Protective mechanisms of activated protein C in severe inflammatory disorders

Protein C Pretreatment Protects Endothelial Cells from SARS-CoV-2-Induced Activation

SARS-CoV-2 can induce vascular dysfunction and thrombotic events in patients with severe COVID-19; however, the cellular and molecular mechanisms behind these effects remain largely unknown. In this study, we used a combination of experimental and in silico approaches to investigate the role of PC in vascular and thrombotic events in COVID-19. Single-cell RNA-sequencing data from patients with COVID-19 and healthy subjects were obtained from the publicly available Gene Expression Omnibus (GEO) repository. In addition, HUVECs were treated with inactive protein C before exposure to SARS-CoV-2 infection or a severe COVID-19 serum. An RT-qPCR array containing 84 related genes was used, and the candidate genes obtained were evaluated. Activated protein C levels were measured using an ELISA kit. We identified at the single-cell level the expression of several pro-inflammatory and pro-coagulation genes in endothelial cells from the patients with COVID-19. Furthermore, we demonstrated that exposure to SARS-CoV-2 promoted transcriptional changes in HUVECs that were partly reversed by the activated protein C pretreatment. We also observed that the serum of severe COVID-19 had a significant amount of activated protein C that could protect endothelial cells from serum-induced activation. In conclusion, activated protein C protects endothelial cells from pro-inflammatory and pro-coagulant effects during exposure to the SARS-CoV-2 virus.

Proteomics data in vitiligo: a scoping review

An unbiased screening of which proteins are deregulated in vitiligo using proteomics can offer an enormous value. It could not only reveal robust biomarkers for detecting disease activity but can also identify which patients are most likely to respond to treatments. We performed a scoping review searching for all articles using proteomics in vitiligo. Eight manuscripts could be identified. Unfortunately, very limited overlap was found in the differentially expressed proteins between studies (15 out of 272; 5,51%) with variable degrees of the type of proteins and a substantial variety in the prevalence of acute phase proteins (range: 6-65%). Proteomics research has therefore brought little corroborating evidence on which proteins are differentially regulated between vitiligo patients and healthy controls or between active and stable vitiligo patients. While a limited patient size is an obvious weakness for several studies, an incomplete description of patient characteristics is an unfortunate and avoidable shortcoming. Additionally, the variations in the used methodology and analyses may further contribute to the overall observed variability. Nonetheless, more recent studies investigating the response to treatment seem to be more robust, as more differentially expressed proteins that have previously been confirmed to be involved in vitiligo were found. The further inclusion of proteomics analyses in clinical trials is recommended to increase insights into the pathogenic mechanisms in vitiligo and identify reliable biomarkers or promising drug targets. A harmonization in the study design, reporting and proteomics methodology could vastly improve the value of vitiligo proteomics research.

Unraveling the Molecular Mechanisms of Activated Protein C (APC) in Mitigating Reperfusion Injury and Cardiac Ischemia: a Promising Avenue for Novel Therapeutic Interventions

Ischemic heart disease, which results from plaque formation in the coronary arteries, hinders the flow of oxygenated blood to the heart, leading to ischemia. Reperfusion injury remains a significant challenge for researchers, and the mechanisms underlying myocardial ischemia-reperfusion injury (MIRI) are not entirely understood. The review directs future research into potential targets in clinical treatment based on our present understanding of the pathophysiological mechanisms of MIRI. The study provides insights into the mechanisms underlying MIRI and offers direction for future research in this area. The use of targeted therapies may hold promise in improving cardiac function in the elderly and minimizing the adverse effects of revascularization therapies. The purpose of this review is to analyze the role of activated protein C (APC) in the pathogenesis of ischemic heart disease, heart failure, and myocardial ischemia-reperfusion injury, and discuss the potential of APC-based therapeutics.

Multi-Omic Admission-Based Prognostic Biomarkers Identified by Machine Learning Algorithms Predict Patient Recovery and 30-Day Survival in Trauma Patients

Admission-based circulating biomarkers for the prediction of outcomes in trauma patients could be useful for clinical decision support. It is unknown which molecular classes of biomolecules can contribute biomarkers to predictive modeling. Here, we analyzed a large multi-omic database of over 8500 markers (proteomics, metabolomics, and lipidomics) to identify prognostic biomarkers in the circulating compartment for adverse outcomes, including mortality and slow recovery, in severely injured trauma patients. Admission plasma samples from patients (n = 129) enrolled in the Prehospital Air Medical Plasma (PAMPer) trial were analyzed using mass spectrometry (metabolomics and lipidomics) and aptamer-based (proteomics) assays. Biomarkers were selected via Least Absolute Shrinkage and Selection Operator (LASSO) regression modeling and machine learning analysis. A combination of five proteins from the proteomic layer was best at discriminating resolvers from non-resolvers from critical illness with an Area Under the Receiver Operating Characteristic curve (AUC) of 0.74, while 26 multi-omic features predicted 30-day survival with an AUC of 0.77. Patients with traumatic brain injury as part of their injury complex had a unique subset of features that predicted 30-day survival. Our findings indicate that multi-omic analyses can identify novel admission-based prognostic biomarkers for outcomes in trauma patients. Unique biomarker discovery also has the potential to provide biologic insights.

Endothelial Dysfunction after Hematopoietic Stem Cell Transplantation: A Review Based on Physiopathology

Endothelial dysfunction (ED) is frequently encountered in transplant medicine. ED is an argument of high complexity, and its understanding requires a wide spectrum of knowledge based on many fields of basic sciences such as molecular biology, immunology, and pathology. After hematopoietic stem cell transplantation (HSCT), ED participates in the pathogenesis of various complications such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), graft-versus-host disease (GVHD), transplant-associated thrombotic microangiopathy (TA-TMA), idiopathic pneumonia syndrome (IPS), capillary leak syndrome (CLS), and engraftment syndrome (ES). In the first part of the present manuscript, we briefly review some biological aspects of factors involved in ED: adhesion molecules, cytokines, Toll-like receptors, complement, angiopoietin-1, angiopoietin-2, thrombomodulin, high-mobility group B-1 protein, nitric oxide, glycocalyx, coagulation cascade. In the second part, we review the abnormalities of these factors found in the ED complications associated with HSCT. In the third part, a review of agents used in the treatment of ED after HSCT is presented.

Relationship between serum soluble endothelial protein C receptor level and COVID-19 findings

Coronavirus-related disease-2019 (COVID-19)-associated coagulopathy presents predominantly with thrombosis and leads to complications in close association with inflammatory process. Soluble endothelial protein C receptor (sEPCR), which is the soluble form of EPCR, reduces the anticoagulant and anti-inflammatory activity of activated protein C. The purpose of this study is to investigate the relationship between sEPCR and the laboratory parameters and thorax computed tomography (CT) findings in the course of COVID-19. Twenty-five laboratory-confirmed [reverse transcription-quantitative polimerase chain reaction (RT-qPCR) positive] and 24 clinically diagnosed (RT-qPCR negative) COVID-19 patients were enrolled in the study. Blood specimens were collected for sEPCR and haematological and biochemical parameter measurement. Thorax CT was performed to detect COVID-19 findings. These parameters from RT-qPCR positive and negative patients were then compared. Although there was no difference between the groups in terms of symptoms, the time between the onset of symptoms and the admission time was shorter in RT-qPCR positive group (P = 0.000). sEPCR levels were significantly higher in the RT-qPCR positive group (P = 0.011). Patients with ground-glass opacity and bilateral involvement on thorax CT have higher serum sEPCR levels (P = 0.012 and 0.043, respectively). This study has shown for the first time that serum sEPCR levels, which is a member of coagulation cascade and has also been reported to be associated with inflammation, is higher in patients with positive RT-qPCR test and patients with GGO or bilateral involvement on thorax CT regardless of the PCR result.

The extract from Agkistrodon halys venom protects against lipopolysaccharide (LPS)-induced myocardial injury

BACKGROUND

Snake venoms contain various bioactive constituents which possess potential therapeutic effects. The aim of this work was to investigate the effect of the extract from Agkistrodon halys venom on lipopolysaccharide (LPS)-induced myocardial injury.

METHODS

Thirty male Sprague-Dawley rats were randomly assigned to three groups (10 rats per group): control group, LPS group and LPS + extract group. Rats in control and the LPS groups were intravenously injected with sterile saline solution, and rats in the LPS + extract group with the extract. After 2 h, rats of the control group were intraperitoneally injected sterile saline solution, and rats in the LPS and the LPS + extract groups were treated with LPS (20 mg per kg body weight). Levels of creatine kinase (CK) and lactate dehydrogenase (LDH) in serum were determined. Anti-inflammation of the extract was analyzed via determination of TNF-α and IL-6 in serum, and expression of TNF-α, IL-6, COX-2 and p-ERK protein in hearts. Heme oxygenase-1 (HO-1) and p-NF-κB protein expression in hearts, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in serum were used to evaluate the anti-oxidative properties of the extract.

RESULTS

Extract pretreatment significantly decreased the level of serum CK and LDH, reduced the generation of inflammatory cytokines such as TNF-α and IL-6, and also reduced serum level of MDA in the LPS + extract group compared with the LPS group. In addition, the extract increased SOD activity in serum, HO-1 protein expression in hearts, and decreased TNF-α, IL-6, COX-2, p-NF-κB and p-ERK1/2 protein expression.

CONCLUSION

Our results suggested that beneficial effect of this extract might be associated with an improved anti-oxidation and anti-inflammatory effect via downregulation of NF-κB/COX-2 signaling by activating HO-1/CO in hearts.

Endothelial Protein C Receptor (EPCR), Protease Activated Receptor-1 (PAR-1) and Their Interplay in Cancer Growth and Metastatic Dissemination

Endothelial protein C receptor (EPCR) and protease activated receptor 1 (PAR-1) by themselves play important role in cancer growth and dissemination. Moreover, interactions between the two receptors are essential for tumor progression. EPCR is a cell surface transmembrane glycoprotein localized predominantly on endothelial cells (ECs). It is a vital component of the activated protein C (APC)—mediated anticoagulant and cytoprotective signaling cascade. PAR-1, which belongs to a family of G protein–coupled cell surface receptors, is also widely distributed on endothelial and blood cells, where it plays a critical role in hemostasis. Both EPCR and PAR-1, generally considered coagulation-related receptors, are implicated in carcinogenesis and dissemination of diverse tumor types, and their expression correlates with clinical outcome of cancer patients. Existing data explain some mechanisms by which EPCR/PAR-1 affects cancer growth and metastasis; however, the exact molecular basis of cancer invasion associated with the signaling is still obscure. Here, we discuss the role of EPCR and PAR-1 reciprocal interactions in cancer progression as well as potential therapeutic options targeted specifically to interact with EPCR/PAR-1-induced signaling in cancer patients.

Dysregulation of pulmonary endothelial protein C receptor and thrombomodulin in severe falciparum malaria-associated ARDS relevant to hemozoin

To investigate the role of the protein C system, endothelial protein C receptor (EPCR) and thrombomodulin (TM) in the pathogenesis of malaria-associated acute respiratory distress syndrome (ARDS) in relation to hemozoin and proinflammatory cytokines-induced type II pneumocyte injury and -aggravated pulmonary resolution. A total of 29 left-over lung specimens that were obtained from patients who died from severe falciparum malaria were examined. Histopathological, immunohistochemical and electron microscopic analyses revealed that ARDS coexisted with pulmonary edema and systemic bleeding; the severity was dependent on the level of hemozoin deposition in the lung and internal alveolar hemorrhaging. The loss of EPCR and TM was primarily identified in ARDS patients and was related to the level of hemozoin, parasitized red blood cell (PRBC) and white blood cell accumulation in the lung. Moreover, an in vitro analysis demonstrated that interleukin-13 and -31 and hemozoin induced pneumocytic cell injury and apoptosis, as assessed by EB/AO staining, electron microscopy and the up-regulation of CARD-9 mRNA (caspase recruitment domain-9 messenger-ribonucleic acid). The dysregulation of EPCR and TM in the lung, especially in those with increased levels of hemozoin, may play an important role in the pathogenesis of malaria-associated ARDS through an apoptotic pathway.

Blood Coagulation and Asthma Exacerbation in Children

BACKGROUND

Recent studies have demonstrated the activation of coagulation pathways in asthmatic airways. This study aimed to determine systemic blood coagulation during asthma exacerbation compared with the stable state in children.

METHODS

Pediatric patients (aged between 5 and 15 years) suffering from asthma exacerbation were enrolled. von Willebrand factor (vWF), plasminogen activator inhibitor type-1 (PAI-1), protein C, D-dimer, prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin complex (TAT), and C-reactive protein (CRP) levels were measured during asthma exacerbation and stable state.

RESULTS

A total of 22 patients were enrolled. The median vWF, PAI-1, and CRP during asthma exacerbation were significantly higher than those of the stable state: 147.5% (interquartile range, IQR: 111.05-196.57) versus 94% (IQR: 69.72-109.62, p < 0.001), 41.9 ng/ml (IQR: 21.91-48.61) versus 26.17 ng/ml (IQR: 15.89-34.44, p < 0.03), and 4.46 mg/l (IQR: 2.15-16.23) versus 0.87 mg/l (IQR: 0.20-3.89, p < 0.015), respectively. However, the median protein C during asthma exacerbation was significantly lower than that of the stable state: 99.5% (IQR: 86.75-117) versus 113% (IQR: 94-115.25), p = 0.01. No significant difference was found between the levels of D-dimer, F1 + 2, and TAT during asthma exacerbation and stable state. Ultimately, D-dimer was positively correlated with asthma exacerbation score (R = 0.466, p = 0.027). A significant correlation was observed between vWF and CRP (R = 0.527, p = 0.012).

CONCLUSION

Evidence was found of increased endothelial activation and increased PAI-1 during asthma exacerbation. This may emphasize the potential role of blood coagulation in asthma exacerbation.

Bilateral iliac and popliteal arterial thrombosis in a child with focal segmental glomerulosclerosis

Thromboembolic complications (TECs) are clinically important sequelae of nephrotic syndrome (NS). The incidence of TECs in children is approximately 2%–5%. The veins are the most commonly affected sites, particularly the deep veins in the legs, the inferior vena cava, the superior vena cava, and the renal veins. Arterial thrombosis, which is less common, typically occurs in the cerebral, pulmonary, and femoral arteries, and is associated with the use of steroids and diuretics. Popliteal artery thrombosis in children has been described in cases of traumatic dissection, osteochondroma, Mycoplasma pneumoniae infection, and fibromuscular dysplasia. We report of a 33-month-old girl with bilateral iliac and popliteal arterial thrombosis associated with steroid-resistant NS due to focal segmental glomerulosclerosis. Her treatment involved thrombectomy and intravenous heparinization, followed by oral warfarin for 8 months. Herein, we report a rare case of spontaneous iliac and popliteal arterial thrombosis in a young child with NS.

The effects of thrombomodulin and activated protein C on the pathogenesis of multiple sclerosis

BACKGROUND

Various molecules of the coagulation cascade are thought to have varying roles in the pathophysiology of multiple sclerosis (MS). We aimed to find new information about the effects of the coagulation cascade molecules to develop new therapeutic strategies for MS.

MATERIALS AND METHODS

Patients with MS were chosen from among patients who were followed up at our hospital. We examined the thrombomodulin (TM) and activated protein C (APC) serum levels in patients with MS and the healthy controls. The patient groups were determined as relapsing-remitting MS (RRMS) or secondary progressive MS (SPMS) according to the McDonald criteria and between ages of 18 and 70.

RESULTS

A total of 244 participants, 122 patients with multiple sclerosis and 122 healthy volunteers were included in the study. There was no statistically significant difference in the APC and TM levels between the patients and the healthy controls (p>0.05), between the patients with RRMS and SPMS (p>0.05), and between the first day of acute relapse and 10th day of methylprednisolone therapy in the patients with RRMS (p=0.334; p=0.363). We detected a statistically positive correlation only between the expanded disability status scale (EDSS) scores and TM levels in the patient group (p=0.009).

CONCLUSION

Treatment with methylprednisolone decreases EDSS score in RRMS relapse. The increase in EDSS is related to level of TM. The changes in level of TM and APC may be indicator for prognosis of MS or treatment modalities to MS.

Levels of protein C and soluble thrombomodulin in critically ill patients with acute kidney injury: a multicenter prospective observational study

Endothelial dysfunction contributes to the development of acute kidney injury (AKI) in animal models of ischemia reperfusion injury and sepsis. There are limited data on markers of endothelial dysfunction in human AKI. We hypothesized that Protein C (PC) and soluble thrombomodulin (sTM) levels could predict AKI. We conducted a multicenter prospective study in 80 patients to assess the relationship of PC and sTM levels to AKI, defined by the AKIN creatinine (AKI Scr) and urine output criteria (AKI UO). We measured marker levels for up to 10 days from intensive care unit admission. We used area under the curve (AUC) and time-dependent multivariable Cox proportional hazard model to predict AKI and logistic regression to predict mortality/non-renal recovery. Protein C and sTM were not different in patients with AKI UO only versus no AKI. On intensive care unit admission, as PC levels are usually lower with AKI Scr, the AUC to predict the absence of AKI was 0.63 (95%CI 0.44-0.78). The AUC using log10 sTM levels to predict AKI was 0.77 (95%CI 0.62-0.89), which predicted AKI Scr better than serum and urine neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, urine kidney injury molecule-1 and liver-fatty acid-binding protein. In multivariable models, PC and urine NGAL levels independently predicted AKI (p=0.04 and 0.02) and PC levels independently predicted mortality/non-renal recovery (p=0.04). In our study, PC and sTM levels can predict AKI Scr but are not modified during AKI UO alone. PC levels could independently predict mortality/non-renal recovery. Additional larger studies are needed to define the relationship between markers of endothelial dysfunction and AKI.

Gemfibrozil attenuates the inflammatory response and protects rats from abdominal sepsis

Sepsis is a serious condition characterized by an infectious process that induces a severe systemic inflammatory response. In this study, the effects of gemfibrozil (GFZ) on the inflammatory response associated with abdominal sepsis were investigated using a rat model of cecal-ligation and puncture (CLP). Male Wistar rats were randomly divided into three groups: Sham-operated group (sham), where laparotomy was performed, the intestines were manipulated, and the cecum was ligated but not punctured; control group, subjected to CLP; and GFZ group, which received GFZ prior to undergoing CLP. The groups were then subdivided into three different time-points: 2, 4 and 24 h, indicating the time at which blood samples were obtained for analysis. Serum concentrations of tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were determined. The LDH, AST and ALT values were significantly elevated following CLP compared with those in the sham group, and GFZ treatment was able to reduce these elevations. GFZ also reduced the sepsis-induced elevations of TNF-α and IL-1. In conclusion, GFZ treatment was able to attenuate the inflammatory response associated with CLP-induced sepsis, by diminishing the release of inflammatory cytokines, thereby reducing tissue injury and oxidative stress.

Thrombomodulin alfa treatment in patients with acute promyelocytic leukemia and disseminated intravascular coagulation: a retrospective analysis of an open-label, multicenter, post-marketing surveillance study cohort

INTRODUCTION

Patients with acute promyelocytic leukemia (APL) can develop disseminated intravascular coagulation (DIC) that results in life-threatening hemorrhagic complications. Studies regarding the safety and efficacy of thrombomodulin alfa (TM-α; recombinant human soluble thrombomodulin) in patients with APL and DIC are limited.

MATERIALS AND METHODS

A retrospective evaluation was performed on a cohort of 172 patients with APL from an open-label, multicenter, post-marketing surveillance study of TM-α.

RESULTS

Of the 172 patients, 31 were relapse/refractory APL patients, and 141 were newly diagnosed APL patients. Within the first 30 days, 24 patients (14.0%) died, and six of those deaths (3.5%) were due to hemorrhage. In total, 12 patients (7.0%) had severe hemorrhagic complications. Both the early death rate due to hemorrhage as well as the severe hemorrhage rate did not exceed those in some recent population-based studies of patients with APL. Forty-nine patients received TM-α prior to the initiation of antileukemic treatment, and one patient experienced hemorrhagic early death (ED), suggesting that early TM-α treatment appeared to result in a reduction in the hemorrhagic ED rate. Moreover, TM-α improved coagulopathy regardless of concomitant all-trans retinoic acid treatment.

CONCLUSIONS

This study confirmed the safety and efficacy of TM-α in daily clinical practice for patients with APL and DIC. TM-α appeared to reduce hemorrhagic early deaths due to DIC in patients with APL who were receiving antileukemic treatment.

Biased signaling of protease-activated receptors

In addition to their role in protein degradation and digestion, proteases can also function as hormone-like signaling molecules that regulate vital patho-physiological processes, including inflammation, hemostasis, pain, and repair mechanisms. Certain proteases can signal to cells by cleaving protease-activated receptors (PARs), a family of four G protein-coupled receptors. PARs are expressed by almost all cell types, control important physiological and disease-relevant processes, and are an emerging therapeutic target for major diseases. Most information about PAR activation and function derives from studies of a few proteases, for example thrombin in the case of PAR1, PAR3, and PAR4, and trypsin in the case of PAR2 and PAR4. These proteases cleave PARs at established sites with the extracellular N-terminal domains, and expose tethered ligands that stabilize conformations of the cleaved receptors that activate the canonical pathways of G protein- and/or β-arrestin-dependent signaling. However, a growing number of proteases have been identified that cleave PARs at divergent sites to activate distinct patterns of receptor signaling and trafficking. The capacity of these proteases to trigger distinct signaling pathways is referred to as biased signaling, and can lead to unique patho-physiological outcomes. Given that a different repertoire of proteases are activated in various patho-physiological conditions that may activate PARs by different mechanisms, signaling bias may account for the divergent actions of proteases and PARs. Moreover, therapies that target disease-relevant biased signaling pathways may be more effective and selective approaches for the treatment of protease- and PAR-driven diseases. Thus, rather than mediating the actions of a few proteases, PARs may integrate the biological actions of a wide spectrum of proteases in different patho-physiological conditions.

Protein C and acute inflammation: a clinical and biological perspective

The protein C system plays an active role in modulating severe systemic inflammatory processes such as sepsis, trauma, and acute respiratory distress syndrome (ARDS) via its anticoagulant and anti-inflammatory properties. Plasma levels of activated protein C (aPC) are lower than normal in acute inflammation in humans, except early after severe trauma when high plasma levels of aPC may play a mechanistic role in the development of posttraumatic coagulopathy. Thus, following positive results of preclinical studies, a clinical trial (PROWESS) with high continuous doses of recombinant human aPC given for 4 days demonstrated a survival benefit in patients with severe sepsis. This result was not confirmed by subsequent clinical trials, including the recently published PROWESS-SHOCK trial in patients with septic shock and a phase II trial with patients with nonseptic ARDS. A possible explanation for the major difference in outcome between PROWESS and PROWESS-SHOCK trials is that lung-protective ventilation was used for the patients included in the recent PROWESS-SHOCK, but not in the original PROWESS trial. Since up to 75% of sepsis originates from the lung, aPC treatment may not have added enough to the beneficial effect of lung-protective ventilation to show lower mortality. Thus whether aPC will continue to be used to modulate the acute inflammatory response in humans remains uncertain. Because recombinant human aPC has been withdrawn from the market, a better understanding of the complex interactions between coagulation and inflammation is needed before considering the development of new drugs that modulate both coagulation and acute inflammation in humans.

Cytokines in sepsis: potent immunoregulators and potential therapeutic targets--an updated view

Sepsis and septic shock are among the leading causes of death in intensive care units worldwide. Numerous studies on their pathophysiology have revealed an imbalance in the inflammatory network leading to tissue damage, organ failure, and ultimately, death. Cytokines are important pleiotropic regulators of the immune response, which have a crucial role in the complex pathophysiology underlying sepsis. They have both pro- and anti-inflammatory functions and are capable of coordinating effective defense mechanisms against invading pathogens. On the other hand, cytokines may dysregulate the immune response and promote tissue-damaging inflammation. In this review, we address the current knowledge of the actions of pro- and anti-inflammatory cytokines in sepsis pathophysiology as well as how these cytokines and other important immunomodulating agents may be therapeutically targeted to improve the clinical outcome of sepsis.

Treatment with activated protein C (aPC) is protective during the development of myocardial fibrosis: an angiotensin II infusion model in mice

Aims

Myocardial fibrosis contributes to the development of heart failure. Activated Protein C (aPC) is a circulating anticoagulant with anti-inflammatory and cytoprotective properties. Using a model of myocardial fibrosis second to Angiotensin II (AngII) infusion, we investigated the novel therapeutic function aPC in the development of fibrosis.

Methods and Results

C57Bl/6 and Tie2-EPCR mice were infused with AngII (2.0 µg/kg/min), AngII and aPC (0.4 µg/kg/min) or saline for 3d. Hearts were harvested and processed for analysis or used for cellular isolation. Basic histology and collagen deposition were assessed using histologic stains. Transcript levels of molecular mediators were analyzed by quantitative RT-PCR. Mice infused with AngII exhibited multifocal areas of myocardial cellular infiltration associated with significant collagen deposition compared to saline control animals (p<0.01). AngII-aPC infusion inhibited this cellular infiltration and the corresponding collagen deposition. AngII-aPC infusion also inhibited significant expression of the pro-fibrotic cytokines TGF-β1, CTGF and PDGF found in AngII only infused animals (p<0.05). aPC signals through its receptor, EPCR. Using Tie2-EPCR animals, where endothelial cells over-express EPCR and exhibit enhanced aPC-EPCR signaling, no significant reduction in cellular infiltration or fibrosis was evident with AngII infusion suggesting aPC-mediate protection is endothelial cell independent. Isolated infiltrating cells expressed significant EPCR transcripts suggesting a direct effect on infiltrating cells.

Conclusions

This data indicates that aPC treatment abrogates the fibrogenic response to AngII. aPC does not appear to confer protection by stimulating the endothelium but by acting directly on the infiltrating cells, potentially inhibiting migration or activation.

Simvastatin is protective during Staphylococcus aureus pneumonia

Epidemiologic studies suggest that the incidence and severity of sepsis are ameliorated in patients on statins (3- hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) for cholesterol lowering indications. We sought to understand the mechanism underlying such protection and hypothesized that simvastatin would be protective in mice against acute infection with Staphylococcus aureus, the primary etiologic agent in sepsis. Mice were treated with simvastatin or buffer for two weeks and were subsequently challenged with S. aureus intratracheally or intravenously. Relative to buffer-treated mice, bacterial killing was enhanced 4-fold (p=0.02), systemic dissemination was reduced, and lethality was decreased (hazard ratio 8.8, 95% CI 2.5 to 31.3, p=0.001) in mice that were pretreated with simvastatin for two weeks. Systemic inflammatory response was abrogated and the local elaboration of inflammatory mediators was diminished. Serum concentrations of pro-fibrinolytic protein C were elevated (p=0.034), while the concentration of pro-coagulant tissue factor in bronchoalveolar lavage fluids was attenuated (reduced 25%), p=0.001, in simvastatin-treated mice. Taken together, these data indicate that extended treatment with simvastatin is protective during infection with S. aureus through enhanced bacterial clearance, anti-inflammatory, and anti-coagulant activities. These studies provide insights into the mechanism by which statins confer protection in acute infection, support the notion that statins may be effective adjuncts in the treatment of sepsis, and provide a rationale for randomized control trials in patients that are at a high risk for infection characterized by coagulopathy.

Human recombinant activated protein C for severe sepsis

BACKGROUND

Sepsis is a common and frequently fatal condition. Human recombinant activated protein C (APC) has been used to reduce the high rate of death by severe sepsis or septic shock. This is an update of a Cochrane review (originally published in 2007 and updated in 2008).

OBJECTIVES

We assessed the clinical effectiveness and safety of APC for the treatment of patients with severe sepsis or septic shock.

SEARCH METHODS

For this updated review we searched CENTRAL (The Cochrane Library 2010, Issue 6); MEDLINE (1966 to June 2010); EMBASE (1980 to July 1, 2010); BIOSIS (1965 to July 1, 2010); CINAHL (1982 to 16 June 2010) and LILACS (1982 to 16 June 2010). There was no language restriction.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing the effects of APC for severe sepsis in adults and children. We excluded studies on neonates. We considered all-cause mortality at day 28, at the end of study follow up, and hospital mortality as the primary outcomes.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

We identified one new RCT in this update. We included a total of five RCTs involving 5101 participants. For 28-day mortality, APC did not reduce the risk of death in adult participants with severe sepsis (pooled RR 0.97, 95% confidence interval (CI) 0.78 to 1.22; P = 0.82, I(2) = 68%). APC use was associated with an increased risk of bleeding (RR 1.47, 95% CI 1.09 to 2.00; P = 0.01, I(2) = 0%). In paediatric patients, APC did not reduce the risk of death (RR 0.98, 95% CI 0.66 to 1.46; P = 0.93). Although the included trials had no major limitations most of them modified their original completion or recruitment protocols.

AUTHORS' CONCLUSIONS

This updated review found no evidence suggesting that APC should be used for treating patients with severe sepsis or septic shock. Additionally, APC is associated with a higher risk of bleeding. Unless additional RCTs provide evidence of a treatment effect, policy-makers, clinicians and academics should not promote the use of APC.Warning: On October 25th 2011, the European Medicines Agency issued a press release on the worldwide withdrawal of Xigris (activated protein C / drotrecogin alfa) from the market by Eli Lilly due to lack of beneficial effect on 28-day mortality in the PROWESS-SHOCK study. Furthermore, Eli Lily has announced the discontinuation of all other ongoing clinical trials. The final results of the PROWESS-SHOCK study are expected to be published in 2012. This systematic review will be updated when results of the PROWESS-SHOCK or other trials are published.

Is EPCR a multi-ligand receptor? Pros and cons

In the last decade, the endothelial cell protein C/activated protein C receptor (EPCR) has received considerable attention. The role initially attributed to EPCR, i.e. the enhancement of protein C (PC) activation by the thrombin-thrombomodulin complex on the surface of the large vessels, although important, did not go beyond the haemostasis scenario. However, the discovery of the cytoprotective, anti-inflammatory and anti-apoptotic features of the activated PC (APC) and the required involvement of EPCR for APC to exert such actions did place the receptor in a privileged position in the crosstalk between coagulation and inflammation. The last five years have shown that PC/APC are not the only molecules able to interact with EPCR. Factor VII/VIIa (FVII/VIIa) and factor Xa (FXa), two other serine proteases that play a central role in haemostasis and are also involved in signalling processes influencing wound healing, tissue remodelling, inflammation or metastasis, have been reported to bind to EPCR. These observations have paved the way for an exploration of unsuspected new roles for the receptor. This review aims to offer a new image of EPCR in the light of its extended panel of ligands. A brief update of what is known about the APC-evoked EPCR-dependent cell signalling mechanisms is provided, but special care has been taken to assemble all the information available about the interaction of EPCR with FVII/VIIa and FXa.

Activated protein C inhalation: a novel therapeutic strategy for acute lung injury

Acute lung injury (ALI) is a critical illness syndrome with a mortality rate of 25–40%. Despite recent advances of our understanding of the pathophysiology of ALI, no pharmacologic therapies have been proven effective. The key pathogenesis of ALI is the activation of the coagulation cascade and impaired fibrinolysis, resulting in extensive fibrin and hyaline membrane deposition. Activated protein C (APC), an endogenous protein that promotes fibrinolysis and inhibits thrombosis, can modulate the coagulation and inflammation associated with ALI. It is therefore reasonable to suggest that preventing the progression of pulmonary coagulopathy, by restoring normal intraalveolar levels of protein C, will be of therapeutic benefit to patients with ALI. However, a recent clinical trial demonstrated that APC did not improve outcomes from ALI, raising the possibility that the method of APC administration, intravenous infusion or inhalation, may influence the outcomes. In this article we propose the hypothesis that APC inhalation might be a promising and novel choice in the treatment of ALI.

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.

A matrix metalloprotease-PAR1 system regulates vascular integrity, systemic inflammation and death in sepsis

Sepsis is a deadly disease characterized by the inability to regulate the inflammatory–coagulation response in which the endothelium plays a key role. The cause of this perturbation remains poorly understood and has hampered the development of effective therapeutics. Matrix metalloproteases (MMPs) are involved in the host response to pathogens, but can also cause uncontrolled tissue damage and contribute to mortality. We found that human sepsis patients had markedly elevated plasma proMMP-1 and active MMP-1 levels, which correlated with death at 7 and 28 days after diagnosis. Likewise, septic mice had increased plasma levels of the MMP-1 ortholog, MMP-1a. We identified mouse MMP-1a as an agonist of protease-activated receptor-1 (PAR1) on endothelial cells. MMP-1a was released from endothelial cells in septic mice. Blockade of MMP-1 activity suppressed endothelial barrier disruption, disseminated intravascular coagulation (DIC), lung vascular permeability as well as the cytokine storm and improved survival, which was lost in PAR1-deficient mice. Infusion of human MMP-1 increased lung vascular permeability in normal wild-type mice but not in PAR1-deficient mice. These findings implicate MMP-1 as an important activator of PAR1 in sepsis and suggest that therapeutics that target MMP1-PAR1 may prove beneficial in the treatment of sepsis.

Human recombinant activated protein C for severe sepsis

BACKGROUND

Sepsis is a common and frequently fatal condition. Human recombinant activated protein C (APC) has been used to reduce the high rate of death by severe sepsis or septic shock. This is an update of a Cochrane review (originally published in 2007 and updated in 2008).

OBJECTIVES

We assessed the clinical effectiveness and safety of APC for the treatment of patients with severe sepsis or septic shock.

SEARCH STRATEGY

For this updated review we searched CENTRAL (The Cochrane Library 2010, Issue 6); MEDLINE (1966 to June 2010); EMBASE (1980 to July 1, 2010); BIOSIS (1965 to July 1, 2010); CINAHL (1982 to 16 June 2010) and LILACS (1982 to 16 June 2010). There was no language restriction.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing the effects of APC for severe sepsis in adults and children. We excluded studies on neonates. We considered all-cause mortality at day 28, at the end of study follow up, and hospital mortality as the primary outcomes.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

We identified one new RCT in this update. We included a total of five RCTs involving 5101 participants. For 28-day mortality, APC did not reduce the risk of death in adult participants with severe sepsis (pooled RR 0.97, 95% confidence interval (CI) 0.78 to 1.22; P = 0.82, I(2) = 68%). APC use was associated with an increased risk of bleeding (RR 1.47, 95% CI 1.09 to 2.00; P = 0.01, I(2) = 0%). In paediatric patients, APC did not reduce the risk of death (RR 0.98, 95% CI 0.66 to 1.46; P = 0.93). Although the included trials had no major limitations most of them modified their original completion or recruitment protocols.

AUTHORS' CONCLUSIONS

This updated review found no evidence suggesting that APC should be used for treating patients with severe sepsis or septic shock. Additionally, APC is associated with a higher risk of bleeding. Unless additional RCTs provide evidence of a treatment effect, policy-makers, clinicians and academics should not promote the use of APC.

Cytoprotective-selective activated protein C attenuates Pseudomonas aeruginosa-induced lung injury in mice

Inhibition of the small GTPase RhoA attenuates the development of pulmonary edema and restores positive alveolar fluid clearance in a murine model of Pseudomonas aeruginosa pneumonia. Activated protein C (aPC) blocks the development of an unfavorably low ratio of small GTPase Rac1/RhoA activity in lung endothelium through endothelial protein C receptor (EPCR)/protease-activated receptor-1 (PAR-1)-dependent signaling mechanisms that include transactivating the sphingosine-1-phosphate (S1P) pathway. However, whether aPC's cytoprotective effects can attenuate the development of pulmonary edema and death associated with P. aeruginosa pneumonia in mice remains unknown. Thus, we determined whether the normalization of a depressed ratio of activated Rac1/RhoA by aPC would attenuate the P. aeruginosa-mediated increase in protein permeability across lung endothelial and alveolar epithelial barriers. Pretreatment with aPC significantly reduced P. aeruginosa-induced increases in paracellular permeability across pulmonary endothelial cell and alveolar epithelial monolayers via an inhibition of RhoA activation and a promotion of Rac1 activation that required the EPCR-PAR-1 and S1P pathways. Furthermore, pretreatment with aPC attenuated the development of pulmonary edema in a murine model of P. aeruginosa pneumonia. Finally, a cytoprotective-selective aPC mutant, aPC-5A, which lacks most of aPC's anticoagulant activity, reproduced the protective effect of wild-type aPC by attenuating the development of pulmonary edema and decreasing mortality in a murine model of P. aeruginosa pneumonia. Taken together, these results demonstrate a critical role for the cytoprotective activities of aPC in attenuating P. aeruginosa-induced lung vascular permeability and mortality, suggesting that cytoprotective-selective aPC-5A with diminished bleeding risks could attenuate the lung damage caused by P. aeruginosa in critically ill patients.

Sepsis-associated encephalopathy and its differential diagnosis

Sepsis-associated encephalopathy (SAE) is defined as a diffuse cerebral dysfunction resulting from the systemic inflammatory response to an infection without direct infestation of the CNS. Although the pathophysiology of SAE is as yet unknown, some mechanisms have been suggested that involve BBB disruption as a consequence of proinflammatory mediators’ effects on endothelial cells. This leads to an increased passage of neurotoxic and proinflammatory mediators into the brain parenchyma, as well as an impairment of the movements of oxygen and metabolites through the BBB. Both neurons and glial cells are affected, resulting in neural functioning and neurotransmission impairment. The clinical translation of this process is an alteration of consciousness and awareness. SAE is a frequent condition in septic patients. Despite being considered reversible, SAE appears to be associated with long-term cognitive impairment. Detection and diagnosis can be challenging; it requires daily neurological assessment with the assistance of clinical scores. Use of biomarkers and neurophysiological testing is discussed. The aim of this article is to provide practical tools for detection of SAE, as well as an updated overview of its pathophysiology and therapeutic perspectives.

Comparison of thromboelastometry with procalcitonin, interleukin 6, and C-reactive protein as diagnostic tests for severe sepsis in critically ill adults

Introduction

Established biomarkers for the diagnosis of sepsis are procalcitonin, interleukin 6, and C-reactive protein. Although sepsis evokes changes of coagulation and fibrinolysis, it is unknown whether thromboelastometry can detect these alterations. We investigated whether thromboelastometry variables are suitable as biomarkers for severe sepsis in critically ill adults.

Methods

In the observational cohort study, blood samples were obtained from patients on the day of diagnosis of severe sepsis (n = 56) and from postoperative patients (n = 52), and clotting time, clot formation time, maximum clot firmness, alpha angle, and lysis index were measured with thromboelastometry. In addition, procalcitonin, interleukin 6, and C-reactive protein levels were determined. For comparison of biomarkers, receiver operating characteristic (ROC) curves were used, and the optimal cut-offs and odds ratios were calculated.

Results

In comparison with postoperative controls, patients with sepsis showed an increase in lysis index (97% ± 0.3 versus 92 ± 0.5; P < 0.001; mean and SEM) and procalcitonin (2.5 ng/ml ± 0.5 versus 30.6 ± 8.7; P < 0.001). Clot-formation time, alpha angle, maximum clot firmness, as well as interleukin 6 and C-reactive protein concentrations were not different between groups; clotting time was slightly prolonged. ROC analysis demonstrated an area under the curve (AUC) of 0.901 (CI 0.838 - 0.964) for the lysis index, and 0.756 (CI 0.666 - 0.846) for procalcitonin. The calculated cut-off for the lysis index was > 96.5%, resulting in a sensitivity of 84.2%, and a specificity of 94.2%, with an odds ratio of 85.3 (CI 21.7 - 334.5).

Conclusions

The thromboelastometry lysis index proved to be a more reliable biomarker of severe sepsis in critically ill adults than were procalcitonin, interleukin 6, and C-reactive protein. The results also demonstrate that early involvement of the hemostatic system is a common event in severe sepsis.

APCAP--activated protein C in acute pancreatitis: a double-blind randomized human pilot trial

Introduction

Previous human studies have shown low activity of protein C (APC) in severe acute pancreatitis (SAP). This, together with the findings in animal models, suggests that activated protein C (APC) may protect against pancreatic injury and ameliorate the disease. We, therefore, evaluated its effect on multiple organ dysfunction (MOD) measured by the SOFA (Sequential Organ Failure Assessment) and on organ-failure-free days, and the safety of APC in SAP.

Methods

A prospective double blind randomized pilot study was use. The study occurred in one university hospital tertiary intensive care unit (ICU) with eight beds. The patients were chosen according to the following inclusion criteria: 1) Those admitted to the hospital < 96 h from the onset of pain, 2) Those who had a three-fold increase in serum amylase over normal upper range or/and in whom computed tomography (CT) verification of SAP was noted, 3) Those who had one or more organ dysfunction (OD), and 4) Those in whom less than 48 hours had passed since their first OD. Of a total of 215 adult patients with SAP screened between June 2003 and August 2007, 158 fulfilled the study inclusion criteria. After exclusions 32 patients were randomized to the study. The intervention consisted of APC (N = 16) administered intravenously for 96 hours with a dose of 24 μg/kg/hour or placebo (N = 16) with a similar infusion rate. The sample size for the study was calculated according to the primary end-point: the change in SOFA during study drug infusion (Days 0 and 5). Comparisons between the study groups were performed using patient-related changes and calculation of difference in means (DIM, 95% CIs) and regarding categorical variables with Fisher's exact test. For all comparisons P < 0.05 was considered significant.

Results

No serious bleeding was detected clinically or by CT scans in either group. No significant difference in SOFA score change between the APC and placebo groups was found (difference in means (DIM) +2.3, 95% CI -0.7 to +5.3). Treatment with APC was associated with an increase in serum levels of both total and conjugated bilirubin. No differences in ventilator-free days, in renal replacement therapy-free days, in vasopressor-free days, or in days alive outside the hospital were detected.

Conclusions

No serious bleeding or differences in the evolution of MOD were detected between APC and the placebo. Instead we found an increase in serum bilirubin in the APC group compared to the placebo group in patients with SAP.

Trial registration

ClinicalTrials.gov NCT01017107.

Inducible innate resistance of lung epithelium to infection

Most studies of innate immunity have focused on leukocytes such as neutrophils, macrophages, and natural killer cells. However, epithelial cells play key roles in innate defenses that include providing a mechanical barrier to microbial entry, signaling to leukocytes, and directly killing pathogens. Importantly, all these defenses are highly inducible in response to the sensing of microbial and host products. In healthy lungs, the level of innate immune epithelial function is low at baseline. This is indicated by low levels of spontaneous microbial killing and cytokine release, reflecting low constitutive stimulation in the nearly sterile lower respiratory tract when mucociliary clearance mechanisms are functioning effectively. This contrasts with the colon, where bacteria are continuously present and epithelial cells are constitutively activated. Although the surface area of the lungs presents a large target for microbial invasion, activated lung epithelial cells that are closely apposed to deposited pathogens are ideally positioned for microbial killing.

Activated protein C action in inflammation

Activated protein C (APC) is a natural anticoagulant that plays an important role in coagulation homeostasis by inactivating the procoagulation factor Va and VIIIa. In addition to its anticoagulation functions, APC also has cytoprotective effects such as anti-inflammatory, anti-apoptotic, and endothelial barrier protection. Recently, a recombinant form of human APC (rhAPC or drotrecogin alfa activated; known commercially as 'Xigris') was approved by the US Federal Drug Administration for treatment of severe sepsis associated with a high risk of mortality. Sepsis, also known as systemic inflammatory response syndrome (SIRS) resulting from infection, is a serious medical condition in critical care patients. In sepsis, hyperactive and dysregulated inflammatory responses lead to secretion of pro- and anti-inflammatory cytokines, activation and migration of leucocytes, activation of coagulation, inhibition of fibrinolysis, and increased apoptosis. Although initial hypotheses focused on antithrombotic and profibrinolytic functions of APC in sepsis, other agents with more potent anticoagulation functions were not effective in treating severe sepsis. Furthermore, APC therapy is also associated with the risk of severe bleeding in treated patients. Therefore, the cytoprotective effects, rather than the anticoagulant effect of APC are postulated to be responsible for the therapeutic benefit of APC in the treatment of severe sepsis.

Mediators and receptors in the resolution of inflammation: drug targeting opportunities

The active resolution of inflammation is recognized as offering new opportunities to generate novel anti-inflammatory agents. The emerging appreciation of the importance of active resolution in regulation of inflammation also creates an imperative to examine developing and existing agents for their potential to influence these pathways. This themed issue of the British Journal of Pharmacology contains papers that discuss the roles of annexin-1, lipoxins and related lipid products of fish oils as well as other mechanisms involved in active resolution and their receptor targets.

Compartmental apoptosis and neutrophil accumulation in severe peritonitis

BACKGROUND

Migration and activation of polymorphonuclear neutrophils (PMN) and apoptosis are central to inflammatory tissue damage. This study examines the relation of these processes, and their expression in the abdominal, systemic, and bronchoalveolar compartments in patients with severe peritonitis.

MATERIALS AND METHODS

Thirty-one consecutive patients undergoing laparotomy for severe secondary peritonitis. Eight operated patients without peritonitis and 10 long-term mechanically ventilated noninfected patients served as controls. Peritoneal fluid, blood, and bronchoalveolar lavage fluid (BALF) was obtained on d 0 (day of initial laparotomy), 2, and 3. Levels of chemokines (interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1), PMN-counts, PMN activation [myeloperoxidase (MPO), elastase] and apoptosis (nucleosomes) were determined.

RESULTS

In peritonitis patients, levels of chemokines and markers of PMN sequestration were increased in all compartments. IL-8 levels were higher in BALF than in plasma, and did not originate from the circulation or from lysis of alveolar cells. Pulmonary nucleosome levels were higher in patients who died (P=0.020), and corresponded with PMN-count in BALF (P<0.001), levels of chemokines (IL-8, P=0.003; MCP-1, P=0.001), and PMN-activation (MPO, P<0.001; elastase P=0.007).

CONCLUSION

Severe peritonitis produces an early pulmonary expression of chemoattractants creating a gradient for PMN sequestration and activation into the lung. These parameters are associated with expression of apoptosis in the lung, which is increased in nonsurviving peritonitis patients.