title: Lactic acid bacteria differ in their ability to induce functional regulatory T cells in humans.
abstract: BACKGROUND
  Trials with probiotic lactic acid bacteria have yielded different results, which may be due to the strains used. Lactobacilli and bifidobacteria are known to be potent modulators of the immune system. The capacity of these bacteria used as probiotics to influence both T helper type 1 (Th1)- and Th2-mediated diseases has been shown before. However, the ability of strains to induce forkhead box P3 (FOXP3(+)) expressing regulatory T cells has not yet been investigated.
  
  
  OBJECTIVE
  Test the inherent differences between strains in their capacity to induce functional regulatory T cells in human peripheral blood mononuclear cells (PBMC).
  
  
  METHODS
  Human PBMC were co-cultured in vitro with either Bifidobacterium lactis W51, Lactobacillus acidophilus W55 or Lactobacillus plantarum W62 or an Escherichia coli control strain. The percentage of FOXP3(+) cells, the origin of the induced cells and the functionality of these cells were assessed. Results Probiotic strains differ in their capacity to induce regulatory T cells. FOXP3(+) cells were induced from CD25(-) cells and were able to suppress effector T cells. Naturally occurring regulatory T cells were not affected by co-culture with lactobacilli. IL-10 concentrations found in the supernatant showed a trend towards the same differences between strains. Blockade of IL-10 did not influence the up-regulation of FOXP3. No differences between lactic acid bacteria were found in IL-17, IFN-gamma or IL-13.
  
  
  CONCLUSIONS
  Some probiotic strains are potent inducers of regulatory cells, while others are not. The clear differences between strains imply that an in vitro characterization of probiotic strains before application is recommended.
authors.affiliation: The Department of Pediatric Immunology, University Medical Centre Utrecht, Wilhemina Children's Hospital, Utrecht, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: de Roock
authors.forename: M
authors.initials: M
authors.lastname: van Elk
authors.forename: M E A
authors.initials: ME
authors.lastname: van Dijk
authors.forename: H M
authors.initials: HM
authors.lastname: Timmerman
authors.forename: G T
authors.initials: GT
authors.lastname: Rijkers
authors.forename: B J
authors.initials: BJ
authors.lastname: Prakken
authors.forename: M O
authors.initials: MO
authors.lastname: Hoekstra
authors.forename: I M
authors.initials: IM
authors.lastname: de Kleer
mesh_terms: D001644:Bifidobacterium / Q000276:immunology*; D049109:Cell Proliferation; D018920:Coculture Techniques; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D056747:Immunomodulation; D007371:Interferon-gamma / Q000096:biosynthesis; D018793:Interleukin-13 / Q000096:biosynthesis; D020381:Interleukin-17 / Q000096:biosynthesis; D007779:Lactobacillus acidophilus / Q000276:immunology*; D048191:Lactiplantibacillus plantarum / Q000276:immunology*; D007963:Leukocytes, Mononuclear; D019936:Probiotics / Q000008:administration & dosage*; D013045:Species Specificity; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D018793:Interleukin-13; D020381:Interleukin-17; D007371:Interferon-gamma