title: Probiotic Escherichia coli Nissle 1917 and commensal E. coli K12 differentially affect the inflammasome in intestinal epithelial cells.
abstract: BACKGROUND
  The probiotic bacterial strain Escherichia coli Nissle 1917 (EcN) is used for the treatment of ulcerative colitis (UC), diarrhea and constipation. Its beneficial effects in the treatment of UC have been demonstrated in several controlled clinical studies; however, the mechanism of action on the cellular level is still not completely clear. The intracellular pattern recognition receptor NLRP3 is expressed in intestinal epithelial cells (IEC), activates caspase-1 within the inflammasome complex and has been implicated to play a role in the etiology of inflammatory bowel diseases.
  
  
  METHODS
  Probiotic EcN and commensal E. coli K12 were applied to IEC in vitro. Inflammasome activation, interleukin (IL)-18 release and caspase-1 activation were determined by coimmunoprecipitation, Western blot and ELISA. Apoptosis was investigated by Western blot.
  
  
  RESULTS
  Incubation of Caco-2 cells with EcN resulted in lower inflammasome activation and subsequent secretion of mature IL-18 as compared to the commensal strain K12. Induction of apoptosis as determined by cleavage of caspase-3 and poly (ADP-ribose) polymerase were lower in EcN-stimulated cells. Autophagy was induced by both bacterial strains, but to a higher extent by K12.
  
  
  CONCLUSIONS
  These findings indicate that genetically very similar E. coli strains differ markedly in their ability to activate the inflammasome.
authors: Division of Gastroenterology and Hepatology, University Hospital Zurich.
authors: Helen M
authors: HM
authors: Becker
authors: Aretussa
authors: A
authors: Apladas
authors: Michael
authors: M
authors: Scharl
authors: Michael
authors: M
authors: Fried
authors: Gerhard
authors: G
authors: Rogler
mesh_terms: D017209:Apoptosis; D001343:Autophagy; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism; D020170:Caspase 1 / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism; D048168:Escherichia coli K12; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism; D020382:Interleukin-18 / Q000378:metabolism*; D007413:Intestinal Mucosa; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019936:Probiotics
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D020382:Interleukin-18; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D020170:Caspase 1