Fibronectin‐adherent monocytes express tissue factor and tissue factor pathway inhibitor whereas endotoxin‐stimulated monocytes primarily express tissue factor: physiologic and pathologic implications

Abstract

To cite this article: Bajaj MS, Ghosh M, Bajaj SP. Fibronectin-adherent monocytes express tissue factor and tissue factor pathway inhibitor whereas endotoxin-stimulated monocytes primarily express tissue factor: physiologic and pathologic implications. J Thromb Haemost 2007; 5: 1493-9.Summary. Background: Monocytes are critical cells in initiating physiologic and/or pathologic tissue factor (TF)-induced intravascular and extravascular coagulation. Monocytes constitutively express small amounts of TF and tissue factor pathway inhibitor (TFPI). Non-adherent lipopolysaccharide (LPS)-stimulated monocytes express significant amounts of TF; however, increased expression of TFPI by these cells is controversial. Further, whether fibronectin-adherent monocytes (mimicking conditions in the extravascular space) express sufficient TFPI to inhibit TF-procoagulant activity (PCA) is unknown. Objective: To compare TF and TFPI expression by fibronectin-adherent and LPS-stimulated non-adherent monocytes. Methods: Monocytes were isolated from normal peripheral blood, adhered to fibronectin or stimulated with lipopolysaccharide (LPS) under non-adherent conditions and examined for expression of TF and TFPI using quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), ELISA and factor X (FX) activation. Results: Under LPS-free conditions, the fibronectin-adherent monocyte TF mRNA, antigen and activity were markedly upregulated. Notably, cell and microparticle (MP)-associated TF and alternatively spliced TF (asTF) were all upregulated. TFPI mRNA and antigen were also upregulated in the fibronectinadherent monocytes, which significantly inhibited TF-PCA. TFPI mRNAs for both alpha and beta forms were detected. The peak in TFPI activity occurred in tandem with the peak in TF-PCA. In contrast, LPS-stimulated monocytes, which expressed cell and MP-associated TF and asTF, demonstrated only minimal expression of TFPI as determined by mRNA, antigen or inhibition of TF activity. Conclusion: Both LPSstimulated and fibronectin-adherent monocytes demonstrate a procoagulant phenotype by expressing TF but only fibronectinadherent monocytes express significant amounts of TFPI to control thrombin generation and fibrin formation in the context of extravascular space.

Structural and Functional Studies of γ-Carboxyglutamic Acid Domains of Factor VIIa and Activated Protein C: Role of Magnesium at Physiological Calcium

“…Monocytes were isolated from heparinized venous blood drawn from healthy donors as described previously. 53 The preparation contained 90–95% monocytes as identified by the non-specific esterase activity, 54 with 95% viability using the Trypan Blue exclusion method. 55 Monocytes were cultured at 37 °C with 5% CO 2 using RPMI-1640 medium containing 15% fetal calf serum.…”

A new assay to evaluate microvesicle plasmin generation capacity: validation in disease with fibrinolysis imbalance

“…LMVs have been primarily ascribed procoagulant properties because of the tissue factor (TF) exposure [18,19] together with procoagulant phospholipids such as phosphatidylserine (PS). However, anticoagulant proteins are also present on the surface of LMVs, including thrombomodulin [20], endothelial protein C receptor [21] and TF pathway inhibitor (TFPI) [22]. Moreover, LMVs have been more recently described to have plasmin generation capacity (MV-PGC) [6,23].…”

Leukocyte-Derived Microparticles in Vascular Homeostasis

“…45 MPs derived from endotoxin-stimulated monocytes also express TF pathway inhibitor (TFPI). 48 TFϩ MonoMPs constitute the second largest pool of thrombogenic MPs after plateletderived MPs (PMPs). 49 -51 TFϩ MonoMPs can interact with neutrophils, 52 transferring to them a procoagulant activity.…”