title: Murine lung injury caused by Leptospira interrogans glycolipoprotein, a specific Na/K-ATPase inhibitor.
abstract: BACKGROUND
  Leptospiral glycolipoprotein (GLP) is a potent and specific Na/K-ATPase inhibitor. Severe pulmonary form of leptospirosis is characterized by edema, inflammation and intra-alveolar hemorrhage having a dismal prognosis. Resolution of edema and inflammation determines the outcome of lung injury. Na/K-ATPase activity is responsible for edema clearance. This enzyme works as a cell receptor that triggers activation of mitogen-activated protein kinase (MAPK) intracellular signaling pathway. Therefore, injection of GLP into lungs induces injury by triggering inflammation.
  
  
  METHODS
  We injected GLP and ouabain, into mice lungs and compared their effects. Bronchoalveolar lavage fluid (BALF) was collected for cell and lipid body counting and measurement of protein and lipid mediators (PGE2 and LTB4). The levels of the IL-6, TNFα, IL-1B and MIP-1α were also quantified. Lung images illustrate the injury and whole-body plethysmography was performed to assay lung function. We used Toll-like receptor 4 (TLR4) knockout mice to evaluate leptospiral GLP-induced lung injury. Na/K-ATPase activity was determined in lung cells by nonradioactive rubidium incorporation. We analyzed MAPK p38 activation in lung and in epithelial and endothelial cells.
  
  
  RESULTS
  Leptospiral GLP and ouabain induced lung edema, cell migration and activation, production of lipid mediators and cytokines and hemorrhage. They induced lung function alterations and inhibited rubidium incorporation. Using TLR4 knockout mice, we showed that the GLP action was not dependent on TLR4 activation. GLP activated of p38 and enhanced cytokine production in cell cultures which was reversed by a selective p38 inhibitor.
  
  
  CONCLUSIONS
  GLP and ouabain induced lung injury, as evidenced by increased lung inflammation and hemorrhage. To our knowledge, this is the first report showing GLP induces lung injury. GLP and ouabain are Na/K-ATPase targets, triggering intracellular signaling pathways. We showed p38 activation by GLP-induced lung injury, which was may be linked to Na/K-ATPase inhibition. Lung inflammation induced by GLP was not dependent on TLR4 activation.
authors.forename: Cassiano Felippe
authors.initials: CF
authors.lastname: Gonçalves-de-Albuquerque
authors.forename: Patrícia
authors.initials: P
authors.lastname: Burth
authors.forename: Adriana Ribeiro
authors.initials: AR
authors.lastname: Silva
authors.forename: Isabel Matos Medeiros
authors.initials: IM
authors.lastname: de Moraes
authors.forename: Flora Magno de Jesus
authors.initials: FM
authors.lastname: Oliveira
authors.forename: Ricardo Erthal
authors.initials: RE
authors.lastname: Santelli
authors.forename: Aline Soares
authors.initials: AS
authors.lastname: Freire
authors.forename: Gerson Silva
authors.initials: GS
authors.lastname: de Lima
authors.forename: Emilson Domingos
authors.initials: ED
authors.lastname: da Silva
authors.forename: Camila Ignácio
authors.initials: CI
authors.lastname: da Silva
authors.forename: Verônica
authors.initials: V
authors.lastname: Morandi
authors.forename: Patrícia Torres
authors.initials: PT
authors.lastname: Bozza
authors.forename: Mauricio
authors.initials: M
authors.lastname: Younes-Ibrahim
authors.forename: Hugo Caire
authors.initials: HC
authors.lastname: de Castro Faria Neto
authors.forename: Mauro Velho
authors.initials: MV
authors.lastname: de Castro Faria
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000633:toxicity; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D007921:Leptospira interrogans; D008070:Lipopolysaccharides / Q000633:toxicity*; D008074:Lipoproteins / Q000633:toxicity*; D055370:Lung Injury / Q000139:chemically induced* / Q000201:enzymology* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D008074:Lipoproteins; D000254:Sodium-Potassium-Exchanging ATPase