title: Probiotics inhibit nuclear factor-kappaB and induce heat shock proteins in colonic epithelial cells through proteasome inhibition.
abstract: OBJECTIVE
  The extent and severity of mucosal injury in inflammatory bowel diseases are determined by the disequilibrium between 2 opposing processes: reparative and cytoprotective mechanisms vs. inflammation-induced injury. Probiotics may provide clinical benefit by ameliorating colitis; however, their mechanisms of action remain largely unknown. Our objective was to investigate microbial-epithelial interactions that could explain the beneficial therapeutic effects of probiotics.
  
  
  METHODS
  The effect of VSL#3-conditioned media on the nuclear factor-kappaB pathway in young adult mouse colonic epithelial cells was assessed by using monocyte chemoattractant protein-1 enzyme-linked immunosorbent assays; IkappaBalpha, IkappaBbeta, and p105 immunoblot analysis; and nuclear factor-kappaB luciferase reporter gene and proteasome assays. Effects on heat shock proteins were determined by electrophoretic mobility shift assay and immunoblot for heat shock proteins 25 and 72 in young adult mouse colonic cells. Cytoprotection against oxidant injury was determined by chromium 51 release and filamentous and globular actin assays.
  
  
  RESULTS
  VSL#3 produces soluble factors that inhibit the chymotrypsin-like activity of the proteasome in gut epithelial cells. Proteasome inhibition is an early event that begins almost immediately after exposure of the epithelial cells to the probiotic-conditioned media. In addition, these bacteria inhibit the proinflammatory nuclear factor-kappaB pathway through a mechanism different from the type III secretory mechanisms described for other nonpathogenic enteric flora. They also induce the expression of cytoprotective heat shock proteins in intestinal epithelial cells.
  
  
  CONCLUSIONS
  The resulting inhibition of nuclear factor-kappaB and increased expression of heat shock proteins may account for the anti-inflammatory and cytoprotective effects reported for probiotics and may be a novel mechanism of microbial-epithelial interaction. These effects seem to be mediated through the common unifying mechanism of proteasome inhibition.
authors.affiliation: Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Elaine O
authors.initials: EO
authors.lastname: Petrof
authors.forename: Keishi
authors.initials: K
authors.lastname: Kojima
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Ropeleski
authors.forename: Mark W
authors.initials: MW
authors.lastname: Musch
authors.forename: Yun
authors.initials: Y
authors.lastname: Tao
authors.forename: Claudio
authors.initials: C
authors.lastname: De Simone
authors.forename: Eugene B
authors.initials: EB
authors.lastname: Chang
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000032:analysis; D003106:Colon; D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D019936:Probiotics / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex; D025801:Ubiquitin / Q000378:metabolism
chemical_list: C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors; D016328:NF-kappa B; D025801:Ubiquitin; C067713:lactacystin; D046988:Proteasome Endopeptidase Complex; D000111:Acetylcysteine