Tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in amniotic fluid and blood plasma: implications for the mechanism of amniotic fluid embolism

Placental vascular pathology and increased thrombin generation as mechanisms of disease in obstetrical syndromes

“…In contrast to the changes detected in the amniotic fluid and the decidua, the median maternal plasma immunoreactive TF concentration of normal pregnant women do not differ significantly from that of non-pregnant patients 3,25 . However, labor at term increases significantly the maternal plasma immunoreactive TF concentration in comparison to the non-pregnant state 20 . In addition to the changes in TF, normal pregnancy is associated with increased thrombin generation 3,8 , as determined by the elevation of maternal concentrations of fibrinopeptide A, prothrombin fragments (PF) 1 and 2, and thrombin-antithrombin (TAT) III complexes 7,[26][27][28] .…”

“…The principal anticoagulant mechanism inhibiting TF activation pathway is tissue factor pathway inhibitor (TFPI), which mRNA is highly expressed in the macrophages in the villi in term placenta 19 . Similarly, high TF concentrations have been detected in the fetal membranes (mainly the amnion) and amniotic fluid 7,[20][21][22][23] . TFPI has been found in amniotic fluid as well 20 , but it is not clear if the presence of TF and its natural inhibitor is related to coagulation per se or is somehow connected with embryonic development 24 .…”

“…Similarly, high TF concentrations have been detected in the fetal membranes (mainly the amnion) and amniotic fluid 7,[20][21][22][23] . TFPI has been found in amniotic fluid as well 20 , but it is not clear if the presence of TF and its natural inhibitor is related to coagulation per se or is somehow connected with embryonic development 24 . In contrast to the changes detected in the amniotic fluid and the decidua, the median maternal plasma immunoreactive TF concentration of normal pregnant women do not differ significantly from that of non-pregnant patients 3,25 .…”

“…TFPI inhibits thrombin generation through the inactivation of activated factor X and the factor VIIa/TF complex 60,62 . The mean maternal plasma concentrations of total TFPI increases during the first half of pregnancy, remains relatively constant in the second half 63 and decreases during labor 20 . There are two types of TFPI: 1) TFPI-1 is the more prevalent form in the non-pregnant state in the maternal circulation and can also be found in the fetal blood, platelets, endothelial cells and other organs 19,64 ; and 2) TFPI-2-the major form of TFPI in the placenta [65][66][67][68] , also known as Placental Protein 5 (PP5) 69,70 .…”

“…During normal pregnancy, there is an increase in the amniotic fluid TF concentration 7,[20][21][22][23] . In .…”