title: Transient receptor potential melastatin 4 inhibition prevents lipopolysaccharide-induced endothelial cell death.
abstract: OBJECTIVE
  Endothelial dysfunction is decisive in the progression of cardiovascular diseases. Lipopolysaccharide (LPS)-induced reactive oxygen species (ROS)-mediated endothelial cell death is a main feature observed in inflammation secondary to endotoxaemia, emerging as a leading cause of death among critically ill patients in intensive care units. However, the molecular mechanism underlying LPS-induced endothelial cell death is not well understood. Transient receptor protein melastatin 4 (TRPM4) is an ion channel associated with cell death that is expressed in endothelium and modulated by ROS. Here, we investigate the role of TRPM4 in LPS-induced endothelial cell death, testing whether suppression of the expression of TRPM4 confers endothelial cell resistance to LPS challenge.
  
  
  RESULTS
  Using primary cultures of human umbilical vein endothelial cells (HUVEC), we demonstrate that TRPM4 is critically involved in LPS-induced endothelial cell death. HUVEC exposed to LPS results in Na(+)-dependent cell death. Pharmacological inhibition of TRPM4 with 9-phenanthrol or glibenclamide protects endothelium against LPS exposure for 48 h. Furthermore, TRPM4-like currents increase in cells pre-treated with LPS and inhibited with glibenclamide. Of note, suppression of TRPM4 expression by siRNA or suppression of its activity in a dominant negative mutant is effective in decreasing LPS-induced endothelial cell death when cells are exposed to LPS for 24-30 h.
  
  
  CONCLUSIONS
  TRPM4 is critically involved in LPS-induced endothelial cell death. These results demonstrate that either pharmacological inhibition of TRPM4, suppression of TRPM4 expression, or inhibition of TRPM4 activity are able to protect endothelium against LPS injury. These results are useful in sepsis drug design and development of new strategies for sepsis therapy.
authors.affiliation: Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas & Facultad de Medicina, Universidad Andres Bello, Av. Republica 217, 8370146 Santiago, Chile.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Becerra
authors.forename: Cesar
authors.initials: C
authors.lastname: Echeverría
authors.forename: Diego
authors.initials: D
authors.lastname: Varela
authors.forename: Daniela
authors.initials: D
authors.lastname: Sarmiento
authors.forename: Ricardo
authors.initials: R
authors.lastname: Armisén
authors.forename: Felipe
authors.initials: F
authors.lastname: Nuñez-Villena
authors.forename: Mario
authors.initials: M
authors.lastname: Montecinos
authors.forename: Felipe
authors.initials: F
authors.lastname: Simon
mesh_terms: D016923:Cell Death; D048429:Cell Size; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects*; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity*; D010616:Phenanthrenes / Q000494:pharmacology; D017382:Reactive Oxygen Species; D012964:Sodium / Q000378:metabolism; D050053:TRPM Cation Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000502:physiology
chemical_list: D008070:Lipopolysaccharides; D010616:Phenanthrenes; D017382:Reactive Oxygen Species; C495345:TLR4 protein, human; D050053:TRPM Cation Channels; C437888:TRPM4 protein, human; D051197:Toll-Like Receptor 4; C091375:9-phenanthrol; D012964:Sodium; D005905:Glyburide