BACKGROUND

Cervical cancer continues to be an important worldwide health problem for women. Up to 35% of patients who are diagnosed with and appropriately treated for cervical cancer will recur and treatment results are poor for recurrent disease. Given these sobering statistics, development of novel therapies for cervical cancer remains a high priority. We evaluated the expression of Tissue Factor (TF) in cervical cancer and the potential of hI-con1, an antibody-like-molecule targeted against TF, as a novel form of immunotherapy against multiple primary cervical carcinoma cell lines with squamous- and adenocarcinoma histology.

METHODS

Because TF is a transmembrane receptor for coagulation factor VII/VIIa (fVII), in this study we evaluated the in vitro expression of TF in cervical carcinoma cell lines by immunohistochemistry (IHC), real time-PCR (qRT-PCR) and flow cytometry. Sensitivity to hI-con1-dependent cell-mediated-cytotoxicity (IDCC) was evaluated in 5-hrs-51chromium-release-assays against cervical cancer cell lines in vitro.

RESULTS

Cytoplasmic and/or membrane TF expression was observed in 8 out of 8 (100%) of the tumor tissues tested by IHC and in 100% (11 out of 11) of the cervical carcinoma cell lines tested by real-time-PCR and flow cytometry but not in normal cervical keratinocytes (p=0.0023 qRT-PCR; p=0.0042 flow cytometry). All primary cervical cancer cell lines tested overexpressing TF, regardless of their histology, were highly sensitive to IDCC (mean killing±SD, 56.2%±15.9%, range, 32.4%-76.9%, p<0.001), while negligible cytotoxicity was seen in the absence of hI-con1 or in the presence of rituximab-control-antibody. Low doses of interleukin-2 further increased the cytotoxic effect induced by hI-con1 (p=0.025) while human serum did not significantly decrease IDCC against cervical cancer cell lines (p=0.597).

CONCLUSIONS

TF is highly expressed in squamous and adenocarcinoma of the uterine cervix. hI-con1 induces strong cytotoxicity against primary cervical cancer cell lines overexpressing TF and may represent a novel therapeutic agent for the treatment of cervical cancer refractory to standard treatment modalities.

BACKGROUND

Most epidemiological studies have found no association between levels of factor (F) VII:C and venous thromboembolism (VTE). Our Longitudinal Investigation of Thromboembolism Etiology (LITE) had, in contrast, reported an independent, increased risk of VTE after 7.8 years of follow-up for those with high baseline levels of FVII:C.

OBJECTIVE

To confirm whether FVII:C is associated with VTE after 12.6 years of follow-up and to examine whether two FVII gene polymorphisms (-670A/C and -402G/A) are related to VTE occurrence.

METHODS

In 19 091 LITE participants with no prior history of VTE or cancer, we measured FVII:C at baseline and identified 404 new VTEs. We also performed a nested case-control study to relate the polymorphisms to VTE (n = 490 without exclusion for cancer or prior VTE).

RESULTS

FVII:C was not independently associated with VTE occurrence after extended follow-up. Multivariable-adjusted rate ratios for VTE were 1.00, 1.00, 0.94, 1.00, and 1.38 (P-trend = 0.48) for the <25th, 25th-49th, 50th-74th, 75th-94th, and>>or=95th percentiles of FVII:C, respectively. The -670C and -402A alleles were in high linkage disequilibrium, and both were associated with greater FVII:C levels. However, neither polymorphism was associated with VTE occurrence.

CONCLUSIONS

After extended follow-up, LITE offers little evidence that a greater FVII level is a risk factor for VTE.

Previously we have determined that residues 88-109 (but not Arg(94)) in the second epidermal growth factor (EGF2)-like domain of factor IXa (FIXa) are important for assembly of the factor X (FX) activating complex on phospholipid vesicles (Wilkinson, F. H., London, F. S., and Walsh, P. N. (2002) J. Biol. Chem. 277, 5725-5733). Here we report that these residues are important for platelet binding affinity, stoichiometry, and assembly of the FX activating complex. We prepared several chimeric FIXa proteins using homologous sequences from factor VII (FVII): FIXa(FVIIEGF2) (FIX Delta 88-124,inverted Delta FVIIFVIIFVIIFVIIFVIIIa, respectively: FIXa(N) (0.55 +/- 0.06, 2.9 +/- 0.45), FIXa(WT) (0.80 +/- 0.08, 3.5 +/- 0.5), FIXa(loop1) (19 +/- 4.0, 27 +/- 5.0), FIXa(loop2) (35 +/- 9.0, 65 +/- 12.0), and FIXa(loop3) (1.1 +/- 0.09, 5.0 +/- 0.90). These K(d) values are in good agreement with K((d)(app)) values (in 10(-9) m) determined from the activation of FX (in the presence and absence of FVIIIa, respectively): FIXa(N) (0.46 +/- 0.05, 1.40 +/- 0.14), FIXa(WT) (0.72 +/- 0.08, 3.8 +/- 0.08), FIXa(loop1) (3.2 +/- 0.72, 14.0 +/- 1.60), FIXa(loop2) (18.4 +/- 1.60, 26.3 +/- 3.40), and FIXa(loop3) (0.7 +/- 0.05, 3.0 +/- 0.15). Moreover, the stoichiometry of binding (sites/platelet) showed an agreement with V(max) of FX activation and was reduced in those proteins that also showed a decreased platelet binding affinity. A peptide corresponding to the FIX EGF2 domain (Leu(84)-Val(128)) was an effective inhibitor of FIXa binding to platelets in both the presence (K(i) = 0.7 x 10(-6) m) and the absence (K(i) = 1.5 x 10(-6) m) of FVIIIa and FX. We conclude that residues 88-109 of the FIXa EGF2 domain mediate binding to platelets and assembly of the FX activating complex.ut not Ar

BACKGROUND

Platelet activation is crucial in normal hemostasis. Using a clotting system free of external tissue factor, we investigated whether activated Factor VII in combination with platelet agonists increased thrombin generation (TG) in vitro.

RESULTS

TG was quantified by time parameters: lag time (LT) and time to peak (TTP), and by amount of TG: peak of TG (PTG) and area under thrombin formation curve after 35 minutes (AUC-->35min) in plasma from 29 healthy volunteers using the calibrated automated thrombography (CAT) technique. TG parameters were measured at basal conditions and after platelet stimulation by sodium arachidonate (AA), ADP, and collagen (Col). In addition, the effects of recombinant activated FVII (rFVIIa) alone or combined with the other platelet agonists on TG parameters were investigated. We found that LT and TTP were significantly decreased (p < 0.05) and PTG and AUC-->35min were significantly increased (p < 0.05) in platelet rich plasma activated with AA, ADP, Col, and rFVIIa compared to non-activated platelet rich plasma from normal subjects (p = 0.01). Furthermore platelet rich plasma activated by the combined effects of rFVIIa plus AA, ADP or Col had significantly reduced LT and TTP and increased AUC-->35min (but not PTG) when compared to platelet rich plasma activated with agonists in the absence of rFVIIa.

CONCLUSIONS

Platelets activated by AA, ADP, Col or rFVIIa triggered TG. This effect was increased by combining rFVIIa with other agonists. Our intrinsic coagulation system produced a burst in TG independent of external tissue factor activity an apparent hemostatic effect with little thrombotic capacity. Thus we suggest a modification in the cell-based model of hemostasis.

BACKGROUND

Treatment with riboflavin and ultraviolet (UV) light reduces the pathogens present in blood components. This study assessed changes to the coagulation proteins that had occurred during this treatment of fresh plasma units before freezing.

METHODS

Twenty fresh plasma units (230 +/- 30 mL) were treated by the Mirasol process (CaridianBCT Biotechnologies) and frozen within 8 hours of donation. Plasma units were combined with 35 mL of a 500 micromol/L riboflavin solution in an illumination bag to achieve a final concentration of approximately 60 micromol/L riboflavin. The bag was placed in the Mirasol illuminator and exposed to UV light (6.24 J/mL). Samples were frozen before and after treatment.

RESULTS

Recoveries observed were 67.7 +/- 3.9% Factor (F)XI, 68.5 +/- 3.3% FVIII:C, 78.8 +/- 4.5% fibrinogen, 78.9 +/- 4.1% FV, 79.0 +/- 4.2% FVII, 79.0 +/- 8.6% F IX, 79.7 +/- 2.6% FX, and 85.0 +/- 3.7% FII. Von Willebrand factor (VWF) antigen, VWF:ristocetin cofactor, and ADAMTS13 recoveries were 87.0 +/- 7.1, 85.5 +/- 6.6, and 73.3 +/- 15.2%, respectively, while that of protein C was 83.6 +/- 2.6%. A loss of high-molecular-weight VWF multimers was observed in most units. Recoveries for protein S, antithrombin, and plasmin inhibitor were greater than 90%. The mean FVIII:C concentration, after treatment, was 0.76 +/- 0.17 IU/mL.

CONCLUSIONS

As with other pathogen reduction technologies, the Mirasol process resulted in some loss of coagulation factor activity. For most Mirasol-treated units and for most of the tested factors this is unlikely to have clinical impact, but trials are required to demonstrate this.

Tissue factor (TF) serving as the receptor for coagulation factor VII (FVII) initiates the extrinsic coagulation pathway. We previously demonstrated that progesterone increases TF, coagulation and invasion in breast cancer cell lines. Herein, we investigated if tissue factor pathway inhibitor (TFPI) could down-regulate progesterone-increased TF activity in these cells. Classically, TFPI redistributes TF-FVII-FX-TFPI in an inactive quaternary complex to membrane associated lipid raft regions. Herein, we demonstrate that TF increased by progesterone is localized to the heavy membrane fraction, despite progesterone-increased coagulation originating almost exclusively from lipid raft domains, where TF levels are extremely low. The progesterone increase in coagulation is not a rapid effect, but is progesterone receptor (PR) dependent and requires protein synthesis. Although a partial relocalization of TF occurs, TFPI does not require the redistribution to lipid rafts to inhibit coagulation or invasion. Inhibition by TFPI and anti-TF antibodies in lipid raft membrane fractions confirmed the dependence on TF for progesterone-mediated coagulation. Through the use of pathway inhibitors, we further demonstrate that the TF up-regulated by progesterone is not coupled to the progesterone increase in TF-mediated coagulation. However, the progesterone up-regulated TF protein may be involved in progesterone-mediated breast cancer cell invasion, which TFPI also inhibits.

Preliminary observations have suggested that non-fasting factor VII coagulant activity (FVII:C) may be related to the dietary fat content. To confirm this, we performed a randomised cross-over study. Seventeen young volunteers were served 2 controlled isoenergetic diets differing in fat content (20% or 50% of energy). The 2 diets were served on 2 consecutive days. Blood samples were collected at 8.00 h, 16.30 h and 19.30 h, and analysed for triglycerides, FVII coagulant activity using human (FVII:C) or bovine thromboplastin (FVII:Bt), and FVII amidolytic activity (FVII:Am). The ratio FVII:Bt/FVII:Am (a measure of FVII activation) increased from fasting levels on both diets, but most markedly on the high-fat diet. In contrast, FVII:Am (a measure of FVII protein) tended to decrease from fasting levels on both diets. FVII:C rose from fasting levels on the high-fat diet, but not on the low-fat diet. The findings suggest that high-fat diets increase non-fasting FVII:C, and consequently may be associated with increased risk of thrombosis.

The association between the R353Q and -323P0/10 (10-bp insertion in the promoter region at position -323) factor VII mutations and plasma factor VII levels was investigated in a group of 214 healthy Tunisians. The frequency for the Q allele was 0.253 and that for the 10-bp allele was 0.206, and their distribution was variable, with a high prevalence of the 10-bp allele (0.306) seen in North Tunisia and a high prevalence of the Q allele (0.288) see in the Sahel region. No significant linkage disequilibrium was observed between the two mutations, and the most prevalent haplotype was -323P0/353R (0.589 +/- 0.054). Carriers of the R353Q (P < 0.001), but not -323P0/10 (P = 0.088), factor VII mutations had lower mean factor VII serum concentrations. This reduction in mean serum factor VII was more pronounced among homozygous (Q/Q) carriers and among males (49.9%) compared to females (32.7%). Adjusting for all other variables in the linear regression analysis (sex, age, region, smoking, and R353Q and -323P0/10 mutations), heterozygous carriers of the -323P0/10 and R353Q mutation had on average reductions of 10 units (P = 0.005) and 30 units (P < 0.001) in plasma factor VII, respectively, compared to noncarriers, while homozygote carriers of the R353Q (-43.3, P < 0.001), but not carriers of the -323P0/10 (-6.30, P = 0.356), had significantly lower levels of mean plasma factor VII. These data suggest that part of the previously described effects on FVIIc levels associated with the R/Q polymorphism may be explained by genetic variation in the promoter region of the FVII gene.

BACKGROUND

We have previously demonstrated that Lactobacillus casei CRL 431 administration improved the resistance to pneumococcal infection in a mouse model.

METHODS

This study examined the effects of the oral administration of Lactobacillus casei CRL 431 (L. casei) on the activation of coagulation and fibrinolytic systems as well as their inhibitors during a Streptococcus pneumoniae infection in mice.

RESULTS

The alveolo-capillary membrane was damaged and the coagulation system was also activated by the infection. As a consequence, we could see fibrin(ogen) deposits in lung histological slices, increased levels of thrombin-antithrombin complex (TATc) in bronchoalveolar lavage (BAL) and plasma, decrease in prothrombin activity (PT) and prolonged activated partial thromboplastin time test (APTT) values. Factor VII (FVII) and factor X (FX) were decreased in plasma, whereas fibrinogen (F) and factor VIII (FVIII) were increased. The low levels of protein C (PC) in BAL and plasma proved damage on inhibitory activity. The infected animals showed reduced fibrinolytic activity, evidenced by an increase in plasminogen activation inhibitor-1 (PAI-1) in BAL and plasma. The pathogen induced an increase of TNF-alpha, IL-1beta and IL-6 in BAL and serum a few hours after challenge followed by a significant decrease until the end of the assayed period. IL-4 and IL-10 in BAL and serum were also augmented, especially at the end of the experiment. The animals treated with L. casei showed an improvement of alveolo-capillary membrane, lower fibrin(ogen) deposits in lung and decrease in TATc. APTT test and PT, FVII and FX activity were normalized. L. casei group showed lower F levels than control during whole experiment. In the present study no effect of L. casei on the recovery of the inhibitory activity was detected. However, L. casei was effective in reducing PAI-1 levels in BAL and in increasing anti-inflammatory ILs concentration.

CONCLUSIONS

L. casei proved effective to regulate coagulation activation and fibrinolysis inhibition during infection, leading to a decrease in fibrin deposits in lung. This protective effect of L. casei would be mediated by the induction of higher levels of IL-4 and IL-10 which could regulate the anti-inflammatory, procoagulant and antifibrinolytic effects of TNF-alpha, IL-1beta and IL-6.

Type 2 diabetes mellitus is frequently accompanied by hypercoagulability and hypofibrinolysis. Both are related to increased cardiovascular risk, but possibly with endothelial injury as well. Studies with nondiabetic persons indicate that unopposed oestrogen replacement therapy (oERT) decreases cardiovascular risk, possibly mediated in part by effects on coagulation and fibrinolysis. In a double-blind, randomised placebo-controlled trial, we assessed the effect of oral 17 beta-oestradiol daily during 6 weeks on indicators of coagulation and of fibrinolysis in postmenopausal women with type 2 diabetes mellitus. We observed significant increases of Factor VII (FVII) and von Willebrand factor (vWF) after oERT and no change in the already high fibrinogen. Prothrombin fragment 1 + 2 (F1 + 2) increased after oERT, whereas thrombin-antithrombin (TAT) complexes was unchanged, but increments of F1 + 2 and TAT correlated. Soluble fibrin (SF) levels remained stable. In fibrinolysis, a clear reduction in plasminogen activator inhibitor 1 (PAI-1) was observed, but no significant change in tissue-type plasminogen activator antigen (t-PA-Ag) or activity was found, although fibrinolytic activity assessed as t-PA activity (t-PA-Act) tended to increase after oERT. Indicators of fibrinolytic activity (plasmin-antiplasmin complexes and fibrin degradation products) however did not change. oERT increased C-reactive protein (CRP) but none of the coagulation or fibrinolysis changes significantly associated with the CRP changes. It is concluded that oERT increases the coagulation potency as well as the fibrinolytic potency raising the question of the net effect in their balance. Increase in F1 + 2 suggests that in diabetic women oERT effectively increases the chronic, continuous activation of coagulation, which appears to be compensated for or not effective in the blood compartment as judged from the unchanged levels of SF. Suspected increased fibrin formation in the vascular wall is at least not followed by increases in fibrinogen degradation products (TDP), which suggests the possibility of accumulation and increased cardiovascular risk. The results indicate that specific attention should be paid to fibrin turnover in studying other categories of women and the effects of the addition of progesterone.

BACKGROUND

The R353Q genotype is a major determinant of factor VII coagulant (FVIIc) activity, which is associated with an increased risk of ischemic heart disease (IHD) and elevated plasma triacylglycerol concentrations.

OBJECTIVE

The objectives were to 1) compare the effects of meals rich in palmitate or oleate with those of a meal low in fat on FVIIc in subjects with moderately elevated plasma nonfasting triacylglycerol concentrations and 2) determine whether the postprandial increase in FVIIc induced by dietary oleate differs in carriers of the Q allele.

METHODS

Fifty-two men aged >52 y with nonfasting plasma triacylglycerol concentrations between 2 and 5.5 mmol/L were randomly assigned to receive isoenergetic (5.1 MJ) meals providing 50 g high-oleate or high-palmitate oils or a low-fat meal providing 15 g high-oleate oil. In a second study, 17 men aged >52 y who were heterozygous for factor VII R353Q polymorphism were age-matched with subjects homozygous for the R allele and their responses to a 50-g, high-oleate meal were measured.

RESULTS

FVIIc decreased by 11% after the low-fat meal. FVIIc increased by 9% and FVIIa (the activated form of FVII) increased by 55% after the high-oleate meal, whereas FVIIc did not change but FVIIa increased by 25% after the high-palmitate meal. Fasting FVIIc and FVIIa concentrations were 24% and 48% lower, respectively, in men with the RQ genotype than in men with the RR genotype but increased postprandially in both groups with no evidence of a genotype interaction.

CONCLUSIONS

A high-fat meal rich in oleate increases FVIIa, whereas a low-fat meal does not, in men at high risk of IHD, independent of R353Q genotype.

Blood coagulation comprises a complex cellular and molecular mechanism that maintains vascular integrity, protects against bleeding (hemostasis) and responds to injury. However, several elements of the coagulation system, including several coagulation factors and platelets, are also involved in other physiological and pathological processes. Tissue factor (TF) is a cell surface glycoprotein expressed in a vast variety of cell types and essential for hemostasis. Upon exposure of the TF-rich subendothelium to the blood stream, Factor VII (FVII) can bind to TF. TF subsequently facilitates the activation of FVII into activated FVII (FVIIa) thereby initiating the extrinsic coagulation pathway followed by the activation of FX and thrombin formation. Besides its hemostatic role in the vasculature, the TF:FVIIa pathway is active in many other compartments and organs where it can take part and mediate different physiological and pathological processes. The so-called non-hemostatic functions of TF:VIIa play a role in diverse processes such as inflammation, atherosclerosis and vascular and cardiac remodeling. This narrative review aims to reassess the most important and recent findings regarding the complex signaling pathways initiated by the TF:FVIIa complex, with an emphasis on the heart and blood vessels. Understanding how the mechanisms of TF:FVIIa signaling contribute to both physiological and pathological processes, is one of the keys to the development of new treatment strategies in cardiovascular disease.

BACKGROUND

Although there is no direct evidence, it is generally believed that bed rest shifts the haemostatic system towards hypercoagulability; thus, immobilized patients are commonly treated with anticoagulants. We therefore aimed to investigate whether long-term bed rest actually leads to an elevated risk for thromboembolic events.

METHODS

Eleven healthy men were enrolled in our study (bed rest campaign in MEDES Clinique d'Investigation, Toulouse, France). Besides various standard laboratory methods, we used calibrated automated thrombography (CAT) and thrombelastometry (TEM). Activation of samples with minute amounts of relipidated tissue factor allowed sensitive detection of hyper- or hypocoagulable states.

RESULTS

CAT and TEM values were not indicative of bed rest-induced hypercoagulability. On the contrary, several parameters were indicative of a tendency towards a hypocoagulable state. Peak and thrombin formation velocity (VELINDEX) were significantly decreased during bed rest compared to baseline. Coagulation times were significantly increased and alpha angles were significantly decreased, indicating attenuated clot formation. Moreover, F1 + 2 and thrombin/antithrombin complex (TAT) values were significantly decreased during bed rest, indicating suppressed coagulation activation. FVII plasma levels were also significantly decreased during the first week of bed rest.

CONCLUSIONS

Our data indicate that the re-ambulation period is associated with a tendency towards hypercoagulability: ttPeak and StartTail were significantly shorter, Peak and VELINDEX were significantly higher compared to baseline. Moreover, plasma levels of F1 + 2, TAT, FVII and FVIII were significantly higher compared to baseline. The results from our study suggest that bed rest by itself is not associated with hypercoagulable states in healthy subjects.

Some epidemiological observations indicate that 1 to 2 weekly servings of fish prevent ischemic heart disease (IHD). This might be explained by an effect of the very-long-chain n-3 polyunsaturated fatty acids (n-3 VLCPUFA) of fish oil on lipid metabolism and/or the hemostatic system, both involved in IHD development. We studied the effect of incorporating natural fish oil (4 g daily equivalent to 0.91 g n-3 VLCPUFA and corresponding to one to two weekly servings of fatty fish) into the diet in a 4-week parallel, randomized, and double-blind trial of 47 healthy males aged 29 to 60 years. Sunflower oil was used as placebo. The fish oil had no significant effect on plasma lipids, apolipoproteins, lipoprotein(a), blood coagulation FVII, fibrinogen, endogenous fibrinolysis, beta-thromboglobulin, von Willebrand factor, glucose, or insulin in fasting blood samples. In nonfasting samples (n = 19), fish oil was associated with an approximately 30% decline in plasma triglycerides (P < .02) and a 9% decline in FVII protein (P < .05), whereas FVII coagulant activity and fibrinolysis were unaffected. In conclusion, our findings indicate that lowering of postprandial triglycerides is the only n-3 VLCPUFA effect that could contribute to primary prevention of IHD in healthy middle-aged men as assessed by currently measurable lipid and hemostatic risk markers.

All but essential surgery is generally avoided in haemophilia patients with inhibitor antibodies, because of concern about the reliability with which haemostasis can be achieved and maintained in such patients. Orthopaedic surgical procedures which are not required to preserve life fall under this category. As a result, patients with inhibitors may be denied operations, which could greatly enhance their quality of life, and which are routinely offered to other haemophilia patients. While caution is appropriate in recommending surgery in any circumstance, we believe that the threshold for offering validated surgical procedures to patients with inhibitors should be re-evaluated in the light of current surgical and rehabilitative techniques, and the long experience with safe and effective factor VIII inhibitor bypassing agents, namely activated prothrombin complex concentrates and recombinant activated factor FVII. In this article, we review the haematological, surgical and rehabilitative considerations relevant to orthopaedic surgery in haemophilia patients with inhibitors, and provide recommendations for carrying out such procedures.

Essentials The activated partial prothrombin time (aPTT) cannot predict the activity of emicizumab (Emi). Adjusted clot waveform analyses using a prothrombin time (PT)/aPTT initiator were developed. Activity of Emi in the co-presence of factor VIII or bypassing agents was quantified. This assay is useful for assessing coagulation potential in Emi-treated hemophilia A.

CONCLUSIONS

Background Emicizumab is an anti-activated factor IX/FX bispecific antibody that mimics activated FVIII cofactor function. Emicizumab does not require activation by thrombin, and its effect on shortening the activated partial thromboplastin time (APTT) is much greater than that of FVIII. Therefore, the APTT has limited utility in hemophilia A (HA) patients treated with emicizumab. Aim To evaluate the global coagulation potential of emicizumab. Methods Clot waveform analysis (CWA) with prothrombin time (PT)/APTT mixed reagents was used to define hemostatic monitoring protocols in HA patients. A modified parameter, adjusted-|min1| (Ad|min1|), was developed. Maximum and minimum percentage transmittance were defined as 100% and 0% in the precoagulation and postcoagulation phases, respectively. Ad|min1| was calculated as an index of the maximum velocity of the coagulation process. Results Ad|min1| obtained with mixed-trigger reagent (PT/APTT/buffer, 1 : 15 : 135) in the presence of emicizumab optimally corresponded to the conversion rate estimated in animals; 0.2-0.4 IU dL-1 equivalent FVIII per 1 μg mL-1 emicizumab). Ex vivo addition of emicizumab to HA plasma with or without inhibitors resulted in concentration-dependent increases in Ad|min1|, with some individual variations. The addition of various concentrations of FVIII to HA plasma mixed with emicizumab resulted in dose-dependent increases in Ad|min1|. Similarly, mixtures of activated prothrombin complex concentrate and emicizumab added to HA plasma resulted in dose-dependent increases in Ad|min1|. In contrast, enhanced coagulation potential appeared to be better defined by the clot time than by Ad|min1| in experiments using recombinant activated FVII. Conclusion The PT/APTT reagent-triggered adjusted CWA could provide a useful means of assessing global coagulation potential in emicizumab-treated HA patients, with enhanced activity neither masking nor being masked by FVIII or bypassing agents.

Recombinant activated human factor VII (rhFVIIa) is an established hemostatic agent in hemophilia, but its mechanism of action remains unclear. Although tissue factor (TF) is its natural receptor, rhFVIIa also interacts with the endothelial protein C receptor (EPCR) through its γ-carboxyglutamic acid (Gla) domain, with unknown hemostatic consequences in vivo. Here, we study whether EPCR facilitates rhFVIIa hemostasis in hemophilia using a mouse model system. Mouse activated FVII (mFVIIa) is functionally homologous to rhFVIIa, but binds poorly to mouse EPCR (mEPCR). We modified mFVIIa to gain mEPCR binding using 3 amino acid changes in its Gla domain (L4F/L8M/W9R). The resulting molecule mFVIIa-FMR specifically bound mEPCR in vitro and in vivo and was identical to mFVIIa with respect to TF affinity and procoagulant functions. In macrovascular injury models, hemophilic mice administered mFVIIa-FMR exhibited superior hemostatic activity compared with mFVIIa. This was abolished by blocking mEPCR and was absent in ex vivo whole blood coagulation assays, implicating a specific mFVIIa-FMR and endothelial mEPCR interaction. Because mFVIIa-FMR models the TF-dependent and EPCR binding properties of rhFVIIa, our data unmask a novel contribution of EPCR on the action of rhFVIIa administration in hemophilia, prompting the rational design of improved and safer rhFVIIa therapeutics.

Intermittent pneumatic compression (IPC) devices are an effective prophylaxis against lower extremity deep vein thrombosis. Their antithrombotic effect has been attributed to a reduction in venous stasis and enhanced fibrinolysis. The initiating mechanism for blood coagulation is the tissue factor (TF) dependent pathway, which is inhibited by tissue factor pathway inhibitor (TFPI). We have investigated the effect of IPC on the TF pathway in 6 normal subjects and 6 patients with postthrombotic venous disease undergoing IPC for 120 minutes; all subjects were studied with each of 5 IPC devices. In normal subjects and patients, plasma factor VIIa (FVIIa) activity (the activated form of factor VII [FVII]) declined from mean values ranging 51 to 65 and 50 to 53 mU/mL before IPC with different devices to 10 to 13 and 20 to 22 mU/mL at 180 minutes, respectively (P<0.001 for all groups). FVII antigen levels were unchanged. Plasma TFPI (P<0.001) rose from mean baseline values ranging 69 to 79 and 57 to 61 ng/mL to 76 to 123 and 71 to 79 ng/mL at 180 minutes in normal subjects and patients, respectively (P<0. 001 for all groups). Plasma prothrombin fragment F1.2 levels showed minimal changes. There was an inverse relationship between TFPI and FVIIa in normal subjects (r=-0.31, P=0.001) and patients (r=-0.37, P<0.001). IPC results in an increase in plasma TFPI and decline in FVIIa. Inhibition of TF pathway, the initiating mechanism of blood coagulation, is a possible mechanism for the antithrombotic effect of IPC.

Glanzmann thrombasthenia (GT) is a rare platelet function disorder characterized by a defect in fibrinogen binding to platelet membrane glycoprotein (GP) IIb/IIIa. Recombinant FVIIa (rFVIIa) is a haemostatic agent approved for the treatment of haemophilia patients with inhibitors, patients with acquired haemophilia and in EU also for treatment of factor VII (FVII)-deficient patients and GT patients with antibodies to GPIIb-IIIa. The present study was conducted to evaluate the use of the whole blood test system, rotational thrombelastometry (ROTEM), in measuring the overall haemostasis potential of rFVIIa in 28 GT patients treated with rFVIIa. The correlation of administered rFVIIa and time to start fibrin formation and clot dynamic/stability was assessed and correlation to the clinical response was elucidated. Assessments were performed on predose blood samples spiked with four different concentrations of rFVIIa and whole blood samples taken at 10 and 120 min following dosing. ROTEM parameters clotting time (CT), clot formation time (CFT) and maximum clot firmness (MCF) were measured. Both ex vivo and in vivo data showed beneficial effects on CT in the presence of rFVIIa, but no effect of added rFVIIa was seen on CFT and MCF. In conclusion, the use of thrombelastography at least in the modified form of ROTEM seems to be of limited use in predicting an adequate dose of rFVIIa in GT patients. A good clinical haemostatic response was recorded in spite of the limited changes in the ROTEM pattern supporting the conclusion that ROTEM should not be the method of choice for monitoring rFVIIa therapy in Glanzmann patients.

BACKGROUND

Coagulopathy has a high prevalence in critically ill patients. An increased International Normalized Ratio (INR) is a common trigger to transfuse fresh frozen plasma (FFP), even in the absence of bleeding. Therefore, FFP is frequently administered to these patients. However, the efficacy of FFP in correcting hemostatic disorders in non-bleeding recipients has been questioned.

OBJECTIVE

To assess whether INR prolongation parallels changes in the results of other tests investigating hemostasis, and to evaluate the coagulant effects of a fixed dose of FFP in non-bleeding critically ill patients with a coagulopathy.

METHODS

Markers of coagulation, individual factor levels and levels of natural anticoagulants were measured. Also, thrombin generation and thromboelastometry (ROTEM) assays were performed before and after FFP transfusion (12 mL kg(-1) ) to 38 non-bleeding critically ill patients with an increased INR (1.5-3.0).

RESULTS

At baseline, levels of factor II, FV, FVII, protein C, protein S and antithrombin were reduced, and thrombin generation was impaired. ROTEM variables were within reference ranges, except for a prolonged INTEM clot formation time. FFP transfusion increased the levels of coagulation factors (FII, 34% [interquartile range (IQR) 26-46] before vs. 44% [IQR 38-52] after; FV, 48% [IQR 28-76] before vs. 58% [IQR 44-90] after; and FVII, 25% [IQR 16-38] before vs. 37% [IQR 28-55] after), and the levels of anticoagulant proteins. Thrombin generation was unaffected by FFP transfusion (endogenous thrombin potential, 72% [IQR 51-88] before vs. 71% [IQR 42-89] after), whereas ROTEM EXTEM clotting time and maximum clot firmness slightly improved in response to FFP.

CONCLUSIONS

In non-bleeding critically ill patients with a coagulopathy, FFP transfusion failed to induce a more procoagulant state.

Human coagulation factor VII (FVII) has two N-glycosylation sites (N145 and N322) and two O-glycosylation sites (S52 and S60). In transiently transfected COS-7 cells, all combinations of N- and O-glycosylation knock-out mutations reduced the release of FVII to the medium. Pulse-chase analysis of CHO-K1 cell lines expressing recombinant FVII demonstrated that virtually all wild-type FVII synthesized was secreted from the cells, whereas both N- and O-glycosylation knock-out mutations induced partial intracellular degradation of the synthesized FVII. Likewise, two thirds of the FVII synthesized in vitamin K-depleted and warfarin-treated CHO cells was degraded intracellularly, demonstrating the importance of gamma-carboxylation for the secretion of FVII. The furin inhibitor decanoyl-R-V-K-R-chloromethylketone inhibited propeptide cleavage, but FVII with propeptide appeared to be secreted equally well as FVII without propeptide. Propeptide cleavage was not inhibited by vitamin K depletion and warfarin treatment, suggesting that for FVII, correct gamma-carboxylation is not required for optimal processing of the propeptide. In conclusion, all post-translational modifications of FVII except propeptide cleavage were important for complete secretion of the synthesized FVII and to avoid intracellular degradation. Thus, the extensive post-translational modification of FVII seems critical for the intracellular stability of the protein and is required for keeping the protein in the secretory pathway.

The relationship between extrinsic coagulation factors, tissue factor pathway inhibitor (TFPI) and activated factor XII (FXIIa) was examined in 71 patients with end-stage chronic renal failure. They had chronic stable uremia due to regular hemodialysis. The patients were divided into two age- and sex-matched groups with and without diabetes mellitus. As extrinsic coagulation parameters, FVIIa and FVII antigen (FVIIag), tissue factor antigen and TFPI (the activity and antigen) were measured. FXIIa was measured as a marker of contact activation, and thrombin generation was evaluated using the two markers thrombin-antithrombin III complex and prothrombin fragment 1 + 2. In both hemodialysis groups with and without diabetes, significant elevations of FXIIa, FVIIa and tissue factor, with high levels of TFPI, were found. Thus, hyperactivation of the coagulation system was in part compensated by TFPI, and a significant increase in FXIIa could not directly affect FVIIa hyperactivation. No differences of these parameters, except for FVIIag and fragment 1 + 2, were found between the groups with and without diabetes. It is suggested that the long-term hemodialysis might have masked any differences due to the underlying disease in these two subgroups.

The relative importance of vessel wall tissue factor (TF) in initiating thrombogenesis is not well defined. In contrast, vessel wall collagens have been well documented as potent inducers of thrombus formation. We compared the potency of a human TF/phospholipid surface with that of a surface consisting of human type III collagen fibrils in triggering thrombus formation in native human blood at venous and arterial blood flow conditions. A commercial preparation, Thromborel S, was used as a source of human TF. Biochemical characterization of this preparation revealed small amounts of FVII, FIX, and FX proteins. Coagulant activity of these proteins was associated with the FVII protein only, although it was a very low activity. Studies with anti-TF antibodies in a one-stage clotting assay showed that the procoagulant activity of Thromborel was mainly a result of TF. The molar ratio of TF to phospholipid was 1:2 x 10(7). Thrombus formation in flowing nonanticoagulated human blood drawn directly from an antecubital vein was triggered by either Thromborel S or collagen fibrils coated on Thermanox coverslips in a parallel-plate perfusion chamber device. A 1:50 Thromborel S dilution gave maximal fibrin deposition (90% surface coverage) at a wall shear rate of 100 s-1. However, pretreatment of the TF surface with a monoclonal anti-TF antibody reduced this fibrin deposition by 93% (P < .001). Thus, TF was essential for the procoagulant activity of the Thromborel S surface in this flow system also. At higher wall shear rates (650 and 2600s-1), less fibrin was deposited, but the platelet thrombus formation on the fibrin mesh increased dramatically.(ABSTRACT TRUNCATED AT 250 WORDS)

To achieve the great potential of siRNA based gene therapy, safe and efficient systemic delivery in vivo is essential. Here we report reductively responsive hydrogel nanoparticles with highly uniform size and shape for systemic siRNA delivery in vivo. "Blank" hydrogel nanoparticles with high aspect ratio were prepared using continuous particle fabrication based on PRINT (particle replication in nonwetting templates). Subsequently, siRNA was conjugated to "blank" nanoparticles via a disulfide linker with a high loading ratio of up to 18 wt %, followed by surface modification to enhance transfection. This fabrication process could be easily scaled up to prepare large quantity of hydrogel nanoparticles. By controlling hydrogel composition, surface modification, and siRNA loading ratio, siRNA conjugated nanoparticles were highly tunable to achieve high transfection efficiency in vitro. FVII-siRNA conjugated nanoparticles were further stabilized with surface coating for in vivo siRNA delivery to liver hepatocytes, and successful gene silencing was demonstrated at both mRNA and protein levels.