title: Differential modulation of innate immunity in vitro by probiotic strains of Lactobacillus gasseri.
abstract: BACKGROUND
  Probiotics species appear to differentially regulate the intestinal immune response. Moreover, we have shown that different immune-modulatory abilities can be found among probiotic strains belonging to the same species. In this study, we further addressed this issue while studying L. gasseri, a species that induces relevant immune activities in human patients.
  
  
  RESULTS
  We determined the ability of two strains of L. gasseri, OLL2809 and L13-Ia, to alter cell surface antigen expression, cytokine production and nuclear erythroid 2-related factor 2 (Nrf2)-mediated cytoprotection in murine bone marrow-derived dendritic cells (DCs) and MODE-K cells, which represent an enterocyte model. Differential effects of L. gasseri strains were observed on the expression of surface markers in mature DCs; nevertheless, both strains dramatically induced production of IL-12, TNF-α and IL-10. Distinctive responses to OLL2809 and L13-Ia were also shown in MODE-K cells by analyzing the expression of MHC II molecules and the secretion of IL-6; however, both L. gasseri strains raised intracellular glutathione. Treatment of immature DCs with culture medium from MODE-K monolayers improved cytoprotection and modified the process of DC maturation by down-regulating the expression of co-stimulatory markers and by altering the cytokine profile. Notably, bacteria-conditioned MODE-K cell medium suppressed the expression of the examined cytokines, whereas cytoprotective defenses were significantly enhanced only in DCs exposed to OLL2809-conditioned medium. These effects were essentially mediated by secreted bacterial metabolites.
  
  
  CONCLUSIONS
  We have demonstrated that L. gasseri strains possess distinctive abilities to modulate in vitro DCs and enterocytes. In particular, our results highlight the potential of metabolites secreted by L. gasseri to influence enterocyte-DC crosstalk. Regulation of cellular mechanisms of innate immunity by selected probiotic strains may contribute to the beneficial effects of these bacteria in gut homeostasis.
authors.forename: Diomira
authors.initials: D
authors.lastname: Luongo
authors.forename: Junki
authors.initials: J
authors.lastname: Miyamoto
authors.forename: Paolo
authors.initials: P
authors.lastname: Bergamo
authors.forename: Filomena
authors.initials: F
authors.lastname: Nazzaro
authors.forename: Federico
authors.initials: F
authors.lastname: Baruzzi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Sashihara
authors.forename: Soichi
authors.initials: S
authors.lastname: Tanabe
authors.affiliation: Institute of Food Sciences, NRC, Avellino, Italy. mrossi@isa.cnr.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Rossi
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000382:microbiology; D020895:Enterocytes / Q000276:immunology / Q000382:microbiology; D007113:Immunity, Innate; D007155:Immunologic Factors / Q000494:pharmacology*; D007778:Lactobacillus / Q000276:immunology*; D051379:Mice; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D019936:Probiotics / Q000494:pharmacology*
chemical_list: D000954:Antigens, Surface; D016207:Cytokines; D007155:Immunologic Factors; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse