title: Mechanical stress activates xanthine oxidoreductase through MAP kinase-dependent pathways.
abstract: Xanthine oxidoreductase (XOR) plays a prominent role in acute lung injury because of its ability to generate reactive oxygen species. We investigated the role of XOR in ventilator-induced lung injury (VILI). Male C57BL/6J mice were assigned to spontaneous ventilation (sham) or mechanical ventilation (MV) with low (7 ml/kg) and high tidal volume (20 ml/kg) for 2 h after which lung XOR activity and expression were measured and the effect of the specific XOR inhibitor allopurinol on pulmonary vascular leakage was examined. In separate experiments, rat pulmonary microvascular endothelial cells (RPMECs) were exposed to cyclic stretch (5% and 18% elongation, 20 cycles/min) for 2 h before intracellular XOR activity measurement. Lung XOR activity was significantly increased at 2 h of MV without changes in XOR expression. There was evidence of p38 MAP kinase, ERK1/2, and ERK5 phosphorylation, but no change in JNK phosphorylation. Evans blue dye extravasation and bronchoalveolar lavage protein concentration were significantly increased in response to MV, changes that were significantly attenuated by pretreatment with allopurinol. Cyclic stretch of RPMECs also caused MAP kinase phosphorylation and a 1.7-fold increase in XOR activity, which was completely abrogated by pretreatment of the cells with specific MAP kinase inhibitors. We conclude that XOR enzymatic activity is significantly increased by mechanical stress via activation of p38 MAP kinase and ERK and plays a critical role in the pathogenesis of pulmonary edema associated with VILI.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors.forename: Raja-Elie E
authors.initials: RE
authors.lastname: Abdulnour
authors.forename: Xinqi
authors.initials: X
authors.lastname: Peng
authors.forename: Jay H
authors.initials: JH
authors.lastname: Finigan
authors.forename: Eugenia J
authors.initials: EJ
authors.lastname: Han
authors.forename: Emile J
authors.initials: EJ
authors.lastname: Hasan
authors.forename: Konstantin G
authors.initials: KG
authors.lastname: Birukov
authors.forename: Sekhar P
authors.initials: SP
authors.lastname: Reddy
authors.forename: James E
authors.initials: JE
authors.lastname: Watkins
authors.forename: Usamah S
authors.initials: US
authors.lastname: Kayyali
authors.forename: Joe G N
authors.initials: JG
authors.lastname: Garcia
authors.forename: Rubin M
authors.initials: RM
authors.lastname: Tuder
authors.forename: Paul M
authors.initials: PM
authors.lastname: Hassoun
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D004730:Endothelium, Vascular / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008171:Lung Diseases / Q000201:enzymology* / Q000209:etiology / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011652:Pulmonary Circulation / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000201:enzymology* / Q000209:etiology / Q000378:metabolism; D013314:Stress, Mechanical; D014158:Transcription, Genetic; D012122:Ventilators, Mechanical; D014969:Xanthine Oxidase / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D014969:Xanthine Oxidase; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases