title: Active α-macroglobulin is a reservoir for urokinase after fibrinolytic therapy in rabbits with tetracycline-induced pleural injury and in human pleural fluids.
abstract: Intrapleural processing of prourokinase (scuPA) in tetracycline (TCN)-induced pleural injury in rabbits was evaluated to better understand the mechanisms governing successful scuPA-based intrapleural fibrinolytic therapy (IPFT), capable of clearing pleural adhesions in this model. Pleural fluid (PF) was withdrawn 0-80 min and 24 h after IPFT with scuPA (0-0.5 mg/kg), and activities of free urokinase (uPA), plasminogen activator inhibitor-1 (PAI-1), and uPA complexed with α-macroglobulin (αM) were assessed. Similar analyses were performed using PFs from patients with empyema, parapneumonic, and malignant pleural effusions. The peak of uPA activity (5-40 min) reciprocally correlated with the dose of intrapleural scuPA. Endogenous active PAI-1 (10-20 nM) decreased the rate of intrapleural scuPA activation. The slow step of intrapleural inactivation of free uPA (t1/2(β) = 40 ± 10 min) was dose independent and 6.7-fold slower than in blood. Up to 260 ± 70 nM of αM/uPA formed in vivo [second order association rate (kass) = 580 ± 60 M(-1)·s(-1)]. αM/uPA and products of its degradation contributed to durable intrapleural plasminogen activation up to 24 h after IPFT. Active PAI-1, active α2M, and α2M/uPA found in empyema, pneumonia, and malignant PFs demonstrate the capacity to support similar mechanisms in humans. Intrapleural scuPA processing differs from that in the bloodstream and includes 1) dose-dependent control of scuPA activation by endogenous active PAI-1; 2) two-step inactivation of free uPA with simultaneous formation of αM/uPA; and 3) slow intrapleural degradation of αM/uPA releasing active free uPA. This mechanism offers potential clinically relevant advantages that may enhance the bioavailability of intrapleural scuPA and may mitigate the risk of bleeding complications.
authors.affiliation: The Univ. of Texas Health Science Center at Tyler, 11937 US Highway 271, Lab C-6, Tyler, TX 75708. andrey.komissarov@uthct.edu or komissarov_a@yahoo.com.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Komissarov
authors.forename: Galina
authors.initials: G
authors.lastname: Florova
authors.forename: Ali
authors.initials: A
authors.lastname: Azghani
authors.forename: Sophia
authors.initials: S
authors.lastname: Karandashova
authors.forename: Anna K
authors.initials: AK
authors.lastname: Kurdowska
authors.forename: Steven
authors.initials: S
authors.lastname: Idell
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D005260:Female; D005342:Fibrinolysis / Q000187:drug effects; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D010994:Pleura / Q000187:drug effects* / Q000293:injuries / Q000378:metabolism; D011817:Rabbits; D055293:Receptors, Urokinase Plasminogen Activator / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013754:Tetracyclines / Q000494:pharmacology*; D015912:Thrombolytic Therapy; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D005343:Fibrinolytic Agents; D017395:Plasminogen Activator Inhibitor 1; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins; D013754:Tetracyclines; D000511:alpha-Macroglobulins; D014568:Urokinase-Type Plasminogen Activator; C067551:saruplase
keywords: fibrinolytic therapy; human; pleural injury; rabbit model; urokinase; α-macroglobulin