukocyte Count; Male; Monocytes; Platelet Count; Prothrombin Time; Swine; Thromboplastin

Topics: Animals; Blood Coagulation Disorders; Blood Platelets; Blood Pressure; Cardiac Output; Disseminated Intravascular Coagulation; Escherichia coli Infections; Fibrinolysis; Hematocrit; Hydrogen-Ion Concentration; Male; Oxygen; Papio; Prothrombin Time; Sepsis; Shock, Septic; Thromboplastin; Vascular Resistance