Lactobacillus johnsonii inhibits indoleamine 2,3-dioxygenase and alters tryptophan metabolite levels in BioBreeding rats

FASEB J. 2013 Apr;27(4):1711-20. doi: 10.1096/fj.12-223339. Epub 2013 Jan 9.


In our previous work, we found that feeding Lactobacillus johnsonii to BioBreeding diabetes-prone (BBDP) rats decreased the incidence of diabetes development. The aim of this study was to investigate host pathways affected by L. johnsonii, with specific focus on the rate-limiting enzyme of tryptophan catabolism, indoleamine 2,3-dioxygenase (IDO). Suspensions of L. johnsonii or an equal volume of vehicle were orally administered to BBDP rats. Tissue IDO was investigated using quantitative RT-PCR and Western blot, whereas tryptophan, kynurenine, and 5-hydroxytryptamine (5-HT) concentrations were quantified by HPLC and ELISA. IDO activity was also investigated using L. johnsonii culture cell-free supernatant (CFS) with affinity-purified IDO and HT-29 intestinal epithelial cells. L. johnsonii feeding resulted in a 17% reduction in serum kynurenine compared with that in vehicle-fed controls, correlating with a 1.4-fold elevation in 5-HT levels. H₂O₂ produced by L. johnsonii abolished IDO activity in vitro, and L. johnsonii feeding resulted in a 3.9-fold increase in ileum lumen H₂O₂. L. johnsonii CFS significantly reduced IDO activity in HT-29 intestinal epithelial cells (47% reduction) compared with that in vehicle-treated controls, an effect abolished by catalase treatment. These data support the role of H₂O₂ in commensal bacteria-host interactions and highlight the influence of commensal bacteria-derived H₂O₂ on host physiology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cells, Cultured
  • Disease Models, Animal
  • Hydrogen Peroxide / pharmacology
  • Indoleamine-Pyrrole 2,3,-Dioxygenase / antagonists & inhibitors*
  • Indoles / metabolism
  • Kynurenine / metabolism*
  • Lactobacillus / drug effects
  • Lactobacillus / enzymology*
  • Rats
  • Rats, Inbred BB
  • Serotonin / blood
  • Tryptophan / antagonists & inhibitors*


  • Indoleamine-Pyrrole 2,3,-Dioxygenase
  • Indoles
  • Serotonin
  • Kynurenine
  • indole
  • Tryptophan
  • Hydrogen Peroxide