title: Atrial natriuretic peptide attenuates LPS-induced lung vascular leak: role of PAK1.
abstract: Increased levels of atrial natriuretic peptide (ANP) in the models of sepsis, pulmonary edema, and acute respiratory distress syndrome (ARDS) suggest its potential role in the modulation of acute lung injury. We have recently described ANP-protective effects against thrombin-induced barrier dysfunction in pulmonary endothelial cells (EC). The current study examined involvement of the Rac effector p21-activated kinase (PAK1) in ANP-protective effects in the model of lung vascular permeability induced by bacterial wall LPS. C57BL/6J mice or ANP knockout mice (Nppa(-/-)) were treated with LPS (0.63 mg/kg intratracheal) with or without ANP (2 μg/kg iv). Lung injury was monitored by measurements of bronchoalveolar lavage protein content, cell count, Evans blue extravasation, and lung histology. Endothelial barrier properties were assessed by morphological analysis and measurements of transendothelial electrical resistance. ANP treatment stimulated Rac-dependent PAK1 phosphorylation, attenuated endothelial permeability caused by LPS, TNF-α, and IL-6, decreased LPS-induced cell and protein accumulation in bronchoalveolar lavage fluid, and suppressed Evans blue extravasation in the murine model of acute lung injury. More severe LPS-induced lung injury and vascular leak were observed in ANP knockout mice. In rescue experiments, ANP injection significantly reduced lung injury in Nppa(-/-) mice caused by LPS. Molecular inhibition of PAK1 suppressed the protective effects of ANP treatment against LPS-induced lung injury and endothelial barrier dysfunction. This study shows that the protective effects of ANP against LPS-induced vascular leak are mediated at least in part by PAK1-dependent signaling leading to EC barrier enhancement. Our data suggest a direct role for ANP in endothelial barrier regulation via modulation of small GTPase signaling.
authors: Section of Pulmonary and Critical Medicine, Lung Injury Center, Dept. of Medicine, Univ. of Chicago, 5841 S. Maryland Ave., Office N613, Chicago, IL 60637, USA. abirukov@medicine.bsd.uchicago.edu
authors: Anna A
authors: AA
authors: Birukova
authors: Junjie
authors: J
authors: Xing
authors: Panfeng
authors: P
authors: Fu
authors: Bakhtiyor
authors: B
authors: Yakubov
authors: Oleksii
authors: O
authors: Dubrovskyi
authors: Jennifer A
authors: JA
authors: Fortune
authors: Alexander M
authors: AM
authors: Klibanov
authors: Konstantin G
authors: KG
authors: Birukov
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000494:pharmacology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002199:Capillary Permeability / Q000187:drug effects*; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000098:blood supply* / Q000166:cytology / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011897:Random Allocation; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D054462:p21-Activated Kinases / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D009320:Atrial Natriuretic Factor; D054462:p21-Activated Kinases