Inflammation, endothelium, and coagulation in sepsis

Exchange protein directly activated by cyclic AMP-1-regulated recruitment of CCAAT/enhancer-binding proteins to the suppressor of cytokine signaling-3 promoter

The ability of prototypical second messenger cyclic AMP (cAMP) to positively control transcription of the somatostatin gene was pivotal to the original identification of the transcription factor cAMP response element-binding protein. However, it is now clear that alternative intracellular cAMP sensors, of which the exchange protein directly activated by cAMP (Epac) proteins have been studied most intensively, also initiate transcription of key genes in response to cAMP elevation. For example, we have demonstrated in vascular endothelial cells that activation of Epac1 is necessary for cAMP-mobilizing agents to trigger the induction of the gene-encoding suppressor of cytokine signaling-3 (SOCS-3), a potent inhibitor of interleukin (IL)-6 signaling. This is achieved through the recruitment of CCAAT/enhancer-binding protein (C/EBP) transcription factors to the SOCS-3 promoter. Here, we describe in detail how to identify and measure cAMP-mediated recruitment of a specific C/EBP isoform to a candidate regulator region of the SOCS-3 promoter in vascular endothelial cells in vitro. We also describe the RNA interference strategies with which we identified a role for Epac1 and SOCS-3 in being responsible for mediating the inhibitory effect of cAMP elevation on IL-6 signaling.

Coagulation and inflammation in scrub typhus and murine typhus--a prospective comparative study from Laos

Scrub typhus (caused by Orientia tsutsugamushi) and murine typhus (caused by Rickettsia typhi) cause up to 28% of febrile episodes in Thailand and Laos. The current understanding of coagulation and inflammation in the pathogenesis of these clinically very similar vasculotropic diseases is limited. This study compared human in vivo changes in 15 coagulation, inflammation and endothelial activation markers in prospectively collected admission and follow-up samples of 121 patients (55 scrub typhus, 55 murine typhus, and 11 typhus-like illness) and 51 healthy controls from Laos. As compared with controls, all but one of the markers assessed were significantly affected in typhus patients; however, the activation patterns differed significantly between scrub and murine typhus patients. The levels of markers of coagulation activation and all inflammatory cytokines, except for interleukin-12, were significantly higher in patients with scrub typhus than in those with murine typhus. In patients with murine typhus, however, the levels of endothelium-derived markers were significantly higher. Anticoagulant factors were inhibited in both typhus patient groups. This is the first study demonstrating that, in scrub typhus, in vivo coagulation activation is prominent and is related to a strong proinflammatory response, whereas in murine typhus, changes in coagulant and fibrinolytic pathways are suggestive of endothelial cell perturbation. These data suggest that, although late-stage endothelial infection is common in both diseases, the in vivo pathogenic mechanisms of R. typhi and O. tsutsugamushi could differ in the early phase of infection and may contribute to disease differentiation.

Sepsis induces albuminuria and alterations in the glomerular filtration barrier: a morphofunctional study in the rat

Introduction

Increased vascular permeability represents one of the hallmarks of sepsis. In the kidney, vascular permeability is strictly regulated by the 'glomerular filtration barrier' (GFB), which is comprised of glomerular endothelium, podocytes, their interposed basement membranes and the associated glycocalyx. Although it is likely that the GFB and its glycocalyx are altered during sepsis, no study has specifically addressed this issue. The aim of this study was to evaluate whether albuminuria -- the hallmark of GFB perm-selectivity -- occurs in the initial stage of sepsis and whether it is associated with morphological and biochemical changes of the GFB.

Methods

Cecal ligation and puncture (CLP) was used to induce sepsis in the rat. Tumor necrosis factor (TNF)-alpha levels in plasma and growth of microorganisms in the peritoneal fluid were evaluated at 0, 3 and 7 hours after CLP or sham-operation. At the same times, kidney specimens were collected and structural and ultrastructural alterations in the GFB were assessed. In addition, several components of GFB-associated glycocalyx, syndecan-1, hyluronan (HA) and sialic acids were evaluated by immunofluorescence, immunohistochemistry and lectin histochemistry techniques. Serum creatinine and creatinine clearance were measured to assess kidney function and albuminuria for changes in GFB permeability. Analysis of variance followed by Tukey's multiple comparison test was used.

Results

Septic rats showed increased TNF-alpha levels and growth of microorganisms in the peritoneal fluid. Only a few renal corpuscles had major ultrastructural and structural alterations and no change in serum creatinine or creatinine clearance was observed. Contrarily, urinary albumin significantly increased after CLP and was associated with diffuse alteration in the glycocalyx of the GFB, which consisted in a decrease in syndecan-1 expression and in HA and sialic acids contents. Sialic acids were also changed in their structure, exhibiting a higher degree of acetylation.

Conclusions

In its initial phase, sepsis is associated with a significant alteration in the composition of the GFB-associated glycocalyx, with loss of GFB perm-selectivity as documented by albumin leakage into urine.

[Thrombin generation in critical illnesses]

Hemostasis is an important component of host defense and wound healing. During the last few decades, the interaction between hemostasis and inflammation has moved into the center of research. Thrombin, which is considered the central enzyme of the hemostatic system, plays a key role in these investigations. Immune modulatory treatment strategies, such as the supraphysiological doses of antithrombin and activated protein C in sepsis, were based on scientific investigations of thrombin generation and its role in inflammatory reactions. However, the complex function of thrombin has not yet been fully elucidated.

Chronic renal failure is accompanied by endothelial activation and a large increase in microparticle numbers with reduced procoagulant capacity

BACKGROUND

In patients with chronic renal failure (CRF), cardiovascular disease is the leading cause of increased morbidity and mortality. We hypothesized a role for endothelial activation and microparticle (MP) numbers and procoagulant activity in the pre-thrombotic state of these patients.

METHODS

We analysed blood samples of 27 patients with CRF [8 chronic kidney disease Stage 4 (CKD4), 9 peritoneal dialysis (PD) and 10 haemodialysis (HD), samples taken before and after HD] and 10 controls. Degree and nature of endothelial activation were assessed by measuring mature von Willebrand factor (vWF) and vWF propeptide levels. Cellular MPs were characterized by flow cytometry and MP-specific thrombin generation (TG) measurements.

RESULTS

CRF was accompanied by chronic (CKD4 and PD) or acute (HD) endothelial activation. Patients with CRF had substantially higher MP numbers than controls (median 9400 versus 4350×10(6)/L, P=0.001), without significant differences between the treatment subgroups or between pre- and post-HD. The vast majority of MPs were platelet derived. Of the minor populations, endothelial MPs and tissue factor-bearing MPs were more abundant in CRF. MPs were procoagulant, but the increase in numbers was not reflected in a proportional increase in MP-specific TG.

CONCLUSION

Renal failure is accompanied by endothelial activation of a different nature in CKD4 and PD patients compared to HD patients, and results in all subgroups in an increase of mainly platelet-derived MPs that appear to be less procoagulant than in other disease states, possibly because of the uraemic functional defect of their cellular source.

The effect of heparin administration in animal models of sepsis: a prospective study in Escherichia coli-challenged mice and a systematic review and metaregression analysis of published studies

INTRODUCTION

If thrombosis contributes to sepsis, heparin titrated using activated partial thromboplastin times may be efficacious. We investigated heparin in preclinical models.

METHODS AND MAIN RESULTS

In unchallenged mice (n = 107), heparin at 100, 500, or 2500 units/kg produced activated partial thromboplastin time levels less than, within, or greater than a prespecified therapeutic range (1.5-2.5 times control), respectively. In animals (n = 142) administered intratracheal Escherichia coli challenge, compared to placebo treatment, heparin at 100, 500, or 2500 units/kg were associated with dose dependent increases in the hazard ratios of death (hazard ratio [95% confidence interval]: 1.08 [0.66, 1.76]; 1.34 [0.80, 2.24]; 3.02 [1.49, 6.10], respectively) (p = .001 for the dose effect). Compared to normal saline challenge, E. coli without heparin (i.e., with placebo) increased the activated partial thromboplastin time (p = .002) close to the therapeutic range. While heparin at 100 and 500 units/kg with E. coli further increased activated partial thromboplastin time (p < .0001 vs. placebo) within or above the therapeutic range, respectively, these did not decrease inflammatory cytokines or lung injury. In metaregression analysis of published preclinical studies, heparin improved survival with lipopolysaccharide (n = 23, p < .0001) or surgically induced infection (n = 14, p < .0001) but not monobacterial (n = 7, p = .29) challenges.

CONCLUSION

Coagulopathy with sepsis or other variables, such as type of infectious source, may influence the efficacy of heparin therapy for sepsis.

Adenosine diphosphate receptor antagonist clopidogrel sulfate attenuates LPS-induced systemic inflammation in a rat model

Septic shock is characterized by systemic inflammation and can lead to hemorrhage and necrosis in multiple organs. Septic shock is one of the leading causes of death. Studies have reported that septic shock is strongly associated with coagulation abnormality. The adenosine diphosphate (ADP) receptor antagonist, clopidogrel sulfate (CS), inhibits platelet function. Thus, we hypothesized that CS could inhibit LPS-induced systemic inflammation in a rat model. Male Wistar rats weighing 250 to 300 g received an LPS injection, followed 6 h later by filtration leukocytapheresis or mock treatment for 30 min under sevoflurane anesthesia. Five days before LPS injection, rats were given an oral dose of water or CS (10 mg/kg body weight). Levels of proinflammatory markers were determined in serum and tissue samples, and high-mobility group box 1 (HMGB1) expression was evaluated in lung and liver tissues. Compared with LPS-treated rats, induction of cytokines (IL-6 and TNF-α) was reduced in rats pretreated with CS. In addition, histological changes observed in lung and liver tissue samples of LPS-treated rats were attenuated in CS-pretreated rats. Clopidogrel sulfate pretreatment also reduced LPS-induced HMGB1 expression in lung and liver tissues. Collectively, our findings demonstrate that CS pretreatment may have value as a new therapeutic tool against systemic inflammation.

Principles of source control in the early management of sepsis

Source control refers to the spectrum of physical measures that are undertaken to control a focus of infection, and to facilitate restoration of optimal anatomy and physiology. These measures are classified as drainage-the evacuation of infected liquid through the creation of a controlled sinus or fistula, debridement-the physical removal of necrotic infected tissue, device removal, and the definitive measures that comprise the process of reconstruction and rehabilitation. Effective and timely source control is critical to the successful management of life-threatening infection. This article reviews the principles of diagnosis and source-control management, and their application to common infections that result in severe sepsis and septic shock.

Antithrombotic and profibrinolytic activities of phloroglucinol

Phloroglucinol is the monomeric units of phlorotannins abundant in brown algae. Several biological effects of phloroglucinol have been reported, however, antithrombotic and profibrinolytic activities of phloroglucinol have not been studied yet. In this study, the anticoagulant properties of phloroglucinol were determined by assays of activated partial thromboplastin time (aPTT), prothrombin time (PT) and cell based thrombin and activated factor X (FXa) generation activities. And the effects of phloroglucinol on the expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were tested in tumor necrosis factor-α (TNF-α) activated human endothelial cells (HUVECs). I found that phloroglucinol prolonged aPTT and PT significantly and inhibited thrombin and FXa generation in HUVECs. Furthermore, phloroglucinol inhibited TNF-α induced PAI-1 production. I then used pathway inhibitors to investigate which step of the TNF-α induced signaling pathway was targeted by phloroglucinol. I observed that the c-Jun N-terminal kinase (JNK) inhibitor increased the inhibitory effects of phloroglucinol, whereas the nuclear factor factor-κB (NF-κB) and the extracellular signal-regulated kinase (ERK) inhibitor did not. Therefore these results suggest that phloroglucinol possess antithrombotic and profibrinolytic activities and that NF-κB and ERK pathways are possible targets of phloroglucinol in the regulation of TNF-α stimulated PAI-1 production in HUVECs.

The myeloid transcription factor KLF2 regulates the host response to polymicrobial infection and endotoxic shock

Precise control of myeloid cell activation is required for optimal host defense. However, this activation process must be under exquisite control to prevent uncontrolled inflammation. Herein, we identify the Kruppel-like transcription factor 2 (KLF2) as a potent regulator of myeloid cell activation in vivo. Exposure of myeloid cells to hypoxia and/or bacterial products reduced KLF2 expression while inducing hypoxia inducible factor-1α (HIF-1α), findings that were recapitulated in human septic patients. Myeloid KLF2 was found to be a potent inhibitor of nuclear factor-kappaB (NF-κB)-dependent HIF-1α transcription and, consequently, a critical determinant of outcome in models of polymicrobial infection and endotoxemia. Collectively, these observations identify KLF2 as a tonic repressor of myeloid cell activation in vivo and an essential regulator of the innate immune system.

Platelet aggregation in severe sepsis

Severe sepsis and multiple organ distress syndrome remain a diagnostic and therapeutic challenge for intensive therapy. Platelet activating factor forms a bridge between inflammation and clot formation. Our study surveys the effect of severe sepsis on platelet function and focuses on spontaneous aggregation in severely ill patients. Daily arterial blood samples were collected from 45 patients (average age of 60.7 ± 13) for five consecutive days following admission and 30 healthy controls. Platelet aggregation was measured using adrenaline (ADR), adenosine diphosphate (ADP), collagen (COL) and normal saline (SAL). Clinical status was observed using Multiple Organ Dysfunction Score (MODS) and Sequential Organ Failure Assessment (SOFA) score systems. Inducible aggregation deteriorated in septic patients in all 5 days with ADR, ADP and COL (P < 0.05) while SAL aggregation was increased during intensive care. Low platelet patients showed weak inducible aggregation with ADP throughout, with ADR on the 2nd, 3rd, 4th and 5th days and with COL on the 1st, 2nd and 3rd days. SAL aggregation showed no significance. No significant difference was seen between platelet functions comparing survivors and non-survivors. In the spontaneous aggregative group, platelet count was insignificantly higher, while procalcitonin levels were lower in 1st, 3rd and 4th days and no significant difference was observed in lactate levels. We demonstrated the presence of spontaneous platelet activity while overall inducible platelet aggregation is significantly deteriorated in septic patients. There were significant differences in inducible aggregation between normal and low platelet count groups. Inducible platelet function had no predictive value in the outcome.

A biomimetic membrane device that modulates the excessive inflammatory response to sepsis

OBJECTIVE

Septic shock has a clinical mortality rate approaching fifty percent. The major clinical manifestations of sepsis are due to the dysregulation of the host's response to infection rather than the direct consequences of the invading pathogen. Central to this initial immunologic response is the activation of leukocytes and microvascular endothelium resulting in cardiovascular instability, lung injury and renal dysfunction. Due to the primary role of leukocyte activation in the sepsis syndrome, a synthetic biomimetic membrane, called a selective cytopheretic device (SCD), was developed to bind activated leukocytes. The incorporation of the SCD along an extracorporeal blood circuit coupled with regional anticoagulation with citrate to lower blood ionized calcium was devised to modulate leukocyte activation in sepsis.

DESIGN

Laboratory investigation.

SETTING

University of Michigan Medical School.

SUBJECTS

Pigs weighing 30-35 kg.

INTERVENTIONS

To assess the effect of the SCD in septic shock, pigs were administered 30×10(10) bacteria/kg body weight of Escherichia coli into the peritoneal cavity and within 1 hr were immediately placed in an extracorporeal circuit containing SCD.

MEASUREMENTS AND MAIN RESULTS

In this animal model, the SCD with citrate compared to control groups without the SCD or with heparin anticoagulation ameliorated the cardiovascular instability and lung sequestration of activated leukocytes, reduced renal dysfunction and improved survival time compared to various control groups. This effect was associated with minimal elevations of systemic circulating neutrophil activation.

CONCLUSIONS

These preclinical studies along with two favorable exploratory clinical trials form the basis of an FDA-approved investigational device exemption for a pivotal multicenter, randomized control trial currently underway.

Pulmonary embolism in critically ill patients receiving antithrombotic prophylaxis: a clinical-pathologic study

PURPOSE

The true incidence of pulmonary embolism (PE) in critically ill adult patients receiving antithrombotic prophylaxis is unknown, as well as the impact on the outcome. The aim of this study was to assess the incidence of PE in a surgical and medical intensive care unit and to evaluate the presence of risk factors that could be helpful in identifying patients at higher risk of missed diagnosis.

MATERIALS AND METHODS

We retrospectively reviewed the autopsies and clinical data of all patients who died in our intensive care unit from 1996 to 2007. All patients received prophylaxis with subcutaneous low-molecular weight heparin.

RESULTS

Among the 600 autopsies, the clinical diagnosis of PE was confirmed in 13 patients (true positives) and not confirmed in 20 patients; in 73 patients, the PE was discovered only at the autopsy (false negatives [FNs]). The overall incidence of PE in our patients was 14.3%. Pulmonary embolism was considered the cause of death in 45% of FNs and 77% of true positives. Among all comorbidities, only a recent abdominal surgery and the presence of acute renal failure were associated with a higher risk of missed diagnosis. In the FN group, there was a significantly higher frequency of cases of septic shock.

CONCLUSIONS

Despite thromboprophylaxis, critically ill patients remain at risk for PE; and because of the difficulty in diagnosing it clinically, the death certificate diagnosis of PE underestimates the problem.

Reversible protease-activated receptor 1 downregulation mediated by Ankaferd blood stopper inducible with lipopolysaccharides inside the human umbilical vein endothelial cells

Ankaferd Blood Stopper (ABS) is a novel topical hemostatic agent with pleiotropic actions indicated in clinical hemorrhages. Protease-activated receptor 1 (PAR-1) is located in the crossroads of hemostasis, inflammation, infection, apoptosis and tumorigenesis. ABS-induced formation of the protein network with vital erythroid aggregation covers the entire physiological hemostatic process. The aim of this study is to assess the effects of ABS on PAR-1 in the Human Umbilical Vein Endothelial Cells (HUVEC) model, in relation to the "ipopolysaccharides (LPS)-challenge" to endothelium. For this purpose, ABS 10 μL and 100 μL, had been applied to HUVEC within the time periods of 5 minutes (min), 25 min, 50 min, 6 hours (h) and 24 h. The cells have lifted from the plastic surface and adhered to each other during theABSapplication to the HUVECs. After 24 hours the cells returned to normal baseline level. We observed dose-dependent reversible PAR-1 down-regulation mediated by ABS inside the human umbilical vein endothelial cells. ABS-induced sustained PAR-1 down-regulation in the presence of LPS. Those findings indicated that ABS hemostatic agent may act as a topical biological response modifier by acting on PAR-1 at the vascular endothelial and cellular level.

Impact of endogenous protein C on pulmonary coagulation and injury during lethal H1N1 influenza in mice

Influenza accounts for 5-10% of community-acquired pneumonia cases, and is a major cause of mortality. Sterile and bacterial lung injury are associated with procoagulant and inflammatory derangements in the lungs and down-regulation of the protein C (PC) pathway has been correlated with disease severity and mortality in severe bacterial pneumonia and sepsis. In addition, during lethal influenza pneumonia, pulmonary and systemic coagulation are activated, which can be attenuated by the administration of recombinant activated (A) PC. We here determined the role of endogenous PC in lethal H1N1 influenza A infection. Male C57BL/6 mice pretreated with an inhibitory monoclonal antibody directed against murine PC or a control antibody were intranasally infected with a lethal dose of a mouse-adapted H1N1 influenza A strain. Mice were killed at 48 or 96 hours after infection, after which lungs and bronchoalveolar lavage fluid were harvested, or observed for up to 9 days. Anti-PC antibody treatment aggravated pulmonary activation of coagulation as compared with control antibody treatment, as reflected by increased lung concentrations of thrombin-antithrombin complexes and fibrin degradation products, as well as intravascular thrombus formation. Anti-PC antibody treatment aggravated lung histopathology, but lowered bronchoalveolar neutrophil influx and total protein levels, and delayed mortality. In conclusion, endogenous PC has strong effects on the host response to lethal influenza A infection, inhibiting pulmonary coagulopathy and inflammation on the one hand, but facilitating neutrophil influx and protein leak and accelerating mortality on the other hand.

The role of endothelial interleukin-8/NADPH oxidase 1 axis in sepsis

Sepsis is a generalized inflammatory disease, caused by the hyperinflammatory response of the host, rather than by invading organisms. Endothelial cells play a crucial role in the pathogenesis of sepsis. In this study, we investigated the effects of interleukin-8 (IL-8), a known neutrophil chemoattractant, on lipopolysaccharide (LPS) -induced reactive oxygen species (ROS) production by endothelial cells, and its significance in the pathogenesis of LPS-mediated sepsis. The results revealed that IL-8 directly induced ROS production in human umbilical vein endothelial cells (HUVECs), and also mediated LPS-induced ROS production by HUVECs. Stimulation of HUVECs by LPS strongly enhanced tissue factor expression, a hallmark of severe sepsis, which was suppressed by IL-8 knockdown. We further discovered that NADPH oxidase (Nox) 1 expression in LPS-stimulated HUVECs was markedly repressed by IL-8 knockdown, and Nox1 knockdown reduced tissue factor expression, suggesting that the LPS/IL-8 signalling in endothelial cells was predominantly mediated by Nox1. In conclusion, LPS stimulation of endothelial cells causes activation of the IL-8-Nox1 axis, enhances the production of ROS, and ultimately contributes to the progression of severe sepsis.

Overexpression of the cell cycle inhibitor p16INK4a promotes a prothrombotic phenotype following vascular injury in mice

OBJECTIVE

Age-associated cellular senescence is thought to promote vascular dysfunction. p16(INK4a) is a cell cycle inhibitor that promotes senescence and is upregulated during normal aging. In this study, we examine the contribution of p16(INK4a) overexpression to venous thrombosis.

METHODS AND RESULTS

Mice overexpressing p16(INK4a) were studied with 4 different vascular injury models: (1) ferric chloride (FeCl(3)) and (2) Rose Bengal to induce saphenous vein thrombus formation; (3) FeCl(3) and vascular ligation to examine thrombus resolution; and (4) lipopolysaccharide administration to initiate inflammation-induced vascular dysfunction. p16(INK4a) transgenic mice had accelerated occlusion times (13.1 ± 0.4 minutes) compared with normal controls (19.7 ± 1.1 minutes) in the FeCl(3) model and 12.7 ± 2.0 and 18.6 ± 1.9 minutes, respectively in the Rose Bengal model. Moreover, overexpression of p16(INK4a) delayed thrombus resolution compared with normal controls. In response to lipopolysaccharide treatment, the p16(INK4a) transgenic mice showed enhanced thrombin generation in plasma-based calibrated automated thrombography assays. Finally, bone marrow transplantation studies suggested increased p16(INK4a) expression in hematopoietic cells contributes to thrombosis, demonstrating a role for p16(INK4a) expression in venous thrombosis.

CONCLUSIONS

Venous thrombosis is augmented by overexpression of the cellular senescence protein p16(INK4a).

Alterations of the preoperative coagulation profile in patients with acute appendicitis

Acute appendicitis (AA) is usually associated with a systemic inflammatory response that often leads to activation of coagulation. However, limited data about coagulation changes in AA are available.

Results of preoperative coagulation testing in 702 patients with confirmed AA and 697 patients undergoing minor elective surgery (control) during the same period were analyzed retrospectively. Coagulation activity of factors VII, IX (FVII:C, FIX:C) and the concentration of plasma endotoxin from 40 patients with AA and 15 control subjects were measured.

Compared with control subjects, prothrombin time (PT), fibrinogen (Fib) and endotoxin increased (all p<0.01), FVII:C decreased (p<0.05), and thrombin time shortened (p<0.01) significantly in patients with AA, which showed trends with increasing severity of disease. Areas under the receiver operating characteristic curve of Fib for discriminating complicated appendicitis or acute perforated appendicitis from enrolled patients were larger than those for leukocyte parameters. The concentration of endotoxin correlated negatively with FVII:C (r=−0.860, p<0.001), positively with PT (0.713, <0.001), and FVII:C negatively with PT (−0.729, <0.001) in individuals that were evaluated. The change in activated partial thromboplastin time and difference in FIX:C among patients with various pathological types of appendicitis were not significant.

Endotoxin-induced activation of the extrinsic coagulation pathway was present in patients with AA. Fib may be useful as a potential indicator for excluding complicated appendicitis.

Bacterial lipoprotein TLR2 agonists broadly modulate endothelial function and coagulation pathways in vitro and in vivo

TLR2 activation induces cellular and organ inflammation and affects lung function. Because deranged endothelial function and coagulation pathways contribute to sepsis-induced organ failure, we studied the effects of bacterial lipoprotein TLR2 agonists, including peptidoglycan-associated lipoprotein, Pam3Cys, and murein lipoprotein, on endothelial function and coagulation pathways in vitro and in vivo. TLR2 agonist treatment induced diverse human endothelial cells to produce IL-6 and IL-8 and to express E-selectin on their surface, including HUVEC, human lung microvascular endothelial cells, and human coronary artery endothelial cells. Treatment of HUVEC with TLR2 agonists caused increased monolayer permeability and had multiple coagulation effects, including increased production of plasminogen activator inhibitor-1 (PAI-1) and tissue factor, as well as decreased production of tissue plasminogen activator and tissue factor pathway inhibitor. TLR2 agonist treatment also increased HUVEC expression of TLR2 itself. Peptidoglycan-associated lipoprotein induced IL-6 production by endothelial cells from wild-type mice but not from TLR2 knockout mice, indicating TLR2 specificity. Mice were challenged with TLR2 agonists, and lungs and plasmas were assessed for markers of leukocyte trafficking and coagulopathy. Wild-type mice, but not TLR2 mice, that were challenged i.v. with TLR2 agonists had increased lung levels of myeloperoxidase and mRNAs for E-selectin, P-selectin, and MCP-1, and they had increased plasma PAI-1 and E-selectin levels. Intratracheally administered TLR2 agonist caused increased lung fibrin levels. These studies show that TLR2 activation by bacterial lipoproteins broadly affects endothelial function and coagulation pathways, suggesting that TLR2 activation contributes in multiple ways to endothelial activation, coagulopathy, and vascular leakage in sepsis.

Global Fibrinolytic Capacity in Neonatal Sepsis

In this study, we studied global fibrinolytic capacity (GFC) in newborn infants with sepsis. Sixty-one newborn infants, admitted to neonatal intensive care unit at Yuzuncu Yil University Hospital were enrolled in this study. White blood cell count, immature (I) / mature (M) neutrophil ratios, prothrombin time, and d-dimer levels were significantly higher in patient group than those of control group ( P < .05). We found GFC to be significantly lower in the patient group compared to the control group ( P < .05). The GFC value was negatively correlated to the Tollner scores but this correlation was not statistically significant ( r = −.267, P = .095). Our findings showed that GFC decreases in severe neonatal sepsis; therefore, we suggest that GFC may be used for prognosis or in the early prediction of severe sepsis rather than the diagnosis of neonatal sepsis.

Fetal death: a condition with a dissociation in the concentrations of soluble vascular endothelial growth factor receptor-2 between the maternal and fetal compartments

OBJECTIVE

An anti-angiogenic state has been implicated in the pathophysiology of preeclampsia, fetal growth restriction and fetal death. Vascular endothelial growth factor (VEGF), an indispensible angiogenic factor for embryonic and placental development exerts its angiogenic properties through the VEGF receptor (VEGFR)-2. A soluble form of this protein (sVEGFR-2) has been recently detected in maternal blood. The aim of this study was to determine if fetal death was associated with changes in the concentrations of sVEGFR-2 in maternal plasma and amniotic fluid.

STUDY DESIGN

Maternal plasma was obtained from patients with fetal death (n = 59) and normal pregnant women (n = 134). Amniotic fluid was collected from 36 patients with fetal death and the control group consisting of patients who had an amniocentesis and delivered at term (n = 160). Patients with fetal death were classified according to the clinical circumstances into the following groups: (1) unexplained; (2) preeclampsia and/or placental abruption; (3) chromosomal and/or congenital anomalies. Plasma and amniotic fluid concentrations of sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

RESULTS

(1) Patients with a fetal death had a significantly lower median plasma concentration of sVEGFR-2 than normal pregnant women (p < 0.001). The median plasma concentration of sVEGFR-2 in patients with unexplained fetal death and in those with preeclampsia/abruption, but not that of those with congenital anomalies, was lower than that of normal pregnant women (p = 0.006, p < 0.001 and p = 0.2, respectively); (2) the association between plasma sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 3.2; 95% CI: 1.4-7.3 per each quartile decrease in plasma sVEGFR-2 concentrations); (3) each subgroup of fetal death had a higher median amniotic fluid concentration of sVEGFR-2 than the control group (p < 0.001 for each); (4) the association between amniotic fluid sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 15.6; 95% CI: 1.5-164.2 per each quartile increase in amniotic fluid sVEGFR-2 concentrations); (5) among women with fetal death, there was no relationship between maternal plasma and amniotic fluid concentrations of sVEGFR-2 (Spearman Rho: 0.02; p = 0.9).

CONCLUSION

Pregnancies with a fetal death, at the time of diagnosis, are characterized by a decrease in the maternal plasma concentration of sVEGFR-2, but an increase in the amniotic fluid concentration of this protein. Although a decrease in sVEGFR-2 concentration in maternal circulation depends upon the clinical circumstances of fetal death, an increase in sVEGFR-2 concentration in amniotic fluid seems to be a common feature of fetal death. It remains to be determined if the perturbation in sVEGFR-2 concentrations in maternal and fetal compartments observed herein preceded the death of a fetus.

Redox responses in patients with sepsis: high correlation of thioredoxin-1 and macrophage migration inhibitory factor plasma levels

Background. Redox active substances (e.g., Thioredoxin-1, Macrophage Migration Inhibitory Factor) seem to be central hubs in the septic inflammatory process. Materials and Methods. Blood samples from patients with severe sepsis or septic shock (n = 15) were collected at the time of sepsis diagnosis (t0), and 24 (t24) and 48 (t48) hours later; samples from healthy volunteers (n = 18) were collected once; samples from postoperative patients (n = 28) were taken one time immediately after surgery. In all patients, we measured plasma levels of IL-6, TRX1 and MIF. Results. The plasma levels of MIF and TRX1 were significantly elevated in patients with severe sepsis or septic shock. Furthermore, TRX1 and MIF plasma levels showed a strong correlation (t0: r_sp = 0.720, ρ = 0.698/t24: r_sp = 0.771, ρ = 0.949). Conclusions. Proinflammatory/~oxidative and anti-inflammatory/~oxidative agents show a high correlation in order to maintain a redox homeostasis and to avoid the harmful effects of an excessive inflammatory/oxidative response.

Impact of the factor V Leiden mutation on the outcome of pneumococcal pneumonia: a controlled laboratory study

INTRODUCTION

Streptococcus (S.) pneumoniae is the most common cause of community-acquired pneumonia. The factor V Leiden (FVL) mutation results in resistance of activated FV to inactivation by activated protein C and thereby in a prothrombotic phenotype. Human heterozygous FVL carriers have been reported to be relatively protected against sepsis-related mortality. We here determined the effect of the FVL mutation on coagulation, inflammation, bacterial outgrowth and outcome in murine pneumococcal pneumonia.

METHODS

Wild-type mice and mice heterozygous or homozygous for the FVL mutation were infected intranasally with 2*106 colony forming units of viable S. pneumoniae. Mice were euthanized after 24 or 48 hours or observed in a survival study. In separate experiments mice were treated with ceftriaxone intraperitoneally 24 hours after infection and euthanized after 48 hours or observed in a survival study.

RESULTS

The FVL mutation had no consistent effect on activation of coagulation in either the presence or absence of ceftriaxone therapy, as reflected by comparable lung and plasma levels of thrombin-antithrombin complexes and fibrin degradation products. Moreover, the FVL mutation had no effect on lung histopathology, neutrophil influx, cytokine and chemokine levels or bacterial outgrowth. Remarkably, homozygous FVL mice were strongly protected against death due to pneumococcal pneumonia when treated with ceftriaxone, which was associated with more pronounced FXIII depletion; this protective effect was not observed in the absence of antibiotic therapy.

CONCLUSIONS

Homozygosity for the FVL mutation protects against lethality due to pneumococcal pneumonia in mice treated with antibiotics.

Fibrinogen and antithrombin in hematological patients with neutropenic fever

The value of plasma fibrinogen and antithrombin as predictors of severe sepsis was investigated in 69 adult hematological patients, who had altogether 93 periods of neutropenic fever. Patients had either acute myeloid leukemia or had received a high dose of chemotherapy supported by autologous stem cell transplantation. In febrile periods with severe sepsis, the median fibrinogen concentration at the start of the fever was significantly higher (5.0 g/L) than that without severe sepsis (4.5 g/L) (p=0.009). Normal plasma fibrinogen could rule out a group of patients with severe sepsis at the beginning of the fever. The antithrombin activity decreased, both in fever periods with severe sepsis and in those without. The decrease in antithrombin activity was found to be greater in fever periods characterized by severe sepsis. In conclusion, elevated plasma fibrinogen and constantly decreasing antithrombin were shown to be linked to the development of severe sepsis.

Blood coagulation disorders in septic patients

Host defense and blood coagulation are tightly connected and interacting systems, necessary for the integrity of an organism. Complex mechanisms regulate the intensity of a host response to invading pathogens or other potentially dangerous situations. Under regular conditions, this response is limited in time and located to the site of injury. Sometimes, however, systemic host response is overwhelming and disproportional and causes damage, not cure. Dependent on the genetical predisposition of the host, its current immunocompetence, or the type of injury, the reaction leads to the clinical picture of the different degrees of sepsis. Septic organ dysfunction is caused by intravascular fibrin deposition as a result of coagulation activation, anticoagulant breakdown, and shut down of fibrinolysis. This article describes the major pathophysiologic reactions in these situations and presents www.SepDIC.eu, an online tool on sepsis and associated coagulopathy.

Mechanisms, detection, and potential management of microcirculatory disturbances in sepsis

Despite improvements in resuscitation and treatment of sepsis, the morbidity and mortality remain unacceptably high. Microvascular dysfunction has been shown to play a significant role in the pathogenesis of sepsis and is a potential new target in the management of sepsis. Clinical studies, aided by new techniques that allow for real-time assessment of the microcirculation, have shown that disturbances in microcirculatory flow are common in sepsis and correlate with worse outcomes. Bedside measurement of microcirculatory perfusion has become simpler and more accessible, and may provide key insights into prognosis in sepsis and guide future therapeutics, much like mean arterial pressure (MAP), lactate, and mixed central oxygen saturation (SvO(2)) do now. The authors review here the role of microcirculatory dysfunction in sepsis and its potential role as a therapeutic target in sepsis.

Recipient tissue factor expression is associated with consumptive coagulopathy in pig-to-primate kidney xenotransplantation

Consumptive coagulopathy (CC) remains a challenge in pig-to-primate organ xenotransplantation (Tx). This study investigated the role of tissue factor (TF) expression on circulating platelets and peripheral blood mononuclear cells (PBMCs). Baboons (n = 9) received a kidney graft from pigs that were either wild-type (n = 2), alpha1,3-galactosyltransferase gene-knockout (GT-KO; n = 1) or GT-KO and transgenic for the complement-regulatory protein, CD46 (GT-KO/CD46, n = 6). In the baboon where the graft developed hyperacute rejection (n = 1), the platelets and PBMCs expressed TF within 4 h of Tx. In the remaining baboons, TF was detected on platelets on post-Tx day 1. Subsequently, platelet-leukocyte aggregation developed with formation of thrombin. In the six baboons with CC, TF was not detected on baboon PBMCs until CC was beginning to develop. Graft histopathology showed fibrin deposition and platelet aggregation (n = 6), but with only minor or no features indicating a humoral immune response (n = 3), and no macrophage, B or T cell infiltration (n = 6). Activation of platelets to express TF was associated with the initiation of CC, whereas TF expression on PBMCs was concomitant with the onset of CC, often in the relative absence of features of acute humoral xenograft rejection. Prevention of recipient platelet activation may be crucial for successful pig-to-primate kidney Tx.

The dynamic regulation of microcirculatory conduit function: features relevant to transfusion medicine

The microcirculation is not merely a passive conduit for red cell transport, nutrient and gas exchange, but is instead a dynamic participant contributing to the multiple processes involved in the maintenance of metabolic homeostasis and optimal end-organ function. The microcirculation's angioarchitechture and surface properties influence conduit function and flow dynamics over a wide spectrum of conditions, accommodating many different mechanical, pathological or organ-specific responses. The endothelium itself plays a critical role as the interface between tissues and blood components, participating in the regulation of coagulation, inflammation, vascular tone, and permeability. The complex nitric oxide pathways affect vasomotor tone and influence vascular conduit caliber and distribution density, alter thrombotic propensity, and modify adhesion molecule expression. Nitric oxide pathways also interact with red blood cells and free hemoglobin moieties in normal and pathological conditions. Red blood cells themselves may affect flow dynamics. Altered rheology and compromised NO bioavailability from medical storage or disease states impede microcirculatory flow and adversely modulate vasodilation. The integration of the microcirculation as a system with respect to flow modulation is delicately balanced, and can be readily disrupted in disease states such as sepsis. This review will provide a description of these varied and intricate functions of the microvasculature.

Macrophage migration inhibitory factor (MIF) and manganese superoxide dismutase (MnSOD) as early predictors for survival in patients with severe sepsis or septic shock

BACKGROUND

Severe sepsis, septic shock, and resulting organ failure appear as the most common cause of death in intensive care medicine. Inflammatory mediators (interleukin-6/IL-6), cell adhesion molecules (intercellular adhesion molecule-1/ICAM-1, vascular cell adhesion molecule-1/VCAM-1), and redox active substances (manganese superoxide dismutase/MnSOD, macrophage migration inhibitory factor/MIF) must be considered to be central hubs in the inflammatory process. However, their exact pathophysiologic function and prognostic value are still poorly understood.

MATERIALS AND METHODS

In total, 133 individuals (87 patients with severe sepsis or septic shock, 28 postoperative patients after major abdominal surgery, 18 healthy volunteers) were enrolled in the study. Blood samples from septic patients were collected within 24 h after the time of sepsis diagnosis, and 48 and 120 h later; samples from healthy volunteers were collected once, and samples from postoperative patients once immediately after surgery. In all patients we measured plasma levels of IL-6, sICAM-1, sVCAM-1, MnSOD, and MIF using enzyme linked immunosorbent assay (ELISA) kits.

RESULTS

Healthy volunteers and postoperative patients showed comparable levels of cell adhesion molecules. Furthermore, their redox system was activated in a comparable manner, whereas in postoperative patients IL-6 was significantly elevated. Plasma levels of inflammatory mediators, cell adhesion molecules and redox active substances were significantly elevated in septic patients. In patients with sepsis who had died, plasma levels of MIF and MnSOD were significantly elevated in comparison with survivors.

CONCLUSIONS

Our results therefore demonstrate that redox active substances may play an important role in the septic inflammatory response. MIF and MnSOD appear to be early predictors for survival in septic patients.

Managing septic shock

Although several successful clinical trials in the last 2-3 years have been greeted with enthusiasm by intensivists, severe sepsis and septic shock still have increasing incidence and more or less unchanged mortality. Within the last few years, the progress in sepsis research covering definitions, epidemiology, pathophysiology, diagnosis, and standard and adjunctive therapy as well as general measures such as treatment bundles is encouraging. In this report, a small selection of recent publications, focusing on the current discussion of activated protein C as well as the relevance of the Surviving Sepsis Campaign bundle therapy, is presented and the possible impact on clinical routine is discussed.

Therapeutic strategies targeting the endothelial glycocalyx: acute deficits, but great potential

Damage of the endothelial glycocalyx, which ranges from 200 to 2000 nm in thickness, decreases vascular barrier function and leads to protein extravasation and tissue oedema, loss of nutritional blood flow, and an increase in platelet and leucocyte adhesion. Thus, its protection or the restoration of an already damaged glycocalyx seems to be a promising therapeutic target both in an acute critical care setting and in the treatment of chronic vascular disease. Drugs that can specifically increase the synthesis of glycocalyx components, refurbish it, or selectively prevent its enzymatic degradation do not seem to be available. Pharmacological blockers of radical production may be useful to diminish the oxygen radical stress on the glycocalyx. Tenable options are the application of hydrocortisone (inhibiting mast-cell degranulation), use of antithrombin III (lowering susceptibility to enzymatic attack), direct inhibition of the cytokine tumour necrosis factor-alpha, and avoidance of the liberation of natriuretic peptides (as in volume loading and heart surgery). Infusion of human plasma albumin (to maintain mechanical and chemical stability of the endothelial surface layer) seems the easiest treatment to implement.

Activated protein C ameliorates coagulopathy but does not influence outcome in lethal H1N1 influenza: a controlled laboratory study

INTRODUCTION

Influenza accounts for 5 to 10% of community-acquired pneumonias and is a major cause of mortality. Sterile and bacterial lung injuries are associated with procoagulant and inflammatory derangements in the lungs. Activated protein C (APC) is an anticoagulant with anti-inflammatory properties that exert beneficial effects in models of lung injury. We determined the impact of lethal influenza A (H1N1) infection on systemic and pulmonary coagulation and inflammation, and the effect of recombinant mouse (rm-) APC here on.

METHODS

Male C57BL/6 mice were intranasally infected with a lethal dose of a mouse adapted influenza A (H1N1) strain. Treatment with rm-APC (125 microg intraperitoneally every eight hours for a maximum of three days) or vehicle was initiated 24 hours after infection. Mice were euthanized 48 or 96 hours after infection, or observed for up to nine days.

RESULTS

Lethal H1N1 influenza resulted in systemic and pulmonary activation of coagulation, as reflected by elevated plasma and lung levels of thrombin-antithrombin complexes and fibrin degradation products. These procoagulant changes were accompanied by inhibition of the fibrinolytic response due to enhanced release of plasminogen activator inhibitor type-1. Rm-APC strongly inhibited coagulation activation in both plasma and lungs, and partially reversed the inhibition of fibrinolysis. Rm-APC temporarily reduced pulmonary viral loads, but did not impact on lung inflammation or survival.

CONCLUSIONS

Lethal influenza induces procoagulant and antifibrinolytic changes in the lung which can be partially prevented by rm-APC treatment.

Selective blockade of endothelial NF-kappaB pathway differentially affects systemic inflammation and multiple organ dysfunction and injury in septic mice

Endothelium has long been considered both a source and a target of systemic inflammation. However, to what extent endothelial activation contributes to systemic inflammation remains unclear. This study addresses the relative contribution of endothelial activation to systemic inflammation and multiple organ dysfunction and injury (MOD/I) in an E. coli peritonitis model of sepsis. We prevented endothelial activation using transgenic (TG) mice that conditionally overexpress a mutant I-kappaBalpha, a NF-kappaB inhibitor, selectively on endothelium. TG mice and their transgene negative littermates (WT) were injected with saline or E. coli (10(8) CFU per mouse). At 7 h after E. coli infection, markers of systemic inflammation, endothelial activation, and MOD/I were assessed. WT-E. coli mice showed significantly increased serum levels of TNF-alpha, IL-1beta, IFN-gamma, IL-6, KC, and MCP-1; tissue levels of TNF-alpha, IL-6, KC, MCP-1, ICAM-1, and VCAM-1; endothelial leakage index in heart, lungs, liver, and kidney; significantly increased serum levels of AST, ALT, BUN, and creatinine; and increased mortality. Blockade of NF-kappaB-mediated endothelial activation in TG mice had no effects on serum levels of TNF-alpha, IL-1beta, IFN-gamma, IL-6, KC, and MCP-1 (markers of systemic inflammation), and tissue levels of TNF-alpha, IL-6, KC, and MCP-1, but significantly reduced tissue levels of ICAM-1 and VCAM-1 (markers of endothelial inflammation and activation) in those four organs. TG-E. coli mice displayed reversed endothelial leakage index; reduced serum levels of AST, ALT, BUN, and creatinine; and improved survival. Our data demonstrate that endothelial NF-kappaB-driven inflammatory response contributes minimally to systemic inflammation, but plays a pivotal role in septic MOD/I, suggesting that endothelium is mainly a target rather than a source of systemic inflammation.

Microcirculatory assessment in daily clinical practice - not yet ready but not too far!

ABSTRACT Shock is characterized by an alteration in tissue perfusion that may lead to tissue hypoxia. Recent guidelines recommend aggressive and early resuscitation therapy, but mortality rate is still unacceptably high. Unfortunately, traditional clinical surrogates used to guide resuscitation therapy poorly correlate with microcirculatory blood flow, a key determinant of tissue perfusion. New techniques that directly assess microcirculatory perfusion at the bedside have emerged as a complement to traditional macrohemodynamic parameters. These techniques have been supported by several studies showing microcirculatory alterations in different clinical settings. In addition, these microcirculatory alterations are related with outcome and persist regardless of arterial pressure normalization, being a better predictor of organ dysfunction and mortality than global hemodynamic and laboratory parameters. These findings allowed the concept of “microcirculatory-goal directed therapy”, which is now in its preliminary phase, as the impact of many interventions still needs to be assessed. Finally, microcirculation assessment has also been explored in other medical fields such as perioperative, systemic arterial hypertension, heart failure, and hyperviscosity syndromes. In this review, we shortly present the characteristics of microcirculation and the main determinants of capillary blood flow, and we discuss advantages and limitations of some recently available techniques to evaluate microcirculation at the bedside, and how they could be useful for the general clinician in daily practice.

Protective effect of carbon monoxide pre-conditioning on LPS-induced endothelial cell stress

Increasing evidence indicates that carbon monoxide (CO) may protect against several diseases including sepsis. The ability of CO pre-treatment to provide good pre-conditioning against lipopolysaccharide (LPS)-induced injury was tested using an in vitro model of primary culture of porcine aortic endothelial cells (pAEC). pAEC were exposed to CO (250 ppm) or air for 1 h prior to the addition of LPS (10 microg/ml). Hsp70, HO-1, and Egr-1 protein levels were determined as well as vascular endothelial growth factor (VEGF) secretion after 4, 7, and 15 h. The effect of CO on LPS-induced apoptosis was also detected at 15 h. CO pre-treatment before the addition of LPS, significantly reduced LPS-induced apoptosis. LPS induced an increase in the level of VEGF in culture media after 7 and 15 h, and a larger increase was detected in CO pre-treated cells. In addition, CO pre-treatment reduced LPS-induced Hsp70, HO-1, and Egr-1 protein expression. In conclusion, CO treatment seems to provide a good pre-conditioning for the prevention of LPS-induced endothelial injury.

Role of acute infection in triggering acute coronary syndromes

Acute coronary syndromes are a leading cause of morbidity and mortality worldwide. The mechanisms underlying the triggering of these events are diverse and include increased coronary and systemic inflammatory activity, dominant prothrombotic conditions, increased biomechanical stress on coronary arteries, variations in the coronary arterial tone, disturbed haemodynamic homoeostasis, and altered myocardial metabolic balance. There is experimental evidence that acute infections can promote the development of acute coronary syndromes, and clinical data strongly support a role for acute infections in triggering these events. In our Review, we summarise the pathogenesis of coronary artery disease and present the evidence linking acute infections with the development of acute coronary syndromes. Greater awareness of this association is likely to encourage research into ways of protecting patients who are at high risk.

Principles of source control in the management of sepsis

The term "source control" encompasses all those physical measures used to control a focus of invasive infection and to restore the optimal function of the affected area. Source-control measures can be categorized into 3 broad modalities: drainage controls the liquid component of an infection by converting a closed space infection to a controlled sinus or fistula; debridement is the physical removal of solid necrotic tissue (removal of an infected device can be considered a form of debridement); definitive measures seek to restore optimal function to the involved area. This article discusses specific approaches to source control in the abdomen, chest, and skin and soft tissues.

Clinical review: the role of biomarkers in the diagnosis and management of community-acquired pneumonia

In patients with community-acquired pneumonia, traditional criteria of infection based on clinical signs and symptoms, clinical scoring systems, and general inflammatory indicators (for example, leukocytosis, fever, C-reactive protein and blood cultures) are often of limited clinical value and remain an unreliable guide to etiology, optimal therapy and prognosis. Procalcitonin is superior to other commonly used markers in its specificity for bacterial infection (allowing alternative diagnoses to be excluded), as an indicator of disease severity and risk of death, and mainly as a guide to the necessity for antibiotic therapy. It can therefore be viewed as a diagnostic, prognostic, and perhaps even theragnostic test. It more closely matches the criteria for usefulness than other candidate biomarkers such as C-reactive protein, which is rather a nonspecific marker of acute phase inflammation, and proinflammatory cytokines such as plasma IL-6 levels that are highly variable, cumbersome to measure, and lack specificity for systemic infection. Elevated levels of pro-adrenomedullin, copeptin (which is produced in equimolar amounts to vasopressin), natriuretic peptides and cortisol are significantly related to mortality in community-acquired pneumonia, as are other prohormones such as pro-atrial natriuretic peptide, coagulation markers, and other combinations of inflammatory cytokine profiles. However, all biomarkers have weaknesses as well as strengths. None should be used on its own; and none is anything more than an aid in the exercise of clinical judgment based upon a synthesis of available clinical, physiologic and laboratory features in each patient.

Inflammation and coagulation

In the pathogenesis of sepsis, inflammation and coagulation play a pivotal role. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation leads to activation of coagulation, and coagulation also considerably affects inflammatory activity. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Pro-inflammatory cytokines and other mediators are capable of activating the coagulation system and down-regulating important physiologic anticoagulant pathways. Activation of the coagulation system and ensuing thrombin generation is dependent on expression of tissue factor and the simultaneous down-regulation of endothelial-bound anticoagulant mechanisms and endogenous fibrinolysis. Conversely, activated coagulation proteases may affect specific cellular receptors on inflammatory cells and endothelial cells and thereby modulate the inflammatory response.