Soluble thrombomodulin, plasma-derived unactivated protein C, and recombinant human activated protein C in sepsis

Emerging roles of a chemoattractant receptor GPR15 and ligands in pathophysiology

Chemokine receptors play a central role in the maintenance of immune homeostasis and development of inflammation by directing leukocyte migration to tissues. GPR15 is a G protein-coupled receptor (GPCR) that was initially known as a co-receptor for human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV), with structural similarity to other members of the chemoattractant receptor family. Since the discovery of its novel function as a colon-homing receptor of T cells in mice a decade ago, GPR15 has been rapidly gaining attention for its involvement in a variety of inflammatory and immune disorders. The recent identification of its natural ligand C10orf99, a chemokine-like polypeptide strongly expressed in gastrointestinal tissues, has established that GPR15-C10orf99 is a novel signaling axis that controls intestinal homeostasis and inflammation through the migration of immune cells. In addition, it has been demonstrated that C10orf99-independent functions of GPR15 and GPR15-independent activities of C10orf99 also play significant roles in the pathophysiology. Therefore, GPR15 and its ligands are potential therapeutic targets. To provide a basis for the future development of GPR15- or GPR15 ligand-targeted therapeutics, we have summarized the latest advances in the role of GPR15 and its ligands in human diseases as well as the molecular mechanisms that regulate GPR15 expression and functions.

Endotheliopathy in Acute COVID-19 and Long COVID

The pulmonary endothelium is a highly regulated organ that performs a wide range of functions under physiological and pathological conditions. Since endothelial dysfunction has been demonstrated to play a direct role in sepsis and acute respiratory distress syndrome, its role in COVID-19 has also been extensively investigated. Indeed, apart from the COVID-19-associated coagulopathy biomarkers, new biomarkers were recognised early during the pandemic, including markers of endothelial cell activation or injury. We systematically searched the literature up to 10 March 2023 for studies examining the association between acute and long COVID-19 severity and outcomes and endothelial biomarkers.

Activation of immune signals during organ transplantation

The activation of host's innate and adaptive immune systems can lead to acute and chronic graft rejection, which seriously impacts graft survival. Thus, it is particularly significant to clarify the immune signals, which are critical to the initiation and maintenance of rejection generated after transplantation. The initiation of response to graft is dependent on sensing of danger and stranger molecules. The ischemia and reperfusion of grafts lead to cell stress or death, followed by releasing a variety of damage-associated molecular patterns (DAMPs), which are recognized by pattern recognition receptors (PRRs) of host immune cells to activate intracellular immune signals and induce sterile inflammation. In addition to DAMPs, the graft exposed to 'non-self' antigens (stranger molecules) are recognized by the host immune system, stimulating a more intense immune response and further aggravating the graft damage. The polymorphism of MHC genes between different individuals is the key for host or donor immune cells to identify heterologous 'non-self' components in allogeneic and xenogeneic organ transplantation. The recognition of 'non-self' antigen by immune cells mediates the activation of immune signals between donor and host, resulting in adaptive memory immunity and innate trained immunity to the graft, which poses a challenge to the long-term survival of the graft. This review focuses on innate and adaptive immune cells receptor recognition of damage-associated molecular patterns, alloantigens and xenoantigens, which is described as danger model and stranger model. In this review, we also discuss the innate trained immunity in organ transplantation.

Downregulation of thrombomodulin-thrombin-activated protein C pathway as a mechanism for SARS-CoV-2 induced endotheliopathy and microvascular thrombosis

There is emerging evidence of microvascular thrombosis and thrombotic microangiopathy (TMA) induced by COVID-19, presumably from endothelial injury. Thrombomodulin (TM) is an endothelial glycoprotein that plays a dual role in maintaining healthy endothelium-as a natural anticoagulant by binding thrombin to activate protein C (APC) and a negative regulator of the alternate complement pathway (AP). TM is shed into the plasma as soluble TM (sTM) during endothelial injury. We hypothesize that SARS-CoV-2 spike proteins cause direct microvascular endothelial injury, leading to TM shedding, decreased activation of PC, and consequently, microvascular thrombosis in COVID-19. We conducted this study twofold: 1) in vivo, we assessed endothelial injury (by measuring sTM) and AP activation by quantifying Ba (cleavage product of AP component Factor B) in a cohort of critically ill COVID-19 pediatric patients and the implications on clinical outcomes; and 2)in vitro, we investigated endothelial injury (TM shedding) by SARS-COV-2 spike proteins and the subsequent functional consequence in activated PC (APC) levels and Ba levels. sTM and Ba in plasma samples from SARS-CoV-2 positive patients admitted to Texas Children's Hospital Pediatric Intensive Care Unit (n = 33) and from healthy controls (n = 38) were measured by ELISA. In vitro, confluent glomerular microvascular endothelial cells (GMVECs) were incubated for 48 h in the presence or absence (control) of purified SARS-CoV-2 spike proteins, S1 and S2. TM from the cell lysates while Ba and APC from the cell supernatants were measured by ELISA. sTM and Ba levels were significantly higher in the COVID-19 pediatric patients compared to healthy controls (p < 0.01 and p < 0.001, respectively). Among the COVID-19 patients, elevated sTM was associated with increased vasopressor use (p = 0.01) and elevated Ba was associated with increased duration of mechanical ventilation (p = 0.04). In vitro, surface bound TM and soluble APC were significantly lower in GMVECs after addition of spike proteins (p < 0.05), while Ba was undetectable in both control and spike proteins exposed GMVECs. In conclusion, we provide evidence of endothelial injury in COVID-19 pediatric patients and demonstrate a potential pathway of SARS-CoV-2 induced thrombosis. Decreased surface-bound TM results in lower amount of thrombin-TM complex, hence lesser activation of PC, likely leading to a pro-thrombotic state. These findings in GMVECs could explain the vulnerability of kidneys to COVID-19-induced TMA.

Vitamin K in COVID-19—Potential Anti-COVID-19 Properties of Fermented Milk Fortified with Bee Honey as a Natural Source of Vitamin K and Probiotics

Vitamin K deficiency is evident in severe and fatal COVID-19 patients. It is associated with the cytokine storm, thrombotic complications, multiple organ damage, and high mortality, suggesting a key role of vitamin K in the pathology of COVID-19. To support this view, we summarized findings reported from machine learning studies, molecular simulation, and human studies on the association between vitamin K and SARS-CoV-2. We also investigated the literature for the association between vitamin K antagonists (VKA) and the prognosis of COVID-19. In addition, we speculated that fermented milk fortified with bee honey as a natural source of vitamin K and probiotics may protect against COVID-19 and its severity. The results reported by several studies emphasize vitamin K deficiency in COVID-19 and related complications. However, the literature on the role of VKA and other oral anticoagulants in COVID-19 is controversial: some studies report reductions in (intensive care unit admission, mechanical ventilation, and mortality), others report no effect on mortality, while some studies report higher mortality among patients on chronic oral anticoagulants, including VKA. Supplementing fermented milk with honey increases milk peptides, bacterial vitamin K production, and compounds that act as potent antioxidants: phenols, sulforaphane, and metabolites of lactobacilli. Lactobacilli are probiotic bacteria that are suggested to interfere with various aspects of COVID-19 infection ranging from receptor binding to metabolic pathways involved in disease prognosis. Thus, fermented milk that contains natural honey may be a dietary manipulation capable of correcting nutritional and immune deficiencies that predispose to and aggravate COVID-19. Empirical studies are warranted to investigate the benefits of these compounds.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

Endothelial biomarkers in the light of new sepsis definition

The aim of our study was to compare usefulness of endothelial biomarkers for severity and outcome prediction in patients with positive Sepsis-3 criteria with traditionally used biomarkers. A total of 150 patients were included in our study. Patients were divided into two groups: patients with sepsis and those with infectious systemic inflammatory response syndrome. Development of septic shock and 28-day mortality were assessed. Endocan and thrombomodulin showed better discriminative power than procalcitonin for the presence of sepsis. Endocan showed good discriminative power for septic shock prediction. Addition of endocan significantly contributed to sequential (sepsis-related) organ failure assessment score in logistic regression model. Conclusion: Endothelial biomarkers have a good diagnostic potential for sepsis. Endocan is useful as a predictor of the severity and fatality of sepsis.

Increased serum thrombomodulin level is associated with disease severity and mortality in pediatric sepsis

Background

Endothelial dysfunction plays an important role in the pathophysiology of sepsis. As previously reported, the serum thrombomodulin is elevated in diseases associated with endothelial injury.

Objective

The aim of this study was to investigate the association of serum thrombomodulin level in different pediatric sepsis syndromes and evaluate the relationship with disease severity and mortality.

Methods

We prospectively collected cases of sepsis treated in a pediatric intensive care unit from June 2012 to July 2015 at Chang Gung Children’s Hospital in Taoyuan, Taiwan. Clinical characteristics and serum thrombomodulin levels were analyzed.

Results

Increased serum thrombomodulin levels on days 1 and 3 of the diagnosis of sepsis were found in different pediatric sepsis syndromes. Patients with septic shock had significantly increased serum thrombomodulin levels on days 1 and 3 [day 1: median, 6.9 mU/ml (interquartile range (IQR): 5.8–12.8) and day 3: median, 5.8 mU/ml (IQR: 4.6–10.8)] compared to healthy controls [median, 3.4 mU/ml (IQR: 2.3–4.2)] (p = <0.001 and 0.001, respectively) and those with sepsis [day 1: median, 2.9 mU/ml (IQR: 1.8–4.7) and day 3: median, 3 mU/ml (IQR: 1.5–3.5)] and severe sepsis [day 1: median, 3.3 mU/ml (IQR: 1.3–8.6) and day 3: median, 4.4 mU/ml (IQR: 0.5–6)] (p = <0.001 and 0.001, respectively). There was also a significant positive correlation between serum thrombomodulin level on day 1 and day 1 PRISM-II, PELOD, P-MOD and DIC scores. The patients who died had significantly higher serum thrombomodulin levels on days 1 and 3 [day 1: median, 9.9 mU/ml (IQR: 6.2–15.6) and day 3: median, 10.4 mU/ml (IQR: 9.2–11.7)] than the survivors [day 1; median, 4.4 mU/ml (IQR: 2.2–7.5) and day 3: [median, 3.5 mU/ml (IQR: 1.6–5.7)] (p = 0.046 and 0.012, respectively).

Conclusion

Increased serum thrombomodulin levels were found in different pediatric sepsis syndromes and correlated with disease severity and mortality.

Procoagulant and fibrinolytic activity after polytrauma in rat

The purpose of this study was to determine whether trauma-induced coagulopathy is due to changes in 1) thrombin activity, 2) plasmin activity, and/or 3) factors that stimulate or inhibit thrombin or plasmin. Sprague-Dawley rats were anesthetized with 1-2% isoflurane/100% oxygen, and their left femoral artery and vein were cannulated. Polytrauma included right femur fracture, and damage to the small intestines, the left and medial liver lobes, and right leg skeletal muscle. Rats were then bled 40% of blood volume. Plasma samples were taken before trauma, and at 30, 60, 120, and 240 min. Polytrauma and hemorrhage led to a significant fall in prothrombin levels. However, circulating thrombin activity did not change significantly over time. Antithrombin III and α2 macroglobulin fell significantly by 2 h, then rose by 4 h. Soluble thrombomodulin was significantly elevated over the 4 h. Circulating plasmin activity, plasminogen, and D-dimers were elevated for the entire 4 h. Tissue plasminogen activator (tPA) was elevated at 30 min, then decreased below baseline levels after 1 h. Plasminogen activator inhibitor-1 was significantly elevated at 2-4 h. Neither tissue factor pathway inhibitor nor thrombin activatable fibrinolysis inhibitor changed significantly over time. The levels of prothrombin and plasminogen were 30-100 times higher than their respective active enzymes. Polytrauma and hemorrhage in rats lead to a fibrinolytic coagulopathy, as demonstrated by an elevation in plasmin activity, D-dimers, and tPA. These results are consistent with the observed clinical benefit of tranexamic acid in trauma patients.

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.

Thrombomodulin is a Strong Predictor of Multiorgan Dysfunction Syndrome in Patients With Sepsis

BACKGROUND

Biomarkers of endothelial dysfunction are not recommended for routine laboratory investigation of the outcome prognosis and prediction of the course of sepsis.

METHODS

A total of 60 patients who fulfilled the criteria for diagnosis of sepsis were included in our study. Development of multiorgan dysfunction syndrome (MODS) in the first 48 hours was assessed. Differences between groups of patients with sepsis were assessed by Mann-Whitney U test and by Kruskal-Wallis test. Logistic regression analysis was performed to test the joint effect of different predictors.

RESULTS

Level of thrombomodulin was significantly higher in group of patients with MODS than without MODS (P = .015). Levels of antithrombin (P = .026) and protein C (P = .035) were significantly lower in patients with MODS. Level of thrombomodulin was the strongest predictor in MODS development in first 48 hours (P = .028).

CONCLUSION

The level of thrombomodulin not only was able to distinguish the severity of sepsis but also was a significant predictor of MODS development.

Therapeutic modulation of coagulation and fibrinolysis in acute lung injury and the acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are characterized by excessive intraalveolar fibrin deposition, driven, at least in part by inflammation. The imbalance between activation of coagulation and inhibition of fibrinolysis in patients with ALI/ARDS favors fibrin formation and appears to occur both systemically and in the lung and airspace. Tissue factor (TF), a key mediator of the activation of coagulation in the lung, has been implicated in the pathogenesis of ALI/ARDS. As such, there have been numerous investigations modulating TF activity in a variety of experimental systems in order to develop new therapeutic strategies for ALI/ARDS. This review will summarize current understanding of the role of TF and other proteins of the coagulation cascade as well the fibrinolysis pathway in the development of ALI/ARDS with an emphasis on the pathways that are potential therapeutic targets. These include the TF inhibitor pathway, the protein C pathway, antithrombin, heparin, and modulation of fibrinolysis through plasminogen activator- 1 (PAI-1) or plasminogen activators (PA). Although experimental studies show promising results, clinical trials to date have proven unsuccessful in improving patient outcomes. Modulation of coagulation and fibrinolysis has complex effects on both hemostasis and inflammatory pathways and further studies are needed to develop new treatment strategies for patients with ALI/ARDS.

Critical role of activated protein C in early coagulopathy and later organ failure, infection and death in trauma patients

BACKGROUND

Recent studies have identified an acute traumatic coagulopathy that is present on admission to the hospital and is independent of iatrogenic causes. We have previously reported that this coagulopathy is due to the association of severe injury and shock and is characterized by a decrease in plasma protein C (PC) levels. Whether this early coagulopathy and later propensity to infection, multiple organ failure and mortality are associated with the activation of PC pathway has not been demonstrated and constitutes the aim of this study.

METHODS AND FINDINGS

This was a prospective cohort study of 203 major trauma patients. Serial blood samples were drawn on arrival in the emergency department, and at 6, 12, and 24 hours after admission to the hospital. PT, PTT, Va, VIIIa, PC aPC t-PA, and D-dimer levels were assayed. Comprehensive injury, resuscitation, and outcome data were prospectively collected. A total of 203 patients were enrolled. Patients with tissue hypoperfusion and severe traumatic injury showed a strong activation of the PC which was associated with a coagulopathy characterized by inactivation of the coagulation factors V and VIII and a derepression of the fibrinolysis with high plasma levels of plasminogen activator and high D-dimers. Elevated plasma levels of activated PC were significantly associated with increased mortality, organ injury, increased blood transfusion requirements, and reduced ICU ventilator-free days. Finally early depletion of PC after trauma is associated with a propensity to posttraumatic ventilator-associated pneumonia.

CONCLUSIONS

Acute traumatic coagulopathy occurs in the presence of tissue hypoperfusion and severe traumatic injury and is mediated by activation of the PC pathway. Higher plasma levels of aPC upon admission are predictive of poor clinical outcomes after major trauma. After activation, patients who fail to recover physiologic plasma values of PC have an increased propensity to later nosocomial lung infection.

Animal models of DIC and their relevance to human DIC: a systematic review

Disseminated intravascular coagulation (DIC) is a severe clinical condition with activation of coagulation and fibrinolysis. Its diagnosis is based on the International Society of Thrombosis and Haemostasis (ISTH) scoring system of DIC. Animal models of DIC, used to investigate pathophysiology and evaluate treatments, have not been developed in a standardized way, which impedes comparison between models and translation to the human setting. In the current review of animal models of DIC an overview of species, inducers, and dosing regimens is provided. Diagnostic approaches are compared in the light of the ISTH score and treatments tested in animal models of DIC are summarized. Systematic analysis revealed that the rat is by far the preferred species amongst animal models of DIC and lipopolysaccharides (LPS) the preferred inducer of DIC. An overview of the reporting of ISTH DIC score parameters elucidated that only about 25% of the studies measure all of the four parameters necessary for the implementation the ISTH scoring system. Furthermore, most therapeutic interventions tested in animal models of DIC are administered prophylactically, which may be irrelevant to the clinical setting and could explain why compounds effective in preclinical animal models often fail in clinical trials. It is concluded that Implementation of a scoring system in animal models of DIC may increase the ability to compare DIC amongst animal models and improve the translational aspect of treatment effect.

Recombinant human activated protein C inhibits integrin-mediated neutrophil migration

Integrin-mediated cell migration is central to many biologic and pathologic processes. During inflammation, tissue injury results from excessive infiltration and sequestration of activated leukocytes. Recombinant human activated protein C (rhAPC) has been shown to protect patients with severe sepsis, although the mechanism underlying this protective effect remains unclear. Here, we show that rhAPC directly binds to beta(1) and beta(3) integrins and inhibits neutrophil migration, both in vitro and in vivo. We found that human APC possesses an Arg-Gly-Asp (RGD) sequence, which is critical for the inhibition. Mutation of this sequence abolished both integrin binding and inhibition of neutrophil migration. In addition, treatment of septic mice with a RGD peptide recapitulated the beneficial effects of rhAPC on survival. Thus, we conclude that leukocyte integrins are novel cellular receptors for rhAPC and the interaction decreases neutrophil recruitment into tissues, providing a potential mechanism by which rhAPC may protect against sepsis.

Disseminated intravascular coagulation: current concepts

Disseminated intravascular coagulation (DIC) is an acquired disorder in which normal hemostatic balance is disturbed. There is excessive thrombin formation leading to fibrin deposition in microcirculation and consequent ischemic organ damage. The etiology is multifactorial. A number of medical, surgical, oncological and obstetrical conditions can cause DIC. The diagnosis is essentially clinical supported by laboratory parameters and a scoring system based on these. The mainstay of treatment is correction of underlying cause and hemostatic support with replacement of coagulation factors. The role of heparin therapy and other therapeutic options including activated protein C, antithrombin III etc. have also been discussed.

Study of proinflammatory responses induced by Yersinia pestis in human monocytes using cDNA arrays

Yersinia pestis, the causative agent of plague, is known to develop strategies to overcome the host immune mechanisms and survive in the host. The molecular changes induced by Y. pestis in the host are not well delineated. Here, we examined the early events triggered after the intracellular infection of Y. pestis in human monocytes and lymphocytes by analyzing the host transcriptional profiles using cDNA arrays. We found that sets of genes that, especially at early time periods, were highly upregulated in monocytes alone when compared with a mixed culture of lymphocytes and monocytes. Gene expression responses revealed genes coding for cytokines, chemokines, transcription factors, inflammatory and apoptosis-related genes. Protein levels were measured, and real-time polymerase chain reaction was used to validate the microarray results. Our data suggest that intracellular infection of human monocytes with Y. pestis results in a strong inflammatory response at early time periods and a downregulation of genes such as thromobomodulin, which may play a role in coagulation, resulting in disseminated intravascular coagulation, a primary cause of death in plague infected hosts. We provide evidence that genomic analysis can provide a solid foundation to mechanistic insights to explain some of the symptoms induced by Y. pestis.

MLCK210 gene knockout or kinase inhibition preserves lung function following endotoxin-induced lung injury in mice

Barrier dysfunction, involving the endothelium or epithelium, is implicated in the pathophysiology of many disease states, including acute and ventilator-associated lung injury. Evidence from cell culture, in vivo and clinical studies, has identified myosin light chain kinase as a drug discovery target for such diseases. Here, we measured disease-relevant end points to test the hypothesis that inhibition of myosin light chain kinase is a potential therapeutic target for treatment of barrier dysfunction resulting from acute lung injury. We used a combined gene knockout and chemical biology approach with an in vivo intact lung injury model. We showed that inhibition of myosin light chain kinase protects lung function, preserves oxygenation, prevents acidosis, and enhances survival after endotoxin exposure with subsequent mechanical ventilation. This protective effect provided by the small molecule inhibitor of myosin light chain kinase is present when the inhibitor is administered during a clinically relevant injury paradigm after endotoxin exposure. Treatment with inhibitor confers additional protection against acute lung injury to that provided by a standard protective mode of ventilation. These results support the hypothesis that myosin light chain kinase is a potential therapeutic target for acute lung injury and provide clinical end points of arterial blood gases and pulmonary compliance that facilitate the direct extrapolation of these studies to measures used in critical care medicine.

The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility

This is the first study to examine the hypothesis that prolonged sitting is associated with procoagulant changes in the local lower-limb venous system. A comparison was made with upper-limb venous changes. Changes in markers of thrombin generation, fibrinolysis, endothelial perturbation and haemoconcentration were analysed as 10 healthy adult male participants sat for 8 h. The change in foot volume was estimated. Subjective venous thromboembolism assessment was undertaken hourly, along with 2-week and 4-week safety follow-up for clinical events. Expected increases in median prothrombin fragments 1 and 2, thrombin-antithrombin complex and D-dimer were not observed in either limb. An increase greater than 45% in the median tissue plasminogen activator and plasminogen activator-1 molar ratio (t-PA/PAI-1), and a decrease greater than 15% in median soluble thrombomodulin were noted in both limbs. Median haematocrit decreased minimally (1%) in the lower limbs, while the foot volume increased by 4%. Subjects experienced vague symptoms after 6 h of sitting, but none developed symptomatic venous thromboembolism. Upper and lower-limb changes in biomarkers did not correlate, except those in t-PA/PAI-1 ratio and plasminogen activator-1. Significant correlation was found between changes in the lower-limb t-PA/PAI-1 ratio and right foot volume. This study originally reveals that even in the lower limbs, prolonged daytime cramped sitting is not associated with significant procoagulant changes in healthy adult male volunteers, and confirms a previous observation that local lower-limb venous changes are not identically reflected in the upper limbs.

From bench to bedside: a review of the clinical trial development plan of drotrecogin alfa (activated)

OBJECTIVE

To provide a comprehensive overview of the various clinical trials of drotrecogin alfa (activated) (DrotAA) completed by Eli Lilly and Company over the past 10 years.

METHODS

Eli Lilly and Company data from phase 1 through phase 4 trials, observational studies, and compassionate-use studies of DrotAA were reviewed. Safety, efficacy, and pharmacokinetic data were included. The review excluded pediatric studies and studies recently concluded where the manuscript was in press. All studies included in the review were approved by the ethical review boards at the participating institutions.

RESULTS

Over 9000 adults with severe sepsis have been enrolled in DrotAA clinical trials through December 2005 and the results of the clinical evaluation of DrotAA have been widely disseminated in publications. Analyses of the data indicate that the pharmacokinetics of DrotAA are both linear and dose-proportional. The phase 2 and phase 3 studies of administration of DrotAA to patients with severe sepsis demonstrated a significant reduction in mortality and were associated with a favorable benefit/risk profile. Three of these trials (a phase 2 and two phase 3, PROWESS and ENHANCE) evaluated the effect of DrotAA in adult patients with sepsis associated with acute organ dysfunction (severe sepsis) while another phase 3 trial (ADDRESS) was conducted in the non-indicated population of adult patients with severe sepsis associated with a lower risk of death. A phase 4 trial demonstrated no significant difference in steady-state plasma concentrations or elimination half-life of DrotAA between patients < or =135 kg and >135 kg, indicating that DrotAA should be dosed by actual body weight.

DISCUSSION

The challenges and limitations of the clinical development plan for DrotAA are discussed.

CONCLUSION

DrotAA is indicated for the reduction of mortality in adult patients with severe sepsis (sepsis associated with acute organ dysfunction) who have a high risk of death. DrotAA is not indicated in adult patients with severe sepsis and low risk of death. The clinical plan for DrotAA continues with a focus on tailored therapy and identifying the most appropriate patients for DrotAA treatment.

Coagulation interventions in experimental human endotoxemia

Recognition of the link between coagulation activation and inflammation has led to the hypothesis that anticoagulants may be effective in the treatment of septic patients by altering the inflammatory response. However, only limited methodologies exist that can be used in human volunteers to mimic the physiologic alterations observed in critically ill patients. The human endotoxemia model represents a model of inflammation-induced tissue factor triggered coagulation activation. As it permits elucidation of a key player in this proinflammatory and procoagulant response, it serves as a useful tool to investigate novel therapeutics in a standardized setting. The aim of this review is to focus on coagulation interventions in the human endotoxemia model.

Endotoxaemia induces resistance to activated protein C in healthy humans

Systemic inflammation activates the tissue factor/factor VIIa complex (TF/FVIIa), leading to a procoagulant state, which may be enhanced by impairment of physiological anticoagulant pathways, such as the protein C system. Besides impaired protein C activation, resistance to activated protein C (APC) may occur. We studied the effect of endotoxemia on APC resistance, analysed its determinants and evaluated the effect of TF/FVIIa inhibition on endotoxin-induced APC resistance. Sixteen healthy male volunteers participated in the study, eight receiving endotoxin alone and eight receiving the combination of endotoxin and recombinant Nematode Anticoagulant Protein c2 (rNAPc2), a potent inhibitor of TF/FVIIa. Parameters of coagulation were subsequently studied. The sensitivity to APC was determined by two tests: a test based on the endogenous thrombin potential and a test based on the activated partial thromboplastin time. In response to endotoxemia, both tests detected a transient APC resistance that was predominantly mediated by an increase in factor VIII and was not influenced by TF/FVIIa inhibition. In vitro tests confirmed that an increase in factor VIII induced APC resistance, as measured by both tests. This finding suggests that APC resistance might play a role in the procoagulant state occurring during human endotoxemia.

The influence of age on in vitro plasmin generation in the presence of fibrin monomer

BACKGROUND AND OBJECTIVES

The components of the fibrinolytic system interact to generate plasmin from its zymogen form, plasminogen. At birth, all the components of the fibrinolytic system are present but with differing plasma concentrations. The present study was undertaken to explore the effect of physiological, age-dependent factors of the fibrinolytic system during childhood on the capacity to generate plasmin.

DESIGN AND METHODS

Total plasmin generation was measured in venous plasma from umbilical cords and adults, on plastic and cell surfaces, in the presence of fibrin monomer, Desafib. Plasminogen, its inhibitors alpha2-antiplasmin and plasminogen activator inhibitor type 1, and plasmin-alpha2-antiplasmin complex in the time samples were assayed by enzyme-linked immunosorbent assay. The effect of addition of plasminogen on the plasmin generation in cord plasma and the effect of lipoprotein on adult and cord plasmin generation were measured.

RESULTS

On the surface of human umbilical vein endothelial cells, onset of plasmin generation was earlier (40 min) compared to plastic (60 min) but total plasmin generation was similar on both surfaces. The addition of plasminogen to cord plasma increased plasmin generation. Supplementation of lipoprotein in adult plasma had an inhibitory effect, but there was no significant effect in cord plasma.

INTERPRETATIONS AND CONCLUSIONS

Plasmin generation is reduced in newborn compared to adult plasma. Decreased plasmin generation in cord plasma is likely due to decreased plasminogen concentration. The antifibrinolytic effect of lipoprotein is more pronounced in adults as compared to newborns due to the presence of higher plasminogen concentration.

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.

Challenge and Rechallenge: Drotrecogin alfa (activated)–Induced Prolongation of Activated Partial Thromboplastin Time in a Patient with Severe Sepsis

An 81-year-old woman with ischemic bowel underwent laparotomy with small-bowel resection and developed septic shock. She required broadspectrum antibiotics, norepinephrine, and mechanical ventilation. The patient received drotrecogin alfa (activated) 24 microg/kg/hour for a total of 67.5 hours. Coagulation parameters were monitored during her therapy. Significant increases in activated partial thromboplastin time (aPTT) during infusion led to two temporary discontinuations of the drug. Coagulation parameters decreased when the drug was held and increased with each rechallenge. The patient survived the episode and was discharged on postoperative day 27. Medical records of 26 other patients who received drotrecogin alfa (activated) at our institution from November 2001-August 2003 were reviewed retrospectively for coagulation parameters and bleeding rate. Of the 26 patients, nine (35%) were treatment compliant (>90% of the 96-hr course). Coagulopathy and bleeding resulted in early discontinuation in four (15%) and six (23%) patients, respectively. An increase in aPTT from baseline to during infusion of drotrecogin alfa (activated) was noted in 14 patients with complete data (p=0.56). A decrease in median platelet count from baseline to during infusion was noted in the six patients who bled during therapy (p=0.01). Two of these patients had platelet counts less than 30x10(3)/mm3 during administration. Drotrecogin alfa (activated) should be considered an anticoagulant. In postmarketing reports, clinically significant bleeding occurred more frequently than was noted in a large, randomized, multicenter trial. Patients receiving drotrecogin alfa (activated) should be closely monitored for prolongation of coagulation parameters. Temporary discontinuation of the drug should be considered when international normalized ratio is greater than 3.0, platelet count is less than 15x10(3)/mm3, and aPTT is greater than 100 seconds.

Recombinant human activated protein C resets thrombin generation in patients with severe sepsis - a case control study

Introduction

Recombinant human activated protein C (rhAPC) is the first drug for which a reduction of mortality in severe sepsis has been demonstrated. However, the mechanism by which this reduction in mortality is achieved is still not clearly defined. The aim of the present study was to evaluate the dynamics of the anticoagulant, anti-inflammatory and pro-fibrinolytic action of rhAPC in patients with severe sepsis, by comparing rhAPC-treated patients with case controls.

Methods

In this prospectively designed multicenter case control study, 12 patients who were participating in the ENHANCE study, an open-label study of rhAPC in severe sepsis, were treated intravenously with rhAPC at a constant rate of 24 μg/kg/h for a total of 96 h. Twelve controls with severe sepsis matching the inclusion criteria received standard therapy. The treatment was started within 48 h after the onset of organ failure. Blood samples were taken before the start of the infusion and at 4, 8, 24, 48, 96 and 168 h, for determination of parameters of coagulation and inflammation.

Results

Sepsis-induced thrombin generation as measured by thrombin-antithrombin complexes and prothrombin fragment F1+2, was reset by rhAPC within the first 8 h of infusion. The administration of rhAPC did not influence parameters of fibrinolysis and inflammation. There was no difference in outcome or occurrence of serious adverse events between the treatment group and the control group.

Conclusion

Sepsis-induced thrombin generation in severely septic patients is reset by rhAPC within the first 8 h of infusion without influencing parameters of fibrinolysis and inflammation.

[Disturbances of protein C activity in abdominal sepsis: diagnostic and predictive importance]

BACKGROUND

Despite improved diagnostic modalities, potent antibiotics, modern intensive care, and aggressive surgical treatment, more than one third of patients still die of severe secondary peritonitis. Clinical difficulties in the treatment of abdominal sepsis were related to inherent problems of limited clinical signs and the rapid spread of infection. An inflammatory process is often well under way before the presence of clinical signs and symptoms of sepsis. The aim of this prospective study was to assess diagnostic and prognostic significance of protein C in abdominal sepsis.

METHODS

Twenty-two patients with severe intraabdominal infections with sepsis syndrome were treated surgically as compared to 15 patients with hernia repair (control group). During the study, the following parameters were analyzed daily: protein C, AT III, plasminogen, alfa-2 antiplasmin, HMWK, C5a and C5-B9 complement, C1-inhibitor, CRP. RESULTS. The mean APACHE II score was 17 points, with actual mortality rate of 23%. Each parameter evaluated in the abdominal sepsis group differed from the one evaluated in the control group to a great extent (p = 0.001). The results and multivariate regression statystical analysis confirmed the following parameters as sensitive biological markers of septic cascade (p < 0.0001-0.026): protein C, AT III, HMWK, C1-inhibitor and C5-B9 complement. According to the results the low level of protein C consistently correlated with disease severity and suggested the development of septic shock and poor outcome.

CONCLUSION

Early diagnosis of plasma proteolytic disturbances was very important, from the diagnostic and predictive point of view, in abdominal sepsis. According to the results protein C was the most significant marker of sepsis and early predictor of the outcome of septic complications during severe intraabdominal infections (r = 0.761; p = 0.0001).

Drotrecogin alfa: a role in emergency department treatment of severe sepsis?

Human protein C is a serine protease that circulates in the blood as an inactive zymogen. It is converted to its active form by interaction with thrombomodulin on the endothelial wall. Activated protein C has a significant role in maintaining haemostasis, and is a major mechanism of controlling microvascular thrombosis. Recent reports describe the use of drotrecogin alfa (recombinant activated protein C) in severe sepsis, a condition relevant to emergency medicine. This review describes the physiology of the protein C pathway and its importance in sepsis. It will also focus on the use of drotrecogin alfa in sepsis, and its use in the ED.

Covalently immobilized thrombomodulin inhibits coagulation and complement activation of artificial surfaces in vitro

Thrombomodulin (TM) serves as the endothelial cell receptor for thrombin and alters its characteristics from pro- to anticoagulant. Additionally, it promotes the formation of activated protein C. We evaluated the conservation of the overall outcome of these functions in recombinant TM linked to artificial surfaces by incubation with human whole blood in vitro. TM was covalently immobilized through poly(ethylene glycol) (PEG) spacers onto thin films of poly(octadecene alt maleic anhydride) covering planar glass substrates. TM binding to the polymer films was achieved after active ester formation at the carboxylic acid terminus of the PEG spacers and thoroughly characterized by HPLC-based amino acid analysis, immunofluorescence and ellipsometry. TM-coated samples were incubated for 3h with freshly drawn whole human blood anticoagulated with heparin (5IU/ml) using in-house developed incubation systems. The substantially reduced activation of blood coagulation (TAT) for TM-coated samples correlates well with the degree of contact activation (bradykinin and FXIIa formation) while no significant effects were observed for the platelet activation (PF4). Further, complement activation (C5a levels), was strongly diminished at the TM-containing surfaces. We conclude that the suggested method for preparation of TM immobilization may serve to prepare model substrates for studies on TM interactions but similarly provides a promising coating strategy for blood contacting medical devices.

The use of activated protein C (drotrecogin alfa (activated)) in the treatment of severe sepsis

Advances in intensive care have allowed many critically ill patients to survive their initial insult. These patients may later demonstrate multiple organ dysfunction and failure, the genesis of which appears to be the body's reaction to critical illness, manifested by an imbalance and failure of inflammatory and immune system homeostasis. The manifestation of multiple organ dysfunction in the critically ill has been termed multiple organ dysfunction syndrome (MODS). MODS mortality is high and remains a leading cause of death in intensive care units (ICUs). The understanding of the pathophysiology of severe sepsis and MODS has moved from a focus on inflammation to include an understanding of the associated anti-inflammatory responses. Loss of homeostasis can manifest as malignant inflammation or immune paralysis. Increased emphasis is emerging on the role of loss of immune homeostasis and disordered coagulation as a cause of organ injury and dysfunction. Treatment of severe sepsis is based upon aggressive resuscitation, source control and support for failing organs. Novel therapies directed at the modifying the inflammatory response have, up to now, not proven beneficial. However, a new agent, drotrecogin alfa (activated) has been shown, in a phase III randomised controlled trial, to be of benefit in the treatment of severe sepsis. This new agent affects both the inflammatory and coagulation dimensions of severe sepsis. The developing concepts of the pathophysiology of sepsis and the emergence of a new therapy increases the complexity of the already complex demands of providing nursing care for the patient with severe sepsis and MODS. This article reviews pathophysiological processes in sepsis, reviews clinical data on activated protein C and illustrates the utility of this therapy in a case study.

Recombinant human activated protein C (rhAPC; drotrecogin alfa [activated]) has minimal effect on markers of coagulation, fibrinolysis, and inflammation in acute human endotoxemia

Inflammatory and procoagulant host responses are closely related in sepsis. The protein C pathway serves as a regulatory pathway with anti-inflammatory and anticoagulant properties. Recently, recombinant human activated protein C (rhAPC) was shown to reduce mortality in severe sepsis. Nevertheless, the effects of rhAPC in humans are still ill defined. The infusion of low endotoxin doses into humans provides a standardized model to study inflammatory and hemostatic mechanisms. Thus, we investigated whether rhAPC acts as an anticoagulant or anti-inflammatory drug in human endotoxemia. There were 24 volunteers randomized to receive either 24 microg/kg per hour rhAPC or placebo intravenously for 8 hours. Lipopolysaccharide (LPS, 2 ng/kg) was administered 2 hours after starting the infusions. rhAPC decreased basal tissue factor (TF)-mRNA expression, and thrombin formation and action. In contrast, rhAPC did not significantly blunt LPS-induced thrombin generation. Consistently, rhAPC did not reduce LPS-induced levels of TF-mRNA or D-dimer and had no effect on fibrinolytic activity or inflammation. Finally, endogenous APC formation was enhanced during endotoxemia and appeared to be associated with inflammation rather than thrombin formation. In conclusion, even low-grade endotoxemia induces significant protein C activation. Infusion of rhAPC decreases "spontaneous" activation of coagulation but does not blunt LPS-induced, TF-mediated coagulation in healthy volunteers, which is in contrast to a number of anticoagulants.

Physiologic inhibitors of coagulation in patients on chronic hemodialysis

Patients on hemodialysis are at increased risk for bleeding and thromboses. The intriguing balance between these risks is more complex than once thought, as endogenous clotting factors and their regulators come into contact with bioincompatible dialyzer membranes, in the setting of an extracorporeal circuit of blood flow, in the face of the uremic state. In this review, we summarize the current data on the interaction between the physiologic inhibitors of coagulation and hemodialysis. Data sources and study selection were obtained from research and review articles related to the endogenous anticoagulation pathway published in English on MEDLINE from 1972 to 2002. While protein C activity and protein S antigen concentrations are increased, there is no change in antithrombin III levels during hemodialysis in relation to predialysis levels. Plasma protein Z, which has only recently been studied in uremic subjects, is increased as well. In addition, hemodialysis leads to elevated tissue factor plasminogen inhibitor, thrombomodulin, tissue plasminogen activator, and plasminogen activator inhibitor-1 activities. The potential functional significance of these observations is discussed. Finally, as erythropoietin is commonly prescribed to uremic patients and is recognized to be prothrombotic, an appraisal of its interaction with the naturally occurring anticoagulants is presented. It is apparent that we are only beginning to realize the complexity of the interplay between this myriad of serum factors and hemodialysis. Further research is needed to shed light on this underexplored area of hemodialysis.

Anticoagulant therapy in acute lung injury

OBJECTIVE

To review the rationale for evaluating anticoagulant therapies in acute lung injury (ALI) and to review selected data regarding the effectiveness of anticoagulants in animals and human patients with ALI and acute respiratory distress syndrome.

DATA SOURCES

Published literature on coagulation alterations and anticoagulant strategies in ALI during the past 25 yrs.

DATA EXTRACTION AND SYNTHESIS

In the lung, alveolar and interstitial fibrin deposition are the hallmarks of early phase ALI. Local procoagulant activity and reduced fibrinolysis constitute the rationale for anticoagulant use in the treatment of ALI. An activated complex of tissue factor and factor VIIa triggers procoagulant activity in the lung, with subsequent thrombin formation and fibrin deposition. Increased pulmonary vascular permeability and leukocyte accumulation have been successfully prevented in animals treated with tissue factor/activated factor VII pathway inhibitor. In humans, a phase II study evaluating tissue factor pathway inhibitor in the treatment of severe sepsis suggested that lung function in acute respiratory distress syndrome patients was improved. However, the phase III trial failed to demonstrate a survival benefit; data regarding respiratory dysfunction have not yet been published. Heparin, despite effectively inhibiting thrombin formation, has not shown consistent benefits in reducing lung injury, and its efficacy has not yet been evaluated in a controlled study. Antithrombin administration in animals has shown consistent benefits with ALI, but clinical studies have failed to demonstrate reductions in mortality and lung injury. Activated protein C administration has been shown to improve survival and lung function in both animal and clinical studies. Soluble thrombomodulin has been shown to improve ALI in animals, and it is currently being evaluated in humans with sepsis. Finally, plasminogen activators may improve gas exchange in ALI, but studies in humans are limited.

Drotrecogin alfa (recombinant human activated protein C) for the treatment of severe sepsis

BACKGROUND

The search for a life-preserving drug to treat sepsis has increased understanding of the pathogenesis of the process but produced little in the way of successful treatments. The prospective, randomized, double-blind, placebo-controlled, Phase III, multicenter Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) trial suggested that drotrecogin alfa--recombinant human activated protein C--significantly improved 28-day mortality rates in acute sepsis (P = 0.005).

OBJECTIVES

The goals of this drug review were to summarize the recent findings regarding the pathogenesis of sepsis and septic shock, as well as the results of select immunomodulator drug trials, and to offer a comprehensive review of the mechanism of action, pharmacokinetic profile, efficacy and safety profile, and pharmacoeconomics of drotrecogin alfa.

METHODS

The English-language literature was searched using the EMBASE and MEDLINE databases. In EMBASE, the subject headings drotrecogin, activated protein C, and sepsis were used to search publications from 1980 through September 2002. In MEDLINE, the MeSH heading protein C and subject heading sepsis were used to search publications from 1966 through September 2002. Published abstracts of recent meetings and proceedings of the US Food and Drug Administration were also reviewed.

RESULTS

Drotrecogin alfa mimics the endogenous protein depleted during acute sepsis. Its activity as an antithrombotic, anti-inflammatory, and profibrinolytic agent appears to diminish the negative outcomes of acute sepsis, notably mortality at 28 days. The results of the PROWESS trial support this finding. A bleeding risk was noted during Phase II and III trials despite efforts to exclude those patients at high risk of bleeding.

CONCLUSIONS

Drotrecogin alfa is the first adjunctive agent for the treatment of sepsis to display clinically and statistically significant effects on mortality rates at 28 days. Many questions remain regarding which patients are ideal candidates for treatment. New research and treatment guidelines are necessary to address these questions.

Recombinant human activated protein C for the treatment of severe sepsis: is there a role in pediatrics?

Sepsis with organ failure (severe sepsis) remains an important cause of morbidity and mortality among children. The clinical pathophysiology of severe sepsis reflects a coordinated activation of the innate immune response, including elaboration of proinflammatory cytokines and the induction of the extrinsic pathway of coagulation (sepsis-induced coagulopathy). These proinflammatory and procoagulant pathways are linked, and are similarly coregulated by a number of proteins and factors, including protein C. However, at least 80% of children and adults with severe sepsis develop acquired deficiency of protein C because of factor consumption. This deficiency is associated with poor outcomes, including multiple organ failure and mortality. Recently, recombinant activated protein C was shown to reduce the mortality of adults with severe sepsis, and is now approved for such use in the United States and Europe. The rationale for pediatric applications of protein C and ongoing clinical trials in children are reviewed.

Protein C as diagnostic and predictive biomarker of sepsis during severe intra-abdominal infections

Severe intra-abdominal infections (IAI) with sepsis syndrome are still associated with high mortality rate (20-60%). This prospective study refers to diagnostic and prognostic importance of protein C detection during severe abdominal sepsis. We treated surgically 22 patients with severe IAI (mostly diffuse peritonitis with sepsis syndrome) vs. 15 patients with hernia repair (control group). During the study the next parameters were analyzed: Protein C, AT III, plasminogen, alpha-2 antiplasmin, HMWK, C5a, C5-B9 complements C1-inhibitor, CRP. All the evaluated parameters were different between the study and control groups, with high statistical significance (p < 0.001). The results and multivariate statistical analysis revealed the following parameters as very sensitive and important biological markers of abdominal sepsis: Protein C, AT III, HMWK, C5-B9, C1-inhibitor (p < 0.0001-0.026). The clinical difficulties of intra-abdominal sepsis are due to inherent problems of the limited clinical signs and the complexity of the distribution of infection. Inflammatory process is often well under way before the clinical signs and symptoms of sepsis are present. Early diagnosis of plasma proteolytic disturbances is, from the diagnostic and predictive point of view, very important in abdominal sepsis. According to multivariate statistical analysis protein C is the most significant diagnostic marker of sepsis during severe IAI (p < 0.0001).