Modulation of procoagulant and fibrinolytic system components of mesothelial cells by inflammatory mediators.
Human peritoneal mesothelial cells (HMC) play a critical role in maintaining the intraperitoneal balance between fibrinolysis and coagulation by expressing the fibrinolytic enzyme tissue-type plasminogen activator (t-PA) as well as a specific plasminogen activator inhibitor, PAI-1, and the procoagulant protein tissue factor (TF). Of three compounds known to stimulate t-PA synthesis in cultured human endothelial cells, i.e., retinoic acid, the protein kinase C activator 4 beta-phorbol 12-myristate 13-acetate (PMA), and sodium butyrate, only butyrate (1 mM) caused about a threefold increase in t-PA synthesis and mRNA expression in HMC after 24 h of incubation, without markedly affecting PAI-1 synthesis. PMA (10 nM) induced a threefold increase in urokinase-type plasminogen activator (u-PA) mRNA, but u-PA antigen levels in the HMC conditioned media remained below the detection level (0.5 ng/ml), possibly as a result of rapid uptake and degradation by the u-PA receptor. The u-PA receptor mRNA levels were about fivefold enhanced above control levels after PMA treatment of the cells. An increase in intracellular adenosine 3',5'-cyclic monophosphate levels by forskolin (10 microM) diminished t-PA and PAI-1 levels 43 and 17%, respectively. Among the inflammatory mediators tested [tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha, and bacterial lipopolysaccharide], TNF-alpha (10-1,000 U/ml) showed the strongest procoagulant effects. We found that the isoflavone compound genistein (25 micrograms/ml) prevented the TNF-alpha-induced expression of PAI-1 and TF while also slightly counteracting the decrease in t-PA synthesis. The protein kinase C inhibitor R0-318220 (3 microM) only moderately opposed the TNF-alpha-induced changes in t-PA and PAI-1 synthesis but completely prevented the induction of TF mRNA. In summary, our results demonstrate that t-PA synthesis in HMC is relatively insensitive to pharmacological stimulation. To restore the balance between fibrinolysis and coagulation under inflammatory conditions, attempts to interfere with the TNF-alpha-signaling pathway were more successful.
Sitter
T
T
Department of Medicine, Klinikum Innenstadt, University of Munich, Germany.
Toet
K
K
Fricke
H
H
Schiffl
H
H
Held
E
E
Kooistra
T
T
D001777:Blood Coagulation / Q000187:drug effects*; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005342:Fibrinolysis / Q000187:drug effects*; D019833:Genistein; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology*; D007529:Isoflavones / Q000494:pharmacology; D010537:Peritoneum / Q000166:cytology / Q000378:metabolism*; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000494:pharmacology; D013268:Stimulation, Chemical; D013925:Thromboplastin / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D018836:Inflammation Mediators; D007529:Isoflavones; D017395:Plasminogen Activator Inhibitor 1; D013925:Thromboplastin; D019833:Genistein; D011493:Protein Kinase C; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator