Jana Prochazkova

The pathophysiology of endothelial function in pregnancy and the usefulness of endothelial markers.

AIM The aim of this study was to assess coagulation markers of endothelial damage and examine new markers of endothelial activation such as matrix metalloproteinases (MMPs) in a group of healthy pregnant women. Matrix metalloproteinase (MMP)-2, in particular, plays a major role in the degradation of the extracellular matrix confirming its essential function in both the survival (angiogenesis) and death of endothelial cells. Detection of specific coagulation factors, mainly released from the vascular endothelium such as vWF, sTM (soluble thrombomodulin) and ePCR (endothelial protein C receptor) and factors dependent on endothelial activation such as t-PA and PAI-1, could provide information on possible endothelial dysfunction and help differentiate pregnant patients with an altered thrombotic state. METHODS Healthy pregnant women underwent complete assessment for endothelial damage (as vWF, vWF activity, sTM, ePCR, EMP, MMP-2, MMP-9 and TIMP-2) using the ELISA and other methods. RESULTS AND CONCLUSIONS The results show that endothelial activation during pregnancy is different from that in other pathological conditions involving endothelial damage and typically characterized by higher levels of both coagulation endothelial markers and MMPs. In pregnancy, changes in extracellular matrix composition and matrix metalloproteinase activity also occur and promote vascular remodeling but, only in the uterus. Predisposing risk factors for epithelial dysfunction, and vascular mediators associated with vascular remodeling must be assessed from concentrations in whole blood. The levels of MMPs are not increased in the circulation and the local situation in the uterus cannot be monitored this way. However, MMP-2 processes and modulates the functions of many other vasoactive and pro-inflammatory molecules including adrenomedullin, big endothelin-1, calcitonin gene-related peptide, CCL7/MCP-3, CXCL12/SDF-1, galectin-3, IGFBP-3, IL-1 Beta, S100A8, and S100A9. These molecules represent new potential molecular markers of endothelial damage during pregnancy.

The role of tissue factor in normal pregnancy and in the development of preeclampsia: A review

BACKGROUND Tissue factor (TF) is a key element for normal gestation, especially in the first trimester. TF levels are hence raised in pregnancy, producing an adaptive hypercoagulable state. Potentiated hypercoagulability however, is associated with disorders of pregnancy such as pre-eclampsia but the results of TF and its inhibitor, tissue factor pathway inhibitor (TFPI), measurement, in pre eclampsic women are ambiguous and the data conflicting. This review covers the current knowledge status of the role of TF assessment in pregnancy with a focus on its diagnostic utility. METHODS A review of the literature using the following key words: tissue factor, thrombosis, inflammation, pregnancy, preeclampsia. RESULTS The published literature shows raised and unchanged TF levels in various studies of pre-eclampsia along with equally conflicting data for TFPI. The various study designs and methods used in these studies makes valid comparison difficult. Meta analysis of 34 randomized trials showed that low-dose aspirin in early phases of gravidity (starting from the 16th week or earlier) significantly reduces the incidence of preeclampsia. CONCLUSIONS Overall, the results of the literature search together with knowledge of the structure and biological effects of TF, suggest that measuring the level of plasma TF/TFPI is not ideal for determining the actual levels of TF in the uteroplacental circulation. The current view that endothelial dysfunction is the trigger for preeclampsia, suggests that aspirin may be an effective prophylaxis. Further research will be necessary: measuring the expression of tissue factor on monocytes using flowcytometry and comparing the development of this expression during normal pregnancy and pregnancy complicated by preeclampsia, for example. Another possibility is immunohistochemical determination of the level of TF expression directly in placental tissue.

Validation of a New Panel of Automated Chemiluminescence Assays for Anticardiolipin Antibodies in the Screening for Antiphospholipid Syndrome

BACKGROUND Antibodies anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) are two of three laboratory criteria of antiphospholipid syndrome (APS). All of assays of antiphospholipid antibodies (aPL), coagulation assays as well as ELISAs, show methodological shortcomings, that affect their sensitivity and specificity. Therefore, we decided to validate these parameters for a new chemiluminescent examination (CLIA). METHODS aCL and aβ2GPI antibodies were measured by ELISAs (AIDA, Bad Kreuznach, Germany) and aβ2GPI with CLIA kits (Werfen, Barcelona, Spain). RESULTS When we evaluated both assays, the coefficient of variation for CLIA was slightly lower (9.04 - 12.74%) than for ELISA (11.05 - 15.3%) and the LOD was 0.2 U/L. The dilution series showed significant linearity for all CLIA methods, aCL IgG, aCL IgM, aβ2GPI IgG, and aβ2GPI IgM (0 - 3000 U/L), and method comparison studies revealed good agreement with the currently used ELISA (Kappa values ranging 0.534 - 0.936) without determination of aβ2GPI IgG. The determination aβ2GPI IgG by CLIA method shows higher positivity in 31 samples. These new aCL IgG, aCL IgM, aβ2GPI IgG, and aβ2GPI IgM tests have excellent analytical characteristics and allow fully automated and simultaneous analysis on an analyzer. CONCLUSIONS Chemiluminescent determination of an automated analyzer can improve the fundamental parameters of tests such as reproducibility between laboratories.

Possibility of Coagulation System Activation Determination with Tissue Factor in Pregnancy Complications

BACKGROUND In this part of the study, where we determined the causes of preeclampsia and other obstetric complications, we focused on the role of tissue factor (TF) in the activation of these pathophysiological processes. Recent findings attribute a significant part of the activation of coagulation creation of autoantibodies. Once this mechanism is activated, the antibodies induce expression of tissue factor (TF, CD142) on monocytes and vascular endothelial cells. METHODS We have proposed a monitor activation model of the coagulation system in preeclampsia and other pregnancy complications using TF expression on monocytes by flow cytometry and simultaneous determination the TF-induced thrombin generation in plasma. To determine expression of tissue factor (CD142) on monocytes, we proposed a method of multicolor flow cytometry using anti CD45 PerCP, anti CD14 APC, anti CD16b FITC, and anti CD142 PE antibodies and the corresponding isotype controls. RESULTS We verified the model on patients with severe antiphospholipid syndrome, which is a high expression of antibodies, in particular against beta-2GPI. CONCLUSIONS We demonstrated complete inhibition of TF expression on monocytes and a significant reduction of thrombin generation in plasma.