Plasma and IgGs from patients with lupus anticoagulant induce tissue factor in monocytes: a possible risk factor for thrombosis

The role of beta-2-glycoprotein I in health and disease associating structure with function: More than just APS

Beta-2-Glycoprotein I (β2GPI) plays a number of essential roles throughout the body. β2GPI, C-reactive protein and thrombomodulin are the only three proteins that possess the dual capability to up and down regulate the complement and coagulation systems depending upon external stimulus. Clinically, β2GPI is the primary antigen in the autoimmune condition antiphospholipid syndrome (APS), which is typically characterised by pregnancy morbidity and vascular thrombosis. This protein is also capable of adopting at least two distinct structural forms, but it has been argued that several other intermediate forms may exist. Thus, β2GPI is a unique protein with a key role in haemostasis, homeostasis and immunity. In this review, we examine the genetics, structure and function of β2GPI in the body and how these factors may influence its contribution to disease pathogenesis. We also consider the clinical implications of β2GPI in the diagnosis of APS and as a potentially novel therapeutic target.

Prognostic significance of the absolute monocyte counts in lung cancer patients with venous thromboembolism

We investigated the clinical significance of the absolute monocyte count (AMC) as a predictor of the response to anticoagulation and survival in lung cancer patients with venous thromboembolism (VTE). We retrospectively reviewed 1707 patients with pathologically proven lung cancer who visited the hospital between July 2008 and May 2014. Among them, the clinical data of patients newly diagnosed with VTE and treated with anticoagulation were compared between the low and high AMC groups according to the median value of AMC (640/μL) at the time of VTE diagnosis. The incidence of VTE was 7.9 % during the study period. Most of the patients had non-small-cell lung cancer (82.1 %), stage IV (64.2 %), and pulmonary thromboembolism (76.1 %) and were incidentally diagnosed with VTE (76.9 %). The patients' characteristics and laboratory values were not significantly different between the low and high AMC groups. Among patients available for evaluation of the response to anticoagulation, the high AMC group was significantly more refractory to anticoagulation than the low AMC group (no response to anticoagulation, 21.7 vs. 6.8 %, respectively; p = 0.044). Additionally, the high AMC group showed worse overall survival (OS) than the low AMC group (median, 9.6 vs. 5.9 months; p = 0.038). On multivariate analysis, high AMC, low albumin, and advanced stage were independent poor prognostic factors for OS. High AMC is associated with refractoriness to anticoagulation and poor prognosis in lung cancer patients with VTE.

Improvement of adequate use of warfarin for the elderly using decision tree-based approaches

OBJECTIVES

Due to the narrow therapeutic range and high drug-to-drug interactions (DDIs), improving the adequate use of warfarin for the elderly is crucial in clinical practice. This study examines whether the effectiveness of using warfarin among elderly inpatients can be improved when machine learning techniques and data from the laboratory information system are incorporated.

METHODS

Having employed 288 validated clinical cases in the DDI group and 89 cases in the non-DDI group, we evaluate the prediction performance of seven classification techniques, with and without an Adaptive Boosting (AdaBoost) algorithm. Measures including accuracy, sensitivity, specificity and area under the curve are used to evaluate model performance.

RESULTS

Decision tree-based classifiers outperform other investigated classifiers in all evaluation measures. The classifiers supplemented with AdaBoost can generally improve the performance. In addition, weight, congestive heart failure, and gender are among the top three critical variables affecting prediction accuracy for the non-DDI group, while age, ALT, and warfarin doses are the most influential factors for the DDI group.

CONCLUSION

Medical decision support systems incorporating decision tree-based approaches improve predicting performance and thus may serve as a supplementary tool in clinical practice. Information from laboratory tests and inpatients' history should not be ignored because related variables are shown to be decisive in our prediction models, especially when the DDIs exist.

Human platelets do not express tissue factor

BACKGROUND

The controversy about the expression of tissue factor (TF) in platelet after de novo synthesis prevail despite many groups recognize that platelet isolation, assays and reagents, particularly non-specific antibodies, may account for the diversity. In this study the potential of TF expression was evaluated using immune-purified human platelets and employing a very sensitive and highly specific TF activity assay.

METHODS

Isolated platelets in plasma anti-coagulated with Fragmin were subjected to stimulation by LPS plus PMA, IgG antibody or TRAP and tested for TF activity.

RESULTS

Platelets stimulated with LPS plus PMA for 4 hours expressed trace amounts of TF like activity (PCA), not inhibited by anti-TF antibody (0.2±0.1 mU/ml blood). Platelets, not immune-adsorbed to remove monocytes, showed significant TF activity (2.0±0.9 mU/ml blood) that was nearly abolished by anti-TF antibody. IgG antibody from patient with lupus anticoagulant failed to enhance the trace amount of PCA as compared to the control in contrast to high TF activity induced in monocytes (0.4±0.1 mU/ml blood versus 27.5±10.5 mU/10(6) cells) showing that activation of complement is not mediating TF expression. Platelet subjected to TRAP activation for 10 min possessed only trace amounts of PCA that was not inhibited by anti-TF antibody and slightly enhanced by anti-TFPI antibody.

CONCLUSIONS

It is concluded that platelets free of monocytes do not express TF activity when stimulated by LPS or activated complement factors, implying no role for Toll like receptor (TLR4) as suggested recently. There is no evidence of TF activity associated with platelets as a result of rapid and dynamic process.

Tissue factor/TFPI and blood cells

Vascular injury-induced access of blood to tissue factor (TF) leads to the formation of a TF-FVII/FVIIa complex and the triggering of blood coagulation. The activated TF-dependent pathway is regulated by Tissue Factor Pathway Inhibitor (TFPI), which binds and inhibits FXa, but more importantly forms an inactive quaternary complex with TF-FVIIa-FXa, effectively shutting off the TF activity. The old view of TF residing in extravascular sites exclusively has recently been challenged by several reports on TF expression in various blood cells. The latter arena has unfortunately been marred by many contradictions, apparently related to inferior tools and/or study design, notably the widespread use of antibodies with inferior and misleading specificity and TF activity assays of low sensitivity/specificity. Our own studies along with many other reports, compels the conclusion that in blood of healthy individuals TF is exclusively associated with and expressed in circulating monocytes. In this short review the distribution of TF and TFPI in blood is discussed.