Prognostic value of protein C concentrations in neutropenic patients at high risk of severe septic complications

Endothelial Activation and Microcirculatory Disorders in Sepsis

The vascular endothelium is crucial for the maintenance of vascular homeostasis. Moreover, in sepsis, endothelial cells can acquire new properties and actively participate in the host's response. If endothelial activation is mostly necessary and efficient in eliminating a pathogen, an exaggerated and maladaptive reaction leads to severe microcirculatory damage. The microcirculatory disorders in sepsis are well known to be associated with poor outcome. Better recognition of microcirculatory alteration is therefore essential to identify patients with the worse outcomes and to guide therapeutic interventions. In this review, we will discuss the main features of endothelial activation and dysfunction in sepsis, its assessment at the bedside, and the main advances in microcirculatory resuscitation.

Coagulation profile of COVID-19 patients admitted to the ICU: An exploratory study

BACKGROUND

Coagulation abnormalities in COVID-19 patients have not been addressed in depth.

OBJECTIVE

To perform a longitudinal evaluation of coagulation profile of patients admitted to the ICU with COVID-19.

METHODS

Conventional coagulation tests, rotational thromboelastometry (ROTEM), platelet function, fibrinolysis, antithrombin, protein C and S were measured at days 0, 1, 3, 7 and 14. Based on median total maximum SOFA score, patients were divided in two groups: SOFA ≤ 10 and SOFA > 10.

RESULTS

Thirty patients were studied. Some conventional coagulation tests, as aPTT, PT and INR remained unchanged during the study period, while alterations on others coagulation laboratory tests were detected. Fibrinogen levels were increased in both groups. ROTEM maximum clot firmness increased in both groups from Day 0 to Day 14. Moreover, ROTEM-FIBTEM maximum clot firmness was high in both groups, with a slight decrease from day 0 to day 14 in group SOFA ≤ 10 and a slight increase during the same period in group SOFA > 10. Fibrinolysis was low and decreased over time in all groups, with the most pronounced decrease observed in INTEM maximum lysis in group SOFA > 10. Also, D-dimer plasma levels were higher than normal reference range in both groups and free protein S plasma levels were low in both groups at baseline and increased over time, Finally, patients in group SOFA > 10 had lower plasminogen levels and Protein C ​​than patients with SOFA <10, which may represent less fibrinolysis activity during a state of hypercoagulability.

CONCLUSION

COVID-19 patients have a pronounced hypercoagulability state, characterized by impaired endogenous anticoagulation and decreased fibrinolysis. The magnitude of coagulation abnormalities seems to correlate with the severity of organ dysfunction. The hypercoagulability state of COVID-19 patients was not only detected by ROTEM but it much more complex, where changes were observed on the fibrinolytic and endogenous anticoagulation system.

Plasma protein C levels are directly associated with better outcomes in patients with severe burns

Protein C circulates in human plasma to regulate inflammation and coagulation. It has shown a crucial role in wound healing in animals, and low plasma levels predict the presence of a wound in diabetic patients. However, no detailed study has measured protein C levels in patients with severe burns over the course of a hospital admission. A severe burn is associated with dysfunction of inflammation and coagulation as well as a significant risk of morbidity and mortality. The current methods of burn assessment have shortcomings in reliability and have limited prognostic value. The discovery of a biomarker that estimates burn severity and predicts clinical events with greater accuracy than current methods may improve management, resource allocation and patient counseling. This is the first study to assess the potential role of protein C as a biomarker of burn severity. We measured the plasma protein C levels of 86 patients immediately following a severe burn, then every three days over the first three weeks of a hospital admission. We also analysed the relationships between burn characteristics, blood test results including plasma protein C levels and clinical events. We used a primary composite outcome of increased support utilisation defined as: a mean intravenous fluid administration volume of five litres or more per day over the first 72 h of admission, a length of stay in the intensive care unit of more than four days, or greater than four surgical procedures during admission. The hypothesis was that low protein C levels would be negatively associated with increased support utilisation. At presentation to hospital after a severe burn, the mean plasma protein C level was 76 ± 20% with a range of 34-130% compared to the normal range of 70-180%. The initial low can be plausibly explained by impaired synthesis, increased degradation and excessive consumption of protein C following a burn. Levels increased gradually over six days then remained at a steady-state until the end of the inpatient study period, day 21. A multivariable regression model (Nagelkerke's R² = 0.83) showed that the plasma protein C level on admission contributed the most to the ability of the model to predict increased support utilisation (OR = 0.825 (95% CI = 0.698-0.977), P = 0.025), followed by burn size (OR = 1.252 (95% CI = 1.025-1.530), P = 0.027), burn depth (partial thickness was used as the reference, full thickness OR = 80.499 (1.569-4129.248), P = 0.029), and neutrophil count on admission (OR = 1.532 (95% CI = 0.950-2.473), P = 0.08). Together, these four variables predicted increased support utilisation with 93.2% accuracy, 83.3% sensitivity and 97.6% specificity. However if protein C values were disregarded, only 49.5% of the variance was explained, with 82% accuracy, 63% sensitivity and 91.5% specificity. Thus, protein C may be a useful biomarker of burn severity and study replication will enable validation of these novel findings.

Outpatient treatment for people with cancer who develop a low-risk febrile neutropaenic event

BACKGROUND

People with febrile neutropaenia are usually treated in a hospital setting. Recently, treatment with oral antibiotics has been proven to be as effective as intravenous therapy. However, the efficacy and safety of outpatient treatment have not been fully evaluated.

OBJECTIVES

To compare the efficacy (treatment failure and mortality) and safety (adverse events of antimicrobials) of outpatient treatment compared with inpatient treatment in people with cancer who have low-risk febrile neutropaenia.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 11) in the Cochrane Library, MEDLINE via Ovid (from 1948 to November week 4, 2018), Embase via Ovid (from 1980 to 2018, week 48) and trial registries (National Cancer Institute, MetaRegister of Controlled Trials, Medical Research Council Clinical Trial Directory). We handsearched all references of included studies and major reviews.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing outpatient with inpatient treatment for people with cancer who develop febrile neutropaenia. The outpatient group included those who started treatment as an inpatient and completed the antibiotic course at home (sequential) as well as those who started treatment at home.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, methodological quality, and extracted data. Primary outcome measures were: treatment failure and mortality; secondary outcome measures considered were: duration of fever, adverse drug reactions to antimicrobial treatment, duration of neutropaenia, duration of hospitalisation, duration of antimicrobial treatment, and quality of life (QoL). We estimated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous data; we calculated weighted mean differences for continuous data. Random-effects meta-analyses and sensitivity analyses were conducted.

MAIN RESULTS

We included ten RCTs, six in adults (628 participants) and four in children (366 participants). We found no clear evidence of a difference in treatment failure between the outpatient and inpatient groups, either in adults (RR 1.23, 95% CI 0.82 to 1.85, I² 0%; six studies; moderate-certainty evidence) or children (RR 1.04, 95% CI 0.55 to 1.99, I² 0%; four studies; moderate-certainty evidence). For mortality, we also found no clear evidence of a difference either in studies in adults (RR 1.04, 95% CI 0.29 to 3.71; six studies; 628 participants; moderate-certainty evidence) or in children (RR 0.63, 95% CI 0.15 to 2.70; three studies; 329 participants; moderate-certainty evidence).According to the type of intervention (early discharge or exclusively outpatient), meta-analysis of treatment failure in four RCTs in adults with early discharge (RR 1.48, 95% CI 0.74 to 2.95; P = 0.26, I² 0%; 364 participants; moderate-certainty evidence) was similar to the results of the exclusively outpatient meta-analysis (RR 1.15, 95% CI 0.62 to 2.13; P = 0.65, I² 19%; two studies; 264 participants; moderate-certainty evidence).Regarding the secondary outcome measures, we found no clear evidence of a difference between outpatient and inpatient groups in duration of fever (adults: mean difference (MD) 0.2, 95% CI -0.36 to 0.76, 1 study, 169 participants; low-certainty evidence) (children: MD -0.6, 95% CI -0.84 to 0.71, 3 studies, 305 participants; low-certainty evidence) and in duration of neutropaenia (adults: MD 0.1, 95% CI -0.59 to 0.79, 1 study, 169 participants; low-certainty evidence) (children: MD -0.65, 95% CI -0.1.86 to 0.55, 2 studies, 268 participants; moderate-certainty evidence). With regard to adverse drug reactions, although there was greater frequency in the outpatient group, we found no clear evidence of a difference when compared to the inpatient group, either in adult participants (RR 8.39, 95% CI 0.38 to 187.15; three studies; 375 participants; low-certainty evidence) or children (RR 1.90, 95% CI 0.61 to 5.98; two studies; 156 participants; low-certainty evidence).Four studies compared the hospitalisation time and found that the mean number of days of hospital stay was lower in the outpatient treated group by 1.64 days in adults (MD -1.64, 95% CI -2.22 to -1.06; 3 studies, 251 participants; low-certainty evidence) and by 3.9 days in children (MD -3.90, 95% CI -5.37 to -2.43; 1 study, 119 participants; low-certainty evidence). In the 3 RCTs of children in which days of antimicrobial treatment were analysed, we found no difference between outpatient and inpatient groups (MD -0.07, 95% CI -1.26 to 1.12; 305 participants; low-certainty evidence).We identified two studies that measured QoL: one in adults and one in children. QoL was slightly better in the outpatient group than in the inpatient group in both studies, but there was no consistency in the domains included.

AUTHORS' CONCLUSIONS

Outpatient treatment for low-risk febrile neutropaenia in people with cancer probably makes little or no difference to treatment failure and mortality compared with the standard hospital (inpatient) treatment and may reduce time that patients need to be treated in hospital.

Extract from Bougainvillea xbuttiana (Variety Orange) Inhibits Production of LPS-Induced Inflammatory Mediators in Macrophages and Exerts a Protective Effect In Vivo

Background

Different pharmacological properties, such as antioxidant, antiproliferative, and anti-inflammatory properties, have been described among natural products. We previously described that the Bougainvillea xbuttiana (Variety Orange) ethanolic extract (BxbO) has an anti-inflammatory effect; however, this action is not fully understood. In this study, the action of the BxbO extract on the secretion of inflammatory mediators in two experimental models, in vitro and in vivo, after LPS challenge was evaluated.

Methods

Peritoneal macrophages were obtained from female BALB/c mice and LPS-challenged with or without the BxbO extract. For the evaluation of mediators, the supernatants at 0, 12, 24, 36, and 48 hours were collected. For in vivo estimation, groups of female BALB/c mice were first intraperitoneously injected with different amounts of LPS and later administered the oral BxbO extract (v.o.) for 144 hours. To understand the mechanism of action, sera obtained from mice were collected at 0, 2, 4, 8, 12, and 24 hours after LPS challenge (with or without BxbO) for the detection of mediators.

Results

The results showed that, in both peritoneal macrophages and sera of mice treated with the BxbO extract 1 hour before or together with LPS challenge, proinflammatory cytokines and nitric oxide release were unquestionably repressed. In contrast, in both systems studied here, the IL-10 levels were elevated to 5 to 9 times. At lethal doses of LPS, the BxbO extract treatment was found to protect animals from death.

Conclusions

The results revealed that the inhibitory, protective, and benign effects of the BxbO extract were due to its capacity to balance the secretion of mediators.

Activated Protein C Drives the Hyperfibrinolysis of Acute Traumatic Coagulopathy

BACKGROUND

Major trauma is a leading cause of morbidity and mortality worldwide with hemorrhage accounting for 40% of deaths. Acute traumatic coagulopathy exacerbates bleeding, but controversy remains over the degree to which inhibition of procoagulant pathways (anticoagulation), fibrinogen loss, and fibrinolysis drive the pathologic process. Through a combination of experimental study in a murine model of trauma hemorrhage and human observation, the authors' objective was to determine the predominant pathophysiology of acute traumatic coagulopathy.

METHODS

First, a prospective cohort study of 300 trauma patients admitted to a single level 1 trauma center with blood samples collected on arrival was performed. Second, a murine model of acute traumatic coagulopathy with suppressed protein C activation via genetic mutation of thrombomodulin was used. In both studies, analysis for coagulation screen, activated protein C levels, and rotational thromboelastometry (ROTEM) was performed.

RESULTS

In patients with acute traumatic coagulopathy, the authors have demonstrated elevated activated protein C levels with profound fibrinolytic activity and early depletion of fibrinogen. Procoagulant pathways were only minimally inhibited with preservation of capacity to generate thrombin. Compared to factors V and VIII, proteases that do not undergo activated protein C-mediated cleavage were reduced but maintained within normal levels. In transgenic mice with reduced capacity to activate protein C, both fibrinolysis and fibrinogen depletion were significantly attenuated. Other recognized drivers of coagulopathy were associated with less significant perturbations of coagulation.

CONCLUSIONS

Activated protein C-associated fibrinolysis and fibrinogenolysis, rather than inhibition of procoagulant pathways, predominate in acute traumatic coagulopathy. In combination, these findings suggest a central role for the protein C pathway in acute traumatic coagulopathy and provide new translational opportunities for management of major trauma hemorrhage.

Biomarker candidates for the detection of an infectious etiology of febrile neutropenia

PURPOSE

Infections and subsequent septicemia are major complications in neutropenic patients with hematological malignancies. Here, we identify biomarker candidates for the early detection of an infectious origin, and monitoring of febrile neutropenia (FN).

METHODS

Proteome, metabolome, and conventional biomarkers from 20 patients with febrile neutropenia without proven infection (FNPI) were compared to 28 patients with proven infection, including 17 patients with bacteremia.

RESULTS

Three peptides (mass to charge ratio 1017.4-1057.3; p-values 0.011-0.024), six proteins (mass to charge ratio 6881-17,215; p-values 0.002-0.004), and six phosphatidylcholines (p-values 0.007-0.037) were identified that differed in FNPI patients compared to patients with infection or bacteremia. Seven of these marker candidates discriminated FNPI from infection at fever onset with higher sensitivity and specificity (ROC-AUC 0.688-0.824) than conventional biomarkers i.e., procalcitonin, C-reactive protein, or interleukin-6 (ROC-AUC 0.535-0.672). In a post hoc analysis, monitoring the time course of four lysophosphatidylcholines, threonine, and tryptophan allowed for discrimination of patients with or without resolution of FN (ROC-AUC 0.648-0.919) with higher accuracy compared to conventional markers (ROC-AUC 0.514-0.871).

CONCLUSIONS

Twenty-one promising biomarker candidates for the early detection of an infectious origin or for monitoring the course of FN were found which might overcome known shortcomings of conventional markers.

Hemostatic abnormalities in critically ill patients

Hemostatic abnormalities frequently occur in critically ill patients and may vary from prolonged global clotting tests or isolated thrombocytopenia, to composite defects, such as consumption coagulopathies. There are many reasons for a disturbed coagulation in intensive care patients, and each of these underlying syndromes may require specific therapeutic intervention. Hence, an adequate differential diagnosis and initiation of proper (supportive) therapeutic strategies are critical to decrease morbidity and mortality in critically ill patients with hemostatic abnormalities.

New diagnostic strategy for sepsis-induced disseminated intravascular coagulation: a prospective single-center observational study

Introduction

Inflammation and coagulation are closely interrelated pathophysiologic processes in the pathogenesis of sepsis. However, the diagnostic criteria of sepsis and disseminated intravascular coagulation (DIC) are different. This study aimed to define a biomarker panel to predict sepsis-induced DIC in emergency department patients.

Methods

Eighty-two patients who were admitted to the emergency department of a tertiary university hospital were included in this study. The inclusion criteria were as follows: (1) age >18 years; (2) ≥1 systemic inflammatory response syndrome (SIRS) criteria. Patients were excluded if they lacked biomarker data or apparent clinical manifestations. Eleven biomarkers were assayed from blood drawn on ED admission. Receiver operating curve (ROC) analysis including the area under the ROC and multivariable logistic regression were used to identify an optimal combination of biomarkers to create a diagnostic panel. The derived formula for weighting biomarker values was used to determine the severity of sepsis-induced DIC, which was divided into three categories: mild, moderate, and severe. We also investigated the ability of this classification to predict secondary outcome measures of rates of sepsis and DIC, DIC score, acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure score (SOFA) score, and 28-day all-cause mortality.

Results

Among the 11 biomarkers tested, the optimal 2-marker panel comprised presepsin and protein C. The area under the curve for the accuracies of predicting sepsis and DIC from these two biomarkers were 0.913 and 0.880, respectively. When patients were divided according to the severity of sepsis-induced DIC, all secondary outcomes except for mortality were significantly higher depending on the severity (P < .0001). The overall mortality rates of mild, moderate, and severe sepsis-induced DIC were 7.14%, 15.4%, and 28.6%, respectively (P = .0994).

Conclusions

A biomarker panel of presepsin and protein C is predictive of the severity of sepsis-induced DIC in suspected ED patients. These criteria for sepsis-induced DIC are very simple, easy to implement, and can be used in intensive care units as a point-of-care test.

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.

Coagulation system changes associated with susceptibility to infection in trauma patients

BACKGROUND

Infection following trauma is associated with increased morbidity and mortality and is common following severe hemorrhage. There is a strong interaction between the coagulation and immunity. The objective of this study was to establish if there was an association between changes in coagulation status after hemorrhage and the subsequent incidence of infection.

METHODS

Prospective cohort study of adult injured patients presenting to a major trauma center during a 2-year period. Blood was drawn at 24 hours following admission and analyzed using functional thromboelastography testing and laboratory defined tests of coagulation and blood count. Patients were followed up for infectious episodes while in the hospital using Center for Disease Control definitions.

RESULTS

A total of 158 patients were recruited; 71 (45%) developed infection and were older (44 years vs. 32 years, p = 0.01) and more severely injured (Injury Severity Score [ISS], 25 vs.10; p < 0.01). White blood cell counts at 24 hours were normal, and there was no difference between groups (both 9.6 × 10/(9)L). Protein C was lower in those with infection (70.2 IU/dL vs. 83.3 IU/dL, p = 0.02), with a dose-dependent increase in infection as levels of protein C decreased. Plasmin activation at 24 hours was also strongly associated with infection plasmin-antiplasmin (infection vs. no infection, 6,156 μg/L vs. 3,324 μg/L, p = 0.03). The infection cohort had overall 12% lower procoagulant levels (varied between factor VIII 6.4% and factor II 16.2%).

CONCLUSION

There is a strong association between the status of the coagulation system after 24 hours and the development of infection following trauma. Improved early coagulation management may decrease infection rates in this patient group.

LEVEL OF EVIDENCE

Prognostic prospective study, level III.

Discrepant fibrinolytic response in plasma and whole blood during experimental endotoxemia in healthy volunteers

Background

Sepsis induces early activation of coagulation and fibrinolysis followed by late fibrinolytic shutdown and progressive endothelial damage. The aim of the present study was to investigate and compare the functional hemostatic response in whole blood and plasma during experimental human endotoxemia by the platelet function analyzer, Multiplate and by standard and modified thrombelastography (TEG).

Methods

Prospective physiologic study of nine healthy male volunteers undergoing endotoxemia by means of a 4-hour infusion of E. coli lipopolysaccharide (LPS, 0.5 ng/kg/hour), with blood sampled at baseline and at 4 h and 6 h. Physiological and standard biochemical data and coagulation tests, TEG (whole blood: TEG, heparinase-TEG, Functional Fibrinogen; plasma: TEG±tissue-type plasminogen activator (tPA)) and Multiplate (TRAPtest, ADPtest, ASPItest, COLtest) were recorded. Mixed models with Tukey post hoc tests and correlations were applied.

Results

Endotoxemia induced acute SIRS with increased HR, temperature, WBC, CRP and procalcitonin and decreased blood pressure. It also induced a hemostatic response with platelet consumption and reduced APTT while INR increased (all p<0.05). Platelet aggregation decreased (all tests, p<0.05), whereas TEG whole blood clot firmness increased (G, p = 0.05). Furthermore, during endotoxemia (4 h), whole blood fibrinolysis increased (clot lysis time (CLT), p<0.001) and Functional Fibrinogen clot strength decreased (p = 0.049). After endotoxemia (6 h), whole blood fibrinolysis was reduced (CLT, p<0.05). In contrast to findings in whole blood, the plasma fibrin clot became progressively more resistant towards tPA-induced fibrinolysis at both 4 h and 6 h (p<0.001).

Conclusions

Endotoxemia induced a hemostatic response with reduced primary but enhanced secondary hemostasis, enhanced early fibrinolysis and fibrinogen consumption followed by downregulation of fibrinolysis, with a discrepant fibrinolytic response in plasma and whole blood. The finding that blood cells are critically involved in the vasculo-fibrinolytic response to acute inflammation is important given that disturbances in the vascular system contribute significantly to morbidity and mortality in critically ill patients.

New approaches to sepsis: molecular diagnostics and biomarkers

Sepsis is among the most common causes of death in hospitals. It arises from the host response to infection. Currently, diagnosis relies on nonspecific physiological criteria and culture-based pathogen detection. This results in diagnostic uncertainty, therapeutic delays, the mis- and overuse of antibiotics, and the failure to identify patients who might benefit from immunomodulatory therapies. There is a need for new sepsis biomarkers that can aid in therapeutic decision making and add information about screening, diagnosis, risk stratification, and monitoring of the response to therapy. The host response involves hundreds of mediators and single molecules, many of which have been proposed as biomarkers. It is, however, unlikely that one single biomarker is able to satisfy all the needs and expectations for sepsis research and management. Among biomarkers that are measurable by assays approved for clinical use, procalcitonin (PCT) has shown some usefulness as an infection marker and for antibiotic stewardship. Other possible new approaches consist of molecular strategies to improve pathogen detection and molecular diagnostics and prognostics based on transcriptomic, proteomic, or metabolic profiling. Novel approaches to sepsis promise to transform sepsis from a physiologic syndrome into a group of distinct biochemical disorders and help in the development of better diagnostic tools and effective adjunctive sepsis therapies.

Emodin-6-O-β-D-glucoside inhibits HMGB1-induced inflammatory responses in vitro and in vivo

High mobility group box 1 (HMGB1) protein acts as a potent proinflammatory cytokine and is involved in the pathogenesis of several vascular diseases, such as, systemic vasculitis and sepsis. Emodin-6-O-β-D-glucoside (EG) is a new active compound from Reynoutria japonica, and its biologic activities have not been previously investigated. In this study, we first investigated the antiinflammatory activities of EG on HMGB1-mediated proinflammatory responses in human umbilical vein endothelial cells (HUVECs) and in a murine cecal ligation and puncture (CLP)-model of sepsis in mice. EG was found to suppress the release of HMGB1, the production of tumor necrosis factor (TNF)-α, and the activation of nuclear factor-κB (NF-κB) by HMGB1 in HUVECs, and to inhibit HMGB1-mediated hyperpermeability and leukocyte migration in mice. In the CLP model, HMGB1 was highly released, but this release was prevented by EG. Furthermore, EG also increased the survival times of CLP administered mice. Collectively, this study shows EG can protect barrier integrity and inhibit HMGB1-mediated inflammatory responses, which suggests a potential use as a therapy for sepsis or septic shock.

Protein C activity and postoperative metabolic liver function after liver transplantation

BACKGROUND

Protein C is a natural thrombin antagonist produced by hepatocytes. Its levels are low in liver failure and predispose patients to increased risk for thrombosis. Little is known about the relationship between protein C activity and hepatic function after orthotopic liver transplantation (OLT).

METHODS

We measured protein C activity of 41 patients undergoing liver transplantation by the Staclot method (normal range, 70%-130%) preoperatively and then daily on postoperative days (POD) 0-5.

RESULTS

The mean protein C activity was low before OLT (34.3 ± 4.3%) and inversely correlated with the preoperative Model for End-Stage Liver Disease score (Spearman's r = -0.643; P < .0001). Mean activity increased significantly on POD 1 (58.9 ± 4.5%), and remained above preoperative levels through POD 5. Ten patients developed metabolic liver dysfunction defined by a serum total bilirubin >5 mg/dL on POD 7. These patients had significantly lower protein C activity from POD 3 (47.2 ± 9.6% vs 75.9 ± 5.8%; P = .01) to POD 5. Preoperative protein C activity correlated inversely with the severity of liver failure as indicated by preoperative MELD score.

CONCLUSION

Protein C activity recovered rapidly in patients with good allograft function but remained significantly lower in patients who had limited metabolic function as evidenced by increased total bilirubin levels.

Inhibitory effects of lycopene on HMGB1-mediated pro-inflammatory responses in both cellular and animal models

High mobility group box 1 (HMGB1) mediates proinflammatory responses in inflammatory diseases. Lycopene found in tomatoes and tomato products has anti-oxidant, anti-cancer and antiinflammatory effects. The potential anti-inflammatory roles of lycopene in HMGB1-mediated proinflammatory responses in both primary human umbilical vein endothelial cells (HUVECs) and animal were investigated. The anti-inflammatory effects of lycopene were determined including permeability, monocyte adhesion and migration, and activation of proinflammatory proteins and HMGB1 receptors on HMGB1 activated HUVECs. In the in vivo model, the anti-inflammatory effect of lycopene was assessed by monitoring vascular permeability and migration of leukocytes to the peritoneal cavity of mice injected with lycopene. Lycopene inhibited lipopolysaccharide (LPS)-mediated release of HMGB1, expression of HMGB1-mediated tumor necrosis factor (TNF)-secretory phospholipase A2 (sPLA2)-IIA, and HMGB1-mediated pro-inflammatory signaling responses in endothelial cells. It did this through down-regulation of cell surface expression of cell adhesion molecules (CAMs), HMGB1 receptors, toll-like receptor (TLR)-2, and -4, and receptors for advanced glycation end products (RAGE). These findings suggest that lycopene promotes barrier integrity, inhibits monocyte adhesion and migration to HMGB1 activating HUVECs by blocking activation of proinflammatory cytokines and expression of CAMs and HMGB1 receptors, thereby showing its usefulness as a therapy for vascular inflammatory diseases.

Systemic versus localized coagulation activation contributing to organ failure in critically ill patients

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 not only leads to activation of coagulation but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may not only be relevant for vascular atherothrombotic disease in general but has in certain clinical settings considerable consequences, for example in the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. 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 downregulating important physiological anticoagulant pathways. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by physiological anticoagulant mechanisms and endogenous fibrinolysis. Interestingly, apart from the overall systemic responses, a differential local response in various vascular beds related to specific organs may occur.

Activated protein C plasma levels in the fasting and postprandial states among patients with previous unprovoked venous thromboembolism

INTRODUCTION

The protein C anticoagulant system is of major importance in the regulation of thrombotic risk, but it is not known whether low plasma levels of activated protein C (APC) in vivo reflect a compromised anticoagulant situation with increased thrombotic risk. Previous studies have reported low, normal or increased plasma APC levels in unselected patients with venous thromboembolism (VTE).

MATERIALS AND METHODS

We performed a population-based, case-control study in patients with a previous history of unprovoked VTE and subjected the participants to a standard fat tolerance test (1g fat/kg body weight) in order to promote physiological coagulation activation.

RESULTS

VTE patients had higher BMI (28.3 ± 4.4 kg/m(2) versus 26.3 ± 3.9 kg/m(2), p=0.045) and greater waist circumference (98.2 ± 12.5 cm versus 93.4 ± 13.4 cm, p=0.041) than age and sex matched controls. APC levels were equal in fasting plasma (3.00 ± 0.74 ng/ml and 2.99 ± 0.60 ng/ml, p=0.66) but higher in postprandial plasma (3.18 ± 0.57 ng/ml and 2.81 ± 0.38 ng/ml, p=0.008) collected from VTE patients and controls, respectively. Endogenous thrombin generation in plasma following a standardized meal, assessed by thrombin-antithrombin complex (TAT), increased similarly in both groups, whereas APC increased only among the VTE patients during the postprandial state. Plasma levels of APC increased linearly with TAT in the postprandial state (p for linear trend=0.012).

CONCLUSIONS

Our findings fail to support the hypothesis that low APC levels are linked to increased thrombotic risk in unprovoked VTE, and they suggest that plasma APC is a biomarker of thrombin generation.

A moderate aseptic local inflammation does not induce a significant systemic inflammatory response

The aim of this prospective study was to characterize the response of the coagulation system to a defined sterile localized inflammatory process. Tissue cages were implanted subcutaneously in five healthy Beagles. After 9-10 weeks, local inflammation was induced by an injection of 0.5 ml 1% carrageenan. Serial samples of tissue cage fluid (TCF) and blood were collected at 10 time points (0-168 h). Nucleated cells (NC) of TCF were counted automatically to characterize local inflammation. C-reactive protein (CRP), leukocytes and coagulation variables (PT, aPTT, fibrinogen, factor VIII, antithrombin, protein C, protein S, and d-dimers) were determined in blood samples. Carrageenan induced a significant 32-fold increase of NCs in TCF (P<0.0001). A slight increase in leukocytes (P<0.0001) was observed. There was a significant 1.3- to 1.5-fold increase in protein C (P=0.0001) and protein S (P=0.0028). CRP, secondary hemostasis and fibrinolysis did not change. The mild increase from baseline in PC/PS, may reflect a physiological counter reaction.

Severe congenital protein C deficiency: the use of protein C concentrates (human) as replacement therapy for life-threatening blood-clotting complications

The protein C pathway has an important function in regulating and modulating blood coagulation and ensuring patency of the microcirculation. Protein C deficiency leads to macro- and microvascular thrombosis. Congenital severe protein C deficiency is a life-threatening state with neonatal purpura fulminans and pronounced coagulopathy. Patients with heterozygous protein C deficiency have an increased risk for thromboembolic events or experience coumarin-induced skin necrosis during initiation of coumarin therapy. Replacement with protein C concentrates is an established therapy of congenital protein C deficiency, resulting in rapid resolving of coagulopathy and thrombosis without reasonable side effects. This article summarizes the current knowledge on protein C replacement therapy in congenital protein C deficiency.

Severe protein C deficiency is associated with organ dysfunction in patients with severe sepsis

PURPOSE

The aim of this study was to assess the relationship between protein C levels and temporal changes in organ dysfunction.

MATERIALS AND METHODS

Using data from the placebo arm of Recombinant Human Activated PROtein C Worldwide Evaluation in Severe Sepsis trial (N = 775), we compared the development of organ dysfunction over time, in adult severe sepsis patients with and without severe protein C deficiency.

RESULTS

At study enrollment (baseline), patients with and without severe protein C deficiency were similar in age and likelihood of comorbidities. Patients with severe protein C deficiency had lower arterial blood pressure (P = .0006), greater serum creatinine concentration (P < .0001), elevated markers of thrombosis and inflammation, and impairment of fibrinolysis (P < .0001). The baseline PaO(2)/FiO(2) ratio was not significantly different between the 2 groups. Seven days after study enrollment, cardiovascular and renal function remained significantly worse in patients with severe protein C deficiency (P < .0001), and respiratory dysfunction was greater (P < .0001). Baseline protein C deficiency was seen to be associated with subsequent pulmonary, renal, and hematologic organ failure.

CONCLUSIONS

Severe protein C deficiency in patients with severe sepsis is associated with both the incidence and severity of organ dysfunction and subsequent worsening of organ function and may be a useful predictor of organ failure in severe sepsis.

Defects in coagulation encountered in small animal critical care

Critically ill small animals are at risk for developing coagulation abnormalities. The processes of inflammation and coagulation are intertwined, and severe inflammation can lead to disturbances of coagulation. Severe coagulation dysfunction is associated with increased morbidity and mortality. Pathophysiology, diagnosis, and treatment of coagulation dysfunction are discussed. Defects in coagulation in small animal patients are complex and a consensus on diagnosis and treatment has yet to be reached.

Randomized trial evaluating serial protein C levels in severe sepsis patients treated with variable doses of drotrecogin alfa (activated)

Introduction

Serial alterations in protein C levels appear to correlate with disease severity in patients with severe sepsis, and it may be possible to tailor severe sepsis therapy with the use of this biomarker. The purpose of this study was to evaluate the dose and duration of drotrecogin alfa (activated) treatment using serial measurements of protein C compared to standard therapy in patients with severe sepsis.

Methods

This was a phase 2 multicenter, randomized, double-blind, controlled study. Adult patients with two or more sepsis-induced organ dysfunctions were enrolled. Protein C deficient patients were randomized to standard therapy (24 μg/kg/hr infusion for 96 hours) or alternative therapy (higher dose and/or variable duration; 24/30/36 μg/kg/hr for 48 to 168 hours). The primary outcome was a change in protein C level in the alternative therapy group, between study Day 1 and Day 7, compared to standard therapy.

Results

Of 557 patients enrolled, 433 patients received randomized therapy; 206 alternative, and 227 standard. Baseline characteristics of the groups were largely similar. The difference in absolute change in protein C from Day 1 to Day 7 between the two therapy groups was 7% (P = 0.011). Higher doses and longer infusions were associated with a more pronounced increase in protein C level, with no serious bleeding events. The same doses and longer infusions were associated with a larger increase in protein C level; higher rates of serious bleeding when groups received the same treatment; but no clear increased risk of bleeding during the longer infusion. This group also experienced a higher mortality rate; however, there was no clear link to infusion duration.

Conclusions

The study met its primary objective of increased protein C levels in patients receiving alternative therapy demonstrating that variable doses and/or duration of drotrecogin alfa (activated) can improve protein C levels, and also provides valuable information for incorporation into potential future studies.

Trial registration

ClinicalTrials.gov identifier: NCT00386425.

Prowess-shock trial: a protocol overview and perspectives

Sepsis remains a challenge for intensive care physicians, as it keeps up with high mortality rate in spite of the high costs associated with its treatment. Several studies indicate that the infusion of Drotrecogin-alpha activated (DrotAA) reduce mortality in patients at high risk of death when administered early and secured the appropriate initial treatment of sepsis as recommended by Surviving Sepsis Campaign. Europe and United States of America differ regarding the criteria of high risk of death in sepsis, two or more organ dysfunctions and Acute Physiology and Chronic Health Evaluation 25 or more, respectively. In addition to varied definitions of high risk of death for inclusion of patients in sepsis studies, the possibility of bleeding related to drug use and intrinsic limitations related to study design led the Company to develop a new randomized, multinational, placebo-controlled, double-blind study to assess the effectiveness of drug in patients with septic shock in adults.

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.

Protein C depletion early after trauma increases the risk of ventilator-associated pneumonia

INTRODUCTION

Mechanically ventilated trauma patients have a high risk for the development of ventilator-associated pneumonia (VAP). We have recently reported that reduced plasma protein C (PC) levels early after trauma/shock are associated with coagulopathy and mortality. Furthermore, trauma patients with tissue injury and shock are at higher risk for the development of VAP.

OBJECTIVE

We hypothesized that low PC levels early after trauma are associated with an increased susceptibility to VAP in trauma patients.

METHODS

Fifty-nine acutely injured, intubated trauma patients were admitted to the critical care unit. Serial blood samples were drawn and coagulation factors were measured. VAP was diagnosed by presence of bacteria on bronchial alveolar lavage specimen, bilateral infiltrates on chest roentgenogram, and fever or elevated white blood cell count.

RESULTS

There were no differences in demographic or injury characteristics between patients who developed VAP and those who did not. As expected, patients who developed VAP had more ventilator days, hospital days, intensive care unit days, and greater mortality (all p < 0.05). Patients in both groups had lower mean PC levels at 6 hours compared with baseline. Noninfected patients' PC subsequently returned to near baseline levels, whereas those patients who eventually acquired VAP had significantly lower PC levels at both 12 and 24 hours (12 hours: 79 vs. 96%, p = 0.05; 24 hours: 75 vs. 97% p = 0.02). Soluble endothelial PC receptor (sEPCR) levels were also lower at 24 hours (82 vs. 99% in the noninfected group, p = 0.04).

DISCUSSION

The activation of PC pathway early after trauma may protect the vascular endothelium by both its anticoagulant and cytoprotective effects. However, trauma patients who later developed VAP have significantly lower plasma levels of PC within 24 hours after injury, suggesting a possible consumption of this vitamin K-dependent protein and an inhibition of its activation by inflammatory mediators. EPCR is involved in the activation of PC and is also a mediator of its cytoprotective effects.

CONCLUSION

Critically ill trauma patients have an early activation of the PC pathway, associated with a rapid decrease in the plasma levels of this protein and increase in EPCR. Plasma levels of PC return to normal levels within 24 hours in most patients. However, patients who go on to acquire VAP have persistently low plasma levels of PC in the immediate period after trauma. Whether PC could play a mechanistic role in the host response against nosocomial lung infection warrants further study.

Early prediction of septic shock in hospitalized patients

BACKGROUND

Hospitalized patients who develop severe sepsis have significant morbidity and mortality. Early goal-directed therapy has been shown to decrease mortality in severe sepsis and septic shock, though a delay in recognizing impending sepsis often precludes this intervention.

OBJECTIVE

To identify early predictors of septic shock among hospitalized non-intensive care unit (ICU) medical patients.

DESIGN

Retrospective cohort analysis.

SETTING

A 1200-bed academic medical center.

PATIENTS

Derivation cohort consisted of 13,785 patients hospitalized during 2005. The validation cohorts consisted of 13,737 patients during 2006 and 13,937 patients from 2007.

INTERVENTION

Development and prospective validation of a prediction model using Recursive Partitioning And Regression Tree (RPART) analysis.

METHODS

RPART analysis of routine laboratory and hemodynamic variables from the derivation cohort to identify predictors prior to the occurrence of shock. Two models were generated, 1 including arterial blood gas (ABG) data and 1 without.

RESULTS

When applied to the 2006 cohort, 347 (54.7%) and 121 (19.1%) of the 635 patients developing septic shock were correctly identified by the 2 models, respectively. For the 2007 patients, the 2 models correctly identified 367 (55.0%) and 102 (15.3%) of the 667 patients developing septic shock, respectively.

CONCLUSIONS

Readily available data can be employed to predict non-ICU patients who develop septic shock several hours prior to ICU admission.

Clinical review: a review and analysis of heart rate variability and the diagnosis and prognosis of infection

Bacterial infection leading to organ failure is the most common cause of death in critically ill patients. Early diagnosis and expeditious treatment is a cornerstone of therapy. Evaluating the systemic host response to infection as a complex system provides novel insights: however, bedside application with clinical value remains wanting. Providing an integrative measure of an altered host response, the patterns and character of heart rate fluctuations measured over intervals-in-time may be analysed with a panel of mathematical techniques that quantify overall fluctuation, spectral composition, scale-free variation, and degree of irregularity or complexity. Using these techniques, heart rate variability (HRV) has been documented to be both altered in the presence of systemic infection, and correlated with its severity. In this review and analysis, we evaluate the use of HRV monitoring to provide early diagnosis of infection, document the prognostic implications of altered HRV in infection, identify current limitations, highlight future research challenges, and propose improvement strategies. Given existing evidence and potential for further technological advances, we believe that longitudinal, individualized, and comprehensive HRV monitoring in critically ill patients at risk for or with existing infection offers a means to harness the clinical potential of this bedside application of complex systems science.

Treatment of the critically ill patient with protein C: is it worth the cost?

INTRODUCTION

We have shown that low protein C levels predict poor survival up to five years in a general intensive care unit patient material and hypothesize that treatment with protein C is beneficial. The objectives were to calculate costs of protein C treatment, at best-case scenario, per statistical life saved.

MATERIALS AND METHODS

Ninety-two patients with deranged global haemostatic tests admitted to the mixed surgical medical intensive care unit, Malmö University Hospital. We hypothesized that increasing protein C levels in patients with low levels would enhance survival to the same rate as a cohort with higher protein C. Number of statistical lives saved were estimated using survival analysis. Costs per life saved at 30days were calculated.

RESULTS

Total costs per life saved in 2007 prices (upper limit of 95% CI) were calculated at euro 50,200 (recombinant activated protein C, drotrecogin alfa (activated), Xigris) and euro 46,000 (zymogen protein C, Ceprotin), which may be compared to the value of a statistical life (euro 937,000).

CONCLUSIONS

Our theoretical model of converting a low protein C group to a higher protein C group by treating with activated protein C or the protein zymogen showed no major difference between the treatments in terms of costs, and that costs are lower than the value of a statistical life. Although our study has several caveats the results support the PROWESS study, in that patients with a very severe disease, having low protein C levels, may benefit from protein C treatment in a cost effective way.

Plasma protein C levels in immunocompromised septic patients are significantly lower than immunocompetent septic patients: a prospective cohort study

Introduction

Activated Protein C [APC] improves outcome in immunocompetent patients with severe sepsis particularly in those who are perceived to have high mortality risk. Before embarking on a trial of APC administration in immunocompromised septic patients, a preliminary study on plasma levels of protein C in this cohort is essential.

Objective

To assess serum Protein C concentrations in immunocompromised patients as compared to immunocompetent patients during sepsis, severe sepsis, septic shock and recovery.

Methods

Prospective cohort study in a tertiary hospital. Patients satisfying inclusion criteria were enrolled after informed consent. Clinical variables were noted with sample collection when patients met criteria for sepsis, severe sepsis, septic shock and recovery. Protein C levels were measured using monoclonal antibody based fluorescence immunoassay.

Results

Thirty one patients participated in this study (22 immunocompromised, 9 immunocompetent). Protein C levels were found to be significantly lower in the immunocompromised group compared to the immunocompetent group, particularly observed in severe sepsis [2.27 (95% CI: 1.63-2.9) vs 4.19 (95% CI: 2.87-5.52) mcg/ml] (p = 0.01) and sepsis [2.59 (95% CI: 1.98-3.21) vs 3.64 (95% CI: 2.83-4.45) mcg/ml] (p = 0.03). SOFA scores were similar in both the groups across sepsis, severe sepsis and septic shock categories. Protein C levels improved significantly in recovery (p = 0.001) irrespective of immune status.

Conclusion

Protein C levels were significantly lower in immunocompromised patients when compared to immunocompetent patients in severe sepsis and sepsis categories. Our study suggests a plausible role for APC in severely septic immunocompromised patients which need further elucidation.

Mouse recombinant protein C variants with enhanced membrane affinity and hyper-anticoagulant activity in mouse plasma

Mouse anticoagulant protein C (461 residues) shares 69% sequence identity with its human ortholog. Interspecies experiments suggest that there is an incompatibility between mouse and human protein C, such that human protein C does not function efficiently in mouse plasma, nor does mouse protein C function efficiently in human plasma. Previously, we described a series of human activated protein C (APC) Gla domain mutants (e.g. QGNSEDY-APC), with enhanced membrane affinity that also served as superior anticoagulants. To characterize these Gla mutants further in mouse models of diseases, the analogous mutations were now made in mouse protein C. In total, seven mutants (mutated at one or more of positions P(10)S(12)D(23)Q(32)N(33)) and wild-type protein C were expressed and purified to homogeneity. In a surface plasmon resonance-based membrane-binding assay, several high affinity protein C mutants were identified. In Ca(2+) titration experiments, the high affinity variants had a significantly reduced (four-fold) Ca(2+) requirement for half-maximum binding. In a tissue factor-initiated thrombin generation assay using mouse plasma, all mouse APC variants, including wild-type, could completely inhibit thrombin generation; however, one of the variants denoted mutant III (P10Q/S12N/D23S/Q32E/N33D) was found to be a 30- to 50-fold better anticoagulant compared to the wild-type protein. This mouse APC variant will be attractive to use in mouse models aiming to elucidate the in vivo effects of APC variants with enhanced anticoagulant activity.

Growing insights into the potential benefits and risks of activated protein C administration in sepsis: a review of preclinical and clinical studies

Recombinant human activated protein C (rhAPC) was developed to reduce excessive coagulant and inflammatory activity during sepsis. Basic and clinical research has suggested these pathways contribute to the pathogenesis of this lethal syndrome and are inhibited by rhAPC. Based in large part on the results of a single multicenter randomized controlled trial, rhAPC was first approved in 2001 by the US Food and Drug Administration (FDA) as adjunctive therapy in septic patients with a high risk of death. This was followed closely by approval in Europe, Australia, and New Zealand. At the original FDA review of rhAPC, concerns were raised as to whether a confirmatory trial should be done before final regulatory approval because of concerns that rhAPCs bleeding risk might outweigh its potential benefit during clinical use. Since 2001, continuing basic and clinical research has further elucidated the complex role activated protein C may have in both adaptive and maladaptive responses during sepsis. Moreover, subsequent controlled trials in other types of septic patients and observational studies appear to support earlier concerns that the benefit-to-risk ratio of rhAPC may not support its clinical use. This experience has prompted additional trials presently underway, to define whether treatment with rhAPC as it was originally indicated in septic patients with persistent shock, is safe and effective. Until such trials are complete, physicians employing this agent must carefully consider which patients may be appropriate candidates for rhAPC administration.

No association between protein C levels and bacteremia in children with febrile neutropenia

BACKGROUND

Little is known about protein C levels and outcomes of pediatric febrile neutropenia. The primary aim was to evaluate the relationship between markers of activated coagulation including protein C levels and bacteremia in pediatric oncology patients with febrile neutropenia.

METHODS

In this prospective cohort study, we collected a blood specimen from pediatric oncology patients who were admitted to a tertiary care hospital between October 2, 2002 and February 3, 2006 with febrile neutropenia. Levels of protein C, soluble thrombomodulin, soluble endothelial protein C receptor, thrombin-antithrombin complex, fibrinogen degradation products and activated protein C were measured. Associations between markers of activated coagulation and bacteremia were examined using univariate logistic regression.

RESULTS

Of the 73 evaluable patients, 10 had bacteremia. None of the above measured markers of activated coagulation were associated with bacteremia. More specifically, the median level of protein C in those with bacteremia was 0.64 U/mL (interquartile range: 0.58 to 0.72) in comparison with the median level in those without bacteremia of 0.73 U/mL (interquartile range: 0.61 to 0.92), odds ratio 0.18 (95% confidence interval 0.00 to 8.33); P=0.38.

CONCLUSIONS

Protein C levels do not differ between pediatric febrile neutropenic patients with and without bacteremia.

Protein C in critical illness

PURPOSE

The role of protein C in critical illness is assessed.

SUMMARY

Conversion of protein C to activated protein C (APC) requires thrombin and thrombomodulin. When thrombin is not bound to thrombomodulin, it can convert fibrinogen to fibrin, factor V to factor Va, and factor VIII to factor VIIIa but will not convert protein C to APC. When thrombin is bound to thrombomodulin, it can convert protein C to APC but cannot convert fibrinogen, factor V, or factor VIII. Activation of protein C is accelerated by the presence of endothelial protein C receptors. In conjunction with protein S, APC limits coagulation by inactivating factors Va and VIIIa, which decreases thrombin-mediated inflammation. By inhibiting the formation of thrombin and the release of proinflammatory cytokines, APC reduces the inflammatory response to infection. By inducing cell signaling, APC directly modulates the cellular response to infection, resulting in antiinflammatory, cytoprotective, and barrier-protective activities. APC is metabolized by protease inhibitors and other proteins in the plasma. Conversion of protein C to APC is impaired in severe sepsis. During severe sepsis, endogenous levels of the inactive precursor protein C are reduced because of decreased production by the liver and degradation by enzymes. More than 85% of patients with severe sepsis have low levels of protein C. Absolute levels of protein C correlate with morbidity and mortality outcomes of the sepsis population, regardless of age, infecting microorganism, presence of shock, disseminated intravascular coagulation, degree of hypercoagulation, or severity of illness.

CONCLUSION

The protein C pathway is a natural homeostatic regulator with multiple mechanisms of action. Blood protein C concentration is inversely correlated with morbidity and mortality in sepsis and other critical illness.

Saponin fraction from Astragalus membranaceus roots protects mice against polymicrobial sepsis induced by cecal ligation and puncture by inhibiting inflammation and upregulating protein C pathway

Sepsis remains the leading cause of death in intensive care units. Uncontrolled systemic inflammation and an impaired protein C pathway are two important contributors to sepsis pathophysiology. Based on the beneficial effects of the saponin fraction from Astragalus membranaceus roots (SAM) against inflammation, liver dysfunction, and endothelium injury, we investigated the potential protective roles and underlying mechanisms of SAM on polymicrobial sepsis induced by cecal ligation and puncture (CLP) in mice. SAM, orally administered 1 h before and after CLP, significantly elevated the survival rate of mice. At 96 h after CLP operation, all mice in the model group died, whereas 33.3% of mice in the SAM (400 mg/kg)-treated group survived. SAM attenuated both inflammatory factors and their abilities to induce tissue dysfunction, which was mainly evidenced by decreased infiltration of polymorphonuclear leukocytes, tissue edema, and lung wet-to-dry weight ratio, lowered levels of myeloperoxidase (MPO), nitric oxide (NO), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) in serum, as well as downregulated expressions of iNOS and IL-1beta mRNA in livers. Furthermore, we addressed the effects of SAM on the protein C (PC) pathway, closely linked with sepsis. In CLP-induced septic mice, SAM elevated the impaired expression of PC mRNA in livers. In vitro, SAM reversed the decreased expressions of thrombomodulin (TM) and endothelial PC receptor (EPCR) mRNA induced by lipopolysaccharide (LPS) in endothelial cells. These findings suggest that SAM is able to restore the impaired protein C pathway. Taken together, the current study demonstrates that SAM has protective effects on polymicrobial sepsis in mice. The mechanisms of action involve anti-inflammation and upregulation of the PC pathway.

Extended drotrecogin alfa (activated) treatment in patients with prolonged septic shock

OBJECTIVE

To determine the efficacy and safety of extended drotrecogin alfa (activated) (DAA) therapy.

DESIGN

Multicentre, randomised, double-blind, placebo-controlled study.

SETTING

Sixty-four intensive care units in nine countries.

PATIENTS

Adults with severe sepsis and vasopressor-dependent hypotension after a 96-h infusion of standard DAA.

INTERVENTIONS

A total of 193 patients received an intravenous infusion of extended DAA 24 microg/kg/h or sodium chloride placebo for a maximum of 72 h.

MEASUREMENTS AND RESULTS

At extended therapy initiation (baseline), DAA-group patients had lower protein C levels (P = 0.23) and higher vasopressor requirements, particularly for the primary vasopressor used, norepinephrine (P = 0.03), compared with placebo-group patients. DAA treatment did not result in a difference in the primary outcome of time to resolution of vasopressor-dependent hypotension versus placebo (P = 0.419). However, few patients reached resolution (DAA 34%, placebo 40%) as most continued to require vasopressor support after 72 additional hours of treatment. Treatment did not reduce 28-day all-cause mortality and in-hospital mortality or improve organ function compared with placebo, although there was a lower percentage change in D-dimers (P < 0.001) and increases in protein C levels were numerically greater on extended infusion. There was no difference in serious adverse events including bleeding events.

CONCLUSIONS

Extended DAA treatment did not result in more rapid resolution of vasopressor-dependent hypotension, despite demonstrating anticipated biological effects on D-dimer and protein C levels. A reduced planned sample size combined with baseline imbalances in protein C levels and vasopressor requirements may have limited the ability to demonstrate a clinical benefit.

Protein C: a potential biomarker in severe sepsis and a possible tool for monitoring treatment with drotrecogin alfa (activated)

Introduction

Drotrecogin alfa (activated; DrotAA) treatment, a 96-hour infusion, reduces 28-day mortality in severe sepsis to approximately 25%. The question remains whether a longer infusion or higher dose could increase rate of survival. The goal of this study was to identify a dependable, sensitive measure with which to monitor disease progression and response in patients during DrotAA treatment.

Methods

Data on severe sepsis patients included in PROWESS (placebo-controlled, double-blind, randomized study of 850 DrotAA and 840 placebo individuals) and ENHANCE (single-arm, open-label study of 2,375 DrotAA patients) studies were analyzed. In these studies, DrotAA (24 μg/kg per hour) or placebo was infused for 96 hours and patients were followed for 28 days. Data on six laboratory measures and five organ dysfunctions were systematically analyzed to identify a potential surrogate end-point for monitoring DrotAA therapy and predicting 28-day mortality at the end of therapy. To allow comparison across variables, sensitivity and specificity analyses identified cut-off values for preferred outcome, and relative risks for being above or below cut-offs were calculated, as was the 'proportion of treatment effect explained' (PTEE) to identify biomarkers that contribute to benefit from DrotAA.

Results

Protein C was the only variable that correlated with outcome across all analyses. Using placebo data, a baseline protein C under 40% was established as a useful predictor of outcome (odds ratio 2.12). Similar odds ratios were associated with cut-off values of other biomarkers, but the treatment benefit associated with DrotAA was significantly greater below the cut-off than above the cut-off only for protein C (relative risk for 28-day mortality 0.66 versus 0.88; P = 0.04). Protein C was the only end-of-infusion biomarker that potentially explained at least 50% of the benefit from DrotAA (PTEE 57.2%). The PTEE was 41% for cardiovascular Sequential Organ Failure Assessment score and for d-dimer. At the end of infusion (day 4), protein C categories (≤40%, 41% to 80%, and > 80%) remained significantly related to mortality, regardless of treatment assignment.

Conclusion

Based on systematic analyses of 11 variables measured in severe sepsis clinical trials, protein C was the only variable consistently correlated with both DrotAA treatment effect and survival. Further study is needed to determine whether longer infusions or higher doses of DrotAA would achieve the goal of normalizing protein C in more patients with severe sepsis.

Recombinant human activated protein C: current insights into its mechanism of action

Impairment of the protein C pathway plays a central role in the pathogenesis of sepsis. Administration of recombinant human activated protein C (rhAPC) may correct the dysregulated anticoagulant mechanism and prevent propagation of thrombin generation and formation of microvascular thrombosis. Furthermore, it may simultaneously modulate the inflammatory response. It is likely that the beneficial effect of rhAPC observed in experimental and clinical studies of severe sepsis results from a combination of mechanisms that modulate the entangled processes of coagulation and inflammation. This review presents an analysis of the various mechanisms of action of rhAPC in sepsis.

The protein C pathway: implications for the design of the RESPOND study

The predictive value of plasma protein C level in sepsis has been demonstrated in a number of studies in which depressed protein C levels were associated with increased likelihood of negative outcome. Data from the PROWESS (Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis) trial indicate that administration of drotrecogin alfa (activated; DrotAA) leads to an increase in endogenous protein C levels in severe sepsis patients. In a group as heterogeneous as sepsis patients, the currently approved dose and duration of administration (24 mug/kg per hour for 96 hours) might not be optimal in some individuals. The RESPOND (Research Evaluating Serial Protein C levels in severe sepsis patients ON Drotrecogin alfa [activated]) trial is a phase II study being conducted to explore the use of endogenous protein C level as both a biomarker and a steering parameter for administration of DrotAA. Eligible patients will receive DrotAA either at the normal, currently approved dose and duration of administration ('standard therapy') or at a higher dose with variable infusion duration or variable infusion duration only ('alternative therapy'). The duration of DrotAA infusion in the alternative therapy arm depends on the individual response in terms of sustained increase in endogenous protein C. The ultimate aims of this and potential following studies are as follows: to establish serial plasma protein C measurement as a biomarker that will aid in the identification of severe sepsis patients who are most likely to benefit from DrotAA therapy, to enable adjustment of DrotAA therapy in individual patients (specifically, the possibility to use a higher dose and to adjust the infusion duration), and to provide guidance to the clinician regarding whether the patient is responding to DrotAA.

Practical aspects of treatment with drotrecogin alfa (activated)

In November 2001, drotrecogin alfa (activated) was approved by the US Food and Drug Administration; in August 2002 it was approved by the European Medicines Agency. Since the approval of drotrecogin alfa (activated), however, critical care physicians have been faced with several challenges, namely its costs, selection of patients who are more likely to benefit from it, and the decision regarding when to start drotrecogin alfa (activated) treatment. There are also operational issues such as how to manage the infusion to deliver an effective treatment while minimizing the risk for bleeding, particularly in patients with deranged clotting, at around the time of surgery or during renal replacement therapy. While addressing these issues, this review remains practical but evidence based as much as possible.

Protein C -1641A/-1654C haplotype is associated with organ dysfunction and the fatal outcome of severe sepsis in Chinese Han population

Activation of protein C plays an important role in modulating coagulation as well as inflammation during severe sepsis. The baseline of activated protein C level in patients with severe sepsis showed interindividual variability between survivors and nonsurvivors, and the decreased level of protein C correlated with organ dysfunction and poor outcome. However, there are limited data concerning the genetic predisposition of individuals carrying two functional polymorphisms -1641A>G and -1654C>T within protein C gene to sepsis. Here we investigated the impact of these two variations on the development of severe sepsis in 240 patients with severe sepsis and 323 healthy controls using direct sequencing. After Bonferroni correction for multiple comparisons, -1641A/-1654C haplotype was significantly associated with the fatal outcome of severe sepsis (P = 0.008, OR 1.739, 95% CI 1.165-2.595), which was confirmed by multiple logistic regression analysis (P = 0.024, OR 2.090, 95% CI 1.101-3.967). Compared to patients without carrying -1641A/-1654C haplotype, the -1641A/-1654C haplotype carriers showed higher SOFAmax scores (10.3 +/- 5.2 vs. 9.0 +/- 4.5; P = 0.014) and more hepatic dysfunction (P = 0.004, OR 2.270, 95% CI 1.312-3.930). These findings suggest that protein C haplotype -1641A/-1654C is associated with organ dysfunction and is an independent risk factor for the fatal outcome of severe sepsis in Chinese Han population.