Peter Quehenberger

Advanced Glycation End Product-Induced Activation of NF-κB is Suppressed by α-Lipoic Acid in Cultured Endothelial Cells

Depletion of cellular antioxidant defense mechanisms and the generation of oxygen free radicals by advanced glycation end products (AGEs) have been proposed to play a major role in the pathogenesis of diabetic vascular complications. Here we demonstrate that incubation of cultured bovine aortic endothelial cells (BAECs) with AGE albumin (500 nmol/l) resulted in the impairment of reduced glutathione (GSH) and ascorbic acid levels. As a consequence, increased cellular oxida-tive stress led to the activation of the transcription factor NF-KB and thus promoted the upregulation of various NF-KB-controlled genes, including endothelial tissue factor. Supplementation of the cellular antiox-idative defense with the natural occurring antioxidant α-lipoic acid before AGE albumin induction completely prevented the AGE albumin–dependent depletion of reduced glutathione and ascorbic acid. Electrophoretic mobility shift assays (EMSAs) revealed that AGE albumin-mediated NF-KB activation was also reduced in a time- and dose-dependent manner as long as α-lipoic acid was added at least 30 min before AGE albumin stimulation. Inhibition was not due to physical interactions with protein DNA binding, since α-lipoic acid, directly included into the binding reaction, did not prevent binding activity of recombinant NF-KB. Western blots further demonstrated that α-lipoic acid inhibited the release and translocation of NF-KB from the cytoplasm into the nucleus. As a consequence, α-lipoic acid reduced AGE albumin-induced NF-KB mediated transcription and expression of endothelial genes relevant in diabetes, such as tissue factor and endothelin-1. Thus, supplementation of cellular antioxidative defense mechanisms by extracellularly administered α-lipoic acid reduces AGE albumin-induced endothelial dysfunction in vitro.

Prediction of venous thromboembolism in cancer patients

The risk of venous thromboembolism (VTE) is increased in cancer patients. To improve prediction of VTE in cancer patients, we performed a prospective and observational cohort study of patients with newly diagnosed cancer or progression of disease after remission. A previously developed risk scoring model for prediction of VTE that included clinical (tumor entity and body mass index) and laboratory (hemoglobin level and thrombocyte and leukocyte count) parameters was expanded by incorporating 2 biomarkers, soluble P-selectin, and D-Dimer. Of 819 patients 61 (7.4%) experienced VTE during a median follow-up of 656 days. The cumulative VTE probability in the original risk model after 6 months was 17.7% in patients with the highest risk score (≥ 3, n = 93), 9.6% in those with score 2 (n = 221), 3.8% in those with score 1 (n = 229), and 1.5% in those with score 0 (n = 276). In the expanded risk model, the cumulative VTE probability after 6 months in patients with the highest score (≥ 5, n = 30) was 35.0% and 10.3% in those with an intermediate score (score 3, n = 130) as opposed to only 1.0% in patients with score 0 (n = 200); the hazard ratio of patients with the highest compared with those with the lowest score was 25.9 (8.0-84.6). Clinical and standard laboratory parameters with addition of biomarkers enable prediction of VTE and allow identification of cancer patients at high or low risk of VTE.

D-Dimer and Prothrombin Fragment 1 + 2 Predict Venous Thromboembolism in Patients With Cancer: Results From the Vienna Cancer and Thrombosis Study

PURPOSE Venous thromboembolism (VTE) is a well-recognized complication of cancer. Laboratory parameters might be useful to assess the VTE risk in patients with cancer. The aim of this study was to investigate D-dimer and prothrombin fragment 1 + 2 (F 1 + 2), which reflect activation of blood coagulation and fibrinolysis, for prediction of cancer-associated VTE. PATIENTS AND METHODS In a prospective, observational, cohort study of 821 patients with newly diagnosed cancer or progression of disease who did not recently receive chemotherapy, radiotherapy, or surgery were enrolled and followed for a median of 501 days (interquartile range, 255 to 731 days). The malignancies in these patients were as follows: breast (n = 132), lung (n = 119), stomach (n = 35), lower gastrointestinal tract (n = 106), pancreas (n = 46), kidney (n = 22), and prostate (n = 101) cancers; high-grade glioma (n = 102); malignant lymphoma (n = 94); multiple myeloma (n = 17); and other tumor types (n = 47). The study end point was occurrence of objectively confirmed symptomatic or fatal VTE. RESULTS VTE occurred in 62 patients (7.6%). The cutoff level for elevated D-dimer and elevated F 1 + 2 was set at the 75th percentile of the total study population. In multivariable analysis that included elevated D-dimer, elevated F 1 + 2, age, sex, surgery, chemotherapy, and radiotherapy, the hazard ratios (HRs) of VTE in patients with elevated D-dimer (HR, 1.8; 95% CI, 1.0 to 3.2; P = .048) and elevated F 1 + 2 (HR, 2.0; 95% CI, 1.2 to 3.6; P = .015) were statistically significantly increased. The cumulative probability of developing VTE after 6 months was highest in patients with both elevated D-dimer and elevated F 1 + 2 (15.2%) compared with patients with nonelevated D-dimer and nonelevated F 1 + 2 (5.0%; P < .001). CONCLUSION High D-dimer and F 1 + 2 levels independently predict occurrence of VTE in patients with cancer.

Tissue factor-positive microparticles : Cellular origin and association with coagulation activation in patients with colorectal cancer

The pathogenesis of hypercoagulability in cancer is not entirely understood. We hypothesized that in cancer patients circulating tissue factor-positive microparticles (TF (+) MPs) are increased and associated with hemostatic system activation. In 20 patients with advanced colorectal cancer and in 20 age- and sex-matched controls, number and cellular origin of TF (+) MPs were determined in plasma by flow cytometry. D-dimer was determined as an indicator of hemostatic system activation. Compared to controls, the median (interquartile range) number of TF (+) MPs was two-fold higher in cancer patients: 25.9 (15.4 - 42.0) x 10 (3) /ml plasma versus 13.1 (11.9 - 19.7) x 10 (3) /ml plasma, p = 0.007. This was mainly due to a higher amount of TF (+) MPs from platelets (13.4 [5.0 - 17.4] x 10 (3) /ml plasma vs. 5.8 [4.5 - 7.5] x 10 (3) /ml plasma, p = 0.017). TF (+) MPs correlated with D-dimer ( ? = 0.48, p = 0.002). High levels of TF (+) MPs in cancer patients and their correlation with D-dimer suggest that TF (+) MPs might be involved in hemostasis activation in cancer patients.

Leptin Induces Endothelin-1 in Endothelial Cells In Vitro

Leptin, a protein encoded by the obese gene, is produced by adipocytes and released into the bloodstream. In obese humans, serum leptin levels are increased and correlate with the individual’s body mass index and blood pressure. Elevated serum concentrations of endothelin-1 (ET-1), a potent vasoconstrictor and mitogen, were also observed in obese subjects. The pathomechanisms underlying this ET-1 increase in obesity are poorly understood. In the present study, we investigated the influence of the ob gene product leptin on the expression of ET-1 in human umbilical vein endothelial cells (HUVECs). Binding studies using 125I-radiolabeled leptin revealed high- and low-affinity leptin binding sites on HUVECs (Kd1=13.1±3.1 nmol/L and Kd2=1390±198 nmol/L, respectively), mediating a time- and dose-dependent increase of ET-1 mRNA expression and protein secretion after incubation of HUVECs with leptin. This leptin-induced ET-1 expression was inhibited by preincubation of HUVECs with 0.75 &mgr;mol/L antisense phosphorothioate oligonucleotides directed against the leptin receptor Ob-Rb. Furthermore, after incubation with leptin, increased nuclear staining of c-fos and c-jun, the major components of the transcription factor AP-1, and increased AP-1 DNA binding were observed. Transient transfection studies with ET-1 promoter constructs showed that leptin-induced promoter activity was abolished in the absence of AP-1 binding sites or by cotransfection with a plasmid overexpressing a mutated jun, which is able to bind c-fos but not DNA. Thus, leptin upregulates ET-1 production in HUVECs via a mechanism potentially involving jun binding members of the bZIP family.

Risk of pregnancy-associated recurrent venous thromboembolism in women with a history of venous thrombosis

Summary.  Background: Limited data exist on the risk of pregnancy‐associated venous thromboembolism (VTE) in women with a history of VTE. Objective: To evaluate the risk of recurrent pregnancy‐associated thrombosis in women with previous VTE in a large retrospective cohort study. Patients and methods: One hundred and fifty‐nine women with at least one pregnancy (293 pregnancies in total) after a VTE were included into the study. The patients underwent a standardized interview on their history of thrombosis and pregnancy‐associated complications. Results: Eight recurrent events occurred during 197 pregnancies without thrombosis prophylaxis. The probability of VTE during pregnancy without thrombosis prophylaxis was 6.2% (95% confidence interval 1.6–10.9%). The risk was constant over the whole period of pregnancy. Of the eight women with VTE during pregnancy four had heterozygous FV:R506Q, two in combination with hyperhomocysteinemia. No VTE occurred during 87 pregnancies with thrombosis prophylaxis. In the postpartum period 15 VTEs occurred, two of 83 (2.4%) after pregnancy termination, one of 53 (1.9%) after miscarriage, three of 10 (30%) after stillbirth and nine of 138 (6.5%) after live birth. Conclusions: Without thrombosis prophylaxis the risk for recurrent symptomatic VTE is substantial during the whole period of pregnancy in women with previous VTE. The majority of events occurred after delivery, reflecting the very high risk during the postpartum period. Prospective and comparative trials to ascertain efficacy and safety of prophylactic heparin are urgently needed.

Validation of rotation thrombelastography in a model of systemic activation of fibrinolysis and coagulation in humans

Summary.  Background: Thrombelastography (TEG) is a whole blood assay to evaluate the viscoelastic properties during blood clot formation and clot lysis. Rotation thrombelastography (e.g. ROTEM®) has overcome some of the limitations of classical TEG and is used as a point‐of‐care device in several clinical settings of coagulation disorders. Endotoxemia leads to systemic activation of the coagulation system and fibrinolysis in humans. Objectives: We validated whether ROTEM® is sensitive to endotoxin induced, tissue factor‐triggered coagulation and fibrinolysis and if its measures correlate with biohumoral markers of coagulation and fibrinolysis. Patients and methods: Twenty healthy male volunteers participated in this randomized placebo‐controlled trial. Volunteers received either 2 ng kg−1 National Reference Endotoxin or saline. Results: Endotoxemia significantly shortened ROTEM® clotting time (CT) by 36% (CI 0.26–0.46; P < 0.05) with a strong inverse correlation with the peak plasma levels of prothrombin fragments (F1 + 2) (r = −0.83, P < 0.05). Additionally, endotoxin infusion enhanced maximal lysis (ML) 3.9‐fold (CI: 2.5–5.2) compared with placebo or baseline after 2 h (P < 0.05). Peak ML and peak tissue plasminogen activator (t‐PA) values correlated excellently (r = 0.82, P < 0.05). ROTEM® parameters clot formation time and maximal clot firmness were not affected by LPS infusion, whereas platelet function analyzer (PFA‐100) closure times decreased. Conclusions: Rotation thrombelastography (ROTEM®) detects systemic changes of in vivo coagulation activation, and importantly it is a point of care device, which is sensitive to changes in fibrinolysis in humans. The ex vivo measures CT and ML correlate very well with established in vivo markers of coagulation activation (F1 + 2) and fibrinolysis (t‐PA), respectively.

High D-dimer levels are associated with poor prognosis in cancer patients

Background Systemic activation of hemostasis is frequently observed in cancer patients, even in the absence of thrombosis. Moreover, this activation has been implicated in tumor progression, angiogenesis and metastatic spread. Increased levels of D-dimer, which is a degradation product of cross-linked fibrin, indicate a global activation of hemostasis and fibrinolysis. Design and Methods In a prospective and observational cohort study, we assessed the prognostic value of D-dimer levels for overall survival and mortality risk in 1178 cancer patients included in the Vienna Cancer and Thrombosis Study (CATS). Patients were followed over 2 years at regular intervals until occurrence of symptomatic venous thromboembolism or death. D-dimer levels were measured with a quantitative D-dimer latex agglutination assay Results The main solid tumors were malignancies of the lung (n=182), breast (n=157), lower gastrointestinal tract (n=133), pancreas (n=74), stomach (n=50), kidney (n=37), prostate (n=133), and brain (n=148); 201 of the patients had hematologic malignancies; 63 had other tumors. During a median follow-up of 731 days, 460 (39.0%) patients died. The overall survival probabilities for patients with D-dimer levels categorized into four groups based on the 1st, 2nd and 3rd quartiles of the D-dimer distribution in the total study population were 88%, 82%, 66% and 53% after 1 year, and 78%, 66%, 50% and 30% after 2 years, respectively (P<0.001). The univariate hazard ratio of D-dimer (per double increase) for mortality was 1.5 (95% confidence interval: 1.4–1.6, P<0.001) and remained increased in multivariable analysis including tumor subgroups, age, sex and venous thromboembolism. Conclusions High D-dimer levels were associated with poor overall survival and increased mortality risk in cancer patients.

Morning Hypercoagulability and Hypofibrinolysis Diurnal Variations in Circulating Activated Factor VII, Prothrombin Fragment F1+2, and Plasmin–Plasmin Inhibitor Complex

BACKGROUND Diurnal fluctuations of blood coagulation and fibrinolysis activity are thought to play a role in the observed circadian variation in the frequency of onset of acute cardiovascular events. In the present study, the diurnal variations in blood coagulation and fibrinolysis activity were investigated in 10 young, healthy control subjects by use of specific molecular activation markers. METHODS AND RESULTS The plasma levels of activated factor FVII (FVIIa), the active portion of the main coagulation activator, decreased during the day (8 AM: 2.03 ng/mL, CI 1.16 to 2.88 ng/mL; 8 PM: 1.16 ng/mL, CI 0.81 to 1.5 ng/mL; P = .005), whereas FVII antigen did not change significantly. In parallel with the diurnal variations of FVIIa, we found a decrease of prothrombin fragment F1+2 (8 AM: 0.97 nmol/L, CI 0.79 to 1.15 nmol/L; 8 PM: 0.78 nmol/L, CI 0.64 to 0.93 nmol/L; P = .005), a molecular marker of intravasal thrombin generation. Evidence for a possible functional relevance of circulating FVIIa was found because this parameter was significantly correlated with prothrombin fragment F1+2 in 72 fasting healthy individuals (r = .29, P = .011). Plasminogen activator inhibitor-1 levels decreased (8 AM: 9.9 ng/mL, CI 7.7 to 12.1 ng/mL; 8 PM: 5.4 ng/mL, CI 3.8 to 6.9 ng/mL; P < .005), whereas plasmin-plasmin inhibitor complex levels, representing the degree of intravascular plasmin generation, concomitantly increased (8 AM: 235 micrograms/L, CI 198 to 272 micrograms/L; 8 PM: 449 micrograms/L, CI 391 to 507 micrograms/L; P = .008). CONCLUSIONS Our data suggest that the diurnal changes in the plasma levels of activators and inhibitors of coagulation and fibrinolysis lead to corresponding changes in the activity state of these systems, leading to morning hypercoagulability and hypofibrinolysis.

The risk of recurrent venous thromboembolism among patients with high factor IX levels

Summary.  High factor IX (FIX) is a risk factor of deep vein thrombosis. The impact of high FIX on the risk of recurrent venous thrombosis is unknown. We prospectively followed 546 patients after anticoagulation for a first spontaneous venous thromboembolism. Patients with a natural coagulation inhibitor deficiency, lupus anticoagulant or cancer were excluded. At 3 years, the likelihood of recurrence was 23% among patients with high FIX (exceeding the 75th percentile) compared with 11% among patients with lower levels. Among patients with high FIX, the relative risk of recurrence was 2.2 (95% CI: 1.3–3.6) before and was 1.6 (95% CI: 1.0–2.8) after adjustment for age, gender, duration of anticoagulation, FV Leiden, FII G20210A, high FVIII and hyperhomocysteinemia. Compared with patients with low factor IX (< 138 IU dL−1) and low FVIII (≤ 234 IU dL−1), the relative risk of recurrence was 1.5 among patients with high FIX and low FVIII, 2.7 among patients with low FIX and high FVIII and 6.6 among patients with high FIX and high FVIII. High levels of FIX confer an increased risk of recurrent venous thromboembolism and enhance the risk of recurrence among patients with high FVIII.