title: Prostacyclin post-treatment improves LPS-induced acute lung injury and endothelial barrier recovery via Rap1.
abstract: Protective effects of prostacyclin (PC) or its stable analog beraprost against agonist-induced lung vascular inflammation have been associated with elevation of intracellular cAMP and Rac GTPase signaling which inhibited the RhoA GTPase-dependent pathway of endothelial barrier dysfunction. This study investigated a distinct mechanism of PC-stimulated lung vascular endothelial (EC) barrier recovery and resolution of LPS-induced inflammation mediated by small GTPase Rap1. Efficient barrier recovery was observed in LPS-challenged pulmonary EC after prostacyclin administration even after 15 h of initial inflammatory insult and was accompanied by the significant attenuation of p38 MAP kinase and NFκB signaling and decreased production of IL-8 and soluble ICAM1. These effects were reproduced in cells post-treated with 8CPT, a small molecule activator of Rap1-specific nucleotide exchange factor Epac. By contrast, pharmacologic Epac inhibitor, Rap1 knockdown, or knockdown of cell junction-associated Rap1 effector afadin attenuated EC recovery caused by PC or 8CPT post-treatment. The key role of Rap1 in lung barrier restoration was further confirmed in the murine model of LPS-induced acute lung injury. Lung injury was monitored by measurements of bronchoalveolar lavage protein content, cell count, and Evans blue extravasation and live imaging of vascular leak over 6 days using a fluorescent tracer. The data showed significant acceleration of lung recovery by PC and 8CPT post-treatment, which was abrogated in Rap1a(-/-) mice. These results suggest that post-treatment with PC triggers the Epac/Rap1/afadin-dependent mechanism of endothelial barrier restoration and downregulation of p38MAPK and NFκB inflammatory cascades, altogether leading to accelerated lung recovery.
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Birukova
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Fanyong
authors.initials: F
authors.lastname: Meng
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Angelo
authors.initials: A
authors.lastname: Meliton
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Nicolene
authors.initials: N
authors.lastname: Sarich
authors.affiliation: Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Quilliam
authors.affiliation: Lung Injury Center, Section of Pulmonary and Critical Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA. Electronic address: kbirukov@medicine.bsd.uchicago.edu.
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Birukov
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced / Q000235:genetics / Q000517:prevention & control*; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D011464:Epoprostenol / Q000031:analogs & derivatives / Q000494:pharmacology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008070:Lipopolysaccharides; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C473217:8-(4-chloro-phenylthio)-2'-O-methyladenosine-3'-5'-cyclic monophosphate; C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; C090509:Icam1 protein, mouse; D016209:Interleukin-8; D008070:Lipopolysaccharides; D008840:Microfilament Proteins; D016328:NF-kappa B; D010975:Platelet Aggregation Inhibitors; C108835:afadin; D018799:Intercellular Adhesion Molecule-1; C048081:beraprost; D011464:Epoprostenol; D000242:Cyclic AMP; D048051:p38 Mitogen-Activated Protein Kinases; D020827:rap1 GTP-Binding Proteins
keywords: Cytoskeleton; Endothelium; Inflammation; Lung; Permeability