Increased mortality in systemic inflammatory response syndrome patients with high levels of coagulation factor VIIa

A bispecific antibody approach for the potential prophylactic treatment of inherited bleeding disorders

Inherited bleeding disorders such as Glanzmann thrombasthenia (GT) lack prophylactic treatment options. As a result, serious bleeding episodes are treated acutely with blood product transfusions or frequent, repeated intravenous administration of recombinant activated coagulation factor VII (rFVIIa). Here we describe HMB-001, a bispecific antibody designed to bind and accumulate endogenous FVIIa and deliver it to sites of vascular injury by targeting it to the TREM (triggering receptor expressed on myeloid cells)-like transcript-1 (TLT-1) receptor that is selectively expressed on activated platelets. In healthy nonhuman primates, HMB-001 prolonged the half-life of endogenous FVIIa, resulting in its accumulation. Mouse bleeding studies confirmed antibody-mediated potentiation of FVIIa hemostatic activity by TLT-1 targeting. In ex vivo models of GT, HMB-001 localized FVIIa on activated platelets and potentiated fibrin-dependent platelet aggregation. Taken together, these results indicate that HMB-001 has the potential to offer subcutaneous prophylactic treatment to prevent bleeds in people with GT and other inherited bleeding disorders, with a low-frequency dosing regimen.

Knockdown of coagulation factor VII has potential anticoagulant and anti-inflammatory effects in a mouse model of group A streptococcal sepsis

Infections originating from subcutaneous tissues are among the most common invasive infections caused by group A streptococcus (GAS) and associated with systemic coagulation activation. The role of intrinsic coagulation factors on GAS virulence has recently been determined, but the role of the extrinsic coagulation factor VII is unknown. Using a mouse model, in which GAS-sepsis emerges from a subcutaneous infection, we show that FVII is a negative acute phase protein. F7 knockdown using antisense oligonucleotides resulted in an attenuated systemic coagulation activation and inflammatory response in septic animals. The findings indicate FVII's ability to modify the host response.

Camelid-derived single-chain antibodies in hemostasis: Mechanistic, diagnostic, and therapeutic applications

Hemostasis is a complex process involving the concerted action of molecular and vascular components. Its basic understanding as well as diagnostic and therapeutic aspects have greatly benefited from the use of monoclonal antibodies. Interestingly, camelid-derived single-domain antibodies (sdAbs), also known as VHH or nanobodies, have become available during the previous 2 decades as alternative tools in this regard. Compared to classic antibodies, sdAbs are easier to produce and their small size facilitates their engineering and functionalization. It is not surprising, therefore, that sdAbs are increasingly used in hemostasis-related research. In addition, they have the capacity to recognize unique epitopes unavailable to full monoclonal antibodies. This property can be used to develop novel diagnostic tests identifying conformational variants of hemostatic proteins. Examples include sdAbs that bind active but not globular von Willebrand factor or free factor VIIa but not tissue factor-bound factor VIIa. Finally, sdAbs have a high therapeutic potential, exemplified by caplacizumab, a homodimeric sdAb targeting von Willebrand factor that is approved for the treatment of thrombotic thrombocytopenic purpura. In this review, the various applications of sdAbs in thrombosis and hemostasis-related research, diagnostics, and therapeutic strategies will be discussed.

A single-domain antibody that blocks factor VIIa activity in the absence but not presence of tissue factor

BACKGROUND

Activated factor VII (FVIIa) is pertinent to the initiation of blood coagulation. Proteolytic and amidolytic activity of FVIIa are greatly enhanced by its cofactor, tissue factor (TF).

OBJECTIVE

We aimed to generate a single-domain antibody (sdAb) that recognizes free FVIIa rather than TF-bound FVIIa.

METHODS

A llama-derived phage library was used to screen for anti-FVIIa sdAbs.

RESULTS

One sdAb, KB-FVIIa-004, bound to FVIIa, but not to its precursor FVII or to homologous proteins (prothrombin, factor X, or their activated derivatives). FVIIa amidolytic activity was inhibited by KB-FVIIa-004 (Ki  = 28-45 nM) in a competitive manner. KB-FVIIa-004 also inhibited FVIIa-mediated FX activation (Ki  = 26 nM). In contrast, KB-FVIIa-004 was inefficient in prolonging the clotting time of the prothrombin time-test, which was prolonged by a maximum of 10 s at high sdAb concentrations (10 μM). Furthermore, FVIIa/TF amidolytic activity or FVIIa/TF-mediated FX activation remained unaffected up to a 50-fold to 1000-fold molar excess of KB-FVIIa-004. These data suggest that KB-FVIIa-004 loses its inhibitory activity in the presence of TF. A KB-FVIIa-004/albumin fusion-protein (004-HSA) was generated for in vivo testing. By using 004-HSA, we observed that this sdAb blocked the therapeutic capacity of FVIIa to correct bleeding in FVIII-deficient mice.

DISCUSSION

This observation is compatible with the view that FVIIa functions independently of TF under these conditions. In conclusion, we have generated a sdAb that specifically blocks TF-independent activity of FVIIa. This antibody can be used to gain insight into the roles of TF-bound and TF-free FVIIa.

Osteoprotegerin is Higher in Sepsis Than in Noninfectious SIRS and Predicts 30-Day Mortality of SIRS Patients in the Intensive Care

BACKGROUND

Systemic inflammatory response syndrome (SIRS) is a complex disease involving multiple pathways and organs. Biomarkers reflecting these pathways and organ function could correlate with the severity of the disease. Osteoprotegerin (OPG), mainly known for its role in bone metabolism, is also involved in the immune and vascular system and is therefore an interesting biomarker to study in SIRS patients. In this prospective observational study, we investigated the correlation of plasma OPG concentrations, sepsis, and 30-day mortality of SIRS patients in the intensive care unit (ICU).

METHODS

This observational, single-center, cohort study included 313 consecutive patients admitted to the ICU, with an anticipated stay of more than 48 h and SIRS on admission. Data from included patients were collected daily until discharge or death for a maximum of 10 days. Thirty-day mortality was retrospectively assessed. OPG concentrations were measured in the first 48 h after admission. The relation of OPG with no sepsis, sepsis, and septic shock was assessed with the Kruskal-Wallis test and the Mann-Whitney U-test. Cox proportional hazards regression was used to study OPG concentrations and 30-day mortality.

RESULTS

OPG concentrations were higher in patients with sepsis and septic shock than in patients without sepsis. Furthermore, patients with OPG concentrations in the highest tertile at admission in the ICU have an increased risk of mortality within 30 days when compared to patients with OPG concentrations in the lowest and middle tertiles, independent of acute physiologic and chronic health evaluation (APACHE) and sequential organ failure assessment (SOFA) scores.

CONCLUSIONS

We show that OPG is a biomarker that correlates with sepsis and predicts mortality of SIRS patients in the ICU.

Myeloperoxidase can differentiate between sepsis and non-infectious SIRS and predicts mortality in intensive care patients with SIRS

Background

Systemic inflammatory response syndrome (SIRS) is a clinical syndrome following inflammation. Clinically, it is difficult to distinguish SIRS following an infection, i.e., sepsis, from non-infectious SIRS. Myeloperoxidase is a hemeprotein stored in the neutrophil azurophilic granules and is one of the main pillars of neutrophil attack. Therefore, we hypothesized that myeloperoxidase can differentiate between sepsis and non-infectious SIRS in patients with systemic inflammatory response syndrome in the intensive care unit (ICU).

Methods

An observational single-center cohort study was conducted measuring myeloperoxidase in patients with SIRS in the first 48 h after admission. The outcomes were established using predefined definitions. Thirty-day mortality was retrospectively assessed.

Results

We found significantly higher levels of myeloperoxidase in patients with sepsis and septic shock compared to patients without sepsis (60 ng/ml versus 43 ng/ml, P = 0.002). Myeloperoxidase levels were related to 30-day mortality (P = 0.032), and high MPO levels on top of a high APACHE IV score further increased mortality risk.

Conclusions

We show that myeloperoxidase is a potentially novel biomarker for sepsis in the ICU. Myeloperoxidase could eventually help in diagnosing sepsis and predicting mortality. However, more research is necessary to confirm our results.

The anticoagulant effect of heparin during radiofrequency ablation (RFA) in patients taking apixaban or rivaroxaban

PURPOSE

Measuring the anticoagulant effect of heparin during radiofrequency ablation (RFA) in patients taking apixaban and rivaroxaban is challenging, since the activated coagulation time (ACT) does not seem to reflect the true anticoagulant activity of these drugs. We therefore evaluated coagulation properties of apixaban and rivaroxaban during RFA by different coagulation assays to better monitor periprocedural hemostasis.

METHODS

The study included 90 patients (61 ± 12 years) with atrial fibrillation who underwent RFA procedures. Patients received 20 mg rivaroxaban (n = 73) once or 5 mg apixaban (n = 17) twice daily 4 weeks prior to the procedure. During RFA, unfractionated heparin i.v. was given to maintain an ACT of 250-300 s. Blood samples were taken before and 10, 60, and 360 min after heparin administration.

RESULTS

Heparin displayed a lower anti-Xa activity in rivaroxaban-treated patients compared to apixaban-treated patients. In contrast, D-dimer and prothrombin fragment F1+2 plasma levels indicated a higher activation of the coagulation cascade in apixaban/heparin than in rivaroxaban/heparin patients. This discordant coagulative state measured in vitro had no clinical impact in terms of bleeding or thromboembolic complications.

CONCLUSION

We found different biochemical responses to rivaroxaban/heparin and apixaban/heparin during RFA. Precaution is necessary when monitoring periprocedural hemostasis in DOAC patients to avoid mismanagement.

Low plasma FVII:C and activated FVII as predictive markers for overt disseminated intravascular coagulation

In sepsis, binding of factor VII (FVII:C) and activated factor VII (FVIIa) with tissue factor is the key step of coagulation resulting in disseminated intravascular coagulation (DIC). We conducted a prospective cohort study among 47 septic patients, aged 8 months to 18.8 years. They were initially divided into three groups of no DIC (n=27), non-overt DIC (n=14) and overt DIC (n=6). Blood samples were collected at 0, 24 and 48 hours (h) after the onset of sepsis. At the onset of sepsis, FVII:C tended to be lower in the non-overt DIC [median 57 % (interquartile range [IQR] 41-80)] and overt DIC groups [33 % (23-52)] than that in the no DIC group [65 % (44-87)]. Whereas FVIIa tended to be lower in the overt DIC group [1.29 % (0.50-4.19)] than those in the non-overt DIC [3.01 % (1.01-5.24)] and no DIC groups [2.49 % (1.14-3.13)]. At 24 h, FVII:C was significantly lower in the non-overt DIC [57 % (41-101)] and overt DIC groups [31 % (28-49)] than that in the no DIC group [83 % (70-102)]. While FVIIa was significantly lower in the overt DIC group [2.15 % (0.86-3.96)] than that in the no DIC group [3.83 % (2.90-5.46)]. Using FVII:C <65 % or FVIIa <3 % at 24 h among patients without hepatic dysfunction to determine overt DIC at 24 h, the sensitivity was 83.9 % and 77.4 %, respectively, and the specificity was both 83.3 %. Patients with low FVII:C and low FVIIa at 24 h after the onset of sepsis had a 20.8-fold (95 % confidence interval [CI], 2.0-213.0, p=0.010) and 14.4-fold (95 %CI, 1.5-142.4, p=0.023) chance of overt DIC.

Soluble P-selectin as a Biomarker for Infection and Survival in Patients With a Systemic Inflammatory Response Syndrome on the Intensive Care Unit

Aims:

This study investigated the ability of soluble platelet selectin (sP-selectin) to identify infection and predict 30-day mortality in patients with a systemic inflammatory response syndrome (SIRS) on the intensive care unit.

Methods:

Soluble platelet selectin levels were measured daily in the first 48 hours in patients presenting with SIRS. The outcome, proven infection, was established using predefined definitions. The 30-day mortality was retrospectively assessed.

Results:

In a total of 313 patients with SIRS, sP-selectin levels were measured. Of these, 114 patients had proven infection on admission or developing during their intensive care unit (ICU) stay. Patients with proven infection had moderately higher levels of sP-selectin (147 ng/mL; interquartile range [IQR], 93.4-203 ng/mL) compared with noninfected patients (143.8 ng/mL; IQR, 89.6-194.7 ng/mL). This difference was not statistically significant (P = .072). However, in patients who were not admitted for infection (n = 235), sP-selectin levels were significantly related to the subsequent development of infection (P = .013). Soluble platelet selectin levels were particularly high in patients with abdominal sepsis and skin infections. Higher sP-selectin levels were associated with higher mortality (although not statistically significant, P = .08).

Conclusions:

This study shows that in patients with SIRS not admitted for infection, sP-selectin levels are significantly related to the subsequent development of infection. Furthermore, patients with higher sP-selectin levels in the first 2 days of admission had higher 30-day mortality, although this association is not statistically significant. Therefore, we conclude that sP-selectin is a potential future biomarker for both mortality and infection in patients with SIRS, but more research is needed to confirm its prognostic role.

Baseline thrombospondin-1 concentrations are not associated with mortality in septic patients: a single-center cohort study on the intensive care unit

Background

The initial phase of sepsis is characterized by hyperinflammation. Levels of thrombospondin-1 (TSP-1) rise rapidly during acute inflammation. The purpose of this clinical study was to study the association between plasma TSP-1 levels and mortality in patients with sepsis on the intensive care unit.

Methods

Critically ill adult patients with sepsis, severe sepsis, or septic shock were included. They were further divided into tertiles based on their baseline plasma TSP-1 concentrations. Primary outcome measure was 28-day mortality. Furthermore, associations with severity of sepsis and platelet counts were studied.

Results

Two hundred thirty-five patients were included. Median plasma TSP-1 concentrations of the tertiles were 194, 463 and 874 ng/mL, respectively. There were no baseline differences. Mortality rates (26.6, 16.7, and 16.7%, p = 0.20) and cumulative survival curves (p = 0.22) were not statistically different between the tertiles. There was no association of baseline TSP-1 with severity of sepsis (p = 0.08). TSP-1 and platelet counts were positively correlated (159, 198, and 295 × 10⁹/L, p = 0.04).

Conclusions

Baseline plasma levels of TSP-1 were not associated with mortality and severity of sepsis in mixed population of septic ICU patients. Further research is needed to clarify the expression of TSP-1 and to unravel the potential prognostic value of this biomarker in human sepsis.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0120-y) contains supplementary material, which is available to authorized users.

Strenuous exercise induces a hyperreactive rebalanced haemostatic state that is more pronounced in men

Physical exercise is recommended for a healthy lifestyle. Strenuous exercise, however, may trigger the haemostatic system, increasing the risk of vascular thrombotic events and the incidence of primary cardiac arrest. Our goal was to study the effects of strenuous exercise on risk factors of cardiovascular disease. Blood was collected from 92 healthy volunteers who participated in the amateur version of the pro-tour Amstel Gold cycling race, before and directly after the race. Thrombin generation showed a shortening of the lag time and time to peak and an increase of the velocity index. Interestingly, the endogenous thrombin potential measured in plasma decreased due to reduced prothrombin conversion. Platelet reactivity increased and this effect was stronger in men than in women. Lower fibrinogen and higher D-dimer levels after exercise indicated higher fibrin formation. On the other hand, fibrinolysis was also elevated as indicated by a shortening of the clot lysis time. Exercise activated the endothelium (von Willebrand factor (VWF) and active VWF levels were elevated) and the immune system (concentrations IL-6, IL-8, MCP-1, RANTES and PDGF increased). Additionally, an increased cardiac troponin T level was measured post-exercise. Strenuous exercise induces a temporary hyperreactive state in the body with enhanced pro- and anticoagulant responses. As strenuous exercise has a more pronounced effect on platelet function in male subjects, this gives a possible explanation for the higher incidence of sudden cardiac death during exercise compared to women. This trial is registered at www.clinicaltrials.gov as NCT02048462.

Decreased plasma levels of activated factor VII in patients with deep vein thrombosis

BACKGROUND

The initiating trigger in the development of deep vein thrombosis (DVT) remains unidentified. It has been suggested that tissue factor (TF)-bearing microparticles play a key role, which indicates a role for the TF pathway in the initiation of DVT.

OBJECTIVE

To assess the role of the TF pathway in the initiation of venous thrombosis, we measured plasma levels of factor VII and VIIa in patients with acute DVT and in controls.

METHODS

We included 148 patients diagnosed with acute DVT and 179 controls in this study. Antigen levels of FVII and FVIIa were measured by using assays recently developed in our laboratory.

RESULTS

Median FVII levels in patients were 109.8% (interquartile range [IQR] 86.0-153.2) compared with 102.2% (IQR 76.1-141.7) in controls. Individuals with FVII levels in the upper quartile had a 1.6-fold increased risk for the presence of a DVT (odds ratio 1.6, 95% confidence interval 0.8-3.1). Median FVIIa levels in patients were 50.2 ng mL(-1) (IQR 25.2-86.1) compared with 96.6 ng mL(-1) (69.9-168.9) in controls. Individuals with FVIIa levels in the lowest quartile had a > 5-fold increased risk for the presence of a DVT (odds ratio 5.5, 95% confidence interval 2.8-10.6). Both risks did not change substantially after adjustment for potential confounders.

CONCLUSION

Decreased plasma levels of FVIIa in patients with deep vein thrombosis may indicate ongoing consumption of FVIIa and suggest a contributory role for TF in venous thrombus formation.

Cirrhosis patients have a coagulopathy that is associated with decreased clot formation capacity

BACKGROUND

The coagulopathy in cirrhosis is associated with thrombosis and bleeding.

OBJECTIVES

To gain better insights into the coagulopathy in patients with cirrhosis, we evaluated plasma thrombin generation and whole blood clot formation in a cross-sectional study.

METHODS

Blood was collected from 73 patients with all-cause cirrhosis (Child-Pugh-A n = 52, B n = 15, C n = 6) and 20 healthy controls. Activity of the coagulation pathways was measured with assays for factor (F) VIIa and FIXa-antithrombin and FXa-antithrombin complexes, respectively. Thrombin generation by calibrated automated thrombography was determined in platelet-poor plasma using a 1 or 5 pm tissue factor trigger with/without thrombomodulin. ROTEM measurements were performed in whole blood triggered with 35 pm tissue factor without/with 175 ng mL(-1) tissue plasminogen activator (the latter refered to as 'tPA-ROTEM').

RESULTS

We observed an increased generation of FVIIa and a moderately elevated amount of FIXa (in complex with antithrombin) without apparent increase in FX activation in patients with cirrhosis. In accordance with this prothrombotic state, markers of thrombin generation potential were also increased upon increasing severity of cirrhosis. In the whole blood clotting assay we observed delayed clot formation and decreased clot strength associated with increased severity of cirrhosis. No significant differences were found for tPA-ROTEM parameters of clot degradation.

CONCLUSION

These results indicate that cirrhosis patients have an overall procoagulant plasma milieu but a decreased whole blood clot formation capacity with an apparently unaltered resistance to clot lysis.

The influence of Erythropoietin on platelet activation, thrombin generation and FVII/active FVII in patients with AMI

BACKGROUND

Erythropoietin (Epo) has been shown to improve myocardial function in models of experimental myocardial infarction, but has also been associated with a rise in thromboembolic events. Thus, the aim of this study was to investigate the influence of Epo on platelet activation and coagulation in patients with acute myocardial infarction (AMI).

METHODS

The study was designed as a substudy of the randomised, double-blind, placebo controlled REVIVAL-3 (REgeneration of VItal Myocardium in ST-Segment EleVation MyocardiAL Infarction by Erythropoietin) study that investigated the effects of recombinant human Epo in AMI. Serial venous blood samples were collected before and after study medication. Circulating prothrombin fragment F1 + 2, FVII, active FVII, beta thromboglobulin (TG) and P-Selectin were measured before and 60 hours after randomization by immunoassay (n = 94). In a randomly selected subgroup platelet aggregation was measured using whole blood aggregometry (Multiplate Analyzer, n = 45).

RESULTS

After 5 days an increase in FVII was observed after Epo as compared to placebo (P = 0.02), yet active FVII and prothrombin fragment F1 + 2 remained unchanged. Moreover, no statistically significant differences in circulating TG or P-selectin were observed between the groups. As an expected response to peri-interventional therapy with clopidogrel and aspirin, platelet aggregation after stimulation with ADP, TRAP, ASPI or collagen decreased 12 hours and 2 days after PCI. However, no difference between the Epo and the placebo group was observed.

CONCLUSION

After treatment with Epo in patients with AMI a slight increase in circulating FVII after Epo was not associated with an increase in active FVII, prothrombin fragment F1 + 2, TG or P-selectin. Moreover, platelet aggregation was not altered after treatment with Epo as compared to placebo.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01761435.

Active von Willebrand factor predicts 28-day mortality in patients with systemic inflammatory response syndrome

Endothelial dysfunction contributes to the pathology of systemic inflammatory response syndrome (SIRS). However, endothelial biomarkers are not routinely evaluated in this setting. Here, 275 patients with SIRS and plasma levels of von Willebrand factor (VWF), thrombospondin-1, myeloperoxidase, ADAMTS-13, and active VWF (aVWF) were studied in relation to 28-day mortality. On admission, aVWF levels were higher in nonsurvivors vs survivors (0.69 vs 0.47 µg/mL, P = .019). Patients in the highest tertile of aVWF levels had a lower cumulative survival (86% vs 75%, P = .017) and twofold increased hazard ratio (HR). When adjusted for the Acute Physiology and Chronic Health Evaluation IV (APACHE-IV) score, this difference remained significant (HR 1.82, 95% confidence interval, 1.03-3.3). On admission, no significant differences were measured for the other proteins. These observations suggest that the stimulated release of VWF is not predictive for mortality in patients with SIRS, opposite of the processing of VWF after release. aVWF could be used with the APACHE-IV score to stratify SIRS patients at high mortality risk.