Human protein C zymogen concentrate in patients with severe sepsis and multiple organ failure after adult cardiac surgery

Endothelial dysfunction and immunothrombosis in sepsis

Sepsis is a life-threatening clinical syndrome characterized by multiorgan dysfunction caused by a dysregulated or over-reactive host response to infection. During sepsis, the coagulation cascade is triggered by activated cells of the innate immune system, such as neutrophils and monocytes, resulting in clot formation mainly in the microcirculation, a process known as immunothrombosis. Although this process aims to protect the host through inhibition of the pathogen’s dissemination and survival, endothelial dysfunction and microthrombotic complications can rapidly lead to multiple organ dysfunction. The development of treatments targeting endothelial innate immune responses and immunothrombosis could be of great significance for reducing morbidity and mortality in patients with sepsis. Medications modifying cell-specific immune responses or inhibiting platelet–endothelial interaction or platelet activation have been proposed. Herein, we discuss the underlying mechanisms of organ-specific endothelial dysfunction and immunothrombosis in sepsis and its complications, while highlighting the recent advances in the development of new therapeutic approaches aiming at improving the short- or long-term prognosis in sepsis.

Nonactivated Protein C in the Treatment of Neonatal Sepsis: A Retrospective Analysis of Outcome

BACKGROUND

Previously, we found that plasma protein C (PC) activity ≤10% significantly increased the probability of the occurrence of death during neonatal sepsis. Accordingly, if the activity of plasma PC declined during the course of sepsis to ≤10%, we administered a nonactivated PC zymogen to increase a PC activity. The aim of that retrospective analysis was to explore treatment effects of PC zymogen supplementation in septic infants, with plasma PC activity ≤10%.

METHODS

A database was used to locate 85 newborns treated with PC from among 458 analyzed infants with confirmed sepsis.

RESULTS

The median birth weight and gestational age of treated infants were, respectively, 1010.0 g and 29 weeks. In 47 infants, early-onset sepsis developed, whereas in 38 neonates, late-onset sepsis was recognized. PC was given as a single dose of 200 IU/kg. Among 458 septic patients, death occurred in 19 newborns (4.2%), exclusively in infants with plasma PC activity ≤10%. In 15 infants, death occurred in the course of early-onset sepsis and 4 newborns died of late-onset sepsis (early-onset sepsis vs. late-onset sepsis; P = 0.036; χ with the Yates correction).

CONCLUSIONS

An increased risk of death in septic neonates with plasma PC activity ≤10% suggests the necessity for its evaluation and possibility of supplementation of PC zymogen.

Protein C zymogen in severe sepsis: a double-blinded, placebo-controlled, randomized study

PURPOSE

To determine whether protein C zymogen (protein C concentrates or human protein C) improves clinically relevant outcomes in adult patients with severe sepsis and septic shock.

METHODS

This is a randomized, double-blind, placebo-controlled, parallel-group trial that from September 2012 to June 2014 enrolled adult patients with severe sepsis or septic shock and high risk of death and of bleeding (e.g., APACHE II greater than 25, extracorporeal membrane oxygenation or disseminated intravascular coagulopathy). All patients completed their follow-up 90 days after randomization and data were analyzed according to the intention-to-treat principle. Follow-up was performed at 30 and 90 days after randomization. The primary endpoint was a composite outcome of prolonged intensive care unit (ICU) stay and/or 30-day mortality. Secondary endpoints included mortality.

RESULTS

The study was stopped early in a situation of futility for the composite outcome of prolonged ICU stay and/or 30-day mortality that was 79 % (15 patients) in the protein C zymogen group and 67 % (12 patients) in the placebo group (p = 0.40) and for a concomitant safety issue: ICU mortality was 79 % (15 patients) in the protein C zymogen group vs 39 % (7 patients) in the placebo group (p = 0.020), and 30-day mortality was 68 vs 39 % (p = 0.072).

CONCLUSION

Protein C zymogen did not improve clinically relevant outcomes in severe sepsis and septic shock adult patients. Given its high cost and the potential increase in mortality, the use of this drug in adult patients should be discouraged.

Clinical aspects of sepsis: an overview

Sepsis is one of the oldest and most elusive syndromes in medicine. With the confirmation of germ theory by Semmelweis, Pasteur, and others, sepsis was considered as a systemic infection by a pathogenic organism. Although the germ is probably the beginning of the syndrome and one of the major enemies to be identified and fought, sepsis is something wider and more elusive. In this chapter clinically relevant themes of sepsis will be approached to provide an insight of everyday clinical practice for healthcare workers often not directly involved in the patient's management.

Coronary artery bypass grafting in 2 thrombophilic patients with protein s deficiency

In this report, we review 2 cases of coronary revascularization in patients with a diagnosis of coronary artery disease and preoperative protein S deficiency, an established hypercoagulable condition. In an attempt to normalize protein S levels, fresh frozen plasma was used as the priming fluid for the cardiopulmonary bypass circuit before the initiation of extracorporeal circulation. On the basis of a low risk of bleeding and the theoretical risk of thrombosis, neither patient received intraoperative antifibrinolytic treatment nor did they develop perioperative thrombotic complications.

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.

Protein C zymogen in adults with severe sepsis or septic shock

INTRODUCTION

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

DESIGN, SETTING AND PARTICIPANTS

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

RESULTS

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

CONCLUSION

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

The protein C pathway in cancer metastasis

Cancer is frequently associated with activation of blood coagulation, which in turn has been suggested to promote tumor growth and metastasis. Indeed, low molecular weight heparin treatment significantly prolongs the survival of a wide variety of patients with cancer. Based on this notion that anticoagulant treatment seems to benefit cancer patients, recent experiments aimed to elucidate the importance of the natural anticoagulant protein C pathways in cancer progression. Interestingly, these experiments showed that the repeated administration of exogenous activated protein C limits cancer cell extravasation in experimental animal models. In line, reducing endogenous activated protein C activity dramatically increased the number of experimental metastasis. These data thus strongly suggest that exogenous activated protein C administration may be a novel therapeutic avenue to limit cancer metastasis thereby prolonging overall survival of cancer patients. The current review provides an overview of recent data on the role of the protein C pathway in cancer metastasis. It discusses the potential of activated protein C as a novel target to reduce cancer progression, it points to several limitations of activated protein C administration in the setting of cancer cell metastasis and it suggest zymogen protein C as an attractive alternative.

The protein C pathway and sepsis

After the discovery of the key components of the protein C (PC) pathway a beneficial effect on survival of the infusion of activated protein C (APC) in animal models of sepsis was demonstrated, leading to the development of recombinant human activated protein C (rh-APC) as a therapeutic agent. It soon became clear that rather than the anticoagulant and profibrinolytic activities of APC, its anti-inflammatory and cytoprotective properties played a major role in the treatment of patients with severe sepsis. Such properties affect the response to inflammation of endothelial cells and leukocytes and are exerted through binding of APC to at least five receptors with intracellular signaling. The main APC protective mechanism involves binding of the Gla-domain to the endothelial protein C receptor (EPCR) and cleavage of protease activated receptor 1 (PAR-1), eliciting suppression of proinflammatory cytokines synthesis and of intracellular proapoptotic pathways and activation of endothelial barrier properties. However, thrombin cleaves PAR-1 with much higher catalytic efficiency, followed by pro-inflammatory, pro-apoptotic and barrier disruptive intracellular signaling, and it is unclear how APC can exert a protective activity through the cleavage of PAR-1 when thrombin is also present in the same environment. Interestingly, in endothelial cell cultures, PAR-1 cleavage by thrombin results in anti-inflammatory and barrier protective signaling provided occupation of EPCR by the PC gla-domain, raising the possibility that the beneficial effects of rh-APC might be recapitulated in vivo by administration of h-PC zymogen to patients with severe sepsis. Recent reports of h-PC infusion in animal models of sepsis support this hypothesis.

Protein C concentrate controls leukocyte recruitment during inflammation and improves survival during endotoxemia after efficient in vivo activation

Anti-inflammatory properties of protein C (PC) concentrate are poorly studied compared to activated protein C, although PC is suggested to be safer in clinical use. We investigated how PC interferes with the leukocyte recruitment cascade during acute inflammation and its efficacy during murine endotoxemia. We found that similar to activated protein infusion, intravenous PC application reduced leukocyte recruitment in inflamed tissues in a dose- and time-dependent manner. During both tumor necrosis factor-α induced and trauma-induced inflammation of the cremaster muscle, intravital microscopy revealed that leukocyte adhesion and transmigration, but not rolling, were profoundly inhibited by 100 U/kg PC. Moreover, PC blocked leukocyte emigration into the bronchoalveolar space during lipopolysaccharide (LPS) induced acute lung injury. PC was efficiently activated in a murine endotoxemia model, which reduced leukocyte infiltration of organs and strongly improved survival (75% versus 25% of control mice). Dependent on the inflammatory model, PC provoked a significant inhibition of leukocyte recruitment as early as 1 hour after administration. PC-induced inhibition of leukocyte recruitment during acute inflammation critically involves thrombomodulin-mediated PC activation, subsequent endothelial PC receptor and protease-activated receptor-1-dependent signaling, and down-regulation of intercellular adhesion molecule 1 leading to reduced endothelial inflammatory response. We conclude that during acute inflammation and sepsis, PC is a fast acting and effective therapeutic approach to block leukocyte recruitment and improve survival.