Different Tissue Plasminogen Activator Release in the Arm and Leg during Venous Occlusion Is Equalized after DDAVP Infusion

The mechanism of tissue plasminogen activator (t-PA) release during arm and leg venous occlusions and DDAVP (1 desamino- 8-D-arginine vasopressin) infusion was studied in 10 healthy males. The following determinations were carried out on venous blood: t-PA antigen (ELISA), t-PA activity, and t-PA inhibitor (PAI) activity (amidolytic assays). Before DDAVP, there was a 270% t-PA antigen increase in the arm at the end of occlusion as opposed to only a 40% increase in the leg. After DDAVP, t-PA antigen at the end of arm and leg occlusion reached an equal level which was significantly higher than in the arm before DDAVP. The study produced no evidence of PAI release during venous occlusion of a limb. It is concluded that DDAVP is able to elicit t-PA release from arm as well as from leg vessels. The poor fibrinolytic response of leg vessels to venous occlusion is not due to a high PAT release or t-PA stores depletion in leg vessels, but rather to low basal t-PA release in leg vessels.

Physical Exercise Induces Enhancement of Urokinase-Type Plasminogen Activator (u-PA) Levels in Plasma

The enhancement of the blood fibrinolytic potential by physical exercise is generally attributed to the release of tissue-type plasminogen activator (t-PA) from the vessel wall. In this study we have investigated the possible contribution of urokinase-type plasminogen activator (u-PA).

Six healthy male volunteers (age 21–25 years) were screened for their ability to perform maximal exercise for their age-group for 12 min on a bicycle ergometer. Subsequently, on one occasion they were required to remain supine for 2 h (from 8.30 a. m. onwards) and on another they performed maximal exercise (from 9.00 a.m. onwards). During exercise an increase in u-PA antigen and plasmin-activatable pro-urokinase (proUK) activity, concurrent with t-PA antigen and euglobulin t-PA activity, was observed in all six volunteers, while at rest these parameters remained unaffected. Mean u-PA- and t-PA antigen increased, respectively, from 4.2 ± 1.0 ng/ml and 5.8 ± 2.1 ng/ml before exercise to 9.8 ± 3.0 ng/ml and 18.3 ± 3.8 ng/ml (peak). Mean plasminactivatable proUK activity and t-PA activity increased, respectively, from 2.1 ± 0.4 ng/ml and 0.3 ± 0.2 ng/ml before exercise to 4.3 ± 1.7 ng/ml and 7.2 ± 4.0 ng/ml (peak). The increases were statistically significant throughout (paired t-test, pre vs post, antigen P <0.005 and activity P <0.02). After cessation of exercise u-PA and t-PA declined concurrently to normal values with a 50"/" decay in about 5 min. In conclusion, we found that both u-PA antigen and plasmin-activatable proUK activity are, concurrently with t-PA, enhanced upon exercise and, therefore, we consider that u-PA also contributes to – and co-operates in – the enhancement of the blood fibrinolytic potential and activity under these conditions.

Modified Crossed Immunoelectrophoresis to Study with Whole Plasma the Reversible Complex Formation of Histidine-Rich Glycoprotein with Plasminogen

To study the reversible complex formation between the plasma protein histidine-rich glycoprotein (HRG) and plasminogen, crossed immunoelectrophoresis of HRG was modified. In the modification, purified plasminogen was introduced into the gel of the first dimension electrophoresis.

Two molecular forms of plasminogen, Glu- and Lys-plasmino-gen, induced a dose-dependent reduction of the electrophoretic mobility of HRG, with a half maximal retardation for both plasminogens at 0.50–0.55 μM of added plasminogen to the agarose gel. HRG in plasma behaved as a uniform fraction with respect to plasminogen binding. In contrast, with the same modified technique another plasma protein, β2-antiplasmin, separated into a retarded plasminogen-binding form and a nonretarded non-plasminogen-binding form.

The method can be used to assess several aspects of reversible complex formation between plasma proteins, as demonstrated for plasminogen binding of HRG and α2-antiplasmin in whole plasma.

Effects of Moderate Alcohol Consumption on Platelet Function, Tissue-Type Plasminogen Activator and Plasminogen Activator Inhibitor

Short-term effects of moderate alcohol consumption on platelet function, tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) were studied in two age groups of volunteers (20–30 and 45–55 years), each consisting of eight healthy males. The alcohol (30 g in red port and wine) was consumed during a standard dinner. Two blood samples were drawn: one in the postprandial phase, and one the next morning after fasting overnight. Alcohol consumption tended to increase platelet aggregation and production of hydroxy fatty acids, reduced plasma t-PA activity and increased PAI activity in the postprandial phase. After the overnight fast the effects on t-PA and PAI had disappeared whereas at that time alcohol consumption tended to decrease platelet function. The effects of alcohol on t-PA and PAI activity appeared mainly in the older age group, whereas the t-PA activity in this group was already much lower, irrespective of alcohol consumption.

Quantitation of Plasma Levels of Tetranectin - Effects of Oral Contraceptives, Pregnancy, Treatment with L-Asparaginase and Liver Cirrhosis

Tetranectin is a tetrameric protein that binds to kringle 4 of plasminogen. Increase of electrophoretic mobility of the otherwise slowly migrating tetranectin in the presence of ethylenediaminetetraacetate was used to develop a reproducible electroimmunoassay to quantify plasma levels. Plasma levels in normals were found within narrow limits of 100 ± 16 (SD)%, (100% =0.15 pmol/1). There was no difference between males and females, smokers and non-smokers, and there were no significant changes with age from 20 to 49 years.

Patients with severe liver cirrhosis showed a large variation in plasma tetranectin levels but no systematic or average reduction, in contrast to strong reductions in plasma levels of other proteins. Patients treated with L-asparaginase showed a gradual reduction in time in plasma levels of various proteins, though tetranectin showed no significant reduction.

It is concluded that tetranectin can be assayed reproducibly in plasma and has a well regulated plasma level. This level is not sensitive to conditions with reductions in synthesis of many proteins, such as during cirrhosis of the liver and during L-asparaginase therapy. The reductions in plasma levels during the use of oral contraceptives and pregnancy indicate involvement of sex steroids in the metabolism of tetranectin.

Elevated Plasminogen Activator Inhibitor (PAI), a Cause of Thrombophilia? – A Study in 203 Patients with Familial or Sporadic Venous Thrombophilia

Two hundred and three patients with venous thrombophilia were investigated in order to find out whether an elevated plasma concentration of plasminogen activator inhibitor (PAI) could be a cause of their tendency to thrombosis. The patients were studied in an asymptomatic period about 3 months after their last thromboembolic episode. PAI activity was found to be elevated in 19 patients (9%), and a corresponding elevation of PAI-1 antigen was observed.

In 16 out of the 19 patients with elevated PAI activity, followup could be performed after an additional asymptomatic period of about 1 year: in eight patients the elevation of PAI was transient and in eight it was persistent. Out of the eight patients with a persistent elevation of PAI, seven had a positive family history of thrombosis. Investigation of these families excluded a hereditary elevation of PAI activity in two families. In only two other families was elevated PAI activity also found among family members. The occurrence of elevated PAI activity, however, did not coincide with the occurrence of thrombosis in these individuals: except for the probands, all investigated family members who had a history of thrombosis had a normal PAI activity.

We therefore conclude that, at least in our material, familial thrombophilia can not be attributed to an inherited, persistent elevation of the blood level of PAI.

Influence of Factor Xllla Activity on Human Whole Blood Clot Lysis In Vitro

We studied the influence of Factor XIII a (F XIII a) activity on the lysis rate of fresh whole human blood clots, without using anticoagulants. Clotting was induced by exogenous thrombin, lysis by tissue-type Plasminogen Activator (t-PA) added before clotting. After various periods of time, lysis rates were determined by measuring the radioactivity in the supernatant of the clot originating from 125I-Fibrinogen added before clotting.

Lysis rates were determined in the presence of endogenous F XHIa and compared with those obtained after specific inhibition of F XIII a activity. We used an IgG fraction of an antiserum quenching the F XIII a activity. Addition of increasing amounts of the antibodies to normal blood resulted in a dramatic increase in clot lysis rate, concomitant with loss of F XIII activity. Lysis of blood clots from a patient with a congenital, homozygous, functional α2-Antiplasmin (α2-AP) deficiency (α2-AP-Enschede) was not or slightly increased by the anti F XIII antibodies indicating that fibrin-fibrin crosslinking per se does not contribute essentially to resistance of the blood clot against fibrinolysis. Both active α2-AP and F XIII a are required for the major part of the F XIII-dependent resistance of whole blood clots against lysis.

Depression of Tissue Plasminogen Activator (t-PA) Activity and Rise of t-PA Inhibition and Acute Phase Reactants in Blood of Patients with Acute Myocardial Infarction (AMI)

We determined during the acute stage of myocardial infarction selected fibrinolysis variables (tissue-type plasminogen activator, intrinsic plasminogen activators, tissue-type plasminogen activator inhibition, C1-inactivator) and relatedthe observed changes to changes in two acute phase reactants (C-reactive protein, fibrinogen). Acute myocardial injury induce significant increases in blood of tissue-type plasminogen activator inhibition (day one, p <0.05), C-reactive protein (day three, p <0.01), fibrinogen (day six, p <0.01), and C1-inactivator (day eight, p <0.01). Tissue-type plasminogen activator activity measured as C1-inactivator resistant fibrinolytic activity showed a minimum day two after the acute attack (p <0.01), whereas plasminogen activator activities arising from the intrinsic system of fibrinolysis remained constant. The observed changes did not parallel the occurrence of deep vein thrombosis indicated by a positive Tc-plasmin test (41% of the patients).

The BCR-ABL1 Inhibitors Imatinib and Ponatinib Decrease Plasma Cholesterol and Atherosclerosis, and Nilotinib and Ponatinib Activate Coagulation in a Translational Mouse Model

Treatment with the second and third generation BCR-ABL1 tyrosine kinase inhibitors (TKIs) increases cardiovascular risk in chronic myeloid leukemia (CML) patients. We investigated the vascular adverse effects of three generations of TKIs in a translational model for atherosclerosis, the APOE*3Leiden.CETP mouse. Mice were treated for sixteen weeks with imatinib (150 mg/kg BID), nilotinib (10 and 30 mg/kg QD) or ponatinib (3 and 10 mg/kg QD), giving similar drug exposures as in CML-patients. Cardiovascular risk factors were analyzed longitudinally, and histopathological analysis of atherosclerosis and transcriptome analysis of the liver was performed. Imatinib and ponatinib decreased plasma cholesterol (imatinib, −69%, p < 0.001; ponatinib 3 mg/kg, −37%, p < 0.001; ponatinib 10 mg/kg−44%, p < 0.001) and atherosclerotic lesion area (imatinib, −78%, p < 0.001; ponatinib 3 mg/kg, −52%, p = 0.002; ponatinib 10 mg/kg, −48%, p = 0.006), which were not affected by nilotinib. In addition, imatinib increased plaque stability. Gene expression and pathway analysis demonstrated that ponatinib enhanced the mRNA expression of coagulation factors of both the contact activation (intrinsic) and tissue factor (extrinsic) pathways. In line with this, ponatinib enhanced plasma levels of FVII, whereas nilotinib increased plasma FVIIa activity. While imatinib showed a beneficial cardiovascular risk profile, nilotinib and ponatinib increased the cardiovascular risk through induction of a pro-thrombotic state.

Daytime Fluctuations in Blood of Tissue-Type Plasminogen Activator (t-PA) and Its Fast-Acting Inhibitor (PAI-1)

Circadian fluctuation in blood fibrinolytic activity was studiedin 10 volunteers in the day-time period at 09.00, 12.00 and15.0 h. Activity of tissue-type plasminogen activator (t-PA) wasfound to increase from 09.00 to 15.00 h in accordance with knownresults with global assays of blood activity.

Mild Haemostatic Problems Associated with Congenital Heterozygous α2-Antiplasmin Deficiency

A Dutch family, of which 13 members are heterozygotes, deficient for α2-antiplasmin (α2-AP) is reported. Clinical studies showed that 2 heterozygotes had a mild bleeding tendency, which presented as bleeding episodes after tooth extraction and after surgery and, in one patient, also as excessive menstruation. Laboratory investigations revealed an α2-AP activity of 62% (51-71) (median and range) and an antigen level of 60% (60-66). The plasminogen binding as well as the fibrin binding properties of α2-AP were normal. Plasminogen concentrations were significantly higher in the heterozygotes compared to the other family members. However, free plasminogen not bound to histidine-rich glycoprotein was not significantly different between these two groups. We propose that in this family the deficiency of α2-AP is due to a decreased synthesis of a normal α2-AP molecule. This present study brings the frequency of heterozygous α2-AP deficient patients with a bleeding tendency to 13 out of 59 heterozygotes reported in the literature.

Thrombin Generation in Vitreous and Subretinal Fluid of Patients with Retinal Detachment

PURPOSE

To measure prothrombin fragments (F1+2) and thrombin-antithrombin complex (TAT) in vitreous and subretinal fluid (SRF) of rhegmatogenous retinal detachment (RRD) patients and to validate and further specify our earlier finding of increased thrombin activity in patients with proliferative vitreoretinopathy (PVR).

METHODS

F1+2 and TAT were measured in 31 vitreous and 16 SRF samples using the Enzygnost® immunoassays.

RESULTS

We found significant levels of F1+2 and TAT in the vitreous of all patients with RRD compared to patients with macular hole or macular pucker. However, there was no significant difference between patients who would develop PVR in the future, had established PVR, and patients with uncomplicated RRD both in vitreous concentrations of F1+2 (Kruskal-Wallis p = 0.963) and TAT (p = 0.516).

CONCLUSION

The analysis of F1+2 and TAT confirmed significant thrombin generation in both vitreous and SRF of patients with RRD. An imbalance between the thrombin regulation mechanisms TAT and α2-macroglobulin possibly explains the difference from our previous findings.

Venous thromboembolism during pregnancy is not associated with persistent elevated activated protein C (APC) sensitivity ratio based on the endogenous thrombin potential

Women who are using oral contraceptives can acquire APC resistance, measured by the effect of APC on the endogenous thrombin potential (ETP). The objective of our study was to examine whether persistentAPC resistance determined with an ETP-based normalized APC sensitivity ratio (nAPCsr) is a risk marker for venous thromboembolism in women with pregnancy-associated thromboembolism. We determined the activities of antithrombin, protein C, protein S, and performed a genetic analysis of factor V Leiden G1691A, prothrombin mutation G20210A, and methylenetetrahydrofolate reductase mutation (MTHFR C677T) in 65 women with venous thromboembolism during pregnancy or the puerperium and in 114 normal women. A significantly (p<0.05) higher nAPCsr was present in normal women using hormones, in younger women (≤ 45 yrs), and in women with carrier status of factorV Leiden. In normal women without factor V Leiden a significant (p< 0.05) negative correlation of nAPCsr with age (r= –0.39),antithrombin activity (r= –0.38),protein S activity (r= –0,26),and a significant positive correlation with hormone intake (r= 0.36) was present. nAPCsr is influenced by several coagulation parameters, which are modified by the use of oral contraceptives. Consequently, a multivariate analysis of our data did not show a significant association of nAPCsr to venous thromboembolism, neither as a continuous variable (odds ratio 0.8, 95% CI 0.6–1.1, p=0.10) nor using a cutoff value (nAPCsr cut-off 3.1: odds ratio 1.2, 95% CI 0.3–5.3, p=0.77). Our study demonstrates that nAPCsr is not a risk marker for pregnancy-associated venous thromboembolism.

DNA-Polymorphisms and Plasma Levels of Vascular Disease Risk Factors in Greenland Inuit

Greenland Inuit are a population with a low risk of cardiovascular disease. Recently, we stated that frequencies of potentially high risk alleles of the apolipoproteins, fibrinogen, factor V, glycoprotein IIIa and factor VII (FVII) genes have different allele frequencies in the Inuit when compared with Caucasian populations. We have extended this study and evaluated whether or not this was also true for the genetic polymorphisms of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), angiotensin-converting enzyme (ACE) and angiotensinogen in a group of 133 Greenland Inuit, aged 30-34 y. In addition, we compared the plasma levels of these factors and those of C-reactive protein (CRP) and D-Dimer in Inuit and in Danes, comparable for age and gender. Frequencies (f) were assessed of the alleles that are known as the potential high risk alleles in Caucasians.

In the Inuit, the f(insertion allele) of the t-PA intron8ins311 polymorphism was 0.37 (CI 0.32-0.43), the f(4G allele) of the PAI-1 promoter polymorphism was 0.88 (CI 0.83-0.91), the f(deletion allele) of the ACE intron16ins287 polymorphism was 0.40 (CI 0.33-0.47) and the f(M-allele) of the angiotensinogen M/T353 polymorphism was 0.30 (CI 0.25-0.38). As for fibrinogen and FVII polymorphisms, these frequencies are all significantly different from what is reported for Caucasian populations. In the Inuit, plasma levels of fibrinogen and D-Dimer were higher than in the Danes, the PAI-1 levels were lower and FVII, t-PA and CRP levels were comparable. The observed allele frequencies of the polymorphisms of t-PA, fibrinogen, FVII, ACE, angiotensinogen and the plasma levels of PAI-1 and D-Dimer were in accordance with the low CVD risk in the Inuit, considering the observed associations between these measures and CVD risk in Caucasian populations, but for other measures this was not the case (allele frequencies of the PAI-1 polymorphism, and plasma levels of fibrinogen, FVII and t-PA).

In conclusion there are clear differences in genetic background and plasma levels of risk factors in Greenland Inuit compared with Caucasian populations, and these differences were sometimes, but not always, in accordance with the observed low cardiovascular disease risk of the Inuit population.

Activation Products of the Haemostatic System in Coronary, Cerebrovascular and Peripheral Arterial Disease

To determine the presence of a ‘hypercoagulable state’ as assessed by indices of thrombin and plasmin generation and of the amount of fibrin that is lysed, in patients with stable coronary, cerebral and peripheral arterial disease a population-based cross-sectional study was performed. From a population-based cohort comprising 7983 men and women aged 55 years and over, we randomly selected 127 subjects with a history of myocardial infarction, 124 with a history of stroke and/or transient ischemic attack, 131 patients with peripheral arterial disease and 263 control subjects in the same age group without arterial disease. Subjects using anticoagulant drugs were not selected. F1+2, TAT, and PAP were not associated with a history of cardiovascular events, nor with peripheral arterial disease. In contrast, positive associations were found for D-Dimer. Mean D-Dimer level was 40 μg/l (95% CI 35,44) in control subjects; 53 μg/l (47, 61) in those with a history of myocar-dial infarction and 51 μg/l (45, 58) in those with a history of stroke and or transient ischemic attack. D-Dimer increased gradually with increasing severity of peripheral atherosclerosis; a decrease in ankle/arm systolic blood pressure ratio of 0.1 was associated with an increase in D-Dimer of 3.9 μg/l (p<0.01). This was more pronounced in subjects with higher F1+2, TAT and PAP concentration. In conclusion, the markers of onset of coagulation F1+2, TAT and PAP are not associated with the presence of arterial disease, but increased levels of these markers are necessary for the positive association between D-Dimer and arterial disease.

Clot Accumulation Characteristics of Plasminogen-bearing Liposomes in a Flow-system

In this study, the clot accumulation properties of liposome-coupled plasminogen were compared to those of free (non-liposomal) plasminogen in an in vitro, closed-loop, flow-system. After introduction of a clot into the closed system, double-radiolabelled plasminogen-liposomes were administered and the accumulation of radiolabel on the entire clot was measured.

Liposomal plasminogen showed improved accumulation over free plasminogen, on both a fibrin clot and a whole blood clot. Moreover, once liposomal plasminogen was fibrin associated, it could not be washed away with buffer, in contrast to free plasminogen. Liposomal plasminogen was able to compete successfully with an excess of free plasminogen. The plateau levels for the accumulated amount of plasminogen depended on the incubated amount of plasminogen and were influenced by partial degradation of the clot. Furthermore, it was shown that a threshold liposomal plasminogen surface-density was needed for optimum clot accumulation.

Fibrinolytic Activity in Peripheral Atherosclerosis in the Elderly

Increased concentrations of plasminogen activator inhibitor type 1 (PAI-1) and of D-dimer have jointly been found in subjects with cardiovascular disease. To understand this apparent paradox of increased inhibition of fibrinolysis (high PAI-1) combined with increased fibrinolytic activity (high D-dimer), we examined the relation between D-dimer, PAI-1 and the activator of fibrinolysis, tissue type plasminogen activator (t-PA) in subjects with varying severity of peripheral atherosclerosis. In 325 subjects selected from the Rotterdam Study, a cohort of 7983 men and women aged 55 years and over, the ankle to brachial systolic blood pressure ratio, t-PA antigen and activity, PAI-1 antigen and D-dimer were measured.

T-PA antigen and t-PA activity were, independent from each other, increased with degree of atherosclerosis; t-PA antigen increased with 3.5 ng/ml (SE 1.7, p = 0.04) and t-PA activity with 0.46 IU/ml (0.20, p = 0.02) per unit decrease in ankle to brachial pressure ratio (i.e. increase in atherosclerosis). PAI-1 antigen was not related to atherosclerosis. More marked atherosclerosis was associated with increased D-dimer, mainly in subgroups with PAI-1 antigen below 50 ng/ml, t-PA antigen below 10 ng/ml, or t-PA activity above 1.5 IU/ml. In contrast to current beliefs, we found that only a fraction of the variation of t-PA antigen was due to the variation in circulating PAI-1 antigen. A slight positive association was observed between t-PA antigen and D-dimer. PAI-1 and t-PA activity were not associated with D-dimer concentration.

In conclusion, in subjects with peripheral atherosclerosis PAI-1 antigen is not increased, but low PAI-1 levels (and possibly also low levels of t-PA antigen and high levels of t-PA activity) appear to be required to increase circulating D-dimer. This suggests that increased D-dimer levels in subjects with atherosclerosis do not reflect increased inhibition, but rather reflect increased fibrinolysis.

Diurnal Variation in PAI-1 Activity Predominantly Confined to the 4G-allele of the PAI-1 Gene

We examined the diurnal pattern in Plasminogen Activator Inhibitor-type 1 (PAI-1) activity and Plasminogen activator (t-PA) in relation to the 4G/5G-polymorphism in the promoter of the PAI-1 gene. The analyses were performed in the Arnhem Elderly Study, a populationbased study of 598 elderly. A single blood sample was drawn and the time of blood sampling was recorded (between 8 a. m. and 5.30 p. m.). Plasma PAI-1 activity was strongly associated with time of blood sampling, showing the highest values in the early morning. The diurnal pattern was clearly present in the 4G/4G (n = 184) and 4G/5G (n = 275) genotypes, but not in the 5G/5G-genotype (n = 139). T-PA antigen showed a weak diurnal variation, which did not differ across the variants of the 4G/5G-polymorphism. Our findings raise the hypothesis that 5G-homozygotic persons may be relatively protected from diurnal variation in the occurrence of coronary events.

Association between thrombin-activatable fibrinolysis inhibitor (TAFI) and clinical outcome in patients with unstable angina pectoris

Decrease of fibrinolytic potential is considered to be a risk factor for arterial thrombosis. The recently described thrombinactivatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis by cleaving of the C-terminal lysine residues from fibrin, thereby inhibiting tPA mediated plasminogen activation. The role of plasma TAFI antigen (Ag) levels and gene polymorphisms in arterial thrombosis is still not elucidated. In this prospective study, the association between plasma TAFI Ag levels and the TAFI gene polymorphisms, Ala147Thr, Thr325Ile and -438A/G, with refractory unstable angina pectoris (UAP) was determined. The study population consisted of 209 patients with UAP of whom 76 were refractory and 133 non-refractory to medical treatment. In the same study population the contribution of these polymorphisms to plasma TAFI Ag levels was determined.

Plasma TAFI Ag levels were significantly higher in non-refractory patients compared to refractory patients (geometric mean 114.4 and 105.6 U/dl respectively, p=0.042). Plasma TAFI Ag levels in the lowest quartile resulted in a 2.6 fold (95% confidence interval 1.2-5.9) increased risk for refractory UAP compared to plasma TAFI Ag levels in the upper quartile. The three studied TAFI polymorphisms had an independent and additive effect on plasma TAFI Ag levels. However, no significant association between the individual TAFI polymorphisms and refractiveness was observed.

In conclusion, in this study population plasma TAFI Ag levels are significantly correlated with refractiveness in patients with UAP. Furthermore, all three polymorphisms contribute independently to plasma TAFI Ag levels, but not to refractiveness.

Part of this paper was originally presented at the joint meetings of the 16th International Congress of the International Society of Fibrinolysis and Proteolysis (ISFP) and the 17th International Fibrinogen Workshop of the International Fibrinogen Research Society (IFRS) held in Munich, Germany, September, 2002.

No effect of folic acid supplementation in the course of 1 year on haemostasis markers and C-reactive protein in older adults

Elevated homocysteine levels are associated with an increased cardiovascular disease (CVD) risk, but the underlying mechanism is still unclear. High homocysteine might affect the endothelium, and consequently lead to impaired haemostasis. In a randomized placebo controlled trial among 276 older adults with plasma total homocysteine concentrations above 13 mM at screening, we investigated the effect of homocysteine lowering by folic acid supplementation (0.8 mg/day) for 1 year on markers of endothelial function (vonWillebrand factor), coagulation (tissue factor, factor VIIa, fragments 1+2), and fibrinolysis (fibrin degradation products, tissue-type plasminogen activator), and inflammation (C-reactive protein). Despite a 24% reduction in plasma homocysteine concentration and four-fold increase in serum folate concentration in the folic acid group compared to the placebo group, there was no clear change in any of the haemostasis markers, nor CRP. Although homocysteine is associated with vascular disease risk in the general population, marked lowering of slightly elevated homocysteine concentrations by one-year folic acid supplementation does not influence haemostasis markers.

Performance goals for the laboratory testing of antithrombin, protein C and protein S

To achieve a reliable analytical quality for both monitoring and diagnostic testing, laboratories need to fulfil the widely accepted analytical performance goals based on the biological variation of the analytes of testing. Not only is the short-term analytical performance, which regularly is assessed by internal quality control procedures, of importance, but also the long-term analytical performance. To assess the long-term analytical performance, data obtained from an external quality assessment programme can be used. In this study we have used the evaluation model designed by the ECAT Foundation for the assessment of the longterm analytical performance, including imprecision, bias and total analytical error. The model was applied to the data from 136 different laboratories for the assay of antithrombin (activity), protein C (activity and antigen) and protein S (activity, total and free antigen). The imprecision (median; range), reflected by the long-term analytical coefficient of variation (LCVA), was the lowest for antithrombin (7.6%; 2.6 – 43.8%) and the highest for protein S activity (17.2%; 4.3 – 88.6%). For bias and total error the same pattern was observed (antithrombin: 3.8%; 0.3 – 17.1% and 9.1%; 3.4 – 34.3%, respectively; protein S activity: 12.8%; 3.1 – 34.8% and 24.5%; 9.9 – 87.0%, respectively). For the majority of the laboratories (70 – 85%) the imprecision contributes considerably more to the total error than the bias. However the effect of the bias on the analytical quality is not negligible. Assays for antithrombin, protein C and protein S are mainly used for diagnostic testing. About 70 – 100% of the laboratories can fulfil the desirable performance goal for imprecision. The desirable performance goal for bias was reached by 50 – 95% of the laboratories. In all cases the highest numbers of laboratories fulfilling performance goals was obtained for the protein C variables. To improve the analytical quality in assays of antithrombin, protein C and protein S it is highly recommended that primarily imprecision (non-systematic failures) be suppressed. However the effect of the bias (systematic failures) on the analytical quality should not be neglected. A useful tool for determining the imprecision (LCVA) and bias is the long-term analytical performance evaluation model as used by the ECAT Foundation.

A model for the harmonisation of test results of different quantitative D-dimer methods

The numerical test results of different D-dimer assays vary widely. Because of the complexity of the analyte of target as well as the variability in specificity of different D-dimer assays, only harmonisation of the test results seems to be feasible. The use of a single conversion factor does not take into account for several methods the lack of commutability between test results and consensus values at different D-dimer levels. This is probably related to the mutually different response of methods to high and low levels. We therefore designed a harmonisation model based on the transformation of a method-specific regression line to a reference regression line. We used the data for the measurement of a set of plasma samples with different D-dimer levels by 353 different laboratories using 7 of the most frequently used quantitative D-dimer methods. For each method we calculated the method-specific consensus value for each sample. The overall median value was also estimated. Per method linear regression was applied throughout the method-specific consensus values using the amount of patient pooled plasma added to the different plasma samples as the independent variable. The line through the overall median values of all 7 methods was used as the reference line. Harmonisation between the methods was obtained by transformation of the method-specific regression line to the reference line. This harmonisation resulted in a reduction of the variability between the method-specific consensus values from about 75% to about 5.5%. Clinical validation of this concept had shown significant improvement of the test result comparability. We conclude that this model isa feasible approach in the harmonisation of D-dimer methods. If the harmonisation procedure is included in the calibration procedure by the manufacturers, customers will automatically obtain harmonised test results.

Fibrin clot structure - pro-fibrinolytic effect of oral contraceptives in apparently healthy women

Fibrin metabolism is influenced by many factors. The velocity of fibrin formation, genetic polymorphisms, fibrinolytic features and the structure of the fibrin clot are determinants of fibrin turnover. Oral contraceptives (OCs) have significant impact on the haemostatic system, by increasing the concentration of coagulation factors, plasminogen and tissue plasminogen activator activity, and decreasing the concentration of haemostatic inhibitors. The present study addresses the influence of OCs on fibrin structure and fibrin metabolism. The study included 70 women treated with seven different OC-formulations. Blood was collected at baseline and after six months of OCs. The plasma concentration of fibrinogen, thrombin-antithrombin complex (TAT), plasminogen, plasmin-antiplasmin complex (PAP), D-Dimer and thrombin generation measures were determined. Fibrin structure measures and fibrin clot lysis not affected by the plasma concentration of plasminogen activators and inhibitors were determined. OCs increased the concentration of fibrinogen, TAT, plasminogen, PAP and D-dimer significantly and affected measures of thrombin generation (p<0.001). The maximal optical density of fibrin (p<0.001), the fibrin fibre density (p=0.03), fibrin fibre diameter (p=0.003), fibrin mass-length ratio (p<0.001) and lysis per hour (p<0.001) increased significantly upon OC-treatment. Lysis per hour was not correlated to the concentration of plasminogen. We conclude that the effect of OCs on the coagulation system is balanced by alterations in fibrin structure, facilitating clot lysis and contributing to the fibrinolytic susceptibility already present in women treated with OC. These alterations may counterbalance the OC-induced increased thrombin generation and reduced coagulation inhibitory potential, contributing to maintenance of the haemostatic balance in women receiving OCs.

2SNP heritability and effects of genetic variants for neutrophil-to-lymphocyte and platelet-to-lymphocyte ratio

Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are important biomarkers for disease development and progression. To gain insight into the genetic causes of variance in NLR and PLR in the general population, we conducted genome-wide association (GWA) analyses and estimated SNP heritability in a sample of 5901 related healthy Dutch individuals. GWA analyses identified a new genome-wide significant locus on the HBS1L-MYB intergenic region for PLR, which replicated in a sample of 2538 British twins. For platelet count, we replicated three known genome-wide significant loci in our cohort (at CCDC71L-PIK3CG, BAK1 and ARHGEF3). For neutrophil count, we replicated the PSMD3 locus. For the identified top SNPs, we found significant cis and trans expression quantitative trait loci effects for several loci involved in hematological and immunological pathways. Linkage Disequilibrium score (LD) regression analyses for PLR and NLR confirmed that both traits are heritable, with a polygenetic SNP heritability for PLR of 14.1%, and for NLR of 2.4%. Genetic correlations were present between ratios and the constituent counts, with the genetic correlation (r=0.45) of PLR with platelet count reaching statistical significance. In conclusion, we established that two important biomarkers have a significant heritable SNP component, and identified the first genome-wide locus for PLR.

Uncovering a Predictive Molecular Signature for the Onset of NASH-Related Fibrosis in a Translational NASH Mouse Model

BACKGROUND & AIMS

The incidence of nonalcoholic steatohepatitis (NASH) is increasing. The pathophysiological mechanisms of NASH and the sequence of events leading to hepatic fibrosis are incompletely understood. The aim of this study was to gain insight into the dynamics of key molecular processes involved in NASH and to rank early markers for hepatic fibrosis.

METHODS

A time-course study in low-density lipoprotein-receptor knockout. Leiden mice on a high-fat diet was performed to identify the temporal dynamics of key processes contributing to NASH and fibrosis. An integrative systems biology approach was used to elucidate candidate markers linked to the active fibrosis process by combining transcriptomics, dynamic proteomics, and histopathology. The translational value of these findings were confirmed using human NASH data sets.

RESULTS

High-fat-diet feeding resulted in obesity, hyperlipidemia, insulin resistance, and NASH with fibrosis in a time-dependent manner. Temporal dynamics of key molecular processes involved in the development of NASH were identified, including lipid metabolism, inflammation, oxidative stress, and fibrosis. A data-integrative approach enabled identification of the active fibrotic process preceding histopathologic detection using a novel molecular fibrosis signature. Human studies were used to identify overlap of genes and processes and to perform a network biology-based prioritization to rank top candidate markers representing the early manifestation of fibrosis.

CONCLUSIONS

An early predictive molecular signature was identified that marked the active profibrotic process before histopathologic fibrosis becomes manifest. Early detection of the onset of NASH and fibrosis enables identification of novel blood-based biomarkers to stratify patients at risk, development of new therapeutics, and help shorten (pre)clinical experimental time frames.

Biological Variation of Hemostasis Variables in Thrombosis and Bleeding: Consequences for Performance Specifications

BACKGROUND

Levels of hemostasis factors vary between and within individuals as a result of genetic and environmental factors and analytical variation of the assays. The current state of the art for defining analytical precision requirements for analytical testing is based on this between- and within-individual (biological) variation. However, information on biological variation in hemostasis variables is still limited.

The aim of this study was to determine the biological variation of coagulation variables involved in thrombosis and bleeding to provide a recommendation for performance specifications and to assess whether hemostasis assays fulfill the recommendation.

METHODS

We performed a longitudinal study by repeated blood sampling (in total 13 times over a 1-year period) in 40 healthy individuals and measured prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, antithrombin, factor VIII, factor IX, von Willebrand factor (VWF), protein C, and protein S. We evaluated the effect of the biological variation on parameters of analytical variation and propose required performance specifications.

RESULTS

Biological variation was highly different for various hemostasis variables: the within-subject variation ranged from 2.6% (PT) to 25.6% [VWF collagen binding (CB) activity], the between-subject variation varied from 4.1% (PT) to 31.2% (VWF:ristocetin cofactor acitivity), and the assay variation from 1.3% (PT) to 12.9% (VWF:CB).

CONCLUSIONS

With the reagents and analyzers used in this study, most of the hemostasis tests variables fulfill the current quality criteria for diagnosis and monitoring of routine hemostasis assays.

Vitreous and subretinal fluid concentrations of orally administered dabigatran in patients with rhegmatogenous retinal detachment

PURPOSE

One of the factors that was shown to contribute to the development of proliferative vitreoretinopathy (PVR) is the coagulation factor thrombin. Therefore, a specific oral thrombin inhibitor such as dabigatran might be a possible therapeutic option. An oral drug has the advantage of patient-friendly prolonged administration in contrast to drugs that can only be applied during vitrectomy, on condition that the drug reaches the target site. We tested whether dabigatran reaches the vitreous and subretinal fluid (SRF) after a single oral dose of dabigatran.

METHODS

Twenty-eight patients with a retinal detachment received a single dose of 220 mg dabigatran etexilate 2-8 hr prior to surgery. During surgery, we took a blood sample and a vitreous or subretinal fluid sample. The concentration of dabigatran was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

The dabigatran concentration between 2 and 9 hr after administration was higher in SRF than in vitreous (max 8.5 and 3.8 ng/ml). Corresponding plasma concentrations ranged from 15 to 225 ng/ml. There was a significant relationship between SRF levels and plasma levels (r_s  = 0.68, p = 0.014); the levels in vitreous fluid showed no such relationship (r_s  = 0.20, p = 0.48). In addition, we measured the vitreous concentration of a non-study patient using 150 mg dabigatran twice daily. The concentration was approximately 10 times higher than after a single dosage (25.8 ng/ml).

CONCLUSION

We demonstrate that oral intake of dabigatran, a candidate drug to modulate PVR, results in potentially relevant intraocular concentrations. We suggest that repeated dosing may lead to higher concentrations, but this should be further explored.

Causes of variation in the neutrophil-lymphocyte and platelet-lymphocyte ratios: a twin-family study

AIM

Neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLR) are biomarkers for disease development, for whom little is known about causes of variation in the general population.

MATERIALS & METHODS

We estimated the heritability of PLR and NLR and examined their association with gender, demographic, lifestyle and environmental factors in a Dutch nonpatient twin family population (n = 8108).

RESULTS

Heritability was estimated at 64% for PLR and 36% for NLR. Men had on average higher NLR, but lower PLR levels than women. PLR and NLR increased significantly with age, decreased in colder months and showed small but significant sex- and age-specific associations with body composition and smoking.

CONCLUSION

NLR and PLR levels are heritable and influenced by age, sex and environmental factors, such as seasonal conditions and lifestyle.

Review: Diabetes as a procoagulant condition

Major known effects of the metabolic derangements of diabetes in haemostasis are induction of platelet-vascular activation by hyperglycaemia, the increase in fibrinogen, modification of fibrin substrate by glucose and hypofibrinolysis related to insulin resistance. The platelet effects are specifically expressed during high shear stress and may be relevant in particular for developing of micro-angiopathy. Hypofibrinolysis, increased fibrinogen and modifications of fibrin may aggravate microthrombosis and organ damage and contribute to precipitation of coronary and cerebral infarction. In addition to specific anti-diabetic medication to reduce the haemostatic effects, specific antiplatelet and profibrinolytic treatments may be relevant for reducing further the morbidity and mortality in diabetics for both micro- and macro-angiopathy.

Discovery of biochemical biomarkers for aggression: A role for metabolomics in psychiatry

Human aggression encompasses a wide range of behaviors and is related to many psychiatric disorders. We introduce the different classification systems of aggression and related disorders as a basis for discussing biochemical biomarkers and then present an overview of studies in humans (published between 1990 and 2015) that reported statistically significant associations of biochemical biomarkers with aggression, DSM-IV disorders involving aggression, and their subtypes. The markers are of different types, including inflammation markers, neurotransmitters, lipoproteins, and hormones from various classes. Most studies focused on only a limited portfolio of biomarkers, frequently a specific class only. When integrating the data, it is clear that compounds from several biological pathways have been found to be associated with aggressive behavior, indicating complexity and the need for a broad approach. In the second part of the paper, using examples from the aggression literature and psychiatric metabolomics studies, we argue that a better understanding of aggression would benefit from a more holistic approach such as provided by metabolomics. © 2016 Wiley Periodicals, Inc.

Assessing Safety of Thrombolytic Therapy

Thrombolytic therapy involves thrombolytic agents administered to patients suffering from venous or arterial thrombosis. The therapy induces systemic effects interrelated with the thrombolytic agent used. Bleeding is a prominent complication of thrombolytic therapy. Exhaustion of coagulation factors, generation of excessive amounts of fibrin degradation products (FDPs), therapy-induced activation of coagulation, therapy-induced anticoagulation, and formation of new fibrin all illustrate the complexity of effects of the treatment and challenges the hemostatic balance in the patients. The therapy-induced effects can be modulated by parallel administration of anticoagulants. Risk assessment is mandatory prior to thrombolytic therapy. Anticoagulated and unconscious patients represent particular safety concerns, and should be fully evaluated. Several guidelines describe the choice of tests and their safety limits in relation to pretreatment evaluation of anticoagulated patients. Fibrinogen depletion and FDPs during treatment may be promising markers for the evaluation of bleeding risk posttreatment. Future risk assessment measures should focus on the dynamics of the hemostatic balance. Here, thromboelastography may be considered a tool addressing clot formation, fibrin structure, and fibrinolytic resistance in parallel. Suitable laboratory analysis performed shortly after treatment may help to recognize severe treatment-induced systemic effects that can be counteracted by rational treatment, thereby reducing bleeding risk.

Comparison of Three Isolation Techniques for Human Peripheral Blood Mononuclear Cells: Cell Recovery and Viability, Population Composition, and Cell Functionality

Routine techniques for the isolation of human peripheral blood mononuclear cells (PBMCs) include density centrifugation with Ficoll-Paque and isolation by cell preparation tubes (CPTs) and SepMate tubes with Lymphoprep. In a series of experiments, these three PBMC isolation techniques were compared for cell recovery and viability, PBMC population composition, and cell functionality, aiming to provide a starting basis for the selection of the most appropriate method of PBMC isolation for a specific downstream application. PBMCs were freshly isolated from venous blood of healthy male donors, applying the different techniques in parallel. Cell recovery and viability were assessed using a hemacytometer and trypan blue. Immunophenotyping was performed by flow cytometry. Cell functionality was assessed in stimulated (100 ng/mL staphylococcal enterotoxin B [SEB]) and unstimulated 24 hours PBMC cultures, with cytokine production and lactate dehydrogenase (LDH) release as readout measures. PBMC isolation by SepMate and CPT resulted in a 70% higher recovery than Ficoll isolation. CPT-isolated populations contained more erythrocyte contamination. Cell viability, assessed by trypan blue exclusion, was 100% for all three isolation techniques. SepMate and CPT isolation gave higher SEB-induced cytokine responses in cell cultures, for IFNγ and for secondary cytokines. IL-6 and IL-8 release in unstimulated cultures was higher for CPT-isolated PBMCs compared to Ficoll- and SepMate-isolated PBMCs. LDH release did not differ between cell isolation techniques. In addition to criteria such as cost and application practicalities, these data may support selection of a specific PBMC isolation technique for downstream analysis.

Effect of genome and environment on metabolic and inflammatory profiles

Twin and family studies have established the contribution of genetic factors to variation in metabolic, hematologic and immunological parameters. The majority of these studies analyzed single or combined traits into pre-defined syndromes. In the present study, we explore an alternative multivariate approach in which a broad range of metabolic, hematologic, and immunological traits are analyzed simultaneously to determine the resemblance of monozygotic (MZ) twin pairs, twin-spouse pairs and unrelated, non-cohabiting individuals. A total of 517 participants from the Netherlands Twin Register, including 210 MZ twin pairs and 64 twin-spouse pairs, took part in the study. Data were collected on body composition, blood pressure, heart rate, and multiple biomarkers assessed in fasting blood samples, including lipid levels, glucose, insulin, liver enzymes, hematological measurements and cytokine levels. For all 51 measured traits, pair-wise Pearson correlations, correcting for family relatedness, were calculated across all the individuals in the cohort. Hierarchical clustering techniques were applied to group the measured traits into sub-clusters based on similarity. Sub-clusters were observed among metabolic traits and among inflammatory markers. We defined a phenotypic profile as the collection of all the traits measured for a given individual. Average within-pair similarity of phenotypic profiles was determined for the groups of MZ twin pairs, spouse pairs and pairs of unrelated individuals. The average similarity across the full phenotypic profile was higher for MZ twin pairs than for spouse pairs, and lowest for pairs of unrelated individuals. Cohabiting MZ twins were more similar in their phenotypic profile compared to MZ twins who no longer lived together. The correspondence in the phenotypic profile is therefore determined to a large degree by familial, mostly genetic, factors, while household factors contribute to a lesser degree to profile similarity.

Longitudinal weight differences, gene expression and blood biomarkers in BMI-discordant identical twins

Background

BMI discordant monozygotic (MZ) twins allows an examination of the causes and consequences of adiposity in a genetically controlled design. Few studies have examined longitudinal BMI discordance in MZ pairs.

Objectives

To study the development over time of BMI discordance in adolescent and adult MZ twin pairs, and to examine lifestyle, metabolic, inflammatory, and gene expression differences associated with concurrent and long-term BMI discordance in MZ pairs.

Subjects/Methods

BMI data from 2775 MZ twin pairs, collected in eight longitudinal surveys and a biobank project between 1991 and 2011, were analyzed to characterize longitudinal discordance. Lifestyle characteristics were compared within discordant pairs (ΔBMI ≥ 3 kg/m²) and biomarkers (lipids, glucose, insulin, CRP, fibrinogen, IL-6, TNF-α and sIL-6R and liver enzymes AST, ALT and GGT) and gene expression were compared in peripheral blood from discordant pairs who participated in the NTR biobank project.

Results

The prevalence of discordance ranged from 3.2% in 1991 (mean age=17, SD=2.4) to 17.4% (N=202 pairs) in 2009 (mean age=35, SD=15), and was 16.5% (N=174) among pairs participating in the biobank project (mean age=35, SD=12). Of 699 MZ with BMI data from 3-5 time points, 17 pairs (2.4%) were long-term discordant (at all available time points; mean follow-up range=6.4 years). Concurrently discordant pairs showed significant differences in self-ratings of which twin eats most (p=2.3×10⁻¹³), but not in leisure time exercise activity (p=0.28) and smoking (p>0.05). Ten out of 14 biomarkers showed significantly more unfavorable levels in the heavier of twin of the discordant pairs (p-values < 0.001); most of these biomarker differences were largest in longitudinally discordant pairs. No significant gene expression differences were identified, although high ranking genes were enriched for Gene Ontology (GO) terms highlighting metabolic gene regulation and inflammation pathways.

Conclusions

BMI discordance is uncommon in adolescent identical pairs but increases with higher pair-mean of BMI at older ages, although long-term BMI discordance is rare. In discordant pairs, the heavier twin had a more unfavorable blood biomarker profile than the genetically matched leaner twin, in support of causal effects of obesity.

Consequences for the APTT due to direct action of factor XIa on factor X, resulting in bypassing factors VIII-IX

BACK GROUND

It has recently been reported that factor XIa can activate factor X directly and can bypass factors VIII-IX. We evaluated the consequences for factor analysis with the one-stage APTT.

METHODS

APTT was performed with the Actin FS reagent with ellagic acid as the standard. Silica, high lipid (PTT-A) or low lipid (PTT-LA) were also tested. Factor depleted and deficient plasma's were obtained from commercial sources.

RESULTS

The APTT clotting times in factor XII, XI, High Molecular Weight Kininogen, factor X and factor V deficient plasma's were all significantly longer (>100s) than the clotting times of factor VIII- and IX-depleted or deficient plasma's (<100s). That the shorter times for factor VIII and IX deficient plasmas were due to contact activation was supported by biphasic inhibition of the clotting times with addition of Corn Trypsin Inhibitor and Trasylol. The role of factor XI and the by-passing of factor VIII/IX was shown by the use of quenching antibodies towards factor XI and VIII. Enriching factor VIII or IX depleted plasma with purified factor XI and addition of factor XIa showed a strong dependence on factor XI level. Calibration curves for factor analysis were steeper for factors FXII, HMWK, FX and FV, compared to those of both factors VIII and IX. Curves for VIII/IX were found steeper by the use of APTT-A/silica-based, 50% diluted substrate plasma and low factor XI in the substrate plasma.

CONCLUSIONS

In factors VIII and IX deficient plasmas, the APTT shows an activity which can be attributed to contact activation of factor X by factor XIa. This direct activity is lower with silica reagent compared to ellagic acid, dilution of plasma and low factor XI in substrate plasma.

The contribution of the functional IL6R polymorphism rs2228145, eQTLs and other genome-wide SNPs to the heritability of plasma sIL-6R levels

The non-synonymous SNP rs2228145 in the IL6R gene on chromosome 1q21.3 is associated with a wide range of common diseases, including asthma, rheumatoid arthritis, type 1 diabetes and coronary heart disease. We examined the contribution of this functional IL6R gene polymorphism rs2228145 versus other genome-wide SNPs to the variance of sIL-6R levels in blood plasma in a large population-based sample (N ~5,000), and conducted an expression QTL analysis to identify SNPs associated with IL6R gene expression. Based on data from 2,360 twin families, the broad heritability of sIL-6R was estimated at 72 and 51% of the total variance was explained by the functional SNP rs2228145. Converging findings from GWAS, linkage, and GCTA analyses indicate that additional variance of sIL-6R levels can be explained by other variants in the IL6R region, including variants at the 3'-end of IL6R tagged by rs60760897 that are associated with IL6R RNA expression.

Plasma cotinine levels in cigarette smokers: impact of mental health and other correlates

BACKGROUND/AIMS

We examined in cigarette smokers whether cotinine was associated with depressive and/or anxiety disorders.

METHODS

Data were derived from 1,026 smoking adults with and without depressive and/or anxiety disorders participating in the Netherlands Study of Depression and Anxiety (NESDA). Depressive and anxiety disorders were ascertained with the DSM-IV Composite International Diagnostic Interview. Cigarette consumption was inquired about during an interview. Cotinine was assessed in plasma.

RESULTS

Currently depressed and/or anxious smokers (n=692) reported smoking a higher number of cigarettes per day (CPD) than smokers with a remitted disorder (n=190) and smokers with no lifetime disorder (n=144). After controlling for CPD and other covariates, depressed and/or anxious smokers had lower cotinine levels compared to smokers with no lifetime disorder (B=-56.0, p=0.001). In the full regression model, CPD was positively associated with cotinine levels, whereas current depression and/or anxiety and high body mass index were inversely associated with cotinine.

CONCLUSION

After considering CPD, the presence of current depressive and/or anxiety disorders was associated with lower cotinine levels, which may point to a different smoking topography or a faster cotinine metabolism in individuals with affective disorders. The latter could help to explain the higher number of cigarettes smoked and poorer cessation rates among depressed or anxious patients.

Exposure to secondhand smoke and depression and anxiety: a report from two studies in the Netherlands

OBJECTIVE

Previous population-based studies suggest that exposure to secondhand smoke (SHS) is related to increased depressive symptoms and poor mental health among non-smokers. We examined whether these associations could be replicated in two independent Dutch samples.

METHODS

Non-smoking adults were selected from two studies: 1) the Netherlands Study of Depression and Anxiety (NESDA), comprising individuals with current and remitted depressive and/or anxiety disorders, and healthy controls and 2) the Netherlands Twin Register (NTR), comprising twin-family studies on health-related behaviors. In both studies, SHS exposure was assessed with plasma cotinine levels (1-14ng/ml vs. <1ng/ml). In NESDA, outcomes were current depressive and/or anxiety disorders, and depression and anxiety symptom severity scores. In NTR, the Adult Self Report derived DSM-subscales for depressive and anxiety problems, and anxious depressive scores were analyzed.

RESULTS

In NESDA non-smokers (n=1757), increased plasma cotinine level (≥1ng/ml) was not related to current depressive and/or anxiety disorders [odds ratio (OR) 0.96, P=.77], nor to depression or anxiety severity indicators. Similarly, in NTR non-smokers (n=1088) cotinine levels ≥1ng/ml were not associated with the DSM-subscale for depressive problems [unstandardized regression coefficient (B) 0.04, P=.88], nor to other depression and anxiety measures.

CONCLUSIONS

In non-smoking adults from patient and population samples, we found no evidence that plasma cotinine levels were related to either depressive and/or anxiety disorders, or to depressive and anxiety symptoms. This suggests that SHS exposure is not related to depression and anxiety in non-smoking adults.

Abstract 316: A Superantigen Whole Blood Challenge Test for the Quantification of Immuno-inflammation in Early Phase Drug Development

Development of immune-modulating drugs is challenging as assessment of intended pharmacology in healthy volunteers is difficult. Commonly, ex-vivo LPS challenges of whole blood or isolated cells are applied. However, the applicability of the LPS challenge is limited as LPS primarily stimulates germ-line encoded innate-immune TLR4-receptors, and thus does not allow monitoring of pharmacological modulation of the adaptive immune compartment. We explored an alternative whole blood challenge, inducing lymphocyte-driven inflammation by the superantigen staphylococcal enterotoxin B (SEB), and compared this to LPS. Further validation was performed by assessing the inhibitory effects of different immune-modulating compounds (MAP kinase inhibitors, calcitriol, methotrexate, protein kinase C, doxycycline, simvastatin), allowing discrimination between effects on monocytes and lymphocytes.

SEB induction resulted in the release of a cytokine panel that well-resembled cytokine release observed after physiological lymphocyte stimulation, with clear induction of IL-2, IFN-γ, TNF- α, IL-10 and GM-CSF. Based on TNF-α and IL-2 release, SEB’s maximal effect was reached at 100 ng/mL. Whereas inter-individual variability in EC50 was relatively small for LPS (0.32±0.10 ng/mL), for SEB inter-subject variability was distinctly higher (62±54 ng/mL). MAP kinase inhibitors and calcitriol were effective in inhibiting SEB-induced TNF-α and IL-2 release, demonstrating an inhibitory effect on the monocyte and/or lymphocyte. Importantly, whereas methotrexate, doxycycline, and simvastatin did not affect SEB-induced TNF-α release, a clear inhibiting effect on SEB-induced IL-2 release was observed, implying a direct action of these compounds on the lymphocyte.

These data demonstrate that the SEB challenge can be used to estimate the immune-modulating effects of compounds directly acting on the T-lymphocyte population. As such, the whole blood SEB challenge is a useful translational tool in early drug development, especially since immune-inflammation is a target in the development of new treatment modalities for currently poorly-controlled diseases such as rheumatoid arthritis and psoriasis, and cardiovascular disease.

Abstract 342: Coagulation Pathways Drive Substantial Leukocyte Recruitment Relative to Solitary TLR4-mediated Pathways

Recruitment of leukocytes is critical for controlling infections. However, chronic leukocyte activity is deleterious in a variety of pathological conditions. As such, leukocyte behavior is an attractive pharmacological target, although knowledge is lacking on the exact triggers driving leukocyte migration. We explored the contribution of coagulation pathways versus TLR4 signaling on the leukocyte recruitment by mimicking non-sterile and sterile leukocyte activation. A sterile inflammatory milieu was generated by spontaneous ex-vivo coagulation of human whole blood, a non-sterile milieu by incubating human whole blood with LPS (at the maximal effective dose), inducing TLR-4 mediated cytokines. The chemoattractant activity of supernatant obtained from these conditions was compared by assessment of primary human leukocyte recruitment in transwell cultures, microscopically and by flow cytometry. Human recombinant IL-8 (100 ng/mL) was used as control chemoattractant.

Ex-vivo coagulation resulted in a strong release of IL-8 (119±58 ng/mL), being 5-fold higher than LPS-induced IL-8 release. Leukocyte recruitment (mainly identified as granulocytes) towards the sterile milieu was greater than TLR4-driven chemoattraction. Comparison of recombinant IL-8-induced and coagulation-induced chemotaxis indicated that chemotaxis towards the coagulated milieu was driven by more factors than IL-8 alone. Additional experiments indicated that fibrinogen cleavage product fibrinopeptide B may be involved, as this dose-dependently increased leukocyte migration.

Coagulation activation drives substantial neutrophil recruitment, primarily mediated by IL-8. For this ex-vivo coagulation model, a stronger and differently mediated leukocyte response was observed compared to TLR4-driven chemoattraction. The model can be used to study the involvement of extracellular coagulation pathways in specific inflammatory pathways that differ distinctly from pathways involved in non-sterile inflammatory conditions. This model, when further optimized, may be helpful as a methodological tool for early evaluation of new treatment modalities for chronic inflammatory diseases.

The Adult Netherlands Twin Register: twenty-five years of survey and biological data collection

Over the past 25 years, the Adult Netherlands Twin Register (ANTR) has collected a wealth of information on physical and mental health, lifestyle, and personality in adolescents and adults. This article provides an overview of the sources of information available, the main research findings, and an outlook for the future. Between 1991 and 2012, longitudinal surveys were completed by twins, their parents, siblings, spouses, and offspring. Data are available for 33,957 participants, with most individuals having completed two or more surveys. Smaller projects provided in-depth phenotyping, including measurements of the autonomic nervous system, neurocognitive function, and brain imaging. For 46% of the ANTR participants, DNA samples are available and whole genome scans have been obtained in more than 11,000 individuals. These data have resulted in numerous studies on heritability, gene x environment interactions, and causality, as well as gene finding studies. In the future, these studies will continue with collection of additional phenotypes, such as metabolomic and telomere length data, and detailed genetic information provided by DNA and RNA sequencing. Record linkage to national registers will allow the study of morbidity and mortality, thus providing insight into the development of health, lifestyle, and behavior across the lifespan.

Preincubation in the Prothrombinase-induced Clotting Time test (PiCT) is necessary for in vitro evaluation of fondaparinux and to be avoided for the reversible, direct factor Xa inhibitor, rivaroxaban

INTRODUCTION

There is no clear consensus about tests in vitro that are suitable for evaluating various factor Xa inhibitors. The availability of reversible and irreversible inhibitors further complicates the application of available assays.

METHODS

We evaluated the suitability of the prothrombinase-induced clotting test (PiCT) for fondaparinux and rivaroxaban, as representatives for irreversible and reversible inhibition of factor Xa, with specific attention to preincubation times prior to re-calcification, in the context of automate program limitations.

RESULTS

We demonstrate that the PiCT assay requires a preincubation step to allow inhibitory activity by fondaparinux. Without this step, inhibition in the test is minimal and lacking sufficient dynamic range. In contrast, to measure the reversible inhibition by rivaroxaban, we found any preincubation introduced an artifact in inhibition as exemplified by a biphasic pattern and only the test without a preincubation phase gave informative results.

CONCLUSION

It is concluded that PiCT in its format with two steps is suitable for fondaparinux evaluation, while its format without preincubation (the one-addition format) is suitable for reversible inhibitors such as rivaroxaban. Unfortunately, both types of inhibitors cannot be compared in vitro in a single assay format.