Factor Seven Activating Protease (FSAP) levels during normal pregnancy and in women using oral contraceptives

IntroductionFactor seven activating protease (FSAP) is a plasma serine protease involved in haemostasis and remodeling processes. We have investigated whether pregnancy or the use of oral contraceptives (OCs) influences circulating FSAP levels. The effect of female sex hormones on FSAP expression in cultured cells was also determined.Materials and MethodsFSAP levels and activity was measured in plasma samples obtained at different gestation stages from healthy pregnant women (n = 101), from non-pregnant women, pre-menopausal women who currently use OCs (n = 48), and non-pregnant women who did not use OCs (n = 69).ResultsIn late pregnancy the plasma FSAP antigen (median 2.28 PEU/ml [range 1.11 to 2.62 PEU/ml]; p < 0.001 vs control group) and activity (median 2.98 PEU/ml [range 1.05 to 4.24 PEU/ml]; p < 0.001 vs control group) was significantly higher compared with levels in non-pregnant women and remained elevated after delivery. Plasma FSAP levels in women using OCs was also significantly elevated compared to the control group. Ex vivo experiments demonstrated enhanced FSAP expression in monocytes isolated from women using OCs. In vitro experiments showed that FSAP mRNA levels were strongly induced by estradiol in monocytes but not in hepatocytes.ConclusionsIncreased levels of circulating FSAP in pregnancy and in women using OCs indicate that hormonal status critically influences FSAP expression. Hormonal influences could be observed in monocytes in vivo and ex-vivo but not in hepatocytes indicating cell-specific regulation. Future studies designed to investigate the role of FSAP in haemostasis and remodeling processes should consider the role of female sex hormones on FSAP expression.