Print Email Facebook Twitter Different effects of lipopolysaccharide on plasminogen activator inhibitor-1 production in aortic media in vivo and in culture Title Different effects of lipopolysaccharide on plasminogen activator inhibitor-1 production in aortic media in vivo and in culture Author van Leeuwen, R.T.J. Quax, P.H.A. Tippins, J.R. Antoniw, J.W. Andreotti, F. Maseri, A. Kluft, C. Sperti, G. Gaubius Instituut TNO Publication year 1996 Abstract Background: Lipopolysaccharide (endotoxin) has been shown to increase the expression of plasminogen activator inhibitor type-1 (PAI-1) in the vessel wall. Endotoxin is known to increase PAI-1 production in endothelial cells, but its action on smooth muscle cells (SMCs) is presently not clear. In this study we determined the effect of endotoxin on PAI-1 and tissue plasminogen activator (t-PA) production by aortic SMCs in vivo in two animal species, and in culture. Methods: The aortas of Sprague Dawley rats and of New Zealand White rabbits were rapidly excised after parenteral administration of endotoxin. Total RNA was extracted from the aortic media, and PAI-1 and t-PA mRNA levels were quantified after Northern blotting. In addition, cultured rat aortic SMCs were treated with endotoxin. PAI activity in the conditioned medium was determined with a spectrophotometric assay, and total RNA was extracted from the cells and analyzed. Results: A rapid and strong induction in the aortic media of PAI-1 mRNA was observed by endotoxin in both rat (50 mg/kg) and rabbit (1 mg/kg). t-PA mRNA was barely detectable and was not increased by endotoxin. Studies in cultured SMCs showed low expression of PAI-1 mRNA under serum-free conditions and little PAI activity in the cell-conditioned medium. Endotoxin did not increase the levels of PAI-1 mRNA nor PAI activity under serum-free conditions. The effect of endotoxin (10 mg/ml) in the presence of 10% (v/v) newborn calf serum on PAI-1 mRNA was negligible; PAI activity, however, increased by 50.3 ± 7.3% compared with controls. mRNA levels of t-PA and low-density lipoprotein/receptor-related protein/α2-macroglobulin receptor also increased after endotoxin administration. PAI activity was identified as PAI-1 by immunoblotting. Fibrin zymography showed that t-PA was present only in complex with PAI-1. Conclusions: A strong increase in PAI-1 gene expression by endotoxin was observed in aortic SMCs in vivo but not in culture. This suggests that the effect of endotoxin on SMCs is indirect. The fibrinolytic/proteolytic potential of the SMCs in the vessel wall is likely to have important implications for the migration of cells during vessel wall remodeling, such as neointima formation, during tumor cell metastasis, and for the fate of intramural thrombi. © Kluwer Academic Publishers. Chemicals/CAS: alpha 2 macroglobulin, 95568-41-5; fibrin, 9001-31-4; plasminogen activator inhibitor 1, 140208-23-7; RNA, 63231-63-0; tissue plasminogen activator, 105913-11-9 Subject BiologyEndotoxinPlasminogen activator inhibitor-1RabbitRatSmooth muscleTissue-type plasminogen activatoralpha 2 macroglobulinendotoxinfibrinlipopolysaccharidelow density lipoprotein receptormessenger rnaplasminogen activator inhibitor 1rnatissue plasminogen activatoranimal cellanimal experimentanimal modelaorta mediaarticleblood vessel wallcell culturecell migrationcontrolled studyculture mediumgene expressionimmunoblottingintimametastasisnonhumannorthern blottingpriority journalprotein degradationrabbitratspectrophotometrythrombusvascular endotheliumvascular smooth muscle To reference this document use: http://resolver.tudelft.nl/uuid:7c23684c-409a-43fb-8a10-920c350955d5 TNO identifier 233580 ISSN 0929-5305 Source Journal of Thrombosis and Thrombolysis, 3 (3), 215-223 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.