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

Recombinant Activated Protein C (rhAPC) Affects Lipopolysaccharide-Induced Mechanical Compliance Changes and Beat Frequency of mESC-Derived Cardiomyocyte Monolayers

BACKGROUND

Septic cardiomyopathy increases mortality by 70% to 90% and results in mechanical dysfunction of cells.

METHODS

Here, we created a LPS-induced in-vitro sepsis model with mouse embryonic stem cell-derived cardiomyocytes (mESC-CM) using the CellDrum technology which simultaneously measures mechanical compliance and beat frequency of mESCs. Visualization of reactive oxygen species (ROS), actin stress fibers, and mRNA quantification of endothelial protein C receptor (EPCR) and protease-activated receptor 1 (PAR1) before/after LPS incubation were used for method validation. Since activated protein C (APC) has cardioprotective effects, samples were treated with human recombinant APC (rhAPC) with/-out LPS predamage to demonstrate the application in therapeutic studies.

RESULTS

Twelve hours LPS treatment (5 μg/mL) increased ROS and decreased actin stress fiber density and significantly downregulated EPCR and PAR1 compared to control samples (0.26, 0.39-fold respectively). rhAPC application (5 μg/mL, 12 h) decreased ROS and recovered actin density, EPCR, and PAR1 levels were significantly upregulated compared to LPS predamaged samples (4.79, 3.49-fold respectively). The beat frequencies were significantly decreased after 6- (86%) and 12 h (73%) of LPS application. Mechanical compliance of monolayers significantly increased in a time-dependent manner, up to eight times upon 12-h LPS incubation compared to controls. rhAPC incubation increased the beat frequency by 127% (6h-LPS) and 123% (12h-LPS) and decreased mechanical compliance by 68% (12h-LPS) compared to LPS predamaged samples.

CONCLUSION

LPS-induced contraction dysfunction and the reversal effects of rhAPC were successfully assessed by the mechanical properties of mESC-CMs. The CellDrum technology proved a decent tool to simulate sepsis in-vitro.

UM171 induces a homeostatic inflammatory-detoxification response supporting human HSC self-renewal

Elucidation of the molecular cues required to balance adult stem cell self-renewal and differentiation is critical for advancing cellular therapies. Herein, we report that the hematopoietic stem cell (HSC) self-renewal agonist UM171 triggers a balanced pro- and anti-inflammatory/detoxification network that relies on NFKB activation and protein C receptor-dependent ROS detoxification, respectively. We demonstrate that within this network, EPCR serves as a critical protective component as its deletion hypersensitizes primitive hematopoietic cells to pro-inflammatory signals and ROS accumulation resulting in compromised stem cell function. Conversely, abrogation of the pro-inflammatory activity of UM171 through treatment with dexamethasone, cAMP elevating agents or NFkB inhibitors abolishes EPCR upregulation and HSC expansion. Together, these results show that UM171 stimulates ex vivo HSC expansion by establishing a critical balance between key pro- and anti-inflammatory mediators of self-renewal.

The contact pathway and sepsis

The contact pathway factors XI (FXI) and XII (FXII) have been demonstrated to be largely dispensable for hemostasis, as their absence results in a mild to absent bleeding diathesis. A growing body of literature, however, suggests that the contact pathway contributes to the pathologic host response to certain infectious organisms that produces the often-fatal syndrome known as sepsis. The contact pathway factors serve as a central node connecting inflammation to coagulation, and may offer a potentially safe therapeutic target to mitigate the morbidity and mortality associated with sepsis. Herein, we summarize published in vivo and in vitro data that have explored the roles of the contact pathway in sepsis, and discuss potential clinical applications of novel FXI- and FXII-inhibiting drugs currently under investigation.

The effect of plasma-derived activated protein C on leukocyte cell-death and vascular endothelial damage

INTRODUCTION

The role of leukocyte and its death in the progression in inflammation attracts attention nowadays. The purpose of this study is to examine the effects of activated protein C (APC) on leucocyte cell death and vascular endothelial damage in sepsis.

METHODS

Wistar rats were infused with lipopolysaccharide (8.0mg/kg) concomitantly with either a low dose (0.5mg/kg), a high dose (5.0mg/kg) of plasma-derived APC or albumin. One and 3hours after the injections, the mesenteric microcirculation was observed by intravital microscopy. The serum levels of nucleosome and High Mobility Group Box 1 (HMGB1) were measured in each group. In another series, cultured leukocyte cell-death in the medium supplemented with serum obtained from each group was examined in vitro.

RESULTS

Microcirculatory disturbance was significantly suppressed in both the high-dose and low-dose groups compared to the control group (P<0.01, 0.05, respectively). The bleeding area was significantly increased in the control and high-dose groups (P<0.05, 0.01, respectively). Serum levels of cell death markers such as nucleosome and HMGB1 were significantly decreased in the treatment groups (P<0.01), and the protective effect was more pronounced in high-dose group. Cell death suppression was most prominent in high-dose group and the formation of neutrophil extracellular traps (NETs) was significantly suppressed in the treatment groups.

CONCLUSION

Low-dose plasma-derived APC exerted protective effects on the microcirculation without increasing the risk of bleeding. The protective effect against leukocyte cell death and the suppressive effect on NETs formation of APC might be related to its beneficial effects.

Safety and dose-finding study of activated protein C (drotrecogin alfa activated) as an anticoagulant in end-stage renal disease patients treated with hemodialysis

BACKGROUND/AIMS

End-stage renal disease (ESRD) patients treated with hemodialysis (HD) experience a high risk of death. ESRD patients with elevated levels of pro-inflammatory cytokines are at increased risk of death from cardiovascular events and infection. HD is often facilitated by the use of an anticoagulant. We hypothesized that the use of an anticoagulant that also possessed anti-inflammatory qualities without significant immunosuppressive effects may reduce the risk of death. In this pilot study, we sought to determine the optimal dose of activated protein C (APC) to achieve adequate regional anticoagulation for HD and determine if the drug can be safely used in ESRD patients treated with HD.

METHODS

Twelve stable HD patients were enrolled into this safety and dose-finding study. Varying doses of APC were administered in place of usual heparin at varying doses to determine the range of APC that can be used for extracorporeal circuit anticoagulation. Partial thromboplastin time was assessed at fixed intervals during the HD treatment.

RESULTS

The average age of study patients was 49 ± 12 years. 75% of patients were African-American and 66.7% were male. The optimal dose of APC to induce adequate anticoagulation was 24-30 μg/kg/h. No patients experienced any serious adverse events. One patient had their infusion stopped early due to refractory intradialytic hypertension.

CONCLUSIONS

For ESRD patients undergoing HD, an initial starting dose of 24-30 μg/kg/h achieves a target partial thromboplastin time that should be adequate for circuit anticoagulation. This dose appears safe and was well tolerated.

Contribution of procoagulant phospholipids, thrombomodulin activity and thrombin generation assays as prognostic factors in intensive care patients with septic and non-septic organ failure

BACKGROUND

Multiple organ dysfunction syndrome (MODS) observed in patients with sepsis and in nonseptic patients organ failure (OF) is associated with a high mortality rate. We investigated whether new coagulation assays [quantification of procoagulant phospholipids (PPL) activity, functional assays measuring the activity of thrombomodulin (TMa) or tissue factor (TFa) and thrombin generation using calibrated automated thrombography (CAT)] could constitute new tools to better understand the physiopathology of MODS and have any prognostic value.

METHODS

We measured TMa, TFa, PPL and CAT in 32 healthy controls, 24 patients with sepsis and 26 patients with non-septic OF. We compared these parameters with usual coagulation assays [prothrombin time, activated partial thromboplastin time, protein C (PC), protein S, D-Dimers (D-Di), soluble thrombomodulin (sTM)] and markers of inflammation (IL-6, CRP). Samples were collected within 24 h of the diagnosis.

RESULTS

TMa, TFa, PPL, the lag time and time to thrombin peak levels were increased in both groups of patients. For both groups D-Di, IL-6, CRP and endogenous thrombin potential (ETP) were higher in non-survivors than in survivors, while PC and PPL were lower in non-survivors than in survivors. TMa increase was more marked in non-survivors patients with OF, while the ratio TMa/sTM was low in non-survivors with sepsis. Received operating characteristic (ROC) curve analysis indicated that thrombin peak and ETP were the more powerful discriminating factors in patients with sepsis or non-septic OF, respectively.

CONCLUSIONS

PPL, TMa and CAT assays could represent promising tools to identify patients with increased risk of mortality in MODS and could procure insights into pathogenesis of MODS.

Efficacy of recombinant human soluble thrombomodulin for childhood hemolytic uremic syndrome

Recombinant human soluble thrombomodulin (rhTM) is a promising therapeutic natural anticoagulant and is used clinically for the treatment of disseminated intravascular coagulation (DIC). Herein is reported the cases of two HUS children treated with rhTM. The patients were diagnosed as having typical HUS on the basis of thrombocytopenia, hemolytic anemia, acute renal failure, and the detection Escherichia coli 0157. I.v. rhTM was started as an anti-coagulant drug. At 2 days after the first treatment in both patients, fibrin/fibrinogen degradation products and d-dimer levels were significantly decreased, and there was a subsequent slight improvement in thrombocytopenia, and a decrease in serum lactate dehydrogenase level. Urinary protein excretion gradually diminished and a decrease in serum creatinine level was observed. The patients did not require dialysis therapy. The present results suggest that rhTM may be a safe and effective treatment for DIC complicated with HUS in children.

Why activated protein C was not successful in severe sepsis and septic shock: are we still tilting at windmills?

Drotrecogin alpha activated (DAA), trade name Xigris, is a recombinant human protein C that has been the subject of controversy since 2001, when it became the first biologic agent approved for the treatment of severe sepsis and septic shock. The PROWESS trial showed a 6.1 % absolute reduction in 28-day mortality, although these findings were not replicated in later trials, ultimately leading to the withdrawal of DAA in 2011. Observational trials, however, have consistently shown a mortality benefit with the use of DAA, leading to the following questions: Did DAA truly fail and, if so, why? While these questions may never be definitively answered on the basis of available evidence, several factors may explain the conflicting results. In clinical practice, DAA may have been preferentially given to subjects more likely to survive. Contemporary treatments, including early antibiotic administration and volume resuscitation, may have mitigated the inflammatory processes leading to disordered coagulation and microvascular thrombosis and, thus, reduced or abolished the therapeutic opportunity for DAA. Later randomized clinical trials of DAA focused on the clinical phenotype of refractory shock, largely due to a strong efficacy signal in this subset from PROWESS; however, this clinical phenotype may not be tightly linked, at least after contemporary early resuscitation strategies, to the mechanistic phenotype of dysregulated coagulation that may have been a better target for DAA. Future trials of biologic therapies in severe sepsis and septic shock should use a combination of clinical phenotype and biomarkers to identify responsive populations that may benefit from such therapies.

Recombinant human activated protein C for adults with septic shock: a randomized controlled trial

RATIONALE

A decade after drotrecogin alfa (activated) (DAA) was released on the market worldwide, its benefit-to-risk ratio remains a matter of debate.

OBJECTIVES

The current investigator-led trial was designed to evaluate the efficacy and safety of DAA, in combination with low-dose steroids, in adults with persistent septic shock.

METHODS

This was a multicenter (24 intensive care units), placebo-controlled, double-blind, 2 × 2 factorial design trial in which adults with persistent septic shock and no contraindication to DAA were randomly assigned to DAA alone (24 μg/kg/h for 96 h), hydrocortisone and fludrocortisone alone, their respective combinations, or their respective placebos. Primary outcome was mortality rate on Day 90.

MEASUREMENTS AND MAIN RESULTS

On October 25, 2011, the trial was suspended after the withdrawal from the market of DAA. The Scientific Committee decided to continue the trial according to a two parallel group design comparing low-dose steroids with their placebos and to analyze the effects of DAA on patients included before trial suspension. At the time trial was suspended, 411 patients had been recruited, 208 had received DAA, and 203 had received its placebo. There was no significant interaction between DAA and low-dose steroids (P = 0.47). On Day 90, there were 99 deaths (47.6%) among the 208 patients receiving DAA and 94 deaths (46.3%) among the 203 patients receiving placebo (P = 0.79). There was no evidence of a difference between DAA and its placebo for any secondary outcomes or serious adverse events.

CONCLUSIONS

In adults with established and severe septic shock, DAA showed no evidence of benefit or harm. Clinical trial registered with www.clinicaltrials.gov (NCT00625209).

Evaluation of recombinant activated protein C for severe sepsis at a tertiary academic medical center

Purpose

Early clinical trials of recombinant human activated protein C (rhAPC) for severe sepsis excluded patients at high risk of bleeding. Recent literature suggests bleeding rates are higher in clinical practice and may be associated with worsened outcomes. Our objective was to evaluate baseline demographics; incidence, and risk factors for major bleeding; and mortality of patients receiving rhAPC for severe sepsis at our institution.

Methods

A retrospective study was performed for all patients receiving rhAPC for treatment of severe sepsis at a tertiary academic medical center from January 2002 to June 2009. Demographic information, clinical variables, intensive care unit, and hospital outcomes were recorded.

Results

Of the 156 patients that received rhAPC, 54 (34.6%) did not meet institutional criteria for safe use at baseline due to bleeding precaution or contraindication. Twenty-three (14.7%) patients experienced a major bleeding event. Multivariate analysis demonstrated baseline International Normalized Ratio ≥2.5 (odds ratio [OR] 3.68, 95% confidence interval [CI]: 1.28–10.56; P = 0.03) and platelet count ≤100 × 10³/mm³ (OR 2.86, 95% CI: 1.07–7.67; P = 0.01) as significant predictors of a major bleed. Overall hospital mortality was 57.7%. Multivariate analysis demonstrated the presence of ≥3 organ dysfunctions (OR 2.46, 95% CI: 1.19–5.09; P < 0.05) and medical intensive care unit admission (OR 1.99, 95% CI: 1.00–3.98; P = 0.05) were independent variables associated with hospital mortality.

Conclusion

Patients receiving rhAPC at our institution had higher APACHE II scores, mortality, and major bleeding events than published postmarketing studies. Risk factors for major bleeding other than package-labeling contraindications and bleeding precautions were identified in our patient population.

Enhancing autophagy with activated protein C and rapamycin protects against sepsis-induced acute lung injury

BACKGROUND

Autophagy plays distinct roles in apoptosis and the inflammatory process. Understanding the role of autophagy in sepsis-induced acute lung injury (ALI) may provide new insights into developing novel therapeutic strategies for this group of patients. The aim of this study was to investigate the regulation of autophagy in the septic lung and to use pharmacologic agents to modulate autophagy to study its functional significance.

METHODS

Mice were subjected to cecal ligation and puncture (CLP) or a sham operation. At 1 hour after CLP, mice were treated with vehicle, activated protein C (APC), rapamycin, or bafilomycin A1. Mice were humanely killed at 4 or 24 hours after the operation or were observed for ≤ 7 days.

RESULTS

CLP induced a systemic inflammatory response and significantly decreased survival. In lung tissue, increased leukocyte infiltration, inflammation, and apoptosis were observed. In contrast, autophagy was suppressed after CLP such that the expression of LC3II, Atg5, and Rab7 were downregulated. Rapamycin activated autophagy, limited the CLP-induced proinflammatory response, and downregulated apoptotic activity after CLP. The administration of APC after CLP had an effect similar to that of rapamycin. Both medications significantly improved survival 7 days after CLP.

CONCLUSION

The downregulation of autophagy may lead to systemic inflammation and ALI after sepsis. The direct or indirect modification of autophagy using rapamycin or APC, respectively, resulted in improved survival. Enhancing or restoring autophagy early after sepsis seems to be a potential strategy for the treatment of sepsis-induced ALI.

Endogenous protein C has a protective role during Gram-negative pneumosepsis (melioidosis)

BACKGROUND

Activated protein C (APC) exerts anticoagulant effects via inactivation of factors Va and VIIIa and cytoprotective effects via protease activated receptor (PAR)1. Inhibition of endogenous APC in endotoxemia and sepsis results in exacerbation of coagulation and inflammation, with consequent enhanced lethality.

OBJECTIVES

We here sought to dissect the distinct roles of the anticoagulant and cytoprotective functions of endogenous APC in severe Gram-negative pneumonia-derived sepsis (melioidosis).

METHODS

We infected wild-type (WT) mice with Burkholderia pseudomallei, a common sepsis pathogen in southeast Asia, and treated them with antibodies inhibiting both the anticoagulant and cytoprotective functions of APC (MPC1609) or the anticoagulant functions of APC (MAPC1591) only. Additionally, we administered SEW2871 (stimulating the S1P1-pathway downstream from PAR1) to control and MPC1609-treated mice.

RESULTS

MPC1609, but not MAPC1591, significantly worsened survival, increased coagulation activation, facilitated bacterial growth and dissemination and enhanced the inflammatory response. The effects of MPC1609 could not be reversed by SEW2871, suggesting that S1P1 does not play a major role in this model.

CONCLUSIONS

These results suggest that the mere inhibition of the anticoagulant function of APC does not interfere with its protective role during Gram-negative pneumosepsis, suggesting a more prominent role for cytoprotective effects of APC .

Preclinical sepsis models

BACKGROUND

A variety of sepsis models have been used to unravel pathophysiologic processes and to examine the effects of novel therapeutic interventions. The lack of therapeutic efficacy of numerous compounds in clinical sepsis trials, despite glorious results in animal models of sepsis, has raised doubt and debate about the usefulness of such models.

METHODS

Review of the pertinent literature.

RESULTS

Many sepsis models have been described, none of which is ideal. Clinical sepsis can originate from different sources, can be accompanied by many complicating conditions, and strikes human beings with strongly variable genetic backgrounds, co-morbidities, and drug usages. To provide answers to the three main objectives of research-insight into the regulation of normal host defense mechanisms in the early stages of infection; the mechanisms underlying dysregulation of the host response; and proof of principle for the mechanism of action of novel therapeutic agents and to establish their efficacy and potential harm-diverse models are required. The future of sepsis research lies in the systematic combination of models, together with in vitro studies and carefully designed and monitored Phase I/II clinical studies.

CONCLUSION

This review discusses the nature of various animal sepsis models and the way their results should be interpreted.

Live liver donors: Are they at a higher risk for post-operative thrombotic complications?

Live liver donor transplantation to adult recipients is becoming a common practice, increasing the organ pool and providing an alternative to whole cadaveric liver transplantation. These patients are healthy adults without serious medical conditions and typically have normal coagulation profiles preoperatively. Right hepatic lobectomy is usually performed for adult recipients, while left hepatic lobectomy is performed for pediatric recipients. Removal of the whole right lobe from the donors may expose theses patients to multiple intraoperative and postoperative complications. Hypercoagulability has been identified as a serious complication which leads to thromboembolic phenomena with potential fatal consequences. The primary aim of this review is to look at possible changes in post-operative coagulation dynamics that may increase the risk for development of thromboembolic complications in live liver donors. In this article, we stress the importance of addressing the issue that conventional clotting tests (PT, INR, PTT) are unable to detect a hypercoagulable state, and therefore, we should examining alternative laboratory tests to improve diagnosis and early detection of thrombotic complications. Measurement of natural anticoagulant/procoagulant biomarkers combined with conventional coagulation studies and thromboelastography offers a more accurate assessment of coagulation disorders. This allows earlier diagnosis, permitting appropriate intervention sooner, hence avoiding potential morbidity and mortality. Biomarkers that may be evaluated include, but are not limited to: protein C, soluble P-selectin, antithrombin III, thrombin-antithrombin complex, and thrombin generation complex.

Mediators of systemic inflammatory response syndrome and the role of recombinant activated protein C in sepsis syndrome

The systemic inflammatory response syndrome, the host's response to infection involves a series of cascading events that mobilize a series of mediators involving the immune system, complement, and the coagulation cascade. Although the initial focus of mediators is to limit infection, this cascade may run amok and cause the development of hypotension, vascular instability, and disseminated intravascular coagulation, leading to morbidity and mortality in the host. Several therapeutic trials have focused on the modulation of these mediators, but use of recombinant human activated protein C in patients with severe sepsis is the only one that has shown a benefit in clinical trials.

Activated protein C attenuates systemic lupus erythematosus and lupus nephritis in MRL-Fas(lpr) mice

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease leading to inflammatory tissue damage in multiple organs (e.g., lupus nephritis). Current treatments including steroids, antimalarials, and immunosuppressive drugs have significant side effects. Activated protein C is a natural protein with anticoagulant and immunomodulatory effects, and its recombinant version has been approved by the U.S. Food and Drug Administration to treat severe sepsis. Given the similarities between overshooting immune activation in sepsis and autoimmunity, we hypothesized that recombinant activated protein C would also suppress SLE and lupus nephritis. To test this concept, autoimmune female MRL-Fas(lpr) mice were injected with either vehicle or recombinant human activated protein C from week 14-18 of age. Activated protein C treatment significantly suppressed lupus nephritis as evidenced by decrease in activity index, glomerular IgG and complement C3 deposits, macrophage counts, as well as intrarenal IL-12 expression. Further, activated protein C attenuated cutaneous lupus and lung disease as compared with vehicle-treated MRL-Fas(lpr) mice. In addition, parameters of systemic autoimmunity, such as plasma cytokine levels of IL-12p40, IL-6, and CCL2/MCP-1, and numbers of B cells and plasma cells in spleen were suppressed by activated protein C. The latter was associated with lower total plasma IgM and IgG levels as well as lower titers of anti-dsDNA IgG and rheumatoid factor. Together, recombinant activated protein C suppresses the abnormal systemic immune activation in SLE of MRL-Fas(lpr) mice, which prevents subsequent kidney, lung, and skin disease. These results implicate that recombinant activated protein C might be useful for the treatment of human SLE.

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.

The resuscitation package in sepsis

Sepsis and its attendant complications are commonly encountered in the intensive care unit. Early recognition of sepsis is critical because it allows for rapid deployment of a multifaceted resuscitation package. The cornerstones of sepsis management are antibiotic therapy, source control, and hemodynamic resuscitation. In select patients, ancillary therapies are indicated, such as activated protein C, corticosteroids, and glycemic control. Given the complexity of sepsis management, optimal care can be delivered as a bundle-a protocol encompassing the above interventions. The evidence behind the various components of sepsis management are reviewed here.

Treatment effects of recombinant human soluble thrombomodulin in patients with severe sepsis: a historical control study

Introduction

Cross-talk between the coagulation system and inflammatory reactions during sepsis causes organ damage followed by multiple organ dysfunction syndrome or even death. Therefore, anticoagulant therapies have been expected to be beneficial in the treatment of severe sepsis. Recombinant human soluble thrombomodulin (rhTM) binds to thrombin to inactivate coagulation, and the thrombin-rhTM complex activates protein C to produce activated protein C. The purpose of this study was to examine the efficacy of rhTM for treating patients with sepsis-induced disseminated intravascular coagulation (DIC).

Methods

This study comprised 65 patients with sepsis-induced DIC who required ventilatory management. All patients fulfilled the criteria of severe sepsis and the International Society on Thrombosis and Haemostasis criteria for overt DIC. The initial 45 patients were treated without rhTM (control group), and the following 20 consecutive patients were treated with rhTM (0.06 mg/kg/day) for six days (rhTM group). The primary outcome measure was 28-day mortality. Stepwise multivariate Cox regression analysis was used to assess which independent variables were associated with mortality. Comparisons of Sequential Organ Failure Assessment (SOFA) score on sequential days between the two groups were analyzed by repeated measures analysis of variance.

Results

Cox regression analysis showed 28-day mortality to be significantly lower in the rhTM group than in the control group (adjusted hazard ratio, 0.303; 95% confidence interval, 0.106 to 0.871; P = 0.027). SOFA score in the rhTM group decreased significantly in comparison with that in the control group (P = 0.028). In the post hoc test, SOFA score decreased rapidly in the rhTM group compared with that in the control group on day 1 (P < 0.05).

Conclusions

We found that rhTM administration may improve organ dysfunction in patients with sepsis-induced DIC. Further clinical investigations are necessary to evaluate the effect of rhTM on the pathophysiology of sepsis-induced DIC.

Elevated plasma matrix metalloproteinases and their tissue inhibitors in patients with severe sepsis

PURPOSE

Matrix metalloproteinases (MMPs) are essential for tissue remodeling. Our objectives were to determine (1) the concentrations of MMPs and their tissue inhibitors (TIMPs) in plasma obtained from patients with severe sepsis, (2) to correlate changes in MMP and TIMP levels with disease severity, and (3) to investigate recombinant activated protein C (rAPC) actions on plasma MMP2, 9 activities from severe sepsis patients.

MATERIALS AND METHODS

Matrix metalloproteinase and TIMP levels were quantified in plasma from patients with severe sepsis using antibody microarrays and gelatin zymography.

RESULTS

Plasma MMPs (3, 7, 8, 9) and TIMPs (1, 2, 4) on microarray were increased in severe sepsis on intensive care unit (ICU) day 1, with more than 3-fold increases in MMP3, MMP7, MMP8, MMP9, and TIMP4. Latent forms of MMP2, 9 on zymography were increased in plasma from patients with severe sepsis, whereas only half of severe sepsis patients showed active MMP9. Elevated MMP7 and MMP9 on ICU days 1 and 3 negatively correlated with multiple organ dysfunctions. The temporal activity patterns of MMP2, 9 during 21 ICU days were not altered in patients treated with rAPC or by the addition of exogenous rAPC to plasma.

CONCLUSION

Most plasma MMPs and TIMPS were elevated in patients with severe sepsis, but only a limited subset of MMPs (7, 9) negatively correlated with disease severity. Recombinant activated protein C does not appear to directly alter MMP2, 9 activities.

Use of recombinant human activated protein C in nonmenstrual staphylococcal toxic shock syndrome

Toxic shock syndrome (TSS) is a serious, potentially life-threatening condition resulting from an overwhelming immunological response to an exotoxin released by Staphylococcus aureus and group A streptococci. High index of suspicion, early diagnosis and aggressive therapeutic measures must be instituted in view of high mortality of the TSS. In recent years, new agents have been tested to reduce morbidity and mortality in patients with severe sepsis, in addition to standard supportive measures. Among them, recombinant human activated protein C (rhAPC) has been reported to significantly reduce mortality and morbidity in patients with severe sepsis and two or more acute organ failures. We describe our experience with this drug in the early reversal of septic shock from TSS.

Sepsis in burns: a review of current practice and future therapies

Sepsis is a major cause of death worldwide and remains the subject of much research and debate within the critical care community. Despite advances in burn prevention, treatment, and rehabilitation, sepsis remains a common cause of death in patients who have sustained a severe burn injury. The unique physical, metabolic, and physiologic changes seen after major thermal injury mean that the management of sepsis in burns poses a particular challenge and differs in many respects to the management of sepsis in the general critical care population. This article describes current issues in the prevention, diagnosis, and treatment of sepsis in burns with a review of the associated literature. In addition, we discuss possible future therapies for managing this condition.

Liposomal Formulations of Thrombomodulin Increase Engraftment after Intraportal Islet Transplantation

Early destruction of donor islet grafts due to an instant blood-mediated inflammatory reaction (IBMIR) remains a major obstacle in islet transplantation. Thrombomodulin plays an important role in limiting coagulation and inflammatory events through a variety of effects. In this study, we investigated the ability of thrombomodulin (TM), when reconstituted as a liposomal formulation, to enhance early syngeneic islet engraftment by minimizing or abrogating the IBMIR. Administration of TM significantly improved early engraftment of syngeneic islets after intraportal transplantation in diabetic mice. In the absence of treatment, conversion to euglycemia was observed among 46.6% (7/15) of recipients. In contrast, administration of TM led to euglycemia in 93.3% (14/15) of recipients ( p = 0.0142). Recipients that received TM exhibited a lower incidence of primary nonfunction and better glucose control over a 30-day period after transplantation. Fibrin deposition ( p < 0.05), neutrophil infiltration ( p < 0.05), expression of TNF-α and IL-β mRNA ( p < 0.05), as well as NF-κB activity ( p < 0.05) were significantly reduced in the liver of islet recipients having been treated with liposomal TM. These data demonstrate that TM significantly improves early syngeneic islet engraftment through effects that target both coagulation and inflammatory pathways.

Obesity hypoventilation syndrome: mechanisms and management

Obesity hypoventilation syndrome describes the association between obesity and the development of chronic daytime alveolar hypoventilation. This syndrome arises from a complex interaction between sleep-disordered breathing, diminished respiratory drive, and obesity-related respiratory impairment, and is associated with significant morbidity and mortality. Therapy directed toward reversing these abnormalities leads to improved daytime breathing, with available treatment options including positive pressure therapy, weight loss, and pharmacological management. However, a lack of large-scale, well-designed studies evaluating these various therapies has limited the development of evidence-based treatment recommendations. Although treatment directed toward improving sleep-disordered breathing is usually effective, not all patients tolerate mask ventilation and awake hypercapnia may persist despite effective use. In the longer term, weight loss is desirable, but data on the success and sustainability of this approach in obesity hypoventilation are lacking. The review outlines the major mechanisms believed to underlie the development of hypoventilation in this subgroup of obese patients, their clinical presentation, and current therapy options.

Use of recombinant human activated protein C in nonmenstrual staphylococcal toxic shock syndrome

Toxic shock syndrome (TSS) is a serious, potentially life-threatening condition resulting from an overwhelming immunological response to an exotoxin released by Staphylococcus aureus and group A streptococci. High index of suspicion, early diagnosis and aggressive therapeutic measures must be instituted in view of high mortality of the TSS. In recent years, new agents have been tested to reduce morbidity and mortality in patients with severe sepsis, in addition to standard supportive measures. Among them, recombinant human activated protein C (rhAPC) has been reported to significantly reduce mortality and morbidity in patients with severe sepsis and two or more acute organ failures. We describe our experience with this drug in the early reversal of septic shock from TSS.

Drotrecogin alfa (activated) may attenuate severe sepsis-associated encephalopathy in clinical septic shock

Introduction

Sepsis-associated encephalopathy (SAE) is a diffuse cerebral dysfunction induced by the immuno-inflammatory response to infection. Elevated levels of the brain-specific S100B protein are present in many septic patients and reflect the severity of SAE. Adjunctive treatment with drotrecogin alfa (activated) (DrotAA), the human recombinant form of activated protein C, has been shown to improve mortality in patients with severe sepsis-induced organ failure. We studied the effect of DrotAA on S100B levels in patients with acute septic shock who presented with increased baseline values of this biomarker.

Methods

All patients received standard goal-directed resuscitation treatment. Patients with pre-existing or acute neurological disorders were excluded. Based on the Glasgow coma scale (GCS), patients were classified into two groups: GCS ≥ 13 and GCS <13. DrotAA was given as a continuous infusion of 24 μg/kg/h for 96 h. S100B was measured before sedation and the start of DrotAA (0 h) and at 32 h, 64 h and 96 h and at corresponding time points in patients not treated with DrotAA. The lower limit of normal was < 0.5 μg/L.

Results

Fifty-four patients completed the study. S100B was increased in 29 (54%) patients. Twenty-four patients (9 with GCS ≥ 13 and 15 with GCS <13) received DrotAA. S100B levels in DrotAA-treated patients with a GCS <13, though higher at baseline than in untreated subjects (1.21 ± 0.22 μg/L vs. 0.95 ± 0.12 μg/L; P = 0.07), progressively and significantly decreased during infusion (0.96 ± 0.22 μg/L at 32 h, P = 0.3; 0.73 ± 0.12 μg/L at 64 h, P < 0.05; and 0.70 ± 0.13 μg/L at 96 h, P < 0.05 vs. baseline). This patient group had also significantly lower S100B values at 64 h and at 96 h than their untreated counterparts. In the patients with a GCS ≥ 13, S100B levels were not influenced by DrotAA treatment.

Conclusions

S100B-positivity is present in more than half of the patients with septic shock. When increased S100B levels are used as a surrogate for SAE, adjunctive DrotAA treatment seems to beneficially affect the evolution of severe SAE as discriminated by an admission GCS <13.

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.

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.

Nonimmune cells in inflammatory bowel disease: from victim to villain

Nonimmune cells have traditionally been viewed as target cells of the aberrant inflammatory process present in chronic immune-mediated conditions such as inflammatory bowel disease (IBD). However, the discovery that many of the functions traditionally attributed to immune cells are also performed by nonimmune cells has caused a shift to a multidirectional hypothesis in which nonimmune cells and acellular elements play active roles. Many types of interactions occur within this multidirectional system, and the difficulties associated with modeling these complex interactions currently limit our understanding of the cellular network that occurs in IBD. I describe the current knowledge of the roles played by nonimmune cells in the pathogenesis of IBD, as they emerge as crucial alternative targets for therapeutic intervention.

Early drotrecogin alpha (activated) administration in severe sepsis is associated with lower mortality: a retrospective analysis of the Canadian ENHANCE cohort

INTRODUCTION

Early multimodal treatment of severe sepsis, including the use of drotrecogin alfa (activated) (DrotAA) when indicated, is considered essential for optimum outcome. However, predicting which infected patients will progress to severe sepsis and the need for aggressive intervention continues to be problematic. We therefore wished to explore whether there were any potential early markers that might predict improved survival in response to early use of DrotAA in patients with severe sepsis. In particular, in the dynamic setting of severe sepsis, we postulated that changes in markers reflecting evolving rather than baseline clinical status might guide therapy.

METHODS

Data on a cohort of 305 Canadian patients from the open label ENHANCE trial of DrotAA in severe sepsis was retrospectively analyzed to search for potential clinical predictors of outcome in severe sepsis. Patients received a 96-hour infusion of DrotAA and were followed for 28 days. The association between time to treatment and mortality within subgroups defined by dynamic changes in various potential markers was explored.

RESULTS

Mortality at 28 days was 22.6% and the variables of age, time to treatment, and early changes in serum creatinine and platelet count were identified by logistic regression as independent predictors of mortality. Across all age ranges, 28-day mortality was lower when DrotAA was administered within 24 hours of first sepsis-induced organ dysfunction compared to administration after 24 hours for both subgroups of patients defined by changes in platelet count and creatinine within the first day.

CONCLUSIONS

These findings suggest that when indicated, treatment with DrotAA should be initiated as soon as possible, regardless of age.

TRIAL REGISTRATION

Previous trial registration number: NCT00568893.

Recombinant human activated protein C in acute lung injury: what is the role of bronchial circulation?

Impairment of the protein C pathway plays a central role in the pathogenesis of sepsis. Treatment with recombinant human activated protein C (rhAPC) has been reported to increase survival from severe sepsis. Protein C levels also decrease markedly in acute lung injury, of both septic and nonseptic origin. Low levels of protein C in acute lung injury are associated with poor clinical outcome. The present article discusses the beneficial effects of rhAPC in oleic acid-induced lung injury as well as the controversies between different animal models and the timing of drug administration. The unique bronchial circulation in ovine models seems to be responsible for the beneficial effects of rhAPC when given simultaneously to the injury.