title: Evidence that postoperative fibrinolytic shutdown is mediated by plasma factors that stimulate endothelial cell type I plasminogen activator inhibitor biosynthesis.
abstract: Postoperative fibrinolytic shutdown has been attributed to an increase in plasma levels of type I plasminogen activator inhibitor (PAI-1) activity and may contribute to postoperative venous thrombosis. The purpose of this study was to determine whether the postoperative increase in PAI-1 is contributed to by a plasma mediator(s) that stimulates PAI-1 synthesis and secretion by vascular endothelium. Plasma samples collected from patients (N = 11) before and after surgery for total hip replacement were (1) assayed for endogenous plasma PAI-1 antigen and activity, and (2) incubated with cultured human umbilical vein endothelial cells (HUVECs) and PAI-1 antigen and activity measured in the conditioned medium (CM). Eighteen hours after surgery, endogenous plasma levels of PAI-1 antigen and activity were increased by 225% (P = .003) and 190% (P = .04), respectively over the preoperative values. In addition, compared with preoperative plasma, postoperative plasma increased HUVEC secretion of PAI-1 antigen and activity by 99% (P = .001) and 66% (P = .002), respectively. This increase in HUVEC PAI-1 secretion reflects an increase in PAI-1 mRNA expression and protein biosynthesis as confirmed by metabolic radiolabeling, immunoprecipitation, and Northern blot analysis. Ultra-filtration experiments indicate that the postoperative plasma mediator(s) that stimulates HUVEC PAI-1 biosynthesis is in a molecular weight (MW) range of approximately 30 to 100 Kd. Heat treatment (56 degrees C; 30 minutes) of postoperative plasma abolished the induction of HUVEC PAI-1 production. Enzyme-linked immunosorbent assay and immunoneutralization experiments indicate that tumor necrosis factor-alpha (TNF alpha) and interleukin-1 alpha (IL-1 alpha) do not contribute to the postoperative plasma effect on HUVEC PAI-1 synthesis. These observations demonstrate that postoperative patient plasma contains a factor(s) that may stimulate endothelial cell PAI-1 biosynthesis in vivo and thus mediate postoperative fibrinolytic shut-down.
authors.affiliation: Department of Pathology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Kassis
authors.forename: J
authors.initials: J
authors.lastname: Hirsh
authors.forename: T J
authors.initials: TJ
authors.lastname: Podor
mesh_terms: D000368:Aged; D015152:Blotting, Northern; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D005342:Fibrinolysis; D006493:Heparin / Q000627:therapeutic use; D006622:Hip Prosthesis; D006801:Humans; D007375:Interleukin-1 / Q000097:blood*; D007700:Kinetics; D008297:Male; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D011184:Postoperative Period; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014470:Umbilical Cord
chemical_list: D007375:Interleukin-1; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D006493:Heparin