title: Interplay of pneumococcal hydrogen peroxide and host-derived nitric oxide.
abstract: Reactive oxygen and nitrogen species are released by immune-competent cells and contribute to cellular damage. On the other hand, certain pathogens, including Streptococcus pneumoniae, are known to produce hydrogen peroxide (H2O2), while production of nitrogen radicals by bacteria presumably occurs but has been poorly studied. We determined the relative contributions of bacterial versus host-derived oxygen and nitrogen radicals to cellular damage in pneumococcal infection. A special focus was placed on peroxynitrite as a hypothetical common product formed by the reaction of H2O2 and NO. In microglial cultures, reduction of the formation of 3-nitrotyrosine and cellular damage required H2O2-deficient (DeltaspxB or DeltacarB) pneumococci and inhibition of host NO synthesis with aminoguanidine. In infected C57BL/6 mice, neuronal loss and immunopositivity for nitrotyrosine in the dentate gyrus were markedly reduced with DeltaspxB or DeltacarB bacterial mutants and in inducible nitric oxide synthase knockout mice. We conclude that although host and bacteria both produce oxygen and nitrogen radicals, the interplay of prokaryotic H2O2 and eukaryotic NO is a major contributor to cellular damage in pneumococcal meningitis.
authors.affiliation: Department of Neurology, Charité-Universitaetsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Hoffmann
authors.forename: Janine
authors.initials: J
authors.lastname: Zweigner
authors.forename: Shannon H
authors.initials: SH
authors.lastname: Smith
authors.forename: Dorette
authors.initials: D
authors.lastname: Freyer
authors.forename: Cordula
authors.initials: C
authors.lastname: Mahrhofer
authors.forename: Emilie
authors.initials: E
authors.lastname: Dagand
authors.forename: Elaine I
authors.initials: EI
authors.lastname: Tuomanen
authors.forename: Joerg R
authors.initials: JR
authors.lastname: Weber
mesh_terms: D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000235:genetics; D002478:Cells, Cultured; D004195:Disease Models, Animal; D017353:Gene Deletion; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008586:Meningitis, Pneumococcal / Q000378:metabolism* / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009457:Neuroglia / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D030421:Peroxynitrous Acid / Q000032:analysis; D011771:Pyruvate Oxidase / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000201:enzymology* / Q000235:genetics; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D006146:Guanidines; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D011771:Pyruvate Oxidase; D002222:Carbamoyl-Phosphate Synthase (Ammonia); C004479:pimagedine