title: Activity of Species-specific Antibiotics Against Crohn's Disease-Associated Adherent-invasive Escherichia coli.
abstract: BACKGROUND
  Crohn's disease (CD) is associated with bacterial dysbiosis that frequently includes colonization by adherent-invasive Escherichia coli (AIEC). AIEC are adept at forming biofilms and are able to invade host cells and stimulate the production of proinflammatory cytokines. The use of traditional antibiotics for the treatment of CD shows limited efficacy. In this study, we investigate the use of species-specific antibiotics termed colicins for treatment of CD-associated AIEC.
  
  
  METHODS
  Colicin activity was tested against a range of AIEC isolates growing in the planktonic and biofilm mode of growth. Colicins were also tested against AIEC bacteria associated with T84 intestinal epithelial cells and surviving inside RAW264.7 macrophages using adhesion assays and gentamicin protection assay, respectively. Uptake of colicins into eukaryotic cells was visualized using confocal microscopy. The effect of colicin treatment on the production of proinflammatory cytokine tumor necrosis factor alpha by macrophages was assessed by an enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Colicins show potent activity against AIEC bacteria growing as biofilms when delivered either as a purified protein or through a colicin-producing bacterial strain. In addition, colicins E1 and E9 are able to kill cell-associated and intracellular AIEC, but do not show toxicity toward macrophage cells or stimulate the production of proinflammatory cytokines. Colicin killing of intracellular bacteria occurs after entry of colicin protein into AIEC-infected macrophage compartments by actin-mediated endocytosis.
  
  
  CONCLUSIONS
  Our results demonstrate the potential of colicins as highly selective probiotic therapeutics for the eradication of E. coli from the gastrointestinal tract of patients with CD.
authors.affiliation: Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Carla L
authors.initials: CL
authors.lastname: Brown
authors.forename: Karen
authors.initials: K
authors.lastname: Smith
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Wall
authors.forename: Daniel
authors.initials: D
authors.lastname: Walker
mesh_terms: D000199:Actins / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms; D003087:Colicins / Q000494:pharmacology*; D003424:Crohn Disease / Q000382:microbiology*; D004705:Endocytosis / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000382:microbiology; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000199:Actins; D000900:Anti-Bacterial Agents; D003087:Colicins; D014409:Tumor Necrosis Factor-alpha