Am. J. Respir. Cell Mol. Biol., Vol 17, No. 2, 08 1997, 164-172.
Tissue factor expression in mesothelial cells: induction both in vivo and in vitro
KD Bottles, Z Laszik, JH Morrissey and GT Kinasewitz
Department of Medicine, Pulmonary and Critical Care Medicine, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
Exudative pleural effusions are characterized by a high protein content and
frequently progress to loculation and fibrosis. To test the hypothesis that
tissue factor (TF) plays an integral role in this process, we investigated
the expression of TF by human mesothelial cells (HMC) both in vivo and in
vitro, and measured the effect of serum on HMC expression of TF in vitro.
In vivo TF expression was not detected in HMC of normal pleura, but was
detected in HMC of pleura overlying inflamed lung. In vitro, quiescent HMC
demonstrated negligible levels of TF expression; however, upon serum
stimulation there was a marked induction in both TF protein level and
activity, peaking at 8-9 h. In contrast, treating quiescent HMC with plasma
resulted in a further small, but significant, decrease in TF expression.
This serum-induced rise in TF was also reflected in TF mRNA levels and did
not require de novo protein synthesis. These results suggest that induction
of HMC TF expression may be important in triggering both the intrapleural
activation of prothrombin and the deposition of fibrin characteristic of
inflammatory effusions.
