title: Differential activation of eosinophils by bacteria associated with asthma.
abstract: BACKGROUND
  It has been suggested that there is a complex interaction between microbiota and various human diseases. Some bacteria have been reported to be involved in the inception and progression of asthma, and others in the protection against asthma. We know very little about the mechanisms by which bacteria do harm or good with regard to asthma. This study investigated whether bacteria exert differential effects on the functions of eosinophils, major effector cells in airway inflammation in asthma.
  
  
  METHODS
  Eosinophils were purified from healthy adult volunteers by Percoll density gradient centrifugation and negative immunomagnetic bead selection using anti-CD16 microbeads. Three kinds of heat-killed bacteria that have been implicated in asthma, namely Staphylococcus aureus (SA), Haemophilus influenzae (HI) and a Prevotella sp. (PS), were tested for their effects on the secretion of eosinophil-derived neurotoxin (EDN), the generation of superoxides and the production of cytokines/chemokines.
  
  
  RESULTS
  SA, but not HI or PS, induced significant EDN release in a dose-dependent manner. Superoxide generation was significantly enhanced by each of the bacterial species, but most strongly by SA, which induced significantly greater TNF-α production by eosinophils than either HI or PS. Conversely, interleukin 10, an anti-inflammatory cytokine, was more strongly induced by HI and PS than by SA.
  
  
  CONCLUSIONS
  Bacteria exert differential effects on eosinophils. Based on these results, SA may be involved in the exacerbation of, and HI and PS in the inhibition of, eosinophilic inflammation in asthma.
authors.affiliation: Institute for Clinical Research, Mie National Hospital, Tsu, Japan.
authors.forename: Koa
authors.initials: K
authors.lastname: Hosoki
authors.forename: Akiko
authors.initials: A
authors.lastname: Nakamura
authors.forename: Keigo
authors.initials: K
authors.lastname: Kainuma
authors.forename: Mayumi
authors.initials: M
authors.lastname: Sugimoto
authors.forename: Mizuho
authors.initials: M
authors.lastname: Nagao
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hiraguchi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Tanida
authors.forename: Reiko
authors.initials: R
authors.lastname: Tokuda
authors.forename: Hideo
authors.initials: H
authors.lastname: Wada
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nobori
authors.forename: Shigeru
authors.initials: S
authors.lastname: Suga
authors.forename: Takao
authors.initials: T
authors.lastname: Fujisawa
mesh_terms: D001249:Asthma / Q000276:immunology* / Q000382:microbiology*; D001419:Bacteria / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D047208:Eosinophil-Derived Neurotoxin / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology* / Q000378:metabolism; D006193:Haemophilus influenzae / Q000276:immunology; D006801:Humans; D018720:Prevotella / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology; D013481:Superoxides / Q000378:metabolism
chemical_list: D016207:Cytokines; D013481:Superoxides; D047208:Eosinophil-Derived Neurotoxin