Prevention of Lung Fibrosis in a Rabbit Model of Bleomycin-Induced Lung Fibrosis Upon Aerosol Application of Heparin or Urokinase

Günther, Andreas; Lübke, Norbert; Ruppert, Clemens; Weissman, Norbert; Grimminger, Friedrich; Seeger, Werner

doi:10.1016/s0012-3692(15)38670-0

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“…In view of the pathogenetic relevance of alveolar fibrin formation and accumulation of surfactant-rich fibrin clots in the lung for impairment of surfactant function, gas exchange properties andstill hypotheticallyfibroproliferative changes in late ARDS and inflammatory lung disease, selective fibrinolysis in the alveolar compartment might offer as new therapeutic approach. Coaerosolation of native urokinase and natural surfactant material was, indeed, recently shown to improve gas exchange and to limit lung fibrosis in experimental models of acute and chronic inflammatory injury ( , ). A properly designed fibrinolytic agent, addressing the unique nature of alveolar fibrin, might be an interesting tool for such a purpose, and the data of the present study render the anti-SP-B−u-PA-B-chain conjugate an interesting candidate in this context.…”

Section: Discussionmentioning

confidence: 99%

Chemical Coupling of a Monoclonal Antisurfactant Protein-B Antibody to Human Urokinase for Targeting Surfactant-Incorporating Alveolar Fibrin

et al. 2002

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Intraalveolar fibrin formation is a common histopathological finding in acute inflammatory and chronic interstitial lung diseases. Incorporation of hydrophobic surfactant components into polymerizing fibrin results in a severe loss of surface activity, altered mechanical and structural clot properties, and a reduced susceptibility toward fibrinolytic degradation. Such events have been implicated in atelectasis formation, impairment of gas exchange, and provocation of fibroproliferative changes. In an effort to address the unique features of alveolar fibrin, we designed a hybrid molecule consisting of a monoclonal antibody against surfactant protein SP-B (8B5E) and the catalytic domain of urokinase (B-chain), which was termed MABUC. The urokinase B-chain was prepared by limited reduction of human two-chain-urokinase and subsequent affinity purification and coupled to the antibody using a heterobifunctional cross-linker. Purification of the chimeric protein included gel filtration chromatography and affinity chromatography. An ELISA-like microtiter plate assay, based on the immunological detection of the SP-B moiety and the fibrinolytic activity of the u-PA domain, was developed for the detection of the hybrid molecule. Chromogenic substrate assays, (125)I-based fibrin plate assays, and active site titration were performed to analyze the specific fibrinolytic activity of the conjugate. MABUC was found to fully retain the ability of SP-B binding and the fibrinolytic activity of u-PA. In addition, MABUC was noted to be 1.5-2-fold more effective in the dissolution of surfactant embedding clots and to be approximately 3-fold more resistant against PAI-1, the predominant fibrinolysis inhibitor in the alveolar compartment, as compared to the native u-PA. The superiority of MABUC was particularly prominent (>5-fold efficacy) when investigating clot material incorporating both PAI-1 and surfactant, as a mimicry of alveolar fibrin. We conclude that urokinase and 8B5E can be cross-linked chemically, thus yielding a fibrinolytic enzyme with enhanced substrate specifity for surfactant-containing clots and higher PAI-1 resistance as compared to native u-PA.

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Section: Discussionmentioning

confidence: 99%