Targeting of Plasminogen Activator Inhibitor 1 Improves Fibrinolytic Therapy for Tetracycline Induced Pleural Injury in Rabbits
Florova, Galina × Azghani, Ali Karandashova, Sophia Schaefer, Chris Koenig, Kathleen Stewart-Evans, Kris Declerck, Paul Idell, Steven Komissarov, Andrey A #
American Lung Association
American Journal of Respiratory Cell and Molecular Biology vol:52 issue:4 pages:429-37
Introduction: Endogenous active plasminogen activator inhibitor 1 (PAI-1) was targeted in vivo with monoclonal antibodies (mAbs) that redirect its reaction with proteinases to the substrate branch. mAbs were used as an adjunct to prourokinase (scuPA) intrapleural fibrinolytic therapy (IPFT) of tetracycline-induced pleural injury in rabbits. Methods: Outcomes of scuPA IPFT (0.25 or 0.0625 mg/kg) with 0.5 mg/kg of mouse IgG or mAbs (MA-33H1F7 and MA-8H9D4) were assessed at 24h. Pleural fluid (PF) was collected at 0, 10, 20, 40 min and 24h after IPFT and analyzed for plasminogen activating (PA), urokinase (uPA), fibrinolytic activities, levels of total plasmin/plasminogen, α-macroglobulin (αM), mAbs/IgG antigens, free active uPA and αM/uPA complexes. Results:Anti-PAI-1 mAbs, but not mouse IgG, delivered with an 8-fold reduction in the minimal effective dose of scuPA (from 0.5 to 0.0625 mg/kg), improved the outcome of IPFT (p<0.05). mAbs and IgG were detectable in PFs at 24h. Compared to identical doses of scuPA alone or with IgG, treatment with scuPA and anti-PAI-1 mAbs generated higher PF uPA amidolytic and PA activities, faster formation of αM/uPA complexes, and slower uPA inactivation. However, PAI-1 targeting did not significantly affect intrapleural fibrinolytic activity or levels of total plasmin/plasminogen and αM antigens. Conclusions: Targeting PAI-1 did not induce bleeding and rendered otherwise ineffective doses of scuPA able to improve outcome in tetracycline-induced pleural injury. PAI-1 neutralizing mAbs improved IPFT by increasing the durability of intrapleural PA activity. These results suggest a novel, well-tolerated IPFT strategy that is tractable for clinical development.