Regulation of cardiomyocyte full-length tissue factor expression and microparticle release under inflammatory conditions in vitro.
BACKGROUND
Myocardial inflammation is associated with an increase in circulating microparticles (MPs) and procoagulability.


OBJECTIVE
We determined whether acute inflammation was associated with altered full-length tissue factor (flTF) expression and increased procoagulability in cardiomyocytic cells.


METHODS
This study examined the transcriptional regulation of flTF expression in murine cardiomyocytic (HL-1) cells. Also, the generation of MPs by HL-1 cells and their ability to diffuse through an artificial endothelium was evaluated.


RESULTS
Constitutive and tumor necrosis factor-alpha (TNF-alpha)-induced flTF expression of HL-1 was reduced when c-Jun N-terminal kinase (JNK) was inhibited. Tissue factor (TF)-positive procoagulant MPs were released from HL-1 cells in response to TNF-alpha. JNK inhibition potentiated the release of MPs from HL-1 cells without affecting MP-associated TF activity. MP generation was dependent on RhoA activation and associated with a reorganization of the actin cytoskeleton. Increased diffusion of HL-1-derived MPs through an endothelial monolayer was found after TNF-alpha treatment. The increased diffusion was dependent not only on TNF-alpha but also on HL-1-released mediators.


CONCLUSIONS
Full-length TF expression in HL-1 cells was regulated through JNK. The TNF-alpha-induced increase in procoagulability was mediated through RhoA-dependent release of flTF-bearing MPs. These MPs were able to diffuse through an endothelial barrier adjacent to HL-1 cells and increased the procoagulability of the extracellular endothelial space. Cardiomyocytes seem to be a likely source of flTF-bearing procoagulant MPs.
Antoniak
S
S
Department of Cardiology and Pneumology, CharitéCentrum 11 - Herz-, Kreislauf- und Gefässmedizin, Charité- Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
Boltzen
U
U
Eisenreich
A
A
Stellbaum
C
C
Poller
W
W
Schultheiss
H P
HP
Rauch
U
U
D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D018920:Coculture Techniques; D007249:Inflammation / Q000378:metabolism*; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013925:Thromboplastin / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000199:Actins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D013925:Thromboplastin