title: Extracellular calcium reduction strongly increases the lytic capacity of pneumolysin from streptococcus pneumoniae in brain tissue.
abstract: BACKGROUND
  Streptococcus pneumoniae causes serious diseases such as pneumonia and meningitis. Its major pathogenic factor is the cholesterol-dependent cytolysin pneumolysin, which produces lytic pores at high concentrations. At low concentrations, it has other effects, including induction of apoptosis. Many cellular effects of pneumolysin appear to be calcium dependent.
  
  
  METHODS
  Live imaging of primary mouse astroglia exposed to sublytic amounts of pneumolysin at various concentrations of extracellular calcium was used to measure changes in cellular permeability (as judged by lactate dehydrogenase release and propidium iodide chromatin staining). Individual pore properties were analyzed by conductance across artificial lipid bilayer. Tissue toxicity was studied in continuously oxygenated acute brain slices.
  
  
  RESULTS
  The reduction of extracellular calcium increased the lytic capacity of the toxin due to increased membrane binding. Reduction of calcium did not influence the conductance properties of individual toxin pores. In acute cortical brain slices, the reduction of extracellular calcium from 2 to 1 mM conferred lytic activity to pathophysiologically relevant nonlytic concentrations of pneumolysin.
  
  
  CONCLUSIONS
  Reduction of extracellular calcium strongly enhanced the lytic capacity of pneumolysin due to increased membrane binding. Thus, extracellular calcium concentration should be considered as a factor of primary importance for the course of pneumococcal meningitis.
authors.affiliation: DFG Membrane/Cytoskeleton Interaction Group, Institute of Pharmacology and Toxicology & Rudolf Virchow Center for Experimental Medicine, University of Würzburg, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Wippel
authors.forename: Christina
authors.initials: C
authors.lastname: Förtsch
authors.forename: Sabrina
authors.initials: S
authors.lastname: Hupp
authors.forename: Elke
authors.initials: E
authors.lastname: Maier
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
authors.forename: Jiangtao
authors.initials: J
authors.lastname: Ma
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchell
authors.forename: Asparouh I
authors.initials: AI
authors.lastname: Iliev
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism / Q000633:toxicity; D001921:Brain / Q000382:microbiology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D013296:Streptococcus pneumoniae / Q000472:pathogenicity*; D013301:Streptolysins / Q000378:metabolism / Q000633:toxicity*
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D007770:L-Lactate Dehydrogenase; D002118:Calcium