• Birgitt Gutbier, Xiaohui Jiang, Kristina Dietert, Carolin Ehrler, Jasmin Lienau, Van SlykePaulPVasomune Therapeutics, 661 University Avenue, Suite 465, Toronto, ON, M5G 1M1, Canada., Harold Kim, Van C Hoang, Jason T Maynes, Daniel J Dumont, Achim D Gruber, Norbert Weissmann, Timothy J Mitchell, Norbert Suttorp, and Martin Witzenrath.
• Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Infectious Diseases and Pulmonary Medicine, Charitéplatz 1, 10117, Berlin, Germany.
• Crit Care. 2017 Nov 13; 21 (1): 274274.

BackgroundCommunity-acquired pneumonia (CAP) is a significant cause of morbidity and mortality worldwide. Despite effective antimicrobial therapy, CAP can induce pulmonary endothelial hyperpermeability resulting in life-threatening lung failure due to an exaggerated host-pathogen interaction. Treatment of acute lung injury is mainly supportive because key elements of inflammation-induced barrier disruption remain undetermined. Angiopoietin-1 (Ang-1)-mediated Tie2 activation reduces, and the Ang-1 antagonist Ang-2 increases, inflammation and endothelial permeability in sepsis. Vasculotide (VT) is a polyethylene glycol-clustered Tie2-binding peptide that mimics the actions of Ang-1. The aim of our study was to experimentally test whether VT is capable of diminishing pneumonia-induced lung injury.MethodsVT binding and phosphorylation of Tie2 were analyzed using tryptophan fluorescence spectroscopy and phospho-Tie-2 enzyme-linked immunosorbent assay. Human and murine lung endothelial cells were investigated by immunofluorescence staining and electric cell-substrate impedance sensing. Pulmonary hyperpermeability was quantified in VT-pretreated, isolated, perfused, and ventilated mouse lungs stimulated with the pneumococcal exotoxin pneumolysin (PLY). Furthermore, Streptococcus pneumoniae-infected mice were therapeutically treated with VT.ResultsVT showed dose-dependent binding and phosphorylation of Tie2. Pretreatment with VT protected lung endothelial cell monolayers from PLY-induced disruption. In isolated mouse lungs, VT decreased PLY-induced pulmonary permeability. Likewise, therapeutic treatment with VT of S. pneumoniae-infected mice significantly reduced pneumonia-induced hyperpermeability. However, effects by VT on the pulmonary or systemic inflammatory response were not observed.ConclusionsVT promoted pulmonary endothelial stability and reduced lung permeability in different models of pneumococcal pneumonia. Thus, VT may provide a novel therapeutic perspective for reduction of permeability in pneumococcal pneumonia-induced lung injury.

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