title: Non-pathogenic commensal Escherichia coli bacteria can inhibit degranulation of mast cells.
abstract: BACKGROUND
  The mast cell's (MC) ability to rapidly release presynthesized mediators allows it to play a critical role in the immune system's first-line response to pathogens. Although recent research has illuminated the role of MCs in bacterial infection, little is known about how non-pathogenic bacteria influence MC responses.
  
  
  OBJECTIVE
  To characterize the influence of non-pathogenic Escherichia coli bacteria on MCs.
  
  
  RESULTS
  High concentrations of live E. coli strongly down-modulated the degranulation of murine peritoneal MCs under all activator conditions. Bacteria did not induce MC degranulation by themselves, and staining of MCs showed they were still entirely viable. Dead bacteria and bacterial supernatant had no effect on MC degranulation. Ex vivo experiments confirmed that E. coli exposure down-modulates subsequently induced MC degranulation and that this effect lasts for up to a few days after exposure.
  
  
  CONCLUSIONS
  Our results show that high doses of non-pathogenic E. coli bacteria can function as a strong, direct inhibitor of MC degranulation. This suggests a possible basis for future antiallergic treatment or prophylaxis with commensal bacteria, i.e. probiotics.
authors.affiliation: Department of Dermatology and Allergy, Charité- Universitätsmedizin, Berlin, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Magerl
authors.forename: Verena
authors.initials: V
authors.lastname: Lammel
authors.forename: Frank
authors.initials: F
authors.lastname: Siebenhaar
authors.forename: Torsten
authors.initials: T
authors.lastname: Zuberbier
authors.forename: Martin
authors.initials: M
authors.lastname: Metz
authors.forename: Marcus
authors.initials: M
authors.lastname: Maurer
mesh_terms: D000818:Animals; D017209:Apoptosis; D000001:Calcimycin / Q000494:pharmacology; D015550:Cell Degranulation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival; D003609:Dactinomycin / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004926:Escherichia coli / Q000472:pathogenicity; D005434:Flow Cytometry; D007073:Immunoglobulin E / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010537:Peritoneum / Q000166:cytology; D012701:Serotonin / Q000032:analysis / Q000378:metabolism; D012709:Serum Albumin / Q000494:pharmacology; D014316:Tritium / Q000032:analysis
chemical_list: D004140:Dinitrophenols; D012709:Serum Albumin; C058064:dinitrophenyl-human serum albumin conjugate; D014316:Tritium; D003609:Dactinomycin; D012701:Serotonin; D007073:Immunoglobulin E; D000001:Calcimycin