Coagulation Activation and Tissue Necrosis in Meningococcal Septic Shock: Severely Reduced Protein C Levels Predict a High Mortality

Hematologic Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference

CONTEXT

Studies of organ dysfunction in children are limited by a lack of consensus around organ dysfunction criteria.

OBJECTIVES

To derive evidence-informed, consensus-based criteria for hematologic dysfunction in critically ill children.

DATA SOURCES

Data sources included PubMed and Embase from January 1992 to January 2020.

STUDY SELECTION

Studies were included if they evaluated assessment/scoring tools to screen for hematologic dysfunction and assessed outcomes of mortality, functional status, organ-specific outcomes, or other patient-centered outcomes. Studies of adults or premature infants, animal studies, reviews/commentaries, small case series, and non-English language studies with inability to determine eligibility were excluded.

DATA EXTRACTION

Data were abstracted from each eligible study into a standard data extraction form along with risk of bias assessment.

RESULTS

Twenty-nine studies were included. The systematic review supports the following criteria for hematologic dysfunction: thrombocytopenia (platelet count <100000 cells/µL in patients without hematologic or oncologic diagnosis, platelet count <30000 cells/µL in patients with hematologic or oncologic diagnoses, or platelet count decreased ≥50% from baseline; or leukocyte count <3000 cells/µL; or hemoglobin concentration between 5 and 7 g/dL (nonsevere) or <5 g/dL (severe).

LIMITATIONS

Most studies evaluated pre-specified thresholds of cytopenias. No studies addressed associations between the etiology or progression of cytopenias overtime with outcomes, and no studies evaluated cellular function.

CONCLUSIONS

Hematologic dysfunction, as defined by cytopenia, is a risk factor for poor outcome in critically ill children, although specific threshold values associated with increased mortality are poorly defined by the current literature.

Protein C system in preterm babies with chronic lung disease: Prospective study

BACKGROUND

Chronic lung disease (CLD) is a major neonatal pulmonary disorder associated with inflammation. Recent studies have shown that protein C anticoagulant pathways, such as those for protein C (PC), protein S (PS), and thrombomodulin (TM), could be useful indices for reflecting pulmonary injury. However, the involvement of these factors in preterm infants with very low birthweight (VLBW) who have developed CLD remains to be investigated. Here, we investigated whether PC pathway-related factors could predict the development of CLD in preterm infants with VLBW.

METHODS

We collected plasma samples from 26 preterm infants with VLBW (13 each from those with and without CLD) at the time of birth and measured TM, PC, and PS levels in their plasmas. We analyzed prospectively the relationship between these factors in infants with and without CLD.

RESULTS

There were significant differences in gestational age, birthweight, Apgar score (5 min), and duration of mechanical ventilation between the CLD and non-CLD groups. No significant differences in the PC and PS levels at birth were observed between the two groups, whereas the TM levels in the CLD group were significantly higher than those in the non-CLD group (P = 0.013). The TM levels correlated with gestational age and duration of mechanical ventilation. However, covariance analysis demonstrated that gestational age was significantly associated with TM levels, and consequently, development of CLD was not associated with TM level at birth.

CONCLUSIONS

Thrombomodulin, PC, and PS levels at birth could not predict the development of CLD in preterm infants with VLBW.

Fibrinolytic Alterations in Sepsis: Biomarkers and Future Treatment Targets

Sepsis is a life-threatening condition which develops as a dysregulated immune response in the face of infection and which is associated with profound hemostatic disturbances and in the most extreme cases disseminated intravascular coagulation (DIC). In addition, the fibrinolytic system is subject to alterations during infection and sepsis, and impaired fibrinolysis is currently considered a key player in sepsis-related microthrombus formation and DIC. However, we still lack reliable biomarkers to assess fibrinolysis in the clinical setting. Furthermore, drugs targeting the fibrinolytic system have potential value in sepsis patients with severe fibrinolytic disturbances, but these are still being tested in the preclinical stage. The present review provides an overview of key fibrinolytic changes in sepsis, reviews the current literature on potential laboratory markers of altered fibrinolysis in adult sepsis patients, and discusses future perspectives for diagnosis and treatment of fibrinolytic disturbances in sepsis patients.

Symmetrical peripheral gangrene in critical illness

Symmetrical peripheral gangrene (SPG) is a disabling complication that affects a small proportion of patients who survive critical illness. Its pathogenesis reflects profoundly disturbed procoagulant-anticoagulant balance in susceptible tissue beds secondary to circulatory shock (cardiogenic, septic). There is a characteristic SPG triad: (a) shock (hypotension, lactic acidemia, normoblastemia, multiple organ dysfunction), (b) disseminated intravascular coagulation (DIC), and (c) natural anticoagulant depletion (protein C, antithrombin). In recent years, risk factors for natural anticoagulant depletion have been identified, most notably acute ischemic hepatitis ("shock liver"), which is seen in at least 90% of patients who develop SPG. Moreover, there is a characteristic time interval (2-5 days, median 3 days) between the onset of shock/shock liver and the beginning of ischemic injury secondary to peripheral microthrombosis ("limb ischemia with pulses"), reflecting the time required to develop severe depletion in hepatically-synthesized natural anticoagulants. Other risk factors for natural anticoagulant depletion include chronic liver disease (e.g., cirrhosis) and, possibly, transfusion of colloids (albumin, high-dose immunoglobulin) lacking coagulation factors. A causal role for vasopressor therapy is unproven and is unlikely; this is because critically ill patients who develop SPG do so usually after at least 36-48 hours of vasopressor therapy, implicating a time-dependent pathophysiological mechanism. The most plausible explanation is a progressive time-dependent decline in key natural anticoagulant factors, reflecting ongoing DIC ("consumption"), proximate liver disease whether acute or chronic ("impaired production"), and colloid administration ("hemodilution"). Given these evolving concepts of pathogenesis, a rationale approach to prevention/treatment of SPG can be developed.

Purpura fulminans manifesting with Staphylococcus aureus endocarditis: a case report

BACKGROUND

Purpura fulminans (PF) is a haematologic emergency that can occur in the setting of severe septic shock. Its pathophysiology is not well-understood; however, some evidence suggests it may be mediated by excessive protein C consumption.

CASE SUMMARY

In this case report, we describe a patient with PF secondary to methicillin-resistant Staphylococcus aureus endocarditis. She presented with severe septic shock and, despite haemodynamic improvement, developed a significant purpuric rash. Diagnostic work-up was notable for severely decreased serum levels of protein C. This patient was successfully treated with protein C concentrate and surgical valve replacement.

DISCUSSION

While PF is rarely associated with S. aureus infection, this presentation may be more frequently encountered among clinicians in the current opioid epidemic. Quick recognition is crucial and a multidisciplinary approach, including intravenous infusion of protein C, may be considered.

Pathogen interactions with endothelial cells and the induction of innate and adaptive immunity

There are over 10 trillion endothelial cells (EC) that line the vasculature of the human body. These cells not only have specialized functions in the maintenance of homeostasis within the circulation and various tissues but they also have a major role in immune function. EC also represent an important replicative niche for a subset of viral, bacterial, and parasitic organisms that are present in the blood or lymph; however, there are major gaps in our knowledge regarding how pathogens interact with EC and how this influences disease outcome. In this article, we review the literature on EC-pathogen interactions and their role in innate and adaptive mechanisms of resistance to infection and highlight opportunities to address prominent knowledge gaps.

Disseminated intravascular coagulation: an update on pathogenesis and diagnosis

INTRODUCTION

Activation of the hemostatic system can occur in many clinical conditions. However, a systemic and strong activation of coagulation complicating clinical settings such as sepsis, trauma or malignant disease may result in the occurrence disseminated intravascular coagulation (DIC). Areas covered: This article reviews the clinical manifestation and relevance of DIC, the various conditions that may precipitate DIC and the pathogenetic pathways underlying the derangement of the hemostatic system, based on clinical and experimental studies. In addition, the (differential) diagnostic approach to DIC is discussed. Expert commentary: In recent years a lot of precise insights in the pathophysiology of DIC have been uncovered, leading to a better understanding of pathways leading to the hemostatic derangement and providing points of impact for better adjunctive treatment strategies. In addition, simple diagnostic algorithms have been developed and validated to establish a diagnosis of DIC in clinical practice.

Coordinated responses of natural anticoagulants to allogeneic stem cell transplantation and acute GVHD - A longitudinal study

Background

Allogeneic stem cell transplantation (SCT) enhances coagulation via endothelial perturbation and inflammation. Role of natural anticoagulants in interactions between coagulation and inflammation as well as in acute graft-versus-host disease (GVHD) are not well known. The purpose of this study was to define changes in natural anticoagulants over time in association with GVHD.

Patients and methods

This prospective study included 30 patients who received grafts from siblings (n = 19) or unrelated donors (n = 11). Eight patients developed GVHD. Standard clinical assays were applied to measure natural anticoagulants, represented by protein C (PC), antithrombin (AT), protein S (PS), complex of activated PC with its inhibitor (APC-PCI) and by markers of endothelial activation: Factor VIII coagulant activity (FVIII:C) and soluble thrombomodulin (s-TM) at 6–8 time points over three months.

Results

Overall, PC, AT and FVIII:C increased in parallel after engraftment. Significant correlations between PC and FVIII:C (r = 0.64–0.82, p<0.001) and between PC and AT (r = 0.62–0.81, p<0.05) were observed at each time point. Patients with GVHD had 21% lower PC during conditioning therapy and 55% lower APC-PCI early after transplantation, as well as 37% higher values of s-TM after engraftment. The GVHD group had also increases of PC (24%), FVIII: C (28%) and AT (16%) three months after transplantation.

Conclusion

The coordinated activation of natural anticoagulants in our longitudinal study indicates the sustained ability of adaptation to endothelial and inflammatory activation during allogenic SCT treatment. The suboptimal control of coagulation by natural anticoagulants at early stage of SCT may contribute to onset of GVHD.

Evolution of Factor V Leiden

Factor V Leiden is a procoagulant mutation associated with venous and arterial thrombosis and pregnancy complications. Its high prevalence of 5% in Caucasians suggests that there are evolutionary benefits as well. Carriers are indeed reported to have various advantageous phenotypes related to haemostasis, inflammation and fertility: less acute blood loss; less menstrual blood loss; decreased risk of intracranial haemorrhage; milder phenotypes of haemophilia; higher survival in and lower susceptibility to severe sepsis; higher survival in acute respiratory distress syndrome; less severe diabetic nephropathy and higher fecundity in both men and women. Not all these associations come from high quality adequately powered studies and many have not been confirmed by further research. The evolutionary influence of the alleged associations varies and is difficult to establish, partly due to a shift over time in risk factors of the diseases concerned. For most of the phenotypes possible mechanistic explanations can be provided. The procoagulant phenotype and perhaps also certain pregnancy complications follow from activated protein C (APC) resistance. Elevated APC levels possibly mediate anti-inflammatory effects. Higher sperm counts and more successful embryo implantation seem to play a role in the increased fecundity.

Purpura Fulminans: Mechanism and Management of Dysregulated Hemostasis

Purpura fulminans (PF) is a highly thrombotic subtype of disseminated intravascular coagulation that can accompany severe bacterial, and more rarely, viral infections. PF is associated with an extremely high mortality rate, and patients often die of overwhelming multisystemic thrombosis rather than septic shock. Survivors typically experience amputation of involved extremities and significant scarring in affected areas. Despite the devastating clinical course associated with this hemostatic complication of infection, the mechanism of PF remains poorly understood. Severe acquired deficiency of protein C and dysfunction of the protein C-thrombomodulin pathway as well as other systems that exert a negative regulatory effect on coagulation have been implicated. Management of PF involves treatment of the underlying infection, aggressive anticoagulation, and robust transfusion support aimed at correcting acquired deficiencies in natural anticoagulant proteins. In this review, we address the diagnosis and management of PF with a focus on a rational approach to this condition informed by the available data. Proposed mechanisms underlying the dysregulation of coagulation seen in PF are also covered, and implications for therapy are discussed.

Invited review: Neisseria meningitidis lipopolysaccharides in human pathology

Neisseria meningitidis causes meningitis, fulminant septicemia or mild meningococcemia attacking mainly children and young adults. Lipopolysaccharides (LPS) consist of a symmetrical hexa-acyl lipid A and a short oligosaccharide chain and are classified in 11 immunotypes. Lipid A is the primary toxic component of N. meningitidis . LPS levels in plasma and cerebrospinal fluid as determined by Limulus amebocyte lysate (LAL) assay are quantitatively closely associated with inflammatory mediators, clinical symptoms, and outcome. Patients with persistent septic shock, multiple organ failure, and severe coagulopathy reveal extraordinarily high levels of LPS in plasma. The cytokine production is compartmentalized to either the circulation or to the subarachnoid space. Mortality related to shock increases from 0% to > 80% with a 10-fold increase of plasma LPS from 10 to 100 endotoxin units/ml. Hemorrhagic skin lesions and thrombosis are caused by up-regulation of tissue factor which induces coagulation, and by inhibition of fibrinolysis by plasminogen activator inhibitor 1 (PAI-1). Effective antibiotic treatment results in a rapid decline of plasma LPS (half-life 1—3 h) and cytokines, and reduced generation of thrombin, and PAI-1. Early antibiotic treatment is mandatory. Three intervention trials to block lipid A have not significantly reduced the mortality of meningococcal septicemia.

Disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is an acquired syndrome characterized by widespread intravascular activation of coagulation that can be caused by infectious insults (such as sepsis) and non-infectious insults (such as trauma). The main pathophysiological mechanisms of DIC are inflammatory cytokine-initiated activation of tissue factor-dependent coagulation, insufficient control of anticoagulant pathways and plasminogen activator inhibitor 1-mediated suppression of fibrinolysis. Together, these changes give rise to endothelial dysfunction and microvascular thrombosis, which can cause organ dysfunction and seriously affect patient prognosis. Recent observations have pointed to an important role for extracellular DNA and DNA-binding proteins, such as histones, in the pathogenesis of DIC. The International Society on Thrombosis and Haemostasis (ISTH) established a DIC diagnostic scoring system consisting of global haemostatic test parameters. This scoring system has now been well validated in diverse clinical settings. The theoretical cornerstone of DIC management is the specific and vigorous treatment of the underlying conditions, and DIC should be simultaneously managed to improve patient outcomes. The ISTH guidance for the treatment of DIC recommends treatment strategies that are based on current evidence. In this Primer, we provide an updated overview of the pathophysiology, diagnosis and management of DIC and discuss the future directions of basic and clinical research in this field.

Shock, acute disseminated intravascular coagulation, and microvascular thrombosis: is 'shock liver' the unrecognized provocateur of ischemic limb necrosis?

For unknown reasons, a small minority of critically ill patients with septic or cardiogenic shock, multiorgan failure, and disseminated intravascular coagulation develop symmetrical acral (distal extremity) limb loss due to microvascular thrombosis ('limb gangrene with pulses'). Case reports have described preceding 'shock liver' in some critically ill patients who developed such a picture of ischemic limb necrosis. This suggests that profoundly disturbed procoagulant-anticoagulant balance featuring uncontrolled generation of thrombin-resulting from failure of the protein C and antithrombin natural anticoagulant systems due to insufficient hepatic synthesis of these crucial proteins-could explain the microvascular thrombosis and associated limb loss. We hypothesize that shock liver is the key predisposing risk factor underlying ischemic limb necrosis in the majority of patients who develop this complication in the setting of acute disseminated intravascular coagulation complicating septic or cardiogenic shock. As shock liver precedes onset of limb ischemia by several days, therapeutic intervention may be possible.

Prediction of survival in patients suspected of disseminated intravascular coagulation

BACKGROUND

Although antithrombin (AT), protein C (PC), and antiplasmin (AP) are consumed during disseminated intravascular coagulation (DIC), their association with mortality in patients initially suspected of acute DIC is unknown. We examined how these proteins associate with mortality in consecutive patients initially suspected of DIC, fulfilling or not fulfilling overt DIC criteria.

METHODS

All consecutive patients clinically suspected of acute DIC during 5 years at a tertiary referral hospital were scored according to overt International Society of Thrombosis and Haemostasis (ISTH) DIC criteria. The influence of ISTH DIC score and measurements of AT, PC, and AP measured in all on mortality was assessed.

RESULTS

During 1825 occurrences in 1814 patients, 91 fulfilled ISTH criteria for overt DIC (score ≥ 5). Both 28-day and 1-year mortality increased progressively as AT and in particular PC decreased. AT and PC correlated inversely with ISTH score (AT: R(2 ) = 0.14, P < 0.001, PC: R(2 ) = 0.21, P < 0.001). AP decreased when ISTH score of > 3 was reached. The 28-day mortality was 3%, 11%, 16%, 23%, 35%, and 52% and 1-year mortality 5%, 18%, 24%, 36%, 54%, and 63%, respectively for patients with an ISTH score of 0, 1, 2, 3, 4, and ≥5 (P < 0.001 for all).

CONCLUSIONS

Lowered AT and in particular PC activity was predictive of mortality risk upfront in critically ill patients suspected of acute DIC. Mortality in patients suspected of acute DIC increased progressively across the spectrum of the overt ISTH score and not only in those fulfilling overt DIC criteria.

Prognostic markers of meningococcal disease in children: recent advances and future challenges

Meningococcal disease is a life-threatening condition and a major cause of bacterial meningitis and sepsis worldwide. In many fatal cases, meningococcal disease is rapidly progressive and death occurs within hours of the initial symptoms. The early identification of patients at high risk of death would be useful in order to provide aggressive and more personalized clinical management with the proper level of supportive therapy required, contributing to an improvement in the survival rate and reduction in sequelae. The current study aims to review the current published literature about prognostic markers of meningococcal sepsis in children in order to elaborate conclusions and recommendations that could guide clinical practice and further research.

Diagnosis and treatment of disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a condition in which systemic activation of coagulation without a specific localization occurs, resulting in extensive formation of intravascular fibrin, particularly in small and midsize vessels. Disseminated intravascular coagulation may lead to several altered coagulation parameters, including a low platelet count, abnormal global clotting assays, low levels of physiological anticoagulant proteases, or increased fibrin degradation products. Also, more complex assays for activation of coagulation factors or pathways may indicate involvement of these molecules in DIC. None of these tests alone, however, can accurately ascertain or rebuff a diagnosis of DIC. Nonetheless, a combination of readily available routine assays may be instrumental in establishing a diagnosis of DIC and can also be useful to point to a subset of patients with DIC that may need definite, often costly, interventions in the hemostatic system. Current insights on relevant etiological pathways that may contribute to the occurrence of DIC have led to innovative therapeutic and adjunctive approaches to patient with DIC. Management options directed at the amelioration of hemostatic activation may tentatively be indicated and were found to be advantageous in experimental and clinical investigations. These treatments encompass elimination of tissue factor-mediated thrombin generation or restitution of normal anticoagulant function.

The role of protein C in sepsis

During the past 15 years, several anti-inflammatory treatments have failed to reduce mortality in patients with severe sepsis. However, recent evidence indicates that coagulation abnormalities in sepsis may play a major role in the pathogenesis of multiple organ failure and the high mortality rate in patients with severe sepsis. Interestingly, blockade of the coagulant pathway can inhibit both procoagulant and proinflammatory pathways in sepsis. Protein C, a natural anticoagulant, interrupts several of the pathophysiologic pathways in sepsis. Acquired protein C deficiency is present in the majority of septic patients and is associated with unfavorable outcomes. Protein C replacement therapy was effective in preclinical animal models of sepsis in reducing end-organ damage and mortality. Recent clinical trials of protein C replacement in human meningococcemia resulted in a markedly decreased morbidity and mortality. And, most importantly, in a recently completed large, randomized trial of activated protein C treatment in severe sepsis, mortality was reduced from 30.8% in the placebo group to 24.7% in the treatment group at 28 days. Thus, there is new evidence that mortality can be reduced among patients with severe sepsis through the use of a new therapy that inhibits the procoagulant and the inflammatory cascades.

Protein C zymogen in adults with severe sepsis or septic shock

INTRODUCTION

Activated protein C is associated with a risk of bleeding and its effects on survival in septic shock patients are questionable. Protein C zymogen has no risk of bleeding and improves the outcome of patients with septic shock. We hereby describe the largest published case series of adult patients receiving protein C zymogen.

DESIGN, SETTING AND PARTICIPANTS

A prospective study on 23 adult patients with severe sepsis or septic shock, two or more organ failures and at high risk for bleeding, treated with protein C zymogen (50IU/kg bolus followed by continuous infusion of 3IU/kg/h for 72h).

RESULTS

The Z-test evidenced a significant reduction between the expected mortality (53%) and the observed mortality 30% (Z value=1.99, p=0.046) in our sample population. Protein C levels increased from 34±18% to 66±22% at 6h after PC bolus (p<0.001), and kept on increasing during 72h of administration (p<0.001 to baseline). Sequential Organ Failure Assessment (SOFA), score of organ dysfunction, decreased from baseline to 7 days after administration of protein C from 14±2 to 7±4 (p<0.001). No adverse event drug related was noted.

CONCLUSION

Protein C zymogen administration is safe and its use in septic patients should be investigated through a randomized controlled trial.

Enhanced thrombin generation and depressed anticoagulant function in children with pneumonia

AIMS

To clarify the status of the coagulation system in children with community-acquired pneumonia.

METHODS

Coagulation activation markers (prothrombin fragment F1 + 2, thrombin-antithrombin complexes, D-dimer), the natural anticoagulants (antithrombin, protein C and S) and tissue factor were measured in 28 consecutive children with pneumonia on admission to the hospital. Patients were divided into those with either bacterial-type pneumonia (at least two of the following three criteria: plasma C-reactive protein (CRP) >80 mg/L, white blood cell count >15 × 10(9) /L and alveolar infiltrates on the chest radiograph) or viral-type pneumonia.

RESULTS

The majority of the patients (79%) showed elevation of at least one of the three coagulation activation markers. Plasma CRP concentration correlated with F1 + 2 (R = 0.44, p < 0.05) and D-dimer (R = 0.71, p < 0.0001). Patients with bacterial-type pneumonia (n = 17) had higher D-dimer levels (p < 0.05) and lower levels of antithrombin (p = 0.005) and protein C (p = 0.08) than the patients with viral-type pneumonia.

CONCLUSIONS

Children with community-acquired bacterial-type pneumonia show distinctive changes in their coagulation system. The finding of coagulation system activation and depressed function of natural anticoagulants in uncomplicated pneumonia helps to understand the rapid and unpredictable changes observed in the coagulation status in patients with more severe forms of disease.

Purpura fulminans caused by community-associated methicillin-resistant Staphylococcus aureus

Sepsis-induced purpura fulminans is a rare but life-threatening condition characterized by rapidly progressive hemorrhagic infarction of the skin due to dermal vascular thrombosis resulting in tissue loss and severe scarring. Although most commonly related to meningococcal or invasive group A streptococcal disease, it may also be caused by several other bacterial or viral pathogens including Pneumococcus and Varicella. Purpura fulminans associated with Staphylococcus aureus sepsis is rare but has been reported in adults. However, the syndrome is very unusual in children, and to our knowledge, only 2 cases of staphylococcal purpura fulminans have been reported in children, both due to methicillin-susceptible S aureus in the United Kingdom. We report the first well-described case of purpura fulminans due to community-associated methicillin-resistant S aureus in a child.

Activated protein C utilizes the angiopoietin/Tie2 axis to promote endothelial barrier function

Activated protein C (APC) is an anticoagulant, approved as a treatment for severe sepsis, that can prevent apoptosis, inflammation, and vascular leakage. The aim of this study was to investigate whether APC protects endothelial barrier function through the angiopoietin (Ang)/Tie2 axis. APC significantly up-regulated gene and protein expression of Tie2 and Ang1 in a dose (0.01-10 microg/ml)- and time (0.5-24 h)-dependent manner in human umbilical vein endothelial cells (HUVECs). Interestingly, it markedly inhibited Ang2 with an IC(50) of approximately 0.1 microg/ml. HUVEC permeability, measured using Evans blue dye transfer, was significantly reduced in the presence of APC, and, in concordance, the tight junction associated protein zona occludens (ZO)-1 was up-regulated and localized peripherally around cells, compared with controls. Smooth muscle cell migration toward APC-stimulated HUVECs was elevated compared with unstimulated cells. Blocking antibodies and small interfering (si) RNA treatment, compared with isotype (IgG) or scrambled siRNA controls, showed that APC requires 3 receptors, the endothelial protein C receptor, protease-activated receptor 1, and Tie2 to perform all these barrier stabilization functions. In summary, this study demonstrates that APC has novel effects on the Ang/Tie2 axis, which enhance endothelial barrier function and are likely to contribute to its therapeutic effect in sepsis and other diseases associated with vascular leakage.-Minhas, N., Xue, M., Fukudome, K., Jackson, C. J. Activated protein C utilizes the angiopoietin/Tie2 axis to promote endothelial barrier function.

The effect of fibrinolytic enzyme FIIa from Agkistrodon acutus venom on disseminated intravascular coagulation in rabbits

A novel fibrinolytic enzyme, FII(a), was isolated from Agkistrodon acutus venom, which can degrade fibrin/fibrinogen and dissolve thrombus without activating plasminogen or influencing the activities of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1). In this study, we evaluated the effect of FII(a) on lipopolysaccharide (LPS)-induced experimental disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100-microg/kg/h LPS for a period of 6 h. Seven groups were established: LPS control, FII(a) (0.1, 0.3, and 0.6 mg/kg/h, respectively), heparin control (100 IU/kg/h), heparin + FII(a) (heparin 100 IU/kg/h associated with FII(a) 0.3 mg/kg/h), and a saline control group. A continuous injection of LPS induced a gradual impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. The intravenous administration of FII(a) improved the concentration of fibrinogen, the activities of protein C, plasminogen, t-PA, antithrombin III (ATIII), and PAI-1. Kidney fibrin deposition and the mortality also decreased. In the in vitro experiments, FII(a) can degrade fibrin/fibrinogen and high-dose FII(a) enhanced the activity of protein C. These findings suggest that the effects of FII(a) on LPS-induced DIC were from fibrinogen degradation and enhanced protein C activity. The simultaneous administration of FII(a) and heparin further improved all the hemostatic parameters, including decreased kidney fibrin deposition, and none of the rabbits died within 24 h, which indicates that the effects were mediated by degradation of fibrin/fibrinogen together with thrombin inhibition. We conclude that FII(a) may be useful in the treatment of DIC.

Protein C promoter polymorphisms associate with sepsis in children with systemic meningococcemia

Meningococcal disease may present as sepsis, meningitis or a combination of both. Protein C (PC) is an important regulator of thrombin activity. Two polymorphisms in the promoter region of PC (C-1654T, A-1641G) have been shown to affect PC levels. In patients with meningococcal sepsis, low PC levels have been correlated with increased severity and poor outcome. We established a multicenter case-control study to determine whether PC promoter polymorphisms are associated with occurrence and outcome of meningococcal disease and sepsis. 288 previously healthy children with meningococcal infection from 97 pediatric hospitals in Germany, Switzerland, Italy, and Austria and 309 healthy controls were included in the study. A strong age-dependant effect was found. Patients younger than 1 year carried significantly more often the CG-CG genotype than healthy controls (28.6% vs. 17.8%, P = 0.04). Carriers of the CG allele showed a 3.43-fold increased odds ratio (OR) to develop sepsis (95% CI: 1.05-11.20; 85.7% vs. 63.6%, P = 0.036). The TA-TA genotype conferred a protective role for the development of sepsis (P = 0.017) with a Haldane OR of 0.09 (95% CI: 0.01-0.94). Systolic blood pressure values were significantly decreased in patients carrying the CG-CG genotype (70 vs. 86 mmHg, P = 0.005), and the need for adrenergic support significantly higher (70% vs. 26%, P = 0.018), resulting in an OR of 6.61 (95% CI: 1.28-34.14). These findings show that in young children PC promoter genotype is associated with susceptibility for meningococcal disease, the development of meningococcal sepsis, lower blood pressure, and need for adrenergic support.

Low plasma protein C values predict mortality in low birth weight neonates with septicemia

BACKGROUND

Septicemia activates coagulation and decreases activated protein C (APC). Low APC in adults is associated with multiorgan dysfunction and mortality, but such data in neonates are lacking. Being deficient in APC, neonates may be especially vulnerable to the effects of low APC.

METHODS

This cohort study was conducted on 40 neonates with severe bacterial septicemia to determine the relationship between plasma APC values and mortality, time to mortality, and hazard of dying. Low birth weight neonates with sepsis, organ dysfunction, and systemic inflammatory response syndrome were enrolled after parental consent. Plasma APC was assayed at enrollment and subjects were followed for 14 days from enrollment. Low birth weight neonates, who had major malformations, severe birth asphyxia, or received blood products before APC assay, were excluded.

PRIMARY OUTCOME

comparison of APC level between survivors and nonsurvivors.

SECONDARY OUTCOMES

survival with low versus normal APC; and hazard ratio of APC, adjusted for birth weight, Score for Neonatal Acute Physiology and number of affected organs.

RESULTS

Forty of 74 eligible neonates were included. Twenty-five of the enrolled neonates died within 14 days. APC levels in nonsurvivors were lower than in survivors [median (interquartile range) %, 15 (4.5-21) versus 33 (18-55); P < 0.001]. Ten nonsurvivors versus 1 survivor had low APC (P = 0.03). Positive predictive value (PPV) of low APC values for mortality was 90.9%. Survival in the low APC group (n = 11) was shorter than in normal APC group [median (95% confidence interval) days, 3 (2.3-3.7) versus 10, P value <0.001]. APC value was independently associated with hazard of dying [adjusted risk 0.95 (95% confidence interval 0.92-0.99), P = 0.02]. Each 1% rise in APC decreased the hazard of dying by 5%.

CONCLUSIONS

Mortality was higher and duration of survival shorter in septic neonates with lower plasma ACP. The latter was an independent predictor of the hazard of dying.

Epidemic meningitis, meningococcaemia, and Neisseria meningitidis

Meningococcus, an obligate human bacterial pathogen, remains a worldwide and devastating cause of epidemic meningitis and sepsis. However, advances have been made in our understanding of meningococcal biology and pathogenesis, global epidemiology, transmission and carriage, host susceptibility, pathophysiology, and clinical presentations. Approaches to diagnosis, treatment, and chemoprophylaxis are now in use on the basis of these advances. Importantly, the next generation of meningococcal conjugate vaccines for serogroups A, C, Y, W-135, and broadly effective serogroup B vaccines are on the horizon, which could eliminate the organism as a major threat to human health in industrialised countries in the next decade. The crucial challenge will be effective introduction of new meningococcal vaccines into developing countries, especially in sub-Saharan Africa, where they are urgently needed.

Peritoneal lavage with activated protein C alters compartmentalized coagulation and fibrinolysis and improves survival in polymicrobial peritonitis

OBJECTIVE

During peritonitis, intra-abdominal fibrin entraps bacteria and hampers their elimination. Systemic administration of anticoagulant activated protein C improves survival in patients with severe sepsis, but its precise mode of action is unclear. This study in polymicrobial peritonitis assessed the effects of local activated protein C administration in peritoneal lavage fluid on coagulation, fibrinolysis, and survival.

DESIGN

Prospective, randomized study.

SETTING

University-based research laboratory.

SUBJECTS

C57BL/6 mice.

INTERVENTIONS

Twenty-four hours after induction of peritonitis by cecal ligation and puncture, mice underwent peritoneal lavage with activated protein C (1.0 microg/mL) or saline. Peritoneal lavage fluid, blood, and lungs were sampled after 24, 48, or 72 hrs (n = 8/group/time point). For survival analysis, maximum observation was 96 hrs (n = 22/group). Clotting time, tissue factor expression, thrombin-antithrombin complexes, fibrin degradation products (D-dimers), plasminogen activator, and plasminogen activator inhibitor were used to assess coagulation and fibrinolysis responses.

MEASUREMENTS AND MAIN RESULTS

Activated protein C lavage reduced abdominal bacterial load, abdominal and pulmonary clotting times, D-dimers (p < .05 vs. saline), pulmonary tissue factor expression, and fibrin depositions, without clear effects on systemic thrombin generation. Activated protein C lavage decreased plasma and abdominal tissue plasminogen activator levels with increased inhibitor plasminogen activator inhibitor-1 levels (p < .05) but had reverse effects on pulmonary fibrinolysis. Survival improved from 55% (saline) to 80% after intra-abdominal activated protein C administration (p = .03).

CONCLUSIONS

Peritoneal lavage with activated protein C may rebalance coagulation and fibrinolysis within compartments and improve survival in polymicrobial peritonitis.

Treatment of adult patients with sepsis-induced coagulopathy and purpura fulminans using a plasma-derived protein C concentrate (CeprotinR)

BACKGROUND AND OBJECTIVES

The aim of this study was to document the effects of supplementation with a plasma-derived protein C concentrate in adult patients with infectious purpura fulminans.

MATERIALS AND METHODS

We report the effect of the administration of a human protein C concentrate (Ceprotin, Baxter, Vienna, Austria) in eight adult patients with purpura fulminans. Five patients received the concentrate as level-adjusted continuous infusion (10 U/kg/h, target protein C activity 100%) and three patients received the concentrate as bolus infusions (100 U/kg every 6 h) in addition to standard sepsis therapy. Heparin, fresh-frozen plasma, antithrombin- and fibrinogen concentrates, low-dose rtPA, and platelet transfusions were given when appropriate.

RESULTS

Six patients had overt disseminated intravascular coagulation: platelets, 19 g/l; fibrinogen, 60 mg/dl; antithrombin, 47%; prothrombin time, 32%; activated partial thromboplastin time (APTT), 88 s; d-dimer, 66 microg/ml; protein C activity, 29% (medians). Five patients had septic shock, six renal failure and four respiratory failure. Patients received between 5000 and 77,000 U of protein C concentrate over 2.5 days (median); the protein C activity increased to 184% (median) and coagulopathy resolved within 3 days in seven of the eight patients. Six patients survived, one died early from fulminant sepsis, and one died after 14 days from candida sepsis.

CONCLUSIONS

Our data suggest that treatment with a plasma-derived protein C zymogen concentrate might be a useful support in adult patients with purpura fulminans.

Protein C as an early marker of severe septic complications in diffuse secondary peritonitis

To evaluate the predictive value of protein C as a marker of severity in patients with diffuse peritonitis and abdominal sepsis, protein C levels were repeatedly determined and compared with serum levels of antithrombin III, plasminogen, alpha(2)-antiplasmin, Plasminogen activator inhibitor, D-dimer, C1-inhibitor, high molecular weight kininogen, and the C5a, C5b-9 fragments of the complement system. We carried out a prospective study from 44 patients with severe peritonitis confirmed by laparotomy and 15 patients undergoing elective ventral hernia repair who acted as controls. Analyzed biochemical parameters were determined before operations and on days 1, 2, 3, 5, 7, 10, and 14 after operations. For the study group, preoperative average protein C level was significantly lower in the patients who developed septic shock in the late course of the disease, with lethal outcome, than in the patients with severe peritonitis and sepsis who survived (p = 0.0001). In non-survivors, protein C activity remained decreased below 70%, whereas the course of survivors was characterized by increased values that were significantly higher (p < 0.03) at every time point than in those patients who died. Protein C was of excellent predictive value and achieved a sensitivity of 80% and a specificity of 87.5% in discriminating survivors from non-survivors within the first 48 hours of the study (AUC-0.917; p < 0.001), with a "cut-off" level of 66.0%. As for the control group, throughout the study period, protein C activity was permanently maintained within the range of normal, with significant differences with reference to the study group (p < 0.01). These results suggest that protein C represents a sensitive and early marker for the prediction of severe septic complications during diffuse peritonitis, and of outcome.

Decreased protein C, protein S, and antithrombin levels are predictive of poor outcome in Gram-negative sepsis caused by Burkholderia pseudomallei

BACKGROUND

Acute septicemic melioidosis is associated with systemic release of endotoxin and the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin-1, and interleukin-6. Excessive release of these cytokines may lead to endothelial injury, depletion of naturally occurring endothelial modulators, microvascular thrombosis, organ failure, and death.

METHOD

Plasma samples drawn at baseline and after initial antimicrobial therapy in 30 patients with suspected acute severe melioidosis were assayed for D-dimer levels, protein C and protein S antigen levels, and antithrombin functional activities.

RESULTS

Both baseline and continued deficiencies of protein C, protein S, and antithrombin were statistically associated with a poor outcome by logistic regression. Baseline D-dimer levels were significantly higher in fatal cases than survivors and correlated inversely with protein C and antithrombin, suggesting both increased fibrin deposition and fibrinolysis.

CONCLUSION

The inflammatory response to systemic Burkholderia pseudomallei infection leads to depletion of the natural endothelial modulators protein C, protein S, and antithrombin. Both baseline and continued deficiency of these endothelial modulators is predictive of poor outcome in melioidosis.

Back to the future: testing in disseminated intravascular coagulation

Following on from the first clinical observations on disseminated intravascular coagulation (DIC) in the nineteenth century, the dawn of laboratory testing for DIC began with the availability of assays that characterized the extrinsic and intrinsic pathways of coagulation. Markedly increased clotting times were the hallmark of DIC. As the understanding of the biochemistry of haemostasis and thrombosis improved, new tests were developed based on the molecular players that participate in the process. However, many are non-specific for DIC and/or are unwieldy in performance to keep apace with the demands of the acute clinical setting. The renewed emphasis in DIC for the modern laboratory of the twenty-first century has seen a return to the simple, rapid and practical global tests of coagulation within scoring systems that also capture the pathophysiological continuum by trend analysis. Additionally, new technologies based on these simple tests of coagulation hold promise in also indicating the in vivo interplay between coagulation and inflammation during DIC.

New anticoagulants: a pediatric perspective

Unfractionated heparin and vitamin K antagonists such as warfarin have been used as the anticoagulants of choice for over five decades. Subsequently, low molecular weight heparins (LMWHs) became widely available and have provided several advantages, especially in infants and children. The field of anticoagulation, however, has undergone a major revolution with better understanding of the structure of coagulation proteins and the development of a host of new drugs with highly specific actions. Many of these drugs have undergone extensive clinical testing in adults and have been approved for specific indications in adults. Unfortunately, clinical data and the reported use of these drugs in children are extremely limited. A lack of familiarity with the actions and pharmacokinetic properties of these drugs could be a major contributing factor. This review focuses on several of the new anticoagulants, with a special emphasis on those that could be potentially beneficial in pediatric patients with thromboembolic disorders. The need for well-designed trials with large-scale participation by pediatric hematologists in order to improve the antithrombotic care of young infants and children is also emphasized.

Activated protein C for the treatment of fulminant meningococcal septicaemia

We report two cases of meningococcal septic shock with multiple organ failure treated with prompt administration of activated protein C. This was associated with a rapid clinical improvement and early cessation of organ support. Both patients survived to hospital discharge with no long-term sequelae.

Disseminated Intravascular Coagulation in Sepsis

Disseminated intravascular coagulation is a frequent complication of sepsis. Coagulation activation, inhibition of fibrinolysis, and consumption of coagulation inhibitors lead to a procoagulant state resulting in inadequate fibrin removal and fibrin deposition in the microvasculature. As a consequence, microvascular thrombosis contributes to promotion of organ dysfunction. Recently, three randomized, double-blind, placebo-controlled trials investigated the efficacy of antithrombin, activated protein C (APC), and tissue factor pathway inhibitor, respectively, in sepsis patients. A significant reduction in mortality was demonstrated in the APC trial. In this article, we first discuss the physiology of coagulation and fibrinolysis activation. Then, the pathophysiology of coagulation activation, consumption of coagulation inhibitors, and the inhibition of fibrinolysis leading to a procoagulant state are described in more detail. Moreover, therapeutic concepts as well as the three randomized, double-blind, placebo-controlled studies are discussed.

A protein C deficiency exacerbates inflammatory and hypotensive responses in mice during polymicrobial sepsis in a cecal ligation and puncture model

During the systemic inflammatory state induced by sepsis, the potential for coagulopathy exists because of up-regulation of natural procoagulants and anti-fibrinolytics, and down-regulation of natural anti-coagulants, with protein C (PC) being a critical example of the latter case. PC functions as an anti-coagulant, profibrinolytic, and anti-inflammatory agent, and, thus, its administration or deficiency may affect the course and outcome of sepsis in patients. In this study, a cecal ligation and puncture model of septic peritonitis was applied to wild-type mice and littermates with a targeted heterozygous deficiency of PC (PC(+/-)) to characterize the importance of a PC-deficiency on polymicrobial sepsis. An enhanced mortality rate was found to accompany a PC deficiency. Plasma cytokines, as well as organ-specific expression of cytokine transcripts, were elevated in PC(+/-) mice. No signs of severe disseminated intravascular coagulation (DIC) were observed in wild-type or PC(+/-) mice, as indicated by an increase in fibrinogen levels and the invariability of platelet counts after cecal ligation and puncture. Consumption of coagulation factors was similar in both genotypes and a decrease in the PC mRNA and protein levels was more prominent in PC(+/-) mice. Renal and organ muscle damage was enhanced in PC(+/-) mice, as shown by increases in plasma blood urea nitrogen, creatinine, and creatinine kinase. Hypotension and bradycardia were more enhanced in PC(+/-) mice than in wild-type mice, thus provoking a more severe septic shock response. Thus, the hemodynamic role of PC during sepsis is of critical importance to the outcome of the disease.

Coagulation in Sepsis

Activation of the coagulation cascade during invasive infection can result in purpura fulminans, with rapid progression of tissue ischemia, or may manifest as abnormal clotting indices alone. Although severe derangements in coagulation are associated with organ dysfunction and increased mortality, the contribution of coagulopathy to the pathophysiology of sepsis remains incompletely understood. Over the past decade, investigators have evaluated several therapeutic anticoagulant strategies in sepsis, and manipulation of the coagulation system has emerged as a key concept in the current management of this disease. Clinical observations during treatment of septic patients with the endogenous anticoagulant activated protein C have stimulated additional study of interactions between endothelial injury, coagulation, and inflammation. This review describes clotting abnormalities during sepsis and discusses the clinical experience with therapeutic strategies intended to oppose excessive coagulation.

Linking the sepsis triad of inflammation, coagulation, and suppressed fibrinolysis to infants

Sepsis continues to be a significant cause of morbidity and mortality in hospitalized newborns and premature infants. The pathophysiology and disease state of sepsis appear to be similar between adults and children. Both groups display symptoms that indicate a systemic inflammatory response leading to coagulopathy, hypotension, inadequate perfusion of peripheral tissues and organs, and, ultimately, organ failure and death. By presenting a comparison of adult and neonatal pathophysiology, as well as a supporting literature review and clinical evidence, this article links the pathways of inflammation, activation of coagulation, and impaired fibrinolysis, known as the sepsis cascade, to neonatal sepsis. Knowledge of the pathophysiology has important clinical and research implications. Unlike traditional antimicrobial therapy, new potential therapies, currently under investigation for the treatment of sepsis, target the cellular response rather than the invading organism. A more complete understanding of the pathophysiology of sepsis may also lead to diagnostic tools with improved sensitivity and specificity for early recognition and treatment.

Evaluation of protein C and other biomarkers as predictors of mortality in a rat cecal ligation and puncture model of sepsis

OBJECTIVE

To evaluate protein C and other factors associated with the septic response as predictors of mortality in a clinically relevant animal model of sepsis.

DESIGN

Laboratory investigation.

SETTING

Eli Lilly and Company discovery research laboratory.

SUBJECTS

Forty female Sprague Dawley rats weighing 245-265 g.

INTERVENTIONS

Polyethylene catheters were surgically implanted into the femoral vein and sepsis was induced by cecal ligation and puncture (CLP). A solution of 5% dextrose in 0.9 % saline was continuously infused via femoral catheters immediately following surgery. Blood sampling was done before surgery and at 6 and 20 hrs after surgery. Rats were then monitored for survival out to 4 days.

MEASUREMENTS AND MAIN RESULTS

Blood collections were used to measure blood glucose, bacteremia, plasma protein C, D-dimer, hormones, chemokines, cytokines, and myoglobin (as a marker of organ damage). Mortality was categorized into three groups: early death (before 30 hrs post-CLP), late death (after 30 hrs post-CLP), and survivors (96 hrs post-CLP). Compared with survivors, early death rats had statistically significant differences in 30 variables indicative of severe inflammation, coagulopathy, and muscle damage including less bacterial clearance, hypoglycemia, lower plasma protein C, higher plasma D dimer, higher plasma cytokine/ chemokines, and higher plasma myoglobin concentrations. Twenty variables had a moderate to strong correlation with time of death. Receiver operator characteristic curves generated from a simple logistic regression model indicated that KC and macrophage inflammatory protein-2, rodent homologues of the human growth related oncogene CXC chemokine family, and protein C were the best predictors of mortality in this model.

CONCLUSIONS

The data from this study indicate that an early decrease in protein C concentration predicts poor outcome in a rat sepsis model. The data further indicate that increases in the CXC chemokines macrophage inflammatory protein-2 and KC precede poor outcome.

Genomic polymorphic profiles in an Irish population with meningococcaemia: is it possible to predict severity and outcome of disease?

Patients with meningococcal disease have increased plasma levels of proinflammatory cytokines IL-6, IL-1beta, and TNF-alpha, with higher levels associated with fatal outcome. This study investigated whether polymorphisms in genes encoding these cytokines, and in those encoding anti-inflammatory IL-10 and IL-1Ra, are associated with the outcome in patients with meningococcal disease. Seven polymorphisms were genotyped in 183 meningococcal disease patients and 389 controls. The IL-6 -174 G/G and IL-10 -1082 A/A genotypes were more frequent in nonsurvivors compared with survivors (P=0.023 IL-6, 0.25 IL-10), and in patients with severe disease compared to those with mild disease (P=0.037 IL-6, 0.0078 IL-10). An association was also found between meningococcal disease and the IL-1RN VNTR polymorphism, but no association was observed with the LTA +252, TNF -308, IL-10 -592, or IL-1B +3953 polymorphisms. We conclude that genetic variability in the IL-6, IL-10, and IL-1RN genes is associated with a poor outcome in meningococcal disease.